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https://www.tutorialspoint.com/modelling_and_simulation/modelling_and_simulation_quick_guide.htm | # Modelling & Simulation - Introduction
Modelling is the process of representing a model which includes its construction and working. This model is similar to a real system, which helps the analyst predict the effect of changes to the system. In other words, modelling is creating a model which represents a system including their properties. It is an act of building a model.
Simulation of a system is the operation of a model in terms of time or space, which helps analyze the performance of an existing or a proposed system. In other words, simulation is the process of using a model to study the performance of a system. It is an act of using a model for simulation.
## History of Simulation
The historical perspective of simulation is as enumerated in a chronological order.
• 1940 − A method named ‘Monte Carlo’ was developed by researchers (John von Neumann, Stanislaw Ulan, Edward Teller, Herman Kahn) and physicists working on a Manhattan project to study neutron scattering.
• 1960 − The first special-purpose simulation languages were developed, such as SIMSCRIPT by Harry Markowitz at the RAND Corporation.
• 1970 − During this period, research was initiated on mathematical foundations of simulation.
• 1980 − During this period, PC-based simulation software, graphical user interfaces and object-oriented programming were developed.
• 1990 − During this period, web-based simulation, fancy animated graphics, simulation-based optimization, Markov-chain Monte Carlo methods were developed.
## Developing Simulation Models
Simulation models consist of the following components: system entities, input variables, performance measures, and functional relationships. Following are the steps to develop a simulation model.
• Step 1 − Identify the problem with an existing system or set requirements of a proposed system.
• Step 2 − Design the problem while taking care of the existing system factors and limitations.
• Step 3 − Collect and start processing the system data, observing its performance and result.
• Step 4 − Develop the model using network diagrams and verify it using various verifications techniques.
• Step 5 − Validate the model by comparing its performance under various conditions with the real system.
• Step 6 − Create a document of the model for future use, which includes objectives, assumptions, input variables and performance in detail.
• Step 7 − Select an appropriate experimental design as per requirement.
• Step 8 − Induce experimental conditions on the model and observe the result.
## Performing Simulation Analysis
Following are the steps to perform simulation analysis.
• Step 1 − Prepare a problem statement.
• Step 2 − Choose input variables and create entities for the simulation process. There are two types of variables - decision variables and uncontrollable variables. Decision variables are controlled by the programmer, whereas uncontrollable variables are the random variables.
• Step 3 − Create constraints on the decision variables by assigning it to the simulation process.
• Step 4 − Determine the output variables.
• Step 5 − Collect data from the real-life system to input into the simulation.
• Step 6 − Develop a flowchart showing the progress of the simulation process.
• Step 7 − Choose an appropriate simulation software to run the model.
• Step 8 − Verify the simulation model by comparing its result with the real-time system.
• Step 9 − Perform an experiment on the model by changing the variable values to find the best solution.
• Step 10 − Finally, apply these results into the real-time system.
## Modelling & Simulation ─ Advantages
Following are the advantages of using Modelling and Simulation −
• Easy to understand − Allows to understand how the system really operates without working on real-time systems.
• Easy to test − Allows to make changes into the system and their effect on the output without working on real-time systems.
• Easy to upgrade − Allows to determine the system requirements by applying different configurations.
• Easy to identifying constraints − Allows to perform bottleneck analysis that causes delay in the work process, information, etc.
• Easy to diagnose problems − Certain systems are so complex that it is not easy to understand their interaction at a time. However, Modelling & Simulation allows to understand all the interactions and analyze their effect. Additionally, new policies, operations, and procedures can be explored without affecting the real system.
## Modelling & Simulation ─ Disadvantages
Following are the disadvantages of using Modelling and Simulation −
• Designing a model is an art which requires domain knowledge, training and experience.
• Operations are performed on the system using random number, hence difficult to predict the result.
• Simulation requires manpower and it is a time-consuming process.
• Simulation results are difficult to translate. It requires experts to understand.
• Simulation process is expensive.
## Modelling & Simulation ─ Application Areas
Modelling & Simulation can be applied to the following areas − Military applications, training & support, designing semiconductors, telecommunications, civil engineering designs & presentations, and E-business models.
Additionally, it is used to study the internal structure of a complex system such as the biological system. It is used while optimizing the system design such as routing algorithm, assembly line, etc. It is used to test new designs and policies. It is used to verify analytic solutions.
# Concepts & Classification
In this chapter, we will discuss various concepts and classification of Modelling.
## Models & Events
Following are the basic concepts of Modelling & Simulation.
• Object is an entity which exists in the real world to study the behavior of a model.
• Base Model is a hypothetical explanation of object properties and its behavior, which is valid across the model.
• System is the articulate object under definite conditions, which exists in the real world.
• Experimental Frame is used to study a system in the real world, such as experimental conditions, aspects, objectives, etc. Basic Experimental Frame consists of two sets of variables − the Frame Input Variables & the Frame Output Variables, which matches the system or model terminals. The Frame input variable is responsible for matching the inputs applied to the system or a model. The Frame output variable is responsible for matching the output values to the system or a model.
• Lumped Model is an exact explanation of a system which follows the specified conditions of a given Experimental Frame.
• Verification is the process of comparing two or more items to ensure their accuracy. In Modelling & Simulation, verification can be done by comparing the consistency of a simulation program and the lumped model to ensure their performance. There are various ways to perform validation process, which we will cover in a separate chapter.
• Validation is the process of comparing two results. In Modelling & Simulation, validation is performed by comparing experiment measurements with the simulation results within the context of an Experimental Frame. The model is invalid, if the results mismatch. There are various ways to perform validation process, which we will cover in separate chapter.
## System State Variables
The system state variables are a set of data, required to define the internal process within the system at a given point of time.
• In a discrete-event model, the system state variables remain constant over intervals of time and the values change at defined points called event times.
• In continuous-event model, the system state variables are defined by differential equation results whose value changes continuously over time.
Following are some of the system state variables −
• Entities & Attributes − An entity represents an object whose value can be static or dynamic, depending upon the process with other entities. Attributes are the local values used by the entity.
• Resources − A resource is an entity that provides service to one or more dynamic entities at a time. The dynamic entity can request one or more units of a resource; if accepted then the entity can use the resource and release when completed. If rejected, the entity can join a queue.
• Lists − Lists are used to represent the queues used by the entities and resources. There are various possibilities of queues such as LIFO, FIFO, etc. depending upon the process.
• Delay − It is an indefinite duration that is caused by some combination of system conditions.
## Classification of Models
A system can be classified into the following categories.
• Discrete-Event Simulation Model − In this model, the state variable values change only at some discrete points in time where the events occur. Events will only occur at the defined activity time and delays.
• Stochastic vs. Deterministic Systems − Stochastic systems are not affected by randomness and their output is not a random variable, whereas deterministic systems are affected by randomness and their output is a random variable.
• Static vs. Dynamic Simulation − Static simulation include models which are not affected with time. For example: Monte Carlo Model. Dynamic Simulation include models which are affected with time.
• Discrete vs. Continuous Systems − Discrete system is affected by the state variable changes at a discrete point of time. Its behavior is depicted in the following graphical representation.
Continuous system is affected by the state variable, which changes continuously as a function with time. Its behavior is depicted in the following graphical representation.
## Modelling Process
Modelling process includes the following steps.
Step 1 − Examine the problem. In this stage, we must understand the problem and choose its classification accordingly, such as deterministic or stochastic.
Step 2 − Design a model. In this stage, we have to perform the following simple tasks which help us design a model −
• Collect data as per the system behavior and future requirements.
• Analyze the system features, its assumptions and necessary actions to be taken to make the model successful.
• Determine the variable names, functions, its units, relationships, and their applications used in the model.
• Solve the model using a suitable technique and verify the result using verification methods. Next, validate the result.
• Prepare a report which includes results, interpretations, conclusion, and suggestions.
Step 3 − Provide recommendations after completing the entire process related to the model. It includes investment, resources, algorithms, techniques, etc.
# Verification & Validation
One of the real problems that the simulation analyst faces is to validate the model. The simulation model is valid only if the model is an accurate representation of the actual system, else it is invalid.
Validation and verification are the two steps in any simulation project to validate a model.
• Validation is the process of comparing two results. In this process, we need to compare the representation of a conceptual model to the real system. If the comparison is true, then it is valid, else invalid.
• Verification is the process of comparing two or more results to ensure its accuracy. In this process, we have to compare the model’s implementation and its associated data with the developer's conceptual description and specifications.
## Verification & Validation Techniques
There are various techniques used to perform Verification & Validation of Simulation Model. Following are some of the common techniques −
### Techniques to Perform Verification of Simulation Model
Following are the ways to perform verification of simulation model −
• By using programming skills to write and debug the program in sub-programs.
• By using “Structured Walk-through” policy in which more than one person is to read the program.
• By tracing the intermediate results and comparing them with observed outcomes.
• By checking the simulation model output using various input combinations.
• By comparing final simulation result with analytic results.
### Techniques to Perform Validation of Simulation Model
Step 1 − Design a model with high validity. This can be achieved using the following steps −
• The model must be discussed with the system experts while designing.
• The model must interact with the client throughout the process.
• The output must supervised by system experts.
Step 2 − Test the model at assumptions data. This can be achieved by applying the assumption data into the model and testing it quantitatively. Sensitive analysis can also be performed to observe the effect of change in the result when significant changes are made in the input data.
Step 3 − Determine the representative output of the Simulation model. This can be achieved using the following steps −
• Determine how close is the simulation output with the real system output.
• Comparison can be performed using the Turing Test. It presents the data in the system format, which can be explained by experts only.
• Statistical method can be used for compare the model output with the real system output.
## Model Data Comparison with Real Data
After model development, we have to perform comparison of its output data with real system data. Following are the two approaches to perform this comparison.
### Validating the Existing System
In this approach, we use real-world inputs of the model to compare its output with that of the real-world inputs of the real system. This process of validation is straightforward, however, it may present some difficulties when carried out, such as if the output is to be compared to average length, waiting time, idle time, etc. it can be compared using statistical tests and hypothesis testing. Some of the statistical tests are chi-square test, Kolmogorov-Smirnov test, Cramer-von Mises test, and the Moments test.
### Validating the First Time Model
Consider we have to describe a proposed system which doesn’t exist at the present nor has existed in the past. Therefore, there is no historical data available to compare its performance with. Hence, we have to use a hypothetical system based on assumptions. Following useful pointers will help in making it efficient.
• Subsystem Validity − A model itself may not have any existing system to compare it with, but it may consist of a known subsystem. Each of that validity can be tested separately.
• Internal Validity − A model with high degree of internal variance will be rejected as a stochastic system with high variance due to its internal processes will hide the changes in the output due to input changes.
• Sensitivity Analysis − It provides the information about the sensitive parameter in the system to which we need to pay higher attention.
• Face Validity − When the model performs on opposite logics, then it should be rejected even if it behaves like the real system.
# Discrete System Simulation
In discrete systems, the changes in the system state are discontinuous and each change in the state of the system is called an event. The model used in a discrete system simulation has a set of numbers to represent the state of the system, called as a state descriptor. In this chapter, we will also learn about queuing simulation, which is a very important aspect in discrete event simulation along with simulation of time-sharing system.
Following is the graphical representation of the behavior of a discrete system simulation.
## Discrete Event Simulation ─ Key Features
Discrete event simulation is generally carried out by a software designed in high level programming languages such as Pascal, C++, or any specialized simulation language. Following are the five key features −
• Entities − These are the representation of real elements like the parts of machines.
• Relationships − It means to link entities together.
• Simulation Executive − It is responsible for controlling the advance time and executing discrete events.
• Random Number Generator − It helps to simulate different data coming into the simulation model.
• Results & Statistics − It validates the model and provides its performance measures.
### Time Graph Representation
Every system depends on a time parameter. In a graphical representation it is referred to as clock time or time counter and initially it is set to zero. Time is updated based on the following two factors −
• Time Slicing − It is the time defined by a model for each event until the absence of any event.
• Next Event − It is the event defined by the model for the next event to be executed instead of a time interval. It is more efficient than Time Slicing.
## Simulation of a Queuing System
A queue is the combination of all entities in the system being served and those waiting for their turn.
### Parameters
Following is the list of parameters used in the Queuing System.
Symbol Description
λ Denotes the arrival rate which is the number of arrivals per second
Ts Denotes the mean service time for each arrival excluding the waiting time in the queue
σTs Denotes the standard deviation of service time
ρ Denotes the server time utilization, both when it was idle and busy
u Denotes traffic intensity
r Denotes the mean of items in the system
R Denotes the total number of items in the system
Tr Denotes the mean time of an item in the system
TR Denotes the total time of an item in the system
σr Denotes the standard deviation of r
σTr Denotes the standard deviation of Tr
w Denotes the mean number of items waiting in the queue
σw Denotes the standard deviation of w
Tw Denotes the mean waiting time of all items
Td Denotes the mean waiting time of the items waiting in the queue
N Denotes the number of servers in a system
mx(y) Denotes the yth percentile which means the value of y below which x occurs y percent of the time
### Single Server Queue
This is the simplest queuing system as represented in the following figure. The central element of the system is a server, which provides service to the connected devices or items. Items request to the system to be served, if the server is idle. Then, it is served immediately, else it joins a waiting queue. After the task is completed by the server, the item departs.
### Multi Server Queue
As the name suggests, the system consists of multiple servers and a common queue for all items. When any item requests for the server, it is allocated if at-least one server is available. Else the queue begins to start until the server is free. In this system, we assume that all servers are identical, i.e. there is no difference which server is chosen for which item.
There is an exception of utilization. Let N be the identical servers, then ρ is the utilization of each server. Consider to be the utilization of the entire system; then the maximum utilization is N*100%, and the maximum input rate is −
$λmax = \frac{\text{N}}{\text{T}s}$
### Queuing Relationships
The following table shows some basic queuing relationships.
General Terms Single Server Multi server
r = λTr Little's formula ρ = λTs ρ = λTs/N
w = λTw Little's formula r = w + ρ u = λTs = ρN
Tr = Tw + Ts r = w + Nρ
## Simulation of Time-Sharing System
Time-sharing system is designed in such a manner that each user uses a small portion of time shared on a system, which results in multiple users sharing the system simultaneously. The switching of each user is so rapid that each user feels like using their own system. It is based on the concept of CPU scheduling and multi-programming where multiple resources can be utilized effectively by executing multiple jobs simultaneously on a system.
Example − SimOS Simulation System.
It is designed by Stanford University to study the complex computer hardware designs, to analyze application performance, and to study the operating systems. SimOS contains software simulation of all the hardware components of the modern computer systems, i.e. processors, Memory Management Units (MMU), caches, etc.
# Modelling & Simulation - Continuous
A continuous system is one in which important activities of the system completes smoothly without any delay, i.e. no queue of events, no sorting of time simulation, etc. When a continuous system is modeled mathematically, its variables representing the attributes are controlled by continuous functions.
## What is Continuous Simulation?
Continuous simulation is a type of simulation in which state variables change continuously with respect to time. Following is the graphical representation of its behavior.
## Why Use Continuous Simulation?
We have to use continuous simulation as it depends on differential equation of various parameters associated with the system and their estimated results known to us.
## Application Areas
Continuous simulation is used in the following sectors. In civil engineering for the construction of dam embankment and tunnel constructions. In military applications for simulation of missile trajectory, simulation of fighter aircraft training, and designing & testing of intelligent controller for underwater vehicles.
In logistics for designing of toll plaza, passenger flow analysis at the airport terminal, and proactive flight schedule evaluation. In business development for product development planning, staff management planning, and market study analysis.
# Monte Carlo Simulation
Monte Carlo simulation is a computerized mathematical technique to generate random sample data based on some known distribution for numerical experiments. This method is applied to risk quantitative analysis and decision making problems. This method is used by the professionals of various profiles such as finance, project management, energy, manufacturing, engineering, research & development, insurance, oil & gas, transportation, etc.
This method was first used by scientists working on the atom bomb in 1940. This method can be used in those situations where we need to make an estimate and uncertain decisions such as weather forecast predictions.
## Monte Carlo Simulation ─ Important Characteristics
Following are the three important characteristics of Monte-Carlo method −
• Its output must generate random samples.
• Its input distribution must be known.
• Its result must be known while performing an experiment.
## Monte Carlo Simulation ─ Advantages
• Easy to implement.
• Provides statistical sampling for numerical experiments using the computer.
• Provides approximate solution to mathematical problems.
• Can be used for both stochastic and deterministic problems.
## Monte Carlo Simulation ─ Disadvantages
• Time consuming as there is a need to generate large number of sampling to get the desired output.
• The results of this method are only the approximation of true values, not the exact.
## Monte Carlo Simulation Method ─ Flow Diagram
The following illustration shows a generalized flowchart of Monte Carlo simulation.
# Modelling & Simulation - Database
The objective of the database in Modelling & Simulation is to provide data representation and its relationship for analysis and testing purposes. The first data model was introduced in 1980 by Edgar Codd. Following were the salient features of the model.
• Database is the collection of different data objects that defines the information and their relationships.
• Rules are for defining the constraints on data in the objects.
• Operations can be applied to objects for retrieving information.
Initially, Data Modelling was based on the concept of entities & relationships in which the entities are types of information of data, and relationships represent the associations between the entities.
The latest concept for data modeling is the object-oriented design in which entities are represented as classes, which are used as templates in computer programming. A class having its name, attributes, constraints, and relationships with objects of other classes.
Its basic representation looks like −
## Data Representation
### Data Representation for Events
A simulation event has its attributes such as the event name and its associated time information. It represents the execution of a provided simulation using a set of input data associated with the input file parameter and provides its result as a set of output data, stored in multiple files associated with data files.
### Data Representation for Input Files
Every simulation process requires a different set of input data and its associated parameter values, which are represented in the input data file. The input file is associated with the software which processes the simulation. The data model represents the referenced files by an association with a data file.
### Data Representation for Output Files
When the simulation process is completed, it produces various output files and each output file is represented as a data file. Each file has its name, description and a universal factor. A data file is classified into two files. The first file contains the numerical values and the second file contains the descriptive information for the contents of the numerical file.
## Neural Networks in Modelling & Simulation
Neural network is the branch of artificial intelligence. Neural network is a network of many processors named as units, each unit having its small local memory. Each unit is connected by unidirectional communication channels named as connections, which carry the numeric data. Each unit works only on their local data and on the inputs they receive from the connections.
### History
The historical perspective of simulation is as enumerated in a chronological order.
The first neural model was developed in 1940 by McCulloch & Pitts.
In 1949, Donald Hebb wrote a book “The Organization of Behavior”, which pointed to the concept of neurons.
In 1950, with the computers being advanced, it became possible to make a model on these theories. It was done by IBM research laboratories. However, the effort failed and later attempts were successful.
In 1959, Bernard Widrow and Marcian Hoff, developed models called ADALINE and MADALINE. These models have Multiple ADAptive LINear Elements. MADALINE was the first neural network to be applied to a real-world problem.
In 1962, the perceptron model was developed by Rosenblatt, having the ability to solve simple pattern classification problems.
In 1969, Minsky & Papert provided mathematical proof of the limitations of the perceptron model in computation. It was said that the perceptron model cannot solve X-OR problem. Such drawbacks led to the temporary decline of the neural networks.
In 1982, John Hopfield of Caltech presented his ideas on paper to the National Academy of Sciences to create machines using bidirectional lines. Previously, unidirectional lines were used.
When traditional artificial intelligence techniques involving symbolic methods failed, then arises the need to use neural networks. Neural networks have its massive parallelism techniques, which provide the computing power needed to solve such problems.
### Application Areas
Neural network can be used in speech synthesis machines, for pattern recognition, to detect diagnostic problems, in robotic control boards and medical equipments.
## Fuzzy Set in Modelling & Simulation
As discussed earlier, each process of continuous simulation depends on differential equations and their parameters such as a, b, c, d > 0. Generally, point estimates are calculated and used in the model. However, sometimes these estimates are uncertain so we need fuzzy numbers in differential equations, which provide the estimates of the unknown parameters.
### What is a Fuzzy Set?
In a classical set, an element is either a member of the set or not. Fuzzy sets are defined in terms of classical sets X as −
A = {(x,μA(x))| x ∈ X}
Case 1 − The function μA(x) has the following properties −
∀x ∈ X μA(x) ≥ 0
sup x ∈ X {μA(x)} = 1
Case 2 − Let fuzzy set B be defined as A = {(3, 0.3), (4, 0.7), (5, 1), (6, 0.4)}, then its standard fuzzy notation is written as A = {0.3/3, 0.7/4, 1/5, 0.4/6}
Any value with a membership grade of zero doesn’t appear in the expression of the set.
Case 3 − Relationship between fuzzy set and classical crisp set.
The following figure depicts the relationship between a fuzzy set and a classical crisp set. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7593919038772583, "perplexity": 1065.2375406237365}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-34/segments/1596439738913.60/warc/CC-MAIN-20200812171125-20200812201125-00115.warc.gz"} |
http://jsxgraph.uni-bayreuth.de/wp/2018-05-30-release-of-version-0.99.7/ | # Release of 0.99.7
## Major new release
Here it is: The much awaited version 0.99.7 of JSXGraph has been released! There are a few new elements and many new features. We are especially happy that we received many requests for new features from active JSXGraph users.
### Improvements and bug fixes
• In Chrome and Edge on Windows point events are used.
• JSXGraph is now compatible to require.js. This allows a seamless integration into learning management system moodle via the JSXGraph filter.
• MediaWiki plug-in works again.
• Improved support for MathJax.
• Some elements can be constructed by supplying an original element and an arbitrary transformation as parent elements: these are point, line, circle, polygon, arc, sector, angle. The resulting elements are point, line, polygon if the input elements were point, line, polygon, resp. The output element is a conic in for circles and curves for arc, sector and angle.
• New default values for pinch / zoom: for zoom shift+wheel is set to true by default now.
• Improved output from Dump.toJavaScript()
• Polygon reflection now creates vertex names A', B', …
• Enable transformation “rotate” of type [angle, [x,y]].
• The events hit and mousehit work again.
• The attribute hasInnerPoints is available for all arc types: arc, sector, angle.
• New curve attributes recursionDepthLow and recursionDepthHigh allow user controlled plot quality.
• The inequality element takes now also the functiongraph element as input.
• Screenshot button.
### Compatibility
• The attribute JXG.Option.semicirclearc.midpoint has been renamed into JXG.Option.semicirclearc.center.
We thank all contributors which supplied patches, bug reports and suggestions for improvements.
For a full list of all changes see the CHANGELOG.
Enjoy, Alfred | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.19655649363994598, "perplexity": 11316.046542763688}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-04/segments/1547583831770.96/warc/CC-MAIN-20190122074945-20190122100945-00340.warc.gz"} |
https://www.physicsforums.com/threads/simple-harmonic-motion-finding-the-distance-traveled-by-the-vibrating-object.86465/ | # Simple Harmonic Motion-Finding the distance traveled by the vibrating object?
• #1
50
0
Simple Harmonic Motion-Finding the distance traveled by the vibrating object???
Hi, I would really like to know if my solution to the following question is correct, I would really really really appreciate it.
A hanging spring stretches by 35cm when an object of mass 450g is hung on it at rest. In this situation, we define its position as x=0. The object is pulled down an additional 18cm and released from rest to oscillate without friction. What is its position x at a time 84.4s later?
Find the distance traveled by the vibrating object.
Well, by using the equation -ky-mg=0 (at rest) I derived the equation
y=-mg/k. So i replaced y with 35 cm and m with 0.45kg in order to find k.
With k, i set the equation: x(t)= Acos(wt+c) c=phase constant w=angular frequency
and since this started at rest, there is no phase constant, and amplitude is 18cm so i made the equation
x(t)=0.18cos(5.29t)
then i replace the t with 84.4. Is this right?
And how do i go about finding the "distance traveled by the vibrating object"?
Thanks!
Last edited:
• #2
574
1
Just calculate how many oscillations it goes through and multiply the amplitude with that.
• #3
Fermat
Homework Helper
872
1
That should be the double-amplitude.
• #4
andrevdh
Homework Helper
2,128
116
I think you got it right if we agree that positive x is measured downwards.
For the distance travelled you can try T = 2π/ω for the period of the oscillation. Dividing the time by the period wil therefore give the amount of full oscillations (I get 71) plus a bit (0.0790 of an oscillation which converts to a time of 0.0938s). For every full oscillation the mass covers four times the amplitude. Using your equation and the amount of leftover time you can calculate the additional disance it travelled.
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2K | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9154012799263, "perplexity": 1553.0400304631817}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243991428.43/warc/CC-MAIN-20210514152803-20210514182803-00148.warc.gz"} |
http://matdl.org/matdlwiki/index.php/softmatter:FENE_Spring | # softmatter:FENE Spring
Finitely extensible non-linear elastic (FENE) springs are often used in bead spring models of polymeric materials.
$U_{FENE} = \begin{cases} -0.5kR_{0}^2ln\left[1-\left(\frac{r}{R_{0}}\right )^2 \right ] & r
where r is the distance between neighboring beads, k is the energy parameter and R0 is the maximum length of the spring. Typically the values f k = 30 and R0 = 1.5σ are used in simulation, where σ is the diameter of the particle. These values ensure relatively stiff bonds and prevent unphysical chain crossings.
In many simulation packages particle-particle interactions between bonded pairs are not calculated, and thus to avoid particles sitting on top of each other, the Weeks-Chandler-Andersen is often included in the spring potential calculation:
$U_{FENE} = \begin{cases} U_{WCA} + -0.5kR_{0}^2ln\left[1-\left(\frac{r}{R_{0}}\right )^2 \right ] & r
"U"WCA is a Weeks-Chandler-Anderson volume-excluding repulsive force that balances the purely attractive logarithmic term.
## References
• G. S. Grest and K. Kremer, "Molecular dynamics simulation for polymers in the presence of a heat bath," Phys. Rev. A., 33, 3628-3631, (1986) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 2, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8455204367637634, "perplexity": 12475.70722779525}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657138770.35/warc/CC-MAIN-20140914011218-00030-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://andburch.github.io/constant_scales/ | # Setting scales constant across multiple plots (ggplot2)
So you have a bunch of plots and they all have color scales with different limits and you realize that eyeballing the numbers trying to normalize the colors in your head is a bad way to compare them, huh?
You could manually review each plot, then manually set the limits of each color scale so that they encompass the same set, and then hope you never change the data in a way that would invalidate those limits, but that’s dumb, huh?
Come along and find out how to set non-position scales to be constant across multiple plots!
## The problem
Let’s say you’ve got two plots, p1 and p2. Side by side, they look like this:
The colors lie! They lie to us!
It would be great if the colors meant the same thing across plots, but we can see that the yellow in p2 corresponds to a much higher value than in p1. This can be misleading if you’re comparing the two plots visually.
Those “fat cats”” at stackexchange might tell you to do something like:
where you manually set the limits of both plots to encompass all the values in each. You can do this, for sure.
If you’re a baby.
But seriously, if you’re doing this for a lot of different plots, or if you want to automate it, or the data has changed, then this is a pretty fault-intolerant, slow process.
## My hacky solution
After spending a few hours bumbling around the undocumented guts of the ggplot2 code, I was able to put together a pretty nifty solution. I’ve broken it down to three steps / functions.
NOTE: my code only works for continuous scales!
If you just want the function without a walk-through of what it does, jump down to the gist in the source code section at the end of this post. Be wary though, it’s relatively untested!
### 1: Extract the range of a plot
In order to set the limit of a scale so that it encompasses the range of the union of the plots in question, you have to be able to access their ranges. ggplot2 saves a lot of the calculation-y stuff (like, calculating data for stats_* objects) right until the moment it’s plotted, so you have to make it do that with ggplot_build() (or at least, that’s how I managed it).
Here’s the function that I wrote; given a plot and a scale that you want to eventually apply (e.g., scale_viridis_fill_c("z")), this gets the range of values that the plot uses for the aesthetic of that scale:
Voilà:
## 2: Get a single shared scale
Now that we can get a single range from a single plot, let’s get the range of the union of all of the ranges for a bunch of plots.
This function takes in any number of plots and the scale you want to use for all of these plots, and returns that scale with the right limits.
You can use it like this:
Note that you can supply any additional arguments you want for the scale in that scale’s call (e.g., oob, guide, expand, etc.).
While you could take the scale output of get_shared_scale() and then add it to those plots manually,1 that’s still too much work for me.
## 3: Editing plots ‘in place’
I wanted to be able to make the plots, run a single function that sets the shared scale of all the plots, and then just have those plots be edited, without me having to manually add in a new scale or add extra lines to re-edit those plots.
This next function is probably a little more “dangerous” than the previous two functions, but if you use it in the right circumstances it’s mega helpful. If you’ve assigned the plots to variables in the environment you call set_scale_union() in, it will call get_shared_scale(), get the shared scale, add it to each of the previously-assigned plots, and re-assign their names to the new plots.
So after we call:
When we go to plot p1 and p2, we find that they now have the right scales!
Now the colors mean the same things across plots! Your graduate advisor sheds a single tear of happiness.
## Source Code:
set_scales_constant.R
This is the code used in this post, but better because I included some checks to make sure that the scales being used are all continuous scales. I didn’t include that in the examples above because I though they’d be distracting for newbies.
### Footnotes:
1. And I specifically made get_shared_scale() a separate function in case you do want to.
#### Tags:
R, ggplot2, plots, plotting, data visualization, recipes, scales,
Buy me a beer? Litecoin address: LaiZUuF4RY3PkC8VMFLu3YKvXob7ZGZ5o3 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3734382092952728, "perplexity": 909.4350416609974}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764499758.83/warc/CC-MAIN-20230129180008-20230129210008-00602.warc.gz"} |
http://chronos.msu.ru/en/updates/temporpublications/temporpublications-5/from-the-waveguided-gravity-to-the-periodic-waveguided-multiverse-as-united-solution-of-dark-energy-dark-matter-susy-mysteries | Поиск по сайту: .ya-page_js_yes .ya-site-form_inited_no { display: none; }
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From the waveguided gravity to the periodic waveguided Multiverse as united solution of dark energy & dark matter & SUSY – mysteries
Грибов Ю.А. (Gribov Y.A.) From the waveguided gravity to the periodic waveguided Multiverse as united solution of dark energy & dark matter & SUSY – mysteries // http://vixra.org, 2013. 91 p.
Категории: Исследование, Авторский указатель, Время в математике, Математика
## From the waveguided gravity to the periodic waveguided Multiverse as united solution of dark energy & dark matter & SUSY – mysteries 0.0/5 rating (0 votes)/*<![CDATA[*/jQuery(function($) {$('#c4aab8cf-bd11-4dce-bfe9-a2fdc567666a-5ed274a041fb3').ElementRating({ url: '/en/updates?task=callelement&format=raw&item_id=7868&element=c4aab8cf-bd11-4dce-bfe9-a2fdc567666a' }); });/*]]>*/
### Abstract
The quasi-classical concept of Periodic Waveguided Multiverse (PWM) is proposed. This periodic 4D-hyperstructure has substantial theoretical and observational-cosmological confirmations because it unites and refines the basic physical laws (SR&GR&QM, etc), inseparably emergent in the waveguided dynamics and gives the multiversal explanation of dominating observational DE&DM-mysteries (including predicted and observed two-component DM) – interconnected cosmological evidences for the PWM-existence. The PWM concept can be soon tested in a laboratory: (a) it predicts antigravity in the anti-hydrogen gravity test at CERN; (b) predicts direct-atypical DM&ANTIMATTER annihilation with radiation of one – visible-detectable and one – dark-undetectable gamma quantum - as basis for the proposed selective direct DM-detection. The PWM-foundation is surprisingly compact – it is based on two penetrating Planckian & Einsteinian ideas: I - photon-quanta and II - principle of equality of our 3D-spatial dimensions (x,y,z) with an additional extra-dimension L, realizing so expanded - automatically Euclidean 4D-space (x,y,z,L). We have applied these basic physical insights in frames of classical-Maxwellian-like 3D-waveguides Wn [x,y,z,nL0<L<(n+1)L0], realizing an endless periodic chain of physically identical parallel W2n/W2n+1 Universes/Antiuniverses (n = ±1, ±2, ±3,…, ±), filling this global space (x,y,z,L), where Lo=λel.Compton ≈ 1 picometer, determined by the lightest (electron) rest mass particle. This structure discloses the waveguided co-emergence of the (1) pure C4-dynamical quantized-gapped - “elementary” rest mass; (2) the SR & QM & Newtonian-like, periodic matter/antimatter antigravity; (3) the CPTPWM symmetry between particles/antiparticles, with the gravity “charge” symmetry (4) the modified Equivalence Principle EPPWM; (5) singularity-less Diracian-like fermions/antifermions and GR-like black/white holes free of singularity; (6) opens physical possibility of the nongravitating – chargeless, very robust scalar (Cooper-like) composites - electron-positron-cells, hidden in their globally coherent superfluid vacuum condensate at low T – as Diracian-like, equilibrium superfluid sea/anti-sea. Common electron/positron pairs arise as elementary defects – Diracian holes/antiholes in this vacuum, disclosing the composite-SUSY nature and explaining why cosmological constant is zero; (7) the global C3-dynamical pseudo-Euclidean 4D-spacetime concept by Minkowski is rethought and reformulated on the 3D-waveguided, 4D-Euclidean physical basis, where global linear intervals (→→→→→C3tMink.) → (↗↘↗↘↗↘↗↘↗↘C4tPWM) -waveguided-polygonal intervals - C4t-parameterizations of the polygonal rest mass particle dynamics, disclosing the waveguided/wave-optical (Huygens-Fermat’s) sense of the mechanical Lagrangian and Hamilton's principle of the least action.
You have no rights to post comments | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3845670223236084, "perplexity": 19789.510115812784}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347409337.38/warc/CC-MAIN-20200530133926-20200530163926-00486.warc.gz"} |
https://earthscience.stackexchange.com/questions/350/how-are-subsurface-wave-speeds-determined-without-subsurface-sensors/351 | # How are subsurface wave speeds determined without subsurface sensors?
This is something I've never quite understood from a geology class I took years ago:
Consider the following picture (courtesy of wikipedia)
Obviously, we can't possibly have sensors deep in the mantle (or core). So, how exactly are these wave speeds determined?
This is a good question, and the basic answer is earthquake seismology. To answer this question, lets accept a fact: Waves propagate through the least time pathway, and not the least distance path. This property of physics is known as Fermat's principle.
When an Earthquake occurs, energy propagates similar to a ripple of water, and spreads. Each point on this ripple can be modeled as a ray, each following its least time path through the Earth. As these rays propagate, they reflect and refract off heterogeneities inside the earth. These reflections are important: we can detect these reflections using surface seismometers. Using multiple seismometers, and the location of the source (earthquake), we can calculate the "lag" between when the closest seismometer detects the earthquake and the others(further from the source). This lag time can be used as a proxy for the depth of the reflected wave's heterogeneity. Using how deep this reflection originates, we can then figure out the least time path of the wave in terms of actual distance. Velocity is just distance over time, even for seismic waves. So since we have the distance traveled by the wave, and the time the wave took to get to the receiver, we can complete the equation (distance/time).
In actual practice, this process is far more complex, as you have to look for many different waveforms:
The picture above illustrates an earthquake sending waveforms through the earth. The SKS wave is a shear wave that refracts into the liquid outer core, turns into a compressional wave (since shear waves cannot propagate through liquid), and then is converted again to a shear wave as it enters the mantle and goes to the surface. A trained seismologist looks at the readings from seismometers to tease out specific waves, which we know the properties of, to determine properties of the planet's interior. The speeds of these waves are highly dependent on the assumed densities and other rock properties of the crust, mantle, and core.
• Another reason this is such a hard problem is that we don't know the precise 3D location or timing of an earthquake without a prior estimate of velocity. Hence the need for tomography. – kwinkunks Apr 19 '14 at 14:25
• yes, its a lot of modeling, how we(people) got good at it seems to be pure brute force. – Neo Apr 19 '14 at 16:47
• Maybe the previous comments address this, but regarding "So since we have the distance traveled by the wave, and the time the wave took to get to the receiver, we can complete the equation (distance/time)." How do we know the distance traveled by the wave? More specifically, how do we know where the wave signal we receive from an earth quake originates? – cr0 Apr 13 '18 at 1:49
Tomography! In essence, we guess some velocities, compute the arrival times our guess implies, compare them with actual arrival times, tweak our answer, and repeat. Seismic tomography is an ill-posed, ill-conditioned inverse problem, and one upshot of this is that the solutions are non-unique — there are infinitely many answers! We have to choose one (or, better, many), that are compatible with what we think we know about the earth. Compare this with a medical computed tomography (CT) scan, in which there are far fewer unknowns.
In the shallow subsurface, down to about 5–10 km in most basins, we have the added advantage of measured well logs, specifically sonic logs, which measure the slowness (1/velocity) of ultrasound. As in all inverse problems, extra information constrains the solution greatly. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8687693476676941, "perplexity": 802.925755604851}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579251778272.69/warc/CC-MAIN-20200128122813-20200128152813-00171.warc.gz"} |
https://chemistry.stackexchange.com/questions/67073/why-is-carbon-dioxide-considered-a-lewis-acid/67080 | # Why is carbon dioxide considered a Lewis acid?
$\ce{CO2}$ is considered a Lewis acid. How it is an acid? According to Lewis: “species that accept an electron pair are acids”. But $\ce{CO2}$ can't accept electron pairs because oxygen and carbon both are electron sufficient (have complete octets). If the reason is within a lone pair of electrons on oxygen then ammonia ($\ce{NH3}$), which also has a lone pair of electrons, should be acidic, too. But ammonia basic in nature.
So why can carbon dioxide be considered a Lewis acid?
• $\ce{CO2 +H2O <--> H2CO3}$ so the oxygen of the water molecule donates the electrons and is the Lewis Base. Thus $\ce{CO2}$ must be the Lewis acid. – MaxW Jan 25 '17 at 18:02
• MaxW That is just an experimental observation and gives no insight into why CO2 is a Lewis acid. – electronpusher Jan 25 '17 at 18:36
If you've learned how to draw resonance structures, they will help you greatly here (and in general). In the attached figure, 1 is the relevant resonance, implying the carbon in $\ce{CO2}$ is partially positive and therefore may be prone to accept electrons (see the resonance hybrid).
In theory, any Lewis base (electron-donor) can react with $\ce{CO2}$ (Lewis base abbreviated B in 2 & 3). We can draw the reaction mechanism using the charged resonance structure (2) or the neutral, most "stable" structure (3). In reality, these are not two discretely different forms but just "snapshots in time" of a true $\ce{CO2}$ molecule, so it doesn't really matter which structure we as humans choose to represent on paper.
I hope you can see how $\ce{CO2}$ is a Lewis acid because it is able to accept electrons. Although in the principal resonance structure you see all atoms have full octets of electrons, the double bonds can easily break, rearranging the electrons. If full octets prevented atoms from receiving electrons, a great percentage of all known reactions would not occur. The key is that the electrons in the octet must have an alternative place to go if new electrons are donated to the molecule (in this case, the electrons migrate to the $\ce{O}$ atom). In more advanced chemistry, we would say $\ce{O}$ acted as an electron sink in this process.
It is interesting to note that any $\ce{C=O}$ structure can react as a Lewis acid in exactly the way your $\ce{CO2}$ molecule did, and this reaction of the $\ce{C=O}$ group (known as a carbonyl functional group) is among the most important patterns in the biochemical reactions occuring in our bodies.
• This is an extension. Would you consider carbon dioxide to be a strong electrophile since two oxygens are "pulling" on the electron density of the carbon instead of only one oxygen in the typical carbonyl group? – Tan Yong Boon Aug 13 '17 at 7:00
• It's better to stick to relative comparisons like "CO2 is a stronger electrophile than benzaldehyde". This example is claimed here [chemicalforums.com/index.php?topic=51558.0], and should give you some idea of how strong of a Lewis base CO2 is. – electronpusher Aug 13 '17 at 7:23
You cannot adequately understand the Lewis acid theory with respect to main group elements if you only draw simple Lewis structures (which, per definition, should have complete octets on all main group elements) and then attempt to find electron pair acceptors. Well, to be perfectly honest, you might get lucky with boron compounds but the game will end there.
It is relatively clear to most people that metal cations can act as Lewis acids: they are positively charged because they lost at least one electron. They also have relatively low-lying orbitals (e.g. the one that lost an electron) with which the Lewis bases can interact. One has to apply more thought to molecules such as $\ce{CO2}$, though.
To analyse a molecule such as $\ce{CO2}$, you should start by thinking about the polarity of the bonds in question. The periodic table or whichever data page you wish to consult will tell us that oxygen is much more polar than carbon; therefore, the bonds are polarised towards oxygen. This can be exemplified by the partial charge formalism as shown below.
$$\ce{\overset{\delta -}{O}=\overset{\delta +}{C}=\overset{\delta -}{O}}\tag{1}$$
This first depiction already tells us that carbon is somewhat ‘electron-lacking’. While that in itself is not yet a proof of Lewis acidity, it is a strong hint. Diving deeper, one would have to consider the molecular orbitals of $\ce{CO2}$. There are two symmetry-equivalent but perpendicular π systems both populated by four electrons; and both can be seen as an allyl anion type of π system. Since it is wholly symmetric, we can draw the following three resonance structures (for clarification, the allyl anion $\ce{C3H5-}$, has also been included in the scheme).
$$\begin{array}{ccccc}\ce{O=C=O &<->& \overset{+}{O}#C-\overset{-}{O} &<->& O=\overset{+}{C}-\overset{-}{O}}\\ \ce{H2\overset{-}{C}-CH=CH2 &<->& H2C=CH-\overset{-}{C}H2 &<->& H2\overset{-}{C}-\overset{+}{C}H-\overset{-}{C}H2}\end{array}\tag{2}$$
In this depiction, I have chosen the left-hand double bond to belong to the perpendicular π system and the right-hand double bond to be the interesting one analogous to the allyl anion. Hence, there will always be one more bond on the left half of carbon dioxide than the allyl anion. The negative charge (i.e. lone pair) present on the leftmost allyl anion carbon corresponds to a lone pair of the leftmost oxygen in carbon dioxide; the lone pair is unmarked as per convention.
In these depictions we can observe a resonance structure wherein carbon dioxide’s carbon has a positive charge and thus an electron sextet. If you look at the actual orbitals in question, the two populated bonding orbitals (one may be called nonbonding) have a high oxygen contribution while the antibonding π3 orbital is a primarily carbon-centred one. This orbital is also the lowest unoccupied molecular orbital (LUMO) and thus the one we are interested in when determining Lewis acidity. We find that it is energetically low-lying and easily accessible and therefore Lewis bases (e.g. hydroxide, ammonia) can easily interact with it.
The Lewis acid-base reaction can also be guessed looking at the resonance structures. Because the Lewis base interacts with the antibonding π3 orbital, it will break one of the $\ce{C=O}$ double bonds leading to the following structure:
$$\ce{\color{cyan}{O}=C=O + \color{blue}{O}H- -> H\color{blue}{O}-C(=\color{cyan}{O})-\overset{-}{O}}\tag{3}$$
I have marked the oxygens in blue and cyan (and black) so they may be distinguished from another.
• I love your answer. However, I have a hunch you're going to lose him around "There are two symmetry-equivalent but perpendicular π systems both populated by four electrons; and both can be seen as an allyl anion type of π system." – electronpusher Jan 25 '17 at 21:16
• At the very least your answer certainly helped me see the the issue in a new light – electronpusher Jan 25 '17 at 21:20
• On a lot of these questions I have wondered if we need multiple levels of answers. So high school, undergraduate, graduate and research level answers. ;-) – MaxW Jan 25 '17 at 21:35 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7446815967559814, "perplexity": 1273.7470282398665}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570986705411.60/warc/CC-MAIN-20191020081806-20191020105306-00199.warc.gz"} |
http://electronics.stackexchange.com/questions/32841/how-do-i-treat-a-pmos-compared-to-an-nmos-in-small-signal-analysis | # How do I treat a PMOS compared to an NMOS in small-signal analysis?
What exhaustive list can I use to determine the differences between NMOS and PMOS devices when doing small-signal analysis?
Equivalently, what are the fundamental differences between NMOS and PMOS devices, and how do related terms (i.e. treshold voltage, which is either positive in NMOS and negative in PMOS, or positive in both but with reversed polarity in PMOS, affecting many formulas) differ between them?
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I hope that the answer will clear up questions like this. – Andres Riofrio May 28 '12 at 22:25
With equal respect. – Telaclavo May 28 '12 at 22:56
pMOS's $I_{SD}$ will be proportional to $V_{SG} - |V_T|$, where nMOS's $I_{DS}$ will be proportional to $V_{GS} - |V_T|$. Note that for the pMOS, you can flip SG and SD and still obtain the right values, as long as you use the absolute value of Vt. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8026395440101624, "perplexity": 1852.587888438929}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368706470197/warc/CC-MAIN-20130516121430-00097-ip-10-60-113-184.ec2.internal.warc.gz"} |
http://mathcentral.uregina.ca/QQ/database/QQ.09.15/h/diaz1.html | SEARCH HOME
Math Central Quandaries & Queries
Question from Diaz, a student: How would you solve : ( pie*X)/ 4 = -pie/2 I have no idea.what to do!
Hi,
You have
$\frac{\pi \; x}{4} = -\frac{\pi}{2}.$
I would start by multiplying each side by $\large \frac{1}{\pi}.$
Write back if you need more assistance,
Penny
Math Central is supported by the University of Regina and the Imperial Oil Foundation. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.23539744317531586, "perplexity": 2950.364054190551}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655878753.12/warc/CC-MAIN-20200702111512-20200702141512-00046.warc.gz"} |
https://www.byteflying.com/archives/3800 | C#LeetCode刷题之#594-最长和谐子序列（Longest Harmonious Subsequence）
We define a harmonious array is an array where the difference between its maximum value and its minimum value is exactly 1.
Now, given an integer array, you need to find the length of its longest harmonious subsequence among all its possible subsequences.
Input: [1,3,2,2,5,2,3,7]
Output: 5
Explanation: The longest harmonious subsequence is [3,2,2,2,3].
Note: The length of the input array will not exceed 20,000.
```public class Program {
public static void Main(string[] args) {
var nums = new int[] { 1, 3, 2, 2, 5, 2, 3, 7 };
var res = FindLHS(nums);
Console.WriteLine(res);
Console.ReadKey();
}
public static int FindLHS(int[] nums) {
var res = 0;
var dic = new Dictionary<int, int>();
for(var i = 0; i < nums.Length; i++) {
if(dic.ContainsKey(nums[i])) {
dic[nums[i]]++;
} else {
dic[nums[i]] = 1;
}
}
foreach(var item in dic) {
if(dic.ContainsKey(item.Key + 1)) {
res = Math.Max(res, dic[item.Key + 1] + item.Value);
}
if(dic.ContainsKey(item.Key - 1)) {
res = Math.Max(res, dic[item.Key - 1] + item.Value);
}
}
return res;
}
}```
`5`
(2) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 1, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3774067461490631, "perplexity": 1314.5895179977692}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030335190.45/warc/CC-MAIN-20220928082743-20220928112743-00005.warc.gz"} |
https://brilliant.org/problems/3-couples-in-a-row/ | 3 Couples in a Row
3 Couples are seated at random in a row on 6 chairs. What is the probability that none of the spouses are seated together?
× | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8043410181999207, "perplexity": 213.49082621915136}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-51/segments/1544376832259.90/warc/CC-MAIN-20181219110427-20181219132427-00524.warc.gz"} |
http://mathhelpforum.com/algebra/154427-exponents-log-print.html | # Exponents and log
• Aug 25th 2010, 04:25 PM
Exponents and log
x3/2 = 27/64, so x = ¾ and ln(12 + x) = (ln 12)(ln x)
• Aug 25th 2010, 04:34 PM
pickslides
$\displaystyle x^{\frac{3}{2}}= \frac{27}{64}$
$\displaystyle (\sqrt{x})^3= \frac{27}{64}$
$\displaystyle \sqrt{x}= \frac{3}{4}$
$\displaystyle x= \frac{9}{16}$
• Aug 25th 2010, 04:47 PM
thegreenmathdr
You have ln(12+x)=ln12+lnx Therefore ln(12+x)=ln12x if you put e to both logs you get 12+x=12x---->12=11x--->x=12/11
I would normally be more wordy and explain each step but I see they don't do that here.
• Aug 25th 2010, 04:50 PM
pickslides
Quote:
.....I was given these problems to fix the errors!
ln(12 + x) = (ln 12)(ln x)
Assuming this is an error?
It should be
$\ln a +\ln b = \ln (a\times b)$
• Aug 25th 2010, 07:03 PM | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 5, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9810402393341064, "perplexity": 8323.303199976874}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948594665.87/warc/CC-MAIN-20171217074303-20171217100303-00646.warc.gz"} |
http://tex.stackexchange.com/questions/28554/is-there-a-way-to-enable-syntax-highlighting-coloring-in-lyx-for-program-listing/28597 | # Is there a way to enable syntax highlighting coloring in Lyx for program listings?
I want to embed a small program listing and have used `Insert -> Program Listing` in LyX's menu for that.
The settings dialog supports selecting a language (Java), but I can't actually see any difference.
Is there a way to get real syntax highlighting/coloring?
-
Since you have some responses below that seem to answer your question, please consider marking one of them as ‘Accepted’ by clicking on the tickmark below their vote count (see How do you accept an answer?). This shows which answer helped you most, and it assigns reputation points to the author of the answer (and to you!). It's part of this site's idea to identify good questions and answers through upvotes and acceptance of answers. – Jubobs Mar 2 '14 at 11:26
## 2 Answers
Lyx's "Insert -> Program Listing" is internally based on the `listings` package, which provides a a plenty full of options to influence the typesetting. You can enter such `listings`options on the "Advanced" page of the "Listing Settings" dialog. For instance, entering
``````keywordstyle={\color{blue}}
``````
there would typeset all keywords in blue color. For a quick start take a look at other questions with the tag – or consult the (excellent!) `listings` documentation
The reason you do not "see any difference" in your current setup may be a font issue: The culprit is the standard `typewriter` font in LaTeX, which does not have a boldface version; however, the default of `listings` is `keywordstyle=\bfseries`, that is, keywords are typeset in boldface. So just try another `typewriter` font in "Document -> Settings -> Fonts" and see if this makes a difference.
(BeraMono is a good font for typesetting listings.)
-
I'm using "Latin Modern Typewriter" is this supposed to work? – soc Sep 15 '11 at 23:55
@soc: So have you tried another font to see if this makes a difference? AFAIK LMT supports a boldface series, but at small font sizes the visual difference to normalfont is not too obvious. – Daniel Sep 16 '11 at 7:12
Mhhh, I have tried various fonts, but bold worked with none of them... :-/ – soc Sep 16 '11 at 9:43
@soc: Have you tried setting `keywordstyle` explicitly, as described in my answer? – Daniel Sep 16 '11 at 11:49
Yes, I set the color to blue, which worked... – soc Sep 16 '11 at 12:20
An example for GRASS-GIS module names. The code goes to the Listings section (to be found under Document > Settings... ):
``````alsoletter={*()"'0123456789.}
alsoother={\{\=\}}
backgroundcolor={\color{lightgray3}}
basicstyle={\small\ttfamily}
breaklines=true
commentstyle={\itshape\color{lightgray}}
fillcolor={\color{red}}
frame=l
framexleftmargin=1em
framextopmargin=1em
keywordstyle={\color{magenta}\bfseries}
language=bash
literate={{=}{{{\color{blue}=}}}1}
morecomment={[n][\keywordstyle]{{}{}}}
morekeywords={GRASS_OVERWRITE, region, zoom, nsres, ewres, MASK, input, in, rast, map, output, out, type, use, attrcolumn, rgbcolumn, labelcolumn, method, size, title, color, null(), S, N, W, E, a, b, c, d, e, f, g, n, s, w, e, --o, -c, -e, -s, -ca}
otherkeywords={g.access,g.cairocomp,g.copy,g.dirseps,g.filename,g.findetc,g.findfile,g.gisenv,g.gui,g.list,g.mapset,g.mapsets,g.message,g.mkfontcap,g.mlist,g.mremove,g.parser,g.pnmcat,g.pnmcomp,g.ppmtopng,g.proj,g.region,g.remove,g.rename,g.setproj,g.tempfile,g.version,r.basins.fill,r.bitpattern,r.buffer,r.carve,r.category,r.circle,r.clump,r.coin,r.colors,r.colors.out,r.composite,r.compress,r.contour,r.cost,r.covar,r.cross,r.describe,r.digit,r.distance,r.drain,r.external,r.external.out,r.fill.dir,r.flow,r.grow,r.grow.distance,r.gwflow,r.his,r.horizon,r.in.arc,r.in.ascii,r.in.bin,r.info,r.in.gdal,r.in.gridatb,r.in.lidar,r.in.mat,r.in.png,r.in.poly,r.in.xyz,r.kappa,r.lake,r.le,r.li,r.los,r.mapcalc,r.mfilter,r.mode,r.neighbors,r.null,r.out.arc,r.out.ascii,r.out.bin,r.out.gdal,r.out.gridatb,r.out.mat,r.out.mpeg,r.out.png,r.out.pov,r.out.ppm,r.out.ppm3,r.out.tiff,r.out.vrml,r.out.vtk,r.param.scale,r.patch,r.profile,r.proj,r.quant,r.quantile,r.random,r.random.cells,r.random.surface,r.reclass,r.recode,r.region,r.regression.line,r.report,r.resamp.bspline,r.resamp.filter,r.resamp.interp,r.resample,r.resamp.rst,r.resamp.stats,r.rescale,r.rescale.eq,r.ros,r.series,r.series.interp,r.shaded.relief2,r.slope.aspect,r.solute.transport,r.spread,r.spreadpath,r.statistics,r.statistics2,r.statistics3,r.stats,r.sun,r.sunmask,r.support,r.support.stats,r.surf.area,r.surf.contour,r.surf.fractal,r.surf.gauss,r.surf.idw,r.surf.idw2,r.surf.random,r.terraflow,r.texture,r.thin,r.timestamp,r.topidx,r.topmodel,r.to.rast3,r.to.rast3elev,r.to.vect,r.transect,r.univar,r.uslek,r.usler,r.viewshed,r.volume,r.walk,r.water.outlet,r.watershed,r.what,r.what.color,v.buffer,v.build,v.build.polylines,v.category,v.class,v.clean,v.colors,v.colors.out,v.convert,v.db.connect,v.db.select,v.delaunay,v.distance,v.drape,v.edit,v.external,v.external.out,v.extract,v.extrude,v.generalize,v.hull,v.in.ascii,v.in.db,v.in.dwg,v.in.dxf,v.info,v.in.lidar,v.in.ogr,v.in.region,v.in.sites,v.kcv,v.kernel,v.label,v.label.sa,v.lidar.correction,v.lidar.edgedetection,v.lidar.growing,v.lrs,v.mapcalc,v.mkgrid,v.neighbors,v.net,v.net.alloc,v.net.allpairs,v.net.bridge,v.net.centrality,v.net.components,v.net.connectivity,v.net.distance,v.net.flow,v.net.iso,v.net.path,v.net.salesman,v.net.spanningtree,v.net.steiner,v.net.timetable,v.net.visibility,v.normal,v.out.ascii,v.out.dxf,v.outlier,v.out.ogr,v.out.postgis,v.out.pov,v.out.svg,v.out.vtk,v.overlay,v.parallel,v.patch,v.perturb,v.proj,v.qcount,v.random,v.reclass,v.rectify,v.sample,v.segment,v.select,v.split,v.support,v.surf.bspline,v.surf.idw,v.surf.rst,v.timestamp,v.to.3d,v.to.db,v.to.points,v.to.rast,v.to.rast3,v.transform,v.type,v.univar,v.vect.stats,v.vol.rst,v.voronoi,v.what,v.what.rast,v.what.rast3,m.cogo,m.measure,m.nviz.image,m.nviz.script,m.transform}
prebreak={\textbackslash}
sensitive=true
stepnumber=1
tabsize=4
upquote=true
``````
It works fine, except for one error: the keyword `v.lidar.growing` isn't colored correctly. Because there is an `r.grow` entry already, only a part of it appears to get the desired color (here the bold letters), `v.lida``r.growing`.
- | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8431170582771301, "perplexity": 3056.3156950977536}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461860109993.2/warc/CC-MAIN-20160428161509-00216-ip-10-239-7-51.ec2.internal.warc.gz"} |
https://www.lesswrong.com/posts/PX7AdEkpuChKqrNoj/what-are-your-greatest-one-shot-life-improvements | # 98
Sometimes, people have life problems that can be entirely solved by doing one thing. (doing X made my life 0.1% better, PERMANENTLY!) These are not things like "This TAP made me exercise more frequently", but rather like "moving my scale into my doorway made me weigh myself more, causing me to exercise more frequently" - a one-shot solution that makes a reasonable amount of progress in solving a problem.
I've found that I've had a couple of life problems that I couldn't solve because I didn't know what the solution was, not because it was hard to solve - once I thought of the solution, implementation was not that difficult. I'm looking to collect various one-shot solutions to problems to expand my solution space, as well as potentially find solutions to problems that I didn't realize I had.
New Comment
blueanchovy
### May 17, 2020
42
My realization that smoking was associative, led me to try to do it alone. I told everyone in my social circle that i had quit, and smoked in secret when I had to. I don't generally espouse lying but it might be a prerequisite in this case. I stopped using smoking as an aid to social situations, or as something to do with my hands and mouth when i was pensive. I focused completely on the very process and did not accompany smoking with anything else at all. What this method encompasses is, being very aware of smoking, from lighting it, putting it on your lips, inhaling the smoke, exhaling, to flicking the ash and throwing the butt away. I also focused on the sensations in my mouth and lungs, as well as the blood rush. It reduced my daily intake immediately, made me despise smoking, and along with other measures, helped me kick the addiction for good.
Reminds me of something Nate Soares wrote:
When I was quite young, one of the guests at our house refused to eat processed food. I remember that I offered her some fritos and she refused. I was fairly astonished, and young enough to be socially inept. I asked, incredulous, how someone could not like fritos. To my surprise, she didn't brush me off or feed me banal lines about how different people have different tastes. She gave me the answer of someone who had recently stopped liking fritos through an act of will. Her answer went something like this: "Just start noticing how greasy they are, and how the grease gets all over your fingers and coats the inside of the bag. Notice that you don't want to eat things soaked in that much grease. Become repulsed by it, and then you won't like them either."
Now, I was a stubborn and contrary child, so her ploy failed. But to this day, I still notice the grease. This woman's technique stuck with me. She picked out a very specific property of a thing she wanted to stop enjoying and convinced herself that it repulsed her.
Ah, right. Twix. I forgot about this one. While depressed, I gradually ramped up my consumption of Twix from the vending machine near my office to over 1 per day (2 since they came in pairs?). I wanted to stop, tried several times and failed, remembered about a technique I'd seen on LW. Tried it. Have not had a single Twix for many years.
Technique: bought one Twix. Slowly, mindfully, broken off pieces and threw them in the trash, carefully imagining that I was tasting the Twix and that it was full of maggots. Took... a few minutes? Craving gone.
Mark Xu
### May 16, 2020
8
My glasses didn't fit properly, causing them to slide down my nose frequently. I used hot water to bend the frames around my ears better, solving the problem.
I wrapped a small rubber band to the ends of the stems & the glasses do not slide anymore.
Orfeas
### Feb 17, 2021
7
Solution: A browser extension that removes the recommended videos sidebar.
This has easily saved me tens of hours of wasted time.
slicko
### Dec 07, 2020
7
Problem:
Spending too much time using your phone each day (surfing, messaging, watching videos, ..etc.).
Solution:
Change your phone's display settings to only display in grey scale.
Notes:
I saw this tip online a long time ago, and have tried it on several occasions to break an addiction to my phone (where I was glued to my phone for hours daily).
It's shocking how well this trick works. You realize after using your phone in this mode for a few days how effective colours are in getting and keeping your attention, all in the name of getting you more "engaged" with apps / your phone.
One the one hand, this one-time solution gets rid of all these temptations wholesale, on the other hand, it's almost nauseating to use the phone for a long period of time in grey scale. I don't know why, but I will literally end up tossing my phone away in disgust after a few minutes of using it in this mode, thereby very effectively solving the original problem.
Viliam
### May 24, 2020
7
I spent a lot of time sitting, because computers are both my work and my hobby. I was thinking about solutions, and I had a few ideas, but I procrastinated for years.
Recently, a health problem made me look for a solution immediately. So I put a huge plastic box on my table, and put the monitor and keyboard on the top of the box, and now I use the computer while standing. At first it felt weird, and I quickly got tired. But after a few weeks, my body adapted and now it feels natural. And the health problem that inspired this change is mostly gone.
Another positive side effect is that the "activation energy" needed to leave the computer is much smaller when I am no longer sitting. Yet another is that my 2 years old daughter no longer tries to climb in my lap whenever I try using the computer.
From the rationality perspective, it is quite humiliating to notice how long it took me to finaly address a problem that could have serious health consequences, and how little time and effort the actual solution required, once the gun was metaphorically pointed at my head.
(To be honest, I am not completely satisfied with this solution, and would like to replace the plastic box with something better... not sure what exactly. But the difference is that now I procrastinate on minor improvements, having already solved the critical part.)
There are standing desks available. They do happen to be quite pricey, which is why I don’t have one. Would be good if a cheaper alternative, that was still aesthetically pleasing, came along.
moderock
### May 19, 2020
7
Glide floss. My teeth absolutely shred every other brand, but Glide is coated with Teflon. Made regular flossing possible.
I stopped watching news years ago. Improved my mental state massively.
Stretching every day, right after work, has been a win as well. It’s a good end to the day, I’m way more flexible, and overall feel happier.
Whenever I feel angry or frustrated, I ask myself what outcome I want from the situation, and focus on how to make that happen. Helps me avoid acting counterproductively on emotion.
sebkap
### May 18, 2020
7
If it will take < 5 mins do it immediately.
It works for responding to e-mails, buying stuff for home, paying bills etc. Benefits which I noticed:
• It allowed me to have smaller backlog of quick task
• I feel I have less cluttered mind
• I feel I forget less stuff which I need to do
### May 17, 2020
7
Buying my girlfriend a vape. She smokes weed a lot and it's been said that getting a smoker to switch to vaping is one of the best things that you can do in terms of longevity. She also says that it is much more enjoyable.
(She likes the Pax 3 a lot; Vape Critic seems like a good resource for reviews.)
Liron
### May 17, 2020
6
Any gym equipment in your house, even just a couple 15-pound dumbbells.
Exercising used to be the #1 reason I leave my house, and I don’t leave my house much overall, so pre-COVID I thought I might as well keep using outside-the-home gyms. But I'm also somebody who finds doing 10+ minutes of "task-switching", like driving to the gym, to be a pretty big psychological barrier.
So finally I bought some weights and a treadmill, and now almost every day I'm like sure, at some point of this day I'll take 30 seconds to switch tasks from sitting in a chair to moving my body, it's a nice change of pace.
A pull-up bar: cost $10, installation in door frame 5 minutes, allows me to do pull-ups spontaneously at any moment. Which sometimes leads to other forms of exercise. Then a small problem appeared, because I installed the pull-up bar in the bedroom door (reasoning: this door is used least frequently, so people would be least bothered by having the bar there), but it turned out that no one minds the bar, however I cannot exercise when other people sleep. Solved by installing another pull-up bar in a different door frame. A stepper: now I can exercise while watching movies. Pablo ### May 17, 2020 6 Recurring Freedom session across all my devices (laptop, phone, tablet) set to disable all apps and most websites (including messaging, news, and discussion sites) 30 minutes before bedtime every night. bbleeker ### May 17, 2020 6 Reading https://www.amazon.com/Allen-Carrs-Easy-Control-Alcohol-ebook/dp/B07B7QRWTH enabled me to quit drinking alcohol very easily. It was almost like it just turned off my desire to drink for good. ~3.5 years alcohol-free now. What does he do specifically? It's very unclear just from reading the Amazon description. Or is it like an entire program. I'm skeptical: I have never heard of this anywhere else, so it seems like one of those$100-bill-on-the-subway-floor type things.
5bbleeker4moI'm actually not quite sure. It's not a whole program; you just read the book, and (if you're anything like me) you're sober, just like that. I'm not a 'recovering alcoholic' the way I see some people writing who have been sober for even longer than I have; I'm done with alcohol, for good, and I knew it right away. He basically talks about the negatives of drinking and the positives of sobriety, with stories and examples, in a way that just 'clicked' for me.
1BeanSprugget4moI see. Thanks.
bbleeker
### May 17, 2020
6
Reading https://www.amazon.com/Allen-Carrs-Easy-Stop-Smoking-ebook/dp/B0051XSN50/ enabled me to stop smoking very easily, and I've not wanted a smoke in 25+ years now.
Did you already want to stop smoking at the time you read it?
2bbleeker1yYes, and I had tried several times before, without success. The difference is that earlier I just wanted to stop smoking for health reasons, but I still loved smoking. After reading the book, I don't want to smoke because I just don't like it anymore.
1oast4moWas there anything in particular in the book that triggered you to not enjoy smoking anymore?
2bbleeker4moYes, I think it was where he explained that you don't really feel better when you smoke. What happens is that a smoker feels worse in the times they don't smoke, and then a cigarette brings them up to normal again for a short while; so while you're smoking you feel as good as a non-smoker feels all the time. But I don't know if just reading that would have done the trick without the rest of the book.
maximkazhenkov
### May 17, 2020
5
Installing the Hide YouTube Comments chrome extension stopped my habit of reading and participating in the toxic comment section of YouTube. Absolutely essential for mental hygiene if you suffer from the same habit but at same time don't want to miss out on the great video content there.
As a more powerful version of this, you can install uBlock Origin and configure these custom filters to remove everything on youtube except for the video and the search box. As a user, I don't miss the comments, social stuff, 'recommendations', or any other stuff at all.
bbleeker
### May 17, 2020
5
Taking Alexander technique classes improved my posture a lot, and cured the tendinitis I used to get in my shoulders.
How much time did the classes take, in terms of upfront investment and any ongoing investment required?
3bbleeker1yI took 10 lessons, and I think I could probably have done it with 8. I still feel myself sagging now and again, and then I have to correct myself (and then I wonder why I sagged to begin with, because the correct posture is actually more comfortable). I have also bought a new chair ( https://www.ikea.com/nl/nl/p/kullaberg-bureaustoel-zwart-90325518/, [https://www.ikea.com/nl/nl/p/kullaberg-bureaustoel-zwart-90325518/,] only mine has a different color) and removed the backrest. I have found that chairs with a backrest and armrests tempt you to lean on them, and then you can end up sitting in a wrong posture for a long time without noticing. Without them, I soon notice and can correct myself.
Lynne Stanshine
### Jan 02, 2021
4
When partner is really upset, look at him or her in the eyes & say, "Darling, I'm here for you." (Buddhist)
Annapurna
### Jul 19, 2020
4
Flossing in the shower.
I went from seldom flossing to flossing every single day, improving my gum health significantly.
I brush my teeth in the shower and find that I clean more thoroughly than standing at the sink
practically
### Jul 10, 2020
4
When I revise my writing I find it hard to delete large chunks because it feels like a waste and I'm also worried that I might change my mind and need parts later.
I have a folder in Notes called "Writing Stubs," where I dump the would-have-been-deleted chunks (and also other temporary relevant bits of information, kind of like working memory). It makes me feel better that I have the original still and so, feeling more assured, I can ruthlessly delete large chunks from my writing which might be unnecessary or badly written. Speeds up the revision process.
I'm fascinated by this phenomenon, where expunging even obviously poor chunks can feel like an amputation. If you don't mind, I have a couple of questions. Have you looked at using version control for your writing? What tools do you use (Apple Notes?) and why?
1practically1yMy guess would be that the feeling is probably due to some combination of sunk cost fallacy and maybe that the writer would tend to feel some type of emotional connection to whatever they've already written since it's a reflection of their opinions / at some point when they were writing it they thought it was good stuff. I looked this up and found other people who do the same; in this post [https://thewritepractice.com/delete/] there's a lot of discussion in the comments about this, if you wanted to take a look. I personally don't write that often, and the system of keeping the deleted chunks in Apple Notes was just out of convenience. Other people in the post linked above have used a Word Document to keep the deleted chunks, but I personally feel that it takes more time to open up a Word Document than to drop something in Notes, which is also particularly nice since you can always start a new note without having to scroll past old writing. I never really thought of using version control before but I do feel like it's not quite the same as just keeping the deleted chunks. Usually I might delete a large portion, make some significant changes to another portion, and then go back and decide I want to use stuff from the deleted portion, so version control might be inconvenient since I've already changed other things too. I might be wrong since I haven't really used version control before, though.
Raj Thimmiah
### May 23, 2020
4
Earmuffs have helped me a lot for productive time. The silence lets me focus more on what I'm trying to work on. Compared to my noice cancelling headphones (qc 35 II) I can't play music even if I want to to so less likelihood of distraction. On occasion though, if they aren't enough by themselves I'll put earbuds inside the earmuffs with low wind noise. I can hear pretty much nothing external after that.
They also help me sleep on planes since they block out a fair portion of the noise.
This is the one I use: https://www.amazon.in/3M-Peltor-X5A-Over-Earmuffs/dp/B00CPCHBCQ
It looks ridiculous when you wear it. Really ridiculous, I won't lie.
Two related life hacks:
1. Poundland earplugs are surprisingly good.
2. Slot glasses in over the top of earmuffs. I don't wear contact lenses due to dust allergies, and, even if I buy the thinnest frames, glasses under earmuffs still reduce sound attenuation. (Disclaimer: wearing glasses over earmuffs causes some visual distortion.)
Liron
### May 17, 2020
4
My solution for keyboard RSI:
For software engineers, a normal QWERTY keyboard requires the pinky on the right hand to press a ton of different keys, and my pinky joint was getting sore.
I bought this Ergodox EZ keyboard and remapped the "P" and various brackets to extra keys that are easily-pressable with my forefinger or thumb. It took a couple weeks to stop being annoyed by the new layout, and a couple months to return to my old typing speed, but this is a lifelong ROI.
There's another major bonus: I can now separate my arms far apart when I type, instead of squishing them together to accommodate a one-piece keyboard.
I solved the same problem by using Dvorak.
I really love my Ultimate Hacking Keyboard which looks pretty similar to the Ergodox EZ one.
3Liron1yAh ya I didn't realize Dvorak helps significantly with layout of punctuation. The Ultimate Hacking Keyboard looks great, only thing for me is I prefer the two sides extra far apart and I think Ergodox's cable span is an extra foot or so.
2Dagon1y+1 on UHK - also, get more than one if you like it and spend significant time in multiple locations (I have one for my home workstation and one for my office, though both are at home just now...). Definitely try the ergodox as well, but I couldn't get used to the ortho layout, when I have to switch back to a standard keyboard occasionally (using a laptop away from my station). UHK is standard size/layout of keys, so running AutoHotKey (for Windows; there's an equivalent for OSX) lets me use the same layers on the standard keyboard as on my UHK. Built-in KB is still inferior in feel, and in lack of distance/angle between hands, but the muscle memory of mod-HJKL for arrows and nearby keys for other nav is retained.
Can you link your ergodox config? I'm currently trying to build mine and suffering from feature creep.
2Liron1yThis layout [https://configure.ergodox-ez.com/ergodox-ez/layouts/Eejdn/latest/0] has worked decently well for me and I haven't tweaked it in months, but it makes major tradeoffs, most notably: 1. No arrow keys in the main layer 2. The same key can be either enter or right shift so occasionally I accidentally hit enter in a chatroom when I don't want to. But at least my thumbs can do a lot of heavy lifting.
On a similar note, I use a kinesis advantage; I had to choose between that and an ergodox and expected to like it slightly more, but I can't actually compare.
I've set it up so that if I hold caps lock, I can control the mouse with my right hand. Not as fluidly as I'd like, at least partly due to (what I believe to be) bugs in the xkb code implementing such things. I can only move 100px at a time. But I also have focus-follows-mouse, and that makes it really easy to jump between two windows, which by itself is a decently big win.
caps lock also mirrors the r
Purplehermann
### May 16, 2020
4
Skincare - not using product.
Giving up facial soap and making sure shampoo didn't get on my face did what no cleaning regiment did.
I tried this as a teen with moderate - severe acne, and to this day my skin is even better than most people's
Lynne Stanshine
### Jan 02, 2021
3
Sound machine at night eliminates sound from other rooms when you sleep.
My alternative to a sound machine is to have my desk fan turned on on during the night
Morpheus
### Dec 20, 2020
3
I feel very drowsy in the morning, if I get woken up by an alarmsound or vibration. Buying a light alarm clock has largely solved this problem for me. I wake up before the alarm rings about 80% of the time. It does not work that well if I am sleep deprived.
The main advantages for me are: I wake up more often before my alarm rings and the light is an immediate cue that it is time to wake up.
They are relatively expensive, but from browsing Amazon for 2 minutes I get the impression that you can get pretty good ones for 30-50$(I personally bought one for ~60$).
jimwheeler
### Aug 22, 2020
3
I get waylaid down rabbit holes as I work on the computer. Everybody is probably familiar with this - you start a Chrome tab to read about space exploration and two hours later you have 50 tabs open, the current one being about the nesting habits of robins :-)
A couple of years ago I started using the Evernote web clipper to save all these articles to my Evernote library. So now I don't go off track and I don't spend endless hours reading articles that are interesting but unrelated to my current projects.
My brain's FOMO related to not reading these articles appears to be satiated as long as it knows the article is safely saved in case I need it later!
+1 to this, although I just use bookmarks or OneTab. And it turns out I only go through my bookmarks once every like five years, so by the time I get to the articles 90% of the time they are completely irrelevant to the present day or my interests have changed enough that I just don't care anymore :P
### May 19, 2020
3
Reading 'Say Goodnight to Insomnia'. I struggled with horrible insomnia, now I have a ridiculous control over my sleep.
bfinn
### Apr 27, 2021
1
I fixed my sleep in a few weeks using the (paid) online service Sleepio, which has been clinically proven (to the extent I think it's available via NHS prescription in the UK):
It took me from getting 1 night's full sleep per year, to sleeping a full night maybe 6 nights a week.
This was after I'd done my own research study for months trying out lots of different standard sleep improvement techniques - none of which made a significant difference.
Sleepio got me to try various things, and hit on one I hadn't considered, which was that I was allowing too much time to sleep in - i.e. setting my alarm clock too late. So I was sleeping too shallowly. It gradually made me compress my sleep into a shorter and shorter time until I was sleeping deeply enough to stay asleep throughout the night. Problem solved!
Conaugh
### Apr 15, 2021
1
Problem: I struggle with sleep. Both getting to sleep and staying asleep.
Solution: Custom gel earplugs, and soft fleece eyemask.
Improvement: %%.
Comment: I'm sensitive to light and sound, so the slightest noises and early morning light will wake me up. I didn't realise this may be the cause of the problem until three years ago; people told me it was because I was depressed, but it was the other way around. I tried a bunch of solutions but they were all irritating, and the plugs icky or wasteful. So I went to my local opticians for my earplugs (best £100 life spend.) And for the mask I found a material that didn't itch on my skin with soft pressure, and made it into a headband. I used to be a sleepless mess until my twenties. This was a big change.
Zian
### Dec 07, 2020
1
>sleep
Buy new blanket that isn't falling apart. Semi-permanently reduced the ugh field.
>health
If I take "Doctor diagnosed X" as strong evidence that I have X, then I should find the latest treatment guidelines/summary articles for X once a year. Led to a possibly permanent treatment algorithm (full or nearly-full symptom management) for 2 chronic problems with little to no side effects. Also caught a medication error with the acquired knowledge. Also a found a treatment that greatly helps (but not eliminates/prevents) another chronic condition.
May also have turned up a life-altering diagnoses but that is to-be-confirmed by real medical experts.
>general knowledge acquisition
Using Sci-Hub. Reduces the "Relevant article in PubMed based on the abstract->paste the PMID->oh, this is useful" loop to <1 min.
If necessary, I can try to quantify the benefits of the above items but it's a little like the RENT song about measuring a year.
Raven
### Jun 02, 2020
1
Transition medication. The actual act is incredibly simple (just take pills a couple times a day) but has a disproportionately huge impact on the rest of my life.
I suspect this probably generalizes pretty well to things like antidepressants.
Raj Thimmiah
### May 23, 2020
1
Eyemasks and earplugs have helped a lot for sleep. I'm not sure how to quantify the benefit but I haven't slept without them (for nightsleep) in at least a year from what I can recall.
I can't fall asleep with earplugs in. I wear earplugs and earmuffs at work, but my job involves fast-paced assembly work which provides a lot of tactile feedback to distract me from the itchy earplugs.
Also be aware any earplugs marketed as being 'for sleep' or 'for nuisance noise' block out so little noise that you are better off sleeping on your side with a pillow over your ear. Look for earplugs with an SNR of at least 30dB (preferably at least 35dB).
I've found that earplugs exacerbate the effects of tinnitus and make it difficult to sleep. Having my desk fan turned on throughout the night helped me sleep a lot better
Zian
### May 18, 2020
1
Haven't quite reached the 100% resolved/full-payoff state yet but I once had a doctor firmly tell a family member to (paraphrased) not settle for a partial improvement and https://www.lesswrong.com/posts/fhEPnveFhb9tmd7Pe/use-the-try-harder-luke. I notice that when I apply that seriously to my health problems, entire swaths of the problem space vanish. I can't say that I'm 100% fixed though because my doctors and I are still digging around in the much-reduced problem space.
If you require something that's fully resolved or has definite results, then I'd say:
• Aforementioned "1 thing" resulted in long-term pain relief in part of my body
• Checking UpToDate (<$50 for 1 week) before (and during) doctor visits dropped my stress greatly and showed me that certain problems might have a real solution. I am also able to have a much more intelligent and meaningful conversation with doctors ### May 16, 2020 1 The Zettelkasten has resolved my problem, i.e. searching for a place where to keep and retrieve easily all the stuff I collect to study Are you putting yours on paper or storing it digitally? 1[anonymous]1yDigitally TruetoThis ### May 17, 2020 -7 In order to win Championships, some tennis players take ballet to make them more graceful and light on the courts. They create habits of working on themselves while each 0.1% amounts to the whole. It may also be a word of advice to create habits around the solutions to your problems i.e. the tennis player stretching every morning before the start of the day. PROBLEM: flexibility, mobility SOLUTION: ballet and dance classes [This comment is no longer endorsed by its author] This answer says nothing about what you tried. "Create a habit" also mostly isn't a one-shot solution in the way the OP uses the term. 1TruetoThis1yMy relation to the article was in reference to implementation (of a habit) and to address the 0.1% in changes that advocate for a better outcome for a solution to change. I play tennis and I must also sharpen this skill with complementary solutions (ballet) to ensure I win my matches. Again, it's about the small solution changes that add to a whole. 12 comments, sorted by Highlighting new comments since My read is that over half the non-OP answers are not one-shot enough to match the question, and have downvoted them (weakly). I'm curious for feedback on this use of downvoting I agree that many answers aren't the sort of one-shot things that I was looking for. Downvoting in general confuses me, but I think that downvoting to 0 is appropriate if the answer isn't quite answering the question, but downvoting past zero doesn't make sense. Downvoting to 0 feels like saying "this isn't that helpful" whereas downvoting past 0 feels like "this is actively harmful". This comment makes a lot of sense, and is consistent with consensus on Stack Exchange. For this reason, I've changed my voting method from my previous policy of voting independently of the current score. I bought ~$5 medicine dispensers with weekday labels, which improved my life by ~15%.
Due to a psychiatric illness, I have to take a single pill every morning. It wasn't very complicated, so I just took them from the blister pack she was carrying. If I forget to take a pill, I feel uncomfortable in the evening. Not too much, but what was much more stressful was that I often didn't *know* it: Did I forget to take the pill in the morning? Or is my condition worsening? This uncertainty was really scary.
With the Medi-Dispenser I forget the pill less often, and more importantly: if I feel uncomfortable in the evening, I can check the dispenser, and in 95% I recognize it again: No, my condition does not get worse, I only forgot to take my pill in the morning. Then I go to sleep and make sure that I take the next pill the day after.
PS: I am a little embarrassed that it took me about 5 years to come to this simple solution. I'll share it anyway, if it helps anyone else.
From one chronic health person to another...
Consider filling up a second dispenser ahead of time. That way, if you're completely exhausted but it's time to take your medication, you can yank the second box off the shelf and refill things when you're more awake. It also gives you a 1 week buffer to refill your prescription.
Pill counting trays are also helpful if you have to take medications that come in a bottle. Buy one that has Amazon reviews from real pharmacists and put the cap under the spout on the right side to catch any runaway pills. This will dramatically reduce the # of pills that fall to the floor.
Getting into bed by 6pm and waking up at 3am (small win), going through my moring routine: 20 pushup 10 knee ups to warm/ wake up (small win), make bed (small win), at least 30 min walk outside (small win) all these thing set my day up to be productive I the last 5 months I've accomplished many Sunrise hikes, over 21 friends made, read many books i'd been meaning to get to, started carrying around a journal and writing everything down. Some of the moments of the last 5 months have been the best of my life, I have been feeling great. I have accomplish more towards my life goals in 5 months than I have in 3 years.
Sources:
The Miracle Morning
The Power of Habit
Why is it better to wake up at 3 am compared to 6 or 7 am?
I suspect the best sleep schedule is highly individual.
I like to watch the sunrise, it also feels pretty inspiring when you complete tasks early and while everyone else is waking up your work for the day is done and you can enjoy your self. Its also a hard thing to do, a small win (the power of habit) something that when I have the discipline to do gives me greater freedom "start your day with a task complete" (make your bed) and chains into getting more and more done that day.
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https://finalfantasy.fandom.com/wiki/Hashmal_(Tactics)?diff=2435162&oldid=2434448 | ## FANDOM
36,804 Pages
Master, 'Bloody Angel'... Let me offer you 'blood' darker than wine and hotter than burning lava!
—Hashmal
Hashmal (), also known as Hashmalum , is the fifth Lucavi demon that Ramza Beoulve must fight in Final Fantasy Tactics. Second-in-command of the Lucavi, he is associated with the Leo Auracite and has possessed Folmarv Tengille, leader of the Knights Templar of the corrupt Church of Glabados.
## Profile
### Appearance
Hashmal appears to be a demi-human with long pale blond hair with two low short braids on each side and a lion-like face. He wears a dark blue sleeveless robe with matching wristbands on both wrists and has sharp claws on both of his hands.
## Story
Spoiler warning: Plot and/or ending details follow. (Skip section)
Hashmal was responsible for killing most of the guards including Folmarv's son, Isilud in Riovanes Castle during a rampage after his negotiations with Duke Gerrith Barrington soured until he reverts back into Folmarv who had found Alma who is a suitable host vessel for his master, Ultima.
Later, Ramza fights Hashmal at the Airship Graveyard, where he is attempting to bring his master Ultima back to life. After receiving a wound from Ramza, Hashmal commits suicide to provide his own blood for Ultima's resurrection. This works, and Ramza must battle Ultima shortly afterward.
Spoilers end here.
## Gameplay
Hashmal's job is Regulator (PS)/Bringer of Order (WotL) in the game. He is level 59 with 70 Bravery and Faith, and has roughly 1425 HP and 790 MP. He is immune to all negative statuses except Blind, Slow, and Immobilize. He has several powerful attacks like Quake.
### Rendezvous
When fought in the thirteenth Rendezvous battle: Nightmares, he is level 99 and carries the same abilities and status immunities as previously.
## Stats
A being capable of controlling the very laws of nature, and thus ruling all living things far and wide.
Move Rate Jump Rate Speed Physical Evasion Rate Base Attack Base Magic Base HP Base MP
5 4 13 12% High High Average High
## Abilities
### Innate Abilities
Lucavi job command. This special technique shatters the mind, causing status effects.
The formula for damage is as follows:
$Magick Attack \times PWR \times (Faith/100) \times (Target Faith/100)$
Original Name WotL Name Description Range Effect Speed
Speed Ruin Speedsap Dull the target's reflexes, reducing his or her Speed.
MP Cost: 20
Quote: "Destroy all time! Speed Ruin!"
4 2 33
Spell Bind Inflict a status effect.
Effect: Stop.
Quote: "One step closer to hell! Spell!"
5 2 Now
Death Cold Ague Inflict a status effect.
Effect: Slow.
Quote: "Inject evil spirits! Death Cold!"
5 2 Now
### Dimension Magic/Planar Magicks
Bringer of Order job command. Warps time and space to bring about catastrophe.
PS Name WotL Name Description MP Cost Range Effect Speed
Melt Meltdown Magick that transforms the entire area of effect into the searing-hot flames of the lower hells.
Element: Fire.
Quote: "Dissolve into a fiery world of chaos... Melt!"
70 4 4 15
Element: Wind.
Quote: "Gusting winds, hear what I say! Tornado!"
70 4 4 15
Quake Magick that conjures up a massive earthquake, nearly upending earth and sky.
Element: Earth.
Quote: "Assailants in the ground, it's time to rumble! Quake!"
70 4 4 15
Meteor Time magick that warps space-time, causing an enormous meteor to fall on the battlefield.
Quote: "Time has come...crash down on the wicked! Meteor!"
70 4 4 8
## Etymology
In modern Hebrew hashmal means "electricity". Hashmalim is the Jewish second order of angels; translated as golden/amber ones. (Amber was known for its static charges in antiquity and the basis of understanding electricity.) The leader of this order is named "Hashmal".
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https://brilliant.org/discussions/thread/a-doubt-of-integrals/ | # A doubt of Integrals !
Find the value of the definite integral : $\displaystyle \int_0^1( 1+e^{-x^{2}} )dx$
Note by Rishu Jaar
10 months, 4 weeks ago
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- 10 months, 4 weeks ago
@Pi Han Goh , thank you , its a jee 1981 question but didn't knew the maths involved was so higher.
- 10 months, 4 weeks ago
Then you can only evaluate it using numerical methods, like trapezoidal rule or Simpson's rule.
- 10 months, 4 weeks ago
Thanks , could you provide a link?
- 10 months, 4 weeks ago
Trapezium Rule
- 10 months, 4 weeks ago
Thanks!
- 10 months, 4 weeks ago
If, by value, you mean the area under the curve from 0 to 1, the solution would be 1/2 sqrt(π) • e • rf(1) + 1. This is simply found by removing the parentheses, taking the derivative, and then solving from there as usual.
- 10 months, 4 weeks ago
Oh can you explain more.
- 10 months, 4 weeks ago
Yes - I'll post a new discussion called JEE 1981 Int Calc with the information enclosed. I need my LaTeX!
- 10 months, 4 weeks ago
Ok sure.
- 10 months, 4 weeks ago
@RISHU Jaar It's in the new section.
- 10 months, 4 weeks ago
Done.
- 10 months, 4 weeks ago
@Rishabh Cool and others please give a proof !
- 10 months, 4 weeks ago | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9895690679550171, "perplexity": 9392.193042799534}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267164750.95/warc/CC-MAIN-20180926101408-20180926121808-00514.warc.gz"} |
http://abce.readthedocs.io/en/master/Agent_class.html | # Agents¶
The abce.Agent class is the basic class for creating your agents. It automatically handles the possession of goods of an agent. In order to produce/transforme goods you also need to subclass the abce.Firm or to create a consumer the abce.Household.
For detailed documentation on:
Logging and data creation, see Observing agents and logging.
Messaging between agents, see Messaging.
class abce.Agent(id, agent_parameters, simulation_parameters, group, trade_logging, database, check_unchecked_msgs, expiring, perishable, resource_endowment, start_round=None)[source]
Every agent has to inherit this class. It connects the agent to the simulation and to other agent. The abce.Trade, abce.Database and abce.Messaging classes are included. An agent can also inheriting from abce.Firm, abce.FirmMultiTechnologies or abce.Household classes.
Every method can return parameters to the simulation.
For example:
class Household(abce.Agent, abce.Household):
def init(self, simulation_parameters, agent_parameters):
self.num_firms = simulation_parameters['num_firms']
self.type = agent_parameters['type']
...
def selling(self):
for i in range(self.num_firms):
self.sell('firm', i, 'good', quantity=1, price=1)
...
def return_quantity_of_good(self):
return['good']
...
simulation = Simulation()
households = Simulation.build_agents(household, 'household',
parameters={...},
agent_parameters=[{'type': 'a'},
{'type': 'b'}])
for r in range(10):
households.selling()
print(households.return_quantity_of_good())
group = None
self.group returns the agents group or type READ ONLY!
id = None
self.id returns the agents id READ ONLY
init()[source]
This method is called when the agents are build. It can be overwritten by the user, to initialize the agents. Parameters are the parameters given to abce.Simulation.build_agents().
Example:
class Student(abce.Agent):
def init(self, rounds, age, lazy, school_size):
self.rounds = rounds
self.age = age
self.lazy = lazy
self.school_size = school_size
def say(self):
print('I am', self.age ' years old and go to a school
that is ', self.school_size')
def main():
sim = Simulation()
students = sim.build_agents(Student, 'student',
agent_parameters=[{'age': 12, lazy: True},
{'age': 12, lazy: True},
{'age': 13, lazy: False},
{'age': 14, lazy: True}],
rounds=50,
school_size=990)
name = None
self.name returns the agents name, which is the group name and the id
round = None
self.round is depreciated
time = None
self.time, contains the time set with simulation.advance_round(time) you can set time to anything you want an integer or (12, 30, 21, 09, 1979) or ‘monday’ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.18515703082084656, "perplexity": 22533.833022135077}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257649931.17/warc/CC-MAIN-20180324054204-20180324074204-00441.warc.gz"} |
https://www.physicsforums.com/threads/how-do-you-simplify-this.605717/ | # How do you simplify this?
1. May 13, 2012
### tamtam402
1. The problem statement, all variables and given/known data
Simplify e^(2n ln sin(pi/3))
2. Relevant equations
3. The attempt at a solution
I know that I can simplify to the form e^ln sin(π/3)^2n but I'm stuck there.
I can't see how I could end up with the answer (3/4)^n, which is supposed to be the right answer.
2. May 13, 2012
### tamtam402
Nevermind I'm a dumbass. Sin(pi/3) = sqrt(3)/2
Similar Discussions: How do you simplify this? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9608615040779114, "perplexity": 1690.869066400247}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886106754.4/warc/CC-MAIN-20170820131332-20170820151332-00622.warc.gz"} |
https://sumtxt.github.io/wiesbaden/index.html | The R package wiesbaden provides functions to directly retrieve data from databases maintained by the Federal Statistical Office of Germany (DESTATIS) in Wiesbaden. The package uses the SOAP XML web service from DESTATIS (PDF Documentation).
Note, to access any of the databases using this package, you need to register on the respective website to get a personal login name and password. The registration is free.
### Installation
You can install the package directly from CRAN:
install.packages("wiesbaden")
remotes::install_github("sumtxt/wiesbaden", force=TRUE)
### Usage
The package helps with retrieving the data cubes which are used to construct the data tables available as csv files via the web application of each database. The data cubes are long format data tables that are much easier to process as compared to the csv files. For details on how to use the package: Getting Started with wiesbaden.
The package also helps with importing the German municipality register files via the function read_gv100(). For more information see the help file of this function.
Users that wish to work with the csv files might find the download_csv() and read_header_genesis() in this package helpful. The former can be used to automate downloads and the latter facilitates importing downloaded files. Users might also wish to check the R package destatiscleanr github.com/cutterkom/destatiscleanr.
### FAQ
• Does this package work with a proxy? Yes. Set the proxy globally before calling any package command, e.g.:
httr::set_config(httr::use_proxy(
"your.proxy", port = 1234, auth = "basic"))
data <- retrieve_data(tablename="14111KJ002",
genesis=c(db="regio")) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.18701346218585968, "perplexity": 3158.362513854333}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710972.37/warc/CC-MAIN-20221204104311-20221204134311-00639.warc.gz"} |
https://worldwidescience.org/topicpages/a/atmospheric+hg+deposition.html | #### Sample records for atmospheric hg deposition
1. Observations of atmospheric Hg species and depositions in remote areas of China
Directory of Open Access Journals (Sweden)
Feng X.
2013-04-01
Full Text Available From September 2007, we conducted continuous measurements of speciated atmospheric mercury (Hg and atmospheric mercury depositions at five remote sites in China. Four of these sites were involved in the Global Mercury Observation System (GMOS as ground-based stations. These stations were located in the northwest, southwest, northeast, and east part of China, respectively, which represent the regional atmospheric Hg budgets in different areas of China. The preliminary results showed that mean TGM concentrations were in the range of 1.60 – 2.88 ng m-3, with relatively higher levels observed at sites in Eastern China and Southwestern China and lower levels at sites in Northeastern and Northwestern China. TGM concentrations at remote sites of China were also higher than those reported from background sites in North America and Europe, and this is corresponding very well with the Chinese great anthropogenic Hg emissions. Gaseous oxidized mercury (GOM and particulate bounded mercury (PBM were in the ranges of 3.2 – 7.4 pg m−3 and 19.4 – 43.5 pg m-3, respectively. The preliminary result on precipitation showed mean precipitation THg concentrations were in the range of 2.7 – 18.0 ng L-1.
2. Atmospheric mercury deposition to forests in the eastern USA
International Nuclear Information System (INIS)
Risch, Martin R.; DeWild, John F.; Gay, David A.; Zhang, Leiming; Boyer, Elizabeth W.; Krabbenhoft, David P.
2017-01-01
Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007–2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m 2 /yr) and ranged from 2.2 to 23.4 μg/m 2 /yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007–2009 than in 2012–2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can
3. Atmospheric mercury deposition to forests in the eastern USA.
Science.gov (United States)
Risch, Martin R; DeWild, John F; Gay, David A; Zhang, Leiming; Boyer, Elizabeth W; Krabbenhoft, David P
2017-09-01
Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007-2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m 2 /yr) and ranged from 2.2 to 23.4 μg/m 2 /yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007-2009 than in 2012-2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can
4. Net atmospheric mercury deposition to Svalbard: Estimates from lacustrine sediments
Science.gov (United States)
Drevnick, Paul E.; Yang, Handong; Lamborg, Carl H.; Rose, Neil L.
2012-11-01
In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5 ± 3.3 μg m-2 y-1 and 7.0 ± 3.0 μg m-2 y-1, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.
5. A 320 Year Ice-Core Record of Atmospheric Hg Pollution in the Altai, Central Asia.
Science.gov (United States)
Eyrikh, Stella; Eichler, Anja; Tobler, Leonhard; Malygina, Natalia; Papina, Tatyana; Schwikowski, Margit
2017-10-17
Anthropogenic emissions of the toxic heavy metal mercury (Hg) have substantially increased atmospheric Hg levels during the 20th century compared to preindustrial times. However, on a regional scale, atmospheric Hg concentration or deposition trends vary to such an extent during the industrial period that the consequences of recent Asian emissions on atmospheric Hg levels are still unclear. Here we present a 320 year Hg deposition history for Central Asia, based on a continuous high-resolution ice-core Hg record from the Belukha glacier in the Siberian Altai, covering the time period 1680-2001. Hg concentrations and deposition fluxes start rising above background levels at the beginning of the 19th century due to emissions from gold/silver mining and Hg production. A steep increase occurs after the 1940s culminating during the 1970s, at the same time as the maximum Hg use in consumer products in Europe and North America. After a distinct decrease in the 1980s, Hg levels in the 1990s and beginning of the 2000s return to their maximum values, which we attribute to increased Hg emissions from Asia. Thus, rising Hg emissions from coal combustion and artisanal and small-scale gold mining (ASGM) in Asian countries determine recent atmospheric Hg levels in Central Asia, counteracting emission reductions due to control measures in Europe and North America.
6. Trade-Induced Atmospheric Mercury Deposition over China and Implications for Demand-Side Controls.
Science.gov (United States)
Chen, Long; Meng, Jing; Liang, Sai; Zhang, Haoran; Zhang, Wei; Liu, Maodian; Tong, Yindong; Wang, Huanhuan; Wang, Wei; Wang, Xuejun; Shu, Jiong
2018-02-20
Mercury (Hg) is of global concern because of its adverse effects on humans and the environment. In addition to long-range atmospheric transport, Hg emissions can be geographically relocated through economic trade. Here, we investigate the effect of China's interregional trade on atmospheric Hg deposition over China, using an atmospheric transport model and multiregional input-output analysis. In general, total atmospheric Hg deposition over China is 408.8 Mg yr -1 , and 32% of this is embodied in China's interregional trade, with the hotspots occurring over Gansu, Henan, Hebei, and Yunnan provinces. Interprovincial trade considerably redistributes atmospheric Hg deposition over China, with a range in deposition flux from -104% to +28%. Developed regions, such as the Yangtze River Delta (Shanghai, Jiangsu, and Zhejiang) and Guangdong, avoid Hg deposition over their geographical boundaries, instead causing additional Hg deposition over developing provinces. Bilateral interaction among provinces is strong over some regions, suggesting a need for joint mitigation, such as the Jing-Jin-Ji region (Beijing, Tianjin, and Hebei) and the Yangtze River Delta. Transferring advanced technology from developed regions to their developing trade partners would be an effective measure to mitigate China's Hg pollution. Our findings are relevant to interprovincial efforts to reduce trans-boundary Hg pollution in China.
7. Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor
Science.gov (United States)
The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702±318 μg Hg g -1 was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding.
8. Atmospheric mercury deposition and its contribution of the regional atmospheric transport to mercury pollution at a national forest nature reserve, southwest China.
Science.gov (United States)
Ma, Ming; Wang, Dingyong; Du, Hongxia; Sun, Tao; Zhao, Zheng; Wei, Shiqing
2015-12-01
Atmospheric mercury deposition by wet and dry processes contributes to the transformation of mercury from atmosphere to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to subtropical forests were identified in this study. Throughfall and open field precipitation samples were collected in 2012 and 2013 using precipitation collectors from forest sites located across Mt. Jinyun in southwest China. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy was the primary factor on THg and MeHg deposition. Simultaneously, continuous measurements of atmospheric gaseous elemental mercury (GEM) were carried out from March 2012 to February 2013 at the summit of Mt. Jinyun. Atmospheric GEM concentrations averaged 3.8 ± 1.5 ng m(-3), which was elevated compared with global background values. Sources identification indicated that both regional industrial emissions and long-range transport of Hg from central, northeast, and southwest China were corresponded to the elevated GEM levels. Precipitation deposition fluxes of THg and MeHg in Mt. Jinyun were slightly higher than those reported in Europe and North America, whereas total fluxes of MeHg and THg under forest canopy on Mt. Jiuyun were 3 and 2.9 times of the fluxes of THg in wet deposition in the open. Highly elevated litterfall deposition fluxes suggest that even in remote forest areas of China, deposition of atmospheric Hg(0) via uptake by vegetation leaf may be a major pathway for the deposition of atmospheric Hg. The result illustrates that areas with greater atmospheric pollution can be expected to have greater fluxes of Hg to soils via throughfall and litterfall.
9. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources
Science.gov (United States)
Domagalski, Joseph L.; Majewski, Michael S.; Alpers, Charles N.; Eckley, Chris S.; Eagles-Smith, Collin A.; Schenk, Liam N.; Wherry, Susan
2016-01-01
10. Hg localisation in Tillandsia usneoides L. (Bromeliaceae), an atmospheric biomonitor
Energy Technology Data Exchange (ETDEWEB)
Filho, G.M.A. [Instituto de Pesquisas Jardim Botanico do Rio de Janeiro (Brazil). Programa Zona Costeira; Andrade, L.R.; Farina, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Ciencias Biomedicas, Departamento de Anatomia; Malm, O. [Cidade Universitaria, Rio de Janeiro (Brazil). Instituto de Biofisica Carlos Chagas Filho, Laboratorio de Radioisotopos Eduardo Penna Franca
2002-07-01
The Spanish moss, Tillandsia usneoides, has been applied as an atmospheric biomonitor of Hg contamination, although the mechanism of metal plant accumulation has not been understood until now. In the present work, analytical scanning electron microscopy (SEM) was used to localize Hg in T. usneoides exposed to a Hg-air-contaminated area during 15 days. After this period, Hg was determined by the flow injection mercury system, and plants were prepared for SEM observation and energy-dispersive X-ray analysis. A concentration of 2702{+-}318{mu}g Hgg{sup -1} was determined in exposed plants. The presented microanalytical results demonstrated that Hg was partly associated with atmospheric particles deposited upon the plant surface, but it was highly absorbed by the scales, stem and leaves surfaces and less absorbed by epidermal cells of T. usneoides. No Hg was detected in mesophyll parenchyma or in vascular system cells. The great surface adsorption area provided by the scales, in addition to the characteristics of T. usneoides morphology, especially of the node region, are suggested to confer the great capability of T. usneoides in Hg holding. (author)
11. Just passing through --- high Hg deposition to Puerto Rico forest moves quickly off the landscape
Science.gov (United States)
Shanley, J. B.; Willenbring, J. K.; Kaste, J. M.; Occhi, M.; McDowell, W. H.
2012-12-01
Atmospheric mercury (Hg) in wet deposition at the Luquillo Experimental Forest in northeastern Puerto Rico, averages 28 μg m-2 yr-1, higher than any site in the USA Mercury Deposition Network. Despite the high deposition, Hg content of soils, vegetation, and biota are below global averages. The low Hg content of watershed surfaces, coupled with exceptionally high stream total Hg flux, suggest that most of the Hg passes through the watershed with minimal retention. We assessed Hg dynamics in two adjacent watersheds, Rio Icacos underlain by quartz diorite, and Rio Mameyes underlain by volcaniclastic rocks. At both sites, high-flow Hg concentrations approached 100 ng L-1, dominated by particulate Hg. In order to assess the apparent pass-through nature of Hg in this tropical forest, we measured 7Be and 10Be isotopes from natural, cosmogenic fallout adsorbed on stream suspended particles to constrain the Hg age /residence time and source (atmospheric vs. geogenic or legacy Hg from 19th century gold mining). Ubiquitous 7Be (half-life 53 days) and relatively high 7Be/10Be ratios on suspended particles suggest that stream Hg was dominated by erosion from exposed surfaces, supporting a short residence time. The low watershed retention of the high Hg throughput limits adverse biological effects in this tropical ecosystem.
12. Comparison of mercury mass loading in streams to atmospheric deposition in watersheds of Western North America: Evidence for non-atmospheric mercury sources
Science.gov (United States)
Domagalski, Joseph L.; Majewski, Michael S.; Alpers, Charles N.; Eckley, Chris S.; Eagles-Smith, Collin A.; Schenk, Liam N.; Wherry, Susan
2016-01-01
13. Atmospheric gaseous elemental mercury (GEM concentrations and mercury depositions at a high-altitude mountain peak in south China
Directory of Open Access Journals (Sweden)
X. W. Fu
2010-03-01
Full Text Available China is regarded as the largest contributor of mercury (Hg to the global atmospheric Hg budget. However, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric gaseous elemental mercury (GEM were carried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Simultaneously, deposition fluxes of THg and MeHg in precipitation, throughfall and litterfall were also studied. Atmospheric GEM concentrations averaged 2.80±1.51 ng m−3, which was highly elevated compared to global background values but much lower than semi-rural and industrial/urban areas in China. Sources identification indicates that both regional industrial emissions and long range transport of Hg from central, south and southwest China were corresponded to the elevated GEM level. Seasonal and diurnal variations of GEM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Precipitation and throughfall deposition fluxes of THg and MeHg in Mt. Leigong were comparable or lower compared to those reported in Europe and North America, whereas litterfall deposition fluxes of THg and MeHg were higher compared to Europe and North America. This highlights the importance of vegetation to Hg atmospheric cycling. In th remote forest ecosystem of China, deposition of GEM via uptake of foliage followed by litterfall was very important for the depletion of atmospheric Hg. Elevated GEM level in ambient air may accelerate the foliar uptake of Hg through air which may partly explain the elevated litterfall deposition fluxes of Hg observed in Mt. Leigong.
14. Atmospheric deposition of mercury in central Poland: Sources and seasonal trends
Science.gov (United States)
Siudek, Patrycja; Kurzyca, Iwona; Siepak, Jerzy
2016-03-01
Atmospheric deposition of total mercury was studied at two sites in central Poland, between April 2013 and October 2014. Hg in rainwater (bulk deposition) was analyzed in relation to meteorological parameters and major ions (H+, NO3-, Cl-, SO42 -) in order to investigate seasonal variation, identify sources and determine factors affecting atmospheric Hg chemistry and deposition. Total mercury concentrations varied between 1.24 and 22.1 ng L- 1 at the urban sampling site (Poznań) and between 0.57 and 18.3 ng L- 1 in the woodland protected area (Jeziory), with quite similar mean values of 6.96 and 6.37 ng L- 1, respectively. Mercury in precipitation exhibited lower spatial variability within the study domain (urban/forest transect) than the concentrations determined during other similar observations, reflecting the predominant influence of the same local sources. In our study, a significant seasonal pattern of Hg deposition was observed at both sampling sites, with higher and more variable concentrations of Hg reported for the urban area. In particular, deposition values of Hg were higher in the samples attributed to relatively large precipitation amounts in the summer and in those collected during the winter season (the result of higher contributions from combustion sources, i.e. intensive combustion of fossil fuels in residential and commercial boilers, individual power/heat-generating plants). In addition, a significant relationship between Hg concentration and precipitation amount was found while considering different types of wintertime samples (i.e. rain, snow and mixed precipitation). The analysis of backward trajectories showed that air masses arriving from polluted regions of western Europe and southern Poland largely affected the amount of Hg in rainwater. A seasonal variation in Hg deposition fluxes was also observed, with the maximum value of Hg in spring and minimum in winter. Our results indicated that rainwater Hg and, consequently, the wet deposition
15. Elevated atmospheric deposition and dynamics of mercury in a remote upland forest of southwestern China
International Nuclear Information System (INIS)
Fu Xuewu; Feng Xinbin; Zhu Wanze; Rothenberg, S.; Yao Heng; Zhang Hui
2010-01-01
Mt. Gongga area in southwest China was impacted by Hg emissions from industrial activities and coal combustion, and annual means of atmospheric TGM and PHg concentrations at a regional background station were 3.98 ng m -3 and 30.7 pg m -3 , respectively. This work presents a mass balance study of Hg in an upland forest in this area. Atmospheric deposition was highly elevated in the study area, with the annual mean THg deposition flux of 92.5 μg m -2 yr -1 . Total deposition was dominated by dry deposition (71.8%), and wet deposition accounted for the remaining 28.2%. Forest was a large pool of atmospheric Hg, and nearly 76% of the atmospheric input was stored in forest soil. Volatilization and stream outflow were identified as the two major pathways for THg losses from the forest, which yielded mean output fluxes of 14.0 and 8.6 μg m -2 yr -1 , respectively. - Upland forest ecosystem is a great sink of atmospheric mercury in southwest China.
16. Meteorological effects on Hg wet deposition in a forested site in the Adirondack region of New York during 2000-2015
Science.gov (United States)
Mao, Huiting; Ye, Zhuyun; Driscoll, Charles
2017-11-01
An analysis of weekly measurement data of mercury (Hg) wet deposition was conducted for Huntington Wildlife Forest (HWF), a forest ecosystem in Upstate New York and a biological Hg hotspot, during 2000-2015. Annual accumulated Hg wet deposition flux was found to decrease at a rate of -0.13 μg m-2 yr-1 (2% yr-1) (p = 0.09), and volume weighted mean (VWM) Hg precipitation concentrations at -0.14 ng L-1 yr-1 (2.5% yr-1) (p = 0.00). In examining data by season, no trends were identified for the two variables. It was found that the North Atlantic Oscillation (NAO) affected Hg wet deposition predominantly in spring, as did the position of the U.S. East Coast trough in summer, which suggests different dominant mechanisms driving Hg wet deposition in different seasons. The impacts of such large scale circulation processes were facilitated via variations in precipitation amounts. This was manifested in spring 2011 with the strongest positive phase of NAO, resulting in the wettest spring with the largest Hg wet deposition flux, and in summer 2007 with the U.S. East Coast trough positioned the farthest out over the Atlantic Ocean, causing the driest summer with the lowest Hg wet deposition flux of the study period. Extreme precipitation amounts in spring could singularly drive the overall long-term trend in Hg wet deposition whereas in summer other factors could just be as important. Similar mechanisms were thought to control the long term variations of Hg wet deposition and precipitation concentrations in all seasons but summer as indicated in their significant correlation in all but summer. Atmospheric concentrations of gaseous oxidized mercury (GOM) and particulate borne mercury (PBM) at HWF over 2009-2015 hardly exhibited correlations with Hg wet deposition or precipitation concentrations. Chemical transport model simulations strongly supported efficient scavenging of oxidized Hg by precipitation resulting in the lowest concentration of GOM in the warm season despite the
17. Modeling the global atmospheric transport and deposition of mercury to the Great Lakes
Directory of Open Access Journals (Sweden)
Mark D. Cohen
2016-07-01
Full Text Available Abstract Mercury contamination in the Great Lakes continues to have important public health and wildlife ecotoxicology impacts, and atmospheric deposition is a significant ongoing loading pathway. The objective of this study was to estimate the amount and source-attribution for atmospheric mercury deposition to each lake, information needed to prioritize amelioration efforts. A new global, Eulerian version of the HYSPLIT-Hg model was used to simulate the 2005 global atmospheric transport and deposition of mercury to the Great Lakes. In addition to the base case, 10 alternative model configurations were used to examine sensitivity to uncertainties in atmospheric mercury chemistry and surface exchange. A novel atmospheric lifetime analysis was used to characterize fate and transport processes within the model. Model-estimated wet deposition and atmospheric concentrations of gaseous elemental mercury (Hg(0 were generally within ∼10% of measurements in the Great Lakes region. The model overestimated non-Hg(0 concentrations by a factor of 2–3, similar to other modeling studies. Potential reasons for this disagreement include model inaccuracies, differences in atmospheric Hg fractions being compared, and the measurements being biased low. Lake Erie, downwind of significant local/regional emissions sources, was estimated by the model to be the most impacted by direct anthropogenic emissions (58% of the base case total deposition, while Lake Superior, with the fewest upwind local/regional sources, was the least impacted (27%. The U.S. was the largest national contributor, followed by China, contributing 25% and 6%, respectively, on average, for the Great Lakes. The contribution of U.S. direct anthropogenic emissions to total mercury deposition varied between 46% for the base case (with a range of 24–51% over all model configurations for Lake Erie and 11% (range 6–13% for Lake Superior. These results illustrate the importance of atmospheric
18. Chemical cycling and deposition of atmospheric mercury in polar regions: review of recent measurements and comparison with models
Directory of Open Access Journals (Sweden)
H. Angot
2016-08-01
Full Text Available Mercury (Hg is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions to deposition of Hg onto environmental surfaces, large uncertainties arise from our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission. Atmospheric Hg reactivity is exacerbated in high latitudes and there is still much to be learned from polar regions in terms of atmospheric processes. This paper provides a synthesis of the atmospheric Hg monitoring data available in recent years (2011–2015 in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. The cycle of atmospheric Hg in the Arctic and in Antarctica presents both similarities and differences. Coastal sites in the two regions are both influenced by springtime atmospheric Hg depletion events and by summertime snowpack re-emission and oceanic evasion of Hg. The cycle of atmospheric Hg differs between the two regions primarily because of their different geography. While Arctic sites are significantly influenced by northern hemispheric Hg emissions especially in winter, coastal Antarctic sites are significantly influenced by the reactivity observed on the East Antarctic ice sheet due to katabatic winds. Based on the comparison of multi-model simulations with observations, this paper discusses whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models and identifies research gaps in our understanding of the atmospheric Hg cycling in high latitudes.
19. Mobility and contamination assessment of mercury in coal fly ash, atmospheric deposition, and soil collected from Tianjin, China.
Science.gov (United States)
Wei, Zheng; Wu, Guanghong; Su, Ruixian; Li, Congwei; Liang, Peiyu
2011-09-01
Samples of class F coal fly ash (levels I, II, and III), slag, coal, atmospheric deposition, and soils collected from Tianjin, China, were analyzed using U.S. Environmental Protection Agency (U.S. EPA) Method 3052 and a sequential extraction procedure, to investigate the pollution status and mobility of Hg. The results showed that total mercury (HgT) concentrations were higher in level I fly ash (0.304 µg/g) than in level II and level III fly ash and slag (0.142, 0.147, and 0.052 µg/g, respectively). Total Hg in the atmospheric deposition was higher during the heating season (0.264 µg/g) than the nonheating season (0.135 µg/g). Total Hg contents were higher in suburban area soils than in rural and agricultural areas. High HgT concentrations in suburban area soils may be a result of the deposition of Hg associated with particles emitted from coal-fired power plants. Mercury in fly ash primarily existed as elemental Hg, which accounted for 90.1, 85.3, and 90.6% of HgT in levels I, II, and III fly ash, respectively. Mercury in the deposition existed primarily as sulfide Hg, which accounted for 73.8% (heating season) and 74.1% (nonheating season) of HgT. However, Hg in soils existed primarily as sulfide Hg, organo-chelated Hg and elemental Hg, which accounted for 37.8 to 50.0%, 31.7 to 41.8%, and 13.0 to 23.9% of HgT, respectively. The percentage of elemental Hg in HgT occurred in the order fly ash > atmospheric deposition > soils, whereas organo-chelated Hg and sulfide Hg occurred in the opposite order. The present approach can provide a window for understanding and tracing the source of Hg in the environment in Tianjin and the risk associated with Hg bioaccessibility. Copyright © 2011 SETAC.
20. GNAQPMS-Hg v1.0, a global nested atmospheric mercury transport model: model description, evaluation and application to trans-boundary transport of Chinese anthropogenic emissions
Science.gov (United States)
Chen, H. S.; Wang, Z. F.; Li, J.; Tang, X.; Ge, B. Z.; Wu, X. L.; Wild, O.; Carmichael, G. R.
2015-09-01
Atmospheric mercury (Hg) is a toxic pollutant and can be transported over the whole globe due to its long lifetime in the atmosphere. For the purpose of assessing Hg hemispheric transport and better characterizing regional Hg pollution, a global nested atmospheric Hg transport model (GNAQPMS-Hg - Global Nested Air Quality Prediction Modeling System for Hg) has been developed. In GNAQPMS-Hg, the gas- and aqueous-phase Hg chemistry representing the transformation among three forms of Hg: elemental mercury (Hg(0)), divalent mercury (Hg(II)), and primary particulate mercury (Hg(P)) are calculated. A detailed description of the model, including mercury emissions, gas- and aqueous-phase chemistry, and dry and wet deposition is given in this study. Worldwide observations including extensive data in China have been collected for model evaluation. Comparison results show that the model reasonably simulates the global mercury budget and the spatiotemporal variation of surface mercury concentrations and deposition. Overall, model predictions of annual total gaseous mercury (TGM) and wet deposition agree with observations within a factor of 2, and within a factor of 5 for oxidized mercury and dry deposition. The model performs significantly better in North America and Europe than in East Asia. This can probably be attributed to the large uncertainties in emission inventories, coarse model resolution and to the inconsistency between the simulation and observation periods in East Asia. Compared to the global simulation, the nested simulation shows improved skill at capturing the high spatial variability of surface Hg concentrations and deposition over East Asia. In particular, the root mean square error (RMSE) of simulated Hg wet deposition over East Asia is reduced by 24 % in the nested simulation. Model sensitivity studies indicate that Chinese primary anthropogenic emissions account for 30 and 62 % of surface mercury concentrations and deposition over China, respectively
1. Mass Dependent Fractionation of Hg Isotopes in Source Rocks, Mineral Deposits and Spring Waters of the California Coast Ranges, USA
Science.gov (United States)
Smith, C. N.; Kesler, S. E.; Blum, J. D.; Rytuba, J. J.
2007-12-01
We present here the first study of the isotopic composition of Hg in rocks, ore deposits, and active hydrothermal systems from the California Coast Ranges, one of Earth's largest Hg-depositing systems. The Franciscan Complex and Great Valley Sequence, which form the bedrock in the California Coast Ranges, are intruded and overlain by Tertiary volcanic rocks including the Clear Lake Volcanic Sequence. These rocks contain two types of Hg deposits, hot-spring deposits that form at shallow depths (<300 m) and silica-carbonate deposits that extend to greater depths (200 to 1000 m), as well as active springs and geothermal systems that release Hg to the present surface. The Franciscan Complex and Great Valley Sequence contain clastic sedimentary rocks with higher concentrations of Hg than volcanic rocks of the Clear Lake Volcanic Field. Mean Hg isotope compositions for all three rock units are similar, although the range of values in Franciscan Complex rocks is greater than in either Great Valley or Clear Lake rocks. Hot spring and silica-carbonate Hg deposits have similar average isotopic compositions that are indistinguishable from averages for the three rock units, although δ202Hg values for the Hg deposits have a greater variance than the country rocks. Precipitates from dilute spring and saline thermal waters in the area have similarly large variance and a mean δ202Hg value that is significantly lower than the ore deposits and rocks. These observations indicate there is little or no isotopic fractionation during release of Hg from its source rocks into hydrothermal solutions. Isotopic fractionation does appear to take place during transport and concentration of Hg in deposits, especially in their uppermost parts. Boiling of hydrothermal fluids is likely the most important process causing of the observed Hg isotope fractionation. This should result in the release of Hg with low δ202Hg values into the atmosphere from the top of these hydrothermal systems and a
2. History of atmospheric deposition of Cd, Hg, and Pb in North America: Evidence from lake and peat bog sediments
International Nuclear Information System (INIS)
Norton, S.A.; Dillon, P.J.; Evans, R.D.; Mierle, G.; Kahl, J.S.
1990-01-01
The precipitation chemistry and lake and peat sediment chemistry of three metals emitted to the atmosphere in significant amounts as a result of anthropogenic activity are reviewed. The three metals, Cd, Hg, and Pb, have contrasting source terms, atmospheric residence times, and chemical mobility. Lake and ombrotrophic peat bog sediments record increases in the concentrations and accumulation rates of the metals for most of temperate North America for the last 100 years. These increases are largely related to the burning of coal, smelting of nonferrous metals, the transportation industry, and the industrial production of chlorine. Modern atmospheric fluxes of Cd in central North America are about 1,000 times background fluxes; accumulation rates for Cd in sediments have increased two to 3 times above background, beginning about 100 years ago. Global scale Hg pollution off the atmosphere is suggested by concentrations in northern hemisphere air that are double the Hg content of southern hemisphere air. Accumulation rates of Hg in sediment have approximately doubled in the last 100 years. However, these rates are approximately an order of magnitude less than those for Cd. Modern increases in Pb concentrations are ubiquitous for all lakes examines thus far in North America. Input is from multiple sources and thus the timing of increased accumulation rates in sediment varies across the continent. Typical modern accumulation rates reach maxima at 20 to 30 mg/sq-m/yr, or 100 times that of Cd and 1,000 times that off Hg. Recent decreases in atmospheric lead are reflected in decreases in the accumulation rate of Pb in both lake and peat bog sediment in eastern North America
3. The Influence of Climate Change on Atmospheric Deposition of Mercury in the Arctic—A Model Sensitivity Study
Science.gov (United States)
Hansen, Kaj M.; Christensen, Jesper H.; Brandt, Jørgen
2015-01-01
Mercury (Hg) is a global pollutant with adverse health effects on humans and wildlife. It is of special concern in the Arctic due to accumulation in the food web and exposure of the Arctic population through a rich marine diet. Climate change may alter the exposure of the Arctic population to Hg. We have investigated the effect of climate change on the atmospheric Hg transport to and deposition within the Arctic by making a sensitivity study of how the atmospheric chemistry-transport model Danish Eulerian Hemispheric Model (DEHM) reacts to climate change forcing. The total deposition of Hg to the Arctic is 18% lower in the 2090s compared to the 1990s under the applied Special Report on Emissions Scenarios (SRES-A1B) climate scenario. Asia is the major anthropogenic source area (25% of the deposition to the Arctic) followed by Europe (6%) and North America (5%), with the rest arising from the background concentration, and this is independent of the climate. DEHM predicts between a 6% increase (Status Quo scenario) and a 37% decrease (zero anthropogenic emissions scenario) in Hg deposition to the Arctic depending on the applied emission scenario, while the combined effect of future climate and emission changes results in up to 47% lower Hg deposition. PMID:26378551
4. Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.
Science.gov (United States)
Luo, Hong-Wei; Yin, Xiangping; Jubb, Aaron M; Chen, Hongmei; Lu, Xia; Zhang, Weihua; Lin, Hui; Yu, Han-Qing; Liang, Liyuan; Sheng, Guo-Ping; Gu, Baohua
2017-01-01
Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation. Copyright © 2016 Elsevier Ltd. All rights reserved.
5. Spatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016
Science.gov (United States)
Risch, Martin R.; Kenski, Donna M.
2018-01-01
Spatial patterns and temporal changes in atmospheric-mercury (Hg) deposition were examined in a five-state study area in the Midwestern USA where 32% of the stationary sources of anthropogenic Hg emissions in the continental USA were located. An extensive monitoring record for wet and dry Hg deposition was compiled for 2001–2016, including 4666 weekly precipitation samples at 13 sites and 27 annual litterfall-Hg samples at 7 sites. This study is the first to examine these Hg data for the Midwestern USA. The median annual precipitation-Hg deposition at the study sites was 10.4 micrograms per square meter per year (ug/m2/year) and ranged from 5.8 ug/m2/year to 15.0 ug/m2/year. The median annual Hg concentration was 9.4 ng/L. Annual litterfall-Hg deposition had a median of 16.1 ug/m2/year and ranged from 9.7 to 23.4 ug/m2/year. Isopleth maps of annual precipitation-Hg deposition indicated a recurring spatial pattern similar to one revealed by statistical analysis of weekly precipitation-Hg deposition. In that pattern, high Hg deposition in southeastern Indiana was present each year, frequently extending to southern Illinois. Most of central Indiana and central Illinois had similar Hg deposition. Areas with comparatively lower annual Hg deposition were observed in Michigan and Ohio for many years and frequently included part of northern Indiana. The area in southern Indiana where high Hg deposition predominated had the highest number of extreme episodes of weekly Hg deposition delivering up to 15% of the annual Hg load from precipitation in a single week. Modeled 48-h back trajectories indicated air masses for these episodes often arrived from the south and southwest, crossing numerous stationary sources of Hg emissions releasing from 23 to more than 300 kg Hg per year. This analysis suggests that local and regional, rather than exclusively continental or global Hg emissions were likely contributing to the extreme episodes and at least in part, to the spatial
6. Loess as an environmental archive of atmospheric trace element deposition
Science.gov (United States)
Blazina, T.; Winkel, L. H.
2013-12-01
Environmental archives such as ice cores, lake sediment cores, and peat cores have been used extensively to reconstruct past atmospheric deposition of trace elements. These records have provided information about how anthropogenic activities such as mining and fossil fuel combustion have disturbed the natural cycles of various atmospherically transported trace elements (e.g. Pb, Hg and Se). While these records are invaluable for tracing human impacts on such trace elements, they often provide limited information about the long term natural cycles of these elements. An assumption of these records is that the observed variations in trace element input, prior to any assumed anthropogenic perturbations, represent the full range of natural variations. However, records such as those mentioned above which extend back to a maximum of ~400kyr may not capture the potentially large variations of trace element input occurring over millions of years. Windblown loess sediments, often representing atmospheric deposition over time scales >1Ma, are the most widely distributed terrestrial sediments on Earth. These deposits have been used extensively to reconstruct continental climate variability throughout the Quaternary and late Neogene periods. In addition to being a valuable record of continental climate change, loess deposits may represent a long term environmental archive of atmospheric trace element deposition and may be combined with paleoclimate records to elucidate how fluctuations in climate have impacted the natural cycle of such elements. Our research uses the loess-paleosol deposits on the Chinese Loess Plateau (CLP) to quantify how atmospheric deposition of trace elements has fluctuated in central China over the past 6.8Ma. The CLP has been used extensively to reconstruct past changes of East Asian monsoon system (EAM). We present a suite of trace element concentration records (e.g. Pb, Hg, and Se) from the CLP which exemplifies how loess deposits can be used as an
7. Determination of MeHg sources to fish in the St. Louis River, MN, USA, using Hg stable isotopes
Science.gov (United States)
Mercury contamination in the Great Lakes region has become a prevalent concern due to elevated methylmercury (MeHg) levels in fish. While atmospheric deposition of Hg is ubiquitous, releases from legacy point-sources give rise to numerous Areas of Concern (AOCs) across the Great ...
8. Wading bird guano contributes to Hg accumulation in tree island soils in the Florida Everglades
International Nuclear Information System (INIS)
Zhu, Yingjia; Gu, Binhe; Irick, Daniel L.; Ewe, Sharon; Li, Yuncong; Ross, Michael S.; Ma, Lena Q.
2014-01-01
Tree islands are habitat for wading birds and a characteristic landscape feature in the Everglades. A total of 93 surface soil and 3 soil core samples were collected from 7 degraded/ghost and 34 live tree islands. The mean Hg concentration in surface soils of ghost tree islands was low and similar to marsh soil. For live tree islands, Hg concentrations in the surface head region were considerably greater than those in mid and tail region, and marsh soils. Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings (105 μg kg −1 ) and plant leaves (53 μg kg −1 ). In addition, Hg concentrations and δ 15 N values displayed positive correlation in soils influenced by guano. During 1998–2010, estimated annual Hg deposition by guano was 148 μg m −2 yr −1 and ∼8 times the atmospheric deposition. Highlights: • Hg concentrations in the head region of tree islands were the highest. • Hg concentrations in bird guano (286 μg kg −1 ) were significantly higher than those in mammal droppings and plant leaves. • Hg concentrations and δ 15 N values showed positive correlation in soils influenced by guano. • Estimated annual Hg deposition by guano was 148 μg m −2 yr −1 , ∼8 times the atmospheric deposition. -- The annual Hg deposition by bird guano to tree island soils in the Everglades was ∼8 times the atmospheric deposition
9. Atmospheric Metal Pollutants-Archives, Methods, and History
International Nuclear Information System (INIS)
Norton, Stephen A.
2007-01-01
Pollution of the atmosphere with cadmium (Cd), mercury (Hg), and lead (Pb) is a consequence of human activities. Natural archives are necessary to reconstruct the long-term history of metal deposition because accurate measurement of atmospheric deposition is a recent accomplishment. Reconstructions require: (1) accurate determination of concentrations of elements and isotopes, (2) accurate chronology of archives, and (3) archives that faithfully record atmosphere deposition. The most useful long-term archives are accumulations of ice and snow, peat, and lake sediment. Quantification of Cd deposition is uncommon because of its low concentration and substantial chemical mobility. Nonetheless, trends in peat and lake sediment are similar to those of Hg and Pb since ca. 1800 a.d. Both Hg and Pb are relatively chemically immobile and thus the peat and lake archives are believed to record historic trends of atmospheric deposition. Isotopic and concentration studies of Pb indicate a history of northern hemisphere atmospheric pollution extending back prior to 0 a.d. Although measurements of Hg concentration are now routine, isotopic measurements are in their infancy. Some Hg pollution sources have unique isotopic ratios, thereby contributing unique signals to the total Hg. Maximum accumulation rates of Hg and Pb occur up to 10 years later than for Cd (1970s versus 1960s in eastern North America, perhaps slightly later in Europe). By 2004, deposition of Cd, Hg, and Pb had declined from peak values in eastern North America more than 75, 75, and 90%, respectively
10. Determination of heavy metal deposition in the county of Obrenovac (Serbia using mosses as bioindicators, III: Copper (Cu, Iron (Fe and Mercury (Hg
Directory of Open Access Journals (Sweden)
Sabovljević M.
2007-01-01
Full Text Available In this study, the deposition of three heavy metals (Cu, Fe and Hg in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp. and Hypnum cupressiforme in the county of Obrenovac (Serbia is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while long-term atmospheric deposition (in the mosses Bryum argenteum and B. capillare and short-term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme are discussed and given in a table. Areas of the highest contaminations are highlighted.
11. Atmospheric mercury in northern Wisconsin: sources and species
International Nuclear Information System (INIS)
Lamborg, C.H.; Fitzgerald, W.F.; Vandal, G.M.; Rolfhus, K.R.
1995-01-01
The atmospheric chemistry, deposition and transport of mercury (Hg) in the Upper Great Lakes region is being investigated at a near-remote sampling location in northern Wisconsin. Intensive sampling over two years has been completed. A multi-phase collection strategy was used to gain insight into the processes controlling concentrations and chemical/physical speciation of atmospheric Hg. Additional chemical and physical atmospheric determinations were also made during these periods to aid in the interpretation of the Hg determinations. For example, correlations of Hg with ozone, sulfur dioxide and synopticscale meteorological features suggest a regionally discernible signal in Hg. Comparison to isosigma backward air parcel trajectories confirms this regionality and implicates the areas south, southeast and northwest of the size to be source for Hg. Particle-phase Hg (Hg p ) was found to be approximately 40% in an oxidized form, or operationally defined as reactive but was variable. Hg p and other particle constituents show significant correlation and similarity in behavior. These observations support the hypothesis that precipitation-phase Hg arises from the scavenging of atmospheric particulates bearing Hg. Observed concentrations of rain and particle-Hg fit the theoretical expectations for nucleation and below-cloud scavenging. Increases in the Hg/aerosol mass ratio appear to take place during transport. Enrichment of aerosols is taken as evidence of gas/particle conversion which could represent the step linking gas-phase Hg with rain. The refined budget indicates ca. 24% of total deposition is from summer particle dry deposition, and that this deposition also contributes ca. 24% of all reactive Hg deposition. Most deposition occurs during the summer months. 40 refs., 4 figs., 7 tabs
12. Atmospheric deposition exposes Qinling pandas to toxic pollutants.
Science.gov (United States)
Chen, Yi-Ping; Zheng, Ying-Juan; Liu, Qiang; Song, Yi; An, Zhi-Sheng; Ma, Qing-Yi; Ellison, Aaron M
2017-03-01
The giant panda (Ailuropoda melanoleuca) is one of the most endangered animals in the world, and it is recognized worldwide as a symbol for conservation. A previous study showed that wild and captive pandas, especially those of the Qinling subspecies, were exposed to toxicants in their diet of bamboo; the ultimate origin of these toxicants is unknown. Here we show that atmospheric deposition is the most likely origin of heavy metals and persistent organic pollutants (POPs) in the diets of captive and wild Qinling pandas. Average atmospheric deposition was 199, 115, and 49 g·m -2 ·yr -1 in the center of Xi'an City, at China's Shaanxi Wild Animal Research Center (SWARC), and at Foping National Nature Reserve (FNNR), respectively. Atmospheric deposition of heavy metals (As, Cd, Cr, Pb, Hg, Co, Cu, Zn, Mn, and Ni) and POPs was highest at Xi'an City, intermediate at SWARC, and lowest at FNNR. Soil concentrations of the aforementioned heavy metals other than As and Zn also were significantly higher at SWARC than at FNNR. Efforts to conserve Qinling pandas may be compromised by air pollution attendant to China's economic development. Improvement of air quality and reductions of toxic emissions are urgently required to protect China's iconic species. © 2017 by the Ecological Society of America.
13. Huguangyan Maar Lake (SE China): A solid record of atmospheric mercury pollution history in a non-remote region
Science.gov (United States)
Zeng, Yan; Chen, Jingan; Yang, Yongqiong; Wang, Jianxu; Zhu, Zhengjie; Li, Jian
2017-10-01
Mercury is a highly toxic metal that can cause harm to environment and human health. As atmospheric deposition is the main source of total Hg input to aquatic system in remote and pristine regions, almost all the studies on atmospheric Hg pollution history concentrated in these areas, while the studies in non-remote areas are much limited, especially for the long history records. In this study, Huguangyan Maar Lake, an undisturbed lake system at low altitude in China, was selected to reconstruct the atmospheric mercury pollution history. Variation patterns of TOC, Hg and non-residual Sr in the sediment core indicated that, compared to the direct atmospheric Hg deposition, the effect of either Hg scavenging from water column by algae or the catchment inputs of previously deposited Hg on the Hg accumulation in the lake sediment was limited. The sediment Hg content in Huguangyan Lake was mainly controlled by the atmospheric Hg deposition, and thus accurately reflected the atmospheric Hg pollution history. The Hga (Hg content from atmospheric deposition) in Huguangyan Lake presented a comparable variation pattern to that in remote sites. It had the same variation trend as the global atmospheric Hg before 1950 CE, which could be attributed to the Industrial Revolution. After that, it was mainly controlled by Hg emissions from Asian countries. The variation of Hga also indicated that atmospheric Hg deposition accelerated significantly since 2000 CE. This study, along with other investigations in remote sites in China, showed that the sediment Hg in Huguangyan Lake responded to the atmospheric Hg pollution more sensitively than in the alpine regions. It should be noted that, the more intensive acceleration of Hg deposition in Huguangyan Lake may imply that the South of China suffered from much more serious atmospheric Hg pollution than previous studies revealed.
14. Assessment of Global Mercury Deposition through Litterfall.
Science.gov (United States)
Wang, Xun; Bao, Zhengduo; Lin, Che-Jen; Yuan, Wei; Feng, Xinbin
2016-08-16
There is a large uncertainty in the estimate of global dry deposition of atmospheric mercury (Hg). Hg deposition through litterfall represents an important input to terrestrial forest ecosystems via cumulative uptake of atmospheric Hg (most Hg(0)) to foliage. In this study, we estimate the quantity of global Hg deposition through litterfall using statistical modeling (Monte Carlo simulation) of published data sets of litterfall biomass production, tree density, and Hg concentration in litter samples. On the basis of the model results, the global annual Hg deposition through litterfall is estimated to be 1180 ± 710 Mg yr(-1), more than two times greater than the estimate by GEOS-Chem. Spatial distribution of Hg deposition through litterfall suggests that deposition flux decreases spatially from tropical to temperate and boreal regions. Approximately 70% of global Hg(0) dry deposition occurs in the tropical and subtropical regions. A major source of uncertainty in this study is the heterogeneous geospatial distribution of available data. More observational data in regions (Southeast Asia, Africa, and South America) where few data sets exist will greatly improve the accuracy of the current estimate. Given that the quantity of global Hg deposition via litterfall is typically 2-6 times higher than Hg(0) evasion from forest floor, global forest ecosystems represent a strong Hg(0) sink.
15. Pre-industrial and recent (1970-2010) atmospheric deposition of sulfate and mercury in snow on southern Baffin Island, Arctic Canada.
Science.gov (United States)
Zdanowicz, Christian; Kruemmel, Eva; Lean, David; Poulain, Alexandre; Kinnard, Christophe; Yumvihoze, Emmanuel; Chen, JiuBin; Hintelmann, Holger
2015-03-15
Sulfate (SO4(2-)) and mercury (Hg) are airborne pollutants transported to the Arctic where they can affect properties of the atmosphere and the health of marine or terrestrial ecosystems. Detecting trends in Arctic Hg pollution is challenging because of the short period of direct observations, particularly of actual deposition. Here, we present an updated proxy record of atmospheric SO4(2-) and a new 40-year record of total Hg (THg) and monomethyl Hg (MeHg) deposition developed from a firn core (P2010) drilled from Penny Ice Cap, Baffin Island, Canada. The updated P2010 record shows stable mean SO4(2-) levels over the past 40 years, which is inconsistent with observations of declining atmospheric SO4(2-) or snow acidity in the Arctic during the same period. A sharp THg enhancement in the P2010 core ca 1991 is tentatively attributed to the fallout from the eruption of the Icelandic volcano Hekla. Although MeHg accumulation on Penny Ice Cap had remained constant since 1970, THg accumulation increased after the 1980s. This increase is not easily explained by changes in snow accumulation, marine aerosol inputs or air mass trajectories; however, a causal link may exist with the declining sea-ice cover conditions in the Baffin Bay sector. The ratio of THg accumulation between pre-industrial times (reconstructed from archived ice cores) and the modern industrial era is estimated at between 4- and 16-fold, which is consistent with estimates from Arctic lake sediment cores. The new P2010 THg record is the first of its kind developed from the Baffin Island region of the eastern Canadian Arctic and one of very few such records presently available in the Arctic. As such, it may help to bridge the knowledge gap linking direct observation of gaseous Hg in the Arctic atmosphere and actual net deposition and accumulation in various terrestrial media. Copyright © 2014 Elsevier B.V. All rights reserved.
16. Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution.
Science.gov (United States)
Obrist, Daniel; Agnan, Yannick; Jiskra, Martin; Olson, Christine L; Colegrove, Dominique P; Hueber, Jacques; Moore, Christopher W; Sonke, Jeroen E; Helmig, Detlev
2017-07-12
Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through 'atmospheric mercury depletion events', or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(ii)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg(ii) via precipitation or AMDEs. We find that deposition of Hg(0)-the form ubiquitously present in the global atmosphere-occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean.
17. Speciation of Hg in lichens
International Nuclear Information System (INIS)
Jereb, Vesna; Horvat, Milena
2002-01-01
Lichens have long been regarded as a suitable tool for monitoring the relative levels of atmospheric pollutants. Lichens have neither roots, a waxy cuticle nor stomata: hence, for mineral nutrition they are largely dependent on wet and dry deposition from the atmosphere. Moreover, lichens are perennial and can accumulate elements over long periods of time. Therefore, concentrations of elements in lichens represent the average levels of elements in the atmosphere for a long period of time. The epiphytic lichen Hypogymnia physodes is a good bioindicator of air pollution with total mercury (THg). In addition, it contains small amounts of methylmercury (MeHg + ). The first aim of our work was to test analytical techniques for determination of MeHg in lichens taken from different locations in Idrija and reference locations
18. Atmospheric Deposition: Sampling Procedures, Analytical Methods, and Main Recent Findings from the Scientific Literature
Directory of Open Access Journals (Sweden)
M. Amodio
2014-01-01
Full Text Available The atmosphere is a carrier on which some natural and anthropogenic organic and inorganic chemicals are transported, and the wet and dry deposition events are the most important processes that remove those chemicals, depositing it on soil and water. A wide variety of different collectors were tested to evaluate site-specificity, seasonality and daily variability of settleable particle concentrations. Deposition fluxes of POPs showed spatial and seasonal variations, diagnostic ratios of PAHs on deposited particles, allowed the discrimination between pyrolytic or petrogenic sources. Congener pattern analysis and bulk deposition fluxes in rural sites confirmed long-range atmospheric transport of PCDDs/Fs. More and more sophisticated and newly designed deposition samplers have being used for characterization of deposited mercury, demonstrating the importance of rain scavenging and the relatively higher magnitude of Hg deposition from Chinese anthropogenic sources. Recently biological monitors demonstrated that PAH concentrations in lichens were comparable with concentrations measured in a conventional active sampler in an outdoor environment. In this review the authors explore the methodological approaches used for the assessment of atmospheric deposition, from the analysis of the sampling methods, the analytical procedures for chemical characterization of pollutants and the main results from the scientific literature.
19. Chemical bath deposition of Hg doped CdSe thin films and their characterization
International Nuclear Information System (INIS)
Bhuse, V.M.
2005-01-01
The deliberate addition of Hg in CdSe thin film have been carried out using a simple, modified, chemical bath deposition technique with the objective to study the effect of Hg doping on properties of CdSe thin films. Synthesis was initiated at 278 K temperature using complexed cadmium sulphate, mercuric nitrate and sodium selenosulphate in an aqueous ammonical medium at pH 10. Films were characterized by XRD, SEM, optical absorption, electrical and thermoelectric techniques. The 'as deposited' films were uniform, well adherent, nearly stoichiometric and polycrystalline in a single cubic phase (zinc blende). Crystallite size determined from XRD and SEM was found to increase slightly with addition of Hg. The optical band gap of CdSe remains constant upto 0.05 mol% Hg doping, while it decreases monotonically with further increase in mercury content. Dark dc electrical resistivity and conduction activation energy of CdSe were found to decrease initially upto 0.05 mol% of Hg, thereafter increased for higher values of Hg but remains less than those of CdSe. All the films showed n-type of conductivity. A CdSe film containing 0.05 mol% of Hg showed higher absorption coefficient, and conductivity
20. The Kongsberg silver deposits, Norway: Ag-Hg-Sb mineralization and constraints for the formation of the deposits
Science.gov (United States)
2018-04-01
The Kongsberg silver district has been investigated by microscopy and electron microprobe analysis, focusing primarily on the Ag-Hg-Sb mineralization within the context of the updated mineral paragenesis. The earliest mineralization stage is represented by sulfides, including acanthite, and sulfosalts. Native silver formed initially through breakdown of early Ag-bearing phases and later through influx of additional Ag-bearing fluids and silver remobilization. The first two generations of native silver were separated in time by the formation of Ni-Co-Fe sulfarsenides and the monoarsenide niccolite along rims of silver crystals. The presence of As-free sulfosalts and the absence of di- and tri-arsenides suggest a lower arsenic/sulfur activity ratio for the Kongsberg deposits compared to other five-element deposits. Native silver shows binary Ag-Hg and Ag-Sb solid solutions, in contrast to the ternary Ag-Hg-Sb compositions typical for other deposits of similar type. Antimonial silver together with allargentum, dyscrasite, and pyrargyrite was documented exclusively from the northern area of the district. Elsewhere, the only Sb-bearing minerals are polybasite and tetrahedrite/freibergite. Hg-rich silver (up to 21 wt% Hg) has been documented only in the central-western area. Myrmekite of freibergite and chalcopyrite reflects exsolution from an original Ag-poor tetrahedrite upon cooling, while myrmekite of pyrite and silver, forming through breakdown of low-temperature phases (argentopyrite or lenaite) upon heating, characterizes the Kongsberg silver district. Based on the stabilities of minerals and mineral assemblages, the formation of the silver mineralization can be constrained to temperatures between 180 and 250 °C.
1. Identification of atmospheric mercury sources and transport pathways on local and regional sales
Science.gov (United States)
Gratz, Lynne E.
Mercury (Hg) is a hazardous air pollutant and bioaccumulative neurotoxin whose intricate atmospheric chemistry complicates our ability to define Hg source-receptor relationships on all scales. Our detailed measurements of Hg in its different forms together with atmospheric tracers have improved our understanding of Hg chemistry and transport. Daily-event precipitation samples collected from 1995 to 2006 in Underhill, VT were examined to identify Hg wet deposition trends and source influences. Analysis revealed that annual Hg deposition at this fairly remote location did not vary significantly over the 12-year period. While a decreasing trend in volume-weighted mean Hg concentration was observed, Hg wet deposition did not decline as transport of emissions from the Midwest and along the Atlantic Coast consistently contributed to the largest observed Hg wet deposition events. Receptor modeling of Hg and trace elements in precipitation indicated that ---60% of Hg wet deposition at Underhill could be attributed to emissions from coal-fired utility boilers (CFUBs), and their contribution to Hg wet deposition did not change significantly over time. Hybrid-receptor modeling further defined these CFUBs to be located predominantly in the Midwestern U.S. Atmospheric Hg chemistry and transport from the Chicago urban/industrial area was the focus of speciated Hg measurements performed in the southern Lake Michigan basin during summer 2007. Transport from Chicago, IL to Holland, MI occurred during 27% of the study period, resulting in a five-fold increase in divalent reactive gaseous Hg (RGM) at the downwind Holland site. Dispersion modeling of case study periods demonstrated that under southwesterly flow approximately half of the RGM in Holland could be attributed to primary RGM emissions from Chicago after transport and dispersion, with the remainder due to Hg0 oxidation in the atmosphere en route. Precipitation and ambient vapor phase samples were also collected in Chicago
2. Atmospheric deposition of mercury in Atlantic Forest and ecological risk to soil fauna
Science.gov (United States)
Cristhy Buch, Andressa; Cabral Teixeira, Daniel; Fernandes Correia, Maria Elizabeth; Vieira Silva-Filho, Emmanoel
2014-05-01
The increasing levels of mercury (Hg) found in the atmosphere nowadays has a great contribution from anthropogenic sources and has been a great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. Certainly, the petroleum refineries have significant contribution, seen that 100 million m3 of crude oil are annually processed. These refineries contribute with low generation of solid waste; however, a large fraction of Hg can be emitted to the atmosphere. There are sixteen refineries in Brazil, three of them located in the state of Rio de Janeiro. The Hg is a toxic and hazardous trace element, naturally found in the earth crust. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of great importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transfer to the soil through litterfall, which play an important role as Hg sink. The Atlantic Forest of Brazil is the greater contributor of fauna and flora biodiversity in the world and, according to recent studies, this biome has the highest concentrations of mercury in litter in the world, as well as in China, at Subtropical Forest. Ecotoxicological assessments can predict the potential ecological risk of Hg toxicity in the soil can lead to impact the soil fauna and indirectly other trophic levels of the food chain within one or more ecosystems. This study aims to determine mercury levels that represent risks to diversity and functioning of soil fauna in tropical forest soils. The study is conducted in two forest areas inserted into conservation units of Rio de Janeiro state. One area is located next to an important petroleum refinery in activity since fifty-two years ago, whereas the other one is located next to other refinery under construction (beginning activities in 2015), which will
3. Anthropogenic contributions to atmospheric Hg, Pb and As accumulation recorded by peat cores from southern Greenland and Denmark dated using the 14C "bomb pulse curve"
Science.gov (United States)
Shotyk, W.; Goodsite, M. E.; Roos-Barraclough, F.; Frei, R.; Heinemeier, J.; Asmund, G.; Lohse, C.; Hansen, T. S.
2003-11-01
Mercury concentrations are clearly elevated in the surface and sub-surface layers of peat cores collected from a minerotrophic ("groundwater-fed") fen in southern Greenland (GL) and an ombrotrophic ("rainwater-fed") bog in Denmark (DK). Using 14C to precisely date samples since ca. AD 1950 using the "atmospheric bomb pulse," the chronology of Hg accumulation in GL is remarkably similar to the bog in DK where Hg was supplied only by atmospheric deposition: this suggests not only that Hg has been supplied to the surface layers of the minerotrophic core (GL) primarily by atmospheric inputs, but also that the peat cores have preserved a consistent record of the changing rates of atmospheric Hg accumulation. The lowest Hg fluxes in the GL core (0.3 to 0.5 μg/m 2/yr) were found in peats dating from AD 550 to AD 975, compared to the maximum of 164 μg/m 2/yr in AD 1953. Atmospheric Hg accumulation rates have since declined, with the value for 1995 (14 μg/m 2/yr) comparable to the value for 1995 obtained by published studies of atmospheric transport modelling (12 μg/m 2/yr). The greatest rates of atmospheric Hg accumulation in the DK core are also found in the sample dating from AD 1953 and are comparable in magnitude (184 μg/m 2/yr) to the GL core; again, the fluxes have since gone into strong decline. The accumulation rates recorded by the peat core for AD 1994 (14 μg/m 2/yr) are also comparable to the value for 1995 obtained by atmospheric transport modelling (18 μg/m 2/yr). Comparing the Pb/Ti and As/Ti ratios of the DK samples with the corresponding crustal ratios (or "natural background values" for preanthropogenic peat) shows that the samples dating from 1953 also contain the maximum concentration of "excess" Pb and As. The synchroneity of the enrichments of all three elements (Hg, Pb, and As) suggests a common source, with coal-burning the most likely candidate. Independent support for this interpretation was obtained from the Pb isotope data ( 206Pb/ 207Pb
4. Litter mercury deposition in the Amazonian rainforest
International Nuclear Information System (INIS)
Fostier, Anne Hélène; Melendez-Perez, José Javier; Richter, Larissa
2015-01-01
The objective of this work was to assess the flux of atmospheric mercury transferred to the soil of the Amazonian rainforest by litterfall. Calculations were based on a large survey of published and unpublished data on litterfall and Hg concentrations in litterfall samples from the Amazonian region. Litterfall based on 65 sites located in the Amazon rainforest averaged 8.15 ± 2.25 Mg ha"−"1 y"−"1. Average Hg concentrations were calculated from nine datasets for fresh tree leaves and ten datasets for litter, and a median concentration of 60.5 ng Hg g"−"1 was considered for Hg deposition in litterfall, which averaged 49 ± 14 μg m"−"2 yr"−"1. This value was used to estimate that in the Amazonian rainforest, litterfall would be responsible for the annual removing of 268 ± 77 Mg of Hg, approximately 8% of the total atmospheric Hg deposition to land. The impact of the Amazon deforestation on the Hg biogeochemical cycle is also discussed. - Highlights: • Based on published data we estimated the litterfall in the Amazonian rainforest. • All the published data on Hg concentration in leaves and litter from the region and some unpublished data are presented. • We calculated the litter mercury deposition. • We estimated the contribution of dry, wet and litter Hg deposition in the Amazonian rainforest. • We also discussed the impact of Amazon deforestation on the Hg biogeochemical cycle. - The Amazonian rainforest is responsible for removing at least 268 Mg Hg y"−"1, 8% of the total atmospheric mercury deposition to land.
5. A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow
Directory of Open Access Journals (Sweden)
A. J. Poulain
2008-03-01
Full Text Available It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg. This phenomenon is termed atmospheric mercury depletion events (AMDEs and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does
6. Sensitivity model study of regional mercury dispersion in the atmosphere
Science.gov (United States)
Gencarelli, Christian N.; Bieser, Johannes; Carbone, Francesco; De Simone, Francesco; Hedgecock, Ian M.; Matthias, Volker; Travnikov, Oleg; Yang, Xin; Pirrone, Nicola
2017-01-01
Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg0(g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg0(g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more HgII(g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O3 / OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat
7. Characterization of soil fauna under the influence of mercury atmospheric deposition in Atlantic Forest, Rio de Janeiro, Brazil.
Science.gov (United States)
Buch, Andressa Cristhy; Correia, Maria Elizabeth Fernandes; Teixeira, Daniel Cabral; Silva-Filho, Emmanoel Vieira
2015-06-01
The increasing levels of mercury (Hg) found in the atmosphere arising from anthropogenic sources, have been the object of great concern in the past two decades in industrialized countries. Brazil is the seventh country with the highest rate of mercury in the atmosphere. The major input of Hg to ecosystems is through atmospheric deposition (wet and dry), being transported in the atmosphere over large distances. The forest biomes are of strong importance in the atmosphere/soil cycling of elemental Hg through foliar uptake and subsequent transference to the soil through litter, playing an important role as sink of this element. Soil microarthropods are keys to understanding the soil ecosystem, and for such purpose were characterized by the soil fauna of two Units of Forest Conservation of the state of the Rio de Janeiro, inwhich one of the areas suffer quite interference from petrochemicals and industrial anthropogenic activities and other area almost exempts of these perturbations. The results showed that soil and litter of the Atlantic Forest in Brazil tend to stock high mercury concentrations, which could affect the abundance and richness of soil fauna, endangering its biodiversity and thereby the functioning of ecosystems. Copyright © 2015. Published by Elsevier B.V.
8. Atmospheric Mercury Deposition to a Remote Islet in the Subtropical Northwest Pacific Ocean
Science.gov (United States)
Sheu, G.; Lin, N.
2013-12-01
Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean with an area of 1.14 km^2, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is the first study concerning wet Hg deposition to the subtropical NW Pacific Ocean downwind of the East Asian continent, which is the major source region for Hg emissions worldwide. Sample Hg concentrations ranged from 2.25 to 22.33 ng L^-1, with a volume-weighted mean (VWM) concentration of 8.85 ng L^-1. The annual wet Hg deposition flux was 10.18 μg m^-2, about 2.5 times the fluxes measured at sites on the Pacific coast of the USA, supporting the hypothesis that deposition is higher in the western than in the eastern Pacific. Seasonal VWM concentrations were 7.23, 11.58, 7.82, and 9.84 ng L^-1, whereas seasonal wet deposition fluxes were 2.14, 3.45, 2.38, and 2.21 μg m^-2, for spring, summer, fall and winter, respectively. Higher summer wet Hg deposition was a function of both higher rainwater Hg concentration and greater rainfall. The seasonal pattern of rainwater Hg concentrations was the opposite of the general seasonal pattern of the East Asian air pollutant export. Since there is no significant anthropogenic Hg emission source on the islet of Pengjiayu, the observed high summertime rainwater Hg concentration hints at the importance of Hg(0) oxidation and/or scavenging of upper-altitude reactive gaseous Hg (RGM) by deep convection. Direct anthropogenic RGM emissions from the East Asian continent may not contribute significantly to the rainwater Hg concentrations, but anthropogenic Hg(0) emissions could be transported to the upper troposphere or marine boundary layer where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.
9. Atmospheric deposition of trace elements recorded in snow from the Mt. Nyainqêntanglha region, southern Tibetan Plateau.
Science.gov (United States)
Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Chen, Pengfei; Zhang, Guoshuai; Tripathee, Lekhendra
2013-08-01
In May 2009, snowpit samples were collected from a high-elevation glacier in the Mt. Nyainqêntanglha region on the southern Tibetan Plateau. A set of elements (Al, V, Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg and Pb) was analyzed to investigate the concentrations, deposition fluxes of trace elements, and the relative contributions from anthropogenic and natural sources deposited on the southern Tibetan Plateau. Concentrations of most of the trace elements in snowpit samples from the Zhadang glacier are significantly lower than those examined from central Asia (e.g., eastern Tien Shan), with higher concentrations during the non-monsoon season than during the monsoon season. The elements of Al, V, Cr, Mn, Co, and Ni display low crustal enrichment factors (EFs), while Cu, Zn, Cd, Hg, and Pb show high EF values in the snow samples, suggesting anthropogenic inputs are potentially important for these elements in the remote, high-elevation atmosphere on the southern Tibetan Plateau. Together with the fact that the concentration levels of such elements in the Mt. Nyainqêntanglha region are significantly higher than those observed on the south edge of the Tibetan Plateau, our results suggest that the high-elevation atmosphere on the southern Tibetan Plateau may be more sensitive to variations in the anthropogenic emissions of atmospheric trace elements than that in the central Himalayas. Moreover, the major difference between deposition fluxes estimated in our snow samples and those recently measured at Nam Co Station for elements such as Cr and Cu may suggest that atmospheric deposition of some of trace elements reconstructed from snowpits and ice cores could be grossly underestimated on the Tibetan Plateau. Copyright © 2013 Elsevier Ltd. All rights reserved.
10. The role of ENSO in determining the emission, the speciation and the resulting fate of Hg from Biomass Burning, a lesson from the recent past
Science.gov (United States)
De Simone, F.; Hedgecock, I. M.; Cinnirella, S.; Carbone, F.; Sprovieri, F.; Pirrone, N.
2017-12-01
The burning of vegetation is an environmental process that impacts the chemical composition of troposphere on a global scale, and has significant consequences on atmospheric pollution and climate. ENSO influences the alternating patterns of drier and wetter periods in almost all continents, therefore causing a rise in, and varying the timing of, fire activity in numerous regions and ecosystems (Le Page et al). A large amount of legacy Hg is currently buffered in different environmental compartments, including soil and vegetation, due to past and current anthropogenic processes and activities. Biomass Burning (BB) is a major source of atmospheric Hg, and a main driver in recycling this legacy Hg which is eventually re-deposited over land and oceans. Hg from BB is emitted mainly as Hg(0)(g), but a large fraction (up to 30% and more) is released as Hg bound to particulate matter, Hg(p), which is more likely to be deposited close to the fire activity (De Simone et al). Thus, speciation is one of the most important factors in determining the redistribution of Hg, and of the subsequent geographical distribution of its atmospheric deposition. Although the drivers controlling speciation remain uncertain, there is evidence that it depends on burn characteristics and fuel moisture content, which depends on the climatological characteristics of the regions where BB occurs (Obrist et al). The areas where atmospheric Hg is deposited depends ultimately on atmospheric transport, transformation and precipitation patterns, hence the fate of Hg emitted from BB is determined by a complex series of interacting processes and mechanisms, which begin with the release of Hg and continue until deposition. Many of these processes are influenced by ENSO. This modeling study analyses the deposition of Hg from BB using different satellite imagery based products, spanning a number of years, characterized by different ENSO regimes, to evaluate how it impacts BB, the speciation of emitted Hg, and
11. Mercury in stream water at five Czech catchments across a Hg and S deposition gradient
Science.gov (United States)
Navrátil, Tomáš; Shanley, James B.; Rohovec, Jan; Oulehle, Filip; Krám, Pavel; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria
2015-01-01
The Czech Republic was heavily industrialized in the second half of the 20th century but the associated emissions of Hg and S from coal burning were significantly reduced since the 1990s. We studied dissolved (filtered) stream water mercury (Hg) and dissolved organic carbon (DOC) concentrations at five catchments with contrasting Hg and S deposition histories in the Bohemian part of the Czech Republic. The median filtered Hg concentrations of stream water samples collected in hydrological years 2012 and 2013 from the five sites varied by an order of magnitude from 1.3 to 18.0 ng L− 1. The Hg concentrations at individual catchments were strongly correlated with DOC concentrations r from 0.64 to 0.93 and with discharge r from 0.48 to 0.75. Annual export fluxes of filtered Hg from individual catchments ranged from 0.11 to 13.3 μg m− 2 yr− 1 and were highest at sites with the highest DOC export fluxes. However, the amount of Hg exported per unit DOC varied widely; the mean Hg/DOC ratio in stream water at the individual sites ranged from 0.28 to 0.90 ng mg− 1. The highest stream Hg/DOC ratios occurred at sites Pluhův Bor and Jezeří which both are in the heavily polluted Black Triangle area. Stream Hg/DOC was inversely related to mineral and total soil pool Hg/C across the five sites. We explain this pattern by greater soil Hg retention due to inhibition of soil organic matter decomposition at the sites with low stream Hg/DOC and/or by precipitation of a metacinnabar (HgS) phase. Thus mobilization of Hg into streams from forest soils likely depends on combined effects of organic matter decomposition dynamics and HgS-like phase precipitation, which were both affected by Hg and S deposition histories.
12. Deposition of HgTe by electrochemical atomic layer epitaxy (EC-ALE)
CSIR Research Space (South Africa)
Venkatasamy, V
2006-04-01
Full Text Available This paper describes the first instance of HgTe growth by electrochemical atomic layer epitaxy (EC-ALE). EC-ALE is the electrochemical analog of atomic layer epitaxy (ALE) and atomic layer deposition (ALD), all of which are based on the growth...
13. Development of a Ground-Based Atmospheric Monitoring Network for the Global Mercury Observation System (GMOS
Directory of Open Access Journals (Sweden)
Sprovieri F.
2013-04-01
Full Text Available Consistent, high-quality measurements of atmospheric mercury (Hg are necessary in order to better understand Hg emissions, transport, and deposition on a global scale. Although the number of atmospheric Hg monitoring stations has increased in recent years, the available measurement database is limited and there are many regions of the world where measurements have not been extensively performed. Long-term atmospheric Hg monitoring and additional ground-based monitoring sites are needed in order to generate datasets that will offer new insight and information about the global scale trends of atmospheric Hg emissions and deposition. In the framework of the Global Mercury Observation System (GMOS project, a coordinated global observational network for atmospheric Hg is being established. The overall research strategy of GMOS is to develop a state-of-the-art observation system able to provide information on the concentration of Hg species in ambient air and precipitation on the global scale. This network is being developed by integrating previously established ground-based atmospheric Hg monitoring stations with newly established GMOS sites that are located both at high altitude and sea level locations, as well as in climatically diverse regions. Through the collection of consistent, high-quality atmospheric Hg measurement data, we seek to create a comprehensive assessment of atmospheric Hg concentrations and their dependence on meteorology, long-range atmospheric transport and atmospheric emissions.
14. Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres
Science.gov (United States)
Sprovieri, Francesca; Pirrone, Nicola; Bencardino, Mariantonia; D'Amore, Francesco; Angot, Helene; Barbante, Carlo; Brunke, Ernst-Günther; Arcega-Cabrera, Flor; Cairns, Warren; Comero, Sara; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Fu, Xuewu; Garcia, Patricia Elizabeth; Gawlik, Bernd Manfred; Hageström, Ulla; Hansson, Katarina; Horvat, Milena; Kotnik, Jože; Labuschagne, Casper; Magand, Olivier; Martin, Lynwill; Mashyanov, Nikolay; Mkololo, Thumeka; Munthe, John; Obolkin, Vladimir; Ramirez Islas, Martha; Sena, Fabrizio; Somerset, Vernon; Spandow, Pia; Vardè, Massimiliano; Walters, Chavon; Wängberg, Ingvar; Weigelt, Andreas; Yang, Xu; Zhang, Hui
2017-02-01
The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.
15. Optimization studies of HgSe thin film deposition by electrochemical atomic layer epitaxy (EC-ALE)
CSIR Research Space (South Africa)
Venkatasamy, V
2006-06-01
Full Text Available Studies of the optimization of HgSe thin film deposition using electrochemical atomic layer epitaxy (EC-ALE) are reported. Cyclic voltammetry was used to obtain approximate deposition potentials for each element. These potentials were then coupled...
16. Sampling of Atmospheric Precipitation and Deposits for Analysis of Atmospheric Pollution
OpenAIRE
Skarżyńska, K.; Polkowska, Ż; Namieśnik, J.
2006-01-01
This paper reviews techniques and equipment for collecting precipitation samples from the atmosphere (fog and cloud water) and from atmospheric deposits (dew, hoarfrost, and rime) that are suitable for the evaluation of atmospheric pollution. It discusses the storage and preparation of samples for analysis and also presents bibliographic information on the concentration ranges of inorganic and organic compounds in the precipitation and atmospheric deposit samples.
17. Atmospheric emissions of F, As, Se, Hg, and Sb from coal-fired power and heat generation in China.
Science.gov (United States)
Chen, Jian; Liu, Guijian; Kang, Yu; Wu, Bin; Sun, Ruoyu; Zhou, Chuncai; Wu, Dun
2013-02-01
Coal is one of the major energy resources in China, with nearly half of produced Chinese coal used for power and heat generation. The large use of coal for power and heat generation in China may result in significant atmospheric emissions of toxic volatile trace elements (i.e. F, As, Se, Hg, and Sb). For the purpose of estimating the atmospheric emissions from coal-fired power and heat generation in China, a simple method based on coal consumption, concentration and emission factor of trace element was adopted to calculate the gaseous emissions of elements F, As, Se, Hg, and Sb. Results indicate that about 162161, 236, 637, 172, and 33 t F, As, Se, Hg, and Sb, respectively, were introduced into atmosphere from coal combustion by power and heat generation in China in 2009. The atmospheric emissions of F, As, Se, Hg, and Sb by power and heat generation increased from 2005 to 2009 with increasing coal consumptions. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.
18. A Comparison of Mathematical Models of Fish Mercury Concentration as a Function of Atmospheric Mercury Deposition Rate and Watershed Characteristics
Science.gov (United States)
Smith, R. A.; Moore, R. B.; Shanley, J. B.; Miller, E. K.; Kamman, N. C.; Nacci, D.
2009-12-01
Mercury (Hg) concentrations in fish and aquatic wildlife are complex functions of atmospheric Hg deposition rate, terrestrial and aquatic watershed characteristics that influence Hg methylation and export, and food chain characteristics determining Hg bioaccumulation. Because of the complexity and incomplete understanding of these processes, regional-scale models of fish tissue Hg concentration are necessarily empirical in nature, typically constructed through regression analysis of fish tissue Hg concentration data from many sampling locations on a set of potential explanatory variables. Unless the data sets are unusually long and show clear time trends, the empirical basis for model building must be based solely on spatial correlation. Predictive regional scale models are highly useful for improving understanding of the relevant biogeochemical processes, as well as for practical fish and wildlife management and human health protection. Mechanistically, the logical arrangement of explanatory variables is to multiply each of the individual Hg source terms (e.g. dry, wet, and gaseous deposition rates, and residual watershed Hg) for a given fish sampling location by source-specific terms pertaining to methylation, watershed transport, and biological uptake for that location (e.g. SO4 availability, hill slope, lake size). This mathematical form has the desirable property that predicted tissue concentration will approach zero as all individual source terms approach zero. One complication with this form, however, is that it is inconsistent with the standard linear multiple regression equation in which all terms (including those for sources and physical conditions) are additive. An important practical disadvantage of a model in which the Hg source terms are additive (rather than multiplicative) with their modifying factors is that predicted concentration is not zero when all sources are zero, making it unreliable for predicting the effects of large future reductions in
19. Hg Storage and Mobility in Tundra Soils of Northern Alaska
Science.gov (United States)
Olson, C.; Obrist, D.
2017-12-01
Atmospheric mercury (Hg) can be transported over long distances to remote regions such as the Arctic where it can then deposit and temporarily be stored in soils. This research aims to improve the understanding of terrestrial Hg storage and mobility in the arctic tundra, a large receptor area for atmospheric deposition and a major source of Hg to the Arctic Ocean. We aim to characterize spatial Hg pool sizes across various tundra sites and to quantify the mobility of Hg from thawing tundra soils using laboratory mobility experiments. Active layer and permafrost soil samples were collected in the summer of 2014 and 2015 at the Toolik Field Station in northern Alaska (68° 38' N) and along a 200 km transect extending from Toolik to the Arctic Ocean. Soil samples were analyzed for total Hg concentration, bulk density, and major and trace elements. Hg pool sizes were estimated by scaling up Hg soil concentrations using soil bulk density measurements. Mobility of Hg in tundra soils was quantified by shaking soil samples with ultrapure Milli-Q® water as an extracting solution for 24 and 72 hours. Additionally, meltwater samples were collected for analysis when present. The extracted supernatant was analyzed for total Hg, dissolved organic carbon, cations and anions, redox, and ph. Mobility of Hg from soil was calculated using Hg concentrations determined in solid soil samples and in supernatant of soil solution samples. Results of this study show Hg levels in tundra mineral soils that are 2-5 times higher than those observed at temperate sites closer to pollution sources. Most of the soil Hg was located in mineral horizons where Hg mass accounted for 72% of the total soil pool. Soil Hg pool sizes across the tundra sites were highly variable (166 - 1,365 g ha-1; avg. 419 g ha-1) due to the heterogeneity in soil type, bulk density, depth to frozen layer, and soil Hg concentration. Preliminary results from the laboratory experiment show higher mobility of Hg in mineral
20. Atmospheric wet deposition of mercury and other trace elements in Pensacola, Florida
Directory of Open Access Journals (Sweden)
W. M. Landing
2010-05-01
Full Text Available In an effort to understand and quantify the impact of local, regional, and far-distant atmospheric mercury sources to rainfall mercury deposition in the Pensacola, Florida watershed, a program of event-based rainfall sampling was started in late 2004. Modified Aerochem-Metrics wet/dry rainfall samplers were deployed at three sites in the region around the Crist coal-fired power plant and event-based samples were collected continuously for three years. Samples were analyzed for total Hg and a suite of trace elements including Al, As, Ba, Bi, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, La, Li, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Se, Si, Sn, Sr, Th, U, V, and Zn. Nutrients (ammonia and nitrate and major anions (chloride and sulfate were also measured on each sample. Multivariate statistical methods were used to sort these tracers into factors that represent potential source categories contributing to the rainfall chemistry. As, Hg, Sb, Se, Sn, and non sea-salt sulfate were all significantly correlated (R>0.6 with one factor which we interpret as an anthropogenic source term reflecting input from coal combustion throughout the southeastern US. Using ratios of total Hg to volatile elements, we estimate that 22–33% of the rainfall Hg results from coal combustion in the southeastern US with the majority coming from the global background.
1. External quality-assurance project report for the National Atmospheric Deposition Program/National Trends Network and Mercury Deposition Network, 2009-2010
Science.gov (United States)
Wetherbee, Gregory A.; Martin, RoseAnn; Rhodes, Mark F.; Chesney, Tanya A.
2014-01-01
The U.S. Geological Survey operated six distinct programs to provide external quality-assurance monitoring for the National Atmospheric Deposition Program/National Trends Network (NTN) and Mercury Deposition Network (MDN) during 2009–2010. The field-audit program assessed the effects of onsite exposure, sample handling, and shipping on the chemistry of NTN samples; a system-blank program assessed the same effects for MDN. Two interlaboratory-comparison programs assessed the bias and variability of the chemical analysis data from the Central Analytical Laboratory (CAL) and Mercury (Hg) Analytical Laboratory (HAL). The blind-audit program was also implemented for the MDN to evaluate analytical bias in total Hg concentration data produced by the HAL. The co-located-sampler program was used to identify and quantify potential shifts in NADP data resulting from replacement of original network instrumentation with new electronic recording rain gages (E-gages) and precipitation collectors that use optical sensors. The results indicate that NADP data continue to be of sufficient quality for the analysis of spatial distributions and time trends of chemical constituents in wet deposition across the United States. Results also suggest that retrofit of the NADP networks with the new precipitation collectors could cause –8 to +14 percent shifts in NADP annual precipitation-weighted mean concentrations and total deposition values for ammonium, nitrate, sulfate, and hydrogen ion, and larger shifts (+13 to +74 percent) for calcium, magnesium, sodium, potassium, and chloride. The prototype N-CON Systems bucket collector is more efficient in the catch of precipitation in winter than Aerochem Metrics Model 301 collector, especially for light snowfall.
2. Temporal changes in the distribution, methylation, and bioaccumulation of newly deposited mercury in an aquatic ecosystem
Energy Technology Data Exchange (ETDEWEB)
Orihel, Diane M. [Clayton H. Riddell Faculty of Environment, Earth, and Resources, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 (Canada); Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6 (Canada)], E-mail: orihel@ualberta.ca; Paterson, Michael J.; Blanchfield, Paul J.; Bodaly, R.A. [Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6 (Canada); Gilmour, Cynthia C. [Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037 (United States); Hintelmann, Holger [Department of Chemistry, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8 (Canada)
2008-07-15
Our objective was to examine how the behavior of atmospheric mercury (Hg) deposited to boreal lake mesocosms changed over time. We added inorganic Hg enriched in a different stable isotope in each of two years, which allowed us to differentiate between Hg added in the first and second year. Although inorganic Hg and methylmercury (MeHg) continued to accumulate in sediments throughout the experiment, the availability of MeHg to the food web declined within one year. This decrease was detected in periphyton, zooplankton, and water mites, but not in gomphid larvae, amphipods, or fish. We suggest that reductions in atmospheric Hg deposition should lead to decreases in MeHg concentrations in biota, but that changes will be more easily detected in short-lived pelagic species than long-lived species associated with benthic food webs. - Mercury deposited to aquatic ecosystems becomes less available for uptake by biota over time.
3. Atmospheric deposition 2000. NOVA 2003; Atmosfaerisk deposition 2000. NOVA 2003
Energy Technology Data Exchange (ETDEWEB)
Ellermann, T.; Hertel, O.; Hovmand, M.F.; Kemp, K.; Skjoeth, C.A.
2001-11-01
This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2000. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorus and sulphur compounds related to eutrophication and acidification. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. Measurements: In 2000 the monitoring program consisted of eight stations where wet deposition of ammonium, nitrate, phosphate (semi quantitatively) and sulphate were measured using bulk precipitation samplers. Six of the stations had in addition measurements of atmospheric content of A, nitrogen, phosphorus, and sulphur compounds in gas and particulate phase carried out by use of filter pack samplers. Filters were analysed at the National Environmental Research Institute. Furthermore nitrogen dioxide were measured using nitrogen dioxide filter samplers and monitors. Model calculations: The measurements in the monitoring program were supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surface, marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data as input. The advantage of combining measurements with model calculations is that the strengths of both methods is obtained. Conclusions concerning: 1) actual concentration levels at the monitoring stations, 2) deposition at the monitoring stations, 3) seasonal variations and 4) long term trends in concentrations and depositions are mainly based on the direct measurements. These are furthermore used to validate the results of the model calculations. Calculations and conclusions concerning: 1) depositions to land surface and to the individual marine water, 2) contributions from different emission
4. Litter mercury deposition in the Amazonian rainforest.
Science.gov (United States)
Fostier, Anne Hélène; Melendez-Perez, José Javier; Richter, Larissa
2015-11-01
The objective of this work was to assess the flux of atmospheric mercury transferred to the soil of the Amazonian rainforest by litterfall. Calculations were based on a large survey of published and unpublished data on litterfall and Hg concentrations in litterfall samples from the Amazonian region. Litterfall based on 65 sites located in the Amazon rainforest averaged 8.15 ± 2.25 Mg ha(-1) y(-1). Average Hg concentrations were calculated from nine datasets for fresh tree leaves and ten datasets for litter, and a median concentration of 60.5 ng Hg g(-1) was considered for Hg deposition in litterfall, which averaged 49 ± 14 μg m(-2) yr(-1). This value was used to estimate that in the Amazonian rainforest, litterfall would be responsible for the annual removing of 268 ± 77 Mg of Hg, approximately 8% of the total atmospheric Hg deposition to land. The impact of the Amazon deforestation on the Hg biogeochemical cycle is also discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.
5. Achieving uniform layer deposition by atmospheric-pressure plasma-enhanced chemical vapor deposition
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae-Ok [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Kang, Woo Seok, E-mail: kang@kimm.re.kr [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Department of Environment & Energy Mechanical Engineering, University of Science & Technology (UST), Daejeon 305-350 (Korea, Republic of); Hur, Min; Lee, Jin Young [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Song, Young-Hoon [Department of Plasma Engineering, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343 (Korea, Republic of); Department of Environment & Energy Mechanical Engineering, University of Science & Technology (UST), Daejeon 305-350 (Korea, Republic of)
2015-12-31
This work investigates the use of plasma-enhanced chemical vapor deposition under atmospheric pressure for achieving uniform layer formation. Electrical and optical measurements demonstrated that the counterbalance between oxygen and precursors maintained the homogeneous discharge mode, while creating intermediate species for layer deposition. Several steps of the deposition process of the layers, which were processed on a stationary stage, were affected by flow stream and precursor depletion. This study showed that by changing the flow streamlines using substrate stage motion uniform layer deposition under atmospheric pressure can be achieved. - Highlights: • Zirconium oxide was deposited by atmospheric-pressure plasma-enhanced chemical vapor deposition. • Homogeneous plasma was maintained by counterbalancing between discharge gas and precursors. • Several deposition steps were observed affected by the gas flow stream and precursor depletion. • Thin film layer was uniformly grown when the substrate underwent a sweeping motion.
6. Assessment of atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana using epiphytic lichens
Energy Technology Data Exchange (ETDEWEB)
Boamponsem, L.K. [Department of Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, University Post Office, Kumasi (Ghana); Department of Laboratory Technology, School of Physical Sciences, University of Cape Coast, Cape Coast (Ghana); Adam, J.I. [Department of Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science and Technology, University Post Office, Kumasi (Ghana); Dampare, S.B., E-mail: dampare@cc.okayama-u.ac.j [National Nuclear Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana); Department of Earth Sciences, Okayama University, 1-1, Tsushima-Naka 3-Chome, Okayama 700-8530 (Japan); Nyarko, B.J.B. [National Nuclear Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon-Accra (Ghana); Essumang, D.K. [Department of Laboratory Technology, School of Physical Sciences, University of Cape Coast, Cape Coast (Ghana)
2010-05-01
In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area.
7. Assessment of atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana using epiphytic lichens
International Nuclear Information System (INIS)
Boamponsem, L.K.; Adam, J.I.; Dampare, S.B.; Nyarko, B.J.B.; Essumang, D.K.
2010-01-01
In situ lichens (Parmelia sulcata) have been used to assess atmospheric heavy metal deposition in the Tarkwa gold mining area of Ghana. Total heavy metal concentrations obtained by instrumental neutron activation analysis (INAA) were processed by positive matrix factorization (PMF), principal component (PCA) and cluster (CA) analyses. The pollution index factor (PIF) and pollution load index (PLI) criteria revealed elevated levels of Sb, Mn, Cu, V, Al, Co, Hg, Cd and As in excess of the background values. The PCA and CA classified the examined elements into anthropogenic and natural sources, and PMF resolved three primary sources/factors: agricultural activities and other non-point anthropogenic origins, natural soil dust, and gold mining activities. Gold mining activities, which are characterized by dominant species of Sb, Th, As, Hg, Cd and Co, and significant contributions of Cu, Al, Mn and V, are the main contributors of heavy metals in the atmosphere of the study area.
8. Sensitivity of stream methyl Hg concentrations to environmental change in the Adirondack mountains of New York, USA
Science.gov (United States)
Doug Burns; Karen Riva Murray; Elizabeth A. Nystrom; David M. Wolock; Geofrey Millard; Charles T. Driscoll
2016-01-01
The Adirondacks of New York have high levels of mercury (Hg) bioaccumulation as demonstrated by a region-wide fish consumption advisory for children and women who may become pregnant. The source of this Hg is atmospheric deposition that originates from regional, continental, and global emissions.
9. Thermal stability of atomic layer deposition Al2O3 film on HgCdTe
Science.gov (United States)
Zhang, P.; Sun, C. H.; Zhang, Y.; Chen, X.; He, K.; Chen, Y. Y.; Ye, Z. H.
2015-06-01
Thermal stability of Atomic Layer Deposition Al2O3 film on HgCdTe was investigated by Al2O3 film post-deposition annealing treatment and Metal-Insulator-Semiconductor device low-temperature baking treatment. The effectiveness of Al2O3 film was evaluated by measuring the minority carrier lifetime and capacitance versus voltage characteristics. After annealing treatment, the minority carrier lifetime of the HgCdTe sample presented a slight decrease. Furthermore, the fixed charge density and the slow charge density decreased significantly in the annealed MIS device. After baking treatment, the fixed charge density and the slow charge density of the unannealed and annealed MIS devices decreased and increased, respectively.
10. Characterizations of wet mercury deposition on a remote high-elevation site in the southeastern Tibetan Plateau.
Science.gov (United States)
Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Sillanpää, Mika; Wang, Yongjie; Sun, Shiwei; Sun, Xuejun; Tripathee, Lekhendra
2015-11-01
Accurate measurements of wet mercury (Hg) deposition are critically important for the assessment of ecological responses to pollutant loading. The Hg in wet deposition was measured over a 3-year period in the southeastern Tibetan Plateau. The volume-weighted mean (VWM) total Hg (HgT) concentration was somewhat lower than those reported in other regions of the Tibetan Plateau, but the VWM methyl-Hg concentration and deposition flux were among the highest globally reported values. The VWM HgT concentration was higher in non-monsoon season than in monsoon season, and wet HgT deposition was dominated by the precipitation amount rather than the scavenging of atmospheric Hg by precipitation. The dominant Hg species in precipitation was mainly in the form of dissolved Hg, which indicates the pivotal role of reactive gaseous Hg within-cloud scavenging to wet Hg deposition. Moreover, an increasing trend in precipitation Hg concentrations was synchronous with the recent economic development in South Asia. Copyright © 2015 Elsevier Ltd. All rights reserved.
11. Mercury stable isotope signatures of world coal deposits and historical coal combustion emissions.
Science.gov (United States)
Sun, Ruoyu; Sonke, Jeroen E; Heimbürger, Lars-Eric; Belkin, Harvey E; Liu, Guijian; Shome, Debasish; Cukrowska, Ewa; Liousse, Catherine; Pokrovsky, Oleg S; Streets, David G
2014-07-01
Mercury (Hg) emissions from coal combustion contribute approximately half of anthropogenic Hg emissions to the atmosphere. With the implementation of the first legally binding UNEP treaty aimed at reducing anthropogenic Hg emissions, the identification and traceability of Hg emissions from different countries/regions are critically important. Here, we present a comprehensive world coal Hg stable isotope database including 108 new coal samples from major coal-producing deposits in South Africa, China, Europe, India, Indonesia, Mongolia, former USSR, and the U.S. A 4.7‰ range in δ(202)Hg (-3.9 to 0.8‰) and a 1‰ range in Δ(199)Hg (-0.6 to 0.4‰) are observed. Fourteen (p coal Hg emissions tracing. A revised coal combustion Hg isotope fractionation model is presented, and suggests that gaseous elemental coal Hg emissions are enriched in the heavier Hg isotopes relative to oxidized forms of emitted Hg. The model explains to first order the published δ(202)Hg observations on near-field Hg deposition from a power plant and global scale atmospheric gaseous Hg. Yet, model uncertainties appear too large at present to permit straightforward Hg isotope source identification of atmospheric forms of Hg. Finally, global historical (1850-2008) coal Hg isotope emission curves were modeled and indicate modern-day mean δ(202)Hg and Δ(199)Hg values for bulk coal emissions of -1.2 ± 0.5‰ (1SD) and 0.05 ± 0.06‰ (1SD).
12. Mercury from combustion sources: a review of the chemical species emitted and their transport in the atmosphere
International Nuclear Information System (INIS)
Carpi, A.
1997-01-01
Different species of mercury have different physical/chemical properties and thus behave quite differentially in air pollution control equipment and in the atmosphere. In general, emission of mercury from coal combustion sources are approximately 20-50% elemental mercury (Hg 0 ) and 50-80% divalent mercury (Hg(II)), which may be predominantly HgCl 2 . Emissions of mercury from waste incinerators are approximately 10-20% Hg 0 and 75-85% Hg(II). The partitioning of mercury in flue gas between the elemental and divalent forms may be dependent on the concentration of particulate carbon, HCl and other pollutants in the stack emissions. The emission of mercury from combustion facilities depends on the species in the exhaust stream and the type of air pollution control equipment used at the source. Air pollution control equipment for mercury removal at combustion facilities includes activated carbon injection, sodium sulfide injection and wet lime/limestone flue gas desulfurization. White Hg(II) is water-soluble and may be removed form the atmosphere by wet and dry deposition close to the combustion sources, the combination of a high vapor pressure and low water-solubility facilitate the long-range transport of Hg 0 in the atmosphere. Background mercury in the atmosphere is predominantly Hg 0 . Elemental mercury is eventually removed from the atmosphere by dry deposition onto surfaces and by wet deposition after oxidation to water-soluble, divalent mercury. 62 refs., 2 figs., 1 tab
13. Recent Advances in Atmospheric Chemistry of Mercury
Directory of Open Access Journals (Sweden)
Lin Si
2018-02-01
Full Text Available Mercury is one of the most toxic metals and has global importance due to the biomagnification and bioaccumulation of organomercury via the aquatic food web. The physical and chemical transformations of various mercury species in the atmosphere strongly influence their composition, phase, transport characteristics and deposition rate back to the ground. Modeling efforts to assess global cycling of mercury require an accurate understanding of atmospheric mercury chemistry. Yet, there are several key uncertainties precluding accurate modeling of physical and chemical transformations. We focus this article on recent studies (since 2015 on improving our understanding of the atmospheric chemistry of mercury. We discuss recent advances in determining the dominant atmospheric oxidant of elemental mercury (Hg0 and understanding the oxidation reactions of Hg0 by halogen atoms and by nitrate radical (NO3—in the aqueous reduction of oxidized mercury compounds (HgII as well as in the heterogeneous reactions of Hg on atmospheric-relevant surfaces. The need for future research to improve understanding of the fate and transformation of mercury in the atmosphere is also discussed.
14. MEAD Marine Effects of Atmospheric Deposition
Science.gov (United States)
Jickells, T.; Spokes, L.
2003-04-01
The coastal seas are one of the most valuable resources on the planet but they are threatened by human activity. We rely on the coastal area for mineral resources, waste disposal, fisheries and recreation. In Europe, high population densities and high levels of industrial activity mean that the pressures arising from these activities are particularly acute. One of the main problems concerning coastal seas is the rapid increase in the amounts of nitrogen-based pollutants entering the water. They come from many sources, the most important ones being traffic, industry and agriculture. These pollutants can be used by algae as nutrients. The increasing concentrations of these nutrients have led to excessive growth of algae, some of which are harmful. When algae die and decay, oxygen in the water is used up and the resulting lower levels of oxygen may lead to fish kills. Human activity has probably doubled the amount of chemically and biologically reactive nitrogen present globally. In Europe the increases have been greater than this, leading to real concern over the health of coastal waters. Rivers have, until recently, been thought to be the most important source of reactive nitrogen to the coastal seas but we now know that inputs from the atmosphere are large and can equal, or exceed, those from the rivers. Our initial hypothesis was that atmospheric inputs are important and potentially different in their effect on coastal ecosystems to riverine inputs and hence require different management strategies. However, we had almost no information on the direct effects of atmospheric deposition on marine ecosystems, though clearly such a large external nitrogen input should lead to enhanced phytoplankton growth The aim of this European Union funded MEAD project has been to determine how inputs of nitrogen from the atmosphere affect the chemistry and biology of coastal waters. To try to answer this, we have conducted field experiments in the Kattegat, an area where we know
15. The use of Pb, Sr, and Hg isotopes in Great Lakes precipitation as a tool for pollution source attribution
Energy Technology Data Exchange (ETDEWEB)
Sherman, Laura S., E-mail: lsaylors@umich.edu [University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109 (United States); Blum, Joel D. [University of Michigan, Department of Earth and Environmental Sciences, 1100 N. University Ave., Ann Arbor, MI 48109 (United States); Dvonch, J. Timothy [University of Michigan, Air Quality Laboratory, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Gratz, Lynne E. [University of Washington-Bothell, 18115 Campus Way NE, Bothell, WA 98011 (United States); Landis, Matthew S. [U.S. EPA, Office of Research and Development, Research Triangle Park, NC 27709 (United States)
2015-01-01
The anthropogenic emission and subsequent deposition of heavy metals including mercury (Hg) and lead (Pb) present human health and environmental concerns. Although it is known that local and regional sources of these metals contribute to deposition in the Great Lakes region, it is difficult to trace emissions from point sources to impacted sites. Recent studies suggest that metal isotope ratios may be useful for distinguishing between and tracing source emissions. We measured Pb, strontium (Sr), and Hg isotope ratios in daily precipitation samples that were collected at seven sites across the Great Lakes region between 2003 and 2007. Lead isotope ratios ({sup 207}Pb/{sup 206}Pb = 0.8062 to 0.8554) suggest that Pb deposition was influenced by coal combustion and processing of Mississippi Valley-Type Pb ore deposits. Regional differences in Sr isotope ratios ({sup 87}Sr/{sup 86}Sr = 0.70859 to 0.71155) are likely related to coal fly ash and soil dust. Mercury isotope ratios (δ{sup 202}Hg = − 1.13 to 0.13‰) also varied among the sites, likely due to regional differences in coal isotopic composition, and fractionation occurring within industrial facilities and in the atmosphere. These data represent the first combined characterization of Pb, Sr, and Hg isotope ratios in precipitation collected across the Great Lakes region. We demonstrate the utility of multiple metal isotope ratios in parallel with traditional trace element multivariate statistical modeling to enable more complete pollution source attribution. - Highlights: • We measured Pb, Sr, and Hg isotopes in precipitation from the Great Lakes region. • Pb isotopes suggest that deposition was impacted by coal combustion and metal production. • Sr isotope ratios vary regionally, likely due to soil dust and coal fly ash. • Hg isotopes vary due to fractionation occurring within facilities and the atmosphere. • Isotope results support conclusions of previous trace element receptor modeling.
16. High Mercury Wet Deposition at a "Clean Air" Site in Puerto Rico.
Science.gov (United States)
Shanley, James B; Engle, Mark A; Scholl, Martha; Krabbenhoft, David P; Brunette, Robert; Olson, Mark L; Conroy, Mary E
2015-10-20
Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m(-2) yr(-1) wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr(-1). The volume-weighted mean Hg concentration was 9.8 ng L(-1), and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m(-3)). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this "clean air" site suggests that other tropical areas may be hotspots for Hg deposition as well.
17. Impact of Atmospheric Long Range Transport of Lead, Mercury and Cadmium on the Swedish Forest Environment
International Nuclear Information System (INIS)
Johansson, K.; Bergbaeck, B.; Tyler, G.
2001-01-01
Emissions of Hg, Pb, and Cd to air are transported over wide areas in Europe and deposited far away from their sources. About 80% of the atmospheric deposition of these metals in south Sweden originate from emissions in other countries. As a result of the increased anthropogenic deposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainly during the 20th century. Although the atmospheric deposition of these elements has declined during the most recent decades, the reduction of the input of Hg and Pb is not sufficient to prevent a further accumulation. The concentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currently decreasing in a large part of Sweden as a result of both deposition decreases and enhanced leaching induced by soil acidification. The accumulation factors of Hg and Pb, especially in the forest topsoils of south Sweden, are already above those at which adverse effects on soil biological processes and organisms have been demonstrated in studies of gradients from local emission sources and laboratory assessment. There are also indications of such effects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observations in field and laboratory studies. There is an apparent risk of Pb induced reduction in microbial activity over parts of south Sweden. This might cause increased accumulation of organic matter and a reduced availability of soil nutrients. At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increased concentrations of these elements in organs of mammals and birds have also been measured, though decreases have been demonstrated in recent years, related to changes in atmospheric deposition rates. As a result of current and past deposition in south Sweden, concentrations of Hg in fish have increased
18. Feedback mechanisms between snow and atmospheric mercury: Results and observations from field campaigns on the Antarctic plateau.
Science.gov (United States)
Spolaor, Andrea; Angot, Hélène; Roman, Marco; Dommergue, Aurélien; Scarchilli, Claudio; Vardè, Massimiliano; Del Guasta, Massimo; Pedeli, Xanthi; Varin, Cristiano; Sprovieri, Francesca; Magand, Olivier; Legrand, Michel; Barbante, Carlo; Cairns, Warren R L
2018-04-01
The Antarctic Plateau snowpack is an important environment for the mercury geochemical cycle. We have extensively characterized and compared the changes in surface snow and atmospheric mercury concentrations that occur at Dome C. Three summer sampling campaigns were conducted between 2013 and 2016. The three campaigns had different meteorological conditions that significantly affected mercury deposition processes and its abundance in surface snow. In the absence of snow deposition events, the surface mercury concentration remained stable with narrow oscillations, while an increase in precipitation results in a higher mercury variability. The Hg concentrations detected confirm that snowfall can act as a mercury atmospheric scavenger. A high temporal resolution sampling experiment showed that surface concentration changes are connected with the diurnal solar radiation cycle. Mercury in surface snow is highly dynamic and it could decrease by up to 90% within 4/6 h. A negative relationship between surface snow mercury and atmospheric concentrations has been detected suggesting a mutual dynamic exchange between these two environments. Mercury concentrations were also compared with the Br concentrations in surface and deeper snow, results suggest that Br could have an active role in Hg deposition, particularly when air masses are from coastal areas. This research presents new information on the presence of Hg in surface and deeper snow layers, improving our understanding of atmospheric Hg deposition to the snow surface and the possible role of re-emission on the atmospheric Hg concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.
19. Dry deposition fluxes and deposition velocities of trace metals in the Tokyo metropolitan area measured with a water surface sampler.
Science.gov (United States)
Sakata, Masahiro; Marumoto, Kohji
2004-04-01
Dry deposition fluxes and deposition velocities (=deposition flux/atmospheric concentration) for trace metals including Hg, Cd, Cu, Mn, Pb, and Zn in the Tokyo metropolitan area were measured using an improved water surface sampler. Mercury is deposited on the water surface in both gaseous (reactive gaseous mercury, RGM) and particulate (particulate mercury, Hg(p)) forms. The results based on 1 yr observations found that dry deposition plays a significant if not dominant role in trace metal deposition in this urban area, contributing fluxes ranging from 0.46 (Cd) to 3.0 (Zn) times those of concurrent wet deposition fluxes. The deposition velocities were found to be dependent on the deposition of coarse particles larger than approximately 5 microm in diameter on the basis of model calculations. Our analysis suggests that the 84.13% diameter is a more appropriate index for each deposited metal than the 50% diameter in the assumed undersize log-normal distribution, because larger particles are responsible for the flux. The deposition velocities for trace metals other than mercury increased exponentially with an increase in their 84.13% diameters. Using this regression equation, the deposition velocities for Hg(p) were estimated from its 84.13% diameter. The deposition fluxes for Hg(p) calculated from the estimated velocities tended to be close to the mercury fluxes measured with the water surface sampler during the study periods except during summer.
20. High mercury wet deposition at a “clean Air” site in Puerto Rico
Science.gov (United States)
Shanley, James B.; Engle, Mark A.; Scholl, Martha A.; Krabbenhoft, David P.; Brunette, Robert; Olson, Mark L.; Conroy, Mary E.
2015-01-01
Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m–2 yr–1 wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr–1. The volume-weighted mean Hg concentration was 9.8 ng L–1, and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m–3). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this “clean air” site suggests that other tropical areas may be hotspots for Hg deposition as well.
1. Patterned deposition by atmospheric pressure plasma-enhanced spatial atomic layer deposition
NARCIS (Netherlands)
Poodt, P.; Kniknie, B.J.; Branca, A.; Winands, G.J.J.; Roozeboom, F.
2011-01-01
An atmospheric pressure plasma enhanced atomic layer deposition reactor has been developed, to deposit Al2O3 films from trimethyl aluminum and an He/O2 plasma. This technique can be used for 2D patterned deposition in a single in-line process by making use of switched localized plasma sources. It
2. Impact of climate change on mercury concentrations and deposition in the eastern United States.
Science.gov (United States)
Megaritis, Athanasios G; Murphy, Benjamin N; Racherla, Pavan N; Adams, Peter J; Pandis, Spyros N
2014-07-15
The global-regional climate-air pollution modeling system (GRE-CAPS) was applied over the eastern United States to study the impact of climate change on the concentration and deposition of atmospheric mercury. Summer and winter periods (300 days for each) were simulated, and the present-day model predictions (2000s) were compared to the future ones (2050s) assuming constant emissions. Climate change affects Hg(2+) concentrations in both periods. On average, atmospheric Hg(2+) levels are predicted to increase in the future by 3% in summer and 5% in winter respectively due to enhanced oxidation of Hg(0) under higher temperatures. The predicted concentration change of Hg(2+) was found to vary significantly in space due to regional-scale changes in precipitation, ranging from -30% to 30% during summer and -20% to 40% during winter. Particulate mercury, Hg(p) has a similar spatial response to climate change as Hg(2+), while Hg(0) levels are not predicted to change significantly. In both periods, the response of mercury deposition to climate change varies spatially with an average predicted increase of 6% during summer and 4% during winter. During summer, deposition increases are predicted mostly in the western parts of the domain while mercury deposition is predicted to decrease in the Northeast and also in many areas in the Midwest and Southeast. During winter mercury deposition is predicted to change from -30% to 50% mainly due to the changes in rainfall and the corresponding changes in wet deposition. Copyright © 2014 Elsevier B.V. All rights reserved.
3. Characterizations of wet mercury deposition on a remote high-elevation site in the southeastern Tibetan Plateau
International Nuclear Information System (INIS)
Huang, Jie; Kang, Shichang; Zhang, Qianggong; Guo, Junming; Sillanpää, Mika; Wang, Yongjie; Sun, Shiwei
2015-01-01
Accurate measurements of wet mercury (Hg) deposition are critically important for the assessment of ecological responses to pollutant loading. The Hg in wet deposition was measured over a 3-year period in the southeastern Tibetan Plateau. The volume-weighted mean (VWM) total Hg (Hg_T) concentration was somewhat lower than those reported in other regions of the Tibetan Plateau, but the VWM methyl-Hg concentration and deposition flux were among the highest globally reported values. The VWM Hg_T concentration was higher in non-monsoon season than in monsoon season, and wet Hg_T deposition was dominated by the precipitation amount rather than the scavenging of atmospheric Hg by precipitation. The dominant Hg species in precipitation was mainly in the form of dissolved Hg, which indicates the pivotal role of reactive gaseous Hg within-cloud scavenging to wet Hg deposition. Moreover, an increasing trend in precipitation Hg concentrations was synchronous with the recent economic development in South Asia. - Highlights: • The lowest Hg_T concentration in precipitation was found at Southeast Tibet Station. • MeHg concentration and wet deposition flux were among the highest at our study site. • Hg_D dominated the concentration and flux of Hg_T in wet Hg deposition. • A long-term increasing trend in the Hg_T concentration was found at our study site. - An increasing trend in the precipitation Hg concentrations was synchronous with the recent economic development in South Asia.
4. Methodology and significance of studies of atmospheric deposition in highway runoff
Science.gov (United States)
Colman, John A.; Rice, Karen C.; Willoughby, Timothy C.
2001-01-01
Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available.Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Massbudget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and
5. A vegetation control on seasonal variations in global atmospheric mercury concentrations
Science.gov (United States)
Jiskra, Martin; Sonke, Jeroen E.; Obrist, Daniel; Bieser, Johannes; Ebinghaus, Ralf; Myhre, Cathrine Lund; Pfaffhuber, Katrine Aspmo; Wängberg, Ingvar; Kyllönen, Katriina; Worthy, Doug; Martin, Lynwill G.; Labuschagne, Casper; Mkololo, Thumeka; Ramonet, Michel; Magand, Olivier; Dommergue, Aurélien
2018-04-01
Anthropogenic mercury emissions are transported through the atmosphere as gaseous elemental mercury (Hg(0)) before they are deposited to Earth's surface. Strong seasonality in atmospheric Hg(0) concentrations in the Northern Hemisphere has been explained by two factors: anthropogenic Hg(0) emissions are thought to peak in winter due to higher energy consumption, and atmospheric oxidation rates of Hg(0) are faster in summer. Oxidation-driven Hg(0) seasonality should be equally pronounced in the Southern Hemisphere, which is inconsistent with observations of constant year-round Hg(0) levels. Here, we assess the role of Hg(0) uptake by vegetation as an alternative mechanism for driving Hg(0) seasonality. We find that at terrestrial sites in the Northern Hemisphere, Hg(0) co-varies with CO2, which is known to exhibit a minimum in summer when CO2 is assimilated by vegetation. The amplitude of seasonal oscillations in the atmospheric Hg(0) concentration increases with latitude and is larger at inland terrestrial sites than coastal sites. Using satellite data, we find that the photosynthetic activity of vegetation correlates with Hg(0) levels at individual sites and across continents. We suggest that terrestrial vegetation acts as a global Hg(0) pump, which can contribute to seasonal variations of atmospheric Hg(0), and that decreasing Hg(0) levels in the Northern Hemisphere over the past 20 years can be partly attributed to increased terrestrial net primary production.
6. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model
International Nuclear Information System (INIS)
Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B.; Hao, Jiming
2014-01-01
China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35–50% of THg concentration and 50–70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. - Highlights: • China's anthropogenic mercury emission was 643.1 t in 2007. • GEOS-Chem model well reproduces the background Hg concentrations. • Anthropogenic emissions contribute 35–50% of Hg concentrations in polluted regions. • The priorities for mercury control in polluted regions are identified. - Anthropogenic Hg emissions are updated and their impacts on atmospheric mercury concentrations and depositions are quantified for China
7. Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States
Science.gov (United States)
Lei, H.; Liang, X.-Z.; Wuebbles, D. J.; Tao, Z.
2013-11-01
Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry). The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg(0)), reactive mercury (Hg(II)), and particulate mercury (PHg). Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air-sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0) in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0). Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999-2001 period. The resulting surface concentrations of total gaseous mercury (TGM) are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The general reproduction of global TGM concentrations and the overestimation on South Africa indicate that model simulations of TGM are seriously affected by emissions. The comparison to wet deposition indicates that wet deposition patterns
8. Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history.
Science.gov (United States)
Kim, Jihun; Lim, Dhongil; Jung, Dohyun; Kang, Jeongwon; Jung, Hoisoo; Woo, Hanjun; Jeong, Kapsik; Xu, Zhaokai
2018-03-01
We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10 -5 g/m 2 /yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems. Copyright © 2018 Elsevier Ltd. All rights reserved.
9. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions
Science.gov (United States)
Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,
2015-01-01
Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.
10. Total dissolved atmospheric nitrogen deposition in the anoxic Cariaco basin
Science.gov (United States)
Rasse, R.; Pérez, T.; Giuliante, A.; Donoso, L.
2018-04-01
Atmospheric deposition of total dissolved nitrogen (TDN) is an important source of nitrogen for ocean primary productivity that has increased since the industrial revolution. Thus, understanding its role in the ocean nitrogen cycle will help assess recent changes in ocean biogeochemistry. In the anoxic Cariaco basin, the place of the CARIACO Ocean Time-Series Program, the influence of atmospherically-deposited TDN on marine biogeochemistry is unknown. In this study, we measured atmospheric TDN concentrations as dissolved organic (DON) and inorganic (DIN) nitrogen (TDN = DIN + DON) in atmospheric suspended particles and wet deposition samples at the northeast of the basin during periods of the wet (August-September 2008) and dry (March-April 2009) seasons. We evaluated the potential anthropogenic N influences by measuring wind velocity and direction, size-fractionated suspended particles, chemical traces and by performing back trajectories. We found DIN and DON concentration values that ranged between 0.11 and 0.58 μg-N m-3 and 0.11-0.56 μg-N m-3 in total suspended particles samples and between 0.08 and 0.54 mg-N l-1 and 0.02-1.3 mg-N l-1 in wet deposition samples, respectively. Continental air masses increased DON and DIN concentrations in atmospheric suspended particles during the wet season. We estimate an annual TDN atmospheric deposition (wet + particles) of 3.6 × 103 ton-N year-1 and concluded that: 1) Atmospheric supply of TDN plays a key role in the C and N budget of the basin because replaces a fraction of the C (20% by induced primary production) and N (40%) removed by sediment burial, 2) present anthropogenic N could contribute to 30% of TDN atmospheric deposition in the basin, and 3) reduced DON (gas + particles) should be a significant component of bulk N deposition.
11. Oil sands development and its impact on atmospheric wet deposition of air pollutants to the Athabasca Oil Sands Region, Alberta, Canada
International Nuclear Information System (INIS)
Lynam, Mary M.; Dvonch, J. Timothy; Barres, James A.; Morishita, Masako; Legge, Allan; Percy, Kevin
2015-01-01
Characterization of air pollutant deposition resulting from Athabasca oil sands development is necessary to assess risk to humans and the environment. To investigate this we collected event-based wet deposition during a pilot study in 2010–2012 at the AMS 6 site 30 km from the nearest upgrading facility in Fort McMurray, AB, Canada. Sulfate, nitrate and ammonium deposition was (kg/ha) 1.96, 1.60 and 1.03, respectively. Trace element pollutant deposition ranged from 2 × 10"−"5 - 0.79 and exhibited the trend Hg < Se < As < Cd < Pb < Cu < Zn < S. Crustal element deposition ranged from 1.4 × 10"−"4 – 0.46 and had the trend: La < Ce < Sr < Mn < Al < Fe < Mg. S, Se and Hg demonstrated highest median enrichment factors (130–2020) suggesting emissions from oil sands development, urban activities and forest fires were deposited. High deposition of the elements Sr, Mn, Fe and Mg which are tracers for soil and crustal dust implies land-clearing, mining and hauling emissions greatly impacted surrounding human settlements and ecosystems. - Highlights: • Atmospheric event wet deposition was collected during a 21 month pilot study. • Major ion, anthropogenic and crustal element wet deposition was characterized. • Low precipitation depths attenuated major ion and anthropogenic element deposition. • Oil sands development, urban activities and forest fires contributed to deposition. - In the vicinity of oil sands, monitoring revealed that wet deposition of major ions (SO_4"2"−, NO_3"-, NH_4"+) was highest followed by S and Mg, the latter is a tracer for soil/crustal dust.
12. Wet deposition of mercury in Qingdao, a coastal urban city in China: Concentrations, fluxes, and influencing factors
Science.gov (United States)
Chen, Lufeng; Li, Yanbin; Liu, Chang; Guo, Lina; Wang, Xiulin
2018-02-01
Mercury (Hg) is a global pollutant of public concern because of its high toxicity and capability for worldwide distribution via long-range atmospheric transportation. Wet atmospheric deposition is an important source of Hg in both terrestrial and aquatic environments. Concentrations of various Hg species in precipitation were monitored from March 2016 to February 2017 in a coastal urban area of Qingdao, and their wet deposition fluxes were estimated. The results showed that the volume-weighted mean (VWM) concentrations of total mercury (THg), reactive mercury (RHg), dissolved THg (DTHg), particulate THg (PTHg), total methylmercury (TMeHg), and dissolved and particulate MeHg (DMeHg and PMeHg) in Qingdao's precipitation were 13.6, 1.5, 5.4, 8.2, 0.38, 0.15, and 0.22 ng L-1, respectively, and their annual deposition fluxes were estimated to be 5703.0 (THg), 666.6 (RHg), 2304.0 (DTHg), 3470.4 (PTHg), 161.6 (TMeHg), 64.0 (DMeHg), and 95.7 (PMeHg) ng m-2 y-1, respectively. A relatively high proportion of MeHg in THg was observed in precipitation (3.0 ± 2.6%) possibly due to higher methylation and contributions from an oceanic source to MeHg in the precipitation. Obvious seasonal variations in Hg concentrations and deposition fluxes were observed in the precipitation in Qingdao. Correlation analyses and multiple regression analyses showed that SO2, pH, and NO3- were the controlling factors for THg in precipitation, whereas the MeHg concentration was primarily controlled by the SO2, WS, Cl-, and THg concentrations. PM2.5 and Cl- were the major controlling factors for PMeHg/TMeHg, whereas the TMeHg/THg ratio was mainly influenced by Cl-. The THg and MeHg fluxes were primarily controlled by precipitation, whereas Cl- was also an important factor for the MeHg wet deposition flux. The results of a 72-h backward trajectory analysis in the study region with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated that Hg deposition in Qingdao mainly
13. Global atmospheric model for mercury including oxidation by bromine atoms
Directory of Open Access Journals (Sweden)
C. D. Holmes
2010-12-01
Full Text Available Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model. We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by
14. Accumulation of Mercury (Hg) and Methyl Mercury (Me Hg) Concentrations In Selected Marine Biota From Manjung Coastal Area
International Nuclear Information System (INIS)
Anisa Abdullah; Zaini Hamzah; Ahmad Saat; Ahmad Saat; Abd Khalik Wood; Masitah Alias
2015-01-01
Level of mercury (Hg) and methyl mercury (Me Hg) in marine ecosystem has been intensively studied as these toxic substances could be accumulated in the marine biota. This study is focusing on the Hg and Me Hg content in marine biota in Manjung coastal area. This area has high potential being affected by rapid socio-economic development of Manjung area such as heavy industrial activities (coal fired power plant, iron foundries, port development and factories), agricultural runoff, waste and toxic discharge, quarries, housing constructions. It may has a potential risk when released into the atmosphere and dispersed on the surface of water and continue deposited at the bottom of the water and sediment and being absorbed by marine biota. The concentrations of Hg and Me Hg in marine ecosystem can be adversely affect human health when it enters the food chain. In this study, five species of marine biota including Johnius dussumieri (Ikan Gelama), Pseudorhombus malayanus (Ikan Sebelah), Arius maculatus (Ikan Duri), Portunus pelagicus (Ketam Renjong) and Charybdis natator (Ketam Salib) were collected during rainy and dry seasons. Measurements were carried out using inductively coupled plasma mass spectrometry (ICP-MS) technique. The Hg concentrations for dry and rainy season are in the range 65.13-102.12 μg/ kg and 75.75-106.10 μg/ kg respectively, while for MeHg concentrations for dry and rainy seasons are in the range 4.35-6.26 μg/ kg and 5.42-6.46 μg/ kg, respectively. These results are below the limit set by Malaysia Food Act (1983). Generally, marine biota from the Manjung coastal area is safe to consume due to low value of ingestion dose rate and health risk index (HRI) for human health. (author)
15. Multielement atmospheric deposition study in Croatia using moss biomonitoring, NAA, AAS and GIS technologies
International Nuclear Information System (INIS)
Spiric, Z.; Frontas'eva, M.V.; Gundorina, S.F.; Ostrovnaya, T.M.; Stafilov, T.; Enimiteva, V.; Steinnes, E.; Bukovec, D.
2009-01-01
For the first time the moss biomonitoring technique and two complementary analytical techniques - neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) - were applied to study multielement atmospheric deposition in the Republic of Croatia. Moss samples were collected during the summer 2006 from 98 sites evenly distributed over the country. Sampling was performed in accordance with the LRTAP Convention - ICP Vegetation protocol and sampling strategy of the European Programme on Biomonitoring of Heavy Metal Atmospheric Deposition. Conventional and epithermal neutron activation analyses made it possible to determine concentrations of 41 elements including key heavy metals such as Pb, Cd, Hg, and Cu determined by AAS. Principal component analysis (factor analysis with VARIMAX rotation) was applied to distinguish elements mainly of anthropogenic origin from those predominantly originating from natural sources. Geographical distribution maps of the elements over the sampled territory were constructed using GIS technology. The median values for Croatia are consistent with the corresponding values for all Europe for most elements. It was shown that the Adriatic coastline of Croatia may be considered as an environmentally pristine area. This study was conducted for providing reliable assessment of air quality throughout Croatia and producing information needed for better identification of pollution sources and improving the potential for assessing environmental and health risks in Croatia associated with toxic metals
16. Atmospheric heavy metal deposition accumulated in rural forest soils of southern Scandinavia
DEFF Research Database (Denmark)
Hovmand, Mads Frederik; Kemp, Kaare; Kystol, J.
2008-01-01
Thirty-three years of measurements of atmospheric heavy metal (HM) deposition (bulk precipitation) in Denmark combined with European emission inventories form the basis for calculating a 50-year accumulated atmospheric input to a remote forest plantation on the island of Laesoe. Soil samples taken...... in atmospheric deposition and in soils. The accumulated atmospheric deposition is of the same magnitude as the increase of these metals in the top soil....
17. Effects of historical and modern mining on mercury deposition in southeastern Peru.
Science.gov (United States)
Beal, Samuel A; Jackson, Brian P; Kelly, Meredith A; Stroup, Justin S; Landis, Joshua D
2013-11-19
Both modern anthropogenic emissions of mercury (Hg), primarily from artisanal and small-scale gold mining (ASGM), and preindustrial anthropogenic emissions from mining are thought to have a large impact on present-day atmospheric Hg deposition. We study the spatial distribution of Hg and its depositional history over the past ∼400 years in sediment cores from lakes located regionally proximal (∼90-150 km) to the largest ASGM in Peru and distal (>400 km) to major preindustrial mining centers. Total Hg concentrations in surface sediments from fourteen lakes are typical of remote regions (10-115 ng g(-1)). Hg fluxes in cores from four lakes demonstrate preindustrial Hg deposition in southeastern Peru was spatially variable and at least an order of magnitude lower than previously reported fluxes in lakes located closer to mining centers. Average modern (A.D. 2000-2011) Hg fluxes in these cores are 3.4-6.9 μg m(-2) a(-1), compared to average preindustrial (A.D. 1800-1850) fluxes of 0.8-2.5 μg m(-2) a(-1). Modern Hg fluxes determined from the four lakes are on average 3.3 (±1.5) times greater than their preindustrial fluxes, similar to those determined in other remote lakes around the world. This agreement suggests that Hg emissions from ASGM are likely not significantly deposited in nearby down-wind regions.
18. Atmospheric Deposition of Phosphorus to the Everglades: Concepts, Constraints, and Published Deposition Rates for Ecosystem Management
Directory of Open Access Journals (Sweden)
Garth W. Redfield
2002-01-01
Full Text Available This paper summarizes concepts underlying the atmospheric input of phosphorus (P to ecosystems, published rates of P deposition, measurement methods, and approaches to future monitoring and research. P conveyed through the atmosphere can be a significant nutrient source for some freshwater and marine ecosystems. Particle sources and sinks at the land-air interface produce variation in P deposition from the atmosphere across temporal and spatial scales. Natural plant canopies can affect deposition rates by changing the physical environment and surface area for particle deposition. Land-use patterns can alter P deposition rates by changing particle concentrations in the atmosphere. The vast majority of P in dry atmospheric deposition is conveyed by coarse (2.5 to 10 μm and giant (10 to 100 μm particles, and yet these size fractions represent a challenge for long-term atmospheric monitoring in the absence of accepted methods for routine sampling. Most information on P deposition is from bulk precipitation collectors and wet/dry bucket sampling, both with questionable precision and accuracy. Most published annual rates of P deposition are gross estimates derived from bulk precipitation sampling in locations around the globe and range from about 5 to well over 100 mg P m–2 year–1, although most inland ecosystems receive between 20 and 80 mg P m–2 year–1. Rates below 30 mg P m–2 year–1 are found in remote areas and near coastlines. Intermediate rates of 30 to 50 mg P m–2 year–1 are associated with forests or mixed land use, and rates of 50 to 100 mg P m–2 year–1 or more are often recorded from urban or agricultural settings. Comparison with other methods suggests that these bulk precipitation estimates provide crude boundaries around actual P deposition rates for various land uses. However, data screening cannot remove all positive bias caused by contamination of bucket or bulk collectors. As a consequence, continued sampling
19. Distribution and air-sea exchange of mercury (Hg) in polluted marine environments
Science.gov (United States)
Bagnato, E.; Sprovieri, M.; Bitetto, M.; Bonsignore, M.; Calabrese, S.; Di Stefano, V.; Oliveri, E.; Parello, F.; Mazzola, S.
2012-04-01
Mercury (Hg) is emitted in the atmosphere by anthropogenic and natural sources, these last accounting for one third of the total emissions. Since the pre-industrial age, the atmospheric deposition of mercury have increased notably, while ocean emissions have doubled owing to the re-emission of anthropogenic mercury. Exchange between the atmosphere and ocean plays an important role in cycling and transport of mercury. We present the preliminary results from a study on the distribution and evasion flux of mercury at the atmosphere/sea interface in the Augusta basin (SE Sicily, southern Italy), a semi-enclosed marine area affected by a high degree of contamination (heavy metals and PHA) due to the oil refineries placed inside its commercial harbor. It seems that the intense industrial activity of the past have lead to an high Hg pollution in the bottom sediments of the basin, whose concentrations are far from the background mercury value found in most of the Sicily Strait sediments. The release of mercury into the harbor seawater and its dispersion by diffusion from sediments to the surface, make the Augusta basin a potential supplier of mercury both to the Mediterranean Sea and the atmosphere. Based on these considerations, mercury concentration and flux at the air-sea interface of the Bay have been estimated using a real-time atomic adsorption spectrometer (LUMEX - RA915+) and an home-made accumulation chamber, respectively. Estimated Total Atmospheric Mercury (TGM) concentrations during the cruise on the bay were in the range of 1-3 ng · m-3, with a mean value of about 1.4 ng · m-3. These data well fit with the background Hgatm concentration values detected on the land (1-2 ng · m-3, this work), and, more in general, with the background atmospheric TGM levels found in the North Hemisphere (1.5-1.7 ng · m-3)a. Besides, our measurements are in the range of those reported for other important polluted marine areas. The mercury evasion flux at the air-sea interface
20. Sulfur accumulation and atmospherically deposited sulfate in the Lake States.
Science.gov (United States)
Mark B. David; George Z. Gernter; David F. Grigal; Lewis F. Ohmann
1989-01-01
Characterizes the mass of soil sulfur (adjusted for nitrogen), and atmospherically deposited sulfate along an acid precipitation gradient from Minnesota to Michigan. The relationship of these variables, presented graphically through contour mapping, suggests that patterns of atmospheric wet sulfate deposition are reflected in soil sulfur pools.
1. Direct and indirect atmospheric deposition of PCBs to the Delaware River watershed.
Science.gov (United States)
Totten, Lisa A; Panangadan, Maya; Eisenreich, Steven J; Cavallo, Gregory J; Fikslin, Thomas J
2006-04-01
Atmospheric deposition can be an important source of PCBs to aquatic ecosystems. To develop the total maximum daily load (TMDL) for polychlorinated biphenyls (PCBs) for the tidal Delaware River (water-quality Zones 2-5), estimates of the loading of PCBs to the river from atmospheric deposition were generated from seven air-monitoring sites along the river. This paper presents the atmospheric PCB data from these sites, estimates direct atmospheric deposition fluxes, and assesses the importance of atmospheric deposition relative to other sources of PCBs to the river. Also, the relationship between indirect atmospheric deposition and PCB loads from minor tributaries to the Delaware River is discussed. Data from these sites revealed high atmospheric PCB concentrations in the Philadelphia/Camden urban area and lower regional background concentrations in the more remote areas. Wet, dry particle, and gaseous absorption deposition are estimated to contribute about 0.6, 1.8, and 6.5 kg year-(-1) sigmaPCBs to the River, respectively, exceeding the TMDL of 0.139 kg year(-1) by more than an order of magnitude. Penta-PCB watershed fluxes were obtained by dividing the tributary loads by the watershed area. The lowest of these watershed fluxes are less than approximately 1 ng m(-2) day(-1) for penta-PCB and probably indicates pristine watersheds in which PCB loads are dominated by atmospheric deposition. In these watersheds, the pass-through efficiency of PCBs is estimated to be on the order of 1%.
2. Atmospheric heavy metal deposition in Europe estimated by moss analysis
Energy Technology Data Exchange (ETDEWEB)
Ruehling, Aa. [Swedish Environmental Research Inst., Lund (Sweden). Dept. of Ecology
1995-12-31
Atmospheric heavy metal deposition in Europe including 21 countries was monitored in 1990-1992 by the moss technique. This technique is based on the fact that the concentrations of heavy metals in moss are closely correlated to atmospheric deposition. This was the first attempt to map heavy metal deposition in this large area. The objectives of the project were to characterise qualitatively and quantitatively the regional atmospheric deposition pattern of heavy metals in background areas in Europe, to indicate the location of important heavy metal pollution sources and to allow retrospective comparisons with similar studies. The present survey is a follow-up of a joint Danish and Swedish project in 1980 and an extended survey in 1985 within the framework of the Nordic Council of Ministers. In Sweden, heavy-metal deposition was first mapped on a nation-wide scale in 1968-1971 and 1975. (author)
3. Atmospheric heavy metal deposition in Europe estimated by moss analysis
Energy Technology Data Exchange (ETDEWEB)
Ruehling, Aa [Swedish Environmental Research Inst., Lund (Sweden). Dept. of Ecology
1996-12-31
Atmospheric heavy metal deposition in Europe including 21 countries was monitored in 1990-1992 by the moss technique. This technique is based on the fact that the concentrations of heavy metals in moss are closely correlated to atmospheric deposition. This was the first attempt to map heavy metal deposition in this large area. The objectives of the project were to characterise qualitatively and quantitatively the regional atmospheric deposition pattern of heavy metals in background areas in Europe, to indicate the location of important heavy metal pollution sources and to allow retrospective comparisons with similar studies. The present survey is a follow-up of a joint Danish and Swedish project in 1980 and an extended survey in 1985 within the framework of the Nordic Council of Ministers. In Sweden, heavy-metal deposition was first mapped on a nation-wide scale in 1968-1971 and 1975. (author)
4. A Distinct Magnetic Isotope Effect Measured in Atmospheric Mercury in Epiphytes
Science.gov (United States)
Ghosh, S.; Odom, A. L.
2007-12-01
Due to the importance of Mercury as an environmental contaminant, mercury cycling in the atmosphere has been extensively studied. However, there still remain uncertainties in the relative amounts of natural and anthropogenic emissions, atmospheric deposition rates as well as the spatial variation of atmospheric mercury. Part of a study to determine the isotopic composition of mercury deposited from the atmosphere has involved the use of epiphytes as monitors. The greatest advantage of such natural monitors is that a widespread, high-density network is possible at low cost. One of the disadvantages at present is that these monitors likely contain different mercury species (for example both gaseous, elemental mercury trapped by adsorption and Hg (II) by wet deposition). The project began with the understanding that biochemical reactions involving metallothioneins within the epiphytes might have produced an isotopic effect. One such regional network was composed of samples of Tillandsia usenoides (common name: Spanish moss) collected along the eastern Coastal Plain of the U.S. from northern Florida to North Carolina. The isotopic composition of a sample is expressed as permil deviations from a standard. The deviations are defined as δAHg = \\left(\\frac{Rsample}{Rstd}-1 \\right)1000 ‰ , where A represents the atomic mass number. R=\\frac{AHg}{202Hg} were measured for the isotopes 198Hg, 199Hg, 200Hg, 201Hg, 202Hg and 204Hg relative to the mercury standard SRM NIST 3133, by a standard-sample bracketing technique. For all samples, the delta values of the even-N plotted against atomic mass numbers define a linear curve. For the odd-N isotopes, δ199Hg and δ201Hg deviate from this mass-dependent fractionation (MDF) relationship and indicate a mass-independent fractionation (MIF) effect and a negative anomaly, i.e. a depletion in 199Hg and 201Hg relative to the even-N isotopes. These deviations are expressed as Δ199Hg = δ199Hgtotal - δ199HgMDF. A Δ201Hg/Δ199Hg
5. Ecological geochemical assessment and source identification of trace elements in atmospheric deposition of an emerging industrial area: Beibu Gulf economic zone.
Science.gov (United States)
Zhong, Cong; Yang, Zhongfang; Jiang, Wei; Hu, Baoqing; Hou, Qingye; Yu, Tao; Li, Jie
2016-12-15
Industrialization and urbanization have led to a deterioration in air quality and provoked some serious environmental concerns. Fifty-four samples of atmospheric deposition were collected from an emerging industrial area and analyzed to determine the concentrations of 11 trace elements (As, Cd, Cu, Fe, Hg, Mn, Mo, Pb, Se, S and Zn). Multivariate geostatistical analyses were conducted to determine the spatial distribution, possible sources and enrichment degrees of trace elements in atmospheric deposition. Results indicate that As, Fe and Mo mainly originated from soil, their natural parent materials, while the remaining trace elements were strongly influenced by anthropogenic or natural activities, such as coal combustion in coal-fired power plants (Pb, Se and S), manganese ore (Mn, Cd and Hg) and metal smelting (Cu and Zn). The results of ecological geochemical assessment indicate that Cd, Pb and Zn are the elements of priority concern, followed by Mn and Cu, and other heavy metals, which represent little threat to local environment. It was determine that the resuspension of soil particles impacted the behavior of heavy metals by 55.3%; the impact of the coal-fired power plants was 18.9%; and the contribution of the local manganese industry was 9.6%. The comparison of consequences from various statistical methods (principal component analysis (PCA), cluster analysis (CA), enrichment factor (EF) and absolute principle component score (APCS)-multiple linear regression (MLR)) confirmed the credibility of this research. Copyright © 2016 Elsevier B.V. All rights reserved.
6. Global observations and modeling of atmosphere-surface exchange of elemental mercury: a critical review
Science.gov (United States)
Zhu, Wei; Lin, Che-Jen; Wang, Xun; Sommar, Jonas; Fu, Xuewu; Feng, Xinbin
2016-04-01
Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg0) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg0. Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O3, radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling. We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg0 flux observations in East
7. New technique for quantification of elemental hg in mine wastes and its implications for mercury evasion into the atmosphere
Science.gov (United States)
Jew, A.D.; Kim, C.S.; Rytuba, J.J.; Gustin, M.S.; Brown, Gordon E.
2011-01-01
Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline ??-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range. ?? 2011 American Chemical Society.
8. Removal of Atmospheric Ethanol by Wet Deposition: A Global Flux Estimate
Science.gov (United States)
Felix, J. D. D.; Willey, J. D.; Avery, B.; Thomas, R.; Mullaugh, K.; Kieber, R. J.; Mead, R. N.; Helms, J. R.; Campos, L.; Shimizu, M. S.; Guibbina, F.
2017-12-01
Global ethanol fuel consumption has increased exponentially over the last two decades and the US plans to double annual renewable fuel production in the next five years as required by the renewable fuel standard. Regardless of the technology or feedstock used to produce the renewable fuel, the primary end product will be ethanol. Increasing ethanol fuel consumption will have an impact on the oxidizing capacity of the atmosphere and increase atmospheric concentrations of the secondary pollutant peroxyacetyl nitrate as well a variety of VOCs with relatively high ozone reactivities (e.g. ethanol, formaldehyde, acetaldehyde). Despite these documented effects of ethanol emissions on atmospheric chemistry, current global atmospheric ethanol budget models have large uncertainties in the magnitude of ethanol sources and sinks. The presented work investigates the global wet deposition sink by providing the first estimate of the global wet deposition flux of ethanol (2.4 ± 1.6 Tg/yr) based on empirical wet deposition data (219 samples collected at 12 locations). This suggests the wet deposition sink removes between 6 and 17% of atmospheric ethanol annually. Concentrations of ethanol in marine wet deposition (25 ± 6 nM) were an order of magnitude less than in the majority of terrestrial deposition (345 ± 280 nM). Terrestrial deposition collected in locations impacted by high local sources of biofuel usage and locations downwind from ethanol distilleries were an order of magnitude higher in ethanol concentration (3090 ± 448 nM) compared to deposition collected in terrestrial locations not impacted by these sources. These results indicate that wet deposition of ethanol is heavily influenced by local sources and ethanol emission impacts on air quality may be more significant in highly populated areas. As established and developing countries continue to rapidly increase ethanol fuel consumption and subsequent emissions, understanding the magnitude of all ethanol sources and
9. Atmospheric metal deposition in France: Estimation based on moss analysis. First results
International Nuclear Information System (INIS)
Galsomies, L.; Letrouit-Galinou, M.A.; Avnaim, M.; Duclaux, G.; Deschamps, C.; Savanne, D.
2000-01-01
The aim of this programme set up by University Pierre and Marie Curie-Paris VI and ADEME (French Agency for the Environment and Energy Management) is to obtain information on the atmospheric deposition of 36 elements (most being heavy metals) all over France, using 5 common mosses as bioaccumulators: Pleurozium schreberi, Hylocomium splendens, Hypnum cupressiforme, Scleropodium purum and Thuidium tamariscinum. Sampling was performed in 1996 from April to November thanks to 43 collectors. One sample of moss at least has been collected in 512 sites distributed over France, with an average density of one site each 1000 km 2 . Procedures for sampling, drying, cleaning, sorting are strictly codified based on Scandinavian guidelines. Analyses are performed according to two procedures: ICP-MS (Inductively Coupled Plasma, Mass Spectrometry) for Pb, Ni specialty and INAA (instrumental Neutron Activation Analysis for other elements. Data concerning As, Cd, Cr, Cu, Fe, Hg, Pb. Ni, V, Zn will be incorporated into the 1995-1996 European Programme 'Atmospheric Heavy Metal Deposition in Europe - estimation based on moss analysis' coordinated by the Nordic Council. The analyses are in progress, but preliminary results from Ile-de-France have been achieved for 34 elements in INAA. A preliminary study has shown that interspecies calibration could be possible for some heavy metals and that saturation effects in one species could be present when the intercalibration between species is not possible. Such a programme is made possible thanks to the financial support of the French Ministry of Environment and ADEME and with the active cooperation of several national organisations, especially the Laboratory Pierre Sue (CNRS-CEA). (author)
10. Effects of atmospheric inorganic nitrogen deposition on ocean biogeochemistry
OpenAIRE
Krishnamurthy, Aparna; Moore, J. Keith; Zender, Charles S; Luo, Chao
2007-01-01
We perform a sensitivity study with the Biogeochemical Elemental Cycling (BEC) ocean model to understand the impact of atmospheric inorganic nitrogen deposition on marine biogeochemistry and air-sea CO2 exchange. Simulations involved examining the response to three different atmospheric inorganic nitrogen deposition scenarios namely, Pre-industrial (22 Tg N/year), 1990s (39 Tg N/year), and an Intergovernmental Panel on Climate Change (IPCC) prediction for 2100, IPCC-A1FI (69 Tg N/year). Glob...
11. Atmospheric deposition, operational report for air pollution 2003. NOVA 2003; Atmosfaerisk deposition, driftsrapport for Luftforurening i 2003 NOVA 2003
Energy Technology Data Exchange (ETDEWEB)
Ellermann, T.; Hertel, O.; Ambelas Skjoeth, C.; Kemp, K.; Monies, C.
2004-12-01
This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2003. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorous and sulphur compounds related to eutrofication and acidification and selected heavy metals. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. The measurements in the monitoring programme are supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surfaces as well as marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data input. (BA)
12. Atmospheric transport, diffusion, and deposition of radioactivity
International Nuclear Information System (INIS)
Crawford, T.V.
1969-01-01
From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)
13. Atmospheric transport, diffusion, and deposition of radioactivity
Energy Technology Data Exchange (ETDEWEB)
Crawford, T V [Lawrence Radiation Laboratory, Livermore, CA (United States)
1969-07-01
From a meteorological standpoint there are two types of initial sources for atmospheric diffusion from Plowshare applications. One is the continuous point-source plume - a slow, small leak from an underground engineering application. The other is the large cloud produced almost instantaneously from a cratering application. For the purposes of this paper the effluent from neither type has significant fall speed. Both are carried by the prevailing wind, but the statistics of diffusion for each type are different. The use of constant altitude, isobaric and isentropic techniques for predicting the mean path of the effluent is briefly discussed. Limited data are used to assess the accuracy of current trajectory forecast techniques. Diffusion of continuous point-source plumes has been widely studied; only a brief review is given of the technique used and the variability of their results with wind speed and atmospheric stability. A numerical model is presented for computing the diffusion of the 'instantaneously-produced' large clouds. This model accounts for vertical and diurnal changes in atmospheric turbulence, wet and dry deposition, and radioactivity decay. Airborne concentrations, cloud size, and deposition on the ground are calculated. Pre- and post-shot calculations of cloud center, ground level concentration of gross radioactivity, and dry and wet deposition of iodine-131 are compared with measurements on Cabriolet and Buggy. (author)
14. Deposition rates of viruses and bacteria above the atmospheric boundary layer.
Science.gov (United States)
Reche, Isabel; D'Orta, Gaetano; Mladenov, Natalie; Winget, Danielle M; Suttle, Curtis A
2018-04-01
Aerosolization of soil-dust and organic aggregates in sea spray facilitates the long-range transport of bacteria, and likely viruses across the free atmosphere. Although long-distance transport occurs, there are many uncertainties associated with their deposition rates. Here, we demonstrate that even in pristine environments, above the atmospheric boundary layer, the downward flux of viruses ranged from 0.26 × 10 9 to >7 × 10 9 m -2 per day. These deposition rates were 9-461 times greater than the rates for bacteria, which ranged from 0.3 × 10 7 to >8 × 10 7 m -2 per day. The highest relative deposition rates for viruses were associated with atmospheric transport from marine rather than terrestrial sources. Deposition rates of bacteria were significantly higher during rain events and Saharan dust intrusions, whereas, rainfall did not significantly influence virus deposition. Virus deposition rates were positively correlated with organic aerosols 0.7 μm, implying that viruses could have longer residence times in the atmosphere and, consequently, will be dispersed further. These results provide an explanation for enigmatic observations that viruses with very high genetic identity can be found in very distant and different environments.
15. Soil as an archive of coal-fired power plant mercury deposition.
Science.gov (United States)
Rodríguez Martín, José Antonio; Nanos, Nikos
2016-05-05
Mercury pollution is a global environmental problem that has serious implications for human health. One of the most important sources of anthropogenic mercury emissions are coal-burning power plants. Hg accumulations in soil are associated with their atmospheric deposition. Our study provides the first assessment of soil Hg on the entire Spanish surface obtained from one sampling protocol. Hg spatial distribution was analysed with topsoil samples taken from 4000 locations in a regular sampling grid. The other aim was to use geostatistical techniques to verify the extent of soil contamination by Hg and to evaluate presumed Hg enrichment near the seven Spanish power plants with installed capacity above 1000 MW. The Hg concentration in Spanish soil fell within the range of 1-7564 μg kg(-1) (mean 67.2) and 50% of the samples had a concentration below 37 μg kg(-1). Evidence for human activity was found near all the coal-fired power plants, which reflects that metals have accumulated in the basin over many years. Values over 1000 μg kg(-1) have been found in soils in the vicinity of the Aboño, Soto de Ribera and Castellon power plants. However, soil Hg enrichment was detectable only close to the emission source, within an approximate range of only 15 km from the power plants. We associated this effect with airborne emissions and subsequent depositions as the potential distance through fly ash deposition. Hg associated with particles of ash tends to be deposited near coal combustion sources. Copyright © 2016 Elsevier B.V. All rights reserved.
16. Critical levels of atmospheric pollution: criteria and concepts for operational modelling of mercury in forest and lake ecosystems
NARCIS (Netherlands)
Meili, M.; Bishop, K.; Bringmark, L.; Johansson, K.; Munthe, J.; Sverdrup, H.; Vries, de W.
2003-01-01
Mercury (Hg) is regarded as a major environmental concern in many regions, traditionally because of high concentrations in freshwater fish, and now also because of potential toxic effects on soil microflora. The predominant source of Hg in most watersheds is atmospheric deposition, which has
17. Deposition of atmospheric 210Pb and total beta activity in Finland
International Nuclear Information System (INIS)
Jussi Paatero; Murat Buyukay; Juha Hatakka; Kaisa Vaaramaa; Jukka Lehto
2015-01-01
The seasonal and regional variation of the atmospheric 210 Pb deposition in Finland was studied. The 210 Pb activity concentration in precipitation shows a decreasing trend from southeastern Finland north-westwards. An average deposition of 40 Bq/m 2 during a 12 months period was observed. The deposition of 210 Pb shows a seasonal variation with minimum in spring and maximum in autumn and winter. The specific activity of 210 Pb (activity of 210 Pb per unit mass of stable lead) in the atmosphere has returned to the level prior to World War II owing to the reduced lead emissions into the atmosphere. (author)
18. Spatial variation in the flux of atmospheric deposition and its ecological effects in arid Asia
Science.gov (United States)
Jiao, Linlin; Wang, Xunming; Li, Danfeng
2018-06-01
Atmospheric deposition is one of the key land surface processes, and plays important roles in regional ecosystems and global climate change. Previous studies have focused on the magnitude of and the temporal and spatial variations in the flux of atmospheric deposition, and the composition of atmospheric deposition on a local scale. However, there have been no comprehensive studies of atmospheric deposition on a regional scale and its ecological effects in arid Asia. The temporal and spatial patterns, composition of atmospheric deposition, and its potential effects on regional ecosystems in arid Asia are investigated in this study. The results show that the annual deposition flux is high on the Turan Plain, Aral Sea Desert, and Tarim Basin. The seasonal deposition flux also varies remarkably among different regions. The Tarim Basin shows higher deposition flux in both spring and summer, southern Mongolian Plateau has a higher deposition flux in spring, and the deposition flux of Iran Plateau is higher in summer. Multiple sources of elements in deposited particles are identified. Calcium, iron, aluminum, and magnesium are mainly derived from remote regions, while zinc, copper and lead have predominantly anthropogenic sources. Atmospheric deposition can provide abundant nutrients to vegetation and consequently play a role in the succession of regional ecosystems by affecting the structure, function, diversity, and primary production of the vegetation, especially the exotic or short-lived opportunistic species in arid Asia. Nevertheless, there is not much evidence of the ecological effects of atmospheric deposition on the regional and local scale. The present results may help in further understanding the mechanism of atmospheric deposition as well as providing a motivation for the protection of the ecological environment in arid Asia.
19. The annual averaged atmospheric dispersion factor and deposition factor according to methods of atmospheric stability classification
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Hwang, Won Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-09-15
This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.
20. Chemical Bath Deposition of PbS:Hg2+ Nanocrystalline Thin Films
Directory of Open Access Journals (Sweden)
R. Palomino-Merino
2013-01-01
Full Text Available Nanocrystalline PbS thin films were prepared by Chemical Bath Deposition (CBD at 40 ± 2°C onto glass substrates and their structural and optical properties modified by in-situ doping with Hg. The morphological changes of the layers were analyzed using SEM and the X-rays spectra showing growth on the zinc blende (ZB face. The grain size determined by using X-rays spectra for undoped samples was found to be ~36 nm, whereas with the doped sample was 32–20 nm. Optical absorption spectra were used to calculate the Eg, showing a shift in the range 1.4–2.4 eV. Raman spectroscopy exhibited an absorption band ~135 cm−1 displaying only a PbS ZB structure.
1. A review of studies on atmospheric mercury in China.
Science.gov (United States)
Fu, Xuewu; Feng, Xinbin; Sommar, Jonas; Wang, Shaofeng
2012-04-01
Due to the fast developing economy, mercury (Hg) emissions to the atmosphere from Chinese mainland have increased rapidly in recent years. Consequently, this issue has received a considerable attention internationally. This paper reviews the current understanding of and knowledge on atmospheric Hg emissions, distribution and transport in China. The magnitude of Hg emissions to the atmosphere from Chinese anthropogenic sources has been estimated to be in the range of 500-700 tons per year, whereby comprising a significant proportion of the globe total anthropogenic emissions. Emissions of Hg from natural surfaces including bare soil, water, and vegetation covered soil tend in a comparison to be higher in China than in Europe and North America, indicating the importance of this source category. Atmospheric Hg exhibits a significant concentration variability among urban, semi-remote, and remote areas. Total Gaseous Mercury (TGM) concentrations in urban areas of China were often 1.5 - 5 folds higher compared to the corresponding settings in North America and Europe. In turn, particulate mercury (PHg) concentrations in urban areas of China were up to two orders of magnitude higher compared to North America and Europe. Atmospheric observations made at strictly remote sites in China also include the presence of occasional high concentrations of TGM, and the more short-lived fractions PHg and Reactive Gaseous Mercury (RGM). Accordingly, Hg deposition fluxes tended to be higher in China, with remote areas and urban areas being 1-2 times and 1-2 magnitude higher than those in North America and Europe, respectively. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.
2. Modelling atmospheric deposition flux of Cadmium and Lead in urban areas
International Nuclear Information System (INIS)
Cherin, Nicolas
2017-01-01
According to WHO, air pollution is responsible for more than 3.7 million premature deaths each year (OMS, 2014). Moreover, among these deaths, more than 70 within urban areas. Consequently, the health and environmental impacts of pollutants within these urban areas are of great concern in air quality studies. The deposition fluxes of air pollutants, which can be significant near sources of pollution, have rarely been modeled within urban areas. Historically, atmospheric deposition studies have focused mostly on remote areas to assess the potential impacts on ecosystems of acid deposition and nitrogen loading. Therefore, current atmospheric deposition models may not be suitable to simulate deposition fluxes in urban areas, which include complex surface geometries and diverse land use types. Atmospheric dry deposition is typically modeled using an average roughness length, which depends on land use. This classical roughness-length approach cannot account for the spatial variability of dry deposition in complex settings such as urban areas. Urban canopy models have been developed to parameterize momentum and heat transfer. We extend this approach here to mass transfer, and a new dry deposition model based on the urban canyon concept is presented. It uses a local mixing-length parameterization of turbulence within the canopy, and a description of the urban canopy via key parameters to provide spatially distributed dry deposition fluxes. This approach provides spatially distributed dry deposition fluxes depending on surfaces (streets, walls, roofs) and flow regimes (recirculation and ventilation) within the urban area. (author) [fr
3. Trends in the chemistry of atmospheric deposition and surface waters in the Lake Maggiore catchment
Directory of Open Access Journals (Sweden)
M. Rogora
2001-01-01
Full Text Available The Lake Maggiore catchment is the area of Italy most affected by acid deposition. Trend analysis was performed on long-term (15-30 years series of chemical analyses of atmospheric deposition, four small rivers draining forested catchments and four high mountain lakes. An improvement in the quality of atmospheric deposition was detected, due to decreasing sulphate concentration and increasing pH. Similar trends were also found in high mountain lakes and in small rivers. Atmospheric deposition, however, is still providing a large and steady flux of nitrogen compounds (nitrate and ammonium which is causing increasing nitrogen saturation in forest ecosystems and increasing nitrate levels in rivers. Besides atmospheric deposition, an important factor controlling water acidification and recovery is the weathering of rocks and soils which may be influenced by climate warming. A further factor is the episodic deposition of Saharan calcareous dust which contributes significantly to base cation deposition. Keywords: trend, atmospheric deposition, nitrogen, stream water chemistry.
4. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions
Science.gov (United States)
Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,
2015-01-01
Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (inventories indicating flat or increasing emissions over that period. However, the inventories have three major flaws: (i) they do not account for the decline in atmospheric release of Hg from commercial products; (ii) they are biased in their estimate of artisanal and small-scale gold mining emissions; and (iii) they do not properly account for the change in Hg0/HgII speciation of emissions from coal-fired utilities after implementation of emission controls targeted at SO2 and NOx. We construct an improved global emission inventory for the period 1990 to 2010 accounting for the above factors and find a 20% decrease in total Hg emissions and a 30% decrease in anthropogenic Hg0 emissions, with much larger decreases in North America and Europe offsetting the effect of increasing emissions in Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.
5. Spatial atmospheric atomic layer deposition of alxzn1-xo
NARCIS (Netherlands)
Illiberi, A.; Scherpenborg, R.; Wu, Y.; Roozeboom, F.; Poodt, P.
2013-01-01
The possibility of growing multicomponent oxides by spatial atmospheric atomic layer deposition has been investigated. To this end, Al xZn1-xO films have been deposited using diethyl zinc (DEZ), trimethyl aluminum (TMA), and water as Zn, Al, and O precursors, respectively. When the metal precursors
6. Annual ambient atmospheric mercury speciation measurement from Longjing, a rural site in Taiwan.
Science.gov (United States)
Fang, Guor-Cheng; Lo, Chaur-Tsuen; Cho, Meng-Hsien; Zhuang, Yuan-Jie; Tsai, Kai-Hsiang; Huang, Chao-Yang; Xiao, You-Fu
2017-08-01
The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000-2012.
7. Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model.
Science.gov (United States)
Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B; Hao, Jiming
2014-07-01
China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. Copyright © 2014 Elsevier Ltd. All rights reserved.
8. Passivation Effect of Atomic Layer Deposition of Al2O3 Film on HgCdTe Infrared Detectors
Science.gov (United States)
Zhang, Peng; Ye, Zhen-Hua; Sun, Chang-Hong; Chen, Yi-Yu; Zhang, Tian-Ning; Chen, Xin; Lin, Chun; Ding, Ring-Jun; He, Li
2016-09-01
The passivation effect of atomic layer deposition of (ALD) Al2O3 film on a HgCdTe infrared detector was investigated in this work. The passivation effect of Al2O3 film was evaluated by measuring the minority carrier lifetime, capacitance versus voltage ( C- V) characteristics of metal-insulator-semiconductor devices, and resistance versus voltage ( R- V) characteristics of variable-area photodiodes. The minority carrier lifetime, C- V characteristics, and R- V characteristics of HgCdTe devices passivated by ALD Al2O3 film was comparable to those of HgCdTe devices passivated by e-beam evaporation of ZnS/CdTe film. However, the baking stability of devices passivated by Al2O3 film is inferior to that of devices passivated by ZnS/CdTe film. In future work, by optimizing the ALD Al2O3 film growing process and annealing conditions, it may be feasible to achieve both excellent electrical properties and good baking stability.
9. Atmospheric Nitrogen Deposition in the Western United States: Sources, Sinks and Changes over Time
Science.gov (United States)
Anderson, Sarah Marie
Anthropogenic activities have greatly modified the way nitrogen moves through the atmosphere and terrestrial and aquatic environments. Excess reactive nitrogen generated through fossil fuel combustion, industrial fixation, and intensification of agriculture is not confined to anthropogenic systems but leaks into natural ecosystems with consequences including acidification, eutrophication, and biodiversity loss. A better understanding of where excess nitrogen originates and how that changes over time is crucial to identifying when, where, and to what degree environmental impacts occur. A major route into ecosystems for excess nitrogen is through atmospheric deposition. Excess nitrogen is emitted to the atmosphere where it can be transported great distances before being deposited back to the Earth's surface. Analyzing the composition of atmospheric nitrogen deposition and biological indicators that reflect deposition can provide insight into the emission sources as well as processes and atmospheric chemistry that occur during transport and what drives variation in these sources and processes. Chapter 1 provides a review and proof of concept of lichens to act as biological indicators and how their elemental and stable isotope composition can elucidate variation in amounts and emission sources of nitrogen over space and time. Information on amounts and emission sources of nitrogen deposition helps inform natural resources and land management decisions by helping to identify potentially impacted areas and causes of those impacts. Chapter 2 demonstrates that herbaria lichen specimens and field lichen samples reflect historical changes in atmospheric nitrogen deposition from urban and agricultural sources across the western United States. Nitrogen deposition increases throughout most of the 20 th century because of multiple types of emission sources until the implementation of the Clean Air Act Amendments of 1990 eventually decrease nitrogen deposition around the turn of
10. Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China
Science.gov (United States)
Pan, Y. P.; Wang, Y. S.
2015-01-01
Atmospheric deposition is considered to be a major process that removes pollutants from the atmosphere and an important source of nutrients and contaminants for ecosystems. Trace elements (TEs), especially toxic metals deposited on plants and into soil or water, can cause substantial damage to the environment and human health due to their transfer and accumulation in food chains. Despite public concerns, quantitative knowledge of metal deposition from the atmosphere to ecosystems remains scarce. To advance our understanding of the spatiotemporal variations in the magnitudes, pathways, compositions and impacts of atmospherically deposited TEs, precipitation (rain and snow) and dry-deposited particles were collected simultaneously at 10 sites in Northern China from December 2007 to November 2010. The measurements showed that the wet and dry depositions of TEs in the target areas were orders of magnitude higher than previous observations within and outside China, generating great concern over the potential risks. The spatial distribution of the total (wet plus dry) deposition flux was consistent with that of the dry deposition, with a significant decrease from industrial and urban areas to suburban, agricultural and rural sites, while the wet deposition exhibited less spatial variation. In addition, the seasonal variation of wet deposition was also different from that of dry deposition, although they were both governed by the precipitation and emission patterns. For the majority of TEs that exist as coarse particles, dry deposition dominated the total flux at each site. This was not the case for potassium, nickel, arsenic, lead, zinc, cadmium, selenium, silver and thallium, for which the relative importance between wet and dry deposition fluxes varied by site. Whether wet deposition is the major atmospheric cleansing mechanism for the TEs depends on the size distribution of the particles. We found that atmospheric inputs of copper, lead, zinc, cadmium, arsenic and
11. Updated atmospheric speciated mercury emissions from iron and steel production in China during 2000-2015
Science.gov (United States)
Wu, Qingru; Gao, Wei; Wang, Shuxiao; Hao, Jiming
2017-09-01
Iron and steel production (ISP) is one of the significant atmospheric Hg emission sources in China. Atmospheric mercury (Hg) emissions from ISP during 2000-2015 were estimated by using a technology-based emission factor method. To support the application of this method, databases of Hg concentrations in raw materials, technology development trends, and Hg removal efficiencies of air pollution control devices (APCDs) were constructed through national sampling and literature review. Hg input to ISP increased from 21.6 t in 2000 to 94.5 t in 2015. In the various types of raw materials, coking coal and iron concentrates contributed 35-46 and 25-32 % of the total Hg input. Atmospheric Hg emissions from ISP increased from 11.5 t in 2000 to 32.7 t in 2015 with a peak of 35.6 t in 2013. Pollution control promoted the increase in average Hg removal efficiency, from 47 % in 2000 to 65 % in 2015. During the study period, sinter/pellet plants and blast furnaces were the largest two emission processes. However, emissions from roasting plants and coke ovens cannot be ignored, which accounted for 22-34 % of ISP's emissions. Overall, Hg speciation shifted from 50/44/6 (gaseous elemental Hg (Hg0)/gaseous oxidized Hg (HgII)/particulate-bound Hg (Hgp)) in 2000 to 40/59/1 in 2015, which indicated a higher proportion of Hg deposition around the emission points. Future emissions of ISP were expected to decrease based on the comprehensive consideration crude-steel production, steel scrap utilization, energy saving, and pollution control measures.
12. Silver nanoparticles deposited on amine-functionalized silica spheres and their amalgamation-based spectral and colorimetric detection of Hg(II) ions
Energy Technology Data Exchange (ETDEWEB)
Rameshkumar, Perumal; Manivannan, Shanmugam; Ramaraj, Ramasamy, E-mail: ramarajr@yahoo.com [Madurai Kamaraj University, Centre for Photoelectrochemistry, School of Chemistry (India)
2013-05-15
A facile synthetic method to decorate amine-functionalized silica spheres (SiO{sub 2}) by silver nanoparticles (Ag NPs) is reported. The transmission electron microscopic (TEM) images showed that spherical Ag NPs with an average particle size of 14 nm were deposited on 250 nm-sized SiO{sub 2} spheres (SiO{sub 2}/Ag NPs). The spectral and colorimetric detection of Hg(II) ions were carried out using the synthesized SiO{sub 2}/Ag NPs with an experimental detection limit of 5 {mu}M. It was found that the addition of Hg(II) ions (150 {mu}M) into the solution of SiO{sub 2}/Ag NPs completely quenched the SPR band of the Ag NPs due to the formation of anisotropic Ag amalgam crystals (AgHg). The selective detection of Hg(II) ions by SiO{sub 2}/Ag NPs in the presence of other environmentally relevant metal ions was also demonstrated using spectral and colorimetric methods.Graphical abstractAmine-functionalized silica spheres are decorated by in situ formation of silver nanoparticles and their spectral and colorimetric detection of Hg(II) ions is reported.
13. Human health risk assessment of lead pollution in atmospheric deposition in Baoshan District, Shanghai.
Science.gov (United States)
Chen, Yuanyuan; Wang, Jun; Shi, Guitao; Sun, Xiaojing; Chen, Zhenlou; Xu, Shiyuan
2011-12-01
The lead (Pb) content in atmospheric deposition was determined at 42 sampling sites in Baoshan District of Shanghai, China. Based on exposure and dose-response assessments, the health risk caused by Pb exposure in atmospheric deposition was investigated. The results indicated that Pb was significantly accumulated in atmospheric deposition. The spatial distribution of Pb was mapped by geostatistical analysis, and the results showed that pollution hotspots were present at traffic and industrial zones. Ingestion was the main route of Pb exposure in both adults and children. For children the risk value was above 1, whereas it was below 1 for the adult group. Therefore, children belong to the high-risk group for Pb exposure from atmospheric deposition in the observed area of Shanghai, China.
14. Contribution of Asian dust to atmospheric deposition of radioactive cesium (137Cs)
International Nuclear Information System (INIS)
Fukuyama, Taijiro; Fujiwara, Hideshi
2008-01-01
Both Asian dust (kosa) transported from the East Asian continent and locally suspended dust near monitoring sites contribute to the observed atmospheric deposition of 137 Cs in Japan. To estimate the relative contribution of these dust phenomena to the total 137 Cs deposition, we monitored weekly deposition of mineral particles and 137 Cs in spring. Deposition of 137 Cs from a single Asian dust event was 62.3 mBq m -2 and accounted for 67% of the total 137 Cs deposition during the entire monitoring period. Furthermore, we found high 137 Cs specific activity in the Asian dust deposition sample. Although local dust events contributed to 137 Cs deposition, their contribution was considerably smaller than that of Asian dust. We conclude that the primary source of atmospheric 137 Cs in Japan is dust transported from the East Asian continent
15. Measurement of forest condition and response along the Pennsylvania atmospheric deposition gradent
Science.gov (United States)
D.D. David; J.M. Skelly; J.A. Lynch; L.H. McCormick; B.L. Nash; M. Simini; E.A. Cameron; J.R. McClenahen; R.P. Long
1991-01-01
Research in the oak-hickory forest of northcentral Pennsylvania is being conducted to detect anomalies in forest condition that may be due to atmospheric deposition, with the intent that such anomalies will be further studied to determine the role, if any, of atmospheric deposition. This paper presents the status of research along a 160-km gradient of sulfate/nitrate...
16. New insights into the atmospheric mercury cycling in central Antarctica and implications on a continental scale
Directory of Open Access Journals (Sweden)
H. Angot
2016-07-01
Full Text Available Under the framework of the GMOS project (Global Mercury Observation System atmospheric mercury monitoring has been implemented at Concordia Station on the high-altitude Antarctic plateau (75°06′ S, 123°20′ E, 3220 m above sea level. We report here the first year-round measurements of gaseous elemental mercury (Hg(0 in the atmosphere and in snowpack interstitial air on the East Antarctic ice sheet. This unique data set shows evidence of an intense oxidation of atmospheric Hg(0 in summer (24-hour daylight due to the high oxidative capacity of the Antarctic plateau atmosphere in this period of the year. Summertime Hg(0 concentrations exhibited a pronounced daily cycle in ambient air with maximal concentrations around midday. Photochemical reactions and chemical exchange at the air–snow interface were prominent, highlighting the role of the snowpack on the atmospheric mercury cycle. Our observations reveal a 20 to 30 % decrease of atmospheric Hg(0 concentrations from May to mid-August (winter, 24 h darkness. This phenomenon has not been reported elsewhere and possibly results from the dry deposition of Hg(0 onto the snowpack. We also reveal the occurrence of multi-day to weeklong atmospheric Hg(0 depletion events in summer, not associated with depletions of ozone, and likely due to a stagnation of air masses above the plateau triggering an accumulation of oxidants within the shallow boundary layer. Our observations suggest that the inland atmospheric reservoir is depleted in Hg(0 in summer. Due to katabatic winds flowing out from the Antarctic plateau down the steep vertical drops along the coast and according to observations at coastal Antarctic stations, the striking reactivity observed on the plateau most likely influences the cycle of atmospheric mercury on a continental scale.
17. Trends in mercury wet deposition and mercury air concentrations across the U.S. and Canada
Science.gov (United States)
Weiss-Penzias, Peter S.; Gay, David A.; Brigham, Mark E.; Parsons, Matthew T.; Gustin, Mae S.; ter Shure, Arnout
2016-01-01
18. Atmospheric Deposition of Heavy Metals in Soil Affected by Different Soil Uses of Southern Spain
Science.gov (United States)
Acosta, J. A.; Faz, A.; Martínez-Martínez, S.; Bech, J.
2009-04-01
Heavy metals are a natural constituent of rocks, sediments and soils. However, the heavy metal content of top soils is also dependent on other sources than weathering of the indigenous minerals; input from atmospheric deposition seems to be an important pathway. Atmospheric deposition is defined as the process by which atmospheric pollutants are transferred to terrestrial and aquatic surfaces and is commonly classified as either dry or wet. The interest in atmospheric deposition has increased over the past decade due to concerns about the effects of deposited materials on the environment. Dry deposition provides a significant mechanism for the removal of particles from the atmosphere and is an important pathway for the loading of heavy metals into the soil ecosystem. Within the last decade, an intensive effort has been made to determine the atmospheric heavy metal deposition in both urban and rural areas. The main objective of this study was to identification of atmospheric heavy metals deposition in soil affected by different soil uses. Study area is located in Murcia Province (southeast of Spain), in the surroundings of Murcia City. The climate is typically semiarid Mediterranean with an annual average temperature of 18°C and precipitation of 350 mm. In order to determine heavy metals atmospheric deposition a sampling at different depths (0-1 cm, 1-5 cm, 5-15 cm and 15-30 cm) was carried out in 7 sites including agricultural soils, two industrial areas and natural sites. The samples were taken to the laboratory where, dried, passed through a 2 mm sieve, and grinded. For the determination of the moisture the samples were weighed and oven dried at 105 °C for 24 h. The total amounts of metals (Pb, Cu, Pb, Zn, Cd, Mn, Ni and Cr) were determined by digesting the samples with nitric/perchoric acids and measuring with ICP-MS. Results showed that zinc contamination in some samples of industrial areas was detected, even this contamination reaches 30 cm depth; thus it is
19. Litterfall mercury dry deposition in the eastern USA
International Nuclear Information System (INIS)
Risch, Martin R.; DeWild, John F.; Krabbenhoft, David P.; Kolka, Randall K.; Zhang, Leiming
2012-01-01
Mercury (Hg) in autumn litterfall from predominately deciduous forests was measured in 3 years of samples from 23 Mercury Deposition Network sites in 15 states across the eastern USA. Annual litterfall Hg dry deposition was significantly higher (median 12.3 micrograms per square meter (μg/m 2 ), range 3.5–23.4 μg/m 2 ) than annual Hg wet deposition (median 9.6 μg/m 2 , range 4.4–19.7 μg/m 2 ). The mean ratio of dry to wet Hg deposition was 1.3–1. The sum of dry and wet Hg deposition averaged 21 μg/m 2 per year and 55% was litterfall dry deposition. Methylmercury was a median 0.8% of Hg in litterfall and ranged from 0.6 to 1.5%. Annual litterfall Hg and wet Hg deposition rates differed significantly and were weakly correlated. Litterfall Hg dry deposition differed among forest-cover types. This study demonstrated how annual litterfall Hg dry deposition rates approximate the lower bound of annual Hg dry fluxes. - Highlights: ► Annual litterfall mercury dry deposition was significantly higher than wet deposition. ► The mean ratio of dry to wet mercury deposition was 1.3–1. ► The sum of dry and wet mercury deposition averaged 55% litterfall dry deposition. ► Litterfall mercury deposition was highest in the oak-hickory forest-cover type. ► Methylmercury was a median 0.8% of mercury in litterfall and ranged to 1.5%. - A multi-year study of Mercury Deposition Network sites found that annual mercury dry deposition from litterfall in predominately deciduous forests exceeded annual mercury wet deposition in the eastern USA.
20. Atmospheric wet deposition of mercury in North America
Energy Technology Data Exchange (ETDEWEB)
Sweet, C.W.; Prestbo, E.; Brunette, B.
1999-07-01
Currently, 39 states in the US and 5 Canadian provinces have issued advisories about the dangers of eating mercury-contaminated fish taken from waters within their boundaries. The problem is most severe in the Great Lakes region, the Northeast US states, the Canadian maritime provinces, and in south Florida where many lakes and streams contain fish with concentrations of 1 ppm or higher. For many rural and remote locations, atmospheric deposition is the primary source of mercury. In 1995, the National Atmospheric Deposition Program (NADP) initiated a program to monitor total mercury and methylmercury (MMHg) in wet deposition (rain and snow) in North America. In this program, the Mercury Deposition Network (MDN), individual monitoring sites are funded and operated by a variety of local, state, and federal agencies. However, sampling and analysis are coordinated through a central laboratory so that all of the samples are collected and analyzed using the same protocols. Weekly wet-only precipitation samples are collected using an all-glass sampling train and special handling techniques. Analysis is by cold vapor atomic fluorescence spectrometry using USEPA Method 1631 for total mercury. Nearly 40 MDN sites are in operation in 1999. Most of the sites are in the eastern US and Canada. During 1996 and 1997, the volume-weighted mean concentration of total mercury in precipitation collected at 22 sites ranged from 6.0 to 18.9 ng/L. Annual deposition varied between 2.1 and 25.3 {micro} g/m{sup 2}. The average weekly wet deposition of total mercury is more than three times higher in the summer (June-August) than in the winter (December-February). This increase is due to both higher amounts of precipitation and higher concentrations of mercury in precipitation during the summer. The highest values for mercury concentration in precipitation and wet deposition of mercury were measured in the southeastern US.
1. Oceanic Emissions and Atmospheric Depositions of Volatile Organic Compounds
Science.gov (United States)
Yang, M.; Blomquist, B.; Beale, R.; Nightingale, P. D.; Liss, P. S.
2015-12-01
Atmospheric volatile organic compounds (VOCs) affect the tropospheric oxidative capacity due to their ubiquitous abundance and relatively high reactivity towards the hydroxyal radical. Over the ocean and away from terrestrial emission sources, oxygenated volatile organic compounds (OVOCs) make up a large fraction of VOCs as airmasses age and become more oxidized. In addition to being produced or destroyed in the marine atmosphere, OVOCs can also be emitted from or deposited to the surface ocean. Here we first present direct air-sea flux measurements of three of the most abundant OVOCs - methanol, acetone, and acetaldehyde, by the eddy covariance technique from two cruises in the Atlantic: the Atlantic Meridional Transect in 2012 and the High Wind Gas Exchange Study in 2013. The OVOC mixing ratios were quantified by a high resolution proton-reaction-transfer mass spectrometer with isotopically labeled standards and their air-sea (net) fluxes were derived from the eddy covariance technique. Net methanol flux was consistently from the atmosphere to the surface ocean, while acetone varied from supersaturation (emission) in the subtropics to undersaturation (deposition) in the higher latitudes of the North Atlantic. The net air-sea flux of acetaldehyde is near zero through out the Atlantic despite the apparent supersaturation of this compound in the surface ocean. Knowing the dissolved concentrations and in situ production rates of these compounds in seawater, we then estimate their bulk atmospheric depositions and oceanic emissions. Lastly, we summarize the state of knowledge on the air-sea transport of a number of organic gasses, and postulate the magnitude and environmental impact of total organic carbon transfer between the ocean and the atmosphere.
2. Standard test method for determining atmospheric chloride deposition rate by wet candle method
CERN Document Server
American Society for Testing and Materials. Philadelphia
2002-01-01
1.1 This test method covers a wet candle device and its use in measuring atmospheric chloride deposition (amount of chloride salts deposited from the atmosphere on a given area per unit time). 1.2 Data on atmospheric chloride deposition can be useful in classifying the corrosivity of a specific area, such as an atmospheric test site. Caution must be exercised, however, to take into consideration the season because airborne chlorides vary widely between seasons. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
3. Recent Advances in Atmospheric Vapor-Phase Deposition of Transparent and Conductive Zinc Oxide
NARCIS (Netherlands)
Illiberi, A.; Poodt, P.; Roozeboom, F.
2014-01-01
The industrial need for high-throughput and low-cost ZnO deposition processes has triggered the development of atmospheric vapor-phase deposition techniques which can be easily applied to continuous, in-line manufacturing. While atmospheric CVD is a mature technology, new processes for the growth of
4. Atmospheric deposition of 137Cs between 1994 and 2002 at Cienfuegos, Cuba
International Nuclear Information System (INIS)
Alonso-Hernandez, C.M.; Cartas-Aguila, H.; Diaz-Asencio, M.; Munoz-Caravaca, A.; Martin-Perez, J.; Sibello-Hernandez, R.
2006-01-01
Levels of 137 Cs in total atmospheric deposition have been measured in the Cienfuegos region (Cuba) between 1994 and 2002. Samples were collected every three months, evaporated to dryness to obtain residual samples, and measured by gamma spectrometry. The 137 Cs mean concentration in total deposition was 0.24 Bq m -2 and data ranged between -2 . Precipitation rates and raintime have proved to be the most important factors controlling the concentration and depositional flux of 137 Cs in the atmosphere over Cienfuegos, showing a high correlation coefficient (R = 0.93)
5. HTO deposition by vapor exchange between atmosphere and soil
International Nuclear Information System (INIS)
Bunnenberg, C.
1989-01-01
HTO deposition to soils occurs by vapor exchange between atmosphere and soil-air, when the concentration gradient is directed downwards, and it is principally independent from simultaneous transport of H 2 O. In relatively dry top soil, which is frequently the case, as it tries to attain equilibrium with the air humidity, HTO diffuses into deeper soil driven by the same mechanisms that caused the deposition process. The resulting HTO profile is depending on the atmospheric supply and the soil physical conditions, and it is the source for further tritium pathways, namely root uptake by plants and reemission from soil back into the ground-level air. Simulation experiments with soil columns exposed to HTO labeled atmospheres have proved the theoretical expectation that under certain boundary conditions the HTO profile can be described by an error function. The key parameter is the effective diffusion coefficient, which in turn is a function of the sorption characteristics of the particular soil. (orig.) [de
6. Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison
International Nuclear Information System (INIS)
Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter
2017-01-01
Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012–2014. Total fluxes of 17 PAHs were 587-32,300 ng m −2 day −1 , with a geometric mean of 2600 ng m −2 day −1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km −2 ) with a range of 2.5–10 tons (0.4–1.6 kg km −2 ). - Highlights: • PAH deposition flux in Shanghai is categorized as moderate to high on global scale. • Their spatial distribution reveals the influence of urbanization/industrialization. • Atmospheric deposition is the principal pathway of PAHs input to local topsoils. • Other pathways have to be considered for PAH input in urban soil. - Atmospheric deposition of PAHs revealed the influence of urbanization and industrialization and the relevance of local emissions on Shanghai topsoils.
7. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington forests, USA
Science.gov (United States)
Linda H. Geiser; Sarah E. Jovan; Doug A. Glavich; Matthew K. Porter
2010-01-01
Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry,...
8. Atmospheric bulk deposition of polycyclic aromatic hydrocarbons in Shanghai: Temporal and spatial variation, and global comparison.
Science.gov (United States)
Feng, Daolun; Liu, Ying; Gao, Yi; Zhou, Jinxing; Zheng, Lirong; Qiao, Gang; Ma, Liming; Lin, Zhifen; Grathwohl, Peter
2017-11-01
Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai's urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012-2014. Total fluxes of 17 PAHs were 587-32,300 ng m -2 day -1 , with a geometric mean of 2600 ng m -2 day -1 . The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km -2 ) with a range of 2.5-10 tons (0.4-1.6 kg km -2 ). Copyright © 2017 Elsevier Ltd. All rights reserved.
9. Beryllium abundances in Hg-Mn stars
International Nuclear Information System (INIS)
Boesgaard, A.M.; Heacox, W.D.; Wolff, S.C.; Borsenberger, J.; Praderie, F.
1982-01-01
The Hg-Mn stars show anomalous line strengths of many chemical elements including Be. We have observed the Be ii resonance doublet at lambdalambda 3130, 3131 at 6.7 A mm -1 in 43 Hg-Mn stars and 10 normal stars in the same temperature range with the coude spectrograph of the 2.24 m University of Hawaii telescope at Mauna Kea. Measured equivalent widths of the two lines and/or the blend of the doublet have been compared with predictions from (1) LTE model atmospheres and (2) non-LTE line formation on non-LTE model atmospheres. (For strong Be ii lines, the LTE calculations result in more Be by factors of 2 to 4 than do the non-LTE calculations.) Overabundances of factors of 20--2 x 10 4 relative to solar have been found for 75% of the Hg-Mn stars. The 25% with little or no Be are typically among the cooler Hg-Mn stars, but for the stars with Be excesses, there is only marginal evidence for a correlationi of the size of the overabundance and temperature. It is suggested that diffusion driven by radiation pressure is responsible for the observed Be abundance anomalies
10. Updated atmospheric speciated mercury emissions from iron and steel production in China during 2000–2015
Directory of Open Access Journals (Sweden)
Q. Wu
2017-09-01
Full Text Available Iron and steel production (ISP is one of the significant atmospheric Hg emission sources in China. Atmospheric mercury (Hg emissions from ISP during 2000–2015 were estimated by using a technology-based emission factor method. To support the application of this method, databases of Hg concentrations in raw materials, technology development trends, and Hg removal efficiencies of air pollution control devices (APCDs were constructed through national sampling and literature review. Hg input to ISP increased from 21.6 t in 2000 to 94.5 t in 2015. In the various types of raw materials, coking coal and iron concentrates contributed 35–46 and 25–32 % of the total Hg input. Atmospheric Hg emissions from ISP increased from 11.5 t in 2000 to 32.7 t in 2015 with a peak of 35.6 t in 2013. Pollution control promoted the increase in average Hg removal efficiency, from 47 % in 2000 to 65 % in 2015. During the study period, sinter/pellet plants and blast furnaces were the largest two emission processes. However, emissions from roasting plants and coke ovens cannot be ignored, which accounted for 22–34 % of ISP's emissions. Overall, Hg speciation shifted from 50/44/6 (gaseous elemental Hg (Hg0/gaseous oxidized Hg (HgII/particulate-bound Hg (Hgp in 2000 to 40/59/1 in 2015, which indicated a higher proportion of Hg deposition around the emission points. Future emissions of ISP were expected to decrease based on the comprehensive consideration crude-steel production, steel scrap utilization, energy saving, and pollution control measures.
11. Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering
Science.gov (United States)
Stark, C. R.; Diver, D. A.
2018-04-01
Context. In contemporary sub-stellar model atmospheres, dust growth occurs through neutral gas-phase surface chemistry. Recently, there has been a growing body of theoretical and observational evidence suggesting that ionisation processes can also occur. As a result, atmospheres are populated by regions composed of plasma, gas and dust, and the consequent influence of plasma processes on dust evolution is enhanced. Aim. This paper aims to introduce a new model of dust growth and destruction in sub-stellar atmospheres via plasma deposition and plasma sputtering. Methods: Using example sub-stellar atmospheres from DRIFT-PHOENIX, we have compared plasma deposition and sputtering timescales to those from neutral gas-phase surface chemistry to ascertain their regimes of influence. We calculated the plasma sputtering yield and discuss the circumstances where plasma sputtering dominates over deposition. Results: Within the highest dust density cloud regions, plasma deposition and sputtering dominates over neutral gas-phase surface chemistry if the degree of ionisation is ≳10-4. Loosely bound grains with surface binding energies of the order of 0.1-1 eV are susceptible to destruction through plasma sputtering for feasible degrees of ionisation and electron temperatures; whereas, strong crystalline grains with binding energies of the order 10 eV are resistant to sputtering. Conclusions: The mathematical framework outlined sets the foundation for the inclusion of plasma deposition and plasma sputtering in global dust cloud formation models of sub-stellar atmospheres.
12. Acid atmospheric deposition in a forested mountain catchment
Czech Academy of Sciences Publication Activity Database
Křeček, J.; Palán, L.; Stuchlík, Evžen
2017-01-01
Roč. 10, č. 4 (2017), s. 680-686 ISSN 1971-7458 Institutional support: RVO:60077344 Keywords : mountain water shed * spruce forests * acid atmospheric deposition * water resources recharge Subject RIV: DA - Hydrology ; Limnology OBOR OECD: Marine biology, freshwater biology, limnology Impact factor: 1.623, year: 2016
13. Estimating chemical composition of atmospheric deposition fluxes from mineral insoluble particles deposition collected in the western Mediterranean region
Directory of Open Access Journals (Sweden)
Y. Fu
2017-11-01
Full Text Available In order to measure the mass flux of atmospheric insoluble deposition and to constrain regional models of dust simulation, a network of automatic deposition collectors (CARAGA has been installed throughout the western Mediterranean Basin. Weekly samples of the insoluble fraction of total atmospheric deposition were collected concurrently on filters at five sites including four on western Mediterranean islands (Frioul and Corsica, France; Mallorca, Spain; and Lampedusa, Italy and one in the southern French Alps (Le Casset, and a weighing and ignition protocol was applied in order to quantify their mineral fraction. Atmospheric deposition is both a strong source of nutrients and metals for marine ecosystems in this area. However, there are few data on trace-metal deposition in the literature, since their deposition measurement is difficult to perform. In order to obtain more information from CARAGA atmospheric deposition samples, this study aimed to test their relevance in estimating elemental fluxes in addition to total mass fluxes. The elemental chemical analysis of ashed CARAGA filter samples was based on an acid digestion and an elemental analysis by inductively coupled plasma atomic emission spectroscopy (ICP-AES and mass spectrometry (MS in a clean room. The sampling and analytical protocols were tested to determine the elemental composition for mineral dust tracers (Al, Ca, K, Mg and Ti, nutrients (P and Fe and trace metals (Cd, Co, Cr, Cu, Mn, Ni, V and Zn from simulated wet deposition of dust analogues and traffic soot. The relative mass loss by dissolution in wet deposition was lower than 1 % for Al and Fe, and reached 13 % for P due to its larger solubility in water. For trace metals, this loss represented less than 3 % of the total mass concentration, except for Zn, Cu and Mn for which it could reach 10 %, especially in traffic soot. The chemical contamination during analysis was negligible for all the elements except for Cd
14. Source apportionment of atmospheric bulk deposition in the Belgrade urban area using Positive Matrix factorization
Science.gov (United States)
Tasić, M.; Mijić, Z.; Rajšić, S.; Stojić, A.; Radenković, M.; Joksić, J.
2009-04-01
The primary objective of the present study was to assess anthropogenic impacts of heavy metals to the environment by determination of total atmospheric deposition of heavy metals. Atmospheric depositions (wet + dry) were collected monthly, from June 2002 to December 2006, at three urban locations in Belgrade, using bulk deposition samplers. Concentrations of Fe, Al, Pb, Zn, Cu, Ni, Mn, Cr, V, As and Cd were analyzed using atomic absorption spectrometry. Based upon these results, the study attempted to examine elemental associations in atmospheric deposition and to elucidate the potential sources of heavy metal contaminants in the region by the use of multivariate receptor model Positive Matrix Factorization (PMF).
15. Source apportionment of atmospheric bulk deposition in the Belgrade urban area using Positive Matrix factorization
International Nuclear Information System (INIS)
Tasic, M; Mijic, Z; Rajsic, S; Stojic, A; Radenkovic, M; Joksic, J
2009-01-01
The primary objective of the present study was to assess anthropogenic impacts of heavy metals to the environment by determination of total atmospheric deposition of heavy metals. Atmospheric depositions (wet + dry) were collected monthly, from June 2002 to December 2006, at three urban locations in Belgrade, using bulk deposition samplers. Concentrations of Fe, Al, Pb, Zn, Cu, Ni, Mn, Cr, V, As and Cd were analyzed using atomic absorption spectrometry. Based upon these results, the study attempted to examine elemental associations in atmospheric deposition and to elucidate the potential sources of heavy metal contaminants in the region by the use of multivariate receptor model Positive Matrix Factorization (PMF).
16. Biomonitoring along the french coastline: could mercury isotopic composition indicate a temporal change in hg reaching the coastal zone?
OpenAIRE
Briant, Nicolas; Chouvelon, Tiphaine; Brach-papa, Christophe; Chiffoleau, Jean-francois; Savoye, Nicolas; Sonke, Jeroen; Knoery, Joel
2017-01-01
Mercury (Hg) is a natural element toxic to all living organisms. Its ocean biogeochemical cycle is dominated by atmospheric deposition, which human activities contribute to disrupt signi cantly, and to a lesser extent by riverine discharge. This element is bioamplifed and bioaccumulated in marine food webs. since mercury concentrations in some coastal animal species of high trophic level approach sanitary thresholds, understanding biogeochemical processes and mechanisms leading to these eleva...
17. Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta
Directory of Open Access Journals (Sweden)
Junbao Yu
2014-01-01
Full Text Available The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD using automatic sampling equipment. The results showed that SO42- and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3-–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4+–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3-–N and NH4+–N was ~31.38% and ~20.50% for the contents of NO3-–N and NH4+–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.
18. Wet and dry atmospheric depositions of inorganic nitrogen during plant growing season in the coastal zone of Yellow River Delta.
Science.gov (United States)
Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun
2014-01-01
The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.
19. Atmospheric deposition and environmental quality in Italy
International Nuclear Information System (INIS)
Mosello, R.
1993-01-01
For Italy's Po River hydrological basin, artificial reservoirs have a great importance; water reserve is about 1600 million cubic meters for the hydroelectric reservoirs and about 76 million cubic meters for irrigation. Relevant to studies on water quality and acidification in the Po River Basin, this paper reviews some aspects of research on atmospheric deposition, i.e., geographical variability, long term trends, and effects on surface waters
20. The deposition of radioiodine onto rice plant from atmosphere
International Nuclear Information System (INIS)
Uchida, Shigeo; Muramatsu, Yasuyuki; Yoshida, Satoshi; Sumiya, Misako; Ohmomo, Yoichiro.
1994-01-01
Radiation dose estimations are usually made with the aid of assessment models in which model parameters such as the transfer factors of radionuclides from one environmental compartment to another are involved. In simple models the parameters are often described as the concentration ratio of a radionuclide between two compartments, when the system is under equilibrium condition. In this paper, the authors introduce the values of the parameters of radioiodine obtained by tracer experiments. Laboratory experiments on the transfer parameters of radionuclides from the atmosphere to rice plant were carried out in the atmosphere-to-crops system (deposition pathway). It is known that the typical chemical species of gaseous iodine in the atmosphere are elemental iodine (I 2 ) and methyliodide (CH 3 I). The deposition characteristics of both chemical species of gaseous iodine to rice grains were obtained. Mass normalized deposition velocity (V D ) and grain number normalized deposition velocity (V S ) of gaseous elemental iodine (I 2 ) and also methyliodide (CH 3 I) on unhulled rice were measured. Both V D and V S of methyliodide were about one percent of those of elemental iodine. Distribution pattern of methyliodide between unhulled rice and brown rice was significantly lower than that of elemental one. For wet deposition, we investigated the retention of radioiodines (iodide [I - ] and iodate [IO 3 - ] on rice grains and their translocation from the surface of the grains to brown rice. Though the ears were dipped into the solution containing 125 I - or 125 IO 3 - more than 15 min., both iodine species in the solutions were hardly taken up to the rice grains. The transfer rates of iodide and iodate, which are defined as 'the amount of the iodine in brown rice' divided by 'the amount of iodide in unhulled rice' were about 0.015 and 0.04, respectively. The rates were not changed with time after the radioiodine application. (author)
1. Atmospheric heavy metal deposition in the Copenhagen area
DEFF Research Database (Denmark)
Andersen, Allan; Hovmand, Mads Frederik; Johnsen, Ib
1978-01-01
Atmospheric dry and wet deposition (bulk precipitation) of the heavy metals Cu, Pb, Zn, Ni, V and Fe over the Copenhagen area was measured by sampling in plastic funnels from 17 stations during a twelve-month period. Epigeic bryophytes from 100 stations in the area were analysed for the heavy...
2. Potential geographic distribution of atmospheric nitrogen deposition from intensive livestock production in North Carolina, USA
International Nuclear Information System (INIS)
Costanza, Jennifer K.; Marcinko, Sarah E.; Goewert, Ann E.; Mitchell, Charles E.
2008-01-01
To examine the consequences of increased spatial aggregation of livestock production facilities, we estimated the annual production of nitrogen in livestock waste in North Carolina, USA, and analyzed the potential distribution of atmospheric nitrogen deposition from confined animal feeding operations ('CAFO') lagoons. North Carolina is a national center for industrial livestock production. Livestock is increasingly being raised in CAFOs, where waste is frequently held, essentially untreated, in open-air lagoons. Reduced nitrogen in lagoons is volatilized as ammonia (NH 3 ), transported atmospherically, and deposited to other ecosystems. The Albemarle-Pamlico Sound, NC, is representative of nitrogen-sensitive coastal waters, and is a major component of the second largest estuarine complex in the U.S. We used GIS to model the area of water in the Sound within deposition range of CAFOs. We also evaluated the number of lagoons within deposition range of each 1 km 2 grid cell of the state. We considered multiple scenarios of atmospheric transport by varying distance and directionality. Modeled nitrogen deposition rates were particularly elevated for the Coastal Plain. This pattern matches empirical data, suggesting that observed regional patterns of reduced nitrogen deposition can be largely explained by two factors: limited atmospheric transport distance, and spatial aggregation of CAFOs. Under our medium-distance scenario, a small portion (roughly 22%) of livestock production facilities contributes disproportionately to atmospheric deposition of nitrogen to the Albemarle-Pamlico Sound. Furthermore, we estimated that between 14-37% of the state receives 50% of the state's atmospheric nitrogen deposition from CAFO lagoons. The estimated total emission from livestock is 134,000 t NH 3 yr -1 , 73% of which originates from the Coastal Plain. Stronger waste management and emission standards for CAFOs, particularly those on the Coastal Plain nearest to sensitive water bodies
3. Effect of argon addition into oxygen atmosphere on YBCO thin films deposition
International Nuclear Information System (INIS)
Mozhaev, P. B.; Borisenko, I. V.; Ovsyannikov, G. A.; Kuehle, A.; Bindslev-Hansen, J.; Johannes, L.; Skov, J. L.
2002-01-01
Multicomponent nature of the YBa 2 Cu 3 O x (YBCO) high-temperature superconductor makes difficult fabrication of smooth thin films: every local deviation from stoichiometry can result in seeding of a non-superconducting oxide particle. High density of such particles on typical YBCO thin film surface, however, presumes overall non-stoichiometry of the film. Such an effect can result from (i) non-uniform material transport from target to substrate, and (ii) re-evaporation or re-sputtering from the growing film surface. The first reason is more usual for laser ablation deposition technique, the second is typical for long sputtering deposition processes. Substitution of oxygen with argon in the deposition atmosphere improves surface quality of YBCO thin films deposited both by laser ablation and DC-sputtering at high pressure techniques. In the first case, the ablated species are scattered different ways in the oxygen atmosphere. Addition of argon decreases the inelastic scattering of barium; the proper part of Ar in the deposition atmosphere makes scattering and, hence, transport of all atoms uniform. The YBCO films deposited by DC-sputtering at high pressure technique are Ba-deficient also, but the reason is re-sputtering of Ba from the growing film as a result of negative oxygen ions bombardment. Such bombardment can lead also to chemical interaction of the deposited material with the substrate, as in the case of deposition of YBCO thin film on the CeO 2 buffer layer on sapphire. Substitution of oxygen with argon not only suppresses ion bombardment of the film, but also increases discharge stability due to presence of positive Ar + ions. The limiting factor of argon substitution is sufficient oxygenation of the growing oxide film. When oxygen partial pressure is too small, the superconducting quality of the YBCO thin film decreases and such a decrease cannot be overcome by prolonged oxygenation after deposition. (Authors)
4. Toward Synchronous Evaluation of Source Apportionments for Atmospheric Concentration and Deposition of Sulfate Aerosol Over East Asia
Science.gov (United States)
Itahashi, S.
2018-03-01
Source apportionments for atmospheric concentration, dry deposition, and wet deposition of sulfate aerosol (SO42-) were synchronously evaluated over East Asia, a main source of anthropogenic sulfur dioxide (SO2) emissions. Estimating dry deposition was difficult owing to the difficulty of measuring deposition velocity directly; therefore, sensitivity simulations using two dry deposition schemes were conducted. Moreover, sensitivity simulations for different emission inventories, the largest uncertainty source in the air quality model, were also conducted. In total, four experimental settings were used. Model performance was verified for atmospheric concentration and wet deposition using a ground-based observation network in China, Korea, and Japan, and all four model settings captured the observations. The underestimation of wet deposition over China was improved by an adjusted approach that linearly scaled the modeled precipitation values to observations. The synchronous evaluation of source apportionments for atmospheric concentration and dry and wet deposition showed the dominant contribution of anthropogenic emissions from China to the atmospheric concentration and deposition in Japan. The contributions of emissions from volcanoes were more important for wet deposition than for atmospheric concentration. Differences in the dry deposition scheme and emission inventory did not substantially influence the relative ratio of source apportionments over Japan. Because the dry deposition was more attributed to local factors, the differences in dry deposition may be an important determinant of the source contributions from China to Japan. Verification of these findings, including the dry deposition velocity, is necessary for better understanding of the behavior of sulfur compound in East Asia.
5. Wet and Dry Atmospheric Mercury Deposition Accumulates in Watersheds of the Northeastern United States
Science.gov (United States)
Boyer, E. W.; Grant, C.; Grimm, J.; Drohan, P. J.; Bennett, J.; Lawler, D.
2013-12-01
Mercury emissions to the atmosphere from coal-fired power plants and other sources such as waste incineration can be deposited to landscapes in precipitation and in dry fallout. Some mercury reaches watersheds and streams, where it can accumulate in sediments and biota. Human exposure to mercury occurs primarily through fish consumption, and currently mercury fish eating advisories are in place for many of the streams and lakes in the state. Here, we explored mercury in air, soils, water, and biota. To quantify atmospheric mercury deposition, we measured both wet and dry mercury deposition at over 10 locations in Pennsylvania, from which we present variation in mercury deposition and initial assessments of factors affecting the patterns. Further, we simulated mercury deposition at unmonitored locations in Pennsylvania and the northeastern United States over space and time with a high-resolution modeling technique that reflects storm tracks and air flow patterns. To consider mercury accumulation in watersheds, we collected data on soil mercury concentrations in a set of soil samples, and collected baseline data on mercury in streams draining 35 forested watersheds across Pennsylvania, spanning gradients of atmospheric deposition, climate and geology. Mercury concentrations were measured in stream water under base-flow conditions, in streambed sediments, aquatic mosses, and in fish tissues from brook trout. Results indicate that wet and dry atmospheric deposition is a primary source of mercury that is accumulating in watersheds of Pennsylvania and the northeastern United States.
6. Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in Shanghai: the spatio-temporal variation and source identification
Science.gov (United States)
Cheng, Chen; Bi, Chunjuan; Wang, Dongqi; Yu, Zhongjie; Chen, Zhenlou
2018-03-01
This study investigated the dry and wet deposition fluxes of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Shanghai, China. The flux sources were traced based on composition and spatio-temporal variation. The results show that wet deposition concentrations of PAHs ranged from 0.07 to 0.67 mg·L-1 and were correlated with temperature ( P<0.05). Dry deposition of PAHs concentrations ranged from 3.60-92.15 mg·L-1 and were higher in winter and spring than in summer and autumn. The annual PAH average fluxes were 0.631 mg·m-2·d-1 and 4.06 mg·m-2·d-1 for wet and dry deposition, respectively. The highest wet deposition of PAH fluxes was observed in summer, while dry deposition fluxes were higher in winter and spring. Atmospheric PAHs were deposited as dry deposition in spring and winter, yet wet deposition was the dominant pathway during summer. Total atmospheric PAH fluxes were higher in the northern areas than in the southern areas of Shanghai, and were also observed to be higher in winter and spring. Annual deposition of atmospheric PAHs was about 10.8 t in across all of Shanghai. Wet deposition of PAHs was primarily composed of two, three, or four rings, while dry deposition of PAHs was composed of four, five, or six rings. The atmospheric PAHs, composed of four, five, or six rings, primarily existed in the form of particulates. Coal combustion and vehicle emissions were the dominant sources of PAH in the observed area of downtown Shanghai. In suburban areas, industrial pollution, from sources such as coke oven, incinerator, and oil fired power plant, was as significant as vehicle emissions in contributing to the deposition of PAHs.
7. Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition
Science.gov (United States)
Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae
2017-12-01
Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.
8. Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma
Science.gov (United States)
Khan, T. M.; Pokle, A.; Lunney, J. G.
2018-04-01
Two methods of atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver are described. In both methods the ablation plume, produced by a 248 nm, 20 ns excimer laser in gas, is strongly confined near the target and forms a nanoparticle aerosol. For both the flowing gas, and the atmospheric plasma from a dielectric barrier discharge plasma source, the aerosol is entrained in the flow and carried to a substrate for deposition. The nanoparticle films produced by both methods were examined by electron microscopy and optical absorption spectroscopy. With plasma assistance, the deposition rate was significantly enhanced and the film morphology altered. With argon gas, isolated nanoparticles of 20 nm size were obtained, whereas in argon plasma, the nanoparticles are aggregated in clusters of 90 nm size. Helium gas also leads to the deposition of isolated nanoparticles, but with helium plasma, two populations of nanoparticles are observed: one of rounded particles with a mean size of 26 nm and the other of faceted particles with a mean size 165 nm.
9. Atmospheric deposition of radioactive cesium (137Cs) associated with dust events in East Asia
International Nuclear Information System (INIS)
Fujiwara, H.
2010-01-01
Since the cessation of atmospheric nuclear testing in 1980, there has been no known serious atmospheric contamination by radioactive cesium (sup(137)Cs) apart from the Chernobyl nuclear reactor accident in 1986. There now remain only small amounts of anthropogenic radionuclides in the atmosphere that can be directly related to past testing. However, sup(137)Cs is still regularly found in atmospheric deposition samples in Japan. In this study, we analyzed sup(137)Cs monitoring data, meteorological data, and field survey results to investigate the recent transport and deposition of sup(137)Cs associated with dust phenomena. Monthly records of nationwide sup(137)Cs deposition in Japan during the 1990s show a consistent seasonal variation, with higher levels of deposition occurring in spring. In March 2002, an unexpectedly high amount of sup(137)Cs was deposited in the northwestern coastal area of Japan at the same time as an Asian dust event was observed. Analysis of land-based weather data showed that sandstorms and other dust-raising phenomena also occurred in March 2002 over areas of Mongolia and northeastern China where grassland and shrubs predominated. Furthermore, radioactivity measurements showed sup(137)Cs enrichment in the surface layer of grassland soils in the areas affected by these sandstorms. These results suggest that grasslands are potential sources of sup(137)Cs-bearing dust. Continued desertification of the East Asian continent in response to recent climate change can be expected to result in an increase in sup(137)Cs-bearing soil particles in the atmosphere, and their subsequent re-deposition in Japan. However, soil dust is also raised around Japanese monitoring sites by the strong winds that are common in Japan in spring, and this local dust might also contribute to sup(137)Cs deposition in Japan. To estimate the relative contributions of local and distant dust events to the total sup(137)Cs deposition, we monitored deposition of mineral particles
10. Dispersion, deposition and resuspension of atmospheric contaminants
International Nuclear Information System (INIS)
Anon.
1985-01-01
The following topics are discussed: dry deposition, oil shale fugitive air emissions, particle resuspension and translocation, theoretical studies and applications, and processing of emissions by clouds and precipitation. The concentration of contaminant species in air is governed by the rate of input from sources, the rate of dilution or dispersion as a result of air turbulence, and the rate of removal to the surface by wet and dry deposition processes. Once on the surface, contaminants also may be resuspended, depending on meteorological and surface conditions. An understanding of these processes is necessary for accurate prediction of exposures of hazardous or harmful contaminants to humans, animals, and crops. In the field, plume dispersion and plume depletion by dry deposition were studied by the use of tracers. Dry deposition was investigated for particles of both respiration and inhalation interest. Complementary dry deposition studies of particles to rock canopies were conducted under controlled conditions in a wind tunnel. Because of increasing concern about hazardous, organic gases in the atmosphere some limited investigations of the dry deposition of nitrobenzene to a lichen mat were conducted in a stirred chamber. Resuspension was also studied using tracers and contaminated surfaces and in the wind tunnel. The objective of the resuspension studies was to develop and verify models for predicting the airborne concentrations of contaminants over areas with surface contamination, develop resuspension rate predictors for downwind transport, and develop predictors for resuspension input to the food chain. These models will be of particular relevance to the evaluation of deposition and resuspension of both radionuclides and chemical contaminants
11. Mosses as an integrating tool for monitoring PAH atmospheric deposition: comparison with total deposition and evaluation of bioconcentration factors. A year-long case-study.
Science.gov (United States)
Foan, Louise; Domercq, Maria; Bermejo, Raúl; Santamaría, Jesús Miguel; Simon, Valérie
2015-01-01
Polycyclic aromatic hydrocarbon (PAH) atmospheric deposition was evaluated at a remote site in Northern Spain using moss biomonitoring with Hylocomium splendens (Hedw.) Schimp., and by measuring the total deposition fluxes of PAHs. The year-long study allowed seasonal variations of PAH content in mosses to be observed, and these followed a similar trend to those of PAH fluxes in total deposition. Generally, atmospheric deposition of PAHs is greater in winter than in summer, due to more PAH emissions from domestic heating, less photoreactivity of the compounds, and intense leaching of the atmosphere by wet deposition. However, fractionation of these molecules between the environmental compartments occurs: PAH fluxes in total deposition and PAH concentrations in mosses are correlated with their solubility (r=0.852, pPAH fluxes can be estimated with moss biomonitoring data if the bioconcentration or 'enriching' factors are known. Copyright © 2014 Elsevier Ltd. All rights reserved.
12. Hg concentrations from Late Triassic and Early Jurassic sedimentary rocks: first order similarities and second order depositional and diagenetic controls
Science.gov (United States)
Yager, J. A.; West, A. J.; Bergquist, B. A.; Thibodeau, A. M.; Corsetti, F. A.; Berelson, W.; Bottjer, D. J.; Rosas, S.
2016-12-01
Mercury concentrations in sediments have recently gained prominence as a potential tool for identifying large igneous province (LIP) volcanism in sedimentary records. LIP volcanism coincides with several mass extinctions during the Phanerozoic, but it is often difficult to directly tie LIP activity with the record of extinction in marine successions. Here, we build on mercury concentration data reported by Thibodeau et al. (Nature Communications, 7:11147, 2016) from the Late Triassic and Early Jurassic of New York Canyon, Nevada, USA. Increases in Hg concentrations in that record were attributed to Central Atlantic Magmatic Province (CAMP) activity in association with the end-Triassic mass extinction. We expand the measured section from New York Canyon and report new mercury concentrations from Levanto, Peru, where dated ash beds provide a discrete chronology, as well as St. Audrie's Bay, UK, a well-studied succession. We correlate these records using carbon isotopes and ammonites and find similarities in the onset of elevated Hg concentrations and Hg/TOC in association with changes in C isotopes. We also find second order patterns that differ between sections and may have depositional and diagenetic controls. We will discuss these changes within a sedimentological framework to further understand the controls on Hg concentrations in sedimentary records and their implications for past volcanism.
13. Atmospheric deposition, CO2, and change in the land carbon sink
DEFF Research Database (Denmark)
Martinez-Fernandez, Cristina; Vicca, Sara; Janssens, Ivan A.
2017-01-01
Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and gene...... show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling....
14. Worldwide dispersion and deposition of radionuclides produced in atmospheric tests.
Science.gov (United States)
Bennett, Burton G
2002-05-01
Radionuclides produced in atmospheric nuclear tests were widely dispersed in the global environment. From the many measurements of the concentrations in air and the deposition amounts, much was learned of atmospheric circulation and environmental processes. Based on these results and the reported fission and total yields of individual tests, it has been possible to devise an empirical model of the movement and residence times of particles in the various atmospheric regions. This model, applied to all atmospheric weapons tests, allows extensive calculations of air concentrations and deposition amounts for the entire range of radionuclides produced throughout the testing period. Especially for the shorter-lived fission radionuclides, for which measurement results at the time of the tests are less extensive, a more complete picture of levels and isotope ratios can be obtained, forming a basis for improved dose estimations. The contributions to worldwide fallout can be inferred from individual tests, from tests at specific sites, or by specific countries. Progress was also made in understanding the global hydrological and carbon cycles from the tritium and 14C measurements. A review of the global measurements and modeling results is presented in this paper. In the future, if injections of materials into the atmosphere occur, their anticipated motions and fates can be predicted from the knowledge gained from the fallout experience.
15. Watershed-scale changes in terrestrial nitrogen cycling during a period of decreased atmospheric nitrate and sulfur deposition
Science.gov (United States)
Sabo, Robert D.; Scanga, Sara E.; Lawrence, Gregory B.; Nelson, David M.; Eshleman, Keith N.; Zabala, Gabriel A.; Alinea, Alexandria A.; Schirmer, Charles D.
2016-01-01
Recent reports suggest that decreases in atmospheric nitrogen (N) deposition throughout Europe and North America may have resulted in declining nitrate export in surface waters in recent decades, yet it is unknown if and how terrestrial N cycling was affected. During a period of decreased atmospheric N deposition, we assessed changes in forest N cycling by evaluating trends in tree-ring δ15N values (between 1980 and 2010; n = 20 trees per watershed), stream nitrate yields (between 2000 and 2011), and retention of atmospherically-deposited N (between 2000 and 2011) in the North and South Tributaries (North and South, respectively) of Buck Creek in the Adirondack Mountains, USA. We hypothesized that tree-ring δ15N values would decline following decreases in atmospheric N deposition (after approximately 1995), and that trends in stream nitrate export and retention of atmospherically deposited N would mirror changes in tree-ring δ15N values. Three of the six sampled tree species and the majority of individual trees showed declining linear trends in δ15N for the period 1980–2010; only two individual trees showed increasing trends in δ15N values. From 1980 to 2010, trees in the watersheds of both tributaries displayed long-term declines in tree-ring δ15N values at the watershed scale (R = −0.35 and p = 0.001 in the North and R = −0.37 and p <0.001 in the South). The decreasing δ15N trend in the North was associated with declining stream nitrate concentrations (−0.009 mg N L−1 yr−1, p = 0.02), but no change in the retention of atmospherically deposited N was observed. In contrast, nitrate yields in the South did not exhibit a trend, and the watershed became less retentive of atmospherically deposited N (−7.3% yr−1, p < 0.001). Our δ15N results indicate a change in terrestrial N availability in both watersheds prior to decreases in atmospheric N deposition, suggesting that decreased atmospheric N deposition was not the sole driver of
16. Atmospheric mercury pollution around a chlor-alkali plant in Flix (NE Spain): an integrated analysis.
Science.gov (United States)
Esbrí, José M; López-Berdonces, Miguel Angel; Fernández-Calderón, Sergio; Higueras, Pablo; Díez, Sergi
2015-04-01
An integrated analysis approach has been applied to a mercury (Hg) case study on a chlor-alkali plant located in the Ebro River basin, close to the town of Flix (NE Spain). The study focused on atmospheric Hg and its incorporation in soils and lichens close to a mercury cell chlor-alkali plant (CAP), which has been operating since the end of the 19th century. Atmospheric Hg present in the area was characterized by means of seven total gaseous mercury (TGM) surveys carried out from 2007 to 2012. Surveys were carried out by car, walking, and at fixed locations, and covered an area of some 12 km(2) (including the CAP area, the village in which workers live, Flix town, and the Sebes Wildlife Reserve). Finally, an atmospheric Hg dispersion model was developed with ISC-AERMOD software validated by a lichen survey of the area. The results for the atmospheric compartment seem to indicate that the Flix area currently has the highest levels of Hg pollution in Spain on the basis of the extremely high average concentrations in the vicinity of the CAP (229 ng m(-3)). Moreover, the Hg(0) plume affects Flix town center to some extent, with values well above the international thresholds for residential areas. Wet and dry Hg deposition reached its highest values on the banks of the Ebro River, and this contributes to increased soil contamination (range 44-12,900 ng g(-1), average 775 ng g(-1)). A good fit was obtained between anomalous areas indicated by lichens and the dispersion model for 1 year.
17. Apportioning global and non-global components of mercury deposition through (210)Pb indexing.
Science.gov (United States)
Lamborg, Carl H; Engstrom, Daniel R; Fitzgerald, William F; Balcom, Prentiss H
2013-03-15
Our previous work has documented a correlation between Hg concentrations and (210)Pb activity measured in wet deposition that might be used to help apportion sources of Hg in precipitation. Here we present the results of a 27-month precipitation collection effort using co-located samplers for Hg and (210)Pb designed to assess this hypothesis. Study sites were located on the east and west coasts of North America, in the continental interior, and on the Florida Peninsula. Relatively high variability in Hg/(210)Pb ratios was found at all sites regionally and seasonally (e.g., overall: 0.99-9.13ngdpm(-1)). The ratio of average volume-weighted Hg concentrations and (210)Pb activities showed consistent trends (higher in impacted area), with Glacier Bay in southeast Alaska, exhibiting the lowest value. Assuming that Glacier Bay represents a benchmark for a site with no regional contribution, we estimate less than 50% of the Hg input was "global" at the Seattle and Florida sites. Differences in Hg/(210)Pb in wet deposition could be due to either a regional/local source contribution of Hg, or a regional/local enhancement in the removal of Hg from the atmosphere (i.e., oxidants), however, this approach is not capable of discerning between these two possibilities. Thus, this method of source apportionment represents an estimate of the maximal amount of Hg contributed by regional sources and may be limited in regions of deep convective mixing. Copyright © 2012 Elsevier B.V. All rights reserved.
18. Passive sampling for the isotopic fingerprinting of atmospheric mercury
Science.gov (United States)
Bergquist, B. A.; MacLagan, D.; Spoznar, N.; Kaplan, R.; Chandan, P.; Stupple, G.; Zimmerman, L.; Wania, F.; Mitchell, C. P. J.; Steffen, A.; Monaci, F.; Derry, L. A.
2017-12-01
Recent studies show that there are variations in the mercury (Hg) isotopic signature of atmospheric Hg, which demonstrates the potential for source tracing and improved understanding of atmospheric cycling of Hg. However, current methods for both measuring atmospheric Hg and collecting enough atmospheric Hg for isotopic analyses require expensive instruments that need power and expertise. Additionally, methods for collecting enough atmospheric Hg for isotopic analysis require pumping air through traps for long periods (weeks and longer). Combining a new passive atmospheric sampler for mercury (Hg) with novel Hg isotopic analyses will allow for the application of stable Hg isotopes to atmospheric studies of Hg. Our group has been testing a new passive sampler for gaseous Hg that relies on the diffusion of Hg through a diffusive barrier and adsorption onto a sulphur-impregnated activated carbon sorbent. The benefit of this passive sampler is that it is low cost, requires no power, and collects gaseous Hg for up to one year with linear, well-defined uptake, which allows for reproducible and accurate measurements of atmospheric gaseous Hg concentrations ( 8% uncertainty). As little as one month of sampling is often adequate to collect sufficient Hg for isotopic analysis at typical background concentrations. Experiments comparing the isotopic Hg signature in activated carbon samples using different approaches (i.e. by passive diffusion, by passive diffusion through diffusive barriers of different thickness, by active pumping) and at different temperatures confirm that the sampling process itself does not impose mass-independent fractionation (MIF). However, sampling does result in a consistent and thus correctable mass-dependent fractionation (MDF) effect. Therefore, the sampler preserves Hg MIF with very high accuracy and precision, which is necessary for atmospheric source tracing, and reasonable MDF can be estimated with some increase in error. In addition to
19. Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts
NARCIS (Netherlands)
Phoenix, G.K.; Hicks, W.K.; Cinderby, S.; Kuylenstierna, J.C.I.; Stock, W.D.; Dentener, F.J.; Giller, K.E.; Austin, A.T.; Lefroy, R.D.B.; Gimeno, B.S.; Ashmore, M.R.; Ineson, P.
2006-01-01
Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi-natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition
20. Effects of atmospheric deposition of pesticides on terrestrial organisms in the Netherlands
NARCIS (Netherlands)
Jong FMW de; Luttik R; SEC
2004-01-01
At present there is much focus on the atmospheric dispersal of pesticides. However, there is very little known about the effects of atmospheric deposition, especially in terrestrial ecosystems. In the study described here, a start has been made to clarify the possible effects on terrestrial
1. CO2 deficit in temperate forest soils receiving high atmospheric N-deposition.
Science.gov (United States)
Fleischer, Siegfried
2003-02-01
Evidence is provided for an internal CO2 sink in forest soils, that may have a potential impact on the global CO2-budget. Lowered CO2 fraction in the soil atmosphere, and thus lowered CO2 release to the aboveground atmosphere, is indicated in high N-deposition areas. Also at forest edges, especially of spruce forest, where additional N-deposition has occurred, the soil CO2 is lowered, and the gradient increases into the closed forest. Over the last three decades the capacity of the forest soil to maintain the internal sink process has been limited to a cumulative supply of approximately 1000 and 1500 kg N ha(-1). Beyond this limit the internal soil CO2 sink becomes an additional CO2 source, together with nitrogen leaching. This stage of "nitrogen saturation" is still uncommon in closed forests in southern Scandinavia, however, it occurs in exposed forest edges which receive high atmospheric N-deposition. The soil CO2 gradient, which originally increases from the edge towards the closed forest, becomes reversed.
2. Local deposition of mercury in topsoils around coal-fired power plants: is it always true?
Science.gov (United States)
Rodriguez Martin, José Antonio; Nanos, Nikos; Grigoratos, Theodoros; Carbonell, Gregoria; Samara, Constantini
2014-09-01
Mercury (Hg) is a toxic element that is emitted to the atmosphere through human activities, mainly fossil fuel combustion. Hg accumulations in soil are associated with atmospheric deposition, while coal-burning power plants remain the most important source of anthropogenic mercury emissions. In this study, we analyzed the Hg concentration in the topsoil of the Kozani-Ptolemais basin where four coal-fired power plants (4,065 MW) run to provide 50 % of electricity in Greece. The study aimed to investigate the extent of soil contamination by Hg using geostatistical techniques to evaluate the presumed Hg enrichment around the four power plants. Hg variability in agricultural soils was evaluated using 276 soil samples from 92 locations covering an area of 1,000 km(2). We were surprised to find a low Hg content in soil (range 1-59 μg kg(-1)) and 50 % of samples with a concentration lower than 6 μg kg(-1). The influence of mercury emissions from the four coal-fired power plants on soil was poor or virtually nil. We associate this effect with low Hg contents in the coal (1.5-24.5 μg kg(-1)) used in the combustion of these power plants (one of the most Hg-poor in the world). Despite anthropic activity in the area, we conclude that Hg content in the agricultural soils of the Kozani-Ptolemais basin is present in low concentrations.
3. Investigation of deposition characteristics and properties of high-rate deposited silicon nitride films prepared by atmospheric pressure plasma chemical vapor deposition
International Nuclear Information System (INIS)
Kakiuchi, H.; Nakahama, Y.; Ohmi, H.; Yasutake, K.; Yoshii, K.; Mori, Y.
2005-01-01
Silicon nitride (SiN x ) films have been prepared at extremely high deposition rates by the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique on Si(001) wafers from gas mixtures containing He, H 2 , SiH 4 and N 2 or NH 3 . A 150 MHz very high frequency (VHF) power supply was used to generate high-density radicals in the atmospheric pressure plasma. Deposition rate, composition and morphology of the SiN x films prepared with various deposition parameters were studied by scanning electron microscopy and Auger electron spectroscopy. Fourier transformation infrared (FTIR) absorption spectroscopy was also used to characterize the structure and the chemical bonding configurations of the films. Furthermore, etching rate with buffered hydrofluoric acid (BHF) solution, refractive index and capacitance-voltage (C-V) characteristics were measured to evaluate the dielectric properties of the films. It was found that effective passivation of dangling bonds and elimination of excessive hydrogen atoms at the film-growing surface seemed to be the most important factor to form SiN x film with a dense Si-N network. The C-V curve of the optimized film showed good interface properties, although further improvement was necessary for use in the industrial metal-insulator-semiconductor (MIS) applications
4. Deposition velocity of gaseous organic iodine from the atmosphere to rice plants
International Nuclear Information System (INIS)
Muramatsu, Yasuyuki; Shigeo-Uchida; Sumiya, Misako; Ohmomo, Yoichiro
1996-01-01
To obtain parameter values for the assessment of 129 I transfer from the atmosphere to rice, deposition of CH 3 I to rice plants has been studied. The mass normalized deposition velocity (V D ) of CH 3 I for rough (unhulled) rice was 0.00048 cm 3 g -1 s -1 , which is about 1/300 of that of I 2 . Translocation of iodine, deposited as CH 3 I on leaves and stems, to rice grain was negligibly small. Distribution of iodine between hull and inner part of the grain was found to depend also on the chemical forms of atmospheric iodine to be deposited. The ratio of the iodine distribution in a grain exposed to CH 3 I was as follows: rough rice: brown rice (hulled rice):polished rice = 1.0:0.49:0.38. The distribution ratio in polished grains for CH 3 I exposed rice was about 20 times higher than that for I 2 . 22 refs., 1 fig., 6 tabs
5. Preparation of CdxHg1-xTe films by the method of vapour-phase epitaxy of HgTe on CdTe substrates with subsequent mutual diffusion
International Nuclear Information System (INIS)
Varavin, V.S.; Sidorov, Yu.G.; Remesnik, V.G.; Chikichev, S.I.; Nis, I.E.
1994-01-01
Mirror-like HgTe films have been grown on CdTe substrates of various orientations by vapor deposition of HgTe in temperature gradient. Deposition rates fell in the range of 5-12 μm/h. Subsequent annealing has permitted production of Hg 1-x Cd x Te layers about 15 μm in thickness. Canier density in annealed n-type specimens has been found to constitute (1-20)x10 15 cm -3 at carrier mobility of (2-5)x10 4 cm 2 xV -1 xs -1 and in p-type films - (1-5)x10 16 cm -3 and 200-350 cm 2 xV -1 xs -1 (77 K) respectively
6. Atmospheric Mercury Transport Across Southern Lake Michigan: Influence from the Chicago/Gary Urban Area
Science.gov (United States)
Gratz, L. E.; Keeler, G. J.; Dvonch, J. T.
2008-12-01
The local and regional impacts of mercury emissions from major urban and industrial areas are critical to quantify in order to further understand mercury cycling in the environment. The Chicago/Gary urban area is one such location in which mercury emissions from industrial sources are significant and regional mercury transport needs to be further examined. Speciated atmospheric mercury was measured in Chicago, IL and Holland, MI from July to November 2007 to better characterize the impact of Chicago/Gary on southwest Michigan. Previous work under the 1994-1995 Lake Michigan Mass Balance Study (LMMBS) indicated that the highest levels of mercury deposition in southwest Michigan occurred with transport from the Chicago/Gary area, particularly with rapid transport where less mercury was deposited close to sources(1). However, at that time it was not possible to measure reactive gas phase mercury (RGM), a highly-soluble form of mercury in industrial emissions that is readily removed from the atmosphere. Since the LMMBS, the development of speciated mercury systems has made it possible to continuously monitor gaseous elemental mercury (Hg0), particulate mercury (HgP), and RGM. These measurements are useful for understanding atmospheric mercury chemistry and differentiating between local and regional source impacts due to the different behaviors of reactive and elemental mercury. Results from 2007 show that, on average, Hg0 and HgP were 1.5 times higher and RGM was 2 times higher in Chicago than in Holland. Mean mercury wet deposition was nearly 3 times higher in Chicago than in Holland. Meteorological analysis indicates that transport across the lake from Chicago/Gary occurred frequently during the study. Additional measurements of O3, SO2, meteorological parameters, event mercury and trace element precipitation samples, and modeled back-trajectories are used to discern regional transport events from local deposition and characterize the impact of the Chicago/Gary urban
7. Optimizing best management practices to control anthropogenic sources of atmospheric phosphorus deposition to inland lakes.
Science.gov (United States)
Weiss, Lee; Thé, Jesse; Winter, Jennifer; Gharabaghi, Bahram
2018-04-18
Excessive phosphorus loading to inland freshwater lakes around the globe has resulted in nuisance plant growth along the waterfronts, degraded habitat for cold water fisheries, and impaired beaches, marinas and waterfront property. The direct atmospheric deposition of phosphorus can be a significant contributing source to inland lakes. The atmospheric deposition monitoring program for Lake Simcoe, Ontario indicates roughly 20% of the annual total phosphorus load (2010-2014 period) is due to direct atmospheric deposition (both wet and dry deposition) on the lake. This novel study presents a first-time application of the Genetic Algorithm (GA) methodology to optimize the application of best management practices (BMPs) related to agriculture and mobile sources to achieve atmospheric phosphorus reduction targets and restore the ecological health of the lake. The novel methodology takes into account the spatial distribution of the emission sources in the airshed, the complex atmospheric long-range transport and deposition processes, cost and efficiency of the popular management practices and social constraints related to the adoption of BMPs. The optimization scenarios suggest that the optimal overall capital investment of approximately $2M,$4M, and $10M annually can achieve roughly 3, 4 and 5 tonnes reduction in atmospheric P load to the lake, respectively. The exponential trend indicates diminishing returns for the investment beyond roughly$3M per year and that focussing much of this investment in the upwind, nearshore area will significantly impact deposition to the lake. The optimization is based on a combination of the lowest-cost, most-beneficial and socially-acceptable management practices that develops a science-informed promotion of implementation/BMP adoption strategy. The geospatial aspect to the optimization (i.e. proximity and location with respect to the lake) will help land managers to encourage the use of these targeted best practices in areas that
8. Meridional transport and deposition of atmospheric 10Be
Directory of Open Access Journals (Sweden)
J. Feichter
2009-01-01
Full Text Available 10Be concentrations measured in ice cores exhibit larger temporal variability than expected based on theoretical production calculations. To investigate whether this is due to atmospheric transport a general circulation model study is performed with the 10Be production divided into stratospheric, tropospheric tropical, tropospheric subtropical and tropospheric polar sources. A control run with present day 10Be production rate is compared with a run during a geomagnetic minimum. The present 10Be production rate is 4–5 times higher at high latitudes than in the tropics whereas during a period of no geomagnetic dipole field it is constant at all latitudes. The 10Be deposition fluxes, however, show a very similar latitudinal distribution in both the present day and the geomagnetic minimum run indicating that 10Be is well mixed in the atmosphere before its deposition. This is also confirmed by the fact that the contribution of 10Be produced in the stratosphere is dominant (55%–70% and relatively constant at all latitudes. The contribution of stratospheric 10Be is approximately 70% in Greenland and 60% in Antarctica reflecting the weaker stratosphere-troposphere air exchange in the Southern Hemisphere.
9. Multi-year Surface Deposition of {sup 210}Pb and {sup 210}Po at Lisbon - Atmospheric Depositions of {sup 210}Pb and {sup 210}Po in Lisbon, Portugal
Energy Technology Data Exchange (ETDEWEB)
Carvalho, Fernando P.; Oliveira, Joao M.; Alberto, G. [Instituto Superior Tecnico/ Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, E.N. 10, 2686-953 Sacavem (Portugal)
2014-07-01
The long lived radon daughters {sup 210}Pb and {sup 210}Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual {sup 210}Pb flux was 66±12 Bq m{sup -2}, and the average annual {sup 210}Po flux was 8±3 Bq m{sup -2}, with an overall {sup 210}Po/{sup 210}Pb activity ratio of 0.15±0.06. Direct determination of the {sup 210}Pb atmospheric flux was compared with the {sup 210}Pb excess determined in soil surface layers along with atmospheric depositions of {sup 137}Cs. The deposition of atmospheric {sup 210}Pb was positively correlated with seasonal rainfall, while {sup 210}Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high {sup 210}Po/{sup 210}Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of {sup 210}Pb and {sup 210}Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)
10. Exchange pattern of gaseous elemental mercury in landfill: mercury deposition under vegetation coverage and interactive effects of multiple meteorological conditions.
Science.gov (United States)
Tao, Zhengkai; Liu, Yang; Zhou, Meng; Chai, Xiaoli
2017-12-01
Landfill is known as a potential source of atmospheric Hg and an important component of the local or regional atmospheric Hg budget. This study investigated the gaseous elemental Hg surface-air fluxes under differing conditions at a typical municipal solid waste landfill site, highlighting the interactive effects of plant coverage and meteorological conditions. The results indicated that Hg fluxes exhibited a feature represented by diel variation. In particular, Hg deposition was observed under a condition of Kochia sieversiana coverage, whereas emission that occurred after K. sieversiana was removed. Hg emission was the dominant mode under conditions of Setaria viridis coverage and its removal; however, the average Hg emission flux with the S. viridis coverage was nearly four times lower than after its removal. These findings verified that the plant coverage should be a key factor influencing the Hg emission from landfills. In addition, Hg fluxes were correlated positively with solar radiation and air/soil temperature and correlated inversely with relative humidity under all conditions, except K. sieversiana coverage. This suggested that the interactive effects of meteorological conditions and plant coverage played a jointly significant role in the Hg emission from landfills. It was established that K. sieversiana can inhibit Hg emission efficiently, and therefore, it could potentially be suitable for use as a plant-based method to control Hg pollution from landfills.
11. Intensive atmospheric mercury measurements at Terra Nova Bay in Antarctica during November and December 2000
Science.gov (United States)
Sprovieri, F.; Pirrone, N.; Hedgecock, I. M.; Landis, M. S.; Stevens, R. K.
2002-12-01
It is well known that due to its long atmospheric residence time, mercury is distributed on a global scale and aeolian transport is believed to be the major contributor to mercury in polar environments. No measurements of reactive gaseous mercury (RGM) at all have ever been performed in the Antarctic before. Hg0(g) concentrations were in the range 0.29 to 2.3 ng m-3, with an average value of 0.9 ± 0.3 ng m-3. RGM was measured using KCl-coated annular denuders and a speciation unit coupled to a TGM analyzer; concentrations ranged from 10.5 to 334 pg m-3, with an average of 116.2 ± 77.8 pg m-3. The Hg0(g) measurements are in good agreement with the few data available for such southerly latitudes. The RGM concentrations are as high as those found in some industrial environments; the high concentrations in the absence of local sources (anthropogenic or natural) show that in situ gas phase oxidation of Hg0 is the most important factor influencing RGM production and therefore also Hg deposition. The toxicity of Hg means that the consequences of high concentrations of oxidized and soluble Hg species depositing in the fragile Antarctic environment could be serious indeed.
12. Shifts in lake N: P stoichiometry and nutrient limitation driven by atmospheric nitrogen deposition
Science.gov (United States)
Elser, J.J.; Andersen, T.; Baron, Jill S.; Bergstrom, A.-K.; Jansson, M.; Kyle, M.; Nydick, K.R.; Steger, L.; Hessen, D.O.
2009-01-01
Human activities have more than doubled the amount of nitrogen (N) circulating in the biosphere. One major pathway of this anthropogenic N input into ecosystems has been increased regional deposition from the atmosphere. Here we show that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus (P) in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted. Under low N deposition, phytoplankton growth is generally N-limited; however, in high-N deposition lakes, phytoplankton growth is consistently P-limited. Continued anthropogenic amplification of the global N cycle will further alter ecological processes, such as biogeochemical cycling, trophic dynamics, and biological diversity, in the world's lakes, even in lakes far from direct human disturbance.
13. Preparation and characterization of pulsed laser deposited CdTe thin films at higher FTO substrate temperature and in Ar + O{sub 2} atmosphere
Energy Technology Data Exchange (ETDEWEB)
Ding, Chao; Ming, Zhenxun [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Li, Bing, E-mail: libing70@126.com [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Feng, Lianghuan [College of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Wu, Judy [Department of Physics and Astronomy, Kansas University, Lawrence 66045 (United States)
2013-06-20
Highlights: • CdTe films were deposited by PLD at high substrate temperatures (400 °C, 550 °C). • CdTe films were achieved under the atmosphere (1.2 Torr) of Ar mixed with O{sub 2}. • Deposited CdTe films were cubic phase and had strong (1 0 0) preferred orientation. • Scanning electron microscope (SEM) showed an average grain size of 0.3–0.6 μm. • The ultra-thin film (CdS/PLD-CdTe) solar cell with efficiency of 6.68% was made. -- Abstract: Pulsed laser deposition (PLD) is one of the promising techniques for depositing cadmium telluride (CdTe) thin films. It has been reported that PLD CdTe thin films were almost deposited at the lower substrate temperatures (<300 °C) under vacuum conditions. However, the poor crystallinity of CdTe films prepared in this way renders them not conducive to the preparation of high-efficiency CdTe solar cells. To obtain high-efficiency solar cell devices, better crystallinity and more suitable grain size are needed, which requires the CdTe layer to be deposited by PLD at high substrate temperatures (>400 °C). In this paper, CdTe layers were deposited by PLD (KrF, λ = 248 nm, 10 Hz) at different higher substrate temperatures (T{sub s}). Excellent performance of CdTe films was achieved at higher substrate temperatures (400 °C, 550 °C) under an atmosphere of Ar mixed with O{sub 2} (1.2 Torr). X-ray diffraction analysis confirmed the formation of CdTe cubic phase with a strong (1 0 0) preferential orientation at all substrates temperatures on 60 mJ laser energy. The optical properties of CdTe were investigated, and the band gaps of CdTe films were 1.51 eV and 1.49 eV at substrate temperatures of 400 °C and 550 °C, respectively. Scanning electron microscopy (SEM) showed an average grain size of 0.3–0.6 μm. Thus, under these conditions of the atmosphere of Ar + O{sub 2} (15 Torr) and at the relatively high T{sub s} (500 °C), an thin-film (FTO/PLD-CdS (100 nm)/PLD-CdTe (∼1.5 μm)/HgTe: Cu/Ag) solar cell with an
14. The Use of Biomonitors to Monitor Atmospheric Deposition of 210Pb
International Nuclear Information System (INIS)
Jeran, Z.; Jacimovic, R.
1998-01-01
The main source of 210 Pb in the environment is the exhalation of 222 Rn gas from the ground to the atmosphere during the radioactive decay of natural uranium - radium chain. In the atmosphere this radionuclide is rapidly attached to small particles - aerosols, predominantly on those particles below 0.3 mm. The half-life of 210 Pb is longer than the atmospheric residence time of the aerosols on which it resides (1). By sedimentation and washout of aerosols this nuclide is then transferred to the soil or vegetation. The other main sources include burning of fossil fuels and phosphate fertilizers. The usual way to determine the levels of 210 Pb and other radionuclides in the atmosphere is the use of a high volume filter system, which should operate for a long time to collect enough material for analysis. An other approach to determining the outdoor levels of radionuclides is the use of suitable biomonitors such as lichens or mosses. These organisms, although neither evolutionarie nor taxonomically related, have some common characteristics which enable them to be used as monitors for atmospheric pollution. They lack roots and protective organs against the substances derived from the atmosphere (stomata and cuticle) and are very efficient accumulators of atmospheric particulate material and chemical substances such as radionuclides or heavy metals (2). The levels of these substances in lichens and mosses are usually much higher than in air particulates or precipitation and for these reason the analysis is much easier. Another advantage of biomonitors over conventional sampling of air particulates or precipitation is that the collection of lichens or mosses is very cheap therefore allows a very large number of sites to be included in the same survey and permits detailed geographical deposition patterns to be drawn (3). It must be emphasised that concentration data on elements or radionuclides in lichens or mosses represent the relative deposition patterns over a certain
15. Atmospheric depositions around a heavily industrialized area in a seasonally dry tropical environment of India
International Nuclear Information System (INIS)
2005-01-01
Clear and throughfall bulk depositions were collected in the downwind of a highly industrialized region in Sonbhadra district of India to estimate the influence of anthropogenic activities on chemical composition of depositions. Significant spatial and temporal variations in depositions of cations and anions were observed. Depositions were higher near the thermal power stations and coalmines as compared to distantly situated site. Seasonally summer samples showed maximum cation and anion depositions followed by winter and minimum in rainy season. The mean pH of the depositions indicates that rainfall in the area is alkaline. Among the anions, maximum deposition was recorded for SO 4 2- followed by NO 3 - and minimum for Cl - . Among the cations, Ca 2+ deposition was maximum followed by NH 4 + . Na + , K + and Mg 2+ deposition rates showed more or less similar values. The depositions of cations and anions as well as pH were higher in throughfall than clearfall samples. Results of the present study suggest that atmospheric depositions are strongly modified due to thermal power stations and coal mines in the area. - Atmospheric abundance of cations have neutralized the acidity of depositions around a heavily industrialized area in India
16. Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments
Science.gov (United States)
Oldani, K. M.; Mladenov, N.; Williams, M. W.
2013-12-01
The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.
17. Properties of alumina films prepared by metal-organic chemical vapour deposition at atmospheric pressure in hte presence of small amounts of water
NARCIS (Netherlands)
Haanappel, V.A.C.; Haanappel, V.A.C.; van Corbach, H.D.; Rem, J.B.; Fransen, T.; Gellings, P.J.
1995-01-01
Thin alumina films were deposited on stainless steel, type AISI 304. The deposition process was carried out in nitrogen with low partial pressures of water (0–2.6 × 10−2 kPa (0−0.20 mmHg)) by metal-organic chemical vapour deposition (MOCVD) with aluminium-tri-sec-butoxide (ATSB) as the precursor.
18. Atmospheric deposition patterns of (210)Pb and (7)Be in Cienfuegos, Cuba.
Science.gov (United States)
Alonso-Hernández, Carlos M; Morera-Gómez, Yasser; Cartas-Águila, Héctor; Guillén-Arruebarrena, Aniel
2014-12-01
The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03' N, 80° 29' W) (Cuba), are analysed in this paper. Measurement of (7)Be and (210)Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of (7)Be and (210)Pb are in the range of 13.2-132 and 1.24-8.29 Bq m(-2), and their mean values are: 56.6 and 3.97 Bq m(-2), respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of (210)Pb and (7)Be were 47 and 700 Bq m(-2) y(-1), respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of (7)Be and (210)Pb were moderately well correlated with precipitation and well correlated with one another. The (210)Pb/(7)Be ratios in the monthly depositions samples varied in the range of 0.05-0.10 and showed a strong correlation with the number of rainy days. Copyright © 2014 Elsevier Ltd. All rights reserved.
19. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA
International Nuclear Information System (INIS)
Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita
2013-01-01
Highlights: ► Hg and Pb concentration and isotopic compositions traced anthropogenic sources. ► Concentrations and metal loadings of Hg and Pb increased during the smelting period. ► Hg isotopic compositions changed during smelting compared to the pre-smelting period. ► Data indicate mass independent fractionation of Hg isotopes. - Abstract: Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ 202 Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ 202 Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206 Pb/ 207 Pb and 208 Pb/ 207 Pb isotopic compositions during these periods. Data for Δ 199 Hg and Δ 201 Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ 199 Hg and Δ 201 Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger
20. Evidence for the Importance of Atmospheric Nitrogen Deposition to Eutrophic Lake Dianchi, China
Science.gov (United States)
Zhan, X.; Bo, Y.; Zhou, F.; Liu, X.; Paerl, H. W.; Shen, J.; Wang, R.; Li, F. R.; Tao, S.; Yanjun, D.; Tang, X.
2017-12-01
Elevated atmospheric nitrogen (N) deposition has significantly influenced aquatic ecosystems, especially with regard to their N budgets and phytoplankton growth potentials. Compared to a considerable number of studies on oligotrophic lakes and oceanic waters, little evidence for the importance of N deposition has been generated for eutrophic lakes, even though emphasis has been placed on reducing external N inputs to control eutrophication in these lakes. Our high-resolution observations of atmospheric depositions and riverine inputs of biologically reactive N species into eutrophic Lake Dianchi (the sixth largest freshwater lake in China) shed new light onto the contribution of N deposition to total N loads. Annual N deposition accounted for 15.7% to 16.6% of total N loads under variable precipitation conditions, 2-fold higher than previous estimates (7.6%) for the Lake Dianchi. The proportion of N deposition to total N loads further increased to 27-48% in May and June when toxic blooms of the ubiquitous non-N2 fixing cyanobacteria Microcystis spp. are initiated and proliferate. Our observations reveal that reduced N (59%) contributes a greater amount than oxidized N to total N deposition, reaching 56-83% from late spring to summer. Progress toward mitigating eutrophication in Lake Dianchi and other bloom-impacted eutrophic lakes will be difficult without reductions in ammonia emissions and subsequent N deposition.
1. Atmospheric nitrogen deposition budget in a subtropical hydroelectric reservoir (Nam Theun II case study, Lao PDR)
Science.gov (United States)
Adon, Marcellin; Galy-Lacaux, Corinne; Serça, Dominique; Guerin, Frederic; Guedant, Pierre; Vonghamsao, Axay; Rode, Wanidaporn
2016-04-01
With 490 km² at full level of operation, Nam Theun 2 (NT2) is one of the largest hydro-reservoir in South East Asia. NT2 is a trans-basin hydropower project that diverts water from the Nam Theun river (a Mekong tributary) to the Xe Ban Fai river (another Mekong tributary). Atmospheric deposition is an important source of nitrogen (N), and it has been shown that excessive fluxes of N from the atmosphere has resulted in eutrophication of many coastal waters. A large fraction of atmospheric N input is in the form of inorganic N. This study presents an estimation of the atmospheric inorganic nitrogen budget into the NT2 hydroelectric reservoir based on a two-year monitoring (July 2010 to July 2012) including gas concentrations and precipitation. Dry deposition fluxes are calculated from monthly mean surface measurements of NH3, HNO3 and NO2 concentrations (passive samplers) together with simulated deposition velocities, and wet deposition fluxes from NH4+ and NO3- concentrations in single event rain samples (automated rain sampler). Annual rainfall amount was 2500 and 3160 mm for the two years. The average nitrogen deposition flux is estimated at 1.13 kgN.ha-1.yr-1 from dry processes and 5.52 kgN.ha-1.yr-1 from wet ones, i.e., an average annual total nitrogen flux of 6.6 kgN.ha-1.yr-1 deposited into the NT2 reservoir. The wet deposition contributes to 83% of the total N deposition. The nitrogen deposition budget has been also calculated over the rain tropical forest surrounding the reservoir. Due to higher dry deposition velocities above forested ecosystems, gaseous dry deposition flux is estimated at 4.0 kgN.ha-1.yr-1 leading to a total nitrogen deposition about 9.5 kgN.ha-1.yr-1. This result will be compared to nitrogen deposition in the African equatorial forested ecosystems in the framework of the IDAF program (IGAC-DEBITS-AFrica).
2. Atmospheric deposition of nutrients to north Florida rivers: A multivariate statistical analysis. Final report. Master's thesis
International Nuclear Information System (INIS)
Fu, J.
1991-01-01
Atmospheric nutrient input to the Apalachicola Bay estuary was studied because it has been demonstrated that atmospheric deposition can be a major source of nutrients to eastern U.S. estuaries. Besides the Apalachicola River, the Sopchoppy and the Ochlockonee were also selected for a comparative analysis. Receptor model, absolute principal of component analysis (APCA), and mass balance methods were applied in the study. The results of the study show that nitrogen is probably not a limiting nutrient in the three rivers because their N:P mole ratios are nearly 3 times higher than the Redfield ratio for photosynthesis. The total atmospheric nitrogen depositions in the three river watershed are at least as great as their river fluxes. In the Apalachicola River, the atmospheric source of nitrogen is found to be several times higher than the largest possible input of urban sewage. Atmospheric deposition, therefore, might be the dominant nitrogen source entering the estuary. The results of APCA show that Apalachicola River water is mainly a mixture of components that correspond in their compositions to aged rain, ground water, and fresh rain. Atmospheric nitrate deposition is the result of the air pollution, i.e., acid rain. The studies also show that the annual average deposition of nitrate has a narrow range, mainly from 5.8 to 11.5 kg/ha/yr in most of the NADP sites in the 8 southeastern states. Since all the software and data sets employed in the study are accessible nationwide, the methods could be applied in other watersheds
3. Distribution and air-sea exchange of mercury (Hg in the Yellow Sea
Directory of Open Access Journals (Sweden)
Z. J. Ci
2011-03-01
Full Text Available The Yellow Sea, surrounded by East China and the Korea Peninsula, is a potentially important receptor for anthropogenic mercury (Hg emissions from East Asia. However, there is little documentation about the distribution and cycle of Hg in this marine system. During the cruise covering the Yellow Sea in July 2010, gaseous elemental mercury (GEM or Hg(0 in the atmosphere, total Hg (THg, reactive Hg (RHg and dissolved gaseous mercury (DGM, largely Hg(0 in the waters were measured aboard the R/V Kexue III. The mean (±SD concentration of GEM over the entire cruise was 2.61 ± 0.50 ng m−3 (range: 1.68 to 4.34 ng m−3, which were generally higher than other open oceans. The spatial distribution of GEM generally reflected a clear gradient with high levels near the coast of East China and low levels in open waters, suggesting the significant atmospheric Hg outflow from East China. The mean concentration of THg in the surface waters was 1.69 ± 0.35 ng l−1 and the RHg accounted for a considerable fraction of THg (RHg: 1.08 ± 0.28 ng l−1, %RHg/THg = 63.9%. The mean concentration of DGM in the surface waters was 63.9 ± 13.7 pg l−1 and always suggested the supersaturation of Hg(0 in the surface waters with respect to Hg(0 in the atmosphere (the degree of saturation: 7.8 ± 2.3 with a range of 3.6–14.0. The mean Hg(0 flux at the air-sea interface was estimated to be 18.3 ± 11.8 ng m−2 h−1 based on a two-layer exchange model. The high wind speed and DGM levels induced the extremely high Hg(0 emission rates. Measurements at three stations showed no clear vertical patterns of DGM, RHg and THg in the water column. Overall, the elevated Hg levels in the Yellow Sea compared with other open oceans suggested that the human activity has influenced the oceanic Hg cycle downwind of East Asia.
4. Long-term mercury dynamics in UK soils
International Nuclear Information System (INIS)
Tipping, E.; Wadsworth, R.A.; Norris, D.A.; Hall, J.R.; Ilyin, I.
2011-01-01
A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 μg Hg m -2 a -1 to rural soils, 19 μg Hg m -2 a -1 to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg 0 per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: → Spatial data for mercury in UK soils can be related to past atmospheric deposition. → The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. → UK soils currently contribute more Hg 0 to the atmosphere than human activities. → Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg 0 to the global circulation.
5. [Pollution evaluation and health risk assessment of heavy metals from atmospheric deposition in Lanzhou].
Science.gov (United States)
Li, Ping; Xue, Su-Yin; Wang, Sheng-Li; Nan, Zhong-Ren
2014-03-01
In order to evaluate the contamination and health risk of heavy metals from atmospheric deposition in Lanzhou, samples of atmospheric deposition were collected from 11 sampling sites respectively and their concentrations of heavy metals were determined. The results showed that the average contents of Cu, Pb, Cd, Cr, Ni, Zn and Mn were 82.22, 130.31, 4.34, 88.73, 40.64, 369.23 and 501.49 mg x kg(-1), respectively. There was great difference among different functional areas for all elements except Mn. According to the results, the enrichment factor score of Mn was close to 1, while the enrichment of Zn, Ni, Cu and Cr was more serious, and Pb and Cd were extremely enriched. The assessment results of geoaccumulation index of potential ecological risk indicated that the pollution of Cd in the atmospheric deposition of Lanzhou should be classified as extreme degree, and that of Cu, Ni, Zn, Pb as between slight and extreme degrees, and Cr as practically uncontaminated. Contaminations of atmospheric dust by heavy metals in October to the next March were more serious than those from April to August. Health risk assessment indicated that the heavy metals in atmospheric deposition were mainly ingested by human bodies through hand-mouth ingestion. The non-cancer risk was higher for children than for adults. The order of non-cancer hazard indexes of heavy metals was Pb > Cr > Cd > Cu > Ni > Zn. The non-cancer hazard indexes and carcinogen risks of heavy metals were both lower than their threshold values, suggesting that they will not harm the health.
6. Seasonal atmospheric deposition variations of polychlorinated biphenyls (PCBs) and comparison of some deposition sampling techniques.
Science.gov (United States)
2011-03-01
Ambient air and bulk deposition samples were collected between June 2008 and June 2009. Eighty-three polychlorinated biphenyl (PCB) congeners were targeted in the samples. The average gas and particle PCB concentrations were found as 393 ± 278 and 70 ± 102 pg/m(3), respectively, and 85% of the atmospheric PCBs were in the gas phase. Bulk deposition samples were collected by using a sampler made of stainless steel. The average PCB bulk deposition flux value was determined as 6,020 ± 4,350 pg/m(2) day. The seasonal bulk deposition fluxes were not statistically different from each other, but the summer flux had higher values. Flux values differed depending on the precipitation levels. The average flux value in the rainy periods was 7,480 ± 4,080 pg/m(2) day while the average flux value in dry periods was 5,550 ± 4,420 pg/m(2) day. The obtained deposition values were lower than the reported values given for the urban and industrialized areas, yet close to the ones for the rural sites. The reported deposition values were also influenced by the type of the instruments used. The average dry deposition and total deposition velocity values calculated based on deposition and concentration values were found as 0.23 ± 0.21 and 0.13 ± 0.13 cm/s, respectively.
7. Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains
Science.gov (United States)
Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K.
2012-08-01
Many alpine areas are experiencing deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, atmospheric deposition sources may be an important source of C and nutrients for these environments. We evaluated the magnitude of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long-term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were 1.12 ± 0.19 mg l-1, and weekly concentrations reached peaks as high at 6-10 mg l-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. To investigate potential sources of C in atmospheric deposition, we evaluated the chemical quality of dissolved organic matter (DOM) and relationships between DOM and other solutes in wet deposition. Relationships between DOC concentration, fluorescence, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring, which may reflect an association of DOM with dust. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples. Our C budget estimates for the Green Lake 4 catchment
8. Effects of geographical location and land use on atmospheric deposition of nitrogen in the State of Connecticut
International Nuclear Information System (INIS)
Luo, Yuzhou; Yang, Xiusheng; Carley, Robert J.; Perkins, Christopher
2003-01-01
High ambient concentrations of tropospheric nitrogen and dry deposition flux were found in urban areas. - A network of eight monitoring stations was established to study the atmospheric nitrogen concentration and deposition in the State of Connecticut. The stations were classified into urban, rural, coastal and inland categories to represent the geographical location and land use characteristics surrounding the monitoring sites. Nitrogen species including nitrate, ammonium, nitric acid vapor and organic nitrogen in the air and precipitation were collected, analyzed and used to infer nitrogen concentrations and dry and wet deposition flux densities for the sampling period from 1997 through 1999, with independently collected meteorological data. Statistical analyses were conducted to evaluate the spatial variations of atmospheric concentration and deposition fluxes of total nitrogen in Connecticut. A slightly higher atmospheric concentration of total nitrogen was observed along the Connecticut coastline of Long Island Sound compared to inland areas, while the differences of nitrogen deposition fluxes were insignificant between coastal and inland sites. The land use characteristics surrounding the monitoring sites had profound effects on the atmospheric nitrogen concentration and dry deposition flux. The ambient nitrogen concentration over the four urban sites was averaged 38.9% higher than that over the rural sites, resulting a 58.0% higher dry deposition flux in these sites compared to their rural counterparts. The local industrial activities and traffic emissions of nitrogen at urban areas had significant effects on the spatial distribution of atmospheric nitrogen concentration and dry deposition flux in the State. Wet and total deposition fluxes appeared to be invariant between the monitoring sites, except for high flux densities measured at Old Greenwich, a monitoring station near to and downwind of the New York and New Jersey industrial complexes
9. Enhanced Hg{sup 2+} removal and Hg{sup 0} re-emission control from wet fuel gas desulfurization liquors with additives
Energy Technology Data Exchange (ETDEWEB)
Tingmei Tang; Jiang Xu; Rongjie Lu; Jingjing Wo; Xinhua Xu [Zhejiang University, Hangzhou (China). Department of Environmental Engineering
2010-12-15
Secondary atmospheric pollutions may result from wet flue gas desulfurization (FGD) systems caused by the reduction of Hg{sup 2+} to Hg{sup 0}. The present study employed three agents: Na{sub 2}S, 2,4,6-trimercaptotiazine, trisodium salt nonahydrate (TMT) and sodium dithiocarbamate (DTCR) to precipitate aqueous Hg{sup 2+} in simulated desulfurization solutions. The effects of the precipitator's dosing quantity, the initial pH value, the reaction temperature, the concentrations of Cl{sup -} and other metal ions (e.g. Cu{sup 2+} and Pb{sup 2+}) on Hg{sup 2+} removal were studied. A linear relationship was observed between Hg{sup 2+} removal efficiency and the increasing precipitator's doses along with initial pH. The addition of chloride and metal ions impaired the Hg{sup 2+} removal from solutions due to the complexation of Cl{sup -} and Hg{sup 2+} as well as the chelating competition between Hg{sup 2+} and other metal ions. Based on a comprehensive comparison of the treatment effects, DTCR was found to be the most effective precipitating agent. Moreover, all the precipitating agents were potent enough to inhibit Hg{sup 2+} reduction as well as Hg{sup 0} re-emission from FGD liquors. More than 90% Hg{sup 2+} was captured by precipitating agents while Hg{sup 2+} reduction efficiency decreased from 54% to just less than 3%. The additives could efficiently control the secondary Hg{sup 0} pollution from FGD liquors. 21 refs., 6 figs.
10. Current and future levels of mercury atmospheric pollution on a global scale
Science.gov (United States)
Pacyna, Jozef M.; Travnikov, Oleg; De Simone, Francesco; Hedgecock, Ian M.; Sundseth, Kyrre; Pacyna, Elisabeth G.; Steenhuisen, Frits; Pirrone, Nicola; Munthe, John; Kindbom, Karin
2016-10-01
An assessment of current and future emissions, air concentrations, and atmospheric deposition of mercury worldwide is presented on the basis of results obtained during the performance of the EU GMOS (Global Mercury Observation System) project. Emission estimates for mercury were prepared with the main goal of applying them in models to assess current (2013) and future (2035) air concentrations and atmospheric deposition of this contaminant. The combustion of fossil fuels (mainly coal) for energy and heat production in power plants and in industrial and residential boilers, as well as artisanal and small-scale gold mining, is one of the major anthropogenic sources of Hg emissions to the atmosphere at present. These sources account for about 37 and 25 % of the total anthropogenic Hg emissions globally, estimated to be about 2000 t. Emissions in Asian countries, particularly in China and India, dominate the total emissions of Hg. The current estimates of mercury emissions from natural processes (primary mercury emissions and re-emissions), including mercury depletion events, were estimated to be 5207 t year-1, which represents nearly 70 % of the global mercury emission budget. Oceans are the most important sources (36 %), followed by biomass burning (9 %). A comparison of the 2035 anthropogenic emissions estimated for three different scenarios with current anthropogenic emissions indicates a reduction of these emissions in 2035 up to 85 % for the best-case scenario. Two global chemical transport models (GLEMOS and ECHMERIT) have been used for the evaluation of future mercury pollution levels considering future emission scenarios. Projections of future changes in mercury deposition on a global scale simulated by these models for three anthropogenic emissions scenarios of 2035 indicate a decrease in up to 50 % deposition in the Northern Hemisphere and up to 35 % in Southern Hemisphere for the best-case scenario. The EU GMOS project has proved to be a very important
11. Current and future levels of mercury atmospheric pollution on a global scale
Directory of Open Access Journals (Sweden)
J. M. Pacyna
2016-10-01
Full Text Available An assessment of current and future emissions, air concentrations, and atmospheric deposition of mercury worldwide is presented on the basis of results obtained during the performance of the EU GMOS (Global Mercury Observation System project. Emission estimates for mercury were prepared with the main goal of applying them in models to assess current (2013 and future (2035 air concentrations and atmospheric deposition of this contaminant. The combustion of fossil fuels (mainly coal for energy and heat production in power plants and in industrial and residential boilers, as well as artisanal and small-scale gold mining, is one of the major anthropogenic sources of Hg emissions to the atmosphere at present. These sources account for about 37 and 25 % of the total anthropogenic Hg emissions globally, estimated to be about 2000 t. Emissions in Asian countries, particularly in China and India, dominate the total emissions of Hg. The current estimates of mercury emissions from natural processes (primary mercury emissions and re-emissions, including mercury depletion events, were estimated to be 5207 t year−1, which represents nearly 70 % of the global mercury emission budget. Oceans are the most important sources (36 %, followed by biomass burning (9 %. A comparison of the 2035 anthropogenic emissions estimated for three different scenarios with current anthropogenic emissions indicates a reduction of these emissions in 2035 up to 85 % for the best-case scenario. Two global chemical transport models (GLEMOS and ECHMERIT have been used for the evaluation of future mercury pollution levels considering future emission scenarios. Projections of future changes in mercury deposition on a global scale simulated by these models for three anthropogenic emissions scenarios of 2035 indicate a decrease in up to 50 % deposition in the Northern Hemisphere and up to 35 % in Southern Hemisphere for the best-case scenario. The EU GMOS project has
12. Electrical properties of MIS devices on CdZnTe/HgCdTe
Science.gov (United States)
Lee, Tae-Seok; Jeoung, Y. T.; Kim, Hyun Kyu; Kim, Jae Mook; Song, Jinhan; Ann, S. Y.; Lee, Ji Y.; Kim, Young Hun; Kim, Sun-Ung; Park, Mann-Jang; Lee, S. D.; Suh, Sang-Hee
1998-10-01
In this paper, we report the capacitance-voltage (C-V) properties of metal-insulator-semiconductor (MIS) devices on CdTe/HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe/HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n-type and the carrier concentration, ND is low 1015 cm-3 after Hg-vacancy annealing at 260 degrees Celsius. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0% bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C-V measurement is conducted at 80 K and 1 MHz. C-V curve of MIS devices on CdTe/HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg-vacancy annealing process. A negative flat band voltage (VFB approximately equals -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe/HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te4+ on the surface after etching with bromine in methanol solution.
13. The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution.
Science.gov (United States)
Niu, Zhenchuan; Zhang, Xiaoshan; Wang, Sen; Ci, Zhijia; Kong, Xiangrui; Wang, Zhangwei
2013-09-01
One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p 0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g(-1), respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m(-3).
14. Atmospheric heavy metal deposition in the Copenhagen area
Energy Technology Data Exchange (ETDEWEB)
Andersen, A; Hovmand, M F; Johnsen, I
1978-10-01
Transport of heavy metals from the atmosphere to the soil and vegetation takes place by dust fall, bulk precipitation, and gas/aerosol adsorption processes. Atmospheric dry and wet deposition of the heavy metals lead, zinc, nickel, vanadium, iron, and copper over the Copenhagen area was measured by sampling in plastic funnels from 17 stations throughout the area for 12 months. Epigeic bryophytes, epiphytic lichen, and topsoil samples were analyzed. A linear correlation between bulk precipitation and heavy metal concentration in lichens and bryophytes was found. An exponential correlation between bulk precipitation and heavy metal concentration in soil was noted. Regional variation of the heavy metal levels in the Copenhagen area was described, and three sub-areas with high metal burdens were distinguished. (10 diagrams, 8 graphs, 13 references, 2 tables)
15. The effects of atmospheric nitrogen deposition in the Rocky Mountains of Colorado and southern Wyoming, USA-a critical review
International Nuclear Information System (INIS)
Burns, Douglas A.
2004-01-01
The Rocky Mountains of Colorado and southern Wyoming receive atmospheric nitrogen (N) deposition that ranges from 2 to 7 kg ha -1 yr -1 , and some previous research indicates pronounced ecosystem effects at the highest rates of deposition. This paper provides a critical review of previously published studies on the effects of atmospheric N deposition in the region. Plant community changes have been demonstrated through N fertilization studies, however, N limitation is still widely reported in alpine tundra and subalpine forests of the Front Range, and sensitivity to changes in snow cover alone indicate the importance of climate sensitivity in these ecosystems. Retention of N in atmospheric wet deposition is 3 - concentrations have not been demonstrated, and future trend analyses must consider the role of climate as well as N deposition. Relatively high rates of atmospheric N deposition east of the Divide may have altered nutrient limitation of phytoplankton, species composition of diatoms, and amphibian populations, but most of these effects have been inconclusive to date, and additional studies are needed to confirm hypothesized cause and effect relations. Projected future population growth and energy use in Colorado and the west increase the likelihood that the subtle effects of atmospheric N deposition now evident in the Front Range will become more pronounced and widespread in the future. - The effects of nitrogen deposition will become more evident as growth increases
16. Atmospheric nitrogen deposition: Revisiting the question of the importance of the organic component
International Nuclear Information System (INIS)
Cornell, Sarah E.
2011-01-01
The organic component of atmospheric reactive nitrogen plays a role in biogeochemical cycles, climate and ecosystems. Although its deposition has long been known to be quantitatively significant, it is not routinely assessed in deposition studies and monitoring programmes. Excluding this fraction, typically 25-35%, introduces significant uncertainty in the determination of nitrogen deposition, with implications for the critical loads approach. The last decade of rainwater studies substantially expands the worldwide dataset, giving enough global coverage for specific hypotheses to be considered about the distribution, composition, sources and effects of organic-nitrogen deposition. This data collation and meta-analysis highlights knowledge gaps, suggesting where data-gathering efforts and process studies should be focused. New analytical techniques allow long-standing conjectures about the nature and sources of organic N to be investigated, with tantalising indications of the interplay between natural and anthropogenic sources, and between the nitrogen and carbon cycles. - Highlights: → Organic-nitrogen deposition is globally ubiquitous. → Geographic patterns can now be seen in the near-global dataset. → Organic N can be formed through interactions of biogenic and anthropogenic compounds. → Neglecting organic N in deposition assessments increases critical loads uncertainty - Routinely including the organic component of atmospheric deposition (known to be around 25-35% worldwide) would make the understanding and prediction of nitrogen biogeochemistry more robust. This paper makes a preliminary global synthesis based on literature reports.
17. RF sputtered HgCdTe films for tandem cell applications
International Nuclear Information System (INIS)
Wang, S.L.; Lee, S.H.; Gupta, A.; Compaan, A.D.
2004-01-01
Polycrystalline Hg 1-x Cd x Te films were investigated for their potential as bottom cells of a CdTe-based tandem solar cell. The films were deposited by RF sputtering from a cold pressed target containing 30% HgTe+70% CdTe. The as-deposited films were highly resistive with (111) preferred orientation and a bandgap of ∝1.0 eV. Various thermal treatment schemes were investigated under different conditions of ambient and temperature to reduce the resistivity. The film properties were analyzed using infrared transmission spectra, energy dispersive X-ray spectra and X-ray diffraction. N doped p-HgCdTe films were also prepared by reactive sputtering in a N 2 /Ar ambient. P-n junction solar cells were fabricated with CdS films as the heterojunction partner. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
18. Atmospheric spatial atomic layer deposition of in-doped ZnO
NARCIS (Netherlands)
Illiberi, A.; Scherpenborg, R.; Roozeboom, F.; Poodt, P.
2014-01-01
Indium-doped zinc oxide (ZnO:In) has been grown by spatial atomic layer deposition at atmospheric pressure (spatial-ALD). Trimethyl indium (TMIn), diethyl zinc (DEZ) and deionized water have been used as In, Zn and O precursor, respectively. The metal content of the films is controlled in the range
19. Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment
International Nuclear Information System (INIS)
Bergknut, Magnus; Laudon, Hjalmar; Jansson, Stina; Larsson, Anna; Gocht, Tilman; Wiberg, Karin
2011-01-01
The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time. - Graphical abstract: Display Omitted Highlights: → The fluxes of organic pollutants in a pristine boreal catchment were measured. → Most of the input and export occurred during winter and spring flood. → 96.0-99.9% of received bulk deposition was retained by the landscape. → Organic pollutants will impact boreal stream waters for an extended period of time. - The boreal landscape is effective in retaining diffuse atmospheric deposition of dioxins and PCBs, slowly releasing these pollutants into nearby streams.
20. Long-term mercury dynamics in UK soils
Energy Technology Data Exchange (ETDEWEB)
Tipping, E., E-mail: et@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Wadsworth, R.A. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Norris, D.A.; Hall, J.R. [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Ilyin, I. [Meteorological Synthesizing Centre - East, Krasina pereulok, 16/1, 123056 Moscow (Russian Federation)
2011-12-15
A model assuming first-order losses by evasion and leaching was used to evaluate Hg dynamics in UK soils since 1850. Temporal deposition patterns of Hg were constructed from literature information. Inverse modelling indicated that 30% of 898 rural sites receive Hg only from the global circulation, while in 51% of cases local deposition exceeds global. Average estimated deposition is 16 {mu}g Hg m{sup -2} a{sup -1} to rural soils, 19 {mu}g Hg m{sup -2} a{sup -1} to rural and non-rural soils combined. UK soils currently hold 2490 tonnes of reactive Hg, of which 2140 tonnes are due to anthropogenic deposition, mostly local in origin. Topsoil currently releases 5.1 tonnes of Hg{sup 0} per annum to the atmosphere, about 50% more than the anthropogenic flux. Sorptive retention of Hg in the lower soil exerts a strong control on surface water Hg concentrations. Following decreases in inputs, soil Hg concentrations are predicted to decline over hundreds of years. - Highlights: > Spatial data for mercury in UK soils can be related to past atmospheric deposition. > The residence time of Hg (c. 400 years) depends on gaseous evasion and leaching. > UK soils currently contribute more Hg{sup 0} to the atmosphere than human activities. > Sorption of Hg by deeper soil is a strong control on surface water concentrations. - Atmospherically-deposited anthropogenic mercury, mostly of local origin, has accumulated in UK soils, and is now a significant source of Hg{sup 0} to the global circulation.
1. Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network
Directory of Open Access Journals (Sweden)
F. Sprovieri
2016-09-01
Full Text Available Long-term monitoring of data of ambient mercury (Hg on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS project was funded by the European Commission (http://www.gmos.eu and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010–2015, analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.
2. Atmospheric deposition of long-lived Beta radionuclides over the territory of Bulgaria during the last decades
Energy Technology Data Exchange (ETDEWEB)
Veleva, B. [National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Sofia (Bulgaria)
2013-07-01
The sources of atmospheric radioactivity are discussed and compared. Radon isotopes and their daughters' dominate the natural background of beta activity in the surface air. The man-made radionuclides, much of them beta emitters, started to contaminate regionally and globally the environment after 1940's due to the atmospheric nuclear bomb tests. Additional significant sources of technogenic radionuclides in the atmosphere were nuclear accidents with pronounced examples of Chernobyl and Fukushima. The Bulgarian network for atmospheric radioactivity monitoring has been developing since 1959 in the frame of the state Hydro-meteorological service, now National Institute of Meteorology and Hydrology. It includes daily measurements of aerosol beta activity and deposition immediately and 120h after the sampling. The time and space variations of deposited beta activity, based on long term data records are presented and impact assessment of the different sources is given. The role of precipitation in deposition of radionuclides is evaluated. (author)
3. Heavy metals in atmospheric surrogate dry deposition
Science.gov (United States)
Morselli; Cecchini; Grandi; Iannuccilli; Barilli; Olivieri
1999-02-01
This paper describes a methodological approach for the assessment of the amount of surrogate dry deposition of several toxic heavy metals (Cd, Cr, Cu, Ni, Pb, V, Zn) associated with atmospheric particulate matter at ground level. The objectives of the study were twofold: i) the evaluation of several techniques for the digestion of dry deposition samples for trace metal analysis; ii) the comparison of the results from two samplers with different collecting surfaces. A dry solid surface sampler (DRY sampler, Andersen--USA) and a water layer surface sampler (DAS sampler--MTX Italy) were employed. The samples were collected over a one-year period in an urban site of Bologna (northern Italy). A description is given of the complete procedure, from sampling to data elaboration, including sample storage, digestion and analytical methods. According to the results obtained with three different digestion techniques (Teflon bomb, microwave digester and Teflon flask with vapour cooling system), the highest recovery rate was achieved by the Teflon bomb procedure employing an NBS 1648 Standard Reference Material; 90-95% of the elements considered were recovered by dissolution in a pressurized Teflon bomb with an HNO3-HF mixture. Given these results, the technique was adopted for dry deposition sample digestion. On the basis of the amount of heavy metals measured as monthly deposition fluxes (microg/m2), the collecting efficiency of the DAS sampler for a number of elements was found to be as much as two to three times greater than that of the DRY sampler.
4. Spatial variation in atmospheric nitrogen deposition on low canopy vegetation
International Nuclear Information System (INIS)
Verhagen, Rene; Diggelen, Rudy van
2006-01-01
Current knowledge about the spatial variation of atmospheric nitrogen deposition on a local scale is limited, especially for vegetation with a low canopy. We measured nitrogen deposition on artificial vegetation at variable distances of local nitrogen emitting sources in three nature reserves in the Netherlands, differing in the intensity of agricultural practices in the surroundings. In the nature reserve located in the most intensive agricultural region nitrogen deposition decreased with increasing distance to the local farms, until at a distance of 1500 m from the local nitrogen emitting sources the background level of 15 kg N ha -1 yr -1 was reached. No such trend was observed in the other two reserves. Interception was considerably lower than in woodlands and hence affected areas were larger. The results are discussed in relation to the prospects for the conservation or restoration of endangered vegetation types of nutrient-poor soil conditions. - Areas with low canopy vegetation are affected over much larger distances by nitrogen deposition than woodlands
5. Fission products in National Atmospheric Deposition Program—Wet deposition samples prior to and following the Fukushima Dai-Ichi Nuclear Power Plant incident, March 8?April 5, 2011
Science.gov (United States)
Wetherbee, Gregory A.; Debey, Timothy M.; Nilles, Mark A.; Lehmann, Christopher M.B.; Gay, David A.
2012-01-01
Radioactive isotopes I-131, Cs-134, or Cs-137, products of uranium fission, were measured at approximately 20 percent of 167 sampled National Atmospheric Deposition Program monitoring sites in North America (primarily in the contiguous United States and Alaska) after the Fukushima Dai-Ichi Nuclear Power Plant incident on March 12, 2011. Samples from the National Atmospheric Deposition Program were analyzed for the period of March 8-April 5, 2011. Calculated 1- or 2-week radionuclide deposition fluxes at 35 sites from Alaska to Vermont ranged from 0.47 to 5,100 Becquerels per square meter during the sampling period of March 15-April 5, 2011. No fission-product isotopes were measured in National Atmospheric Deposition Program samples obtained during March 8-15, 2011, prior to the arrival of contaminated air in North America.
6. The Effects of Atmospheric Nitrogen Deposition on Terrestrial and Freshwater Biodiversity
NARCIS (Netherlands)
Baron, J.S.; Barber, M.; Adams, M.; Dobben, van H.F.
2014-01-01
This chapter reports the findings of a Working Group on how atmospheric nitrogen (N) deposition affects both terrestrial and freshwater biodiversity. Regional and global scale impacts on biodiversity are addressed, together with potential indicators. Key conclusions are that: the rates of loss in
7. Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution.
Science.gov (United States)
Osterwalder, Stefan; Bishop, Kevin; Alewell, Christine; Fritsche, Johannes; Laudon, Hjalmar; Åkerblom, Staffan; Nilsson, Mats B
2017-11-22
Peatlands are a major source of methylmercury that contaminates downstream aquatic food webs. The large store of mercury (Hg) in peatlands could be a source of Hg for over a century even if deposition is dramatically reduced. However, the reliability of Hg mass balances can be questioned due to missing long-term land-atmosphere flux measurements. We used a novel micrometeorological system for continuous measurement of Hg peatland-atmosphere exchange to derive the first annual Hg budget for a peatland. The evasion of Hg (9.4 µg m -2 yr -1 ) over the course of a year was seven times greater than stream Hg export, and over two times greater than wet bulk deposition to the boreal peatland. Measurements of dissolved gaseous Hg in the peat pore water also indicate Hg evasion. The net efflux may result from recent declines in atmospheric Hg concentrations that have turned the peatland from a net sink into a source of atmospheric Hg. This net Hg loss suggests that open boreal peatlands and downstream ecosystems can recover more rapidly from past atmospheric Hg deposition than previously assumed. This has important implications for future levels of methylmercury in boreal freshwater fish and the estimation of historical Hg accumulation rates from peat profiles.
8. Atmospheric Deposition of Pb, Zn, Cu, and Cd in Amman, Jordan
International Nuclear Information System (INIS)
Momani, K.A.; Jiries, A.G.; Jaradat, Q.M.
1999-01-01
Atmospheric samples were collected by high-volume air sampler and dust fall containers during the summer of 1995 at different sites in Amman City, Jordan. Heavy metal contents in settle able (dust fall) as well as in air particulates (suspended) were analyzed by graphite furnace atomic absorption spectrophotometry. The atmospheric concentrations of Zn, Cu, Pb, and Cd were 344, 170, 291, and 3.8 ng/m 3 , respectively. On the other hand, the levels of these elements in dust fall deposition were 505, 94, 74, and 3.1 μg/g, respectively. The fluxes and dry deposition velocities of these heavy metals were determined and compared with the findings of other investigators worldwide. Significant enrichment coefficients of heavy metals in dust fall were observed. The enrichment coefficients were 12.1, 6.1, 11.7, and 1.1 for Zn, Cu, Pb, and Cd, respectively
9. Atmospheric Nitrogen Deposition and the Properties of Soils in Forests of Vologda Region
Science.gov (United States)
Kudrevatykh, I. Yu.; Ivashchenko, K. V.; Ananyeva, N. D.; Ivanishcheva, E. A.
2018-02-01
Twenty plots (20 m2 each) were selected in coniferous and mixed forests of the industrial Vologda district and the Vytegra district without developed industries in Vologda region. In March, snow cores corresponding to the snow cover depth were taken on these plots. In August, soil samples from the 0- to 20-cm layer of litter-free soddy-podzolic soil (Albic Retisol (Ochric)) were taken on the same plots in August. The content of mineral nitrogen (Nmin), including its ammonium (NH+ 4) and nitrate (NO- 3) forms, was determined in the snow (meltwater) and soil. The contents of total organic carbon, total nitrogen, and elements (Al, Ca); pH; particle size distribution; and microbiological parameters―carbon of microbial biomass (Cmic) and microbial respiration (MR)―were determined in the soil. The ratio MR/Cmic = qCO2 (specific respiration of microbial biomass, or soil microbial metabolic quotient) was calculated. The content of Nmic in meltwater of two districts was 1.7 mg/L on the average (1.5 and 0.3 mg/L for the NH+ 4 and NO- 3 forms, respectively). The annual atmospheric deposition was 0.6-8.9 kg Nmin/ha, the value of which in the Vologda district was higher than in the Vytegra district by 40%. Reliable correlations were found between atmospheric NH+ 4 depositions and Cmic (-0.45), between NH+ 4 and qCO2 (0.56), between atmospheric NO- 3 depositions and the soil NO- 3 (-0.45), and between NO- 3 and qCO2 (-0.58). The content of atmospheric Nmin depositions correlated with the ratios C/N (-0.46) and Al/Ca (-0.52) in the soil. In forests with the high input of atmospheric nitrogen (>2.0 kg NH+ 4/(ha yr) and >6.4 kg Nmin/(ha yr)), a tendency of decreasing Cmic, C/N, and Al/Ca, as well as increasing qCO2, was revealed, which could be indicative of deterioration in the functioning of microbial community and the chemical properties of the soil.
10. Analysis of Atmospheric Nitrate Deposition in Lake Tahoe Using Multiple Oxygen Isotopes
Science.gov (United States)
McCabe, J. R.; Michalski, G. M.; Hernandez, L. P.; Thiemens, M. H.; Taylor, K.; Kendall, C.; Wankel, S. D.
2002-12-01
Lake Tahoe in the Sierra Nevada Mountain Range is world renown for its depth and water clarity bringing 2.2 million visitors per year resulting in annual revenue of \\1.6 billion from tourism. In past decades the lake has suffered from decreased water clarity (from 32 m plate depth to less than 20), which is believed to be largely the result of algae growth initiated by increased nutrient loading. Lake nutrients have also seen a shift from a nitrogen limited to a phosphorous limited system indicating a large increase in the flux of fixed nitrogen. Several sources of fixed nitrogen of have been suggested including surface runoff, septic tank seepage from ground water and deposition from the atmosphere. Bio-available nitrogen in the form of nitrate (NO_{3}$-) is a main component of this system. Recent studies have estimated that approximately 50% of the nitrogen input into the lake is of atmospheric origin (Allison et al. 2000). However, the impact and magnitude of atmospheric deposition is still one of the least understood aspects of the relationship between air and water quality in the Basin (TRPA Threshold Assessment 2002). The utility of stable isotopes as tracers of nitrate reservoirs has been shown in several studies (Bohlke et al. 1997, Kendall and McDonnell 1998, Durka et al. 1994). Stable nitrogen (δ15N) and oxygen (δ18O) isotopes have been implemented in a dual isotope approach to characterize the various nitrate sources to an ecosystem. While δ18O distinguishes between atmospheric and soil sources of nitrate, processes such as denitrification can enrich the residual nitrate in δ18O leaving a misleading atmospheric signature. The benefit of δ15N as a tracer for NO3- sources is the ability to differentiate natural soil, fertilizer, and animal or septic waste, which contain equivalent δ18O values. The recent implementation of multiple oxygen isotopes to measure Δ17O in nitrate has proven to be a more sensitive tracer of atmospheric deposition. The 11. Atmospheric deposition of selected chemicals and their effect on nonpoint-source pollution in the Twin Cities Metropolitan Area, Minnesota Science.gov (United States) Brown, R.G. 1984-01-01 Atmospheric deposition and subsequent runoff concentrations of total Kjeldahl nitrogen, dissolved nitrite-plus-nitrate nitrogen, total phosphorus, total sulfate (only for atmospheric deposition), total chloride, and total lead were studied from April 1 to October 31, 1980, in one rural and three urban watersheds in the Twin Cities Metropolitan Area, Minnesota. Seasonal patterns of wetfall and dryfall generally were similar for all constituents except chloride in both rural and urban watersheds. Similarity between constituents and between rural and urban watersheds suggested that regional air masses transported from the Gulf of Mexico by frontal storm movements influence seasonal patterns of atmospheric deposition in the metropolitan area. Local influences such as industrial, agricultural, and vehicular air pollutants were found to influence the magnitude or rate of atmospheric deposition rather than the seasonal pattern. Chloride was primarily influenced by northwest frontal storms laden with coastal chloride. Local influences such as dust from road deicing salt dust are thought to have caused an increase in atmospheric chloride during June. 12. Mercury sedimentation in lakes in western Whatcom County, Washington, USA and its relation to local industrial and municipal atmospheric sources Science.gov (United States) Paulson, A.J.; Norton, D. 2008-01-01 Concentrations of mercury (Hg) were measured in six dated cores from four lakes in western Whatcom County, Washington, USA, that were at various bearings from a chlor-alkali plant, two municipal waste incinerators and a municipal sewage sludge incinerator. The importance of atmospheric emissions of Hg from these local municipal and industrial sources was evaluating by comparing the temporal trends in sedimentation of the lake cores with the emission history of each Hg species and by examining the geographical distribution of Hg sedimentation in relation to the region's primary wind pattern. Local municipal and industrial sources of atmospheric Hg were not responsible for the majority of the Hg in the upper layer of sediments of Whatcom County lakes because of (1) the significant enrichment of Hg in lake sediments prior to emissions of local industrial and municipal sources in 1964, (2) smaller increases in Hg concentrations occurred after 1964, (3) the similarity of maximum enrichments found in Whatcom County lakes to those in rural lakes around the world, (4) the inconsistency of the temporal trends in Hg sedimentation with the local emission history, and (5) the inconsistency of the geographic trends in Hg sedimentation with estimated deposition. Maximum enrichment ratios of Hg in lake sediments between 2 and 3 that are similar to rural areas in Alaska, Minnesota, and New England suggest that global sources of Hg were primarily responsible for increases of Hg in Whatcom County lakes beginning about 1900. ?? 2007 GovernmentEmployee: U.S. Government, Department of Interior, U.S. Geological Survey. 13. An evaluation of dry deposition from the long range atmospheric dispersion International Nuclear Information System (INIS) Suh, K.S.; Kim, E.H.; Hwang, W.T.; Han, M.H.; Lee, H.S.; Lee, C.W. 2003-01-01 The dry deposition of pollutants released into the atmosphere must be evaluated to estimate the radiological dose of terrestrial plants and foodstuffs in the ecosystem. Especially, the atmospheric dispersion and dry deposition models have been widely developed to predict and minimize the radiological damage for the surrounding environment after the TMI-2 and the Chernobyl accidents. A Lagrangian particle model for the evaluation the long-range dispersion has been firstly developed in Korea since 2001. The particle tracking method was used for the estimation of the concentration distribution of the radioactive materials released into the atmosphere. The model is designed to estimate air concentration and ground deposition at distances up to some thousands of kilometers from the source point in the horizontal direction. The turbulent motion is considered to separate the treatment of particles within the mixing layer and above the mixing layer. Also, the dispersion model is designed to receive the results of the MM5 model being operated by KMA (Korea Meteorological Administration). The test run of the long-range dispersion model has been performed in the area which covered extends from 102.47deg E to 173.34deg E and from 12.27deg N to 53.72deg N in Northeast Asia. The release point of Cs-137 assumed in the east part of the China. The long range dispersion model has been firstly developed to estimate the radiological consequences against a nuclear accident. The model will be supplemented by the comparative study using the data of the ETEX experiments. (author) 14. Controls on mercury and methylmercury deposition for two watersheds in Acadia National Park, Maine. Science.gov (United States) Johnson, K B; Haines, T A; Kahl, J S; Norton, S A; Amirbahman, Aria; Sheehan, K D 2007-03-01 Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to 16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed (burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 microg/m(2)/year in Cadillac Brook watershed and 10.2 microg/m(2)/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 microg/m(2)/year in Cadillac Brook watershed and 0.10 microg/m(2)/year in Hadlock Brook watershed. 15. Ice Core Perspective on Mercury Pollution during the Past 600 Years. Science.gov (United States) Beal, Samuel A; Osterberg, Erich C; Zdanowicz, Christian M; Fisher, David A 2015-07-07 Past emissions of the toxic metal mercury (Hg) persist in the global environment, yet these emissions remain poorly constrained by existing data. Ice cores are high-resolution archives of atmospheric deposition that may provide crucial insight into past atmospheric Hg levels during recent and historical time. Here we present a record of total Hg (HgT) in an ice core from the pristine summit plateau (5340 m asl) of Mount Logan, Yukon, Canada, representing atmospheric deposition from AD 1410 to 1998. The Colonial Period (∼1603-1850) and North American "Gold Rush" (1850-1900) represent minor fractions (8% and 14%, respectively) of total anthropogenic Hg deposition in the record, with the majority (78%) occurring during the 20th Century. A period of maximum HgT fluxes from 1940 to 1975 coincides with estimates of enhanced anthropogenic Hg emissions from commercial sources, as well as with industrial emissions of other toxic metals. Rapid declines in HgT fluxes following peaks during the Gold Rush and the mid-20th Century indicate that atmospheric Hg deposition responds quickly to reductions in emissions. Increasing HgT fluxes from 1993 until the youngest samples in 1998 may reflect the resurgence of Hg emissions from unregulated coal burning and small-scale gold mining. 16. HgSe(Te)-HgHal2 systems International Nuclear Information System (INIS) Pan'ko, V.V.; Khudolij, V.A.; Voroshilov, Yu.V. 1989-01-01 Using the methods of differential thermal and X-ray phase analyses the character of chemical interaction in the systems HgTe(Se)-HgHal 2 , where Hal is Cl, Br, I, is investigated. Formation of compounds Hg 3 Se 2 Hal 2 , Hg 3 Te 2 Hal 2 , Hg 3 TeCl 4 and Hg 3 TeBr 4 in these systems is established. The phase diagrams of the studied systems are presented. The parameters of elementary cells of the compounds with the unknown structure, as well as their unknown physicochemical properties, are determined 17. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA Energy Technology Data Exchange (ETDEWEB) Geiser, Linda H., E-mail: lgeiser@fs.fed.u [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Jovan, Sarah E. [US Forest Service Forest Inventory and Analysis Program, Pacific Northwest Research Station, 620 SW Main St, Suite 400, Portland, OR 97205 (United States); Glavich, Doug A. [US Forest Service Pacific Northwest Region Air Resource Management Program, Siuslaw National Forest, PO Box 1148, Corvallis, OR 97339 (United States); Porter, Matthew K. [Laboratory for Atmospheric Research, Washington State University, Pullman, WA 99164 (United States) 2010-07-15 Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha{sup -1} y{sup -1} in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs. - Lichen-based critical loads for N deposition in western Oregon and Washington forests ranged from 3 to 9 kg ha{sup -1} y{sup -1}, increasing with mean annual precipitation. 18. Uncertainty analysis of atmospheric deposition simulation of radiocesium and radioiodine from Fukushima Daiichi Nuclear Power Plant Science.gov (United States) Morino, Yu; Ohara, Toshimasa; Yumimoto, Keiya 2014-05-01 Chemical transport models (CTM) played key roles in understanding the atmospheric behaviors and deposition patterns of radioactive materials emitted from the Fukushima Daiichi nuclear power plant (FDNPP) after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011. In this study, we assessed uncertainties of atmospheric simulation by comparing observed and simulated deposition of radiocesium (137Cs) and radioiodine (131I). Airborne monitoring survey data were used to assess the model performance of 137Cs deposition patterns. We found that simulation using emissions estimated with a regional-scale (~500 km) CTM better reproduced the observed 137Cs deposition pattern in eastern Japan than simulation using emissions estimated with local-scale (~50 km) or global-scale CTM. In addition, we estimated the emission amount of 137Cs from FDNPP by combining a CTM, a priori source term, and observed deposition data. This is the first use of airborne survey data of 137Cs deposition (more than 16,000 data points) as the observational constraints in inverse modeling. The model simulation driven by a posteriori source term achieved better agreements with 137Cs depositions measured by aircraft survey and at in-situ stations over eastern Japan. Wet deposition module was also evaluated. Simulation using a process-based wet deposition module reproduced the observations well, whereas simulation using scavenging coefficients showed large uncertainties associated with empirical parameters. The best-available simulation reproduced the observed 137Cs deposition rates in high-deposition areas (≥10 kBq m-2) within one order of magnitude. Recently, 131I deposition map was released and helped to evaluate model performance of 131I deposition patterns. Observed 131I/137Cs deposition ratio is higher in areas southwest of FDNPP than northwest of FDNPP, and this behavior was roughly reproduced by a CTM if we assume that released 131I is more in gas phase 19. Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition Science.gov (United States) Nelson, David M.; Tsunogai, Urumu; Ding, Dong; Ohyama, Takuya; Komatsu, Daisuke D.; Nakagawa, Fumiko; Noguchi, Izumi; Yamaguchi, Takashi 2018-05-01 Atmospheric nitrate deposition resulting from anthropogenic activities negatively affects human and environmental health. Identifying deposited nitrate that is produced locally vs. that originating from long-distance transport would help inform efforts to mitigate such impacts. However, distinguishing the relative transport distances of atmospheric nitrate in urban areas remains a major challenge since it may be produced locally and/or be transported from upwind regions. To address this uncertainty we assessed spatiotemporal variation in monthly weighted-average Δ17O and δ15N values of wet and dry nitrate deposition during one year at urban and rural sites along the western coast of the northern Japanese island of Hokkaido, downwind of the East Asian continent. Δ17O values of nitrate in wet deposition at the urban site mirrored those of wet and dry deposition at the rural site, ranging between ˜ +23 and +31 ‰ with higher values during winter and lower values in summer, which suggests the greater relative importance of oxidation of NO2 by O3 during winter and OH during summer. In contrast, Δ17O values of nitrate in dry deposition at the urban site were lower (+19 - +25 ‰) and displayed less distinct seasonal variation. Furthermore, the difference between δ15N values of nitrate in wet and dry nitrate deposition was, on average, 3 ‰ greater at the urban than rural site, and Δ17O and δ15N values were correlated for both forms of deposition at both sites with the exception of dry deposition at the urban site. These results suggest that, relative to nitrate in wet and dry deposition in rural environments and wet deposition in urban environments, nitrate in dry deposition in urban environments forms from relatively greater oxidation of NO by peroxy radicals and/or oxidation of NO2 by OH. Given greater concentrations of peroxy radicals and OH in cities, these results imply that dry nitrate deposition results from local NOx emissions more so than wet 20. Soil surface Hg emission flux in coalfield in Wuda, Inner Mongolia, China. Science.gov (United States) Li, Chunhui; Liang, Handong; Liang, Ming; Chen, Yang; Zhou, Yi 2018-03-30 Hg emission flux from various land covers, such as forests, wetlands, and urban areas, have been investigated. China has the largest area of coalfield in the world, but data of Hg flux of coalfields, especially, those with coal fires, are seriously limited. In this study, Hg fluxes of a coalfield were measured using the dynamic flux chamber (DFC) method, coupled with a Lumex multifunctional Hg analyzer RA-915+ (Lumex Ltd., Russia). The results show that the Hg flux in Wuda coalfield ranged from 4 to 318 ng m -2 h -1 , and the average value for different areas varied, e.g., coal-fire area 99 and 177 ng m -2 h -1 ; no coal-fire area 19 and 32 ng m -2 h -1 ; and backfilling area 53 ng m -2 h -1 . Hg continued to be emitted from an underground coal seam, even if there were no phenomena, such as vents, cracks, and smog, of coal fire on the soil surface. This phenomenon occurred in all area types, i.e., coal-fire area, no coal-fire area, and backfilling area, which is universal in Wuda coalfield. Considering that many coalfields in northern China are similar to Wuda coalfield, they may be large sources of atmospheric Hg. The correlations of Hg emission flux with influence factors, such as sunlight intensity, soil surface temperature, and atmospheric Hg content, were also investigated for Wuda coalfield. Graphical abstract ᅟ. 1. Effectiveness of Emission Controls to Reduce the Atmospheric Concentrations of Mercury. Science.gov (United States) Castro, Mark S; Sherwell, John 2015-12-15 Coal-fired power plants in the United States are required to reduce their emissions of mercury (Hg) into the atmosphere to lower the exposure of Hg to humans. The effectiveness of power-plant emission controls on the atmospheric concentrations of Hg in the United States is largely unknown because there are few long-term high-quality atmospheric Hg data sets. Here, we present the atmospheric concentrations of Hg and sulfur dioxide (SO2) measured from 2006 to 2015 at a relatively pristine location in western Maryland that is several (>50 km) kilometers downwind of power plants in Ohio, Pennsylvania, and West Virginia. Annual average atmospheric concentrations of gaseous oxidized mercury (GOM), SO2, fine particulate mercury (PBM2.5), and gaseous elemental mercury (GEM) declined by 75%, 75%, 43%, and 13%, respectively, and were strongly correlated with power-plant Hg emissions from the upwind states. These results provide compelling evidence that reductions in Hg emissions from power plants in the United States had their intended impact to reduce regional Hg pollution. 2. Atmospheric deposition of nitrogen to the Baltic Sea in the period 1995–2006 Directory of Open Access Journals (Sweden) J. Bartnicki 2011-10-01 Full Text Available The EMEP/MSC-W model has been used to compute atmospheric nitrogen deposition into the Baltic Sea basin for the period of 12 yr: 1995–2006. The level of annual total nitrogen deposition into the Baltic Sea basin has changed from 230 Gg N in 1995 to 199 Gg N in 2006, decreasing 13 %. This value corresponds well with the total nitrogen emission reduction (11 % in the HELCOM Contracting Parties. However, inter-annual variability of nitrogen deposition to the Baltic Sea basin is relatively large, ranging from −13 % to +17 % of the averaged value. It is mainly caused by the changing meteorological conditions and especially precipitation in the considered period. The calculated monthly deposition pattern is similar for most of the years showing maxima in the autumn months October and November. The source allocation budget for atmospheric nitrogen deposition to the Baltic Sea basin was calculated for each year of the period 1997–2006. The main emission sources contributing to total nitrogen deposition are: Germany 18–22 %, Poland 11–13 % and Denmark 8–11 %. There is also a significant contribution from distant sources like the United Kingdom 6–9 %, as well as from the international ship traffic on the Baltic Sea 4–5 %. 3. Atmospheric transport and deposition of pesticides: An assessment of current knowledge DEFF Research Database (Denmark) Pul, W.A.J. van; Bidleman, T.F.; Brorström-Lunden, E. 1999-01-01 The current knowledge on atmospheric transport and deposition of pesticides is reviewed and discussed by a working group of experts during the Workshop on Fate of pesticides in the atmosphere; implications for risk assessment, held in Driebergen, the Netherlands, 22-24 April, 1998. In general...... in the exchange processes at the interface between air and soil/water/vegetation. In all process descriptions the uncertainty in the physicochemical properties play an important role. Particularly those in the vapour pressure, Henry's law constant and its temperature dependency. More accurate data... 4. Rapid atmospheric transport and large-scale deposition of recently synthesized plant waxes Science.gov (United States) Nelson, Daniel B.; Ladd, S. Nemiah; Schubert, Carsten J.; Kahmen, Ansgar 2018-02-01 Sedimentary plant wax 2H/1H ratios are important tools for understanding hydroclimate and environmental changes, but large spatial and temporal uncertainties exist about transport mechanisms from ecosystem to sediments. To assess atmospheric pathways, we collected aerosol samples for two years at four locations within a ∼60 km radius in northern Switzerland. We measured n-alkane distributions and 2H/1H ratios in these samples, and from local plants, leaf litter, and soil, as well as surface sediment from six nearby lakes. Increased concentrations and 2H depletion of long odd chain n-alkanes in early summer aerosols indicate that most wax aerosol production occurred shortly after leaf unfolding, when plants synthesize waxes in large quantities. During autumn and winter, aerosols were characterized by degraded n-alkanes lacking chain length preferences diagnostic of recent biosynthesis, and 2H/1H values that were in some cases more than 100‰ higher than growing season values. Despite these seasonal shifts, modeled deposition-weighted average 2H/1H values of long odd chain n-alkanes primarily reflected summer values. This was corroborated by n-alkane 2H/1H values in lake sediments, which were similar to deposition-weighted aerosol values at five of six sites. Atmospheric deposition rates for plant n-alkanes on land were ∼20% of accumulation rates in lakes, suggesting a role for direct deposition to lakes or coastal oceans near similar production sources, and likely a larger role for deposition on land and transport in river systems. This mechanism allows mobilization and transport of large quantities of recently produced waxes as fine-grained material to low energy sedimentation sites over short timescales, even in areas with limited topography. Widespread atmospheric transfer well before leaf senescence also highlights the importance of the isotopic composition of early season source water used to synthesize waxes for the geologic record. 5. Critical Loads of Atmospheric Nitrogen Deposition for Aquatic Ecosystems in Yosemite and Sequoia and Kings Canyon National Parks Science.gov (United States) Nanus, L.; Clow, D. W.; Sickman, J. O. 2016-12-01 High-elevation aquatic ecosystems in Yosemite (YOSE) and Sequoia and Kings Canyon (SEKI) National Parks are impacted by atmospheric nitrogen (N) deposition associated with local and regional air pollution. Documented effects include elevated surface water nitrate concentrations, increased algal productivity, and changes in diatom species assemblages. Annual wet inorganic N deposition maps, developed at 1-km resolution for YOSE and SEKI to quantify N deposition to sensitive high-elevation ecosystems, range from 1.0 to over 5.0 kg N ha-1 yr-1. Critical loads of N deposition for nutrient enrichment of aquatic ecosystems were quantified and mapped using a geostatistical approach, with N deposition, topography, vegetation, geology, and climate as potential explanatory variables. Multiple predictive models were created using various combinations of explanatory variables; this approach allowed us to better quantify uncertainty and more accurately identify the areas most sensitive to atmospherically deposited N. The lowest critical loads estimates and highest exceedances identified within YOSE and SEKI occurred in high-elevation basins with steep slopes, sparse vegetation, and areas of neoglacial till and talus. These results are consistent with previous analyses in the Rocky Mountains, and highlight the sensitivity of alpine ecosystems to atmospheric N deposition. 6. Long-Term Simulated Atmospheric Nitrogen Deposition Alters Leaf and Fine Root Decomposition Science.gov (United States) Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we p... 7. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China International Nuclear Information System (INIS) Cao Zongze; Yang Yuhua; Lu, Julia; Zhang Chengxiao 2011-01-01 Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m -2 yr -1 . The average deposition rate (76.7 g m -2 yr -1 ) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), ∼10% of the settled dusts having size 70% having size <30 μm; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: → High atmospheric dust deposition rate in Xi'an, Shaanxi, China. → Coal-burning power plan being a major source of particulate matter in Xi'an area. → High levels of toxic elements in the settled dusts. → Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China. 8. The atmospheric chemical vapour deposition of coatings on glass International Nuclear Information System (INIS) Sanderson, Kevin David 1996-01-01 The deposition of thin films of indium oxide, tin doped indium oxide (ITO) and titanium nitride for solar control applications have been investigated by Atmospheric Chemical Vapour Deposition (APCVD). Experimental details of the deposition system and the techniques used to characterise the films are presented. Results from investigations into the deposition parameters, the film microstructure and film material properties are discussed. A range of precursors were investigated for the deposition of indium oxide. The effect of pro-mixing the vaporised precursor with an oxidant source and the deposition temperature has been studied. Polycrystalline In 2 O 3 films with a resistivity of 1.1 - 3x10 -3 Ω cm were obtained with ln(thd) 3 , oxygen and nitrogen. The growth of ITO films from ln(thd) 3 , oxygen and a range of tin dopants is also presented. The effect of the dopant precursor, the doping concentration, deposition temperature and the effect of additives on film growth and microstructure is discussed. Control over the preferred orientation growth of ITO has been achieved by the addition of acetate species during film growth. Insitu infra-red spectroscopy has been used to identify the gas phase species and identify the species responsible for the film modification. ITO films with a resistivities of 1.5 - 4x10 -4 Ω cm have been achieved. The deposition of titanium nitride by the APCVD of Ti(NMe 2 ) 4 and a mixture of Ti(NMe 2 ) 4 and ammonia is reported. Contamination of the films and pro-reaction between the precursors in the gas phase is discussed, and the synthesis of new precursors for the deposition of titanium nitride is reported. New precursors have been synthesised under anaerobic conditions and characterised by infra-red spectroscopy, 1 H and 13 C NMR, mass spectrometry, thermal gravemetric analysis and three by single crystal X-ray diffraction. Deposition of titanium nitride utilising two new precursors is reported. (author) 9. Dry deposition of submicron atmospheric aerosol over water surfaces in motion International Nuclear Information System (INIS) Nevenick, Calec 2013-01-01 Whether by chronic or accidental releases, the impact of a nuclear installation on the environment mainly depends on atmospheric transfers; and as the accidents at Chernobyl and Fukushima show, affect the contamination of surfaces and impacts in the medium and long-term on the environment and the population. In this context, this work focuses on the characterization and modeling of dry deposition of submicron aerosols on liquid surfaces in motion such as rivers. Unlike wet deposition which is conditioned by washout and rainout (rain and clouds), dry deposition is a phenomenon that depends entirely on the characteristics of aerosols, receiving surfaces, and air flow. In practice, the evaluation of dry deposition is based on the estimation of flux modeling as the product of particle concentration and deposition velocity which can vary over several orders of magnitude depending on the receiving surfaces (forest, snow, urban, grassland...). This topic is motivated by the virtual non-existence of studies on the mechanisms of dry deposition on continental water systems such as rivers; and respect for submicron aerosols. They have the lowest deposition efficiencies and filtration and the longer residence time in the atmosphere. In addition, they are potentially the most dangerous to living beings because they can penetrate deeper into the airway. Due to the lack of data on the dry deposition of submicron aerosols on a liquid surface in motion, the approach was based on two axes: 1) the acquisition of experimental deposition velocities and 2) the analysis and interpretation of results through modeling. The experiments were performed with uranine aerosols released into the IOA wind tunnel (Interface Ocean Atmosphere) of the Institute for Research on Non Equilibrium Phenomena which is configured to study the coupling between the air flow and water. These experiments have given many dry deposition velocities for different configurations characterized according to wind 10. Dry deposition of submicron atmospheric aerosol over water surfaces in motion International Nuclear Information System (INIS) Calec, Nevenick 2013-01-01 Whether by chronic or accidental releases, the impact of a nuclear installation on the environment mainly depends on atmospheric transfers; and as the accidents at Chernobyl and Fukushima show, affect the contamination of surfaces and impacts in the medium and long-term on the environment and the population. In this context, this work focuses on the characterization and modeling of dry deposition of submicron aerosols on liquid surfaces in motion such as rivers. Unlike wet deposition which is conditioned by washout and rainout (rain and clouds), dry deposition is a phenomenon that depends entirely on the characteristics of aerosols, receiving surfaces, and air flow. In practice, the evaluation of dry deposition is based on the estimation of flux modeling as the product of particle concentration and deposition velocity which can vary over several orders of magnitude depending on the receiving surfaces (forest, snow, urban, grassland..). This topic is motivated by the virtual non-existence of studies on the mechanisms of dry deposition on continental water systems such as rivers; and respect for submicron aerosols. They have the lowest deposition efficiencies and filtration and the longer residence time in the atmosphere. In addition, they are potentially the most dangerous to living beings because they can penetrate deeper into the airway. Due to the lack of data on the dry deposition of submicron aerosols on a liquid surface in motion, the approach was based on two axes: 1) the acquisition of experimental deposition velocities and 2) the analysis and interpretation of results through modeling. The experiments were performed with uranine aerosols released into the IOA wind tunnel (Interface Ocean Atmosphere) of the Institute for Research on Non Equilibrium Phenomena which is configured to study the coupling between the air flow and water. These experiments have given many dry deposition velocities for different configurations characterized according to wind 11. Spectroscopic investigation of the Hg-Mn star κ Cnc. I. Choice of parameters of the model atmosphere and determination of the helium abundance International Nuclear Information System (INIS) Dobrichev, V.M.; Raikova, D.V.; Ryabchikova, T.A.; Topil'skaya, G.P. 1989-01-01 It is shown that a blanketed model atmosphere of the Hg-Mn star κ Cnc with T e = 12,800 degree K and log g = 3.7 (Stepien and Muthsam) completely describes the profiles of the lines H α , H γ , and H δ in the spectrum of this star. The synthetic-spectrum method is used to determine the helium abundance in the atmosphere of κ Cnc: He/H = 0.017, this value being almost three times greater than the value obtained earlier for this star by Adelman. The isotope shift of the lines leads to the isotope ratio 3 He/ 4 He = 0.35, and this indicates that there is a process of diffusion separation of the elements in the atmosphere of κ Cnc. 23 refs., 3 figs., 1 tab 12. Atmospheric deposition of organochlorine contaminants to Galveston Bay, Texas Science.gov (United States) Park, June-Soo; Wade, Terry L.; Sweet, Stephen Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB ( tPCB) concentrations in air ranged from 0.21 to 4.78 ng m -3 with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l -1, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4'-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m -2 yr -1) was significantly higher than that of pesticides by a factor of 5-10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m -2 yr -1). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux. 13. Deposition of aerosols formed by HCDA due to decay heat transport in inner containment atmospheres International Nuclear Information System (INIS) Vate, J.F. van de 1976-01-01 Coupling of decay heat transfer by aerosol-laden inner containment atmospheres with aerosol deposition from such atmospheres leads to useful and simple models for calculation of the time dependence of the aerosol mass concentration. Special attention is given to thermophoretic deposition (dry case) and condensation followed by gravitational deposition (wet case). Attractive features of the models are: 1) coagulation can be omitted and therefore complicated and doubtful calculations on coagulation are avoided, 2) material and particle size of the aerosol are not important for the aerosol decay rate, 3) the aerosol decay rate is related to the decay heat production which is known function of time, and the relevant part of it must be assessed usually for other purposes as well. (orig.) [de 14. Determination of Hg concentration in gases by PIXE Science.gov (United States) Dutkiewicz, E.; van Kuijen, W. J. P.; Munnik, F.; Mutsaers, P. H. A.; Rokita, E.; de Voigt, M. J. A. 1992-05-01 A method for determination of the concentration of mercury in the gaseous phase is described. In the first step of the method a stable sulphur-mercury complex is formed. For this purpose sulphur is deposited on a filter and the investigated gas flows through the filter. Millipore filters and the deposition of sulphur from Na2S2O3 * 5H2O solution were found to be most suitable. The amount of Hg absorbed on the filter was determined by PIXE or by NAA in the second step of the method. An optimization of proton energy was performed in the PIXE analysis to obtain the maximal signal-to-background ratio. The detection limit of the method, expressed as the minimal amount of Hg which has to flow through the filter equals to 30 and 2 ng for PIXE and NAA techniques, respectively. Applications of the method are also described. 15. New insight into atmospheric mercury emissions from zinc smelters using mass flow analysis. Science.gov (United States) Wu, Qingru; Wang, Shuxiao; Hui, Mulin; Wang, Fengyang; Zhang, Lei; Duan, Lei; Luo, Yao 2015-03-17 The mercury (Hg) flow paths from three zinc (Zn) smelters indicated that a large quantity of Hg, approximately 38.0-57.0% of the total Hg input, was stored as acid slag in the landfill sites. Approximately 15.0-27.1% of the Hg input was emitted into water or stored as open-dumped slags, and 3.3-14.5% of the Hg input ended in sulfuric acid. Atmospheric Hg emissions, accounting for 1.4-9.6% of the total Hg input, were from both the Zn production and waste disposal processes. Atmospheric Hg emissions from the waste disposal processes accounted for 40.6, 89.6, and 94.6% of the total atmospheric Hg emissions of the three studied smelters, respectively. The Zn production process mainly contributed to oxidized Hg (Hg2+) emissions, whereas the waste disposal process generated mostly elemental Hg (Hg0) emissions. When the emissions from these two processes are considered together, the emission proportion of the Hg2+ mass was 51, 46, and 29% in smelters A, B, and C, respectively. These results indicated that approximately 10.8±5.8 t of atmospheric Hg emissions from the waste disposal process were ignored in recent inventories. Therefore, the total atmospheric Hg emissions from the Zn industry of China should be approximately 50 t. 16. Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China. Science.gov (United States) Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui 2014-09-01 Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China. Copyright © 2014. Published by Elsevier B.V. 17. Active moss biomonitoring of trace elements with Sphagnum girgensohnii moss bags in relation to atmospheric bulk deposition in Belgrade, Serbia International Nuclear Information System (INIS) Anicic, M.; Tasic, M.; Frontasyeva, M.V.; Tomasevic, M.; Rajsic, S.; Mijic, Z.; Popovic, A. 2009-01-01 Active biomonitoring with wet and dry moss bags was used to examine trace element atmospheric deposition in the urban area of Belgrade. The element accumulation capability of Sphagnum girgensohnii Russow was tested in relation to atmospheric bulk deposition. Moss bags were mounted for five 3-month periods (July 2005-October 2006) at three representative urban sites. For the same period monthly bulk atmospheric deposition samples were collected. The concentrations of Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, and Pb were determined by instrumental neutron activation analyses and atomic absorption spectrometry. Significant accumulation of most elements occurred in the exposed moss bags compared with the initial moss content. High correlations between the elements in moss and bulk deposits were found for V, Cu, As, and Ni. The enrichment factors of the elements for both types of monitor followed the same pattern at the corresponding sites. - Accumulated trace elements in the moss Sphagnum girgensohnii reflect atmospheric deposition 18. Puff-plume atmospheric deposition model for use at SRP in emergency-response situations International Nuclear Information System (INIS) Garrett, A.J.; Murphy, C.E. Jr. 1981-05-01 An atmospheric transport and diffusion model developed for real-time calculation of the location and concentration of toxic or radioactive materials during an accidental release was improved by including deposition calculations 19. Atmospheric deposition as a source of carbon and nutrients to barren, alpine soils of the Colorado Rocky Mountains Science.gov (United States) Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K. 2012-03-01 Many alpine areas are experiencing intense deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, we evaluated the magnitude and chemical quality of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were approximately 1.0 mg L-1and weekly concentrations reached peaks as high at 6-10 mg L-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. Relationships among DOC concentration, dissolved organic matter (DOM) fluorescence properties, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples and, therefore, likely to be more bioavailable to microbes in barren alpine soils. Bioavailability experiments with different types of atmospheric C sources are needed to better evaluate the substrate quality of atmospheric C inputs. Our C budget estimates for the Green Lake 4 catchment suggest that atmospheric deposition represents an 20. Interlaboratory model comparisons of atmospheric concentrations with and without deposition International Nuclear Information System (INIS) Kern, C.D.; Cooper, R.E. 1978-01-01 To calculate the dose to the regional and U.S. populations, the pollutant concentration both with and without deposition and the amount of material deposited on the ground and watersheds around such a facility must be known. The following report (Article 50) of this document contains some initial estimates of population exposure from atmospheric effluents. The expertise of laboratories supported by U.S. Department of Energy funds ensures that the latest methods and data are available. Lawrence Livermore Laboratory (LLL) performed regional calculations (out to distances of the order of 200 km from a hypothetical fuel reprocessing plant). The Air Resources Laboratory (ARL) of the National Oceanic and Atmospheric Administration (NOAA), and Battelle Pacific Northwest Laboratories (PNL) performed U.S. scale calculations, and ARL also did the global calculations. Data from a winter and summer period were used to make comparisons of calculations by LLL, ARL, and PNL to determine which model should be used for the final calculations and to determine if a 200-km square area centered on the site would be large enough for dose calculations via the water and food pathways 1. Atmospheric deposition of methanol over the Atlantic Ocean Science.gov (United States) Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher 2013-01-01 In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air–sea methanol transfer along a ∼10,000-km north–south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air–sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface—an important term for improving air–sea gas exchange models. PMID:24277830 2. Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A. Science.gov (United States) Böhlke, J.K.; Ericksen, G.E.; Revesz, K. 1997-01-01 Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to determine if some proposed N sources could be supported or rejected, and to determine if the isotopic signature of these natural deposits could be used to distinguish them from various types of anthropogenic nitrate contamination that might be found in desert groundwaters. High-grade caliche-type nitrate deposits from both localities have ??15N values that range from -5 to +5???, but are mostly near 0???. Values of ??15N near 0??? are consistent with either bulk atmospheric N deposition or microbial N fixation as major sources of the N in the deposits. ??18O values of those desert nitrates with ??15N near 0??? range from about +31 to + 50??? (V-SMOW), significantly higher than that of atmospheric O2 (+ 23.5???). Such high values of ??18O are considered unlikely to result entirely from nitrification of reduced N, but rather resemble those of modern atmospheric nitrate in precipitation from some other localities. Assuming that limited modern atmospheric isotope data are applicable to the deposits, and allowing for nitrification of co-deposited ammonium, it is estimated that the fraction of the nitrate in the deposits that could be accounted for isotopically by atmospheric N deposition may be at least 20% and possibly as much as 100%. ??34S values are less diagnostic but could also be consistent with atmospheric components in some of the soluble sulfates associated with the deposits. The stable isotope data support the hypothesis that some high-grade caliche-type nitrate-rich salt deposits in some of the Earth's hyperarid deserts represent long-term accumulations of atmospheric deposition 3. Study of the odd mass transition nuclei: 185Hg, 187Hg, 189Hg and 183Ir International Nuclear Information System (INIS) Zerrouki, A. 1979-01-01 The radioactive decay of 185 Tl, 186 Tl, 187 Tl has been studied on the isotope separator Isocele II working on line with the Orsay synchrocyclotron from Au( 3 He,xn) reactions: the emitted α lines have been measured and the main γ lines belonging to the 187 Tl→ 187 Hg decay have been identified. The 185 Hg, 187 Hg, 189 Hg high spin states have been studied using the following (HI,xn) reactions obtained on the Strasbourg MP Tandem: 168 Er( 24 Mg,xn) 187 Hg, 188 Hg, 166 Er( 24 Mg,xn) 185 Hg, 186 Hg, 157 Gd( 32 S,xn) 184 Hg, 185 Hg, 158 Gd( 32 S,5n) 185 Hg and 175 Lu( 19 F,5n) 189 Hg. The excitation functions are indicated and a high spin level scheme of 189 Hg is proposed: it is compared to the 'quasiparticle + triaxial rotor' model predictions. A level scheme of 183 Ir is proposed from the data collected at Isolde II (CERN) by Dr. SCHUCK: it is analysed within the framework of the same theoretical model used above [fr 4. Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition Science.gov (United States) Thiagarajan, Nivedita; Aeolus Lee, Cin-Ty 2004-07-01 Smooth rock surfaces in arid environments are often covered with a thin coating of Fe-Mn oxyhydroxides known as desert varnish. It is debated whether such varnish is formed (a) by slow diagenesis of dust particles deposited on rock surfaces, (b) by leaching from the underlying rock substrate, or (c) by direct deposition of dissolved constituents in the atmosphere. Varnishes collected from smooth rock surfaces in the Mojave Desert and Death Valley, California are shown here to have highly enriched and fractionated trace-element abundances relative to upper continental crust (UCC). They are highly enriched in Co, Ni, Pb and the rare-earth elements (REEs). In particular, they have anomalously high Ce/La and low Y/Ho ratios. These features can only be explained by preferential scavenging of Co, Ni, Pb and the REEs by Fe-Mn oxyhydroxides in an aqueous environment. High field strength elements (HFSEs: Zr, Hf, Ta, Nb, Th), however, show only small enrichments despite the fact that these elements should also be strongly scavenged by Fe-Mn oxyhydroxides. This suggests that their lack of enrichment is a feature inherited from a solution initially poor in HFSEs. The first two scenarios for varnish formation can be ruled out as follows. The high enrichment factors of Fe, Mn and many trace elements cannot be generated by mass loss associated with post-depositional diagenesis of dust particles because such a process predicts only a small increase in concentration. In addition, the highly fractionated abundance patterns of particle reactive element pairs (e.g., Ce/La and Y/Ho) rules out leaching of the rock substrate. This is because if leaching were to occur, varnishes would grow from the inside to the outside, and thus any particle-reactive trace element leached from the substrate would be quantitatively sequestered in the Fe-Mn oxyhydroxide layers, prohibiting any significant elemental fractionations. One remaining possibility is that the Fe, Mn and trace metals in varnish are 5. Hg in snow cover and snowmelt waters in high-sulfide tailing regions (Ursk tailing dump site, Kemerovo region, Russia). Science.gov (United States) Gustaytis, M A; Myagkaya, I N; Chumbaev, A S 2018-07-01 Gold-bearing polymetallic Cu-Zn deposits of sulphur-pyrite ores were discovered in the Novo-Ursk region in the 1930s. The average content of mercury (Hg) was approximately 120 μg/g at the time. A comprehensive study of Hg distribution in waste of metal ore enrichment industry was carried out in the cold season on the tailing dump site and in adjacent areas. Mercury concentration in among snow particulate, dissolved and colloid fractions was determined. The maximal Hg content in particulate fraction from the waste tailing site ranged 230-573 μg/g. Such indices as the frequency of aerosol dust deposition events per units of time and area, enrichment factor and the total load allowed to establish that the territory of the tailing waste dump site had a snow cover highly contaminated with dust deposited at a rate of 247-480 mg/(m 2 ∙day). Adjacent areas could be considered as area with low Hg contamination rate with average deposition rate of 30 mg/(m 2 ∙day). The elemental composition of the aerosol dust depositions was determined as well, which allowed to reveal the extent of enrichment waste dispersion throughout adjacent areas. The amount of Hg entering environment with snowmelt water discharge was estimated. As a result of snowmelting, in 2014 the nearest to the dump site hydrographic network got Hg as 7.1 g with colloids and as 5880 g as particles. The results obtained allowed to assess the degree of Hg contamination of areas under the impact of metal enrichment industry. Copyright © 2018 Elsevier Ltd. All rights reserved. 6. The effects of atmospheric nitrogen deposition on terrestrial and freshwater biodiversity Science.gov (United States) Baron, Jill S.; Barber, Mary C.; Adams, Mark; Agboola, Julius I.; Allen, Edith B.; Bealey, William J.; Bobbink, Roland; Bobrovsky, Maxim V.; Bowman, William D.; Branquinho, Cristina; Bustamente, Mercedes M. C.; Clark, Christopher M.; Cocking, Edward C.; Cruz, Cristina; Davidson, Eric A.; Denmead, O. Tom; Dias, Teresa; Dise, Nancy B.; Feest, Alan; Galloway, James N.; Geiser, Linda H.; Gilliam, Frank S.; Harrison, Ian J.; Khanina, Larisa G.; Lu, Xiankai; Manrique, Esteban; Ochoa-Hueso, Raul; Ometto, Jean P. H. B.; Payne, Richard; Scheuschner, Thomas; Sheppard, Lucy J.; Simpson, Gavin L.; Singh, Y. V.; Stevens, Carly J.; Strachan, Ian; Sverdrup, Harald; Tokuchi, Naoko; van Dobben, Hans; Woodin, Sarah 2014-01-01 This chapter reports the findings of a Working Group on how atmospheric nitrogen (N) deposition affects both terrestrial and freshwater biodiversity. Regional and global scale impacts on biodiversity are addressed, together with potential indicators. Key conclusions are that: the rates of loss in biodiversity are greatest at the lowest and initial stages of N deposition increase; changes in species compositions are related to the relative amounts of N, carbon (C) and phosphorus (P) in the plant soil system; enhanced N inputs have implications for C cycling; N deposition is known to be having adverse effects on European and North American vegetation composition; very little is known about tropical ecosystem responses, while tropical ecosystems are major biodiversity hotspots and are increasingly recipients of very high N deposition rates; N deposition alters forest fungi and mycorrhyzal relations with plants; the rapid response of forest fungi and arthropods makes them good indicators of change; predictive tools (models) that address ecosystem scale processes are necessary to address complex drivers and responses, including the integration of N deposition, climate change and land use effects; criteria can be identified for projecting sensitivity of terrestrial and aquatic ecosystems to N deposition. Future research and policy-relevant recommendations are identified. 7. Use of mosses as biomonitors of atmospheric deposition of trace elements International Nuclear Information System (INIS) Steinnes, E. 2000-01-01 Some basic facts about the use of mosses as biomonitors of atmospheric trace element deposition are reviewed, and advantages and limitations of this approach are discussed, largely on the basis of experience from regular use of this technique in Norway over the last 20 years. Topics discussed include different versions of the moss technique, mechanisms and efficiencies of trace element uptake, conversion of concentrations in moss to bulk deposition rates, and contribution from sources other than air pollution to the elemental composition of different elements. Suggestions are presented for further work in order to extend the use of mosses as biomonitors. (author) 8. Distribution of atmospheric mercury in northern Southeast Asia and South China Sea during Dongsha Experiment Science.gov (United States) Sheu, Guey-Rong; Lin, Neng-Huei; Lee, Chung-Te; Wang, Jia-Lin; Chuang, Ming-Tung; Wang, Sheng-Hsiang; Chi, Kai Hsine; Ou-Yang, Chang-Feng 2013-10-01 Northern South China Sea (SCS) is adjacent to major atmospheric mercury (Hg) emission source regions; however, studies concerning regional atmospheric Hg distribution and cycling are very limited. Accordingly, measurements of atmospheric Hg were conducted in March and April during the 2010 Dongsha Experiment to study its spatial and temporal distribution. Atmospheric Hg was measured at Hengchun and Dongsha Island (Taiwan), Da Nang (Vietnam), Chiang Mai (Thailand) and over the northern SCS. Atmospheric Hg concentrations ranged between 1.54 and 6.83 ng m-3, mostly higher than the Northern Hemisphere background value. Regional wind fields and backward trajectories indicated that the atmospheric Hg concentrations over northern SCS should principally reflect the export of the East Asian Hg emissions by northeast monsoon. However, significantly elevated Hg concentrations were always observed at Da Nang, possibly due to the influence of local Hg emissions. Chiang Mai is located in the intense biomass burning region in northern Thailand. Therefore, atmospheric Hg concentrations at Chiang Mai reflected the influence of regional biomass burning Hg emissions. Two dust storms were encountered at Dongsha Island, one on March 16 and the other on March 21, with atmospheric Hg enhancements. Compared with the 2008 summer values, elevated Hg levels were observed at Dongsha Island in the spring of 2010. Summer air masses were mainly from the deep SCS, representing relatively clean marine air. On the other hand, air masses were from the north in spring, passing eastern China or Taiwan prior to reaching Dongsha Island. Results of this research thus demonstrated the transport of atmospheric Hg from the East Asian continent to northern SCS by regional monsoon activity in spring, but special events, such as biomass burning and dust storms, can also cause enhancements of ambient Hg levels. 9. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere International Nuclear Information System (INIS) Havskov Soerensen, J.; Baklanov, A.; Mahura, A.; Lauritzen, Bent; Mikkelsen, Torben 2008-07-01 Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au) 10. Chromium speciation in rainwater: temporal variability and atmospheric deposition Energy Technology Data Exchange (ETDEWEB) Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry 2002-12-15 Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs. 11. Impacts of atmospheric nitrogen deposition on vegetation and soils in Joshua Tree National Park Science.gov (United States) E.B. Allen; L. Rao; R.J. Steers; A. Bytnerowicz; M.E. Fenn 2009-01-01 The western Mojave Desert is downwind of nitrogen emissions from coastal and inland urban sources, especially automobiles. The objectives of this research were to measure reactive nitrogen (N) in the atmosphere and soils along a N-deposition gradient at Joshua Tree National Park and to examine its effects on invasive and native plant species. Atmospheric nitric acid (... 12. Indirect N2O emission due to atmospheric N deposition for the Netherlands International Nuclear Information System (INIS) Denier van der Gon, H.; Bleeker, A. 2005-10-01 Nitrous oxide (N2O) is a potent greenhouse gas produced in soils and aquatic systems. The UNFCCC requires participants to report 'indirect' N2O emissions, following from agricultural N losses to ground- and surface water and N deposition on (other) ecosystems due to agricultural sources. Indirect N2O emission due to atmospheric N deposition is presently not reported by the Netherlands. In this paper, we quantify the consequences of various tiers to estimate indirect N2O due to deposition for a country with a high agricultural N use and discuss the reliability and potential errors in the IPCC methodology. A literature review suggests that the current IPCC default emission factor for indirect N2O from N deposition is underestimated by a factor 2. Moreover, considering anthropogenic N emissions from agriculture only and not from e.g., traffic and industry, results in further underestimation of indirect N2O emissions. We calculated indirect N2O emissions due to Dutch anthropogenic N emissions to air by using official Dutch N emission data as input in an atmospheric transport and deposition model in combination with land use databases. Next, land use-specific emission factors were used to estimate the indirect N2O emission. This revealed that (1) for some countries, like the Netherlands, most agricultural N emitted will be deposited on agricultural soils, not on natural ecosystems and, (2) indirect N2O emissions are at least 20% higher because more specific emission factors can be applied that are higher than the IPCC default. The results suggest that indirect N2O emission due to deposition is underestimated in current N2O budgets 13. Modelling the impact of climate change and atmospheric N deposition on French forests biodiversity International Nuclear Information System (INIS) Rizzetto, Simon; Belyazid, Salim; Gégout, Jean-Claude; Nicolas, Manuel; Alard, Didier; Corcket, Emmanuel; Gaudio, Noémie; Sverdrup, Harald; Probst, Anne 2016-01-01 A dynamic coupled biogeochemical–ecological model was used to simulate the effects of nitrogen deposition and climate change on plant communities at three forest sites in France. The three sites had different forest covers (sessile oak, Norway spruce and silver fir), three nitrogen loads ranging from relatively low to high, different climatic regions and different soil types. Both the availability of vegetation time series and the environmental niches of the understory species allowed to evaluate the model for predicting the composition of the three plant communities. The calibration of the environmental niches was successful, with a model performance consistently reasonably high throughout the three sites. The model simulations of two climatic and two deposition scenarios showed that climate change may entirely compromise the eventual recovery from eutrophication of the simulated plant communities in response to the reductions in nitrogen deposition. The interplay between climate and deposition was strongly governed by site characteristics and histories in the long term, while forest management remained the main driver of change in the short term. - Highlights: • The effects of N atmospheric deposition and climate change on vegetation were simulated. • The model ForSAFE-Veg was calibrated and validated carefully for three forests in France. • Climate has a greater influence on vegetation than N deposition in conifer forests. • N-poor ecosystems are, however, more sensitive to N deposition than to climate change. - Compared to nitrogen atmospheric deposition, climate appears to be the main driver of change in forest plant biodiversity on a century scale, except in N-poor ecosystems. 14. Oxidation of elemental mercury in the atmosphere; Constraints imposed by global scale modelling Energy Technology Data Exchange (ETDEWEB) Bergan, Torbjoern; Rodhe, Henning [Stockholm Univ. (Sweden). Dept. of Meteorology 2000-05-01 Based on the global mercury model published by Bergan et al. (1999), we present here further results from simulations where the central theme has been to evaluate the role of ozone and the hydroxyl radical as possible gas phase oxidants for the oxidation of elemental mercury in the atmosphere. The magnitude of natural and man-made mercury emissions are taken from recent literature estimates and the flux from land areas is assumed to vary by season. We consider only two mercury reservoirs, elemental mercury, Hg{sup 0}, and the more soluble divalent form, Hgll. Wet and dry deposition of Hgll is explicitly treated. Applying monthly mean fields of ozone for the oxidation of gas phase Hg{sup 0} and using the reaction rate by Hall (1995) yields a global transformation of Hg{sup 0} to Hgll which is too slow to keep the simulated concentration of Hg{sup 0} near observed values. This shows that there are additional important removal processes for Hg{sup 0} or that the reaction rate proposed by Hall (1995) is too slow. A simulation in which the oxidation rate was artificially increased, so that the global turn-over time of Hg{sup 0} was one year and the simulated average concentration of Hg{sup 0} was realistic, produced latitudinal and seasonal variations in Hg{sup 0} that did not support the hypothesis that gas phase reaction with O{sub 3} is the major oxidation process for Hg{sup 0}. Recent studies indicate that OH may be an important gas phase oxidant for Hg{sup 0}. Using OH as the oxidant and applying the preliminary oxidation rate by Sommar et al. (1999) gave an unrealistically large removal of Hg{sup 0} from the atmosphere. From calculations using a slower reaction rate, corresponding to a turn-over time of Hg{sup 0} of one year, we calculated concentrations of both Hg{sup 0} in surface air and Hgll in precipitation which correspond, both in magnitude and temporal variation, to seasonal observations in Europe and North America. This result supports the suggestion that 15. [Heavy metals contents and Hg adsorption characteristics of mosses in virgin forest of Gongga Mountain]. Science.gov (United States) Liang, Peng; Yang, Yong-Kui; He, Lei; Wang, Ding-Yong 2008-06-01 Seven main moss species in the Hailuogou virgin forest of Gongga Mountain were sampled to determine their heavy metals (Hg, Cr, Cd, Ni, Pb, Cu, Mn, Zn and Fe) content, and two widely distributed species, Pleurozium schreberi (Brid.) Mitt. and Racomitrium laetum Besch., were selected to study their Hg adsorption characteristics. The results showed that the heavy metals contents in the mosses were lower than the background values in Europe and America, except that the Cd had a comparable value, which indicated that the atmosphere in study area was not polluted by heavy metals and good in quality. The Hg adsorption by P. schreberi and R. laetum was an initiative and rapid process, with the equilibrium reached in about two hours, and could be well fitted by Freundlich and Langmuir equations. Based on Langmuir equation, the maximum Hg adsorption capacities of P. schreberi and R. laetum were 15.24 and 8.19 mg x g(-1), respectively, suggesting that the two mosses had a good capacity of Hg adsorption, and could be used as the bio-monitors of atmospheric Hg pollution. 16. Forest vegetation as a sink for atmospheric particulates: Quantitative studies in rain and dry deposition International Nuclear Information System (INIS) Russel, I.J.; Choquette, C.E.; Fang, S.; Dundulis, W.P.; Pao, A.A.; Pszenny, A.A.P. 1981-01-01 Radionuclides in the atmosphere are associated with nonradioactive air particulates and hence serve to trace the fluxes of air particulates to various surfaces. Natural and artificial radioactivities found in the atmosphere have been measured in vegetation for 10 years to elucidate some of the mechanisms of acquirement by forest trees of atmospheric particulates. Whole tree analysis, in conjunction with soil assay, have served to establish the fraction of the flux of radionuclides retained by above-ground tissues of a forest stand. Interpretation is facilitated because most radionuclides in the atmosphere are superficially acquired. Typically 5--20% of the total open field flux is retained by the forest canopy in a moderately rainy climate (120 cm/year). Short-lived daughters of radon give a dry deposition velocity of particulates in the Aitken size range of 0.03--0.05 cm/s, thus permitting an estimate of transient removal by forest canopies by dry deposition of this size fraction 17. Stability studies of Hg implanted YBa$_{2}$Cu$_{3}$O$_{6+x}$CERN Document Server Araújo, J P; Wahl, U; Marques, J G; Alves, E; Amaral, V S; Lourenço, A A; Galindo, V; Von Papen, T; Senateur, J P; Weiss, F; Vantomme, A; Langouche, G; Melo, A A; Da Silva, M F A; Soares, J C; Sousa, J B 1999-01-01 High quality YBa$_{2}$Cu$_{3}$O$_{6+x}$(YBCO) superconducting thin films were implanted with the radioactive$^{197m}$Hg (T$_{1/2}$= 24 h) isotope to low fluences of 10$^{13}$atoms/cm$^{2}$and 60 keV energy. The lattice location and stability of the implanted Hg were studied combining the Perturbed Angular Correlation (PAC) and Emission Channeling (EC) techniques. We show that Hg can be introduced into the YBCO lattice by ion implantation into unique regular sites. The EC data show that Hg is located on a highly symmetric site on the YBCO lattice, while the PAC data suggests that Hg occupies the Cu(1) site. Annealing studies were performed under vacuum and O$_{2}\$ atmosphere and show that Hg starts to diffuse only above 653 K.
18. Forest canopy uptake of atmospheric nitrogen deposition at eastern U.S. conifer sites: Carbon storage implications?
Science.gov (United States)
Herman Sievering; Ivan Fernandez; John Lee; John Hom; Lindsey Rustad
2000-01-01
Dry deposition determinations, along with wet deposition and throughfall (TF) measurements, at a spruce fir forest in central Maine were used to estimate the effect of atmospherically deposited nitrogen (N) uptake on forest carbon storage. Using nitric acid and particulate N as well as TF ammonium and nitrate data, the growing season (May-October) net canopy uptake of...
19. Order-of-magnitude increase of Hg in Norwegian peat profiles since the outset of industrial activity in Europe
International Nuclear Information System (INIS)
Steinnes, Eiliv; Sjobakk, Torill Eidhammer
2005-01-01
Peat cores from six ombrotrophic bogs at different latitudes in Norway (58 deg N-69 deg N) were analysed for Hg by atomic fluorescence spectrometry. In all cases a smooth decrease of Hg with depth was observed down to 15-20 cm. At greater depths Hg showed a relatively constant level of the order of 10% of that in the peat surface layer. In the surface peat Hg concentrations exhibit moderate variation with latitude. The pre-industrial levels of Hg in the peat correspond to a net annual Hg accumulation of 0.3-0.9 μg m -2 . The Hg accumulation over the last 100 years is about 15 times higher on average than the pre-industrial level. The present work supports the view that a major part of the present atmospheric Hg in the Northern Hemisphere is of anthropogenic origin. It is speculated that the comparatively high Hg contemporary accumulation rates observed at the Andoya bog on 69 deg N may be related to the Arctic springtime depletion of Hg. - Results from analyses of ombrotrophic peat cores support the view that the present level of Hg 0 in the atmosphere is mainly of anthropogenic origin
20. UFOMOD - atmospheric dispersion and deposition
International Nuclear Information System (INIS)
Panitz, H.J.; Matzerath, C.; Paesler-Sauer, J.
1989-10-01
The report gives an introduction into the modelling of atmospheric dispersion and deposition which has been implemented in the new program system UFOMOD for assessing the consequences after nuclear accidents. According to the new structure of UFOMOD, different trajectory models with ranges of validity near to the site and at far distances are applied. Emphasis is laid on the description of the segmented plume model MUSEMET and its affilated submodels, being the removal of activity from the cloud by dry and wet deposition, and special effects like plume rise and the behaviour of plumes released into building wakes. In addition, the evaluation of γ-dose correction factors to take account of the finite extent of the radioactive plume in the near range (up to about 20 km) are described. Only brief introductions are given into the principles of the other models available: the puff model RIMPUFF, the long-range puff model MESOS, and the special straight-line Gaussian model ISOLA which are used if low-level long-duration releases are considered. To define starting times of weather sequences and the probabilities of occurrence of these sequences, it is convenient to perform stratified sampling. Therefore, the preprocessing program package METSAM has been developed to perform for generic ACAs a random sampling of weather sequences out off a population of classified weather conditions. The sampling procedure and a detailed input/output (I/O) description is presented and an additional appendix, respectively. A general overview on the I/O structure of MUSEMET as well as a brief user guide to run the KfK version of the MESOS code are also given in the appendix. (orig.) [de
1. Stability and diffusion of Hg implanted YBa2Cu3O6+x
International Nuclear Information System (INIS)
Araujo, J.P.; Correia, J.G.; Wahl, U.; Marques, J.G.; Alves, E.; Amaral, V.S.; Lourenco, A.A.; Galindo, V.; Papen, T. von; Senateur, J.P.; Weiss, F.; Vantomme, A.; Langouche, G.; Melo, A.A.; Silva, M.F. da; Soares, J.C.; Sousa, J.B.
1999-01-01
The radioactive isotope 197m Hg was implanted at 60 keV with low fluences (10 13 ions/cm 2 ) into YBa 2 Cu 3 O 6+x (YBCO) superconducting thin films at ISOLDE/CERN. We report on the Hg dynamics and stability inside the YBCO lattice as a function of annealing temperature up to 890 K in a vacuum or O 2 atmosphere. The perturbed angular correlation (PAC) technique was used for probing the Hg behavior at the atomic scale, while by monitoring the sample's activity in situ the Hg outdiffusion was studied. We found that Hg ions occupy unique lattice sites and that Hg should be bound to two apical oxygens. Hg diffusion occurs only for annealing temperatures above 653 K, in vacuum. The Hg migration energy was estimated to be E M =1.58±0.15 eV
2. Atmospheric mercury accumulation between 5900 and 800 calibrated years BP in the high arctic of Canada recorded by Peat Hummocks
DEFF Research Database (Denmark)
Givelet, N.; Roos-Barraclough, F.; Goodsite, Michael Evan
2004-01-01
In this paper, we present the first comprehensive long-term record of preanthropogenic rates of atmospheric mercury accumulation in dated peat deposits for the High Arctic of Canada. Geochemical studies of two peat hummocks from Bathurst Island, Nunavut reveal substantial inputs from soil dust...... (titanium), marine aerosols (bromine), and mineral-water interactions (uranium). Mercury, however, was supplied to these peat mounds exclusively by atmospheric deposition. Mercury concentration measurements and age dating of the peat profiles indicate rather constant natural "background" mercury flux of ca....... 1 microgram per square meter per year from 5900 to 800 calibrated years BP. These values are well within the range of the mercury fluxes reported from other Arctic locations, but also by peat cores from southern Canada that provide a record of atmospheric Hg accumulation extending back 8000 years...
3. Impact of acid atmosphere deposition on soils : field monitoring and aluminum chemistry
NARCIS (Netherlands)
Mulder, J.
1988-01-01
The effect of acid atmospheric deposition on concentrations and transfer of major solutes in acid, sandy soils was studied. Emphasis was given to mobilization and transport of potentially toxic aluminum. Data on solute concentrations and fluxes in meteoric water as well as soil solutions
4. Assessment of atmospheric deposition of heavy metals and other elements in Belgrade using the moss biomonitoring technique and neutron activation analysis.
Science.gov (United States)
Anicić, Mira; Frontasyeva, Marina V; Tomasević, Milica; Popović, Aleksandar
2007-06-01
This study aimed at assessing atmospheric deposition of heavy metals and other elements using the moss genera Brachythecium sp. (B. rutabulum and B. salebrosum) and Eurhynchium sp. (E. hians and E. striatum) collected in autumn 2004 in the urban area of Belgrade. The concentrations of 36 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Tb, Dy, Hf, Ta, W, Hg, Th, U) were determined in moss and local topsoil samples by instrumental neutron activation analysis. The concentration of elements in moss positively correlated to those obtained for topsoil. High enrichment factors for As, Zn, Mo, Br, Sb, Se, Hg and Cl, calculated to continental crust composition, gave an evidence for anthropogenic impact on urban area, mainly due to intensive vehicular traffic and fossil fuel combustion. The concentration of elements in moss, characteristic for fossil fuel combustion, obtained in this study were substantially lower than in the previous investigation (2000) conducted in the area of Belgrade. The level of concentrations for V, Cr, Ni, and As in moss from this study correlated to those measured for neighboring countries, and were several times higher than the base-level data from low polluted areas. The level of accumulated elements in both investigated moss genera were similar and all studied species could be combined for biomonitoring purposes in urban areas.
5. Assessment of atmospheric deposition of heavy metals and other elements in Belgrade using the moss biomonitoring technique and neutron activation analysis
International Nuclear Information System (INIS)
Anicic, M.; Tomasevic, M.; Frontas'eva, M.V.; Popovic, A.
2006-01-01
The study aimed at assessing atmospheric deposition of heavy metals and other elements using the moss genera Brachythecium sp. (B. rutabulum and B. salebrosum) and Eurhynchium sp. (E. hians and E. striatum) collected in autumn 2004 in the urban area of Belgrade. The concentrations of 36 elements (Na, Mg, Al, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Mo, Sb, I, Cs, Ba, La, Ce, Sm, Tb, Dy, Hf, Ta, W, Hg, Th, U) were determined in moss and local topsoil samples by instrumental neutron activation analysis. The concentration of elements in moss positively correlated to those obtained for topsoil. High enrichment factors for As, Zn, Mo, Br, Sb, Se, Hg, and Cl, calculated to continental crust composition, gave an evidence for anthropogenic impact on urban area, mainly due to intensive vehicular traffic and fossil fuel combustion. The concentrations of elements in moss, characteristic for fossil fuel combustion, obtained in this study, were substantially lower than in the previous investigation (2000) conducted in the area of Belgrade. The level of concentrations for V, Cr, Ni, and As in moss from this study correlated to those measured for neighboring countries, and were several times higher than the base-level data from low polluted areas. The level of accumulated elements in both investigated moss genera were similar and all studied species could be combined for biomonitoring purposes in urban areas
6. Hydrogenated amorphous silicon photoresists for HgCdTe patterning
Energy Technology Data Exchange (ETDEWEB)
Hollingsworth, R.E.; DeHart, C.; Wang, L.; Dinan, J.H.; Johnson, J.N.
1997-07-01
A process to use a hydrogenated amorphous silicon (a-Si:H) film as a dry photoresist mask for plasma etching of HgCdTe has been demonstrated. The a-Si:H films were deposited using standard plasma enhanced chemical vapor deposition with pure silane as the source gas. X-ray photoelectron spectra show that virtually no oxide grows on the surface of an a-Si:H film after 3 hours in air, indicating that it is hydrogen passivated. Ultraviolet light frees hydrogen from the surface and enhances the oxide growth rate. A pattern of 60 micron square pixels was transferred from a contact mask to the surface of an a-Si:H film by ultraviolet enhanced oxidation in air. For the conditions used, the oxide thickness was 0.5--1.0 nm. Hydrogen plasmas were used to develop this pattern by removing the unexposed regions of the film. A hydrogen plasma etch selectivity between oxide and a-Si:H of greater than 500:1 allows patterns as thick as 700 nm to be generated with this very thin oxide. These patterns were transferred into HgCdTe by etching in an electron cyclotron resonance plasma. An etch selectivity between a-Si:H and HgCdTe of greater than 4:1 was observed after etching 2,500 nm into the HgCdTe. All of the steps are compatible with processing in vacuum.
7. Atmospheric deposition of inorganic nitrogen in Spanish forests of Quercus ilex measured with ion-exchange resins and conventional collectors
Science.gov (United States)
Héctor García-Gomez; Sheila Izquieta-Rojano; Laura Aguillaume; Ignacio González-Fernández; Fernando Valiño; David Elustondo; Jesús M. Santamaría; Anna Àvila; Mark E. Fenn; Rocío Alonso
2016-01-01
Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and time-consuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work...
8. Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars
Science.gov (United States)
Burns, Roger G.
1992-01-01
During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.
9. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere
Energy Technology Data Exchange (ETDEWEB)
Havskov Soerensen, J.; Baklanov, A.; Mahura, A. (Danish Meteorological Institute, Copenhagen (Denmark)); Lauritzen, Bent; Mikkelsen, Torben (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))
2008-07-15
Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)
10. High 210Po atmospheric deposition flux in the subtropical coastal area of Japan
International Nuclear Information System (INIS)
Tateda, Yutaka; Iwao, Kenji
2008-01-01
Bulk atmospheric deposition fluxes of 210 Po and 210 Pb were measured at three coastal regions of Japan, the Pacific Ocean coastal area of the Japanese mainland (Odawa Bay), the Chinese continental side of Japanese coastal area (Tsuyazaki), and an isolated island near Okinawa (Akajima). Wet and dry fallout collectors were continuously deployed from September 1997 through August 1998 for periods of 3 to 31 days depending on the frequency of precipitation events. Annual 210 Pb deposition fluxes at Odawa Bay (35 o N 139 o E), Tsuyazaki (33 o N 130 o E) and Akajima (26 o N 127 o E) were 73.3 ± 8.0, 197 ± 35 and 78.5 ± 8.0 Bq m -2 y -1 , respectively. Higher 210 Pb deposition was observed at the Chinese continental side of Japanese coast than at the Pacific Ocean coastal site. The high 210 Pb atmospheric flux at the Chinese continental side coast was thought to be attributable to 222 Rn-rich air-mass transport from the Chinese continent during the winter monsoon. In contrast, the annual 210 Po deposition fluxes at the three study sites were 13.0 ± 2.3 (Odawa Bay), 21.9 ± 4.4 (Tsuyazaki) and 58.4 ± 7.7 (Akajima) Bq m -2 y -1 , respectively, indicating unusual high 210 Po deposition at Akajima during winter. Anomalous unsupported 210 Po input was observed during summer 1997, suggesting unknown source of 210 Po at this area
11. Historical deposition and fluxes of mercury in Narraguinnep Reservoir, southwestern Colorado, USA
International Nuclear Information System (INIS)
Gray, John E.; Fey, David L.; Holmes, Charles W.; Lasorsa, Brenda K.
2005-01-01
Narraguinnep Reservoir has been identified as containing fish with elevated Hg concentrations and has been posted with an advisory recommending against consumption of fish. There are presently no point sources of significant Hg contamination to this reservoir or its supply waters. To evaluate potential historical Hg sources and deposition of Hg to Narraguinnep Reservoir, the authors measured Hg concentrations in sediment cores collected from this reservoir. The cores were dated by the 137 Cs method and these dates were further refined by relating water supply basin hydrological records with core sedimentology. Rates of historical Hg flux were calculated (ng/cm 2 /a) based on the Hg concentrations in the cores, sediment bulk densities, and sedimentation rates. The flux of Hg found in Narraguinnep Reservoir increased by approximately a factor of 2 after about 1970. The 3 most likely sources of Hg to Narraguinnep Reservoir are surrounding bedrocks, upstream inactive Au-Ag mines, and several coal-fired electric power plants in the Four Corners region. Patterns of Hg flux do not support dominant Hg derivation from surrounding bedrocks or upstream mining sources. There are 14 coal-fired power plants within 320 km of Narraguinnep Reservoir that produce over 80 x 10 6 MWH of power and about 1640 kg-Hg/a are released through stack emissions, contributing significant Hg to the surrounding environment. Two of the largest power plants, located within 80 km of the reservoir, emit about 950 kg-Hg/a. Spatial and temporal patterns of Hg fluxes for sediment cores collected from Narraguinnep Reservoir suggest that the most likely source of Hg to this reservoir is from atmospheric emissions from the coal-fired electric power plants, the largest of which began operation in this region in the late-1960s and early 1970s
12. Does seasonal snowpacks enhance or decrease mercury contamination of high elevation ecosystems?
Science.gov (United States)
Pierce, A.; Fain, X.; Obrist, D.; Helmig, D.; Barth, C.; Jacques, H.; Chowanski, K.; Boyle, D.; William, M.
2009-12-01
Mercury (Hg) is an extremely toxic pollutant globally dispersed in the environment. Natural and anthropogenic sources emit Hg to the atmosphere, either as gaseous elemental mercury (GEM; Hg0) or as divalent mercury species. Due to the long lifetime of GEM mercury contamination is not limited to industrialized sites, but also a concern in remote areas such as high elevation mountain environments. During winter and spring 2009, we investigated the fate of atmospheric mercury deposited to mountain ecosystems in the Sierra Nevada (Sagehen station, California, USA) and the Rocky Mountains (Niwot Ridge station, Colorado, USA). At Sagehen, we monitored mercury in snow (surface snow sampling and snow pits), wet deposition, and stream water during the snow-dominated season. Comparison of Hg stream discharge to snow Hg wet deposition showed that only a small fraction of Hg wet deposition reached stream in the melt water. Furthermore, Hg concentration in soil transects (25 different locations) showed no correlations to wet deposition Hg loads due to pronounced altitudinal precipitation gradient suggesting that Hg deposited to the snowpack was not transferred to ecosystems. At Niwot Ridge, further characterization of the chemical transformation involving mercury species within snowpacks was achieved by 3-months of continuous monitoring of GEM and ozone concentrations in the snow air at eight depths from the soil-snow interface to the top of the up to 2 meter deep snowpack. Divalent mercury concentrations were monitored as well (surface snow sampling and snow pits). GEM levels in snow air exhibited strong diurnal pattern indicative of both oxidation and reduction processes. Low levels of divalent mercury concentrations in snow pack suggest that large fractions of Hg originally deposited as wet deposition was reemitted back to the atmosphere after reduction. Hence, these results suggest that the presence of a seasonal snowpack may decrease effective wet deposition of mercury and
13. Thermally stimulated currents in α-HgI2 polycrystalline films
International Nuclear Information System (INIS)
Shiu, Y.-T.; Huang, T.-J.; Shih, C.-T.; Su, C.-F.; Lan, S.-M.; Chiu, K.-C.
2007-01-01
A study of thermally stimulated currents (TSC) is applied to α-HgI 2 polycrystalline films grown by physical vapour deposition with various thermal boundary conditions. Five TSC peaks are clearly observed and numerically fitted. The activation energy and the density of the trapping centre that corresponds to each TSC peak are then calculated. Finally, the effects of the deposition conditions on the TSC results are discussed
14. A review of global environmental mercury processes in response to human and natural perturbations: Changes of emissions, climate, and land use.
Science.gov (United States)
Obrist, Daniel; Kirk, Jane L; Zhang, Lei; Sunderland, Elsie M; Jiskra, Martin; Selin, Noelle E
2018-03-01
We review recent progress in our understanding of the global cycling of mercury (Hg), including best estimates of Hg concentrations and pool sizes in major environmental compartments and exchange processes within and between these reservoirs. Recent advances include the availability of new global datasets covering areas of the world where environmental Hg data were previously lacking; integration of these data into global and regional models is continually improving estimates of global Hg cycling. New analytical techniques, such as Hg stable isotope characterization, provide novel constraints of sources and transformation processes. The major global Hg reservoirs that are, and continue to be, affected by anthropogenic activities include the atmosphere (4.4-5.3 Gt), terrestrial environments (particularly soils: 250-1000 Gg), and aquatic ecosystems (e.g., oceans: 270-450 Gg). Declines in anthropogenic Hg emissions between 1990 and 2010 have led to declines in atmospheric Hg 0 concentrations and Hg II wet deposition in Europe and the US (- 1.5 to - 2.2% per year). Smaller atmospheric Hg 0 declines (- 0.2% per year) have been reported in high northern latitudes, but not in the southern hemisphere, while increasing atmospheric Hg loads are still reported in East Asia. New observations and updated models now suggest high concentrations of oxidized Hg II in the tropical and subtropical free troposphere where deep convection can scavenge these Hg II reservoirs. As a result, up to 50% of total global wet Hg II deposition has been predicted to occur to tropical oceans. Ocean Hg 0 evasion is a large source of present-day atmospheric Hg (approximately 2900 Mg/year; range 1900-4200 Mg/year). Enhanced seawater Hg 0 levels suggest enhanced Hg 0 ocean evasion in the intertropical convergence zone, which may be linked to high Hg II deposition. Estimates of gaseous Hg 0 emissions to the atmosphere over land, long considered a critical Hg source, have been revised downward, and
15. Atmospheric particle characterization, distribution, and deposition in Xi'an, Shaanxi Province, Central China
Energy Technology Data Exchange (ETDEWEB)
Cao Zongze; Yang Yuhua [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Lu, Julia, E-mail: julialu@ryerson.c [Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada); Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China); Zhang Chengxiao, E-mail: cxzhang@snnu.edu.c [Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 (China)
2011-02-15
Physical characterization and chemical analysis of settled dusts collected in Xi'an from November 2007 to December 2008 show that (1) dust deposition rates ranged from 14.6 to 350.4 g m{sup -2} yr{sup -1}. The average deposition rate (76.7 g m{sup -2} yr{sup -1}) ranks the 11th out of 56 dust deposition rates observed throughout the world. The coal-burning power was the major particle source; (2) on average (except site 4), {approx}10% of the settled dusts having size <2.6, {approx}30% having size <10.5, and >70% having size <30 {mu}m; (3) the concentrations for 20 out of 27 elements analyzed were upto 18 times higher than their soil background values in China. With such high deposition rates of dusts that contain elevated levels of toxic elements, actions should be taken to reduce emission and studies are needed to assess the potential impacts of settled particles on surface ecosystem, water resource, and human health in the area. - Research highlights: High atmospheric dust deposition rate in Xi'an, Shaanxi, China. Coal-burning power plan being a major source of particulate matter in Xi'an area. High levels of toxic elements in the settled dusts. Enrichment of heavy metals (e.g., Pb, Ni, Cu) in fine particles. - Atmospheric dust deposition rate is high and the levels of toxic elements associated with the settled dusts are elevated in Xi'an, Shaanxi, China.
16. Evaluation of the pollution and human health risks posed by heavy metals in the atmospheric dust in Ebinur Basin in Northwest China.
Science.gov (United States)
Abuduwailil, Jilili; Zhaoyong, Zhang; Fengqing, Jiang
2015-09-01
Recently, a large amount of research assessing pollution levels and the related health risks posed by atmosphere dust has been undertaken worldwide. However, little work has been done in the oases of the arid regions of Northwest China. In this paper, we studied the pollution and health risks over a year of seven heavy metals in the atmospheric dust of Ebinur Basin, a typical oasis in Northwest China. The results showed the following: (1) The annual amount of atmospheric deposition in Ebinur Basin was 298.23 g m(-2) and the average monthly atmospheric deposition was 25.06 g m(-2). The average and maximum values of the seven heavy metals measured were all below the National Soil Environmental Quality Standards (2nd). (2) Heavy metals of Cu, Cr, and As in the atmospheric deposition mainly originated from the natural geological background, while Zn came from human activity. This study also showed that among the seven measured heavy metals, the ratios of the no-pollution status of Pb, Cd, and Hg were higher than those of others with moderate degrees of pollution also accounting for a certain ratio. (3) The carcinogenic risks from As, Cd, and Cr were all lower than the corresponding standard limit values, and these metals are considered not harmful to the health of the basin. However, there is a relatively high risk of exposure for children from hand-to-mouth intake, which is worthy of attention. This research showed that both human activity and natural factors, such as wind and altitude, influenced the heavy metal contents in the atmospheric dust of the study area. Furthermore, recent human activity in the study area had the most negative influence on the accumulation of the heavy metals and the corresponding health risks, especially for Hg, Pb, and Cd, which is worthy of attention.
17. Development of ion-exchange collectors for monitoring atmospheric deposition of inorganic pollutants in Alaska parklands
Science.gov (United States)
Brumbaugh, William G.; Arms, Jesse W.; Linder, Greg L.; Melton, Vanessa D.
2016-09-19
Between 2010 and 2014, the U.S. Geological Survey completed a series of laboratory and field experiments designed to develop methodology to support the National Park Service’s long-term atmospheric pollutant monitoring efforts in parklands of Arctic Alaska. The goals of this research were to develop passive sampling methods that could be used for long-term monitoring of inorganic pollutants in remote areas of arctic parklands and characterize relations between wet and dry deposition of atmospheric pollutants to that of concentrations accumulated by mosses, specifically the stair-step, splendid feather moss, Hylocomium splendens. Mosses and lichens have been used by National Park Service managers as atmospheric pollutant biomonitors since about 1990; however, additional research is needed to better characterize the dynamics of moss bioaccumulation for various classes of atmospheric pollutants. To meet these research goals, the U.S. Geological Survey investigated the use of passive ionexchange collectors (IECs) that were adapted from the design of Fenn and others (2004). Using a modified IEC configuration, mulitple experiments were completed that included the following: (a) preliminary laboratory and development testing of IECs, (b) pilot-scale validation field studies during 2012 with IECs at sites with instrumental monitoring stations, and (c) deployment of IECs in 2014 at sites in Alaska having known or suspected regional sources of atmospheric pollutants where samples of Hylocomium splendens moss also could be collected for comparison. The targeted substances primarily included ammonium, nitrate, and sulfate ions, and certain toxicologically important trace metals, including cadmium, cobalt, copper, nickel, lead, and zinc.Deposition of atmospheric pollutants is comparatively low throughout most of Alaska; consequently, modifications of the original IEC design were needed. The most notable modification was conversion from a single-stage mixed-bed column to a two
18. The electrochemical properties of LaNi5 electrodes doped with multi-walled carbon nanotubes synthesized by chemical vapor deposition and treated at different temperatures in a nitrogen atmosphere
International Nuclear Information System (INIS)
Yi Shuangping; Zhang Haiyan; Zhang Guoqin; Hu Shoule; Pei Lei; Yin Jianfen
2006-01-01
The electrochemical properties of LaNi 5 electrodes doped with multi-walled carbon nanotubes (MWNTs) treated at different temperatures in a nitrogen atmosphere were investigated. The MWNTs were synthesized by chemical vapor deposition (CVD). The purified carbon nanotubes (CNTs) were annealed during 1.5 h in a nitrogen atmosphere at different temperatures. A three-electrode system was applied. The CNTs-LaNi 5 electrodes were prepared by mixing CNTs and LaNi 5 in a weight ratio of 1:10, and used as the working electrode; Ni(OH) 2 /NiOOH worked as the counter electrode and Hg/HgO as the reference electrode. A 6 mol/L KOH solution acted as the electrolyte. MWNTs annealed at different temperatures in a nitrogen atmosphere showed large differences in the electrochemical hydrogen storage capability under the same testing condition. The CNTs-LaNi 5 electrodes with 20-40 nm diameter CNTs heated at 800 deg. C in nitrogen proved to have the best electrochemical hydrogen storage capacity, with a discharging capacity of 519.1 mAh/g and a corresponding discharging plateau voltage of 1.18 V, at a 200 mA/g charge current density and a 60 Ma/g discharge current density with a 0.2 V discharge voltage limit. From 500 to 800 deg. C, the higher the annealing temperature,the better the electrochemical hydrogen storage property. However, CNTs-LaNi 5 electrodes with 20-40 nm diameter CNTs heated at 900 deg. C in nitrogen have a lower capacity of 476.2 mAh/g under the same testing condition. This shows that the annealing temperature of CNTs is an important factor that influences their electrochemical hydrogen storage performance
19. Modeling the biogeochemical impact of atmospheric phosphate deposition from desert dust and combustion sources to the Mediterranean Sea
Science.gov (United States)
Richon, Camille; Dutay, Jean-Claude; Dulac, François; Wang, Rong; Balkanski, Yves
2018-04-01
Daily modeled fields of phosphate deposition to the Mediterranean from natural dust, anthropogenic combustion and wildfires were used to assess the effect of this external nutrient on marine biogeochemistry. The ocean model used is a high-resolution (1/12°) regional coupled dynamical-biogeochemical model of the Mediterranean Sea (NEMO-MED12/PISCES). The input fields of phosphorus are for 2005, which are the only available daily resolved deposition fields from the global atmospheric chemical transport model LMDz-INCA. Traditionally, dust has been suggested to be the main atmospheric source of phosphorus, but the LMDz-INCA model suggests that combustion is dominant over natural dust as an atmospheric source of phosphate (PO4, the bioavailable form of phosphorus in seawater) for the Mediterranean Sea. According to the atmospheric transport model, phosphate deposition from combustion (Pcomb) brings on average 40.5×10-6 mol PO4 m-2 yr-1 over the entire Mediterranean Sea for the year 2005 and is the primary source over the northern part (e.g., 101×10-6 mol PO4 m-2 yr-1 from combustion deposited in 2005 over the north Adriatic against 12.4×10-6 from dust). Lithogenic dust brings 17.2×10-6 mol PO4 m-2 yr-1 on average over the Mediterranean Sea in 2005 and is the primary source of atmospheric phosphate to the southern Mediterranean Basin in our simulations (e.g., 31.8×10-6 mol PO4 m-2 yr-1 from dust deposited in 2005 on average over the south Ionian basin against 12.4×10-6 from combustion). The evaluation of monthly averaged deposition flux variability of Pdust and Pcomb for the 1997-2012 period indicates that these conclusions may hold true for different years. We examine separately the two atmospheric phosphate sources and their respective flux variability and evaluate their impacts on marine surface biogeochemistry (phosphate concentration, chlorophyll a, primary production). The impacts of the different phosphate deposition sources on the biogeochemistry of the
20. Accounting for the effect of temperature in clarifying the response of foliar nitrogen isotope ratios to atmospheric nitrogen deposition.
Science.gov (United States)
Chen, Chongjuan; Li, Jiazhu; Wang, Guoan; Shi, Minrui
2017-12-31
Atmospheric nitrogen deposition affects nitrogen isotope composition (δ 15 N) in plants. However, both negative effect and positive effect have been reported. The effects of climate on plant δ 15 N have not been corrected for in previous studies, this has impeded discovery of a true effect of atmospheric N deposition on plant δ 15 N. To obtain a more reliable result, it is necessary to correct for the effects of climatic factors. Here, we measured δ 15 N and N contents of plants and soils in Baiwangshan and Mount Dongling, north China. Atmospheric N deposition in Baiwangshan was much higher than Mount Dongling. Generally, however, foliar N contents showed no difference between the two regions and foliar δ 15 N was significantly lower in Baiwangshan than Mount Dongling. The corrected foliar δ 15 N after accounting for a predicted value assumed to vary with temperature was obviously more negative in Baiwangshan than Mount Dongling. Thus, this suggested the necessity of temperature correction in revealing the effect of N deposition on foliar δ 15 N. Temperature, soil N sources and mycorrhizal fungi could not explain the difference in foliar δ 15 N between the two regions, this indicated that atmospheric N deposition had a negative effect on plant δ 15 N. Additionally, this study also showed that the corrected foliar δ 15 N of bulk data set increased with altitude above 1300m in Mount Dongling, this provided an another evidence for the conclusion that atmospheric N deposition could cause 15 N-depletion in plants. Copyright © 2017 Elsevier B.V. All rights reserved.
1. Deposition and surface characterization of nanoparticles of zinc oxide using dense plasma focus device in nitrogen atmosphere
International Nuclear Information System (INIS)
Malhotra, Yashi; Srivastava, M P; Roy, Savita
2010-01-01
Nanoparticles of zinc oxide from zinc oxide pellets in the nitrogen plasma atmosphere are deposited on n and p type silicon substrates using Dense Plasma Focus device. The hot and dense nitrogen plasma formed during the focus phase ionizes the ZnO pellet, which then move upward in a fountain like shape and gets deposited on substrates which are placed above the top of the anode. Structural and surface properties of the deposited ZnO are investigated using X-ray diffraction and Atomic force microscope (AFM). X-ray spectra shows the diffraction plane (002) of ZnO nanoparticles deposited on Si with few shots in nitrogen atmosphere. AFM investigations revealed that there are nanoparticles of size between 15-80 nm on n-Si and p-Si substrates. The deposition on n-type Si is better than the p-type Si can be seen from AFM images, this may be due to different orientation of silicon.
2. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe
International Nuclear Information System (INIS)
Harmens, H.; Norris, D.A.; Cooper, D.M.; Mills, G.; Steinnes, E.; Kubin, E.; Thoeni, L.; Aboal, J.R.; Alber, R.; Carballeira, A.; Coskun, M.; De Temmerman, L.; Frolova, M.; Gonzalez-Miqueo, L.
2011-01-01
In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses ( 2 = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: → Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. → Moss concentrations were compared with EMEP modelled nitrogen deposition. → The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha -1 y -1 . → Linear relationships were found with measured nitrogen deposition in some countries. → Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.
3. Atmospheric Deposition Modeling Results
Data.gov (United States)
U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...
4. Atmospheric deposition of trace elements around Ulan Bator city studied by moss and lichen biomonitoring technique and INAA
International Nuclear Information System (INIS)
Ganbold, G.; Gehrbish, Sh.; Tsehndehehkhuu, Ts.; Gundorina, S.F.; Frontas'eva, M.V.; Ostrovnaya, T.M.; Pavlov, S.S.
2005-01-01
For the first time the moss and lichen biomonitoring technique has been applied to air pollution in Mongolia (Ulan-Bator, the capital city). INAA at the IBR-2 reactor has made it possible to determine the content of 35 elements in moss and lichen biomonitors. Samples collected at sites located 10-15 km from the center of Ulan-Bator were analyzed by Instrumental Neutron Activation Analysis (INAA) using epithermal neutrons. The mosses (Rhytidium rugosum, Thuidium abietinum, Entodon concinnus) and lichens (Cladonia stellaris, Parmelia separata) were used to study the atmospheric deposition of trace elements. It was shown that the suggested types of mosses could be used as suitable biomonitors to estimate the concentration levels of heavy metals and trace elements in Ulan-Bator atmospheric deposition. The results are compared to the data of atmospheric deposition of some European countries
5. Atmospheric dispersion and deposition of 131I released from the Hanford Site
International Nuclear Information System (INIS)
Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.; Stage, S.A.
1996-01-01
Approximately 2.6 x 10 4 TBq (700,000 Ci) of 131 I were released to the air from reactor fuel processing plants on the Hanford Site in southcentral Washington State from December 1944 through December 1949. The Hanford Environmental Dose Reconstruction Project developed a suite of codes to estimate the doses that might have resulted from these releases. The Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET) computer code is part of this suite. The RATCHET code implements a Lagrangian-trajectory, Gaussian-puff dispersion model that uses hourly meterological and release rate data to estimate daily time-integrated air concentrations and surface contamination for use, in dose estimates. In this model, iodine is treated as a mixture of three species (inorganic gases, organic gases, and particles). Model deposition parameters are functions of the mixture and meterological conditions. A resistance model is used to calculate dry deposition velocities. Equilibrium between concentrations in the precipitation and the air near the ground is assumed in calculating wet deposition of gases, and irreversible washout of the particles is assumed. RATCHET explicitly treats the uncertainties in model parameters and meteorological conditions. Uncertainties in 131 I release rates and partitioning among the nominal species are treated by varying model input. The results of 100 model runs for December 1944 through December 1949 indicate that monthly average air concentrations and deposition have uncertainties ranging from a factor of two near the center of the time-integrated plume to more than an order of magnitude near the edge. These results indicate that ∼10% of the 131 I released to the atmosphere decayed during transit in the study area, ∼56% was deposited within the study area, and the remaining 34% was transported out of the study area while still in the air
6. Deposition and retention of air pollutants on vegetation and other atmospheric interfaces
International Nuclear Information System (INIS)
Jonas, R.
1984-09-01
The question of the deposition of aerosols and gases are applied to biological and ecological problems concerning the filtering aspect of atmospheric interfaces, especially vegetation, with respect to air pollution, and also the resulting pollutant effect. In order to determine the deposition of aerosols, numerous field experiments were carried out. The deposition of gases was treated on the basis of current literature data. The experiments indicate that the deposition of aerosols on grass largely depends on aerosol diameter, dry weight per unit area and the wind velocity or turbulence of the air layer near the ground. Of the interfaces studied, namely soil without vegetation, water, filter paper, smooth and structured metals, grass, clover and trees, the latter had the greatest dust collecting capability. It is recommended that in the afforestation of areas in the close proximity of industrial regions the common beech, silver birch and Japanese larch should be taken into particular consideration due to their great deposition effectiveness with respect to dusts and their comparatively high resistance to pollutant gases. Silver birch and moreover red horse chestnut should be considered for filtering the air in urban regions because of the high aerosol deposition. (orig./HP) [de
7. Mercury in the mix: An in situ mesocosm approach to assess relative contributions of mercury sources to methylmercury production and bioaccumulation in the Sacramento-San Joaquin Delta
Science.gov (United States)
Fleck, J.; Krabbenhoft, D. P.; Kraus, T. E. C.; Ackerman, J.; Stumpner, E. B.; DeWild, J.; Marvin-DiPasquale, M. C.; Tate, M.; Ogorek, J.
2014-12-01
Mercury (Hg) contamination is considered one of the greatest threats to the Sacramento-San Joaquin Delta and the San Francisco Estuary ecosystems. This threat is driven by the transformation of Hg, deposited in the Delta from erosion of upstream historic mining debris and atmospheric deposition, by native bacteria into the more toxic and biologically available form, methylmercury (MeHg), in the wetlands and sediment of the Delta. To effectively manage this threat, a quantitative understanding of the relative contribution of the different Hg sources to MeHg formation is needed. Mass balance estimates indicate as much as 99% of the Hg entering the Delta arrives via tributary inputs. Of the tributary Hg load, approximately 90% is adsorbed to suspended particles from tributary discharge and 10% is in the dissolved fraction, potentially of atmospheric origin. In comparison, the remaining 1-2% of the Hg entering the Delta arrives through direct atmospheric deposition (wet and dry). The relative importance of these sources to MeHg production within the Delta is not linearly related to the mass inputs because atmospherically-derived Hg is believed to be more reactive than sediment-bound Hg with respect to MeHg formation. We conducted an in situ mesocosm dosing experiment where different Hg sources to the Delta (direct atmospheric, dissolved riverine and suspended sediment) were "labeled" with different stable Hg isotopes and added to mesocosms within four different wetlands. Mercury isotopes added with the streambed sediments were equilibrated in sealed containers for six months; while the Hg isotopes associated with the precipitation and river water were equilibrated for 24 hours prior to use. After adding the isotopes, we sampled the water column, overlying air, bottom sediments and fish (Gambusia) at time intervals up to 30 days. Preliminary results from this experiment suggest that aqueous Hg sources (Hg introduced with precipitation and filtered river water) are 10
8. Atmospheric Deposition Effects on Plankton Communities in the Eastern Mediterranean: A Mesocosm Experimental Approach
Directory of Open Access Journals (Sweden)
Tatiana M. Tsagaraki
2017-07-01
Full Text Available The effects of atmospheric deposition on plankton community structure were examined during a mesocosm experiment using water from the Cretan Sea (Eastern Mediterranean, an area with a high frequency of atmospheric aerosol deposition events. The experiment was carried out under spring-summer conditions (May 2012. The main objective was to study the changes induced from a single deposition event, on the autotrophic and heterotrophic surface microbial populations, from viruses to zooplankton. To this end, the effects of Saharan dust addition were compared to the effects of mixed aerosol deposition on the plankton community over 9 days. The effects of the dust addition seemed to propagate throughout the food-web, with changes observed in nearly all of the measured parameters up to copepods. The dust input stimulated increased productivity, both bacterial and primary. Picoplankton, both autotrophic and heterotrophic capitalized on the changes in nutrient availability and microzooplankton abundance also increased due to increased availability of prey. Five days after the simulated deposition, copepods also responded, with an increase in egg production. The results suggest that nutrients were transported up the food web through autotrophs, which were favored by the Nitrogen supplied through both treatments. Although, the effects of individual events are generally short lived, increased deposition frequency and magnitude of events is expected in the area, due to predicted reduction in rainfall and increase in temperature, which can lead to more persistent changes in plankton community structure. Here we demonstrate how a single dust deposition event leads to enhancement of phytoplankton and microzooplankton and can eventually, through copepods, transport more nutrients up the food web in the Eastern Mediterranean Sea.
9. Annual atmospheric mercury species in downtown Toronto, Canada.
Science.gov (United States)
Song, Xinjie; Cheng, Irene; Lu, Julia
2009-03-01
Real-time concentrations of atmospheric gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and mercury associated with particles having sizes RGM were 4.5 +/- 3.1 ng m(-3) (99.2%), 21.5 +/- 16.4 pg m(-3) (0.5%) and 14.2 +/- 13.2 pg m(-3) (0.3%), respectively. The concentrations for all the measured Hg species were highly variable throughout the year and were lower in winter than in the other three seasons. The maximum concentrations of Hg species were observed in June and were a result of the high number of Hg spikes (using [GEM] >10 ng m(-3) as an indicator) that occurred in the month. Nighttime (between 9pm-6am) concentrations of Hg species were higher than those of daytime. The results revealed: (1) an urban area is a continuous source of Hg species that have the potential to pose impacts on local, regional and global scales; (2) local/regional anthropogenic sources contributed significantly to the levels and the distributions of the Hg species in the urban atmosphere. More studies are needed to identify and quantify the anthropogenic sources of Hg and the Hg species emitted from these sources; (3) surface emission and photochemical reactions (including the reactions involving ozone) did not have significant influence on the levels of Hg species and their distribution in the urban atmosphere.
10. A Heavy Metal Atmospheric Deposition Study in the South Ural Mountains
CERN Document Server
Frontasyeva, M V; Steinnes, E; Lyapunov, S M; Cherchintsev, V D
2002-01-01
Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Ural, one of the most heavily polluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Ta, W, Au, Th, U) in soil and 33 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) in mosses were determined by epithermal neutron activation analysis. The elem...
11. Decreased atmospheric sulfur deposition across the southeastern U.S.: When will watersheds release stored sulfate?
Science.gov (United States)
Rice, Karen C.; Scanlon, Todd M.; Lynch, Jason A.; Cosby, Bernard J.
2014-01-01
Emissions of sulfur dioxide (SO2) to the atmosphere lead to atmospheric deposition of sulfate (SO42-), which is the dominant strong acid anion causing acidification of surface waters and soils in the eastern United States (U.S.). Since passage of the Clean Air Act and its Amendments, atmospheric deposition of SO2 in this region has declined by over 80%, but few corresponding decreases in stream-water SO42- concentrations have been observed in unglaciated watersheds. We calculated SO42- mass balances for 27 forested, unglaciated watersheds from Pennsylvania to Georgia, by using total atmospheric deposition (wet plus dry) as input. Many of these watersheds still retain SO42-, unlike their counterparts in the northeastern U.S. and southern Canada. Our analysis showed that many of these watersheds should convert from retaining to releasing SO42- over the next two decades. The specific years when the watersheds crossover from retaining to releasing SO42- correspond to a general geographical pattern of later net watershed release from north to south. The single most important variable that explained the crossover year was the runoff ratio, defined as the ratio of annual mean stream discharge to precipitation. Percent clay content and mean soil depth were secondary factors in predicting crossover year. The conversion of watersheds from net SO42- retention to release anticipates more widespread reductions in stream-water SO42- concentrations in this region.
12. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA
International Nuclear Information System (INIS)
Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.
2013-01-01
Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7 Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7 Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7 Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L −1 , with a mean (±standard deviation) of 2.2 ± 0.9 Bq L −1 , and a volume-weighted average of 2.0 Bq L −1 . The range of wet atmospheric deposition was 18–188 Bq m −2 per rain event, with a mean of 72 ± 53 Bq m −2 . Dry deposition fluxes of 7 Be ranged from less than 0.01 up to 0.45 Bq m −2 d −1 , with an estimated dry season deposition of 7 Bq m −2 month −1 . Annualized 7 Be atmospheric deposition was approximately 1900 Bq m −2 yr −1 , with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7 Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g −1 , with a median activity of 0.26 Bq g −1 . A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7 Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7 Be data over the storm
13. Forest condition and chemical characteristics of atmospheric depositions: research and monitoring network in Lombardy
Directory of Open Access Journals (Sweden)
Flaminio DI GIROLAMO
2002-09-01
Full Text Available Since 1987, the Regional Forestry Board of Lombardy and the Water Research Institute of the National Research Council have been carrying out surveys of forest conditions and the response of the ecosystem to environmental factors. The study approach is based on a large number of permanent plots for extensive monitoring (Level 1. At this level, crown condition is assessed annually, and soil condition and the nutritional status of forests surveyed. Some of the permanent plots were selected for intensive monitoring (Level 2, focussing mainly on the impact of atmospheric pollution on forest ecosystems. Level 2 monitoring also includes increment analyses, ground vegetation assessment, atmospheric deposition, soil solution analyses and climatic observations. This paper summarises the main results of a pluriannual research, which provides a general picture of the state of forest health in the region and focuses on more detailed investigations, described as case studies. Modified wet and dry samplers which use a water surface to collect dry deposition were used in a pluriannual field campaign at five sites in alpine and prealpine areas, to measure the total atmospheric depositions and to evaluate the nitrogen and sulphate exceedances of critical loads. Throughfall and bulk precipitation chemistry were studied for five years (June 1994-May 1999 at two high elevation forest sites (Val Gerola and Val Masino which were known to differ in terms of tree health, as assessed by live crown condition. Results indicated a higher contribution from the dry deposition of N-NO3 -, N-NH4 + and H+ and considerable canopy leaching of Ca2+, K+ and weak organic acids at Val Gerola, where the symptoms of damage were more evident. In the area of Val Masino (SO, included since 1997 in the national CONECOFOR network, investigations focused on the effectiveness of the biological compartment in modifying fluxes of atmospheric elements, and on the role of nitrogen both as an
14. Spatial variation of mercury bioaccumulation in bats of Canada linked to atmospheric mercury deposition.
Science.gov (United States)
Chételat, John; Hickey, M Brian C; Poulain, Alexandre J; Dastoor, Ashu; Ryjkov, Andrei; McAlpine, Donald; Vanderwolf, Karen; Jung, Thomas S; Hale, Lesley; Cooke, Emma L L; Hobson, Dave; Jonasson, Kristin; Kaupas, Laura; McCarthy, Sara; McClelland, Christine; Morningstar, Derek; Norquay, Kaleigh J O; Novy, Richard; Player, Delanie; Redford, Tony; Simard, Anouk; Stamler, Samantha; Webber, Quinn M R; Yumvihoze, Emmanuel; Zanuttig, Michelle
2018-06-01
Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n=1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n=21) of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [M. septentrionalis]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88-12.78μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric
15. Controlling Factors of Mercury Wet Deposition and Precipitation Concentrations in Upstate New York
Science.gov (United States)
Ye, Z.; Mao, H.; Driscoll, C. T.
2017-12-01
Observations from the Mercury Deposition Network (MDN) at Huntington Wildlife Forest (HWF) suggested that a significant decline in Hg concentrations in precipitation was linked to Hg emission decreases in the United States, especially in the Northeast and Midwest, and yet Hg wet deposition has remained fairly constant over the past two decades. The present study was aimed to investigate how climatic, terrestrial, and anthropogenic factors had influenced the Hg wet deposition flux in upstate New York (NY). To achieve this, an improved Community Multiscale Air Quality (CMAQ) model was employed, which included state-of-the-art Hg and halogen chemistry mechanisms. A base simulation and five sensitivity simulations were conducted. The base simulation used 2010 meteorology, U.S. EPA NEI 2011, and GEOS-Chem output as initial and boundary conditions (ICs and BCs). The five sensitivity runs each changed one condition at the time as follows: 1-3) 2004, 2005, and 2007 meteorology instead of 2010, 4) NEI 2005 Hg anthropogenic emission out of NYS instead of NEI 2011, and 5) no in-state Hg anthropogenic emission. The study period of all the simulations was March - November 2010, and the domain covered the northeastern United States at 12 km resolution. As a result, compared with rural areas in NYS, Hg wet deposition and ambient Hg concentrations in urban areas were affected more significantly by in-state anthropogenic Hg emission. The in-state anthropogenic Hg emissions contributed up to 20% of Hg wet deposition at urban sites and cloud height, precipitation, wind speed and direction, and relative humidity, among which precipitation had the largest effects in most areas. Diluting effects were found in non-convective precipitation, which contributed 31-48% to changes in Hg concentration in precipitation.
16. Transfer of gaseous iodine (I2) from atmosphere to rice grains through dry deposition
International Nuclear Information System (INIS)
Uchida, Shigeo; Muramatsu, Yasuyuki; Sumiya, Misako; Ohmomo, Yoichiro
1989-01-01
The report briefly outlines parameters required to determine the transfer of 129 I from the atmosphere to rice grains, and presents results of a study in which the transfer of iodine from the atmosphere to rice grains is calculated using empirically determined parameters. There are four major parameters required for the calculation: (1) the major transfer route (translocation either from leaves or from the surface of hulls to rice grains), (2) rate of deposition onto the surface of leaves or hulls, (3) biological half-life of iodine deposited on leaves or hulls, and (4) either the rate of translocation from leaves to hulls (where the translocation from leaves is the major route) or the ratio of iodine distribution among hulls, unpolished rice grains, and polished rice grains (where the translocation from hulls is the major route). Techniques available to determine the translocation route, deposition rate, biological half-life and distribution ratio are outlined. Chemical forms of iodine, parameters relating to the transfer of gaseous iodine to paddy rice, and calculation models are also described. (N,K.)
17. Hg0 and HgCl2 Reference Gas Standards: ?NIST Traceability ...
Science.gov (United States)
EPA and NIST have collaborated to establish the necessary procedures for establishing the required NIST traceability of commercially-provided Hg0 and HgCl2 reference generators. This presentation will discuss the approach of a joint EPA/NIST study to accurately quantify the true concentrations of Hg0 and HgCl2 reference gases produced from high quality, NIST-traceable, commercial Hg0 and HgCl2 generators. This presentation will also discuss the availability of HCl and Hg0 compressed reference gas standards as a result of EPA's recently approved Alternative Methods 114 and 118. Gaseous elemental mercury (Hg0) and oxidized mercury (HgCl2) reference standards are integral to the use of mercury continuous emissions monitoring systems (Hg CEMS) for regulatory compliance emissions monitoring. However, a quantitative disparity of approximately 7-10% has been observed between commercial Hg0 and HgCl2 reference gases which currently limits the use of (HgCl2) reference gas standards. Resolving this disparity would enable the expanded use of (HgCl2) reference gas standards for regulatory compliance purposes.
18. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide
International Nuclear Information System (INIS)
Johnson, Kyle W.; Guruvenket, Srinivasan; Sailer, Robert A.; Ahrenkiel, S. Phillip; Schulz, Douglas L.
2013-01-01
Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H 2 O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF 2 . • Carbonaceous contamination from the precursor was minimal
19. Control of Toxic Chemicals in Puget Sound, Phase 3: Study of Atmospheric Deposition of Air Toxics to the Surface of Puget Sound
Energy Technology Data Exchange (ETDEWEB)
Brandenberger, Jill M.; Louchouarn, Patrick; Kuo, Li-Jung; Crecelius, Eric A.; Cullinan, Valerie I.; Gill, Gary A.; Garland, Charity R.; Williamson, J. B.; Dhammapala, R.
2010-07-05
The results of the Phase 1 Toxics Loading study suggested that runoff from the land surface and atmospheric deposition directly to marine waters have resulted in considerable loads of contaminants to Puget Sound (Hart Crowser et al. 2007). The limited data available for atmospheric deposition fluxes throughout Puget Sound was recognized as a significant data gap. Therefore, this study provided more recent or first reported atmospheric deposition fluxes of PAHs, PBDEs, and select trace elements for Puget Sound. Samples representing bulk atmospheric deposition were collected during 2008 and 2009 at seven stations around Puget Sound spanning from Padilla Bay south to Nisqually River including Hood Canal and the Straits of Juan de Fuca. Revised annual loading estimates for atmospheric deposition to the waters of Puget Sound were calculated for each of the toxics and demonstrated an overall decrease in the atmospheric loading estimates except for polybrominated diphenyl ethers (PBDEs) and total mercury (THg). The median atmospheric deposition flux of total PBDE (7.0 ng/m2/d) was higher than that of the Hart Crowser (2007) Phase 1 estimate (2.0 ng/m2/d). The THg was not significantly different from the original estimates. The median atmospheric deposition flux for pyrogenic PAHs (34.2 ng/m2/d; without TCB) shows a relatively narrow range across all stations (interquartile range: 21.2- 61.1 ng/m2/d) and shows no influence of season. The highest median fluxes for all parameters were measured at the industrial location in Tacoma and the lowest were recorded at the rural sites in Hood Canal and Sequim Bay. Finally, a semi-quantitative apportionment study permitted a first-order characterization of source inputs to the atmosphere of the Puget Sound. Both biomarker ratios and a principal component analysis confirmed regional data from the Puget Sound and Straits of Georgia region and pointed to the predominance of biomass and fossil fuel (mostly liquid petroleum products such
20. Mercury Concentration and Isotopic Composition of Epiphytic Tree Lichens in the Alberta Oil Sands Region
Science.gov (United States)
Mercury (Hg) is a toxic heavy metal that is found associated with fossil fuel deposits and that can be released to the atmosphere during fossil fuel combustion and/or processing. Hg emitted to the atmosphere can be deposited to aquatic and terrestrial ecosystems where it can be m...
1. Deposition of hybrid organic-inorganic composite coatings using an atmospheric plasma jet system.
Science.gov (United States)
Dembele, Amidou; Rahman, Mahfujur; Reid, Ian; Twomey, Barry; MacElroy, J M Don; Dowling, Denis P
2011-10-01
The objective of this study is to investigate the influence of alcohol addition on the incorporation of metal oxide nanoparticles into nm thick siloxane coatings. Titanium oxide (TiO2) nanoparticles with diameters of 30-80 nm were incorporated into an atmospheric plasma deposited tetramethylorthosilicate (TMOS) siloxane coating. The TMOS/TiO2 coating was deposited using the atmospheric plasma jet system known as PlasmaStream. In this system the liquid precursor/nanoparticle mixture is nebulised into the plasma. It was observed that prior to being nebulised the TiO2 particles agglomerated and settled over time in the TMOS/TiO2 mixture. In order to obtain a more stable nanoparticle/TMOS suspension the addition of the alcohols methanol, octanol and pentanol to this mixture was investigated. The addition of each of these alcohols was found to stabilise the nanoparticle suspension. The effect of the alcohol was therefore assessed with respect to the properties of the deposited coatings. It was observed that coatings deposited from TMOS/TiO2, with and without the addition of methanol were broadly similar. In contrast the coatings deposited with octanol and pentanol addition to the TMOS/TiO2 mixture were significantly thicker, for a given set of deposition parameters and were also more homogeneous. This would indicate that the alcohol precursor was incorporated into the plasma polymerised siloxane. The incorporation of the organic functionality from the alcohols was confirmed from FTIR spectra of the coatings. The difference in behaviour with alcohol type is likely to be due to the lower boiling point of methanol (65 degrees C), which is lower than the maximum plasma temperature measured at the jet orifice (77 degrees C). This temperature is significantly lower than the 196 degrees C and 136 degrees C boiling points of octanol and pentanol respectively. The friction of the coatings was determined using the Pin-on-disc technique. The more organic coatings deposited with
2. Methylation of Hg downstream from the Bonanza Hg mine, Oregon
Science.gov (United States)
Gray, John E.; Hines, Mark E.; Krabbenhoft, David P.; Thoms, Bryn
2012-01-01
Speciation of Hg and conversion to methyl-Hg were evaluated in stream sediment, stream water, and aquatic snails collected downstream from the Bonanza Hg mine, Oregon. Total production from the Bonanza mine was >1360t of Hg, during mining from the late 1800s to 1960, ranking it as an intermediate sized Hg mine on an international scale. The primary objective of this study was to evaluate the distribution, transport, and methylation of Hg downstream from a Hg mine in a coastal temperate climatic zone. Data shown here for methyl-Hg, a neurotoxin hazardous to humans, are the first reported for sediment and water from this area. Stream sediment collected from Foster Creek flowing downstream from the Bonanza mine contained elevated Hg concentrations that ranged from 590 to 71,000ng/g, all of which (except the most distal sample) exceeded the probable effect concentration (PEC) of 1060ng/g, the Hg concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in stream sediment collected from Foster Creek varied from 11 to 62ng/g and were highly elevated compared to regional baseline concentrations (0.11-0.82ng/g) established in this study. Methyl-Hg concentrations in stream sediment collected in this study showed a significant correlation with total organic C (TOC, R2=0.62), generally indicating increased methyl-Hg formation with increasing TOC in sediment. Isotopic-tracer methods indicated that several samples of Foster Creek sediment exhibited high rates of Hg-methylation. Concentrations of Hg in water collected downstream from the mine varied from 17 to 270ng/L and were also elevated compared to baselines, but all were below the 770ng/L Hg standard recommended by the USEPA to protect against chronic effects to aquatic wildlife. Concentrations of methyl-Hg in the water collected from Foster Creek ranged from 0.17 to 1.8ng/L, which were elevated compared to regional baseline sites upstream and downstream
3. Monolithic dual-band HgCdTe infrared detector structure
CSIR Research Space (South Africa)
Parish, G
1997-07-01
Full Text Available A monolithic HgCdTe photoconductive device structure is presented that is suitable for dual-band optically registered infrared photodetection in the two atmospheric transmission windows of 3-5 mu m and 8-12 mu m, which correspond to the mid...
4. Impact of acid atmospheric deposition on soils : quantification of chemical and hydrologic processes
NARCIS (Netherlands)
Grinsven, van J.J.M.
1988-01-01
Atmospheric deposition of SO x , NOx and NHx will cause major changes in the chemical composition of solutions in acid soils, which may affect the biological functions of the soil. This thesis deals with quantification of soil acidification by means of chemical
5. Heavy metal atmospheric deposition study in the South Ural Mountains
International Nuclear Information System (INIS)
Frontasyeva, M.V.; Smirnov, L.I.; Lyapunov, S.M.
2004-01-01
Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Urals, one of the most heavily polluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Ta, W, Au, Th, U) in soil and 33 elements Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) were determined by epithermal neutron activation analysis. The elements Cu, Cd and Pb (in moss samples only) were obtained by atomic absorption spectrometry. VARIMAX rotated principal component analysis was used to identify and characterize different pollution sources and to point out the most polluted areas. (author)
6. Atmospheric Deposition of Trace Elements Around Ulan-Bator City Studied by Moss and Lichen Biomonitoring Technique and INAA
CERN Document Server
Ganbold, G; Gundorina, S F; Frontasyeva, M V; Ostrovnaya, T M; Pavlov, S S; Tsendeekhuu, T
2005-01-01
For the first time the moss and lichen biomonitoring technique has been applied to air pollution in Mongolia (Ulan-Bator, the capital city). INAA at the IBR-2 reactor has made it possible to determine the content of 35 elements in moss and lichen biomonitors. Samples collected at sites located 10-15 km from the center of Ulan-Bator were analyzed by Instrumental Neutron Activation Analysis (INAA) using epithermal neutrons. The mosses (\\textit{Rhytidium rugosum}, \\textit{Thuidium abietinum}, \\textit{Entodon concinnus}) and lichens (\\textit{Cladonia stellaris}, \\textit{Parmelia separata}) were used to study the atmospheric deposition of trace elements. It was shown that the suggested types of mosses could be used as suitable biomonitors to estimate the concentration levels of heavy metals and trace elements in Ulan-Bator atmospheric deposition. The results are compared to the data of atmospheric deposition of some European countries.
7. Source discrimination of atmospheric metal deposition by multi-metal isotopes in the Three Gorges Reservoir region, China.
Science.gov (United States)
Liu, Jinling; Bi, Xiangyang; Li, Fanglin; Wang, Pengcong; Wu, Jin
2018-05-12
Concentrations of heavy metals, as well as isotopic compositions of mercury (Hg) and lead (Pb), in mosses (Bryum argenteum) from the Three Gorges Reservoir (TGR) region were investigated to decipher the sources of atmospheric metals in this region. Higher contents of metals (0.90 ± 0.65 mg/kg of Cd, 24.6 ± 27.4 mg/kg of Cu, and 36.1 ± 51.1 mg/kg of Pb) in the mosses from TGR were found compared with those from pollution-free regions. Principal component analysis (PCA) grouped the moss metals into four main components which were associated with both anthropogenic and natural sources. The ratios of Pb isotopes of the mosses (1.153-1.173 for 206 Pb/ 207 Pb and 2.094-2.129 for 208 Pb/ 206 Pb) fell between those of the traffic emissions and coals. Similarly, the compositions of δ 202 Hg (-4.29∼-2.33‰) and Δ 199 Hg (within ±0.2‰) were comparable to those of the coals and coal combustion emissions from China and India. These joined results of Pb and Hg isotope data give solid evidences that the coal combustion and traffic emissions are the main causes of metal accumulation in the TGR region. Copyright © 2018 Elsevier Ltd. All rights reserved.
8. Atmospheric Energy Deposition Modeling and Inference for Varied Meteoroid Structures
Science.gov (United States)
Wheeler, Lorien; Mathias, Donovan; Stokan, Edward; Brown, Peter
2018-01-01
Asteroids populations are highly diverse, ranging from coherent monoliths to loosely-bound rubble piles with a broad range of material and compositional properties. These different structures and properties could significantly affect how an asteroid breaks up and deposits energy in the atmosphere, and how much ground damage may occur from resulting blast waves. We have previously developed a fragment-cloud model (FCM) for assessing the atmospheric breakup and energy deposition of asteroids striking Earth. The approach represents ranges of breakup characteristics by combining progressive fragmentation with releases of variable fractions of debris and larger discrete fragments. In this work, we have extended the FCM to also represent asteroids with varied initial structures, such as rubble piles or fractured bodies. We have used the extended FCM to model the Chelyabinsk, Benesov, Kosice, and Tagish Lake meteors, and have obtained excellent matches to energy deposition profiles derived from their light curves. These matches provide validation for the FCM approach, help guide further model refinements, and enable inferences about pre-entry structure and breakup behavior. Results highlight differences in the amount of small debris vs. discrete fragments in matching the various flare characteristics of each meteor. The Chelyabinsk flares were best represented using relatively high debris fractions, while Kosice and Benesov cases were more notably driven by their discrete fragmentation characteristics, perhaps indicating more cohesive initial structures. Tagish Lake exhibited a combination of these characteristics, with lower-debris fragmentation at high altitudes followed by sudden disintegration into small debris in the lower flares. Results from all cases also suggest that lower ablation coefficients and debris spread rates may be more appropriate for the way in which debris clouds are represented in FCM, offering an avenue for future model refinement.
9. Lichens as biomonitors of atmospheric ammonium/ammonia deposition in Portugal
International Nuclear Information System (INIS)
Capelao, A.L.; Maguas, C.; Branquinho, C.; Cruz, C.; Martins-Loucao, M.A.
2000-01-01
The aim of the present work was to evaluate the potentiality of lichens as biomonitors of NH 4 + /NH 3 (ammonium/ammonia) and NO 3 - (nitrate) atmospheric deposition. For that, we used as a field station a rice plantation which is submitted, once a year, to air spraying fertilization with a mixture of nitrogen sources. Samples of an epiphytic lichen, Ramalina fastigiata, were collected from an ash-tree bordering the rice-plantation by the Sorraia River Valley (Central Portugal). The study started one month before fertilization and sampling was carried out for five months. The concentration of ammonium in the lichen was highly and significantly correlated with the number of days without precipitation before sampling, and had an inverse correlation with fluorescence values. Under these conditions, the amount of NH 4 + found in the lichen appears to reflect ammonium/ammonia dry deposition. (author)
10. Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center
Science.gov (United States)
Zhang, Kai; Zhang, Bao-Zhong; Li, Shao-Meng; Zhang, Lei-Ming; Staebler, Ralf; Zeng, Eddy Y.
2012-09-01
Atmospheric gaseous and size-segregated particle samples were collected from urban Guangzhou at the heights of 100 and 150 m above the ground in daytime and at night in August and December 2010, and were analyzed for polycyclic aromatic hydrocarbons (PAHs). Particulate PAHs were more abundant at night than in daytime, and significantly higher in winter than in summer. The observed vertical, diurnal, and seasonal variability in the occurrences of PAH were attributed to varying meteorological conditions and atmospheric boundary layers. More than 60% of the particulate PAHs were contained in particles in the accumulation mode with an aerodynamic diameter (Dp) in the range of 0.1-1.8 μm. Different mass transfer velocities by volatilization and condensation are considered the main causes for the different particle size distributions among individual PAHs, while combustion at different temperatures and atmospheric transport were probable causes of the observed seasonal variation in the size distribution of PAHs. Based on the modeled size-dependent dry deposition velocities, daily mean dry deposition fluxes of particulate PAHs ranged from 604 to 1190 ng m-2 d-1, with PAHs in coarse particles (Dp > 1.8 μm) accounting for 55-95% of the total fluxes. In addition, gaseous PAHs were estimated to contribute 0.6-3.1% to the total dry deposition fluxes if a conservative dry deposition velocity for gaseous species (2 × 10-4 m s-1) were used. Finally, disequilibrium phase partitioning, meteorological conditions and atmospheric transport were regarded as the main reasons for the variances in dry deposition velocities of individual PAHs.
11. Dynamic modelling of atmospherically-deposited Ni, Cu, Zn, Cd and Pb in Pennine catchments (northern England)
International Nuclear Information System (INIS)
Tipping, E.; Rothwell, J.J.; Shotbolt, L.; Lawlor, A.J.
2010-01-01
Simulation modelling with CHUM-AM was carried out to investigate the accumulation and release of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in six moorland catchments, five with organic-rich soils, one with calcareous brown earths, in the Pennine chain of northern England. The model considers two soil layers and a third layer of weathering mineral matter, and operates on a yearly timestep, driven by deposition scenarios covering the period 1400-2010. The principal processes controlling heavy metals are competitive solid-solution partitioning of solutes, chemical interactions in solution, and chemical weathering. Agreement between observed and simulated soil metal pools and surface water concentrations for recent years was generally satisfactory, the results confirming that most contemporary soil metal is from atmospheric pollution. Metals in catchments with organic-rich soils show some mobility, especially under more acid conditions, but the calcareous mineral soils have retained nearly all anthropogenic metal inputs. Complexation by dissolved organic matter and co-transport accounts for up to 80% of the Cu in surface waters. - CHUM-AM is applied to six differing moorland catchments to account for the accumulation and leaching of atmospherically-deposited trace metals over the past several centuries.
12. Dynamic modelling of atmospherically-deposited Ni, Cu, Zn, Cd and Pb in Pennine catchments (northern England)
Energy Technology Data Exchange (ETDEWEB)
Tipping, E., E-mail: et@ceh.ac.u [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom); Rothwell, J.J. [Upland Environments Research Unit, School of Environment and Development, University of Manchester, Manchester M13 9PL (United Kingdom); Shotbolt, L. [Geography Department, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Lawlor, A.J. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)
2010-05-15
Simulation modelling with CHUM-AM was carried out to investigate the accumulation and release of atmospherically-deposited heavy metals (Ni, Cu, Zn, Cd and Pb) in six moorland catchments, five with organic-rich soils, one with calcareous brown earths, in the Pennine chain of northern England. The model considers two soil layers and a third layer of weathering mineral matter, and operates on a yearly timestep, driven by deposition scenarios covering the period 1400-2010. The principal processes controlling heavy metals are competitive solid-solution partitioning of solutes, chemical interactions in solution, and chemical weathering. Agreement between observed and simulated soil metal pools and surface water concentrations for recent years was generally satisfactory, the results confirming that most contemporary soil metal is from atmospheric pollution. Metals in catchments with organic-rich soils show some mobility, especially under more acid conditions, but the calcareous mineral soils have retained nearly all anthropogenic metal inputs. Complexation by dissolved organic matter and co-transport accounts for up to 80% of the Cu in surface waters. - CHUM-AM is applied to six differing moorland catchments to account for the accumulation and leaching of atmospherically-deposited trace metals over the past several centuries.
13. Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies
International Nuclear Information System (INIS)
Parsons, Matthew J.; Long, David T.; Yohn, Sharon S.
2010-01-01
increasing after 1997. The cause of the recent Hg concentrations may be related to influx of contaminated watershed soils or sediments. Estimating the time frame for recovery is challenging in this system because the process of natural recovery seems to have been arrested and deeper, uncontaminated sediments, were not recovered as a basis for reference. However, a recovery to background conditions is likely not achievable since rates of Hg loading to nearby lakes and the current rate of atmospheric deposition are greater than an estimate of background conditions for Deer Lake. Assuming recovery continued after 2000, estimates of the time required for recovery varied based on the system state used to define it (e.g., recent rates of wet Hg deposition or Hg surface concentrations/fluxes from similar systems), but were less than 12 a. However, the recent increasing values of recovery indicators (e.g., Hg concentrations) suggests that these estimates are conservative and will be longer if recovery remains arrested, which may in part be due to the legacy of Hg contamination on the landscape. This study shows that estimates of recovery of highly disturbed lake systems can be made in the absence of within lake reference conditions by using comparisons to reference systems and challenges of estimating ages from atypical 210 Pb activity profiles can be overcome in part using event-based dating techniques.
14. Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies
Energy Technology Data Exchange (ETDEWEB)
Parsons, Matthew J. [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Long, David T., E-mail: long@msu.edu [Michigan State University, Department of Geological Sciences, 206 Natural Science, East Lansing, MI 48824 (United States); Yohn, Sharon S. [Juniata College, Raystown Field Station, Brumbaugh Academic Center, Huntingdon, PA 16652 (United States)
2010-11-15
their peak, remain elevated, and were increasing after 1997. The cause of the recent Hg concentrations may be related to influx of contaminated watershed soils or sediments. Estimating the time frame for recovery is challenging in this system because the process of natural recovery seems to have been arrested and deeper, uncontaminated sediments, were not recovered as a basis for reference. However, a recovery to background conditions is likely not achievable since rates of Hg loading to nearby lakes and the current rate of atmospheric deposition are greater than an estimate of background conditions for Deer Lake. Assuming recovery continued after 2000, estimates of the time required for recovery varied based on the system state used to define it (e.g., recent rates of wet Hg deposition or Hg surface concentrations/fluxes from similar systems), but were less than 12 a. However, the recent increasing values of recovery indicators (e.g., Hg concentrations) suggests that these estimates are conservative and will be longer if recovery remains arrested, which may in part be due to the legacy of Hg contamination on the landscape. This study shows that estimates of recovery of highly disturbed lake systems can be made in the absence of within lake reference conditions by using comparisons to reference systems and challenges of estimating ages from atypical {sup 210}Pb activity profiles can be overcome in part using event-based dating techniques.
15. 196Hg and 202Hg isotopic ratios in chondrites: revisited
International Nuclear Information System (INIS)
Jovanovic, S.; Reed, G.W. Jr.
1976-01-01
Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce 196 Hg and 202 Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly. (Auth.)
16. Cavity ring-down spectroscopy (CRDS) system for measuring atmospheric mercury using differential absorption
Science.gov (United States)
Pierce, A.; Obrist, D.; Moosmuller, H.; Moore, C.
2012-04-01
Atmospheric elemental mercury (Hg0) is a globally pervasive element that can be transported and deposited to remote ecosystems where it poses — particularly in its methylated form — harm to many organisms including humans. Current techniques for measurement of atmospheric Hg0 require several liters of sample air and several minutes for each analysis. Fast-response (i.e., 1 second or faster) measurements would improve our ability to understand and track chemical cycling of mercury in the atmosphere, including high frequency Hg0 fluctuations, sources and sinks, and chemical transformation processes. We present theory, design, challenges, and current results of our new prototype sensor based on cavity ring-down spectroscopy (CRDS) for fast-response measurement of Hg0 mass concentrations. CRDS is a direct absorption technique that implements path-lengths of multiple kilometers in a compact absorption cell using high-reflectivity mirrors, thereby improving sensitivity and reducing sample volume compared to conventional absorption spectroscopy. Our sensor includes a frequency-doubled, dye-laser emitting laser pulses tunable from 215 to 280 nm, pumped by a Q-switched, frequency tripled Nd:YAG laser with a pulse repetition rate of 50 Hz. We present how we successfully perform automated wavelength locking and stabilization of the laser to the peak Hg0 absorption line at 253.65 nm using an external isotopically-enriched mercury (202Hg0) cell. An emphasis of this presentation will be on the implementation of differential absorption measurement whereby measurements are alternated between the peak Hg0 absorption wavelength and a nearby wavelength "off" the absorption line. This can be achieved using a piezo electric tuning element that allows for pulse-by-pulse tuning and detuning of the laser "online" and "offline" of the Hg absorption line, and thereby allows for continuous correction of baseline extinction losses. Unexpected challenges with this approach included
17. Variability of atmospheric depositions of artificial radioelements and their transfer into soils
International Nuclear Information System (INIS)
Pourcelot, Laurent
2008-01-01
18. Acid Deposition Phenomena
International Nuclear Information System (INIS)
2004-01-01
Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H 2 SO 4 ) and nitric acids (HNO 3 ), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry
19. Seasonal and diurnal variations of Hg° over New England
Directory of Open Access Journals (Sweden)
J. D. Hegarty
2008-03-01
Full Text Available Factors influencing diurnal to interannual variability in Hg° over New England were investigated using multi-year measurements conducted by AIRMAP at the Thompson Farm (TF coastal site, an inland elevated site at Pac Monadnock (PM, and two month measurements on Appledore Island (AI in the Gulf of Maine. Mixing ratios of Hg° at TF showed distinct seasonality with maxima in March and minima in October. Hg° at AI tracked the trend at TF but with higher minima, while at PM the diurnal and annual cycles were dampened. In winter, Hg° was correlated most strongly with CO and NOy, indicative of anthropogenic emissions as their primary source. Our analysis indicates that Hg° had a regional background level of ~160 fmol/mol in winter, a dry deposition velocity of ~0.20 cm s−1 with a ~16 day lifetime in the coastal boundary layer in summer. The influence of oceanic emissions on ambient Hg° levels was identified using the Hg°-CHBr3 correlation at both TF and AI. Moreover, the lower Hg° levels and steeper decreasing warm season trend at TF (0.5–0.6 fmol/mol d−1 compared to PM (0.2–0.3 fmol/mol d−1 likely reflected the impact of marine halogen chemistry. Large interannual variability in warm season Hg° levels in 2004 versus 2005/2006 may be due to the role of precipitation patterns in influencing surface evasion of Hg°. In contrast, changes in wintertime maximum levels of Hg° were small compared to drastic reductions in CO, CO2, NOy, and SO2 from 2004/2005 to 2006/2007. These trends could be explained by a homogeneous distribution of Hg° over North American in winter due to its long lifetime and/or rapid removal of reactive mercury from anthropogenic sources. We caution that during warmer winters, the Hg°-CO slope possibly reflects Hg° loss relative to changes in CO more than their emission ratio.
20. Challenges in tracing the fate and effects of atmospheric polycyclic aromatic hydrocarbon deposition in vascular plants.
Science.gov (United States)
Desalme, Dorine; Binet, Philippe; Chiapusio, Geneviève
2013-05-07
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants that raise environmental concerns because of their toxicity. Their accumulation in vascular plants conditions harmful consequences to human health because of their position in the food chain. Consequently, understanding how atmospheric PAHs are taken up in plant tissues is crucial for risk assessment. In this review we synthesize current knowledge about PAH atmospheric deposition, accumulation in both gymnosperms and angiosperms, mechanisms of transfer, and ecological and physiological effects. PAHs emitted in the atmosphere partition between gas and particulate phases and undergo atmospheric deposition on shoots and soil. Most PAH concentration data from vascular plant leaves suggest that contamination occurs by both direct (air-leaf) and indirect (air-soil-root) pathways. Experimental studies demonstrate that PAHs affect plant growth, interfering with plant carbon allocation and root symbioses. Photosynthesis remains the most studied physiological process affected by PAHs. Among scientific challenges, identifying specific physiological transfer mechanisms and improving the understanding of plant-symbiont interactions in relation to PAH pollution remain pivotal for both fundamental and applied environmental sciences.
1. Atmospheric deposition of nitrogen at five subtropical forested sites in South China
International Nuclear Information System (INIS)
Chen, Xi Yun; Mulder, Jan
2007-01-01
Elevated concentrations of reactive nitrogen (N) in precipitation have been reported for many cities in China. Due to increased use of fossil fuels and expansion in agriculture, further increases in deposition of ammonia (NH x ) and reactive N oxides (NO y ) are predicted. Increased deposition of reactive N is likely to affect N dynamics and N runoff in forest ecosystems. Yet, in China little work has been done to quantify the levels of atmospheric N deposition in such systems. Here, we assess the deposition of inorganic N (ammonium, NH 4 + and nitrate, NO 3 - ) for five subtropical forest ecosystems in remote and urban areas of South China. Annual volume-weighted concentrations in bulk precipitation range from 0.18 to 1.55 mg NH 4 + -N L - 1 and from 0.12 to 0.74 mg NO 3 - -N L - 1 . These values are large and several times greater than those reported for remote sites of the world. The fluxes of total inorganic N (TIN) in wet-only deposition range from 0.8 to 2.3 g N m - 2 yr - 1 , with NH 4 + -N contributing 54% to 77%. Both the tree canopy and the ground vegetation layer are important in determining the net N flux reaching the forest floor, but the net effect varies from site to site. At TieShanPing (TSP), close to Chongqing city, and at CaiJiaTang (CJT), near Shaoshan (Hunan province), the canopy represents a net source of N, probably due to dry deposition. At the other three sites (LiuChongGuan (LCG), LeiGongShan (LGS), both in Guizhou province, and LiuXiHe (LXH) in Guangdong), a net loss of reactive N from precipitation water occurs in the canopy, probably due to uptake processes. The total annual atmospheric TIN load is estimated to range from at least 0.8 g N m - 2 yr - 1 to 4.0 g N m - 2 yr - 1 , with a considerable contribution from dry deposition. Concentrations and fluxes of inorganic N in tree canopy throughfall are greater than those in North America. Also the contribution of NH 4 + -N to TIN fluxes in throughfall (40% to 70%) is greater than in North
2. Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.
Science.gov (United States)
Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender
2016-05-01
Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.
3. Mercury in the atmosphere, snow and melt water ponds in the North Atlantic Ocean during Arctic summer.
Science.gov (United States)
Aspmo, Katrine; Temme, Christian; Berg, Torunn; Ferrari, Christophe; Gauchard, L Pierre-Alexis; Fain, Xavier; Wibetoe, Grethe
2006-07-01
Atmospheric mercury speciation measurements were performed during a 10 week Arctic summer expedition in the North Atlantic Ocean onboard the German research vessel RV Polarstern between June 15 and August 29, 2004. This expedition covered large areas of the North Atlantic and Arctic Oceans between latitudes 54 degrees N and 85 degrees N and longitudes 16 degrees W and 16 degrees E. Gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and mercury associated with particles (Hg-P) were measured during this study. In addition, total mercury in surface snow and meltwater ponds located on sea ice floes was measured. GEM showed a homogeneous distribution over the open North Atlantic Ocean (median 1.53 +/- 0.12 ng/m3), which is in contrast to the higher concentrations of GEM observed over sea ice (median 1.82 +/- 0.24 ng/m3). It is hypothesized that this results from either (re-) emission of mercury contained in snow and ice surfaces that was previously deposited during atmospheric mercury depletion events (AMDE) in the spring or evasion from the ocean due to increased reduction potential at high latitudes during Arctic summer. Measured concentrations of total mercury in surface snow and meltwater ponds were low (all samples RGM and Hg-P without a significant diurnal variability. These results indicate that the production and deposition of these reactive mercury species do not significantly contribute to the atmospheric mercury cycle in the North Atlantic Ocean during the Arctic summer.
4. Deposition rates of atmospheric particulates determined from 210Pb measurements in soils and air
International Nuclear Information System (INIS)
Likuku, A. S.; Branford, D.
2011-01-01
Deposition rates of atmospheric particles were determined using previously published 210P b data in soils and air. The dry deposition velocities for moorland and woodland soils were 2.2 ± 1.8 and 9 ± 2 mm · s - 1 , respectively. The 210P b concentration in rain was calculated to be 94 ± 10 mBq · L - 1. The large (∼ 4 times) deposition velocities in woodland relative to moorland soils is an indication of the degree of accumulation of particles, and most possibly contaminants within woodland soils, which is of practical importance in the mitigation of pollutant concentrations in urban areas by planting trees. (authors)
5. Mercury in stream water at five Czech catchments across a Hg and S deposition gradient
Czech Academy of Sciences Publication Activity Database
Navrátil, Tomáš; Shanley, J.; Rohovec, Jan; Oulehle, F.; Krám, P.; Matoušková, Šárka; Tesař, Miroslav; Hojdová, Maria
2015-01-01
Roč. 158, November (2015), s. 201-211 ISSN 0375-6742 R&D Projects: GA ČR(CZ) GAP210/11/1369 Institutional support: RVO:67985831 ; RVO:67985874 Keywords : Black Triangle * DOC quality * Filtered Hg * Hg/DOC ratio * Runoff fluxes * Seasonal changes * SUVA Subject RIV: DD - Geochemistry; DA - Hydrology ; Limnology (UH-J) Impact factor: 2.147, year: 2015
6. Application of a rule-based model to estimate mercury exchange for three background biomes in the continental United States
Science.gov (United States)
Hartman, J.S.; Weisberg, P.J.; Pillai, R.; Ericksen, J.A.; Kuiken, T.; Lindberg, S.E.; Zhang, H.; Rytuba, J.J.; Gustin, M.S.
2009-01-01
Ecosystems that have low mercury (Hg) concentrations (i.e., not enriched or impactedbygeologic or anthropogenic processes) cover most of the terrestrial surface area of the earth yet their role as a net source or sink for atmospheric Hg is uncertain. Here we use empirical data to develop a rule-based model implemented within a geographic information system framework to estimate the spatial and temporal patterns of Hg flux for semiarid deserts, grasslands, and deciduous forests representing 45% of the continental United States. This exercise provides an indication of whether these ecosystems are a net source or sink for atmospheric Hg as well as a basis for recommendation of data to collect in future field sampling campaigns. Results indicated that soil alone was a small net source of atmospheric Hg and that emitted Hg could be accounted for based on Hg input by wet deposition. When foliar assimilation and wet deposition are added to the area estimate of soil Hg flux these biomes are a sink for atmospheric Hg. ?? 2009 American Chemical Society.
7. Phase transition study in a [Cu2 HgI4:0⋅xAgI] mixed composite system
Diffraction, thermal analysis of compound, Ag2HgI4,. Cu2HgI4, Tl2HgI4 ... nitrogen atmosphere (200 ml/min) at a heating rate of. 5°C per min and a ..... Bates J B and Farington G C 1981 Proceedings of the interna- tional conference on fast ...
8. Mechanisms and rates of atmospheric deposition of selected trace elements and sulfate to a deciduous forest watershed. [Roles of dry and wet deposition concentrations measured in Walker Branch Watershed
Energy Technology Data Exchange (ETDEWEB)
Lindberg, S.E.; Harriss, R.C.; Turner, R.R.; Shriner, D.S.; Huff, D.D.
1979-06-01
The critical links between anthropogenic emissions to the atmosphere and their effects on ecosystems are the mechanisms and rates of atmospheric deposition. The atmospheric input of several trace elements and sulfate to a deciduous forest canopy is quantified and the major mechanisms of deposition are determined. The study area was Walker Branch Watershed (WBW) in eastern Tennessee. The presence of a significant quantity of fly ash and dispersed soil particles on upward-facing leaf and flat surfaces suggested sedimentation to be a major mechanism of dry deposition to upper canopy elements. The agreement for deposition rates measured to inert, flat surfaces and to leaves was good for Cd, SO/sub 4//sup =/, Zn, and Mn but poor for Pb. The precipitation concentrations of H/sup +/, Pb, Mn, and SO/sub 4//sup =/ reached maximum values during the summer months. About 90% of the wet deposition of Pb and SO/sub 4//sup =/ was attributed to scavenging by in-cloud processes while for Cd and Mn, removal by in-cloud scavenging accounted for 60 to 70% of the deposition. The interception of incoming rain by the forest canopy resulted in a net increase in the concentrations of Cd, Mn, Pb, Zn, and SO/sub 4//sup =/ but a net decrease in the concentration of H/sup +/. The source of these elements in the forest canopy was primarily dry deposited aerosols for Pb, primarily internal plant leaching for Mn, Cd, and Zn, and an approximately equal combination of the two for SO/sub 4//sup =/. Significant fractions of the total annual elemental flux to the forest floor in a representative chestnut oak stand were attributable to external sources for Pb (99%), Zn (44%), Cd (42%), SO/sub 4//sup =/ (39%), and Mn (14%), the remainder being related to internal element cycling mechanisms. On an annual scale the dry deposition process constituted a significant fraction of the total atmospheric input. (ERB)
9. Source, flux and balance of atmospheric deposition of metals at Ile-de-France; Source, flux et bilan des retombees atmospheriques de metaux en Ile de France
Energy Technology Data Exchange (ETDEWEB)
Azimi, S
2004-07-15
The urban atmosphere is submitted to large inputs of anthropogenic contaminants arising from both stationary (power plants, industries, etc.) and mobile (road traffic) sources. These small particles may be transported over long distances and affect ecosystems. Significant dry and wet atmospheric deposition also occurs locally and contributes to the contamination of urban runoff. The aim of this study is to compare heavy metal and hydrocarbon atmospheric deposition fluxes to other input ways on agricultural and urban areas to assess their importance. Moreover, a source investigation has been done to identify the main origins of these pollutants. Before the quantification of pollutant fluxes, a comparison of several sampling procedures was performed. As a result, the sampling of total atmospheric deposition is not affected by the funnel material (Teflon and polyethylene) or by the sampling duration (7 and 28 days). However, the rinsing step of the funnel walls showed a higher relative importance during short sampling periods. The relative amount contained in these solutions reached 24 to 40 % of the total flux during weekly sampling periods and 8 to 18 % during monthly sampling periods, whatever the element considered. The temporal evolution of atmospheric deposition showed no seasonal influence on flux variations during the 2001-2002 period. Considering an 8-year period behaviour, between 1994 and 2002, a significant decrease of the deposition fluxes of Cd, Cu, Pb and Zn occurred at the Creteil site which is placed in an industrialized area of the Paris suburb. The decreasing factor reached 16, 2.5, 4 and 7.5 for these elements respectively. At the Ile-de-France scale, the deposition flux levels on urban and semi-urban areas were of the same order of magnitude (?20 tonnes per year for Ba, Cu, Pb and Sr). Since semi-urban surface area is four times higher than urban ones, the important influence of anthropogenic activities on atmospheric deposition of urban areas is
10. Mercury-cycling in surface waters and in the atmosphere - species analysis for the investigation of transformation and transport properties of mercury
International Nuclear Information System (INIS)
Ebinghaus, R.; Hintelmann, H.; Wilken, R.D.
1994-01-01
The river Elbe has been one of the most contaminated rivers with regard to mercury for many years. In 1991 a length-profile has been measured for mercury and methylmercury (CH 3 Hg + ) from Obristvi, Czech Republic, to the German bight. Total mercury has been measured by cold vapor atomic absorption spectrometry (CVAAS). The organo mercury compounds have been separated by high performance liquid chromatography (HPLC) connected on-line to an atomic fluorescence spectrometer (AFS) by a continuous flow-system. Total mercury up to 120 mg Hg + /kg and CH 3 Hg + concentrations up to 130 μg CH 3 Hg + /kg could be detected in special sites. The formation of CH 3 Hg + in sediments can be caused besides the methylation of mercury, by sulphate reducing or methanogenic bacteria and transmethylation reactions with organometals. Atmospheric mercury concentrations have been measured at three different European sites. Samples have been collected on gold-coated glass balls or on quartz wool, respectively. After thermal desorption mercury has been determined using the two step amalgamation technique with AFS detection. Compared to natural background concentrations of total gaseous mercury (TGM), slightly increased levels could be detected at a rural site in Germany. This increase can probably be explained by long-range transport processes. Within the vicinity of a inactivated mercury production plant high concentrations of up to 13.5 ng/m 3 particle associated mercury (Hg part ) have been detected. Consequently, dry deposition of mercury in the particulate form can intensify the total deposition flux close to Hg-emitting sources. (orig.)
11. A thermodynamic stability of bulk and epitaxial CdHgTe, ZnHgTe and MnHgTe solid solutions
International Nuclear Information System (INIS)
Dejbuk, V.G.; Dremlyuzhenko, S.G.; Ostapov, S.Eh.
2005-01-01
A thermodynamics of Cd 1-x Hg x Te, Zn x Hg 1-x Te and Mg x Hg 1-x Te alloys has been investigated for a delta-lattice parameter model. The phase diagrams obtained show the stability of Cd 1-x Hg x Te, Zn x Hg 1-x Te in the whole range of compositions, alongside with a miscibility gap for Mn x Hg 1-x Te being of 0.35 x Hg 1-x Te/CdTe and Mn x Hg 1-x Te/Cd 0.96 Zn 0.04 Te epitaxial films result in lowering critical temperatures and narrowing the miscibility gap [ru
12. New system for vacuum deposition of refractory materials using an atmospheric-pressure inductively coupled plasma
International Nuclear Information System (INIS)
Merkle, B.D.; Kniseley, R.N.; Schmidt, F.A.
1987-01-01
We have successfully developed a technique utilizing an atmospheric-pressure inductively coupled plasma combined with a low-pressure deposition chamber for deposition of thin films. The equipment and method of operation are discussed. Refractory powders (Nb and Y 2 O 3 ) were injected into the plasma and deposited as Nb and substoichiometric yttrium oxide, YO/sub 1.49/, onto Fe and Cu substrates. The substoichiometric yttrium oxide deposit adhered well to the Fe and Cu substrates, while the Nb deposit adhered well to the Fe only. The Nb deposit on the Cu substrate flaked and peeled probably because of stresses induced from the thermal expansion mismatch between the Nb and Cu. Further studies will be undertaken to better understand the processes occurring in this type of plasma-coating system in order to optimize the instrumental parameters for particular coating applications
13. Spatial-temporal dynamics and sources of total Hg in a hydroelectric reservoir in the Western Amazon, Brazil.
Science.gov (United States)
Pestana, I A; Bastos, W R; Almeida, M G; de Carvalho, D P; Rezende, C E; Souza, C M M
2016-05-01
Damming rivers to construct hydroelectric reservoirs results in a series of impacts on the biogeochemical Hg cycle. For example, modifying the hydrodynamics of a natural watercourse can result in the suspension and transport of Hg deposits in the water column, which represents an exposure risk for biota. The objective of this study was to evaluate the influences of seasonality on the dispersion of total Hg in the Hydroelectric Power Plant (HPP)-Samuel Reservoir (Porto Velho/Brazil). Sampling campaigns were performed during the three following hydrological periods characteristic of the region: low (Oct/2011), ebbing (May/2012), and high (Feb/2013) water. Sediment profiles, suspended particulate matter (SPM), and aquatic macrophytes (Eicchornia crassipes and Oryza spp.) were collected, and their Hg concentrations and isotopic and elemental C and N signatures were determined. The drainage basin significantly influenced the SPM compositions during all the periods, with a small autochthonous influence from the reservoir during the low water. The highest SPM Hg concentrations inside the reservoir were observed during the high water period, suggesting that the hydrodynamics of this environment favor the suspension of fine SPM, which has a higher Hg adsorption capacity. The Hg concentrations in the sediment profiles were ten times lower than those in the SPM, indicating that large particles with low Hg concentrations were deposited to form the bottom sediment. Hg concentrations were higher in aquatic macrophyte roots than in their leaves and appeared to contribute to the formation of SPM during the low water period. In this environment, Hg transport mainly occurs in SPM from the Jamari River drainage basin, which is the primary source of Hg in this environment.
14. Atmospheric deposition, resuspension and root uptake of plutonium in corn and other grain-producing agroecosystems near a nuclear fuel facility
International Nuclear Information System (INIS)
Pinder, J.E. III; McLeod, K.W.; Adriano, D.C.; Corey, J.C.; Boni, A.L.
1989-01-01
Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake and translocation to grain. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the US Department of Energy's H-Area nuclear fuel chemical separations facility on the Savannah River Site was used to estimated parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining > resuspension of soil to grain surfaces > root uptake. Approximately 3.9 x 10 -5 of a year's atmospheric deposition is transferred to grain. Approximately 6.2 x 10 -9 of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 x 10 -10 of the soil inventory is absorbed by roots and translocated to grains
15. Trace organic compounds in wet atmospheric deposition: an overview
Science.gov (United States)
Steinheimer, T.R.; Johnson, S.M.
1987-01-01
An overview of the occurrence of organic compounds in wet atmospheric deposition is given. Multiplicity of sources and problems associated with source identification are discussed. Available literature is reviewed by using citations from Chemical Abstracts and Water Resources Abstracts through June 1985 and includes reports published through December 1984 that summarize current knowledge. Approaches to the chemical determination of organic compounds in precipitation are examined in addition to aspects of sampling protocols. Best methods for sample collection and preparation for instrumental analysis continue to be discussed among various investigators. Automatic wet-deposition-only devices for collection and extraction are preferred. Classes of organic compounds that have been identified in precipitation include a spectrum of compounds with differing properties of acidity or basicity, polarity, and water solubility. Those compounds that have been reported in rainfall, snowfall, and ice include hydrocarbons (both aromatic and nonaromatic), chlorinated derivatives of these hydrocarbons, carbonyl compounds (both acidic and nonacidic), and carboxylic acids and esters. Formic and acetic are the most abundant organic acids present. Cloudwater, fogwater, and mist also have been collected and analyzed for organic composition.
16. Mercury emission to the atmosphere from municipal solid waste landfills: A brief review
Science.gov (United States)
Tao, Zhengkai; Dai, Shijin; Chai, Xiaoli
2017-12-01
Municipal solid waste (MSW) landfill is regarded as an important emission source of atmospheric mercury (Hg), which is associated with potential health and environmental risks, as outlined by the Minamata Convention on Hg. This review presents the current state of knowledge with regards to landfill Hg sources, Hg levels in MSW and cover soils, Hg emission to the atmosphere, available Hg biogeochemical transformations, research methods for Hg emission, and important areas for future research. In addition, strategies for controlling landfill Hg emissions are considered, including reducing the Hg load in landfill and in situ controls. These approaches mainly focus on Hg source reduction, Hg recycling programs, public education, and in situ technology such as timely soil cover, vegetation, and end-of-pipe technology for controlling Hg emission from landfill gas.
17. Measurements of gaseous mercury exchanges at the sediment-water, water-atmosphere and sediment-atmosphere interfaces of a tidal environment (Arcachon Bay, France).
Science.gov (United States)
Bouchet, Sylvain; Tessier, Emmanuel; Monperrus, Mathilde; Bridou, Romain; Clavier, Jacques; Thouzeau, Gerard; Amouroux, David
2011-05-01
The elemental mercury evasion from non-impacted natural areas is of significant importance in the global Hg cycle due to their large spatial coverage. Intertidal areas represent a dynamic environment promoting the transformations of Hg species and their subsequent redistribution. A major challenge remains in providing reliable data on Hg species variability and fluxes under typical transient tidal conditions found in such environment. Field experiments were thus carried out to allow the assessment and comparison of the magnitude of the gaseous Hg fluxes at the three interfaces, sediment-water, sediment-atmosphere and water-atmosphere of a mesotidal temperate lagoon (Arcachon Bay, Aquitaine, France) over three distinct seasonal conditions. The fluxes between the sediment-water and the sediment-atmosphere interfaces were directly evaluated with field flux chambers, respectively static or dynamic. Water-atmosphere fluxes were evaluated from ambient concentrations using a gas exchange model. The fluxes at the sediment-water interface ranged from -5.0 to 5.1 ng m(-2) h(-1) and appeared mainly controlled by diffusion. The occurrence of macrophytic covers (i.e.Zostera noltii sp.) enhanced the fluxes under light radiations. The first direct measurements of sediment-atmosphere fluxes are reported here. The exchanges were more intense and variable than the two other interfaces, ranging between -78 and 40 ng m(-2) h(-1) and were mostly driven by the overlying atmospheric Hg concentrations and superficial sediment temperature. The exchanges between the water column and the atmosphere, computed as a function of wind speed and gaseous mercury saturation ranged from 0.4 to 14.5 ng m(-2) h(-1). The flux intensities recorded over the intertidal sediments periodically exposed to the atmosphere were roughly 2 to 3 times higher than the fluxes of the other interfaces. The evasion of elemental mercury from emerged intertidal sediments is probably a significant pathway for Hg evasion in
18. Zuotai and HgS differ from HgCl2 and methyl mercury in Hg accumulation and toxicity in weanling and aged rats.
Science.gov (United States)
Zhang, Bin-Bin; Li, Wen-Kai; Hou, Wei-Yu; Luo, Ya; Shi, Jing-Zhen; Li, Cen; Wei, Li-Xin; Liu, Jie
2017-09-15
Mercury sulfides are used in Ayurvedic medicines, Tibetan medicines, and Chinese medicines for thousands of years and are still used today. Cinnabar (α-HgS) and metacinnabar (β-HgS) are different from mercury chloride (HgCl 2 ) and methylmercury (MeHg) in their disposition and toxicity. Whether such scenario applies to weanling and aged animals is not known. To address this question, weanling (21d) and aged (450d) rats were orally given Zuotai (54% β-HgS, 30mg/kg), HgS (α-HgS, 30mg/kg), HgCl 2 (34.6mg/kg), or MeHg (MeHgCl, 3.2mg/kg) for 7days. Accumulation of Hg in kidney and liver, and the toxicity-sensitive gene expressions were examined. Animal body weight gain was decreased by HgCl 2 and to a lesser extent by MeHg, but unaltered after Zuotai and HgS. HgCl 2 and MeHg produced dramatic tissue Hg accumulation, increased kidney (kim-1 and Ngal) and liver (Ho-1) injury-sensitive gene expressions, but such changes are absent or mild after Zuotai and HgS. Aged rats were more susceptible than weanling rats to Hg toxicity. To examine roles of transporters in Hg accumulation, transporter gene expressions were examined. The expression of renal uptake transporters Oat1, Oct2, and Oatp4c1 and hepatic Oatp2 was decreased, while the expression of renal efflux transporter Mrp2, Mrp4 and Mdr1b was increased following HgCl 2 and MeHg, but unaffected by Zuotai and HgS. Thus, Zuotai and HgS differ from HgCl 2 and MeHg in producing tissue Hg accumulation and toxicity, and aged rats are more susceptible than weanling rats. Transporter expression could be adaptive means to reduce tissue Hg burden. Copyright © 2017 Elsevier Inc. All rights reserved.
19. Gradient measurements of gaseous elemental mercury (Hg0) in the marine boundary layer of the northwest Sea of Japan (East Sea).
Science.gov (United States)
Kalinchuk, Viktor; Lopatnikov, Evgeny; Astakhov, Anatoly
2018-06-01
Gaseous elemental mercury (Hg 0 ) is a prolific and persistent contaminant in the atmosphere. Atmospheric concentrations of Hg 0 were determined from 17 September to 7 October 2015 in the northwest Sea of Japan aboard the Russian research vessel Professor Gagarinsky. Simultaneous measurements of Hg 0 concentrations were performed 2 m and 20 m above the sea surface using automatic Hg 0 analysers RA-915M and RA-915+, respectively. Concentrations ranged from 0.3 to 25.9 ng/m 3 (n = 5207) and from 0.3 to 27.8 ng/m 3 (n = 4415), with medians of 1.7 and 1.6 ng/m 3 , respectively. Elevated Hg 0 was observed during three episodes from 19 to 22 September, likely caused by one or more of the following factors: 1) atmospheric transport of Hg 0 from the west and south-west (from N. Korea, China, and the Yellow Sea region); 2) Hg 0 emission from the sea due to pollution by water from the Tumannaya River; or 3) underwater geological activities. Increased Hg 0 concentration was observed during periods when air masses flowed from the south, and low concentrations were observed when air masses came from the north. A daytime increase of Hg 0 concentrations at a height of 2 m occurred simultaneously with decreasing Hg 0 at a height of 20 m. These diurnal variations suggest that two contrasting processes occur during the daytime in the marine boundary layer (MBL): Hg 0 emission from the sea surface and Hg 0 oxidation in the MBL by active halogens formed by photolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.
20. Atmospheric Nitrogen Deposition at Two Sites in an Arid Environment of Central Asia.
Science.gov (United States)
Li, Kaihui; Liu, Xuejun; Song, Wei; Chang, Yunhua; Hu, Yukun; Tian, Changyan
2013-01-01
Arid areas play a significant role in the global nitrogen cycle. Dry and wet deposition of inorganic nitrogen (N) species were monitored at one urban (SDS) and one suburban (TFS) site at Urumqi in a semi-arid region of central Asia. Atmospheric concentrations of NH3, NO2, HNO3, particulate ammonium and nitrate (pNH4 (+) and pNO3 (-)) concentrations and NH4-N and NO3-N concentrations in precipitation showed large monthly variations and averaged 7.1, 26.6, 2.4, 6.6, 2.7 µg N m(-3) and 1.3, 1.0 mg N L(-1) at both SDS and TFS. Nitrogen dry deposition fluxes were 40.7 and 36.0 kg N ha(-1) yr(-1) while wet deposition of N fluxes were 6.0 and 8.8 kg N ha(-1) yr(-1) at SDS and TFS, respectively. Total N deposition averaged 45.8 kg N ha(-1) yr(-1)at both sites. Our results indicate that N dry deposition has been a major part of total N deposition (83.8% on average) in an arid region of central Asia. Such high N deposition implies heavy environmental pollution and an important nutrient resource in arid regions.
1. Characterizations of wet mercury deposition to a remote islet (Pengjiayu) in the subtropical Northwest Pacific Ocean
Science.gov (United States)
Sheu, Guey-Rong; Lin, Neng-Huei
2013-10-01
Thirty-four weekly rainwater samples were collected in 2009 at Pengjiayu, a remote islet in the subtropical Northwest (NW) Pacific Ocean, to study the distribution of rainwater mercury (Hg) concentrations and associated wet deposition fluxes. This is the first study concerning wet Hg deposition to the subtropical NW Pacific Ocean downwind of the East Asian continent, which is the major source region for Hg emissions worldwide. Sample Hg concentrations ranged from 2.25 to 22.33 ng L-1, with a volume-weighted mean (VWM) concentration of 8.85 ng L-1. The annual wet Hg deposition flux was 10.18 μg m-2, about 2.5 times the fluxes measured at sites on the Pacific coast of the USA, supporting the hypothesis that deposition is higher in the western than in the eastern Pacific. Seasonal VWM concentrations were 7.23, 11.58, 7.82, and 9.84 ng L-1, whereas seasonal wet deposition fluxes were 2.14, 3.45, 2.38, and 2.21 μg m-2, for spring, summer, fall and winter, respectively. Higher summer wet Hg deposition was a function of both higher rainwater Hg concentration and greater rainfall. The seasonal pattern of rainwater Hg concentrations was the opposite of the general seasonal pattern of the East Asian air pollutant export. Since there is no significant anthropogenic Hg emission source on the islet of Pengjiayu, the observed high summertime rainwater Hg concentration hints at the importance of Hg0 oxidation and/or scavenging of upper-altitude reactive gaseous Hg (RGM) by deep convection. Direct anthropogenic RGM emissions from the East Asian continent may not contribute significantly to the rainwater Hg concentrations, but anthropogenic Hg0 emissions could be transported to the upper troposphere or marine boundary layer (MBL) where they can be oxidized to produce RGM, which will then be effectively scavenged by cloud water and rainwater.
2. Atmospheric nitrogen deposition influences denitrification and nitrous oxide production in lakes.
Science.gov (United States)
McCrackin, Michelle L; Elser, James J
2010-02-01
Microbially mediated denitrification is an important process that may ameliorate the effects of nitrogen (N) loading by permanently removing excess N inputs. In this study, we measured the rate of denitrification and nitrous oxide (N2O) production during denitrification in sediments from 32 Norwegian lakes at the high and low ends of a gradient of atmospheric N deposition. Denitrification and N2O production rates averaged 41.7 and 1.1 micromol N x m(-2) x h(-1), respectively, for high-deposition lakes. There was no detectable denitrification or N2O production in low-deposition lakes. Epilimnetic nitrate concentration was strongly correlated with denitrification rate (r2 = 0.67). We also measured the denitrification rate in response to experimental additions of organic carbon, nitrate, and phosphorus. Experimental nitrate additions stimulated denitrification in sediments of all lakes, regardless of N deposition level. In fact, the rate of denitrification in nitrate-amended treatments was the same magnitude for lakes in both deposition areas. These findings suggest that lake sediments possess considerable capacity to remove nitrate and that this capacity has not been saturated under conditions of chronic N loading. Further, nitrous oxide was nearly 3% of the total gaseous product during denitrification in high-deposition lakes, a fraction that is comparable to polluted marine sediments. Our findings suggest that, while lakes play an important role in N removal in the landscape, they may be a source of N2O emissions, especially in areas subject to elevated N inputs.
3. Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)
Science.gov (United States)
Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.
2010-12-01
Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how
4. 199Hg Moessbauer measurements on mercury, alloys and Hg-fluorides
International Nuclear Information System (INIS)
Wurtinger, W.; Kankeleit, E.
1979-01-01
The Moessbauer effect on the 158 keV 5/2 - -1/2 - transition in 199 Hg, of the order of 10 ppm, has been studied using the current integration technique. The isomer shift between the Hg(I)- and Hg(II)-fluorides as well as the quadrupole splitting in Hg 2 Pt and Hg 2 F 2 are interpreted in terms of relativistic Hartree-Fock-Slater and Molecular Orbital calculations. The following nuclear parameters could be derived: Δ[r 2 ] = (3.2+-1.1) 10 -3 fm 2 and Q(5/2 - ) = (-0.8+-0.4)b. Evidence for an oblate triaxially deformed 199 Hg nucleus is derived from particle plus rotor calculations. (orig.)
5. Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network
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Marchetto A
2014-04-01
Full Text Available Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network. Since 1997, atmospheric deposition was sampled and analyzed in the permanent plots of the Italian network for the evaluation of forest health (CONECOFOR, under the coordination of the Italian Forest Service. This paper presents the results of the activity carried out in 2009, when the EU-funded LIFE+ “FutMon” project allowed to extend the sampling network to 22 sites. Long-term trends will also be evaluated for the sampling sites with the longest time series. The sampling of open field bulk deposition was performed in a clearance close to the CONECOFOR permanent plots, while throughfall deposition and stemflow (in beech stand, only were sampled in the plot. Deposition samples were collected weekly and sent to the laboratories, where they were analyzed for pH, conductivity, major ions, and total carbon and nitrogen. Most measured variables showed a strong geographical gradient. For example, nitrogen deposition was relatively high in the Po plain (where the emissions of nitrogen oxides and ammonia are the highest and surrounding hills, reaching 10-20 kgN ha-1 y-1 in the open field and 13-25 kgN ha-1 y-1 in the throughfall. Sulphate deposition also showed a marked geographical gradient. Deposition of marine aerosol also had an important impact on the chemical composition of atmospheric deposition in Italy, together with the episodic deposition of Saharan dust, which showed a marked gradient, with highest values in the southernmost plots. Trend analysis was carried out on 10 sites running since the beginning of the program. A general negative trend in sulphate concentration was detected, paralleled in most plots by a positive trend in deposition pH, in good agreement with the strong reduction in the emission of sulphur dioxide recorded in the last decades. Nitrogen concentration also showed a significant decrease
6. Neutrons and gamma transport in atmosphere by Tripoli-2 code. Energy deposit and electron current time function
International Nuclear Information System (INIS)
Vergnaud, T.; Nimal, J.C.; Ulpat, J.P.; Faucheux, G.
1988-01-01
The Tripoli-2 computer code has been adapted to calculate, in addition to energy deposit in matter by neutrons (Kerma) the energy deposit by gamma produced in neutronic impacts and the induced recoil electron current. The energy deposit conduces at air ionization, consequently at a conductibility. This knowledge added at that of electron current permit to resolve the Maxwell equations of electromagnetic field. The study is realized for an atmospheric explosion 100 meters high. The calculations of energy deposit and electron current have been conducted as far as 2.5km [fr
7. Mercury Sources and Cycling in the Great Lakes: Dramatic Changes Resulting from Altered Atmospheric Loads and the Near-Shore Shunt
Science.gov (United States)
Krabbenhoft, D. P.; DeWild, J. F.; Maglio, M. M.; Tate, M. T.; Ogorek, J. M.; Hurley, J. P.; Lepak, R.
2013-12-01
Mercury (Hg) contamination of the aquatic food webs across the Great Lakes remains a significant environmental issue. However, our ability to prescribe corrective actions has been significantly hampered by a scarcity of data, particularly for methylmercury (MeHg) the most toxic and bioaccumulative form of mercury in freshwater ecosystems. As part of the Great Lakes Restoration Initiative initiated in 2010, a joint effort was undertaken by the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) to improve our understanding of total Hg and MeHg concentrations and distributions in the Great Lakes. Since 2010, sampling surveys have been conducted at about 15-20 stations twice annually (April and August) at 15-20 stations per lake to collect data from both cold and warm water conditions. All sampling was conducted using trace-metal free protocols using a sampling rosette equipped with 12 Teflon-lined Niskin. Water samples were collected at predetermined depths: mid-epilimnion, mid-thermocline, deep chlorophyll layer, mid-hypolimnion, and about 2 meters above the bottom. Seston samples were collected from the top 20 meters using plankton nets, while bottom sediments and benthos samples were acquired using a ponar sampler. Water, biota, and sediment samples were all analyzed for Hg and MeHg concentration at the USGS Mercury Research Laboratory in Middleton, Wisconsin. Several important trends are apparent from the water column samples. First, most stations reveal a strong top-to-bottom declining trend total Hg concentration, underscoring the importance of atmospheric deposition to the Great Lakes. Methylmercury profiles, show maximal concentrations at the thermocline or deep chlorophyll layer, suggesting in situ water-column MeHg production. Calculations suggest this in-lake MeHg source is similar in magnitude to tributary loading of MeHg, which heretofore was thought to be the dominant MeHg source. Aqueous total Hg results also suggest that
8. Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011
Science.gov (United States)
Morino, Y.; Ohara, T.; Nishizawa, M.
2011-12-01
To understand the atmospheric behavior of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011, we simulated the transport and deposition of iodine-131 and cesium-137 using a chemical transport model. The model roughly reproduced the observed temporal and spatial variations of deposition rates over 15 Japanese prefectures (60-400 km from the plant), including Tokyo, although there were some discrepancies between the simulated and observed rates. These discrepancies were likely due to uncertainties in the simulation of emission, transport, and deposition processes in the model. A budget analysis indicated that approximately 13% of iodine-131 and 22% of cesium-137 were deposited over land in Japan, and the rest was deposited over the ocean or transported out of the model domain (700 × 700 km2). Radioactivity budgets are sensitive to temporal emission patterns. Accurate estimation of emissions to the air is important for estimation of the atmospheric behavior of radionuclides and their subsequent behavior in land water, soil, vegetation, and the ocean.
9. Methylmercury declines in a boreal peatland when experimental sulfate deposition decreases
Science.gov (United States)
Jill K. Coleman Wasik; Carl P.J. Mitchell; Daniel R. Engstrom; Edward B. Swain; Bruce A. Monson; Steven J. Balogh; Jeffrey D. Jeremiason; Brian A. Branfireun; Susan L. Eggert; Randall K. Kolka; James E. Almendinger
2012-01-01
Between 2001 and 2008 we experimentally manipulated atmospheric sulfate-loading to a small boreal peatland and monitored the resulting short and long-term changes in methylmercury (MeHg) production. MeHg concentrations and %MeHg (fraction of total-Hg (HgT) present as MeHg) in the porewaters of the experimental treatment reached peak values within...
10. Sources of mercury in sediments, water, and fish of the lakes of Whatcom County, Washington
Science.gov (United States)
Paulson, Anthony J.
2004-01-01
Concerns about mercury (Hg) contamination in Lake Whatcom, Washington, were raised in the late 1990s after a watershed protection survey reported elevated concentrations of Hg in smallmouth bass. The U.S. Geological Survey, the Whatcom County Health Department, and the Washington State Department of Ecology (Ecology) cooperated to develop a study to review existing data and collect new data that would lead to a better understanding of Hg deposition to Lake Whatcom and other lakes in Whatcom County, Washington. A simple atmospheric deposition model was developed that allowed comparisons of the deposition of Hg to the surfaces of each lake. Estimates of Hg deposition derived from the model indicated that the most significant deposition of Hg would have occurred to the lakes north of the City of Bellingham. These lakes were in the primary wind pattern of two municipal waste incinerators. Of all the lakes examined, basin 1 of Lake Whatcom would have been most affected by the Hg emissions from the chlor-alkali plant and the municipal sewage-sludge incinerator in the City of Bellingham. The length-adjusted concentrations of Hg in largemouth and smallmouth bass were not related to estimated deposition rates of Hg to the lakes from local atmospheric sources. Total Hg concentrations in the surface sediments of Lake Whatcom are affected by the sedimentation of fine-grained particles, whereas organic carbon regulates the concentration of methyl-Hg in the surface sediments of the lake. Hg concentrations in dated sediment core samples indicate that increases in Hg sedimentation were largest during the first half of the 20th century. Increases in Hg sedimentation were smaller after the chlor-alkali plant and the incinerators began operating between 1964 and 1984. Analysis of sediments recently deposited in basin 1 of Lake Whatcom, Lake Terrell, and Lake Samish indicates a decrease in Hg sedimentation. Concentrations of Hg in Seattle precipitation and in tributary waters were
11. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition
Energy Technology Data Exchange (ETDEWEB)
Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd., NW, Washington, DC 20015 (United States)
2015-11-02
Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.
12. Atmospheric deposition having been one of the major source of Pb in Jiaozhou Bay
Science.gov (United States)
Yang, Dongfang; Miao, Zhenqing; Zhang, Xiaolong; Wang, Qi; Li, Haixia
2018-03-01
Many marine bays have been polluted by Pb due to the rapid development of industry, and identifying the major source of Pb is essential to pollution control. This paper analyzed the distribution and pollution source of Pb in Jiaozhou Bay in 1988. Results showed that Pb contents in surface waters in Jiaozhou Bay in April, July and October 1988 were 5.52-24.61 μg L‑1, 7.66-38.62 μg L‑1 and 6.89-19.30 μg L‑1, respectively. The major Pb sources in this bay were atmospheric deposition, and marine current, whose source strengths were 19.30-24.61μg L‑1 and 38.62 μg L‑1, respectively. Atmospheric deposition had been one of the major Pb sources in Jiaozhou Bay, and the source strengths were stable and strong. The pollution level of Pb in this bay in 1988 was moderate to heavy, and the source control measurements were necessary.
13. Depletion of atmospheric gaseous elemental mercury by plant uptake at Mt. Changbai, Northeast China
Directory of Open Access Journals (Sweden)
X. Fu
2016-10-01
Full Text Available There exists observational evidence that gaseous elemental mercury (GEM can be readily removed from the atmosphere via chemical oxidation followed by deposition in the polar and sub-polar regions, free troposphere, lower stratosphere, and marine boundary layer under specific environmental conditions. Here we report GEM depletions in a temperate mixed forest at Mt. Changbai, Northeast China. The strong depletions occurred predominantly at night during the leaf-growing season and in the absence of gaseous oxidized mercury (GOM enrichment (GOM < 3 pg m−3. Vertical gradients of decreasing GEM concentrations from layers above to under forest canopy suggest in situ loss of GEM to forest canopy at Mt. Changbai. Foliar GEM flux measurements showed that the foliage of two predominant tree species is a net sink of GEM at night, with a mean flux of −1.8 ± 0.3 ng m2 h−1 over Fraxinus mandshurica (deciduous tree species and −0.1 ± 0.2 ng m2 h−1 over Pinus Koraiensis (evergreen tree species. Daily integrated GEM δ202Hg, Δ199Hg, and Δ200Hg at Mt. Changbai during 8–18 July 2013 ranged from −0.34 to 0.91 ‰, from −0.11 to −0.04 ‰ and from −0.06 to 0.01 ‰, respectively. A large positive shift in GEM δ202Hg occurred during the strong GEM depletion events, whereas Δ199Hg and Δ200Hg remained essentially unchanged. The observational findings and box model results show that uptake of GEM by forest canopy plays a predominant role in the GEM depletion at Mt. Changbai forest. Such depletion events of GEM are likely to be a widespread phenomenon, suggesting that the forest ecosystem represents one of the largest sinks ( ∼ 1930 Mg of atmospheric Hg on a global scale.
14. Mercury Stable Isotopes Discriminate Different Populations of European Seabass and Trace Potential Hg Sources around Europe.
Science.gov (United States)
Cransveld, Alice; Amouroux, David; Tessier, Emmanuel; Koutrakis, Emmanuil; Ozturk, Ayaka A; Bettoso, Nicola; Mieiro, Cláudia L; Bérail, Sylvain; Barre, Julien P G; Sturaro, Nicolas; Schnitzler, Joseph; Das, Krishna
2017-11-07
Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ 202 Hg and Δ 199 Hg values in SIBER enabled us to estimate Hg isotopic niches, successfully discriminating several populations. Recursive-partitioning analyses demonstrated the relevance of Hg stable isotopes as discriminating tools. Hg isotopic values also provided insight on Hg contamination sources for biota in coastal environment. The overall narrow range of δ 202 Hg around Europe was suggested to be related to a global atmospheric contamination while δ 202 Hg at some sites was linked either to background contamination, or with local contamination sources. Δ 199 Hg was related to Hg levels of fish but we also suggest a relation with ecological conditions. Throughout this study, results from the Black Sea population stood out, displaying a Hg cycling similar to fresh water lakes. Our findings bring out the possibility to use Hg isotopes in order to discriminate distinct populations, to explore the Hg cycle on a large scale (Europe) and to distinguish sites contaminated by global versus local Hg source. The interest of using Hg sable isotopes to investigate the whole European Hg cycle is clearly highlighted.
15. Tracing the fate of atmospheric nitrate deposited onto a forest ecosystem in Eastern Asia using Δ17O
Directory of Open Access Journals (Sweden)
I. Noguchi
2010-02-01
Full Text Available The stable isotopic compositions of nitrate in precipitation (wet deposition and groundwater (spring, lake, and stream water were determined for the island of Rishiri, Japan, so as to use the 17O anomalies (Δ17O to trace the fate of atmospheric nitrate that had deposited onto the island ecosystem, which is a representative background forest ecosystem for eastern Asia. The deposited nitrate had large 17O anomalies with Δ17O values ranging from +20.8‰ to +34.5‰ (n = 32 with +26.2‰ being the annual average. The maximum Δ17O value of +34.5‰, obtained for precipitation on the 23rd to 24th of February 2007, was an extraordinarily large value among values for all samples of precipitation in Rishiri. Most nitrate in the sample might have been produced via NO3 radical in a highly polluted air mass that had been supplied from megacities on the eastern coast of the Asian continent. On the other hand, nitrate in groundwater had small Δ17O values ranging from +0.9‰ to 3.2‰ (n = 19, which corresponds to an mixing ratio of atmospheric nitrate to total nitrate of (7.4±2.6%. Comparing the inflow and outflow of atmospheric nitrate in groundwater within the island, we estimated that the direct drainage accounts for (8.8±4.6% of atmospheric nitrate that has deposited on the island and that the residual portion has undergone biological processing before being exported from the forest ecosystem.
16. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere
International Nuclear Information System (INIS)
Smith Korsholm, U.; Havskov Soerensen, J.; Astrup, P.; Lauritzen, B.
2011-04-01
The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)
17. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere
Energy Technology Data Exchange (ETDEWEB)
Smith Korsholm, U.; Havskov Soerensen, J. (Danish Meteorological Institute (DMI), Copenhagen (Denmark)); Astrup, P.; Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy. Radiation Research Div., Roskilde (Denmark))
2011-04-15
The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)
18. Atmospheric organic nitrogen deposition: analysis of nationwide data and a case study in Northeast China.
Science.gov (United States)
Jiang, C M; Yu, W T; Ma, Q; Xu, Y G; Zou, H; Zhang, S C; Sheng, W P
2013-11-01
The origin of atmospheric dissolved organic nitrogen (DON) deposition is not very clear at present. Across China, the DON deposition was substantially larger than that of world and Europe, and we found significant positive correlation between contribution of DON and the deposition flux with pristine site data lying in outlier, possibly reflecting the acute air quality problems in China. For a case study in Northeast China, we revealed the deposited DON was mainly derived from intensive agricultural activities rather than the natural sources by analyzing the compiled dataset across China and correlating DON flux with NH4(+)-N and NO3(-)-N. Crop pollens and combustion of fossil fuels for heating probably contributed to summer and autumn DON flux respectively. Overall, in Northeast China, DON deposition could exert important roles in agro-ecosystem nutrient management and carbon sequestration of natural ecosystems; nationally, it was suggested to found rational network for monitoring DON deposition. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.
19. Development of atmospheric acid deposition in China from the 1990s to the 2010s
International Nuclear Information System (INIS)
Yu, Haili; He, Nianpeng; Wang, Qiufeng; Zhu, Jianxing; Gao, Yang; Zhang, Yunhai; Jia, Yanlong; Yu, Guirui
2017-01-01
Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO 4 2− ) and nitrate (NO 3 − ) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO 4 2− deposition declined from 40.54 to 34.87 kg S ha −1 yr −1 but average NO 3 − deposition increased from 4.44 to 7.73 kg N ha −1 yr −1 . Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions. - Highlights: • Explore spatial and temporal dynamics of wet acid deposition during three decades in China. • Acid
20. Depositional characteristics of atmospheric polybrominated diphenyl ethers on tree barks.
Science.gov (United States)
Chun, Man Young
2014-07-17
This study was conducted to determine the depositional characteristics of several tree barks, including Ginkgo (Ginkgo biloba), Pine (Pinus densiflora), Platanus (Platanus), and Metasequoia (Metasequoia glyptostroboides). These were used as passive air sampler (PAS) of atmospheric polybrominated diphenyl ethers (PBDEs). Tree barks were sampled from the same site. PBDEs were analyzed by highresolution gas chromatography/high-resolution mass spectrometer, and the lipid content was measured using the gravimetric method by n-hexane extraction. Gingko contained the highest lipid content (7.82 mg/g dry), whereas pine (4.85 mg/g dry), Platanus (3.61 mg/g dry), and Metasequoia (0.97 mg/g dry) had relatively lower content. The highest total PBDEs concentration was observed in Metasequoia (83,159.0 pg/g dry), followed by Ginkgo (53,538.4 pg/g dry), Pine (20,266.4 pg/g dry), and Platanus (12,572.0 pg/g dry). There were poor correlations between lipid content and total PBDE concentrations in tree barks (R(2)=0.1011, p =0.682). Among the PBDE congeners, BDE 206, 207 and 209 were highly brominated PBDEs that are sorbed to particulates in ambient air, which accounted for 90.5% (84.3-95.6%) of the concentration and were therefore identified as the main PBDE congener. The concentrations of particulate PBDEs deposited on tree barks were dependent on morphological characteristics such as surface area or roughness of barks. Therefore, when using the tree barks as the PAS of the atmospheric PBDEs, samples belonging to same tree species should be collected to reduce errors and to obtain reliable data.
1. Simulation of trace metals and PAH atmospheric pollution over Greater Paris: Concentrations and deposition on urban surfaces
Science.gov (United States)
Thouron, L.; Seigneur, C.; Kim, Y.; Legorgeu, C.; Roustan, Y.; Bruge, B.
2017-10-01
Urban areas can be subject not only to poor air quality, but also to contamination of other environmental media by air pollutants. Here, we address the potential transfer of selected air pollutants (two metals and three PAH) to urban surfaces. To that end, we simulate meteorology and air pollution from Europe to a Paris suburban neighborhood, using a four-level one-way nesting approach. The meteorological and air quality simulations use urban canopy sub-models in order to better represent the effect of the urban morphology on the air flow, atmospheric dispersion, and deposition of air pollutants to urban surfaces. This modeling approach allows us to distinguish air pollutant deposition among various urban surfaces (roofs, roads, and walls). Meteorological model performance is satisfactory, showing improved results compared to earlier simulations, although precipitation amounts are underestimated. Concentration simulation results are also satisfactory for both metals, with a fractional bias Paris region. The model simulation results suggest that both wet and dry deposition processes need to be considered when estimating the transfer of air pollutants to other environmental media. Dry deposition fluxes to various urban surfaces are mostly uniform for PAH, which are entirely present in fine particles. However, there is significantly less wall deposition compared to deposition to roofs and roads for trace metals, due to their coarse fraction. Meteorology, particle size distribution, and urban morphology are all important factors affecting air pollutant deposition. Future work should focus on the collection of data suitable to evaluate the performance of atmospheric models for both wet and dry deposition with fine spatial resolution.
2. Optical characterization of a-Si:H thin films grown by Hg-Photo-CVD
International Nuclear Information System (INIS)
Barhdadi, A.; Karbal, S.; M'Gafad, N.; Benmakhlouf, A.; Chafik El Idrissi, M.; Aka, B.M.
2006-08-01
Mercury-Sensitized Photo-Assisted Chemical Vapor Deposition (Hg-Photo-CVD) technique opens new possibilities for reducing thin film growth temperature and producing novel semiconductor materials suitable for the future generation of high efficiency thin film solar cells onto low cost flexible plastic substrates. This paper provides some experimental data resulting from the optical characterization of hydrogenated amorphous silicon thin films grown by this deposition technique. Experiments have been performed on both as-deposited layers and thermal annealed ones. (author) [fr
3. Studies of the 198Hg(d,d') and 198Hg(d,p) reactions
Science.gov (United States)
Diaz Varela, Alejandra; Garrett, P. E.; Rand, E. T.; Ball, G. C.; Bilstein, V.; Laffoley, A. T.; Maclean, A. D.; Svensson, C. E.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.
2017-09-01
Limits on the electric dipole moment (EDM) continue to decrease for 199Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for 199Hg is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. The E 3 and E 1 strength distributions to the ground state of 199Hg, and E 2 transitions amongst excited states, would be ideal information to further constrain 199Hg Schiff moment theoretical models. The high level density of 199Hg makes those determinations challenging, however the similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near 199Hg, two experiments, 198Hg(d,d') 198Hg and 198Hg(d,p)199Hg reaction were performed using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a 198Hg32S target. The (d,d') reaction allows us to probe the desired E 2 and E 3 matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of 199Hg.
4. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands
Directory of Open Access Journals (Sweden)
P. Pinho
2012-03-01
Full Text Available Nitrogen (N has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds such as critical loads (deposition fluxes and levels (concentrations can be established. Few studies have assessed these thresholds for semi-natural Mediterranean ecosystems. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands. We have considered changes in epiphytic lichen communities, one of the most sensitive comunity indicators of excessive N in the atmosphere. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done for a Mediterranean climate in evergreen cork-oak woodlands, based on the relation between lichen functional diversity and modelled N deposition for critical loads and measured annual atmospheric ammonia concentrations for critical levels, evaluated downwind from a reduced N source (a cattle barn. Modelling the highly significant relationship between lichen functional groups and annual atmospheric ammonia concentration showed the critical level to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Modelling the highly significant relationship between lichen functional groups and N deposition showed that the critical load was lower than 26 kg (N ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should aid development of policies to protect Mediterranean woodlands from the initial effects of excessive N.
5. Enhancing atmospheric mercury research in China to improve the current understanding of the global mercury cycle: the need for urgent and closely coordinated efforts.
Science.gov (United States)
Ci, Zhijia; Zhang, Xiaoshan; Wang, Zhangwei
2012-06-05
The current understanding of the global mercury (Hg) cycle remains uncertain because Hg behavior in the environment is very complicated. The special property of Hg causes the atmosphere to be the most important medium for worldwide dispersion and transformation. The source and fate of atmospheric Hg and its interaction with the surface environment are the essential topics in the global Hg cycle. Recent declining measurement trends of Hg in the atmosphere are in apparent conflict with the increasing trends in global anthropogenic Hg emissions. As the single largest country contributor of anthropogenic Hg emission, China's role in the global Hg cycle will become more and more important in the context of the decreasing man-made Hg emission from developed regions. However, much less Hg information in China is available. As a global pollutant which undergoes long-range transport and is persistence in the environment, increasing Hg knowledge in China could not only promote the Hg regulation in this country but also improve the understanding of the fundamental of the global Hg cycle and further push the abatement of this toxin on a global scale. Then the atmospheric Hg research in China may be a breakthrough for improving the current understanding of the global Hg cycle. However, due to the complex behavior of Hg in the atmosphere, a deeper understanding of the atmospheric Hg cycle in China needs greater cooperation across fields.
6. History of HgTe-based photodetectors in Poland
Science.gov (United States)
Rogalski, A.
2010-09-01
In Poland, the HgCdTe studies began in 1960 at the Institute of Physics, Warsaw University. The material processing laboratory was created by Giriat and later by Dziuba, Gałązka, and others. Bridgman technique with sealed thick wall quartz ampoules was used to grow material suitable for research and experimental devices. Among the first papers published in 1961 and 1963 there were the Polish works devoted to preparation, doping, and electrical properties of HgCdTe. Infrared detector's research and development efforts in Poland were concentrated mostly on uncooled market niche. At the beginning, a modified isothermal vapour phase epitaxy has been used for research and commercial fabrication of photoconductive, photoelectromagnetic and other HgCdTe devices. Bulk growth and liquid phase epitaxy were also used. Recently, the fabrication of infrared devices relies on low temperature epitaxial technique, namely metalorganic vapour phase deposition. At present stage of development, the photoconductive and photoelectromagnetic (PEM) detectors are gradually replaced with photovoltaic devices which offer inherent advantages of no electric or magnetic bias, no heat load and no flicker noise. Potentially, photodiodes offer high performance and very fast response. However, conventional photovoltaic uncooled detectors suffer from low quantum efficiency and very low junction resistance. The problems have been solved with advanced band gap engineered architecture, multiple cell heterojunction devices connected in series, and monolithic integration of the detectors with microoptics. In final part of the paper, the Polish achievements in technology and performance of HgMnTe and HgZnTe photodetectors are presented.
7. 46 CFR 53.12-1 - General (modifies HG-600 through HG-640).
Science.gov (United States)
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false General (modifies HG-600 through HG-640). 53.12-1... HEATING BOILERS Instruments, Fittings, and Controls (Article 6) § 53.12-1 General (modifies HG-600 through HG-640). (a) The instruments, fittings and controls for heating boilers shall be as indicated in HG...
8. Mercury distribution in the foliage and soil profiles of the Tibetan forest: Processes and implications for regional cycling
International Nuclear Information System (INIS)
Gong, Ping; Wang, Xiao-ping; Xue, Yong-gang; Xu, Bai-qing; Yao, Tan-dong
2014-01-01
Remote forests are considered a pool of Mercury (Hg) in the global Hg cycle. However, notably few studies have investigated the fate of Hg in the Tibetan forest. In this study, fifty-two foliage samples and seven litter/soil profiles were collected throughout the Tibetan forest. The concentrations of total Hg (THg) in foliage were positively correlated with longitude and negatively correlated with altitude, indicating that the emission of Hg is expected to decrease with increasing distance from emission sources to the Tibetan forest. The deposition flux of THg in the Tibetan forest (with an air-to-forest ground flux of 9.2 μg/m 2 /year) is ∼2 times the flux in clearings, which is suggestive of enhanced Hg deposition by the forest. The depositional Hg is eventually stored in the forest soil, and the soil acts as a net ‘sink’ for Hg. - Highlights: • Foliage can be used as bio-indicator for monitoring the spatial Hg distribution. • The Tibetan forest can enhance the atmospheric Hg deposition to the ground. • The Tibetan forest soil is a pool of Hg that acts to delay the regional cycling of Hg. - The Tibetan forest can accumulate atmospheric Hg, which undergoes long-range transport, and the soil of Tibetan forest acts as the final Hg ‘sink’
9. Deposition of radionuclides and their subsequent relocation in the environment following an accidental release to the atmosphere
International Nuclear Information System (INIS)
Underwood, B.Y.; Roed, J.; Paretzke, H.G.
1993-01-01
The objective of the project is to improve, as necessary, the models and parameterizations used in estimating the intensity and spatial distribution of deposited activity, and the total health/economic impact of such deposits in assessments of the consequences of accidental releases of radioactivity. The study comprises the influence of various weather conditions on deposition; the resuspension of deposited 137 Cs activity; the weathering of deposits in urban and rural environments; the ultimate fate and dosimetric impact of radionuclides carried by urban run-off water; the impact of the atmosphere's dispersion capabilities. Objectives and results of the four contributions to the project for the reporting period are presented. (R.P.) 5 refs., 4 figs., 1 tab
10. Mangifera indica as Bioindicator of Mercury Atmospheric Contamination in an ASGM Area in North Gorontalo Regency, Indonesia
OpenAIRE
Hendra Prasetia; Masayuki Sakakibara; Koji Omori; Jamie S. Laird; Koichiro Sera; Idham A. Kurniawan
2018-01-01
We report the atmospheric Hg contamination in an artisanal and small-scale gold mining (ASGM) area in North Gorontalo, Indonesia. It is well known that atmospheric Hg contaminates the air, water, soil, and living organisms, including trees. In this study, we calculated total weight of heavy metals, especially Hg, and quantitatively measure the concentrations of heavy metals, especially Hg, in tree bark from an ASGM area. Tree bark can be used for the environmental assessment of atmospheric co...
11. CdTe as a passivating layer in CdTe/HgCdTe heterostructures
International Nuclear Information System (INIS)
Virt, I. S.; Kurilo, I. V.; Rudyi, I. A.; Sizov, F. F.; Mikhailov, N. N.; Smirnov, R. N.
2008-01-01
CdTe/Hg 1-x Cd x Te heterostructures are studied. In the structures, CdTe is used as a passivating layer deposited as a polycrystal or single crystal on a single-crystal Hg 1-x Cd x Te film. The film and a passivating layer were obtained in a single technological process of molecular beam epitaxy. The structure of passivating layers was studied by reflection high-energy electron diffraction, and the effect of the structure of the passivating layer on the properties of the active layer was studied by X-ray diffractometry. Mechanical properties of heterostructures were studied by the microhardness method. Electrical and photoelectrical parameters of the Hg 1-x Cd x Te films are reported.
12. Quadrupole moments of the 12+ isomers in 188Hg and 190Hg
International Nuclear Information System (INIS)
Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.
1984-01-01
The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)
13. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA
Science.gov (United States)
Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.
2013-01-01
Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load
14. Export of Atmospheric Mercury from East Asia Observed at Various Monitoring Sites in Taiwan
Science.gov (United States)
Sheu, G.; Lin, N.; Wang, J.; Lee, C.; Chang, S.
2009-12-01
East Asia is the major atmospheric mercury (Hg) source region in the world due to the excessive coal combustion, industrial emission, and biomass burning in this area. Nonetheless, studies concerning the export of atmospheric Hg from East Asia are still limited. Accordingly, atmospheric Hg has been measured at various sites in Taiwan to study its temporal and spatial distribution, and the significance of long-range transport from the East Asian continent as well. Here we report the data collected in Fu-guei-jiao (121.97°E, 25.47°N, ~30 m a.s.l.), Mt. Bamboo (121.54°E, 25.19°N, 1025 m a.s.l.), and Lulin Atmospheric Background Station (LABS; 120.87°E, 23.47°N, 2862 m a.s.l.) to discuss the atmospheric Hg export from the East Asian continent. Twenty-four hour-integrated total atmospheric Hg (THg) samples were manually collected in Fu-guei-jiao and Mt. Bamboo in 2007-2008 and quantified by dual amalgamation CVAFS. On the other hand, continuous measurements of gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particulate Hg (PHg) at LABS began since April 13, 2006 using the Tekran 2537A/1130/1135 speciation system. Mean(±S.D.) THg concentrations were 2.09±0.71 and 1.86±0.50 ng m-3 for Fu-guei-jiao and Mt. Bamboo, respectively. At LABS between April 2006 and April 2009, the mean(±S.D.) concentrations of GEM, RGM and PHg were 1.77±0.54 ng m-3, 22.4±43.8 pg m-3 and 6.3±10.9 pg m-3, respectively. Evident seasonal distribution in THg/GEM concentrations was observed at all sites with higher values usually occurred between fall and spring when the air masses were mainly from the East Asian continent, indicating the influence of the East Asian atmospheric Hg outflow. This also demonstrated that the atmospheric Hg export is occurring both in the boundary layer and in the free troposphere. Concentrations of PHg were usually low at LABS; however, elevated values were detected in spring when the Indochina Peninsula biomass burning plumes frequently affected
15. Mercury biogeochemical cycling in the ocean and policy implications.
Science.gov (United States)
Mason, Robert P; Choi, Anna L; Fitzgerald, William F; Hammerschmidt, Chad R; Lamborg, Carl H; Soerensen, Anne L; Sunderland, Elsie M
2012-11-01
Anthropogenic activities have enriched mercury in the biosphere by at least a factor of three, leading to increases in total mercury (Hg) in the surface ocean. However, the impacts on ocean fish and associated trends in human exposure as a result of such changes are less clear. Here we review our understanding of global mass budgets for both inorganic and methylated Hg species in ocean seawater. We consider external inputs from atmospheric deposition and rivers as well as internal production of monomethylmercury (CH₃Hg) and dimethylmercury ((CH₃)₂Hg). Impacts of large-scale ocean circulation and vertical transport processes on Hg distribution throughout the water column and how this influences bioaccumulation into ocean food chains are also discussed. Our analysis suggests that while atmospheric deposition is the main source of inorganic Hg to open ocean systems, most of the CH₃Hg accumulating in ocean fish is derived from in situ production within the upper waters (ocean basins are changing at different rates due to differences in atmospheric loading and that the deeper waters of the oceans are responding slowly to changes in atmospheric Hg inputs. Most biological exposures occur in the upper ocean and therefore should respond over years to decades to changes in atmospheric mercury inputs achieved by regulatory control strategies. Migratory pelagic fish such as tuna and swordfish are an important component of CH₃Hg exposure for many human populations and therefore any reduction in anthropogenic releases of Hg and associated deposition to the ocean will result in a decline in human exposure and risk. Copyright © 2012 Elsevier Inc. All rights reserved.
16. Projecting Soil Feedbacks to Atmospheric CO2 Following Erosion and Deposition on Centennial Timescales in Two Contrasting Forests: A Study of Critical Zone-Atmosphere Exchange
Science.gov (United States)
Billings, S. A.; Richter, D., Jr.; Ziegler, S. E.; Prestegaard, K. L.
2016-12-01
For almost 20 y there has been a growing recognition that erosion and associated lateral movement of SOC does not necessarily result in a net CO2 source from terrestrial sources to the atmosphere. Eroded SOC may undergo mineralization to CO2 at a more rapid pace than it would have in situ, but the eroding ecosystem continues to generate SOC at a potentially modified rate, and the eroding profile may also experience changing SOC mineralization rates. No one knows how these process rates may change upon erosion. Years ago, we introduced a model that computes the influence of erosion on biosphere-atmosphere CO2 exchange for any profile of interest. The model permits the user to test how assumptions of changing SOC production and mineralization can influence the degree to which erosion induces a net CO2 sink or source. Here we present an analogous model depicting how deposition of eroded SOC also can result in altered biosphere-atmosphere CO2 exchange. We employ both models to investigate how erosion and deposition in two contrasting forested regions may influence regional C budgets. Runoff-induced erosion in a boreal forest occurs at low rates, but removes C-rich, organic material; anthropogenically-enhanced erosion in a warm temperate forest removed both O- and mineral-rich A-horizons. Model runs (100 y) suggest that even though the great volume of mineral soil eroded from the temperate forest was relatively low-SOC, high erosion rates prompted greater potential for erosion to serve as a net CO2 sink compared to the boreal forest where C-rich material was lost but erosion rates remained low. The models further suggest that changes in SOC production and mineralization at eroding sites in both forest types are a greater influence on CO2 source or sink strength than analogous changes at depositional sites. The fate of eroded material and the influence of erosion and deposition on SOC dynamics remain knowledge gaps critical for projecting atmospheric CO2.
17. Tracing aquatic bioavailable Hg in three different regions of China using fish Hg isotopes.
Science.gov (United States)
Liu, Cheng-Bin; Hua, Xiu-Bing; Liu, Hong-Wei; Yu, Ben; Mao, Yu-Xiang; Wang, Ding-Yong; Yin, Yong-Guang; Hu, Li-Gang; Shi, Jian-Bo; Jiang, Gui-Bin
2018-04-15
To trace the most concerned bioavailable mercury (Hg) in aquatic environment, fish samples were collected from three typical regions in China, including 3 rivers and 1 lake in the Tibetan Plateau (TP, a high altitude background region with strong solar radiation), the Three Gorges Reservoir (TGR, the largest artificial freshwater reservoir in China), and the Chinese Bohai Sea (CBS, a heavily human-impacted semi-enclosed sea). The Hg isotopic compositions in fish muscles were analyzed. The results showed that anthropogenic emissions were the main sources of Hg in fish from TGR and CBS because of the observed negative δ 202 Hg and positive Δ 199 Hg in these two regions (TGR, δ 202 Hg: - 0.72 to - 0.29‰, Δ 199 Hg: 0.15 - 0.52‰; CBS, δ 202 Hg: - 2.09 to - 0.86‰, Δ 199 Hg: 0.07 - 0.52‰). The relatively higher δ 202 Hg and Δ 199 Hg (δ 202 Hg: - 0.37 - 0.08‰, Δ 199 Hg: 0.50 - 1.89‰) in fish from TP suggested the insignificant disturbance from local anthropogenic activities. The larger slopes of Δ 199 Hg/Δ 201 Hg in fish from TGR (1.29 ± 0.14, 1SD) and TP (1.25 ± 0.06, 1SD) indicated methylmercury (MeHg) was produced and photo-reduced in the water column before incorporation into the fish. In contrast, the photoreduction of Hg 2+ was the main process in CBS (slope of Δ 199 Hg/Δ 201 Hg: 1.06 ± 0.06, 1SD). According to the fingerprint data of Hg isotopes, the most important source for aquatic bioavailable Hg in TP should be the long-range transported Hg, contrasting to the anthropogenic originated MeHg from surface sediments and runoffs in TGR and inorganic Hg from continental inputs in CBS. Therefore, the isotopic signatures of Hg in fish can provide novel clues in tracing sources and behaviors of bioavailable Hg in aquatic systems, which are critical for further understanding the biogeochemical cycling of Hg. Copyright © 2017 Elsevier Inc. All rights reserved.
18. Further promotion of the use of mosses and lichens for studies of atmospheric deposition of trace elements
International Nuclear Information System (INIS)
Steinnes, Eiliv
2001-01-01
Some recent and ongoing studies related to the use of mosses as biomonitors of atmospheric metal deposition are briefly reviewed. Issues discussed in particular are the conversion of concentration in moss to absolute deposition values, introduction of a second-generation ICP-MS instrument for moss analysis, determination of stable lead isotope ratios in mosses for source apportionment, and temporal trends of lead and cadmium deposition in Norway. A novel nuclear technique for the determination of fluorine in mosses surrounding an aluminium smelter is presented. (author)
19. Emission, transport, deposition, and re-suspension of radionuclides from Fukushima Dai-ichi Nuclear Power Plant in the atmosphere - Overview of 2-year investigations in Japan
Science.gov (United States)
Kita, Kazuyuki; Igarashi, Yasuhiro; Yoshida, Naohiro; Nakajima, Teruyuki
2013-04-01
20. A heavy metal atmospheric deposition study in the South Ural mountains
International Nuclear Information System (INIS)
Frontas'eva, M.V.; Smirnov, L.I.; Steinnes, E.; Lyapunov, S.M.; Cherchintsev, V.D.
2002-01-01
Samples of the mosses Hylocomium splendens and Pleurozium schreberi, collected in the summer of 1998, were used to study the atmospheric deposition of heavy metals and other toxic elements in the Chelyabinsk Region situated in the South Ural, one of the most heavily poluted industrial areas of the Russian Federation. Samples of natural soils were collected simultaneously with moss at the same 30 sites in order to investigate surface accumulation of heavy metals and to examine the correlation of elements in moss and soil samples in order to separate contributions from atmospheric deposition and from soil minerals. A total of 38 elements (Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Rb, Sr, Zr, Mo, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Hf, Tf, W, Au, Th, U) in soil and 33 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, Ba, La, Ce, Sm, Tb, Yb, Hf, Ta, W, Au, Th, U) in mosses were determined by epithermal neutron activation analysis, The elements Cu, Cd and Pb (in moss samples only) were obtained by atomic absorption spectrometry. The element concentrations were compared to those for copper basins in Poland and Serbia as well as to baseline concentrations in Norway. VARIMAX rotated principal component analysis was used to identify and characterise different pollution sources and to point out the most polluted areas
1. Using Simple Science to Influence Corporate Responsibility—A Lesson from Mercury (Hg)
Science.gov (United States)
Filippelli, G. M.
2016-12-01
Mercury (Hg) is a powerful neurotoxin with wide environmental distribution. Typical population exposure to Hg comes from fish consumption, with fish being the final ecological endpoint of Hg magnification after a series of biogeochemical processes. The emission of Hg from coal-fired power plants has been strongly implicated as a key source of environmental Hg, and thus the target for various public policy initiatives in the US and abroad. We conducted a study of Hg distribution in surface soils over a broad area of central Indiana (US) to understand the major sources of Hg to local fish, and to assess the potential role of policy compliance in reducing Hg. We found a plume-like distribution pattern for soil Hg, with values exceeding 400 ppb Hg in the heart of the plume, and reducing to background concentration of about 30 ppb outside of the plume. The plume covered hundreds of square kilometers, was centered directly over the downtown area of Indianapolis (a city of roughly 1 million inhabitants), and could be roughly backtracked to a source in the southwest corner of the city, coincident with a large coal-fired utility plant that has the highest reported emissions of Hg in the area. Evidence of this link between a local source of Hg and net Hg deposition, with related implications for Hg runoff to local stream, biomagnification to fish, and fish consumption advisories was reported in regional newspapers and eventually published in scientific journals. But importantly, these findings were used by an NGO (the Beyond Coal campaign by Indiana branch of the Sierra Club) at a critical time to influence a decision by the owner of the power plant of whether to comply with the Hg policy rule by either adding higher technology scrubbing technologies to the plant or simply to convert the plant over to natural gas as the fuel source (a costlier choice upfront). The utility chose the latter option, and with the permanent elimination of Hg emissions, the net measurable effects
2. Potassium limits potential growth of bog vegetation under elevated atmospheric CO2 and N deposition
NARCIS (Netherlands)
Hoosbeek, M.R.; Breemen, van N.; Vasander, H.; Buttlers, A.; Berendse, F.
2002-01-01
The free air carbon dioxide enrichment (FACE) and N deposition experiments on four ombrotrophic bogs in Finland, Sweden, the Netherlands and Switzerland, revealed that after three years of treatment: (1) elevated atmospheric CO2 concentration had no significant effect on the biomass growth of
3. Long-term atmospheric wet deposition of dissolved organic nitrogen in a typical red-soil agro-ecosystem, Southeastern China.
Science.gov (United States)
Cui, Jian; Zhou, Jing; Peng, Ying; He, Yuan Q; Yang, Hao; Xu, Liang J; Chan, Andy
2014-05-01
Dissolved organic nitrogen (DON) from atmospheric deposition has been a growing concern in the world and atmospheric nitrogen (N) deposition is increasing quickly in China especially Southeastern China. In our study, DON wet deposition was estimated by collecting and analyzing rainwater samples continuously over eight years (2005-2012) in a typical red-soil farmland ecosystem, Southeast China. Results showed that the volume-weighted-average DON concentration varied from 0.2 to 3.3 mg N L(-1) with an average of 1.2 mg N L(-1). DON flux ranged from 5.7 to 71.6 kg N ha(-1) year(-1) and averaged 19.7 kg N ha(-1) year(-1) which accounted for 34.6% of the total dissolved nitrogen (TDN) in wet deposition during the eight-year period. Analysis of DON concentration and flux, contribution of DON to TDN, rainfall, rain frequency, air temperature and wind frequency and the application of pig manure revealed possible pollution sources. Significant positive linear relation of annual DON flux and usage of pig manure (Pcycle in the red-soil agro-ecosystem in the future.
4. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe
Energy Technology Data Exchange (ETDEWEB)
Harmens, H., E-mail: hh@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Norris, D.A., E-mail: danor@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Cooper, D.M., E-mail: cooper@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, G., E-mail: gmi@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Steinnes, E., E-mail: Eiliv.Steinnes@chem.ntnu.no [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Kubin, E., E-mail: Eero.Kubin@metla.fi [Finnish Forest Research Institute, Kirkkosaarentie 7, 91500 Muhos (Finland); Thoeni, L., E-mail: lotti.thoeni@fub-ag.ch [FUB-Research Group for Environmental Monitoring, Alte Jonastrasse 83, 8640 Rapperswil (Switzerland); Aboal, J.R., E-mail: jesusramon.aboal@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Alber, R., E-mail: Renate.Alber@provinz.bz.it [Environmental Agency of Bolzano, 39055 Laives (Italy); Carballeira, A., E-mail: alejo.carballeira@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Coskun, M., E-mail: coskunafm@yahoo.com [Canakkale Onsekiz Mart University, Faculty of Medicine, Department of Medical Biology, 17100 Canakkale (Turkey); De Temmerman, L., E-mail: ludet@var.fgov.be [Veterinary and Agrochemical Research Centre, Tervuren (Belgium); Frolova, M., E-mail: marina.frolova@lvgma.gov.lv [Latvian Environment, Geology and Meteorology Agency, Riga (Latvia); Gonzalez-Miqueo, L., E-mail: lgonzale2@alumni.unav.es [Univ. of Navarra, Irunlarrea No 1, 31008 Pamplona (Spain)
2011-10-15
In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations ({>=}1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r{sup 2} = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: > Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. > Moss concentrations were compared with EMEP modelled nitrogen deposition. > The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha{sup -1} y{sup -1}. > Linear relationships were found with measured nitrogen deposition in some countries. > Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.
5. Equilibrium mercury isotope fractionation between dissolved Hg(II) species and thiol-bound Hg
NARCIS (Netherlands)
Wiederhold, Jan G.; Cramer, Christopher J.; Daniel, Kelly; Infante, Ivan; Bourdon, Bernard; Kretzschmar, Ruben
2010-01-01
Stable Hg isotope ratios provide a new tool to trace environmental Hg cycling. Thiols (-SH) are the dominant Hg-binding groups in natural organic matter. Here, we report experimental and computational results on equilibrium Hg isotope fractionation between dissolved Hg(II) species and thiol-bound
6. Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet
Energy Technology Data Exchange (ETDEWEB)
2016-10-01
Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH{sub 4}{sup +} in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7 ng L{sup −1}, with an average of 12.5 ng L{sup −1}. The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH{sub 4}{sup +}. The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. - Highlights: • The low pH/high electronic conductivity was found in atmospheric water vapor. • Anthropogenic NH{sub 4}{sup +} was higher than that determined in precipitation of Lhasa. • Elevated Hg and major ions levels were usually associated with weak acidic samples. • Hg in atmospheric water vapor was largely influenced by transboundary transport. • Below-cloud scavenging accounted for most Hg in precipitation.
7. Influence of long-range transboundary transport on atmospheric water vapor mercury collected at the largest city of Tibet
International Nuclear Information System (INIS)
Huang, Jie; Kang, Shichang; Tian, Lide; Guo, Junming; Zhang, Qianggong; Cong, Zhiyuan; Sillanpää, Mika
2016-01-01
Monsoon circulation is an important process that affects long-range transboundary transport of anthropogenic contaminants such as mercury (Hg). During the Indian monsoon season of 2013, a total of 92 and 26 atmospheric water vapor samples were collected at Lhasa, the largest city of the Tibet, for Hg and major ions analysis, respectively. The relatively low pH/high electronic conductivity values, together with the fact that NH_4"+ in atmospheric water vapor was even higher than that determined in precipitation of Lhasa, indicated the effects of anthropogenic perturbations through long-range transboundary atmospheric transport. Concentrations of Hg in atmospheric water vapor ranged from 2.5 to 73.7 ng L"−"1, with an average of 12.5 ng L"−"1. The elevated Hg and major ions concentrations, and electronic conductivity values were generally associated with weak acidic samples, and Hg mainly loaded with anthropogenic ions such as NH_4"+. The results of principal component analysis and trajectory analysis suggested that anthropogenic emissions from the Indian subcontinent may have largely contributed to the determined Hg in atmospheric water vapor. Furthermore, our study reconfirmed that below-cloud scavenging contribution was significant for precipitation Hg in Lhasa, and evaluated that on average 74.1% of the Hg in precipitation could be accounted for by below-cloud scavenging. - Highlights: • The low pH/high electronic conductivity was found in atmospheric water vapor. • Anthropogenic NH_4"+ was higher than that determined in precipitation of Lhasa. • Elevated Hg and major ions levels were usually associated with weak acidic samples. • Hg in atmospheric water vapor was largely influenced by transboundary transport. • Below-cloud scavenging accounted for most Hg in precipitation.
8. Depositional characteristics of atmospheric polybrominated diphenyl ethers on tree barks
Directory of Open Access Journals (Sweden)
Man Young Chun
2014-07-01
Full Text Available Objectives This study was conducted to determine the depositional characteristics of several tree barks, including Ginkgo (Ginkgo biloba, Pine (Pinus densiflora, Platanus (Platanus, and Metasequoia (Metasequoia glyptostroboides. These were used as passive air sampler (PAS of atmospheric polybrominated diphenyl ethers (PBDEs. Methods Tree barks were sampled from the same site. PBDEs were analyzed by highresolution gas chromatography/high-resolution mass spectrometer, and the lipid content was measured using the gravimetric method by n-hexane extraction. Results Gingko contained the highest lipid content (7.82 mg/g dry, whereas pine (4.85 mg/g dry, Platanus (3.61 mg/g dry, and Metasequoia (0.97 mg/g dry had relatively lower content. The highest total PBDEs concentration was observed in Metasequoia (83,159.0 pg/g dry, followed by Ginkgo (53,538.4 pg/g dry, Pine (20,266.4 pg/g dry, and Platanus (12,572.0 pg/g dry. There were poor correlations between lipid content and total PBDE concentrations in tree barks (R2=0.1011, p =0.682. Among the PBDE congeners, BDE 206, 207 and 209 were highly brominated PBDEs that are sorbed to particulates in ambient air, which accounted for 90.5% (84.3-95.6% of the concentration and were therefore identified as the main PBDE congener. The concentrations of particulate PBDEs deposited on tree barks were dependent on morphological characteristics such as surface area or roughness of barks. Conclusions Therefore, when using the tree barks as the PAS of the atmospheric PBDEs, samples belonging to same tree species should be collected to reduce errors and to obtain reliable data.
9. 46 CFR 53.10-3 - Inspection and tests (modifies HG-500 through HG-540).
Science.gov (United States)
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false Inspection and tests (modifies HG-500 through HG-540... tests (modifies HG-500 through HG-540). (a) The inspections required by HG-500 through HG-540 must be performed by the “Authorized Inspector” as defined in HG-515 of section IV of the ASME Boiler and Pressure...
10. Mercury in precipitation over the coastal zone of the southern Baltic Sea, Poland.
Science.gov (United States)
Siudek, Patrycja; Falkowska, Lucyna; Brodecka, Aleksandra; Kowalski, Artur; Frankowski, Marcin; Siepak, Jerzy
2015-02-01
An investigation of atmospheric mercury was conducted in the urban coastal zone of the Gulf of Gdansk (Baltic Sea, Poland) in 2008. Rainwater samples were collected in bulk samplers and Hg concentration was determined using AAS method. Total mercury concentration ranged from 1.9 to 14.8 ng l(-1) (the mean was 8.3 ng l(-1) with standard deviation ±3.7), out of which about 34 % were water-soluble Hg(II) forms. Distribution of Hg species in rainwater was related to both the emission source and the atmospheric processes. During the sampling period, two maxima of Hg concentration in precipitation were observed: the first in the cold season and the second one in the warm season. Elevated concentrations of Hg in wintertime precipitation were generally the result of local urban atmospheric emission connected with the following anthropogenic sources: intensive combustion of fossil fuels in domestic furnaces, individual power/heat generating plants, and motor vehicles. During summertime, Hg° re-emitted from contaminated land and sea surfaces was photochemically oxidized by active atmospheric substances (e.g., hydroxyl radicals, hydrogen peroxide, halogens) and could be an additional source of atmospherically deposited Hg. The results presented in this work indicate that rainwater Hg concentration and deposition values are not much higher in comparison with other urban locations along the Baltic Sea basin and other coastal cities. However, the elevated mercury concentration in rainwater and, consequently, higher deposition ratio could appear occasionally as an effect of intensive anthropogenic emissions (domestic heating) and/or photochemical reactions.
11. Atmospheric deposition and surface stratification as controls of contrasting chlorophyll abundance in the North Indian Ocean
Digital Repository Service at National Institute of Oceanography (India)
Patra, P.K.; DileepKumar, M.; Mahowald, N.; Sarma, V.V.S.S.
Intense upwelling during summer and convection in winter are believed to drive higher biological productivity in the Arabian Sea than in the Bay of Bengal. Although the Arabian Sea receives substantial atmospheric deposition of dust aerosols, its...
12. Lattice defects in semiconducting Hg/1-x/Cd/x/Te alloys. I - Defect structure of undoped and copper doped Hg/0.8/Cd/0.2/Te. II - Defect structure of indium-doped Hg/0.8/Cd/0.2/Te
Science.gov (United States)
Vydyanath, H. R.
1981-01-01
Hall effect and mobility measurements were conducted on undoped Hg(0.8)Cd(0.2)Te crystals which were quenched to room temperature after being subjected to equilibration at temperatures ranging from 400 to 655 C in various Hg atmospheres. The variation of the hole concentration in the cooled crystals at 77 K as a function of Hg's partial pressure at the equilibration temperature, together with a comparison of the hole mobility in the undoped samples with that in copper-doped ones, yields a defect model for the undoped crystals according to which they are intrinsic at the equilibration temperatures and the native acceptor defects are doubly ionized. In the second part of this paper, the effects of indium doping are considered. The concentration of electrons obtained in the cooled crystals was found to be lower than the intrinsic carrier concentration at the equilibration temperatures. A defect model is proposed according to which most of the indium is incorporated as In2Te3(s) dissolved in the crystal, with only a small fraction of indium acting as single donors occupying Hg lattice sites.
13. Factors Controlling the Distribution of Atmospheric Mercury in the East Asian Free Troposphere
Science.gov (United States)
Sheu, G.; Lee, C.; Lin, N.; Wang, J.; Ouyang, C.
2008-12-01
Taiwan is located to the downwind side of both East and Southeast Asia, which are the major anthropogenic mercury (Hg) source region worldwide. Also, it has been suggested that mountain-top monitoring sites, which are frequently in the free troposphere, are essential to the understanding of the global Hg transport. Accordingly, continuous measurements of atmospheric Hg have been conducting at Lulin Atmospheric Background Station (LABS, 2862 m a.s.l.) in Taiwan since April 13, 2006 to study the trans-boundary transport and transformation of Hg in the free troposphere. Three types of atmospheric Hg, including gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particulate Hg (PHg), are measured using the Tekran 2537A/1130/1135 speciation system. Diurnal variations in the concentrations of GEM, RGM, ozone, and water vapor (WV) mixing ratio indicated the influence of boundary layer air in daytime and the subsidence of free tropospheric air masses from higher altitudes at night. Seasonal variation in GEM concentrations was evident with elevated concentrations usually observed between fall and spring when air masses were more or less under the influence of Asian continent. Low summer GEM values were associated with marine air masses. Spikes of RGM were frequently detected between midnight and early morning with concurrent decreases in GEM and WV mixing ratio and increases in ozone concentrations, suggesting the oxidation of GEM and formation of RGM in free troposphere. Concentrations of PHg were usually low; however, elevated concentrations were detected in spring when the Southeast Asian biomass burning plumes affected the LABS. Analysis of the collected data indicate that at LABS the distribution of atmospheric Hg is dynamically controlled by background atmosphere, exchange and mixing of free troposphere/boundary layer air, chemical transformation, and long-range transport from East and Southeast Asia.
14. Characterization of atmospheric deposition and runoff water on a small suburban catchment
OpenAIRE
LAMPREA, Diana Katerine; RUBAN, Véronique
2011-01-01
A study of air quality and atmospheric deposition on a small urban catchment (Pin Sec catchment) has been carried out in Nantes, France, in 2007 and 2008 in the frame of a federative project aimed at understanding the origin of pollution in urban environments. Carbon monoxide, nitrogen monoxide, nitrogen dioxide, ozone, sulphur dioxide and particles less than 10 µm (PM 10) were monitored for air quality, whereas heavy metals, Polycyclic aromatic hydrocarbons (PAHs) and pesticides were analyze...
15. Simple and green synthesis of piperazine-grafted reduced graphene oxide and its application for the detection of Hg(II)
Science.gov (United States)
Zuo, Yinxiu; Xu, Jingkun; Xing, Huakun; Duan, Xuemin; Lu, Limin; Ye, Guo; Jia, Haiyan; Yu, Yongfang
2018-04-01
In this paper, piperazine-grafted reduced graphene oxide (NH-rGO) was synthesized via a simple and green two-step procedure: (i) opening of the resulting epoxides of graphene oxide (GO) with piperazine (NH) through nucleophilic substitution; (ii) reduction of GO with ascorbic acid. Its structure and morphology were characterized by scanning electron microscopy and x-ray photoelectron spectroscopy. The NH-rGO modified glassy carbon electrode was explored as an electrochemical sensor for the determination of Hg(II) using a differential pulse anodic stripping voltammetry technique. Hg(II) can be efficiently accumulated and deposited on the surface of a modified electrode by strong coordination chemical bonds formed between Hg(II) and NH. And then the anodic stripping current can be significantly enhanced by rGO with the merits of large specific surface area and high conductivity, which served as a signal amplifier, finally realizing the highly sensitive determination of Hg(II). The experimental parameters including the pH value of the acetate buffer, deposition potential and deposition time were optimized. Under optimal conditions, the developed sensor exhibited a wide linear range from 0.4-12 000 nM with a low limit of detection of 0.2 nM, which is well below the guideline value in drinking water set by the WHO. Moreover, the practical application of this method was confirmed by an assay of Hg(II) in tap water samples with acceptable results.
16. An Artificial Turf-Based Surrogate Surface Collector for the Direct Measurement of Atmospheric Mercury Dry Deposition
Directory of Open Access Journals (Sweden)
Naima L. Hall
2017-02-01
Full Text Available This paper describes the development of a new artificial turf surrogate surface (ATSS sampler for use in the measurement of mercury (Hg dry deposition. In contrast to many existing surrogate surface designs, the ATSS utilizes a three-dimensional deposition surface that may more closely mimic the physical structure of many natural surfaces than traditional flat surrogate surface designs (water, filter, greased Mylar film. The ATSS has been designed to overcome several complicating factors that can impact the integrity of samples with other direct measurement approaches by providing a passive system which can be deployed for both short and extended periods of time (days to weeks, and is not contaminated by precipitation and/or invalidated by strong winds. Performance characteristics including collocated precision, in-field procedural and laboratory blanks were evaluated. The results of these performance evaluations included a mean collocated precision of 9%, low blanks (0.8 ng, high extraction efficiency (97%–103%, and a quantitative matrix spike recovery (100%.
17. Mercury isotope constraints on the source for sediment-hosted lead-zinc deposits in the Changdu area, southwestern China
Science.gov (United States)
Xu, Chunxia; Yin, Runsheng; Peng, Jiantang; Hurley, James P.; Lepak, Ryan F.; Gao, Jianfeng; Feng, Xinbin; Hu, Ruizhong; Bi, Xianwu
2018-03-01
The Lanuoma and Cuona sediment-hosted Pb-Zn deposits hosted by Upper Triassic limestone and sandstone, respectively, are located in the Changdu area, SW China. Mercury concentrations and Hg isotopic compositions from sulfide minerals and potential source rocks (e.g., the host sedimentary rocks and the metamorphic basement) were investigated to constrain metal sources and mineralization processes. In both deposits, sulfide minerals have higher mercury (Hg) concentrations (0.35 to 1185 ppm) than the metamorphic basement rocks (0.05 to 0.15 ppm) and sedimentary rocks (0.02 to 0.08 ppm). Large variations of mass-dependent fractionation (3.3‰ in δ202Hg) and mass-independent fractionation (0.3‰ in Δ199Hg) of Hg isotopes were observed. Sulfide minerals have Hg isotope signatures that are similar to the hydrothermal altered rocks around the deposit, and similar to the metamorphic basement, but different from barren sedimentary rocks. The variation of Δ199Hg suggests that Hg in sulfides was mainly derived from the underlying metamorphic basement. Mercury isotopes could be a geochemical tracer in understanding metal sources in hydrothermal ore deposits.
18. A fluvial mercury budget for Lake Ontario.
Science.gov (United States)
Denkenberger, Joseph S; Driscoll, Charles T; Mason, Edward; Branfireun, Brian; Warnock, Ashley
2014-06-03
Watershed mercury (Hg) flux was calculated for ten inflowing rivers and the outlet for Lake Ontario using empirical measurements from two independent field-sampling programs. Total Hg (THg) flux for nine study watersheds that directly drain into the lake ranged from 0.2 kg/yr to 13 kg/yr, with the dominant fluvial THg load from the Niagara River at 154 kg/yr. THg loss at the outlet (St. Lawrence River) was 68 kg/yr and has declined approximately 40% over the past decade. Fluvial Hg inputs largely (62%) occur in the dissolved fraction and are similar to estimates of atmospheric Hg inputs. Fluvial mass balances suggest strong in-lake retention of particulate Hg inputs (99%), compared to dissolved total Hg (45%) and methyl Hg (22%) fractions. Wetland land cover is a good predictor of methyl Hg yield for Lake Ontario watersheds. Sediment deposition studies, coupled atmospheric and fluvial Hg fluxes, and a comparison of this work with previous measurements indicate that Lake Ontario is a net sink of Hg inputs and not at steady state likely because of recent decreases in point source inputs and atmospheric Hg deposition.
19. Expanding atmospheric acid deposition in China from the 1990s to the 2010s
Science.gov (United States)
Yu, Haili; Wang, Qiufeng
2017-04-01
Atmospheric acid deposition is considered a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to be more serious with the country's economic development and increasing consumption of fossil fuels in recent decades. By collecting nationwide data on pH and concentrations of sulfate (SO42-) and nitrate (NO3-) in precipitation between 1980 and 2014 in China, we explored the spatiotemporal variations of precipitation acid deposition (bulk deposition) and their influencing factors. Our results showed that average precipitation pH values were 4.86 and 4.84 in the 1990s and 2010s, respectively. This suggests that precipitation acid deposition in China has not seriously changes. Average SO42- deposition declined from 30.73 to 28.61 kg S ha-1 yr-1 but average NO3- deposition increased from 4.02 to 6.79 kg N ha-1 yr-1. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of decreasing pollutant emissions, whereas the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Significant positive correlations have been found between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and reduce pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6849889159202576, "perplexity": 9147.719718395088}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662587158.57/warc/CC-MAIN-20220525120449-20220525150449-00015.warc.gz"} |
https://people.csail.mit.edu/sbangaru/projects/teg-2021/index.html | # Systematically Differentiating Parametric Discontinuities
### ACM SIGGRAPH 2021
Jesse Michel*
MIT CSAIL
Kevin Mu
MIT CSAIL
Gilbert Bernstein
UC Berkeley and
MIT CSAIL
Tzu-Mao Li
MIT CSAIL
### Abstract
Emerging research in computer graphics, inverse problems, and machine learning requires us to differentiate and optimize parametric discontinuities. These discontinuities appear in object boundaries, occlusion, contact, and sudden change over time. In many domains, such as rendering and physics simulation, we differentiate the parameters of models that are expressed as integrals over discontinuous functions. Ignoring the discontinuities during differentiation often has a significant impact on the optimization process. Previous approaches either apply specialized hand-derived solutions, smooth out the discontinuities, or rely on incorrect automatic differentiation.
We propose a systematic approach to differentiating integrals with discontinuous integrands, by developing a new differentiable programming language. We introduce integration as a language primitive and account for the Dirac delta contribution from differentiating parametric discontinuities in the integrand. We formally define the language semantics and prove the correctness and closure under the differentiation, allowing the generation of gradients and higher-order derivatives. We also build a system, \textsc{Teg}, implementing these semantics. Our approach is widely applicable to a variety of tasks, including image stylization, fitting shader parameters, trajectory optimization, and optimizing physical designs. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8006826043128967, "perplexity": 1961.716943570451}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243991370.50/warc/CC-MAIN-20210515131024-20210515161024-00491.warc.gz"} |
http://export.arxiv.org/abs/2002.04737 | math.AG
(what is this?)
# Title: Projective rational manifolds with non-finitely generated discrete automorphism group and infinitely many real forms
Abstract: We show, among other things, that for each integer $n \ge 3$, there is a smooth complex projective rational variety of dimension $n$, with discrete non-finitely generated automorphism group and with infinitely many mutually non-isomorphic real forms. Our result is inspired by the work of Lesieutre and the work of Dinh and Oguiso.
Comments: 13 pages, no figure Subjects: Algebraic Geometry (math.AG) Cite as: arXiv:2002.04737 [math.AG] (or arXiv:2002.04737v1 [math.AG] for this version)
## Submission history
From: Keiji Oguiso [view email]
[v1] Tue, 11 Feb 2020 23:57:45 GMT (14kb)
Link back to: arXiv, form interface, contact. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.20285473763942719, "perplexity": 2436.8150419416343}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600400202418.22/warc/CC-MAIN-20200929154729-20200929184729-00500.warc.gz"} |
https://www.maa.org/press/periodicals/convergence/a-classic-from-china-the-nine-chapters-introduction-and-history | # A Classic from China: The Nine Chapters - Introduction and History
Author(s):
Randy K. Schwartz (Schoolcraft College)
##### Introduction
This article is about the most important mathematical work in China’s long history, the Jiuzhang Suanshu (“Nine Chapters on the Art of Calculation”). The book was used throughout China for centuries, and it also circulated in Korea and Japan, influencing mathematics there. The author(s) and date(s) of the original work are no longer known, but clues in the text—including the units used in story problems—indicate that it was probably written shortly after 200 BCE. The original version of the Nine Chapters presented rules and algorithms but without formal proof or derivation. Later, in the year 263 CE, the mathematician Liu Hui provided a written commentary that included justification for the techniques used.
China, a large region with an immensely long history, has played a big role in many spheres of culture. In mathematics and other sciences, China has also played an advanced world role. This is not a new development. In fact, the Needham Research Institute in Cambridge, England, has been working for decades to summarize the rich history of China’s contributions to science and technology. So far, the summary occupies over 20 large published volumes; volume 3 is on mathematics. (Editor's note: As of 2018, the series consists of 27 volumes, the most recent one published in 2015.)
Looking over portions of the Nine Chapters, and solving some of the story problems in it, is a good way to see how the development of mathematics in Asia was shaped by how life and society were organized there. Life in the West and in the East have had similarities and differences, so we can expect that the mathematics of these two cultures will also have some similarities and some differences.
In subsequent sections of this article, I’ll provide some background about the book and then present 10 story problems from it. I challenge you, the reader, to solve as many of the problems as you can. All 10 problems are drawn from the edited translation by Shen Kangshen, et al. (1999).
Above: The opening page of Sankei kyusho, a book from Edo-period Japan (1603-1867) that is modeled after The Nine Chapters (in fact, the Japanese word kyusho means “nine chapters”). The author and date of the book are unknown. (Source: Mathematical Treasure: The Chinese Nine Chapters in Japan, MAA Convergence)
##### The Nine Chapters versus Euclid's Elements
Of the works considered China’s Ten Mathematical Classics, the Nine Chapters is the oldest and the most influential. Like Euclid’s Elements in the West, it was used as a basic textbook for mathematics from ancient times all the way to 1600 CE and even later.
Comparing these two works, we can’t help but notice some differences between the roots of Eastern and Western mathematics:
• The Nine Chapters was focused more on practical problem-solving than on theory. It is a how-to manual consisting of 246 exemplary problems and their solutions. After a few problems of a given type were solved, the general method of solution was summarized. By contrast, the Elements was a rigorous development of the structure of geometry and some related fields, with theorems built up in a careful manner from a foundation consisting of basic “elements” (axioms and postulates). The style of the Nine Chapters was inductive; the Elements, deductive.
• In ancient times, Asians were far more adept at arithmetic and computation than were Westerners. The Nine Chapters used decimal place-value arithmetic at a time when Europeans were still using Roman numerals or other cumbersome systems. The ancient Chinese were also the first of the two to use negative numbers, a practice not adopted in Europe until the 1400’s. The Chinese word for mathematics, suanshu, that appears in the title of the Nine Chapters, literally means “the art of calculation”.
• The study of prime numbers, factorization, and other topics in number theory, which was an important part of the Elements and of ancient Greek mathematics, does not seem to have been taken up in traditional Chinese mathematics. For example, in China the greatest common divisor of two numbers was found not by factoring, but by a process of repeated subtraction that was also described by Euclid.
• Centuries before other peoples, the Chinese developed algorithms for solving linear problems, including matrix methods and techniques of excess and deficit.
##### The Nine Chapters of the Jiuzhang Suanshu
Just how much Chinese mathematics was rooted in practical problem-solving is reflected in the nine chapter subjects of the Jiuzhang Suanshu. The chapters correspond to the nine arithmetical arts of Chinese tradition:
Chapter 1 “Field Measurement”—calculating the areas of various shapes of farming plots such as triangles, rectangles, and circles (using an accurate approximation of $\pi$), plus arithmetical rules for fractions and greatest common divisors.
This page illustrates a Chinese version of the exhaustion method for approximating $\pi,$ based on regular polygons inscribed in or circumscribed around a circle. It appears in a sixteenth-century version of Liu Hui’s third-century edition and commentary on the Nine Chapters, in which he obtained a $\pi$ approximation of 3.14024. (Source: Mathematical Treasures - Jiuzhang suanshu, MAA Convergence)
Chapter 2 “Millet and Rice”—using ratios and proportions in the commercial exchange of different kinds of grains and other products.
Chapter 3 “Distribution by Proportion”—subdividing quantities by direct, inverse, or compound proportion, plus a discussion of arithmetic and geometric progressions.
Chapter 4 “What Width?”—calculating an unknown dimension of a rectangle or rectangular solid if the area or volume is known, including how to find reciprocals, square roots, and cube roots of various types of numbers.
Chapter 5 “Construction Consultations”—finding the areas and volumes of shapes and solids used in designing buildings and other structures.
Chapter 6 “Fair Levies”—proportionally distributing wages and taxes, continuing Chapter 3.
Chapter 7 “Excess and Deficit”—solving linear equations with arithmetical algorithms and without algebra.
Chapter 8 “Rectangular Grids”—using matrices to solve simultaneous linear equations.
Chapter 9 “Right Triangles”—solving practical geometric problems using properties of right triangles, and quadratic equations by an adaptation of the square-root algorithm.
For centuries, the Nine Chapters was used to train civil servants in the prestigious imperial bureaucracy. This was consistent with Chinese philosophical traditions, in which intellectuals were supposed to use their skills to benefit society in practical ways. For example, a line of hereditary state officials called chouren was specifically charged with “reading the heavens” (studying astronomy) and doing the calculations needed to make calendars, which were so important in this agrarian society. The chouren’s routine need for various kinds of approximations stimulated the development of algorithms that utilized fractional and signed numbers. The word chouren came to mean both “astronomers” and “mathematicians” (Lĭ and Dù, pp. 22-24, 32, 48-49, 232).
Randy K. Schwartz (Schoolcraft College), "A Classic from China: The Nine Chapters - Introduction and History," Convergence (December 2018) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5175835490226746, "perplexity": 1788.4700252447929}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623487630518.38/warc/CC-MAIN-20210617162149-20210617192149-00166.warc.gz"} |
https://jkcs.or.kr/journal/view.php?number=3833 | J. Korean Ceram. Soc. > Volume 30(9); 1993 > Article
Journal of the Korean Ceramic Society 1993;30(9): 761.
$CeO_2$을 첨가한 $Pb(Mg, Te, Mn, Nb)O_3-PZT$계 세라믹스의 물리적 성질과 압전트랜스의 출력특성 박순태, 정수태1, 이종헌2 부산전문대학 전자과1부산공업대학교 전자공학과2동아대학교 전자공학과 Physical Properties and Out-put Characteristics of Piezoelectric Transformer of $Pb(Mg, Te, Mn, Nb)O_3-PZT$ Ceramics with Addition of $CeO_2$ ABSTRACT Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/$textrm{cm}^2$) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.
TOOLS | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3270343840122223, "perplexity": 15715.120637927075}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623488286726.71/warc/CC-MAIN-20210621151134-20210621181134-00363.warc.gz"} |
https://stats.stackexchange.com/questions/235498/how-can-bootstrap-be-used-to-establish-confidence-intervals-for-theil-regression | # How can bootstrap be used to establish confidence intervals for Theil regression parameters?
In References for methods for calculating the confidence interval for Theil-Sen Estimator, we note that Wilcox (1998, 2009?) proposed the use of bootstrap as a method for finding confidence intervals for Theil regression of heteroscedastic conditions. There is a practical problem doing this and that is the treatment of ties. That is, since bootstrap is sampling with replacement, it is probable to eventually sample the same point twice leading to an indeterminate slope pair. Thus, we need to either discard indeterminate results or use something else, for example a variant of leave n/2 out.
Q1: How do we resolve the indeterminate bootstrap problem for Theil regression?
Possible answers: Heretofore unspecified correction for ties. Incomplete Jackknife of n/2 samples (e.g., I have 412 samples, leave out 206 cannot be completely re-sampled as the combination of 412 samples taken 206 at a time is a geological time to completion answer competitive with the age of the universe on my pc. Moreover, leave one out would not be very useful for establishing confidence intervals).
BTW, leave half out appears to work +/- circa 7% on Monte-Carlo simulation of my data. However, that is a far cry from proving that the leave half out approach is valid.
Any clarification would be welcome.
• I am not familiar with the basic Theil-Sen estimator algorithm in practice, but Wikipedia says essentially "Theil = median slope $\Delta y/\Delta x$ over all pairs of sample points", while "Sen = median over all pairs of sample points with $\Delta x \neq 0$". So the bootstrap part of the question seems un-needed to encounter the basic problem (actually, since neither description says distinct points, the Sen version could still have this difficulty). Generalizing Sen would just assign 0 weight to point-pairs with the same point. – GeoMatt22 Sep 17 '16 at 17:53
• @GeoMatt Sen makes undesirable assumptions concerning the distribution of slopes that I believe to be not useful in the majority of cases, including mine. Sen uses all distinct pairs of sample points, but bootstrap has to have replacement of points without uniqueness to be usable. – Carl Sep 17 '16 at 18:41
• @GeoMatt Indeed, it would seem that the problems with the Sen estimator is what led Wilcox to propose bootstrap in 1998. – Carl Sep 17 '16 at 18:57
• If you have whatever procedure that allows you to compute a single realization of the estimator, then that procedure will take a median over some empirical distribution of pairs of points. So why not just do bootstrap resampling on that point-pairs PDF? (vs. drawing each point of a pair independently). In other words you bootstrap the PDF of slopes. – GeoMatt22 Sep 17 '16 at 21:22
• Anyway, I am not clear on what the underlying "model" for Theil-Sen regression is. For what it's worth, if I care about robustness, I will typically just use a robust residual norm (e.g. an M-estimator). If I care about "errors in variables", I will typically use TLS. For both, I'd probably do RANSAC, but if I needed a well-defined parametric model, I'd probably do a combo, using "TLS" with a robust norm. – GeoMatt22 Sep 17 '16 at 21:48 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6260525584220886, "perplexity": 1186.490741428739}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560628000414.26/warc/CC-MAIN-20190626174622-20190626200622-00279.warc.gz"} |
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# Guy's net income equals his gross income minus his deduction
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Guy's net income equals his gross income minus his deduction [#permalink] 01 Oct 2012, 04:25
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Guy's net income equals his gross income minus his deductions. By what percent did Guy's net income change on January 1, 1989, when both his gross income and his deductions increased?
(1) Guy's gross income increased by 4 percent on January 1, 1989.
(2) Guy's deductions increased by 15 percent on January 1, 1989.
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 01 Oct 2012, 04:26
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SOLUTION
Guy's net income equals his gross income minus his deductions. By what percent did Guy's net income change on January 1, 1989, when both his gross income and his deductions increased?
Given: Net Income = Gross Income - Deductions.
(1) Guy's gross income increased by 4 percent on January 1, 1989. No info about deductions. Not sufficient.
(2) Guy's deductions increased by 15 percent on January 1, 1989. No info about gross income. Not sufficient.
(1)+(2) If Gross Income=100 and Deductions=100, then Guy had decrease in Net Income (since Deductions increased by greater percent than Gross Income) BUT if Gross Income=1,000 and Deductions=100, then Guy had some increase in Net Income. So, we cannot get the percent by which Guy's net income changed on January 1, 1989. Not sufficient.
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 01 Oct 2012, 05:45
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N.Income = G.Income - Deductions
lets say ni= gi -d
from 1 gi => 1.04 gi doesnot take abt Deductions so not sufficient
from 2 d => 1.15 d doesnot take abt Gross income so not sufficient
from 1 and 2
new net income = 1.04 gi - 1.15 d
Using thsi we still cant find the % change in Net income so E
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 01 Oct 2012, 19:04
1) No info about Deduction - Insufficient
2) No info about Gross income - Insufficient
1+2) New Income = 1.04 G + 1.15 D
New Income will vary for different relative values of Gross Income & Deductions - Insufficient
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 04 Oct 2012, 14:09
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SOLUTION
Guy's net income equals his gross income minus his deductions. By what percent did Guy's net income change on January 1, 1989, when both his gross income and his deductions increased?
Given: Net Income = Gross Income - Deductions.
(1) Guy's gross income increased by 4 percent on January 1, 1989. No info about deductions. Not sufficient.
(2) Guy's deductions increased by 15 percent on January 1, 1989. No info about gross income. Not sufficient.
(1)+(2) If Gross Income=100 and Deductions=100, then Guy had decrease in Net Income (since Deductions increased by greater percent than Gross Income) BUT if Gross Income=1,000 and Deductions=100, then Guy had some increase in Net Income. So, we cannot get the percent by which Guy's net income changed on January 1, 1989. Not sufficient.
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 04 Oct 2012, 16:27
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I like those kind of questions because are almost pure logic without to stay too much thinking about numbers.
$$NI = net income$$
$$GI = gross income$$
$$Ded= deduction$$
$$NI = GI - Ded$$
1) we have only GI
2) we have only Ded
Both are insuff
Now is the most abstract part that you have to understand very carefully: if GI increase by 4% and Ded by 15% if we do not have a clear anchor point: GI even with a small variation could be larger than Ded so we could have a NI BUT if we have the reverse situation we would not have NI because the Ded could be larger than GI and the latter would disappear without to establish with security NI
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 05 Jun 2013, 10:44
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I have a question:
If the problem provided with a Gross and Deduction ratio, then the correct answer would have been be C?
Since we are looking for a percent change, it doesn't matter actual values, right?
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 06 Jun 2013, 01:00
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marcovg4 wrote:
I have a question:
If the problem provided with a Gross and Deduction ratio, then the correct answer would have been be C?
Since we are looking for a percent change, it doesn't matter actual values, right?
Yes, you are right.
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Re: Guy's net income equals his gross income minus his deduction [#permalink] 04 May 2014, 07:57
Bunuel wrote:
marcovg4 wrote:
I have a question:
If the problem provided with a Gross and Deduction ratio, then the correct answer would have been be C?
Since we are looking for a percent change, it doesn't matter actual values, right?
Yes, you are right.
Hi Bunuel,
I came here to ask the same question, although I was expecting a different answer.
If we have an original ratio of Gross/Deduc, and they gave us the adjusted Gross/Deduc -- that would just mean that we have a new ratio for Gross/Deduc, correct?
If we compare the two ratios, don't we just get a old net/new net? Without knowing the anchor points, how can we still classify that as a change, wouldn't it instead just be a ratio? Meaning, a ratio of new/old could be 5/4, so the new net could be 100 and the old could be 80. Using the same theory, it could also be 200/160. The dollar amount has a much bigger change in the second example?
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Guy's net income equals his gross income minus his deduction [#permalink] 04 Nov 2014, 12:13
russ9 wrote:
Bunuel wrote:
marcovg4 wrote:
I have a question:
If the problem provided with a Gross and Deduction ratio, then the correct answer would have been be C?
Since we are looking for a percent change, it doesn't matter actual values, right?
Yes, you are right.
Hi Bunuel,
I came here to ask the same question, although I was expecting a different answer.
If we have an original ratio of Gross/Deduc, and they gave us the adjusted Gross/Deduc -- that would just mean that we have a new ratio for Gross/Deduc, correct?
If we compare the two ratios, don't we just get a old net/new net? Without knowing the anchor points, how can we still classify that as a change, wouldn't it instead just be a ratio? Meaning, a ratio of new/old could be 5/4, so the new net could be 100 and the old could be 80. Using the same theory, it could also be 200/160. The dollar amount has a much bigger change in the second example?
BUMP.
Suppose, original ratio is given as Gr:De = 100 : 80 .....[Also, assuming it as smart number]
Then, 1+2) New Gr : De = 1.04*100 : 1.15*80 => 104 : 92
New NI = 12
Old NI = 20
We get (12-20)/20 = -8/20 = 40 percent decrease.
The NI is supposed to increase and but due to the higher De percentage, NI decreased. Is it sufficient or not?
...or am I lost?
Update 1: NI can increase/decrease because the questions says what percent NI change.
Guy's net income equals his gross income minus his deduction [#permalink] 04 Nov 2014, 12:13
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https://homework.cpm.org/category/MN/textbook/cc1mn/chapter/10/lesson/10.1.1/problem/10-8 | ### Home > CC1MN > Chapter 10 > Lesson 10.1.1 > Problem10-8
10-8.
On your paper, sketch the algebra tile shape shown at right. Write expressions for the area and perimeter of the shape. Then calculate the area and perimeter of the shape for each $x\text{-value}$.
Add the areas of all six tiles to find the shape's total area.
Area: $3x+3$
Add the lengths of all the sides of the shape to find the perimeter.
Try labeling all the sides first.
Perimeter: $2x+10$
1. $x=9$ cm
Substitute $9$ cm for $x$ in each expression.
$A=3(9)+3$
$P=2(9)+10$
Use the Order of Operations to simplify and calculate the answer.
$A=30$ sq cm
$P=28$ cm
2. $x=0.5$ cm Hint: Draw a diagram. Does your perimeter expression work?
$A=4.5$ sq cm
$P=14$ cm
3. $x=15$ cm
See part (a). | {"extraction_info": {"found_math": true, "script_math_tex": 14, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6758161783218384, "perplexity": 1976.2954550542993}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764499654.54/warc/CC-MAIN-20230128184907-20230128214907-00185.warc.gz"} |
https://www.physicsforums.com/threads/high-school-cyclotron.238046/ | # High School Cyclotron
1. May 31, 2008
### anisotropyx
Hi, my name is Peter Heuer, I am a high school student and an avid reader of physics forums :)
I have been working with two friends over the last year and a half to build a small cyclotron to enter in a science fair. We have completed our design but are having trouble funding the project.
We have created a website here with more information, this can be found by goggling "cyclotron kids"
If anyone has any ideas on how to fund such a project or comments on the idea in general, please let me know!
The website has an email at which I can be contacted.
Thanks!
2. May 31, 2008
### eys_physics
Hey
Sounds like a very interesting and ambitious project. To get founding is maybe one of the greatest for scientific projects today. There are plenty of ideas but not always money ...
I have unfournately no help to give you but I wish you good luck with the project and hope that you can find founding for it in some way.
3. May 31, 2008
Staff Emeritus
I hate to be a wet blanket, but I believe your device is inherently unsafe, undercosted, and may not actually work.
Safety: I see no mention of any sort of interlock. You need a design so that you cannot open anything you shouldn't with the system energized. (And if you do, the system automatically shuts off)
Also, you argue that you use AWG14 wire because its rated for 15 amps, and your design is for 14 amps with 10% ripple. Not only does this provide only a 7% margin, once you put your 10% ripple on it, you are now driving it beyond its specs.
My table says for power transmission, you need AWG10 (without any ripple); AWG14 is only good to 6 amps.
You say that heat is not a problem - without calculations. That's not convincing.
Finally, you have selected an energy high enough for nuclear processes to occur. So how do you know you haven't activated any of your equipment? And if it is activated, how do you plan on disposing of this radioactive waste?
Cost: In real life, projects need "contingency" - what do you do if the price of copper goes up? Or you discover you need AWG10 wire after you started making coils of AWG14? No large project - from home repair to building a cyclotron - is immune.
As an example, how do you plan to get the iron in the right shape? How do you plan to move and stack it? (Safely) This may well cost money.
Will it work? You don't say how big your magnet is, but given that your box is 34 x 39 cm, I used that. 6000 turns is just over 28,000 feet. That means the coils have a resistance of about 70 ohms, which means you need about 1000 V to get your 14 A. You don't have that with your setup.
Going to AWG9 will solve this problem, but of course it will increase your copper cost by a factor of 4, which will increase your cost by $4000 or so. (See the above on contingency) I think you would be better off building a smaller cyclotron. The original Lawrence one fit in the palm of your hand. 4. May 31, 2008 ### anisotropyx Let me answer each of those questions at a time: "I see no mention of any sort of interlock. You need a design so that you cannot open anything you shouldn't with the system energized. (And if you do, the system automatically shuts off)" Because of time constraints, our entire safety system was not "prettied up" for the grant proposal and website. We do, however, have a design for a number of safety systems along this line. All of the electrical systems of the cyclotron will be in an enclosed space that is locked during operation (but still well ventilated by a system of fans. The system will also have a number of easy-access and automatic "fuse" systems that will shut down systems such as the magnets if overheating occurs or the hydrogen source if the vacuum level starts to fall. "Also, you argue that you use AWG14 wire because its rated for 15 amps, and your design is for 14 amps with 10% ripple. Not only does this provide only a 7% margin, once you put your 10% ripple on it, you are now driving it beyond its specs. My table says for power transmission, you need AWG10 (without any ripple); AWG14 is only good to 6 amps. You say that heat is not a problem - without calculations. That's not convincing." Again another item that was no covered explicitly in the online documents for time reasons (though I believe it was mentioned) is the cooling system for the magnets. There will be a system of copper tubing bringing cooled water over the coils at all times. In addition, we will only be running the cyclotron for short periods - a few seconds at a time - so magnet heating will be minimal anyway. These two considerations make the AWG14 wire safe. "Finally, you have selected an energy high enough for nuclear processes to occur. So how do you know you haven't activated any of your equipment? And if it is activated, how do you plan on disposing of this radioactive waste?" At all times the radiation level near the cyclotron will be measured and the machine will be turned off if any hazard is realized. Cyclotrons operating at much higher energy levels then ours (see the Rutgers link on our website) have had no problem with radiation and thus we don't expect to have any either. However, we have designed a a lead-covered box that the cyclotron will be placed in to minimize even this small chance. "Cost: In real life, projects need "contingency" - what do you do if the price of copper goes up? Or you discover you need AWG10 wire after you started making coils of AWG14? No large project - from home repair to building a cyclotron - is immune." This is true. However, this is an issue any project must deal with. We have had our design inspected by several physicists, all of which offered suggestions but also seemed to think it would work. "As an example, how do you plan to get the iron in the right shape? How do you plan to move and stack it? (Safely) This may well cost money." Our cyclotron was designed with this in mind. We have access to a machining shop and have obtained the skills/help to do what we need to. The yoke was planned in such a way that it can be assembled fairly easily on-site; no piece weighs more than 90lbs and they can all be put together with simple bolts. Again these designs are not online, if you are interested I can email them to you. "You don't say how big your magnet is, but given that your box is 34 x 39 cm, I used that. 6000 turns is just over 28,000 feet. That means the coils have a resistance of about 70 ohms, which means you need about 1000 V to get your 14 A. You don't have that with your setup." We have run through these equations multiple times; the results are on our web page. Our system uses 240V wall current through a large transformer to provide the watts we need. If an unexpected problem occurs, we can also change the windings on the transformer fairly easily to adapt this design to different amperages. "The original Lawrence one fit in the palm of your hand." The issue with the original cyclotron is that it did hardly anything besides prove that it worked. This was our original plan, however we soon realized that in order to justify the costs of the project we needed to make a cyclotron that could actually perform experiments outside of the area of cyclotron resonance. I hope that answered your questions. There is more information on all these systems in "draft" form that have not been scanned, however summaries of most of them are on the design document on our web page. 5. May 31, 2008 ### Vanadium 50 Staff Emeritus I still don't see an interlock system. Look at it this way. A cyclotron designed by professionals and operated by professionals has an interlock system. Should a cyclotron designed and operated by amateurs be designed with less safety in mind? You also argue that you won't operate it unsafely. To my mind, this isn't good enough - you need to design a system that cannot be operated unsafely. For example, if you think that the magnet should only be operated for a few seconds, put a timer on it so it automatically shuts off. You mention that you didn't have the time to put some of this on the web - I think you can't afford not to. Nobody is going to put money or resources towards getting three kids killed, so it's to your advantage to have a well-designed safety system and to publish the details. It's up to you to convince your potential donors that this won't happen. As far as prompt radiation, you have to tell me how much is "too much", how you are going to detect it, whether the response is manual or automatic, and so on. But I am more worried about activation - having the beam make some part of the cyclotron radioactive. Even if you immediately shut off the beam, it's too late. "The other guys didn't have a problem" is not a particularly compelling answer to a safety-related question. As far as your magnet, I don't see a drawing of it or a table of its properties. I can't tell how much wire you need. The best I was able to do was to figure out how much wire you are buying from the weight and density of copper, and that's 12000 feet. So I was off by a factor of ~2 (not bad, considering there's no drawing). That's 30 ohms, and to support 14 A requires 420 V. Your transformer only gives 340 V. You say that that you've done these calculations multiple times - fine. Put them on the web site. Including this particular calculation. Changing the windings won't help. You've designed a 6 kW magnet (before losses - it's probably closer to 7 with losses), and it's ultimately getting plugged into a 4.8 kW source. You also have a problem with operating it for just a few seconds at a time. I don't know what the inductance is - 300 H maybe? 300 H and 30 ohms gives you a time constant of 10 seconds. That means it will take ~45 seconds just to get the magnet to full (99%) power - and another 45 seconds to bring it back to zero. You also didn't address the fact that your own design (14 A + 10% ripple) exceeds what you say is the safe current limit for this wire. Even if you ignore my arguments for thicker wire, your own numbers say you're exceeding the safe current limit. 6. May 31, 2008 ### anisotropyx The first mistake you are making continually is to assume that the complete design is on the website. Again, due to time constraints we have not made presentable circuit diagrams/descriptions of the interlock systems. Our "potential donors" are getting different information. Many of our tech drawings for the chamber/magnet design do not scan well; we send potential donors copies by mail. You should understand that the website is made with the average person in mind, not a scientist. Thus we have tried to keep most of the complicated stuff in our actual funding proposals. I'm not sure how you are arriving with 30 ohms, I believe our calculations yielded 21 ohms which, although close, is possible. It is true that inductance is large, however we are confident that the cooling system will work. Even if it does not, it is not a safety hazard; all it will do is trip the automatic shut down system. I would like to see the table you are citing. However, the information on Fred Neill's website (a previous high school cyclotron builder) agrees with our numbers. He made, in fact, a fairly similar, if smaller magnet. At the level of 1.35 MeV, 7. May 31, 2008 ### Vanadium 50 Staff Emeritus Hey, I can only go by what you've posted, here and the site. If what's on the site is wrong or incomplete, you should fix it. For example, you've said 14 amperes average, you've said 10% ripple and you've said 15 amperes is the safe limit. Using your numbers and only your numbers, I get that your current exceeds your limit. Which number is wrong? 14? 15? Or 10? 8. May 31, 2008 ### anisotropyx Both numbers are correct. The 15 amp safety limit is meant for every-day appliances etc. like household wiring. Since our system is cooled, insulated with enamel instead of thick plastic and running for a matter of seconds at peak, we can stretch that number a little bit. By the way, the magnets will be turned on slowly so that they can "warm up" at least part of the way below the max. current. 9. May 31, 2008 ### Vanadium 50 Staff Emeritus Deciding that you don't have to follow the safety limits on a piece of equipment - even something as simple as a piece of wire - is very dangerous. Accidents happen not because people do things they think are dangerous. They happen because people do things they think are safe - but aren't. Since it's clear your mind is made up, and that you won't take any safety commentary seriously (even by someone who has been doing accelerator physics experiments for the last 20 years), I guess all I can say is, "Good luck, be careful, and I hope you don't kill yourselves." 10. May 31, 2008 ### anisotropyx I'm not sure why you think I won't take advice, I've been double checking my numbers and tables for the last half hour. I am still interested in seeing a link/copy of the table you are citing for your numbers. Although I remain convinced that a cooled magnet can safely exceed the recommended running temperature for cold wire (for what other reason would you cool it?) I would be much more worried if your 6 Amp figure was applicable. If the temperature switch flips, we can simply run the magnets on a lower current. The overall output particle velocity will of course be lowered but I would prefer that than to not build the accelerator at all (12AWG wire is vastly more expensive.) 11. Jun 1, 2008 ### Vanadium 50 Staff Emeritus One more question - have you acquired a license to operate such an accelerator in your state? While I am not a lawyer, it appears that the threshold in both New York and Maryland is 1 MeV. (Other states have different thresholds: I believe it's 100 keV for Pennsylvania) 12. Jun 1, 2008 ### bkelly You might consider a test with just the magnet and coils. Apply the power you expect, make temperature, voltage and current measurements over time. Chart the results, and see what you get. You may wish to apply cooling and run a test. Test or not you will probably want the ability to monitor muliple sensors at a rapid rate and record the data. Implementing that at an early stage would probably be benificial. 13. Jun 1, 2008 ### kts123 Posting your full designs and calculations would probably make potential donors more apt to give you money. Personally I've been terrified of radiation of any sorts since I turned on a microwave with the door open (my dad had it in his appliance work shop -- I was little, and didn't realize he had bypassed the door saftey switch!) So just the idea of "being possible to operate unsaftely," scares me. Safety first! Anyway, but, you know, a few big donations is one thing, but many small ones can be just as effective. You're kinda snubbing out smaller donors by not having your information up. And one other thing... have you thought about FedEx/Kinko's? I've been there a couple of times for special prints, I recall seeing a jumbo scanner linked to their computer network. 14. Jun 1, 2008 ### anisotropyx 1. We were unable to find any such legal restriction in our search, if you find anything PLEASE send it to us. We have determined that we seem to be safe legally in at least the radiation laws, however since none of us are lawyers it is possible we may have missed something. 2. We will DEFINITLY test the magnets and all other systems before they are used with the actual cyclotron. I should also stress that THE INTERLOCK WILL DISABLE THE MAGNETS/HV SOURCE IF THE ELECTRONICS LOCKER IS OPENED. This will prevent accidents from happening. 3. If you look, most of our information IS up, all that isn't are the scans of our tech drawings since they are not very good quality and can not be read easily without zooming in a lot. Kinkos was the first place we looked, however those scanners have a HUGE price (like$5 per square foot) for the output, making our total costs for that over \$60 for something we could simply describe.
15. Jun 1, 2008
Staff Emeritus
You can find links to the various state rules http://http://nrc-stp.ornl.gov/rulemaking.html" [Broken].
For Maryland, the appropriate law appears to be the Code of Maryland Regulations 26.12.01.01
Last edited by a moderator: May 3, 2017
16. Jun 1, 2008
### anisotropyx
Thank you very much, I will look into that now.
I want to let you know that, after checking the math and considering we have decided that AWG 12 wire would be a better choice. Thank you for your information.
17. Jun 1, 2008
### anisotropyx
A search of the that legislation seems to read that that limit only applies to those devices that are being used in "the healing arts"
18. Jun 2, 2008
Staff Emeritus
This is why it's worth spending some time and getting professional assistance in dealing with these laws. (Which may include writing a letter to the appropriate state agency, it may involve getting in touch with some local university's RSO, and it may even require a lawyer).
The key seems to be Sec. I2: "No person shall receive, possess, use, transfer, own, or acquire a particle accelerator except as authorized in a registration issued pursuant to Part B of these regulations"
Exemptions (Part B) are: "(a) Electronic equipment that produces radiation incidental to its operation for other purposes is exempt from the registration and notification requirements of this Part, provided that the dose equivalent rate averaged over an area of 10 square centimeters does not exceed 5 μSv (0.5 millirem) per hour at 5 centimeters from any accessible surface of such equipment. The production, testing, or factory servicing of such equipment shall not be exempt. (b) Radiation machines while in transit or storage incident thereto are exempt from the requirements of this Part. (c) Domestic television receivers are exempt from the requirements of this Part."
That said, the only license form I saw was probably the one you found. However, I also suspect that most requests are from hospitals or their service providers. Not people wanting to build accelerators in their basements.
While I am not a regulator, I can't imagine that you will be held to a lower standard than a professionally constructed and operated accelerator, so I think you should be prepared for that.
19. Jun 2, 2008
### anisotropyx
Nor would we want to to, I'd rather have to change our design to comply with laws then be fried.
We have discussed hiring a lawyer, at least for a consultation, but we were concerned that your average lawyer would no nothing about these somewhat obscure rules. Do you have any idea how to go about finding one that would know the laws in this area?
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https://eng.libretexts.org/Bookshelves/Materials_Science/TLP_Library_II/Chapter_3/3.a10%3A_Summary | # 3.10: Summary
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• Liquid crystals are characterised by their high orientational and low positional molecular order.
• Molecules capable of forming liquid crystals are always anisotropic – typically they will be calamitic (rod-shaped).
• There are three types of calamitic liquid crystal: nematic, smectic and chiral nematic. They are defined by their differing degrees of positional order.
• The degree of orientational order of a liquid crystal can be quantified using the $\text { order parameter } Q=\left(3\left\langle\cos ^{2} \theta\right\rangle-1\right) / 2$orderparameterQ=(3cos2θ1)/2
• Defects in liquid crystals are given the name disclinations. Each type of disclination is assigned a positive or negative number; the magnitude indicates its strength whilst the sign indicates which disclinations can cancel each other out.
• Disclinations can be viewed directly by polarised light microscopy. For example, in a nematic they appear as schlieren brushes.
• Liquid crystals also exhibit birefringence when viewed through crossed polars.
• The most common modern commercial use of liquid crystals is in liquid crystal displays.
## Going further
#### Books
• Peter J. Collings & Michael Hird, Introduction to Liquid Crystals: Chemistry and Physics, Taylor & Francis, 1997.
• Peter J. Collings, Liquid Crystals: Nature’s Delicate Phase of Matter, 2nd Edition, Princeton University Press, 2002.
#### Websites
• Liquid Crystals: a Simple View on a Complex Matter
A presentation covering the different liquid crystalline mesophases and their appearance under polarised light microscopy.
• PLC Virtual Textbook
Contains an introduction to liquid crystals and their phase transitions, including virtual experiments.
• The Basics About Liquid Crystals
A tutorial created by the Liquid Crystal and Photonics Group of Ghent University, Belgium.
• Liquid Crystal Disclinations Seen Through Cross-Polars
A simulation of the movement of schlieren brushes for different types of disclination in a nematic liquid crystal.
• Introduction to Anisotropy
A DoITPoMS TLP describing the anisotropy found in liquid crystals and other materials in further detail.
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http://composingprograms.com/pages/43-declarative-programming.html | ## 4.3 Declarative Programming
In addition to streams, data values are often stored in large repositories called databases. A database consists of a data store containing structured data values and an interface for retrieving subsets of the data based on their characteristics. Each value stored in a database is called a record. Records are typically retrieved via a query, which is an expression in a query programming language. By far the most ubiquitous query language in use today is called Structured Query Language or SQL (pronounced "sequel").
SQL is an example of a declarative programming language. Expressions do not describe computations directly, but instead state the form of the result of some computation. It is the role of the query interpreter of the database system to design and perform a computational process to produce such a result.
This interaction differs substantially from the procedural programming paradigm of Python or Scheme. In Python, computational processes are described directly by the programmer. A declarative language specifies the form of the result, but abstracts away procedural details.
In this section, we introduce a declarative query language called logic, designed specifically for this text. It is based upon Prolog and the declarative language in Structure and Interpretation of Computer Programs. Data records are expressed as Scheme lists, and queries are expressed as Scheme values. The logic is a complete implementation that depends upon the Scheme project of the previous chapter.
### 4.3.1 Facts and Queries
Databases store records that represent facts in the system. The purpose of the query interpreter is to retrieve collections of facts drawn directly from database records, as well as to deduce new facts from the database using logical inference. A fact statement in the logic language consists of one or more lists following the keyword fact. A simple fact is a single list. A dog breeder with an interest in U.S. Presidents might record the genealogy of her collection of dogs using the logic language as follows:
logic> (fact (parent abraham barack))
logic> (fact (parent abraham clinton))
logic> (fact (parent delano herbert))
logic> (fact (parent fillmore abraham))
logic> (fact (parent fillmore delano))
logic> (fact (parent fillmore grover))
logic> (fact (parent eisenhower fillmore))
Each fact is not a procedure application, as in a Scheme expression, but instead a relation that is declared. "The dog Abraham is the parent of Barack," declares the first fact. Relation types do not need to be defined in advance. Relations are not applied, but instead matched to queries.
A query also consists of one or more lists, but begins with the keyword query. A query may contain variables, which are symbols that begin with a question mark. Variables are matched to facts by the query interpreter:
logic> (query (parent abraham ?child))
Success!
child: barack
child: clinton
The query interpreter responds with Success! to indicate that the query matches some fact. The following lines show substitutions of the variable ?child that match the query to the facts in the database.
Compound facts. Facts may also contain variables as well as multiple sub-expressions. A multi-expression fact begins with a conclusion, followed by hypotheses. For the conclusion to be true, all of the hypotheses must be satisfied:
(fact <conclusion> <hypothesis0> <hypothesis1> ... <hypothesisN>)
For example, facts about children can be declared based on the facts about parents already in the database:
logic> (fact (child ?c ?p) (parent ?p ?c))
The fact above can be read as: "?c is the child of ?p, provided that ?p is the parent of ?c." A query can now refer to this fact:
logic> (query (child ?child fillmore))
Success!
child: abraham
child: delano
child: grover
The query above requires the query interpreter to combine the fact that defines child with the various parent facts about fillmore. The user of the language does not need to know how this information is combined, but only that the result has a particular form. It is up to the query interpreter to prove that (child abraham fillmore) is true, given the available facts.
A query is not required to include variables; it may simply verify a fact:
logic> (query (child herbert delano))
Success!
A query that does not match any facts will return failure:
logic> (query (child eisenhower ?parent))
Failure.
### 4.3.2 Recursive Facts
The logic language also allows recursive facts. That is, the conclusion of a fact may depend upon a hypothesis that contains the same symbols. For instance, the ancestor relation is defined with two facts. Some ?a is an ancestor of ?y if it is a parent of ?y or if it is the parent of an ancestor of ?y:
logic> (fact (ancestor ?a ?y) (parent ?a ?y))
logic> (fact (ancestor ?a ?y) (parent ?a ?z) (ancestor ?z ?y))
A single query can then list all ancestors of herbert:
logic> (query (ancestor ?a herbert))
Success!
a: delano
a: fillmore
a: eisenhower
Compound queries. A query may have multiple subexpressions, in which case all must be satisfied simultaneously by an assignment of symbols to variables. If a variable appears more than once in a query, then it must take the same value in each context. The following query finds ancestors of both herbert and barack:
logic> (query (ancestor ?a barack) (ancestor ?a herbert))
Success!
a: fillmore
a: eisenhower
Recursive facts may require long chains of inference to match queries to existing facts in a database. For instance, to prove the fact (ancestor fillmore herbert), we must prove each of the following facts in succession:
(parent delano herbert) ; (1), a simple fact
(ancestor delano herbert) ; (2), from (1) and the 1st ancestor fact
(parent fillmore delano) ; (3), a simple fact
(ancestor fillmore herbert) ; (4), from (2), (3), & the 2nd ancestor fact
In this way, a single fact can imply a large number of additional facts, or even infinitely many, as long as the query interpreter is able to discover them.
Hierarchical facts. Thus far, each fact and query expression has been a list of symbols. In addition, fact and query lists can contain lists, providing a way to represent hierarchical data. The color of each dog may be stored along with the name an additional record:
logic> (fact (dog (name abraham) (color white)))
logic> (fact (dog (name barack) (color tan)))
logic> (fact (dog (name clinton) (color white)))
logic> (fact (dog (name delano) (color white)))
logic> (fact (dog (name eisenhower) (color tan)))
logic> (fact (dog (name fillmore) (color brown)))
logic> (fact (dog (name grover) (color tan)))
logic> (fact (dog (name herbert) (color brown)))
Queries can articulate the full structure of hierarchical facts, or they can match variables to whole lists:
logic> (query (dog (name clinton) (color ?color)))
Success!
color: white
logic> (query (dog (name clinton) ?info))
Success!
info: (color white)
Much of the power of a database lies in the ability of the query interpreter to join together multiple kinds of facts in a single query. The following query finds all pairs of dogs for which one is the ancestor of the other and they share a color:
logic> (query (dog (name ?name) (color ?color))
(ancestor ?ancestor ?name)
(dog (name ?ancestor) (color ?color)))
Success!
name: barack color: tan ancestor: eisenhower
name: clinton color: white ancestor: abraham
name: grover color: tan ancestor: eisenhower
name: herbert color: brown ancestor: fillmore
Variables can refer to lists in hierarchical records, but also using dot notation. A variable following a dot matches the rest of the list of a fact. Dotted lists can appear in either facts or queries. The following example constructs pedigrees of dogs by listing their chain of ancestry. Young barack follows a venerable line of presidential pups:
logic> (fact (pedigree ?name) (dog (name ?name) . ?details))
logic> (fact (pedigree ?child ?parent . ?rest)
(parent ?parent ?child)
(pedigree ?parent . ?rest))
logic> (query (pedigree barack . ?lineage))
Success!
lineage: ()
lineage: (abraham)
lineage: (abraham fillmore)
lineage: (abraham fillmore eisenhower)
Declarative or logical programming can express relationships among facts with remarkable efficiency. For example, if we wish to express that two lists can append to form a longer list with the elements of the first, followed by the elements of the second, we state two rules. First, a base case declares that appending an empty list to any list gives that list:
logic> (fact (append-to-form () ?x ?x))
Second, a recursive fact declares that a list with first element ?a and rest ?r appends to a list ?y to form a list with first element ?a and some appended rest ?z. For this relation to hold, it must be the case that ?r and ?y append to form ?z:
logic> (fact (append-to-form (?a . ?r) ?y (?a . ?z)) (append-to-form ?r ?y ?z))
Using these two facts, the query interpreter can compute the result of appending any two lists together:
logic> (query (append-to-form (a b c) (d e) ?result))
Success!
result: (a b c d e)
In addition, it can compute all possible pairs of lists ?left and ?right that can append to form the list (a b c d e):
logic> (query (append-to-form ?left ?right (a b c d e)))
Success!
left: () right: (a b c d e)
left: (a) right: (b c d e)
left: (a b) right: (c d e)
left: (a b c) right: (d e)
left: (a b c d) right: (e)
left: (a b c d e) right: ()
Although it may appear that our query interpreter is quite intelligent, we will see that it finds these combinations through one simple operation repeated many times: that of matching two lists that contain variables in an environment.
Continue: 4.4 Unification | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3453814387321472, "perplexity": 4985.783586558111}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1406510266894.52/warc/CC-MAIN-20140728011746-00099-ip-10-146-231-18.ec2.internal.warc.gz"} |
https://brilliant.org/problems/what-you-will-take-as-system/ | # What You Will Take As system.
A plank of mass 10kg rests on a smooth horizontal surface. Two blocks A and B of masses 2kg and 1 kg respectively. Distance b/w both masses is 3 metre. Coff. of friction for A is 0.3 and for B is 0.1 . Now a force of 15 N is applied to the plank in Horizontal Direction. Find the time after which Block A collides with B.
Round Off to nearest Integer.
Note : Correct the 2nd last statement as coff. of friction for B.
× | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9242346286773682, "perplexity": 870.4034072403989}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-04/segments/1547583857993.67/warc/CC-MAIN-20190122161345-20190122183345-00638.warc.gz"} |
http://math.stackexchange.com/questions/218532/why-the-spectral-theorem-is-named-spectral-theorem | Why the spectral theorem is named “spectral theorem”?
"If $V$ is a complex inner product space and $T\in \mathcal{L}(V)$. Then $V$ has an orthonormal basis Consisting of eigenvectors of T if and only if $T$ is normal".
I know that the set of orthonormal vectors is called the "spectrum" and I guess that's where the name of the theorem. But what is the reason for naming it?
-
Rather: the set of eigenvalues of a linear map is what is called spectrum.In the spectral theorem, you decompose the linear map in (very simple!) pieces, each piece coming from one element of the spectrum. – Mariano Suárez-Alvarez Oct 22 '12 at 6:33
@Mariano, yes! My mistake, thanks. – Hiperion Oct 22 '12 at 6:36
I'm teaching a Linear Algebra course at the moment and if things go according to schedule, I'll be discussing the Spectral Theorem on Halloween's day. :) – Andrea Mori Oct 22 '12 at 10:36 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9411029815673828, "perplexity": 274.68364664190324}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-07/segments/1454701163729.14/warc/CC-MAIN-20160205193923-00132-ip-10-236-182-209.ec2.internal.warc.gz"} |
https://proxieslive.com/tag/considered/ | ## Is the Elven Lightblade considered a light weapon for the purpose of Two Weapon Fighting? [closed]
Is the Elven Lightblade considered a light weapon for the purpose of Two Weapon Fighting?
## Why is the PHB Ranger considered underpowered?
It seems that both the community and Wizards of the Coast are largely in agreement that the PHB Ranger class is underpowered compared to the other classes.
What exactly makes it underpowered compared to other classes?
More specifically, how does the 2019 UA Ranger improve on the PHB Ranger’s weaknesses?
## Is a grappling character considered to be distracted for the purposes of an attack by a second opponent?
If a character is grappling a struggling opponent, and a second opponent attacks the character, would the DM rule that the distraction of dealing with the grappled opponent causes opponent number 2 to have Advantage on its attack?
I suppose it might depend on the nature of the Grapple. Merely grabbing an opponent by the wrist to impede his slingshot might leave you alert and ready to parry or dodge, but a more violent tussle, involving a grab with both arms would, I presume, leave you wide open for a whack from behind and thus at a Disadvantage versus a second opponent.
Even if you have followed up with a move to leave your grappled opponent Prone, I imagine that you are now kneeling, crouching or otherwise distorting your fighting stance in such a way (at least I cannot imagine that grappling a prone opponent can be done standing up) as to give a second opponent the Advantage.
I don’t see anything in the Rules (I have Essentials Kit Rulebook) covering this.
## Would this enchanted bow be considered well balanced? [closed]
The idea of this bow is to adapt the idea of karma into the attacks. It absorbs some of the “bad karma” dealt by an enemy and is able to turn it into minor good karma, or impactful force damage. The effects have been slightly based on the Rod of Absorption, Absorb Elements, the spell provided, bow stabilizers, and my knowledge on karma.
Bow of Karma (any bow, attunement)
This elegant elvish bow was made with wood that grew in a graveyard: yew and ash limbs that are connected to an aspen riser (handle) which houses up to 20 jade orbs the size of peas. With the extra 1lbs weight, one can truly feel the weight of one’s actions using this bow, and strength in the archer’s resolve.
When the wielder is attacked by magic not exerted by the environment, the bow absorbs half the damage and stores it as pure energy within the jade orbs, filling one orb per the attack’s level and attributing 1/2 orb to cantrips and breath weapons. For the absorption to occur, at least one orb must be left empty.
If the archer is attuned to the bow, they can see dots of light along the limbs whenever an orb is filled and can use the energy as spell slots on the following spells, as long as they are equal to the wielder’s own level.
Spare the dying: 1 spell slot
self: When the wielder’s HP reaches 0, the bow automatically casts Spare the Dying on them as long as they have the bow in hand.
ally: with a direct line of attack within the bow’s normal range (distance range with sharpshooter feat), the wielder can cast this spell on any creature as if touching them, by dry loosing their bow.
Conjure Barrage 3 spell slots
This attack deals a cone of force damage at the bow’s normal range (distance range with sharpshooter feat) by loosing a mundane arrow. The blows are forceful enough to the creatures within the area of effect must succeed a DC17 saving throw or be stunned until their next turn.
Conjure Volley 5 spell slots
By shooting one mundane arrow in the air and picking an area of attack, a volley of force arrows descends with enough impact that the terrain becomes difficult to navigate. Each creature within the area of effect must make a DC 17 saving throw or be stunned until their next turn. If they are stunned, they become unconscious for the next 3 turns.
Additionally, this bow’s extra weight acts like a stabilizer, granting the archer +2 proficiency in attack rolls.
I was also thinking that casting Spare the Dying on an undead creature would break it free from their summoner’s control (if summoned through magic) and give them the option to either rest or seek revenge, but I think this would be an unsourced stretch.
All in all, I would like to know if this bow seems well balanced, if there are concepts I am missing in balancing a magical item, and if there are some concepts that would work better for such a bow.
## How would you optimize a multiclass druid/monk for DPR assuming Natural Weapons are considered Unarmed Strikes?
Assuming that the Unarmored Defense, and Flurry of Blows features both work with the Druid’s Wild Shape feature, what is the optimal DPR build for a Druid/Monk multiclass, and what are the notable break points for this particular multiclass?
You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so.
PHB, page 67
Also assume that Natural Weapons are considered Unarmed Strikes, as per the the description of Alter Self:
Natural Weapons. You grow claws, fangs, spines, horns, or a different natural weapon of your choice. Your unarmed strikes deal 1d6 bludgeoning, piercing, or slashing damage, as appropriate to the natural weapon you chose, and you are proficient with your unarmed strikes.
PHB, page 212
Given access to any appropriate Beast, as well as having the option to choose either:
a) Multi-attack from the Beast entry, or
b) Extra Attack from the appropriate Monk level
What is the highest DPR possible?
Other assumptions:
• Official D&D Content only, excluding Unearthed Arcana
## Why is the Black-White Bakery Algorithm considered bounded?
As stated in Lamport’s papers for the bakery algorithm he states that the ticket numbers are unbounded specifically
The range of values of number is unbounded.
and
Fortunately, practical considerations will place an upper bound on the value of number[i] in any real application. For example, if processors enter the doorway at the rate of at most one per msec, then after a year of operation we will have number[i] < $$2^{35}$$—assuming that a read of number[i] can never obtain a value larger than one which has been written there.
What I don’t understand is, why does Taubenfeld’s Black-White Bakery Algorithm solves this problem and thus considered bounded.
I see no reason why the usage of the extra color register would solve such a problem?
Thanks
## What is considered “running water” for the vampire’s weakness?
I like a lot D&D vampires. I even bought curse of Strahd. But something I always wandered is “What is running water ?”
Rivers are running waters, since it is used as an exemple. But how about rain (no answers are given on the related question)? How about a bottle? How about peeing on a vampire? How about puddles?
related question:
Is rain considered Running Water for a Vampire’s weakness?
## In what sense the computer program (Turing machine) can be considered as the complex system and its IIT Phi can be measured and improved?
I am reading https://global.oup.com/academic/product/a-world-beyond-physics-9780190871338?cc=us&lang=en& about one approach of complex systems’ theory for the emergence of the life. It is about the autocatalytic soup of molecules from which the life can emerge. Of course, one is thinking further – every computer program, every Turing machine is more ore less autocatalytic soup of interacting software components from which the consciousness, mind and Artificial General Intelligence (https://content.sciendo.com/view/journals/jagi/jagi-overview.xml) can emerge.
Of course – ther program (Turing machine) should be of sufficient complexity for such consciousness to emerge – and such complexity/level of consciousness can be measured by Phi measure of https://en.wikipedia.org/wiki/Integrated_information_theory .
My question is – how the theory of complex systems is applied to the software programs (including logic programs, sets of first order formulas, knowledge bases, functional programs, lambda terms), e.g. to derive the directions (modular organization, wealth of functionality, et.c) for evolving the programs into the programs with higher level of Phi, whith higer level of autonomy and consciousness? I presume, that consciousness is the driving force for the program to exhibit commonsense knowledge, for the capability to make generalizations and transfer skills among tasks (all those are very hot topics and deep learning community without almost any theory behind them). All these issues are the grails of current computer science and that is why my question is very applied in nature.
Currently computer programs and algorithms are developed in trial-and-error process. The development of software systems that are called cognitive architectures (http://bicasociety.org/cogarch/architectures.php) or that are called cognitive systems (http://www.cogsys.org/journal) is prominent features of such efforts. But maybe the theory of complex systems can be applied to such programs to determine why such programs exhibit or do not exhibit the capabilities of consciousness (as determined by IIT or any other computational theory of consciousness or mind – there are some others, academically sound) and what can be do on such programs to evolve them into capable systems with higher Phi. We have tried to design and program features but no cognitive architecture has achieved sufficient level of AGI. We can try still more harder. But maybe the theory of complex systems can provide some guidance to estimate the weak points and to provide some direction?
Just some reference for applying the theory of complex systems to the programs in the widest sense?
## Are D&D novelizations considered canonical source materials?
I’m curious if the works of R.A. Salvatore and the like are considered canon source material for D&D campaign games. Or if they are treated more like fanfictions.
## Would creating undead minions be considered an evil action in PFS, and therefore earn Infamy?
Would creating undead minions be considered an evil action in PFS, and therefore earn Infamy? I’m not keen on GMing for a necromancer or anti-paladin type character, but also don’t want to deny a player’s choices outright. It seems like a necromancer (sans undead minions) is distinctly different than someone with an undead horde. This line of questioning extends to fiendish summoning, etc. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 1, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5976313948631287, "perplexity": 3352.9666566260403}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875147647.2/warc/CC-MAIN-20200228200903-20200228230903-00382.warc.gz"} |
https://www.earthdoc.org/content/papers/10.3997/2214-4609.201801537 | 1887
### Abstract
Summary
Since most of the information on S-waves and density exists in the middle to large angle range of seismic data, traditional inversion methods based on the Zoeppritz approximation have difficulty in obtaining satisfactory results. Therefore, as a high accuracy AVA inversion, exact Zoeppritz (EZ) equation inversion has aroused a lot of attention in recent years. As for any other non-linear inversion, iterative convergence and error are the important problems. In this abstract, based on a Bayesian framework, we have introduced optimal transport into exact Zoeppritz equation AVA inversion. Then the L-BFGS method is adopted to solve the regularization-constrained least-square argument function to obtain the inversion results, including P-wave velocity, S-wave velocity and density. We compare this method with a conventional method, which is based on a L2 norm or weighted L2 norm as a residual method in the model test. The results show that the proposed method not only reduces the error of the results to be smaller than L2 norm, but it also improves the convergence rate.
/content/papers/10.3997/2214-4609.201801537
2018-06-11
2020-08-05
References
1. Engquist, B., & Froese, B. D.
(2013). Application of the Wasserstein metric to seismic signals. Communications in Mathematical Sciences, 12(5), 979–988.
2. Engquist, B., Froese, B. D., & Yang, Y.
(2016). Optimal transport for seismic full waveform inversion., 14(8).
3. Métivier, L., Brossier, R, Mérigot, Q., Oudet, E., & Virieux, J.
(2016). An optimal transport approach for seismic tomography: application to 3D full waveform inversion. Inverse Problems, 32(11), 115008.
4. Zhou, L., Li, J., Chen, X., Liu, X., & Chen, L.
(2017). Prestack amplitude versus angle inversion for Young’s modulus and Poisson’s ratio based on the exact Zoeppritz equations. Geophysical Prospecting, 65.
5. Zhi, L., Chen, S., & Li, X. Y.
(2016). Amplitude variation with angle inversion using the exact Zoeppritz equations — theory and methodology. Geophysics, 81(2), N1–N15. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.907443106174469, "perplexity": 3431.3232816264936}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-34/segments/1596439735909.19/warc/CC-MAIN-20200805035535-20200805065535-00472.warc.gz"} |
https://www.sqlpac.com/referentiel/docs-en/html-equations-math-with-mathjax-asciimath.html | # Mathematical expressions and equations in HTML with MathJax and AsciiMath
## Introduction
Writing mathematical expressions and equations in HTML pages, even if the use may not be common, and in some instances exceptional, has always been problematic. But sometimes we need to display formulas with a good ergonomic rendering.
Either the expression is in a raw format, not very ergonomic and difficult to read, especially when the formula contains fractions, for example :
f(x) = (x + 2) / (2x + 1) x ∈ R, x ≠ − 1/2
or an image is created from tools such as Formula Math in LibreOffice, image to be recreated if the formula needs to be updated and further more the user is then not able to copy some text :
Very early, HTML 5 was scheduled to integrate MathML standards for writing mathematical expressions in HTML, but browsers publishers have decided otherwise. MathML support in the major browsers (Chrome, FireFox, MS Internet Explorer, Safari) was disparate and there were too many disagreements.
Google, the publisher of Chrome, is probably right by deciding not to bring MathML in its browser. Google argued that MathML is restricted to an audience of scientists (mathematicians, physicists, statisticians) and powerful Javascript libraries already exist to cover the needs.
Indeed, MathJax is a Javascript library, compatible with all browsers, simple and very advanced for rendering mathematical expressions in HTML. The rendering is impressive, the coding simple and the content of the expressions thus becomes easily updatable. The above example rendered with MathJax (option AsciiMath) :
f(x) = (x+2)/(2x+1) x in RR,\ x !=-1/2
<div class="cmath"> f(x) = (x+2)/(2x+1) x in RR,\ x !=-1/2</div>
MathJax manages several input syntaxes (Tex / Latex, AsciiMath, MathML MML), AsciiMath syntax being by far the easiest for simple needs.
This is a quick reference on how to include MathJax automatically in articles if mathematical expressions exist (AsciiMath and/or Tex-Latex syntaxes). Compared to the Tex-Latex syntax, AsciiMath syntax is indeed the easiest to use for basic needs, but there is a lack of documentation about specific needs when using AsciiMath. This paper focuses on these topics using AsciiMath syntax :
• Applying style to a portion of an equation
• Highlighting an equation
• Numbering equations
• Centering equations on the sign =
## Mechanics, configuring MathJax
To schematize the MathJax library mechanics :
One or more input syntaxes are possible (AsciiMath, Tex / Latex, MathML) and the mathematical expression is displayed graphically in an output format (HTML-CSS, SVG, MathML if the browser supports the MathML language like FireFox).
The MathJax JavaScript library is typically called using the syntax below :
<installation path>/MathJax.js?config=<input syntaxe(s)>_<output format(s)>
The official documentation describes the possible configurations combinations : MathJax - Combined configurations.
Some common configurations :
ConfigDescription
…/MathJax.js?config=AM_CHTML
• Input syntax : AsciiMath (AM)
• Output format : "Common HTML" (CHTML)
…/MathJax.js?config=TeX-MML-AM_CHTML
• Input syntax : Tex/Latex (TeX), or MathML (MML), or AsciiMath (AM)
• Output format : "Common HTML" (CHTML)
…/MathJax.js?config=TeX-AMS_CHTML
• Input syntax : Tex/Latex (TeX) including AMS symbols
• Output format : "Common HTML" (CHTML)
The MathJax library can be installed locally. It is downloadable in zip format from the MathJax GitHub site : MathJax GitHub Downloads. The MathJax library size is around 70 Mb uncompressed (version 2.7.8 - August 2019).
When not choosing a local installation, MathJax 2 is available online with CDN providers (Content Delivery Network).
For a given configuration, AM_CHTML in the below examples (AsciiMath syntax in input, Common HTML in output format), in the page’s header using an online CDN context :
<head>…
<script async="true" src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=AM_CHTML"> </script>
…</head>
The option mathjax@2 in the URL of the script MathJax.js guarantees the use of the most recent version 2. If for some reason, a specific version must be used (bug…) in a page or a few, for example the version 2.7.6 :
<head>…
<script async="true" src="https://cdn.jsdelivr.net/npm/mathjax@2.7.6/MathJax.js?config=AM_CHTML"> </script>
…</head>
The examples above are classic and basic calls, a next paragraph describes how to secure and industrialize the call to the MathJax library.
## MathJax and the AsciiMath syntax
AsciiMath is the easiest input syntax (compared to Tex / Latex, MathML) for a basic usage to render mathematical expressions. When advanced features are needed, no choice, switch to the Tex / Latex language.
Requesting AsciiMath in the configuration (AM) and without custom parameters defined before, you're done :
<head>…
<script async="true" src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=AM_CHTML"> </script>
…</head>
Just delimit the mathematical expressions written in AsciiMath syntax using backtick characters ().
<div class="cmath">
f(x)=x^2 + 2x + 1 = 0 Derivative of the function : f'(x)=2x + 2
frac(df(x))(dx) = lim_(h->0)(f(x+h)-f(x))/h
f(t) = a_(0)/2 + sum_(n=1)^oo [a_(n) cos(nt) + b_(n) sin(nt)]
x' = frac(-b -sqrt(Delta))(2a)
</div>
f(x)=x^2 + 2x + 1 = 0 Derivative of the function : f'(x)=2x + 2 frac(df(x))(dx) = lim_(h->0)(f(x+h)-f(x))/h f(t) = a_(0)/2 + sum_(n=1)^oo [a_(n) cos(nt) + b_(n) sin(nt)] x' = frac(-b -sqrt(Delta))(2a)
In the above examples, AsciiMath expressions are written in div blocks. The CSS class cmath is applied on the container div : in this class the property white-space is set to pre. Spaces and new lines in the container are better managed using this property.
div.cmath {
display: block;
margin: 20px 0px 20px 30px;
white-space : pre;
}
Expressions can be "in line" within a paragraph using span tags.
<p>An expression : <span> sum_(i=1)^n i^3=((n(n+1))/2)^2</span> within a phrase.</p>
An expression : sum_(i=1)^n i^3=((n(n+1))/2)^2 within a phrase.
## Securing and industrializing the loading of the MathJax library
With few lines of JavaScript code, the industrialization and optimization of the MathJax library loading can be handled by a function.
<head>
…
<script type="text/javascript" src="./js/lib.js"> </script>
…
</head>
./js/lib.js
run_maths = function() {
if (document.querySelector('[class*="cmath"]') !== null) {
if (typeof (mjax_path)=='undefined') { mjax_path='https://cdn.jsdelivr.net/npm/mathjax@2'; }
if (typeof (mjax_config)=='undefined') { mjax_config='AM_CHTML'; }
smjax = document.createElement ('script');
smjax.setAttribute('src',${mjax_path}/MathJax.js?config=${mjax_config});
smjax.setAttribute('async',true);
}
};
else { run_maths(); }
The function run_maths is called when the event DOMContentLoaded is going to happen or if the document.readyState property is already interactive or complete. All the document’s nodes must be loaded before inserting dynamically and firing MathJax.
In the function run_maths
• The MathJax library is dynamically inserted only if there is at least one element in the document containing the class cmath. Using this method, the MathJax library, which has a significant cost in the page’s load, will only be called if the page needs it.
• If a configuration is not already explicitly specified using the variable mjax_config, a default configuration is applied.
if (typeof (mjax_config)=='undefined') { mjax_config='AM_CHTML'; }
• Ditto for the path to the MathJax library using the variable mjax_path.
if (typeof (mjax_path)=='undefined') { mjax_path='https://cdn.jsdelivr.net/npm/mathjax@2'; }
The path to MathJax and / or the configuration can then be modified for a given page by defining the variables mjax_path and / or mjax_config to override the default values. It doesn’t matter where the definition is performed in the document, MathJax is not loaded before the DOMContentLoaded event.
<script> var mjax_config='TeX-MML-AM_CHTML';</script>
<script> var mjax_path='https://cdn.jsdelivr.net/npm/mathjax@2.7.6';</script>
## The underscore character _ in AsciiMath syntaxes : text{ }
A quick note about the underscore character because the examples of equations in documentations and tutorials do not address this point very much. Often, variables in expressions contain underscore characters _, the character underscore is interpreted in AsciiMath syntax to define subscript letters or symbols. To prevent this character from being interpreted, use the option text{variable_1}.
<div class="cmath">R=D/L=frac (text{del_lf_rows})(text{lf_rows}) >= 0,1</div>
R=D/L=frac (text{del_lf_rows})(text{lf_rows}) >= 0,1
A lighter syntax is possible by escaping the variables containing the underscore character with double quotes.
<div class="cmath">R=D/L=frac ("del_lf_rows")("lf_rows") >= 0,1</div>
Using the syntax text { } or escaping with double quotes, unfortunately we lose the mathematical typography (italics, etc.), to recover it, we have to force the font on the elements inside the mjx-mtext class, class applied by the Mathjax engine in this context.
.mjx-mtext > * { font-family: MJXc-TeX-math-I,MJXc-TeX-math-Ix,MJXc-TeX-math-Iw !important; }
## Problem with the backtick character as the delimiter of AsciiMath syntaxes, conflicts with MySQL and Shell syntaxes
Using the backtick character as the delimiter raises a question : what happens if a page contains this character in the text or in a MySQL or Shell syntax, languages that use the backtick ?
insert into matable values ...
No problem, backticks are not interpreted by MathJax when they are in the below HTML tags :
• script, noscript
• style
• textarea, pre, code
• annotation, annotation-xml
For MySQL syntaxes and Shell scripts, except in specific cases, pre and code tags are generally used in order to benefit from syntax highlighting with HighlightJs or Prism Javascript libraries. In the other cases, use the code or annotation tags to encapsulate the backtik so that MathJax does not interpret the content.
<code></code> <annotation></annotation>
If the backtick as a delimiter of mathematical expressions generates too many conflicts with the content in a page, the AsciiMath delimiter can be modified with the code below before loading the MathJax library :
<script type="text/javascript">
window.MathJax = {
asciimath2jax: {
delimiters: [['~','~']]
}
};
</script>
<script type="text/javascript" src="./js/lib.js"></script>
The backtick character is replaced by the character tilde ~ as the delimiter in the above example.
## CSS styles and MathJax / AsciiMath
Is it possible to apply a CSS style to all or part of an equation written in AsciiMath with MathJax ? Yes.
The features discussed in this paragraph are available starting MathJax 2 version 2.7.5 which supports AsciiMath 2. AsciiMath 2 adds some Latex notations, including the notation class{}
The ouput format must be "Common HTML" (CHTML) in the configuration.
These features are not (yet) ported in MathJax 3 which still relies on AsciiMath 1.7.4.
For the ease of read, it is sometimes needed to change the style (notes…) on all or part of an equation. Using span tags associated to a CSS style class could be one solution, but there is the syntax class{<classname>}{<equation code>} ensuring more consistency in writing the equation and thus avoiding HTML tags.
In the below example, we want the comment Delta=b^2-4ac > 0 to appear with a spacing of 100px on the left, a specific color and a smaller font size:
ax^2 + bx + c = 0 x = frac(-b +- sqrt(Delta))(2a) class{cmjx-note}{ text{rem : } \ Delta=b^2-4ac > 0 }
The class CSS cmjx-note is defined for this purpose, in a stylesheet script of the page or in the HTML code with style tags :
.cmjx-note {
transform: translate(100px);
font-size: 0.8em;
color: #DD4A68;
}
The CSS class cmjx-note is applied to the desired location in the equation with the syntax : … class{cmjx-note} { … Delta=b^2-4ac > 0 } …
<div class="cmath">
ax^2 + bx + c = 0
x = frac(-b +- sqrt(Delta))(2a) class{cmjx-note}{ text{rem : } \ Delta=b^2-4ac > 0 }
</div>
Several CSS classes can be defined using the syntaxe class :
x = frac(-b +- sqrt(Delta))(2a) class{cmjx-note cmjx-note1 cmjx-note2}{ text{rem : } \ Delta=b^2-4ac > 0 }
Knowing this trick about AsciiMath syntaxes, many practical applications :
• Equations to be highlighted with borders.
• Numbering equations.
### Highlighting equations
An immediate and very simple practical application: highlighting an AsciiMath equation by applying a border. Useful to normalize the borders with the site’s ergonomy (colors, etc.).
class{cmjx-highlight} { e^x = lim_(n->oo) (1 + x/n)^n }
.cmjx-highlight { border: 2px solid #DD4A68; padding: 8px; margin-right: 4px; }
<div class="cmath">
class{cmjx-highlight} { e^x = lim_(n->oo) (1 + x/n)^n }
</div>
Much less used, but this class can be applied on "inline" expressions :
The volume of a sphere is class{cmjx-highlight} {V = 4/3\piR^3} , therefore …
<p> The volume of a sphere is <span class="cmath"> class{cmjx-highlight} {V = 4/3\piR^3} </span>, therefore …</p>
### Numbering equations
The solution is not perfect but by using a CSS class in which the position is absolute, 600px on the left for example, the numbering of AsciiMath equations becomes quite simple with the class {} syntax.
.cmjx-nb { position: absolute; left: 600px; }
<div class="cmath">
cos^2 \theta + sin^2 \theta = 1 class{cmjx-nb}{(9)}
cos^2 \theta - sin^2 \theta = cos 2\theta class{cmjx-nb}{(10)}
</div>
cos^2 \theta + sin^2 \theta = 1 class{cmjx-nb}{(9)} cos^2 \theta - sin^2 \theta = cos 2\theta class{cmjx-nb}{(10)}
The absolute position may have to be adjusted through another class depending on the context (equations complexity, etc.).
If rendering on mobile devices is a concern, to summarize very briefly: when equations start to be numbered, it concerns more pages around topics specific to mathematics, physics, etc., pages that should generally be viewed on a desktop device.
## Centering AsciiMath equations on the sign =
To center AsciiMath equations on the sign =, matrices are used for the layout. With the Tex / Latex syntax, it is quite different.
{: ( f(x) ,=, (x+2)(x-3) ) , ( ,=, x^2 -3x +2x -6 ) , ( ,=, x^2 -x - 6 ) , ( f'(x) ,=, 2x -1 ) :}
The sign = is then an element of the matrix. The opening and closing element of the matrix is hidden ({: :}) :
<div class="cmath">
{:
( f(x) ,=, (x+2)(x-3) ) ,
( ,=, x^2 -3x +2x -6 ) ,
( ,=, x^2 -x - 6 ) ,
( f'(x) ,=, 2x -1 )
:}
</div>
When the equations are linear on both sides in the matrix, the rendering is perfect. As soon as there are fractions, the rendering is less optimal.
<div class="cmath">
{:
( f(x) ,=, frac(x+1)(x-2) ) ,
( f'(x) ,=, frac((x-2) - (x+1))((x-2)^2) ) ,
( ,=, - frac(3)(x^2 - 4x + 4) )
:}
</div>
{: ( f(x) ,=, frac(x+1)(x-2) ) , ( f'(x) ,=, frac((x-2) - (x+1))((x-2)^2) ) , ( ,=, - frac(3)(x^2 - 4x + 4) ) :}
To solve this issue, define a CSS class in order to adjust in particular the font size, the adjustment is performed here with the unit rem :
.cmjx-lg { font-size: 1.65rem; padding-bottom:8px;}
The unit and the value to use depend on the context of the page and they are determined empirically.
The class is then applied on the elements to adjust/enlarge, so in this use case the fractions :
<div class="cmath">
{:
( f(x) ,=, class{cmjx-lg} { frac(x+1)(x-2) } ) ,
( f'(x) ,=, class{cmjx-lg} { frac((x-2) - (x+1))((x-2)^2) } ) ,
( ,=, class{cmjx-lg} { - frac(3)(x^2 - 4x + 4) } )
:}
</div>
{: ( f(x) ,=, class{cmjx-lg} { frac(x+1)(x-2) } ) , ( f'(x) ,=, class{cmjx-lg} { frac((x-2) - (x+1))((x-2)^2) } ) , ( ,=, class{cmjx-lg} { - frac(3)(x^2 - 4x + 4) } ) :}
## Combining AsciiMath and Tex/Latex syntaxes: how, when and why ?
When mathematical expressions are basic, the simplicity of AsciiMath syntax is perfect. Whenever there is complexity, the AsciiMath syntax shows its weaknesses.
In a page, the 2 syntaxes can be combined. The Tex / Latex syntax is then used in blocks of equations involving cases that the AsciiMath syntax cannot cover.
To combine the 2 syntaxes, the configuration TeX-MML-AM_CHTML is defined when calling MathJax. Some configuration specific to Tex / Latex is done before calling MathJax using the object window.MathJax
<head> …
<script>
window.MathJax = {
tex2jax : { inlineMath : [ ['##','##'], ["\$$","\$$"] ],
displayMath: [ ['$$','$$'], ["\$","\$"] ],
processEscapes : true
},
displayAlign: "left"
};
</script>
<script async="true" src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=TeX-MML-AM_CHTML"> <script>
… </head>
The run_maths function discussed previously in the paragraph "Securing and industrializing the loading of the MathJax library" is customized to predefine the properties for Tex / Latex syntaxes in the window.MathJax object.
./js/lib.js
run_maths = function() {
if (document.querySelector('[class*="cmath"]') !== null) {
if (typeof (mjax_path)=='undefined') { mjax_path='https://cdn.jsdelivr.net/npm/mathjax@2'; }
if (typeof (mjax_config)=='undefined') { mjax_config='AM_CHTML'; }
if (typeof(window.MathJax) == 'undefined') { window.MathJax = { }; }
if (mjax_config.toLowerCase().indexOf('tex') >= 0) {
m = window.MathJax;
if (typeof(m.displayAlign) == 'undefined') { m.displayAlign = 'left'; }
if (typeof(m.tex2jax) == 'undefined') { m.tex2jax = { }; }
if (typeof(m.tex2jax.inlineMath) == 'undefined') { m.tex2jax.inlineMath = [ ['##','##'], ["\$$","\$$"] ]; }
if (typeof(m.tex2jax.displayMath) == 'undefined') { m.tex2jax.displayMath = [ ['$$','$$'], ["\$","\$"] ]; }
if (typeof(m.tex2jax.processEscapes) == 'undefined') { m.tex2jax.processEscapes = true; }
}
smjax = document.createElement ('script');
smjax.setAttribute('src',${mjax_path}/MathJax.js?config=${mjax_config});
smjax.setAttribute('async',true);
}
};
else { run_maths(); }
When a page needs the combination of the 2 syntaxes (AsciiMath and Tex/Latex), define the variable mjax_config and assign the value TeX-MML-AM_CHTML :
…
<script> var mjax_config='TeX-MML-AM_CHTML'; </script>
…
<script type="text/javascript" src="./js/lib.js"> </script>
…
One may ask why a such complicated function code : by checking if each object or property already exists or not, the function ensures no custom property needed in a page is overwritten, much less the object window.MathJax. Example :
…
<script>
window.MathJax = {
tex2jax : { inlineMath: [ ['~~','~~'] ]; }
};
</script>
<script> var mjax_config='TeX-MML-AM_CHTML'; </script>
<script type="text/javascript" src="./js/lib.js"> </script>
…
In the default configuration applied by the function run_maths, for a page combining the 2 syntaxes :
SyntaxModeCode writing
AsciiMathBlock or "in line"… AsciiMath code…
Tex/LatexBlock$$… Latex code…$$ $… Latex code …$
Tex/LatexIn line##… Latex code …## $$… Latex code …$$
By default, in block mode, expressions written in Latex are centered in the parent container (div …). The property displayAlign in the window.MathJax object overrides this default behaviour. In this article, left alignment is forced (displayAlign: 'left').
In the following sub-paragraphs, some cases in which the Latex syntax solves some issues encountered with the syntax AsciiMath.
### Matrices with fractions (dfrac)
In a matrix containing fractions, using AsciiMath the fractions are badly sized. The CSS class cmjx-lg (font-size: 1.65rem) can be applied in order to adjust the elements to resize, but it does not solve the issue about the opening and closing character of the matrix, offsets are obvious :
[bbrho] = ( ( 1/2 , 0 ), ( 0 , 1/2 ) )
[bbrho] = ((1/2,0), (0,1/2))
[bbrho] = ( ( class{cmjx-lg}{1/2} , 0 ), ( 0 , class{cmjx-lg}{1/2} ) )
[bbrho] = ( ( class{cmjx-lg}{1/2}, 0), (0, class{cmjx-lg}{1/2}) )
The Latex syntax is less easy but the rendering is pertect. Using AsciiMath syntax, this would have been technically impossible. The opening and closing character of the matrix embraces its elements :
$$ [\pmb{\rho}] = \begin{pmatrix} \dfrac{1}{2} & 0 \\ 0 & \dfrac{1}{2} \\ \end{pmatrix} $$
$$[\pmb{\rho}] = \begin{pmatrix} \dfrac{1}{2} & 0 \\ 0 & \dfrac{1}{2} \\ \end{pmatrix}$$
Why \dfrac and not \frac in the Latex syntax ? Using \dfrac (displaystyle), the overall style is applied to the fraction, the fraction is not resized in relation to the matrix row.
### Continuous fractions (cfrac)
Writing continued fractions with AsciiMath syntax is badly rendered, no easy technical solution (CSS classes…) :
x = frac(1)(sqrt2 + frac(1)(sqrt2 + frac(1)(sqrt2 + ...)))
x = frac(1)(sqrt2 + frac(1)(sqrt2 + frac(1)(sqrt2 + ...)))
Using the Latex syntax and cfrac, the rendering is correct and the code is even more readable :
$$ x = \cfrac{1}{\sqrt{2}+ \cfrac{1}{\sqrt{2}+ \cfrac{1}{\sqrt{2}+\dotsb} } } $$
$$x = \cfrac{1}{\sqrt{2}+ \cfrac{1}{\sqrt{2}+ \cfrac{1}{\sqrt{2}+\dotsb} } }$$
### Centering equations on the sign =
Using AsciiMath, when equations are linear on either side of the sign =, no issue to center on the sign = using matrices for layouts. Rendering is more complicated when there is a fraction, fractions are displayed smaller : this issue is solved by applying, on the elements to be adjusted, the CSS class cmjx-lg (font-size: 1.65rem).
<div class="cmath">
{:
( f(x) ,=, class{cmjx-lg} { frac(x+1)(x-2) } ) ,
( f'(x) ,=, class{cmjx-lg} { frac((x-2) - (x+1))((x-2)^2) } ) ,
( ,=, class{cmjx-lg} { - frac(3)(x^2 - 4x + 4) } )
:}
</div>
{: ( f(x) ,=, class{cmjx-lg} { frac(x+1)(x-2) } ) , ( f'(x) ,=, class{cmjx-lg} { frac((x-2) - (x+1))((x-2)^2) } ) , ( ,=, class{cmjx-lg} { - frac(3)(x^2 - 4x + 4) } ) :}
Using the Latex syntax, the adjustment of the fractions is no longer a concern. The Latex syntax is not more or less complex than the AsciiMath syntax to achieve centering.
<div class="cmath"> \begin{align} f(x) &= \frac{x+1}{x-2} \\ \\ f'(x) &= \frac{(x-2) - (x+1)}{(x-2)^2} \\ \\ &= - \frac{3}{x^2 - 4x + 4} \end{align} </div>
\begin{align} f(x) &= \frac{x+1}{x-2} \\ \\ f'(x) &= \frac{(x-2) - (x+1)}{(x-2)^2} \\ \\ &= - \frac{3}{x^2 - 4x + 4} \end{align}
### Numbering equations, references
Using \tag in the Tex/Latex syntax, numbering equations is easy, which is not the case using AsciiMath syntax. We kill two birds with one stone : the equation number is correctly centered on the right side of its container and the equations can be centered on the sign =.
<div class="cmath"> \begin{align} \cos 2\theta &= \cos^2 \theta - \sin^2 \theta \tag{9} \label{cos2x} \\ \\ \cos^2 \theta + \sin^2 \theta &= 1 \tag{10} \label{10} \\ \\ \end{align} </div>
\begin{align} \cos 2\theta &= \cos^2 \theta - \sin^2 \theta \tag{9} \label{cos2x} \\ \\ \cos^2 \theta + \sin^2 \theta &= 1 \tag{10} \label{10} \\ \\ \end{align}
Using \label in the above example, bookmarks are easily defined. It is not necessary that tag and label are the same. Very convenient to refer to an expression described elsewhere on the page using \ref of the Latex syntax :
<div class="cmath">
We deduce from the formulas $$\ref{cos2x}$$ and $$\ref{10}$$ :
\begin{align} \cos 2\theta &= \cos^2 \theta + \sin^2 \theta - \sin^2 \theta - \sin^2 \theta \\ \\ &= 1 - 2\sin^2\theta \end{align} </div>
We deduce from the formulas $$\ref{cos2x}$$ and $$\ref{10}$$ : \begin{align} \cos 2\theta &= \cos^2 \theta + \sin^2 \theta - \sin^2 \theta - \sin^2 \theta \\ \\ &= 1 - 2\sin^2\theta \end{align}
From the menu "Show Math As", the AsciiMath, Tex/Latex source code can be retrieved easily to get a copy. The input syntax (AsciiMath, Tex/Latex) is automatically dectected.
Useful for debugging purposes, using this functionality in the MathJax’s menu we figure out that classes in AsciiMath or Tex/Latex syntaxes only work if the output format is set to "Common HTML" (CHTML`). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 2, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 6, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9771702289581299, "perplexity": 7650.752802038373}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141184123.9/warc/CC-MAIN-20201125183823-20201125213823-00479.warc.gz"} |
https://advancedoptimizationatharvard.wordpress.com/2014/02/20/applying-linear-programming-to-game-theory/comment-page-1/ | # Applying Linear Programming to Game Theory
## Introduction
A central problem in algorithmic game theory involves finding the Nash equilibria of a game quickly. It turns out that this task is very hard in general – finding Nash equilibria is, in fact, PPAD-complete, even for two-player games. There are, however, classes of games for which finding Nash equilibria is computable in worst-case polynomial time, using linear programming. In this blog post, we’ll explore three of these examples: proving the minmax theorem, finding Nash equilibria given the supports of the equilibrium strategies, and finding correlated equilibria.
## Simultaneous-Move Games
A simultaneous-move game $(N,A,u)$ is defined as a set of agents, actions, and payoffs. More formally, we have
• $N = \{1,...n\}$ agents, indexed by $i$
• $A = A_1 \times ... \times A_n$, where $A_i$ is a set of actions available to agent $i$ and where $a = (a_1,...,a_n) \in A$ denotes an action profile
• $u = (u_1,...u_n)$, where $u_i: A \rightarrow \mathbb{R}$ is the payoff function for agent $i$.
## Nash Equilibrium
A Nash equilibrium is an action profile where nobody has an incentive to deviate from his prescribed action when fixing the others’ actions. A Nash equilibrium can be of pure-strategies or mixed strategies.
#### Pure-Strategy Nash Equilibrium
In a pure strategy Nash equilibrium, each player plays one action in equilibrium.
More formally, an action profile $a^* = (a_1^*,...,a_n^*)$ is a pure-strategy Nash equilibrium of the simultaneous-move game (N,A,u) if for all i,
$u_i(a_i^*,a_{-i}^*) \geq u_i(a_i,a_{-i}^*) \text{ for all strategies } a_i \in A_i.$
#### Mixed-Strategy Nash Equilibrium
In a mixed-strategy Nash equilibrium, a player can play a subset of his available actions according to a certain probability distribution. We say that the strategies $a_i \in A_i$ played with positive probability in a mixed-strategy is in the support of that strategy profile.
Formally, a strategy profile $\sigma^* = (\sigma_1^*,...,\sigma_n^*)$ is a mixed-strategy Nash equilibrium in game $(N,A,u)$ if for all $i$,
$u_i(\sigma_i^*,\sigma_{-i}^*) \geq u_i(a_i,\sigma_{-i}^*) \text{ for all strategies } a_i \in A_i.$
## Chicken
One example of a two-player, simultaneous move game is the game of chicken. The story for the game is as follows:
Two teenagers are driving towards each other at a high velocity. If one swerves before the other, the “chicken” loses prestige among his peers, while the other gains prestige. If both of them swerve together, they both retain their honor. If neither of them swerve, both suffer serious injuries, which is much worse than losing their prestige.
This game can be represented in normal form as follows:
The rows represent the strategies available to player 1 while the columns represent the strategies available to player 2. The left number within a matrix entry represents the payoff to player 1 when the respective actions are played, while the right number represents the payoff to player 2. It is easy to see that there is no pure-strategy Nash equilibrium to this game. A mixed-strategy equilibrium does exist, however, where both players swerve with probability $\frac{2}{3}$ and go straight with probability $\frac{1}{3}$. In fact, there is a theorem, which we will not prove, that every finite-strategy, finite-player game has a mixed-strategy Nash equilibrium.
## Two-player, Zero-sum Games
A zero-sum game is a game in which the total payoffs to the players sum to 0 for every action profile in the game. (In fact, these games could also be called constant-sum games, since the payoffs need only sum to the same constant value).
#### Maximin Strategy
A maximin strategy for player 1 is a strategy which maximizes player 1’s payoff given that player 2 tries to minimize player 1’s payoff for any given strategy $a_1 \in A_1$. Namely,
$\overline{s_1} \in arg max_{s_1} \left[min_{a_2\in A_2} u_1(s_1,a_2)\right]$
#### Minimax Strategy
A minimax strategy for player 1 is a strategy which minimizes player 2’s expected utility, given that player 2 tries to maximize his own payoff given any strategy of player 1.
$\underline{s_1} \in arg min_{s_1} \left[max_{a_2\in A_2} u_2(s_1,a_2)\right]$
#### Minmax Theorem
The minmax theorem states that for any two-player, zero-sum game, the set of each player’s maximin strategies will be identical to the set of minimax strategies, that any combination of these minimax/maximin strategies will be a Nash equilibrium of the game, and that each player’s maximin value will equal its minimax value. We can prove this theorem using strong duality.
To solve the maximin value for Player 1, we can solve the LP
Maximize v
Subject to:
$v - u_1(a_1,a_2)p_1(a_1) \leq 0$
$\sum_{a_1 \in A_1} p_1(a_1) = 1$
$p_1(a_1) \geq 0, \forall a_1 \in A_1$
where $p_1(a_1)$ is the probability with which player 1 plays the action $a_1 \in A_1$.
The dual to this problem is
Minimize u
Subject to:
$u - u_2(a_1,a_2)p_2(a_2) \geq 0$
$\sum_{a_2 \in A_2} p_2(a_2) = 1$
$p_2(a_2) \geq 0, \forall a_2 \in A_1$
where $p_2(a_2)$ is the probability with which player 2 plays the action $a_2 \in A_2$.
This is exactly the same as the LP for Player 2’s optimal strategy, and thus strong duality gives us the minmax theorem. We can solve for the minimax/maximin strategies using an algorithm like the simplex algorithm.
## Finding a Nash equilibrium when given the supports in a general two-player game
Although it is difficult to find mixed-strategy Nash equilibria for finite-games in general, it is simpler to find Nash equilibria given the strategies that are in the support of each player’s mixed-strategy in equilibrium. Indeed, given candidate supports $(\sigma_1,\sigma_2)$, we may find Nash equilibria, if feasible, by solving the following LP for any objective function:
Maximize Any objective function
Subject to:
$\sum_{a_2\in A_2} u_1(a_1,a_2)p_2(a_2) = v_1, \forall a_1 \in \sigma_1$
$\sum_{a_2\in A_2} u_1(a_1,a_2)p_2(a_2) \leq v_1, \forall a_1 \notin \sigma_1$
$\sum_{a_1 \in A_1} p_1(a_1) = 1$
$p_1(a_1) \geq 0, \forall a_1 \in \sigma_1$
$p_1(a_1) = 0, \forall a_1 \notin \sigma_1$
$\sum_{a_1\in A_1} u_1(a_1,a_2)p_1(a_1) = v_1, \forall a_2 \in \sigma_1$
$\sum_{a_1\in A_1} u_1(a_1,a_2)p_1(a_1) \leq v_1, \forall a_2 \notin \sigma_1$
$\sum_{a_1 \in A_1} p_2(a_2) = 1$
$p_1(a_2) \geq 0, \forall a_2 \in \sigma_1$
$p_1(a_2) = 0, \forall a_2 \notin \sigma_1$
We note that all strategies in a given support must be used in the mixed-strategy Nash equilibrium. The feasibility of this problem in comparison with the difficulty of finding Nash equilibria suggests that the main difficulty in finding Nash equilibria comes from the difficulty of searching through all possible combinations of supports for the action profiles in a game.
## Correlated Equilibrium
A correlated equilibrium is another type of equilibrium which is a superset of Nash equilibria. In addition to the strategies available to players, there can be a signal which allows players to coordinate their actions. A natural example of a correlated equilibirum is at a traffic junction. When the traffic light is red, drivers stop at an intersection, whereas if the light is green, they go on – this insures that there are no (or relatively few) traffic accidents. If there aren’t traffic signals, drivers must play a mixed strategy of going on and stopping in equilibrium, which would guarantee a non-trivial amount of accidents, given that people do drive with some probability.
More generally, a correlated equilibrium can be defined as follows:
A joint probability distribution $p^*$ on action profiles in A is a correlated equilibrium of a simultaneous-move game $(N,A,u)$ if for all agents $i$, and for actions $a_i \in A_i$ with $p^*(a_i) >0$
$\sum_{a_{-i}\in A_{\-i}} p^*(a_{-i} | a_i)u_i(a_i,a_{-i}) \geq \sum_{a_{-i}\in A_{-i}} p^*(a_{-i} | a_i) u_i (a_i',a_{-i})$
A Nash equilibrium is a special case of the correlated equilibrium, when $(p^*a_{-i}|a_i) = p^*(a_{-i})$. Interestingly, the generalization of Nash equilibrium to correlated equilibrium allows us to solve for equilibrium using an LP.
Maximize Any objective function
Subject to:
$\sum_{a_{-i}\in A_{\-i}} p^*(a_{-i} | a_i)u_i(a_i,a_{-i}) \geq \sum_{a_{-i}\in A_{-i}} p^*(a_{-i} | a_i) u_i (a_i',a_{-i})$
$\forall i \in N, \forall a_i \in A_i, \forall a_i' \in A_i$
$\sum_{a\in A} p(a) = 1$
$p(a) \geq 0, \forall a \in A$.
It is interesting to note that the independence of each player’s action in a Nash equilibrium breaks the linearity of the first constraint in the LP above. Hence, it is the representation of all players’ strategies as a joint distribution which allows us to compute correlated equilibrium quickly.
## Sources
This blog post draws heavily from the forthcoming book Economics and Computation by David C. Parkes and Sven Seuken. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 54, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8124924302101135, "perplexity": 508.58753985382873}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886109470.15/warc/CC-MAIN-20170821172333-20170821192333-00021.warc.gz"} |
http://starlink.eao.hawaii.edu/devdocs/sun211.htx/sun211ss395.html | ### Nout
Number of output coordinates for a Mapping
#### Description:
This attribute gives the number of coordinate values generated by a Mapping to specify each output point (i.e. the number of dimensions of the space in which the Mapping’ s output points reside).
Type:
#### Applicability
##### Mapping
All Mappings have this attribute.
##### CmpMap
If a CmpMap’ s component Mappings are joined in series, then its Nout attribute is equal to the Nout attribute of the second component (or to the Nin attribute of the first component if the the CmpMap’ s Invert attribute is non-zero).
If a CmpMap’ s component Mappings are joined in parallel, then its Nout attribute is given by the sum of the Nout attributes of each component (or to the sum of their Nin attributes if the CmpMap’ s Invert attribute is non-zero).
##### Frame
The Nout attribute for a Frame is always equal to the number of Frame axes (Naxes attribute).
##### FrameSet
The Nout attribute of a FrameSet is equal to the number of FrameSet axes (Naxes attribute) which, in turn, is equal to the Naxes attribute of the FrameSet’ s current Frame (as specified by the Current attribute). The Nout attribute value may therefore change if a new current Frame is selected. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5509992837905884, "perplexity": 3242.525273515876}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780058222.43/warc/CC-MAIN-20210926235727-20210927025727-00132.warc.gz"} |
http://au.mathworks.com/help/matlab/ref/fminsearch.html?s_tid=gn_loc_drop&nocookie=true | # fminsearch
Find minimum of unconstrained multivariable function using derivative-free method
## Syntax
`x = fminsearch(fun,x0)x = fminsearch(fun,x0,options)x = fminsearch(problem)[x,fval] = fminsearch(...)[x,fval,exitflag] = fminsearch(...)[x,fval,exitflag,output] = fminsearch(...)`
## Description
`fminsearch` finds the minimum of a scalar function of several variables, starting at an initial estimate. This is generally referred to as unconstrained nonlinear optimization.
`x = fminsearch(fun,x0)` starts at the point `x0` and returns a value `x` that is a local minimizer of the function described in `fun`. `x0` can be a scalar, vector, or matrix. `fun` is a `function_handle`.
Parameterizing Functions in the MATLAB® Mathematics documentation explains how to pass additional parameters to your objective function `fun`. See also Example 2 and Example 3 below.
`x = fminsearch(fun,x0,options)` minimizes with the optimization parameters specified in the structure `options`. You can define these parameters using the `optimset` function. `fminsearch` uses these `options` structure fields:
`Display` Level of display. `'off'` displays no output; `'iter'` displays output at each iteration; `'final'` displays just the final output; `'notify'` (default) displays output only if the function does not converge. See Iterative Display in MATLAB Mathematics for more information. `FunValCheck` Check whether objective function values are valid. `'on'` displays an error when the objective function returns a value that is `complex`, `Inf` or `NaN`. `'off'` (the default) displays no error. `MaxFunEvals` Maximum number of function evaluations allowed `MaxIter` Maximum number of iterations allowed `OutputFcn` User-defined function that is called at each iteration. See Output Functions in MATLAB Mathematics for more information. `PlotFcns` Plots various measures of progress while the algorithm executes, select from predefined plots or write your own. Pass a function handle or a cell array of function handles. The default is none (`[]`). `@optimplotx` plots the current point`@optimplotfval` plots the function value`@optimplotfunccount` plots the function countSee Plot Functions in MATLAB Mathematics for more information. `TolFun` Termination tolerance on the function value `TolX` Termination tolerance on `x`
`x = fminsearch(problem)` finds the minimum for `problem`, where `problem` is a structure with the following fields:
`objective` Objective function `x0` Initial point for `x` `solver` `'fminsearch'` `options` Options structure created using `optimset`
`[x,fval] = fminsearch(...)` returns in `fval` the value of the objective function `fun` at the solution `x`.
`[x,fval,exitflag] = fminsearch(...)` returns a value `exitflag` that describes the exit condition of `fminsearch`:
`1` `fminsearch` converged to a solution `x`. `0` Maximum number of function evaluations or iterations was reached. `-1` Algorithm was terminated by the output function.
`[x,fval,exitflag,output] = fminsearch(...)` returns a structure `output` that contains information about the optimization in the following fields:
`algorithm` `'Nelder-Mead simplex direct search'` `funcCount` Number of function evaluations `iterations` Number of iterations `message` Exit message
## Arguments
`fun` is the function to be minimized. It accepts an input `x` and returns a scalar `f`, the objective function evaluated at `x`. The function `fun` can be specified as a function handle for a function file
`x = fminsearch(@myfun, x0)`
where `myfun` is a function file such as
```function f = myfun(x) f = ... % Compute function value at x```
or as a function handle for an anonymous function, such as
`x = fminsearch(@(x)sin(x^2), x0);`
Other arguments are described in the syntax descriptions above.
## Examples
### Example 1
The Rosenbrock banana function is a classic test example for multidimensional minimization:
$f\left(x\right)=100{\left({x}_{2}-{x}_{1}^{2}\right)}^{2}+{\left(1-{x}_{1}\right)}^{2}.$
The minimum is at `(1,1)` and has the value `0`. The traditional starting point is `(-1.2,1)`. The anonymous function shown here defines the function and returns a function handle called `banana`:
`banana = @(x)100*(x(2)-x(1)^2)^2+(1-x(1))^2;`
Pass the function handle to `fminsearch`:
`[x,fval] = fminsearch(banana,[-1.2, 1])`
This produces
```x = 1.0000 1.0000 fval = 8.1777e-010```
This indicates that the minimizer was found to at least four decimal places with a value near zero.
### Example 2
If `fun` is parameterized, you can use anonymous functions to capture the problem-dependent parameters. For example, suppose you want to minimize the objective function `myfun` defined by the following function file:
```function f = myfun(x,a) f = x(1)^2 + a*x(2)^2;```
Note that `myfun` has an extra parameter `a`, so you cannot pass it directly to `fminsearch`. To optimize for a specific value of `a`, such as ```a = 1.5```.
1. Assign the value to `a`.
`a = 1.5; % define parameter first`
2. Call `fminsearch` with a one-argument anonymous function that captures that value of `a` and calls `myfun` with two arguments:
`x = fminsearch(@(x) myfun(x,a),[0,1])`
### Example 3
You can modify the first example by adding a parameter a to the second term of the banana function:
$f\left(x\right)=100{\left({x}_{2}-{x}_{1}^{2}\right)}^{2}+{\left(a-{x}_{1}\right)}^{2}.$
This changes the location of the minimum to the point `[a,a^2]`. To minimize this function for a specific value of `a`, for example a = `sqrt(2)`, create a one-argument anonymous function that captures the value of `a`.
```a = sqrt(2); banana = @(x)100*(x(2)-x(1)^2)^2+(a-x(1))^2;```
Then the statement
```[x,fval] = fminsearch(banana, [-1.2, 1], ... optimset('TolX',1e-8));```
seeks the minimum `[sqrt(2), 2]` to an accuracy higher than the default on `x`.
## Limitations
`fminsearch` can often handle discontinuity, particularly if it does not occur near the solution. fminsearch may only give local solutions.
`fminsearch` only minimizes over the real numbers, that is, x must only consist of real numbers and f(x) must only return real numbers. When x has complex variables, they must be split into real and imaginary parts.
collapse all
### Algorithms
fminsearch uses the simplex search method of Lagarias et al. [1]. This is a direct search method that does not use numerical or analytic gradients.
If `n` is the length of `x`, a simplex in `n`-dimensional space is characterized by the `n+1` distinct vectors that are its vertices. In two-space, a simplex is a triangle; in three-space, it is a pyramid. At each step of the search, a new point in or near the current simplex is generated. The function value at the new point is compared with the function's values at the vertices of the simplex and, usually, one of the vertices is replaced by the new point, giving a new simplex. This step is repeated until the diameter of the simplex is less than the specified tolerance.
## References
[1] Lagarias, J.C., J. A. Reeds, M. H. Wright, and P. E. Wright, "Convergence Properties of the Nelder-Mead Simplex Method in Low Dimensions," SIAM Journal of Optimization, Vol. 9 Number 1, pp. 112-147, 1998. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 2, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7193443775177002, "perplexity": 891.4202724021548}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-18/segments/1430451452451.90/warc/CC-MAIN-20150501033732-00095-ip-10-235-10-82.ec2.internal.warc.gz"} |
http://mathoverflow.net/questions/38382/how-can-i-visualize-the-nontrivial-element-of-pi-4s3-and-pi-5s3?sort=newest | # How can I visualize the nontrivial element of $\pi_4(S^3)$ and $\pi_5(S^3)$ ?
I've read in the textbooks that the non-trivial generator $\eta_n$ of $\pi_{n+1}(S^n)$ is the suspension of the Hopf map $S^3\to S^2$, and the generator $\chi$ of $\pi_5(S^3)$ is given by $\eta_3 \circ \eta_4$. Fine.
My question is, how I can visualize them? Is there a nice explicit way to describe these maps $\eta_3$ and $\eta_3\circ \eta_4$ ? How about the generator of $\pi_6(S^3)$ ?
(Other questions on MO look more serious. Hopefully this question is not out of place ...)
EDIT: anyone with rudimentary understanding of basic homotopy theory would say $\eta$ and $\eta\circ\eta$ are explicit enough, but I just can't visualize the suspension. I would be happy with a nice description of $SU(2)$ bundles over $S^n$, as my first exposure to homotopy is through quantum field theory...
Further edit: Thanks everyone for answers, I'm almost inclined to accept Per's answer, but I'm not still satisfied :p
-
Should it be on math.stackexchange.com instead? It's surely not a research-level question... – Yuji Tachikawa Sep 11 '10 at 4:34
Don't be so hard on your question. Visualization is an important tool for understanding, but one that is sometimes hard to get through the usual channels. I think there are many research mathematicians who could learn something from a good answer to this question; I know I look forward to reading the answers. – Tom Church Sep 11 '10 at 6:31
(This is a bit late, but I hope you find it interesting!)
Here's smooth representation of the generator of $\pi_4(Sp(1))$ (and so the same homotopy group of $S^3$ and $SU(2)$). Consider $S^4 = \mathbb{HP}^1$, and $Sp(1)$ the unit sphere in $\mathbb{H}$. Then the following function $t\colon \mathbb{HP}^4 \to Sp(1)$ represents the nontrivial homotopy class $S^4 \to S^3$: $$t[p;q] = \frac{2p\bar{q}i\bar{p}q - |p|^4 + |q|^4}{|p|^4 + |q|^4}$$ where [p;q] are homogeneous coordinates on $\mathbb{HP}^4$. I don't know if this has appeared previously (I would love to know!), but I presented this as part of some slides at the Australian Mathematical Society's annual conference last year (see slide 6), and originally worked it out with a pointer from Michael Murray to the Hopf fibration described using quaternions (that is, $Sp(1) \to S(Im\mathbb{H})$, the unit sphere in the pure imaginaries). That this map is the generator (i.e. is not null-homotopic) I calculated following the answer at my question Detecting homotopy nontriviality of an element in a torsion homotopy group.
Note that this function followed by the inclusion $Sp(1) \hookrightarrow Sp(2)$ (as the top left entry) is the generator of $\pi_4(Sp(2))$ (by results of Mimura and Toda). And thus we also get a representative for the generator of $\pi_4$ of $Spin(5) = Sp(2)$.
-
Through the Pontrjagin-Thom construction, a framed $n-k$ manifold in $S^n$ determines a map from $S^n$ to $S^{n-k}$. $\eta$ is represented by $S^1$ in $S^3$ with framing which "twists around once". The suspension of $\eta$ is represented by $S^1$ in $S^4$ lying in the equatorial $S^3$ with framing which is the product of this "twist once" framing within $S^3$ and the trivial framing in the normal direction, etc.
The composite is represented by an $S^1 \times S^1$ with a framing which is "twist around once" on each factor.
-
The $S^1$ that represents $\eta$ is unknotted, I guess? In that case, what do you get from other knots? – Mariano Suárez-Alvarez Sep 20 '10 at 16:00
@Mariano - the $S^1$ arises in the Pontryagin-Thom construction as the inverse image of a regular value of the map from $S^3$ to $S^2$. Homotopy classes of these maps are in correspondence with framed cobordism classes of links. Thus knottedness (or even number of components) of the inverse image is not a homotopy invariant, but "framing number" is. – j.c. Sep 22 '10 at 1:34
Is it possible to see that this generator when added to it is homotopic to zero? – Yuji Tachikawa Sep 27 '11 at 13:26
In the answer it should read "framed k-manifold". For the circle in $S^3$, how many normal framings are there? Well the framing can twist around any number of times, so you get $\mathbb{Z}$ many ($\pi_1 SO(2)$) and this corresponds to $\pi_3 S^2$. However when you suspend then there are only two ways to twists around, the trivial non-twisted way and the other way corresponding to $\pi_1(SO(n))$. – Chris Schommer-Pries May 17 '14 at 8:09
@Chris you can edit it, you know... – David Roberts May 17 '14 at 22:35
The main thing to visualize is the Hopf fibration of $S^2$, its suspensions, and their various compositions.
Let $f \colon S^3 \to S^2$ be the Hopf fibration.
When you suspend $f$ to get $g \colon S^4 \to S^3$, you effectively embed a 2-sphere as the equator of a 3-sphere and extend the mapping in parallel to 2-spheres of latitude. Thus away from the poles you still have circles as preimages.
You can see that $f$ and $g$ compose to give a map $h \colon S^4 \to S^2$. To get a sense of how this looks as a fibration, you can work backwards. First, the preimage of a point in $S^2$ under $f$ is a circle in $S^3$. As noted above, each pointwise preimage of this circle under the suspension $g$ is again generically a circle. When the different circles fit together cleanly, it looks like you get a torus fibration, where the tori twist and interlink within each latitudinal 3-sphere of $S^4$ analogously to the meshing of circles in $S^3$ for the Hopf fibration. If you now suspend this situation, you get a torus fibration over $S^3$ that looks like $h$ within each 2-sphere of latitude.
(I'm still not happy with this description but decided to post it in the hope it might spark some ideas.)
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Is there some simple argument that shows that this map is not null-homothopic? – Dmitri Sep 11 '10 at 18:19
You can read some John Baez
http://math.ucr.edu/home/baez/week102.html
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Thanks, but John only says it's the suspension... :p – Yuji Tachikawa Sep 11 '10 at 17:59
$S^3$ is isomorphic to $SO(3)$, which is a real Lie group and therefore is a differentiable and oriented real 3-fold, which has the double cover by $SU(2)$ which is the universal covering of $SO(3)$ or exponential of $su(2)$. Higher dimensional terms come from Bott's periodicity theorem. This is the QFT explanation.
In other words, thanks to the complex structure, we have a triangulation (approximation by CW (cell) complex attaching several n-dimensinal cell $e^n$ to a point set ${0}$, and Eilenberg-Steenrod axioms of singular homology of integral coefficient [with torsion module]). Then the textbook of Chern-Weil theory of characteristic class or some classic foliation (Postnikov tower of fibration) can tell you that there is a $E_2$ spectral sequence of double complex [see Bott-Tu GTM82, P.251-252] which is computable by exact sequence. This is the algebraic topology answer (non-simply connected space).
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I'm finding it hard to parse your answer! For instance, $SO(3)$ has $SU(2)$ as its double cover and not the other way around. What higher dimensional terms are you referring to and how does Bott periodicity come in? I can imagine referring to Bott's result about the cell structure of $\Omega G$ but that's not clear either. And nothing that you have said helps to visualize the higher homotopy elements. One, of course, knows that there are algebraic tools to compute what the referred elements are but that wasn't the question! – Somnath Basu Sep 20 '10 at 5:44
I thought Yuji wanted several other comments, but if he wanted geometric topology, I should mention lens space, which I am not working on. (Should I call it by Spin group?) I was considering whether I should write about loop group and DGA model, but it is outside of my reach today. (And I am not working on differential topology of exotic space today.) – Makoto Sep 20 '10 at 6:01
If you mean by "visualize" some graphs like string topology and higher category, you can see many pictures of Riemann surfaces, trees (operad), and braid groups. But I think it is not the ordinary mathematics based on logical algebra. Also, torsion part is not so difficult to handle and I didn't care about it. In my opinion, the "theoretical tool" is the jet space. – Makoto Sep 20 '10 at 21:25
You might want to revise the first sentence, since $S^3$ is isomorphic to $SU(2)$, not the quotient $SO(3)$. – S. Carnahan Sep 21 '10 at 5:59
It is not fair to revise my post after someone noticed it, though I found some difficulty with "complexification". – Makoto Sep 21 '10 at 6:56 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8389830589294434, "perplexity": 348.7034276409345}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-30/segments/1469257824624.99/warc/CC-MAIN-20160723071024-00007-ip-10-185-27-174.ec2.internal.warc.gz"} |
http://www.eoearth.org/view/article/51cbee0a7896bb431f695b1a/?topic=49987 | Health
Human Health Consequences of DDT Use
Topics: More
This review articleappeared first in Environmental Health Perspectivesthe peer-reviewed, open access journal of the'National Institute of Environmental Health Sciences.
The article is a verbatim version of the original and is not available for edits or additions by Encyclopedia of Earth editors or authors. Companion articles on the same topic that are editable may exist within the Encyclopedia of Earth.
The Pine River Statement: Human Health Consequences of DDT Use
This Review was authored by:
Brenda Eskenazi,1 Jonathan Chevrier,1 Lisa Goldman Rosas,1 Henry A. Anderson,2 Maria S. Bornman,3 Henk Bouwman,4 Aimin Chen,5 Barbara A. Cohn,6 Christiaan de Jager,7 Diane S. Henshel,8 Felicia Leipzig,9 John S. Leipzig,9,10 Edward C. Lorenz,9,11 Suzanne M. Snedeker,12 and Darwin Stapleton13
1School of Public Health, University of California, Berkeley, California, USA; 2Wisconsin Division of Public Health, Madison, Wisconsin, USA; 3Department of Urology, University of Pretoria, Pretoria, South Africa; 4School of Environmental Sciences and Development, North-West University, Potchefstroom Campus, Potchefstroom, South Africa; 5School of Medicine, Creighton University, Omaha, Nebraska, USA; 6Public Health Institute, Oakland, California, USA; 7School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa; 8School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana, USA; 9Pine River Superfund Citizen Task Force, St. Louis, Michigan, USA; 10Center for Responsible Leadership, and 11Public Affairs Institute, Alma College, Alma, Michigan, USA; 12Sprecher Institute for Comparative Cancer Research, Cornell University, Ithaca, New York, USA; 13Emeritus, Rockefeller University, New York, New York, USA
Abstract
Objectives: Dichlorodiphenyltrichloroethane (DDT) was used worldwide until the 1970s, when concerns about its toxic effects, its environmental persistence, and its concentration in the food supply led to use restrictions and prohibitions. In 2001, more than 100 countries signed the Stockholm Convention on Persistent Organic Pollutants (POPs) , committing to eliminate the use of 12 POPs of greatest concern. However, DDT use was allowed for disease vector control. In 2006, the World Health Organization and the U.S. Agency for International Development endorsed indoor DDT spraying to control malaria. To better inform current policy, we reviewed epidemiologic studies published from 2003 to 2008 that investigated the human health consequences of DDT and/or DDE (dichlorodiphenyldichloroethylene) exposure.
Data sources and extraction: We conducted a PubMed search in October 2008 and retrieved 494 studies.
Data synthesis: Use restrictions have been successful in lowering human exposure to DDT, but blood concentrations of DDT and DDE are high in countries where DDT is currently being used or was more recently restricted. The recent literature shows a growing body of evidence that exposure to DDT and its breakdown product DDE may be associated with adverse health outcomes such as breast cancer, diabetes, decreased semen quality, spontaneous abortion, and impaired neurodevelopment in children.
Conclusions: Although we provide evidence to suggest that DDT and DDE may pose a risk to human health, we also highlight the lack of knowledge about human exposure and health effects in communities where DDT is currently being sprayed for malaria control. We recommend research to address this gap and to develop safe and effective alternatives to DDT.
Key words: DDE, DDT, dichlorodiphenyldichloroethylene, dichlorodiphenyltrichloroethane, health effects, organochlorine pesticides, persistent organic pollutants.Environ Health Perspect 117:1359–1367 (2009) . doi:10.1289/ehp.11748 available via http://dx.doi.org/ [Online 4 May 2009]
Address correspondence to B. Eskenazi, School of Public Health, University of California, Berkeley, 2150 Shattuck Ave., Suite 600, Berkeley, CA 94720 USA. Telephone: (510) 642-3496. Fax: (510) 642-9083. E-mail: eskenazi@berkeley.edu
We thank S.R. Wyrobek and R.H. Weldon for their contributions.
This publication was supported in part by grant RD83171001 from the U.S. Environmental Protection Agency (EPA) and grants P01 ES009605 and R01 ES015572 from the National Institute of Environmental Health Sciences (NIEHS) .
The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, National Institutes of Health, or U.S. EPA.
F.L., J.S.L., and E.C.L. are members of the Pine River Superfund Citizen Task Force. E.C.L. also represents Alma College ; individuals at this institution may have been exposed to DDT contamination of the Pine River. The remaining authors declare they have no competing financial interests.
Received 30 May 2008 ; accepted 4 May 2009.
Introduction
Mixing DDT in the field. Source: U.S. Army.
Dichlorodiphenyltrichloroethane (DDT) is a potent insecticide that was used worldwide for agricultural and public health purposes from the 1940s until the 1970s, when concern about its toxic effects on wildlife and humans, its environmental persistence, and its concentration in the food supply led to restrictions and prohibitions on its use [Agency for Toxic Substances and Disease Registry (ATSDR) 2002]. Commercial mixtures, often called technical-grade DDT, contain two major isomers, the active ingredient, p,p´?DDT, and a by-product, o,p´?DDT. DDT and its primary breakdown product, dichlorodiphenyldichloroethylene (DDE), are highly lipophilic, persist in the environment, and bioaccumulate in humans because of their long half-lives (6 years and possibly up to 10 years, respectively) (Longnecker 2005; Wolff et al. 2000).
DDT was identified as a potent insecticide in 1939 and was heavily used during World War II. After the war, DDT became the global insecticide of choice in households, for agriculture, and for public health vector-control projects. In 1962, Rachel Carson, in Silent Spring, noted that DDT bioaccumulates and biomagnifies up the food chain and raised concerns that the pesticide may have long-lasting effects on wildlife and possibly on humans (Carson 1962).
In the United States, all nonpublic health uses of DDT were banned by 1972. Regulation by some other nations occurred more gradually. DDT continues to be used for malaria control in several African and Asian countries (Stockholm Convention on Persistent Organic Pollutants 2008). In 2001, more than 100 countries signed the Stockholm Convention on Persistent Organic Pollutants (POPs), committing to eliminate the use of 12 POPs of greatest concern to the health of the global community, including DDT (United Nations Environment Programme 2001). By 2008, 160 countries had ratified the Stockholm Convention, making it one of the most successful international environmental agreements (Stockholm Convention on Persistent Organic Pollutants 2008). Recognizing the continued need for DDT use in some countries, the convention allows the production and use of DDT for disease vector control only, provided that no safe, effective, and affordable alternatives are locally available. In these cases, the convention requires parties to notify the convention secretariat of their intention to produce and/or use DDT for vector control and to prevent or minimize human exposure and release into the environment. In 2006, the World Health Organization (WHO) and the U.S. Agency for International Development (USAID) endorsed indoor DDT spraying to control malaria (WHO 2006).
On 14 March 2008, researchers met for the Eugene Kenaga International DDT Conference, which was jointly organized by the Pine River Superfund Citizen Task Force, the Center for Responsible Leadership, and the Public Affairs Institute of Alma College with the endorsement of the International Society of Environmental Epidemiology, the Society for Environmental Toxicology and Chemistry, Alma College, and the Pine River Superfund Task Force. The goal of the conference was to bring together experts on DDT and concerned citizens to address the current and legacy implications of DDT production and use. This conference was held at Alma College, near the Velsicol Chemical Corporation U.S. Superfund site in Gratiot County, Michigan.
The purpose of this review is to summarize information on health risks so as to better inform risk–benefit analyses and policy. We do so by reviewing evidence of human exposure to DDT and some of its potential health consequences, focusing primarily on studies that have been published since the endorsement of DDT by WHO and USAID and since the publication of other literature reviews on the subject (Longnecker 2005; Rogan and Chen 2005). We conducted a search of PubMed (National Library of Medicine, Bethesda, MD, USA) to find human studies (excluding case reports) published in English from 2003 to 2008 by using the following search terms: (DDT OR DDE) AND (toxicity OR health OR cancer OR carcinogenicity OR reproduction OR estrogen OR neurological OR development OR exposure OR diabetes OR pregnancy OR miscarriage OR spontaneous abortion OR birth weight OR gestation OR lactation OR birth defects OR growth OR puberty OR fertility OR neurotoxicity OR neurodevelopment OR immunological). We identified 494 papers and reviewed them for primary research. On the basis of available data, we make recommendations regarding the introduction, continuation, or reintroduction of DDT use worldwide. These recommendations represent the consensus opinion of the authors and participants present at the Eugene Kenaga International DDT Conference.
Potential for Human Exposure
Environmental and biological monitoring studies in the United States demonstrate that use restrictions were successful in lowering human exposure to DDT. Estimated dietary intake of DDT dropped > 200% between 1970 and 1986 (ATSDR 2002), whereas serum DDT concentrations declined 9-fold between 1980 and 2000 [Centers for Disease Control and Prevention (CDC) 2003; Murphy et al. 1983]. Recent studies in the United States report low concentrations of DDT and DDE in food (U.S. Food and Drug Administration 2002) and in house dust and soil (Bradman et al. 1997; Butte and Heinzow 2002). Yet nearly all U.S. residents have measurable serum p,p´?DDE levels, whereas p,p´?DDT is detected in 5–10% of the population (CDC 2005).
A sample of recent studies of DDT/DDE serum levels in pregnant women and women of reproductive age shows the different exposure scenarios around the world. In this sample of studies, low concentrations were observed in U.S. women of reproductive age participating in the 2001–2002 wave of the National Health and Nutrition Examination Survey (NHANES; Table 1). The median DDE serum concentration was 10-fold higher in a population of primarily Mexican immigrant women living in an agricultural area of California where half of the women had immigrated within the previous 5 years (Bradman et al. 2007). DDE concentrations in this Mexican-American cohort were similar to those of a concurrent population living in Morelos, Mexico, where DDT probably had not been used for some time (Torres-Sanchez et al. 2007). However, median DDE serum concentrations in women residing in Chiapas, Mexico, where DDT may have been used up until 2000, were about five times higher in 1998 (Koepke et al. 2004) than in Morelos (Torres-Sanchez et al. 2007) and within the range observed in older studies from the United States when DDT was still being used (Bhatia et al. 2005; Gladen et al. 2004; Longnecker et al. 2005). However, the concentrations in pregnant women in Chiapas are still orders of magnitude lower than those reported in a study of South African men whose houses were sprayed with DDT as part of indoor residual spraying programs (mean blood DDE concentration = 239 ± 215 µg/g lipid) (Aneck-Hahn et al. 2007). Other studies conducted in South Africa also reported very high levels of DDT/DDE in breast milk (Bouwman et al. 1994, 2006). It may be that the pattern of use and/or formulation of DDT for malaria control differed in Chiapas and South Africa. Nevertheless, these data suggest that indoor residual spraying results in high DDT exposure in humans, including vulnerable populations, such as pregnant women and fetuses.
Evidence for Carcinogenicity and Cancer in Humans
In 1991, the International Agency for Research on Cancer (IARC) rated DDT as “possibly carcinogenic to humans (Group 2B)” (IARC 1991). This rating was largely based on the induction of liver tumors in experimental animal studies that reported significant increases in hepatomas (neoplastic liver cell tumors) in multiple strains of male and female rodents exposed to technical DDT orally (gavage or diet) or to p,p´?DDE (diet) (IARC 1991). Most human studies reviewed by IARC in 1991 did not show an association between DDT exposure and cancer risk. Some studies suggested that DDT exposure may be associated with certain cancers (lung cancer and lymphomas); however, the lack of control for exposure to other chemicals, small study size, insufficient data on confounding factors (e.g., incomplete information on tobacco use), and short follow-up time for long-latency cancers limited the ability to make any conclusions at that time (IARC 1991). Research on DDT/DDE exposure and cancer continued to yield mixed results after the publication of the IARC report. We review the recent research with a focus on cancers of the liver, pancreas, and breast.
Liver cancer. In an ecologic study, Cocco et al. (2000) found that standardized mortality rates (SMRs) for liver cancer were elevated in whites but not in African Americans who lived in states with high population-level adipose tissue DDE concentrations. These researchers offered no explanation for this racial difference. In a case–control study, McGlynn et al. (2006) reported that the risk of liver cancer was significantly elevated in Chinese men with the highest blood levels of DDT [odds ratio (OR) = 3.8; 95% confidence interval (CI), 1.7–8.0] compared with men with lower levels of DDT. Blood levels of DDE were not associated with a higher risk.
Pancreatic cancer.Mechanistic data suggest that DDT could play a role in pancreatic cancer by modulating activation of the oncogene K-ras (Porta et al. 1999). An association of workplace exposure to DDT and the risk of pancreatic cancer is supported by two studies. In a cohort of 5,886 DDT manufacturing plant workers, Garabrant et al. (1992) reported a 7.4-fold higher risk of pancreatic cancer deaths in workers exposed to DDT for an average of 47 months, as determined using work records and interviews with coworkers, compared with workers who had no exposure. Similarly, deaths from pancreatic cancer were significantly higher in a cohort occupationally exposed to DDT compared with a control cohort in an Australian study with follow-up data from 1935 to the 1990s (SMR = 3.57; 95% CI, 1.09–15.40) (Beard et al. 2003). In contrast, other studies have found no association between estimates of DDT exposure among workers (Cocco et al. 2005) or serum/adipose tissue levels of p,p´?DDE and pancreatic cancer risk after adjustment for confounders (Hardell et al. 2007; Hoppin et al. 2000). It has been suggested that the etiology of pancreatic cancer may be causally linked to diabetes mellitus and hyperinsulinemia (Michaud 2004) and thus linked to associations between DDT and diabetes (see below).
Breast cancer. Although neither DDT nor DDE induced mammary tumors in laboratory animal cancer bioassays (IARC 1991), early studies suggested that DDE levels in women were associated with a higher risk of breast cancer (Snedeker 2001). Two recent case–control studies (Charlier et al. 2004; Rubin et al. 2006) also showed higher DDE blood concentrations in cases than controls. However, most case–control studies recently published and reviewed have not supported an association (Brody et al. 2004; Gatto et al. 2007; Ibarluzea et al. 2004; Iwasaki et al. 2008; Lopez-Cervantes et al. 2004; Siddiqui et al. 2005; Snedeker 2001).
The literature on DDT and breast cancer has two main limitations. First, most studies used biological samples collected well after exposure to technical DDT had occurred and relied on serum concentrations of p,p´?DDE as a proxy for exposure to “DDT.” Second, most studies included women who would not have been exposed to technical DDT when young, yet both animal (Birnbaum and Fenton 2003) and human studies of radiation exposure (Howe and McLaughlin 1996; Tokunaga et al. 1994) strongly suggest that the breast is most vulnerable to environmentally induced carcinogenesis during several critical periods such as in utero, before menarche, and before first pregnancy.
Overcoming these past limitations, Cohn et al. (2007) measured concentrations in archived serum samples collected between 1959 and 1967 (peak years of DDT use) from pregnant women participating in the Child Health and Development Studies (CHDS). Medical records were obtained nearly 40 years later. Among women who were ? 14 years of age by 1945 (when DDT was first introduced for use by the general public), those with blood concentrations in the highest tertile were five times more likely to develop breast cancer than those with blood levels in the lowest tertile (OR = 5.4; 95% CI, 1.7–17.1). However, there was no association between serum p,p´-DDT levels and adult risk of breast cancer among women who were not exposed before 14 years of age, and interaction by age in 1945 was statistically significant. This study suggests that the prepubertal and pubertal years are critical periods of exposure. Thus, previous studies that measured exposure in older women may have missed the critical period.
Other cancers.Research has not supported an association of DDT or DDE and incidence of colorectal, lung, bladder, prostate, endometrial, and stomach cancers (Baris et al. 1998; Cocco et al. 2005; Hardell et al. 2004; Howsam et al. 2004; Purdue et al. 2007; Sturgeon et al. 1998; Weiderpass et al. 2000). Although no associations were found with serum DDT (Rothman et al. 1997), higher DDE levels in dust, adipose tissue, and plasma have been associated with non-Hodgkinlymphoma in case–control studies (Colt et al. 2005; Quintana et al. 2004; Spinelli et al. 2007). For other cancers, such as leukemia (Flodin et al. 1988; Purdue et al. 2007), and testicular cancer (Hardell et al. 2006; McGlynn et al. 2008), evidence remains equivocal.
Evidence for Diabetes
Since Morgan et al.’s (1980) initial observation that the sum of DDT and DDE levels in serum was 29% higher in occupationally exposed workers with diabetes compared with nondiabetics, a number of other studies have been published on this subject. For example, data from the 1999–2002 NHANES suggested that elevated serum concentrations of p,p´?DDT (Everett et al. 2007) and p,p´?DDE (Lee et al. 2006) were significantly associated with the prevalence of diabetes. In addition, Lee et al. (2006) reported an increasing trend in the odds of diabetes as exposure to p,p´?DDE increased (ptrend < 0.001) with an OR of 4.3 (95% CI, 1.8–10.2) for those ? 90th percentile of exposure compared with those in the lowest quartile.
Because diabetes occurs in Mexican Americans twice as frequently as in non- Hispanic whites (Haffner 1998), and serum levels of p,p´?DDE and p,p´?DDT are higher in Mexican Americans than other ethnic groups in the U.S. population (CDC 2001), data from the Hispanic Health and Nutrition Examination Survey (HHANES) for 1982–1984 were analyzed. Serum p,p´?DDT or p,p´?DDE levels were dose related to the prevalence of self-reported diabetes in Mexican Americans (Cox et al. 2007). Additionally, in a study of Native Americans (Mohawks), Codru et al. (2007) observed a significant positive association between diabetes prevalence and serum levels of p,p´?DDE.
A Swedish study found that diabetes prevalence was significantly higher (ptrend = 0.04) in Baltic Sea fishermen with elevated serum DDE levels (Rylander et al. 2005), but not in their wives. With a larger study population (nonfisherman families), the same authors reported a significant positive association (ptrend < 0.01) between type 2 diabetes and serum p,p´-DDE levels in Swedish women (Rignell-Hydbom et al. 2007).
Collectively, these studies from the United States and Sweden suggest that body burdens of DDT and/or DDE may be associated with the prevalence of diabetes. A variety of other persistent environmental chemicals also have been associated with diabetes prevalence (Lee et al. 2006). However, given the high correlation among various organochlorine exposures (Bradman et al. 2007), additional research is needed to delineate the specific contributions of DDT and DDE.
Evidence for Health Consequences to the Fetus
Pregnancy loss.In the U.S. Collaborative Perinatal Project (CPP), where the median maternal serum DDE level was 24.5 µg/L, high DDE concentrations (45–59 vs. < 15 µg/L) were associated with an increased risk of fetal loss in previous pregnancies (Longnecker et al. 2005). Although the outcome occurred before DDE measurement, this study of 1,717 women corroborated findings from smaller studies (Korrick et al. 2001; Saxena et al. 1981). Venners et al. (2005) studied 338 nulliparous Chinese textile workers with similar DDE concentrations (median, 29 ng/g serum) for the risk of early pregnancy loss (measured by daily human chorionic gonadotropin). Authors reported an OR of 1.17 (95% CI, 1.05–1.29) for each 10?ng/g serum increase in total DDT. In a case– control study of habitual aborters, researchers did not observe higher mean serum DDE levels in cases relative to controls (Sugiura-Ogasawara et al. 2003).
Gestational length and birth weight. Early studies on DDE and preterm delivery (< 37 weeks of gestation) were small, and results were inconsistent (Berkowitz et al. 1996; O’Leary et al. 1970; Saxena et al. 1981; Wassermann et al. 1982). Studies using data from larger cohorts also have not consistently supported an association between exposure to DDT/DDE and birth weight or gestational duration. In a study of 2,380 pregnant women participating in the CPP, Longnecker et al. (2001) found that the odds of preterm delivery were 3.1 times higher (95% CI, 1.8–5.4) in women with serum DDE ? 60 µg/L compared with those with DDE < 15 µg/L during pregnancy. Adjusted odds of having a child small for gestational age also increased, but less consistently (ptrend = 0.04). However, two analyses of the CHDS, which was conducted around the same time as the CPP, have found no associations of DDT/DDE and preterm delivery or small for gestational age, despite slightly higher median DDE levels than in the CPP (43 vs. 25 µg/L) (Farhang et al. 2005; Jusko et al. 2006).
Most studies of more recent cohorts, which had somewhat lower exposure than those in the earlier studies, did not find an association between maternal serum measurements of DDE and/or DDT and gestational duration, premature labor, birth weight, or other measures of fetal growth such as crown–heel length or head circumference (Bjerregaard and Hansen 2000; Fenster et al. 2006; Gladen et al. 2003; Karmaus and Zhu 2004; Khanjani and Sim 2006; Sagiv et al. 2007; Wood et al. 2007), although some studies did find associations (Siddiqui et al. 2003; Weisskopf et al. 2005; Wolff et al. 2007). The high DDE serum concentrations observed in the CPP and CHDS cohorts during the 1960s are several-fold higher than current serum levels, but substantially lower than in populations where indoor residual spraying is occurring.
Duration of lactation. Two studies have found a shorter duration of lactation among mothers with high breast milk DDE concentrations (Gladen and Rogan 1995; Rogan et al. 1987). A North Carolina study of 858 women indicated that higher breast milk DDE concentrations were associated with a shorter median duration of lactation (2.5 months for DDE > 6 µg/g lipids vs. 6.5 months for DDE < 1 µg/g lipids) (Rogan et al. 1987). A study of 229 Mexican women found similar results (Gladen and Rogan 1995), but only among women who had previously lactated. Estrogenic effects of DDT were postulated to affect prolactin levels and milk production (Gladen and Rogan 1995; Rogan et al. 1987). A more recent study suggested that DDE serum concentrations were related to decreased rates of breast-feeding initiation as well as shortened duration of lactation in women who had never breast-fed and in nonsmoking women (Karmaus et al. 2005b), but a Mexican study found that serum DDE was associated with duration of lactation only in women who previously breast-fed (Cupul-Uicab et al. 2008). In this Mexican study of 784 mothers of male term babies, the hazard ratio of weaning for women with high serum DDE levels (cutoff point, 9 µg/g lipids) was 1.76 (95% CI, 1.22–2.53) in women who had previously breast-fed and 0.91 (95% CI, 0.66–1.26) in women who had never breast-fed. Previous lactation can reduce the maternal body burden of DDE, and women who breast-feed longer for previous infants tend to do so for the current baby. Thus, associations between DDE levels and early weaning may be spurious, and further research is warranted.
Urogenital birth defects. Studies in rats have suggested a relationship between fetal tissue concentrations of 10–20 ppm of p,p´?DDE and reproductive abnormalities in male offspring (Gray et al. 2001). In the CPP birth cohort, Longnecker et al. (2002) reported ORs of 1.07 (95% CI, 0.97–1.18) for cryptorchidism (n = 219), 1.01 (95% CI, 0.90–1.14) for hypospadias (n = 199), and 1.06 (95% CI, 0.97–1.16) for polythelia (n = 167) for each 2.67 µg/g lipid increase in maternal serum p,p´-DDE (Longnecker et al. 2002). However, in the CHDS birth cohort, Bhatia et al. (2005) found that the odds of cryptorchidism were twice as high in participants with p,p´-DDT levels above versus below the median (OR = 1.97; 95% CI, 1.40–2.54) but found no associations between maternal serum p,p´?DDE and the odds of cryptorchidism, or between p,p´?DDT and p,p´?DDE concentrations and odds of hypospadias. A Spanish study also reported more than a doubling of the odds of cryptorchidism and/or hypospadias cases associated with detectable levels of p,p´?DDT (OR = 2.63; 95% CI, 1.21–5.72) and o,p´?DDT (OR = 2.25; 95% CI, 1.03–4.89) measured in placental tissues (Fernandez et al. 2007). Other studies conducted in France (Brucker-Davis et al. 2008) and in Finland and Denmark (Damgaard et al. 2006) reported increased colostrum levels of p,p´?DDE, and elevated breast milk concentrations of p,p´?DDT, o,p´?DDT, p,p´?DDE, and p,p´?dichlorodiphenyldichloroethane (DDD), respectively, in cases of cryptorchidism compared with controls, although associations were not statistically significant.
Child growth.Evidence for an association between physical growth after birth and DDT and DDE exposure is inconsistent. Maternal DDT concentrations were not associated with child weight or height at 5 years of age in children participating in the CHDS (Jusko et al. 2006). In contrast, those who had the highest prenatal concentrations of DDE in the CPP cohort (? 60 µg/L) compared with the lowest (< 15 µg/L) were significantly shorter at 1, 4, and 7 years of age (Ribas-Fito et al. 2006a). However, a study that examined growth in adolescent boys participating in the CPP found no relation between maternal serum levels of DDE or DDT in pregnancy and height, body mass index (BMI), and other measures of growth (Gladen et al. 2004). Two other studies in older children and in populations with much lower serum levels reported conflicting findings: A study from Germany found shorter height in 8-year-old girls in relation to higher DDE concentration (Karmaus et al. 2002), and an older North Carolina study found a relation to taller height in boys 12–14 years of age (Gladen et al. 2000). Overall, the evidence for the relation of maternal DDT exposure and child physical growth is weak.
Evidence for Reproductive Effects
Age of onset of puberty. A small number of human studies have examined DDT/DDE and onset of menarche in girls, with two studies finding associations of earlier age at menarche with higher exposure (Ouyang et al. 2005; Vasiliu et al. 2004) and one study finding no association (Denham et al. 2005). Ouyang et al. (2005) found that women with higher serum levels of total DDT (i.e., the sum of p,p´- and o,p´?isomers of DDT, DDE, and DDD) measured in adulthood (mean age, 24.9 years) reported significantly earlier age at onset of menarche, adjusting for BMI and birth year. In contrast, Denham et al. (2005) found no association between concurrent DDE blood concentrations [geometric mean (GM) = 0.35 ppb] and menarcheal status among 138 Mohawk girls 10–16.9 years of age. Vasiliu et al. (2004) estimated serum DDE levels during pregnancy in 151 women by back-calculating from measurements made up to 25 years later. They reported that higher (estimated) prenatal DDE levels were associated with earlier age at menarche in daughters (adjusted ? = –0.07, p = 0.04).
Two studies examined onset of puberty rather than menarche in relation to DDE exposure. Gladen et al. (2000) found no association between transplacental or lactational DDE concentrations and pubertal stage as self-reported in a cohort of approximately 315 adolescent girls with relatively high exposure (range, 0.3–25.8 ppm). Wolff et al. (2008) performed Tanner exams on approximately 80 9-year-old girls and found no difference in concurrent DDE plasma levels in those girls who had reached Tanner breast stage 2 (onset of puberty) and those who did not, but DDE levels were low. Only one study has examined onset of puberty in boys. Gladen et al. (2000) found no association between DDE and self-reported Tanner staging in boys up to 16 years of age. All these studies examined associations with DDE and not DDT.
Although these studies of puberty and menarche suggest an association with exposure, no study has examined the relationship of serum levels of DDE and DDT concentrations in blood collected before puberty in relation to Tanner staging in girls or boys.
Male fertility.Researchers have investigated the seminal parameters of men living in regions of high DDT use. In one such study (de Jager et al. 2006), participants were drawn from rural communities in the malaria-endemic region of Chiapas, Mexico, with a history of high use and where DDT was sprayed inside their homes at least annually from the late 1940s until 1997 (Stapleton 1998); sampling took place between 2000 and 2001. The mean serum DDE concentration (45 ± 31 µg/g lipids) was 100 times higher than reported in unexposed populations. The percentage of motile sperm was negatively correlated with plasma DDE concentrations, whereas the percentage of sperm with morphologic tail defects and insufficient sperm chromatin condensation was positively correlated with these levels (de Jager et al. 2006).
In a study conducted in Limpopo, South Africa, men were selected from rural communities in a malaria-endemic area where DDT is sprayed annually inside unpainted houses, but not inside painted houses (Aneck-Hahn et al. 2007). The GM serum concentrations of DDT (90.2 ± 102.4 µg/g) and DDE (215.5 ± 210.6 µg/g) in the 311 participants from this area were extremely high. DDT and DDE serum concentrations were also significantly higher (p < 0.001) in participants whose houses were sprayed with DDT (101.9 µg/g lipid DDT and 239.0 µg/g lipid DDE) compared with those whose houses were not sprayed (30.5 µg/g lipid DDT and 99.5 µg/g lipid DDE). Their semen volume was low (1.9 ± 1.3 mL) and several sperm motion parameters were impaired, including the percentage of motile sperm in men with higher DDT (r = –0.27, p < 0.001) and DDE concentrations (r = –0.20, p < 0.001). In another cross-sectional study of 48 DDT applicators (Dalvie et al. 2004) conducted in Limpopo, overall semen quality was low, and DDT, but not DDE, serum levels were associated with decreased sperm count.
Studies of semen quality or genetic markers in sperm have been conducted in other populations, usually with lower exposure than noted in Chiapas or South Africa. For example, case–control studies of men of subfertile couples have found no difference in the men’s DDE serum levels (Charlier and Foidart 2005) but higher current blood levels in the mothers of the cases compared with controls, and no association with DNA integrity (neutral comet assay) (Hauser et al. 2003). Similarly, the multinational (Greenland; Warsaw, Poland; Kharkiv, Ukraine; and Sweden) INUENDO study of European and Inuit pregnant women and their spouses failed to find associations of DDE serum levels and conventional measures of semen quality (Toft et al. 2006), chromatin integrity (Spano et al. 2005), and hormone levels or a measure of apoptosis (Stronati et al. 2006). However, as in many populations where exposure to several organochlorines, including polychlorinated biphenyls, may be highly correlated, independent associations with DDE often could not be established.
Overall, studies of highly exposed populations suggest that male fertility may be adversely affected by DDT exposure, but studies in populations with moderate to low exposure levels do not support a relationship between exposure and male fertility outcomes.
Female reproduction, fertility, and time to conception. Two recent studies examined the relationship of DDT/DDE levels and menstrual cycle characteristics and found only weak associations (Chen et al. 2005; Cooper et al. 2005). However, one study from the INUENDO population reported a 3?fold increase in risk of long menstrual cycles among Polish women but not among women from other European countries (Toft et al. 2008). Another study using data from the Hispanic Health and Nutrition Examination Survey found that both DDT and DDE levels were associated with a significantly earlier age of menopause (Akkina et al. 2004).
Two cross-sectional studies found suggestive evidence that p,p´?DDE serum levels in pregnant women were correlated with delays in conception (Axmon et al. 2006; Law et al. 2005), but another study in Mexican-American women did not find a relation with either p,p´?DDT or p,p´?DDE serum levels (Harley et al. 2008). One of these studies (Axmon et al. 2006) also examined paternal serum p,p´?DDE and found no effects on partners’ time to pregnancy. In contrast, a study of 105 male DDT applicators found that p,p´?DDE exposure, estimated by occupation history, was associated with delayed time to pregnancy in their spouses, defined using marriage dates and birth dates of first-born children (Cocco et al. 2005).
The only study to examine in utero exposure to DDT and time to pregnancy was conducted among 289 women born in California between 1960 and 1963 (CHDS). Authors found that each 10?µg/L increase in mothers’ serum concentrations of p,p´?DDT and p,p´?DDE during pregnancy was associated with a 32% reduction and a 16% increase, respectively, in their daughters’ per cycle probability of pregnancy (Cohn et al. 2003). The ratio of these two compounds varied considerably, and longer time to pregnancy in daughters was observed as the ratio of p,p´?DDT to p,p´?DDE increased in maternal serum samples. Findings suggest that recent exposure or direct exposure to the pesticide, rather than chronic exposure to p,p´?DDE in the food chain, was the underlying risk factor.
Overall, the few studies conducted to date suggest that DDT exposure may affect time to pregnancy, but more research is needed.
Evidence for Neurodevelopmental Effects
DDT exerts its insecticidal effects by disrupting the nervous system. Animal studies confirm that DDT is a neurodevelopmental toxicant (ATSDR 2002). In mice, exposure to DDT timed to sensitive periods of prenatal (Craig and Ogilvie 1974) and neonatal (Eriksson and Nordberg 1986; Eriksson et al. 1990; Johansson et al. 1996) nervous system development has been shown to cause behavioral and neurochemical changes into adulthood.
The few studies conducted in humans have focused primarily on exposure to DDE rather than DDT. In a North Carolina birth cohort recruited in the 1980s, Rogan et al. (1986) reported that maternal serum and breast milk DDE levels were related to hyporeflexia in a dose-dependent fashion in infants assessed by the Brazelton Neonatal Behavioral Assessment Scale (BNBAS), but this finding has not been replicated in more recent studies (Engel et al. 2007; Fenster et al. 2006; Stewart et al. 2000). In a recent investigation from Massachusetts, DDE measured in cord blood was negatively related to BNBAS measures of alertness and attention and positively related to measures of irritability, although only the trend for irritability was significant (Sagiv et al. 2008).
The North Carolina study reported no adverse association between perinatal DDE exposure and performance on the Bayley Scales of Infant Development (BSID) from 6 to 24 months of age (Gladen et al. 1988; Rogan and Gladen 1991); on the McCarthy Scales of Children’s Abilities (MCSA) at ages 3, 4, and 5 years; or on school performance at 8–10.5 years (Gladen and Rogan 1991). Similarly, a study conducted in Oswego, New York, found no association of DDE levels and performance on the Fagan Test of Infant Intelligence at 6 and 12 months of age (Darvill et al. 2000). However, a smaller Spanish study (Ribas-Fito et al. 2003) of 92 infants 13 months of age found a significant negative association between relatively low cord serum DDE levels and cognitive, psychomotor, and social development on the BSID and Griffith Scales of Infant Development. Similarly, a study of 230 infants from Mexico found that maternal serum DDE levels were inversely associated with psychomotor development scores on the BSID at 3, 6, and 12 months (Torres-Sanchez et al. 2007). Using the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort of Mexican-American children, Eskenazi et al. (2006) also reported an inverse association of maternal serum DDE and psychomotor development at 6 and 12 but not at 24 months, and with mental development at 24 months.
In a small study measuring visual evoked potentials (VEPs) in 12-month-olds (Riva et al. 2004), wave latency VEPs at 15 min were significantly related to the colostral levels of both DDT and DDE, and wave latency VEPs at 60 min were related to levels of DDT. However, findings were no longer statistically significant after authors controlled for the plasma levels of long-chain polyunsaturated fatty acids, thought to be one of the beneficial components of breast milk for brain development. The authors concluded that breast-feeding in itself may exert a protective effect against contaminants in human milk.
Only two studies have examined the relationship of DDT levels and cognitive functioning. Increased maternal serum DDT levels were associated with poorer psychomotor development at 6, 12, and 24 months and mental development at 12 and 24 months in the CHAMACOS cohort (Eskenazi et al. 2006). Breast-feeding did not have a negative relationship with mental development in the group with the highest maternal DDT levels. In another study, cord serum DDT levels were also found to be associated with poorer performance in general cognitive, memory, quantitative, verbal, and executive function domains of the MCSA in 4- and 5-year-old children in Spain (Ribas-Fito et al. 2006b).
These studies suggest that DDT, and less so DDE, may be associated with neurodevelopmental deficits. In addition, breast-feeding may modulate some of the negative effects of DDT, but this needs to be examined when exposure is high such as in communities where indoor residual spraying is occurring. Follow-up studies of these populations are needed to verify whether these developmental deficits persist.
Evidence for Other Health Effects
Although thyroid hormones are essential for normal brain development (Dunn 1993), studies suggest that DDE, and possibly DDT, may depress triiodothyronine (T3) and/or thyroxine (T4) in maternal, cord, and preschool children’s blood (Abdelouahab et al. 2008; Alvarez-Pedrerol et al. 2008; Asawasinsopon et al. 2006; Maervoet et al. 2007; Takser et al. 2005) but not entirely consistently (Chevrier et al. 2008). Higher DDT levels were also found in cases of congenital hypothyroidism relative to controls (Nagayama et al. 2007a). Results from studies conducted in men and nonpregnant women have generally been inconsistent. Two of these studies reported a positive association between serum DDE and thyroid-stimulating hormone (TSH) concentrations (Meeker et al. 2007; Rylander et al. 2006), one found a positive correlation between DDE and total T3 (Langer et al. 2007a), whereas other studies found no associations between DDE and TSH (Langer et al. 2005, 2006, 2007a, 2007b; Turyk et al. 2006), total T3 or the free T4 index (Turyk et al. 2006).
DDT and particularly DDE have demonstrated the potential for modulating the human immune response as measured by multiple markers such as interleukin-4 (Daniel et al. 2002) and interleukin-13 (Brooks et al. 2007), plasma levels of type 1 (interferon-?) response to mitogen in nursing mothers, white blood cell counts, and various lymphocyte phenotypes (Nagayama et al. 2007b; Noakes et al. 2006; Vine et al. 2001), and immunoglobulin (Ig) A, G, and E levels (Cooper et al. 2004; Karmaus et al. 2005a). Associations with immune system–related conditions such as aplastic anemia (with DDT but not DDE) (Ahamed et al. 2006; Issaragrisil et al. 2006), asthma (with DDE) (Karmaus et al. 2001; Sunyer et al. 2005), otitis media (with DDE) (Dallaire et al. 2004), and farmer’s lung (with technical DDT use) (Hoppin et al. 2007) were also reported. In children, one cross-sectional study of German schoolchildren found that DDE levels in blood were associated with increased IgE blood levels and asthma (Karmaus et al. 2001). A longitudinal study of 405 Spanish children confirmed the association between DDE exposure and asthma, but found that DDE was not associated with IgE levels (Sunyer et al. 2005). Additional research is needed to understand the effects of DDT/DDE on the immune system and associated diseases, especially because DDT is used in areas where there are often high rates of HIV.
Conclusions
The use of DDT historically may have helped prevent millions of infections and deaths from insect-borne diseases. Based on recent studies, we conclude that humans are exposed to DDT and DDE, that indoor residual spraying can result in substantial exposure, and that DDT may pose a risk for human populations. However, few studies have measured body burdens of both DDE and DDT, and studies have rarely investigated the effects of DDT/DDE exposure at levels observed in populations exposed through indoor residual spraying. Furthermore, information on exposure to DDT/DDE during critical periods is limited for outcomes such as cancer.
We are concerned about the health of children and adults given the persistence of DDT and its active metabolites in the environment and in the body, and we are particularly concerned about the potential effects of continued DDT use on future generations. We recognize the serious implications of restricting DDT use given that an estimated 880,000 people die each year from malaria, most of whom are < 5 years of age (WHO 2008). Given our continually deepening understanding of the effects of DDT use on humans, we ask global policy makers to consider the following issues:
• In the United States, individuals have been exposed to DDT by working in occupational settings and by living in proximity to DDT manufacturing facilities. State and federal agencies should monitor levels of contaminants in residents near Superfund sites (e.g., Pine River/Velsicol Chemical Corp. Michigan Superfund site) and conduct health effects studies if biomonitoring indicates persistently elevated levels of DDT or DDE.
• Few studies of health outcomes have been conducted in populations where indoor residual spraying with DDT is occurring. These populations likely have much higher exposures to DDT and may differ from those previously studied in ways that might affect susceptibility (e.g., genetics, diet, health status, and social class). Research is needed to determine the exposure and health risks associated with DDT used for indoor residual spraying in the relevant communities.
• Children, pregnant women, and those who are immunocompromised may be most at risk for the effects of DDT. People in many malaria-endemic areas where DDT is being used also have high rates of HIV/AIDS infection.
• Breast-feeding is the best form of nutrition for infants and is recommended up to at least 1 year of age by the American Academy of Pediatrics (2005). In some African countries, women may breast-feed for up to 2 years. However, because of the lipophilic nature of DDT/DDE, breast milk is a major route of DDT/DDE exposure to infants. Significant public health consequences could ensue should breast-feeding be discouraged as a result of high DDT contamination.
• DDT may be a valuable short-term approach for controlling malaria, but measures should be taken to reduce human exposure to this pesticide. DDT exposure could conceivably be reduced through strict adherence to indoor residual spraying guidelines, better education of communities and applicators regarding the potential hazards of DDT exposure, improved application methods and formulations, and a better understanding of the determinants of exposure.
• New methods of vector control should be developed and rigorously tested considering local differences such as in vectors, parasites, ecology, and culture. As is the case for DDT, new methods for vector control should be evaluated not only for their effectiveness, but also for their potential adverse effects on the environment and populations, including to susceptible subpopulations such as those who are immunocompromised and malnourished. For example, pyrethroids have been substituted for DDT in indoor residual spraying in some locations, yet there is little information on their effects to human health.
Current evidence on DDT exposure to human populations and on its potential health effects support the Stockholm Convention on Persistent Organic Pollutants, which emphasizes that DDT should be used with caution, only when needed, and when no other effective, safe, and affordable alternatives are locally available. Under the convention, each country currently using DDT is required to provide an implementation and management plan to limit the use of DDT to disease vector control and to reduce reliance on DDT. Countries should be assisted so that they can ultimately rely on other sustainable methods, techniques, and strategies for malaria control. Given the paucity of data in populations who are currently potentially exposed to high levels of DDT, we urge the global community to monitor exposure to DDT and to evaluate its potential health impacts both in malaria-endemic regions of the world and in locations where DDT use has been historically high, such as the Pine River Superfund site.
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<p>Last Updated: August 7, 2009 </p>
Glossary
Citation
Perspectives, E. (2013). Human Health Consequences of DDT Use. Retrieved from http://www.eoearth.org/view/article/51cbee0a7896bb431f695b1a | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7836697697639465, "perplexity": 28484.37117710753}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207928076.40/warc/CC-MAIN-20150521113208-00104-ip-10-180-206-219.ec2.internal.warc.gz"} |
http://jgaa.info/getPaper?id=409 | Star-Shaped and L-Shaped Orthogonal Drawings Xin He and Dayu He Vol. 21, no. 2, pp. 155-175, 2017. Regular paper. Abstract An orthogonal drawing of a plane graph $G$ is a planar drawing of $G$, denoted by $D(G)$, such that each vertex of $G$ is drawn as a point on the plane, and each edge of $G$ is drawn as a sequence of horizontal and vertical line segments with no crossings. An orthogonal polygon $P$ is called orthogonally convex if the intersection of any horizontal or vertical line $L$ and $P$ is either a single line segment or empty. An orthogonal drawing $D(G)$ is called orthogonally convex if all of its internal faces are orthogonally convex polygons. An orthogonal polygon $P$ is called a star-shaped polygon if there is a point $p\in P$ such that the entire $P$ is visible from $p$. An orthogonal drawing $D(G)$ is called a star-shaped orthogonal drawing (SSOD) if all of its internal faces are star-shaped polygons. Every SSOD is an orthogonally convex drawing, but the reverse is not true. SSOD is visually more appealing than orthogonally convex drawings. Recently, Chang et al. gave a necessary and sufficient condition for a plane graph to have an orthogonally convex drawing. In this paper, we show that if $G$ satisfies the same condition given by Chang et al., it not only has an orthogonally convex drawing, but also a SSOD, which can be constructed in linear time. An orthogonal drawing $D(G)$ is called an $L$-shaped drawing if each face of $D(G)$ is an $L$-shaped polygon. In this paper we also show that an $L$-shaped orthogonal drawing can be constructed in $O(n)$ time. The same algorithmic technique is used for solving both problems. It is based on regular edge labeling and is quite different from the methods used in previous results. Submitted: February 2016. Reviewed: June 2016. Revised: August 2016. Reviewed: September 2016. Revised: December 2016. Accepted: December 2016. Final: December 2016. Published: January 2017. Communicated by Seok-Hee Hong article (PDF) BibTeX | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7738064527511597, "perplexity": 297.51943335398806}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084891105.83/warc/CC-MAIN-20180122054202-20180122074202-00035.warc.gz"} |
https://sunglee.us/mathphysarchive/?cat=72 | # Independence
Definition. Let $(\Omega,\mathscr{U},P)$ be a probability space. Let $A,B\in\mathscr{U}$ be two events with $P(B)>0$. $P(A|B)$, the probability of $A$ given $B$ is defined by
$$P(A|B)=\frac{P(A\cap B)}{P(B)}\ \mbox{if}\ P(B)>0$$
If the events $A$ and $B$ are independent,
$$P(A)=P(A|B)=\frac{P(A\cap B)}{P(B)}$$
i.e.
$$P(A\cap B)=P(A)P(B)$$
This is true under the assumption that $P(B)>0$ but we take this for the definition even if $P(B)=0$.
Definition. Two events $A$ and $B$ are independent if
$$P(A\cap B)=P(A)P(B)$$
Definition. Let $X_i:\Omega\longrightarrow\mathbb{R}^n$ be random variables, $i=1,\cdots$. Then random variables $X_1,\cdots$ are said to be independent if $\forall$ integers $k\geq 2$ and $\forall$ choices of Borel sets $B_1,\cdots,B_k\subset\mathbb{R}^n$
\begin{align*}
P(X_1\in B_1,X_2\in B_2,&\cdots,X_k\in B_k)=\\
&P(X_1\in B_1)P(X_2\in B_2)\cdots P(X_k\in B_k)
\end{align*}
Theorem. The random variables $X_1,\cdots,X_,m:\Omega\longrightarrow\mathbb{R}^n$ are independent if and only if
\label{eq:indepdistrib}
F_{X_1,\cdots,X_m}(x_1,\cdots,x_m)=F_{X_1}(x_1)\cdots F_{X_m}(x_m)
$\forall x_1\in\mathbb{R}^n$, $\forall i=1,\cdots,m$. If the random variables have densities, \eqref{eq:indepdistrib} is equivalent to
$$f_{X_1,\cdots,X_m}(x_1,\cdots,x_m)=f_{X_1}(x_1)\cdots f_{X_m}(x_m)$$
$\forall x_i\in\mathbb{R}^n$, $\forall i=1,\cdots,m$, where the function $f$ are the appropriate densities.
Proof. Suppose that $X_1,\cdots,X_m$ are independent. Then
\begin{align*}
F_{X_1,\cdots,X_m}(x_1,\cdots,x_m)&=P(X_1\leq x_1,\cdots, X_m\leq x_m)\\
&=P(X_1\leq x_1)\cdots,P(X_m\leq x_m)\\
&=F_{X_1}(x_1)\cdots F_{X_m}(x_m)
\end{align*}
Let $B_1,B_2,\cdots,B_m\subset\mathbb{R}^n$ be Borel sets. Then
\begin{align*}
P(X_1\in B_1,\cdots,X_m\in B_m)&=\int_{B_1\times\cdots\times B_m}f_{X_1,\cdots,X_m}(x_1,\cdots,x_m)dx_1\cdots x_m\\
&=\left(\int_{B_1}f_{X_1}(x_1)dx_1\right)\cdots\left(\int_{B_m}f_{X_m}(x_m)dx_m\right)\\
&=P(X_1\in B_1)P(X_2\in B_2)\cdots P(X_k\in B_k)
\end{align*}
So, $X_1,\cdots,X_m$ are independent.
Theorem. If $X_1,\cdots,X_m$ are independent real-valued random variables with $E(X_i)<\infty$ ($i=1,\cdots,m$) then $E(X_1\cdots X_m)<\infty$ and
$$E(X_1\cdots X_m)=E(X_1)\cdots E(X_m)$$
Proof.
\begin{align*}
E(X_1\cdots X_m)&=\int_{\mathbb{R}^n}x_1\cdots x_m f_{X_1,\cdots,X_m}(x_1,\cdots,x_m)dx_1\cdots x_m\\
&=\left(\int_{\mathbb{R}}x_1f_{X_1}(x_1)dx_1\right)\cdots\left(\int_{\mathbb{R}}x_mf_{X_m}(x_m)dx_m\right)\\
&=E(X_1)\cdots E(X_m)
\end{align*}
Theorem. If $X_1,\cdots,X_m$ are independent real-valued variables with $V(X_i)<\infty$, $i=1,\cdots,m$ then
$$V(X_1+\cdots+X_m)=V(X_1)+\cdots+V(X_m)$$
Proof. We prove for the case when $m=2$. For general $m$ case the proof follows by induction. Let $m_1=E(X_1)$ and $m_2=E(X_2)$. Then
\begin{align*}
E(X_1+X_2)&=\int_{\Omega}(X_1+X_2)dP\\
&=\int_{\Omega}X_1dP+\int_{\Omega}X_2dP\\
&=E(X_1)+E(X_2)\\
&=m_1+m_2
\end{align*}
\begin{align*}
V(X_1+X_2)&=\int_{\Omega}(X_1+X_2-(m_1+m_2))^2dP\\
&=\int_{\Omega}(X_1-m_1)^2dP+\int_{\Omega}(X_2-m_2)^2dP\\
+2\int_{\Omega}(X_1-m_1)(X_2-m_2)dP\\
&=V(X_1)+V(X_2)+2E[(X_1-m_1)(X_2-m_2)]
\end{align*}
For $X_1,X_2$ being independent, we have $E[(X_1-m_1)(X_2-m_2)]=0$. This completes the proof.
References:
Lawrence C. Evans, An Introduction to Stochastic Differential Equations, Lecture Notes
# Distribution Functions
Let $(\Omega,\mathscr{U},P)$ be a probability space and $X:\Omega\longrightarrow\mathbb{R}^n$ a randome variable. We define an ordering between two vectors in $\mathbb{R}^n$ as follows: Let $x=(x_1,\cdots,x_n),y=(y_1,\cdots,y_n)\in\mathbb{R}^n$. Then $x\leq y$ means $x_i\leq y_i$ for $i=i,\cdots,n$.
Definition. The distribution function of $X$ is the function $F_X: \mathbb{R}^n\longrightarrow[0,1]$ defined by
$$F_X(x):=P(X\leq x)$$
for all $x\in\mathbb{R}^n$. If $X_1,\cdots,X_m:\Omega\longrightarrow\mathbb{R}^n$ are random variables, their joint distribution function $F_{X_1,\cdots,X_m}:(\mathbb{R}^n)^m\longrightarrow[0,1]$ is defined by
$$F_{X_1,\cdots,X_m}(x_1,\cdots,x_m):=P(X_1\leq x_1,\cdots,X_m\leq x_m)$$
for all $x_i\in\mathbb{R}^n$ and for all $i=1,\cdots,n$.
Definition. Let $X$ be a random variable, $F=F_X$ its distribution function. If there exists a nonnegative integrable function $f:\mathbb{R}^n\longrightarrow\mathbb{R}$ such that
$$F(x)=F(x_1,\cdots,x_n)=\int_{-\infty}^{x_1}\cdots\int_{-\infty}^{x_n}f(y_1,\cdots,y_n)dy_1\cdots dy_n$$
then $f$ is called the density function for $X$. More generally,
$$P(X\in B)=\int_B f(x)dx$$
for all $B\in\mathscr{B}$ where $\mathscr{B}$ is the Borel $\sigma$-algebra.
Example. If $X:\Omega\longrightarrow\mathbb{R}$ has the density function
$$f(x)=\frac{1}{\sqrt{2\pi\sigma^2}}e^{-\frac{|x-m|^2}{2\sigma^2}},\ x\in\mathbb{R}$$
then we say $X$ has a Gaussian or normal distribution with mean $m$ and variance $\sigma^2$. In this case, we write “$X$ is an $N(m,\sigma^2)$ random variable.”
Example. If $X: \Omega\longrightarrow\mathbb{R}^n$ has the density
$$f(x)=\frac{1}{\sqrt{(2\pi)^n\det C}}e^{-\frac{1}{2}(x-m)C^{-1}(x-m)^t},\ x\in\mathbb{R}^n$$
for some $m\in\mathbb{R}^n$ and some positive definite symmetric matrix $C$, we say that “$X$ has a Gaussian or normal distribution with mean $m$ and covariance matrix $C$.” We write $X$ is an $N(m,C)$ random variable. The covariance matrix is given by
$$\label{eq:covmatrix}C=E[(X-E(X))^t(X-E(X))]$$
where $X=(X_1,\cdots,X_n)$, i.e. each $C$ is the matrix whose $(i,j)$ entry is the covariance
$$C_{ij}=\mathrm{cov}(X_i,X_j)=E[(X_i-E(X_i))(X_j-E(X_j))]=E(X_iX_j)-E(X_i)E(X_j)$$
Clearly $C$ is a symmetric matrix. Recall that for a real-valued random matrix $X$ the variance $\sigma^2$ is given by
$$\sigma^2=V(X)=E[(X-E(X))^2]=E[(X-E(X))\cdot (X-E(X))]$$
So one readily sees that \eqref{eq:covmatrix} is a generalization of variance to higher dimensions. It follows from \eqref{eq:covmatrix} that for a vector $b\in\mathbb{R}^n$,
$$V(Xb^t)=bV(X)b^t$$
Since the variance is nonnegative, we see that the covariance matrix is a positive definite matrix. Since $C$ is symmetric, $PCP^{-1}=D$ where $P$ is an orthogonal matrix and $D$ is a diagonal matrix whose main diagonal contains the eigenvalues of $C$. Recall that for two $n\times n$ matrices $A$ and $B$, $\det(AB)=\det(A)\det(B)$ so we see that $\det(C)=\det(D)$. Since all the eigenvalues of a positive definite matrix are positive, $\det(C)>0$.
Lemma. Let $X:\Omega\longrightarrow\mathbb{R}^n$ be a random variable and assume that its distribution function $F=F_X$ has the density $f$. Suppose $g:\mathbb{R}^n\longrightarrow\mathbb{R}$ and $Y=g(X)$ is integrable. Then
$$E(Y)=\int_{\mathbb{R}^n}g(x)f(x)dx$$
Proof. Suppose first that $g$ is a simple function on $\mathbb{R}^n$.
$$g=\sum_{i=1}^mb_iI_{B_i}\ (B_i\in\mathscr{B})$$
\begin{align*}E(g(X))&=\sum_{i=1}^mb_i\int_{\Omega}I_{B_i}(X)dP\\&=\sum_{i=1}^mb_iP(X\in B_i).\end{align*}
But
\begin{align*}\int_{\mathbb{R}^n}g(x)f(x)dx&=\sum_{i=1}^mb_i\int_{\mathbb{R}^n}I_{B_i}f(x)dx\\&=\sum_{i=1}^nb_i\int_{B_i}f(x)dx\\&=\sum_{i=1}^mb_iP(X\in B_i)\end{align*}
Hence proves the lemma for the case $g$ is a simple function. The rest of the argument extends to general $g$ straightforwardly.
Corollary. If $X:\Omega\longrightarrow\mathbb{R}^n$ is a random variable and its distribution function $F=F_X$ has the density $f$, then
$$V(X)=\int_{\mathbb{R}^n}|x-E(X)|^2f(x)dx$$
Proof. Recall that $V(X)=E(|X-E(X)|^2)$. Define $g:\mathbb{R}^n\longrightarrow\mathbb{R}$ by
$$g(x)=|x-E(X)|^2$$
for all $x\in\mathbb{R}^n$. Then by the Lemma we have
$$V(X)=\int_{\mathbb{R}^n}|x-E(X)|^2f(x)dx$$
Corollary. If $X:\Omega\longrightarrow\mathbb{R}$ is a random variable and its distribution function $F=F_X$ has the density $f$, then $E(X)=\int_{-\infty}^\infty xf(x)dx$ and $V(X)=\int_{-\infty}^\infty |x-E(X)|^2f(x)dx$.
Proof. Trivial from the Lemma by taking $g:\mathbb{R}\longrightarrow\mathbb{R}$ the identity map.
Corollary. If $X:\Omega\longrightarrow\mathbb{R}^n$ is a random variable and its distribution function $F=F_X$ has the density $f$, then
$$E(X_1\cdots X_n)=\int_{\mathbb{R}^n}x_1\cdots x_nf(x)dx$$
Proof. Define $g:\mathbb{R}^n\longrightarrow\mathbb{R}$ by
$$g(x)=x_1\cdots x_n\ \mbox{for all}\ x=(x_1,\cdots,x_n)\in\mathbb{R}^n$$
Then the rest follows by the Lemma.
Example. If $X$ is $N(m,\sigma^2)$ then
\begin{align*}
E(X)&=\frac{1}{\sqrt{2\pi\sigma^2}}\int_{-\infty}^\infty xe^{-\frac{(x-m)^2}{2\sigma^2}}dx\\
&=m\\
V(X)&=\frac{1}{\sqrt{2\pi\sigma^2}}\int_{-\infty}^\infty (x-m)^2e^{-\frac{(x-m)^2}{2\sigma^2}}dx\\
&=\sigma^2
\end{align*}
Therefore, $m$ is the mean and $\sigma^2$ is the variance.
References:
Lawrence C. Evans, An Introduction to Stochastic Differential Equations, Lecture Notes
# Probability Measure
In this lecture notes, we study basic measure theory in terms of probability. If you want to learn more about general measure theory, I recommend [2].
Let $\Omega$ be a set whose elements will be called samples.
Definition. A $\sigma$-algebra is a collection $\mathscr{U}$ of subsets of $\Omega$ satisfying
1. $\varnothing,\Omega\in\mathscr{U}$
2. If $A\in\mathscr{U}$, then $A^c\in\mathscr{U}$
3. If $A_1,A_2,\cdots\in\mathscr{U}$, then $\bigcup_{k=1}^\infty A_k,\bigcap_{k=1}^\infty A_k\in\mathscr{U}$
Note: In condition 3, it suffices to say if $A_1,A_2,\cdots\in\mathscr{U}$, then $\bigcup_{k=1}^\infty A_k\in\mathscr{U}$ or if $A_1,A_2,\cdots\in\mathscr{U}$, then $\bigcap_{k=1}^\infty A_k\in\mathscr{U}$. For example, lets assume that if $A_1,A_2,\cdots\in\mathscr{U}$, then $\bigcup_{k=1}^\infty A_k\in\mathscr{U}$. Let $A_1,A_2,\cdots\in\mathscr{U}$. Then by condition 2, $(A_1)^c,(A_2)^c,\cdots\in\mathscr{U}$ so we have $\bigcup_{k=1}^\infty (A_k)^c\in\mathscr{U}$. By condition 2 again with De Morgan’s laws, this means $\bigcap_{k=1}^\infty A_k=\left[\bigcup_{k=1}^\infty (A_k)^c\right]^c\in\mathscr{U}$.
Definition. Let $\mathscr{U}$ be a $\sigma$-algebra of subsets of $\Omega$. A map $P:\mathscr{U}\longrightarrow[0,1]$ a probability measure if $P$ satisfies
1. $P(\varnothing)=0$, $P(\Omega)=1$
2. If $A_1,A_2,\cdots\in\mathscr{U}$, then $$P\left(\bigcup_{k=1}^\infty A_k\right)\leq\sum_{k=1}^\infty P(A_k)$$
3. If $A_1,A_2,\cdots\in\mathscr{U}$ are mutually disjoint, then $$P\left(\bigcup_{k=1}^\infty A_k\right)=\sum_{k=1}^\infty P(A_k)$$
Proposition. Let $A,B\in\mathscr{U}$. If $A\subset B$ then $P(A)\leq P(B)$.
Proof. Let $A,B\in\mathscr{U}$ with $A\subset B$. Then $B=(B-A)\dot\cup A$ where $\dot\cup$ denotes disjoint union. So by condition 3, $P(B)=P(B-A)+P(A)\geq P(A)$ since $P(B-A)\geq 0$.
Definition. A triple $(\Omega,\mathscr{U},P)$ is called a probability space. We say $A\in\mathscr{U}$ is an event and $P(A)$ is the probability of the event $A$. A property which is true except for an event of probability zero is said to hold almost surely (abbreviated “a.s.”).
Example. The smallest $\sigma$-algebra containing all the open subsets of $\mathbb{R}^n$ is called the Borel $\sigma$-algebra and is denoted by $\mathscr{B}$. Here we mean “open subsets” in terms of the usual Euclidean topology on $\mathbb{R}^n$. Since $\mathbb{R}^n$ with the Euclidean topology is second countable, the “open subsets” can be replaced by “basic open subsets”. Assume that a function $f$ is nonnegative, integrable (whatever that means, we will talk about it later) such that $\int_{\mathbb{R}^n}f(x)dx=1$. Define
$$P(B)=\int_Bf(x)dx$$ for each $B\in\mathscr{B}$. Then $(\mathbb{R}^n,\mathscr{B},P)$ is a probability space. The function $f$ is called the density of the probability measure $P$.
Definition. Let $(\Omega,\mathscr{U},P)$ be a probability space. A mapping $X:\Omega\longrightarrow\mathbb{R}^n$ is called an $n$-dimensional random variable if for each $B\in\mathscr{B}$, $X^{-1}(B)\in\mathscr{U}$. Equivalently we also say $X$ is $\mathscr{U}$-measurable. The probability space $(\Omega,\mathscr{U},P)$ is a mathematical construct that we cannot observe directly. But the values $X(\omega)$, $\omega\in\Omega$ of random variable $X$ are observables. Following customary notations in probability theory, we write $X(\omega)$ simply by $X$. Also $P(X^{-1}(B))$ is denoted by $P(X\in B)$.
Definition. Let $A\in\mathscr{U}$. Then the indicator $I_A: \Omega\longrightarrow\{0,1\}$ of $A$ is defined by $$I_A(\omega)=\left\{\begin{array}{ccc}1 & \mbox{if} & \omega\in A\\0 & \mbox{if} & \omega\not\in A\end{array}\right.$$
In measure theory the indicator of $A$ is also called the characteristic function of $A$ and is usually denoted by $\chi_A$. Here we reserve the term “characteristic function” for something else. Clearly the indicator is a random variable since both $\{0\},\{1\}$ are open. The Borel $\sigma$-algebra $\mathscr{B}$ coincides with the discrete topology on $\{0,1\}$. Or without mentioning subspace topology, let $B\in\mathscr{B}$, the Borel $\sigma$-algebra of $\mathbb{R}$. If $0\in B$ and $1\notin B$ then $I_A^{-1}(B)=A^c\in\mathscr{U}$. If $0\notin B$ and $1\in B$ then $I_A^{-1}(B)=A\in\mathscr{U}$. If $0,1\notin B$ then $I_A^{-1}(B)=\varnothing\in\mathscr{U}$. If $0,1\in B$ then $I_A^{-1}(B)=\Omega\in\mathscr{U}$.
If $A_1,A_2,\cdots,A_m\in\mathscr{U}$ with $\Omega=\bigcup_{i=1}^m A_i$ and $a_1,a_2,\cdots,a_m\in\mathbb{R}$, then
$$X=\sum_{i=1}^m a_iI_{A_i}$$ is a random variable called a simple function.
Simple function
Lemma. Let $X: \Omega\longrightarrow\mathbb{R}^n$ be a random variable. Then
$$\mathscr{U}(X)=\{X^{-1}(B): B\in\mathscr{B}\}$$ is the smallest $\sigma$-algebra with respect to which $X$ is measurable. $\mathscr{U}(X)$ is called the $\sigma$-algebra generated by $X$.
Definition. A collection $\{X(t)|t\geq 0\}$ of random variables parametrized by time $t$ is called a stochastic process. For each $\omega\in\Omega$, the map $t\longmapsto X(t,\omega)$ is the corresponding sample path.
Let $(\Omega,\mathscr{U},P)$ be a probability space and $X=\sum_{i=1}^k a_iI_{A_i}$ a simple random variable. The probability that $X=a_i$ is $P(X=a_i)=P(X^{-1}(a_i))=P(A_i)$, so $\sum_{i=1}^k a_iP(A_i)$ is the expected value of $X$. We define the integral of $X$ by
$$\label{eq:integral}\int_{\Omega}XdP=\sum_{i=1}^k a_iP(A_i)$$
if $X$ is a simple random variable. A random variable is not necessarily simple so we obviously want to extend the notion of integral to general random variables. First suppose that $X$ is a nonnegative random variable. Then we define
$$\label{eq:integral2}\int_{\Omega}XdP=\sup_{Y\leq X,\ Y\ \mbox{simple}}\int_{\Omega}YdP$$
Let $X$ be a random variable. Let $X^+=\max\{X,0\}$ and $X^-=\max\{-X,0\}$. Then $X=X^+-X^-$. Define
$$\label{eq:integral3}\int_{\Omega}XdP=\int_{\Omega}X^+dP-\int_{\Omega}X^-dP$$For a random variable $X$, we would still call the integral \eqref{eq:integral3} the expected value of $X$ and denote it by $E(X)$. This integral is called Lebesgue integral in real analysis (see [2]). When I first learned Lebesgue integral in my senior year in college, it wasn’t very clear to me as to what motivated one to define Lebesgue integral the way it is. In terms of probability the motivation is so much clear. I personally think that it would be better if we introduce Lebesgue integral to undergraduate students in the context of probability theory rather than abstract real analysis. If $X:\Omega\longrightarrow\mathbb{R}^n$ is a vector-valued random variable and $X=(X_1,X_2,\cdots,X_n)$, we define $$\int_{\Omega}XdP=\left(\int_{\Omega}X_1dP,\int_{\Omega}X_2dP,\cdots,\int_{\Omega}X_ndP\right)$$As one would expect from an integral, the expected value $E(\cdot)$ is linear.
Definition. We call $$V(X)=\int_{\Omega}|X-E(X)|^2dP$$the variance of $X$.
It follows from the linearity of $E(\cdot)$ that $$V(X)=E(|X-E(X)|^2)=E(|X|^2)-|E(X)|^2$$
Lemma. If $X$ is a random variable and $1\leq p<\infty$, then $$\label{eq:chebyshev}P(|X|\geq\lambda)\leq\frac{1}{\lambda^p}E(|X|^p)$$for all $\lambda>0$. The inequality \eqref{eq:chebyshev} is called Chebyshev’s inequality.
Proof. Since $1\leq p<\infty$, $|X|\geq\lambda\Rightarrow |X|^p\geq\lambda^p$. So, \begin{align*}E(|X|^p)&=\int_{\Omega}|X|^pdP\\&\geq\int_{|X|\geq\lambda}|X|^pdP\\
&\geq\lambda^p\int_{|X|\geq\lambda}dP\\&=\lambda^pP(|X|\geq\lambda).\end{align*}
Example. Let a random variable $X$ have the probability density function $$f(x)=\left\{\begin{array}{ccc}\frac{1}{2\sqrt{3}} & \mbox{if} & -\sqrt{3}<x<\sqrt{3}\\ 0 & \mbox{elsewhere} \end{array}\right.$$For $p=1$ and $\lambda=\frac{3}{2}$, $\frac{1}{\lambda}E(|X|)=\frac{1}{\sqrt{3}}\approx 0.58$. Note that $E(|X|)=\int_{-\infty}^\infty |x|f(x)dx$. (We will discuss this later.) $P(|X|\geq\frac{3}{2})=1-\int_{-\frac{3}{2}}^{\frac{3}{2}}f(x)dx=1-\frac{\sqrt{3}}{2}=0.134$. Hence we confirm Chebyshev’s inequality.
References: Not in particular order
1. Lawrence C. Evans, An Introduction to Stochastic Differential Equations, Lecture Notes
2. H. L. Royden, Real Analysis, Second Edition, Macmillan
3. Robert V. Hogg, Joseph W. McKean, Allen T. Craig, Introduction to Mathematical Statistics, Sixth Edition, Pearson | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 5, "x-ck12": 0, "texerror": 0, "math_score": 0.9968932271003723, "perplexity": 130.13578927444814}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323586043.75/warc/CC-MAIN-20211024142824-20211024172824-00246.warc.gz"} |
https://www.solidot.org/translate/?nid=85931 | ## Energy Efficiency Analysis of Heterogeneous Cellular Networks With Extra Cell Range Expansion. (arXiv:1801.01663v1 [cs.IT])
The split control and user plane is key to the future heterogeneous cellular network (HCN), where the small cells are dedicated for the most data transmission while the macrocells are mainly responsible for the control signaling. Adapting to this technology, we propose a general and tractable framework of extra cell range expansion (CRE) by introducing an additional bias factor to enlarge the range of small cells flexibly for the extra offloaded macrousers in a two-tier HCN, where the macrocell and small cell users have different required data rates. Using stochastic geometry, we analyze the energy efficiency (EE) of the extra CRE with joint low power transmission and resource partitioning, where the coverages of EE and data rate are formulated theoretically. Numerical simulations verify that the proposed extra CRE can improve the EE performance of HCN, and also show that deploying more small cells can provide benefits for EE coverage, but the EE improvement becomes saturated if the sm查看全文
## Solidot 文章翻译
你的名字 留空匿名提交 你的Email或网站 用户可以联系你 标题 简单描述 内容 The split control and user plane is key to the future heterogeneous cellular network (HCN), where the small cells are dedicated for the most data transmission while the macrocells are mainly responsible for the control signaling. Adapting to this technology, we propose a general and tractable framework of extra cell range expansion (CRE) by introducing an additional bias factor to enlarge the range of small cells flexibly for the extra offloaded macrousers in a two-tier HCN, where the macrocell and small cell users have different required data rates. Using stochastic geometry, we analyze the energy efficiency (EE) of the extra CRE with joint low power transmission and resource partitioning, where the coverages of EE and data rate are formulated theoretically. Numerical simulations verify that the proposed extra CRE can improve the EE performance of HCN, and also show that deploying more small cells can provide benefits for EE coverage, but the EE improvement becomes saturated if the sm | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.834562361240387, "perplexity": 1837.2477243549015}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084890771.63/warc/CC-MAIN-20180121135825-20180121155825-00632.warc.gz"} |
http://blog.mathhelpboards.com/2016/04/13/angle-side-side-law-of-sines | # Side-side-angle and impossible triangles
### What is the ambiguous case?
In high school geometry, the idea of proofs are often first introduced to American students. A common task is to use a basic set of rules to prove two triangles are congruent, which is a fancy way of saying they have the same side lengths and the same angles. Phrases like side-angle-side (SAS) and angle-angle-side (AAS) might ring a bell. This topic is very polarizing and quickly separates students into those who say “I love geometry!” and “I miss algebra!”. Simply put though, all of these acronyms are just descriptions of the information we are given about a triangle. Note that the order of this information is very important! SAS and SSA both contain one angle and two sides, but both of them won’t prove two triangles are congruent.
There is one problematic case of side-side-angle (SSA) or put another way, angle-side-side (I’ll pause here and let you chuckle at the joke every geometry teacher in the country makes at this moment). Some teachers will correctly note that this situation is not enough to show two triangles are congruent and leave it at that, but there is more that can be explored here. When you are given a SSA triangle, this is called the ambiguous case because it could in fact result in 0, 1, or 2 triangles. This post will focus on demonstrating that no solutions exist.
### Step-by-step method of solving
1. Draw the triangle and label all given information. It doesn’t need to be to scale at all! It also doesn’t matter how you orient the triangle as long as side a is across from angle A, side b is across from angle B, and side c is across from angle C. Just draw and label.
2. Use the Law of Sines to solve for the angle across from the second side. Which one is the second side? Well in SSA you have two sides. One of the angle will pair with a side, like angle A and side a, or angle B and side b. There will be an unused side that isn’t paired. We are going to try to find that angle.
Let’s walk through an example.
Side-Side-Angle Triangle Example
$B = 55 ^{\circ}, b=8.99,a=26.22$
Following the steps above, let’s draw this triangle!
Notice that angle A is in the bottom right corner. Often students and teachers like to put angle A at the top. It doesn’t matter as long as the sides go across from the angles! You could draw the triangle like this as well. It won’t change the answer.
The Law of Sines states that $\displaystyle \frac{\sin(A)}{a}=\frac{\sin(B)}{b}=\frac{\sin(C)}{c}$ As mentioned in step 2, we are going to try to find angle B, because it is the angle opposite the second side. (We can’t find angle C or side c right now because we don’t have any information on that side. Try to solve for either of those to convince yourself if that seems unclear.)
\begin{align*}
\frac{\sin(55^{\circ})}{26.22}&=\frac{\sin(B)}{8.99} \\
\sin(B) &= \frac{26.22\sin(55^{\circ})}{8.99} \\
\sin(B) &\approx 2.389
\end{align*}
Uh oh! We have a problem!! Remember that the range of $\sin(x)$ is $[-1,1]$, meaning the output of this function has to stay between these two values. When we get an answer like the one above, it is IMPOSSIBLE to find an angle to make the statement true and we have an IMPOSSIBLE triangle. Try putting $\sin^{-1}(2.389)$ into your calculator to check and you’ll get an error message.
### Key Points
Draw a triangle and label your given information. Do not worry at all if the triangle is to scale. Use the Law of Sines to find the second angle that connects to the second side you are given and simplify. When you get $\sin(A), \sin(B), \sin(C)$ is outside of $[-1,1]$, you can confidently answer that this triangle does not exist. If it does fall inside that range, then you should move onto deciding if 1 or 2 triangles are possible. That topic will be covered in another blog post soon. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.637440025806427, "perplexity": 397.66338534141977}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-09/segments/1487501170600.29/warc/CC-MAIN-20170219104610-00076-ip-10-171-10-108.ec2.internal.warc.gz"} |
http://mathhelpforum.com/trigonometry/39125-trigonometric-modelling.html | # Thread: Trigonometric modelling
1. ## Trigonometric modelling
All help much appreciated, sorry for poor set out of equation.
The height of water(h metres) on a pier pylon is given by:
h=2sin((pi/12)*t)+4, where t is given in hours after midday.What is the height of the water at:
a)2pm
b)6am the next morning
2. Originally Posted by ollieman
All help much appreciated, sorry for poor set out of equation.
The height of water(h metres) on a pier pylon is given by:
h=2sin((pi/12)*t)+4, where t is given in hours after midday.What is the height of the water at:
a)2pm
b)6am the next morning
2pm is 2 hours after midday so t=2
giving us
$h=2\sin (\frac{\pi}{6})+4$
$h=2(\frac{1}{2})+4=5$
I'll leave you to do b, but remember at 6am the next morning it going to be 18 hours after midday | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 2, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9452500343322754, "perplexity": 3191.7440649067667}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-43/segments/1508187825174.90/warc/CC-MAIN-20171022094207-20171022114207-00729.warc.gz"} |
http://physicshelpforum.com/general-physics/1600-laplace-transformation.html | Physics Help Forum Laplace Transformation
General Physics General Physics Help Forum
Mar 9th 2009, 09:47 AM #1 Junior Member Join Date: Feb 2009 Location: Dhaka,Bangladesh Posts: 6 Laplace Transformation Hello, I am facing problem understanding the following equation I have just faced. It will be very kind of you if you can clarify it to me. The equation is...... L [f(at)] = 1/a*F(s/a) I can not find the "F(s/a)" where does it come from? And what does it mean? I have started Laplace Transform lately and to understand it completely. If you can help me I would be very glad. Thank you.
Mar 9th 2009, 06:07 PM #2 Senior Member Join Date: Dec 2008 Location: Las Cruces NM Posts: 256 When you take the Laplace transform of a function $\displaystyle f(t)$ of the varible $\displaystyle t$, you get a function $\displaystyle F(s)$ of a different variable $\displaystyle s$. The rule $\displaystyle {\cal L} f(at) = \frac {1}{|a|} F(s/a)$ tells you how to find the Laplace transform of $\displaystyle f(at)$ when you only know the Laplace transform of $\displaystyle f(t)$. For example, given that $\displaystyle {\cal L} \sin(t) = \frac {1}{s^2 + 1}$, find $\displaystyle {\cal L} \sin(3t)$. $\displaystyle {\cal L} \sin(3t) = \frac {1}{|3|} \frac {1}{ (s/3)^2 + 1}$ $\displaystyle = \frac {1} {3} \frac {1}{ \frac {s^2}{ 9} + 1}$ $\displaystyle = \frac {3}{9} \frac {1}{ \frac {s^2}{ 9} + 1}$ $\displaystyle = \frac {3}{s^2 + 9} = \frac {3}{s^2 + 3^2}$
Mar 9th 2009, 08:56 PM #3 Junior Member Join Date: Feb 2009 Location: Dhaka,Bangladesh Posts: 6 Thanks a lot sir, I was thinking that "F" could be another kind of function. Thank you for your easy solution. I will be glad if you please send me the derivation. I will try it myself but it will be good for me if you send it. Thank you.
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Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post webconnector Advanced Electricity and Magnetism 6 Jul 9th 2015 01:18 PM mooshazz Electricity and Magnetism 1 May 18th 2013 07:31 AM Nimmy Advanced Electricity and Magnetism 0 Oct 18th 2011 09:42 AM aaaa202 Special and General Relativity 0 Oct 10th 2011 06:28 AM rosalia General Physics 0 Apr 22nd 2009 09:49 AM | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8719567656517029, "perplexity": 1009.3109726489886}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514573105.1/warc/CC-MAIN-20190917181046-20190917203046-00556.warc.gz"} |
https://datascience.stackexchange.com/questions/5656/k-means-what-are-some-good-ways-to-choose-an-efficient-set-of-initial-centroids | # K-means: What are some good ways to choose an efficient set of initial centroids?
When a random initialization of centroids is used, different runs of K-means produce different total SSEs. And it is crucial in the performance of the algorithm. What are some effective approaches toward solving this problem? Recent approaches are appreciated.
An approach that yields more consistent results is K-means++. This approach acknowledges that there is probably a better choice of initial centroid locations than simple random assignment. Specifically, K-means tends to perform better when centroids are seeded in such a way that doesn't clump them together in space.
In short, the method is as follows:
1. Choose one of your data points at random as an initial centroid.
2. Calculate $D(x)$, the distance between your initial centroid and all other data points, $x$.
3. Choose your next centroid from the remaining datapoints with probability proportional to $D(x)^2$
4. Repeat until all centroids have been assigned.
Note: $D(x)$ should be updated as more centroids are added. It should be set to be the distance between a data point and the nearest centroid.
You may also be interested to read this paper that proposes the method and describes its overall expected performance.
• I just implement this algorithm in my KMeans for seeding the centroids the algorithm got 10x faster! unbelievable how a small adjustment in the code, can boost the whole system up! May 3 at 20:41
I may be misunderstanding your question, but usually k-means chooses your centroids randomly for you depending on the number of clusters you set (i.e. k). Choosing the number for k tends to be a subjective exercise. A good place to start is an Elbow/Scree plot which can be found here.
• I think the question is about centroid initialization, which are {‘k-means++’, ‘random’ or an ndarray} on the documentation page scikit-learn.org/stable/modules/generated/… Mar 25 '19 at 17:21
The usual approach to this problem is to re-run your K-means algorithm several times, with different random initializations of the centroids, and to keep the best solution. You can do that by evaluating the results on your training data or by means of cross validation.
There are many other ways to initialize the centroids, but none of them is going to perform the best for every single problem. You could evaluate these approaches together with random initialization for your particular problem.
I agree with the Elbow/Scree plot. I found it more intuitively sensible than a random seed. Here's an example code to try it.
Ks=30
mean_acc=np.zeros((Ks-1))
std_acc=np.zeros((Ks-1))
ConfustionMx=[];
for n in range(1,Ks):
#Train Model and Predict
kNN_model = KNeighborsClassifier(n_neighbors=n).fit(X_train,y_train)
yhat = kNN_model.predict(X_test)
mean_acc[n-1]=np.mean(yhat==y_test);
std_acc[n-1]=np.std(yhat==y_test)/np.sqrt(yhat.shape[0])
plt.plot(range(1,Ks),mean_acc,'g')
plt.fill_between(range(1,Ks),mean_acc - 1 * std_acc,mean_acc + 1 * std_acc, alpha=0.10)
plt.legend(('Accuracy ', '+/- 3xstd'))
plt.ylabel('Accuracy ')
plt.xlabel('Number of Nabors (K)')
plt.tight_layout()
plt.show()
print( "The best accuracy was with", mean_acc.max(), "with k=", mean_acc.argmax()+1) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5959427356719971, "perplexity": 1028.230565246656}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323587659.72/warc/CC-MAIN-20211025092203-20211025122203-00576.warc.gz"} |
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=E1DMBP_2004_v17n1_46 | Effect of Varying Levels of Dietary Minerals on Growth and Nutrient Utilization in Lambs
Title & Authors
Effect of Varying Levels of Dietary Minerals on Growth and Nutrient Utilization in Lambs
Sharma, L.C.; Yadav, P.S.; Mandal, A.B.; Sunaria, K.R.;
Abstract
Hisardale male lambs (n=24, 4-5 month of age) were maintained on a conventional ration for a month, to equilibrate the body mineral status. Six lambs were sacrificed after one month of feeding; the samples of organs were analyzed to ascertain mineral status. The remaining 18 lambs were divided into 3 groups of 6 each on body weight basis. Three dietary treatments containing 100 ($\small{T_1}$), 110 ($\small{T_2}$) and 120% ($\small{T_3}$) of minerals (Ca, P, S, Zn and Mn) as specified by NRC (1985) were formulated and each treatment was alloted ad libitum to a group for 120 days. Blood and wool samples were collected at monthly intervals. At the end of the experiment a balance trial of 5 days duration was conducted to study the balance of mineral elements. The effective intake of minerals was Ca, 111 and 120, P, 110 and 122; S, 112 and 129; Zn, 112 and 126 and Mn, 109 and 123 percent in $\small{T_2}$ and $\small{T_3}$, respectively, in comparison to $\small{T_1}$ (100). The additional mineral supplementation had no significant effect on dry matter intake. The average daily weight gain was higher (p<0.01) in $\small{T_2}$ and $\small{T_3}$ than the control ($\small{T_1}$). The lambs under treatments $\small{T_2}$ (8.72) and $\small{T_3}$ (8.47 kg) consumed apparently lesser amount of dry matter per unit gain as compared to $\small{T_1}$ (10.81 kg). Significantly higher (p<0.05) dry matter and crude protein digestibility (%) were observed in $\small{T_2}$ and $\small{T_3}$ than in $\small{T_1}$. The mean balances for different elements were Ca, 1.14, 1.68 and 1.67 g; P, 1.70, 1.95 and 2.18 g; S, 0.54, 0.92 and 1.11 g; Zn, 22.56, 25.30 and 28.71 mg; Cu, 7.94, 5.71 and 5.53 mg; Fe, 33.19, 32.94 and 31.03 mg and Mn, 8.24, 14.40 and 16.07 mg/lamb/day. The retention of supplemental minerals increased (p<0.01) while that of Cu decreased (p<0.01) due to supplementation of minerals (Ca, P, S, Zn and Mn). Retention as per cent of intake increased statistically for S and Mn while that of Cu decreased. It can be concluded that supplementation of minerals (Ca, P, S, Zn and Mn) higher than the recommended level improved body weight gain and feed to gain ratio. The retention of minerals increased due to supplementation. Therefore, an additional supplementation of deficient minerals (Ca, P, S, Zn and Mn) by 10% was beneficial for Hisardale male lambs under tropical condition in India.
Keywords
Minerals;Supplementation;Sheep;Requirements;Growth;Nutrient Utilization;
Language
English
Cited by
1.
Effects of Dietary Copper on Ruminal Fermentation, Nutrient Digestibility and Fibre Characteristics in Cashmere Goats,;;;;;;
아세아태평양축산학회지, 2007. vol.20. 12, pp.1843-1848
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Yadav, K. K. and V. M. Mandokhot. 1988. Effect of sulfur supplementation on the performance of stall-fed Nali lambs, growth responses, nutrient and minerals. Indian J. Anim. Sci. 58:843-48. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 15, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6232074499130249, "perplexity": 26711.207835101406}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-04/segments/1484560280239.54/warc/CC-MAIN-20170116095120-00455-ip-10-171-10-70.ec2.internal.warc.gz"} |
https://math.stackexchange.com/questions/625/why-is-the-derivative-of-a-circles-area-its-perimeter-and-similarly-for-sphere/96752 | # Why is the derivative of a circle's area its perimeter (and similarly for spheres)?
When differentiated with respect to $r$, the derivative of $\pi r^2$ is $2 \pi r$, which is the circumference of a circle.
Similarly, when the formula for a sphere's volume $\frac{4}{3} \pi r^3$ is differentiated with respect to $r$, we get $4 \pi r^2$.
Is this just a coincidence, or is there some deep explanation for why we should expect this?
• (I realise that it might not be clear what the $n$-dimensional generalisation is of this, but perhaps this would happen even in different geometries or metric spaces?).
– bryn
Jul 24, 2010 at 3:01
• Its deep. Look at the most general version of the fundamental theorem of calculus en.wikipedia.org/wiki/… Jul 24, 2010 at 3:23
• And next explain why it fails for the square... or the ellipse... Dec 6, 2011 at 14:22
• You mentioned that it's true for the 2-sphere, and for the 3-sphere, but it should be noted that it is also true for the 1-sphere, which is the interval from -r to r, which has 1-volume of 2r. The derivative of 2r wrt r is 2, which is the measure of its "surface", measure for 0-dimensional items being the same as cardinality. Jan 7, 2012 at 11:47
• @GEdgar : I make out the area of a square of 'radius' $r$ as $4r^2$ and the perimeter as $8r$; the idea continues to work there (for essentially the same uniformity reason that it does on the sphere). Of course, it doesn't work on rectangles for the same reason it doesn't work on ellipses... Apr 8, 2012 at 18:11
## 8 Answers
Consider increasing the radius of a circle by an infinitesimally small amount, $dr$. This increases the area by an annulus (or ring) with inner radius $2 \pi r$ and outer radius $2\pi(r+dr)$. As this ring is extremely thin, we can imagine cutting the ring and then flattening it out to form a rectangle with width $2\pi r$ and height $dr$ (the side of length $2\pi(r+dr)$ is close enough to $2\pi r$ that we can ignore that). So the area gain is $2\pi r\cdot dr$ and to determine the rate of change with respect to $r$, we divide by $dr$ and so we get $2\pi r$. Please note that this is just an informative, intuitive explanation as opposed to a formal proof. The same reasoning works with a sphere, we just flatten it out to a rectangular prism instead.
• Inner radius of the annulus or inner circumference?
– Huey
Sep 4, 2015 at 10:31
$\newcommand{\Reals}{\mathbf{R}}\newcommand{\Bd}{\partial}\DeclareMathOperator{\vol}{vol}$The formulas are no accident, but not especially deep. The explanation comes down to a couple of geometric observations.
1. If $X$ is the closure of a bounded open set in the Euclidean space $\Reals^{n}$ (such as a solid ball, or a bounded polytope, or an ellipsoid) and if $a > 0$ is real, then the image $aX$ of $X$ under the mapping $x \mapsto ax$ (uniform scaling by a factor of $a$ about the origin) satisfies $$\vol_{n}(aX) = a^{n} \vol_{n}(X).$$ More generally, if $X$ is a closed, bounded, piecewise-smooth $k$-dimensional manifold in $\Reals^{n}$, then scaling $X$ by a factor of $a$ multiplies the volume by $a^{k}$.
2. If $X \subset \Reals^{n}$ is a bounded, $n$-dimensional intersection of closed half-spaces whose boundaries lie at unit distance from the origin, then scaling $X$ by $a = (1 + h)$ "adds a shell of uniform thickness $h$ to $X$ (modulo behavior along intersections of hyperplanes)". The volume of this shell is equal to $h$ times the $(n - 1)$-dimensional measure of the boundary of $X$, up to added terms of higher order in $h$ (i.e., terms whose total contribution to the $n$-dimensional volume of the shell is negligible as $h \to 0$).
If $X$ satisfies Property 2. (e.g., $X$ is a ball or cube or simplex of "unit radius" centered at the origin), then $$h \vol_{n-1}(\Bd X) \approx \vol_{n}\bigl[(1 + h)X \setminus X\bigr],$$ or $$\vol_{n-1}(\Bd X) \approx \frac{(1 + h)^{n} - 1}{h}\, \vol_{n}(X). \tag{1}$$ The approximation becomes exact in the limit as $h \to 0$: $$\vol_{n-1}(\Bd X) = \lim_{h \to 0} \frac{(1 + h)^{n} - 1}{h}\, \vol_{n}(X) = \frac{d}{dt}\bigg|_{t = 1} \vol_{n}(tX). \tag{2}$$ By Property 1., if $r > 0$, then $$\vol_{n-1}\bigl(\Bd (rX)\bigr) = r^{n-1}\vol_{n-1}(\Bd X) = \lim_{h \to 0} \frac{(1 + h)^{n}r^{n} - r^{n}}{rh}\, \vol_{n}(X) = \frac{d}{dt}\bigg|_{t = r} \vol_{n}(tX). \tag{3}$$ In words, the $(n - 1)$-dimensional volume of $\Bd(rX)$ is the derivative with respect to $r$ of the $n$-dimensional volume of $rX$.
This argument fails for non-cubical boxes and ellipsoids (to name two) because for these objects, uniform scaling about an arbitrary point does not add a shell of uniform thickness (i.e., Property 2. fails). Equivalently, adding a shell of uniform thickness does not yield a new region similar to (i.e., obtained by uniform scaling from) the original.
(The argument also fails for cubes (etc.) not centered at the origin, again because "off-center" scaling does not add a shell of uniform thickness.)
In more detail:
• Scaling a non-square rectangle adds "thicker area" to the pair of short sides than to the long pair. Equivalently, adding a shell of uniform thickness around a non-square rectangle yields a rectangle having different proportions than the original rectangle.
• Scaling a non-circular ellipse adds thicker area near the ends of the major axis. Equivalently, adding a uniform shell around a non-circular ellipse yields a non-elliptical region. (The principle that "the derivative of area is length" fails drastically for ellipses: The area of an ellipse is proportional to the product of the axes, while the arc length is a non-elementary function of the axes.)
• +1 A fantastic answer! It is a shame that this answer is not getting as much attention as it deserves. The standard answer to this question is effectively "Well, it works by geometry, but let's not worry about why $S^n$ is a very special case." Instead, this answer really focuses on why it works, and how it generalizes. A very good answer indeed. Nov 1, 2015 at 19:17
• Thanks; glad you found it useful! It was pleasant to be able to add to a "first-thousand" post, not to mention getting to ponder a fun mathematical issue. Nov 1, 2015 at 21:45
• Could this be related to a special case of Reynolds transport theorem or generalized Differentiation under the integration rule? en.m.wikipedia.org/wiki/…
– Mann
May 29, 2020 at 21:57
The explanation is very simple. Take a sphere of radius $r$, volume $V$, and surface area $A$. Now paint it, with a layer of thickness $\delta r$. The volume of paint required is (to first order in $\delta r$) $A\delta r$, which gives you straight away: $$\delta V = A \delta r$$ Hence, in the limit:
$$\frac{dV}{dr} = A$$
• Most intuitive answer here. Aug 23, 2019 at 18:29
There is an article on the web that deals, in depth, with this question. Here is a quote from it:
“We were intrigued by the students' work, and this paper is the result of our attempt to answer the question, “When is surface area equal to the derivative of volume?"”
Here is the link:
www.math.byu.edu/~mdorff/docs/DorffPaper07.pdf
• Thank you, I've visited that article three times in the last couple years, it seems to be the definitive word on the matter. I'd like to add another article, one that takes a less formal route (I figured here was the best place.) It also examines when the volume-area-circumference relationships apply, and generalizes them to 2D polygons and 3D polyhedra. I hope others will find this article as helpful as I have. apcentral.collegeboard.com/apc/members/courses/teachers_corner/… Apr 3, 2017 at 4:48
The circle (and sphere) is not really that special. It also works for the square if you measure it using not the side length $s$, but half that, $h=s/2$. Then its area is $A=(2h)^2=4h^2$ with derivative $dA/dh=8h$ which is its perimeter.
• It works for the cube as well. Apr 24, 2014 at 0:18
• ... and Andrew D. Hwang's answer explains why. Oct 10, 2018 at 23:05
The size of the boundary times the rate at which the boundary moves equals the rate at which the size of the bounded region changes.
There appears to be no conventional name for this fact. I've called it the boundary rule sometimes.
I recommend the article by J. Tong, Area and perimeter, volume and surface area, College Math. J. 28 (1) (1997) 57. He shows that for any region where the area can be written as $A(s)=c s^2$ and the perimeter as $L(s)= k s$, you can set $x=(2c/k) s$, and you will get $A'(x)=L(x)$. That means that by careful parametrization, the above holds for rectangles and ellipses, too.
How does one set up the integral to find the area of a circle? An area was defined for a square or rectangle to be the width times the length. It is the equivalent for all geometries. For a circle working in polar coordinates the differential area equivalent is $dr$ while the differential width would be $r \,d\theta$.
So... $$dA = r\, d \theta\, dr.$$ Here $r \,d\theta$ is the differential arc (width) times the differential length $dr$. You can see that by inspecting the form of this differential equation the fundamental form for finding the area of a circle is in the form of what we know to be the circumference of a circle. If we divide through by $dr$. So the connection is implicit in the basic geometry. Because we are working in a polar system.
• You can use LaTeX pretty much as usual. Just enclose your formulas in dollar signs. For example, $\theta$ gives $\theta$.
– t.b.
Dec 6, 2011 at 14:52 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9018794894218445, "perplexity": 281.9990080329935}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030337307.81/warc/CC-MAIN-20221002083954-20221002113954-00120.warc.gz"} |
https://www.omnicalculator.com/math/golden-rectangle | # Golden Rectangle Calculator
By Mateusz Mucha and Piotr Małek
Last updated: Sep 18, 2020
Golden rectangle calculator determines the missing side and area of a golden rectangle.
The golden rectangle calculator will calculate the length of either side and the area of the golden rectangle, provided you give the other side. Before you use this calculator, you should understand what a golden rectangle is, how to calculate ratios in general and the formula for the golden ratio.
## What is the golden rectangle
The golden rectangle is a rectangle whose sides are in the golden ratio, that is `(a + b)/a = a/b`, where `a` is the width and `a + b` is the length of the rectangle. The ratio calculator is an effective tool to assist in calculating ratios in general, while the golden ratio calculator will do the same as the golden rectangle calculator with the exception of finding the area of the rectangle.
Want to know how to use our golden rectangle calculator? Here are the steps:
1. Enter the width `a`.
2. Enter the length `a + b` or segment `b`
3. Find the area `a * (a + b)`
4. If you know the area, divide by the missing part to get the other part.
5. Check your answer with the golden rectangle calculator.
An interesting aspect of the golden rectangle is that when the square section is removed, the remainder is another golden rectangle. Also, if you add another square to the rectangle with a side length of `a+b`, that is another golden rectangle. The golden rectangle calculator will verify this.
Mateusz Mucha and Piotr Małek
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https://www.gamedev.net/forums/topic/589192-making-a-mesh-face-a-directionpoint/ | # Making a mesh face a direction/point
This topic is 2791 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.
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I want my meshs to automaticaly face its objective( position to reach ), so each time a new objective is set I do this:
- calculate the desired direction( aimed position - current position )
- calculate the angle between current direction and desired direction
- update direction to desired direction
- rotate mesh by the angle computed on step 2
Since the aimed position and position are always on floor( y = 0.0 ), the rotation is on y only(xz plane), so I though it would be ok, but it doesnt work, the meshs face weird directions, I cant understand what is going on..Should it be working( theres a logical problem Im not seeing)?
And I also very curious on how Id do that if directions can face any way(not only xz plane)..My guess is to calculate the ortogonal vector between them, the angle between them, and rotate arround the vector by this angle..would it work?
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I actually just figured out how to do this myself. Assuming you want the z-axis to face the new point (which makes z rotation always 0), and that you have each axis in vector form (like (0,1,0) for the default up axis) you can do this (Look is the z axis, Up is the Y axis, and Right is the x axis in this function).
void PointObject(D3DXVECTOR3 TempPos)
{
Look=TempPos-Position;
D3DXVec3Normalize(&Look, &Look);
D3DXVECTOR3 Tempy=D3DXVECTOR3(0.0f,1.0f,0.0f);
D3DXVECTOR3 Tempx=D3DXVECTOR3(1.0f,0.0f,0.0f);
D3DXVec3Cross(&Right, &Tempy, &Look);
D3DXVec3Cross(&Up, &Look, &Right);
Yaw=acos(D3DXVec3Dot(&Tempx, &Right));
Pitch=acos(D3DXVec3Dot(&Tempy, &Up));
Roll=0.0f;
}
Basically, it subtracts Position (the object's position) from TempPos (the position you want to face) to get the directional vector, normalizes it and that makes the new z-axis. Then it uses a cross product of the default up axis and the new z-axis to get the new x-axis. Then it gets a cross product of the new z and x axis to get the new y axis.
Since z rotation is always zero, and the rotation of the axis you are calculating doesn't affect it's value (rotating around the default up axis would still be (0,1,0)), that leaves one rotation that could affect the axis you are calculating, either the x or y axis (depending on which one you are calculating).
To get the new Yaw, you get a dot product of the default x axis and the new x axis, which gives you the cosine of the angle which shows how much you are rotating around the y axis, because y rotation is the only thing that would affect the x axis. You get the acos of the dot product I just talked about (which is a cosine) and you have the new Yaw. To get Pitch, you do the same thing, you just get the dot product of the default y and new y axis and get the acos of.
Sorry if my explanation doesn't make sense, but the function I gave you should work. If you don't use direct x, any vector math library will work, so just modify the code to what you use if necessary.
In case you don't have the axes in vector form, you can get them in two ways. One, you can get them from the World Transformation matrix of your object. Say that m is a world transformation matrix. m[0][0 1 and 2] is the x, y, and z values of the x axis vector. m[1][0 1 and 2] for the y axis, and m[2][0 1 and 2] for the z axis, and m[3][0 1 and 2] has the x, y, and z position of the object itself. Or, you can use D3DXMatrixRotationAxis to get the axes when you add rotation to the object and use the axes to make the transformation matrix without having to do matrix multiplication (unless your scaling the matrix or something). You just make a matrix that rotates around the axis and apply it to the other two vectors with D3DXVec3TransformCoord or a similar command, like this
void SetYaw(float y)
{
Yaw+=y;
D3DXMATRIX m;
D3DXMatrixRotationAxis(&m, &Up, y);
D3DXVec3TransformCoord(&Look, &Look, &m);
D3DXVec3TransformCoord(&Right, &Right, &m);
//Do the same thing for the Pitch and Roll, just change the axis rotation matrix accordingly
}
Just make sure your axis vectors are set to the default axes when you first make the object, (1,0,0) for the x axis, etc. Since you have the axes in vector form and the position of your object, you can make a matrix and just fill it in like I showed above to make the world transformation matrix for the object. There is some other stuff you need to fill in, I'll edit this post and put it in when I get back to my programming computer.
That was a longer post then I thought it would be, my bad :) I hope this helps.
Edit Here's the code for it where matWorld is a D3DXMATRIX(or any 4 by 4 matrix)
matWorld._11=Right.x;
matWorld._12=Right.y;
matWorld._13=Right.z;
matWorld._14=0;
matWorld._21=Up.x;
matWorld._22=Up.y;
matWorld._23=Up.z;
matWorld._24=0;
matWorld._31=Look.x;
matWorld._32=Look.y;
matWorld._33=Look.z;
matWorld._34=0;
matWorld._41=Position.x;
matWorld._42=Position.y;
matWorld._43=Position.z;
matWorld._44=1;
[Edited by - Kryogenik on November 30, 2010 12:34:30 PM]
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Im using xnamath, I kind didnt like your approach of editing the world matrix directly, since with xna math acessing things is a pain..
Did you post the way you would do that or you think I cant do this the way I was thinking?
I did a test scene to try figure out something, so I have a ball centered at origin and another ball that I can move with the keyboard, so I did what I explained in the first post to make the center ball face the moving ball..
It works =D..but just for clockwise rotations D=..Im guessing the function XMVector3AngleBetweenVectors returns the smaller angle(always positive) between vectors..I think that would explain the behavior..
If is not quite clear is like that: If I move the ball arround the center ball in clockwise, the ball face just right( you can say that because if the moving ball is closer, it rotates faster, and if u move away on a straigh line it doesnt move, etc., its clear it is working), but if you starting move in the other direction, the ball keeps rotating always clockwise..
Heres the code Im using:
//updates moving ball world matrix: //translate: litblock.dxMesh.mWorld *= XMMatrixTranslationFromVector( vVelocity ); //back to origin: litblock.dxMesh.mWorld *= XMMatrixTranslationFromVector( -vPosition ); //rotate(reorient): litblock.dxMesh.mWorld *= XMMatrixRotationY( /*fangletest*/fAngleOrient*(FLOAT)sec ); //back to actual position: litblock.dxMesh.mWorld *= XMMatrixTranslationFromVector( vPosition );//face center ball: XMVECTOR aimpos = XMVector3Normalize( vPosition ); aimpos = XMVectorSetW( aimpos, 1.0f );//also direction, cause ball is at origin static XMVECTOR directiontest = XMVectorSet( 0.0f, 0.0f, 1.0f, 1.0f ); FLOAT fangletest = XMVectorGetX( XMVector3AngleBetweenVectors( aimpos, directiontest )); directiontest = aimpos;//update direction //world matrix start as identity mfacingballWorld *= XMMatrixRotationY( fangletest );
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Yeah, so I just puted my brain to remember basic maths..>_> you just keep away from it for a month and they go away from your mind..
So Im getting the angle as I said, and then I compute the cross product checking for the y value, if y is < 0(left turn), then I negate the angle..works like a charm...
But I dont know how I would do that for any direction(not only on xz, again..)I mean, this just works for 2D right? Well, i know 2 vectors are always on a plane..@_@ that is how far I can go..
How I would do that?( find a way to rotate the plane so it align to an axis plane(xy or xz), and then compute the cross? thats looks too overheaded )
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The easiest way to "face" a location is just build a look-at matrix.
You set the Z (at) to the normalized direction to the target. Then create a X (left) and Y (up) vector that are perpendicular.
pseudo:
z = normalize( their_pos - my_pos );
y = (0,1,0);
x = y cross z;
y = z cross x;
You do have to check one edge case, if z dot (0,1,0) ~= 1, then you have an issue. You have to pick y = (1,0,0) or something to compensate.
If you want to perform a smooth rotation to look there, use the Slerp operation. The easiest way to do this is create a quaternion out of your current and target rotations. Then Slerp the quaternions by some factor. Then convert back to a matrix.
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× | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.31229153275489807, "perplexity": 1489.6164439063082}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676593051.79/warc/CC-MAIN-20180722061341-20180722081341-00532.warc.gz"} |
http://www.physicsforums.com/showthread.php?t=216758 | # Induction? question
by rsa58
Tags: induction
P: 85 the question is: let k, n, and k1, . . . , kn be given natural numbers, such that k1 + . . . + kn = k. Assume that k musicians shall be distributed to n orchestras such that exactly ki musicians play in the ith orchestra. Prove that there exist exactly k!/(k1! · · · kn!) different distributions. is it possible to use induction to answer this? i can prove it by using the choose function to find all the possible distributions. in that way i get a proof for the statement, but i am unable to assume that it is correct for n, and then show it is correct for n+1. can someone give me some ideas? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9870041012763977, "perplexity": 386.012347891333}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997894865.50/warc/CC-MAIN-20140722025814-00115-ip-10-33-131-23.ec2.internal.warc.gz"} |
http://math.stackexchange.com/questions/88386/diffeomorphism-group-of-the-unit-circle | # Diffeomorphism group of the unit circle
I am given to understand that the group of diffeomorphisms of the unit circle, $\operatorname{Diff}(\mathbb{S}^1)$, has two connected components, $\operatorname{Diff}^+(\mathbb{S}^1)$ and $\operatorname{Diff}^-(\mathbb{S}^1)$, the diffeomorphisms that preserve or reverse the canonical (counterclockwise) orientation, respectively.
Question 1: How does one prove that?
Question 2: Given $\Phi, \Psi \in \operatorname{Diff}^+(\mathbb{S^1})$, can one construct an explicit path joining them?
I'd be satisfied already with a proof that we can join $\Psi, \Phi \in \operatorname{Diff}^+ (\mathbb{S}^1)$, without giving the path explicitly. I tried the obvious path, $t \mapsto \dfrac{t\Phi + (1-t)\Psi}{|t\Phi + (1-t)\Psi|}$, but that doesn't seem to work.
Thanks.
-
I don't know how relevant it is, but in case anyone is wondering, consider the compact-open topology on $Diff(\mathbb{S}^1)$. – student Dec 4 '11 at 23:08
It is enough to connect everything in the positive part to the identity. To do that, pick a diffeo and lift it to a map $\mathbb R\to\mathbb R$. Then interpolate with a map given by a translation. Then descend back to the circle. – Mariano Suárez-Alvarez Dec 4 '11 at 23:12
@Leandro It seems pretty relevant! – Dylan Moreland Dec 5 '11 at 0:48
Question 2:
As Mariano points out, we can lift $\Phi \in \operatorname{Diff}^+{(\mathbb S^1)}$ uniquely to a diffeomorphism $\phi : \mathbb{R} \to \mathbb{R}$ such that $\phi(0) \in [0,1)$ and $\phi(x+1) = \phi(x) + 1$ for all $x \in \mathbb{R}$. Lift $\Psi$ similarly to $\psi$. For $t \in [0,1]$ the map $\gamma_t = (1-t) \phi + t\psi$ is a diffeomorphism $\mathbb{R} \to \mathbb{R}$ (it is strictly monotonically increasing because $\gamma_{t}^\prime(x) \gt 0$ for all $x \in \mathbb{R}$ and all $t \in [0,1]$) such that $\gamma_t(0) \in [0,1)$ and $\gamma_t(x+1) = \gamma_t(x)+1$. Thus $\gamma_t$ descends to a diffeomorphism $\Gamma_t \in \operatorname{Diff}^+(\mathbb{S}^1)$, $\Gamma_0 = \Phi$ and $\Gamma_1=\Psi$. It is straightforwad to check that $t \mapsto \Gamma_t$ is a continuous path.
What we exploited here is that we have a short exact sequence (in fact a central extension) $$0 \to \mathbb{Z} \to \operatorname{Diff}_{\mathbb{Z}}{(\mathbb{R})} \to \operatorname{Diff}^+{(\mathbb{S}^1)} \to 1$$ where $\operatorname{Diff}_{\mathbb{Z}}{(\mathbb{R})}$ denotes the group of diffeomorphisms $\mathbb{R} \to \mathbb{R}$ commuting with the shift $\tau(x) = x+1$ and $\mathbb{Z} = \langle \tau \rangle$ and the lift $\Phi \mapsto \phi$ is a section of this central extension.
Question 1:
It is clear that a diffeomorphism $\mathbb{S}^1 \to \mathbb{S}^1$ either preserves or reverses orientation and that the orientation-preserving diffeomorphisms $\operatorname{Diff}^+{(\mathbb{S}^1)}$ form a normal subgroup of $\operatorname{Diff}{(\mathbb{S}^1)}$. Now simply use the conjugation diffeomorphism $z \mapsto \bar{z}$ to see that $\operatorname{Diff}^+{(\mathbb{S}^1)}$ has index 2.
For an excellent introduction to $\operatorname{Homeo}^+{(\mathbb{S}^1)}$ and $\operatorname{Diff}^+{(\mathbb{S}^1)}$ and their subgroups I recommend Étienne Ghys's article Groups acting on the circle, Enseign. Math. (2) 47 (2001), no. 3–4, 329–407, MR2111644. The short exact sequence mentioned above plays a central rôle in the theory.
For more on the diffeomorphism group of the circle, I recommend consulting the work of Andrés Navas, and, of course, the classic article:
Michael R. Herman, Sur la conjugaison différentiable des difféomorphismes du cercle à des rotations, Publications Mathématiques de l'IHÉS, 49 (1979), p. 5–233.
-
Excellent answer, and I'll certainly look up those references. Thanks a lot. – student Dec 5 '11 at 0:59
What does $0$ mean in your exact sequence? – Alexei Averchenko Dec 6 '11 at 5:20
@Alexei: $0$ as $0 \in \mathbb{Z}$, which is the neutral element and can be identified with the trivial group. – t.b. Dec 6 '11 at 5:22 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9453662037849426, "perplexity": 173.32099516394698}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-26/segments/1466783403823.74/warc/CC-MAIN-20160624155003-00194-ip-10-164-35-72.ec2.internal.warc.gz"} |
https://www.gradesaver.com/textbooks/math/algebra/algebra-a-combined-approach-4th-edition/chapter-10-section-10-5-rationalizing-numerators-and-denominators-of-radical-expressions-exercise-set-page-718/70 | Algebra: A Combined Approach (4th Edition)
$\dfrac{5+\sqrt{2}}{\sqrt{2x}}=\dfrac{23}{5\sqrt{2x}-2\sqrt{x}}$
$\dfrac{5+\sqrt{2}}{\sqrt{2x}}$ Multiply the numerator and the denominator by the conjugate of the numerator and simplify if possible: $\dfrac{5+\sqrt{2}}{\sqrt{2x}}=\dfrac{5+\sqrt{2}}{\sqrt{2x}}\cdot\dfrac{5-\sqrt{2}}{5-\sqrt{2}}=\dfrac{5^{2}-(\sqrt{2})^{2}}{\sqrt{2x}(5-\sqrt{2})}=...$ $...=\dfrac{25-2}{5\sqrt{2x}-\sqrt{4x}}=\dfrac{23}{5\sqrt{2x}-2\sqrt{x}}$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9998403787612915, "perplexity": 310.3282333546214}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-17/segments/1524125948285.62/warc/CC-MAIN-20180426144615-20180426164615-00217.warc.gz"} |
https://cs.stackexchange.com/questions/125670/regular-language-as-finite-union-of-periodic-sets/130155 | # Regular language as finite union of periodic sets
Is it true that every regular language can be expressed as a finite union of periodic sets? In other words, if $$L$$ is regular, then do there exist finite sets $$A_1,\dots,A_n,B_1,\dots,B_n$$ such that
$$L = A_1 \cdot B_1^* \cup \cdots \cup A_n \cdot B_n^*.$$
I know this is true for regular languages over a unary alphabet, but I'm not sure about general alphabets.
Every language of this form can be represented as a regular expression without nested Kleene star. That is, its star height is $$1$$. The star height hierarchy is strict, and in particular, it is known that the language $$(a^*b^*c)^*$$ cannot be represented in that form. An example over a binary alphabet would be $$(aa(ab)^*bb(ab)^*)^*$$.
The answer by @YuvalFilmus is perfectly fine, and points you to the import notion of star height. But let me add a little bit more. We will show that languages of your form give a proper subset of the languages of star height one. But first, some musings what might come close to your form.
General Regular Languages
First, probably the closest form to yours for regular $$L \subseteq \Sigma^*$$, accepted by a complete deterministic automaton $$A = (\Sigma, Q, \delta, q_0, F)$$. For $$q \in Q$$ and $$E \subseteq Q$$, write $$L_{q, E}(A)$$ for the language accepted by $$(\Sigma, Q, \delta, q, E)$$, i.e., changing the start state to $$q$$ and the set of final states to $$E$$. Then, we can write $$L = \bigcup_{ q \in F } L_{q_0, q}(A) L_{q, \{q\}}(A)^*$$ This result seems to be folklore and follows easily. A more refined variant of this decomposition appears in the book Automata, Languages and Machines, Volume A by S. Eilenberg, under the name iterated up-decomposition.
Commutative and Bounded Regular Languages
Others forms, more close to yours, and being proper generalizations of the unary language case you mentioned, could be given for the bounded and commutative regular languages. A language is commutative, if it is closed under permutation of letters. For example, $$\{ab,ba\}$$ is commutative, whereas $$\{ab\}$$ is not. A language $$L \subseteq \Sigma^*$$ is bounded, if $$L \subseteq w_1^* \cdots w_n^*$$ for words $$w_i \in \Sigma^*$$. In what follows, let us denote by $$\diamond$$ the shuffle of two languages, and, for $$L \subseteq \Sigma^*$$, by $$L^{\diamond,*} = \bigcup_{n \ge 0} \underbrace{L \diamond \ldots \diamond L}_{\mbox{n times}}$$ the iterated shuffle. Also, by $$\operatorname{perm} : 2^{\Sigma^*} \to 2^{\Sigma*}$$ denote the permutational closure, or commutative closure, i.e. adding all words that are permutations. For example, $$\operatorname{perm}(\{ab\}) = \{ab,ba\}$$.
Note that $$L \subseteq w^*$$ is regular iff $$L = w^n(w^p)^*$$ for some $$n, p \ge 0$$. This is implied by noting that $$\{ n : w^n \in L \}$$ is ultimately periodic (it could be viewed as a regular unary language).
By a result of Ginsburg/Spanier we have
A language $$L \subseteq w_1^* \cdots w_r^*$$ is regular iff it is a finite union of languages of the form $$L_1 \cdots L_r$$, where each $$L_i \subseteq w_i^*$$ is regular.
Also, if $$\Sigma = \{a_1, \ldots, a_k\}$$ and $$L \subseteq \Sigma^*$$ is commutative and regular, it is possible to show that $$L = \bigcup_{i=1}^n \operatorname{perm}(u_i) \diamond \operatorname{perm}(N_i)^{\diamond,*}$$ for finite sets $$N_i \subseteq a_1^* \cup \ldots \cup a_k^*$$ with $$|N_i \cap a_j^*| \le 1$$.
Also, as stated here and here, a regular language $$L$$ over $$\Sigma = \{a_1, \ldots, a_k\}$$ is commutative iff $$L = \bigcup_{i=1}^n U_{i,1} \diamond \ldots \diamond U_{i,k}$$ for unary regular languages $$U_{i,j} \subseteq a_j^*$$ with $$i \in \{1,\ldots, n\}$$ and $$j \in \{1,\ldots,k\}$$.
All these results are closely related. Note that for unary languages, they all reduce to the form you have stated.
A Necessary Condition for Languages of your Form
The condition I will state involves topology and infinite words. It yields, for example, that $$b^*a$$ and $$(b^*a)^*$$ could not be written in your form. The latter has star height two, note that star height could be characterized by cycle rank, see Eggan's Theorem. However, I do want to give a self-contained, and different, argument here, not based on star height. Let $$\Sigma^{\omega}$$ be the set of infinite words over $$\Sigma$$. Define an operator $$W : 2^{\Sigma^*} \to 2^{\Sigma^{\omega}}$$ by, for $$L \subseteq \Sigma^*$$, $$W(L) = \{ \xi \in \Sigma^{\omega} \mid \mbox{ \xi has infinitely many prefixes in L } \}.$$ Then \begin{align*} W(b^*a) & = \emptyset \\ W((b^*a)^*) & = \{ \xi \in \Sigma^{\omega} \mid \mbox{\xi has infinitely many a's. } \}. \end{align*} Observe that $$W(U \cup V) = W(U) \cup V(V),$$ as, if $$\xi \in W(U\cup V)$$, then, by the pigenhole principle, at least one of $$U$$ or $$V$$, or both, must contain infinitely many prefixes of $$\xi$$. Also, in your form we could assume all the sets $$A_i$$ are singletons, as concatenation distributes over union.
Let us inspect languages of the form $$L = u(u_1 + \ldots + u_n)^*$$, which are the parts of your form. Set $$\Gamma = \{ b_1, \ldots, b_n \}$$, an auxiliary alphabet, and consider the homomorphism $$h : \Gamma \to \Sigma^*$$ given by $$h(b_i) = u_i$$, i.e., substituting each letter by the corresponding word. This homomorphism could also be applied to infinite words in $$\Gamma^{\omega}$$. We have $$W(u(u_1 + \ldots + u_n)^*) = \{ uh(\xi) \mid \xi \in \Gamma^{\omega} \}.$$ In particular, if all the set $$B_i$$ are singletons, $$W(L)$$ is finite, and $$W(L) \ne \emptyset$$ for every infinite language of your form.
By the last observation, $$b^*a$$ could not be written in your form. So, this is a very simple example, even of star height one. But let us show that $$L = (b^*a)^*$$ could also not be written that way. Assume it could be, then the set of infinite words, which all have an infinite number of $$a$$'s in it, could be written in terms of a homomorphism $$h : \Gamma^* \to \Sigma^*$$ as outlined above, i.e., $$\{ \xi \in \Sigma^{\omega} \mid \mbox{\xi has infinitely many a's. } \} = u h(\Gamma^{\omega})$$ for some $$u \in \Sigma^*$$. Let $$m = \{ |h(x)| : x \in \Gamma \} + |u|$$. Then $$ub^maaaaa\cdots$$ is in this language, and this implies $$h(x) \in b^+$$ for some $$x \in \Gamma$$. But then $$ubbbbbbb\cdots \in uh(\Gamma^{\omega})$$, which is a contradiction, as it only contains a finite number of $$a$$'s. Hence, $$(b^*a)^*$$ could not be written that way. $$\square$$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 80, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9637077450752258, "perplexity": 164.34585227222155}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038469494.59/warc/CC-MAIN-20210418073623-20210418103623-00627.warc.gz"} |
https://oneclass.com/class-notes/ca/utsc/bio/bioc-50h3/96-lecture-note-15-for-bgyb50.en.html | Class Notes (1,200,000)
CA (650,000)
UTSC (30,000)
Lecture
# lecture note 15 for BGYB50
by
Department
Biological Sciences
Course Code
BIOC50H3
Professor
Herbert Kronzucker
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LECTURE 15:
- Despite what politicians and economists would like you to believe, unbridled growth is
not possible all growth in nature has its limits!
- Biological populations grow at widely differing rates, and they can grow exponentially
(or geometrically) for some time, but the rate of increase will ultimately flatten out
(logistic or sigmoidal growth), or the population collapses (irruptive growth); sometimes,
oscillations in population density are observed (partial collapses that are followed by
recovery)
- Both irruptive and oscillatory growth are common among bacteria and viruses, but also
occur in mammals (e.g. snowshoe hare and Canadian lynx)
- Graphically, geometric growth (Nt = N0 !t; geometric rate of increase: ! = Nt+1/Nt)
results in a J-curve pattern resembling exponential growth (Nt = N0 ert, i.e. ! = er), but the
former is used to describe J-curve-type growth in discretely-growing populations (e.g.
annual plants like many grasses or Phlox, with bursts of seed production, rather then
overlapping generations of reproducing individuals; points in such graphs should NOT be
connected!), while the latter is observed in populations with overlapping generations (e.g.
Scotch pine colonization after the last ice age in Europe, collared doves introduced to
Britain; by definition, the e function can only be used to model continuous growth!)
- Each environment imposes different limits upon natural population increase: this is
known as the carrying capacity (K) of each environment, i.e. the maximal sustainable
number of individuals of a population in that environment
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https://www.coin-or.org/CppAD/Doc/tracknewdel.htm | Prev Next Index-> contents reference index search external Up-> CppAD Appendix deprecated TrackNewDel CppAD-> Install Introduction AD ADFun preprocessor multi_thread utility ipopt_solve Example speed Appendix Appendix-> Faq directory Theory glossary Bib wish_list whats_new deprecated compare_c numeric_ad addon License deprecated-> include_deprecated FunDeprecated CompareChange omp_max_thread TrackNewDel omp_alloc memory_leak epsilon test_vector cppad_ipopt_nlp old_atomic zdouble autotools TrackNewDel-> TrackNewDel.cpp Headings-> Deprecated 2007-07-23 Syntax Purpose Include file line oldptr newlen head newptr ncopy TrackNewVec ---..Macro ---..Previously Deprecated TrackDelVec ---..Macro ---..Previously Deprecated TrackExtend ---..Macro ---..Previously Deprecated TrackCount ---..Macro ---..Previously Deprecated Multi-Threading Example
$\newcommand{\W}[1]{ \; #1 \; } \newcommand{\R}[1]{ {\rm #1} } \newcommand{\B}[1]{ {\bf #1} } \newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} } \newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} } \newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} } \newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }$
Routines That Track Use of New and Delete
Deprecated 2007-07-23
All these routines have been deprecated. You should use the thread_alloc memory allocator instead (which works better in both a single thread and properly in multi-threading environment).
Syntax
# include <cppad/utility/track_new_del.hpp> newptr = TrackNewVec(file, line, newlen, oldptr) TrackDelVec(file, line, oldptr) newptr = TrackExtend(file, line, newlen, ncopy, oldptr) count = TrackCount(file, line)
Purpose
These routines aid in the use of new[] and delete[] during the execution of a C++ program.
Include
The file cppad/track_new_del.hpp is included by cppad/cppad.hpp but it can also be included separately with out the rest of the CppAD include files.
file
The argument file has prototype const char *file It should be the source code file name where the call to TrackNew is located. The best way to accomplish this is the use the preprocessor symbol __FILE__ for this argument.
line
The argument line has prototype int line It should be the source code file line number where the call to TrackNew is located. The best way to accomplish this is the use the preprocessor symbol __LINE__ for this argument.
oldptr
The argument oldptr has prototype Type *oldptr This argument is used to identify the type Type .
newlen
The argument newlen has prototype size_t newlen
head newptr
The return value newptr has prototype Type *newptr It points to the newly allocated vector of objects that were allocated using new Type[newlen]
ncopy
The argument ncopy has prototype size_t ncopy This specifies the number of elements that are copied from the old array to the new array. The value of ncopy must be less than or equal newlen .
TrackNewVec
If NDEBUG is defined, this routine only sets newptr = Type new[newlen] The value of oldptr does not matter (except that it is used to identify Type ). If NDEBUG is not defined, TrackNewVec also tracks the this memory allocation. In this case, if memory cannot be allocated ErrorHandler is used to generate a message stating that there was not sufficient memory.
Macro
The preprocessor macro call CPPAD_TRACK_NEW_VEC(newlen, oldptr) expands to CppAD::TrackNewVec(__FILE__, __LINE__, newlen, oldptr)
Previously Deprecated
The preprocessor macro CppADTrackNewVec is the same as CPPAD_TRACK_NEW_VEC and was previously deprecated.
TrackDelVec
This routine is used to a vector of objects that have been allocated using TrackNew or TrackExtend. If NDEBUG is defined, this routine only frees memory with delete [] oldptr If NDEBUG is not defined, TrackDelete also checks that oldptr was allocated by TrackNew or TrackExtend and has not yet been freed. If this is not the case, ErrorHandler is used to generate an error message.
Macro
The preprocessor macro call CPPAD_TRACK_DEL_VEC(oldptr) expands to CppAD::TrackDelVec(__FILE__, __LINE__, oldptr)
Previously Deprecated
The preprocessor macro CppADTrackDelVec is the same as CPPAD_TRACK_DEL_VEC was previously deprecated.
TrackExtend
This routine is used to allocate a new vector (using TrackNewVec), copy ncopy elements from the old vector to the new vector. If ncopy is greater than zero, oldptr must have been allocated using TrackNewVec or TrackExtend. In this case, the vector pointed to by oldptr must be have at least ncopy elements and it will be deleted (using TrackDelVec). Note that the dependence of TrackExtend on NDEBUG is indirectly through the routines TrackNewVec and TrackDelVec.
Macro
The preprocessor macro call CPPAD_TRACK_EXTEND(newlen, ncopy, oldptr) expands to CppAD::TrackExtend(__FILE__, __LINE__, newlen, ncopy, oldptr)
Previously Deprecated
The preprocessor macro CppADTrackExtend is the same as CPPAD_TRACK_EXTEND and was previously deprecated.
TrackCount
The return value count has prototype size_t count If NDEBUG is defined, count will be zero. Otherwise, it will be the number of vectors that have been allocated (by TrackNewVec or TrackExtend) and not yet freed (by TrackDelete).
Macro
The preprocessor macro call CPPAD_TRACK_COUNT() expands to CppAD::TrackCount(__FILE__, __LINE__)
Previously Deprecated
The preprocessor macro CppADTrackCount is the same as CPPAD_TRACK_COUNT and was previously deprecated.
Multi-Threading
These routines cannot be used in_parallel execution mode. Use the thread_alloc routines instead.
Example
The file TrackNewDel.cpp contains an example and test of these functions. It returns true, if it succeeds, and false otherwise.
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http://delay-tolerant-networks.blogspot.com/2014/03/commonly-used-metrics.html | Skip to main content
### Commonly Used Metrics for Performance Evaluation
The following metrics are commonly used when evaluating scenarios related to DTN protocols.
• Delivery ratio of the messages,
• Average message delivery latency
• Overhead ratio (of the underlying routing mechanism)
Suppose that $M$ be the set of all messages created in the network and $M_d$ be the set of all messages delivered. Then, the delivery ratio is computed as $|M_d| / |M|$.
Now let the $i^{th}$ delivered message was created at time $c_i$ and delivered at time $d_i$. Then the average message delivery latency is computed as $(\sum_{i = 1}^{|M_d|} (d_i - c_i)) / |M_d|$. Note that, in Statistics, mean, median and mode are all the measures of average. But "loosely speaking", unless otherwise specified, we refer to the "mean" value when we say "average." Nevertheless, the MessageStatsReport in the ONE simulator provides a measure of both the mean and median values wherever appropriate.
One may refer the above metric as "end-to-end delay." Personally, I think such usage is inappropriate given that, by definition, DTNs typically lack end-to-end paths.
Finally, let $r_i$ be the number of replications of any message $m_i \in M$. Then the overhead ratio is determined as $(\sum_{i = 1}^{|M|} r_i - |M_d|) / M_d$.
The above definitions are generic. However, if you feel that they are helpful and wish to incorporate into your research article, you may consider citing it as:
B. K. Saha (2014, Mar.) Commonly Used Metrics for Performance Evaluation. Accessed: DD Mon. YYYY. [Online]. Available: http://delay-tolerant-networks.blogspot.com/2014/03/commonly-used-metrics.html
### Specifying Source and Destination of Messages
One of the frequently asked questions in the community is how to specify which particular nodes would act as source(s) and destination(s) of the messages created in the ONE simulator. The simulator, in fact, provides a pair of settings (shown below in bold face) aimed for this particular purpose.
Let us consider that there are $n + 1$ nodes in an OMN. Further, let the nodes with addresses from $x$ to $y$, both inclusive, would create messages. The nodes in the range $w$ to $z$, both inclusive, would be the destinations of those messages, where $0 \le x \le y \le n$, and $0 \le w \le z \le n$. Then, the corresponding simulation scenario can be configured as follows.
## Message creation parameters # How many event generators Events.nrof = 1 # Class of the first event generator Events1.class = MessageEventGenerator # (Following settings are specific for the MessageEventGenerator class) # Creation interval in seconds (one new message every 25 to 35 seconds) Events1.interval = 25,35 # Me…
### Effects of Buffer Size on Delay Tolerant Routing
In this post, we look at how buffer size affects, if at all, the performance of the routing protocols in DTNs. For this purpose, we will consider the following five routing protocols:
EpidemicPROPHETSpray-and-Wait (SnW) First Contact (FC) Direct Delivery (DD) Detailed discussion of these protocols is scoped out here. We just note that in case of Epidemic, there is unlimited replication of the messages. In PROPHET, however, the replication is usually less than that of Epidemic. On the other hand, SnW has a fixed limit (L) on possible number of replications of a message. Finally, FC and DD involve message forwarding -- not replication. So, in the latter cases, there is always a single copy of any message in the DTN.
We will consider the buffer sizes from 20 MB to 180 MB, both inclusive, in steps of 20 MB so that we have total 9 different buffer sizes. We will use the real-life connection traces from Infocom'06. Therefore, we will need to simulate 5 * 9 = 45 scenarios to get the rel…
### Controlling Transmission Range from within the Simulation
While simulating scenarios with the ONE simulator, one typically defines one or more network interfaces, and add them to the nodes as required. This use case prevails in most of the scenarios. However, a drawback here is that different network interfaces are mutually incompatible — an interface of type 1 can't communicate with any interface not of type 1.
Under certain circumstances, it might be required to control the transmission range of one or more network interfaces dynamically from within the simulation. For example, in one of my works, "On emotional aspects in Mission-Oriented Opportunistic Networks", I have considered the case where users occasionally turn off their device radios based on their contemporary emotions. In particular, the following shows how to set the radio range to 0: ModuleCommunicationBus comBus = host.getComBus(); // Store the original radio range the first time it is reset if (this.originalRadioRange == -1) { this.originalRadioRange = Double… | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7676288485527039, "perplexity": 1289.217319325697}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948541253.29/warc/CC-MAIN-20171214055056-20171214075056-00359.warc.gz"} |
https://brainder.org/2016/02/08/npc/ | # Non-Parametric Combination (NPC) for brain imaging
Have you ever had an analysis in which there was a large set of contrasts, all of interest, and you were worried about multiple testing? An eventual effect would be missed by a simple Bonferroni correction, but you did not know what else to do? Or did you have a set of different studies and you wished to obtain a style of meta-analytic result, indicating whether there would be evidence across all of them, without requiring the studies to be all consistently significant?
The Non-Parametric Combination (NPC) solves these issues. It is a way of performing joint inference on multiple data collected on the same experimental units (e.g., same subjects), all with minimal assumptions. The method was proposed originally by Pesarin (1990, 1992) [see references below], independently by Blair and Karninski (1993), and described extensively by Pesarin and Salmaso (2010). In this blog entry, the NPC is presented in brief, with emphasis on the modifications we introduce to render it feasible for brain imaging. The complete details are in our paper that has just been published in the journal Human Brain Mapping.
## NPC in a nutshell
The NPC consists of, in a first phase, testing each hypothesis separately using permutations that are performed synchronously across datasets; these tests are termed partial tests. The resulting statistics for each and every permutation are recorded, allowing an estimate of the complete empirical null distribution to be constructed for each one. In a second phase, the empirical p-values for each statistic are combined, for each permutation, into a joint statistic. As such a combined joint statistic is produced from the previous permutations, an estimate of its empirical distribution function is immediately known, and so is the p-value of the joint test. A flowchart of the original algorithm is shown below; click to see it side-by-side with the modified one (described below).
## A host of combining functions
The null hypothesis of the NPC is that null hypotheses for all partial tests are true, and the alternative hypothesis that any is false, which is the same null of a union-intersection test (UIT; Roy, 1953). The rejection region depends on how the combined statistic is produced. Various combining functions, which produce such combined statistics, can be considered, and some of the most well known are listed in the table below:
Method Statistic p-value
Tippett $\min \left(p_{k}\right)$ $1-\left(1-T\right)^{K}$
Fisher $-2 \sum_{k=1}^{K} \ln\left(p_{k}\right)$ $1-\chi^{2}\left(T;\;\nu=2K\right)$
Stouffer $\frac{1}{\sqrt{K}} \sum_{k=1}^{K} \Phi^{-1}\left(1-p_{k}\right)$ $1-\Phi\left(T;\;\mu=0,\;\sigma^2=1\right)$
Mudholkar–George $\frac{1}{\pi}\sqrt{\frac{3(5K+4)}{K(5K+2)}}\sum_{k=1}^{K} \ln\left(\frac{1-p_{k}}{p_{k}}\right)$ $1-t_{\text{cdf}}(T;\;\nu=5K+4)$
In the table, $K$ is the number of partial tests, and the remaining of the variables follow the usual notation (see the Table 1 in the paper for the complete description). Many of these combining functions were proposed over the years for applications such as meta-analyses, and many of them assume independence between the tests being combined, and will give incorrect p-values if such assumption is not met. In the NPC, lack of dependence is not a problem, even if these same functions are used: the synchronised permutations ensure that any dependence, if existing, is taken into account, and this is done so implicitly, with no need for explicit modelling.
The different combining functions lead to different rejection regions for the null hypothesis. For the four combining functions in the table above, the respective rejection regions are in the figure below.
The combining functions can be modified to allow combination of tests so as to favour hypotheses with concordant directions, or be modified for bi-directional tests. Click on the figure above for examples of these cases (again, see the paper for the complete details).
## Two problems, one solution
The multiple testing problem is well known in brain imaging: as an image comprises thousands of voxels/vertices/faces, correction is necessary. Bonferroni is in general too conservative, and various other approaches have been proposed, such as the random field theory. Permutation tests provide control over the familywise error rate (FWER) for the multiple tests across space, requiring only the assumption of exchangeability. This is all well known; see Nichols and Hayasaka (2003) and Winkler et al. (2014) for details.
However, another type of multiple testing is also common: analyses that test multiple hypotheses using the same model, multiple pairwise group comparisons, multiple and distinct models, studies using multiple modalities, that mix imaging and non-imaging data, that consider multiple processing pipelines, and even multiple multivariate analyses. All these common cases also need multiple testing correction. We call this multiple testing problem MTP-II, to discern it from the well known multiple testing problem across space, described above, which we term MTP-I.
One of the many combining functions possible with NPC, the one proposed by Tippett (1931), has a further property that makes it remarkably interesting. The Tippett function uses the smallest p-value across partial tests as its test statistic. Alternatively, if all statistics are comparable, it can be formulated in terms of the maximum statistic. It turns out that the distribution of the maximum statistic across a set of tests is also the distribution that can be used in a closed testing procedure (Marcus et al., 1976) to correct for the familywise error rate (FWER) using resampling methods, such as permutation. In the context of joint inference, FWER-correction can also be seen as an UIT. Thus, NPC offers a link between combination of multiple tests, and correction for multiple tests, in both cases regardless of any dependence between such tests.
This means that the MTP-II, for which correction in the parametric realm is either non-existing or fiendishly difficult, can be accommodated easily. It requires no explicit modelling of the dependence between the tests, and the resulting error rates are controlled exactly at the test level, adding rigour to what otherwise could lead to an excess of false positives without correction, or be overly conservative if a naïve correction such as Bonferroni were attempted.
## Modifying for imaging applications
As originally proposed, in practice NPC cannot be used in brain imaging. As the statistics for all partial tests for all permutations need to be recorded, an enormous amount of space for data storage is necessary. Even if storage space were not a problem, the discreteness of the p-values for the partial tests is problematic when correcting for multiple testing, because with thousands of tests in an image, ties are likely to occur, further causing ties among the combined statistics. If too many tests across an image share the same most extreme statistic, correction for the MTP-I, while still valid, becomes less powerful (Westfall and Young, 1993; Pantazis et al., 2005). The most obvious workaround — run an ever larger number of permutations to break the ties — may not be possible for small sample sizes, or when possible, requires correspondingly larger data storage.
The solution is loosely based on the direct combination of the test statistics, by converting the test statistics of the partial tests to values that behave as p-values, using the asymptotic distribution of the statistics for the partial tests. We call these as “u-values”, in order to emphasise that they are not meant to be read or interpreted as p-values, but rather as transitional values that allow combinations that otherwise would not be possible.
For spatial statistics, the asymptotic distribution of the combined statistic is used, this time to produce a z-score, which can be subjected to the computation of cluster extent, cluster mass, and/or threshold-free cluster enhancement (TFCE; Smith and Nichols, 2009). A flow chart of the modified algorithm is shown below. Click to see it side-by-side with the original.
## More power, fewer assumptions
One of the most remarkable features of NPC is that the synchronised permutations implicitly account for the dependence structure among the partial tests. This means that even combining methods originally derived under the assumption of independence can be used when such independence is untenable. As the p-values are assessed via permutations, distributional restrictions are likewise not necessary, liberating NPC from most assumptions that thwart parametric methods in general. This renders NPC a good alternative to classical multivariate tests, such as MANOVA, MANCOVA, and Hotelling’s T2 tests: each of the response variables can be seen as an univariate partial test in the context of the combination, but without the assumptions that are embodied in these old multivariate tests.
As if all the above were not already sufficient, NPC is also more powerful than such classical multivariate tests. This refers to its finite sample consistency property, that is, even with fixed sample size, as the number of modalities being combined increases, the power of the test also increases. The power of classical multivariate tests, however, increases up to a certain point, then begins to decrease, eventually reaching zero when the number of combining variables match the sample size.
The figure below summarises the analysis of a subset of the subjects of a published FMRI study (Brooks et al, 2005) in which painful stimulation was applied to the face, hand, and foot of 12 subjects. Using permutation tests separately, no results could be identified for any of the three types of stimulation. A simple multivariate test, the Hotelling’s T2 test, even assessed using permutations, did not reveal any effect of stimulation either. The NPC results, however, suggest involvement of large portions of the anterior insula and secondary somatosensory cortex. The Fisher, Stouffer and Mudholkar–George combining functions were particularly successful in recovering a small area of activity in the midbrain and periaqueductal gray area, which would be expected from previous studies on pain, but that could not be located from the original, non-combined data.
Detailed assessment of power, using variable number of modalities, and of modalities containing signal, is shown in the paper.
## Combinations or conjunctions?
Combination, as done via NPC, is different than conjunctions (Nichols et al., 2005) in the following: in the combination, one seeks for aggregate significance across partial tests, without the need that any individual study is necessarily significant. In the conjunction, it is necessary that all of them, with no exception, is significant. As indicated above, the NPC forms an union-intersection test (UIT; Roy, 1953), whereas the conjunctions form an intersection-union test (IUT; Berger, 1982). The former can be said to be significant if any (or an aggregate) of the partial tests is significant, whereas the latter is significant if all the partial tests are.
## Availability
The NPC, with the modifications for brain imaging, is available in the tool PALM — Permutation Analysis of Linear Models. It runs in either Matlab or Octave, and is free (GPL).
## References
Contributed to this post: Tom Nichols. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 9, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7409465909004211, "perplexity": 1228.4072529130292}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500154.33/warc/CC-MAIN-20230204205328-20230204235328-00214.warc.gz"} |
https://osqa-ask.wireshark.org/questions/57681/updating-windows-plugin-from-wireshark-16-to-22 | # updating windows plugin from wireshark 1.6 to 2.2
0 Hello dear Wireshark Exprets, after trying to update the plugin by myself and removing as much error as I can, I am stuck with These Errors and don't know what to do with These. I'd really appreciate your help. Thanks in advance `````` "C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj" (Standardziel) (140) -> (Link Ziel) -> packet-myPlugin.obj : error LNK2005: _plugin_reg_handoff already defined in plugin.obj [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2005: _plugin_register already defined in plugin.obj [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] plugin.obj : error LNK2019: unresolved external symbol _proto_register_myPlugin referenced in function _plugin_register [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] plugin.obj : error LNK2019: unresolved external symbol _proto_reg_handoff_myPlugin referenced in function _plugin_reg_handoff [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _match_strval referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _ADDRESSES_EQUAL referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _se_alloc referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _proto_tree_add_text referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _snprintf referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _ep_strdup_printf referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _tvb_get_ephemeral_string referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] packet-myPlugin.obj : error LNK2019: unresolved external symbol _tvb_get_string referenced in function _dissector_ife [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] C:\Temp\_temp_setupFiles\Development\wsbuild32\run\RelWithDebInfo\plugins\myPlugin.dll : fatal error LNK1120: 10 unresolved externals [C:\Temp\_temp_setupFiles\Development\wsbuild32\plugins\myPlugin\myPlugin.vcxproj] `````` asked 28 Nov '16, 06:27 xaheen 71●14●15●19 accept rate: 50% Guy Harris ♦♦ 17.4k●3●35●196 1 So you are looking at the following functions: ```match_strval() ADDRESSES_EQUAL() se_alloc() proto_tree_add_text() snprintf() ep_strdup_printf() tvb_get_ephemeral_string() tvb_get_string() ``` (28 Nov '16, 11:16) Jaap ♦ @jaap thanks for your reply. Which functions should I use instead of these functions? (29 Nov '16, 04:09) xaheen 1 In addition to the above you need to change the plugin_reg_handoff() to proto_reg_handof_foo. eg the same handoff and register functions are used in plugins as in regular dissectors. You should probably look at the(c)make files of plugin in the current code base. ep and se memory has been replaced by wmem you can look up the usage of those funktions in the docs and or the code base. (29 Nov '16, 05:16) Anders ♦ Thanks guys :) (29 Nov '16, 05:22) xaheen
1 ``````match_strval -> try_val_to_str ADDRESSES_EQUAL -> addresses_equal se_alloc(XXX) -> wmem_alloc(wmem_file_scope(), XXX) proto_tree_add_text -> must be replaced by the proper proto_tree_add_XXX function depending on your use case ep_strdup_printf(XXX) -> wmem_strdup(wmem_packet_scope(), XXX) tvb_get_ephemeral_string(XXX) -> tvb_get_string_enc(wmem_packet_scope(), XXX, ENC_UTF_8|ENC_NA) tvb_get_string(XXX) -> tvb_get_string_enc(NULL, XXX, ENC_UTF_8|ENC_NA) `````` As for snprintf(), this is a standard C function and not a Wireshark API. answered 29 Nov '16, 05:12 Pascal Quantin 5.5k●10●60 accept rate: 30% Thanks a bunch for saving my day :D (29 Nov '16, 05:21) xaheen 1 As for snprintf(), this is a standard C function It's a standard C99 function, but not a standard C89 function, and older versions of Microsoft Visual Studio don't provide it. In Wireshark 2.2 and later, you can include `` and use `ws_snprintf()` instead of `snprintf()`; it should work on UN*X and it should also work on Windows with all versions of Visual Studio that we support. (29 Nov '16, 14:52) Guy Harris ♦♦ ep_strdup_printf(XXX) -> wmem_strdup(wmem_packet_scope(), XXX) didnt work for me. wmem_strdup_printf(wmem_packet_scope(), XXX) worked perfectly (01 Mar '17, 01:13) xaheen
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powered by OSQA | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8046467304229736, "perplexity": 27772.465824759995}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875147154.70/warc/CC-MAIN-20200228104413-20200228134413-00502.warc.gz"} |
https://www.aimsciences.org/article/doi/10.3934/dcdsb.2020234 | # American Institute of Mathematical Sciences
June 2021, 26(6): 3335-3355. doi: 10.3934/dcdsb.2020234
## Entropy-dissipating finite-difference schemes for nonlinear fourth-order parabolic equations
Institute of Analysis and Scientific Computing, Technische Universität Wien, Wiedner Hauptstraße 8–10, 1040 Wien, Austria
* Corresponding author: Ansgar Jüngel
Received January 2020 Revised June 2020 Published June 2021 Early access August 2020
Fund Project: The authors acknowledge partial support from the Austrian Science Fund (FWF), grants F65, P30000, P33010, and W1245
Structure-preserving finite-difference schemes for general nonlinear fourth-order parabolic equations on the one-dimensional torus are derived. Examples include the thin-film and the Derrida–Lebowitz–Speer–Spohn equations. The schemes conserve the mass and dissipate the entropy. The scheme associated to the logarithmic entropy also preserves the positivity. The idea of the derivation is to reformulate the equations in such a way that the chain rule is avoided. A central finite-difference discretization is then applied to the reformulation. In this way, the same dissipation rates as in the continuous case are recovered. The strategy can be extended to a multi-dimensional thin-film equation. Numerical examples in one and two space dimensions illustrate the dissipation properties.
Citation: Marcel Braukhoff, Ansgar Jüngel. Entropy-dissipating finite-difference schemes for nonlinear fourth-order parabolic equations. Discrete & Continuous Dynamical Systems - B, 2021, 26 (6) : 3335-3355. doi: 10.3934/dcdsb.2020234
##### References:
show all references
##### References:
Evolution of the DLSS equation in a semi-logarithmic scale, using the initial datum $u^0(x) = \max\{10^{-10}, \cos(\pi x)^{16}\}$
Left: Decay of the logarithmic entropy $s_0(u(t))$ for two different space grid sizes $h = 1/20$ and $h = 1/200$. Right: Convergence of the $\ell^2$ error. The dots are the values from the numerical solution, the solid line is the regression curve
Left: Decay of the Shannon entropy $s_1(u(t))$ with $h = 1/100$. Right: Convergence of the $\ell^2$ error. The dots are the values from the numerical solution, the solid line is the regression curve
Evolution of the solution to the thin-film equation at times $t = 0$ (densely dotted), $t = 2\cdot 10^{-4}$ (dotted), $t = 5\cdot 10^{-4}$ (dash-dotted), $t = 1\cdot 10^{-3}$ (dashed), $t = 2\cdot 10^{-3}$ (densely dashed), and $t = 5\cdot 10^{-3}$ (solid) and grid sizes $h = 1/10$ (left), $h = 1/200$ (right)
Decay of the logarithmic entropy $S_0(u(t))$ for various space grid sizes
Evolution of the solution to the two-dimensional thin-film equation with $\beta = 2$, $t = 0$ (top left), $t = 3\cdot 10^{-9}$ (top right), $t = 10^{-8}$ (bottom left), $t = 10^{-6}$ (bottom right)
Decay of the logarithmic entropy $S_0(u(t))$ for various space grid sizes
[1] Marina Chugunova, Roman M. Taranets. New dissipated energy for the unstable thin film equation. Communications on Pure & Applied Analysis, 2011, 10 (2) : 613-624. doi: 10.3934/cpaa.2011.10.613 [2] Eric A. Carlen, Süleyman Ulusoy. Localization, smoothness, and convergence to equilibrium for a thin film equation. Discrete & Continuous Dynamical Systems, 2014, 34 (11) : 4537-4553. doi: 10.3934/dcds.2014.34.4537 [3] Richard S. Laugesen. New dissipated energies for the thin fluid film equation. Communications on Pure & Applied Analysis, 2005, 4 (3) : 613-634. doi: 10.3934/cpaa.2005.4.613 [4] Changchun Liu, Jingxue Yin, Juan Zhou. Existence of weak solutions for a generalized thin film equation. Communications on Pure & Applied Analysis, 2007, 6 (2) : 465-480. doi: 10.3934/cpaa.2007.6.465 [5] Jian-Guo Liu, Jinhuan Wang. Global existence for a thin film equation with subcritical mass. Discrete & Continuous Dynamical Systems - B, 2017, 22 (4) : 1461-1492. doi: 10.3934/dcdsb.2017070 [6] Lihua Min, Xiaoping Yang. Finite speed of propagation and algebraic time decay of solutions to a generalized thin film equation. Communications on Pure & Applied Analysis, 2014, 13 (2) : 543-566. doi: 10.3934/cpaa.2014.13.543 [7] Huiqiang Jiang. Energy minimizers of a thin film equation with born repulsion force. Communications on Pure & Applied Analysis, 2011, 10 (2) : 803-815. doi: 10.3934/cpaa.2011.10.803 [8] Daniel Ginsberg, Gideon Simpson. Analytical and numerical results on the positivity of steady state solutions of a thin film equation. Discrete & Continuous Dynamical Systems - B, 2013, 18 (5) : 1305-1321. doi: 10.3934/dcdsb.2013.18.1305 [9] Andrey Shishkov. Waiting time of propagation and the backward motion of interfaces in thin-film flow theory. Conference Publications, 2007, 2007 (Special) : 938-945. doi: 10.3934/proc.2007.2007.938 [10] Sergey Degtyarev. Classical solvability of the multidimensional free boundary problem for the thin film equation with quadratic mobility in the case of partial wetting. Discrete & Continuous Dynamical Systems, 2017, 37 (7) : 3625-3699. doi: 10.3934/dcds.2017156 [11] P. Álvarez-Caudevilla, J. D. Evans, V. A. Galaktionov. The Cauchy problem for a tenth-order thin film equation II. Oscillatory source-type and fundamental similarity solutions. Discrete & Continuous Dynamical Systems, 2015, 35 (3) : 807-827. doi: 10.3934/dcds.2015.35.807 [12] Panayotis Panayotaros. Continuation and bifurcations of breathers in a finite discrete NLS equation. Discrete & Continuous Dynamical Systems - S, 2011, 4 (5) : 1227-1245. doi: 10.3934/dcdss.2011.4.1227 [13] Cheng Wang, Xiaoming Wang, Steven M. Wise. Unconditionally stable schemes for equations of thin film epitaxy. Discrete & Continuous Dynamical Systems, 2010, 28 (1) : 405-423. doi: 10.3934/dcds.2010.28.405 [14] Alexander Zlotnik, Ilya Zlotnik. Finite element method with discrete transparent boundary conditions for the time-dependent 1D Schrödinger equation. Kinetic & Related Models, 2012, 5 (3) : 639-667. doi: 10.3934/krm.2012.5.639 [15] Hyung Ju Hwang, Thomas P. Witelski. Short-time pattern formation in thin film equations. Discrete & Continuous Dynamical Systems, 2009, 23 (3) : 867-885. doi: 10.3934/dcds.2009.23.867 [16] Lei Yang, Xiao-Ping Wang. Dynamics of domain wall in thin film driven by spin current. Discrete & Continuous Dynamical Systems - B, 2010, 14 (3) : 1251-1263. doi: 10.3934/dcdsb.2010.14.1251 [17] Raffaele Esposito, Mario Pulvirenti. Rigorous validity of the Boltzmann equation for a thin layer of a rarefied gas. Kinetic & Related Models, 2010, 3 (2) : 281-297. doi: 10.3934/krm.2010.3.281 [18] Igor Kukavica, Mohammed Ziane. Regularity of the Navier-Stokes equation in a thin periodic domain with large data. Discrete & Continuous Dynamical Systems, 2006, 16 (1) : 67-86. doi: 10.3934/dcds.2006.16.67 [19] M. Ben Ayed, K. El Mehdi, M. Hammami. Nonexistence of bounded energy solutions for a fourth order equation on thin annuli. Communications on Pure & Applied Analysis, 2004, 3 (4) : 557-580. doi: 10.3934/cpaa.2004.3.557 [20] Eitan Tadmor. Perfect derivatives, conservative differences and entropy stable computation of hyperbolic conservation laws. Discrete & Continuous Dynamical Systems, 2016, 36 (8) : 4579-4598. doi: 10.3934/dcds.2016.36.4579
2020 Impact Factor: 1.327 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6079699993133545, "perplexity": 2700.6674993859847}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323585653.49/warc/CC-MAIN-20211023064718-20211023094718-00318.warc.gz"} |
http://math.stackexchange.com/questions/74084/how-to-construct-an-infinite-family-of-cantor-like-sets-with-certain-properties | # How to construct an infinite family of cantor-like sets with certain properties
Q. Construct infinitely many disjoint sets $A_1, A_2,... \subset R$, each of which is a union of suitable symmetric Cantor sets, such that for every interval I and every $k=1,2,...$ the intersection $A_k \cap I$ has positive length.
I'm really struggling with this.The cantor sets are meagre on the interval they are defined so you can easily define some interval that will have empty intersection with any cantor set. Then assuming that we fill the gaps of a cantor set by taking unions with other cantor sets I can't see how to make an infinite family of sets that are a union of cantor like sets but still remain pairwise disjoint.
-
– t.b. Oct 19 '11 at 19:26
@t.b.: It’s not quite a duplicate, since a small extra trick is required to get infinitely many sets instead of one. – Brian M. Scott Oct 19 '11 at 20:16
I dont quite see how you could the given solution to answer this question :( especially even if we find cantor sets satifying the above conditions how do we ensure that each A_i intersects with every interval in R? – user17957 Oct 20 '11 at 18:57
I've got as far as defining $A_1$ with the desired properties but I'm struggling now with how to extend this to an infinite family. I'm thinking of a translation of some sort. – user17904 Oct 20 '11 at 19:20
I was thinking of defining the A_i 's as 'union of cantor sets' over unit intervals (i.e pick a unit interval , define a cantor set on it hich has positive measure , and then fill in the 'gaps' on the interval which are not occupied by cantor sets with more and more cantor sets of positive measure and sort of cover de whole unit interval with cantor sets) so doing this way we can have an infite sequence disjoint sets A_i, with each i corresponding to a unit interval. The problem I'm having with this approach is that there is nothing to ensure that each interval in R will have a non-empty inter – user17957 Oct 20 '11 at 20:10
Enumerate all open intervals with rational coordinates as $(I_j)_{j\ge 1}$. Enumerate all pairs $(k,j)_{k,j\ge 1}$ as $(k(n),j(n))_{n\ge 1}$. For each $n$ choose a symmetric Cantor set of positive measure $C_n$ such that $$C_n\subset I_{j(n)} \setminus \bigcup_{m=1}^{n-1}C_m \tag1$$ This is possible because the set on the right in (1) is open and nonempty (even comeager). The sets $$A_k=\bigcup_{k(n)=k} C_n,\quad k\ge 1$$ meet the requirements.
The above is a slight adaptation of Construction of a Borel set with positive but not full measure in each interval.
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https://worldwidescience.org/topicpages/p/polar+capsule+width.html | #### Sample records for polar capsule width
1. Sieve efficiency in benthic sampling as related to chironomid head capsule width
Science.gov (United States)
Hudson, Patrick L.; Adams, Jean V.
1998-01-01
The width of the head capsule in chironomid larvae is the most important morphometric character controlling retention of specimens in sieving devices. Knowledge of the range in size of these widths within any chironomid community is fundamental to sampling and interpreting the resulting data. We present the head capsule widths of 30 species of chironomids and relate their size distribution to loss or retention in several experiments using graded sieve sizes. Based on our measurements and those found in the literature we found the head capsule width of fourth instars in half the chironomids species to be less than 350 I?m. Many species may never be collected with the commonly used U.S. Standard No. 30 sieve (589 I?m), and the No. 60 (246 I?m) screen appears to retain most species only qualitatively. We found 70 to 90% of the chironomid larvae and 19 to 34% of their biomass can pass through a No. 80 sieve (177 I?m). The implications of sieve loss and other factors affecting sieving efficiency are discussed.
2. Application of a frequency distribution method for determining instars of the beet armyworm (Lepidoptera: Noctuidae) from widths of cast head capsules
Science.gov (United States)
Y. Chen; S. J. Seybold
2013-01-01
Instar determination of field-collected insect larvae has generally been based on the analysis of head capsule width frequency distributions or bivariate plotting, but few studies have tested the validity of such methods. We used head capsules from exuviae of known instars of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae),...
3. Moving systems of polar dimeric capsules out of thermal equilibrium by light irradiation.
Science.gov (United States)
Díaz-Moscoso, Alejandro; Arroyave, Frank A; Ballester, Pablo
2016-02-18
Heterodimeric capsules self-assembled from tetraurea calix[4]pyrrole and tetraurea calix[4]arene provide unique molecular containers for the organised inclusion of small polar molecules. By inserting stimuli-responsive groups (azobenzene) in the heterocapsule structure, we are able to modify the equilibrium state of the system or the exchange between different host-guest assemblies in a reversible manner.
4. Polarization response of clathrate hydrates capsulated with guest molecules
Energy Technology Data Exchange (ETDEWEB)
Zeng, Qun; Li, Jinshan, E-mail: ljs915@263.net, E-mail: myang@scu.edu.cn; Huang, Hui [Institute of Chemical Materials, China Academy of Engineering Physics (CAEP), Mianyang 621900 (China); Wang, Xinqin; Yang, Mingli, E-mail: ljs915@263.net, E-mail: myang@scu.edu.cn [Institute of Atomic and Molecular Physics, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065 (China)
2016-05-28
Clathrate hydrates are characterized by their water cages encapsulating various guest atoms or molecules. The polarization effect of these guest-cage complexes was studied with combined density functional theory and finite-field calculations. An addition rule was noted for these systems whose total polarizability is approximately equal to the polarizability sum of the guest and the cage. However, their distributional polarizability computed with Hirshfeld partitioning scheme indicates that the guest–cage interaction has considerable influence on their polarization response. The polarization of encapsulated guest is reduced while the polarization of water cage is enhanced. The counteraction of these two opposite effects leads to the almost unchanged total polarizability. Further analysis reveals that the reduced polarizability of encapsulated guest results from the shielding effect of water cage against the external field and the enhanced polarizability of water cage from the enhanced bonding of hydrogen bonds among water molecules. Although the charge transfer through the hydrogen bonds is rather small in the water cage, the polarization response of clathrate hydrates is sensitive to the changes of hydrogen bonding strength. The guest encapsulation strengthens the hydrogen bonding network and leads to enhanced polarizability.
5. Template-directed self-assembly of dynamic covalent capsules with polar interiors.
Science.gov (United States)
Galán, Albano; Escudero-Adán, Eduardo C; Ballester, Pablo
2017-11-01
Chiral polyimine molecular capsules with polar interiors have been prepared through template covalent dynamic self-assembly. An aryl-extended tetraaldehyde calix[4]pyrrole scaffold was condensed with suitable diamines as linkers using templates for efficient self-assembly. The capsular complexes were characterized in solution, gas phase and the solid-state. Unprecedented transfer of asymmetry was observed from a chiral diamine linker to the resulting supramolecular capsular assembly.
6. Guests of Differing Polarities Provide Insight into Structural Requirements for Templates of Water-Soluble Nano-Capsules
Science.gov (United States)
Gibb, Corinne L. D.; Gibb, Bruce C.
2009-01-01
Guests covering a range of polarities were examined for their ability to bind to a water-soluble cavitand and trigger its assembly into a supramolecular capsule. Specifically the guests examined were: tridecane 2, 1-dodecanol 3, 2-nonyloxy ethanol (ethylene glycol monononyl ether) 4, 2-(2-hexyloxyethoxy) ethanol (Di(ethylene glycol) hexyl ether) 5, 2-[2-(2 propoxyethoxy)ethoxy] ethanol (Tri(ethylene glycol) propyl ether 6, and bis [2-(2-hydroxyethoxy)ethyl] ether (tetra(ethylene glycol)) 7. In this series, guest 6 proved to signify the boundary between assembly and the formation of 2:1 complexes, and simple 1:1 complexation. Thus, guests 2–5 formed relatively kinetically stable capsules, guest 6 formed a capsule that was unstable relative to the NMR timescale, and guest 7 formed a simple 1:1 complex. PMID:20606762
7. Generation of a chirp-free optical pulse train with tunable pulse width based on a polarization modulator and an intensity modulator.
Science.gov (United States)
Pan, Shilong; Yao, Jianping
2009-07-15
A simple method for the generation of a chirp-free optical pulse train with tunable pulse width using a polarization modulator (PolM) and a zero-chirp intensity modulator (IM) is proposed and demonstrated. In the proposed system, a light wave with its polarization direction oriented at an angle of 45 degrees with respect to the principal axis of the PolM is polarization modulated by a sinusoidal drive signal. An optical polarizer is connected after the PolM to convert the polarization-modulated signals to a pulse train with the main peaks having a narrow pulse width. Then, the main peaks are selected by the IM, leading to the generation of a short optical pulse train with a repetition rate that is identical to or twice the frequency of the sinusoidal drive signal, depending on the dc bias of the IM. The pulse width of the generated pulse is easily tuned by adjusting the phase modulation index of the PolM. An experiment is carried out, and a pulse train with a duty cycle as small as 8.16% is generated.
8. Unusual Ionospheric Echoes with Velocity and Very Low Special Width Observed by the SuperDARN Radars in the Polar Cap During High Geomagnetic Activity
National Research Council Canada - National Science Library
Nishitani, Nozomu
2004-01-01
...) They have a close correlation with geomagnetic activity such that as the Dst index decreases, the radars tend to observe ionospheric echoes with high Doppler velocity and very low spectral width more frequently. (2...
9. opened capsule
African Journals Online (AJOL)
The accuracy of the off-label opened capsule dosing method for stavudine is acceptable. There is no need to instruct caregivers to include sediment in the aliquot given to the infant. However, studies that confirm adequate bioavailability and efficacy are needed. In addition, it is important to avoid supplying generic capsules ...
10. Capsule endoscopy
DEFF Research Database (Denmark)
Skovsen, Anders Peter; Burcharth, Jakob; Burgdorf, Stefan Kobbelgaard
2013-01-01
with ultrasound, MRI, and subsequently a capsule endoscopy. Six months later, the patient presented, and an abdominal CT-scan showed mechanical small bowel obstruction with suspicion of metallic foreign body and perforation. Laparotomy showed perforation, stenosis, and foreign body, approximately 5 cm from...
11. Adhesive capsulitis of the shoulder: MR arthrography
Energy Technology Data Exchange (ETDEWEB)
Kim, Hyun Jeong; Han, Tae Il; Lee, Kwang Won; Choi, Youn Seon; Kim, Dae Hong; Han, Hyun Young; Song, Mun Kab [Eulji Univ. School of Medicine, Taejon (Korea, Republic of); Kwon, Soon Tae [Chungnam National Univ. College of Medicine, Taejon (Korea, Republic of)
2001-07-01
Adhesive capsulitis is a clinical syndrome involving pain and decreased joint motion caused by thickening and contraction of the joint capsule. The purpose of this study is to describe the MR arthrographic findings of this syndrome. Twenty-nine sets of MR arthrographic images were included in the study. Fourteen patients had adhesive capsulitis diagnosed by physical examination and arthrography, and their MR arthrographic findings were compared with those of 15 subjects in the control group. The images were retrospectively reviewed with specific attention to the thickness of the joint capsule, volume of the axillary pouch (length, width, height(depth)), thinkness of the coracohumeral ligament, presence of extra-articular contrast extravasation, and contrst filling of the subcoracoid bursa. Mean capsular thickness measured at the inferior portion of the axillary pouch was 4.1 mm in patients with adhesive capsulitis and 1.5 mm in the control group. The mean width of the axillary pouch was 2.5 mm in patients and 9.5 mm in controls. In patients, the capsule was significantly thicker and the axillary pouch significantly narrower than in controls (p<0.05). Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch (sensitivity 93%, specificity 80%) and a pouch narrower than 3.5 mm (sensitivity 93%, specificity 100%) were useful criteria for the diagnosis of adhesive capsulitis. In patients with this condition, extra-articular contrast extravasation was noted in six patients (43%) and contrast filling of the subcoracoid bursa in three (21%). The MR arthrographic findings of adhesive capsulitis are capsular thickening, a low-volume axillary pouch, extra-articular contrast extravasation, and contrast filling of the subcoracoid bursa. Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch and a pouch width of less than 3.5 mm are useful diagnostic imaging characteristics.
12. Application of DoE approach in the development of mini-capsules, based on biopolymers and manuka honey polar fraction, as powder formulation for the treatment of skin ulcers.
Science.gov (United States)
Tenci, Marika; Rossi, Silvia; Bonferoni, Maria Cristina; Sandri, Giuseppina; Mentori, Irene; Boselli, Cinzia; Cornaglia, Antonia Icaro; Daglia, Maria; Marchese, Anna; Caramella, Carla; Ferrari, Franca
2017-01-10
The aim of the present work was the development of a powder formulation for the delivery of manuka honey (MH) bioactive components in the treatment of chronic skin ulcers. In particular pectin (PEC)/chitosan glutamate (CS)/hyaluronic acid (HA) mini-capsules were obtained by inverse ionotropic gelation in presence of calcium chloride and subsequently freeze-dried. Optimization of unloaded (blank) formulation was performed using DoE approach. In a screening phase, the following three factors were investigated at two levels: CS (0.5-1% w/w), PEC (0.5-1% w/w) and HA (0.3-0.5% w/w) concentrations. For the optimization phase a "central composite design" was used. The response variables considered were: particle size, buffer (PBS) absorption and mechanical resistance. In a previously work two different MH fractions were investigated, in particular MH fraction 1 (Fr1), rich in polar substances (sugars, methylglyoxal (MGO), dicarbonyl compounds, …), was able to enhance human fibroblasts in vitro proliferation. In the present work, the loading of MH Fr1 into mini-capsules of optimized composition determined a significant increase in cell proliferation in comparison with the unloaded ones. Loaded particles showed antimicrobial activity against Staphylococcus aureus and Streptococcus pyogenes; they were also able to improve wound healing in vivo on a rat wound model. Copyright © 2016 Elsevier B.V. All rights reserved.
13. The environmental psychology of capsule habitats.
Science.gov (United States)
Suedfeld, P; Steel, G D
2000-01-01
Capsule habitats make it possible for human beings to survive and function in environments that would otherwise be lethal, such as space, the ocean depths, and the polar regions. The number of people entering capsules in the course of their work or for purposes of recreation is constantly increasing. However, long-term living in such habitats imposes physical and psychological risks as well as offering opportunities and benefits. This paper reviews what is known about the environmental, social, and personality aspects of adaptation to capsules, including sources of stress, selection criteria, obstacles to and facilitators of adequate coping, changes in group interaction, the role of temporal factors, and post-mission consequences.
14. Adhesive Capsulitis of the Shoulder Joint: Value of Glenohumeral Distance on Magnetic Resonance Arthrography.
Science.gov (United States)
Lee, Kyu Hong; Park, Hee Jin; Lee, So Yeon; Youn, In Young; Kim, Eugene; Park, Jai Hyung; Park, Se Jin
2017-01-01
To evaluate the usefulness of glenohumeral distance (GHD) on axial images of magnetic resonance (MR) arthrography for diagnosis of adhesive capsulitis and to compare this finding with previously reported classic MR arthrographic findings of adhesive capsulitis. Our study was approved by the institutional ethical review board of our institute. We evaluated 41 patients (M-F, 35:6; mean age, 46 years; adhesive capsulitis, 21; no adhesive capsulitis, 20) who underwent MR arthrography. Two radiologists measured GHD, width of the axillary recess, and capsular thickness in consensus. The GHD was measured from the subchondral bone of the glenoid fossa to the subchondral bone of the humeral head at the level of the midline of the humeral head. Glenohumeral distance (anterior, middle, posterior, and mean), width of the axillary recess, and capsular thickness (anterior, posterior, and mean) were compared in the adhesive capsulitis and no adhesive capsulitis groups using the Mann-Whitney U test. The mean GHD of the no adhesive capsulitis group was longer than that of the adhesive capsulitis group. The length differences were statistically significant (P adhesive capsulitis group was significantly wider than that of the adhesive capsulitis group (P adhesive capsulitis group was significantly thinner than that in the adhesive capsulitis group (P = 0.001). A decreased GHD on MR arthrography can be another useful feature to diagnose adhesive capsulitis in addition to previously presented radiologic features such as capsular thickening and reduced axillary recess capacity.
15. Wireless communication link for capsule endoscope at 600 MHz.
Science.gov (United States)
Khaleghi, A; Balasingham, I
2015-01-01
Simulation of a wireless communication link for a capsule endoscopy is presented for monitoring of small intestine in humans. The realized communication link includes the transmitting capsule antenna, the outside body receiving antenna and the model of the human body. The capsule antenna is designed for operating at the frequency band of 600 MHz with an impedance bandwidth of 10 MHz and omnidirectional radiation pattern. The quality of the communication link is improved by using directive antenna outside body inside matching layer for electromagnetic wave tuning to the body. The outside body antenna has circular polarization that guaranteeing the communication link for different orientations of the capsule inside intestine. It is shown that the path loss for the capsule in 60 mm from the abdomen surface varies between 37-47 dB in relation to the antenna orientation. This link can establish high data rate wireless communications for capsule endoscopy.
16. Polydopamine-coated capsules
Energy Technology Data Exchange (ETDEWEB)
White, Scott R.; Sottos, Nancy R.; Kang, Sen; Baginska, Marta B.
2018-04-17
One aspect of the invention is a polymer material comprising a capsule coated with PDA. In certain embodiments, the capsule encapsulates a functional agent. The encapsulated functional agent may be an indicating agent, healing agent, protecting agent, pharmaceutical drug, food additive, or a combination thereof.
17. The first capsule implosion experiments on Orion
International Nuclear Information System (INIS)
Garbett, W J; Horsfield, C J; Gales, S G; Leatherland, A E; Rubery, M S; Coltman, J E; Meadowcroft, A E; Rice, S J; Simons, A J; Woolhead, V E
2016-01-01
Direct drive capsule implosions are being developed on the Orion laser at AWE as a platform for ICF and HED physics experiments. The Orion facility combines both long pulse and short-pulse beams, making it well suited for studying the physics of alternative ignition approaches. Orion implosions also provide the opportunity to study aspects of polar direct drive. Limitations on drive symmetry from the relatively small number of laser beams makes predictive modelling of the implosions challenging, resulting in some uncertainty in the expected capsule performance. Initial experiments have been fielded to evaluate baseline capsule performance and inform future design optimization. Highly promising DD fusion neutron yields in excess of 10 9 have been recorded. Results from the experiments are presented alongside radiation-hydrocode modelling. (paper)
18. Adhesive capsulitis of the shoulder: evaluation with MR arthrography
Energy Technology Data Exchange (ETDEWEB)
Jung, Joon-Yong; Jee, Won-Hee; Chun, Ho Jong [Catholic University of Korea, Department of Radiology, Kangnam St. Mary' s Hospital, Seoul (Korea); Kim, Yang-Soo; Chung, Yang Guk; Kim, Jung-Man [Catholic University of Korea, Department of Orthopedic Surgery, Kangnam St. Mary' s Hospital, Seoul (Korea)
2006-04-15
The purpose of this study was to determine the usefulness of magnetic resonance (MR) arthrography for diagnosing adhesive capsulitis. Shoulder MR images of 28 patients with (n=14) and without (n=14) adhesive capsulitis were retrospectively analyzed. MR images were assessed for capsule and synovium thickness as well as the width of the axillary recess on oblique coronal fat-suppressed T1-weighted images and T2-weighted images, respectively. On oblique sagittal fat-suppressed T1-weighted images, the width of the rotator interval and the presence of abnormal tissue in the interval were evaluated. Significant differences were found between the two groups in capsule and synovium thickness on both sides of the recess on oblique coronal T2-weighted images (P=0.000), whereas thickness on the humeral aspect showed no significant difference on oblique coronal fat-suppressed T1-weighted images (P=0.109). On oblique coronal T2-weighted images, a cut-off value of 3-mm thickness gave the highest diagnostic accuracy for adhesive capsulitis with sensitivity, specificity, and accuracy of 79% (11/14), 100% (14/14), and 89% (25/28) at the humeral side and 93% (13/14), 86% (12/14), and 89% (25/28) at the glenoid side, respectively. There were significant differences in rotator interval width, presence of abnormal tissue in the rotator interval, and axillary recess width between the two groups (P<0.05). Thickness of capsule and synovium of the axillary recess greater than 3 mm is a practical MR criterion for diagnosing adhesive capsulitis when measured on oblique coronal T2-weighted MR arthrography images without fat suppression. The presence of abnormal tissue in the rotator interval showed high sensitivity but rather low specificity. (orig.)
19. Pulse-width discriminators
International Nuclear Information System (INIS)
Budyashov, Yu.G.; Grebenyuk, V.M.; Zinov, V.G.
1978-01-01
A pulse duration discriminator is described which is intended for processing signals from multilayer scintillators. The basic elements of the scintillator are: an input gate, a current generator, an integrating capacitor, a Schmidt trigger and an anticoincidence circuit. The basic circuit of the discriminator and its time diagrams explaining its operating are given. The discriminator is based on microcircuits. Pulse duration discrimination threshold changes continuously from 20 to 100 ns, while its amplitude threshold changes within 20 to 100 mV. The temperature instability of discrimination thresholds (both in pulse width and in amplitude) is better than 0.1 per cent/deg C
20. Wireless capsule endoscopy
Science.gov (United States)
Iddan, Gavriel; Meron, Gavriel; Glukhovsky, Arkady; Swain, Paul
2000-05-01
We have developed a new type of endoscopy, which for the first time allows painless endoscopic imaging of the whole of the small bowel. This procedure involves a wireless capsule endoscope and we describe here its successful testing in humans.
1. Advances in Capsule Endoscopy
Science.gov (United States)
Scott, Ryan
2015-01-01
Wireless video capsule endoscopy (VCE) is a minimally invasive technology that has revolutionized the approach to small intestinal disease investigation and management. Designed primarily to provide diagnostic imaging of the small intestine, VCE is used predominantly for obscure gastrointestinal bleeding and suspected Crohn’s disease; however, numerous other indications have been established, including the assessment of celiac disease, investigation of small bowel tumors, and surveillance of hereditary polyposis syndromes. Since the introduction of small bowel VCE in 2000, more than 1600 articles have been published describing the evolution of this technology. The main adverse outcome is capsule retention, which can potentially be avoided by careful patient selection or by using a patency capsule. Despite the numerous advances in the past 15 years, limitations such as incomplete VCE studies, missed lesions, and time-consuming reporting remain. The inability to control capsule movement for the application of targeted therapy or the acquisition of tissue for histologic analysis remains among the greatest challenges in the further development of capsule technology. This article outlines the recent technological and clinical advances in VCE and the future directions of research in this field. PMID:27482183
2. NIF capsule performance modeling
Directory of Open Access Journals (Sweden)
Weber S.
2013-11-01
Full Text Available Post-shot modeling of NIF capsule implosions was performed in order to validate our physical and numerical models. Cryogenic layered target implosions and experiments with surrogate targets produce an abundance of capsule performance data including implosion velocity, remaining ablator mass, times of peak x-ray and neutron emission, core image size, core symmetry, neutron yield, and x-ray spectra. We have attempted to match the integrated data set with capsule-only simulations by adjusting the drive and other physics parameters within expected uncertainties. The simulations include interface roughness, time-dependent symmetry, and a model of mix. We were able to match many of the measured performance parameters for a selection of shots.
3. Hollow Microporous Organic Capsules
Science.gov (United States)
Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien
2013-01-01
Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511
4. Gelatin capsule in stomach (image)
Science.gov (United States)
... detect the presence of intestinal parasites. A weighted gelatin capsule attached to a string is swallowed and left in place. After about 4 hours, the gelatin capsule is pulled out of the stomach by ...
5. Phase width reduction project summary
International Nuclear Information System (INIS)
Clark, D.J.; Xie, Z.Q.; McMahan, M. A.
1999-01-01
The purpose of the phase width reduction project, 1993--96, was to reduce the phase width of the 88-Inch Cyclotron beam on target from 5--10 ns to 1--2 ns for certain experiments, such as Gammasphere, which use time-of-flight identification. Since reducing the phase width also reduces beam intensity, tuning should be done to also optimize the transmission. The Multi-turn Collimator slits in the cyclotron center region were used to collimate the early turns radially, thus reducing the phase width from about 5 ns to 1--2 ns FWHM for a Gammasphere beam. The effect of the slits on phase width was verified with a Fast Faraday Cup and with particle and gamma-ray detectors in the external beamline
6. Management of adhesive capsulitis
Directory of Open Access Journals (Sweden)
Stupay KL
2015-08-01
Full Text Available Kristen L Stupay,1 Andrew S Neviaser2 1Tulane University School of Medicine, New Orleans, LA, USA; 2George Washington University Medical Faculty Associates, Washington, DC, USA Abstract: Adhesive capsulitis of the shoulder is a condition of capsular contracture that reduces both active and passive glenohumeral motion. The cause of adhesive capsulitis is not known but it is strongly associated with endocrine abnormalities such as diabetes. Diverse terminology and the absence of definitive criteria for diagnosis make evaluating treatment modalities difficult. Many treatment methods have been reported, most with some success, but few have been proved to alter the natural course of this disease. Most afflicted patients will achieve acceptable shoulder function without surgery. Those who remain debilitated after 8–12 months are reasonable candidates for invasive treatments. Here, the various treatment methods and the data to support their use are reviewed. Keywords: frozen shoulder, stiff shoulder, periarthritis, painful shoulder
7. A deterministic width function model
Directory of Open Access Journals (Sweden)
C. E. Puente
2003-01-01
Full Text Available Use of a deterministic fractal-multifractal (FM geometric method to model width functions of natural river networks, as derived distributions of simple multifractal measures via fractal interpolating functions, is reported. It is first demonstrated that the FM procedure may be used to simulate natural width functions, preserving their most relevant features like their overall shape and texture and their observed power-law scaling on their power spectra. It is then shown, via two natural river networks (Racoon and Brushy creeks in the United States, that the FM approach may also be used to closely approximate existing width functions.
8. Probabilistic Analysis of Crack Width
Directory of Open Access Journals (Sweden)
J. Marková
2000-01-01
Full Text Available Probabilistic analysis of crack width of a reinforced concrete element is based on the formulas accepted in Eurocode 2 and European Model Code 90. Obtained values of reliability index b seem to be satisfactory for the reinforced concrete slab that fulfils requirements for the crack width specified in Eurocode 2. However, the reliability of the slab seems to be insufficient when the European Model Code 90 is considered; reliability index is less than recommended value 1.5 for serviceability limit states indicated in Eurocode 1. Analysis of sensitivity factors of basic variables enables to find out variables significantly affecting the total crack width.
9. Probabilistic Analysis of Crack Width
OpenAIRE
J. Marková; M. Holický
2000-01-01
Probabilistic analysis of crack width of a reinforced concrete element is based on the formulas accepted in Eurocode 2 and European Model Code 90. Obtained values of reliability index b seem to be satisfactory for the reinforced concrete slab that fulfils requirements for the crack width specified in Eurocode 2. However, the reliability of the slab seems to be insufficient when the European Model Code 90 is considered; reliability index is less than recommended value 1.5 for serviceabi...
10. Adhesive capsulitis of the shoulder.
Science.gov (United States)
Neviaser, Andrew S; Neviaser, Robert J
2011-09-01
Adhesive capsulitis is characterized by painful, gradual loss of active and passive shoulder motion resulting from fibrosis and contracture of the joint capsule. Other shoulder pathology can produce a similar clinical picture, however, and must be considered. Management is based on the underlying cause of pain and stiffness, and determination of the etiology is essential. Subtle clues in the history and physical examination can help differentiate adhesive capsulitis from other conditions that cause a stiff, painful shoulder. The natural history of adhesive capsulitis is a matter of controversy. Management of true capsular restriction of motion (ie, true adhesive capsulitis) begins with gentle, progressive stretching exercises. Most patients improve with nonsurgical treatment. Indications for surgery should be individualized. Failure to obtain symptomatic improvement and continued functional disability following ≥6 months of physical therapy is a general guideline for surgical intervention. Diligent postoperative therapy to maintain motion is required to minimize recurrence of adhesive capsulitis.
11. Correlation between interalar width and intercommisural width against mesiodistal width of central upper incisor in Buginese tribe
Directory of Open Access Journals (Sweden)
Bahruddin Thalib
2016-04-01
Full Text Available Various types of anatomical landmarks of the face should match its proportions with the size of the teeth which is the interalar width, intercomissural width, interpupillary width, Intercanthal width, and byzigomatic width. Some of face landmarks can be used as a guide in the selection of anterior teeth in complete denture, especially if the pre extraction record such as radiography image, extracted teeth, model study, the remaining teeth, face shape, and the shape of the curved jaw have been lost. The objective of this study was to evaluate the correlation between interalar width and intercommisural width against mesiodistal incisivus centralis width in a group of Buginese tribe. Ninety nine Buginese tribe subjects aged 17-25 were selected. The interalar width, intercommisural width, and mesiodistal incisor centralis teeth were measured using caliper about three times for accuracy and precision. Mean of interalar width and mesiodistal incisor centralis maxilla width in males more width than females (p0.05. The degree of correlation between interalar width against mesiodistal incisor centralis maxilla width was 0.030, -0.246, 0,225 in Buginese tribe, males, and females (p>0.05. : The degree of correlation between intercommisural width against mesiodistal incisor centralis maxilla width in Buginese tribe was 0,054, 0,013, 0,153 in Buginese tribe, males, and females (p>0.05. The degree of correlation between interalar width and intercommisural width was 0.301 and 0.356 in Buginese tribe and males (p0.05. In conclusion, there is no significant correlation between interalar width and intercommisural width against mesiodistal incisor centralis maxilla width in a group of Buginese tribe. Interalar width and intercommisural width directly proportional to mesiodistal incisor centralis maxilla in a group of Buginese tribe. Interalar width and intercommisural width inversely proportional to mesiodistal incisor centralis maxilla in males and directly
12. Preshot Predictions for Defect Induced Mix (DIME) Capsules
International Nuclear Information System (INIS)
Bradley, Paul A.; Krasheninnikova, Natalia S.; Tregillis, Ian L.; Schmitt, Mark J.
2012-01-01
In this memo, we evaluate the most probable yield and other results for the Defect Induced Mix (DIME-12A) Polar Direct Drive (PDD) capsule-only shots. We evaluate the expected yield, bang time, burn averaged ion temperature, and the average electron temperature of the Ge line-emitting region. We also include synthetic images of the capsule backlit by Cu K-α emission (8.39 keV) and core self-emission synthetic images. This memo is a companion to the maximum credible yield memo (LA-UR--12-00287) published earlier.
13. Preshot Predictions for Defect Induced Mix (DIME) Capsules
Energy Technology Data Exchange (ETDEWEB)
Bradley, Paul A. [Los Alamos National Laboratory; Krasheninnikova, Natalia S. [Los Alamos National Laboratory; Tregillis, Ian L. [Los Alamos National Laboratory; Schmitt, Mark J. [Los Alamos National Laboratory
2012-07-31
In this memo, we evaluate the most probable yield and other results for the Defect Induced Mix (DIME-12A) Polar Direct Drive (PDD) capsule-only shots. We evaluate the expected yield, bang time, burn averaged ion temperature, and the average electron temperature of the Ge line-emitting region. We also include synthetic images of the capsule backlit by Cu K-{alpha} emission (8.39 keV) and core self-emission synthetic images. This memo is a companion to the maximum credible yield memo (LA-UR-12-00287) published earlier.
14. Wireless capsule endo bronchoscopy
Directory of Open Access Journals (Sweden)
Baratz DM
2014-03-01
Full Text Available No abstract available. Article truncated at 150 words. Case Presentation History of Present Illness A 67 year-old man presents 10 days after swallowing a capsule endoscopy camera that was never retrieved. The wireless capsule was swallowed asymptomatically for evaluation of heme positive stools after negative upper and lower endoscopies. Patient noted that the evening after swallowing the camera he developed mild shortness of breath and cough. The cough and shortness of breath were persistent and worsened while lying down and when moving positions. He denied prior issues with swallowing or aspiration. Review of Systems Negative other than what is noted above. PMH, SH, and FH Past medical history: coronary artery disease, peripheral vascular disease, hyperlipidemia Surgical history: femoral-popliteal bypass, previous shoulder and back surgery Social history: 1 pack/day of cigarettes for 50 years, prior alcohol usage but not current, no illicit drugs Family history: no pulmonary diseases Physical Exam Vital signs: temperature 36.7º C, heart rate 86 beats per minute ...
15. Development of capsule assembling apparatus
International Nuclear Information System (INIS)
Tayama, Yoshinobu; Kanazawa, Yoshiharu; Sozawa, Shizuo; Kawamata, Kazuo; Shizuoka, Yoshihiro; Onizawa, Satoshi; Nakagawa, Tetsuya
2012-01-01
The service of JMTR hot laboratory, associated with the Japan Materials Testing Reactor, was started on 1971 to examine specimens irradiated mainly in the JMTR. A wide variety of post irradiation examinations for research and development of nuclear fuels and materials are available in the JMTR hot laboratory. This laboratory has an advantage that its hot cell is connected with JMTR by a canal directly, and it is easy to transport irradiated capsule and specimens. New power ramping test for the high burn-up fuels by using the JMTR has been planed. The power ramping test using a boiling water capsule facility needs a re-capsuling of fuel rods for re-irradiation, and a modification of the facility up to about 100 GWD/t were necessary. This report introduces the new handling techniques and capsule assembling apparatus for the boiling water capsule facility. (author)
16. Stieltjes-moment-theory technique for calculating resonance width's
International Nuclear Information System (INIS)
Hazi, A.U.
1978-12-01
A recently developed method for calculating the widths of atomic and molecular resonances is reviewed. The method is based on the golden-rule definition of the resonance width, GAMMA(E). The method uses only square-integrable, L 2 , basis functions to describe both the resonant and the non-resonant parts of the scattering wave function. It employs Stieltjes-moment-theory techniques to extract a continuous approximation for the width discrete representation of the background continuum. Its implementation requires only existing atomic and molecular structure codes. Many-electron effects, such as correlation and polarization, are easily incorporated into the calculation of the width via configuration interaction techniques. Once the width, GAMMA(E), has been determined, the energy shift can be computed by a straightforward evaluation of the required principal-value integral. The main disadvantage of the method is that it provides only the total width of a resonance which decays into more than one channel in a multichannel problem. A review of the various aspects of the theory is given first, and then representative results that have been obtained with this method for several atomic and molecular resonances are discussed. 28 references, 3 figures, 4 tables
17. Quantitative measurements in capsule endoscopy.
Science.gov (United States)
Keuchel, M; Kurniawan, N; Baltes, P; Bandorski, D; Koulaouzidis, A
2015-10-01
This review summarizes several approaches for quantitative measurement in capsule endoscopy. Video capsule endoscopy (VCE) typically provides wireless imaging of small bowel. Currently, a variety of quantitative measurements are implemented in commercially available hardware/software. The majority is proprietary and hence undisclosed algorithms. Measurement of amount of luminal contamination allows calculating scores from whole VCE studies. Other scores express the severity of small bowel lesions in Crohn׳s disease or the degree of villous atrophy in celiac disease. Image processing with numerous algorithms of textural and color feature extraction is further in the research focuses for automated image analysis. These tools aim to select single images with relevant lesions as blood, ulcers, polyps and tumors or to omit images showing only luminal contamination. Analysis of motility pattern, size measurement and determination of capsule localization are additional topics. Non-visual wireless capsules transmitting data acquired with specific sensors from the gastrointestinal (GI) tract are available for clinical routine. This includes pH measurement in the esophagus for the diagnosis of acid gastro-esophageal reflux. A wireless motility capsule provides GI motility analysis on the basis of pH, pressure, and temperature measurement. Electromagnetically tracking of another motility capsule allows visualization of motility. However, measurement of substances by GI capsules is of great interest but still at an early stage of development. Copyright © 2015 Elsevier Ltd. All rights reserved.
18. Capsulitis of the Second Toe
Science.gov (United States)
... arch that is structurally unstable and a tight calf muscle. Symptoms Because capsulitis of the second toe is ... may be prescribed for patients who have tight calf muscles. Shoe modifications. Supportive shoes with stiff soles are ...
19. Status of irradiation capsule design
International Nuclear Information System (INIS)
Nagata, Hiroshi; Yamaura, Takayuki; Nagao, Yoshiharu
2013-01-01
For the irradiation test after the restart of JMTR, further precise temperature control and temperature prediction are required. In the design of irradiation capsule, particularly sophisticated irradiation temperature prediction and evaluation are urged. Under such circumstance, among the conventional design techniques of irradiation capsule, the authors reviewed the evaluation method of irradiation temperature. In addition, for the improvement of use convenience, this study examined and improved FINAS/STAR code in order to adopt the new calculation code that enables a variety of analyses. In addition, the study on the common use of the components for radiation capsule enabled the shortening of design period. After the restart, the authors will apply this improved calculation code to the design of irradiation capsule. (A.O.)
20. Adhesive capsulitis: a review.
Science.gov (United States)
Ewald, Anthony
2011-02-15
Adhesive capsulitis is a common, yet poorly understood, condition causing pain and loss of range of motion in the shoulder. It can occur in isolation or concomitantly with other shoulder conditions (e.g., rotator cuff tendinopathy, bursitis) or diabetes mellitus. It is often self-limited, but can persist for years and may never fully resolve. The diagnosis is usually clinical, although imaging can help rule out other conditions. The differential diagnosis includes acromioclavicular arthropathy, autoimmune disease (e.g., systemic lupus erythematosus, rheumatoid arthritis), biceps tendinopathy, glenohumeral osteoarthritis, neoplasm, rotator cuff tendinopathy or tear (with or without impingement), and subacromial and subdeltoid bursitis. Several treatment options are commonly used, but few have high-level evidence to support them. Because the condition is often self-limited, observation and reassurance may be considered; however, this may not be acceptable to many patients because of the painful and debilitating nature of the condition. Nonsurgical treatments include analgesics (e.g., acetaminophen, nonsteroidal anti-inflammatory drugs), oral prednisone, and intra-articular corticosteroid injections. Home exercise regimens and physical therapy are often prescribed. Surgical treatments include manipulation of the joint under anesthesia and capsular release.
1. Summary Report for Capsule Dry Storage Project
Energy Technology Data Exchange (ETDEWEB)
JOSEPHSON, W S
2003-09-04
There are 1.936 cesium (Cs) and strontium (Sr) capsules stored in pools at the Waste Encapsulation and Storage Facility (WESF). These capsules will be moved to dry storage on the Hanford Site as an interim measure to reduce risk. The Cs/Sr Capsule Dry Storage Project (CDSP) is conducted under the assumption the capsules will eventually be moved to the repository at Yucca Mountain, and the design criteria include requirements that will facilitate acceptance at the repository. The storage system must also permit retrieval of capsules in the event vitrification of the capsule contents is pursued. A cut away drawing of a typical cesium chloride (CsCI) capsule and the capsule property and geometry information are provided in Figure 1.1. Strontium fluoride (SrF{sub 2}) capsules are similar in design to CsCl capsules. Further details of capsule design, current state, and reference information are given later in this report and its references. Capsule production and life history is covered in WMP-16938, Capsule Characterization Report for Capsule Dry Storage Project, and is briefly summarized in Section 5.2 of this report.
2. Polarization Optics
OpenAIRE
Fressengeas, Nicolas
2010-01-01
The physics of polarization optics *Polarized light propagation *Partially polarized light; DEA; After a brief introduction to polarization optics, this lecture reviews the basic formalisms for dealing with it: Jones Calculus for totally polarized light and Stokes parameters associated to Mueller Calculus for partially polarized light.
3. Stress Analysis of Cyrano Capsule Hanger
International Nuclear Information System (INIS)
Hasibuan, Djaruddin
2000-01-01
Base on the requirement criteria on nuclear installation, and to complete the document of the cyrano capsule facility the analysis of the cyrano capsule hanger has been done. The cyrano capsule hanger by the overhang installation on the main support of fixed bridge is a main support of whole of the cyrano capsule and frame. By using W 4 x 13 shave as main hanger of cyrano capsule, the maximum allowable stress was found to be bigger than the actual stress. From the final analysis it can be concluded that the hanger of the cyrano capsule is in safe condition
4. Endurance test for DUPIC capsule
International Nuclear Information System (INIS)
Chung, Heung June; Bae, K. K.; Lee, C. Y.; Park, J. M.; Ryu, J. S.
1999-07-01
This report presents the pressure drop, vibration and endurance test results for mini-plate fuel rig which were designed fabricately by KAERI. From the pressure drop test results, it is noted that the flow rate across the capsule corresponding to the pressure drop of 200 kPa is measured to be about 9.632 kg/sec. Vibration frequency for the capsule ranges from 14 to 18.5 Hz. RMS (Root Mean Square) displacement for the fuel rig is less than 14 μm, and the maximum displacement is less than 54 μm. Based on the endurance test results, the appreciable fretting wear for the DUPIC capsule was not detected. Oxidation on the support tube is observed, also tiny trace of wear between contact points observed. (author). 4 refs., 10 tabs., 45 figs
5. Triggered Release from Polymer Capsules
Energy Technology Data Exchange (ETDEWEB)
Esser-Kahn, Aaron P. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Odom, Susan A. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry; Sottos, Nancy R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Materials Science and Engineering; White, Scott R. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Aerospace Engineering; Moore, Jeffrey S. [Univ. of Illinois, Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology and Dept. of Chemistry
2011-07-06
Stimuli-responsive capsules are of interest in drug delivery, fragrance release, food preservation, and self-healing materials. Many methods are used to trigger the release of encapsulated contents. Here we highlight mechanisms for the controlled release of encapsulated cargo that utilize chemical reactions occurring in solid polymeric shell walls. Triggering mechanisms responsible for covalent bond cleavage that result in the release of capsule contents include chemical, biological, light, thermal, magnetic, and electrical stimuli. We present methods for encapsulation and release, triggering methods, and mechanisms and conclude with our opinions on interesting obstacles for chemically induced activation with relevance for controlled release.
6. Osmotic buckling of spherical capsules.
Science.gov (United States)
Knoche, Sebastian; Kierfeld, Jan
2014-11-07
We study the buckling of elastic spherical shells under osmotic pressure with the osmolyte concentration of the exterior solution as a control parameter. We compare our results for the bifurcation behavior with results for buckling under mechanical pressure control, that is, with an empty capsule interior. We find striking differences for the buckling states between osmotic and mechanical buckling. Mechanical pressure control always leads to fully collapsed states with opposite sides in contact, whereas uncollapsed states with a single finite dimple are generic for osmotic pressure control. For sufficiently large interior osmolyte concentrations, osmotic pressure control is qualitatively similar to buckling under volume control with the volume prescribed by the osmolyte concentrations inside and outside the shell. We present a quantitative theory which also captures the influence of shell elasticity on the relationship between osmotic pressure and volume. These findings are relevant for the control of buckled shapes in applications. We show how the osmolyte concentration can be used to control the volume of buckled shells. An accurate analytical formula is derived for the relationship between the osmotic pressure, the elastic moduli and the volume of buckled capsules. This also allows use of elastic capsules as osmotic pressure sensors or deduction of elastic properties and the internal osmolyte concentration from shape changes in response to osmotic pressure changes. We apply our findings to published experimental data on polyelectrolyte capsules.
7. Photon Production Within Storage Capsules
CERN Document Server
Rittmann, P D
2003-01-01
This report provides tables and electronic worksheets that list the photon production rate within SrF2 and CsC1 storage capsules, particularly the continuous spectrum of bremsstrahlung photons from the slowing down of the emitted electrons (BREMCALC).
8. Sensor capsule for diagnosis of gastric disorders
Science.gov (United States)
Holen, J. T.
1972-01-01
Motility and pH sensor capsule is developed to monitor gastric acidity, pressure, and temperature. Capsule does not interfere with digestion. Sensor is capsule which includes pH electrode, Pitran pressure transducer, and thermistor temperature sensor all potted in epoxy and enclosed in high density polyethylene sheath.
9. Lateral migration of a capsule in a parabolic flow.
Science.gov (United States)
Nix, S; Imai, Y; Ishikawa, T
2016-07-26
Red blood cells migrate to the center of the blood vessel in a process called axial migration, while other blood cells, such as white blood cells and platelets, are disproportionately found near the blood vessel wall. However, much is still unknown concerning the lateral migration of cells in the blood; the specific effect of hydrodynamic factors such as a wall or a shear gradient is still unclear. In this study, we investigate the lateral migration of a capsule using the boundary integral method, in order to compute exactly an infinite computational domain for an unbounded parabolic flow and a semi-infinite computational domain for a near-wall parabolic flow in the limit of Stokes flow. We show that the capsule lift velocity in an unbounded parabolic flow is linear with respect to the shear gradient, while the lift velocity in a near-wall parabolic flow is dependent on the distance to the wall. Then, using these relations, we give an estimation of the relative effect of the shear gradient as a function of channel width and distance between the capsule and the wall. This estimation can be used to determine cases in which the effect of the shear gradient or wall can be neglected; for example, the formation of the cell-free layer in blood vessels is determined to be unaffected by the magnitude of the shear gradient. Copyright © 2015 Elsevier Ltd. All rights reserved.
10. Probing cell internalisation mechanics with polymer capsules.
Science.gov (United States)
Chen, Xi; Cui, Jiwei; Ping, Yuan; Suma, Tomoya; Cavalieri, Francesca; Besford, Quinn A; Chen, George; Braunger, Julia A; Caruso, Frank
2016-10-06
We report polymer capsule-based probes for quantifying the pressure exerted by cells during capsule internalisation (P in ). Poly(methacrylic acid) (PMA) capsules with tuneable mechanical properties were fabricated through layer-by-layer assembly. The P in was quantified by correlating the cell-induced deformation with the ex situ osmotically induced deformation of the polymer capsules. Ultimately, we found that human monocyte-derived macrophage THP-1 cells exerted up to approximately 360 kPa on the capsules during internalisation.
11. DIABETES AND SHOULDER ADHESIVE CAPSULITIS
OpenAIRE
J. Mohanakrishnan; Bhanumathy Mohanakrishnan
2016-01-01
Background: Adhesive capsulitis (AC) of shoulder is a common condition encountered by physical therapists in their routine outpatient care services; AC of shoulder is as by itself being a self limiting disorder lasts from months to years causing pain and discomfort to the patients. The condition is commonly associated with Diabetes mellitus or other co morbidities. The incidence of AC is high among diabetic individuals and it becomes mandatory on the part of physical therapists and other heal...
12. Contraindications for video capsule endoscopy
OpenAIRE
Bandorski, Dirk; Kurniawan, Niehls; Baltes, Peter; Hoeltgen, Reinhard; Hecker, Matthias; Stunder, Dominik; Keuchel, Martin
2016-01-01
Video capsule endoscopy (VCE) has been applied in the last 15 years in an increasing field of applications. Although many contraindications have been put into perspective, some precautions still have to be considered. Known stenosis of the gastrointestinal tract is a clear contraindication for VCE unless surgery is already scheduled or at least has been considered as an optional treatment modality. In patients with a higher incidence of stenosis, as in an established diagnosis of Crohn?s dise...
13. A niche width model of optimal specialization
NARCIS (Netherlands)
Bruggeman, J.P.; Ó Nualláin, Breanndán
2000-01-01
Niche width theory, a part of organizational ecology, predicts whether “specialist” or “generalist” forms of organizations have higher “fitness,” in a continually changing environment. To this end, niche width theory uses a mathematical model borrowed from biology. In this paper, we first loosen the
14. Constant Width Planar Computation Characterizes ACC0
DEFF Research Database (Denmark)
Hansen, K.A.
2004-01-01
We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...
15. Constant Width Planar Computation Characterizes ACC0
DEFF Research Database (Denmark)
Hansen, Kristoffer Arnsfelt
2006-01-01
We obtain a characterization of ACC0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...
16. 7 CFR 29.1085 - Width.
Science.gov (United States)
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Width. 29.1085 Section 29.1085 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Heavy Fleshy Medium Thin Oil Lean Oily Rich Color intensity Pale Weak Moderate Strong Deep. Width...
17. Biologic width dimensions--a systematic review.
Science.gov (United States)
Schmidt, Julia C; Sahrmann, Philipp; Weiger, Roland; Schmidlin, Patrick R; Walter, Clemens
2013-05-01
Consideration of the biologic width in restorative dentistry seems to be important for maintaining periodontal health. To evaluate the dimensions of the biologic width in humans. A systematic literature search was performed for publications published by 28 September 2012 using five different electronic databases; this search was complemented by a manual search. Two reviewers conducted the study selection, data collection, and validity assessment. The PRISMA criteria were applied. From 615 titles identified by the search strategy, 14 publications were included and six were suitable for meta-analyses. Included studies were published from the years 1924 to 2012. They differed with regard to measurements of the biologic width. Mean values of the biologic width obtained from two meta-analyses ranged from 2.15 to 2.30 mm, but large intra- and inter-individual variances (subject sample range: 0.2 - 6.73 mm) were observed. The tooth type and site, the presence of a restoration and periodontal diseases/surgery affected the dimensions of the biologic width. Pronounced heterogeneity among studies regarding methods and outcome measures exists. No universal dimension of the biologic width appears to exist. Establishment of periodontal health is suggested prior to the assessment of the biologic width within reconstructive dentistry. © 2013 John Wiley & Sons A/S.
18. Capsule Endoscopy: A Single Centre Experience with the First 226 Capsules
Directory of Open Access Journals (Sweden)
R Enns
2004-01-01
Full Text Available BACKGROUND: Capsule endoscopy (CE refers to a novel diagnostic method of imaging the gastrointestinal tract using a wireless capsule that transmits images to a data recorder while the device traverses the small intestine.
19. Anomalous width variation of rarefactive ion acoustic solitary waves in the context of auroral plasmas
Directory of Open Access Journals (Sweden)
S. S. Ghosh
2004-01-01
Full Text Available The presence of dynamic, large amplitude solitary waves in the auroral regions of space is well known. Since their velocities are of the order of the ion acoustic speed, they may well be considered as being generated from the nonlinear evolution of ion acoustic waves. However, they do not show the expected width-amplitude correlation for K-dV solitons. Recent POLAR observations have actually revealed that the low altitude rarefactive ion acoustic solitary waves are associated with an increase in the width with increasing amplitude. This indicates that a weakly nonlinear theory is not appropriate to describe the solitary structures in the auroral regions. In the present work, a fully nonlinear analysis based on Sagdeev pseudopotential technique has been adopted for both parallel and oblique propagation of rarefactive solitary waves in a two electron temperature multi-ion plasma. The large amplitude solutions have consistently shown an increase in the width with increasing amplitude. The width-amplitude variation profile of obliquely propagating rarefactive solitary waves in a magnetized plasma have been compared with the recent POLAR observations. The width-amplitude variation pattern is found to fit well with the analytical results. It indicates that a fully nonlinear theory of ion acoustic solitary waves may well explain the observed anomalous width variations of large amplitude structures in the auroral region.
20. Diagnostic and therapeutic radio pharmaceutical capsules
International Nuclear Information System (INIS)
Haney, T.A.; Wedeking, P.W.; Morcos, N.A.
1981-01-01
An improved pharmaceutical radioactive capsule consisting of a non-toxic, water soluble material adapted to being ingested and rapidly disintegrating on contact with fluids of the gastro-intestinal tract is described. Each capsule is provided with filler material supporting a pharmaceutically useful radioactive compound absorbable from the gastro-intestinal tract. The capsule is preferably of gelatin, methyl cellulose or polyvinyl alcohol and the filler is a polyethylene glycol. The radioactive compound may be iodine e.g. sodium radioiodide I-131 or 123. The capsule may also contain a reducing agent e.g. sodium thiosulphate, sulphite, or bisulphite. (author)
1. Challenges and Future of Wireless Capsule Endoscopy.
Science.gov (United States)
Saurin, Jean-Christophe; Beneche, Nicolas; Chambon, Christine; Pioche, Mathieu
2016-01-01
In 2015, capsule endoscopy was introduced as the main investigation method for small bowel mucosal diseases, and its role in colonic diseases has been gradually revealed. Future challenges for capsule endoscopy, besides improvements of image quality and visualization of each part of the small bowel and colonic mucosa, include the development of gastric capsules, the capacity to perform histological examination of the mucosa, and maybe in the future, some capsule endoscopy-driven therapeutics. The aim of this review was to evaluate the clinical demands and feasibility of achieving the aforementioned objectives.
2. Critical swelling of fluctuating capsules
Science.gov (United States)
Diamant, Haim; Haleva, Emir
2009-03-01
In many natural transport processes the solute molecules to be transported are encapsulated in semipermeable, flexible membrane vesicles of micron size. We study the swelling of such fluctuating capsules, as the number of encapsulated particles is increased, or the concentration of the outer solution is decreased. The approach to the maximum volume-to-area ratio and the associated buildup of membrane tension involve a continuous phase transition and follow universal scaling laws. The criticality and its features are model-independent, arising solely from the interplay between volume and surface degrees of freedom.ootnotetextE. Haleva and H. Diamant, Phys. Rev. Lett. 101, 078104 (2008).
3. Direct measurement of the W boson width
International Nuclear Information System (INIS)
Abe, F.; Albrow, M.G.; Amidei, D.; Antos, J.; Anway-Wiese, C.; Apollinari, G.; Areti, H.; Atac, M.; Auchincloss, P.; Azfar, F.; Azzi, P.; Bacchetta, N.; Badgett, W.; Bailey, M.W.; Bao, J.; de Barbaro, P.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; Bartalini, P.; Bauer, G.; Baumann, T.; Bedeschi, F.; Behrends, S.; Belforte, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Benlloch, J.; Bensinger, J.; Benton, D.; Beretvas, A.; Berge, J.P.; Bertolucci, S.; Bhatti, A.; Biery, K.; Binkley, M.; Bird, F.; Bisello, D.; Blair, R.E.; Blocker, C.; Bodek, A.; Bokhari, W.; Bolognesi, V.; Bortoletto, D.; Boswell, C.; Boulos, T.; Brandenburg, G.; Buckley-Geer, E.; Budd, H.S.; Burkett, K.; Busetto, G.; Byon-Wagner, A.; Byrum, K.L.; Cammerata, J.; Campagnari, C.; Campbell, M.; Caner, A.; Carithers, W.; Carlsmith, D.; Castro, A.; Cen, Y.; Cervelli, F.; Chapman, J.; Cheng, M.; Chiarelli, G.; Chikamatsu, T.; Cihangir, S.; Clark, A.G.; Cobal, M.; Contreras, M.; Conway, J.; Cooper, J.; Cordelli, M.; Crane, D.; Cunningham, J.D.; Daniels, T.; DeJongh, F.; Delchamps, S.; Dell'Agnello, S.; Dell'Orso, M.; Demortier, L.; Denby, B.; Deninno, M.; Derwent, P.F.; Devlin, T.; Dickson, M.; Donati, S.; Drucker, R.B.; Dunn, A.; Einsweiler, K.; Elias, J.E.; Ely, R.; Engels, E. Jr.; Eno, S.; Errede, D.; Errede, S.; Fan, Q.; Farhat, B.; Fiori, I.; Flaugher, B.; Foster, G.W.; Franklin, M.; Frautschi, M.; Freeman, J.; Friedman, J.; Frisch, H.; Fry, A.; Fuess, T.A.; Fukui, Y.; Funaki, S.; Gagliardi, G.; Galeotti, S.; Gallinaro, M.; Garfinkel, A.F.; Geer, S.; Gerdes, D.W.; Giannetti, P.; Giokaris, N.; Giromini, P.; Gladney, L.; Glenzinski, D.; Gold, M.; Gonzalez, J.; Gordon, A.; Goshaw, A.T.; Goulianos, K.; Grassmann, H.; Grewal, A.; Grieco, G.; Groer, L.; Grosso-Pilcher, C.; Haber, C.; Hahn, S.R.; Hamilton, R.; Handler, R.; Hans, R.M.; Hara, K.; Harral, B.; Harris, R.M.; Hauger, S.A.; Hauser, J.; Hawk, C.; Heinrich, J.; Cronin-Hennessy, D.; Hollebeek, R.; Holloway, L.; Hoelscher, A.
1995-01-01
This Letter describes a direct measurement of the W boson decay width, Γ(W), using the high-mass tail of the transverse mass spectrum of W→eν decays recorded by the Collider Detector at Fermilab. We find Γ(W)=2.11±0.28(stat) ± 0.16(syst) GeV and compare this direct measurement with indirect means of obtaining the width
4. Indirect MR arthrographic findings of adhesive capsulitis.
Science.gov (United States)
Song, Kyoung Doo; Kwon, Jong Won; Yoon, Young Cheol; Choi, Sang-Hee
2011-12-01
The objective of our study was to compare the indirect MR arthrographic findings of patients with adhesive capsulitis and patients without adhesive capsulitis. Indirect MR arthrograms of 35 patients (21 women, 14 men; mean age, 50.1 years) diagnosed with adhesive capsulitis clinically were compared with indirect MR arthrograms of 45 patients (23 women, 22 men; mean age, 48.9 years) without adhesive capsulitis. Joint capsule thickness in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were, respectively, evaluated on coronal T2-weighted images and coronal and sagittal fat-suppressed enhanced T1-weighted images by two radiologists independently. Reliability was studied using the intraclass correlation coefficient (ICC). Receiver operating characteristic (ROC) curves were compared. Patients with adhesive capsulitis had significantly thickened joint capsules in the axillary recess and a thickened enhancing portion in the axillary recess and in the rotator interval. The difference in the thicknesses of the enhancing portion in the axillary recess and in the rotator interval were significantly greater than the difference in joint capsule thicknesses in the axillary recess between the adhesive capsulitis group and the control group (p capsule in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were 0.797, 0.861, and 0.847, respectively. An abundance of enhancing tissue in the rotator interval and thickening and enhancement of the axillary recess are signs suggestive of adhesive capsulitis on indirect MR arthrography.
5. DIABETES AND SHOULDER ADHESIVE CAPSULITIS
Directory of Open Access Journals (Sweden)
J. Mohanakrishnan
2016-08-01
Full Text Available Background: Adhesive capsulitis (AC of shoulder is a common condition encountered by physical therapists in their routine outpatient care services; AC of shoulder is as by itself being a self limiting disorder lasts from months to years causing pain and discomfort to the patients. The condition is commonly associated with Diabetes mellitus or other co morbidities. The incidence of AC is high among diabetic individuals and it becomes mandatory on the part of physical therapists and other health professionals to approach this issue on a holistic manner. This paper deals with the importance of a physiotherapist role in prevention and dealing with the causative factors of AC and not merely its symptom. Methods: Extensive literature review was done from the electronic data bases, Systematic reviews and critical reviews from Pub med indexed journals and other peer reviewed publications across the globe. Results: It was not the type of diabetes but the duration of the disease and the glycemic index, marking the causative factor for adhesive capsulitis of shoulder. Conclusion: It may be concluded that physiotherapist play a vital role in identifying the pre-diabetic or a diabetic state of an individual reporting in a multi disciplinary set up with a AC of shoulder, and also has a role in the prevention of AC by helping the individual to maintain a good glycemic control with a holistic approach which includes aerobic exercises, General Flexibility exercises, Weight management and Yoga therapy.
6. CT arthrography of adhesive capsulitis of the shoulder: Are MR signs applicable?
Directory of Open Access Journals (Sweden)
Milena Cerny
Full Text Available Objective: To determine if diagnostic signs of adhesive capsulitis (AC of the shoulder at Magnetic Resonance Imaging (MRI and arthrography (MRA are applicable to CT arthrography (CTA. Methods: 22 shoulder CTAs with AC were retrospectively reviewed for features described in MR literature. The control group was composed of 83 shoulder CTA divided into four subgroups 1 normal (N = 20, 2 omarthrosis (N = 19, 3 labral injury (N = 23, and 4 rotator cuff tear (N = 21. Two musculoskeletal radiologists assessed the rotator interval (RI for obliteration, increased width and thickening of coracohumeral ligament (CHL. The width and capsule thickness of the axillary recess were measured. Results: The width of the axillary recess was significantly decreased in the AC group (4.6 ± 2.6 mm versus 9.9 ± 4.6 mm, p â¤Â 0.0001; sensitivity and specificity of 84% and 80%. Thickness of the medial and lateral walls of the axillary capsule was significantly increased in the AC group (5.9 ± 1.3 mm versus 3.7 ± 1.1 mm, p â¤Â 0.0001 and 5.7 ± 1 mm versus 3.5 ± 1.3 mm, p â¤Â 0.0001, respectively. CHL thickness was significantly increased in the AC group (4.1 ± 1 mm (p â¤Â 0.001 in comparison to others groups. Obliteration of the RI was statistically significantly more frequent in patients with AC (72.7% (16/22 vs. 12% (10/83, p < 0.0001. Width of the RI did not differ significantly between patients and controls (p â¥Â 0.428. Conclusion: Decreased axillary width, and thickened axillary capsule are MR signs of AC applicable to CTA. Evaluation of rotator interval seems useful and reproducible only for obliteration. Keywords: Adhesive capsulitis, Frozen shoulder, Rotator interval, Arthrography, CTA, MRA
7. Passive sorting of capsules by deformability
Science.gov (United States)
Haener, Edgar; Juel, Anne
We study passive sorting according to deformability of liquid-filled ovalbumin-alginate capsules. We present results for two sorting geometries: a straight channel with a half-cylindrical obstruction and a pinched flow fractioning device (PFF) adapted for use with capsules. In the half-cylinder device, the capsules deform as they encounter the obstruction, and travel around the half-cylinder. The distance from the capsule's centre of mass to the surface of the half-cylinder depends on deformability, and separation between capsules of different deformability is amplified by diverging streamlines in the channel expansion downstream of the obstruction. We show experimentally that capsules can be sorted according to deformability with their downstream position depending on capillary number only, and we establish the sensitivity of the device to experimental variability. In the PFF device, particles are compressed against a wall using a strong pinching flow. We show that capsule deformation increases with the intensity of the pinching flow, but that the downstream capsule position is not set by deformation in the device. However, when using the PFF device like a T-Junction, we achieve improved sorting resolution compared to the half-cylinder device.
8. The future of wireless capsule endoscopy.
Science.gov (United States)
Swain, Paul
2008-07-14
We outline probable and possible developments with wireless capsule endoscopy. It seems likely that capsule endoscopy will become increasingly effective in diagnostic gastrointestinal endoscopy. This will be attractive to patients especially for cancer or varices detection because capsule endoscopy is painless and is likely to have a higher take up rate compared to conventional colonoscopy and gastroscopy. Double imager capsules with increased frame rates have been used to image the esophagus for Barrett's and esophageal varices. The image quality is not bad but needs to be improved if it is to become a realistic substitute for flexible upper and lower gastrointestinal endoscopy. An increase in the frame rate, angle of view, depth of field, image numbers, duration of the procedure and improvements in illumination seem likely. Colonic, esophageal and gastric capsules will improve in quality, eroding the supremacy of flexible endoscopy, and become embedded into screening programs. Therapeutic capsules will emerge with brushing, cytology, fluid aspiration, biopsy and drug delivery capabilities. Electrocautery may also become possible. Diagnostic capsules will integrate physiological measurements with imaging and optical biopsy, and immunologic cancer recognition. Remote control movement will improve with the use of magnets and/or electrostimulation and perhaps electromechanical methods. External wireless commands will influence capsule diagnosis and therapy and will increasingly entail the use of real-time imaging. However, it should be noted that speculations about the future of technology in any detail are almost always wrong.
9. Emission polarization study on quartz and calcite.
Science.gov (United States)
Vincent, R. K.
1972-01-01
Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.
10. Thermoregulation of Capsule Production by Streptococcus pyogenes
Science.gov (United States)
Kang, Song Ok; Wright, Jordan O.; Tesorero, Rafael A.; Lee, Hyunwoo; Beall, Bernard; Cho, Kyu Hong
2012-01-01
The capsule of Streptococcus pyogenes serves as an adhesin as well as an anti-phagocytic factor by binding to CD44 on keratinocytes of the pharyngeal mucosa and the skin, the main entry sites of the pathogen. We discovered that S. pyogenes HSC5 and MGAS315 strains are further thermoregulated for capsule production at a post-transcriptional level in addition to the transcriptional regulation by the CovRS two-component regulatory system. When the transcription of the hasABC capsular biosynthetic locus was de-repressed through mutation of the covRS system, the two strains, which have been used for pathogenesis studies in the laboratory, exhibited markedly increased capsule production at sub-body temperature. Employing transposon mutagenesis, we found that CvfA, a previously identified membrane-associated endoribonuclease, is required for the thermoregulation of capsule synthesis. The mutation of the cvfA gene conferred increased capsule production regardless of temperature. However, the amount of the capsule transcript was not changed by the mutation, indicating that a post-transcriptional regulator mediates between CvfA and thermoregulated capsule production. When we tested naturally occurring invasive mucoid strains, a high percentage (11/53, 21%) of the strains exhibited thermoregulated capsule production. As expected, the mucoid phenotype of these strains at sub-body temperature was due to mutations within the chromosomal covRS genes. Capsule thermoregulation that exhibits high capsule production at lower temperatures that occur on the skin or mucosal surface potentially confers better capability of adhesion and invasion when S. pyogenes penetrates the epithelial surface. PMID:22615992
11. The decay width of stringy hadrons
Directory of Open Access Journals (Sweden)
Jacob Sonnenschein
2018-02-01
We fit the theoretical decay width to experimental data for mesons on the trajectories of ρ, ω, π, η, K⁎, ϕ, D, and Ds⁎, and of the baryons N, Δ, Λ, and Σ. We examine both the linearity in L and the exponential suppression factor. The linearity was found to agree with the data well for mesons but less for baryons. The extracted coefficient for mesons A=0.095±0.015 is indeed quite universal. The exponential suppression was applied to both strong and radiative decays. We discuss the relation with string fragmentation and jet formation. We extract the quark–diquark structure of baryons from their decays. A stringy mechanism for Zweig suppressed decays of quarkonia is proposed and is shown to reproduce the decay width of ϒ states. The dependence of the width on spin and flavor symmetry is discussed. We further apply this model to the decays of glueballs and exotic hadrons.
12. Relative Width and Height of Handwritten Letter.
Science.gov (United States)
Lizega Rika, Joseba
2018-01-01
This is an exploratory study that analyzes the width and the height of letters in two texts written by each of the 21 writers analyzed. After detrending the linear, text, and allograph trends, we proceeded to comparing the sizes obtained in different texts. The different detrended series were compared by means of correlation and t-test. According to the results regarding the width of letters, the texts of 19 of 21 writers correlated strongly, whereas the texts of two writers did not correlate with the limits of the threshold. With regard to the height of letters, texts written by between 18 and 21 writers of 21 writers correlated strongly, whereas texts that did not correlate were within the threshold value. Regarding both the width and the height of letters, of 21 writers, texts written by between 19 and 21 individuals were found to correlate strongly. © 2017 American Academy of Forensic Sciences.
13. Alliances and Bisection Width for Planar Graphs
DEFF Research Database (Denmark)
Olsen, Martin; Revsbæk, Morten
2013-01-01
An alliance in a graph is a set of vertices (allies) such that each vertex in the alliance has at least as many allies (counting the vertex itself) as non-allies in its neighborhood of the graph. We show that any planar graph with minimum degree at least 4 can be split into two alliances...... in polynomial time. We base this on a proof of an upper bound of n on the bisection width for 4-connected planar graphs with an odd number of vertices. This improves a recently published n + 1 upper bound on the bisection width of planar graphs without separating triangles and supports the folklore conjecture...... that a general upper bound of n exists for the bisection width of planar graphs....
14. Line width of Josephson flux flow oscillators
DEFF Research Database (Denmark)
Koshelets, V.P.; Dmitriev, P.N.; Sobolev, A.S.
2002-01-01
A combination of wide-band electronic tunability and moderate free-running line width makes the Josephson flux flow oscillator (FFO) a perfect on-chip local oscillator for integrated submillimeter-wave SIS receivers. The possibility of FFO phase locking at all frequencies of interest has...... to be proven before one initiates real FFO applications. To achieve this goal a comprehensive set of line width measurements of the FFO operating in different regimes has been performed. FFOs with tapered shape have been successfully implemented in order to avoid the superfine resonant structure with voltage...... spacing of about 20 nV and extremely low differential resistance, recently observed in the IVC of the standard rectangular geometry. The obtained results have been compared with existing theories and FFO models in order to understand and possibly eliminate excess noise in the FFO. The intrinsic line width...
15. The decay width of stringy hadrons
Science.gov (United States)
Sonnenschein, Jacob; Weissman, Dorin
2018-02-01
In this paper we further develop a string model of hadrons by computing their strong decay widths and comparing them to experiment. The main decay mechanism is that of a string splitting into two strings. The corresponding total decay width behaves as Γ = π/2 ATL where T and L are the tension and length of the string and A is a dimensionless universal constant. We show that this result holds for a bosonic string not only in the critical dimension. The partial width of a given decay mode is given by Γi / Γ =Φi exp (- 2 πCmsep2 / T) where Φi is a phase space factor, msep is the mass of the "quark" and "antiquark" created at the splitting point, and C is a dimensionless coefficient close to unity. Based on the spectra of hadrons we observe that their (modified) Regge trajectories are characterized by a negative intercept. This implies a repulsive Casimir force that gives the string a "zero point length". We fit the theoretical decay width to experimental data for mesons on the trajectories of ρ, ω, π, η, K*, ϕ, D, and Ds*, and of the baryons N, Δ, Λ, and Σ. We examine both the linearity in L and the exponential suppression factor. The linearity was found to agree with the data well for mesons but less for baryons. The extracted coefficient for mesons A = 0.095 ± 0.015 is indeed quite universal. The exponential suppression was applied to both strong and radiative decays. We discuss the relation with string fragmentation and jet formation. We extract the quark-diquark structure of baryons from their decays. A stringy mechanism for Zweig suppressed decays of quarkonia is proposed and is shown to reproduce the decay width of ϒ states. The dependence of the width on spin and flavor symmetry is discussed. We further apply this model to the decays of glueballs and exotic hadrons.
16. Temperature dependence of giant dipole resonance width
International Nuclear Information System (INIS)
Vdovin, A.I.; Storozhenko, A.N.
2005-01-01
The quasiparticle-phonon nuclear model extended to finite temperature within the framework of the thermo field dynamics is applied to calculate a temperature dependence of the spreading width Γ d own of a giant dipole resonance. Numerical calculations are made for 12S n and 208 Pb nuclei. It is found that the width Γ d own increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones existing in the literature
17. 3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets
International Nuclear Information System (INIS)
Buice, E.S.; Alger, E.T.; Antipa, N.A.; Bhandarkar, S.D.; Biesiada, T.A.; Conder, A.D.; Dzenitis, E.G.; Flegel, M.S.; Hamza, A.V.; Heinbockel, C.L.; Horner, J.; Johnson, M.A.; Kegelmeyer, L.M.; Meyer, J.S.; Montesanti, R.C.; Reynolds, J.L.; Taylor, J.S.; Wegner, P.J.
2011-01-01
This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 (micro)m diameter glass-core fill-tube that tapers down to a 10(micro) diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1σ), which corresponds to approximately 5 (micro)m linear error on the capsule surface.
18. 3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets
Energy Technology Data Exchange (ETDEWEB)
Buice, E S; Alger, E T; Antipa, N A; Bhandarkar, S D; Biesiada, T A; Conder, A D; Dzenitis, E G; Flegel, M S; Hamza, A V; Heinbockel, C L; Horner, J; Johnson, M A; Kegelmeyer, L M; Meyer, J S; Montesanti, R C; Reynolds, J L; Taylor, J S; Wegner, P J
2011-02-18
This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 {micro}m diameter glass-core fill-tube that tapers down to a 10{micro} diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1{sigma}), which corresponds to approximately 5 {micro}m linear error on the capsule surface.
19. [Evaluation of nopal capsules in diabetes mellitus].
Science.gov (United States)
Frati Munari, A C; Vera Lastra, O; Ariza Andraca, C R
1992-01-01
To find out if commercial capsules with dried nopal (prickle-pear cactus, Opuntia ficus indica may have a role in the management of diabetes mellitus, three experiments were performed: 30 capsules where given in fasting condition to 10 diabetic subjects and serum glucose was measured through out 3 hours; a control test was performed with 30 placebo capsules. OGTT with previous intake of 30 nopal or placebo capsules was performed in ten healthy individuals. In a crossover and single blinded study 14 diabetic patients withdrew the oral hypoglycemic treatment and received 10 nopal or placebo capsules t.i.d. during one week; serum glucose, cholesterol and tryglycerides levels were measured before and after each one-week period. Five healthy subjects were also studied in the same fashion. Opuntia capsules did not show acute hypoglycemic effect and did not influence OGTT. In diabetic patients serum glucose, cholesterol and tryglycerides levels did not change with Opuntia, but they increased with placebo (P nopal, while cholesterol and triglycerides decreased (P < 0.01 vs. placebo). The intake of 30 Opuntia capsules daily in patients with diabetes mellitus had a discrete beneficial effect on glucose and cholesterol. However this dose is unpractical and at present it is not recommended in the management of diabetes mellitus.
20. Polarization developments
International Nuclear Information System (INIS)
Prescott, C.Y.
1993-07-01
Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist
1. Radiative width of molecular-cluster states
International Nuclear Information System (INIS)
Alhassid, Y.; Gai, M.; Bertsch, G.F.
1982-01-01
Molecular states are characterized by enhanced electromagnetic deexcitations of many different multipolarities. The expected enhancement of E1, E2, and E3 transitions is examined by deriving molecular sum rules for radiative deexcitation widths and via a dimensionality approach. The enhancement of the E1 transitions is the most striking
2. Wireline equalization using pulse-width modulation
NARCIS (Netherlands)
Schrader, J.H.R.; Klumperink, Eric A.M.; Visschers, J.L.; Nauta, Bram
2006-01-01
Abstract-High-speed data links over copper cables can be effectively equalized using pulse-width modulation (PWM) pre-emphasis. This provides an alternative to the usual 2-tap FIR filters. The use of PWM pre-emphasis allows a channel loss at the Nyquist frequency of ~30dB, compared to ~20dB for a
3. Comparison of Arch Width Changes Following Orthodontic ...
African Journals Online (AJOL)
2015-11-21
Nov 21, 2015 ... they found optimal results are achieved when individual arch forms are maintained.[15]. This retrospective study used digital measurements of orthodontic models (1) to evaluate arch width changes in patients treated with fixed orthodontic appliances whose initial ovoid arch form was maintained following.
4. Bounding the Higgs boson width through interferometry.
Science.gov (United States)
Dixon, Lance J; Li, Ye
2013-09-13
We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.
5. Intrauterine fertilization capsules--a clinical trial
DEFF Research Database (Denmark)
Lenz, S; Lindenberg, S; Sundberg, K
1991-01-01
Treatment of 26 women with tubal infertility was attempted using intrauterine capsules loaded with oocytes and spermatozoa. The stimulation protocol was as used for in vitro fertilization and embryo transfer and consisted of short-term use of Buserelin, human menopausal gonadotropin, and human...... and piston from an intrauterine device. Six complete capsules and parts of two other capsules were expelled. None of the women became pregnant, compared with a pregnancy rate of 21% per aspiration following in vitro fertilization and embryo transfer during the same period....
6. Colon capsule endoscopy: toward the future.
Science.gov (United States)
Muguruma, Naoki; Tanaka, Kumiko; Teramae, Satoshi; Takayama, Tetsuji
2017-02-01
Colon capsule endoscopy is a wireless and minimally invasive technique for visualization of the whole colon. With recent improvements of technical features in second-generation systems, a more important role for colon capsule endoscopy is rapidly emerging. Although several limitations and drawbacks are yet to be resolved, its usefulness as a tool for colorectal cancer screening and monitoring disease activity in inflammatory bowel diseases has become more apparent with increased use. Further investigations, including multicenter trials, are required to evaluate the substantial role of the colon capsule in managing colorectal diseases.
7. Polyamide capsules via soft templating with oil drops-1. Morphological studies of the capsule wall.
Science.gov (United States)
Essawy, Hisham; Tauer, Klaus
2010-02-01
Poly(terephthalamide) microcapsules can be reproducibly and easily prepared by interfacial polycondensation around emulsion droplets in water. Oil drops of cyclohexane/chloroform mixture stabilized with poly(vinyl alcohol) containing terephthaloylchloride serve as soft template. The interfacial polycondensation starts immediately after addition of an amine mixture (hexamethylenediamine/diethylenetriamine). Light and scanning electron microscopy prove the formation of capsules with size distribution in the range from a few up to 100 microm depending on particular composition of the reaction mixture. The morphology of the capsule wall is characterized by precipitated particles. If instead of pure organic solvents a reactive oil phase is used as template, the capsules can serve in subsequent reactions as templates for the synthesis of composite particles. In this way, styrene can be radically polymerized inside the capsule leading to composite capsules. The capsule morphology is determined by the partition of all components between all phases.
8. Skyrmion dynamics in width-varying nanotracks and implications for skyrmionic applications
Science.gov (United States)
Chen, Xing; Kang, Wang; Zhu, Daoqian; Zhang, Xichao; Lei, Na; Zhang, Youguang; Zhou, Yan; Zhao, Weisheng
2017-11-01
A comprehensive study of the magnetic skyrmion dynamics in terms of size, velocity, energy, and stability in width-varying nanotracks is reported by micromagnetic simulations. We find that the diameter of a skyrmion reduces with the decrease in the nanotrack width in the spin Hall effect (SHE)-induced skyrmion motion. Accordingly, the skyrmion energy increases giving rise to the growing instability of the skyrmion. It is also numerically demonstrated that the velocity of the skyrmion varies during the motion, since the repulsive force of the nanotrack edges acting on the skyrmion as well as the driving force created by the SHE associated with the size of the skyrmion have a joint impact on the skyrmion motion dynamics in the width-varying nanotrack. In addition, one interesting finding reveals that skyrmions with small sizes, which may be inaccessible to typical approaches by means of directly injecting a spin-polarized current, could be obtained by utilizing this structure. This finding is potential for generating nanoscale skyrmions in skyrmionic applications with ultra-dense density. Finally, inspired by the skyrmion dynamics in the width-varying nanotrack, a general summary on the tradeoff between the nanotrack width (storage density) and the skyrmion velocity (data access speed) is given by further analyzing the skyrmion dynamics in parallel nanotracks with different widths, which may provide guidelines in designing racetrack-type skyrmionic applications.
9. Polarization, political
NARCIS (Netherlands)
Wojcieszak, M.; Mazzoleni, G.; Barnhurst, K.G.; Ikeda, K.; Maia, R.C.M.; Wessler, H.
2015-01-01
Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass
10. Polarization holography
DEFF Research Database (Denmark)
Nikolova, L.; Ramanujam, P.S.
Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...
11. Therapeutic Capsule Endoscopy: Opportunities and Challenges
Directory of Open Access Journals (Sweden)
Mahdi Rasouli
2011-01-01
Full Text Available The increasing demand for non-invasive (or less-invasive monitoring and treatment of medical conditions has attracted both physicians and engineers to work together and investigate new methodologies. Wireless capsule endoscopy is a successful example of such techniques which has become an accepted routine for diagnostic inspection of the gastrointestinal tract. This method offers a non-invasive alternative to traditional endoscopy and provides the opportunity for exploring distal areas of the small intestine which are otherwise not accessible. Despite these advantages, wireless capsule endoscopy is still limited in functionality compared to traditional endoscopy. Wireless capsule endoscopes with advanced functionalities, such as biopsy or drug delivery, are highly desirable. In this article, the current status of wireless capsule endoscopy is reviewed together with some of its possible therapeutic applications as well as the existing challenges.
12. CAPSULE REPORT: HARD CHROME FUME ...
Science.gov (United States)
All existing information which includes the information extrapolated from the Hard Chrome Pollution Prevention Demonstration Project(s) and other sources derived from plating facilities and industry contacts, will be condensed and featured in this document. At least five chromium emission prevention/control devices have been tested covering a wide spectrum of techniques currently in use at small and large-sized chrome metal plating shops. The goal for limiting chromium emissions to levels specified in the MACT Standards are: (1) 0.030 milligrams per dry standard cubic meter of air (mg/dscm) for small facilities with existing tanks, (2) 0.015 mg/dscm for small facilities with new tanks or large facilities with existing or new tanks. It should be emphasized that chemical mist suppressants still have quality issues and work practices that need to be addressed when they are used. Some of the mist suppressants currently in use are: one-, two-, and three-stage mesh pad mist eliminators; composite mesh pad mist eliminators; packed-bed scrubbers and polyballs. This capsule report should, redominantly, emphasize pollution prevention techniques and include, but not be restricted to, the afore-mentioned devices. Information
13. Capsule production by Pseudomonas aeruginosa
Energy Technology Data Exchange (ETDEWEB)
Lynn, A.R.
1984-01-01
Mucoid strains of Pseudomonas aeruginosa, associated almost exclusively with chronic respiratory infections in patients with cystic fibrosis, possess a capsule composed of alginic acid similar to one produced by Azotobacter vinelandii. Recent reports have provided evidence that the biosynthetic pathway for alginate in P. aeruginosa may differ from the pathway proposed for A. vinelandii in that synthesis in P. aeruginosa may occur by way of the Entner-Doudoroff pathway. Incorporation of isotope from (6-/sup 14/C)glucose into alginate by both P. aueroginosa and A. vinelandii was 10-fold greater than that from either (1-/sup 14/C)/sup -/ or (2-/sup 14/C)glucose, indicating preferential utilization of the bottom half of the glucose molecule for alginate biosynthesis. These data strongly suggest that the Entner-Doudoroff pathway plays a major role in alginate synthesis in both P. aeruginosa and A. vinelandii. The enzymes of carbohydrate metabolism in mucoid strains of P. aeruginosa appear to be unchanged whether alignate is actively produced or not and activities do not differ significantly from nonmucoid strain PAO.
14. The history of time for capsule endoscopy.
Science.gov (United States)
Adler, Samuel N
2017-05-01
Capsule endoscopy was conceived by inventive minds of good people. In the beginning there was a will to do something for medicine. The idea fomented after a discourse between the talented engineer with his physician friend. It took years to develop the concept. Then excellent engineers created de novo the necessary components to turn the capsule into a viable reality. The story is a tribute to human ingenuity.
15. Adhesive capsulitis: review of imaging and treatment
International Nuclear Information System (INIS)
Harris, Guy; Bou-Haider, Pascal; Harris, Craig
2013-01-01
Adhesive capsulitis is one of the most common conditions affecting the shoulder; however, early clinical diagnosis can be challenging. Treatment is most effective when commenced prior to the onset of capsular thickening and contracture; consequently, the role of imaging is increasing. The aim of this review is to demonstrate the typical imaging appearances of adhesive capsulitis and to examine some of the evidence regarding each of these imaging modalities. An evaluation of the various management options available to the clinician is also presented.
16. Radioactive gas-containing polymeric capsule
International Nuclear Information System (INIS)
Winchell, H.S.; Lewis, R.E.
1975-01-01
A disposable ventilation study system for dispensing a single patient dosage of gaseous radioisotopes to patients for pulmonary function studies is disclosed. A gas impermeable capsule encloses the gaseous radioisotope and is stored within a radioactivity shielding body of valve means which shears the capsule to dispense the radioisotope to the patient. A breathing bag receives the patient's exhalation of the radioisotope and permits rebreathing of the radioisotope by the patient. 18 claims, 7 drawing figures
17. Exotic meson decay widths using lattice QCD
International Nuclear Information System (INIS)
Cook, M. S.; Fiebig, H. R.
2006-01-01
A decay width calculation for a hybrid exotic meson h, with J PC =1 -+ , is presented for the channel h→πa 1 . This quenched lattice QCD simulation employs Luescher's finite box method. Operators coupling to the h and πa 1 states are used at various levels of smearing and fuzzing, and at four quark masses. Eigenvalues of the corresponding correlation matrices yield energy spectra that determine scattering phase shifts for a discrete set of relative πa 1 momenta. Although the phase shift data is sparse, fits to a Breit-Wigner model are attempted, resulting in a decay width of about 60 MeV when averaged over two lattice sizes having a lattice spacing of 0.07 fm
18. Analysis of reduced widths and size
International Nuclear Information System (INIS)
Sharma, H.C.; Ram Raj; Nath, N.
1977-01-01
Recent data on S-wave neutron reduced widths for a large number of nuclei have been analysed nucleus-wise and the calculations for the degree of freedom of the associated (chi) 2 -distribution have been made using the Porter and Thomas procedure. It is noted that a number of nuclei can be fitted by a (chi) 2 -distribution with degree of freedom one, while there are few which are identified to follow a (chi) 2 -distribution with degree of freedom two and even more than two. The present analysis thus contradicts the usual presumption according to which the degree of freedom is taken to be always unity. An analytical attempt has also been made to ascertain the suitability of the data on reduced widths to be used for the analysis. These considerations are likely to modify the neutron cross-section evaluations. (author)
19. Palindromic widths of nilpotent and wreath products
Indian Academy of Sciences (India)
This result was gen- eralized by Bardakov and Tolstykh [8] who proved that almost all free products have infinite palindromic width; the only exception is given by ..... Next, let X0 ⊆ X and Y0 ⊆ Y be sets of representatives of elements of ¯X and. ¯Y respectively. Let ¯g ∈ ¯Gn be the homomorphic image of g ∈ Gn, then ¯g =.
20. Polar Bears
Science.gov (United States)
Amstrup, Steven C.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.
2002-01-01
Polar bears (Ursus maritimus) are hunted throughout most of their range. In addition to hunting polar bears of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990).Little was known at the start of this project about how polar bears move about in their environment, and although it was understood that many bears travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000).As human populations increase and demands for polar bears and other arctic resources escalate, managers must know the sizes and distributions of the polar bear populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults.Our objectives for this research were 1) to determine the seasonal and annual movements of polar bears in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar bear population, and 4) to establish reproduction and survival rates (Amstrup 2000).
1. Probing the Physics of Burning DT Capsules Using Gamma-ray Diagnostics
Energy Technology Data Exchange (ETDEWEB)
Hayes-Sterbenz, Anna Catherine [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hale, Gerald M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jungman, Gerard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Paris, Mark W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-02-01
The Gamma Reaction History (GRH) diagnostic developed and lead by the Los Alamos National Laboratory GRH Team is used to determine the bang time and burn width of imploded inertial confinement fusion capsules at the National Ignition Facility. The GRH team is conceptualizing and designing a new Gamma-to-Electron Magnetic Spectrometer (GEMS), that would be capable of an energy resolution ΔE/E~3-5%. In this whitepaper we examine the physics that could be explored by the combination of these two gamma-ray diagnostics, with an emphasis on the sensitivity needed for measurements. The main areas that we consider are hydrodynamical mixing, ablator areal density and density profile, and temporal variations of the density of the cold fuel and the ablator during the DT burn of the capsule.
2. Width and partial widths of unstable particles in the light of the Nielsen identities
International Nuclear Information System (INIS)
Grassi, P.A.; Sirlin, A.; Kniehl, B.A.; Hamburg Univ.
2001-09-01
Fundamental properties of unstable particles, including mass, width, and partial widths, are examined on the basis of the Nielsen identities (NI) that describe the gauge dependence of Green functions. In particular, we prove that the pole residues and associated definitions of branching ratios and partial widths are gauge independent to all orders. A simpler, previously discussed definition of branching ratios and partial widths is found to be gauge independent through next-to-next-to-leading order. It is then explained how it may be modified in order to extend the gauge independence to all orders. We also show that the physical scattering amplitude is the most general combination of self-energy, vertex, and box contributions that is gauge independent for arbitrary s, discuss the analytical properties of the NI functions, and exhibit explicitly their one-loop expressions in the Z-γ sector of the Standard Model. (orig.)
3. Effect of polysaccharide capsule of the microalgae Staurastrum iversenii var. americanum on diffusion of charged and uncharged molecules, using EPR technique
International Nuclear Information System (INIS)
Freire-Nordi, Cristina S.; Nascimento, Otaciro R.; Vieira, Armando A.H.; Nakaie, Clovis R.
2006-01-01
The existence of a mucilaginous envelope, sheath or capsule is usual in many desmids, but few data concerning its function are available. Previous studies of the transport function and permeation of molecules through the algae capsules were done using the algae Spondylosium panduriforme and Nephrocytium lunatum, the Electron Paramagnetic Resonance (EPR) technique, and different spin labels. The results suggested that the capsule functions as a selective diffusion medium. In the present work charged and uncharged molecules (spin labels group A) and Staurastrum iversenii var. americanum (Desmids),whose alga presents a great mucilaginous capsule, were used. Charged nitroxide molecules similar to amino acids (spin labels group B) were also used allowing a better understanding of the electrostatic effect in the permeation process across the capsule. The role of the cell capsule in the solute diffusion was evaluated by determining the capsulated and decapsulated cell permeation times. The permeation times for all spin labels tested in the cells lacking capsules were always shorter than those containing this physical barrier. The decay times of spin labels group A observed for S. iversenii were compared to other studied algae. The results regarding the diffusion of charged spin labels group B suggested that the interaction of cell capsule occurs more strongly with negatively charged molecules than with positively charged ones. The results obtained in this work with spin labels group A confirm that the capsule is an essential structure for the cell, and that due to the polar interactions with the spin labels, it plays an important role in the selection of small molecules. Several parameters, mainly those of electrostatic nature, seem to control the permeation across the algal capsules of spin labels group B, showing that structures which are similar to amino acids could diffuse across the interior of the algal cell. (author)
4. An MRI study of symptomatic adhesive capsulitis.
Science.gov (United States)
Zhao, Wen; Zheng, Xiaofeng; Liu, Yuying; Yang, Wenlu; Amirbekian, Vardan; Diaz, Luis E; Huang, Xudong
2012-01-01
Appilication of MR imaging to diagnose Adhesive Capsulitis (AC) has previously been described. However, there is insufficient information available for the MRI analysis of AC. This study is to describe and evaluate the pathomorphology of the shoulder in Asian patients with AC compared to healthy volunteers. 60 Asian patients with clinically diagnosed AC and 60 healthy volunteers without frozen shoulder underwent MRI of the shoulder joint. All subjects who were age- and sex-matched control ones underwent routine MRI scans of the affected shoulder, including axial, oblique coronal, oblique sagittal T1WI SE and coronal oblique T2WI FSE sequences. Significant abnormal findings were observed on MRI, especially at the rotator cuff interval. The coracohumeral ligament (CHL), articular capsule thickness in the rotator cuff interval as well as the fat space under coracoid process were evaluated. MRI showed that patients with adhesive capsulitis had a significantly thickened coracohumeral ligament and articular capsule in the rotator cuff interval compared to the control subjects (4.2 vs. 2.4 mm, 7.2 vs. 4.4 mm; padhesive capsulitis compared with control subjects (73% vs. 13%, 26% vs. 1.6%; padhesive capsulitis than in control subjects. With regards to the inter-observer variability, two MR radiologists had an excellent kappa value of 0.86. MRI can be used to show characteristic findings in diagnosing AC. Thickening of the CHL and the capsule at the rotator cuff interval and complete obliteration of the fat triangle under the coracoid process have been shown to be the most characteristic MR findings seen with AC.
5. An MRI study of symptomatic adhesive capsulitis.
Directory of Open Access Journals (Sweden)
Wen Zhao
Full Text Available BACKGROUND: Appilication of MR imaging to diagnose Adhesive Capsulitis (AC has previously been described. However, there is insufficient information available for the MRI analysis of AC. This study is to describe and evaluate the pathomorphology of the shoulder in Asian patients with AC compared to healthy volunteers. METHODOLOGY/PRINCIPAL FINDINGS: 60 Asian patients with clinically diagnosed AC and 60 healthy volunteers without frozen shoulder underwent MRI of the shoulder joint. All subjects who were age- and sex-matched control ones underwent routine MRI scans of the affected shoulder, including axial, oblique coronal, oblique sagittal T1WI SE and coronal oblique T2WI FSE sequences. Significant abnormal findings were observed on MRI, especially at the rotator cuff interval. The coracohumeral ligament (CHL, articular capsule thickness in the rotator cuff interval as well as the fat space under coracoid process were evaluated. MRI showed that patients with adhesive capsulitis had a significantly thickened coracohumeral ligament and articular capsule in the rotator cuff interval compared to the control subjects (4.2 vs. 2.4 mm, 7.2 vs. 4.4 mm; p<0.05. Partial or complete obliteration of the subcoracoid fat triangle was significantly more frequent in patients with adhesive capsulitis compared with control subjects (73% vs. 13%, 26% vs. 1.6%; p<0.001. Synovitis-like abnormality around the long biceps tendon was significantly more common in patients with adhesive capsulitis than in control subjects. With regards to the inter-observer variability, two MR radiologists had an excellent kappa value of 0.86. CONCLUSIONS/SIGNIFICANCE: MRI can be used to show characteristic findings in diagnosing AC. Thickening of the CHL and the capsule at the rotator cuff interval and complete obliteration of the fat triangle under the coracoid process have been shown to be the most characteristic MR findings seen with AC.
6. Influence of gate width on gate-channel carrier mobility in AlGaN/GaN heterostructure field-effect transistors
Science.gov (United States)
Yang, Ming; Ji, Qizheng; Gao, Zhiliang; Zhang, Shufeng; Lin, Zhaojun; Yuan, Yafei; Song, Bo; Mei, Gaofeng; Lu, Ziwei; He, Jihao
2017-11-01
For the fabricated AlGaN/GaN heterostructure field-effect transistors (HFETs) with different gate widths, the gate-channel carrier mobility is experimentally obtained from the measured current-voltage and capacitance-voltage curves. Under each gate voltage, the mobility gets lower with gate width increasing. Analysis shows that the phenomenon results from the polarization Coulomb field (PCF) scattering, which originates from the irregularly distributed polarization charges at the AlGaN/GaN interface. The device with a larger gate width is with a larger PCF scattering potential and a stronger PCF scattering intensity. As a function of gate width, PCF scattering potential shows a same trend with the mobility variation. And the theoretically calculated mobility values fits well with the experimentally obtained values. Varying gate widths will be a new perspective for the improvement of device characteristics by modulating the gate-channel carrier mobility.
7. Line width of Josephson flux flow oscillators
DEFF Research Database (Denmark)
Koshelets, V.P.; Dmitriev, P.N.; Sobolev, A.S.
2002-01-01
spacing of about 20 nV and extremely low differential resistance, recently observed in the IVC of the standard rectangular geometry. The obtained results have been compared with existing theories and FFO models in order to understand and possibly eliminate excess noise in the FFO. The intrinsic line width...... increases considerably at voltages above the boundary voltage because of the abrupt increase of the internal damping due to Josephson self-coupling. The influence of FFO parameters, in particular the differential resistances associated both with the bias current and with the applied magnetic field...
8. Integration of Low-Power ASIC and MEMS Sensors for Monitoring Gastrointestinal Tract Using a Wireless Capsule System.
Science.gov (United States)
Arefin, Md Shamsul; Redoute, Jean-Michel; Yuce, Mehmet Rasit
2018-01-01
This paper presents a wireless capsule microsystem to detect and monitor the pH, pressure, and temperature of the gastrointestinal tract in real time. This research contributes to the integration of sensors (microfabricated capacitive pH, capacitive pressure, and resistive temperature sensors), frequency modulation and pulse width modulation based interface IC circuits, microcontroller, and transceiver with meandered conformal antenna for the development of a capsule system. The challenges associated with the system miniaturization, higher sensitivity and resolution of sensors, and lower power consumption of interface circuits are addressed. The layout, PCB design, and packaging of a miniaturized wireless capsule, having diameter of 13 mm and length of 28 mm, have successfully been implemented. A data receiver and recorder system is also designed to receive physiological data from the wireless capsule and to send it to a computer for real-time display and recording. Experiments are performed in vitro using a stomach model and minced pork as tissue simulating material. The real-time measurements also validate the suitability of sensors, interface circuits, and meandered antenna for wireless capsule applications.
9. Scaling effects in spiral capsule robots.
Science.gov (United States)
Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan
2017-04-01
Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10 -5 to 10 -2 m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.
10. Video capsule endoscopy of the small bowel.
Science.gov (United States)
Eliakim, Rami
2013-03-01
Small bowel capsule endoscopy (SBCE) was introduced 13 years ago by Given Imaging (Yokneam, Israel). It has become one of the most important investigational tools of the small bowel. The capsule is swallowed with water after a 12 h fast, propelled via peristalsis through the gastrointestinal tract and excreted naturally. A nonvideo patency capsule was developed to confirm functional patency of the gastrointestinal tract. Four additional companies have introduced competitive small bowel video capsules, some of which are Food and Drug Admistration (FDA) approved. Due to the easiness of the procedure, SBCE has become a first-line tool to detect small bowel abnormalities. The main indications for SBCE include obscure gastrointestinal bleeding, suspected Crohn's disease, small bowel tumors and practically any abnormal small bowel imaging. New indications are emerging like small bowel motility and monitoring of drug therapy and mucosal healing. The present review will describe the available capsules in the market, the procedure itself, present indications and future expectations. It will focus on the PillCam SB of Given Imaging as it is the one on which most of the literature is written. Over the past 10 years, SBCE has become a routine, first-line investigational tool of many small bowel pathologies.
11. Pulse width modulation inverter with battery charger
Science.gov (United States)
Slicker, James M. (Inventor)
1985-01-01
An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a flyback DC-DC converter circuit for recharging the battery.
12. Production of 131I gelatin capsules
International Nuclear Information System (INIS)
Freud, A.; Hirshfeld, N.; Canfi, A.; Melamud, Y.
1997-01-01
Radioiodine ( 131 I) hard-gelatin capsules are widely used for the diagnosis and treatment of various thyroid disorders. Until 1980 radioiodine was supplied by us as a liquid dosage. This proved to be a rather inconvenient form since it resulted in inaccurate dosing by the physicians and caused frequent contamination of the patients and the hospital personnel. In an attempt to overcome these problems we have designed and constructed a production facility for capsules in which 1311 is packaged. Because of the extreme precautions necessary in handling radioactive compounds, encapsulation of radioactive materials requires specifically designed production techniques, special instrumentation and unique quality control procedures that are not encountered in the standard capsule production processes in the pharmaceutical industry
13. Chord length distribution for a compound capsule
International Nuclear Information System (INIS)
Pitřík, Pavel
2017-01-01
Chord length distribution is a factor important in the calculation of ionisation chamber responses. This article describes Monte Carlo calculations of the chord length distribution for a non-convex compound capsule. A Monte Carlo code was set up for generation of random chords and calculation of their lengths based on the input number of generations and cavity dimensions. The code was written in JavaScript and can be executed in the majority of HTML viewers. The plot of occurrence of cords of different lengths has 3 peaks. It was found that the compound capsule cavity cannot be simply replaced with a spherical cavity of a triangular design. Furthermore, the compound capsule cavity is directionally dependent, which must be taken into account in calculations involving non-isotropic fields of primary particles in the beam, unless equilibrium of the secondary charged particles is attained. (orig.)
14. Capsule endoscopy—A mechatronics perspective
Science.gov (United States)
Lin, Lin; Rasouli, Mahdi; Kencana, Andy Prima; Tan, Su Lim; Wong, Kai Juan; Ho, Khek Yu; Phee, Soo Jay
2011-03-01
The recent advances in integrated circuit technology, wireless communication, and sensor technology have opened the door for development of miniature medical devices that can be used for enhanced monitoring and treatment of medical conditions. Wireless capsule endoscopy is one of such medical devices that has gained significant attention during the past few years. It is envisaged that future wireless capsule endoscopies replace traditional endoscopy procedures by providing advanced functionalities such as active locomotion, body fluid/tissue sampling, and drug delivery. Development of energy-efficient miniaturized actuation mechanisms is a key step toward achieving this goal. Here, we review some of the actuators that could be integrated into future wireless capsules and discuss the existing challenges.
15. Endoscopic placement of the small-bowel video capsule by using a capsule endoscope delivery device.
Science.gov (United States)
Holden, Jeremy P; Dureja, Parul; Pfau, Patrick R; Schwartz, Darren C; Reichelderfer, Mark; Judd, Robert H; Danko, Istvan; Iyer, Lalitha V; Gopal, Deepak V
2007-05-01
Capsule endoscopy performed via the traditional peroral route is technically challenging in patients with dysphagia, gastroparesis, and/or abnormal upper-GI (UGI) anatomy. To describe the indications and outcomes of cases in which the AdvanCE capsule endoscope delivery device, which has recently been cleared by the Food and Drug Administration, was used. Retrospective, descriptive, case series. Tertiary care, university hospital. We report a case series of 16 consecutive patients in whom the AdvanCE delivery device was used. The study period was May 2005 through July 2006. Endoscopic delivery of the video capsule to the proximal small bowel by using the AdvanCE delivery device. Indications, technique, and completeness of small bowel imaging in patients who underwent endoscopic video capsule delivery. The AdvanCE delivery device was used in 16 patients ranging in age from 3 to 74 years. The primary indications for endoscopic delivery included inability to swallow the capsule (10), altered UGI anatomy (4), and gastroparesis (2). Of the 4 patients with altered UGI anatomy, 3 had dual intestinal loop anatomy (ie, Bilroth-II procedure, Whipple surgery, Roux-en-Y gastric bypass) and 1 had a failed Nissen fundoplication. In all cases, the capsule was easily deployed without complication, and complete small intestinal imaging was achieved. Small patient size. Endoscopic placement of the Given PillCam by use of the AdvanCE delivery device was safe and easily performed in patients for whom capsule endoscopy would otherwise have been contraindicated or technically challenging.
16. Capsule storage and density-analog techniques
International Nuclear Information System (INIS)
Paxton, H.C.
1975-05-01
Density-analog schemes for describing critical arrays of fissile units have a long history. They originated as methods for generalizing results of subcritical measurements on weapon capsules. Such measurements were needed to establish reasonably efficient rules for capsule storage. Although specific density-analog models have been improved throughout the years, they are now largely replaced by comprehensive tabulations of critical-lattice parameters. Certain simplified forms are still useful as convenient formulas for extrapolation or for gross sorting of safety features. (U.S.)
17. Adhesive capsulitis: review of imaging and treatment.
Science.gov (United States)
Harris, Guy; Bou-Haidar, Pascal; Harris, Craig
2013-12-01
Adhesive capsulitis is one of the most common conditions affecting the shoulder; however, early clinical diagnosis can be challenging. Treatment is most effective when commenced prior to the onset of capsular thickening and contracture; consequently, the role of imaging is increasing. The aim of this review is to demonstrate the typical imaging appearances of adhesive capsulitis and to examine some of the evidence regarding each of these imaging modalities. An evaluation of the various management options available to the clinician is also presented. © 2013 The Royal Australian and New Zealand College of Radiologists.
18. Treatment of adhesive capsulitis: a review
Science.gov (United States)
D’Orsi, Giovanni Maria; Via, Alessio Giai; Frizziero, Antonio; Oliva, Francesco
2012-01-01
Summary Adhesive capsulitis is a condition “difficult to define, difficult to treat and difficult to explain from the point of view of pathology”. This Codman’s assertion is still actual because of a variable nomenclature, an inconsistent reporting of disease staging and many types of treatment. There is no consensus on how the best way best to manage patients with this condition, so we want to provide an evidence-based overview regarding the effectiveness of conservative and surgical interventions to treat adhesive capsulitis. PMID:23738277
19. Lake Basin Fetch and Maximum Length/Width
Data.gov (United States)
Minnesota Department of Natural Resources — Linear features representing the Fetch, Maximum Length and Maximum Width of a lake basin. Fetch, maximum length and average width are calcuated from the lake polygon...
20. Direct measurement of the W boson width
Energy Technology Data Exchange (ETDEWEB)
Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Alberta U. /Simon Fraser U. /McGill U.; Ahsan, M.; /Kansas State U.; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP; Alton, A.; /Michigan U. /Northeastern U.
2009-09-01
We present a direct measurement of the width of the W boson using the shape of the transverse mass distribution of W {yields} e{nu} candidates selected in 1 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider in p{bar p} collisions at {radical}s = 1.96 TeV. We use the same methods and data sample that were used for our recently published W boson mass measurement, except for the modeling of the recoil, which is done with a new method based on a recoil library. Our result, 2.028 {+-} 0.072 GeV, is in agreement with the predictions of the standard model and is the most precise direct measurement result from a single experiment to date.
1. Political polarization
OpenAIRE
Dixit, Avinash K.; Weibull, Jörgen W.
2007-01-01
Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.
2. Political polarization.
Science.gov (United States)
Dixit, Avinash K; Weibull, Jörgen W
2007-05-01
Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.
3. Isolation of Capsulate Bacteria from Acute Dentoalveolar Abscesses
OpenAIRE
Lewis, M. A. O.; Milligan, S. G.; MacFarlane, T. W.; Carmichael, F. A.
2011-01-01
The presence of a capsule was determined for 198 bacterial strains (57 facultative anaerobes, 141 strict anaerobes) isobdted from pus samples aspirated from 40 acute dentoalveolar abscesses. A total of 133 (67 per cent) of the isolates (42 facultative anaerobes, 91 strict anaerobes) were found to have a capsule. Possession ofa capsule may in part explain the apparent pathogenicity of the bacterial species encountered in acute dentoalveolar abscess.Keywords - Bacterial capsule; Acute dentoalve...
4. Characterizing graphs of maximum matching width at most 2
DEFF Research Database (Denmark)
Jeong, Jisu; Ok, Seongmin; Suh, Geewon
2017-01-01
The maximum matching width is a width-parameter that is de ned on a branch-decomposition over the vertex set of a graph. The size of a maximum matching in the bipartite graph is used as a cut-function. In this paper, we characterize the graphs of maximum matching width at most 2 using the minor...
5. GAP WIDTH STUDY IN LASER BUTT-WELDING
DEFF Research Database (Denmark)
Gong, Hui; Olsen, Flemming Ove
In this paper the maximum allowable gap width in laser butt-welding is intensively studied. The gap width study (GWS) is performed on the material of SST of W1.4401 (AISI 316) under various welding conditions, which are the gap width : 0.00-0.50 mm, the welding speed : 0.5-2.0 m/min, the laser...
6. Ultrasound capsule endoscopy: sounding out the future.
Science.gov (United States)
Cox, Benjamin F; Stewart, Fraser; Lay, Holly; Cummins, Gerard; Newton, Ian P; Desmulliez, Marc P Y; Steele, Robert J C; Näthke, Inke; Cochran, Sandy
2017-05-01
Video capsule endoscopy (VCE) has been of immense benefit in the diagnosis and management of gastrointestinal (GI) disorders since its introduction in 2001. However, it suffers from a number of well recognized deficiencies. Amongst these is the limited capability of white light imaging, which is restricted to analysis of the mucosal surface. Current capsule endoscopes are dependent on visual manifestation of disease and limited in regards to transmural imaging and detection of deeper pathology. Ultrasound capsule endoscopy (USCE) has the potential to overcome surface only imaging and provide transmural scans of the GI tract. The integration of high frequency microultrasound (µUS) into capsule endoscopy would allow high resolution transmural images and provide a means of both qualitative and quantitative assessment of the bowel wall. Quantitative ultrasound (QUS) can provide data in an objective and measurable manner, potentially reducing lengthy interpretation times by incorporation into an automated diagnostic process. The research described here is focused on the development of USCE and other complementary diagnostic and therapeutic modalities. Presently investigations have entered a preclinical phase with laboratory investigations running concurrently.
7. Calcitonin effects on shoulder adhesive capsulitis.
Science.gov (United States)
Rouhani, Alireza; Mardani-Kivi, Mohsen; Bazavar, Mohammadreza; Barzgar, Mahmood; Tabrizi, Ali; Hashemi-Motlagh, Keyvan; Saheb-Ekhtiari, Khashayar
2016-08-01
Adhesive capsulitis (frozen shoulder) is a relatively prevalent disease of shoulder and affects soft tissue of glenohumeral joint. Signs include painful restricted motion and disability of the patient in daily activities. Calcitonin is a thyroid hormone, and its effectiveness has been demonstrated in painful conditions. The presents study aims to evaluate the effect of calcitonin in treating shoulder adhesive capsulitis. This double-blinded randomized clinical trial was conducted on 64 patients suffering from shoulder adhesive capsulitis. The intervention and control groups were given intranasal calcitonin and placebo for 6 weeks, respectively. For both groups, physiotherapy and non-steroidal anti-inflammatory drugs were administered correspondingly. The patients were evaluated pre- and post-treatment for shoulder pain and shoulder range of motion (ROM). Shoulder functional outcome (secondary outcome) was evaluated using Disability of Arm, Shoulder, and Hand, Shoulder Pain and Disability Index, and Health Assessment Questionnaire disability criteria. The mean age of patients in calcitonin and control group was 52.4 ± 4.6 and 53.2 ± 4.9, respectively. Demographic characteristics and pre-treatment scores were similar in both groups (all P > 0.05). In post-treatment follow-up, shoulder pain, ROM, and the patients' functional scores were significantly improved in both groups (P adhesive capsulitis with regard to the efficiency in alleviating pain and improving functional outcome. II.
8. Diagnosis and management of adhesive capsulitis
OpenAIRE
Manske, Robert C.; Prohaska, Daniel
2008-01-01
Adhesive capsulitis is a musculoskeletal condition that has a disabling capability. This review discusses the diagnosis and both operative and nonoperative management of this shoulder condition that causes significant morbidity. Issues related to medications, rehabilitation, and post surgical considerations are discussed.
9. Design of Endoscopic Capsule With Multiple Cameras.
Science.gov (United States)
Gu, Yingke; Xie, Xiang; Li, Guolin; Sun, Tianjia; Wang, Dan; Yin, Zheng; Zhang, Pengfei; Wang, Zhihua
2015-08-01
In order to reduce the miss rate of the wireless capsule endoscopy, in this paper, we propose a new system of the endoscopic capsule with multiple cameras. A master-slave architecture, including an efficient bus architecture and a four level clock management architecture, is applied for the Multiple Cameras Endoscopic Capsule (MCEC). For covering more area of the gastrointestinal tract wall with low power, multiple cameras with a smart image capture strategy, including movement sensitive control and camera selection, are used in the MCEC. To reduce the data transfer bandwidth and power consumption to prolong the MCEC's working life, a low complexity image compressor with PSNR 40.7 dB and compression rate 86% is implemented. A chipset is designed and implemented for the MCEC and a six cameras endoscopic capsule prototype is implemented by using the chipset. With the smart image capture strategy, the coverage rate of the MCEC prototype can achieve 98% and its power consumption is only about 7.1 mW.
10. Capsule Endoscopy: New Technology, Old Complication ...
African Journals Online (AJOL)
Wireless capsule endoscopy is a new tool in the armamentarium of the gastroenterologist to evaluate the small bowel non-invasively. It allows improved diagnostic yield with low complication rates relative to traditional modalities. But this new technology has its own set of complications, some which can lead to significant ...
11. Wireless capsule endoscopy: perspectives beyond gastrointestinal bleeding.
Science.gov (United States)
Redondo-Cerezo, Eduardo; Sánchez-Capilla, Antonio Damián; De La Torre-Rubio, Paloma; De Teresa, Javier
2014-11-14
Wireless capsule endoscopy (CE) is a technology developed for the endoscopic exploration of the small bowel. The first capsule model was approved by the Food and Drug Administration in 2001, and its first and essential indication was occult gastrointestinal (GI) bleeding. Over subsequent years, this technology has been refined to provide superior resolution, increased battery life, and capabilities to view different parts of the GI tract. Indeed, cases for which CE proved useful have increased significantly over the last few years, with new indications for the small bowel and technical improvements that have expanded its use to other parts of the GI tract, including the esophagus and colon. The main challenges in the development of CE are new devices with the ability to provide therapy, air inflation for a better vision of the small bowel, biopsy sampling systems attached to the capsule and the possibility to guide and move the capsule with an external motion control. In this article we review the current and new indications of CE, and the evolving technological changes shaping this technology, which has a promising potential in the coming future of gastroenterology.
12. Hardware image assessment for wireless endoscopy capsules.
Science.gov (United States)
Khorsandi, M A; Karimi, N; Samavi, S; Hajabdollahi, M; Soroushmehr, S M R; Ward, K; Najarian, K
2016-08-01
Wireless capsule endoscopy is a new technology in the realm of telemedicine that has many advantages over the traditional endoscopy systems. Transmitted images should help diagnosis of diseases of the gastrointestinal tract. Two important technical challenges for the manufacturers of these capsules are power consumption and size of the circuitry. Also, the system must be fast enough for real-time processing of image or video data. To solve this problem, many hardware designs have been proposed for implementation of the image processing unit. In this paper we propose an architecture that could be used for the assessment of endoscopy images. The assessment allows avoidance of transmission of medically useless images. Hence, volume of data is reduced for more efficient transmission of images by the endoscopy capsule. This is done by color space conversion and moment calculation of images captured by the capsule. The inputs of the proposed architecture are RGB image frames and the outputs are images with converted colors and calculated image moments. Experimental results indicate that the proposed architecture has low complexity and is appropriate for a real-time application.
13. Wireless Capsule Enteroscopy in Healthy Volunteers.
Science.gov (United States)
Tachecí, Ilja; Bradna, Petr; Douda, Tomáš; Baštecká, Drahomíra; Kopáčová, Marcela; Rejchrt, Stanislav; Lutonský, Martin; Soukup, Tomáš; Bureš, Jan
The aim of our prospective study was to define endoscopy appearance of the small bowel in healthy volunteers. Forty-two healthy volunteers underwent wireless capsule endoscopy, clinical investigation, laboratory tests, and completed a health-status questionnaire. All subjects were available for a 36-month clinical follow-up. Eleven subjects (26%) had fully normal endoscopy findings. Remaining 31 persons (74%), being asymptomatic, with normal laboratory results, had some minor findings at wireless capsule endoscopy. Most of those heterogeneous findings were detected in the small intestine (27/31; 87%), like erosions and/or multiple red spots, diminutive polyps and tiny vascular lesions. During a 36-month clinical follow-up, all these 42 healthy volunteers remained asymptomatic, with fully normal laboratory control. Significant part of healthy subjects had abnormal findings at wireless capsule endoscopy. These findings had no clinical relevance, as all these persons remained fully asymptomatic during a 36-month follow-up. Such an endoscopic appearance would be previously evaluated as "pathological". This is a principal report alerting that all findings of any control group of wireless capsule endoscopic studies must be evaluated with caution.
14. Wireless Capsule Enteroscopy in Healthy Volunteers
Directory of Open Access Journals (Sweden)
Ilja Tachecí
2016-09-01
Full Text Available Introduction: The aim of our prospective study was to define endoscopy appearance of the small bowel in healthy volunteers. Method: Forty-two healthy volunteers underwent wireless capsule endoscopy, clinical investigation, laboratory tests, and completed a health-status questionnaire. All subjects were available for a 36-month clinical follow-up. Results: Eleven subjects (26% had fully normal endoscopy findings. Remaining 31 persons (74%, being asymptomatic, with normal laboratory results, had some minor findings at wireless capsule endoscopy. Most of those heterogeneous findings were detected in the small intestine (27/31; 87%, like erosions and/or multiple red spots, diminutive polyps and tiny vascular lesions. During a 36-month clinical follow-up, all these 42 healthy volunteers remained asymptomatic, with fully normal laboratory control. Conclusions: Significant part of healthy subjects had abnormal findings at wireless capsule endoscopy. These findings had no clinical relevance, as all these persons remained fully asymptomatic during a 36-month follow-up. Such an endoscopic appearance would be previously evaluated as “pathological”. This is a principal report alerting that all findings of any control group of wireless capsule endoscopic studies must be evaluated with caution.
15. Can we reduce capsule endoscopy reading times?
NARCIS (Netherlands)
Westerhof, Jessie; Koornstra, Jan J.; Weersma, Rinse K.
Background: Analyzing small-bowel capsule endoscopy (CE) images is time Consuming. Objective: To determine the effect of reducing the number Of images on reacting time and interpretation of CE procedures. Design: Two techniques aimed at reducing the number of images to he viewed were Studied. The
16. Biosorption of lead by Gram-ve capsulated and non-capsulated ...
African Journals Online (AJOL)
Citrobacter freundii ) or capsulated (Klebsiella pneumoniae) was characterised. Lead biosorption was found to be influenced by the pH of the solution, initial metal concentration, and amount of the dried powdered cells and contact time. Thus, the ...
17. Is there an application for wireless capsule endoscopy in horses?
Science.gov (United States)
Montgomery, Julia B; Bracamonte, Jose L; Alam, Mohammad Wajih; Khan, Alimul H; Mohammed, Shahed K; Wahid, Khan A
2017-12-01
This pilot study assessed wireless capsule endoscopy in horses. Image transmission was achieved with good image quality. Time to exit the stomach was variable and identified as one limitation, together with gaps in image transmission, capsule tumbling, and inability to accurately locate the capsule. Findings demonstrate usefulness and current limitations.
18. 21 CFR 872.3110 - Dental amalgam capsule.
Science.gov (United States)
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental amalgam capsule. 872.3110 Section 872.3110...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3110 Dental amalgam capsule. (a) Identification. A dental amalgam capsule is a container device in which silver alloy is intended to be mixed with mercury...
19. Global synchronization of parallel processors using clock pulse width modulation
Science.gov (United States)
Chen, Dong; Ellavsky, Matthew R.; Franke, Ross L.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Jeanson, Mark J.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Littrell, Daniel; Ohmacht, Martin; Reed, Don D.; Schenck, Brandon E.; Swetz, Richard A.
2013-04-02
A circuit generates a global clock signal with a pulse width modification to synchronize processors in a parallel computing system. The circuit may include a hardware module and a clock splitter. The hardware module may generate a clock signal and performs a pulse width modification on the clock signal. The pulse width modification changes a pulse width within a clock period in the clock signal. The clock splitter may distribute the pulse width modified clock signal to a plurality of processors in the parallel computing system.
20. Narrow-width mechanism of a=5 Ξ-state
International Nuclear Information System (INIS)
Kumagai-Fuse, I.; Akaishi, Y.
1995-04-01
Narrow-width mechanism of ≡ 5 H is discussed by calculating conversion widths to all its possible decay channels. Since the conversion processes have small reaction Q values, the three- and four- body decays are strongly suppressed owing to small phase volumes available. Decay widths to the two-body channels are significantly reduced by the distortion of emitted-particle waves. This mechanism brings about a narrow width of ≡ 5 H. The total width is estimated to be 0.87 MeV, in which the largest contribution comes from the decay into the Λ 4 H * +Λ channel. (author)
1. Beam-width spreading of vortex beams in free space
Science.gov (United States)
Wang, Weiwei; Li, Jinhong; Duan, Meiling
2018-01-01
Based on the extended Huygens-Fresnel principle and the definition of second-order moments of the Wigner distribution function, the analytical expression for the beam-width spreading of Gaussian Schell-model (GSM) vortex beams in free space are derived, and used to study the influence of beam parameters on the beam-width spreading of GSM vortex beams. With the increment of the propagation distance, the beam-width spreading of GSM vortex beams will increase; the bigger the topological charge, spatial correlation length, wavelength and waist width are, the smaller the beam-width spreading is.
2. Utility of MR arthrography in the diagnosis of adhesive capsulitis
Energy Technology Data Exchange (ETDEWEB)
Manton, G.L.; Schweitzer, M.E.; Weishaupt, D.; Karasick, D. [Dept. of Radiology, Thomas Jefferson Univ. Hospital, Philadelphia, PA (United States)
2001-06-01
Objective. Arthrographically, adhesive capsulitis is characterized by decreased joint volume; histologically, the capsule and synovium are thickened. We therefore compared using MR arthrography the joint volumes and capsule/synovial thickness of patients with and without adhesive capsulitis in order to assess the utility of MR arthrography in diagnosing adhesive capsulitis.Design and patients. The 1.5 T MR arthrography images of 28 subjects with (n=9) and without (n=19) adhesive capsulitis were compared. Adhe- sive capsulitis was diagnosed when there was an injected glenohumeral joint volume of less than 10 ml. Two masked observers working in consensus assessed the images for the relative amount of fluid in the biceps tendon sheath and axillary recess, corrugation at the margin of the capsule, capsule/synovial thickness, abnormalities of the rotator interval capsule, and for the presence of a cuff tear.Results. There was a trend towards differences in capsular and synovial thickness (P>0.07) between the subjects with and without adhesive capsulitis; however, the controls had thicker synovium/capsules. Surprisingly, the amount of fluid in the axillary recess and biceps tendon sheath was not significantly different between the groups (P>0.25). There were more tears of the rotator cuff in controls than in patients with adhesive capsulitis (6, 3 vs 1, 1: complete, partial). Also, both corrugation (7 vs 0) and interval abnormalities (7 vs 0) were more common in the controls.Conclusion. There appear to be no useful MR arthrographic signs of adhesive capsulitis. Capsular/synovial thickness, static fluid volume, and the presence of corrugation are inconclusive as MR arthrographic signs for distinguishing shoulders with adhesive capsulitis from those without. (orig.)
3. A wireless capsule endoscopy steering mechanism using magnetic field platform.
Science.gov (United States)
Alsunaydih, Fahad N; Redoute, Jean-Michel; Yuce, Mehmet R
2017-07-01
In this paper, a new steering mechanism for wireless capsule devices is presented. The proposed system consists of a platform generating a magnetic field to direct and control the motion of a capsule. The platform contains an upper and a lower set of electromagnets. A permanent magnet is implanted inside the capsule to initiate the movement, which is set by the magnetic field delivered by the electromagnets. The total magnetic field at the capsule's location is the sum of the contributions of each electromagnet. An experimental setup has been designed for testing and comparing between the performance of the capsule mobility in practice and simulations.
4. Symptomatic Patency Capsule Retention in Suspected Crohn's Disease
DEFF Research Database (Denmark)
Rasmussen, Bjørn; Nathan, Torben; Jensen, Michael Dam
2016-01-01
The main limitation of capsule endoscopy is the risk of capsule retention. In patients with suspected Crohn's disease, however, this complication is rare, and if a small bowel stenosis is not reliably excluded, small bowel patency can be confirmed with the Pillcam patency capsule. We present two...... patients examined for suspected Crohn's disease who experienced significant symptoms from a retained patency capsule. Both patients had Crohn's disease located in the terminal ileum. In one patient, the patency capsule caused abdominal pain and vomiting and was visualized at magnetic resonance enterography...
5. Interfacial Widths of Conjugated Polymer Bilayers
Energy Technology Data Exchange (ETDEWEB)
NCSU; UC Berkeley; UCSB; Advanced Light Source; Garcia, Andres; Yan, Hongping; Sohn, Karen E.; Hexemer, Alexander; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Kramer, Edward J.; Ade, Harald
2009-08-13
The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.
6. Wireless capsule endoscopy years after Michelassi stricturoplasty for Crohn's disease.
Science.gov (United States)
Sciaudone, G; Pellino, G; Guadagni, I; Pezzullo, A; Selvaggi, F
2010-01-01
The use of wireless capsule endoscopy in Crohn's disease has been a matter of debate. We report the case of a 27-year-old woman operated for Crohn's disease with a Michelassi stricturoplasty presenting with anaemia. We tested the patient with a patency capsule before undertaking a wireless capsule endoscopy. Although the absorbable capsule was successfully expelled, the wireless capsule was retained next to the distal edge of the Michelassi stricturoplasty, where it revealed an otherwise undetected stenotic recurrence. We successfully treated the recurrence with a Heineke-Mikulicz stricturoplasty on the stenotic outlet of the previous Michelassi, extracting the capsule. We found our treatment effective. We believe that capsule endoscopy can be performed in patients operated on for Crohn's disease, although further studies are needed to clarify its role in patients with long-stricturoplasties and to establish which examination could be the most effective in selecting patients.
7. Adhesive capsulitis of the hip: a review.
Science.gov (United States)
Looney, Colin G; Raynor, Brett; Lowe, Rebecca
2013-12-01
Adhesive capsulitis of the hip (ACH) is a rare clinical entity. Similar to adhesive capsulitis of the shoulder, ACH is characterized by a painful decrease in active and passive range of motion as synovial inflammation in the acute stages of the disease progresses to capsular fibrosis in the chronic stages. Once other diagnoses have been ruled out, management of ACH is tailored to reduce inflammation in the acute stages with NSAIDs, intra-articular steroid injections, and targeted physical therapy while biomechanical dysfunction in the spine, hip, sacroiliac joint, or lower limb joints is addressed. In chronic stages of the disease, intervention should focus on decreasing the progression of fibrotic changes and regaining range of motion through aggressive physical therapy. Interventions described for chronic ACH include manipulation under anesthesia; pressure dilatation; and open or arthroscopic synovectomy, lysis of adhesions, and capsular release. Surgical intervention should be considered only after failure of a minimum 3-month course of nonsurgical treatment.
8. Polymeric multilayer capsules in drug delivery.
Science.gov (United States)
De Cock, Liesbeth J; De Koker, Stefaan; De Geest, Bruno G; Grooten, Johan; Vervaet, Chris; Remon, Jean Paul; Sukhorukov, Gleb B; Antipina, Maria N
2010-09-17
Recent advances in medicine and biotechnology have prompted the need to develop nanoengineered delivery systems that can encapsulate a wide variety of novel therapeutics such as proteins, chemotherapeutics, and nucleic acids. Moreover, these delivery systems should be "intelligent", such that they can deliver their payload at a well-defined time, place, or after a specific stimulus. Polymeric multilayer capsules, made by layer-by-layer (LbL) coating of a sacrificial template followed by dissolution of the template, allow the design of microcapsules in aqueous conditions by using simple building blocks and assembly procedures, and provide a previously unmet control over the functionality of the microcapsules. Polymeric multilayer capsules have recently received increased interest from the life science community, and many interesting systems have appeared in the literature with biodegradable components and biospecific functionalities. In this Review we give an overview of the recent breakthroughs in their application for drug delivery.
9. Technology of swallowable capsule for medical applications
OpenAIRE
Intzes, I; Meng, H; Cosmas, J
2014-01-01
Medical technology has undergone major breakthroughs in recent years, especially in the area of the examination tools for diagnostic purposes. This paper reviews the swallowable capsule technology in the examination of the gastrointestinal system for various diseases. The wireless camera pill has created a more advanced method than many traditional examination methods for the diagnosis of gastrointestinal diseases such as gastroscopy by the use of an endoscope. After years of great innovation...
10. Adhesive capsulitis. Is it possible in childhood?
OpenAIRE
Modesto, C. (C.); Crespo, E. (Eduardo); Villas, C. (Carlos); Aquerreta, D. (Dámaso)
1995-01-01
Adhesive capsulitis affecting shoulders has been extensively studied by orthopedic surgeons, but few reports have been published on this condition when it affects other joints (hips, ankles). To our knowledge no pediatric cases have been reported. As its treatment requires prolonged physiotherapy and sometimes manipulation, a correct diagnosis is essential. We would like to emphasize the importance of having this condition in mind when one is regarding a differential diagnosis, also in children.
11. Automatic blood detection in capsule endoscopy video
Czech Academy of Sciences Publication Activity Database
Novozámský, Adam; Flusser, Jan; Tachecí, I.; Sulík, L.; Bureš, J.; Krejcar, O.
2016-01-01
Roč. 21, č. 12 (2016), s. 1-8, č. článku 126007. ISSN 1083-3668 R&D Projects: GA ČR GA15-16928S Institutional support: RVO:67985556 Keywords : Automatic blood detection * capsule endoscopy video Subject RIV: JD - Computer Applications, Robotics Impact factor: 2.530, year: 2016 http://library.utia.cas.cz/separaty/2016/ZOI/flusser-0466936.pdf
12. Constraints on oxygen fugacity within metal capsules
Science.gov (United States)
Faul, Ulrich H.; Cline, Christopher J., II; Berry, Andrew; Jackson, Ian; Garapić, Gordana
2017-12-01
Experiments were conducted with olivine encapsulated or wrapped in five different metals (Pt, Ni, Ni_{70}Fe_{30} , Fe, and Re) to determine the oxygen fugacity in the interior of large capsules used for deformation and seismic property experiments. Temperature (1200°C ), pressure (300 MPa), and duration (24 h) were chosen to represent the most common conditions in these experiments. The oxygen fugacity was determined by analysing the Fe content of initially pure Pt particles that were mixed with the olivine powder prior to the experiments. Oxygen fugacities in the more oxidizing metal containers are substantially below their respective metal-oxide buffers, with the fO_2 of sol-gel olivine in Ni about 2.5 orders of magnitude below Ni-NiO. Analysis of olivine and metal blebs reveals three different length-, and hence diffusive time scales: (1) Fe loss to the capsule over ˜ 100 μm, (2) fO_2 gradients at the sample-capsule interface up to 2 mm into the sample, and (3) constant interior fO_2 values with an ordering corresponding to the capsule material. The inferred diffusive processes are: Fe diffusion in olivine with a diffusivity ˜ 10^{-14} m^2/s , diffusion possibly of oxygen along grain boundaries with a diffusivity ˜ 10^{-12} m^2/s , and diffusion possibly involving pre-existing defects with a diffusivity ˜ 10^{-10} m^2/s . The latter, fast adjustment to changing fO_2 may consist of a rearrangement of pre-existing defects, representing a metastable equilibrium, analogous to decoration of pre-existing defects by hydrogen. Full adjustment to the external fO_2 requires atomic diffusion.
13. Hemispherical Capsule Implosions for Fast Ignition*
Science.gov (United States)
Hanson, D. L.; Vesey, R. A.; Sinars, D. B.; Adams, R. G.; Cuneo, M. E.; Porter, J. L.; Slutz, S. A.; Johnston, R. R.; Wenger, D. F.; Schroen, D. G.
2003-10-01
The fast ignitor approach to ICF ignition separates the fuel assembly and fast heating processes. After compressing the fuel with the main driver, the fuel is ignited using a focused electron or ion beam generated by a fast, ultra-high power laser pulse. This significantly relaxes the drive symmetry, energy, and shock timing requirements compared to hot spot ignition. A hemispherical capsule target is a fast ignitor geometry well-adapted to symmetric fuel compression by a single-ended z-pinch radiation drive. The hemispherical capsule implodes radially, constrained at its equator by a flat high-density surface (a special case of the spherical capsule "cone-focus" geometry). This glide plane is mounted on a hollow pedestal that provides a plasma-free, short-pulse laser path to the compressed fuel core region. In experiments on the Z accelerator at Sandia, we are studying implosions of 2.0-mm-diameter, 60-micron-thick hemispherical capsules in cylindrical secondary hohlraums heated to 90-100 eV from one end by a 120 TW wire-array z-pinch. Analysis of ZBL 6.7 keV point-projection backlighter images of pole-hot implosions in a tall secondary and 6.18 keV monochromatic crystal backlighter images of more symmetric implosions in a short secondary will be presented. We will also discuss progress on the development of a cryogenic liquid fuel target for this fast ignitor compression geometry. * Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.
14. Hot cell examination on the surveillance capsule and HANARO capsule in IMEF
International Nuclear Information System (INIS)
Choo, Yong Sun; Oh, Wan Ho; Yoo, Byung Ok; Jung, Yang Hong; Ahn, Sang Bok; Baik, Seung Je; Song, Wung Sup; Hong, Kwon Pyo
2000-01-01
For the maintenance of integrity and safety of pressurizer of commercial power plant until its life span, it is required by US NRC 10CFR50 APP. G and H and ASTM E185-94 to periodically monitor irradiation embrittlement by neutron irradiation. In order to accomplished the requirement reactor operator has been carrying out the test by extracting the monitoring capsule embeded in reactor during the period of planned preventive maintenance. In relation to this irradiation samples are being used for prediction of reactor vessel life span and reactor vessel's adjusted reference temperature by irradiation of neutron flux enough to reach to end of life span. And also irradiation capsules with and without instrumentation are used for R and D on nuclear materials. Each capsule contains high radioactivity, therefore, post irradiation examination has to be handled by all means in the hot cell. The facility available for this purpose is Irradiated material examination facility (IMEF) to handle such works as capsule receiving, capsule cut and dismantling, sample classification, various examination, and finally development and improvement of examination equipment and instrumentation. (Hong, J. S.)
15. Effects of food on a gastrically degraded drug: azithromycin fast-dissolving gelatin capsules and HPMC capsules.
Science.gov (United States)
Curatolo, William; Liu, Ping; Johnson, Barbara A; Hausberger, Angela; Quan, Ernest; Vendola, Thomas; Vatsaraj, Neha; Foulds, George; Vincent, John; Chandra, Richa
2011-07-01
Commercial azithromycin gelatin capsules (Zithromax®) are known to be bioequivalent to commercial azithromycin tablets (Zithromax®) when dosed in the fasted state. These capsules exhibit a reduced bioavailability when dosed in the fed state, while tablets do not. This gelatin capsule negative food effect was previously proposed to be due to slow and/or delayed capsule disintegration in the fed stomach, resulting in extended exposure of the drug to gastric acid, leading to degradation to des-cladinose-azithromycin (DCA). Azithromycin gelatin capsules were formulated with "superdisintegrants" to provide fast-dissolving capsules, and HPMC capsule shells were substituted for gelatin capsule shells, in an effort to eliminate the food effect. Healthy volunteers were dosed with these dosage forms under fasted and fed conditions; pharmacokinetics were evaluated. DCA pharmacokinetics were also evaluated for the HPMC capsule subjects. In vitro disintegration of azithromycin HPMC capsules in media containing food was evaluated and compared with commercial tablets and commercial gelatin capsules. When the two fast-dissolving capsule formulations were dosed to fed subjects, the azithromycin AUC was 38.9% and 52.1% lower than after fasted-state dosing. When HPMC capsules were dosed to fed subjects, the azithromycin AUC was 65.5% lower than after fasted-state dosing. For HPMC capsules, the absolute fasting-state to fed-state decrease in azithromycin AUC (on a molar basis) was similar to the increase in DCA AUC. In vitro capsule disintegration studies revealed extended disintegration times for commercial azithromycin gelatin capsules and HPMC capsules in media containing the liquid foods milk and Ensure®. Interaction of azithromycin gelatin and HPMC capsules with food results in slowed disintegration in vitro and decreased bioavailability in vivo. Concurrent measurement of serum azithromycin and the acid-degradation product DCA demonstrates that the loss of azithromycin
16. Strategic Polarization.
Science.gov (United States)
Kalai, Adam; Kalai, Ehud
2001-08-01
In joint decision making, similarly minded people may take opposite positions. Consider the example of a marriage in which one spouse gives generously to charity while the other donates nothing. Such "polarization" may misrepresent what is, in actuality, a small discrepancy in preferences. It may be that the donating spouse would like to see 10% of their combined income go to charity each year, while the apparently frugal spouse would like to see 8% donated. A simple game-theoretic analysis suggests that the spouses will end up donating 10% and 0%, respectively. By generalizing this argument to a larger class of games, we provide strategic justification for polarization in many situations such as debates, shared living accommodations, and disciplining children. In some of these examples, an arbitrarily small disagreement in preferences leads to an arbitrarily large loss in utility for all participants. Such small disagreements may also destabilize what, from game-theoretic point of view, is a very stable equilibrium. Copyright 2001 Academic Press.
17. Recent Advances in Global Measurement and Application of River Widths
Science.gov (United States)
Pavelsky, T.; Allen, G. H.
2015-12-01
Among variables relevant to river form and discharge that can be observed from space, river width is perhaps the simplest to measure. Width can be extracted directly from optical or radar imagery, and application of remotely sensed widths to problems in hydrology, fluvial geomorphology, and ecology dates back more than two decades. Despite this long heritage, until very recently remotely sensed width measurements have largely been made on an ad-hoc basis for individual studies over relatively small regions. Global studies that required river widths have largely relied on estimates from downstream hydraulic geometry relationships with basin area, which inevitably simplify width variability and may, in practice, underestimate the fraction of wide rivers and the total river surface area in many basins. Over the last two years, multiple new regional- and global-scale, satellite-derived river width datasets have been developed that have substantially improved our global understanding of river form. These datasets include the Global Width Database for Large Rivers (GWD-LR), which provides width measurements for rivers wider than ~180 m, and all rivers wider than ~300 m, based on the SRTM water mask and the Global River Widths from Landsat (GRWL), which provides measurements for rivers as narrow as 30 m and all rivers wider than ~100 m. Several regional-scale datasets have also been developed. These datasets will facilitate improvements to regional and global scale hydrodynamic models, will provide more robust information on global river surface area for gas flux studies, and constitute novel information on global patterns of fluvial geomorphology. These datasets represent the beginning, not the end, of global river width measurements, however, as in the future multitemporal width measurements can be combined with recently developed algorithms to estimate river discharge for many rivers, globally.
18. The significance of biometric parameters in determining anterior teeth width
Directory of Open Access Journals (Sweden)
Strajnić Ljiljana
2013-01-01
Full Text Available Background/Aim. An important element of prosthetic treatment of edentulous patients is selecting the size of anterior artificial teeth that will restore the natural harmony of one’s dentolabial structure as well as the whole face. The main objective of this study was to determine the correlation between the inner canthal distance (ICD and interalar width (IAW on one side and the width of both central incisors (CIW, the width of central and lateral incisors (CLIW, the width of anterior teeth (ATW, the width between the canine cusps (CCW, which may be useful in clinical practice. Methods. A total of 89 subjects comprising 23 male and 66 female were studied. Their age ranged from 19 to 34 years with the mean of 25 years. Only the subjects with the preserved natural dentition were included in the sample. All facial and intraoral tooth measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co., Brooklyn NY, USA having a resolution of 0.1mm. Results. A moderate correlation was established between the interalar width and combined width of anterior teeth and canine cusp width (r = 0.439, r = 0.374. A low correlation was established between the inner canthal distance and the width of anterior teeth and canine cusp width (r = 0.335, r = 0.303. The differences between the two genders were highly significant for all the parameters (p < 0.01. The measured facial distances and width of anterior teeth were higher in men than in women. Conclusion. The results of this study suggest that the examined interalar width and inner canthal distance cannot be considered reliable guidelines in the selection of artificial upper anterior teeth. However, they may be used as a useful additional factor combined with other methods for objective tooth selection. The final decision should be made while working on dentures fitting models with the patient’s consent.
19. A Statistical Approach for Obtaining the Controlled Woven Fabric Width
OpenAIRE
Shaker Khubab; Umair Muhammad; Maqsood Muhammad; Nawab Yasir; Ahmad Sheraz; Rasheed Abher; Ashraf Munir; Basit Abdul
2015-01-01
A common problem faced in fabric manufacturing is the production of inconsistent fabric width on shuttleless looms in spite of the same fabric specifications. Weft-wise crimp controls the fabric width and it depends on a number of factors, including warp tension, temple type, fabric take-up pressing tension and loom working width. The aim of this study is to investigate the effect of these parameters on the fabric width produced. Taguchi’s orthogonal design was used to optimise the weaving pa...
20. A Statistical Approach for Obtaining the Controlled Woven Fabric Width
Directory of Open Access Journals (Sweden)
Shaker Khubab
2015-12-01
Full Text Available A common problem faced in fabric manufacturing is the production of inconsistent fabric width on shuttleless looms in spite of the same fabric specifications. Weft-wise crimp controls the fabric width and it depends on a number of factors, including warp tension, temple type, fabric take-up pressing tension and loom working width. The aim of this study is to investigate the effect of these parameters on the fabric width produced. Taguchi’s orthogonal design was used to optimise the weaving parameters for obtaining controlled fabric width. On the basis of signal to noise ratios, it could be concluded that controlled fabric width could be produced using medium temple type and intense take-up pressing tension at relatively lower warp tension and smaller loom working width. The analysis of variance revealed that temple needle size was the most significant factor affecting the fabric width, followed by loom working width and warp tension, whereas take-up pressing tension was least significant of all the factors investigated in the study.
1. Motion of an elastic capsule in a square microfluidic channel.
Science.gov (United States)
Kuriakose, S; Dimitrakopoulos, P
2011-07-01
In the present study we investigate computationally the steady-state motion of an elastic capsule along the centerline of a square microfluidic channel and compare it with that in a cylindrical tube. In particular, we consider a slightly over-inflated elastic capsule made of a strain-hardening membrane with comparable shearing and area-dilatation resistance. Under the conditions studied in this paper (i.e., small, moderate, and large capsules at low and moderate flow rates), the capsule motion in a square channel is similar to and thus governed by the same scaling laws with the capsule motion in a cylindrical tube, even though in the channel the cross section in the upstream portion of large capsules is nonaxisymmetric (i.e., square-like with rounded corners). When the hydrodynamic forces on the membrane increase, the capsule develops a pointed downstream edge and a flattened rear (possibly with a negative curvature) so that the restoring tension forces are increased as also happens with droplets. Membrane tensions increase significantly with the capsule size while the area near the downstream tip is the most probable to rupture when a capsule flows in a microchannel. Because the membrane tensions increase with the interfacial deformation, a suitable Landau-Levich-Derjaguin-Bretherton analysis reveals that the lubrication film thickness h for large capsules depends on both the capillary number Ca and the capsule size a; our computations determine the latter dependence to be (in dimensionless form) h ~ a(-2) for the large capsules studied in this work. For small and moderate capsule sizes a, the capsule velocity Ux and additional pressure drop ΔP+ are governed by the same scaling laws as for high-viscosity droplets. The velocity and additional pressure drop of large thick capsules also follow the dynamics of high-viscosity droplets, and are affected by the lubrication film thickness. The motion of our large thick capsules is characterized by a Ux-U ~ h ~ a(-2
2. Determination of normal maxillary transverse dimension by using intercanine width and interpalatal first molar width.
Science.gov (United States)
Banker, Alka M; Pillai, Jayasankar P; Patel, Kinjal D
2016-01-01
Malocclusion in the vertical and sagittal planes is easy to observe whereas it is difficult to diagnose malocclusion in the transverse plane. There are yet no criteria defining a normal transverse occlusion. The aim of this study was to identify a ratio that defines a normal transverse occlusion. This was a retrospective study. A total sample of 151 maxillary dental models (M = 55, F = 96) in the age range of 12-16 years were randomly selected, with 73 models in control group and 78 in the study group. All the models were mixed up and given to an operator for the measurement of intercanine width (ICW) and inter-palatal molar width (IPMW). The data were statistically analyzed using SPSS software version 16.0. Chi-square test was performed to test the statistical significance difference between the groups at p ≤ 0.05. Nearly 98.60% of normal arches were found to have an IPMW to ICW ratio of 1:1 ± 0.05. On further analysis, it was found that when IPMW ≥37.45 mm, then the case may be considered to have normal arches, and if the ratio between IPMW to ICW is 1.15:1 ± 0.05 or more and IPMW is dimension.
3. Irradiation tests of materials using HANARO instrumented capsules in 2003
International Nuclear Information System (INIS)
Joo, K. M.; Joe, M. S.; Oh, J. M.; Shin, Y. T.; Kang, Y. H.; Lim, I. C.; Hwang, S. R.
2003-01-01
The HANARO irradiation capsule system has been actively utilized for the various irradiation tests requested by users of research institutes, universities, and industries. In 2003, two instrumented capsules were designed, fabricated, and successfully irradiated at HANARO and another is under fabrication. For the evaluation of the irradiation properties of the RPV(Reactor Pressure Vessel) materials and for the development of improved evaluation technology, 02M-02K instrumented capsule was designed, fabricated, and successfully irradiated at HANARO. 02M-05U instrumented capsule was designed, fabricated, and successfully irradiated as a part of 2002 project for active utilization of HANARO. Reactor core materials were also irradiated using 02M-05U capsule. Another instrumented capsule is under design and fabrication as a part of 2003 project for active utilization of HANARO and for the development of precise temperature controlling technology
4. Capsule development and utilization for material irradiation tests
Energy Technology Data Exchange (ETDEWEB)
Kang, Young Hwan; Kim, B. G.; Joo, K. N. [and others
2000-05-01
The development program of advanced nuclear structural and fuel materials includes the in-pile tests using the instrumented capsule at HANARO. The tests were performed in the in-core test holes of CT, IR 1 and 2 and OR 4 and 5 of HANARO. Extensive efforts have also been made to establish design and manufacturing technology for the instrumented capsule and its related system, which should be compatible with the HANARO's characteristics. Since the first instrumented capsule(97M-01K) had been designed and successfully fabricated, five tests were done to support the users and provided the economic benefits to user by generating the essential in-pile information on the performance and structural integrity of materials. This paper describes the present status and future plans of these R and D activities for the development of the instrumented capsule including in-situ material property measurement capsules and nuclear fuel test capsules.
5. Changes in biomechanical properties of glenohumeral joint capsules with adhesive capsulitis by repeated capsule-preserving hydraulic distensions with saline solution and corticosteroid.
Science.gov (United States)
Koh, Eun S; Chung, Sun G; Kim, Tae Uk; Kim, Hee Chan
2012-12-01
To investigate whether capsule-preserving hydraulic distension with saline solution and corticosteroid for adhesive capsulitis induces biomechanical alterations in glenohumeral joint capsules along with clinical improvements. A case series. University outpatient clinic of physical medicine and rehabilitation. Eighteen patients with unilateral adhesive capsulitis. INTERVENTION AND MAIN OUTCOME MEASUREMENTS: Three hydraulic distensions with saline solution and corticosteroid were performed with 1-month intervals. To avoid rupturing capsules, all distensions were monitored by using real-time pressure-volume curves. Stiffness, maximal volume capacity, and pressure at the maximal volume capacity of the capsule were measured at each intervention. Clinical parameters, such as pain and range of motion, were recorded before, 3 days after, and 1 month after each distension. Stiffness decreased (47.6 ± 27.1 mm Hg/mL to 31.7 ± 18.4 mm Hg/mL to 24.2 ± 14.0 mm Hg/mL, mean SD) and maximal volume capacity increased (18.8 ± 7.3 mL to 20.5 ± 7.5 mL to 24.2 ± 7.0 mL, mean SD) significantly (P = .001 for both) at each repeated hydraulic distension. Pressure at the maximal volume capacity tended to decrease, but the decrements were not statistically significant (P = .662). The clinical parameters were significantly improved throughout and 1 month after the 3 repeat procedures (P Capsule-preserving hydraulic distension changed the biomechanical properties of the glenohumeral joint capsule, lessening the stiffness and enlarging the volume capacity. These alterations were accompanied by improved range of motion and relief of pain. Repeated capsule-preserving hydraulic distension with saline solution and corticosteroid would be useful to treat adhesive capsulitis and to evaluate the treatment results. Copyright © 2012 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
6. Capsule Shields the Function of Short Bacterial Adhesins
OpenAIRE
Schembri, Mark A.; Dalsgaard, Dorte; Klemm, Per
2004-01-01
Bacterial surface structures such as capsules and adhesins are generally regarded as important virulence factors. Here we demonstrate that capsules block the function of the self-recognizing protein antigen 43 through physical shielding. The phenomenon is not restricted to Escherichia coli but can occur in other gram-negative bacteria. Likewise, we show that other short adhesins exemplified by the AIDA-I protein are blocked by the presence of a capsule. The results support the notion that cap...
7. Regional Variation Is Present in Elbow Capsules after Injury
OpenAIRE
Germscheid, Niccole M.; Hildebrand, Kevin A.
2006-01-01
Myofibroblast numbers and α-smooth muscle actin expression are increased in anterior joint capsules of patients with posttraumatic elbow contractures. The purpose of our study was to determine whether these changes occur regionally or throughout the entire joint capsule. We hypothesized that the α-smooth muscle actin mRNA expression and the myofibroblast numbers in posterior joint capsules would be elevated in elbows obtained from patients with posttraumatic joint contractures compared with j...
8. Myofibroblast Numbers are Elevated in Human Elbow Capsules After Trauma
OpenAIRE
Hildebrand, Kevin A.; Zhang, Mei; van Snellenberg, Wistara; King, Graham J. W.; Hart, David A.
2004-01-01
Elbow contractures, a frequent problem after injury, can be treated by excision of the joint capsule. However, the underlying changes in the joint capsule are poorly understood. Based on skin healing work, we examined the hypotheses that myofibroblast numbers and expression of a myofibroblast marker α-smooth muscle actin, are elevated in patients with posttraumatic joint contractures. Anterior capsules were obtained from six patients who had operative release of posttraumatic contractures gre...
9. Adhesive Capsulitis in 8 Dogs: Diagnosis and Management
OpenAIRE
Brittany Jean Carr; Sherman Orye Canapp; Debra A Canapp; Lauri-Jo Gamble; David L Dycus
2016-01-01
ABSTRACT:Objective: To describe clinical and diagnostic findings as well as management of adhesive capsulitis in dogs.Background: Adhesive capsulitis, also known as frozen shoulder, is a syndrome defined by loss of range of motion of the shoulder and may be the end-stage manifestation of several primary conditions.Evidentiary Value: This is a case report series of eight dogs with chronic forelimb lameness diagnosed with adhesive capsulitis.Methods: Medical records (June 1, 2010 to September...
10. Adhesive Capsulitis in Eight Dogs: Diagnosis and Management
OpenAIRE
Carr, Brittany J.; Canapp, Sherman O.; Canapp, Debra A.; Gamble, Lauri-Jo; Dycus, David L.
2016-01-01
Objective To describe clinical and diagnostic findings as well as management of adhesive capsulitis in dogs. Background Adhesive capsulitis, also known as frozen shoulder, is a syndrome defined by loss of range of motion of the shoulder and may be the end-stage manifestation of several primary conditions. Evidentiary Value This is a case series report of eight dogs with chronic forelimb lameness diagnosed with adhesive capsulitis. Methods Medical records (June 1, 20...
11. Production, deformation and mechanical investigation of magnetic alginate capsules
Science.gov (United States)
Zwar, Elena; Kemna, Andre; Richter, Lena; Degen, Patrick; Rehage, Heinz
2018-02-01
In this article we investigated the deformation of alginate capsules in magnetic fields. The sensitivity to magnetic forces was realised by encapsulating an oil in water emulsion, where the oil droplets contained dispersed magnetic nanoparticles. We solved calcium ions in the aqueous emulsion phase, which act as crosslinking compounds for forming thin layers of alginate membranes. This encapsulating technique allows the production of flexible capsules with an emulsion as the capsule core. It is important to mention that the magnetic nanoparticles were stable and dispersed throughout the complete process, which is an important difference to most magnetic alginate-based materials. In a series of experiments, we used spinning drop techniques, capsule squeezing experiments and interfacial shear rheology in order to determine the surface Young moduli, the surface Poisson ratios and the surface shear moduli of the magnetically sensitive alginate capsules. In additional experiments, we analysed the capsule deformation in magnetic fields. In spinning drop and capsule squeezing experiments, water droplets were pressed out of the capsules at elevated values of the mechanical load. This phenomenon might be used for the mechanically triggered release of water-soluble ingredients. After drying the emulsion-filled capsules, we produced capsules, which only contained a homogeneous oil phase with stable suspended magnetic nanoparticles (organic ferrofluid). In the dried state, the thin alginate membranes of these particles were rather rigid. These dehydrated capsules could be stored at ambient conditions for several months without changing their properties. After exposure to water, the alginate membranes rehydrated and became flexible and deformable again. During this swelling process, water diffused back in the capsule. This long-term stability and rehydration offers a great spectrum of different applications as sensors, soft actuators, artificial muscles or drug delivery systems.
12. Stream water responses to timber harvest: Riparian buffer width effectiveness
Science.gov (United States)
Barton D. Clinton
2011-01-01
Vegetated riparian buffers are critical for protecting aquatic and terrestrial processes and habitats in southern Appalachian ecosystems. In this case study, we examined the effect of riparian buffer width on stream water quality following upland forest management activities in four headwater catchments. Three riparian buffer widths were delineated prior to cutting; 0m...
13. Evolution of giant dipole resonance width at low temperatures ...
Indian Academy of Sciences (India)
The resonance width. GDR is defined as the full-width at half-maximum (FWHM) of the GDR lineshape and is related to various damping mechanisms of the collective motion inside nuclear matter. The damping of giant collective vibration inside the nuclear medium occurs either due to escape of resonance energy by means ...
14. A STATISTICAL APPROACH FOR OBTAINING THE CONTROLLED WOVEN FABRIC WIDTH
NARCIS (Netherlands)
Maqsood, Muhammad
2015-01-01
A common problem faced in fabric manufacturing is the production of inconsistent fabric width on shuttleless looms in spite of the same fabric specifications. Weft-wise crimp controls the fabric width and it depends on a number of factors, including warp tension, temple type, fabric take-up pressing
15. Enhancement of heat transfer using varying width twisted tape inserts
African Journals Online (AJOL)
Enhancement of heat transfer using varying width twisted tape inserts. ... International Journal of Engineering, Science and Technology ... The present work shows the results obtained from experimental investigations of the augmentation of turbulent flow heat transfer in a horizontal tube by means of varying width twisted ...
16. Precessing deuteron polarization
International Nuclear Information System (INIS)
Sitnik, I.M.; Volkov, V.I.; Kirillov, D.A.; Piskunov, N.M.; Plis, Yu.A.
2002-01-01
The feasibility of the acceleration in the Nuclotron of deuterons polarized in the horizontal plane is considered. This horizontal polarization is named precessing polarization. The effects of the main magnetic field and synchrotron oscillations are included. The precessing polarization is supposed to be used in studying the polarization parameters of the elastic dp back-scattering and other experiments
17. Capsule irradiation tests of non-fissile materials in HANARO
International Nuclear Information System (INIS)
Choo, K. N.; Sohn, J. M.; Kim, B. G.; Shin, Y. T.; Oh, J. M.; Lim, I. C.; Kang, Y. H.
2003-01-01
The R and D programs on the nuclear reactor materials require numerous in-pile tests in HANARO. Extensive efforts have been made to establish design and manufacturing technology for the development of irradiation facilities. Material capsule and rabbit(small non-instrumented capsule) systems were developed for the irradiation test of non fissile materials in HANARO. Several irradiation capsules (8 instrumented and 2 non-instrumented capsules) and rabbits(17 rabbits) has been designed, fabricated and successfully irradiated in HANARO CT, IR, HTS or IP test holes since 1995. Capsules were designed for the irradiation of RPV (Reactor Pressure Vessel), reactor core materials, and Zr-based alloys. Most capsules were made for KAERI material research projects, but 3 capsules were made as a part of national projects for the promotion of HANARO utilization. Rabbits were used for the irradiation of semi-conductors(Si, Sapphire) and magnetic materials. 3,300 specimens from domestic 13 research institutes, 2 nuclear industry companies and 51 universities, were irradiated in HANARO for 26,000 hours using capsule and rabbit irradiation systems. Through this research, the nuclear characteristics of HANARO capsules and rabbits were also produced and piled up in our database
18. Capsule shields the function of short bacterial adhesins
DEFF Research Database (Denmark)
Schembri, Mark; Dalsgaard, D.; Klemm, Per
2004-01-01
occur in other gram-negative bacteria. Likewise, we show that other short adhesins exemplified by the AIDA-I protein are blocked by the presence of a capsule. The results support the notion that capsule polysaccharides sterically prevent receptor-target recognition of short bacterial adhesins......Bacterial surface structures such as capsules and adhesins are generally regarded as important virulence factors. Here we demonstrate that capsules block the function of the self-recognizing protein antigen 43 through physical shielding. The phenomenon is not restricted to Escherichia coli but can....... This negative interference has important biological consequences, such as affecting the ability of bacteria to form biofilms....
19. Difference of CBD width on US vs. ERCP.
Science.gov (United States)
Brook, Olga R; Suissa, Alain; Khamaysi, Iyad; Koren, Dorit; Gaitini, Diana
2007-01-01
To investigate the relationship between US and ERCP in the measurement of common bile duct (CBD) width after application of Compound and Harmonic imaging on ultrasound. We prospectively evaluated the CBD width as measured on endoscopic retrograde cholangiopancreatography (ERCP) and ultrasonography (US), applying Compound and Harmonic US techniques, on 100 patients. Furthermore, we retrospectively re-examined US and ERCP images of 48 patients who underwent ERCP and US during the same hospitalization period. The average difference in measurements by US compared to ERCP was 2.3 mm (P CBD width. There was a good correlation between ERCP and US measurements of CBD width (r = 0.73 for all patients and r = 0.88 for patients with intact gallbladder, P CBD width on US and ERCP of about 2 mm. The application of Compound and Harmonic techniques in the prospective study probably enabled a more accurate sonographic measurement.
20. Introduction to the physics of ICF capsules
International Nuclear Information System (INIS)
Lindl, J.D.
1989-01-01
Inertial Confinement Fusion is an approach to fusion which relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which this confinement is sufficient for efficient thermonuclear burn, high gain ICF targets designed to be imploded directly by laser light. These capsules are generally a spherical shell which is filled with low density DT gas. The shell is composed of an outer region which forms the ablator and an inner region of frozen or liquid DT which forms the main fuel. Energy from the driver is delivered to the ablator which heats up and expands. As the ablator expands and blows outward, the rest of the shell is forced inward to conserve momentum. In this implosion process, several features are important. We define the in-flight-aspect-ratio (IFAR) as the ratio of the shell radius R as it implodes to its thickness ΔR. Hydrodynamic instabilities during the implosion impose limits on this ratio which results in a minimum pressure requirement of about 100 Mbar. The convergence ratio is defined as the ratio of the initial outer radius of the ablator to the final compressed radius of the hot spot. This hot spot is the central region of the compressed fuel which is required to ignite the main fuel in high gain designs. Typical convergence ratios are 30--40. To maintain a nearly spherical shape during the implosion, when convergence ratios are this large, the flux delivered to the capsule must be uniform to a few percent. The remainder of this paper discusses the conditions necessary to achieve thermonuclear ignition in these ICF capsules
1. Effectiveness of corticosteroid injection in adhesive capsulitis.
Science.gov (United States)
Bal, Ajda; Eksioglu, Emel; Gulec, Berna; Aydog, Ece; Gurcay, Eda; Cakci, Aytul
2008-06-01
To assess whether intraarticular corticosteroids improve the outcome of a comprehensive home exercise programme in patients with adhesive capsulitis. The study was undertaken in the Physical Therapy and Rehabilitation Department of a Ministry of Health hospital in Turkey. Eighty patients with adhesive capsulitis were enrolled in the study. The patients were randomly assigned to two groups: Group 1 patients were given intraarticular corticosteroid (1 mL, 40 mg methylprednisolone acetate) followed by a 12-week comprehensive home exercise programme. Group 2 patients were given intraarticular serum physiologic (1 mL solution of 0.9% sodium chloride) followed by a 12-week comprehensive home exercise programme. The outcome parameters were Shoulder Pain and Disability Index and University of California-Los Angeles end-result scores, night pain and shoulder passive range of motion. Mean actual changes in abduction range of motion, Shoulder Pain and Disability Index-total score and Shoulder Pain and Disability Index-pain score were statistically different between the two groups at the second week, with the better scores determined in group 1. However, there were no significant differences between the groups at the 12th week. Medians of University of California-Los Angeles scores in the second week were significantly different between the two groups (P = 0.02), with better scores in group 1; however, the difference in 12th week scores was insignificant. Intraarticular corticosteroids have the additive effect of providing rapid pain relief, mainly in the first weeks of the exercise treatment period. In patients with adhesive capsulitis who have pain symptom predominantly, intraarticular corticosteroid therapy could be advised concomitantly with exercise.
2. Campylobacter polysaccharide capsules: virulence and vaccines
Directory of Open Access Journals (Sweden)
Patricia eGuerry
2012-02-01
Full Text Available Campylobacter jejuni remains a major cause of bacterial diarrhea worldwide and is associated with numerous sequelae, including Guillain Barre Syndrome, inflammatory bowel disease, reactive arthritis, and irritable bowel syndrome. C. jejuni is unusual for an intestinal pathogen in its ability to coat its surface with a polysaccharide capsule (CPS. These capsular polysaccharides vary in sugar composition and linkage, especially those involving heptoses of unusual configuration and O-methyl phosphoramidate linkages. This structural diversity is consistent with CPS being the major serodeterminant of the Penner scheme, of which there are 47 C. jejuni serotypes. Both CPS expression and expression of modifications are subject to phase variation by slip strand mismatch repair. Although capsules are virulence factors for other pathogens, the role of CPS in C. jejuni disease has not been well defined beyond descriptive studies demonstrating a role in serum resistance and for diarrhea in a ferret model of disease. However, perhaps the most compelling evidence for a role in pathogenesis are data that CPS conjugate vaccines protect against diarrheal disease in non-human primates. A CPS conjugate vaccine approach against this pathogen is intriguing, but several questions need to be addressed, including the valency of CPS types required for an effective vaccine. There have been numerous studies of prevalence of CPS serotypes in the developed world, but few studies from developing countries where the disease incidence is higher. The complexity and cost of Penner serotyping has limited its usefulness, and a recently developed multiplex PCR method for determination of capsule type offers the potential of a more rapid and affordable method. Comparative studies have shown a strong correlation of the two methods and studies are beginning to ascertain CPS-type distribution worldwide, as well as examination of correlation of severity of illness with specific CPS types.
3. Chromoendoscopy in magnetically guided capsule endoscopy
Science.gov (United States)
2013-01-01
Background Diagnosis of intestinal metaplasia and dysplasia via conventional endoscopy is characterized by low interobserver agreement and poor correlation with histopathologic findings. Chromoendoscopy significantly enhances the visibility of mucosa irregularities, like metaplasia and dysplasia mucosa. Magnetically guided capsule endoscopy (MGCE) offers an alternative technology for upper GI examination. We expect the difficulties of diagnosis of neoplasm in conventional endoscopy to transfer to MGCE. Thus, we aim to chart a path for the application of chromoendoscopy on MGCE via an ex-vivo animal study. Methods We propose a modified preparation protocol which adds a staining step to the existing MGCE preparation protocol. An optimal staining concentration is quantitatively determined for different stain types and pathologies. To that end 190 pig stomach tissue samples with and without lesion imitations were stained with different dye concentrations. Quantitative visual criteria are introduced to measure the quality of the staining with respect to mucosa and lesion visibility. Thusly determined optimal concentrations are tested in an ex-vivo pig stomach experiment under magnetic guidance of an endoscopic capsule with the modified protocol. Results We found that the proposed protocol modification does not impact the visibility in the stomach or steerability of the endoscopy capsule. An average optimal staining concentration for the proposed protocol was found at 0.4% for Methylene blue and Indigo carmine. The lesion visibility is improved using the previously obtained optimal dye concentration. Conclusions We conclude that chromoendoscopy may be applied in MGCE and improves mucosa and lesion visibility. Systematic evaluation provides important information on appropriate staining concentration. However, further animal and human in-vivo studies are necessary. PMID:23758801
4. Postirradiation examination of capsule GF-4. [HTGR
Energy Technology Data Exchange (ETDEWEB)
Kovacs, W.J.; Sedlak, B.J.
1980-10-01
The GF-4 capsule test was irradiated in the SILOE reactor at Grenoble, France between April 8, 1975 and July 26, 1976. High-enriched uranium (HEU) UC/sub 2/ and weak acid resin (WAR) UC/sub x/O/sub y/ fissile and ThO/sub 2/ fertile particles were tested. Postirradiation examination of cured-in-place fuel rods showed no fuel rod/graphite element interaction. In addition, all rods exhibited adequate structural integrity. Irradiation-induced dimensional changes for rods containing all TRISO-coated fuel were consistent with model predictions; however, rods containing BISO-coated fuel exhibited greater volumetric contractions than predicted.
5. Postirradiation examination of capsule GF-4
International Nuclear Information System (INIS)
Kovacs, W.J.; Sedlak, B.J.
1980-10-01
The GF-4 capsule test was irradiated in the SILOE reactor at Grenoble, France between April 8, 1975 and July 26, 1976. High-enriched uranium (HEU) UC 2 and weak acid resin (WAR) UC/sub x/O/sub y/ fissile and ThO 2 fertile particles were tested. Postirradiation examination of cured-in-place fuel rods showed no fuel rod/graphite element interaction. In addition, all rods exhibited adequate structural integrity. Irradiation-induced dimensional changes for rods containing all TRISO-coated fuel were consistent with model predictions; however, rods containing BISO-coated fuel exhibited greater volumetric contractions than predicted
6. C5 capsule operation modes analysis
International Nuclear Information System (INIS)
Negut, Gh.; Ancuta, Mirela; Stefan, Violeta
2008-01-01
This paper is part of the Nuclear Research Institute Program 13 dedicated to 'TRIGA Research Reactor performance enhancing' and its objective is improving the engineering of the structural materials irradiation. The paper raises the knowledge level on C5 capsule irradiation modes and utilizes previous results in order to increase C5 performances. In the paper the irradiation modes to test zirconium yttrium sample are assessed. These tests are proposed by AECL. There are presented the C5 initial conditions and models. Also. there are presented the thermal hydraulic conditions during normal and accidental operation. The results will be used in the C5 safety report. (authors)
7. Characterization of an aged WESF capsule
International Nuclear Information System (INIS)
Kenna, B.T.; Schultz, F.J.
1983-07-01
A joint effort by SNLA and ORNL was initiated for a detailed characterization of an 18-year-old WESF 137 Cs source which has been used in the Sandia Irradiator for Dried Sewage Solids. The study included evaluation of the inner and outer stainless steel capsules by optical metallography, electron microprobe, and physical testing. Analysis of the residual atmospheres within the two containers was also done. The CsCl was analyzed for isotopic content and impurities. No potential problem areas, including corrosion, were found
8. Automatic blood detection in capsule endoscopy video
Science.gov (United States)
Novozámský, Adam; Flusser, Jan; Tachecí, Ilja; Sulík, Lukáš; Bureš, Jan; Krejcar, Ondřej
2016-12-01
We propose two automatic methods for detecting bleeding in wireless capsule endoscopy videos of the small intestine. The first one uses solely the color information, whereas the second one incorporates the assumptions about the blood spot shape and size. The original idea is namely the definition of a new color space that provides good separability of blood pixels and intestinal wall. Both methods can be applied either individually or their results can be fused together for the final decision. We evaluate their individual performance and various fusion rules on real data, manually annotated by an endoscopist.
9. Reducing redundancy in wireless capsule endoscopy videos.
Science.gov (United States)
Lee, Hyun-Gyu; Choi, Min-Kook; Shin, Byeong-Seok; Lee, Sang-Chul
2013-07-01
We eliminate similar frames from a wireless capsule endoscopy video of the human intestines to maximize spatial coverage and minimize the redundancy in images. We combine an intensity correction method with a method based an optical flow and features to detect and reduce near-duplicate images acquired during the repetitive backward and forward egomotions due to peristalsis. In experiments, this technique reduced duplicate image of 52.3% from images of the small intestine. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.
10. Effect of step width manipulation on tibial stress during running.
Science.gov (United States)
Meardon, Stacey A; Derrick, Timothy R
2014-08-22
Narrow step width has been linked to variables associated with tibial stress fracture. The purpose of this study was to evaluate the effect of step width on bone stresses using a standardized model of the tibia. 15 runners ran at their preferred 5k running velocity in three running conditions, preferred step width (PSW) and PSW±5% of leg length. 10 successful trials of force and 3-D motion data were collected. A combination of inverse dynamics, musculoskeletal modeling and beam theory was used to estimate stresses applied to the tibia using subject-specific anthropometrics and motion data. The tibia was modeled as a hollow ellipse. Multivariate analysis revealed that tibial stresses at the distal 1/3 of the tibia differed with step width manipulation (p=0.002). Compression on the posterior and medial aspect of the tibia was inversely related to step width such that as step width increased, compression on the surface of tibia decreased (linear trend p=0.036 and 0.003). Similarly, tension on the anterior surface of the tibia decreased as step width increased (linear trend p=0.029). Widening step width linearly reduced shear stress at all 4 sites (p<0.001 for all). The data from this study suggests that stresses experienced by the tibia during running were influenced by step width when using a standardized model of the tibia. Wider step widths were generally associated with reduced loading of the tibia and may benefit runners at risk of or experiencing stress injury at the tibia, especially if they present with a crossover running style. Copyright © 2014 Elsevier Ltd. All rights reserved.
11. Polare maskuliniteter
Directory of Open Access Journals (Sweden)
Marit Anne Hauan
2012-05-01
Full Text Available In this paper my aim is to read and understand the journal of Gerrit de Veer from the last journey of William Barents to the Arctic Regions in 1596 and the journal of captain Junge on his hunting trip from Tromsø to Svalbard in 1834.It is nearly 240 years between this to voyages. The first journal is known as the earliest report from the arctic era. Gerrit de Veer adds instructive copper engravings to his text and give us insight in the crews meeting with this new land. Captain Junges journal is found together with his dead crew in a house in a fjord nearby Ny-Ålesund and has no drawings, but word. Both of these journals may be read as sources of the knowledge and understanding of the polar region. They might also unveil the ideas of how to deal with and survive under the challenges that is given. In addition one can ask if the sources can tell us more about how men describe their challenges. Can the way they expressed themselves in the journals give us an understanding of masculinity? And not least help us to create good questions of the change in the ideas of masculinities which is said to follow the change in understanding of the wilderness.
12. Potential value of Cs-137 capsules
Energy Technology Data Exchange (ETDEWEB)
Bloomster, C.H.; Brown, D.R.; Bruno, G.A.; Hazelton, R.F.; Hendrickson, P.L.; Lezberg, A.J.; Tingey, G.L.; Wilfert, G.L.
1985-04-01
We determined the value of Cs-137 compared to Co-60 as a source for the irradiation of fruit (apples and cherries), pork and medical supplies. Cs-137, in the WESF capsule form, had a value of approximately $0.40/Ci as a substitute for Co-60 priced at approximately$1.00/Ci. The comparison was based on the available curies emitted from the surface of each capsule. We developed preliminary designs for fourteen irradiation facilities; seven were based on Co-60 and seven were based on Cs-137. These designs provided the basis for estimating capital and operating costs which, in turn, provided the basis for determining the value of Cs-137 relative to Co-60 in these applications. We evaluated the effect of the size of the irradiation facility on the value of Cs-137. The cost of irradiation is low compared to the value of the product. Irradiation of apples for disinfestation costs $.01 to .02 per pound. Irradiation for trichina-safe pork costs$.02 per pound. Irradiation of medical supplies for sterilization costs $.07 to .12 per pound. The cost of the irradiation source, either Co-60 or Cs-137, contributed only a minor amount to the total cost of irradiation, about 5% for the fruit and hog cases and about 20% for the medical supply cases. We analyzed the sensitivity of the irradiation costs and Cs-137 value to several key assumptions. 13. TREATMENT PROTOCOLS OF ADHESIVE CAPSULITIS - METANALYSIS Directory of Open Access Journals (Sweden) Alisson Guimbala dos Santos Araujo 2013-04-01 Full Text Available Introduction: The adhesive capsulitis (AC is an idiopathic disorder that affects about 3-5% of the general population, the majority being aged 50 years. It is divided into three stages: acute or hiperálgica, rigidity phase or stage of freezing and thawing. This study aimed to analyze the protocols of treatments for adhesive capsulitis. Methods: We performed literature search in electronic databases, BIREME, SciELO, LILACS and PubMed. We analyzed 20 articles of which seven met the inclusion criteria of this study. Results: Of the 20 articles analyzed, it was found that only seven had controlled clinical trials, and the articles selected for the treatment of AC were: medication and physiotherapy, manipulation, hydraulic distension, serials suprascapular nerve blocks, acupuncture, exercise, physiotherapy and nonsteroidal anti-inflammatory therapy dynasplint, deep friction massage and wave diathermy. Conclusion: As noted in the studies, there is a range of treatments that have proven effective for AC, failing to come to a conclusion of what would be the most appropriate treatment. However it was noted that physiotherapy through kinesiotherapy remains the best option, and the earlier therapeutic intervention performed, the better the results. 14. Corticosteroid Injections for Adhesive Capsulitis: A Review. Science.gov (United States) Xiao, Ryan C; Walley, Kempland C; DeAngelis, Joseph P; Ramappa, Arun J 2017-05-01 Adhesive capsulitis is a self-limiting condition in a majority of patients and is often treated nonoperatively. However, symptoms may take 2 to 3 years to resolve fully. A small, but significant, portion of patients require surgical intervention. The purpose of this systematic review is to evaluate the efficacy of corticosteroid injections for the treatment of adhesive capsulitis (AC). A review of articles indexed by the United States National Library of Medicine was conducted by querying the PubMed database for studies involving participants with AC, frozen shoulder, stiff shoulder, or painful shoulder. Articles that included corticosteroids, glucocorticoids, steroids, and injections were included. Corticosteroid injections provide significant symptom relief for 2 to 24 weeks. Injections can be performed intra-articularly or into the subacromial space. Evidence suggests that a 20 mg dose of triamcinolone may be as effective as a 40 mg injection. It remains unclear whether image-guided injections produce a clinically significant difference in outcomes when compared with landmark-guided (blind) injections. Corticosteroids may be less beneficial for diabetic patients. Patients using protease inhibitors (antiretroviral therapy) should not receive triamcinolone because the drug-drug interaction may result in iatrogenic Cushing syndrome. Corticosteroid injections for AC demonstrate short-term efficacy, but may not provide a long-term benefit. More high quality, prospective studies are needed to determine whether corticosteroid injections using ultrasound guidance significantly improve outcomes. 15. Isotretinoin Oil-Based Capsule Formulation Optimization Directory of Open Access Journals (Sweden) Pi-Ju Tsai 2013-01-01 Full Text Available The purpose of this study was to develop and optimize an isotretinoin oil-based capsule with specific dissolution pattern. A three-factor-constrained mixture design was used to prepare the systemic model formulations. The independent factors were the components of oil-based capsule including beeswax (X1, hydrogenated coconut oil (X2, and soybean oil (X3. The drug release percentages at 10, 30, 60, and 90 min were selected as responses. The effect of formulation factors including that on responses was inspected by using response surface methodology (RSM. Multiple-response optimization was performed to search for the appropriate formulation with specific release pattern. It was found that the interaction effect of these formulation factors (X1X2, X1X3, and X2X3 showed more potential influence than that of the main factors (X1, X2, and X3. An optimal predicted formulation with Y10 min, Y30 min, Y60 min, and Y90 min release values of 12.3%, 36.7%, 73.6%, and 92.7% at X1, X2, and X3 of 5.75, 15.37, and 78.88, respectively, was developed. The new formulation was prepared and performed by the dissolution test. The similarity factor f2 was 54.8, indicating that the dissolution pattern of the new optimized formulation showed equivalence to the predicted profile. 16. Petrous bone fractures violating otic capsule. Science.gov (United States) Magliulo, Giuseppe; Ciniglio Appiani, Mario; Iannella, Giannicola; Artico, Marco 2012-12-01 This study presents our experience with a series of patients suffering from petrous bone fractures violating the otic capsule who underwent subtotal petrosectomy combined with eustachian tube, middle ear, and mastoid obliteration, with the goal of preventing cerebrospinal fluid (CSF) leak and meningitis. This study enrolled 26 patients between 1997 and 2011. The clinical symptoms, otoscopy, and preoperative and postoperative audiometry and facial function, as well as CSF leak or meningitis, were evaluated in each patient. The entire group underwent a subtotal petrosectomy using the technique described in detail by Fisch. In addition, each patient was interviewed using a questionnaire to evaluate the impact on quality of life. Intraoperatively, we found significant CSF leaks in 14 patients (42.5%). No patient reported other episodes of CSF leak or meningitis after the surgery. The patients' responses of facial nerve function were slightly worse than the House-Brackmann evaluation (50% versus 42.3%; p < 0.05). The vast majority (88.5%) of the patients experienced no social impact. Our findings suggest the importance of not underestimating the risk for CSF leak in the petrous bone fractures violating the otic capsule. Preoperative counseling regarding the various troublesome complications must adequately motivate candidates to undergo surgery by pointing out the positive impact of the proposed treatment. 17. Potential value of Cs-137 capsules International Nuclear Information System (INIS) Bloomster, C.H.; Brown, D.R.; Bruno, G.A.; Hazelton, R.F.; Hendrickson, P.L.; Lezberg, A.J.; Tingey, G.L.; Wilfert, G.L. 1985-04-01 We determined the value of Cs-137 compared to Co-60 as a source for the irradiation of fruit (apples and cherries), pork and medical supplies. Cs-137, in the WESF capsule form, had a value of approximately$0.40/Ci as a substitute for Co-60 priced at approximately $1.00/Ci. The comparison was based on the available curies emitted from the surface of each capsule. We developed preliminary designs for fourteen irradiation facilities; seven were based on Co-60 and seven were based on Cs-137. These designs provided the basis for estimating capital and operating costs which, in turn, provided the basis for determining the value of Cs-137 relative to Co-60 in these applications. We evaluated the effect of the size of the irradiation facility on the value of Cs-137. The cost of irradiation is low compared to the value of the product. Irradiation of apples for disinfestation costs$.01 to .02 per pound. Irradiation for trichina-safe pork costs $.02 per pound. Irradiation of medical supplies for sterilization costs$.07 to .12 per pound. The cost of the irradiation source, either Co-60 or Cs-137, contributed only a minor amount to the total cost of irradiation, about 5% for the fruit and hog cases and about 20% for the medical supply cases. We analyzed the sensitivity of the irradiation costs and Cs-137 value to several key assumptions
18. Quality evaluation of simvastatin compounded capsules
Directory of Open Access Journals (Sweden)
Flávia Dias Marques-Marinho
2011-09-01
Full Text Available Simvastatin is commercially available as tablets and compounded capsules in Brazil. Very few reports regarding these capsules' quality, and consequently their efficacy, are available. The pharmaceutical quality of 30 batches of 20 mg simvastatin capsules from the market was evaluated by weight determination, content uniformity, disintegration (Brazilian Pharmacopeia, assay and dissolution test (USP32 tablet monograph. A HPLC method was developed for assay, content uniformity and dissolution test, and specifications were also established. Out of the 30 batches evaluated, 29 showed capsule disintegration within 45 min and individual weight variation was within ±10% or ±7.5% relative to average weight, for 300 mg, respectively. Only 27 batches met dissolution test criteria with values >80% of the labeled amount in 45 min; 21 batches showed simvastatin content between 90.0-110.0% of the labeled amount and 19 batches had at least 9 out of 10 capsules with content uniformity values between 85.0-115.0% of the labeled amount with RSDNo Brasil, a sinvastatina está comercialmente disponível na forma de comprimidos e cápsulas manipuladas. Poucos relatos estão disponíveis sobre a qualidade e, consequentemente, a eficácia dessas cápsulas. A qualidade de 30 lotes de sinvastatina 20 mg cápsulas do mercado foi avaliada através da determinação de peso, uniformidade de conteúdo, desintegração (Farmacopéia Brasileira, doseamento e teste de dissolução (monografia comprimidos USP32. Método por CLAE foi desenvolvido para o doseamento, uniformidade de conteúdo e teste de dissolução; além disso, especificações foram estabelecidas. Dos 30 lotes avaliados, 29 apresentaram desintegração da cápsula até 45 min e a variação do peso individual foi ± 10% ou ± 7,5% em relação ao peso médio, se 300 mg, respectivamente. Apenas 27 lotes preencheram os critérios do teste de dissolução com valores > 80% da quantidade rotulada, em 45 min, 21
19. Nightside studies of coherent HF Radar spectral width behaviour
Directory of Open Access Journals (Sweden)
E. E. Woodfield
2002-09-01
Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to the data presented here. Since the
20. Influence of pulse width and detuning on coherent phonon generation
Science.gov (United States)
Nakamura, Kazutaka G.; Shikano, Yutaka; Kayanuma, Yosuke
2015-10-01
We investigated the coherent phonon generation mechanism by irradiation of an ultrashort pulse with a simple two-level model. Our derived formulation shows that both impulsive stimulated Raman scattering (ISRS) and impulsive absorption (IA) simultaneously occur, and phonon wave packets are generated in the electronic ground and excited states by ISRS and IA, respectively. We identify the dominant process from the amplitude of the phonon oscillation. For short pulse widths, ISRS is very small and becomes larger as the pulse width increases. We also show that the initial phase is dependent on the pulse width and the detuning.
1. Nightside studies of coherent HF Radar spectral width behaviour
Directory of Open Access Journals (Sweden)
E. E. Woodfield
Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to
2. The effect of scattering interference term on the practical width
International Nuclear Information System (INIS)
Martins do Amaral, C.; Martinez, A.S.
2001-01-01
The practical width Γ p has an important application in the characterization of the resonance type for the calculation of neutron average cross sections. Previous treatments ignore the interference term χζ,x for the Doppler broadening function in the practical width calculation. In the present paper, a rational approximation for the χζ,x function is derived, using a modified asymptotic Pade method. A new approximation for Γ p is obtained. The results which are presented here provide evidence that the practical width as a function of temperature varies considerably with the inclusion of the interference term χζ,x
3. Finite-width plasmonic waveguides with hyperbolic multilayer cladding.
Science.gov (United States)
Babicheva, Viktoriia E; Shalaginov, Mikhail Y; Ishii, Satoshi; Boltasseva, Alexandra; Kildishev, Alexander V
2015-04-20
Engineering plasmonic metamaterials with anisotropic optical dispersion enables us to tailor the properties of metamaterial-based waveguides. We investigate plasmonic waveguides with dielectric cores and multilayer metal-dielectric claddings with hyperbolic dispersion. Without using any homogenization, we calculate the resonant eigenmodes of the finite-width cladding layers, and find agreement with the resonant features in the dispersion of the cladded waveguides. We show that at the resonant widths, the propagating modes of the waveguides are coupled to the cladding eigenmodes and hence, are strongly absorbed. By avoiding the resonant widths in the design of the actual waveguides, the strong absorption can be eliminated.
4. 21 CFR 520.1920 - Prochlorperazine, isopropamide sustained release capsules.
Science.gov (United States)
2010-04-01
... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Prochlorperazine, isopropamide sustained release capsules. 520.1920 Section 520.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... dogs in which gastrointestinal disturbances are associated with emotional stress. (2)(i) Capsules...
5. The development of the nasal capsule of the silver carp ...
African Journals Online (AJOL)
The development of the nasal capsule, including the procartilaginous as well as some mesenchymatous developmental stages, is described in the Chinese silver carp, Hypophthalmichthys molitrix (Val.). In the nasal capsule a primitive feature, namely the presence of a complete paraphysial bridge was observed.
6. The development of the nasal capsule of the silver carp ...
African Journals Online (AJOL)
The development of the nasal capsule, including the procartilaginous as well as some mesenchymatous developmental stages, is described in the chinese silver carp,. Hypophthalmichthys molitrix (VaL). In the nasal capsule a primitive feature, namely the presence of a complete paraphysial bridge was observed.
7. Evidence for an intact polysaccharide capsule in Bordetella pertussis.
Science.gov (United States)
Neo, YiLin; Li, Rui; Howe, Josephine; Hoo, Regina; Pant, Aakanksha; Ho, SiYing; Alonso, Sylvie
2010-03-01
Polysaccharide capsules contribute to the pathogenesis of many bacteria species by providing resistance against various defense mechanisms. The production of a capsule in Bordetella pertussis, the etiologic agent of whooping cough, has remained controversial; earlier studies reported this pathogen as a capsulated microorganism whereas the recent B. pertussis genome analysis revealed the presence of a truncated capsule locus. In this work, using transmission electron microscopy and immunostaining approaches, we provide a formal evidence for the presence of an intact microcapsule produced at the surface of both laboratory strain and clinical isolates of B. pertussis. In agreement with previous studies, we found that the capsule is optimally produced in avirulent phase. Unexpectedly, the presence of the capsule was also detected at the surface of virulent B. pertussis bacteria. Consistently, a substantial transcriptional activity of the capsule operon was detected in virulent phase, suggesting that the capsular polysaccharide may play a role during pertussis pathogenesis. In vitro assays indicated that the presence of the capsule does not affect B. pertussis adherence to mammalian cells and does not further protect the bacterium from phagocytosis, complement-mediated killing or antimicrobial peptide attack. Copyright 2009. Published by Elsevier SAS.
8. Temporary presence of myofibroblasts in human elbow capsule after trauma
NARCIS (Netherlands)
Doornberg, Job N.; Bosse, Tjalling; Cohen, Mark S.; Jupiter, Jesse B.; Ring, David; Kloen, Peter
2014-01-01
Elbow stiffness is a common complication after elbow trauma. The elbow capsule is often thickened, fibrotic, and contracted at the time of surgical release. The limited studies available suggest that the capsule is contracted because of fibroblast-to-myofibroblast differentiation. We hypothesize
9. Diamagnetically stabilized levitation control of an intraluminal magnetic capsule
International Nuclear Information System (INIS)
Lam, Michael; Mintchev, Martin
2009-01-01
Controlled navigation promotes full utilization of capsule endoscopy for reliable real-time diagnosis in the gastrointestinal (GI) tract, but intermittent natural peristalsis can disturb the navigational control, destabilize the capsule and take it out of levitation. The focus of the present work was to develop an economical and effective real-time magnetic capsule-guiding system that can operate in the presence of naturally existing peristalsis while retaining navigational control. A real-size magnetic navigation system that can handle peristaltic forces of up to 1.5 N was designed utilizing the computer-aided design (CAD) system Maxwell 3D (Ansoft, Pittsburg, PA) and was verified using a small-size physical experimental setup. The proposed system contains a pair of 50 cm diameter, 10 000-turn copper electromagnets with a 10 cm × 10 cm ferrous core driven by currents of up to 300 A and can successfully maintain position control over the levitating capsule during peristalsis. The addition of bismuth diamagnetic casing for stabilizing the levitating capsule was also studied. A modeled magnetic field around the diamagnetically cased permanent magnet was shown to be redistributed aligning its interaction with the external electromagnets, thus stabilizing the levitating capsule. In summary, a custom-designed diamagnetically facilitated capsule navigation system can successfully steer an intraluminal magnet-carrying capsule
10. Material properties of the human posterior knee capsule
NARCIS (Netherlands)
Rachmat, H. H.; Janssen, D.; Verkerke, G. J.; Diercks, R. L.; Verdonschot, N.
2015-01-01
BACKGROUND: There is considerable interest to develop accurate subject-specific biomechanical models of the knee. Most of the existing models currently do not include a representation of the posterior knee capsule. In order to incorporate the posterior capsule in knee models, data is needed on its
11. Material properties of the human posterior knee capsule
NARCIS (Netherlands)
Rachmat, H.H.; Janssen, D.W.; van Tienen, T.; Diercks, R.L.; Verkerke, Gijsbertus Jacob; Verdonschot, Nicolaas Jacobus Joseph; Fernandes, Paulo; Folgado, Joao; Silva, Miguel
2012-01-01
BACKGROUND: There is considerable interest to develop accurate subject-specific biomechanical models of the knee. Most of the existing models currently do not include a representation of the posterior knee capsule. In order to incorporate the posterior capsule in knee models, data is needed on its
12. Iodometric determination of ampicillin in proprietary capsules | Ejele ...
African Journals Online (AJOL)
The concentration of ampicillin in ampicillin capsule preparations purchased in Owerri main market, Imo State of Nigeria, was determined using the iodometric titration method. The results showed that the ampicillin concentrations in the capsules contained between 250 and 260 mg/cap of ampicillin trihydrate. Statistical ...
13. Langmuir and Langmuir–Blodgett films of capsules of haemoglobin ...
Indian Academy of Sciences (India)
Haemoglobin; capsules; Langmuir–Blodgett films; pH; multi-walled capsules; isoelectric point. 1. Introduction. Drug delivery and storage of formulations in pharma- ceutical applications require microencapsulation tech- niques. Many different methods have been used to develop encapsulation techniques for the purpose of.
14. Pharmacokinetic Study of a Capsule-based Chronomodulated Drug ...
African Journals Online (AJOL)
Purpose: To develop and determine the in vivo performance of a capsule-based pulsatile drug delivery system containing salbutamol sulphate. Methods: A controlled pulsatile release of drug after a programmed 4 h lag period was achieved from cross-linked gelatin capsule shells containing salbutamol pellets, and sealed ...
15. Clinical effect of Resina Draconis capsules on primary dysmenorrhoea
African Journals Online (AJOL)
Clinical effect of Resina Draconis capsules on primary dysmenorrhoea. Li Sun, Jia Wang. Abstract. Purpose: To examine the effectiveness of Resina Draconis capsules in the treatment of primary dysmenorrhoea. Methods: In total, 324 patients with primary dysmenorrhoea were randomly allocated to three groups based on ...
16. Agile patency system eliminates risk of capsule retention in patients with known intestinal strictures who undergo capsule endoscopy.
Science.gov (United States)
Herrerias, Juan M; Leighton, Jonathan A; Costamagna, Guido; Infantolino, Anthony; Eliakim, Rami; Fischer, Doron; Rubin, David T; Manten, Howard D; Scapa, Eitan; Morgan, Douglas R; Bergwerk, Ari J; Koslowsky, Binyamin; Adler, Samuel N
2008-05-01
Capsule endoscopy (CE) of the small bowel has become a standard diagnostic tool, but there have been concerns regarding the risk of capsule retention in certain high-risk groups. The Agile patency system, an ingestible and dissolvable capsule with an external scanner, was developed to allow physicians to perform CE with greater confidence that the capsule will be safely excreted in patients at risk for capsule retention. Our purpose was to assess the ability of the device to help physicians identify which patients with known strictures may safely undergo CE. Patients with known strictures ingested the new patency capsule and underwent periodic scanning until it was excreted. The intestinal tract was considered to be sufficiently patent if the capsule was excreted intact or if the capsule was not detected by the scanner at 30 hours after ingestion. If patency was established, then standard CE was performed. International multicenter study. A total of 106 patients with known strictures. Agile patency system. Performance and safety of Agile patency system. A total of 106 patients ingested the patency capsule. Fifty-nine (56%) excreted it intact and subsequently underwent CE. There were no cases of capsule retention. Significant findings on CE were found in 24 (41%). There were 3 severe adverse events. These results suggest that the Agile patency system is a useful tool for physicians to use before CE in patients with strictures to avoid retention. This group of patients may have a high yield of clinically significant findings at CE. This capsule may determine whether patients who have a contraindication to CE may safely undergo CE and obtain useful diagnostic information.
17. No stabilizing effect of the elbow joint capsule. A kinematic study
DEFF Research Database (Denmark)
Nielsen, K K; Olsen, Bo Sanderhoff
1999-01-01
We dissected 7 cadaveric elbow specimens, leaving the collateral ligaments and the joint capsule intact. The anterior and the posterior capsule were sequentially transected, followed by kinematic testings. We found no change in joint laxity after total transection of the capsule.......We dissected 7 cadaveric elbow specimens, leaving the collateral ligaments and the joint capsule intact. The anterior and the posterior capsule were sequentially transected, followed by kinematic testings. We found no change in joint laxity after total transection of the capsule....
18. Analysis of Fission Products on the AGR-1 Capsule Components
Energy Technology Data Exchange (ETDEWEB)
Paul A. Demkowicz; Jason M. Harp; Philip L. Winston; Scott A. Ploger
2013-03-01
The components of the AGR-1 irradiation capsules were analyzed to determine the retained inventory of fission products in order to determine the extent of in-pile fission product release from the fuel compacts. This includes analysis of (i) the metal capsule components, (ii) the graphite fuel holders, (iii) the graphite spacers, and (iv) the gas exit lines. The fission products most prevalent in the components were Ag-110m, Cs 134, Cs 137, Eu-154, and Sr 90, and the most common location was the metal capsule components and the graphite fuel holders. Gamma scanning of the graphite fuel holders was also performed to determine spatial distribution of Ag-110m and radiocesium. Silver was released from the fuel components in significant fractions. The total Ag-110m inventory found in the capsules ranged from 1.2×10 2 (Capsule 3) to 3.8×10 1 (Capsule 6). Ag-110m was not distributed evenly in the graphite fuel holders, but tended to concentrate at the axial ends of the graphite holders in Capsules 1 and 6 (located at the top and bottom of the test train) and near the axial center in Capsules 2, 3, and 5 (in the center of the test train). The Ag-110m further tended to be concentrated around fuel stacks 1 and 3, the two stacks facing the ATR reactor core and location of higher burnup, neutron fluence, and temperatures compared with Stack 2. Detailed correlation of silver release with fuel type and irradiation temperatures is problematic at the capsule level due to the large range of temperatures experienced by individual fuel compacts in each capsule. A comprehensive Ag 110m mass balance for the capsules was performed using measured inventories of individual compacts and the inventory on the capsule components. For most capsules, the mass balance was within 11% of the predicted inventory. The Ag-110m release from individual compacts often exhibited a very large range within a particular capsule.
19. Polarization of the cosmic background radiation
International Nuclear Information System (INIS)
Lubin, P.M.
1980-03-01
The results and technique of a measurement of the linear polarization of the Cosmic Background Radiation are discussed. The ground-based experiment utilizes a single horn (7 0 beam width) Dicke-type microwave polarimeter operating at 33 GHz (9.1 mm). Data taken between May 1978 and February 1980 from both the northern hemisphere (Berkeley Lat. = 38 0 N) and the southern hemisphere (Lima Lat. = 12 0 S) show the radiation to be essentially unpolarized over all areas surveyed. For the 38 0 declination data the 95% confidence level limit on a linearly polarized component is 0.3 mK for the average and 12 and 24 hour periods. Fitting all data gives the 95% confidence level limit on a linearly polarized component of 0.3 mK for spherical harmonics through third order. Constraints on various cosmological models are discussed in light of these limits
20. Adsorption and desorption of phosphorus in ceramic capsules
International Nuclear Information System (INIS)
Almeida, J.R.F. de.
1983-01-01
Experiments were carried out in order to analyse the capacity of adsorving P from water using ceramic capsules with 32P, in the presence and absence of water flow through the capsule. Also studied was the desorption of 32 P from the capsule in water, with and without water flow. The desorption of residual 32 P was analysed by isotopic exchange with 31 P, also with and without water flow. It was observed that, in the presence of a flow, the capsule retained 32 P from the solution, which was weakly desorbed by water but was isotopically exchanged with 31 P. In the absence of a flow, the capsule was not an efficient P adsorber. (Author) [pt
1. [Wireless capsule endoscopy: basic principles and clinical utility].
Science.gov (United States)
González-Suárez, Begoña; Galter, Sara; Balanzó, Joaquín
2007-06-01
Wireless capsule endoscopy (PillCam) represents a major advance in the study of small bowel disease since this procedure allows images of hitherto unreachable areas to be obtained. Approved for use by the Food and Drug Administration in August 2000, capsule endoscopy is currently a first line procedure in the study of small bowel disease. This technique consists of a non-reusable swallowable capsule (length 26 x 11 mm) that acquires video images while moving through the gastrointestinal tract propelled by natural peristalsis. The main indications of capsule endoscopy are evaluation of obscure gastrointestinal bleeding, chronic anemia, and inflammatory bowel disease. Contraindications are swallowing disorders and known or suspected small bowel strictures of any etiology. Consequently, small bowel follow through is useful prior to capsule endoscopy when these lesions are suspected.
2. Multi-modal imaging of adhesive capsulitis of the shoulder.
Science.gov (United States)
Zappia, Marcello; Di Pietto, Francesco; Aliprandi, Alberto; Pozza, Simona; De Petro, Paola; Muda, Alessandro; Sconfienza, Luca Maria
2016-06-01
Adhesive capsulitis of the shoulder is a clinical condition characterized by progressive limitation of active and passive mobility of the glenohumeral joint, generally associated with high levels of pain. Although the diagnosis of adhesive capsulitis is based mainly on clinical examination, different imaging modalities including arthrography, ultrasound, magnetic resonance, and magnetic resonance arthrography may help to confirm the diagnosis, detecting a number of findings such as capsular and coracohumeral ligament thickening, poor capsular distension, extracapsular contrast leakage, and synovial hypertrophy and scar tissue formation at the rotator interval. Ultrasound can also be used to guide intra- and periarticular procedures for treating patients with adhesive capsulitis. • Diagnosis of adhesive capsulitis is mainly based on clinical findings. • Imaging may be used to exclude articular or rotator cuff pathology. • Thickening of coracohumeral and inferior glenohumeral ligaments are common findings. • Rotator interval fat pad obliteration has 100 % specificity for adhesive capsulitis. • Ultrasound can be used to guide intra- and periarticular treatments.
3. Relationship between width of greater trochanters and width of iliac wings in tronchanteric bursitis.
Science.gov (United States)
Viradia, Neal K; Berger, Alex A; Dahners, Laurence E
2011-09-01
Trochanteric bursitis is a common disorder that is characterized by inflammation of the bursa, superficial to the greater trochanter of the femur, leading to pain in the lateral hip, and often occurs because of acute trauma or repetitive friction involving the iliotibial band, the greater trochanter, and the bursa. In the study reported here, we hypothesized that the increased incidence of bursitis may be the result of the increased prominence of the trochanter in relation to the wings of the iliac crest. Distances between the outermost edges of trochanters and iliac wings were measured in 202 patients from the University of North Carolina Health Care System-101 without a known diagnosis and 101 with a clinical diagnosis of trochanteric bursitis. To determine significance, t tests for nonpaired data were used. Mean (SD) difference between trochanter and iliac wing widths was 28 (20) mm in the group diagnosed with trochanteric bursitis and 17 (18) mm in the control group. The difference between the groups in this regard was significant (Pbursitis group and 1.05 (.06) in the control group. The difference between these groups was significant (Pbursitis.
4. Line Width Recovery after Vectorization of Engineering Drawings
Directory of Open Access Journals (Sweden)
Gramblička Matúš
2016-12-01
Full Text Available Vectorization is the conversion process of a raster image representation into a vector representation. The contemporary commercial vectorization software applications do not provide sufficiently high quality outputs for such images as do mechanical engineering drawings. Line width preservation is one of the problems. There are applications which need to know the line width after vectorization because this line attribute carries the important semantic information for the next 3D model generation. This article describes the algorithm that is able to recover line width of individual lines in the vectorized engineering drawings. Two approaches are proposed, one examines the line width at three points, whereas the second uses a variable number of points depending on the line length. The algorithm is tested on real mechanical engineering drawings.
5. The effect of buffer zone width on biodiversity
DEFF Research Database (Denmark)
Navntoft, Søren; Sigsgaard, Lene; Kristensen, Kristian
2012-01-01
attention in previous studies. In this paper we report on finding for syrphids, spiders and carabids, three taxonomic groups with different mobility, all important for conservation biological control. For all groups we found an effect of buffer zone width on their density. A buffer width of 6m......Field margin management for conservation purposes is a way to protect both functional biodiversity and biodiversity per se without considerable economical loss as field margins are less productive. However, the effect of width of the buffer zone on achievable biodiversity gains has received little...... was the narrowest that consistently promoted a higher abundance or activity of arthropods within the field area (outside the hedge bottom). However, a further increase in buffer width always increased the abundance and activity of arthropods a little more....
6. Integrated Diagnostic Analysis of ICF Capsule Performance
Science.gov (United States)
Cerjan, Charles
2012-10-01
An understanding of the dynamics of imploding Inertial Confinement Fusion (ICF) capsules is crucial to achieve high convergence and gain. The relative roles of laser irradiation, hohlraum drive, and capsule response are intertwined and will be difficult to disentangle unless appropriate diagnostic probes are fielded and their results correlated. In the case of capsule implosions, several currently deployed diagnostics provide important information about the size and shape of the developing hot spot through x-ray self-emission, neutron production and average ion temperature by neutron time-of-flight signals, shell material mix into the hot spot by high-resolution x-ray spectra, and remaining mass during convergent ablation by x-ray backlighting. Obtaining a physically consistent picture of the implosion dynamics requires an integration of these disparate experimental data. This talk describes a three-dimensional model that attempts this integration. Assuming pressure equilibrium at peak compression and invoking simple radiative and equation-of-state relations, the pressure, density and electron temperature are obtained by optimized fitting of the experimental output to simple, global functional forms. The fitting procedure is sufficiently flexible to incorporate typical observational data such as x-ray self-emission, neutron time-of-flight signals, neutron yield, high-resolution x-ray spectra and radiographic images. Once consistency is obtained, many important secondary quantities can be derived such as the fuel areal density, high energy x-ray emission, neutron images, and nuclear activation. This approach has been validated by comparison with radiation-hydrodynamic simulations, producing semi-quantitative agreement and is now routinely used to characterize cryogenic implosion experiments. This talk will provide an overview of the implementation of the model and describe its application to recent experimental data.[4pt] In addition to my collaborators Paul
7. Conventional MRI Finding in a Case of Adhesive Shoulder Capsulitis
Energy Technology Data Exchange (ETDEWEB)
Park, Hak Hoon [Yeosu Hanyeoexpo Hospital, Yeosu (Korea, Republic of); Back, Chang Hee [Yeosu Baek Hospital, Yeosu (Korea, Republic of)
2010-02-15
To evaluate the conventional magnetic resonance image findings in patients with adhesive shoulder capsulitis. The preoperative MR images of 76 patients with adhesive shoulder capsulitis that was also treated by arthroscopic capsule release. In contrast to the MR images of 25 control patients without adhesive shoulder capsulitis, the thickness and area of hyposignal intensity around the coracohumeral ligament (CHL), subcoracoidal fat, capsular thickness of the rotator interval, capsular thickness, and height of the axillary recess were measured. The existence of fluid in the axillary recess was also verified. Patients with adhesive capsulitis showed a significant increase in the thickness (average 10.57 mm vs. 5.88 mm, T=8.289, p<0.001), area (average 3.49 point vs. 0.96 point Z=7.775, p< 0.001) of hyposignal intensity around CHL, and a thickened joint capsule in the rotator interval (average 5.93 mm vs. 2.15 mm, Z=6.472, p< 0.001). The thickness of the hyposignal intensity around the CHL is about 10 mm or more and has a specificity of 96%, a sensitivity of about 55% in the area of hyposignal intensity from around the CHL, Seventy-five percent or more of cases, showed a 100%, 95%, complete obliteration of the subcoracoidal fat that was 96%, and a 50% thickness of the capsule. A rotator interval of 6mm or more had a 96%, 50% for the diagnosis of adhesive capsulitis of the shoulder. The capsular thickness and maximal height of axillary recess and the presence of fluid in the axillary recess was not significant in patients with adhesive shoulder capsulitis. Thickening of the hyposignal intensity around the CHL, subcoracoidal fat obliteration, and capsular thickening at the rotator interval, are characteristic MRI findings in adhesive shoulder capsulitis
8. Estimating the Spectral Width of a Narrowband Optical Signal
DEFF Research Database (Denmark)
Lading, Lars; Skov Jensen, A.
1980-01-01
Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector.......Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector....
9. SM Higgs decay branching ratios and total Higgs width
CERN Multimedia
Daniel Denegri
2001-01-01
Upper: Higgs decay ratios as a function of Higgs mass. The largest branching ratio is not necessarily the most usefull one. The most usefull ones are gamma gamma bbar ZZ and WW as in those modes latter signal to background ratios can be achieved. Lower: Total Higgs decay width versus Higgs mass. At low masses the natural width is extremely small, thus observability depends on instrumental resolution primarily.
10. Study of partial width fluctuations for 232Th radiative capture
International Nuclear Information System (INIS)
Nifenecker, H.; Hazoni, Y.; Michaudon, A.; Paya, D.
1962-01-01
The partial widths of radiative capture at the excited level at 1 MeV in 233 Th were measured. This measurement was achieved on 7 neutron resonances of 232 Th from 20 to 175 eV. The normalization methods used for deducing these widths are described. The most probable value of the number of degrees of freedom is found to be 4 and the probability that ν ≤ 1 is found to be 16 per cent. (authors) [fr
11. Width of electromagnetic wave instability spectrum in tungsten plate
International Nuclear Information System (INIS)
Rinkevich, A.B.
1995-01-01
Based on the study of high-frequency signal modulation and spectrum analysis of the envelope a measurement of spectrum width for electromagnetic wave instability was carried out under conditions of current pulse action on tungsten plate in magnetic field. The existence of amplitude-frequency wave modulation was revealed. The width of current disturbance spectrum in a specimen was evaluated. Current disturbances are shown to cause the instability of electromagnetic wave. 11 refs.; 6 figs
12. Quantum numbers and decay widths of the psi (3684)
International Nuclear Information System (INIS)
Luth, V.; Boyarski, A.M.; Lynch, H.L.; Breidenbach, M.; Bulos, F.; Feldman, G.J.; Fryberger, D.; Hanson, G.; Hartill, D.L.; Jean-Marie, B.; Larsen, R.R.; Luke, D.; Morehouse, C.C.; Paterson, J.M.; Perl, M.L.; Pun, T.P.; Rapidis, P.; Richter, B.; Schwitters, R.F.; Tanenbaum, W.; Vannucci, F.; Abrams, G.S.; Chinowsky, W.; Friedberg, C.E.; Goldhaber, G.; Kadyk, J.A.; Litke, A.M.; Lulu, B.A.; Pierre, F.M.; Sadoulet, B.; Trilling, G.H.; Whitaker, J.S.; Winkelmann, F.C.; Wiss, J.E.
1975-01-01
Cross sections for e + e - →hadrons, e + e - , and μ + μ - near 3684 MeV are presented. The psi(3684) resonance is established as having the assignment J/sup PC/=1 -- . The mass is 3684+-5 MeV. The partial width for decay to electrons is GAMMA/sube/=2.1+-0.3 keV and the total width is GAMMA=228+-56 keV
13. Correlations for reduced-width amplitudes in 49V
International Nuclear Information System (INIS)
Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.
1980-01-01
Measurement of the relative sign of inelastic proton-channel amplitudes permits the determination of amplitude correlations. Data were obtained for 45 5/2 + resonances in 49 V. Although the reduced widths in each channel followed a Porter-Thomas distribution, large amplitude correlations were observed. The results are compared with the reduced-width--amplitude distribution of Krieger and Porter. This is the first direct test of the Krieger-Porter distribution
14. Comprehensive intermaxillary tooth width proportion of Bangkok residents
Directory of Open Access Journals (Sweden)
Somchai Manopatanakul
2011-04-01
Full Text Available Proper occlusion depends on the correct width ratio between upper and lower teeth, known as Bolton's ratio. In fact, this ratio can be calculated for each pair of teeth from the central incisor to the first permanent molar. This set of ratios, known as comprehensive cumulative percentage ratios (CPRs, can be used not only to determine which tooth or teeth have a tooth width discrepancy, but can also enable the partial graphical analysis of tooth width discrepancy when there is agenesis of certain permanent teeth. Although CPRs have been calculated for Caucasians, tooth width is known to vary depending on racial origin. Therefore, a test of differences between racial groups should be carried out. If these ratios of the Caucasians and Bangkokians are significantly different, the ratio of the Bangkokians is recommended. The objective of this study was to measure tooth size disproportion for Thai patients and to calculate a corresponding set of CPRs. Thirty-seven pairs of dental models were made from a group of Bangkok residents with normal occlusion. Mesiodistal tooth width was measured for each model. The intra- and inter-examiner measurement errors were ascertained as insignificant (p > 0.05. CPRs were then calculated and compared to those derived from other studies. Ten of thirteen CPRs were significantly different from corresponding values derived from Caucasians. We conclude that tooth width ratios vary between different racial groups, and therefore that these should be calculated specifically for each patient racial group.
15. Electromagnetic Control System for Capsule Navigation: Novel Concept for Magnetic Capsule Maneuvering and Preliminary Study.
Science.gov (United States)
Lucarini, Gioia; Mura, Marco; Ciuti, Gastone; Rizzo, Rocco; Menciassi, Arianna
The gastrointestinal tract is home of some of the most deadly human diseases. The main problems are related to the difficulty of accessing it for diagnosis or intervention and concomitant patient discomfort. The flexible endoscopy technique has established itself in medical practice due to its high diagnostic accuracy and reliability; however, several technical limitations still remain and the procedure is poorly tolerated by patients. The use of magnetic fields to control and steer endoscopic capsules is increasing in minimally invasive procedures. In fact, magnetic coupling is one of the few physical phenomena capable of transmitting motion beyond a physical barrier, allowing for the compact design of the device itself. In this framework, the authors present the preliminary design and assessment of a magnetic coupling for magnetic endoscopic capsules considering an electromagnetic approach. In particular, a novel toroidal electromagnet is proposed as the control and driving system. The system concept, design, and preliminary results are reported.
16. Photophysics Applied to Cavitands and Capsules.
Science.gov (United States)
Berryman, Orion B; Dube, Henry; Rebek, Julius
2011-07-01
The use of light as a stimulus to control functional materials or nano-devices is appealing as it provides convenient control of triggering events where and when they are desired without introducing extra components to the system. Many photophysical and photochemical processes are extremely fast, giving rise to nearly instantaneous onset of events. However, these fast processes can be challenging to engineer into chemical systems. Supramolecular chemistry offers a convenient way to study and control photoprocesses. Given the reversible and self-programmed nature of modern host-guest systems, a modular approach can be considered in which different photoprocesses are coupled to obtain complex functions that emerge and are controlled solely by light inputs. In this review, we highlight recent examples of photoswitching and photophysics applied in the context of supramolecular host-guest systems, with a particular emphasis on resorcinarene based cavitands and hydrogen bonded capsules.
17. Multilevel wireless capsule endoscopy video segmentation
Science.gov (United States)
Hwang, Sae; Celebi, M. Emre
2010-03-01
Wireless Capsule Endoscopy (WCE) is a relatively new technology (FDA approved in 2002) allowing doctors to view most of the small intestine. WCE transmits more than 50,000 video frames per examination and the visual inspection of the resulting video is a highly time-consuming task even for the experienced gastroenterologist. Typically, a medical clinician spends one or two hours to analyze a WCE video. To reduce the assessment time, it is critical to develop a technique to automatically discriminate digestive organs and shots each of which consists of the same or similar shots. In this paper a multi-level WCE video segmentation methodology is presented to reduce the examination time.
18. Capsule HRB-15B postirradiation examination report
Energy Technology Data Exchange (ETDEWEB)
Ketterer, J.W.; Bullock, R.E.
1981-06-01
Capsule HRB-15B design tested 184 thin graphite trays containing unbonded fuel particles to peak exposures of 6.6 x 10/sup 25/ n/m/sup 2/ (E > 29 fJ)/sub HTGR/ fast fluence, approx. 27% fissions per initial metal atom (FIMA) fissile burnup, and 6% FIMA fertile burnup at nominal time-averaged temperatures of 815 to 915/sup 0/C. The capsule tested a variety of low-enriched uranium (approx. 19.5% U-235) fissile particle types, including UC/sub 2/, UC/sub x/O/sub y/, UO/sub 2/, zirconium-buffered UO/sub 2/ (referred to in this report as UO/sub 2//sup *), and 1:1(Th,U)O/sub 2/ with both TRISO and silicon-BISO coatings. All fertile particles were ThO/sub 2/ with BISO, silicon-BISO, or TRISO coatings. The findings indicated that all TRISO particles retained virtually all of their fission product inventories, except small quantities of silver, at these irradiation temperatures, while some of the silicon-BISO particles released significant amounts of both silver and cesium. No kernel migration, pressure vessel, or outer pyrolytic carbon (OPyC) failures were observed in the fuel particles, which had total diameters of < 900 ..mu..m; however, the incidence of failed OPyC coatings was found to increase with particle size in the TRISO inert particles, which had diameters of 1000 to 1200 ..mu..m. UO/sub 2//sup */ particles exhibited no detrimental irradiation effects, but they contained pure carbon precipitates in the kernels after irradiation which were not observed in the undoped UO/sub 2/ particles. Postirradiation examination revealed no differences in the irradiation performance of three UC/sub x/O/sub y/ kernel types with varying oxygen/uranium ratios.
19. Polarized electron sources
Energy Technology Data Exchange (ETDEWEB)
Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)
1994-12-01
The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.
20. Adhesion and detachment of a capsule in axisymmetric flow
Science.gov (United States)
Keh, M. P.; Leal, L. G.
2016-05-01
The adhesion and detachment of a capsule on a solid boundary surface is studied via a combination of scaling theory and numerical simulation and the behavior is compared and contrasted with a vesicle. It is shown that the dominant physical property for both capsules and vesicles is the area dilation modulus Ks of the membrane. The nonzero shear modulus Gs for capsules increases the resistance to deformation and thus decreases slightly the equilibrium contact radius for an adhered capsule compared to an adhered vesicle. The detachment process in this study is due to an external axisymmetric flow. Unlike a rigid body that must be pulled away without change of shape, capsules (and vesicles) almost always detach dominantly by peeling in which the contact radius decreases but the minimum separation distance does not change until the final moments of detachment. Compared to a vesicle with the same Ks, a capsule maintains a more compact shape and is harder to elongate under a given external flow. Hence, the detachment process is slower for capsules compared to vesicles with the same Ks.
1. Closed Loop Control of a Tethered Magnetic Capsule Endoscope.
Science.gov (United States)
Taddese, Addisu Z; Slawinski, Piotr R; Obstein, Keith L; Valdastri, Pietro
2016-06-01
Magnetic field gradients have repeatedly been shown to be the most feasible mechanism for gastrointestinal capsule endoscope actuation. An inverse quartic magnetic force variation with distance results in large force gradients induced by small movements of a driving magnet; this necessitates robotic actuation of magnets to implement stable control of the device. A typical system consists of a serial robot with a permanent magnet at its end effector that actuates a capsule with an embedded permanent magnet. We present a tethered capsule system where a capsule with an embedded magnet is closed loop controlled in 2 degree-of-freedom in position and 2 degree-of-freedom in orientation. Capitalizing on the magnetic field of the external driving permanent magnet, the capsule is localized in 6-D allowing for both position and orientation feedback to be used in a control scheme. We developed a relationship between the serial robot's joint parameters and the magnetic force and torque that is exerted onto the capsule. Our methodology was validated both in a dynamic simulation environment where a custom plug-in for magnetic interaction was written, as well as on an experimental platform. The tethered capsule was demonstrated to follow desired trajectories in both position and orientation with accuracy that is acceptable for colonoscopy.
2. Effects of powder flow properties on capsule filling weight uniformity.
Science.gov (United States)
Osorio, Juan G; Muzzio, Fernando J
2013-09-01
Filling capsules with the right amount of powder ingredients is an important quality parameter. The purpose of this study was to develop effective laboratory methods for characterizing flow properties of pharmaceutical powder blends and correlating such properties to weight variability in filled capsules. The methods used for powder flow characterization were bulk and tapped density, gravitational displacement rheometer (GDR) flow index, Freeman Technology V.4 (FT4) powder rheometer compressibility, FT4 basic flow energy (BFE), and cohesion parameters [cohesion, (C) and flow factor (ffc)] measured in a shear cell also using the FT4. Capsules were filled using an MG2-G140 continuous nozzle dosator capsule-filling machine. Powder flow properties were the most predominant factors affecting the weight and weight variability in the filled capsules. Results showed that the weight variability decreased with increasing bulk and tapped density, ffc and BFE, while the weight variability increased with increasing compressibility, cohesion and GDR flow index. Powder flow properties of the final blends were significantly correlated to the final capsule weight and weight variability of the filled capsules.
3. Polyelectrolyte multilayer capsules as vehicles with tunable permeability.
Science.gov (United States)
Antipov, Alexei A; Sukhorukov, Gleb B
2004-11-29
This review is devoted to a novel type of polymer micro- and nanocapsules. The shell of the capsule is fabricated by alternate adsorption of oppositely charged polyelectrolytes (PEs) onto the surface of colloidal particles. Cores of different nature (organic or inorganic) with size varied from 0.1 to 10 mum can be used for templating such PE capsules. The shell thickness can be tuned in nanometer range by assembling of defined number of PE layers. The permeability of capsules depends on the pH, ionic strength, solvent, polymer composition, and shell thickness; it can be controlled and varied over wide range of substances regarding their molecular weight and charge. Including functional polymers into capsule wall, such as weak PEs or thermosensitive polymers, makes the capsule permeability sensitive to correspondent external stimuli. Permeability of the capsules is of essential interest in diverse areas related to exploitation of systems with controlled and sustained release properties. The envisaged applications of such capsules/vesicles cover biotechnology, medicine, catalysis, food industry, etc.
4. Pulse Width Affects Scalp Sensation of Transcranial Magnetic Stimulation.
Science.gov (United States)
Peterchev, Angel V; Luber, Bruce; Westin, Gregory G; Lisanby, Sarah H
Scalp sensation and pain comprise the most common side effect of transcranial magnetic stimulation (TMS), which can reduce tolerability and complicate experimental blinding. We explored whether changing the width of single TMS pulses affects the quality and tolerability of the resultant somatic sensation. Using a controllable pulse parameter TMS device with a figure-8 coil, single monophasic magnetic pulses inducing electric field with initial phase width of 30, 60, and 120 µs were delivered in 23 healthy volunteers. Resting motor threshold of the right first dorsal interosseus was determined for each pulse width, as reported previously. Subsequently, pulses were delivered over the left dorsolateral prefrontal cortex at each of the three pulse widths at two amplitudes (100% and 120% of the pulse-width-specific motor threshold), with 20 repetitions per condition delivered in random order. After each pulse, subjects rated 0-to-10 visual analog scales for Discomfort, Sharpness, and Strength of the sensation. Briefer TMS pulses with amplitude normalized to the motor threshold were perceived as slightly more uncomfortable than longer pulses (with an average 0.89 point increase on the Discomfort scale for pulse width of 30 µs compared to 120 µs). The sensation of the briefer pulses was felt to be substantially sharper (2.95 points increase for 30 µs compared to 120 µs pulse width), but not stronger than longer pulses. As expected, higher amplitude pulses increased the perceived discomfort and strength, and, to a lesser degree the perceived sharpness. Our findings contradict a previously published hypothesis that briefer TMS pulses are more tolerable. We discovered that the opposite is true, which merits further study as a means of enhancing tolerability in the context of repetitive TMS. Copyright © 2016 Elsevier Inc. All rights reserved.
5. Wireless pH capsule--yield in clinical practice.
Science.gov (United States)
Roman, S; Mion, F; Zerbib, F; Benamouzig, R; Letard, J C; Bruley des Varannes, S
2012-03-01
Wireless pH monitoring is one of the recent technologies that focus on improving the diagnosis of gastroesophageal reflux disease (GERD). The capsule, which is fixed within the esophagus, transmits data via telemetry to an external receiver. The capsule is usually inserted 6 cm above the squamocolumnar junction during an upper endoscopy. The standard recording duration is 48 hours but this can be extended to 96 hours. The wireless capsule has been shown to be at least as accurate as the conventional catheter for the monitoring of esophageal pH. Normal pH values have been established in three different series. The use of a wireless capsule provides an increased diagnostic yield for GERD compared with the conventional catheter. The increased yield is the result of higher sensitivity to detect both abnormal acid esophageal exposure and positive symptom-reflux association. This may be related both to the prolonged recording duration and to fewer dietary modifications and restrictions on activities. Several studies have shown that the pH capsule was better tolerated by patients than the conventional pH catheter. Mild-to-moderate chest pain represents the main side effect of the pH capsule: severe chest pain requiring endoscopic removal of the capsule is rare. The main indication for wireless capsule application is monitoring of distal esophageal pH for diagnostic purpose, particularly in patients with a normal endoscopic examination. The capsule technique has some limitations: costs are higher than conventional pH monitoring, misplacement may occur, and the sampling rate is lower. Finally, compared with pH-impedance monitoring, only acid reflux events can be evaluated. © Georg Thieme Verlag KG Stuttgart · New York.
6. The atomic structure of polar and non-polar InGaN quantum wells and the green gap problem
Energy Technology Data Exchange (ETDEWEB)
Humphreys, C.J., E-mail: colin.humphreys@msm.cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Griffiths, J.T., E-mail: jg641@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Tang, F., E-mail: ft274@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Oehler, F., E-mail: fabrice.oehler@lpn.cnrs.fr [CNRS/C2N, Paris Sud University, Route de Nozay, 91460 Marcoussis (France); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Victoria 3800 (Australia); Zheng, C., E-mail: changlin.zheng@monash.edu [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Etheridge, J., E-mail: joanne.etheridge@mcem.monash.edu [Department of Materials Science and Engineering, Monash University, Victoria 3800 (Australia); Martin, T.L., E-mail: tomas.martin@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Bagot, P.A.J., E-mail: paul.bagot@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Moody, M.P., E-mail: michael.moody@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Sutherland, D., E-mail: danny.sutherland@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Dawson, P., E-mail: philip.dawson@manchester.ac.uk [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Schulz, S., E-mail: stefan.schulz@tyndall.ie [Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork (Ireland); and others
2017-05-15
Highlights: • We have studied the atomic structure of polar and non-polar InGaN quantum wells. • The non-polar (11-20) InGaN quantum wells contain indium-rich clusters, unlike the polar (0001) quantum wells. • The electrons and holes in the quantum wells are localised by different mechanisms. - Abstract: We have used high resolution transmission electron microscopy (HRTEM), aberration-corrected quantitative scanning transmission electron microscopy (Q-STEM), atom probe tomography (APT) and X-ray diffraction (XRD) to study the atomic structure of (0001) polar and (11-20) non-polar InGaN quantum wells (QWs). This paper provides an overview of the results. Polar (0001) InGaN in QWs is a random alloy, with In replacing Ga randomly. The InGaN QWs have atomic height interface steps, resulting in QW width fluctuations. The electrons are localised at the top QW interface by the built-in electric field and the well-width fluctuations, with a localisation energy of typically 20 meV. The holes are localised near the bottom QW interface, by indium fluctuations in the random alloy, with a localisation energy of typically 60 meV. On the other hand, the non-polar (11-20) InGaN QWs contain nanometre-scale indium-rich clusters which we suggest localise the carriers and produce longer wavelength (lower energy) emission than from random alloy non-polar InGaN QWs of the same average composition. The reason for the indium-rich clusters in non-polar (11-20) InGaN QWs is not yet clear, but may be connected to the lower QW growth temperature for the (11-20) InGaN QWs compared to the (0001) polar InGaN QWs.
7. Capacitor charging FET switcher with controller to adjust pulse width
Science.gov (United States)
Mihalka, Alex M.
1986-01-01
A switching power supply includes an FET full bridge, a controller to drive the FETs, a programmable controller to dynamically control final output current by adjusting pulse width, and a variety of protective systems, including an overcurrent latch for current control. Power MOSFETS are switched at a variable frequency from 20-50 kHz to charge a capacitor load from 0 to 6 kV. A ferrite transformer steps up the DC input. The transformer primary is a full bridge configuration with the FET switches and the secondary is fed into a high voltage full wave rectifier whose output is connected directly to the energy storage capacitor. The peak current is held constant by varying the pulse width using predetermined timing resistors and counting pulses. The pulse width is increased as the capacitor charges to maintain peak current. A digital ripple counter counts pulses, and after the desired number is reached, an up-counter is clocked. The up-counter output is decoded to choose among different resistors used to discharge a timing capacitor, thereby determining the pulse width. A current latch shuts down the supply on overcurrent due to either excessive pulse width causing transformer saturation or a major bridge fault, i.e., FET or transformer failure, or failure of the drive circuitry.
8. Evaluation of polarization mode dispersion in a telecommunication wavelength selective switch using quantum interferometry.
Science.gov (United States)
Fraine, A; Minaeva, O; Simon, D S; Egorov, R; Sergienko, A V
2012-01-30
A polarization mode dispersion (PMD) measurement of a commercial telecommunication wavelength selective switch (WSS) using a quantum interferometric technique with polarization-entangled states is presented. Polarization-entangled photons with a broad spectral width covering the telecom band are produced using a chirped periodically poled nonlinear crystal. The first demonstration of a quantum metrology application using an industrial commercial device shows a promising future for practical high-resolution quantum interference.
9. The role of polarization current in magnetic island evolution
International Nuclear Information System (INIS)
Connor, J.W.; Waelbroeck, F.L.; Wilson, H.R.
2001-01-01
The polarization current plays an important role in the evolution of magnetic islands with a width comparable to the characteristic ion orbit width. Understanding the evolution of such small magnetic islands is important for two reasons: (1) to investigate the threshold mechanisms for growth of large-scale islands (e.g., neoclassical tearing modes), and (2) to describe the drive mechanisms for small-scale magnetic turbulence and consequent transport. This article presents a two-fluid, cold ion, collisional analysis of the role of the polarization current in magnetic island evolution in slab geometry. It focuses on the role played by the conjunction of parallel electron dynamics and perpendicular transport (particle diffusion and viscosity) in determining the island rotation frequency and the distribution of the polarization current within the island
10. OdoCapsule: next-generation wireless capsule endoscopy with accurate lesion localization and video stabilization capabilities.
Science.gov (United States)
Karargyris, Alexandros; Koulaouzidis, Anastastios
2015-01-01
In this paper, we propose a platform to achieve accurate localization of small-bowel lesions and endoscopic video stabilization in wireless capsule endoscopy. Current research modules rely on the use of external magnetic fields and triangulation methods to calculate the position vector of the capsule, leading to considerable error margins. Our platform, entitled OdoCapsule (a synthesis of the words Odometer and Capsule), provides real-time distance information from the point of duodenal entry to the point of exit from the small bowel. To achieve this, OdoCapsule is equipped with three miniature legs. Each leg carries a soft rubber wheel, which is made with human-compliant material. These legs are extendable and retractable thanks to a micromotor and three custom-made torsion springs. The wheels are specifically designed to function as microodometers: each rotation they perform is registered. Hence, the covered distance is measured accurately in real time. Furthermore, with its legs fully extended, OdoCapsule can stabilize itself inside the small-bowel lumen thus offering smoother video capture and better image processing. Recent ex vivo testing of this concept, using porcine small bowel and a commercially available (custom-modified) capsule endoscope, has proved its viability.
11. Femtosecond pulse-width dependent trapping and directional ejection dynamics of dielectric nanoparticles
KAUST Repository
Chiang, Weiyi
2013-09-19
We demonstrate that laser pulse duration, which determines its impulsive peak power, is an effective parameter to control the number of optically trapped dielectric nanoparticles, their ejections along the directions perpendicular to polarization vector, and their migration distances from the trapping site. This ability to controllably confine and eject the nanoparticle is explained by pulse width-dependent optical forces exerted on nanoparticles in the trapping site and ratio between the repulsive and attractive forces. We also show that the directional ejections occur only when the number of nanoparticles confined in the trapping site exceeds a definite threshold. We interpret our data by considering the formation of transient assembly of the optically confined nanoparticles, partial ejection of the assembly, and subsequent filling of the trapping site. The understanding of optical trapping and directional ejections by ultrashort laser pulses paves the way to optically controlled manipulation and sorting of nanoparticles. © 2013 American Chemical Society.
12. A direct measurement of the invisible width of the Z from single photon counting
Science.gov (United States)
Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Mattison, T.; Pacheco, A.; Padilla, C.; Pasual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Blucher, E.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Hagelberg, R.; Harvey, J.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Lohse, T.; Maggi, M.; Markou, C.; Martinez, M.; Mato, P.; Meinhard, H.; Minten, A.; Miotto, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Pater, J. R.; Perlas, J. A.; Pusztaszeri, J.-F.; Ranjard, F.; Redlinger, G.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Wachsmuth, H.; Wasserbaech, S.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Atjaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Prulhière, F.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Fouque, G.; Orteu, S.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Levinthal, D.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Colrain, P.; Ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Moutoussi, A.; Nash, J.; Patton, S.; Payne, D. G.; Phillips, M. J.; San Martin, G.; Sedgbeer, J. K.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Vogl, R.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Petl, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Steeg, F.; Walther, S. M.; Wanke, R.; Wolf, B.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Nicod, D.; Papalexiou, S.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jakobs, K.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stielin, U.; Stiegler, U.; St. Denis, R.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jaffe, D. E.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Valassi, A.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Gao, Y.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botteril, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Cartwright, S.; Combley, F.; Dawson, I.; Thompson, L. F.; Barberio, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellatoni, L.; Chen, W.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Nachtman, J. M.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Shi, Z. H.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; Sau, Lan, Wu; Wu, X.; Zheng, M.; Zobernig, G.
1993-09-01
The ALEPH detector at LEP is used to study single photon events in e+e- collisions at the Z resonance. In a total data sample of 15.7 pb-1 taken in 1990 and 1991 scanning the resonance, 400 events were recorded where each has a single deposition of more than 1.5 GeV measured in the polar angular region cosθγ < 0.74 of the electromagnetic calorimeter. It is shown that this number of events cab be accounted for by known processes. After subtraction of background events, the invisible width of the Z is determined to be 45 +/- 34(stat.) +/- 34(syst.) MeV. Using Z. resonance parameters derived by ALEPH, the corresponding number oflight neutrino generations is found to be 2.68 +/- 0.20(stat.) +/- 0.20(syst.). Supported by the US Department of Energy, contract DE-ACO2-76ER00881.
13. Geographical Income Polarization
DEFF Research Database (Denmark)
Azhar, Hussain; Jonassen, Anders Bruun
inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live......In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...
14. Modelling the widths of fission observables in GEF
Directory of Open Access Journals (Sweden)
Schmidt K.-H.
2013-03-01
Full Text Available The widths of the mass distributions of the different fission channels are traced back to the probability distributions of the corresponding quantum oscillators that are coupled to the heat bath, which is formed by the intrinsic degrees of freedom of the fissioning system under the influence of pairing correlations and shell effects. Following conclusion from stochastic calculations of Adeev and Pashkevich, an early freezing due to dynamical effects is assumed. It is shown that the mass width of the fission channels in low-energy fission is strongly influenced by the zero-point motion of the corresponding quantum oscillator. The observed variation of the mass widths of the asymmetric fission channels with excitation energy is attributed to the energy-dependent properties of the heat bath and not to the population of excited states of the corresponding quantum oscillator.
15. Form factors and radiation widths of the giant multipole resonances
International Nuclear Information System (INIS)
Denisov, V.Yu.
1990-01-01
Simple analytic relations for the form factors of inelastic electron scattering in the Born approximation and radiation widths of the isovector and isoscalar giant multipole resonances are derived. The dynamic relationship between the volume and surface density vibrations were taken into account in this calculation. The form factors in the Born approximation were found to be in satisfactory agreement with experimental data in the region of small transferred momenta. The radiation widths of isoscalar multipole resonances increase when the number of nucleons increase as A 1/3 , and for isovector resonances this dependence has the form f(A)A 1/3 , where f(A) is a slowly increasing function of A. Radiation widths well fit the experimental data
16. Analysis of edge stability for models of heat flux width
Directory of Open Access Journals (Sweden)
M.A. Makowski
2017-08-01
Full Text Available Detailed measurements of the ne, Te, and Ti profiles in the vicinity of the separatrix of ELMing H-mode discharges have been used to examine plasma stability at the extreme edge of the plasma and assess stability dependent models of the heat flux width. The results are strongly contrary to the critical gradient model, which posits that a ballooning instability determines a gradient scale length related to the heat flux width. The results of this analysis are not sensitive to the choice of location to evaluate stability. Significantly, it is also found that the results are completely consistent with the heuristic drift model for the heat flux width. Here the edge pressure gradient scales with plasma density and is proportional to the pressure gradient inferred from the equilibrium in accordance with the predictions of that theory.
17. Fast and Robust Nanocellulose Width Estimation Using Turbidimetry.
Science.gov (United States)
Shimizu, Michiko; Saito, Tsuguyuki; Nishiyama, Yoshiharu; Iwamoto, Shinichiro; Yano, Hiroyuki; Isogai, Akira; Endo, Takashi
2016-10-01
The dimensions of nanocelluloses are important factors in controlling their material properties. The present study reports a fast and robust method for estimating the widths of individual nanocellulose particles based on the turbidities of their water dispersions. Seven types of nanocellulose, including short and rigid cellulose nanocrystals and long and flexible cellulose nanofibers, are prepared via different processes. Their widths are calculated from the respective turbidity plots of their water dispersions, based on the theory of light scattering by thin and long particles. The turbidity-derived widths of the seven nanocelluloses range from 2 to 10 nm, and show good correlations with the thicknesses of nanocellulose particles spread on flat mica surfaces determined using atomic force microscopy. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
18. SATCAP-C : a program for thermal hydraulic design of pressurized water injection type capsule
International Nuclear Information System (INIS)
Harayama, Yasuo; Someya, Hiroyuki; Asoh, Tomokazu; Niimi, Motoji
1992-10-01
There are capsules called 'Pressure Water Injection Type Capsule' as a kind of irradiation devices at the Japan Materials Testing Reactor (JMTR). A type of the capsules is a 'Boiling Water Capsule' (usually named BOCA). The other type is a 'Saturated Temperature Capsule' (named SATCAP). When the water is kept at a constant pressure, the water temperature does not become higher than the saturated temperature so far as the water does not fully change to steam. These type capsules are designed on the basis of the conception of applying the water characteristic to the control of irradiation temperature of specimens in the capsules. In designing of the capsules in which the pressurized water is injected, thermal performances have to be understood as exactly as possible. It is not easy however to predict thermal performances such as axially temperature distribution of water injected in the capsule, because there are heat-sinks at both side of inner and outer of capsule casing as the result that the water is fluid. Then, a program (named SATCAP-C) for the BOCA and SATCAP was compiled to grasp the thermal performances in the capsules and has been used the design of the capsules and analysis of the data obtained from some actual irradiation capsules. It was confirmed that the program was effective in thermal analysis for the capsules. The analysis found out the values for heat transfer coefficients at various surfaces of capsule components and some thermal characteristics of capsules. (author)
19. Similarity of Stream Width Distributions Across Headwater Systems
Science.gov (United States)
Allen, G. H.; Pavelsky, T.; Barefoot, E. A.; Tashie, A.; Butman, D. E.
2016-12-01
The morphology and abundance of streams control the rates of hydraulic and biogeochemical exchange between streams, groundwater, and the atmosphere. In large river systems, studies have used remote sensing to quantify river morphology, and have found that the relationship between river width and abundance is fractal, such that narrow rivers are proportionally more common than wider rivers. However, in headwater systems (stream order 1-3), where many biogeochemical reactions are most rapid, the relationship between stream width and abundance is unknown, reducing the certainty of biogeochemical flux estimates. To constrain this uncertainty, we surveyed two components of stream morphology (wetted stream width and length) in seven physiographically contrasting stream networks in Kings Creek in Konza Prarie, KS; Sagehen Creek in the N. Sierra Nevada Mtns., CA; Elder Creek in Angelo Coast Range Preserve, CA; Caribou Creek in the Caribou Poker Creek Research Watershed, AK; V40 Stream, NZ; Blue Duck Creek, NZ; Stony Creek in Duke Forest, NC. To assess temporal variations, we also surveyed stream geometry in a subcatchment of Stony Creek six times over a range of moderate streamflow conditions (discharge less than 90 percentile of gauge record). Here we show a strikingly consistent gamma statistical distribution of stream width in all surveys and a characteristic most abundant stream width of 32±7 cm independent of flow conditions or basin size. This consistency is remarkable given the substantial physical diversity among the studied catchments. We propose a model that invokes network topology theory and downstream hydraulic geometry to show that, as active drainage networks expand and contract in response to changes in streamflow, the most abundant stream width remains approximately static. This framework can be used to better extrapolate stream size and abundance from large rivers to small headwater streams, with significant impact on understanding of the hydraulic
20. Total Space in Resolution Is at Least Width Squared
OpenAIRE
Bonacina, Ilario
2016-01-01
Given an unsatisfiable k-CNF formula phi we consider two complexity measures in Resolution: width and total space. The width is the minimal W such that there exists a Resolution refutation of phi with clauses of at most W literals. The total space is the minimal size T of a memory used to write down a Resolution refutation of phi where the size of the memory is measured as the total number of literals it can contain. We prove that T = Omega((W - k)^2).
1. Statistical analysis of s-wave neutron reduced widths
International Nuclear Information System (INIS)
Pandita Anita; Agrawal, H.M.
1992-01-01
The fluctuations of the s-wave neutron reduced widths for many nuclei have been analyzed with emphasis on recent measurements by a statistical procedure which is based on the method of maximum likelihood. It is shown that the s-wave neutron reduced widths of nuclei follow single channel Porter Thomas distribution (x 2 -distribution with degree of freedom ν = 1) for most of the cases. However there are apparent deviations from ν = 1 and possible explanation and significance of this deviation is given. These considerations are likely to modify the evaluation of neutron cross section. (author)
2. Efficient algorithms for estimating the width of nearly normal distributions
International Nuclear Information System (INIS)
Akerlof, C.W.
1983-01-01
Typical physics data samples often conform to Gaussian distributions with admixtures of more slowly varying backgrounds. Under such circumstances the standard deviation is known to be a poor statistical measure of distribution width. As an alternative, the performance of Gini's mean difference is compared with the standard deviation and the mean deviation. Variants which sum over subsets of all possible pairs are shown to have statistical efficiencies comparable to the mean difference and mean deviation but do not require extensive data storage or a priori knowledge of the sample mean. These statistics are reasonable candidates for monitoring the distribution width of a real time data stream. (orig.)
3. Application and improvement of capsule system for penstocks
Energy Technology Data Exchange (ETDEWEB)
Matstuda, S.; Fujishiro, Y.; Yamagucki, T.; Okubo, M.; Miyabe, N.; Sakagami, H.; Ikeda, M.; Kurose, Y.
1981-01-01
Kawasaki Heavy Industries, Ltd. has succeeded in applying an all-position, narrow-gap MIG automatic welding method using a Capsule System for both penstocks of the Electric Power Development Company's Okukiyotsu and the Kansai Electric Power Company's Okuyoshino Pumped Storage Hydroelectric Power Stations. The application and development of the capsule system and MIG welding method have been officially commended this year by the Japan Society of Steel Construction (JSSC). The KHI-development capsule system has been improved by the study of various data rendered by the aforesaid two projects. Based on past experience, KHI is now involved in the construction of another penstock, this one for the Tokoku Electric Power Company's No. 2 Numazawa Pumped Storage Hydroelectric Power Station. The design and improvements of the capsule system, and its application to Numazawa Penstock are discussed.
4. Colon capsule endoscopy: Advantages, limitations and expectations. Which novelties?
Science.gov (United States)
Riccioni, Maria Elena; Urgesi, Riccardo; Cianci, Rossella; Bizzotto, Alessandra; Spada, Cristiano; Costamagna, Guido
2012-01-01
Since the first reports almost ten years ago, wireless capsule endoscopy has gained new fields of application. Colon capsule endoscopy represents a new diagnostic technology for colonic exploration. Clinical trials have shown that colon capsule endoscopy is feasible, accurate and safe in patients suffering from colonic diseases and might be a valid alternative to conventional colonoscopy in selected cases such as patients refusing conventional colonoscopy or with contraindications to colonoscopy or when colonoscopy is incomplete. Despite the enthusiasm surrounding this new technique, few clinical and randomized controlled trials are to be found in the current literature, leading to heterogeneous or controversial results. Upcoming studies are needed to prove the substantial utility of colon capsule endoscopy for colon cancer screening, especially in a low prevalence of disease population, and for other indications such as inflammatory bowel disease. Possible perspectives are critically analysed and reported in this paper. PMID:22523610
5. Positron radiography of ignition-relevant ICF capsules
Science.gov (United States)
Williams, G. J.; Chen, Hui; Field, J. E.; Landen, O. L.; Strozzi, D. J.
2017-12-01
Laser-generated positrons are evaluated as a probe source to radiograph in-flight ignition-relevant inertial confinement fusion capsules. Current ultraintense laser facilities are capable of producing 2 × 1012 relativistic positrons in a narrow energy bandwidth and short time duration. Monte Carlo simulations suggest that the unique characteristics of such positrons allow for the reconstruction of both capsule shell radius and areal density between 0.002 and 2 g/cm2. The energy-downshifted positron spectrum and angular scattering of the source particles are sufficient to constrain the conditions of the capsule between preshot and stagnation. We evaluate the effects of magnetic fields near the capsule surface using analytic estimates where it is shown that this diagnostic can tolerate line integrated field strengths of 100 T mm.
6. The mechanical properties of the human hip capsule ligaments.
Science.gov (United States)
Hewitt, John D; Glisson, Richard R; Guilak, Farshid; Vail, T Parker
2002-01-01
The human hip capsule is adapted to facilitate upright posture, joint stability, and ambulation, yet it routinely is excised in hip surgery without a full understanding of its mechanical contributions. The objective of this study was to provide information about the mechanical properties of the ligaments that form the hip capsule. Cadaver bone-ligament-bone specimens of the iliofemoral, ischiofemoral, and femoral arcuate ligaments were tested to failure in tension. The hip capsule was found to be an inhomogeneous structure and should be recognized as being composed of discrete constituent ligaments. The anterior ligaments, consisting of the 2 arms of the iliofemoral ligament, were much stronger than the posterior ischiofemoral ligament, withstanding greater force at failure and exhibiting greater stiffness. Knowledge of the anatomy and mechanical properties of the capsule may help the hip surgeon choose an appropriate surgical approach or repair strategy.
7. Outcomes of Surgery for Posterior Polar Cataract Using Torsional Ultrasound
Directory of Open Access Journals (Sweden)
Selçuk Sızmaz
2013-10-01
Full Text Available Purpose: The aim of this study is to report outcomes of surgery for posterior polar cataract using torsional ultrasound. Material and Method: Medical records of 26 eyes of 21 consecutive patients with posterior polar cataract who had cataract surgery using the torsional phacoemulsification were evaluated retrospectively. The surgical procedure used, phacoemulsification parameters, intraoperative complications, and postoperative visual outcome were recorded. Results: Of the 26 eyes, 24 (92.3% had small to medium posterior polar opacity. Two eyes had large opacity. All surgeries were performed using the torsional handpiece. Posterior capsule rupture occurred in 4 (15.3% eyes. The mean visual acuity improved significantly after surgery (p<0.001. The postoperative visual acuity was worse than 20/20 in 5 eyes. The cause of the low acuity was amblyopia. Discussion: Successful surgical results and good visual outcome can be achieved with phacoemulsification using the torsional handpiece. (Turk J Ophthalmol 2013; 43: 345-7
8. The power of product innovation: Smokers' perceptions of capsule cigarettes.
Science.gov (United States)
Moodie, Crawford; Ford, Allison; Dobbie, Fiona; Thrasher, James F; McKell, Jennifer; Purves, Richard
2017-08-30
Since being brought to market in 2007, cigarettes with capsules in the filter that can be burst to change the flavour have had remarkable global success, highlighting the importance of product innovation for tobacco companies. Very few studies have explored how these products are perceived by smokers however. This paper sought to address this gap by exploring smokers' awareness of cigarettes with one or two flavour-changing capsules in the filter and the appeal of these products. Twenty focus groups were conducted in Glasgow and Edinburgh in 2015 with current smokers (N=120), segmented by age (16-17, 18-24, 25-35, 36-50, >50), gender and social grade. Awareness, use and appeal of capsule cigarettes was greater among younger adults (16-35 years), who showed most interest in these products. Those who perceived capsules positively mentioned multiple benefits: the ability to burst the capsule, convenience of being able to share cigarettes among menthol and non-menthol smokers, better taste, fresher breath, reduced smell and greater discretion. It was suggested that capsule cigarettes, particularly the double capsule cigarette (which had two differently flavoured capsules in the filter), would encourage non-smokers to experiment with smoking and discourage smokers from quitting. The findings offer some reasons behind the global growth of the capsule cigarette segment. Cigarettes with flavour-changing capsules in the filter have been one of the most successful product innovations of the last decade for tobacco companies. They have received very little academic attention however. Employing focus groups with 120 smokers aged 16 and over, we found that capsule cigarettes held most appeal to, and were considered to be targeted at, younger people, with it suggested that these products would encourage initiation and discourage cessation. This study provides some understanding of how these products are viewed by smokers. © The Author 2017. Published by Oxford University Press
9. Postirradiation examination of capsule P13Q
International Nuclear Information System (INIS)
Young, C.A.; Scott, C.B.
1977-09-01
Capsule P13Q was the sixth in a series of irradiation tests conducted under the HTGR Fuels and Core Development Program. It was the first accelerated irradiation test of large-diameter graphite-fuel bodies irradiated to peak LHTGR fast fluences. The primary purpose of the test was to evaluate the irradiation performance of the integral bodies and cured-in-place fuel rods. One TRISO UC 2 and two BISO ThO 2 coated particle batches were used in the fuel rods. The postirradiation examination revealed that the performance of the H-451 graphite bodies and fuel rods irradiated to a peak fluence of 9.5 x 10 25 n/m 2 (E greater than 29 fJ)/sub HTGR/ and to an average peak fuel rod temperature of 1175 0 C was acceptable. A range of fuel rod variables was tested and none were detrimental to the integrity of the rods. The coated fuel particles behaved in a manner predicted by previous irradiation data
10. 131-iodine capsules in thyroid therapy
International Nuclear Information System (INIS)
Schulthess, G.K. von; Bekier, A.
1985-01-01
We investigated the uptake of therapeutic doses of 131-Iodine in a capsular form which were given to 16 patients with benign thyroid disease, and compared it to the uptake of a dose of a liquid diagnostic sodium iodide I-131 ( 131 I) given to the same patients. The aim of this study was to determine the additional radiation dose sustained by the gastric mucosa, and thus, to establish the safety of this galenic form of 131 I. It was found that the average capsule-dissolution time was about 12 min, with a large standard deviation of about 7 min. Using these data and a theoretical radiation-dose calculation, we estimated that the maximum dose to the gastric mucosa was approximately 250 rad (250 cGy) for a therapeutic activity of 5 mCi (185 MBq), which is the maximum dose which may be given as single application to out-patients in Switzerland. Thus, 131 I administered in a capsular form is a safe galenic form for therapeutic use in patients with thyroid disease. (orig.)
11. A UWB wireless capsule endoscopy device.
Science.gov (United States)
Thotahewa, Kasun M S; Redoute, Jean-Michel; Yuce, Mehmet Rasit
2014-01-01
Wireless capsule endoscopy (WCE) presents many advantages over traditional wired endoscopic methods. The performance of WCE devices can be improved using high-frequency communication systems such as Impulse Radio-Ultra-Wideband (IR-UWB) to enable a high data rate transmission with low-power consumption. This paper presents the hardware implementation and experimental evaluation of a WCE device that uses IR-UWB signals in the frequency range of 3.5 GHz to 4.5 GHz to transmit image data from inside the body to a receiver placed outside the body. Key components of the IR-UWB transmitter, such as the narrow pulse generator and up-conversion based RF section are described in detail. This design employs a narrowband receiver in the WCE device to receive a control signal externally in order to control and improve the data transmission from the device in the body. The design and performance of a wideband implantable antenna that operates in the aforementioned frequency range is also described. The operation of the WCE device is demonstrated through a proof-of-concept experiment using meat.
12. Capsule Endoscopy for Portal Hypertensive Enteropathy
Directory of Open Access Journals (Sweden)
Seong Ran Jeon
2016-01-01
Full Text Available Portal hypertensive enteropathy (PHE is a mucosal abnormality of the small bowel that is observed in patients with portal hypertension (PH and can lead to gastrointestinal bleeding and anemia. The pathogenesis is still not completely understood. The introduction of new endoscopic methods, including capsule endoscopy (CE or balloon-assisted enteroscopy, has increased the detection of these abnormalities. CE can also serve as a road map for deciding subsequent interventions and evaluating the treatment effect. The prevalence of PHE is reportedly 40–70% in patients with PH. Endoscopic findings can be roughly divided into vascular and nonvascular lesions such as inflammatory-like lesions. Traditionally, PHE-associated factors include large esophageal varices, portal hypertensive gastropathy or colopathy, Child-Turcotte-Pugh class B or C, a history of variceal treatment, and acute gastrointestinal bleeding. More recently, on using scoring systems, a high computed tomography or transient elastography score was reportedly PHE-related factors. However, the prevalence of PHE and its related associated factors remain controversial. The management of PHE has not yet been standardized. It should be individualized according to each patient’s situation, the availability of therapy, and each institutional expertise.
13. Orion Capsule Handling Qualities for Atmospheric Entry
Science.gov (United States)
Tigges, Michael A.; Bihari, Brian D.; Stephens, John-Paul; Vos, Gordon A.; Bilimoria, Karl D.; Mueller, Eric R.; Law, Howard G.; Johnson, Wyatt; Bailey, Randall E.; Jackson, Bruce
2011-01-01
Two piloted simulations were conducted at NASA's Johnson Space Center using the Cooper-Harper scale to study the handling qualities of the Orion Command Module capsule during atmospheric entry flight. The simulations were conducted using high fidelity 6-DOF simulators for Lunar Return Skip Entry and International Space Station Return Direct Entry flight using bank angle steering commands generated by either the Primary (PredGuid) or Backup (PLM) guidance algorithms. For both evaluations, manual control of bank angle began after descending through Entry Interface into the atmosphere until drogue chutes deployment. Pilots were able to use defined bank management and reversal criteria to accurately track the bank angle commands, and stay within flight performance metrics of landing accuracy, g-loads, and propellant consumption, suggesting that the pilotability of Orion under manual control is both achievable and provides adequate trajectory performance with acceptable levels of pilot effort. Another significant result of these analyses is the applicability of flying a complex entry task under high speed entry flight conditions relevant to the next generation Multi Purpose Crew Vehicle return from Mars and Near Earth Objects.
14. Demonstration of Polysaccharide Capsule in Campylobacter jejuni Using Electron Microscopy
OpenAIRE
Karlyshev, Andrey V.; McCrossan, Maria V.; Wren, Brendan W.
2001-01-01
Recently, we reported that Campylobacter jejuni, an important gastrointestinal pathogen, has the genetic determinants to produce a capsular polysaccharide (Karlyshev et al., Mol. Microbiol. 35:529–541, 2000). Despite these data, the presence of a capsule in these bacteria has remained controversial. In this study we stain C. jejuni cells with the cationic dye Alcian blue and demonstrate for the first time by electron microscopy that C. jejuni cells produce a polysaccharide capsule that is ret...
15. Polysaccharide capsule-mediated resistance to opsonophagocytosis in Klebsiella pneumoniae.
OpenAIRE
Domenico, P; Salo, R J; Cross, A S; Cunha, B A
1994-01-01
The polysaccharide capsule of Klebsiella pneumoniae is an important virulence factor that confers resistance to phagocytosis. The treatment of encapsulated bacteria with salicylate to inhibit capsule expression was found to enhance the phagocytosis of encapsulated bacteria by human neutrophils only in the presence of cell surface-specific antibodies. Both type-specific rabbit antisera and anticapsular human hyperimmune globulin were employed as opsonins. Salicylate significantly enhanced phag...
16. The association of metabolic syndrome markers with adhesive capsulitis.
Science.gov (United States)
Austin, Daniel C; Gans, Itai; Park, Min Jung; Carey, James L; Kelly, John D
2014-07-01
Research has associated adhesive capsulitis with diabetes mellitus but suggests that glucose-mediated injury may begin before diabetes is diagnosed. The period preceding diabetes is often marked by metabolic syndrome. We investigated the relationship between metabolic syndrome components (insulin resistance, hypertension, dyslipidemia, and obesity) and the development of adhesive capsulitis using a case-control study. We retrospectively reviewed 150 consecutive adhesive capsulitis patient charts to determine the prevalence of obesity and of medications used for treating metabolic syndrome elements and compared these with previously reported nationwide values. The prevalence of anti-hyperglycemia medications in the adhesive capsulitis cohort was 18.4% (95% confidence interval [CI], 12.9%-25.7%), twice the national rate of diagnosed diabetes of 7.6% (95% CI, 6.7%-8.5%). In the 20- to 39-year-old group, the prevalence of anti-hyperglycemic medications, 26.3% (95% CI, 11.8%-48.8%), was over 10 times the nationwide rate. The overall prevalence of hypertensive medication use in the adhesive capsulitis group, 33.1% (95% CI, 25.9%-41.2%), was notably higher than the nationwide rate, 21.6% (95% CI, 19.8%-23.4%). In the 40- to 64-year-old group, the prevalence of hypertensive medication use, 36.8% (95% CI, 28.6%-46.0%), was notably higher than the nationwide rate of 24.5% (95% CI, 22.2%-27.0%). The prevalence of anti-lipid medications and obesity was similar between the groups. The relationship between adhesive capsulitis and metabolic syndrome remains unclear. Our results confirm previous work associating hyperglycemia with adhesive capsulitis. We have also shown a possible association of hypertension, part of metabolic syndrome and a proinflammatory condition, with adhesive capsulitis, which has not been previously described. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.
17. Editorial Commentary: Recalcitrant Idiopathic Adhesive Capsulitis of the Shoulder.
Science.gov (United States)
Yoo, Jae Chul
2017-03-01
An investigation of recalcitrant idiopathic adhesive capsulitis of the shoulder showed good outcomes with arthroscopic capsular release. However, it is critical that future authors carefully define the term "recalcitrant idiopathic adhesive capsulitis" so that we are speaking the same language and that future authors include a control (nonsurgical) treatment group to better determine whether surgery is truly superior to nonsurgical treatment. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
18. PHYSIOTHERAPY INTERVENTIONS FOR ADHESIVE CAPSULITIS OF SHOULDER: A SYSTEMATIC REVIEW
OpenAIRE
Jacob Isaac Jason; Ganesh Sundaram S; Vengata Subramani M
2015-01-01
Objective: The purpose of this study was to conduct a systematic review on various physiotherapy management for adhesive capsulitis of shoulder. Methods: A search of the literature was conducted using Clinical Key, ProQuest and PEDro databases up to September 2015. Search limits included the English language and human studies. Search terms included adhesive capsulitis, frozen shoulder, Physical therapy, Physiotherapy etc. Inclusion criteria: Systematic reviews and randomised controlled ...
19. Arthroscopic treatment of refractory adhesive capsulitis of the shoulder
OpenAIRE
Fernandes, Marcos Rassi
2014-01-01
OBJECTIVE: to evaluate the results of arthroscopic treatment of refractory adhesive capsulitis of the shoulder associated as for improved range of motion after a minimum follow up of six years. METHODS: from August 2002 to December 2004, ten patients with adhesive capsulitis of the shoulder resistant to conservative treatment underwent arthroscopic surgery. One interscalene catheter was placed for postoperative analgesia before the procedure. All were in Phase II, with a minimum follow up o...
20. Effectiveness of Maitland Techniques in Idiopathic Shoulder Adhesive Capsulitis
OpenAIRE
Kumar, Abhay; Kumar, Suraj; Aggarwal, Anoop; Kumar, Ratnesh; Das, Pooja Ghosh
2012-01-01
Objective. To study the effectiveness of Maitland techniques in the treatment of idiopathic shoulder adhesive capsulitis. Methods. total of 40 patients diagnosed with idiopathic shoulder adhesive capsulitis were recruited and randomly allocated into two groups. In Group A ( ) subjects were treated with Maitland mobilization technique and common supervised exercises, whereas subjects in Group B ( ) only received common supervised exercises. Variables. Shoulder pain and disability index (SPADI)...
1. Polarized Light Corridor Demonstrations.
Science.gov (United States)
Davies, G. R.
1990-01-01
Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)
2. Super-resolution longitudinally polarized light needle achieved by tightly focusing radially polarized beams
Science.gov (United States)
Shi, Chang-kun; Nie, Zhong-quan; Tian, Yan-ting; Liu, Chao; Zhao, Yong-chuang; Jia, Bao-hua
2018-01-01
Based on the vector diffraction theory, a super-resolution longitudinally polarized optical needle with ultra-long depth of focus ( DOF) is generated by tightly focusing a radially polarized beam that is modulated by a self-designed ternary hybrid (phase/amplitude) filter (THF). Both the phase and the amplitude patterns of THF are judiciously optimized by the versatile particle swarm optimization (PSO) searching algorithm. For the focusing configuration with a combination of a high numerical aperture ( NA) and the optimized sine-shaped THFs, an optical needle with the full width at half maximum ( FWHM) of 0.414λ and the DOF of 7.58λ is accessed, which corresponds to an aspect ratio of 18.3. The demonstrated longitudinally polarized super-resolution light needle with high aspect ratio opens up broad applications in high-density optical data storage, nano-photolithography, super-resolution imaging and high-efficiency particle trapping.
3. The external rotation test in the diagnosis of adhesive capsulitis.
Science.gov (United States)
Wolf, Eugene M; Cox, Wesley K
2010-05-12
This article evaluates the effectiveness of the external rotation test in diagnosing capsulitis. The test is performed with the upper arm in a neutral position at the patient's side and the elbow in 90 degrees of flexion. The test is positive when pain is produced with this maneuver. All patients (379) evaluated for atraumatic shoulder pain during 1 calendar year were studied. The patients were divided into external rotation positive (91 patients) and external rotation negative (311 patients) groups. Patients with atraumatic shoulder pain with a positive external rotation test were presumed to have adhesive capsulitis in the absence of glenohumeral arthritis. Patients diagnosed with adhesive capsulitis received an intra-articular steroid injection and a home therapy program. Patients were contacted 10 to 19 months following treatment to determine their status and need for any further care. A diagnosis of adhesive capsulitis was made in 75% of external rotation positive patients (68 patients). Glenohumeral arthritis evidenced by radiographs was the only other diagnosis that produced a positive external rotation test (23 patients) in this group of atraumatic shoulders. Only 1 of 68 patients (1.4%) with a diagnosis of adhesive capsulitis (external rotation positive) had surgery during the follow-up period. However, 86 of 311 (27.7%) patients in the external rotation negative group underwent surgery (Padhesive capsulitis in the absence of glenohumeral arthritis. Copyright 2010, SLACK Incorporated.
4. Colloidal capsules: nano- and microcapsules with colloidal particle shells.
Science.gov (United States)
Bollhorst, Tobias; Rezwan, Kurosch; Maas, Michael
2017-04-18
Utilizing colloidal particles for the assembly of the shell of nano- and microcapsules holds great promise for the tailor-made design of new functional materials. Increasing research efforts are devoted to the synthesis of such colloidal capsules, by which the integration of modular building blocks with distinct physical, chemical, or morphological characteristics in a capsule's shell can result in novel properties, not present in previous encapsulation structures. This review will provide a comprehensive overview of the synthesis strategies and the progress made so far of bringing nano- and microcapsules with shells of densely packed colloidal particles closer to application in fields such as chemical engineering, materials science, or pharmaceutical and life science. The synthesis routes are categorized into the four major themes for colloidal capsule formation, i.e. the Pickering-emulsion based formation of colloidal capsules, the colloidal particle deposition on (sacrificial) templates, the amphiphilicity driven self-assembly of nanoparticle vesicles from polymer-grafted colloids, and the closely related field of nanoparticle membrane-loading of liposomes and polymersomes. The varying fields of colloidal capsule research are then further categorized and discussed for micro- and nano-scaled structures. Finally, a special section is dedicated to colloidal capsules for biological applications, as a diverse range of reports from this field aim at pharmaceutical agent encapsulation, targeted drug-delivery, and theranostics.
5. Capsule Development and Utilization for Material Irradiation Tests
International Nuclear Information System (INIS)
Kang, Young Hwan; Kim, B. G.; Joo, K. N.
2003-05-01
The objective of this project was to establish basic capsule irradiation technology using the multi-purpose research reactor [HANARO] to eventually support national R and D projects of advanced fuel and materials related to domestic nuclear power plants and next generation reactors. There are several national nuclear projects in KAERI, which require several irradiation tests to investigate in-pile behavior of nuclear reactor fuel and materials for the R and D of several types of fuels such as advanced PWR and DUPIC fuels and for the R and D of structural materials such as RPV(reactor pressure vessel) steel, Inconel, zirconium alloy, and stainless steel. At the moment, internal and external researchers in institutes, industries and universities are interested in investigating the irradiation characteristics of materials using the irradiation facilities of HANARO. For these kinds of material irradiation tests, it is important to develop various capsules using our own techniques. The development of capsules requires several leading-edge technologies and our own experiences related to design and fabrication. In the second phase from April 1,2000 to March 31, 2003, the utilization technologies were developed using various sensors for the measurements of temperature, pressure and displacement, and instrumented capsule technologies for the required fuel irradiation tests were developed. In addition, the improvement of the existing capsule technologies and the development of an in-situ measurable creep capsule for specific purposes were done to meet the various requirements of users
6. Capsule colonoscopy increases uptake of colorectal cancer screening
Directory of Open Access Journals (Sweden)
Groth Stefan
2012-06-01
Full Text Available Abstract Background Screening colonoscopy effectiveness is hampered by limited adherence by the general population. The present prospective study was performed to evaluate whether adding capsule colonoscopy to the endoscopic screening options increases uptake. Methods Invitation letters were sent to 2150 persons above the age of 55 insured with a German medical insurance company in the area of Rinteln, Lower Saxony with a baseline spontaneous annual screening colonoscopy uptake of 1 %. Both capsule or conventional colonoscopy were offered. Interested persons were given information about the two screening options by four local gastroenterologists and examinations were then performed according to screenees’ final choice. Results 154 persons sought further information, and 34 and 90 underwent conventional and capsule colonoscopy, respectively. Colonoscopy uptake was thus increased by the invitation process by 60 % (1.6 % vs. 1 %; p = 0.075, while the option of capsule endoscopy led to a fourfold increase of screening uptake (4.2 % vs. 1 %, p Conclusions The present study suggests that offering the option of capsule colonoscopy increases uptake of endoscopic colorectal cancer screening. However, capsule endoscopy sensitivity for adenoma detection needs to be improved.
7. Failure of the capsule for coated particles irradiation
International Nuclear Information System (INIS)
Yamaki, Jikei; Nomura, Yasushi; Nagamatsuya, Takaaki; Yamahara, Takeshi; Sakai, Haruyuki
1975-10-01
During operation cycle No. 27 of the JMTR (Japan Material Testing Reactor) on May 20, 1974, leakage of the fission product gas occurred from the capsule 72F-7A, which contained coated particles for the irradiation; the coated particles are for the development of a multi-purpose high temperature gas cooled reactor. The capsule was designed for heat 1600 0 C. Three nickel plates as the heat reflector were sandwiched in between the plates of titanium and zirconium, which were adsorbents for the impurity gases in the cladding tube (Nb-1%Zr). Temperatures of the plates were about 1000 0 C under the irradiation, so one metal diffused into the other metal through interfaces, resulting in the formation of an alloy. Its melting point was lower than those of metals in the capsule. The cladding material Nb-1%Zr was melted by the alloy and finally a pin hole developed through the cladding. The process of failure, design of the capsule, post-irradiation test of the capsule and the failure-reproducing experiment with a mock-up capsule are described. (auth.)
8. Design and fabrication of non-instrumented capsule
Energy Technology Data Exchange (ETDEWEB)
Kim, Yong Sung; Lee, Jeong Young; Kim, Joon Yeon; Lee, Sung Ho; Ji, Dae Young; Kim, Suk Hoon; Ahn, Sung Ho [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1995-04-01
The use of non-instrumented capsule designed and fabricated in this time is for the evaluation of material irradiation performance, it is to be installed in the inner core of HANARO. The design process of non-instrumented capsule was accomplished by the decision of the quality of material and the shape, thermal analysis, structural analysis. The temperature of the specimen and the stress in capsule during irradiation test was calculated by the thermal analysis and the structural analysis. GGENGTC code and ABAQUS code were used for the calculation of non-instrumented capsule. In case of installing the capsule in irradiation hole, the coolant flow rate and the pressure drop in the hole is changed, which will affect the coolant flow rate of the fuel region. Eventually the coolant flow rate outside capsule have to be restricted to the allowable range. In order to obtain the required pressure drop, the flow rate control mechanism, end plate and orifice ring were used in this test. The test results are compared with 36-element fuel pressure drop data which AECL performed by the SCTR facility.
9. Polarized Moessbauer transitions
International Nuclear Information System (INIS)
Barb, D.
1975-01-01
Theoretical aspects of the emission, absorption and scattering of polarized gamma rays are reviewed for a general case of combined magnetic and electric hyperfine interactions; various possibilities of obtaining polarized gamma sources are described and examples are given of the applications of Moessbauer spectroscopy with polarized gamma rays in solving problems of solid state physics. (A.K.)
10. Interannual Variability of the Meridional Width of the Baiu Rainband in June and the Associated Large-Scale Atmospheric Circulations
Science.gov (United States)
Tsuji, K.; Tomita, T.
2016-12-01
Baiu front, which is defined as a boundary between tropical and polar air masses in the East Asia-western North Pacific sector in boreal early summer, slowly migrates northward with the daily meridional swings. Thus, the interannual variability of meridional width of the baiu rainband reflects the slow northward migration and the daily meridional swings of the baiu front. This study focuses on the meridional width of baiu rainband only in June when the baiu front extends on Japan, and investigates how the width is related to the rainfall of Japan with discussions of associated anomalous large-scale atmospheric circulations. The meridional width of baiu rainband is defined based on the monthly-mean precipitation rate of June, whose threshold is 5mm day-1 that is averaged in 130°-150°E. There is a significant positive correlation between the variations of southern and northern edges of the baiu rainband in June. However, the interannual variance of the southern edge is almost twice larger than that of the northern one. That is, the interannual variability of the meridional width is chiefly caused by the variations of southern edge, and the contribution of northern ones is small. When the meridonal width is narrow (wide), an anomalous anticyclonic (cyclonic) circulation appears to the south of Japan, and the precipitation rate increases (decreases) in the western part of Japan while decreases (increases) in the counterpart. In other words, a local dipole with a node at 140°E appears around Japan in the baiu rainfall anomalies. The anomalous anticyclonic (cyclonic) circulation to the south of Japan, which controls the interannual variability of meridional width of the baiu rainband, is induced by the strength of Indian summer monsoon. When the convective activity of Indian summer monsoon is strong (week), the Tibetan high in the upper troposphere extends more (less) eastward. The induced stronger (weaker) descent leads stronger (weaker) Bonin high in the western
11. Downstream flow top width prediction in a river system | Choudhury ...
African Journals Online (AJOL)
ANFIS, ARIMA and Hybrid Multiple Inflows Muskingum models (HMIM) were applied to simulate and forecast downstream discharge and flow top widths in a river system. The ANFIS model works on a set of linguistic rules while the ARIMA model uses a set of past values to predict the next value in a time series. The HMIM ...
12. Crack width analysis of steel fibers reinforced concrete beams
Directory of Open Access Journals (Sweden)
Šahinagić-Isović Merima
2017-01-01
Full Text Available Fibre reinforced concrete in recent years has grown from experimental material to a practical usable material, due to its positive properties such as increased tensile strength, bending strength, toughness etc. However, still there are many unanswered questions that are the subject of many research. In this paper results and analysis of crack width of concrete beams with steel fibres are presented. This analysis considers influence of steel fibre addition on the crack width of reinforced concrete beams (dimensions 15/28/300 cm loaded up to fracture during short-term ultimate static load with one unloading cycle. Concrete beams were made of two types of concrete: ordinary strength concrete (OSC - C30/37 and high strength concrete (HSC - C60/70, with and without 0.45% of steel fibres. The results indicate that there is a significant influence of fibre addition on crack width, especially for ordinary concrete. At the end, empirical calculations of the concrete elements' crack width with steel fibres according to the recommendations of RILEM and ACI building code are given.
13. Detonation cell widths in hydrogen-air-diluent mixtures
International Nuclear Information System (INIS)
Stamps, D.W.
1990-01-01
In this paper I report on the influence of steam and carbon dioxide on the detonability of hydrogen-air mixtures. Data were obtained on the detonation cell width in a heated detonation tube that is 0.43 m in diameter and 13.1 m long. The detonation cell widths were correlated using a characteristic length calculated from a chemical kinetic model. The addition of either diluent to a hydrogen-air mixture increased the cell width for all equivalence ratios. For equal diluent concentrations, however, carbon dioxide not only yielded larger increases in the cell width than steam, but its efficacy relative to steam was predicted to increase with increasing concentration. The range of detonable hydrogen concentrations in a hydrogen-air mixture initially at 1 atm pressure was found to be between 11.6 percent and 74.9 percent for mixtures at 20 degree C and 9.4 percent and 76.9 percent for mixtures at 100 degree C. The detonation limit was between 38.8 percent and 40.5 percent steam for a stoichiometric hydrogen-air-steam mixture initially at 100 degree C and 1 atm. 10 refs., 4 figs., 1 tab
14. Prediction of concentrated flow width in ephemeral gully channels
Science.gov (United States)
Nachtergaele, J.; Poesen, J.; Sidorchuk, A.; Torri, D.
2002-07-01
Empirical prediction equations of the form W = aQb have been reported for rills and rivers, but not for ephemeral gullies. In this study six experimental data sets are used to establish a relationship between channel width (W, m) and flow discharge (Q, m3 s-1) for ephemeral gullies formed on cropland. The resulting regression equation (W = 2·51 Q0·412; R2 = 0·72; n = 67) predicts observed channel width reasonably well. Owing to logistic limitations related to the respective experimental set ups, only relatively small runoff discharges (i.e. Q channel width was attributed to a calculated peak runoff discharge on sealed cropland, the application field of the regression equation was extended towards larger discharges (i.e. 5 × 10channels revealed that the discharge exponent (distribution over the wetted perimeter between rills, gullies and rivers, (ii) a decrease in probability of a channel formed in soil material with uniform erosion resistance from rills over gullies to rivers and (iii) a decrease in average surface slope from rills over gullies to rivers.channel width equation for concentrated flow on cropland. For the frozen soils the equation
15. Echo width of foam supports used in scattering measurements
DEFF Research Database (Denmark)
Appel-Hansen, Jørgen; Solodukhov, V. V.
1979-01-01
Theoretically and experimentally determined echo widths of dielectric cylinders having circular, triangular, and quadratic cross sections have been compared. The cylinders were made of foam material having a relative dielectric constant of about 1.035. The purpose of the investigation was to find...
16. Joint space width in dysplasia of the hip
DEFF Research Database (Denmark)
Jacobsen, Steffen; Sonne-Holm, Stig; Søballe, K
2005-01-01
. Neither subjects with dysplasia nor controls had radiological signs of ongoing degenerative disease at admission. The primary radiological discriminator of degeneration of the hip was a change in the minimum joint space width over time. There were no significant differences between these with dysplasia...
17. Femoral Intercondylar Notch (ICN) width in Nigerians: Its ...
African Journals Online (AJOL)
It is suggested that the difference could be the result of dominant use of one foot over the other or to occupational habit. This needs further investigation. The Femoral Intercondylar Notch (ICN) width is not related to Femur length as no relationship was found to exist between the two (p > 0.05). We conclude that since ...
18. Utility Interfaced Pulse-Width Modulation of Solar Fed Voltage ...
African Journals Online (AJOL)
This paper describes a utility interfaced pulse-width modulation of solar-fed voltage source single phase full bridge inverter. The proposed system has to do with the conversion of solar energy into electrical energy; boosting the dc power; inversion of the dc to ac and then synchronization of the inverter output with the utility, ...
19. Frequency width of open channels in multiple scattering media
NARCIS (Netherlands)
Bosch, J.; Goorden, S.A.; Mosk, Allard
2016-01-01
We report optical measurements of the spectral width of open transmission channels in a three-dimensional diffusive medium. The light transmission through a sample is enhanced by efficiently coupling to open transmission channels using repeated digital optical phase conjugation. The spectral
20. Writer identification using directional ink-trace width measurements
NARCIS (Netherlands)
Brink, A. A.; Smit, J.; Bulacu, M. L.; Schomaker, L. R. B.
As suggested by modern paleography, the width of ink traces is a powerful source of information for off-line writer identification, particularly if combined with its direction. Such measurements can be computed using simple, fast and accurate methods based on pixel contours, the combination of which
1. The effect of buffer zone width on biodiversity
DEFF Research Database (Denmark)
Navntoft, Søren; Sigsgaard, Lene; Kristensen, Kristian
2012-01-01
Field margin management for conservation purposes is a way to protect both functional biodiversity and biodiversity per se without considerable economical loss as field margins are less productive. However, the effect of width of the buffer zone on achievable biodiversity gains has received little...
2. Development of a sealing process of capsules for surveillance test tubes of the vessel in nuclear power plants
International Nuclear Information System (INIS)
Romero C, J.; Fernandez T, F.; Perez R, N.; Rocamontes A, M.; Garcia R, R.
2007-01-01
The surveillance capsule is composed by the support, three capsules for impact test tubes, five capsules for tension test tubes and one porta dosemeters. The capsules for test tubes are of two types: rectangular capsule for Charpy test tubes and cylindrical capsule for tension test tubes. This work describes the development of the welding system to seal the capsules for test tubes that should contain helium of ultra high purity to a pressure of 1 atmosphere. (Author)
3. Influence of MLC leaf width on biologically adapted IMRT plans
Energy Technology Data Exchange (ETDEWEB)
Roedal, Jan; Soevik, Aaste; Malinen, Eirik (Dept. of Medical Physics, The Norwegian Radium Hospital, Oslo Univ. Hospital, Oslo (Norway)), E-mail: jan.rodal@radiumhospitalet.no
2010-10-15
Introduction. High resolution beam delivery may be required for optimal biology-guided adaptive therapy. In this work, we have studied the influence of multi leaf collimator (MLC) leaf widths on the treatment outcome following adapted IMRT of a hypoxic tumour. Material and methods. Dynamic contrast enhanced MR images of a dog with a spontaneous tumour in the nasal region were used to create a tentative hypoxia map following a previously published procedure. The hypoxia map was used as a basis for generating compartmental gross tumour volumes, which were utilised as planning structures in biologically adapted IMRT. Three different MLCs were employed in inverse treatment planning, with leaf widths of 2.5 mm, 5 mm and 10 mm. The number of treatment beams and the degree of step-and-shoot beam modulation were varied. By optimising the tumour control probability (TCP) function, optimal compartmental doses were derived and used as target doses in the inverse planning. Resulting IMRT dose distributions and dose volume histograms (DVHs) were exported and analysed, giving estimates of TCP and compartmental equivalent uniform doses (EUDs). The impact of patient setup accuracy was simulated. Results. The MLC with the smallest leaf width (2.5 mm) consistently gave the highest TCPs and compartmental EUDs, assuming no setup error. The difference between this MLC and the 5 mm MLC was rather small, while the MLC with 10 mm leaf width gave considerably lower TCPs. When including random and systematic setup errors, errors larger than 5 mm gave only small differences between the MLC types. For setup errors larger than 7 mm no differences were found between non-uniform and uniform dose distributions. Conclusions. Biologically adapted radiotherapy may require MLCs with leaf widths smaller than 10 mm. However, for a high probability of cure it is crucial that accurate patient setup is ensured.
4. Modeling of dislocation channel width evolution in irradiated metals
Science.gov (United States)
Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.
2018-02-01
Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. Based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopy (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Further, examinations of the effect of the so-called "source-broadening" mechanism of channel formation showed that its effect is simply to add a minimum thickness to the channel
5. Electrotherapy modalities for adhesive capsulitis (frozen shoulder).
Science.gov (United States)
Page, Matthew J; Green, Sally; Kramer, Sharon; Johnston, Renea V; McBain, Brodwen; Buchbinder, Rachelle
2014-10-01
Adhesive capsulitis (also termed frozen shoulder) is a common condition characterised by spontaneous onset of pain, progressive restriction of movement of the shoulder and disability that restricts activities of daily living, work and leisure. Electrotherapy modalities, which aim to reduce pain and improve function via an increase in energy (electrical, sound, light, thermal) into the body, are often delivered as components of a physical therapy intervention. This review is one in a series of reviews which form an update of the Cochrane review 'Physiotherapy interventions for shoulder pain'. To synthesise the available evidence regarding the benefits and harms of electrotherapy modalities, delivered alone or in combination with other interventions, for the treatment of adhesive capsulitis. We searched CENTRAL, MEDLINE, EMBASE, CINAHL Plus and the ClinicalTrials.gov and World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) clinical trials registries up to May 2014, unrestricted by language, and reviewed the reference lists of review articles and retrieved trials to identify any other potentially relevant trials. We included randomised controlled trials (RCTs) and controlled clinical trials using a quasi-randomised method of allocation that included adults with adhesive capsulitis and compared any electrotherapy modality to placebo, no treatment, a different electrotherapy modality, or any other intervention. The two main questions of the review focused on whether electrotherapy modalities are effective compared to placebo or no treatment, or if they are an effective adjunct to manual therapy or exercise (or both). The main outcomes of interest were participant-reported pain relief of 30% or greater, overall pain, function, global assessment of treatment success, active shoulder abduction, quality of life, and the number of participants experiencing any adverse event. Two review authors independently selected trials for inclusion
6. The Physics of Polarization
Science.gov (United States)
Landi Degl'Innocenti, Egidio
2015-10-01
The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.
7. Scattering Light by а Cylindrical Capsule with Arbitrary End Caps in the Rayleigh-Gans-Debye Approximation
Directory of Open Access Journals (Sweden)
K. A. Shapovalov
2015-01-01
Full Text Available The paper concerns the light scattering problem of biological objects of complicated structure.It considers optically “soft” (having a refractive index close to that of a surrounding medium homogeneous cylindrical capsules, composed of three parts: central one that is cylindrical and two symmetrical rounding end caps. Such capsules can model more broad class of biological objects than the ordinary shapes of a spheroid or sphere. But, unfortunately, if a particle has other than a regular geometrical shape, then it is very difficult or impossible to solve the scattering problem analytically in its most general form that oblige us to use numerical and approximate analytical methods. The one of such approximate analytical method is the Rayleigh-Gans-Debye approximation (or the first Born approximation.So, the Rayleigh-Gans-Debye approximation is valid for different objects having size from nanometer to millimeter and depending on wave length and refractive index of an object under small phase shift of central ray.The formulas for light scattering amplitude of cylindrical capsule with arbitrary end caps in the Rayleigh-Gans-Debye approximation in scalar form are obtained. Then the light scattering phase function [or element of scattering matrix f11] for natural incident light (unpolarized or arbitrary polarized light is calculated.Numerical results for light scattering phase functions of cylindrical capsule with conical, spheroidal, paraboloidal ends in the Rayleigh-Gans-Debye approximation are compared. Also numerical results for light scattering phase function of cylindrical capsule with conical ends in the Rayleigh-Gans-Debye approximation and in the method of Purcell-Pennypacker (or Discrete Dipole method are compared. The good agreement within an application range of the RayleighGans-Debye approximation is obtained.Further continuation of the work, perhaps, is a consideration of multilayer cylindrical capsule in the Rayleigh
8. The effect of myofibroblasts and corticosteroid injections in adhesive capsulitis.
Science.gov (United States)
Hettrich, Carolyn M; DiCarlo, Edward F; Faryniarz, Deborah; Vadasdi, Katherine B; Williams, Riley; Hannafin, Jo A
2016-08-01
Adhesive capsulitis is a condition that results in restricted glenohumeral motion. Fibroblasts have been implicated in the disease process; however, their role as a contractile element in the development of fibrosis and capsular contracture is not well understood. We hypothesized (1) that myofibroblast prevalence in capsular biopsy specimens from patients with adhesive capsulitis would be increased compared with controls and (2) that patients treated with an intra-articular injection of corticosteroid would have fewer myofibroblasts. The study prospectively enrolled 20 consecutive patients with adhesive capsulitis scheduled for capsular release and matched controls. Tissue samples were collected from the posterior and anterior capsule for histomorphologic and immunohistologic analyses. Identical sectioning and preparation was performed in 14 additional adhesive capsulitis specimens from patients who had not received corticosteroid injections. Patients with adhesive capsulitis not treated with preoperative corticosteroid demonstrated more histologic evidence of fibromatosis, synovial hyperplasia, and an increase in positive staining for α-smooth muscle actin than patients who had received intra-articular injections of steroid. No specimens obtained from control patients demonstrated positive staining for α-smooth muscle actin. There was a higher prevalence of myofibroblast staining in patients with adhesive capsulitis, implicating activation of the myofibroblast in the pathophysiology of capsular contracture. Intra-articular steroid injection decreases the presence and amount of fibromatosis, vascular hyperplasia, fibrosis, and the presence of fibroblasts staining for α-smooth muscle actin. This supports the use of steroid injections to alter the disease process by decreasing the pathologic changes found in the capsular tissue. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
9. Overview of technical solutions and assessment of clinical usefulness of capsule endoscopy.
Science.gov (United States)
Koprowski, Robert
2015-12-01
The paper presents an overview of endoscopic capsules with particular emphasis on technical aspects. It indicates common problems in capsule endoscopy such as: (1) limited wireless communication (2) the use of capsule endoscopy in the case of partial patency of the gastrointestinal tract, (3) limited imaging area, (4) external capsule control limitations. It also presents the prospects of capsule endoscopy, the most recent technical solutions for biopsy and the mobility of the capsule in the gastrointestinal tract. The paper shows the possibilities of increasing clinical usefulness of capsule endoscopy resulting from technological limitations. Attention has also been paid to the current role of capsule endoscopy in screening tests and the limitations of its effectiveness. The paper includes the author's recommendations concerning the direction of further research and the possibility of enhancing the scope of capsule endoscopy.
10. Simple discretization method for autoionization widths. III. Molecules
International Nuclear Information System (INIS)
Macas, A.; Martn, F.; Riera, A.; Yanez, M.
1987-01-01
We apply a new method to calculate widths of two-electron Feshbach resonances, which was described in detail and applied to atomic systems in preceding articles (this issue), to molecular and quasimolecular autoionizing states. For simplicity in the programming effort, we restrict our calculations to the small-R region where one-centered expansions are sufficiently accurate to describe the wave functions. As test cases, positions and widths for the H 2 , He 2 /sup 2+/, HeH + , and LiHe/sup 3+/ resonances of lowest energy are computed for R<0.6 a.u. The advantage of using block-diagonalization techniques to define diabatic resonant states instead of generalizing the Feshbach formalism is pointed out
11. A Direct Measurement of the $W$ Decay Width
Energy Technology Data Exchange (ETDEWEB)
Vine, Troy [Univ. of College, London (United Kingdom)
2008-08-01
A direct measurement of the W boson total decay width is presented in proton-antiproton collisions at √s = 1.96 TeV using data collected by the CDF II detector. The measurement is made by fitting a simulated signal to the tail of the transverse mass distribution in the electron and muon decay channels. An integrated luminosity of 350 pb-1 is used, collected between February 2002 and August 2004. Combining the results from the separate decay channels gives the decay width as 2.038 ± 0.072 GeV in agreement with the theoretical prediction of 2.093 ± 0.002 GeV. A system is presented for the management of detector calibrations using a relational database schema. A description of the implementation and monitoring of a procedure to provide general users with a simple interface to the complete set of calibrations is also given.
12. Determination of the width of the top quark.
Science.gov (United States)
Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Ancu, L S; Aoki, M; Arnoud, Y; Arov, M; Askew, A; Åsman, B; Atramentov, O; Avila, C; BackusMayes, J; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bazterra, V; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Blazey, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brandt, O; Brock, R; Brooijmans, G; Bross, A; Brown, D; Brown, J; Bu, X B; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burnett, T H; Buszello, C P; Calpas, B; Camacho-Pérez, E; Carrasco-Lizarraga, M A; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chen, G; Chevalier-Théry, S; Cho, D K; Cho, S W; Choi, S; Choudhary, B; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Croc, A; Cutts, D; Ćwiok, M; Das, A; Davies, G; De, K; de Jong, S J; De la Cruz-Burelo, E; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; DeVaughan, K; Diehl, H T; Diesburg, M; Dominguez, A; Dorland, T; Dubey, A; Dudko, L V; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fuess, S; Gadfort, T; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerbaudo, D; Gerber, C E; Gershtein, Y; Ginther, G; Golovanov, G; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Hagopian, S; Haley, J; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Head, T; Hebbeker, T; Hedin, D; Hegab, H; Heinson, A P; Heintz, U; Hensel, C; Heredia-De la Cruz, I; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hossain, S; Hubacek, Z; Huske, N; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jamin, D; Jesik, R; Johns, K; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Joshi, J; Juste, A; Kaadze, K; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Khatidze, D; Kirby, M H; Kohli, J M; Kozelov, A V; Kraus, J; Kumar, A; Kupco, A; Kurča, T; Kuzmin, V A; Kvita, J; Lammers, S; Landsberg, G; Lebrun, P; Lee, H S; Lee, S W; Lee, W M; Lellouch, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna-Garcia, R; Lyon, A L; Maciel, A K A; Mackin, D; Madar, R; Magaña-Villalba, R; Malik, S; Malyshev, V L; Maravin, Y; Martínez-Ortega, J; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Menezes, D; Mercadante, P G; Merkin, M; Meyer, A; Meyer, J; Mondal, N K; Muanza, G S; Mulhearn, M; Nagy, E; Naimuddin, M; Narain, M; Nayyar, R; Neal, H A; Negret, J P; Neustroev, P; Novaes, S F; Nunnemann, T; Obrant, G; Orduna, J; Osman, N; Osta, J; Otero y Garzón, G J; Owen, M; Padilla, M; Pangilinan, M; Parashar, N; Parihar, V; Park, S K; Parsons, J; Partridge, R; Parua, N; Patwa, A; Penning, B; Perfilov, M; Peters, K; Peters, Y; Petrillo, G; Pétroff, P; Piegaia, R; Piper, J; Pleier, M-A; Podesta-Lerma, P L M; Podstavkov, V M; Pol, M-E; Polozov, P; Popov, A V; Prewitt, M; Price, D; Protopopescu, S; Qian, J; Quadt, A; Quinn, B; Rangel, M S; Ranjan, K; Ratoff, P N; Razumov, I; Renkel, P; Rich, P; Rijssenbeek, M; Ripp-Baudot, I; Rizatdinova, F; Rominsky, M; Royon, C; Rubinov, P; Ruchti, R; Safronov, G; Sajot, G; Sánchez-Hernández, A; Sanders, M P; Sanghi, B; Santos, A S; Savage, G; Sawyer, L; Scanlon, T; Schamberger, R D; Scheglov, Y; Schellman, H; Schliephake, T; Schlobohm, S; Schwanenberger, C; Schwienhorst, R; Sekaric, J; Severini, H; Shabalina, E; Shary, V; Shchukin, A A; Shivpuri, R K; Simak, V; Sirotenko, V; Skubic, P; Slattery, P; Smirnov, D; Smith, K J; Snow, G R; Snow, J; Snyder, S; Söldner-Rembold, S; Sonnenschein, L; Sopczak, A; Sosebee, M; Soustruznik, K; Spurlock, B; Stark, J; Stolin, V; Stoyanova, D A; Strauss, E; Strauss, M; Strom, D; Stutte, L; Svoisky, P; Takahashi, M; Tanasijczuk, A; Taylor, W; Titov, M; Tokmenin, V V; Tsybychev, D; Tuchming, B; Tully, C; Tuts, P M; Uvarov, L; Uvarov, S; Uzunyan, S; Van Kooten, R; van Leeuwen, W M; Varelas, N; Varnes, E W; Vasilyev, I A; Verdier, P; Vertogradov, L S
2011-01-14
We extract the total width of the top quark, Γ(t), from the partial decay width Γ(t → Wb) measured using the t-channel cross section for single top-quark production and from the branching fraction B(t → Wb) measured in tt events using up to 2.3 fb(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron pp Collider. The result is Γ(t) = 1.99(-0.55)(+0.69) GeV, which translates to a top-quark lifetime of τ(t) = (3.3(-0.9)(+1.3)) × 10(-25) s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |V(tb')| < 0.63 at 95% C.L.
13. Statistical analysis of P-wave neutron reduced widths
International Nuclear Information System (INIS)
Joshi, G.C.; Agrawal, H.M.
2000-01-01
The fluctuations of the p-wave neutron reduced widths for fifty one nuclei have been analyzed with emphasis on recent measurements by a statistical procedure which is based on the method of maximum likelihood. It is shown that the p-wave neutron reduced widths of even-even nuclei fallow single channel Porter Thomas distribution (χ 2 -distribution with degree of freedom ν=1) for most of the cases where there are no intermediate structure. It is emphasized that the distribution in nuclei other than even-even may differ from a χ 2 -distribution with one degree of freedom. Possible explanation and significance of this deviation from ν=1 is given. (author)
14. The SOL width and the MHD interchange instability in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Kerner, W. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pogutse, O. [Kurchatov institute, Moscow (Russian Federation)
1994-07-01
Instabilities in the SOL plasma can strongly influence the SOL plasma behaviour and in particular the SOL width. The SOL stability analysis shows that there exists a critical ratio of the thermal energy and the magnetic energy. If the SOL beta is greater than this critical value, the magnetic field cannot prevent the plasma displacement and a strong MHD instability in the SOL occurs. In the opposite case only slower resistive instabilities can develop. A theoretical investigation of the SOL plasma stability is presented for JET single-null and double-null divertor configurations. The dependence of the stability threshold on the SOL beta and on the sheath resistance is established. Applying a simple mixing length argument gives the scaling of the SOL width. 5 refs., 2 figs.
15. The double capsules in macro-textured breast implants.
Science.gov (United States)
Giot, Jean-Philippe; Paek, Laurence S; Nizard, Nathanael; El-Diwany, Mostafa; Gaboury, Louis A; Nelea, Monica; Bou-Merhi, Joseph S; Harris, Patrick G; Danino, Michel A
2015-10-01
Breast implants are amongst the most widely used types of permanent implants in modern medicine and have both aesthetic and reconstructive applications with excellent biocompatibility. The double capsule is a complication associated with textured prostheses that leads to implant displacement; however, its etiology has yet to be elucidated. In this study, 10 double capsules were sampled from breast expander implants for in-depth analysis; histologically, the inner capsular layer demonstrated highly organized collagen in sheets with delamination of fibers. At the prosthesis interface (PI) where the implant shell contacts the inner capsular layer, scanning electron microscopy (SEM) revealed a thin layer which mirrored the three-dimensional characteristics of the implant texture; the external surface of the inner capsular layer facing the intercapsular space (ICS) was flat. SEM examination of the inner capsule layer revealed both a large bacterial presence as well as biofilm deposition at the PI; a significantly lower quantity of bacteria and biofilm were found at the ICS interface. These findings suggest that the double capsule phenomenon's etiopathogenesis is of mechanical origin. Delamination of the periprosthetic capsule leads to the creation of the ICS; the maintained separation of the 2 layers subsequently alters the biostability of the macro-textured breast implant. Copyright © 2015 Elsevier Ltd. All rights reserved.
16. A legged anchoring mechanism for capsule endoscopes using micropatterned adhesives.
Science.gov (United States)
Glass, Paul; Cheung, Eugene; Sitti, Metin
2008-12-01
This paper presents a new concept for an anchoring mechanism to enhance existing capsule endoscopes. The mechanism consists of three actuated legs with compliant feet lined with micropillar adhesives to be pressed into the intestine wall to anchor the device at a fixed location. These adhesive systems are inspired by gecko and beetle foot hairs. Single-leg and full capsule mathematical models of the forces generated by the legs are analyzed to understand capsule performance. Empirical friction models for the interaction of the adhesives with an intestinal substrate were experimentally determined in vitro using dry and oil-coated elastomer micropillar arrays with 140 microm pillar diameter, 105 microm spacing between pillars, and an aspect ratio of 1:1 on fresh porcine small intestine specimens. Capsule prototypes were also tested in a simulated intestine environment and compared with predicted peristaltic loads to assess the viability of the proposed design. The experimental results showed that a deployed 10 gr capsule robot can withstand axial peristaltic loads and anchor reliably when actuation forces are greater than 0.27 N using dry micropillars. Required actuation forces may be reduced significantly by using micropillars coated with a thin silicone oil layer.
17. Controlled release from stimuli-sensitive microgel capsules
Science.gov (United States)
Masoud, Hassan; Alexeev, Alexander
2011-10-01
We introduce a mesoscale computational model for responsive gels, i.e. chemically cross-linked polymer networks immersed in Newtonian fluids, and use it to probe the release of nanoparticles from hollow microgel capsules that swell and deswell in response to external stimuli. Our model explicitly describes the transport of nanoparticles in swelling/deswelling polymer networks with complex geometries and associated fluid flows. Our simulations reveal that responsive microcapsules can be effectively utilized for steady and pulsatile release of encapsulated solutes. Steady, diffusive release of nanoparticle takes place from swollen gel capsules, whereas capsule deswelling cause burst-like discharge of solutes driven by a flow from the shrinking capsule interior. We demonstrate that this hydrodynamic release can be regulated by introducing rigid microscopic rods inside the capsule. Our calculations indicate that the rods stretch the deswelling membrane and promote the formation of large pores in the shell, which allow massive flow-driven release of nanoparticles. Thus, our findings unveil a new approach for regulating the release from stimulus responsive micro-carriers that will be especially useful for designing new drug delivery systems.
18. A novel release mechanism from responsive microgel capsules
Science.gov (United States)
Masoud, Hassan; Alexeev, Alexander
2011-11-01
We use a mesoscale computational model for responsive gels to study the release of nanoparticles from hollow microcapsules. Our model explicitly describes the transport of nanoparticles in swelling/deswelling polymer networks with complex geometries and associated fluid flows. Our simulations show that capsule swelling results in a steady release of encapsulated nanoparticle, which is set by the ability of particles to diffuse through the capsule network. For deswelling capsules, we show that a fluid flow induced by capsule shrinking leads to rapid nanoparticle release. This release, however, is limited due to decreasing mesh size of the deswelling shell. We show that by introducing solid microrods inside deswelling capsules, we can control the rapid release. Our calculations reveal that the rods stretch the deswelling membrane and promote the formation of large pores in the shell, which allow massive flow-driven release of nanoparticles. Thus, our findings reveal a new approach for regulating the release from stimulus responsive micro-carriers that may be useful for designing new drug delivery systems. Financial support from the Donors of the PetroleumResearchFund, administered by theACS, is gratefully acknowledged.
19. Thermohydraulic design of saturated temperature capsule for IASCC irradiation test
International Nuclear Information System (INIS)
Ide, Hiroshi; Matsui, Yoshinori; Itabashi, Yukio
2002-10-01
An advanced water chemistry controlled irradiation research device is being developed in JAERI, to perform irradiation tests for irradiation assisted stress corrosion cracking (IASCC) research concerned with aging of LWR. This device enables the irradiation tests under the water chemistry condition and the temperature, which simulate the conditions for BWR core internals. The advanced water chemistry controlled irradiation research device is composed of saturated temperature capsule inserted into the JMTR core and the water chemistry control unit installed in the reactor building. Regarding the saturated temperature capsule, the Thermohydraulic design of capsule structure was done, aimed at controlling the specimen's temperature, feeding water velocity on specimen's surface to the environment of BWR nearer. As the result of adopting the new capsule structure based on the design study, it was found out that feeding water velocity at the surface of specimen's is increased to about 10 times as much as before, and nuclear heat generated in the capsule components can be removed safely even in the abnormal event such as the case of loss of feeding water. (author)
20. Thermohydraulic design of saturated temperature capsule for IASCC irradiation test
Energy Technology Data Exchange (ETDEWEB)
Ide, Hiroshi; Matsui, Yoshinori; Itabashi, Yukio [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others
2002-10-01
An advanced water chemistry controlled irradiation research device is being developed in JAERI, to perform irradiation tests for irradiation assisted stress corrosion cracking (IASCC) research concerned with aging of LWR. This device enables the irradiation tests under the water chemistry condition and the temperature, which simulate the conditions for BWR core internals. The advanced water chemistry controlled irradiation research device is composed of saturated temperature capsule inserted into the JMTR core and the water chemistry control unit installed in the reactor building. Regarding the saturated temperature capsule, the Thermohydraulic design of capsule structure was done, aimed at controlling the specimen's temperature, feeding water velocity on specimen's surface to the environment of BWR nearer. As the result of adopting the new capsule structure based on the design study, it was found out that feeding water velocity at the surface of specimen's is increased to about 10 times as much as before, and nuclear heat generated in the capsule components can be removed safely even in the abnormal event such as the case of loss of feeding water. (author)
1. A modular and programmable development platform for capsule endoscopy system.
Science.gov (United States)
Khan, Tareq Hasan; Shrestha, Ravi; Wahid, Khan A
2014-06-01
The state-of-the-art capsule endoscopy (CE) technology offers painless examination for the patients and the ability to examine the interior of the gastrointestinal tract by a noninvasive procedure for the gastroenterologists. In this work, a modular and flexible CE development system platform consisting of a miniature field programmable gate array (FPGA) based electronic capsule, a microcontroller based portable data recorder unit and computer software is designed and developed. Due to the flexible and reprogrammable nature of the system, various image processing and compression algorithms can be tested in the design without requiring any hardware change. The designed capsule prototype supports various imaging modes including white light imaging (WLI) and narrow band imaging (NBI), and communicates with the data recorder in full duplex fashion, which enables configuring the image size and imaging mode in real time during examination. A low complexity image compressor based on a novel color-space is implemented inside the capsule to reduce the amount of RF transmission data. The data recorder contains graphical LCD for real time image viewing and SD cards for storing image data. Data can be uploaded to a computer or Smartphone by SD card, USB interface or by wireless Bluetooth link. Computer software is developed that decompresses and reconstructs images. The fabricated capsule PCBs have a diameter of 16 mm. An ex-vivo animal testing has also been conducted to validate the results.
2. [Future prospects in digestive endoscopy: wireless capsule endoscopy].
Science.gov (United States)
Sacher-Huvelin, S; Bourreille, A; Le Rhun, M; Galmiche, J-P
2009-01-01
Since the beginning of the millennium, the development of wireless capsule endoscopy has represented a major technological advance. The capsule is ingested by the patient and images are transmitted via several sensors positioned on the skin of the patient and downloaded in a computer system. The first applications were focused on the exploration of the small bowel which was previously considered as an obscure area for conventional endoscopy. Wireless capsule endoscopy of the small bowel is now an established technique with many acknowledged indications for the diagnosis of obscure bleeding, anemia of presumed digestive origin, Crohn's disease and small bowel tumors. Recently, thanks to technological progresses, novel capsules have been developed for specific segments of the gut namely the oesophagus and the colon. Recent data suggest that these new capsules could have potential applications for the diagnosis of oesophageal varices, Barrett's oesophagus and for the screening and/or surveillance of polyps of the colon. However, further studies are required before such strategies could be approved for clinical use or even replace conventional endoscopic modalities. In the long-term, progresses in signal processing as well as in the miniaturisation of sensors or markers may lead to a new generation of endoscopic robots. This technological breakthrough may ultimately result in new concepts and change current practice of digestive endoscopy.
3. Wireless powered capsule endoscopy for colon diagnosis and treatment.
Science.gov (United States)
Chen, Wenwen; Yan, Guozheng; He, Shu; Ke, Quan; Wang, Zhiwu; Liu, Hua; Jiang, Pingping
2013-11-01
This paper presents a wireless power transfer system integrated with an active locomotion and biopsy module in an endoscopic capsule for colon inspection. The capsule, which can move automatically, is designed for non-invasive biopsy and visual inspection of the intestine. To supply enough power for multiple functions and ensure safety for the human body, the efficiency of the current power transmission system needs to be improved. To take full advantage of the volume in the capsule body, a novel structure of receiving coils wound on a multi-core of MnZn ferrite hollow cylinder was used; with this new core, the efficiency increased to more than 7.98%. Up to 1.4 W of dc power can be delivered to the capsule as it travels along the gastrointestinal tract. Three micro motors were integrated for pumping, anchoring, locomotion and biopsy. A user interface and RF communication enables the operator to drive the capsule in an intuitive manner. To gauge the efficacy of the wireless power supply in a simulated real-world application, the biopsy and locomotion capabilities of the device were successfully tested in a slippery, soft tube and gut environment in vitro.
4. Regional material properties of the human hip joint capsule ligaments.
Science.gov (United States)
Hewitt, J; Guilak, F; Glisson, R; Vail, T P
2001-05-01
The hip joint capsule functions to constrain translation between the femur and acetabulum while allowing rotational and planar movements. Despite the crucial role it plays in the pathogenesis of hip instability, little is known about its biomechanical properties. The goal of this study was to determine the regional material properties of the iliofemoral and ischiofemoral ligaments of the capsule. Ten human cadaveric specimens of each ligament were tested to failure in tension. The stress at failure, strain at failure, strain energy density at failure, toe- and linear-region elastic moduli, and the Poisson's ratio were measured for each ligament. The strain to failure was greatest in the ischiofemoral ligament, while no significant difference was noted in failure stress by region or ligament. The Young's moduli of elasticity ranged from 76.1 to 285.8 MPa among the different ligaments, and were generally consistent with properties previously reported for the shoulder capsule. The elastic moduli and strain energy density at failure differed by region. No significant differences in Poisson's ratio were found by region or ligament. The average Poisson's ratio was approximately 1.4, consistent with anisotropic behavior of ligamentous tissues. Understanding the material properties of the hip capsule may help the orthopaedic surgeon better understand normal ligament function, and thereby choose a surgical approach or strategy of repair. Furthermore, knowledge of the normal mechanical function of the hip capsule ligaments could assist in the evaluation of the success of a repair.
5. Numerical Solution of the Modified Equal Width Wave Equation
Directory of Open Access Journals (Sweden)
Seydi Battal Gazi Karakoç
2012-01-01
Full Text Available Numerical solution of the modified equal width wave equation is obtained by using lumped Galerkin method based on cubic B-spline finite element method. Solitary wave motion and interaction of two solitary waves are studied using the proposed method. Accuracy of the proposed method is discussed by computing the numerical conserved laws 2 and ∞ error norms. The numerical results are found in good agreement with exact solution. A linear stability analysis of the scheme is also investigated.
6. Pulse-Width-Modulating Driver for Brushless dc Motor
Science.gov (United States)
Salomon, Phil M.
1991-01-01
High-current pulse-width-modulating driver for brushless dc motor features optical coupling of timing signals from low-current control circuitry to high-current motor-driving circuitry. Provides high electrical isolation of motor-power supply, helping to prevent fast, high-current motor-driving pulses from being coupled through power supplies into control circuitry, where they interfere with low-current control signals.
7. Synchronization Technique for Random Switching Frequency Pulse-Width Modulation
OpenAIRE
Apinan Aurasopon; Worawat Sa-ngiavibool
2008-01-01
This paper proposes a synchronized random switching frequency pulse width modulation (SRSFPWM). In this technique, the clock signal is used to control the random noise frequency which is produced by the feedback voltage of a hysteresis circuit. These make the triangular carrier frequency equaling to the random noise frequency in each switching period with the symmetrical positive and negative slopes of triangular carrier. Therefore, there is no error voltage in PWM signal. The PSpice simulate...
8. Penning ionization widths by Fano-algebraic diagrammatic construction method
Science.gov (United States)
Yun, Renjie; Narevicius, Edvardas; Averbukh, Vitali
2018-03-01
We present an ab initio theory and computational method for Penning ionization widths. Our method is based on the Fano theory of resonances, algebraic diagrammatic construction (ADC) scheme for many-electron systems, and Stieltjes imaging procedure. It includes an extension of the Fano-ADC scheme [V. Averbukh and L. S. Cederbaum, J. Chem. Phys. 123, 204107 (2005)] to triplet excited states. Penning ionization widths of various He*-H2 states are calculated as a function of the distance R between He* and H2. We analyze the asymptotic (large-R) dependences of the Penning widths in the region where the well-established electron transfer mechanism of the decay is suppressed by the multipole- and/or spin-forbidden energy transfer. The R-12 and R-8 power laws are derived for the asymptotes of the Penning widths of the singlet and triplet excited states of He*(1s2s1,3S), respectively. We show that the electron transfer mechanism dominates Penning ionization of He*(1s2s 3S)-H2 up until the He*-H2 separation is large enough for the radiative decay of He* to become the dominant channel. The same mechanism also dominates the ionization of He*(1s2s 1S)-H2 when R < 5 Å. We estimate that the regime of energy transfer in the He*-H2 Penning ionization cannot be reached by approaching zero collisional temperature. However, the multipole-forbidden energy transfer mechanism can become important for Penning ionization in doped helium droplets.
9. Pole mass, width, and propagators of unstable fermions
International Nuclear Information System (INIS)
Kniehl, B.A.; Sirlin, A.
2008-01-01
The concepts of pole mass and width are extended to unstable fermions in the general framework of parity-nonconserving gauge theories, such as the Standard Model. In contrast with the conventional on-shell definitions, these concepts are gauge independent and avoid severe unphysical singularities, properties of great importance since most fundamental fermions in nature are unstable particles. General expressions for the unrenormalized and renormalized dressed propagators of unstable fermions and their field-renormalization constants are presented. (orig.)
10. Computer aided wireless capsule endoscopy video segmentation.
Science.gov (United States)
Li, Baopu; Xu, Guoqing; Zhou, Ran; Wang, Tianfu
2015-02-01
Wireless capsule endoscopy (WCE) opens a new door for the digestive tract examination and diagnosis. However, the examination of its video data is tedious. This study aims to assist a physician to interpret a WCE video by segmenting it into different anatomic parts in the digestive tract. A two level WCE video segmentation scheme is proposed to locate the boundary between the stomach, small intestine, and large intestine. In the rough level, the authors utilize color feature to draw a dissimilarity curve for a WCE video and obtain an approximate boundary. Meanwhile, training data for the fine level segmentation can be collected automatically between the two approximate boundaries of organs to overcome the difficulty of training data collection in traditional approaches. In the fine level, color histogram in the HSI color space is used to segment the stomach and small intestine. Then, color uniform local binary pattern (CULBP) algorithm is applied for discrimination of the small intestine and large intestine, which includes two patterns, namely, color norm and color angle pattern. The CULBP feature is robust to variation of illumination and discriminative for classification. In order to increase the performance of support vector machine, the authors integrate it with the Adaboost approach. Finally, the authors refine the classification results to segment a WCE video into different parts, that is, the stomach, small intestine, and large intestine. The average precision and recall are 91.2% and 90.6% for the stomach/small intestine classification, 89.2% and 88.7% for the small/large intestine discrimination. Paired t-test also demonstrates a significant better performance of the proposed scheme compared to some traditional methods. The average segmentation error is 8 frames for the stomach/small intestine discrimination, and 14 frames for the small/large intestine segmentation. The results have demonstrated that the new video segmentation method can accurately locate
11. Biomechanics of the Hip Capsule and Capsule Management Strategies in Hip Arthroscopy.
Science.gov (United States)
Nepple, Jeffrey J; Smith, Matthew V
2015-12-01
Recent advances in our understanding of the function of the hip capsule have clarified its importance to normal hip function and kinematics. The iliofemoral ligament is the primary stabilizing structure for controlling anterior translation and external rotation of the hip, and is violated by the arthroscopic interportal capsulotomy. Microinstability of the hip occurring after surgical trauma remains a poorly defined clinical entity. In certain at-risk populations, capsular repair should be considered as part of an arthroscopic hip procedure to achieve optimal outcomes and avoid iatrogenic instability (dislocation or microinstability). Despite a lack of conclusive evidence-based indications, we recommend capsular repair in the settings of borderline hip dysplasia (or dysplastic variants such as increased femoral anteversion), hip hypermobility, connective tissue disorders, and traumatic or atraumatic instability. With careful attention to arthroscopic capsular management, adequate exposure can be achieved and reproducibly allow for an effective capsular repair when indicated.
12. Balance (perceived and actual) and preferred stance width during pregnancy.
Science.gov (United States)
Jang, John; Hsiao, Katherine T; Hsiao-Wecksler, Elizabeth T
2008-05-01
Pregnant women often remark that their balance degrades during pregnancy; however, it appears that no studies have documented the gravida's perception of her balance nor measured direction-specific changes in balance throughout pregnancy or after delivery. Thirty women, fifteen pregnant and fifteen non-pregnant controls, were tested monthly and through 6-month postpartum. For each session, perceived degradation in sense of balance, laboratory-based balance measures, stance width, and the number of falls since the previous session were recorded. Laboratory-based balance measures, quantified by direction-specific measures of postural sway, were computed from ten 30s quiet-standing trials on a stationary force platform. Repeated-measures analysis of variance, paired t-tests, and Pearson correlations were use to examine group and time effects. For the pregnant group, perceived balance degradation and stance width were highly correlated (r = 0.94). Both increased during pregnancy (P r > 0.72) and also decreased significantly between the third trimester and postpartum (P pregnancy, but increased after delivery. Contrary to recent work suggesting fall rates of 25%, only 13% of our subjects (n = 2) fell during pregnancy. Perceived degradation in balance during pregnancy was strongly related to increasing postural sway instability in the anterior-posterior direction. Lateral stability was maintained during pregnancy and likely accomplished by increasing stance width.
13. Predictors of the peak width for networks with exponential links
Science.gov (United States)
Troutman, B.M.; Karlinger, M.R.
1989-01-01
We investigate optimal predictors of the peak (S) and distance to peak (T) of the width function of drainage networks under the assumption that the networks are topologically random with independent and exponentially distributed link lengths. Analytical results are derived using the fact that, under these assumptions, the width function is a homogeneous Markov birth-death process. In particular, exact expressions are derived for the asymptotic conditional expectations of S and T given network magnitude N and given mainstream length H. In addition, a simulation study is performed to examine various predictors of S and T, including N, H, and basin morphometric properties; non-asymptotic conditional expectations and variances are estimated. The best single predictor of S is N, of T is H, and of the scaled peak (S divided by the area under the width function) is H. Finally, expressions tested on a set of drainage basins from the state of Wyoming perform reasonably well in predicting S and T despite probable violations of the original assumptions. ?? 1989 Springer-Verlag.
14. Measurement of the mass and width of the W boson
CERN Document Server
Abbiendi, G.; Akesson, P.F.; Alexander, G.; Anagnostou, G.; Anderson, K.J.; Asai, S.; Axen, D.; Bailey, I.; Barberio, E.; Barillari, T.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brown, Robert M.; Burckhart, H.J.; Campana, S.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, D.G.; Ciocca, C.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Gagnon, P.; Gary, John William; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harel, A.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herten, G.; Heuer, R.D.; Hill, J.C.; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kramer, T.; Krasznahorkay, A.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, A.; Ludwig, J.; Mader, W.; Marcellini, S.; Martin, A.J.; Mashimo, T.; Mattig, Peter; McKenna, J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Meyer, Niels T.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Roney, J.M.; Rossi, A.M.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schorner-Sadenius, T.; Schroder, Matthias; Schumacher, M.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija
2006-01-01
The mass and width of the W boson are measured using e+e- -> W+W- events from the data sample collected by the OPAL experiment at LEP at centre-of-mass energies between 170 GeV and 209 GeV. The mass (mw) and width (gw) are determined using direct reconstruction of the kinematics of W+W- -> qqbarlv and W+W- -> qqbarqqbar events. When combined with previous OPAL measurements using W+W- -> lvlv events and the dependence on mw of the WW production cross-section at threshold, the results are determined to be mw = 80.415 +- 0.042 +- 0.030 +- 0.009 GeV gw = 1.996 +- 0.096 +- 0.102 +- 0.003 GeV where the first error is statistical, the second systematic and the third due to uncertainties in the value of the LEP beam energy. By measuring mw with several different jet algorithms in the qqbarqqbar channel, a limit is also obtained on possible final-state interactions due to colour reconnection effects in W+W- -> qqbarqqbar events. The consistency of the results for the W mass and width with those inferred from other ele...
15. Stark widths regularities within spectral series of sodium isoelectronic sequence
Science.gov (United States)
Trklja, Nora; Tapalaga, Irinel; Dojčinović, Ivan P.; Purić, Jagoš
2018-02-01
Stark widths within spectral series of sodium isoelectronic sequence have been studied. This is a unique approach that includes both neutrals and ions. Two levels of problem are considered: if the required atomic parameters are known, Stark widths can be calculated by some of the known methods (in present paper modified semiempirical formula has been used), but if there is a lack of parameters, regularities enable determination of Stark broadening data. In the framework of regularity research, Stark broadening dependence on environmental conditions and certain atomic parameters has been investigated. The aim of this work is to give a simple model, with minimum of required parameters, which can be used for calculation of Stark broadening data for any chosen transitions within sodium like emitters. Obtained relations were used for predictions of Stark widths for transitions that have not been measured or calculated yet. This system enables fast data processing by using of proposed theoretical model and it provides quality control and verification of obtained results.
16. [Review] Polarization and Polarimetry
Science.gov (United States)
Trippe, Sascha
2014-02-01
Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.
17. A New Kind of Circular Polarization Leaky-Wave Antenna Based on Substrate Integrated Waveguide
Directory of Open Access Journals (Sweden)
Chong Zhang
2015-01-01
Full Text Available A new kind of circular polarization leaky-wave antenna with N-shaped slots cut in the upper side of substrate integrated waveguide (SIW is investigated and presented. The radiation pattern and polarization axial ratio of the leaky-wave antenna are studied. The results show that the width of N-shaped slots has significant effect on the circular polarization property of the antenna. By properly choosing structural parameters, the SIW based leaky-wave antenna can realize circular polarization with excellent axial ratio in 8 GHz satellite band.
18. Polarization feedback laser stabilization
Science.gov (United States)
Esherick, P.; Owyoung, A.
1987-09-28
A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.
19. Polarization in Sagittarius A*
OpenAIRE
Bower, Geoffrey C.
2000-01-01
We summarize the current state of polarization observations of Sagittarius A*, the compact radio source and supermassive black hole candidate in the Galactic Center. These observations are providing new tools for understanding accretion disks, jets and their environments. Linear polarization observations have shown that Sgr A* is unpolarized at frequencies as high as 86 GHz. However, recent single-dish observations indicate that Sgr A* may have strong linear polarization at frequencies higher...
20. Sensitive Detection of Deliquescent Bacterial Capsules through Nanomechanical Analysis.
Science.gov (United States)
Nguyen, Song Ha; Webb, Hayden K
2015-10-20
Encapsulated bacteria usually exhibit strong resistance to a wide range of sterilization methods, and are often virulent. Early detection of encapsulation can be crucial in microbial pathology. This work demonstrates a fast and sensitive method for the detection of encapsulated bacterial cells. Nanoindentation force measurements were used to confirm the presence of deliquescent bacterial capsules surrounding bacterial cells. Force/distance approach curves contained characteristic linear-nonlinear-linear domains, indicating cocompression of the capsular layer and cell, indentation of the capsule, and compression of the cell alone. This is a sensitive method for the detection and verification of the encapsulation status of bacterial cells. Given that this method was successful in detecting the nanomechanical properties of two different layers of cell material, i.e. distinguishing between the capsule and the remainder of the cell, further development may potentially lead to the ability to analyze even thinner cellular layers, e.g. lipid bilayers.
1. Adhesive capsulitis and dynamic splinting: a controlled, cohort study
Science.gov (United States)
Gaspar, Paul D; Willis, F Buck
2009-01-01
Background Adhesive Capsulitis (AC) affects patient of all ages, and stretching protocols are commonly prescribed for this condition. Dynamic splinting has been shown effective in contracture reduction from pathologies including Trismus to plantar fasciitis. The purpose of this study was to examine the efficacy of dynamic splinting on patients with AC. Methods This controlled, cohort study, was conducted at four physical therapy, sports medicine clinics in Texas and California. Sixty-two patients diagnosed with Stage II Adhesive Capsulitis were grouped by intervention. The intervention categories were as follows: Group I (Control); Group II (Physical Therapy exclusively with standardized protocols); Group III; (Shoulder Dynasplint system exclusively); Group IV (Combined treatment with Shoulder Dynasplint and standardized Physical Therapy). The duration of this study was 90 days for all groups, and the main outcome measures were change in active, external rotation. Results Significant difference was found for all treatment groups (p adhesive Capsulitis. Trial Registration Trial Number: NCT00873158 PMID:19735563
2. Swallowable Wireless Capsule Endoscopy: Progress and Technical Challenges
Directory of Open Access Journals (Sweden)
Guobing Pan
2012-01-01
Full Text Available Wireless capsule endoscopy (WCE offers a feasible noninvasive way to detect the whole gastrointestinal (GI tract and revolutionizes the diagnosis technology. However, compared with wired endoscopies, the limited working time, the low frame rate, and the low image resolution limit the wider application. The progress of this new technology is reviewed in this paper, and the evolution tendencies are analyzed to be high image resolution, high frame rate, and long working time. Unfortunately, the power supply of capsule endoscope (CE is the bottleneck. Wireless power transmission (WPT is the promising solution to this problem, but is also the technical challenge. Active CE is another tendency and will be the next geneion of the WCE. Nevertheless, it will not come true shortly, unless the practical locomotion mechanism of the active CE in GI tract is achieved. The locomotion mechanism is the other technical challenge, besides the challenge of WPT. The progress about the WPT and the active capsule technology is reviewed.
3. Evaluation of hard gelatin capsules and hydroxypropyl methylcellulose containing ampicillin
Directory of Open Access Journals (Sweden)
Graziella Gonçalves Weigert
2012-01-01
Full Text Available This study aims to develop and evaluate formulations containing ampicillin in capsules of gelatin and hydroxypropyl methylcellulose (HPMC. Two formulations (A and B were developed. The final product quality was evaluated by testing for quality control and the results were in agreement with the Brazilian Pharmacopoeia. The formulations with HPMC capsules showed lower percentages of drug dissolved (99.67%, HPMC-A and 87.70%, HPMC-B than the gelatin (100.18%, GEL-A and 101.16% GEL-B. Because of the delay of the ampicillin release observed in the dissolution profiles, it becomes necessary to evaluate the drugs that can be conditioned in the HPMC capsules.
4. Validating Inertial Confinement Fusion (ICF) predictive capability using perturbed capsules
Science.gov (United States)
Schmitt, Mark; Magelssen, Glenn; Tregillis, Ian; Hsu, Scott; Bradley, Paul; Dodd, Evan; Cobble, James; Flippo, Kirk; Offerman, Dustin; Obrey, Kimberly; Wang, Yi-Ming; Watt, Robert; Wilke, Mark; Wysocki, Frederick; Batha, Steven
2009-11-01
Achieving ignition on NIF is a monumental step on the path toward utilizing fusion as a controlled energy source. Obtaining robust ignition requires accurate ICF models to predict the degradation of ignition caused by heterogeneities in capsule construction and irradiation. LANL has embarked on a project to induce controlled defects in capsules to validate our ability to predict their effects on fusion burn. These efforts include the validation of feature-driven hydrodynamics and mix in a convergent geometry. This capability is needed to determine the performance of capsules imploded under less-than-optimum conditions on future IFE facilities. LANL's recently initiated Defect Implosion Experiments (DIME) conducted at Rochester's Omega facility are providing input for these efforts. Recent simulation and experimental results will be shown.
5. Ingestible wireless capsules for enhanced diagnostic inspection of gastrointestinal tract
Science.gov (United States)
Rasouli, Mahdi; Kencana, Andy Prima; Huynh, Van An; Ting, Eng Kiat; Lai, Joshua Chong Yue; Wong, Kai Juan; Tan, Su Lim; Phee, Soo Jay
2011-03-01
Wireless capsule endoscopy has become a common procedure for diagnostic inspection of gastrointestinal tract. This method offers a less-invasive alternative to traditional endoscopy by eliminating uncomfortable procedures of the traditional endoscopy. Moreover, it provides the opportunity for exploring inaccessible areas of the small intestine. Current capsule endoscopes, however, move by peristalsis and are not capable of detailed and on-demand inspection of desired locations. Here, we propose and develop two wireless endoscopes with maneuverable vision systems to enhance diagnosis of gastrointestinal disorders. The vision systems in these capsules are equipped with mechanical actuators to adjust the position of the camera. This may help to cover larger areas of the digestive tract and investigate desired locations. The preliminary experimental results showed that the developed platform could successfully communicate with the external control unit via human body and adjust the position of camera to limited degrees.
6. Swallowable Wireless Capsule Endoscopy: Progress and Technical Challenges
Science.gov (United States)
Pan, Guobing; Wang, Litong
2012-01-01
Wireless capsule endoscopy (WCE) offers a feasible noninvasive way to detect the whole gastrointestinal (GI) tract and revolutionizes the diagnosis technology. However, compared with wired endoscopies, the limited working time, the low frame rate, and the low image resolution limit the wider application. The progress of this new technology is reviewed in this paper, and the evolution tendencies are analyzed to be high image resolution, high frame rate, and long working time. Unfortunately, the power supply of capsule endoscope (CE) is the bottleneck. Wireless power transmission (WPT) is the promising solution to this problem, but is also the technical challenge. Active CE is another tendency and will be the next geneion of the WCE. Nevertheless, it will not come true shortly, unless the practical locomotion mechanism of the active CE in GI tract is achieved. The locomotion mechanism is the other technical challenge, besides the challenge of WPT. The progress about the WPT and the active capsule technology is reviewed. PMID:22253621
7. Airborne Laser Polarization Sensor
Science.gov (United States)
Kalshoven, James, Jr.; Dabney, Philip
1991-01-01
Instrument measures polarization characteristics of Earth at three wavelengths. Airborne Laser Polarization Sensor (ALPS) measures optical polarization characteristics of land surface. Designed to be flown at altitudes of approximately 300 m to minimize any polarizing or depolarizing effects of intervening atmosphere and to look along nadir to minimize any effects depending on look angle. Data from measurements used in conjunction with data from ground surveys and aircraft-mounted video recorders to refine mathematical models used in interpretation of higher-altitude polarimetric measurements of reflected sunlight.
8. Polarization at SLC
International Nuclear Information System (INIS)
Swartz, M.L.
1988-07-01
The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs
9. An O antigen capsule modulates bacterial pathogenesis in Shigella sonnei.
Science.gov (United States)
Caboni, Mariaelena; Pédron, Thierry; Rossi, Omar; Goulding, David; Pickard, Derek; Citiulo, Francesco; MacLennan, Calman A; Dougan, Gordon; Thomson, Nicholas R; Saul, Allan; Sansonetti, Philippe J; Gerke, Christiane
2015-03-01
Shigella is the leading cause for dysentery worldwide. Together with several virulence factors employed for invasion, the presence and length of the O antigen (OAg) of the lipopolysaccharide (LPS) plays a key role in pathogenesis. S. flexneri 2a has a bimodal OAg chain length distribution regulated in a growth-dependent manner, whereas S. sonnei LPS comprises a monomodal OAg. Here we reveal that S. sonnei, but not S. flexneri 2a, possesses a high molecular weight, immunogenic group 4 capsule, characterized by structural similarity to LPS OAg. We found that a galU mutant of S. sonnei, that is unable to produce a complete LPS with OAg attached, can still assemble OAg material on the cell surface, but a galU mutant of S. flexneri 2a cannot. High molecular weight material not linked to the LPS was purified from S. sonnei and confirmed by NMR to contain the specific sugars of the S. sonnei OAg. Deletion of genes homologous to the group 4 capsule synthesis cluster, previously described in Escherichia coli, abolished the generation of the high molecular weight OAg material. This OAg capsule strongly affects the virulence of S. sonnei. Uncapsulated knockout bacteria were highly invasive in vitro and strongly inflammatory in the rabbit intestine. But, the lack of capsule reduced the ability of S. sonnei to resist complement-mediated killing and to spread from the gut to peripheral organs. In contrast, overexpression of the capsule decreased invasiveness in vitro and inflammation in vivo compared to the wild type. In conclusion, the data indicate that in S. sonnei expression of the capsule modulates bacterial pathogenesis resulting in balanced capabilities to invade and persist in the host environment.
10. An O antigen capsule modulates bacterial pathogenesis in Shigella sonnei.
Directory of Open Access Journals (Sweden)
Mariaelena Caboni
2015-03-01
Full Text Available Shigella is the leading cause for dysentery worldwide. Together with several virulence factors employed for invasion, the presence and length of the O antigen (OAg of the lipopolysaccharide (LPS plays a key role in pathogenesis. S. flexneri 2a has a bimodal OAg chain length distribution regulated in a growth-dependent manner, whereas S. sonnei LPS comprises a monomodal OAg. Here we reveal that S. sonnei, but not S. flexneri 2a, possesses a high molecular weight, immunogenic group 4 capsule, characterized by structural similarity to LPS OAg. We found that a galU mutant of S. sonnei, that is unable to produce a complete LPS with OAg attached, can still assemble OAg material on the cell surface, but a galU mutant of S. flexneri 2a cannot. High molecular weight material not linked to the LPS was purified from S. sonnei and confirmed by NMR to contain the specific sugars of the S. sonnei OAg. Deletion of genes homologous to the group 4 capsule synthesis cluster, previously described in Escherichia coli, abolished the generation of the high molecular weight OAg material. This OAg capsule strongly affects the virulence of S. sonnei. Uncapsulated knockout bacteria were highly invasive in vitro and strongly inflammatory in the rabbit intestine. But, the lack of capsule reduced the ability of S. sonnei to resist complement-mediated killing and to spread from the gut to peripheral organs. In contrast, overexpression of the capsule decreased invasiveness in vitro and inflammation in vivo compared to the wild type. In conclusion, the data indicate that in S. sonnei expression of the capsule modulates bacterial pathogenesis resulting in balanced capabilities to invade and persist in the host environment.
11. Shoulder activity level in patients with idiopathic adhesive capsulitis.
Science.gov (United States)
Lamplot, Joseph D; Lillegraven, Olivia; Brophy, Robert H
2017-09-01
Idiopathic adhesive capsulitis is a common condition resulting in painful multidirectional restriction of motion. Adhesive capsulitis may inhibit shoulder activity level, but this relationship has not been previously studied. This study tested the hypothesis that patients with idiopathic adhesive capsulitis have lower shoulder activity than sex- and age-matched controls. Seventy-two eligible patients (37 men and 35 women) with idiopathic adhesive capsulitis completed a validated shoulder activity scale that was compared with sex- and age-matched norms from a healthy population with no history of shoulder disorders. The association of shoulder activity level with patient age, sex, and American Shoulder and Elbow Surgeons and Simple Shoulder Test (SST) scores was evaluated. Overall, 58% of patients actually had higher shoulder activity scores than sex- and age-matched controls. Among patients aged 51 to 70 years, 68% of patients (73% of men and 63% of women) demonstrated higher Shoulder Activity Scale scores compared with controls. The activity level was higher among all patients aged 51 to 70 years compared with controls (10.3 ± 1.48 vs. 8 ± 0.52, P = .0067). The difference was significant for men in this age group (12.2 ± 1.7 vs. 9 ± 0.75, P = .0042). There was a statistically significant positive correlation of the Shoulder Activity Scale score with the SST score (r = 0.31, P = .009). Patients with idiopathic adhesive capsulitis do not have a lower shoulder activity level than sex- and age-matched controls, and older men may actually have a higher level of shoulder activity than controls. Shoulder activity level is correlated with the SST score in patients with idiopathic adhesive capsulitis. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
12. First beryllium capsule implosions on the National Ignition Facility
Energy Technology Data Exchange (ETDEWEB)
Kline, J. L.; Yi, S. A.; Simakov, A. N.; Olson, R. E.; Wilson, D. C.; Kyrala, G. A.; Perry, T. S.; Batha, S. H.; Zylstra, A. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Dewald, E. L.; Tommasini, R.; Ralph, J. E.; Strozzi, D. J.; MacPhee, A. G.; Callahan, D. A.; Hinkel, D. E.; Hurricane, O. A.; Milovich, J. L.; Rygg, J. R.; Khan, S. F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others
2016-05-15
The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosion shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.
13. Analysis Of The Effect Of Flow Channel Width On The Performance Of PEMFC
Directory of Open Access Journals (Sweden)
Elif Eker
2013-08-01
Full Text Available In this work, it was analysed the effect of different channel width on performance of PEM fuel cell. Current density were measured on the single cells of parallel flow fields that has 25 cm² active layer, using three different kinds of channel width. The cell width and the channel height remain constant.The results show that increasing the channel width while the cell width remains constant decreases the current density.
14. Factors affecting capsule size and production by lactic acid bacteria used as dairy starter cultures.
Science.gov (United States)
Hassan, A N; Frank, J F; Shalabi, S I
2001-02-28
The effects of sugar substrates on capsule size and production by some capsule-forming nonropy and ropy dairy starter cultures were studied. Test sugars (glucose, lactose, galactose, or sucrose) were used as a sole carbohydrate source and the presence of a capsule and its size were determined by using confocal scanning laser microscopy. Nonropy strains produced maximum capsule size when grown in milk. Strains that did not produce capsules in milk did not produce them in any other growth medium. Specific sugars required for capsule production were strain-dependent. Increasing lactose content of Elliker broth from 0.5 to 5% or adding whey protein or casein digest produced larger capsules. Whey protein concentrate stimulated production of larger capsules than did casamino acids or casitone. Some Streptococcus thermophilus strains produced capsules when grown on galactose only. Nonropy strains of Lactobacillus delbrueckii subsp. bulgaricus produced capsules on lactose, but not on glucose. A ropy strain of Lactobacillus delbrueckii subsp. bulgaricus produced a constant capsule size regardless of the growth medium. The ability of some strains of Streptococcus thermophilus to use galactose in capsule production could reduce browning of mozzarella cheese during baking by removing a source of reducing sugar. Media that do not support capsule production may improve cell harvesting.
15. Symptomatic retention of the Agile® patency capsule.
Science.gov (United States)
Egea Valenzuela, Juan; Estrella Díez, Esther; Alberca de Las Parras, Fernando
2017-06-01
The Agile® capsule has shown to be useful when evaluating the patency of the small bowel in patients prior to capsule endoscopy studies. It is a safe tool and a low rate of complications have been reported, highlighting symptomatic retention, although references in literature are scarce and it is only observed in 1.2% of the procedures. We present the case of a symptomatic retention of this device in a patient with previously known colonic Crohn's disease in who a small bowel study was indicated and was sent for prior patency test.
16. Data package for the Turkey Point material interaction test capsules
International Nuclear Information System (INIS)
Krogness, J.C.; Davis, R.B.
1979-01-01
Objective of the Materials Interaction Test (MIT) is to obtain interaction information on candidate package storage materials and geologies under prototypic temperatures in gamma and low level neutron fields. Compatibility, structural properties, and chemical transformations will be studied. The multiple test samples are contained within test capsules connected end-to-end to form a test train. Only passive instrumentation has been used to monitor temperatures and record neutron fluence. The test train contains seven capsules: three to test compatibility, two for structural tests, and two for chemical transformation studies. The materials tested are potential candidates for the spent fuel package canister and repository geologies
17. Welding iridium heat-source capsules for space missions
International Nuclear Information System (INIS)
Kanne, W.R. Jr.
1982-03-01
A remote computer-controlled welding station was developed to encapsulate radioactive PuO 2 in iridium. Weld quench cracking caused an interruption in production of capsules for upcoming space missions. Hot crack sensitivity of the DOP-26 iridium alloy was associated with low melting constituents in the grain boundaries. The extent of cracking was reduced but could not be eliminated by changes to the welding operation. An ultrasonic test was developed to detect underbead cracks exceeding a threshold size. Production was continued using the ultrasonic test to reject capsules with detectable cracks
18. Colon capsule endoscopy: Current status and future directions
Science.gov (United States)
Tal, Andrea O; Vermehren, Johannes; Albert, Jörg G
2014-01-01
Colon capsule endoscopy (CCE; PillCam Colon; Given Imaging; Yoqneam, Israel) is a minimally invasive wireless technique for the visualization of the colon. With the recent introduction of the second generation colon capsule the diagnostic accuracy of CCE for polyp detection has significantly improved and preliminary data suggest it may be useful to monitor mucosal inflammation in patients with inflammatory bowel disease. Limitations include the inability to take biopsies and the procedural costs. However, given the potentially higher acceptance within an average risk colorectal cancer (CRC) screening population, its usefulness as a screening tool with regard to CRC prevention should be further evaluated. PMID:25469027
19. Wireless endoscopy in 2020: Will it still be a capsule?
Science.gov (United States)
Koulaouzidis, Anastasios; Iakovidis, Dimitris K; Karargyris, Alexandros; Rondonotti, Emanuele
2015-05-07
Currently, the major problem of all existing commercial capsule devices is the lack of control of movement. In the future, with an interface application, the clinician will be able to stop and direct the device into points of interest for detailed inspection/diagnosis, and therapy delivery. This editorial presents current commercially-available new designs, European projects and delivery capsule and gives an overview of the progress required and progress that will be achieved -according to the opinion of the authors- in the next 5 year leading to 2020.
20. Advances in pediatric gastroenterology: introducing video camera capsule endoscopy.
Science.gov (United States)
Siaw, Emmanuel O
2006-04-01
The video camera capsule endoscope is a gastrointestinal endoscope approved by the U.S. Food and Drug Administration in 2001 for use in diagnosing gastrointestinal disorders in adults. In 2003, the agency approved the device for use in children ages 10 and older, and the endoscope is currently in use at Arkansas Children's Hospital. A capsule camera, lens, battery, transmitter and antenna together record images of the small intestine as the endoscope makes its way through the bowel. The instrument is used with minimal risk to the patient while offering a high degree of accuracy in diagnosing small intestine disorders.
1. The problem of the black plate with zero thickness and finite width in neutron transport theory
International Nuclear Information System (INIS)
Benoist, Pierre.
1979-08-01
A black plate with zero thickness, finite width and infinite height, imbedded in an infinite and homogeneous medium which scatters and absorbs neutrons, is considered. The problem is time-independent and the neutrons, which are supposed to have a unique speed, are issued, either from a current at infinity (problem A), or from a uniform source (problem B). It is shown that the Csub(N) method seems to be particularly well suited to the resolution of this 'two-dimensional Milne problem'. A particular interest is attached to the determination of the radius R of the black cylinder leading to the same polar behaviour of the flux at infinity as the plate (criterion 1), or absorbing the same number of neutrons as the plate (criterion 2). In this preliminary report, values of R are calculated in various limit cases: the width of the plate being taken equal to one, l being the mean free path and c the number of secondaries par collision in the outer medium, R is calculated at first in the limit l → 0 (for c = 1) by the theory of Musklelishvili, and then in the limit l → infinity (whatever c is) and c → 0 (whatever l is). In the limit c → 1 (whatever l is), R is shown to be the same in problems A and B and criteria 1 and 2. On the other hand, whatever l and c are; the values of R obtained in the problem A with the criterion 2 and in the problem B with the criterion 1 are shown to be equal. All these results allow henceforth a reasonable interpolation which can be useful in the practice [fr
2. RHIC Polarized proton operation
International Nuclear Information System (INIS)
Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D'Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.E.; Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.
2011-01-01
The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP 4 . A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above
3. RHIC Polarized proton operation
Energy Technology Data Exchange (ETDEWEB)
Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.
2011-03-28
The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above
4. Sub-Scale Re-entry Capsule Drop via High Altitude Balloons
Data.gov (United States)
National Aeronautics and Space Administration — The project objective is to develop and test a sub-scale version of the Maraia Entry Capsule on a high altitude balloon. The capsule is released at 100,000 ft. The...
5. Self collision avoidance for humanoids using circular and elliptical capsule bounding volumes
CSIR Research Space (South Africa)
Dube, C
2013-09-01
Full Text Available This paper presents a self collision avoidance scheme for humanoid robots using elliptical and circular capsules as collision bounding volumes. A capsule is defined as an elliptical or circular cylinder capped with ellipsoids or spheres respectively...
6. Model of the humanoid body for self collision detection based on elliptical capsules
CSIR Research Space (South Africa)
Dube, C
2011-12-01
Full Text Available This paper presents a self collision detection scheme for humanoid robots using elliptical and circular capsules as bounding volumes. A capsule is defined as an elliptical or circular cylinder capped with ellipsoids or spheres respectively...
7. The application value of capsule endoscopy in diagnosing small intestinal carcinoma
Directory of Open Access Journals (Sweden)
Xiaohuan Li
2018-01-01
Conclusion: Capsule endoscopy demonstrated a high diagnostic value for various small bowel diseases, including both tumor and inflammatory lesions. Given its simplicity, safety, and reliability, capsule endoscopy was an important examination tool for the diagnosis of small bowel diseases.
8. Our Polar Past
Science.gov (United States)
Clary, Renee; Wandersee, James
2009-01-01
The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…
9. Terahertz polarization imaging
NARCIS (Netherlands)
Van der Valk, N.C.J.; Van der Marel, W.A.M.; Planken, P.C.M.
2005-01-01
We present a new method to measure the polarization state of a terahertz pulse by using a modified electrooptic sampling setup. To illustrate the power of this method, we show two examples in which the knowledge of the polarization of the terahertz pulse is essential for interpreting the results:
10. Polarized proton beams
International Nuclear Information System (INIS)
Roser, T.
1995-01-01
The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders
11. Polar Science Is Cool!
Science.gov (United States)
Weeks, Sophie
2012-01-01
Children are fascinated by the fact that polar scientists do research in extremely cold and dangerous places. In the Arctic they might be viewed as lunch by a polar bear. In the Antarctic, they could lose toes and fingers to frostbite and the wind is so fast it can rip skin off. They camp on ice in continuous daylight, weeks from any form of…
12. Beam manipulating by metallic nano-slits with variant widths.
Science.gov (United States)
Shi, Haofei; Wang, Changtao; Du, Chunlei; Luo, Xiangang; Dong, Xiaochun; Gao, Hongtao
2005-09-05
A novel method is proposed to manipulate beam by modulating light phase through a metallic film with arrayed nano-slits, which have constant depth but variant widths. The slits transport electro-magnetic energy in the form of surface plasmon polaritons (SPPs) in nanometric waveguides and provide desired phase retardations of beam manipulating with variant phase propagation constant. Numerical simulation of an illustrative lens design example is performed through finite-difference time-domain (FDTD) method and shows agreement with theory analysis result. In addition, extraordinary optical transmission of SPPs through sub-wavelength metallic slits is observed in the simulation and helps to improve elements' energy using factor.
13. Width of the confining string in Yang-Mills theory.
Science.gov (United States)
Gliozzi, F; Pepe, M; Wiese, U-J
2010-06-11
We investigate the transverse fluctuations of the confining string connecting two static quarks in (2+1)D SU(2) Yang-Mills theory using Monte Carlo calculations. The exponentially suppressed signal is extracted from the large noise by a very efficient multilevel algorithm. The resulting width of the string increases logarithmically with the distance between the static quark charges. Corrections at intermediate distances due to universal higher-order terms in the effective string action are calculated analytically. They accurately fit the numerical data.
14. Bernstein width of a class of functions of finite smoothness
Science.gov (United States)
Kudryavtsev, S. N.
1999-04-01
A weak asymptotic formula is obtained for the Bernstein n-width in the space L_q(I^d) of the class F_p^{l,\\omega }(I^d) of functions on the cube I^d such that their generalized partial derivatives up to order l belong to L_p(I^d) and the moduli of continuity in the space L_p(I^d) of all their derivatives of order l are majorized by a fixed modulus of continuity \\omega.
15. Orbit width scaling of TAE instability growth rate
Energy Technology Data Exchange (ETDEWEB)
Wong, H.V.; Berk, H.L.; Breizman, B.N.
1995-07-01
The growth rate of Toroidal Alfven Eigenmodes (TAE) driven unstable by resonant coupling of energetic charged particles is evaluated in the ballooning limit over a wide range of parameters. All damping effects are ignored. Variations in orbit width, aspect ratio, and the ratio of alfven velocity to energetic particle birth velocity, are explored. The relative contribution of passing and trapped particles, and finite Larmor radius effects, are also examined. The phase space location of resonant particles with interact strongly with the modes is described. The accuracy of the analytic results with respect to growth rate magnitude and parametric dependence is investigated by comparison with numerical results.
16. Energy detection UWB system based on pulse width modulation
Directory of Open Access Journals (Sweden)
Song Cui
2014-05-01
Full Text Available A new energy detection ultra-wideband system based on pulse width modulation is proposed. The bit error rate (BER performance of this new system is slightly worst than that of a pulse position modulation (PPM system in additive white Gaussian noise channels. In multipath channels, this system does not suffer from cross-modulation interference as PPM, so it can achieve better BER performance than PPM when cross-modulation interference occurs. In addition, when synchronisation errors occur, this system is more robust than PPM.
17. Pulse-width modulated DC-DC power converters
CERN Document Server
Kazimierczuk, Marian K
2008-01-01
This book studies switch-mode power supplies (SMPS) in great detail. This type of converter changes an unregulated DC voltage into a high-frequency pulse-width modulated (PWM) voltage controlled by varying the duty cycle, then changes the PWM AC voltage to a regulated DC voltage at a high efficiency by rectification and filtering. Used to supply electronic circuits, this converter saves energy and space in the overall system. With concept-orientated explanations, this book offers state-of-the-art SMPS technology and promotes an understanding of the principle operations of PWM converters,
18. Crack widths in concrete with fibers and main reinforcement
DEFF Research Database (Denmark)
Christensen, Frede; Ulfkjær, Jens Peder; Brincker, Rune
2015-01-01
of the analytical model is to assume that the response of the structure can be described by the cracking response located within a fracture band. The model follows ideas previously used by other researchers in order to describe the fracture mechanics of concrete beams. These ideas are extended in this model to take...... relation is taken into account according to the crack width profile. Pullout of the main reinforcement is taken into account by assuming development of zones around the crack with constant friction stresses. In order to evaluate the capability of the model to produce reliable results, results are compared...
19. New insights on dyke width and upward velocity
Science.gov (United States)
Taisne, B.; Jaupart, C.; Tait, S.
2012-04-01
Striking observations have been made that challenge our understanding of magma migration through the Earth's crust. How may a volatile rich magma stall at shallow depth as a growing crypto-dome such as during the 1980 Mount Saint Helens eruption? How can we explain the width of the 2005 mega-dyke intrusion in Afar, that attained more than 8 meters with a very small amount of magma emitted at the surface? We show that changes in the geometry and the dynamics of the propagation can be attributed to density variations in the host rocks, to solidification, to volatile exsolution and expansion or to changes in the input flux of magma at depth. We focus on the relationship between dyke width and ascent rate. Shallow levels are commonly made of low density rocks or volcanic deposits with strong impact on dyke ascent. The dynamics and width of the upper part of the dyke (the nose region) are determined by a local buoyancy balance, independently of the total buoyancy of the magma column between source and tip. In such conditions, the dyke swells and slows down and, in some cases, may not breach the surface. Using laboratory experiments we show that solidification of the magma may lead to a regime of intermittent propagation, even with constant physical conditions at the source. Interestingly the time between two steps can be related to the input flux at the source region. With volatile-bearing magmas, dyke propagation proceeds in two markedly different ways depending on whether or not fragmentation occurs. With no fragmentation, magma expansion leads to acceleration and thinning of the dyke. With fragmentation, the sharp drop of head loss that occurs in gas-rich fragmented material generates large internal overpressure and swelling of the nose region, leading to deceleration of the dyke. All the above effects lead to rapid and large changes of ascent rate. Large variations of magma flux at the source would be required to have similar impacts on dyke propagation. In an
20. Precision Polarization of Neutrons
Science.gov (United States)
Martin, Elise; Barron-Palos, Libertad; Couture, Aaron; Crawford, Christopher; Chupp, Tim; Danagoulian, Areg; Estes, Mary; Hona, Binita; Jones, Gordon; Klein, Andi; Penttila, Seppo; Sharma, Monisha; Wilburn, Scott
2009-05-01
Determining polarization of a cold neutron beam to high precision is required for the next generation neutron decay correlation experiments at the SNS, such as the proposed abBA and PANDA experiments. Precision polarimetry measurements were conducted at Los Alamos National Laboratory with the goal of determining the beam polarization to the level of 10-3 or better. The cold neutrons from FP12 were polarized using optically polarized ^3He gas as a spin filter, which has a highly spin-dependent absorption cross section. A second ^ 3He spin filter was used to analyze the neutron polarization after passing through a resonant RF spin rotator. A discussion of the experiment and results will be given.
1. Optically polarized 3He
Science.gov (United States)
Gentile, T. R.; Nacher, P. J.; Saam, B.; Walker, T. G.
2018-01-01
This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements. PMID:29503479
2. Optically polarized 3He
Science.gov (United States)
Gentile, T. R.; Nacher, P. J.; Saam, B.; Walker, T. G.
2017-10-01
This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.
3. Parallel Polarization State Generation.
Science.gov (United States)
She, Alan; Capasso, Federico
2016-05-17
The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.
4. Resin Capsules: Permeable Containers for Parallel/Combinatorial Solid-Phase Organic Synthesis
OpenAIRE
Bouillon, Isabelle; Soural, Miroslav; Krchňák, Viktor
2008-01-01
A resin capsule is a permeable container for resin beads designed for multiple/combinatorial solid-phase organic synthesis. Resin capsules consist of a high density polyethylene ring sealed with peek mesh on both sides. The cylindrical shape of resin capsules enabled space-saving packing into plastic column-like reaction vessels commonly used for solid-phase organic synthesis. Resin capsules have been evaluated for their use in combinatorial synthesis, and a set of model compounds with excell...
5. A simple method for preparing radioactive capsules in colon transit study
International Nuclear Information System (INIS)
Wang Shyhjen; Lin Wanyu; Tsai Shihchuan; Chen Granhun
2000-01-01
Colon transit study is currently performed by delivering technetium-99m or indium-111 labelled activated charcoal to the colon in a methacrylate-coated capsule (coated capsule). However, the coating procedure is complicated and methacrylate has not been approved by the Food and Drug Administration. Therefore, a simpler method is needed for the clinical routine use of colon transit study. In this study, we used a commercial empty enteric capsule and a coated capsule for the measurement of colon transit time. We compared the in vitro stability and in vivo scintigraphy of 99m Tc-labelled activated charcoal in the coated capsule and the enteric capsule to evaluate the possibility of clinical usage of the enteric capsule for colon transit time study. Activated charcoal powder was mixed with 99m Tc-diethylene triamine penta-acetic acid (DTPA) and vaporized to dryness. The dry 99m Tc-DTPA activated charcoal was loaded into the coated capsule and the enteric capsule. In vitro stability study was performed by immersing these capsules in a colourless buffer of variable pH which mimicked the conditions in the stomach and the small bowel. Capsule disruption was determined. Colon transit scintigraphy with 99m Tc-DTPA charcoal was performed in five normal volunteers using these two capsules. The in vitro stability of these two types of capsule was similar and the colon transit scintigraphy findings were almost identical. Most capsules dissolved in the ascending colon and very few in the terminal ileum. It is concluded that enteric capsule is a suitable alternative to coated capsule for measurement of colon transit. (orig.)
6. A Pilot Trial of Ambulatory Monitoring of Gastric Motility Using a Modified Magnetic Capsule Endoscope
OpenAIRE
Kim, Hee Man; Choi, Ja Sung; Cho, Jae Hee
2014-01-01
The magnetic capsule endoscope has been modified to be fixed inside the stomach and to monitor the gastric motility. This pilot trial was designed to investigate the feasibility of the magnetic capsule endoscope for monitoring gastric motility. The magnetic capsule endoscope was swallowed by the healthy volunteer and maneuvered by the external magnet on his abdomen surface inside the stomach. The magnetic capsule endoscope transmitted image of gastric peristalsis. This simple trial suggested ...
7. Trismus as manifestation of bilateral internal capsule genu infarction
NARCIS (Netherlands)
Aries, M.J.H.; Vroomen, Patrick C. A. J.; van der Hoeven, Johannes H.; De Keyser, Jacques
Acute trismus can have different causes. We describe the presentation, course and radiological findings of a 34-year-old man who developed acute trismus and MRI findings consistent with the combination of an old and fresh infarction in the genu of the internal capsule. We believe it is important to
8. Langmuir and Langmuir-Blodgett films of capsules of haemoglobin ...
Indian Academy of Sciences (India)
Organized assemblies of capsules of haemoglobin (Hb), in the size range of 0.1 to 0.3 in Langmuir films have been studied at air/water interface below and above the isoelectric point. Spread films of these organizates suggest that there is no expulsion of individual particles or particle assemblies at the interface and the ...
9. Langmuir and Langmuir–Blodgett films of capsules of haemoglobin ...
Indian Academy of Sciences (India)
Abstract. Organized assemblies of capsules of haemoglobin (Hb), in the size range of 0.1 to 0.3 μ in Lang- muir films have been studied at air/water interface below and above the isoelectric point. Spread films of these organizates suggest that there is no expulsion of individual particles or particle assemblies at the interface ...
10. Adhesive capsulitis: role of MR imaging in differential diagnosis
Energy Technology Data Exchange (ETDEWEB)
Connell, David; Padmanabhan, Ravi; Buchbinder, Rachelle [Department of MRI, St. Frances Xavier Cabrini Hospital, 183 Wattletree Road, Malvern, Victoria 3144 (Australia)
2002-08-01
The purpose of this study was to describe and characterize the MR imaging findings in a group of patients who underwent surgery for adhesive capsulitis. Twenty-four MR imaging studies in 24 consecutive patients with clinical evidence of adhesive capsulitis were performed prior to arthroscopic capsulotomy. There were 17 women and 7 men with a mean age of 53.5 years. Images were scrutinised for changes in the synovium particularly in the rotator interval, around the biceps anchor and axillary pouch. Intravenous gadolinium was given routinely. We also examined a control group of 22 patients who underwent the same MR imaging protocol after referral for rotator cuff pathology. Soft tissue density showing variable enhancement after gadolinium administration was visible in the rotator interval in 22 of 24 studies on MR imaging. Seventeen patients showed soft tissue density partially encasing the biceps anchor. Ten patients showed thickening and gadolinium enhancement of the axillary pouch. Three patients from the study cohort had partial tears of the supraspinatus tendon. All the patients subsequently had surgery which confirmed fibrovascular scar tissue in the rotator interval, around the biceps anchor and a variable degree of synovial inflammation of the glenohumeral capsule. Two patients from a control group with suspected rotator cuff pathology showed abnormal intensity in the rotator interval on MR imaging. Magnetic resonance imaging can identify changes in the shoulder joint that correspond to abnormalities seen at surgery. This may be useful for discriminating adhesive capsulitis from other causes of shoulder pain. (orig.)
11. Arthroscopic treatment of refractory adhesive capsulitis of the shoulder.
Science.gov (United States)
Fernandes, Marcos Rassi
2014-01-01
to evaluate the results of arthroscopic treatment of refractory adhesive capsulitis of the shoulder associated as for improved range of motion after a minimum follow up of six years. from August 2002 to December 2004, ten patients with adhesive capsulitis of the shoulder resistant to conservative treatment underwent arthroscopic surgery. One interscalene catheter was placed for postoperative analgesia before the procedure. All were in Phase II, with a minimum follow up of two years. The mean age was 52.9 years (39-66), predominantly female (90%), six on the left shoulder. The time between onset of symptoms and surgical treatment ranged from six to 20 months. Four adhesive capsulitis were found to be primary (40%) and six secondary (60%). the preoperative mean of active anterior elevation was 92°, of external rotation was 10.5° of the L5 level internal rotation; the postoperative ones were 149°, 40° and T12 level, respectively. Therefore, the average gain was 57° for the anterior elevation, 29.5° for external rotation in six spinous processes. There was a significant difference in movements' gains between the pre and post-operative periods (padhesive capsulitis of the shoulder resistant to conservative treatment, improving the range of joint movements of patients evaluated after a minimum follow up of six years.
12. Regional gastrointestinal contractility parameters using the wireless motility capsule
DEFF Research Database (Denmark)
Farmer, A D; Wegeberg, A-M L; Brock, B
2018-01-01
BACKGROUND: The wireless motility capsule concurrently measures temperature, pH and pressure as it traverses the gastrointestinal tract. AIMS: To describe normative values for motility/contractility parameters across age, gender and testing centres. METHODS: Healthy participants underwent a stand...
13. Are Social Networking Websites Educational? Information Capsule. Volume 0909
Science.gov (United States)
Blazer, Christie
2009-01-01
More and more school districts across the country are joining social networking sites, such as Facebook and MySpace. This Information Capsule discusses the frequency with which school districts are using social networking sites, how districts are using the sites, and potential drawbacks associated with their use. Issues for districts to consider…
14. Computer-Based Assessments. Information Capsule. Volume 0918
Science.gov (United States)
Blazer, Christie
2010-01-01
This Information Capsule reviews research conducted on computer-based assessments. Advantages and disadvantages associated with computer-based testing programs are summarized and research on the comparability of computer-based and paper-and-pencil assessments is reviewed. Overall, studies suggest that for most students, there are few if any…
15. Characterization and identification of suspected counterfeit miltefosine capsules
NARCIS (Netherlands)
Dorlo, Thomas P. C.; Eggelte, Teunis A.; de Vries, Peter J.; Beijnen, Jos H.
2012-01-01
Recently, it was revealed that generic miltefosine capsules for the treatment of visceral leishmaniasis, a fatal parasitic disease, were possibly counterfeit products. Here we report on the methods to characterize and identify miltefosine in pharmaceutical products and the procedures that were used
16. Conservative integrated treatment of adhesive capsulitis of the shoulder.
Science.gov (United States)
Russo, Adriano; Arrighi, Annalisa; Vignale, Luigi; Molfetta, Luigi
2014-01-01
the aim of this study was to present the results of a conservative treatment for adhesive capsulitis based on an original protocol of combined pharmacological and rehabilitation treatment. fifty-two patients with idiopathic adhesive capsulitis were enrolled in the present study. The treatment protocol included the use of hyaluronic acid and anaesthetic periarticular and intra-articular injections followed by a specific program of capsule and muscle stretching. the results of this treatment showed complete recovery of range of motion (ROM) in 50 of the 52 cases. The mean pre-treatment ROM values were: 85° for forward elevation, 75° for abduction, 25° for external rotation, and 15° for internal rotation. The post-treatment mean ROM values showed marked improvements: 175° for forward elevation, 175° for abduction, 87.5° for external rotation and 75° for internal rotation. conservative treatment of adhesive capsulitis based on a combined pharmacological and rehabilitation approach was found to be effective in resolving pain and stiffness in 96% of the patients. level IV, therapeutic case series.
17. Assessment of colorectal length using the electromagnetic capsule tracking system
DEFF Research Database (Denmark)
Mark, E B; Poulsen, J L; Haase, A M
2017-01-01
AIM: We aimed to determine colorectal length with the 3D-Transit system by describing a 'centerline' of capsule movement and compare it to known anatomy, as determined by magnetic resonance imaging (MRI). Further, we aimed to test the day-to-day variation of colorectal length assessed with the sy...
18. Anion binding in covalent and self-assembled molecular capsules.
Science.gov (United States)
Ballester, Pablo
2010-10-01
This critical review describes selected examples extracted from the extensive literature generated during the past 42 years on the topic of anion binding in molecular capsules. The goal of including anions in molecular capsules emerges from the idea of incorporating the traits exhibited by biological receptors into synthetic ones. At the outset of this research area the capsules were unimolecular. The scaffold of the receptor was designed to covalently link a series of functional groups that could converge into a cavity and to avoid its collapse. The initial examples involved the encapsulation of one monoatomic spherical anion. With time, the cavity size of the receptor was increased and encapsulation of polyatomic anions and co-encapsulation became a reality. Synthetic economy fueled the use of aggregates of self-complementary molecules rather than one large molecule as capsules. The main purpose of this review is to give a general overview of the topic which might be of interest to supramolecular or non supramolecular chemists alike (149 references).
19. Ingestible capsule for remote controlled release of a substance
DEFF Research Database (Denmark)
2014-01-01
structure, responsive to microwave electromagnetic radiation, is attached to a first wall portion of the capsule wall structure which comprises a lossy dielectric material. At least a predetermined segment of the first wall portion is heated by received microwave electromagnetic radiation to trigger...
20. A magnetically actuated anchoring system for a wireless endoscopic capsule.
Science.gov (United States)
Zhou, Hao; Alici, Gursel; Munoz, Fredy
2016-12-01
In this study, we propose a new magnetically actuated anchoring system for wireless capsule endoscopes (WCE) by employing the principle of a switchable magnetic spring. A force model is derived to predict the magnetic force needed to support the interaction between the anchors and the intestinal lumen. The theoretical and experimental analysis conducted shows that the magnetic spring is capable of providing the force needed to activate the anchoring mechanism, which consists of four foldable legs. A prototype capsule with a size comparable with the size of a commercial WCE was designed, fabricated, and tested. The in-vitro tests with a real small intestine show that the proposed anchoring mechanism is able to raise the friction force between the anchoring legs and inner wall of the intestine by more than two times after its activation using an external magnetic field. Experimental results presented demonstrate that the proposed anchoring system, which has a low foot-print not taking up too much space on the capsule, can provide a reliable anchoring capability with the capsule inside the intestinal lumen.
1. Watermelon stomach seen by wireless‐capsule endoscopy
OpenAIRE
MASCARENHAS‐SARAIVA, M.; LOPES, L.; MASCARENHAS‐SARAIVA, A.
2003-01-01
Endoscopy. 2003 Jan;35(1):100. Watermelon stomach seen by wireless-capsule endoscopy. Mascarenhas-Saraiva M, Lopes L, Mascarenhas-Saraiva A. SourceDigestive Endoscopy and Motility Unit, Trindade Hospital, Rua Trinidade 115, 4000-541 Porto, Portugal. PMID:12510242[PubMed - indexed for MEDLINE
2. Fuel capsule HRB-21 postirradiation examination data report
Energy Technology Data Exchange (ETDEWEB)
Baldwin, C A; Bell, G L; Emerson, L C [and others
1995-04-01
HRB-21 was carried out in HFIR to demonstrate the performance capability of reference Nuclear Energy Modular High-Temperature Gas-Cooled Reactor fuel, which consisted of uranium oxycarbide fissile and ThO{sub 2} fertile TRISO particles bonded into compacts. Long before the capsule was removed from the reactor, it was obvious that the fuel was suffering early failure. After 5 of the planned 6 HFIR cycles, the peak fuel test temperature could not be controlled and the irradiation was terminated. The PIE information will be useful to fuel designers for product improvement. Irradiation-induced failure of the protective PyC layers may have led to the failure of outer PyC coatings. Coating failure fraction was determined by several means to be <1% for both fertile and fissile particles at the ends of the capsule, increasing to 6% for fissile particles and 2.5% for fertile particles at the center of the capsule. More study of SiC microstructure vs fission product release is needed. The work on capsule HRB-21 has identified a set of lessons learned that would benefit future programs.
3. Experimental Investigation of the Supersonic Wake of a Reentry Capsule
NARCIS (Netherlands)
Schrijer, F.F.J.; Walpot, L.M.G.F.M.
2010-01-01
The wake behind an Apollo shaped capsule is investigated in the framework of the ’afterbody heating’ topic in the RTO WG043 working group. Measurements are performed by means of schlieren, shadowgraphy and stereo particle image velocimetry (SPIV) and are used for CFD validation purposes. The model
4. 21 CFR 520.2605 - Trimeprazine tartrate and prednisolone capsules.
Science.gov (United States)
2010-04-01
... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.2605...) Amount. Administer either capsule orally once daily to dogs as follows: Animal weight (pounds) Number of... dermatitis (allergic, parasitic, pustular, and nonspecific). It is also used in dogs as adjunctive therapy in...
5. DEVELOPMENT OF VALUE ADDED TEA BAGS AND CAPSULES ...
African Journals Online (AJOL)
Ifedotun Aina
powdered dried leaves based on Anamed International dosage recommendations. Several studies supported the use of artemisia annua tea and capsules for the treatment of malaria pointing out that flavonoids existing in the leaves and stem considerably enhance the interest of its tea preparation and powdered leave ...
6. Biosorption of mercury by capsulated and slime layer- forming Gram ...
African Journals Online (AJOL)
ONOS
2010-09-20
Sep 20, 2010 ... The biosorption of mercury by two locally isolated Gram-ve bacilli: Klebsiella pneumoniae ssp. pneumonia (capsulated) and slime layer forming Pseudomonas aeruginosa, was characterized. Mercury adsorption was found to be influenced by the pH value of the biosorption solution, initial metal.
7. Improved sample capsule for determination of oxygen in hemolyzed blood
Science.gov (United States)
Malik, W. M.
1967-01-01
Sample capsule for determination of oxygen in hemolyzed blood consists of a measured section of polytetrafluoroethylene tubing equipped at each end with a connector and a stopcock valve. This method eliminates errors from air entrainment or from the use of mercury or syringe lubricant.
8. Hydro-dissection and posterior capsule opacifi | Bekibele | Nigerian ...
African Journals Online (AJOL)
It may however be associated with early post operative complications presumably due to increased manipulation during the procedure. Its use is therefore encouraged but with generous use of viscoelastic material to reduce effect of manipulation on the eye. Keywords: hydrodissection, posterior capsule opacity, cataract ...
9. Biosorption of mercury by capsulated and slime layerforming Gram ...
African Journals Online (AJOL)
The biosorption of mercury by two locally isolated Gram-ve bacilli: Klebsiella pneumoniae ssp. pneumonia (capsulated) and slime layer forming Pseudomonas aeruginosa, was characterized. Mercury adsorption was found to be influenced by the pH value of the biosorption solution, initial metal concentration, amount of the ...
10. Video-based measurements for wireless capsule endoscope tracking
International Nuclear Information System (INIS)
Spyrou, Evaggelos; Iakovidis, Dimitris K
2014-01-01
The wireless capsule endoscope is a swallowable medical device equipped with a miniature camera enabling the visual examination of the gastrointestinal (GI) tract. It wirelessly transmits thousands of images to an external video recording system, while its location and orientation are being tracked approximately by external sensor arrays. In this paper we investigate a video-based approach to tracking the capsule endoscope without requiring any external equipment. The proposed method involves extraction of speeded up robust features from video frames, registration of consecutive frames based on the random sample consensus algorithm, and estimation of the displacement and rotation of interest points within these frames. The results obtained by the application of this method on wireless capsule endoscopy videos indicate its effectiveness and improved performance over the state of the art. The findings of this research pave the way for a cost-effective localization and travel distance measurement of capsule endoscopes in the GI tract, which could contribute in the planning of more accurate surgical interventions. (paper)
11. Video-based measurements for wireless capsule endoscope tracking
Science.gov (United States)
Spyrou, Evaggelos; Iakovidis, Dimitris K.
2014-01-01
The wireless capsule endoscope is a swallowable medical device equipped with a miniature camera enabling the visual examination of the gastrointestinal (GI) tract. It wirelessly transmits thousands of images to an external video recording system, while its location and orientation are being tracked approximately by external sensor arrays. In this paper we investigate a video-based approach to tracking the capsule endoscope without requiring any external equipment. The proposed method involves extraction of speeded up robust features from video frames, registration of consecutive frames based on the random sample consensus algorithm, and estimation of the displacement and rotation of interest points within these frames. The results obtained by the application of this method on wireless capsule endoscopy videos indicate its effectiveness and improved performance over the state of the art. The findings of this research pave the way for a cost-effective localization and travel distance measurement of capsule endoscopes in the GI tract, which could contribute in the planning of more accurate surgical interventions.
12. Wireless capsule endoscopy in adolescents with familial adenomatous polyposis.
Science.gov (United States)
Cavallo, Debora; Ballardini, Giovanni; Ferrari, Andrea; Delconte, Gabriele; Signoroni, Stefano; Sala, Paola; Chiaravalli, Stefano; Massimino, Maura; Bertario, Lucio; Vitellaro, Marco
2016-01-01
Guidelines for surveillance in patients with familial adenomatous polyposis (FAP) recommend mutation carriers to undergo periodic colorectal examination starting in the early teens. Performing colonoscopy in children may lead to complications. Wireless capsule endoscopy (WCE) has been introduced recently to evaluate both the upper and lower gastrointestinal tract, and seems suitable as a first screening examination for adolescents. The aim of this study was to evaluate the pros and cons of WCE. This was a retrospective review of a single institution database of adolescent patients with FAP identified through the Hereditary Colorectal Tumor Registry between 2007 and 2013. The main outcomes were identification of upper and lower gastrointestinal tract polyps, tolerance of the examination, and number and size of polyps. Of 46 adolescent patients with FAP, 14 (30.4%) patients carrying adenomatous polyposis coli gene (APC) mutation, 6 male and 8 female, age (median, range) 12 (10-17) years, body mass index 19 (13-24), underwent WCE as first screening examination. The examination was completed in 13 patients (93.3%). Wireless capsule endoscopy identified the duodenal papilla in 4 patients and colonic and rectal polyps in all 13 patients. In 7 patients, fewer than 25 polyps were identified. No complications were recorded related to the use of the video capsule. Wireless capsule endoscopy is feasible and well-tolerated as a first screening examination in adolescent patients. It cannot be used as alternative to the colonoscopy, but could improve compliance with colonoscopy, and increase early adherence to a surveillance program.
13. Measurement of the Higgs decay width in the diphoton channel
CERN Document Server
Adolfsson, Jonatan
2014-01-01
In this note, a projected measurement of the Higgs decay width ($\\Gamma_{H}$) is presented, based on interference in the diphoton channel. Two different hypotheses were tested. Hypothesis A assumes that the $H\\to\\gamma\\gamma$ cross-section is proportional to $\\Gamma_{H}^{-1}$, whereas hypothesis B assumes that this cross-section is constant and instead uses the overall change in $m_{\\gamma\\gamma}$ line shape. Events were simulated using Sherpa 2.1, and were used to produce test statistics in order to obtain a 95 % confidence limit of $\\Gamma_{H}$. The standard model width was tested using Asimov data sets, which were validated using pseudo-experiments for the integrated luminosities of Run 1, Run 2 and HL-LHC. The obtained limits are significantly improved with respect to previous studies, but further validations of the test are required. The expected limits for 300 fb$^{-1}$ are $1.19\\times\\Gamma_{H\\,SM}$ for hypothesis A and $24\\times\\Gamma_{H\\,SM}$ for hypothesis B.
14. Baryon Masses and Hadronic Decay Widths with Explicit Pionic Contributions
International Nuclear Information System (INIS)
Schmidt, R. A.; Plessas, W.; Schweiger, W.; Canton, L.
2017-01-01
We report results from studies of baryon ground and resonant states by taking explicit mesonic degrees of freedom into account. We are following a relativistic coupled-channels approach relying on a Poincaré-invariant mass operator in matrix form. Generally, it corresponds to a bare particle that is coupled to a number of further mesonic channels. Here we present results, where the bare particle is either a bare nucleon or a bare Delta coupled to pion–nucleon and pion–Delta channels, respectively. For the pion–baryon vertices we employ coupling constants and form factors from different models in the literature. From the mass-operator eigenvalue equation we obtain the pion-dressing effects on the nucleon mass as well as the mass and pion-decay width of the Delta. The dressed masses become smaller than the bare ones, and a finite width of the Delta is naturally generated. The results are relevant for the construction of constituent-quark models for baryons, which have so far not included explicit mesonic degrees of freedom, but have rather relied on three-quark configurations only. (author)
15. Direct top-quark width measurement at CDF.
Science.gov (United States)
Aaltonen, T; Álvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bauer, G; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Bland, K R; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Brisuda, A; Bromberg, C; Brucken, E; Bucciantonio, M; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Cabrera, S; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; De Cecco, S; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, D; Errede, S; Ershaidat, N; Eusebi, R; Fang, H C; Farrington, S; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hidas, D; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Klimenko, S; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Lin, C-J; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, Q; Liu, T; Lockwitz, S; Lockyer, N S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Martínez-Ballarín, R; Mastrandrea, P; Mathis, M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Potamianos, K; Poukhov, O; Prokoshin, F; Pronko, A; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Santi, L; Sartori, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T
2010-12-03
We present a measurement of the top-quark width in the lepton+jets decay channel of tt events produced in p p collisions at Fermilab's Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3 fb(-1) of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γ(t)) and deviations from nominal jet energy scale (Δ(JES)) to perform a simultaneous fit for both parameters, where Δ(JES) is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γ(t) quark mass of 172.5 GeV/c(2), which are consistent with the standard model prediction.
16. Tooth width predictions in a sample of Black South Africans.
Science.gov (United States)
Khan, M I; Seedat, A K; Hlongwa, P
2007-07-01
Space analysis during the mixed dentition requires prediction of the mesiodistal widths of the unerupted permanent canines and premolars and prediction tables and equations may be used for this purpose. The Tanaka and Johnston prediction equations, which were derived from a North American White sample, is one example which is widely used. This prediction equation may be inapplicable to other race groups due to racial tooth size variability. Therefore the purpose of this study was to derive prediction equations that would be applicable to Black South African subjects. One hundred and ten pre-treatment study casts of Black South African subjects were analysed from the Department of Orthodontics' records at the University of Limpopo. The sample was equally divided by gender with all subjects having Class I molar relationship and relatively well aligned teeth. The mesiodistal widths of the maxillary and mandibular canines and premolars were measured with a digital vernier calliper and compared with the measurements predicted with the Tanaka and Johnston equations. The relationship between the measured and predicted values were analysed by correlation and regression analyses. The results indicated that the Tanaka and Johnston prediction equations were not fully applicable to the Black South African sample. The equations tended to underpredict the male sample, while slight overprediction was observed in the female sample. Therefore, new equations were formulated and proposed that would be accurate for Black subjects.
17. Determination of the width of the top quark
Energy Technology Data Exchange (ETDEWEB)
Abazov, Victor Mukhamedovich; /Dubna, JINR; Abbott, Braden Keim; /Oklahoma U.; Abolins, Maris A.; /Michigan State U.; Acharya, Bannanje Sripath; /Tata Inst.; Adams, Mark Raymond; /Illinois U., Chicago; Adams, Todd; /Florida State U.; Alexeev, Guennadi D.; /Dubna, JINR; Alkhazov, Georgiy D.; /St. Petersburg, INP; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls; Alverson, George O.; /Northeastern U.; Alves, Gilvan Augusto; /Rio de Janeiro, CBPF /Nijmegen U.
2010-09-01
We extract the total width of the top quark, {Lambda}{sub t}, from the partial decay width {Lambda}(t {yields} Wb) measured using the t-channel cross section for single top quark production and from the branching fraction B(t {yields} Wb) measured in t{bar t} events using up to 2.3 fb{sup -1} of integrated luminosity collected by the D0 Collaboration at the Tevatron p{bar p} Collider. The result is {Lambda}{sub t} = 1.99{sub -0.55}{sup +0.69} GeV, which translates to a top-quark lifetime of {tau}{sub t} = (3.3{sub -0.9}{sup +1.3}) x 10{sup -25} s. Assuming a high mass fourth generation b{prime} quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on |V{sub tb{prime}}| < 0.63 at 95% C.L.
18. 77 FR 53892 - Determination That ALOXI (Palonosetron Hydrochloride) Capsules, 0.5 Milligram (Base), Were Not...
Science.gov (United States)
2012-09-04
...] Determination That ALOXI (Palonosetron Hydrochloride) Capsules, 0.5 Milligram (Base), Were Not Withdrawn From...)) Capsules, 0.5 milligram (mg) (base), were not withdrawn from sale for reasons of safety or effectiveness... HCl capsules, 0.5 mg (base), if all other legal and regulatory requirements are met. FOR FURTHER...
19. Fabrication, characterization and evaluation of bacterial cellulose-based capsule shells for oral drug delivery
DEFF Research Database (Denmark)
Ullah, Hanif; Badshah, Munair; Mäkilä, Ermei
2017-01-01
Bacterial cellulose (BC) was investigated for the first time for the preparation of capsule shells for immediate and sustained release of drugs. The prepared capsule shells were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The BC...... to gelatin capsules with both immediate and sustained drug release properties depending upon the compositions of the encapsulated materials....
20. Adhesive Capsulitis in Eight Dogs: Diagnosis and Management.
Science.gov (United States)
Carr, Brittany J; Canapp, Sherman O; Canapp, Debra A; Gamble, Lauri-Jo; Dycus, David L
2016-01-01
To describe clinical and diagnostic findings as well as management of adhesive capsulitis in dogs. Adhesive capsulitis, also known as frozen shoulder, is a syndrome defined by loss of range of motion of the shoulder and may be the end-stage manifestation of several primary conditions. This is a case series report of eight dogs with chronic forelimb lameness diagnosed with adhesive capsulitis. Medical records (June 1, 2010-September 1, 2015) including, physical examination findings, radiographic findings, magnetic resonance imaging (MRI) findings, arthroscopy findings, and treatment plans were reviewed. All dogs presented with a chronic, grade III-VI/VI forelimb lameness. On orthopedic examination, all dogs had moderate to significant discomfort on shoulder extension and flexion and severe restriction of range of motion. Six of the eight dogs had evidence of bone remodeling and sclerosis in the affected shoulder on radiographs. Six of the dogs had an initial diagnostic ultrasound performed, which revealed evidence of fibrous scar tissue. Five dogs had MRI performed that revealed moderate shoulder effusion and enhancement of the synovial lining of the shoulder. Arthroscopy was performed in five of the eight patients. Three were noted to have significant contracture, adhesions, and fibrous scar tissue of the joint capsule. Severe inflammation was noted throughout the synovium of two patients. All eight patients tried conservative management consisting of oral medications and rehabilitation therapy. Five of the eight patients received extracorporeal shockwave therapy. Three patients received regenerative medicine treatment in the affected supraspinatus and shoulder. Regardless of the treatment elected, none of the dogs were reported to have significant improvement. Adhesive capsulitis is an uncommon cause of chronic forelimb lameness. Further investigation is needed to describe the etiology and pathogenesis of adhesive capsulitis in dogs to evaluate the effectiveness
1. Adhesive Capsulitis in 8 Dogs: Diagnosis and Management
Directory of Open Access Journals (Sweden)
Brittany Jean Carr
2016-07-01
Full Text Available ABSTRACT:Objective: To describe clinical and diagnostic findings as well as management of adhesive capsulitis in dogs.Background: Adhesive capsulitis, also known as frozen shoulder, is a syndrome defined by loss of range of motion of the shoulder and may be the end-stage manifestation of several primary conditions.Evidentiary Value: This is a case report series of eight dogs with chronic forelimb lameness diagnosed with adhesive capsulitis.Methods: Medical records (June 1, 2010 to September 1, 2015 including, physical examination findings, radiographic findings, magnetic resonance imaging findings, arthroscopy findings, and treatment plans were reviewed. Results: All dogs presented with a chronic, grade III-VI/VI forelimb lameness. On orthopedic examination all dogs had moderate to significant discomfort on shoulder extension and flexion and severe restriction of range of motion. Six of the eight dogs had evidence of bone remodeling and sclerosis in the affected shoulder on radiographs. Six of had an initial diagnostic ultrasound performed, which revealed evidence of fibrous scar tissue. Five dogs had magnetic resonance imaging performed that revealed moderate shoulder effusion and enhancement of the synovial lining of the shoulder. Arthroscopy was performed in five of the eight patients. Three were noted to have significant contracture, adhesions and fibrous scar tissue of the joint capsule. Severe inflammation was noted throughout the synovium of two patients. All eight patients tried conservative management consisting of oral medications and rehabilitation therapy. Five of the eight patients received extracorporeal shockwave therapy. Three patients received regenerative medicine treatment in the affected supraspinatus and shoulder. Regardless of the treatment elected, none of the dogs were reported to have significant improvement. Conclusion: Adhesive capsulitis is an uncommon cause of chronic forelimb lameness. Further investigation is
2. Noncontact optical measurement of lens capsule thickness ex vivo
Science.gov (United States)
Ziebarth, Noel M.; Manns, Fabrice; Uhlhorn, Stephen; Parel, Jean-Marie
2004-07-01
Purpose: To design a non-contact optical system to measure lens capsule thickness in cadaver eyes. Methods: The optical system uses a 670nm laser beam delivered to a single-mode fiber coupler. The output of the fiber coupler is focused onto the tissue using an aspheric lens (NA=0.68) mounted on a motorized translation stage. Light reflected from the sample is collected by the fiber coupler and sent to a silicon photodiode connected to a power meter. Peaks in the power signal are detected when the focal point of the aspheric lens coincides with the capsule boundaries. The capsule thickness is proportional to the distance between successive peaks. Anterior and posterior lens capsule thickness measurements were performed on 13 human, 10 monkey, and 34 New Zealand white rabbit lenses. The cadaver eyes were prepared for optical measurements by bonding a PMMA ring on the sclera. The posterior pole was sectioned, excess vitreous was removed, and the eye was placed on a Teflon slide. The cornea and iris were then sectioned. After the experiments, the lenses were excised, placed in 10% buffered formalin, and prepared for histology. Results: Central anterior lens capsule thickness was 9.4+/-2.9μm (human), 11.2+/-6.6μm (monkey), and 10.3+/-3.6μm (rabbit) optically and 14.9+/-1.6μm (human), 17.7+/-4.9μm (monkey), and 12.6+/-2.3μm (rabbit) histologically. The values for the central posterior capsule were 9.4+/-2.9μm (human), 6.6+/-2.5μm (monkey), and 7.9+/-2.3μm (rabbit) optically and 4.6+/-1.4μm (human), 4.5+/-1.2μm (monkey), and 5.7+/-1.7μm (rabbit) histologically. Conclusions: This study demonstrates that a non-contact optical system can successfully measure lens capsule thickness in cadaver eyes.
3. Requirements to gap widths and clamping for CO2 laser butt welding
DEFF Research Database (Denmark)
Gong, Hui; Juhl, Thomas Winther
1999-01-01
In the experimental study of fixturing and gap width requirements a clamping device for laser butt welding of steel sheets has been developed and tested. It has fulfilled the work and made the gap width experiments possible.It has shown that the maximum allowable gap width to some extent is inver......In the experimental study of fixturing and gap width requirements a clamping device for laser butt welding of steel sheets has been developed and tested. It has fulfilled the work and made the gap width experiments possible.It has shown that the maximum allowable gap width to some extent...
4. Capsule Development and Utilization for Material Irradiation Tests
Energy Technology Data Exchange (ETDEWEB)
Kim, Bong Goo; Kang, Y. H.; Cho, M. S. (and others)
2007-06-15
The essential technology for an irradiation test of materials and nuclear fuel has been successively developed and utilized to meet the user's requirements in Phase I(July 21, 1997 to March 31, 2000). It enables irradiation tests to be performed for a non-fissile material under a temperature control(300{+-}10 .deg. C) in a He gas environment, and most of the irradiation tests for the internal and external users are able to be conducted effectively. The basic technology was established to irradiate a nuclear fuel, and a creep capsule was also developed to measure the creep property of a material during an irradiation test in HANARO in Phase II(April 1, 2000 to March 31, 2003). The development of a specific purpose capsule, essential technology for a re-irradiation of a nuclear fuel, advanced technology for an irradiation of materials and a nuclear fuel were performed in Phase III(April 1, 2003 to February 28, 2007). Therefore, the technology for an irradiation test was established to support the irradiation of materials and a nuclear fuel which is required for the National Nuclear R and D Programs. In addition, an improvement of the existing capsule design and fabrication technology, and the development of an instrumented capsule for a nuclear fuel and a specific purpose will be able to satisfy the user's requirements. In order to support the irradiation test of materials and a nuclear fuel for developing the next generation nuclear system, it is also necessary to continuously improve the design and fabrication technology of the existing capsule and the irradiation technology.
5. Effect of Morinda officinalis capsule on osteoporosis in ovariectomized rats.
Science.gov (United States)
Li, Ye; Lü, Shan-Shan; Tang, Gui-Ying; Hou, Min; Tang, Qing; Zhang, Xiao-Na; Chen, Wei-Hai; Chen, Gang; Xue, Qiang; Zhang, Cong-Cong; Zhang, Ji-Fen; Chen, Yi; Xu, Xiao-Yu
2014-03-01
To explore the therapeutic effects of Morinda officinalis capsules (MOP) on osteoporosis in ovariectomized rats. Six-month-old female Sprague-Dawley rats were induced for postmenopausal osteoporosis (PMOP) by bilateral ovariectomy and divided into seven groups as follows: sham-operated group, ovariectomized (OVX) control group, OVX treated with xianlinggubao (XLGB) (270 mg·kg⁻¹·d⁻¹), OVX treated with alendronate sodium (ALN) (3 mg·kg⁻¹·d⁻¹), and OVX treated with Morinda officinalis capsule (MOP) of graded doses (90, 270 and 810 mg·kg⁻¹·d⁻¹) groups. Oral treatments were administered daily on the 4(th) week after ovariectomy and lasted for 12 weeks. The bone mineral density was evaluated by dual-energy X-ray absorptiometry. The tartrate-resistant acid phosphatase (TRAP), alkaline phosphatase (AKP), and osteocalcin (OC) levels in the serum and plasma were determined by standard colorimetric and enzyme immunoassays methods. Bone biomechanical properties and morphological parameters were analyzed by three-point bending test and histomorphometry respectively. Morinda officinalis capsules at all doses were able to significantly prevent the OVX-induced loss of bone mass due to diminishing serum AKP and TRAP levels while elevating OC level in the plasma. Morinda officinalis capsules also enhanced the bone strength and prevented the deterioration of trabecular microarchitecture. Morinda officinalis capsules possess potent anti-osteoporotic activity in OVX rats which could be an effective treatment for postmenopausal osteoporosis. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.
6. [Systematic review on safety of Xianling Gubao capsule].
Science.gov (United States)
Zhang, Yi-Li; Liao, Xing; Liu, Fu-Mei; Wang, Gui-Qian; Xie, Yan-Ming
2017-08-01
To systemically evaluate the safety of Xianling Gubao capsule after launching. Computer retrieval of Medline, EMbase, the Web of Science, Clinical Trials. gov, the Cochrane Library, CNKI, VIP, WanFang Data and CBM was conducted to collect information on all the research types of Xianling Gubao capsule. The literature was screened according to inclusion and exclusion criteria, and the quality of the studies was assessed according to the internationally accepted quality evaluation standards for data extraction and analysis. A total of 156 papers were included in this study, including 117 randomized control trials, 11 quasi-randomized control trials, 10 non-randomized control trials, 11 case report series, and 7 individual case reports; a total of 167 studies were analyzed. Xianling Gubao capsules were used in 7 496 patients, with an accumulative 377 cases of adverse reactions (ADR) and 4 cases of severe adverse reactions, including 1 death, 1 cerebrovascular accident, 1 case of skin allergy reaction, and 1 case of gastrointestinal discomfort; gastrointestinal system damage was most common in mild ADRs. In this study, we found that the overall safety of Xianling Gubao capsule was acceptable, but it lacked the mechanism study on the safety of the drug after marketing or the prospective long-term clinical observation study, so the further studies on the safety of drug use should be conducted. Meanwhile, the application scope of Xianling Gubao capsules was beyond the manual, in urgent needs of the relevant departments to formulate norms and provide better guidance for clinical medication. Copyright© by the Chinese Pharmaceutical Association.
7. An ultra-low-power image compressor for capsule endoscope
Directory of Open Access Journals (Sweden)
Weng Ping-Kuo
2006-02-01
Full Text Available Abstract Background Gastrointestinal (GI endoscopy has been popularly applied for the diagnosis of diseases of the alimentary canal including Crohn's Disease, Celiac disease and other malabsorption disorders, benign and malignant tumors of the small intestine, vascular disorders and medication related small bowel injury. The wireless capsule endoscope has been successfully utilized to diagnose diseases of the small intestine and alleviate the discomfort and pain of patients. However, the resolution of demosaicked image is still low, and some interesting spots may be unintentionally omitted. Especially, the images will be severely distorted when physicians zoom images in for detailed diagnosis. Increasing resolution may cause significant power consumption in RF transmitter; hence, image compression is necessary for saving the power dissipation of RF transmitter. To overcome this drawback, we have been developing a new capsule endoscope, called GICam. Methods We developed an ultra-low-power image compression processor for capsule endoscope or swallowable imaging capsules. In applications of capsule endoscopy, it is imperative to consider battery life/performance trade-offs. Applying state-of-the-art video compression techniques may significantly reduce the image bit rate by their high compression ratio, but they all require intensive computation and consume much battery power. There are many fast compression algorithms for reducing computation load; however, they may result in distortion of the original image, which is not good for use in the medical care. Thus, this paper will first simplify traditional video compression algorithms and propose a scalable compression architecture. Conclusion As the result, the developed video compressor only costs 31 K gates at 2 frames per second, consumes 14.92 mW, and reduces the video size by 75% at least.
8. An ultra-low-power image compressor for capsule endoscope.
Science.gov (United States)
Lin, Meng-Chun; Dung, Lan-Rong; Weng, Ping-Kuo
2006-02-25
Gastrointestinal (GI) endoscopy has been popularly applied for the diagnosis of diseases of the alimentary canal including Crohn's Disease, Celiac disease and other malabsorption disorders, benign and malignant tumors of the small intestine, vascular disorders and medication related small bowel injury. The wireless capsule endoscope has been successfully utilized to diagnose diseases of the small intestine and alleviate the discomfort and pain of patients. However, the resolution of demosaicked image is still low, and some interesting spots may be unintentionally omitted. Especially, the images will be severely distorted when physicians zoom images in for detailed diagnosis. Increasing resolution may cause significant power consumption in RF transmitter; hence, image compression is necessary for saving the power dissipation of RF transmitter. To overcome this drawback, we have been developing a new capsule endoscope, called GICam. We developed an ultra-low-power image compression processor for capsule endoscope or swallowable imaging capsules. In applications of capsule endoscopy, it is imperative to consider battery life/performance trade-offs. Applying state-of-the-art video compression techniques may significantly reduce the image bit rate by their high compression ratio, but they all require intensive computation and consume much battery power. There are many fast compression algorithms for reducing computation load; however, they may result in distortion of the original image, which is not good for use in the medical care. Thus, this paper will first simplify traditional video compression algorithms and propose a scalable compression architecture. As the result, the developed video compressor only costs 31 K gates at 2 frames per second, consumes 14.92 mW, and reduces the video size by 75% at least.
9. Polarization at the SLC
Energy Technology Data Exchange (ETDEWEB)
Moffeit, K.C.
1988-10-01
The Stanford Linear collider was designed to accommodate polarized electron beams. Longitudinally polarized electrons colliding with unpolarized positrons at a center of mass energy near the Z/sup 0/ mass can be used as novel and sensitive probes of the electroweak process. A gallium arsenide based photon emission source will provide a beam of longitudinally polarized electrons of about 45 percent polarization. A system of bend magnets and a superconducting solenoid will be used to rotate the spins so that the polarization is preserved while the 1.21 GeV electrons are stored in the damping ring. Another set of bend magnets and two superconducting solenoids orient the spin vectors so that longitudinal polarization of the electrons is achieved at the collision point with the unpolarized positrons. A system to monitor the polarization based on Moller and Compton scattering will be used. Nearly all major components have been fabricated and tested. Subsystems of the source and polarimeters have been installed, and studies are in progress. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. 8 refs., 16 figs., 1 tab.
10. Polarization-Directed Surface Plasmon Polariton Launching
Energy Technology Data Exchange (ETDEWEB)
Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.
2017-01-05
The relative intensities of propagating surface plasmons (PSPs) simultaneously launched from opposing edges of a symmetric trench structure etched into a silver thin film may be controllably varied by tuning the linear polarization of the driving field. This is demonstrated through transient multiphoton photoemission electron microscopy measurements performed using a pair of spatially separated phase-locked femtosecond pulses. Our measurements are rationalized using finite-difference time domain simulations, which reveal that the coupling efficiency into the PSP modes is inversely proportional to the magnitude of the localized surface plasmon fields excited at the trench edges. Additional experiments on single step edges also show asymmetric PSP launching with respect to polarization, analogous to the trench results. Our combined experimental and computational results allude to the interplay between localized and propagating surface plasmon modes in the trench; strong coupling to the localized modes at the edges correlates to weak coupling to the PSP modes. Simultaneous excitation of the electric fields localized at both edges of the trench results in complex interactions between the right- and left-side PSP modes with Fabry-Perot and cylindrical modes. This results in a trench width-dependent PSP intensity ratio using otherwise identical driving fields. A systematic exploration of polarization directed PSP launching from a series of trench structures reveals an optimal PSP contrast ratio of 4.2 using a 500 nm-wide trench.
11. Polarized atomic beams for targets
International Nuclear Information System (INIS)
Grueebler, W.
1984-01-01
The basic principle of the production of polarized atomic hydrogen and deuterium beams are reviewed. The status of the present available polarization, density and intensity are presented. The improvement of atomic beam density by cooling the hydrogen atoms to low velocity is discussed. The possible use of polarized atomic beams as targets in storage rings is shown. It is proposed that polarized atomic beams can be used to produce polarized gas targets with high polarization and greatly improved density
12. Polarized scintillator targets
Science.gov (United States)
van den Brandt, B.; Bunyatova, E. I.; Hautle, P.; Konter, J. A.; Mango, S.
2000-05-01
The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as "live" polarized targets in nuclear physics experiments.
13. Polarized scintillator targets
Energy Technology Data Exchange (ETDEWEB)
Brandt, B. van den E-mail: vandenbrandt@psi.ch; Bunyatova, E.I.; Hautle, P.; Konter, J.A.; Mango, S
2000-05-21
The hydrogen nuclei in an organic scintillator have been polarized to more than 80% and the deuterons in its fully deuterated version to 24%. The scintillator, doped with TEMPO, has been polarized dynamically in a field of 2.5 T in a vertical dilution refrigerator in which a plastic lightguide transports the scintillation light from the sample in the mixing chamber to a photomultiplier outside the cryostat. Sizeable solid samples with acceptable optical properties and light output have been prepared and successfully operated as 'live' polarized targets in nuclear physics experiments.
14. Heidelberg polarized alkali source
International Nuclear Information System (INIS)
Kraemer, D.; Steffens, E.; Jaensch, H.; Philipps Universitaet, Marburg, Germany)
1984-01-01
A new atomic beam type polarized alkali ion source has been installed at Heidelberg. In order to improve the beam polarization considerably optical pumping is applied in combination with an adiabatic medium field transition which results in beams in single hyperfine sublevels. The m state population is determined by laser-induced fluorescence spectroscopy. Highly polarized beams (P/sub s/ > 0.9, s = z, zz) with intensities of 30 to 130 μA can be extracted for Li + and Na + , respectively
15. Polarization measurement in the COMPASS polarized target
CERN Document Server
Kondo, K; Baum, G; Berglund, P; Doshita, N; Gautheron, F; Görtz, S; Hasegawa, T; Horikawa, N; Ishimoto, S; Iwata, T; Kisselev, Yu V; Koivuniemi, J H; Le Goff, J M; Magnon, A; Meyer, W; Reicherz, G; Matsuda, T
2004-01-01
Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and -53% as the average in the target cells.
16. Residual mercury content and leaching of mercury and silver from used amalgam capsules.
Science.gov (United States)
Stone, M E; Pederson, E D; Cohen, M E; Ragain, J C; Karaway, R S; Auxer, R A; Saluta, A R
2002-06-01
The objective of this investigation was to carry out residual mercury (Hg) determinations and toxicity characteristic leaching procedure (TCLP) analysis of used amalgam capsules. For residual Hg analysis, 25 capsules (20 capsules for one brand) from each of 10 different brands of amalgam were analyzed. Total residual Hg levels per capsule were determined using United States Environmental Protection Agency (USEPA) Method 7471. For TCLP analysis, 25 amalgam capsules for each of 10 brands were extracted using a modification of USEPA Method 1311. Hg analysis of the TCLP extracts was done with USEPA Method 7470A. Analysis of silver (Ag) concentrations in the TCLP extract was done with USEPA Method 6010B. Analysis of the residual Hg data resulted in the segregation of brands into three groups: Dispersalloy capsules, Group A, retained the most Hg (1.225 mg/capsule). These capsules were the only ones to include a pestle. Group B capsules, Valliant PhD, Optaloy II, Megalloy and Valliant Snap Set, retained the next highest amount of Hg (0.534-0.770 mg/capsule), and were characterized by a groove in the inside of the capsule. Group C, Tytin regular set double-spill, Tytin FC, Contour, Sybraloy regular set, and Tytin regular set single-spill retained the least amount of Hg (0.125-0.266 mg/capsule). TCLP analysis of the triturated capsules showed Sybraloy and Contour leached Hg at greater than the 0.2 mg/l Resource Conservation and Recovery Act (RCRA) limit. This study demonstrated that residual mercury may be related to capsule design features and that TCLP extracts from these capsules could, in some brands, exceed RCRA Hg limits, making their disposal problematic. At current RCRA limits, the leaching of Ag is not a problem.
17. Training the New Generation of Polar Researchers
Science.gov (United States)
Drobot, S.; Weiler, C. S.
2008-12-01
The polar regions are changing rapidly, and many of the pressing problems faced in the future will require a new generation of polar researchers to be disciplinary experts and work across traditional disciplinary boundaries to conduct socially relevant, transformative research, and translate it to more effective action. To learn about the past and better address these new challenges, a select international group of 35 students and early career researchers who are conducting research during the 2007-2009 International Polar Year were brought together May 4-11, 2008, at the La Foret Conference Center for the New Generation Polar Research (NGPR) Symposium. The participants were drawn from professional backgrounds spanning the spectrum of social, natural, and physical sciences and represented the research programs of 7 countries. In addition to the participants, 12 mentors, some of whom participated in the IGY, shared insights, stories, and expertise. This diverse and ambitious group spent an intensive week learning about many important aspects of IPY history and research, along with communication, outreach, interdisciplinary research and career development. Each of the participants presented a 7-minute overview of his or her IPY research and provided details and discussion in evening poster sessions. Polar history provided an informative and unifying context for discussions of the past, present, and future that lasted throughout the week. Mentors and guest speakers shared insights and advice on media interactions, and many participants were subsequently interviewed for an upcoming radio story to be aired on National Public Radio. Several presentations on outreach were followed by a hands-on session for a group 1st grade students who were visiting the La Foret Conference Center. The Symposium also featured several break-out sessions, where small groups of participants and mentors discussed challenges related to interdisciplinary research, science advocacy, and
18. Crosslinking studies in gelatin capsules treated with formaldehyde and in capsules exposed to elevated temperature and humidity.
Science.gov (United States)
Ofner, C M; Zhang, Y E; Jobeck, V C; Bowman, B J
2001-01-01
Incomplete in vitro capsule shell dissolution and subsequent drug release problems have recently received attention. A modified USP dissolution method was used to follow capsule shell dissolution, and a 2,4,6-trinitrobenzenesulfonic acid (TNBS) assay was used to follow loss of epsilon-amino groups to study this shell dissolution problem postulated to be due to gelatin crosslinking. The dissolution problems were simulated using hard gelatin capsule (HGC) shells previously treated with formaldehyde to crosslink the gelatin. These methods were also used to study the effect of uncrosslinked HGC stored under stressed conditions (37 degrees C and 81% RH) with or without the presence of soft gelatin capsule shells (SGC). A 120 ppm formaldehyde treatment reduced gelatin shell dissolution to 8% within 45 min in water at 37 degrees C. A 200 ppm treatment reduced gelatin epsilon-amino groups to 83% of the original uncrosslinked value. The results also support earlier reports of non-amino group crosslinking by formaldehyde in gelatin. Under stressed conditions, HGC stored alone showed little change over 21 weeks. However, by 12 to 14 weeks, the HGC exposed to SGC showed a 23% decrease in shell dissolution and an 8% decrease in the number of epsilon-amino groups. These effects on the stressed HGC are ascribed to a volatile agent from SGC shells, most likely formaldehyde, that crosslinked nearby HGC shells. This report also includes a summary of the literature on agents that reduce gelatin and capsule shell dissolution and the possible mechanisms of this not-so-simple problem. Copyright 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90: 79-88, 2001
19. Cellulose nanofiber/nanocrystal reinforced capsules: a fast and facile approach toward assembly of liquid-core capsules with high mechanical stability.
Science.gov (United States)
Svagan, Anna J; Musyanovych, Anna; Kappl, Michael; Bernhardt, Max; Glasser, Gunnar; Wohnhaas, Christian; Berglund, Lars A; Risbo, Jens; Landfester, Katharina
2014-05-12
Liquid-core capsules of high mechanical stability open up for many solid state-like applications where functionality depending on liquid mobility is vital. Herein, a novel concept for fast and facile improvement of the mechanical properties of walls of liquid-core capsules is reported. By imitating nature's own way of enhancing the mechanical properties in liquid-core capsules, the parenchyma plant cells found in fruits and vegetables, a blend of short cellulose nanofibers (wood pulp hydrolysis. The capsule shell consisted of a covalently (by aromatic diisocyanate) cross-linked NFC/CNC structure at the outer capsule wall and an inner layer dominated by aromatic polyurea. The mechanical properties revealed an effective capsule elastic modulus of 4.8 GPa at 17 wt % NFC/CNC loading, about six times higher compared to a neat aromatic polyurea capsule (0.79 GPa) and 3 orders of magnitude higher than previously reported capsules from regenerated cellulose (0.0074 GPa). The outstanding mechanical properties are ascribed to the dense nanofiber structure, present in the outer part of the capsule wall, that is formed by oriented NFC/CNC of high average aspect ratio (L/d ∼ 70) and held together by both covalent (urethane bonds) and physical bonds (hydrogen bonds).
20. Energy and energy width measurement in the FNAL antiproton accumulator
International Nuclear Information System (INIS)
Church, M.; Hsueh, S.; Rapidis, P.; Werkema, S.
1991-10-01
The Fermilab Antiproton Accumulator has recently been used to produce Charmonium resonances (charm quark, anti-charm quark bound states) in proton-antiproton annihilations using an internal H 2 gas jet target. A measurement of the resonance mass and width may be obtained from a precise knowledge of the antiproton beam energy and energy spread. The beam energy is measured to an accuracy of 1 part in 10 4 in the range 6.3 Gev to 4.1 Gev by measuring the orbit length and revolution frequency of the beam. The beam momentum spread is measured to an accuracy of 10% by measuring the beam frequency spread and the parameter η = (P beam /F rev )·(dF rev /dP beam ). These two measurement techniques are described in this report
1. Energy and energy width measurement in the FNAL antiproton accumulator
Energy Technology Data Exchange (ETDEWEB)
Church, M.; Hsueh, S.; Rapidis, P.; Werkema, S.
1991-10-01
The Fermilab Antiproton Accumulator has recently been used to produce Charmonium resonances (charm quark, anti-charm quark bound states) in proton-antiproton annihilations using an internal H{sub 2} gas jet target. A measurement of the resonance mass and width may be obtained from a precise knowledge of the antiproton beam energy and energy spread. The beam energy is measured to an accuracy of 1 part in 10{sup 4} in the range 6.3 Gev to 4.1 Gev by measuring the orbit length and revolution frequency of the beam. The beam momentum spread is measured to an accuracy of 10% by measuring the beam frequency spread and the parameter {eta} = (P{sub beam}/F{sub rev}){center_dot}(dF{sub rev}/dP{sub beam}). These two measurement techniques are described in this report.
2. Free-edge delamination - Laminate width and loading conditions effects
Science.gov (United States)
Murthy, Pappu L. N.; Chamis, Christos C.
1989-01-01
The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progressive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.
3. Dynamic nuclear spin polarization
Energy Technology Data Exchange (ETDEWEB)
Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)
1996-11-01
Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.
4. Time Domain Induced Polarization
DEFF Research Database (Denmark)
Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest
2012-01-01
Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use...... of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function......%. Furthermore, the presence of low-pass filters in time-domain-induced polarization instruments affects the early times of the acquired decays (typically up to 100 ms) and has to be modeled in the forward response to avoid significant loss of resolution. The developed forward code has been implemented in a 1D...
5. Polarized proton colliders
International Nuclear Information System (INIS)
Roser, T.
1995-01-01
High energy polarized beam collisions will open up the unique physics opportunities of studying spin effects in hard processes. This will allow the study of the spin structure of the proton and also the verification of the many well documented expectations of spin effects in perturbative QCD and parity violation in W and Z production. Proposals for polarized proton acceleration for several high energy colliders have been developed. A partial Siberian Snake in the AGS has recently been successfully tested and full Siberian Snakes, spin rotators, and polarimeters for RHIC are being developed to make the acceleration of polarized beams to 250 GeV possible. This allows for the unique possibility of colliding two 250 GeV polarized proton beams at luminosities of up to 2 x 10 32 cm -2 s -1
6. Measurement of inner wall limiter SOL widths in KSTAR tokamak
Directory of Open Access Journals (Sweden)
J.G. Bak
2017-08-01
Full Text Available Scrape-off layer (SOL widths λq are presented from the KSTAR tokamak using fast reciprocating Langmuir probe assembly (FRLPA measurements at the outboard mid-plane (OMP and the infra-Red (IR thermography at inboard limiter tiles in moderately elongated (κ = 1.45 – 1.55 L-mode inner wall-limited (IWL plasmas under experimental conditions such as BT = 2.0 T, PNBI = 1.4 – 1.5 MW, line averaged densities 2.5 – 5.1 × 1019 m−3 and plasma current Ip = 0.4 − 0.7 MA. There is clear evidence for a double exponential structure in q||(r from the FRLPA such that, for example at Ip = 0.6 MA, a narrow feature, λq,near (=3.5 mm is found close to the LFCS, followed by a broader width, λq,main (=57.0 mm. Double exponential profiles (λq,near = 1.5 – 2.8 mm, λq,main = 17.0 – 35.0 mm can be also observed in the IR heat flux mapped to the OMP throughout the range of Ip investigated. In addition, analysis of SOL turbulence statistics obtained with the FRLPA shows high relative fluctuation levels and positively skewed distributions in electron temperature and ion particle flux across the SOL, with both properties increasing for longer distance from the LCFS, as often previously observed in the tokamaks. Interestingly, the fluctuation character expressed in terms of spectral distributions remains unchanged in passing from the narrow to the broad SOL heat flux channel.
7. Variable Width Riparian Model Enhances Landscape and Watershed Condition
Science.gov (United States)
Abood, S. A.; Spencer, L.
2017-12-01
Riparian areas are ecotones that represent about 1% of USFS administered landscape and contribute to numerous valuable ecosystem functions such as wildlife habitat, stream water quality and flows, bank stability and protection against erosion, and values related to diversity, aesthetics and recreation. Riparian zones capture the transitional area between terrestrial and aquatic ecosystems with specific vegetation and soil characteristics which provide critical values/functions and are very responsive to changes in land management activities and uses. Two staff areas at the US Forest Service have coordinated on a two phase project to support the National Forests in their planning revision efforts and to address rangeland riparian business needs at the Forest Plan and Allotment Management Plan levels. The first part of the project will include a national fine scale (USGS HUC-12 digits watersheds) inventory of riparian areas on National Forest Service lands in western United States with riparian land cover, utilizing GIS capabilities and open source geospatial data. The second part of the project will include the application of riparian land cover change and assessment based on selected indicators to assess and monitor riparian areas on annual/5-year cycle basis.This approach recognizes the dynamic and transitional nature of riparian areas by accounting for hydrologic, geomorphic and vegetation data as inputs into the delineation process. The results suggest that incorporating functional variable width riparian mapping within watershed management planning can improve riparian protection and restoration. The application of Riparian Buffer Delineation Model (RBDM) approach can provide the agency Watershed Condition Framework (WCF) with observed riparian area condition on an annual basis and on multiple scales. The use of this model to map moderate to low gradient systems of sufficient width in conjunction with an understanding of the influence of distinctive landscape
8. Plasma polarization spectroscopy
International Nuclear Information System (INIS)
Iwamae, Atsushi; Horimoto, Yasuhiro; Fujimoto, Takashi; Hasegawa, Noboru; Sukegawa, Kouta; Kawachi, Tetsuya
2005-01-01
The electron velocity distribution function (EVDF) in plasma can be anisotropic in laser-produced plasmas. We have developed a new technique to evaluate the polarization degree of the emission lines in the extreme vacuum ultra violet wavelength region. The polarization of the emission lines and the continuums from the lithium-like nitrogen and from helium- and hydrogen-like carbon in recombining plasma is evaluated. Particle simulation in the velocity space gives the time scale for relaxation of anisotropic EVDFs. (author)
9. Ultracold Polar Molecules
Science.gov (United States)
2016-04-01
AFRL-AFOSR-UK-TR-2016-0005 Ultracold Polar Molecules Jeremy Hutson UNIVERSITY OF DURHAM Final Report 04/01/2016 DISTRIBUTION A: Distribution approved...DATES COVERED (From - To) 15-Jan-2010 to 14-Jul-2015 4. TITLE AND SUBTITLE Final Report on Grant FA8655-10-1-3033 on Ultracold Polar Molecules 5a...formation of ultracold 87RbCs molecules in their rovibrational ground state by magnetoassociation followed by STIRAP, resulting in 14 papers acknowledging
10. Buckling and its effect on the confined flow of a model capsule suspension
Science.gov (United States)
Bryngelson, Spencer; Freund, Jonathan
2015-11-01
The rheology of confined flowing suspensions, such as blood, depend upon the dynamics of the components, which can be particularly rich when they are elastic capsules. Using boundary integral methods, we simulate a two-dimensional model channel through which flows a dense suspension of fluid-filled capsules. A parameter of principal interest is the equilibrium membrane perimeter, which ranges from round capsules to capsules with an elongated dog-bone-like equilibrium shape. It is shown that the minimum effective viscosity occurs for capsules with a biconcave equilibrium shape, similar to that of a red blood cell. The rheological behavior changes significantly over this range; transitions are linked to specific changes in the capsule dynamics. Most noteworthy is an abrupt change in behavior when capsules transition to a dog-bone-like equilibrium shape, which correlates with the onset of capsule buckling. The buckled capsules have a more varied orientation and make significant rotational (rotlet) contributions to the capsule-capsule interactions. Supported under NSF Grant No. CBET 13-36972.
11. Comparative assessment of hepatic Glisson's capsule and bovine pericardium in heart valve bioprostheses.
Science.gov (United States)
Kagramanov, I I; Kokshenev, I V; Dobrova, N B; Kastava, V T; Serov, R A; Zaets, S B
1998-05-01
The optimal material for heart valve bioprostheses remains disputable. This investigation was initiated to compare the properties of hepatic Glisson's capsule, clinical experience of which in cardiovascular surgery is minimal, with those of bovine pericardium. Hepatic Glisson's capsule was harvested from bull calves and used to create composite pulmonary arterial monocusp grafts and bioprostheses. Comparison of the strength and elastic properties of Glisson's capsule and bovine pericardium, as well as the hydrodynamic characteristics of valves made from these materials, was performed. Late results of operations using these materials were estimated echocardiographically. Although Glisson's capsule tissue is thinner than the bovine pericardium, its elasticity modulus is greater. However, the hydrodynamic characteristics of heart valves made from either tissue are similar. Moreover, valves made from Glisson's capsule have a lower systolic pressure gradient on the prosthesis and a higher effective orifice area. Composite pulmonary arterial xenopericardial grafts with a monocusp of Glisson's capsule were used in 30 patients during tetralogy of Fallot repair. Glisson's capsule was also used for tricuspid valve reconstruction and as a bioprosthesis in six patients with Ebstein's anomaly. At 1-2 years after surgery, the Glisson's capsule tissue remained thin and flexible, with no calcification. Although the hydrodynamic properties of hepatic Glisson's capsule and the bovine pericardium are similar, the capsule tissue is thinner and has a greater elasticity modulos. Thus, Glisson's capsule may be used for bioprosthesis construction both independently and in combination with bovine pericardium.
12. Hsp Polarization Verification
Science.gov (United States)
Bless, Robert
1991-07-01
This proposal defines the procedure for determining the instrumental polarization of the polarimetric IDT (IDT#1, POL) on the HSP. 1 of 2 unpolarized standard stars wil be observed using various filter-polarizer combinations. These observations will permit the instrumental polarization to be calibrated. The instrumental polarization must be determined to a high precision in order to vectoriallly remove it from HSP polarization observations to determine the actual astronomical polarization. Final run of proposal will look at one of 2 possible stars previously observed to get another look at the throughput. Revision History: Mark H. Slovak 8/30/88 Translated to V2 proposal instructions (RPSS V6.2) S. Laurent 1/20/89 Updated: Sally Laurent 2/24/89, 3/20/89, 4/13/89, 5/12/89 Modified: P. Stanley 1/15/90 - change to use CTA selected targets only; Fixes for aberration problem - SALM 7/30/90; Based on SV/HSP 1386. New submission changed targets and revised scheduling strategy. Revised: 26 Aug 92 J. Dolan, L. Walter, P. Reppert want to re-run the proposal (3985) one last time to bring down errors.
13. Wireless capsule endoscopy of the small intestine: a review with future directions.
Science.gov (United States)
Neumann, Helmut; Fry, Lucía C; Nägel, Andreas; Neurath, Markus F
2014-09-01
Here, we review the clinical applications of small bowel capsule endoscopy. Moreover, we provide an outlook on the exceptional future developments of small bowel capsule endoscopy. We discuss clinical algorithms for diagnosis of small bowel diseases. Multiple studies have shown the potential of capsule endoscopy for identification of the bleeding source located in the small bowel and the increased diagnostic yield over radiographic studies. Capsule endoscopy could detect villous atrophy and severe complications in patients with nonresponsive celiac disease. In addition, small bowel capsule endoscopy was proven as a valid tool to diagnose polyps and tumors and Crohn's disease. Major current clinical indications of capsule endoscopy in the small bowel include evaluation of obscure gastrointestinal bleeding, diagnosis and surveillance of small bowel polyps and tumors, celiac disease and Crohn's disease. Recent developments have also passed the way for small bowel capsule endoscopy to become a therapeutic instrument.
14. Radiative polarization in high-energy storage rings
International Nuclear Information System (INIS)
Mane, S.R.
1989-01-01
Electron and positron beams circulating in high-energy storage rings become spontaneously polarized by the emission of synchrotron radiation. The asymptotic degree of polarization that can be attained is strongly affected by so-called depolarizing resonances. Detailed experimental measurements of the polarization were made SPEAR about ten years ago, but due to lack of a suitable theory only a limited theoretical fit to the data has so far been achieved. The author presents a general formalism for calculating depolarizing resonances, which has been coded into a computer program called SMILE, and use it to fit the SPEAR data. By the use of suitable approximations, the author is able to fit both higher order and nonlinear resonances, and thereby to interpret many hitherto unexplained features in the data, and to resolve a puzzle concerning the asymmetry of certain resonance widths seen in the data. 18 refs., 2 figs
15. Radiative polarization in high-energy storage rings
International Nuclear Information System (INIS)
Mane, S.R.
1989-03-01
Electron and positron beams circulating in high-energy storage rings become spontaneously polarized by the emission of synchrotron radiation. The asymptotic degree of polarization that can be attained is strongly affected by so-called depolarizing resonances. Detailed experimental measurements of the polarization were made SPEAR about ten years ago, but due to lack of a suitable theory only a limited theoretical fit to the data has so far been achieved. I present a general formalism for calculating depolarizing resonances, which as been coded into a computer program called SMILE, and use it to fit the SPEAR data. By the use of suitable approximations, I am able to fit both higher order and nonlinear resonances, and thereby to interpret many hitherto unexplained features in the data, and to resolve a puzzle concerning the asymmetry of certain resonance widths seen in the data. 18 refs., 2 figs
16. Polarized Light Microscopy
Science.gov (United States)
Frandsen, Athela F.
2016-01-01
Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often
17. Polyp Detection and Segmentation from Video Capsule Endoscopy: A Review
Directory of Open Access Journals (Sweden)
V. B. Surya Prasath
2016-12-01
Full Text Available Video capsule endoscopy (VCE is used widely nowadays for visualizing the gastrointestinal (GI tract. Capsule endoscopy exams are prescribed usually as an additional monitoring mechanism and can help in identifying polyps, bleeding, etc. To analyze the large scale video data produced by VCE exams, automatic image processing, computer vision, and learning algorithms are required. Recently, automatic polyp detection algorithms have been proposed with various degrees of success. Though polyp detection in colonoscopy and other traditional endoscopy procedure based images is becoming a mature field, due to its unique imaging characteristics, detecting polyps automatically in VCE is a hard problem. We review different polyp detection approaches for VCE imagery and provide systematic analysis with challenges faced by standard image processing and computer vision methods.
18. Flexible and capsule endoscopy for screening, diagnosis and treatment.
Science.gov (United States)
Sliker, Levin J; Ciuti, Gastone
2014-11-01
Endoscopy dates back to the 1860s, but many of the most significant advancements have been made within the past decade. With the integration of robotics, the ability to precisely steer and advance traditional flexible endoscopes has been realized, reducing patient pain and improving clinician ergonomics. Additionally, wireless capsule endoscopy, a revolutionary alternative to traditional scopes, enables inspection of the digestive system with minimal discomfort for the patient or the need for sedation, mitigating some of the risks of flexible endoscopy. This review presents a research update on robotic endoscopic systems, including both flexible scope and capsule technologies, detailing actuation methods and therapeutic capabilities. A future perspective on endoscopic potential for screening, diagnostic and therapeutic gastrointestinal procedures is also presented.
19. Compounding of slow-release niacinamide capsules: feasibility and characterization.
Science.gov (United States)
Radojkovic, Branko; Milić, Jela; Calija, Bojan
2012-01-01
The purpose of this study was to assess the feasibility of extemporaneous compounding of slow-release oral dosage form of niacinamide and to evaluate its release kinetics. The model formulation (preparation) was developed in the form of powder-filled hard gelatin capsules. Two slow-release preparations with different ratios of hypromellose have been prepared and evaluated in comparison with an immediate-release preparation. The dissolution tests were performed as per United States Pharmacopoeia requirements: Type I Apparatus, over 7 hours. Both slow-release preparations, containing 40% and 60% v/v hypromellose, respectively, have showed slow release kinetics. The dissolution profiles were significantly different, with similarity factor f2niacinamide capsules can be successfully compounded using hypromellose as a sole release rate modifier, and that the release mechanism is comparable to hydrophilic polymer matrix-based systems.
20. Capsule physics comparison of different ablators for NIF implosion designs
Science.gov (United States)
Clark, Daniel; Kritcher, Andrea; Yi, Austin; Zylstra, Alex; Haan, Steven; Ralph, Joseph; Weber, Christopher
2017-10-01
Indirect drive implosion experiments on the Naitonal Ignition Facility (NIF) have now tested three different ablator materials: glow discharge polymer (GDP) plastic, high density carbon (HDC), and beryllium. How do these different ablator choices compare in current and future implosion experiments on NIF? What are the relative advantages and disadvantages of each? This talk compares these different ablator options in capsule-only simulations of current NIF experiments and proposed future designs. The simulations compare the impact of the capsule fill tube, support tent, and interface surface roughness for each case, as well as all perturbations in combination. According to the simulations, each ablator is impacted by the various perturbation sources differently, and each material poses unique challenges in the pursuit of ignition. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
1. Wireless capsule endoscopy of the small intestine in children.
Science.gov (United States)
Zevit, Noam; Shamir, Raanan
2015-06-01
Wireless capsule endoscopy (CE) for the diagnosis of small-bowel disease has been in clinical use for more than a decade, and is no longer an emerging technology, but rather one that has reached fruition. This noninvasive technology has been readily embraced by both physicians and patients. Used in the diagnosis of inflammatory bowel disease, for locating sources of obscure gastrointestinal bleeding, and for assessing small-bowel polyp burden in polyposis syndromes as well as for less common indications, CE has transformed the diagnostic algorithms of small-bowel investigations. Although already in widespread use, the technology incorporated into the various CE platforms continues to improve and expand. Here, we briefly review the indications, limitations, and advances in video capsule technology, with an emphasis on its use in pediatrics.
2. A Prototype Design of a Wireless Capsule Endoscope
Directory of Open Access Journals (Sweden)
Y. Chan
2006-01-01
Full Text Available Diseases of the gastrointestinal tract, such as intestinal bleeding and ulceration, are very common. To determine the location of the disease, as well as to diagnose the problem, endoscopy is performed. A wireless capsule endoscope is a pill-sized device that is easily swallowed by the patient. It is equipped with a camera and a wireless transmitter so that as it travels through the patient's gastrointestinal tract, it takes pictures or video images of the tract and transmits the information out of the patient's body. This article discusses the possible solutions and challenges of a wireless capsule endoscope in terms of the choice of wireless frequency and circuit components. A prototype is built with commercially available components to demonstrate the concept of the device.
3. Capsule enteroscopy and radiology of the small intestine
International Nuclear Information System (INIS)
Fork, Frans-Thomas; Aabakken, Lars
2007-01-01
In a very few years, the video capsule for small bowel enteroscopy has gained widespread clinical acceptance. It is readily ingested, disposable, and allows for a complete, low-invasive endoscopic examination of the entire mucosa of the small bowel. It is a patient-friendly method and a first-line procedure in the difficult evaluation of obscure gastrointestinal bleeding. It has the highest proven figure of diagnostic sensitivity for detecting lesions of the mucosa, irrespective of aetiology. The limitations of capsule endoscopy include difficulty in localising mucosal lesions anatomically and its restricted use in patients with dysphagia, strictures or motor dysfunction. Strictures, transmural and extra-mural lesions in patients with small bowel Crohn's disease are evaluated by MRI- enterography and CT-enterography. (orig.)
4. A statistical comparison of SuperDARN spectral width boundaries and DMSP particle precipitation boundaries in the morning sector ionosphere
Directory of Open Access Journals (Sweden)
G. Chisham
2005-03-01
Full Text Available Determining reliable proxies for the ionospheric signature of the open-closed field line boundary (OCB is crucial for making accurate ionospheric measurements of many magnetospheric processes (e.g. magnetic reconnection. This study compares the latitudes of Spectral Width Boundaries (SWBs, identified in the morning sector ionosphere using the Super Dual Auroral Radar Network (SuperDARN, with Particle Precipitation Boundaries (PPBs determined using the low-altitude Defense Meteorological Satellite Program (DMSP spacecraft, in order to determine whether the SWB represents a good proxy for the ionospheric projection of the OCB. The latitudes of SWBs and PPBs were identified using automated algorithms applied to 5 years (1997-2001 of data measured in the 00:00-12:00 Magnetic Local Time (MLT range. A latitudinal difference was measured between each PPB and the nearest SWB within a ±10min Universal Time (UT window and within a ±1h MLT window. The results show that the SWB represents a good proxy for the OCB close to midnight (~00:00-02:00 MLT and noon (~08:00-12:00 MLT, but is located some distance (~2°-4° equatorward of the OCB across much of the morning sector ionosphere (~02:00-08:00 MLT. On the basis of this and other studies we deduce that the SWB is correlated with the poleward boundary of auroral emissions in the Lyman-Birge-Hopfield Long" (LBHL UV emission range and hence, that spectral width is inversely correlated with the energy flux of precipitating electrons. We further conclude that the combination of two factors may explain the spatial distribution of spectral width values in the polar ionospheres. The small-scale structure of the convection electric field leads to an enhancement in spectral width in regions close to the OCB, whereas increases in ionospheric conductivity (relating to the level of incident electron energy flux lead to a reduction in spectral width in regions just equatorward of the OCB.
5. The evolution of tensor polarization
International Nuclear Information System (INIS)
Huang, H.; Lee, S.Y.; Ratner, L.
1993-01-01
By using the equation of motion for the vector polarization, the spin transfer matrix for spin tensor polarization, the spin transfer matrix for spin tensor polarization is derived. The evolution equation for the tensor polarization is studied in the presence of an isolate spin resonance and in the presence of a spin rotor, or snake
6. CAPSULES AS A PREVENTION OF FIBRE CLUSTERS IN CONCRETE
OpenAIRE
JOSEF STRYK; KAREL POSPíšIL; RADEK MATULA
2012-01-01
Homogenous concrete mixture without aggregate pockets and fibre clusters is a presumption for appropriate properties of concrete element or structure. There are technological measures how to achieve homogenously looking mixture from aggregate point of view, but fibres are still predisposed for clusters forming. The paper evaluates originally designed and protected within European patent treatment of fibre, based on capsules containing individual rolled fibre which can be admixed into a concre...
7. Deep Reinforcement Learning using Capsules in Advanced Game Environments
OpenAIRE
Andersen, Per-Arne
2018-01-01
Reinforcement Learning (RL) is a research area that has blossomed tremendously in recent years and has shown remarkable potential for artificial intelligence based opponents in computer games. This success is primarily due to vast capabilities of Convolutional Neural Networks (ConvNet), enabling algorithms to extract useful information from noisy environments. Capsule Network (CapsNet) is a recent introduction to the Deep Learning algorithm group and has only barely begun to be explored. The ...
8. Arthroscopic treatment of refractory adhesive capsulitis of the shoulder
Directory of Open Access Journals (Sweden)
Marcos Rassi Fernandes
Full Text Available OBJECTIVE: to evaluate the results of arthroscopic treatment of refractory adhesive capsulitis of the shoulder associated as for improved range of motion after a minimum follow up of six years. METHODS: from August 2002 to December 2004, ten patients with adhesive capsulitis of the shoulder resistant to conservative treatment underwent arthroscopic surgery. One interscalene catheter was placed for postoperative analgesia before the procedure. All were in Phase II, with a minimum follow up of two years. The mean age was 52.9 years (39-66, predominantly female (90%, six on the left shoulder. The time between onset of symptoms and surgical treatment ranged from six to 20 months. Four adhesive capsulitis were found to be primary (40% and six secondary (60%. RESULTS: the preoperative mean of active anterior elevation was 92°, of external rotation was 10.5° of the L5 level internal rotation; the postoperative ones were 149°, 40° and T12 level, respectively. Therefore, the average gain was 57° for the anterior elevation, 29.5° for external rotation in six spinous processes. There was a significant difference in movements' gains between the pre and post-operative periods (p<0.001. By the Constant Score (range of motion, there was an increase of 13.8 (average pre to 32 points (average post. CONCLUSION: the arthroscopic treatment proved effective in refractory adhesive capsulitis of the shoulder resistant to conservative treatment, improving the range of joint movements of patients evaluated after a minimum follow up of six years.
9. Myofibroblast Upregulators are Elevated in Joint Capsules in Posttraumatic Contractures
OpenAIRE
Hildebrand, Kevin A.; Zhang, Mei; Hart, David A.
2007-01-01
We hypothesized specific growth factors are increased in the elbow capsules of patients with post traumatic elbow contractures. A model of surgically induced joint contracture in rabbit knees was developed to study the growth factor expression in joint contractures. This study demonstrates this model mimics the human condition and analyzes how the growth factor levels decrease with time in rabbit knees with contractures. Reverse transcription polymerase chain reaction was used to measure mRNA...
10. An Innovative Wireless Endoscopic Capsule With Spherical Shape.
Science.gov (United States)
Fontana, Rossella; Mulana, Francesca; Cavallotti, Carmen; Tortora, Giuseppe; Vigliar, Mario; Vatteroni, Monica; Menciassi, Arianna
2017-02-01
This paper aims to contribute to the advancement of the Wireless Capsule Endoscopy (WCE) field for ColoRectal Cancer (CRC) screening, by developing all electronic circuits to build an innovative wireless endoscopic capsule with a spherical shape, conceived to reduce the friction during its locomotion and thus improving patient's acceptability. The proposed capsule embeds an image sensor with optics and Light Emitting Diodes (LEDs), a control unit with a telemetry module, an actuation system, a battery with a smart recharging circuit able to recharge in 20 minutes, a smart power-on circuit and a localization module. Everything is devised to fit in a small spherical shape with a diameter of 26 mm and a weight of 12.70 g. The authors present a description of the sub-modules involved in the capsule development, together with the firmware and hardware integration. In order to reduce the bandwidth for matching the specifications of the target commercial telemetry, the firmware interfacing of a custom encoder was performed, which is able to compress the incoming images with a negligible loss of information and occupying a number of Look Up-Tables (LUTs) less than 1780. As a preliminary work, a versatile Field Programmable Gate Arrays (FPGA) based demo-board system has been developed in order to test and optimize the functionalities and the performance of the single sub-modules and wireless vision chain system. This work allows to demonstrate the feasibility of a complex biomedical system, with severe constraints by highlighting the necessity to enhance the frame rate in the future.
11. 21 CFR 520.2100 - Selenium, vitamin E capsules.
Science.gov (United States)
2010-04-01
... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Selenium, vitamin E capsules. 520.2100 Section 520... to 1 milligram of selenium) and 56.2 milligrams of vitamin E (68 I.U.) (as d-alpha tocopheryl acid... of vitamin E (17 I.U.) (as d-alpha tocopheryl acid succinate.) (b) Sponsor. See No. 000061 in § 510...
12. Analysis of Bead Sizes for MR Capsules Labeled for Sprinkle
OpenAIRE
Nagavelli, Laxma R.; Lionberger, Robert A.; Sayeed, Vilayat A.; Yu, Lawrence; Allgire, James; Smith, Anjanette; Wokovich, Anna; Westenberger, Benjamin J.; Buhse, Lucinda
2010-01-01
The bead sizes used in approved modified release capsules labeled for sprinkling on food was investigated to generate bead size guidelines for generic products labeled for sprinkling. The conclusions from a survey of FDA databases were corroborated with experimental data obtained by measuring the bead sizes of several reference-listed drugs on the market labeled for administration by sprinkling on food. The experimental data show that majority of the marketed products were found to have bead ...
13. An ultra-low-power image compressor for capsule endoscope
OpenAIRE
Lin, Meng-Chun; Dung, Lan-Rong; Weng, Ping-Kuo
2006-01-01
Abstract Background Gastrointestinal (GI) endoscopy has been popularly applied for the diagnosis of diseases of the alimentary canal including Crohn's Disease, Celiac disease and other malabsorption disorders, benign and malignant tumors of the small intestine, vascular disorders and medication related small bowel injury. The wireless capsule endoscope has been successfully utilized to diagnose diseases of the small intestine and alleviate the discomfort and pain of patients. However, the res...
14. Capsule enteroscopy and radiology of the small intestine.
OpenAIRE
Fork, Thomas; Aabakken, Lars
2007-01-01
In a very few years, the video capsule for small bowel enteroscopy has gained widespread clinical acceptance. It is readily ingested, disposable, and allows for a complete, low-invasive endoscopic examination of the entire mucosa of the small bowel. It is a patient-friendly method and a first-line procedure in the difficult evaluation of obscure gastrointestinal bleeding. It has the highest proven figure of diagnostic sensitivity for detecting lesions of the mucosa, irrespective of aetiology....
15. First Metatarsal Head and Medial Eminence Widths with and Without Hallux Valgus.
Science.gov (United States)
Lenz, Robin C; Nagesh, Darshan; Park, Hannah K; Grady, John
2016-09-02
Resection of the medial eminence in hallux valgus surgery is common. True hypertrophy of the medial eminence in hallux valgus is debated. No studies have compared metatarsal head width in patients with hallux valgus and control patients. We reviewed 43 radiographs with hallux valgus and 27 without hallux valgus. We measured medial eminence width, first metatarsal head width, and first metatarsal shaft width in patients with and without radiographic hallux valgus. Medial eminence width was 1.12 mm larger in patients with hallux valgus (P hallux valgus (P hallux valgus. However, frontal plane rotation of the first metatarsal likely accounts for this difference.
16. Shock Timing and Yield Sensitivity Studies for NIF Ignition Capsules
International Nuclear Information System (INIS)
Olson, Richard E.
1999-01-01
A cryogenic, β-layered NIF ignition capsule with a beryllium ablator that employs a BeO dopant (2% O) for opacity control is described. The design has an optimized yield of 12 MJ and uses a reduced drive hohlraum temperature pulse shape that peaks at ∼ 250 eV. Shock timing sensitivity calculations have been performed for this capsule design. Individual uncertainties of: (1) ∼200 ps in the timing of the foot pulse; (2) ∼5% in the x-ray flux of the foot pulse and first step; (3) ∼10% in the ablator EOS; or (4) ∼ 5 microm in the DT ice layer thickness each have a significant impact on thermonuclear yield. Combined uncertainties have greater impact than isolated, individual issues. For example, a combination of uncertainties of 200 ps in the foot + 2 eV in the foot + 5 microm in the DT thickness results in a calculation that produces only ∼ 1% of the original design yield. A second, more speculative, capsule concept utilizing a liquid DT ablator is also discussed. This design produces a 5 MJ yield in a 250 eV peak drive calculation
17. Adhesive capsulitis and dynamic splinting: a controlled, cohort study
Directory of Open Access Journals (Sweden)
Willis F Buck
2009-09-01
Full Text Available Abstract Background Adhesive Capsulitis (AC affects patient of all ages, and stretching protocols are commonly prescribed for this condition. Dynamic splinting has been shown effective in contracture reduction from pathologies including Trismus to plantar fasciitis. The purpose of this study was to examine the efficacy of dynamic splinting on patients with AC. Methods This controlled, cohort study, was conducted at four physical therapy, sports medicine clinics in Texas and California. Sixty-two patients diagnosed with Stage II Adhesive Capsulitis were grouped by intervention. The intervention categories were as follows: Group I (Control; Group II (Physical Therapy exclusively with standardized protocols; Group III; (Shoulder Dynasplint system exclusively; Group IV (Combined treatment with Shoulder Dynasplint and standardized Physical Therapy. The duration of this study was 90 days for all groups, and the main outcome measures were change in active, external rotation. Results Significant difference was found for all treatment groups (p Conclusion The difference for the combined treatment group was attributed to patients' receiving the best PT combined with structured "home therapy" that contributed an additional 90 hours of end-range stretching. This adjunct should be included in the standard of care for adhesive Capsulitis. Trial Registration Trial Number: NCT00873158
18. Adhesive capsulitis of the hip: three case reports.
Science.gov (United States)
Joassin, R; Vandemeulebroucke, M; Nisolle, J-F; Hanson, P; Deltombe, T
2008-05-01
To describe the diagnosis and treatment of adhesive capsulitis of the hip (ACH). A literature review and consideration of three case reports. Adhesive capsulitis of the hip is a supposedly rare but probably underestimated condition which predominantly affects middle-aged women. Clinical assessment reveals a painful limitation of joint mobility. The diagnosis is confirmed by arthrography, where the crucial factor is a joint capacity below 12ml. Osteoarthritis and complex regional pain syndrome type 1 are the two main differential diagnoses. Whether the treatment is pharmacological, physical or surgical depends on the aetiology of the condition. Physiotherapy is essential for limiting residual deficits and functional impairments. Adhesive capsulitis of the hip is probably more common than suggested by the limited medical literature. The condition is frequently idiopathic but can be secondary to another joint pathology. The first-line treatment consists of sustained-release corticosteroid intra-articular injections and physical therapy. Arthroscopy and manipulation under anaesthesia may be useful in cases of ACH which are refractory to treatment.
19. Benchmarking uranyl peroxide capsule chemistry in organic media
International Nuclear Information System (INIS)
Neal, Harrison A.; Nyman, May; Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C.
2017-01-01
Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
20. Benchmarking uranyl peroxide capsule chemistry in organic media
Energy Technology Data Exchange (ETDEWEB)
Neal, Harrison A.; Nyman, May [Department of Chemistry, Oregon State University, Corvallis, OR (United States); Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN (United States)
2017-01-03
Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
1. Dumbbell formation for elastic capsules in nonlinear extensional Stokes flows
Science.gov (United States)
Dimitrakopoulos, P.
2017-06-01
Cross-slot and four-roll-mill microdevices are commonly used for particle manipulation and characterization owing to the stagnation-point flow at the device center. Because of the solid boundaries, these devices may generate extensional Stokes flows where the velocity is a nonlinear function of position associated with a decreased pressure at the particle edges and an increased pressure at the particle middle. Our computational investigation shows that in this class of Stokes flows, an elastic capsule made of a strain-hardening membrane develops two distinct steady-state conformations at strong flows, i.e., an elongated weak dumbbell shape with rounded edges at low flow nonlinearity and a laterally extended dumbbell shape at high flow nonlinearity. These effects are more pronounced for the less strain-hardening capsules which develop a flat extended middle where the two sides of the membrane approach each other. The strong stability properties of the strain-hardening capsules (owing to the development of strong membrane tensions) contrast significantly with the behavior of droplets in these nonlinear flows which are unable to achieve highly deformed steady-state dumbbell shapes owing to their constant surface tension.
2. Reduced anterior internal capsule white matter integrity in primary insomnia.
Science.gov (United States)
Spiegelhalder, Kai; Regen, Wolfram; Prem, Martin; Baglioni, Chiara; Nissen, Christoph; Feige, Bernd; Schnell, Susanne; Kiselev, Valerij G; Hennig, Jürgen; Riemann, Dieter
2014-07-01
Chronic insomnia is one of the most prevalent central nervous system diseases, however, its neurobiology is poorly understood. Up to now, nothing is known about the integrity of white matter tracts in insomnia patients. In this study, diffusion tensor imaging (DTI) was used in a well-characterized sample of primary insomnia (PI) patients and good sleeper controls to fill this void. Voxelwise between-group comparisons of fractional anisotropy (FA) were performed in 24 PI patients (10 males; 14 females; 42.7 ± 14.5 years) and 35 healthy good sleepers (15 males; 20 females; 40.1 ± 9.1 years) with age and sex as covariates. PI patients showed reduced FA values within the right anterior internal capsule and a trend for reduced FA values in the left anterior internal capsule. The results suggest that insomnia is associated with a reduced integrity of white matter tracts in the anterior internal capsule indicating that disturbed fronto-subcortical connectivity may be a cause or consequence of the disorder.
3. Liberty Bell 7 Space Capsule Exhibit previews at Visitor Complex
Science.gov (United States)
2000-01-01
Media gather at the KSC Visitor Complex for the kickoff of the Discovery Channel's Liberty Bell 7 Space Capsule Exhibit, which will open to the public on Saturday, June 17. At the podium is Mike Quattrone, executive vice president and general manager, Discovery Channel. Standing to the left of the podium is Rick Abramson, president and chief operating officer of Delaware North Parks Services of Spaceport, Inc., and far left, Jim Jennings, deputy director of Kennedy Space Center. Liberty Bell 7 launched U.S. Air Force Captain Virgil '''Gus''' Grissom July 21, 1961 on a mission that lasted 15 minutes and 37 seconds before sinking to the floor of the Atlantic Ocean, three miles deep. It lay undetected for nearly four decades before a Discovery Channel expedition located it and recovered it. The space capsule is now restored and preserved, and part of an interactive exhibit touring science centers and museums in 12 cities throughout the United States until 2003. The exhibit includes hands-on elements such as a capsule simulator, a centrifuge, and ROV pilot.
4. MRI diagnosis of reverse and separation of meniscus articular capsule
International Nuclear Information System (INIS)
Tang Xiaofeng; Zhou Chengtao; Mu Renqi; Zhang Guanghui; Xu Yongzhong
2005-01-01
Objective: To explore the MR imaging of reverse and separation of meniscal articular capsule. Methods: MR imaging of reverse and separation of meniscus articular capsule confirmed by surgery and arthroscope were analyzed retrospectively in 8 cases. Results: The 'Butterfly knot sign' disappeared and was replaced with fluid signal on the sagittal slice of meniscal body in 8 cases. Part of back angle remained in 3 cases. 'Double anterior cruciate ligament sign' was showed on one side of middle sagittal slice in 7 cases. 'Reverse meniscus sign' was revealed in intercondylar fossa on the coronary view in 8 cases. Abnormal high signal was showed in the injured meniscus in 6 cases. Abnormal high signal was detected in the opposite meniscus in 5 cases. Conclusion: The MR findings of reverse and separation of meniscus articular capsule include disappearance of 'butterfly knot sign', appearance of 'reverse meniscus sign' and 'double anterior cruciate ligament sign'. The diagnosis would be established if the former 2 signs were present or all the 3 signs were present simultaneously. (authors)
5. Technology Insight: current status of video capsule endoscopy.
Science.gov (United States)
Cave, David R
2006-03-01
Video capsule endoscopy (VCE) is the most recent major practical and conceptual development in the field of endoscopy. The video capsule endoscope-a small, pill-sized, passive imaging device-has been demonstrated to be the pre-eminent imaging device for disorders of the small intestine. The initial use for VCE was to detect the origin of obscure gastrointestinal bleeding. Several other indications have now been justified, or are in the process of evaluation. More than 200,000 of these disposable devices have been used worldwide, with an extraordinarily good safety record: indeed, the device has been approved for use in children as young as 10 years of age. In addition, a double-ended capsule has now been approved for the evaluation of mucosal disease in the esophagus. The now-widespread deployment of the device into gastrointestinal practice in the US and many other countries suggests that VCE has achieved mainstream utility. The development of similar competitor devices, and devices whose movement can be controlled, is in progress.
6. Controllable light capsules employing modified Bessel-Gauss beams.
Science.gov (United States)
Gong, Lei; Liu, Weiwei; Zhao, Qian; Ren, Yuxuan; Qiu, Xingze; Zhong, Mincheng; Li, Yinmei
2016-07-08
We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms.
7. In-Situ Preparation of Radioactive Tracers in NIF Capsules
Science.gov (United States)
Stoyer, Mark
2011-04-01
Inertial Confinement Fusion (ICF) experiments at the National Ignition Facility (NIF) will probe fundamental high energy density physics of plasmas. Radiochemical diagnostics will provide information on ablator and fuel rho-R, yield, asymmetry, and mix by collecting both gaseous and solid debris samples following an implosion. Many experiments utilize ratios of produced activities, but full utilization of the technique requires knowledge of sample collection efficiencies. Gaseous samples are expected to be collected with high efficiency, but solid sample collection is typically limited by location of the collecting apparatus. Activation of ICF capsules has been utilized at other laser facilities [1-2] to produce a radioactive tracer in the ablator of the capsule that can be used to measure the solid collection efficiency. This talk will describe preliminary experiments activating CH(Ge) NIF capsules and Au hohlraums in the High Flux Isotope Reactor (HFIR) at ORNL in order to produce Ge, As, and Au isotopes for determination of collection efficiency, spatial distribution of the debris, efficacy of various collectors, and if there are preferred locations for debris collection. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. S.M. Lane and M.B. Nelson, Rev. Sci. Inst. 61 (1990) 3298.
8. Polarized Electrons at Jefferson Laboratory
Energy Technology Data Exchange (ETDEWEB)
Sinclair, C.K.
1997-12-31
The CEBAF accelerator at Jefferson laboratory can deliver CW electron beams to three experimental halls simultaneously. A large fraction of the approved scientific program at the lab requires polarized electron beams. Many of these experiments, both polarized and unpolarized, require high average beam current as well. Since all electrons delivered to the experimental halls originate from the same cathode, delivery of polarized beam to a single hall requires using the polarized source to deliver beam to all experiments in simultaneous operation. The polarized source effort at Jefferson Lab is directed at obtaining very long polarized source operational lifetimes at high average current and beam polarization; at developing the capability to deliver all electrons leaving the polarized source to the experimental halls; and at delivering polarized beam to multiple experimental halls simultaneously.initial operational experience with the polarized source will be presented.
9. Polarized electrons at Jefferson laboratory
International Nuclear Information System (INIS)
The CEBAF accelerator at Jefferson laboratory can deliver CW electron beams to three experimental halls simultaneously. A large fraction of the approved scientific program at the lab requires polarized electron beams. Many of these experiments, both polarized and unpolarized, require high average beam current as well. Since all electrons delivered to the experimental halls originate from the same cathode, delivery of polarized beam to a single hall requires using the polarized source to deliver beam to all experiments in simultaneous operation. The polarized source effort at Jefferson Lab is directed at obtaining very long polarized source operational lifetimes at high average current and beam polarization; at developing the capability to deliver all electrons leaving the polarized source to the experimental halls; and at delivering polarized beam to multiple experimental halls simultaneously. Initial operational experience with the polarized source will be presented
10. Polar low monitoring
Science.gov (United States)
Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid
2010-05-01
Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite
11. Micromagnetic investigation of the dynamics of magnetization switching induced by a spin polarized current
Science.gov (United States)
Lee, Kyung-Jin; Dieny, Bernard
2006-03-01
Using micromagnetic modeling, we tested a prediction of single-domain spin-torque theory which switching current density depends only weakly on magnetic cell size. The switching time and current density are strongly affected by the cell size for low spin polarization. Larger samples with a small length-to-width ratio and small spin polarization can exhibit a nonmonotonous dependence of switching time on current. Excitation of incoherent spin waves caused by the circular Oersted field due to the current is responsible for this nonmonotonous dependence. However, the magnetic dynamics recovers a single-domain-like behavior when the spin polarization is high and/or the cell size is small.
12. Polarized protons at RHIC
International Nuclear Information System (INIS)
Tannenbaum, M.J.
1990-12-01
The Physics case is presented for the use of polarized protons at RHIC for one or two months each year. This would provide a facility with polarizations of approx-gt 50% high luminosity ∼2.0 x 10 32 cm -2 s -1 , the possibility of both longitudinal and transverse polarization at the interaction regions, and frequent polarization reversal for control of systematic errors. The annual integrated luminosity for such running (∼10 6 sec per year) would be ∫ Ldt = 2 x 10 38 cm -2 -- roughly 20 times the total luminosity integrated in ∼ 10 years of operation of the CERN Collider (∼10 inverse picobarns, 10 37 cm -2 ). This facility would be unique in the ability to perform parity-violating measurements and polarization test of QCD. Also, the existence of p-p collisions in a new energy range would permit the study of ''classical'' reactions like the total cross section and elastic scattering, etc., and serve as a complement to measurements from p-bar p colliders. 11 refs
13. The Bochum Polarized Target
International Nuclear Information System (INIS)
Reicherz, G.; Goertz, S.; Harmsen, J.; Heckmann, J.; Meier, A.; Meyer, W.; Radtke, E.
2001-01-01
The Bochum 'Polarized Target' group develops the target material 6 LiD for the COMPASS experiment at CERN. Several different materials like alcohols, alcanes and ammonia are under investigation. Solid State Targets are polarized in magnetic fields higher than B=2.5T and at temperatures below T=1K. For the Dynamic Nuclear Polarization process, paramagnetic centers are induced chemically or by irradiation with ionizing beams. The radical density is a critical factor for optimization of polarization and relaxation times at adequate magnetic fields and temperatures. In a high sensitive EPR--apparatus, an evaporator and a dilution cryostat with a continuous wave NMR--system, the materials are investigated and optimized. To improve the polarization measurement, the Liverpool NMR-box is modified by exchanging the fixed capacitor for a varicap diode which not only makes the tuning very easy but also provides a continuously tuned circuit. The dependence of the signal area upon the circuit current is measured and it is shown that it follows a linear function
14. Maxillary arch width and buccal corridor changes with Damon and conventional brackets: A retrospective analysis.
Science.gov (United States)
Shook, Corey; Kim, Sohyon Michelle; Burnheimer, John
2016-07-01
To evaluate the effect of Damon self-ligating and conventional bracket systems on buccal corridor widths and areas. A retrospective sample of consecutively treated patients using either conventional (CG, n = 45) or Damon self-ligating (SL, n = 39) brackets was analyzed to determine any differences in buccal corridor widths and areas both within and between groups. Pretreatment and posttreatment frontal photographs were transferred to Photoshop CC, standardized using intercanthal width, and linear and area measurements were performed with tools in Photoshop CC. Ratios were then calculated for statistical analysis. Relationships between arch widths and buccal corridors were also examined. There were no significant differences in the posttreatment intercanine or intermolar widths either within or between the CG and SL groups. There were no significant differences in any buccal corridor width or area measurement either within or between the CG and SL groups. There were strong correlations with the intercanine width and the corresponding buccal corridor smile width measurements. There was an inverse correlation with the buccal corridor area in relation to the canine and the total smile width. It is likely that posttreatment increases in arch width can be seen in patients treated with either a conventional bracket system or the Damon system. It is highly unlikely that there is any significant difference in buccal corridor width or area in patients treated with the Damon self-ligating system or a conventional bracket system.
15. In-line Fiber Polarizer
OpenAIRE
Perumalsamy, Priya
1998-01-01
Polarizers and polarization devices are important components in fiber optic communication and sensor systems. There is a growing need for efficient low loss components that are compatible with optical fibers. An all fiber in-line polarizer is a more desirable alternative that could be placed at appropriate intervals along communication links. An in-line fiber polarizer was fabricated and tested. The in-line fiber polarizer operates by coupling optical energy propagatin...
16. On-line multi-bed sorption trap for VOC analysis of large-volume vapor samples: injection plug width, effects of water vapor and sample decomposition.
Science.gov (United States)
Sanchez, Juan M; Sacks, Richard D
2005-01-01
A multibed on-line sorption trap is used to preconcentrate organic vapors from air samples and inject the analytes into a GC separation column. Injection plug widths depend on the boiling point for the lipophilic compounds and on the polarity and boiling point for the polar compounds. Injection plug widths are sufficiently small (0.7-0.8 s) as to allow the direct injection of the most volatile compounds into the GC column without the need for a second focusing device. The presence of water in the samples has an effect on the retention of polar compounds by the trap. However, this effect is reproducible for a fixed water content and so can be overcome by using calibration standards under the same conditions of humidity as the samples. The thermal decomposition of many volatile organic compounds in an on-line sorption trap during the GC analysis of air samples is examined. The results show that degradation of unstable compounds is governed by the amount of heat transferred to the compounds during desorption (i.e., applied temperature and pulse duration). The use of an on-line trap results in the immediate transfer of desorbed compounds to the analytical column, which can reduce the formation of artifacts.
17. Width of gene expression profile drives alternative splicing.
Directory of Open Access Journals (Sweden)
Daniel Wegmann
Full Text Available Alternative splicing generates an enormous amount of functional and proteomic diversity in metazoan organisms. This process is probably central to the macromolecular and cellular complexity of higher eukaryotes. While most studies have focused on the molecular mechanism triggering and controlling alternative splicing, as well as on its incidence in different species, its maintenance and evolution within populations has been little investigated. Here, we propose to address these questions by comparing the structural characteristics as well as the functional and transcriptional profiles of genes with monomorphic or polymorphic splicing, referred to as MS and PS genes, respectively. We find that MS and PS genes differ particularly in the number of tissues and cell types where they are expressed.We find a striking deficit of PS genes on the sex chromosomes, particularly on the Y chromosome where it is shown not to be due to the observed lower breadth of expression of genes on that chromosome. The development of a simple model of evolution of cis-regulated alternative splicing leads to predictions in agreement with these observations. It further predicts the conditions for the emergence and the maintenance of cis-regulated alternative splicing, which are both favored by the tissue specific expression of splicing variants. We finally propose that the width of the gene expression profile is an essential factor for the acquisition of new transcript isoforms that could later be maintained by a new form of balancing selection.
18. Bowman Capsulitis Predicts Poor Kidney Allograft Outcome in T Cell-Mediated Rejection.
Science.gov (United States)
Gallan, Alexander J; Chon, W James; Josephson, Michelle A; Cunningham, Patrick N; Henriksen, Kammi J; Chang, Anthony
2018-02-28
Acute T cell-mediated rejection (TCMR) is an important cause of renal allograft loss. The Banff classification for tubulointerstitial (type I) rejection is based on the extent of both interstitial inflammation and tubulitis. Lymphocytes may also be present between parietal epithelial cells and Bowman capsules in this setting, which we have termed "capsulitis." We conducted this study to determine the clinical significance of capsulitis. We identified 42 patients from the pathology archives at the University of Chicago with isolated Banff type I TCMR from 2010-2015. Patient demographic data, Banff classification, and graft outcome measurements were compared between capsulitis and non-capsulitis groups using Mann-Whitney U test. Capsulitis was present in 26 (62%), and was more frequently seen in Banff IB than IA TCMR (88% vs 44%, P=.01). Patients with capsulitis had a higher serum creatinine at biopsy (4.6 vs 2.9mg/dL, P=.04) and were more likely to progress to dialysis (42% vs 13%, P=.06) with fewer recovering their baseline serum creatinine (12% vs 38%, P=.08). Patients with both Banff IA TCMR and capsulitis have clinical outcomes similar or possibly worse than Banff IB TCMR compared to those with Banff IA and an absence of capsulitis. Capsulitis is an important pathologic parameter in the evaluation of kidney transplant biopsies with potential diagnostic, prognostic, and therapeutic implications in the setting of TCMR. Copyright © 2018. Published by Elsevier Inc.
19. Current applications and potential future role of wireless capsule technology in Crohn's disease.
Science.gov (United States)
Hall, Barry; Holleran, Grainne; McNamara, Deirdre
2014-11-01
The development of capsule technology has modified our approach to the diagnosis of gastrointestinal disease. The relatively rapid uptake of capsule endoscopy as an important clinical tool can be largely ascribed to a number of key factors, including the fact that it is a relatively easy examination to perform in an outpatient setting. It has been established as an integral part of the investigation pathway for obscure gastrointestinal bleeding and suspected small bowel Crohn's disease (CD). CURRENT USE OF CAPSULE ENDOSCOPY: Small bowel CD can be a challenging entity to diagnose. Capsule endoscopy has been shown to be both useful and safe in patients with both suspected and established small bowel CD. In suspected disease, capsule endoscopy has both a high diagnostic yield and negative predictive value. Capsule findings lead to changes in management in up to 73% of patients with established CD. However, while the technology appears capable of detecting subtle mucosal changes not readily apparent on alternate imaging modalities, the question of what actually constitutes small bowel CD as described by capsule is an issue that remains unresolved to date. Thus, capsule endoscopy is best utilised in tandem with advanced imaging and endoscopic techniques such as balloon- assisted enteroscopy. The development of a capsule capable of viewing the colon coupled with improvements in image quality and battery life are likely to lead to the increasing uptake of this technology. In the future, 'interactive' capsules with the ability to view the entire gastrointestinal tract may be a reality.
20. The roles of Tenascin C and Fibronectin 1 in adhesive capsulitis: a pilot gene expression study.
Science.gov (United States)
Cohen, Carina; Leal, Mariana Ferreira; Belangero, Paulo Santoro; Figueiredo, Eduardo Antônio; Smith, Marília Cardoso; Andreoli, Carlos Vicente; de Castro Pochini, Alberto; Cohen, Moises; Ejnisman, Benno; Faloppa, Flávio
2016-07-01
We evaluated mRNA expression levels of genes that encode TGF-β1; the TGF-β1 receptor; the collagen-modifying enzymes LOX, PLOD1, and PLOD2; and the extracellular matrix proteins COMP, FN1, TNC and TNXB in synovial/capsule specimens from patients with idiopathic adhesive capsulitis. Possible associations between the measured mRNA levels and clinical parameters were also investigated. We obtained glenohumeral joint synovium/capsule specimens from 9 patients with idiopathic adhesive capsulitis who had not shown improvement in symptoms after 5 months of physiotherapy. Adhesive capsulitis was confirmed in all patients by magnetic resonance imaging. We also obtained specimens from 8 control patients who had underwent surgery for acute acromioclavicular joint dislocation and who had radiological indication of glenohumeral capsule alteration based on arthroscopic evaluation. mRNA expression in the synovium/capsule specimens was analyzed by quantitative reverse transcription PCR. The B2M and HPRT1 genes were used as references to normalize target gene expression in the shoulder tissue samples. The synovium/capsule samples from the patients with adhesive capsulitis had significantly higher TNC and FN1 expression than those from the controls. Additionally, symptom duration directly correlated with expression of TGFβ1 receptor I. Elevated levels of TNC and FN1 expression may be a marker of capsule injury. Upregulation of TGFβ1 receptor I seems to be dependent on symptom duration; therefore, TGFβ signaling may be involved in adhesive capsulitis. As such, TNC, FN1 and TGFβ1 receptor I may also play roles in adhesive capsulitis by contributing to capsule inflammation and fibrosis. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.68958580493927, "perplexity": 8732.181336982318}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794867841.63/warc/CC-MAIN-20180526170654-20180526190654-00013.warc.gz"} |
http://mathoverflow.net/questions/16837/cone-of-curves-and-mori-theorem-for-algebraic-surfaces?sort=votes | # Cone of curves and Mori Theorem for algebraic Surfaces
In describing part of the geometry of the cone of curves for an algebraic surface $S$, we need to find $(-1)$ curves within $S$. Once we've done that, then we can say that the "negative" part of the cone of curves has as many extremal rays as $(-1)$ curves. Here I am using the cone theorem: $$\overline{NE}(S)=\overline{NE}(S)_{K_S\geq 0}+\sum_i \mathbb{R}^+[C_i]$$ where $C$ are such negative self-intersection rational curves.
However, is there an intuitive argument showing that if we have a curve of negative self-intersection, then such a curve is going to generate a extremal ray in the cone of curves?
What is known about this "positive" part $\overline{NE}(S)_{K_S\geq 0}$ of the cone describe in the theorem?
-
That looks like an interesting theorem! Could you provide a link for those new to it, please? – Ilya Nikokoshev Mar 2 '10 at 9:52
Sure, Wikipedia has two excellent references en.wikipedia.org/wiki/Cone_of_curves – Csar Lozano Huerta Mar 2 '10 at 15:42
Your second sentence is not right as stated. Every rational curve of negative self-intersection yields an extremal ray, not only (-1)-curves. – Andrea Ferretti Apr 14 '10 at 13:50
That's right...got it. Thks! – Csar Lozano Huerta Apr 14 '10 at 14:29
EDIT: We may assume that the Picard number is at least two, as otherwise the cone is simply a ray generated by any effective curve. In particular, every effective curve is extremal. I will also assume that "curve" means "effective curve". (This edit was prompted by Damiano's comment that is now (sadly) deleted. It was a useful contribution.)
A curve on a surface is simultaneously a curve and a divisor and assuming the surface is smooth or at least $\mathbb Q$-factorial, then the curve, as a divisor, induces a linear functional on $1$-cycles. This works better if the surface is proper, so let's assume that.
So, if $C$ is such a curve, then the corresponding linear function on the space where $NE(S)$ lives is best represented by the hyperplane on which it vanishes and remembering which side is positive and which one is negative.
If $C$ is reducible, then it may have negative self-intersection, but it is not extremal. For an example, blow up two separate points on a smooth surface and take the sum of the exceptional divisors. My guess is that you meant irreducible, so let's assume that.
Now we have $3$ cases:
1) $C^2>0$. In this case $C$ is in the interior of the cone and it cannot be extremal, can't even be on the boundary (Use Riemann-Roch to prove this).
2) $C^2=0$. Since $C$ is irreducible, it follows that it is nef and hence a limit of ample classes, so it is effective, but as Damiano pointed out I have already assumed that. (It is left to the reader to rephrase this if $C$ is assumed to be nef instead of effective). In this case the hyperplane corresponding to $C$ as a linear functional is a supporting hyperplane of the cone, intersecting it at least in the ray generated by $C$. So $C$ is definitely on the boundary, but it may or may not be extremal depending on the surface. For example any curve of self-intersection $0$ on an abelian surface is extremal, but for instance a member of a fibration that also has reducible fibers is not extremal despite being irreducible. For the latter think of a K3 surface with an elliptic fibration that has some $(-2)$-curves contained in some fibers.
3) $C^2<0$. If $C$ is effective, then $C\cdot D>0$ for any irreducible curve $D\neq C$. This means that $C$ and all other irreducible curves lie on different sides of the hyperplane corresponding to $C$ as a linear functional, so the convex cone they generate must have $C$ generating an extremal ray.
Observe that we did not use the Cone Theorem. In fact one gets a different "cone theorem" this way:
Theorem Let $S$ be a smooth projective surface $H$ an arbitrary ample divisor on $S$ and let $$Q^+=\{\sigma\in N_1(S) \vert \sigma^2 >0, H\cdot\sigma \geq 0 \}$$ be the "positive component" of the interior of the quadric cone defined by the intersection pairing. Then $$\overline{NE}(S) = \overline{Q^+} + \sum_{C^2<0} \mathbb R_+[C]$$
There is also one for $K3$'S, using the above notation:
Theorem Let $S$ be a smooth algebraic K3 surface and assume that its Picard number is at least $3$. (If the Picard number is at most $2$, then there are not too many choices for a cone). Then one of the following holds:
(i) $$\overline{NE}(S) = \overline{Q^+}, or$$
(ii) $$\overline{NE}(S) = \overline{\sum_{C\simeq \mathbb P^1, C^2<0} \mathbb R_+[C]}.$$ The two cases are distinguished by the fact whether there exists a curve in $S$ with negative self-intersection. If the Picard number is at least $12$, then only (ii) is possible.
For proofs and more details, see this paper.
-
Hi damiano, yes, you are right, but... 1) The question is not interesting otherwise. If the Picard number is one, the cone is just a ray and every effective curve is extremal (belonging to the same extremal ray). But I should have said so. 2) I suppose you are referring to the comment that effective is not needed. When I wrote that I was going to write something different and did not go back to fix it. I will edit it now. – Sándor Kovács Oct 19 '10 at 9:28
I agree that I was being very picky, and I had given you my vote! I have also erased my previous comment, as no longer relevant. d – damiano Oct 19 '10 at 9:47
A curve (irreducible reduced divisor) C with negative selfintersection is always an extremal ray. To see it, first observe that C is the only effective divisor in its complete linear system |C| (if D~C, then C·D=C²<0 so C is a component of D, and therefore D=C), and for the same reason nC is the only effective divisor in |nC|. Now, if C were not extremal it would be possible to express it as the sum of two things in the Mori cone, which means you could write nC~D+E for some n, with D and E nontrivial effective divisors. This is a contradiction.
On the positive part, I believe the most difficult case is rational surfaces, see a recent preprint by Tommaso de Fernex arXiv:1001.5243. I also think in Lazarsfeld's book (Positivity in Algebraic Geometry) there are a few examples, including ones in which the positive part is "round" (part of its border is defined by the quadratic equation $C²\ge 0$).
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One further comment (which I can't add as a comment due to lack of reputation): in the case where S is the blowup of the projective plane in $r \geq 10$ very general points (for smaller r, the K-nonnegative part of the cone of curves is either empty or a single ray), Nagata's conjecture on curves predicts the following upper bound: if there exists a curve C whose projection to the plane has degree d and passes through the blown-up points p_1,...,p_r with multiplicities m_1,...,m_r, then we have
$$d > \frac{1}{\sqrt r} \ \sum_{i=1}^r m_i$$
To take a very simple case, this says that there cannot exist a cubic curve passing through 10 very general points in the plane (which of course we already know), or equivalently that the cone of curves of the blowup doesn't contain the K-positive vector 3L-L_1-...-L_10. (Here L is the class in N^1(S) of the line in the plane, and L_i the class of the exceptional curve of the blowup of p_i).
- | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9399359822273254, "perplexity": 246.06870866371764}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440644064590.32/warc/CC-MAIN-20150827025424-00087-ip-10-171-96-226.ec2.internal.warc.gz"} |
https://www.bas.ac.uk/data/our-data/publication/diet-and-reproductive-success-of-adelie-and-chinstrap-penguins-linking/ | # Diet and reproductive success of Adélie and chinstrap penguins: linking response of predators to prey population dynamics
The diet and reproductive performance of two sympatric penguin species were studied at Signy Island, South Orkney Islands between 1997 and 2001. Each year, Adelie (Pygoscelis adeliae) and chinstrap (P. antarctica) penguins fed almost exclusively (>99% by mass) on Antarctic krill; however, there was considerable inter-annual variation in reproductive output. In 1998, chinstrap penguins were adversely affected by extensive sea-ice in the vicinity of the colony, whereas Adelie penguins were unaffected by this. However, in 2000, both species suffered reduced reproductive output. Detailed analysis of the population-size structure of krill in the diet indicated a lack of recruitment of small krill into the population since 1996. A simple model of krill growth and mortality indicated that the biomass represented by the last recruiting cohort would decline dramatically between 1999 and 2000. Thus, despite the lack of a change in the proportion of krill in the diet, the population demographics of the krill population suggested that the abundance of krill may have fallen below the level required to support normal breeding success of penguins sometime before or during the 2000 breeding season. The role of marine predators as indicator species is greatly enhanced when studies provide data reflecting not only the consequences of changes in the ecosystem but also those data that elucidate the causes of such changes.
### Details
Publication status:
Published
Author(s):
Authors: Lynnes, A.S., Reid, K., Croxall, J.P.
Date:
1 January, 2004
Journal/Source:
Polar Biology / 27
Page(s):
544-554
Digital Object Identifier (DOI):
https://doi.org/10.1007/s00300-004-0617-1 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8016712665557861, "perplexity": 9447.255567441609}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875147116.85/warc/CC-MAIN-20200228073640-20200228103640-00019.warc.gz"} |
http://www.r-bloggers.com/translating-between-r-and-sql-the-basics/ | # Translating between R and SQL: the basics
November 8, 2013
By
(This article was first published on Burns Statistics » R language, and kindly contributed to R-bloggers)
An introductory comparison of using the two languages.
## Background
R was made especially for data analysis and graphics. SQL was made especially for databases. They are allies.
The data structure in R that most closely matches a SQL table is a data frame. The terms rows and columns are used in both.
## A mashup
There is an R package called sqldf that allows you to use SQL commands to extract data from an R data frame. We will use this package in the examples. There are two basic steps to using an R package:
• it must be installed on your machine (once)
• it must be available in each R session where it is used
You can use sqldf by doing (one time only, and assuming an internet connection):
install.packages("sqldf")
Then in each R session where you want to use it:
require(sqldf)
To simplify the examples, we’ll slightly modify one of the inbuilt data frames:
myCO2 <- CO2
attributes(myCO2) <- attributes(CO2)[
c("names", "row.names", "class")]
class(myCO2) <- "data.frame"
Note that the character between C and 2 is a capital-O and not a zero. The CO2 object has a complicated value for its class but the result of the sqldf function has only "data.frame" in its class. We want to cleanly see if two objects are the same, and hence we want the classes to match.
## Column names
In R the colnames function returns the names of the columns:
> colnames(myCO2)
[1] "Plant" "Type" "Treatment" "conc"
[5] "uptake"
The result is a vector of character strings.
## Subsetting columns
Columns in SQL are also called “fields”. In R it is rather common for columns to be called “variables”.
In SQL the subset of columns is determined by select. Here we want to get the Type and conc columns:
s01 <- sqldf("select Type, conc from myCO2")
Subsetting in R (commonly called “subscripting”) is done with square brackets. When subscripting a data frame there will be two places inside the square brackets separated by a comma. The R equivalent of the command above is:
r01 <- myCO2[, c("Type", "conc")]
The first part inside the square brackets (corresponding to rows) is empty. The second part (corresponding to columns) has a character vector with the names of the two columns we want.
We can test that r01 and s01 are the same:
> all.equal(s01, r01)
[1] TRUE
In R the vector of column names could be created as an object and then used in the subscripting:
someCols <- c("Type", "conc")
r01b <- myCO2[, someCols]
The r01 and r01b objects are the same.
### All columns
An asterisk is used in SQL to indicate that you want all columns:
s02 <- sqldf("select * from myCO2")
When you want all items in a dimension in R, you leave it blank:
r02 <- myCO2[ , ]
You might have been able to guess that because we’ve seen that done for rows already. Note that spaces almost never matter in R — the command above has spaces either side of the comma, but would be exactly the same with no spaces.
### Only one column
How to select only a single column is no surprise in either language:
s03 <- sqldf("select Type from myCO2")
r03 <- myCO2[ , "Type"]
But there is a surprise when you test if these two objects are equal:
all.equal(s03, r03)
The command above results in a bunch of stuff, indicating they are quite different.
The r03 object is not a data frame, it is an object of the type of the column. While surprising to those used to SQL, this is quite natural for R’s purposes. For example, we give the mean function a vector of numbers, not a data frame:
> mean(myCO2[, "uptake"])
[1] 27.2131
You can get a one-column data frame by slightly modifying the command:
r03d <- myCO2[ , "Type", drop=FALSE]
The s03 and r03d objects are the same.
Data frames are not natural inputs to some functions:
> mean(myCO2[, "uptake", drop=FALSE])
[1] NA
Warning message:
In mean.default(myCO2[, "uptake", drop = FALSE]) :
argument is not numeric or logical: returning NA
### Case sensitivity
SQL is not case-sensitive:
s04 <- sqldf("select type, coNC from myCO2")
s04 is the same as s01.
On the other hand, R is case-sensitive:
> r04 <- myCO2[, c("type", "coNC")]
Error in [.data.frame(myCO2, , c("type", "coNC")) :
undefined columns selected
### R extensions
We've seen how to select columns of an R data frame with the names of the columns. There are other ways of selecting columns as well.
The order of the columns in an R data frame is of significance. You can select columns by number. For example, you can select column 5 and then column 2:
myCO2[, c(5, 2)]
You can use negative numbers to exclude columns. Here you are asking for all columns except the first and the fourth:
myCO2[, c(-1, -4)]
Column selection in R can also be done with logical values:
myCO2[, c(TRUE, FALSE, FALSE, TRUE, FALSE)]
Those logical values can be created by a command:
myCO2[, colnames(myCO2) > "d"]
## Subsetting rows
In SQL a common synonym for “row” is “record”. In R a common synonym is “observation”.
### Conditions
The common way of getting a subset of rows in SQL is with the where command:
s05 <- sqldf("select * from myCO2 where uptake < 20")
In R the equivalent of the where is put in the first position inside the square brackets:
r05 <- myCO2[ myCO2[, "uptake"] < 20, ]
s05 and r05 are in most respects the same. The difference is that the row names are different. r05 has the row names from the original data frame while s05 has new ones that are sequential from 1.
### with
The command that created r05 is a little convoluted (but logical once you stare at it long enough). The with function allows a command that is more in the spirit of what is done in SQL:
r05w <- with(myCO2, myCO2[uptake < 20, ]) # same as r05
Inside the with call the columns of the data frame named in the first argument can be used as objects. In this example uptake is used directly instead of pulling that column out of the data frame.
### Logical operators
Logical comparisons in SQL are combined with AND and OR:
s06 <- sqldf("select * from myCO2 where uptake < 20 and Type='Quebec'")
Also note that testing equality is with =.
In R this type of ‘and’ operation is done with & and the ‘or’ is |:
r06 <- with(myCO2, myCO2[uptake < 20 & Type == 'Quebec', ])
A possible trouble spot is that equality in R is tested with == (while = is an assignment operator).
The s06 and r06 objects are the same except for their row names.
### First few
The limit command in SQL limits the number of rows that are given:
s07 <- sqldf("select * from myC02 limit 6")
One way to see just the column names is to limit the number of rows to zero.
You can get the first few rows in R with head:
r07 <- head(myCO2)
The tail function gives you the last few rows, and the corner function is a logical extension of head and tail.
### Row names versus numbers
A source of possible confusion is that row names are character even though they are, by default, representations of numbers. Let’s experiment with r06:
> r06
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16.0
8 Qn2 Quebec nonchilled 95 13.6
15 Qn3 Quebec nonchilled 95 16.2
22 Qc1 Quebec chilled 95 14.2
29 Qc2 Quebec chilled 95 9.3
36 Qc3 Quebec chilled 95 15.1
Select the first three rows:
> r06[1:3,]
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16.0
8 Qn2 Quebec nonchilled 95 13.6
15 Qn3 Quebec nonchilled 95 16.2
Now let’s select the characters one through three:
> r06[c 1=""2"," 2=""3")," language="("1","][/c]
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16.0
NA <NA> <NA> <NA> NA NA
36 Qc3 Quebec chilled 95 15.1
What happened? The first row is correct — the first row name is 1. In the second row it looked for a row name called “2″ and didn’t find one, so it put in missing values. The third row is even weirder: it looked for a row name called “3″; there was a single row name starting with “3″ so it did a partial match and gave us that row.
Trying to give numbers instead of the actual names doesn’t necessarily work either:
> r06[c 1="8," 2="15)," language="(1,"][/c]
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16
NA <NA> <NA> <NA> NA NA
NA.1 <NA> <NA> <NA> NA NA
### NULL
In SQL NULL means missing value. Confusingly R also has NULL but the equivalent of SQL NULL is NA in R.
Let’s create some data to play with:
r08 <- r06
r08[2:4, 1] <- NA
r08[5, 4] <- NA
This looks like:
> r08
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16.0
8 <NA> Quebec nonchilled 95 13.6
15 <NA> Quebec nonchilled 95 16.2
22 <NA> Quebec chilled 95 14.2
29 Qc2 Quebec chilled NA 9.3
36 Qc3 Quebec chilled 95 15.1
Get the rows where Plant is not missing:
s09 <- sqldf("select * from r08 where plant is not null")
r09 <- with(r08, r08[!is.na(Plant), ])
We can also get the rows where Plant is missing:
s10 <- sqldf("select * from r08 where plant is null")
r10 <- with(r08, r08[is.na(Plant), ])
To get the rows that have no missing values in R, you can do:
> na.omit(r08)
Plant Type Treatment conc uptake
1 Qn1 Quebec nonchilled 95 16.0
36 Qc3 Quebec chilled 95 15.1
### Quotes
In SQL single quotes are used to delimit character strings. A single quote inside a string is given with two single quotes in a row. Some implementations allow you to specify the delimiter.
In R either single quotes or double quotes can be used. You can use whichever you find more convenient but R always prints using double quotes. The backslash is used to escape a quote character that is the same as the delimiting quote:
> c("he's", 'he\'s', "she has \"it\"")
[1] "he's" "he's" "she has \"it\""
### Semicolons
Semicolons are sometimes used at the end of statements in both SQL and R.
Some SQL implementations require a semicolon at the end of a statement.
Semicolons are used to separate R commands on the same line. They can be used after all R commands, but probably shouldn’t be.
### Single subscript
Note that both
r06[1:3, ]
and
r06[1:3]
are legal R commands, but they do different things. The first gives the first three rows and all of the columns; the second gives all of the rows and the first three columns (for a reason you need not be concerned about initially).
## Efficiency
If a data frame is large and the manipulation is complex, then R can be inefficient. Why should someone with access to a database put up with such inefficiency? One reason is the flexibility that R gives you. It might surprise some people that not all data naturally fit into a structure of rows and columns. Besides it usually doesn’t matter. As has been asked facetiously by a certain someone: “What are you going to do with that extra millisecond?”
But if there are millions of those milliseconds, then you might start to care. The data.table package provides an alternative form of data frames that is highly efficient.
## Resources to learn R
“Impatient R” is a minimal set of things to learn about R.
“Some hints for the R beginner” suggests additional resources.
## Resources to learn SQL
I’m certainly no expert at learning materials for SQL — please make suggestions. But here are things I’ve found that seem at least okay:
SQLZoo provides quite a nice interactive set of exercises.
Tutorialspoint has information easily arranged for learning and refreshing.
“R database interfaces”
“Select operations on R data frames”
The post Translating between R and SQL: the basics appeared first on Burns Statistics. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.49950602650642395, "perplexity": 9707.974165088492}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-49/segments/1416931008720.43/warc/CC-MAIN-20141125155648-00131-ip-10-235-23-156.ec2.internal.warc.gz"} |
http://czerwinski.it/2017/06/04/simplifying-activitytestrule-syntax-with-reified-type-parameters.html | ## Introduction
In this article, I am using JUnit 4.12, and Espresso 2.2.2 with Espresso Intents.
Since Espresso uses old version of Android Support Annotations (i.e. 23.1.1), it is mandatory to exclude this module when using latest Android Support library:
dependencies {
// […]
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
androidTestCompile('com.android.support.test.espresso:espresso-intents:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
}
## The Problems
When testing Android UI with Espresso, I need to define an ActivityTestRule or an IntentsTestRule (in the examples, I will use the latter). Often, I wish to start the Activity under test with a specific Intent, so the rule must be instantiated by calling a constructor with three arguments:
@RunWith(AndroidJUnit4::class)
class MyTestClass {
@Rule
@JvmField
val mainActivityRule = IntentsTestRule(
MainActivity::class.java, false, false)
}
• The first argument is the class of the activity.
• The second one regards initial touch mode (it is false by default, and usually, I don’t need to change it).
• And the last argument tells whether the activity should be launched automatically before each test method (by default it is set to true).
There are several problems with this snippet of code:
1. When I see the constructor call, I don’t know the meaning of each false argument without looking at the definition of the constructor. In Kotlin, I could use named arguments, e.g. launchActivity = false, but it is not allowed with non-Kotlin functions.
2. I have to provide initialTouchMode, even though I don’t need to change its default value. The second argument is only there to prevent ambiguity, because a constructor:
// Java code:
public ActivityTestRule(Class<T> activityClass, boolean launchActivity)
would have the same arguments as the already existing one:
// Java code:
public ActivityTestRule(Class<T> activityClass, boolean initialTouchMode)
3. The ::class.java after the activity class makes the code obscure.
All these problems could be easily avoided in Kotlin, but the Espresso library is written in Java.
## Using Kotlin Functions
To solve the first and the second issue, I created a simple Kotlin function with default argument values:
fun <T : Activity> intentsTestRule(
activityClass: Class<T>,
initialTouchMode: Boolean = false,
launchActivity: Boolean = true) =
IntentsTestRule(activityClass, initialTouchMode, launchActivity)
As a result, I can name the third argument and omit the second one:
@RunWith(AndroidJUnit4::class)
class MyTestClass {
@Rule
@JvmField
val mainActivityRule = intentsTestRule(
MainActivity::class.java,
launchActivity = false)
}
## Using Reified Type Parameters
To solve the last problem, I needed to harness Kotlin reified type parameters.
After reifying parameter T, I can directly access its type inside the function (note that I can only do that with inline functions). Thus, the first argument is no longer needed:
inline fun <reified T : Activity> intentsTestRule(
initialTouchMode: Boolean = false,
launchActivity: Boolean = true) =
IntentsTestRule(T::class.java, initialTouchMode, launchActivity)
So instead of providing the argument, I can just define the type parameter:
@RunWith(AndroidJUnit4::class)
class MyTestClass {
@Rule
@JvmField
val mainActivityRule = intentsTestRule<MainActivity>(launchActivity = false)
}
A similar function might be defined for ActivityTestRules.
Full implementation with examples is available here. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2920587956905365, "perplexity": 4971.481119674699}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046151638.93/warc/CC-MAIN-20210725045638-20210725075638-00605.warc.gz"} |
https://www.physicsforums.com/threads/wave-motion-and-two-detectors-to-measure-that-motion.977838/ | # Wave motion and two detectors to measure that motion
• Start date
#### tina21
8
2
Homework Statement
Envision a wave of the form y(x,y)=100sin(2*pi*x - 4*pi*t) and locate two detectors to measure the disturbances at points x1 = 2 and x2 = 10. What will be the magnitude of the disturbance at the instant t' when y(x1, t') = 100.
Homework Equations
y(x,y)=100sin(2*pi*x - 4*pi*t)
Solving for t' by substitution I obtained t' = 7/8. Then I substituted x= 10 and t = 7/8 in the given equation. Is that the right way to do it? My answer key says the answer is 100 but I am getting 78.5.
Related Introductory Physics Homework Help News on Phys.org
#### haruspex
Homework Helper
Gold Member
2018 Award
31,709
4,687
Homework Statement: Envision a wave of the form y(x,y)=100sin(2*pi*x - 4*pi*t) and locate two detectors to measure the disturbances at points x1 = 2 and x2 = 10. What will be the magnitude of the disturbance at the instant t' when y(x1, t') = 100.
Homework Equations: y(x,y)=100sin(2*pi*x - 4*pi*t)
Solving for t' by substitution I obtained t' = 7/8. Then I substituted x= 10 and t = 7/8 in the given equation. Is that the right way to do it? My answer key says the answer is 100 but I am getting 78.5.
(The quick way is to consider what happens to 2πx as x changes from 2 to 10.)
#### tina21
8
2
(The quick way is to consider what happens to 2πx as x changes from 2 to 10.)
Hey... I finally got 100 too. Thanks for the help, I looked more carefully and found the error in the calculations
"Wave motion and two detectors to measure that motion"
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• Solo and co-op problem solving | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8626444935798645, "perplexity": 1795.1676173857265}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-43/segments/1570987769323.92/warc/CC-MAIN-20191021093533-20191021121033-00530.warc.gz"} |
http://fempar.org/_pages/05_citing.html | ## Citing
### FEMPAR
The following reference must be cited when using FEMPAR:
• Santiago Badia, Alberto F. Martín and Javier Principe. FEMPAR: An object-oriented parallel finite element framework. Archives of Computational Methods in Engineering 25, 2 (2018), 195–271.
When you use one of the components of the FEMPAR project, you should cite the related scientific publications (if any), to credit the work of the authors.
### FEMPAR-BDDC
• S. Badia, A. F. Martín and J. Principe. A Highly Scalable Parallel Implementation of Balancing Domain Decomposition by Constraints. SIAM Journal on Scientific Computing 36, 2 (2014), C190–C218.
• S. Badia, A. F. Martín and J. Principe. Multilevel Balancing Domain Decomposition at Extreme Scales. SIAM Journal on Scientific Computing, (2016), C22–C52. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8418374061584473, "perplexity": 5656.229434621484}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583509960.34/warc/CC-MAIN-20181016010149-20181016031649-00128.warc.gz"} |
http://mathematica.stackexchange.com/users/9923/martin | # martin
less info
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# 93 Questions
17 Creating sculptural forms using graphics primitives 12 Joining ordered set of points with splines in spiral 12 Animating moving surface of torus 11 Replace elements in list not matching elements of another list at the same position 10 Curve fit based on minimal data
# 1,490 Reputation
+10 Prime power list +5 Animating moving surface of torus +20 Coding While loops +5 Pare down list recursively
2 Plot counting function semi primes 1 Counting function, comparing lists 1 Plot counting function semi primes
# 63 Tags
3 plotting × 31 0 functions × 6 1 list-manipulation × 22 0 graphics × 5 0 manipulate × 13 0 prime-numbers × 5 0 equation-solving × 9 0 locator × 5 0 function-construction × 7 0 dynamic × 4
# 27 Accounts
Mathematics 2,862 rep 931 Mathematica 1,490 rep 316 Puzzling 618 rep 29 MathOverflow 271 rep 10 English Language Learners 136 rep 3 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.1620163768529892, "perplexity": 13725.744267553499}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-49/segments/1416931010402.68/warc/CC-MAIN-20141125155650-00034-ip-10-235-23-156.ec2.internal.warc.gz"} |
http://tex.stackexchange.com/questions/50089/tex4ht-problems-with-footnotes | # tex4ht problems with footnotes
I have a problem with footnotes and tex4ht. The following document has a wrong next pointer in subsection 1 and a bad previous pointer in subsection 3:
\documentclass{book}
\begin{document}
\chapter{chap}
\section{A}
\subsection{aa}
xxx\footnote{A}yyy
\subsection{ab}
text
\subsection{ac}
text
\end{document}
The command I use to generate html files is: htlatex main xhtml,4,next. To reproduce: open main.html and click on 1.1.1 "aa" and then click on "next" to go to 1.1.3 (instead of 1.1.2).
When running the above command a second time, everything works fine. What is the correct way to get a sane document at the first run? That is with a directory that contains only the .tex file and no intermediate files?
-
Just an observation: I don't know about tex4ht, but I just rendered your example to html using plastex and it behaves correctly on the first run. plastex.sourceforge.net – Tim A Mar 30 '12 at 14:55
I took the liberty to open a bug at the tex4ht bug database. I will report here any informations from the devs others than a bug fix. – ppr Oct 25 '13 at 14:25
The short answer is there is no way to get a sane document at the first run.
LaTeX is designed to be run two times (at least) to create a correct document structure. At the first run, LaTeX produces files which will be use the second time to create a correct structure.
This is not a tex4ht issue.
-
by default, tex4ht run latex three times, to get correct links. it seems in this particular case even three runs are not enough, as on second tex4ht run (after 6 latex runs!), links are correct – michal.h21 Oct 24 '13 at 19:39
Indeed ! sorry for the mistake. So, it seems to me it's a bug inside tex4ht. Perhaps tex4ht dev should be interested by this post. – ppr Oct 25 '13 at 14:05 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7250095009803772, "perplexity": 2390.662019083937}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1412037663743.38/warc/CC-MAIN-20140930004103-00465-ip-10-234-18-248.ec2.internal.warc.gz"} |
https://docs.welsim.com/welsim/vm/structural/ | # Structural¶
## Statically inteterminate reaction force analysis VM001¶
An assembly of three cylinder bars is supported at both end surfaces. Forces $$F_{1}$$ and $$F_{2}$$ is applied on the middle of the assembly as shown in Figure [fig:ch5_vm_001_schematic].
The input data about material, geometry, and loads are given in Table [tab:ch5_vm_001_parameters].
Material Properties Geometric Properties Boundary Conditions
Young's Modulus E=2e11 h=10 $$F_{1}$$=2000
Mass Density $$\rho$$=7850 a=3 $$F_{2}$$=1000
Poission's Ratio v=0.3 b=3
The geometries and imposed boundary conditions are shown in Figure [fig:ch5_vm_001_bc].
The result comparison is given in Table [tab:ch5_vm_001_result].
Results Theory WELSIM Error (%)
Z Reaction Force at Top Fixed Support 1800 1810 0.556
Z Reaction Force at Bottom Fixed Support 1200 1202 0.167
This test case project file is located at [vm/VM_WELSIM_001.wsdb].
## Rectangular plate with circular hole subjected to tensile pressure VM002¶
A rectangular plate with a circular hole is fixed along one of the end faces. A tensile pressure load is imposed on another end face as shown in Figure [fig:ch5_vm_002_schematic].
The input data about material, geometry, and loads are given in Table [tab:ch5_vm_002_parameters].
Material Properties Geometric Properties Boundary Conditions
Young's Modulus E=2e11 a=15 Pressure P=1e4
Poission's Ratio v=0.3 b=7.5
c=2.5
d=5
thickness=1
The geometries and imposed boundary conditions are shown in Figure [fig:ch5_vm_002_bc].
The result comparison is given in Table [tab:ch5_vm_002_result].
Results Theory WELSIM Error (%)
Maximum Normal X Stress 3.125e4 3.156e4 0.992
This test case project file is located at %Installation Directory%/vm/VM_WELSIM_002.wsdb. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8641555309295654, "perplexity": 6015.888352157923}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710890.97/warc/CC-MAIN-20221202014312-20221202044312-00432.warc.gz"} |
https://library.fiveable.me/ap-physics-e-m/unit-3/capacitors-in-circuit/study-guide/AegDXsjyTIBK0CZ2XNTx | 📚
All Subjects
>
💡
AP Physics C: E & M
>
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Unit 3
# 3.4 Capacitors in a Circuit 📸
Caroline Koffke
Peter Apps
### AP Physics C: E&M💡
Bookmarked 934 • 25 resources
See Units
After looking back at 20+ years of FRQs, if you see an FRQ on circuits, there's a really good chance it will have a capacitor in it. You've been warned 🙂
## Capacitors in Series & Parallel
Capacitors have their own special equations for determining equivalent resistance in series or parallel, just like resistors.
Image from lumenlearning.com
For a parallel circuit, individual capacitors act as one large capacitor storing a large charge (Q_{total} = Q_1 + Q_2 +Q_3) resulting in a total capacitance that is simply the sum of the individual values.
A series circuit is a bit trickier since the charge is split up along each of the capacitors, but we can derive an expression for this by using the KVL (sum of voltage drops needs to be equal to the battery voltage)
image from lumenlearning.com
In a DC circuit, an initially uncharged capacitor will begin storing charge on its plates, increasing its potential difference until the voltage of the capacitor is equal to the voltage of the battery or other supply source. At this point, there is no current passing through the capacitor and it acts as an open switch or a break in the wire.
For example, in the circuit below, the current initially flows through both branches, but as the voltage of C1 approaches the battery voltage, less and less current passes through R1. When steady state is reached, the circuit will appear to be a series circuit with only R2 in it.
## RC Circuits 🏍️
The RC circuit is a very common type of capacitor where a resistor and capacitor are connected in series with each other. A switch is used to allow the capacitor to charge (position a) or discharge (position b).
Image from web.pa.msu.edu
The cool thing about RC circuits is that the charging and discharging time can be tweaked by changing the values of C and R. Let's derive a few useful equations for this circuit.
• Charging the Capacitor
I know that's a lot of math, but we've just derived an equation for the charge on the capacitor as a function of time! We can also tweak this equation to get derivations for V(t) and I(t) as well.
Graphing these functions shows us the changes in V and I as the capacitor charges. Notice how when the steady-state is reached, the current in the capacitor is basically zero.
Image from electronics-tutorials.ws
• Discharging the Capacitor
We're going to follow the same process we did with generating the charging equations.
Now we can make the same sort of graphs as we did for the charging segment.
Image from electronics-tutorials.ws/
In all these cases notice how $\frac{1}{RC}$ shows up in the exponential. This is called the time constant for the RC circuit and determines the exact time it will take for a capacitor to reach steady-state or to discharge from steady-state back to 0 V. Because of this tuneable feature, RC circuits are frequently used in electronics projects as low-pass or high-pass filters to remove noise from audio signals.
## Practice Questions
1)
Image from collegeboard.org
a) Because R_1 is in parallel with C their voltage drops must be equal at any given time. At t=0, V_C = 0 on the graph, so the voltage on R_2 must be equal to the battery's EMF which is 20V.
b) Similar logic as in part (a). V_c = R_1= 12V at the steady state region and we know that ε = V_1 + V_2\$ so the voltage on R_2 must be 8V
c) In the steady state region no current passes through the capacitor, so we can consider the entire circuit as a series circuit with R_1 and R_2 connected to the battery. Using Ohm's Law we can calculate the current flowing through R_1 which must be the same as the current flowing through R_2. Using that value with our known V_2 from part (b) lets us get the answer.
e) Initial conditions:
image created by author
f) The energy stored in the capacitor will increase. The energy stored depends on the voltage of the capacitor and it's capacitance. V_c and V_{R_1}must be equal to each other because they are connected in parallel. Therefore anything that increases the voltage across R_1will result in more energy stored in the capacitor. By decreasing R_2 (and keeping everything else the same), that allows more current to flow through the circuit (because in the circuit R_{eq} = R_1 + R_2 and resistance is inversely proportional to the total current). According to Ohm's Law, increasing the current in a resistor will increase it's voltage drop (V=IR) so increasing the current makes a larger V_{R_1}which makes a larger V_C which means more energy stored in the capacitor (U_c = 1/2 CV^2)
2)
Image from collegeboard.org
a) With the switch open and all the capacitors acting like open switches as well ("connected for a long time"), there's no current flowing through the ammeter.
b) In a steady state configuration, the charged capacitor must have a voltage equal to the battery's so
c) Same logic as (b), the capacitor must have a voltage of 30V
d) With the switch closed, the steady state circuit can be simplified to a series circuit.
e)The 5μ F capacitor is in parallel with the 40Ω resistor, so their voltages must be the same
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http://www.komal.hu/verseny/feladat.cgi?a=feladat&f=P4277&l=en | Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
# Problem P. 4277. (October 2010)
P. 4277. The wedge shown in the figure can slide without friction on a horizontal tabletop. The mass of the wedge is M and its angle of elevation is =30o. A body of mass m slides down without friction along the wedge, the path of the body makes an angle of =60o with the ground. Find the ratio of the masses, m/M.
(5 pont)
Deadline expired on November 10, 2010.
Sorry, the solution is available only in Hungarian. Google translation
Megoldás.
$\displaystyle \frac{m}{M}=\frac{\tg60^\circ-\tg30^\circ}{\tg30^\circ}=2.$
### Statistics:
113 students sent a solution. 5 points: 61 students. 4 points: 7 students. 3 points: 25 students. 2 points: 9 students. 1 point: 4 students. 0 point: 1 student. Unfair, not evaluated: 6 solutions.
Problems in Physics of KöMaL, October 2010 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9427489638328552, "perplexity": 2288.8436916436517}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257647692.51/warc/CC-MAIN-20180321195830-20180321215830-00796.warc.gz"} |
http://www.dlyj.ac.cn/CN/10.11821/yj2010070006 | • 环境与生态 •
### 闽江口潮汐盐沼湿地土壤碳氮磷的空间变化
1. 湿润亚热带生态－地理过程省部共建教育部重点实验室,福建师范大学亚热带湿地研究中心, 福建师范大学地理科学学院, 福州 350007
• 收稿日期:2009-08-05 修回日期:2010-02-01 出版日期:2010-07-20 发布日期:2010-07-20
• 作者简介:仝川(1964-),男,河北定州人,教授,博士。主要研究方向为生态系统生物地球化学循环。 E-mail:tongch@fjnu.edu.cn
• 基金资助:
国家自然科学基金项目(40671174); 福建省自然科学基金资助项目(2006J0128);福建省自然地理学重点学科项目
### Spatial variations of carbon, nitrogen and phosphorous in tidal salt marsh soils of the Minjiang River estuary
TONG Chuan, JIA Rui-xia, WANG Wei-qi, ZENG Cong-sheng
1. Key Laboratory of Humid Subtropical Eco-geographical Process of Ministry of Education, Research Centre of Wetlands in Subtropical Region, School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
• Received:2009-08-05 Revised:2010-02-01 Online:2010-07-20 Published:2010-07-20
Abstract:
The Minjiang River estuary is a typical tidal estuary in the southeast of China, and the Shanyutan wetland (between 119°34'12″-119°40'40″E and 26°00'36″-26°03'42″N) is the largest estuarine wetland in the Minjiang River estuary area. The climate is relatively warm and wet, with a mean annual temperature of 19.6 ℃ and a mean annual precipitation of 1350 mm. The samples were collected in 18 soil profiles with a depth of 60 cm under three dominated macrophytes (Phragmites australis, Cyperus malacceusis var.bervifolius and Scirpus triqueter) in two different inundated districts far from and near a tide ditch in the middle of the Shanyutan wetland. These soil samples were divided into layers of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm in depth. The soil properties and DOC, TN, TP, NH+4-N and NO-3-N contents and storages were measured. The concentrations of DOC in a depth of 0-10 cm ranged from 13.68 to 93.73 mg kg-1, TN from 0.24 to 1.91 g kg-1, and TP, 0.21-1.34 g kg-1. The DOC, TN and TP concentrations of the soils under P. australis and C. malacceusis were similar, which was higher than DOC and TN concentration under Scirpus triqueter in the area far from and near the tide ditch. The TN and TP contents and storages near the tide ditch were significantly higher than that far from the tide ditch for S.triqueter wetland, however, for the P. australis and C. malacceusis wetlands, the TN and TP contents in the area far from and near the tide ditch were similar. Besides, the DOC, TN and TP contents in soils were significantly correlated with the soil grain size, bulk density and moisture. The soil salinity values had a positive correlation with NH+4-N content, and a negative correlation with NO+3-N. The DOC, TN and TP contents in the Shanyutan tidal wetland were much similar with those in the Yangtze River and Pearl River estuaries, and some coastal regions across the world.
Key words: tidal salt marsh, Phragmites australis, Cyperus malaccensis var.bervifolius, Scirpus triqueter, soil, nutrient element, Minjiang River estuary | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2527288496494293, "perplexity": 20943.334030386784}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178366959.54/warc/CC-MAIN-20210303104028-20210303134028-00291.warc.gz"} |
http://greyenlightenment.com/2017/08/05/bitcoin-at-3000/ | # Bitcoin at $3,000 Bitcoin breaks$3,000 to reach new all-time high
Been long bitcoin since 2013. Glad I ignored the headlines about bubbles. The news is useless, as are most forecasts. For every bubble the media calls correctly, they get 10-20 of them wrong. Bitcoin is like General Electric and PG&E…not only does it fill a specific niche/function, but it’s not going anywhere. Against all odds it succeeded and surpassed everyone’s expectations.
Including Bitcoin Cash, the price is closer to $3400, a 1,600-2,000% gain since mid-2013 (by late 2013, the price got to$800-1000).
As for the media being wrong, they were wrong about:
-The post-2009 bull market, which keeps going on and on. Since 2014 when I launched this blog, I have been telling people to buy. The S&P 500 (including dividends) has gained a whopping 25% since early 2014.
-All of the ‘FANG’ stocks (Google, Facebook, Amazon, and Netflix keep going up…recommended all of them , except Netflix)
-Hillary winning, but the pundits incorrectly predicted that Trump and Brexit would cause a recession (the exact opposite happened, and the S&P 500 is up 12% this year…I predict it has a lot further to go).
-Tesla (the media sure got this one wrong. In 2013, the left-wing NYTs wrote a hit piece about Tesla, when the stock was at $40. Tesla shares have risen from$130 in early 2014 to \$340+ now, and will keep going up despite all the failed predictions of Tesla being a bubble. This blog was right about Tesla here and here.)
-Bay Area real estate prices. Home prices in America most expensive areas refuse to fall despite the media’s insistence that prices are in a bubble.
-Doom & gloom predictions about Ebola, Russia, Emails, Comey, Impeachment—all wrong
-Web 2.0 being a bubble (a broken clock is right twice a day, but the liberal media is never right). Uber is under attack by the media for alleged sexism and and breaking the law. I predict Uber will prevail…the media wants Uber to fail.
-The mass hysteria over the alleged ‘college rape epidemic’, which turned out to be a bunch of hoaxes.
-Hillary Clinton’s health (Hillary Clinton collapsed after attending a 911 memorial and the media tried to cover it up, but failed)
-Hyperinflation & dollar collapse (Treasury bond yields are the lowest they have been in decades)
-A ‘post America era’…this is not really a media prediction, but rather a prediction made by many economists in pundits between 2008-2010. During the depth and recovery of the financial crisis, many pundits predicted a ‘new status quo’ with Europe, not America, being on top. They were wrong. Instead, China and America dominate economically and culturally, with France, Germany, and the UK suffocating under the weight of economic stagnation, incompetent leadership, migrants, and general societal decay.
and many more…
Of course, bitcoin could fall 70% by next year…or it may double again. But given the media’s certitude that THIS IS REALLY THE TOP, and the media’s horrible track record regarding everything, I’m erring towards the latter. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.20307280123233795, "perplexity": 8545.219238263398}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-31/segments/1627046153223.30/warc/CC-MAIN-20210727072531-20210727102531-00045.warc.gz"} |
https://docs.kubos.com/1.20.0/sdk-docs/sdk-rust.html | # Using Rust with the Kubos SDK¶
The Kubos SDK comes with pre-built support for Rust and Cargo. Additionally, it includes tooling to assist with cross-compiling for a target OBC and to build projects which use both Rust and C.
## Cross-compilation¶
The Kubos SDK provides Rust cross-compilation targets for each of the supported OBCs.
The target name varies depending which command is used to compile the project.
OBC cargo build target cargo kubos target Beaglebone Black arm-unknown-linux-gnueabihf kubos-linux-beaglebone-gcc ISIS-OBC armv5te-unknown-linux-gnueabi kubos-linux-isis-gcc Pumpkin MBM2 arm-unknown-linux-gnueabihf kubos-linux-pumpkin-mbm2-gcc
Some Rust crates require that the C compiler be explicitly declared when cross-compiling.
OBC Compiler Path Beaglebone Black /usr/bin/bbb_toolchain/usr/bin/arm-linux-gcc ISIS-OBC /usr/bin/iobc_toolchain/usr/bin/arm-linux-gcc Pumpkin MBM2 /usr/bin/bbb_toolchain/usr/bin/arm-linux-gcc
To simplify development when cross-compiling, use the cargo kubos command to automatically setup the build environment. The cargo kubos command takes a required cargo sub-command (i.e. build, test), and a target. For example, to build a project for the ISIS iOBC:
$cargo kubos -c build -t kubos-linux-isis-gcc Cross compiling can also be done manually by specifying the C compiler path in the CC environment variable like so: $ CC={path} cargo build --target {target}
For example, the equivalent command as above using cargo build:
$CC=/usr/bin/iobc_toolchain/usr/bin/arm-linux-gcc cargo build --target armv5te-unknown-linux-gnueabi Some crates also depend on pkg-config, which requires that an additional environment variable, PKG_CONFIG_ALLOW_CROSS, be set in order to enable cross-compiling: $ PKG_CONFIG_ALLOW_CROSS=1 CC=/usr/bin/iobc_toolchain/usr/bin/arm-linux-gcc cargo build --target armv5te-unknown-linux-gnueabi
## Making Rust Binaries Smaller¶
By default, Rust binaries can be quite large. Check out our Rust optimization tips for suggestions on how to make your compiled Rust projects smaller.
## Transferring to Target¶
Rust binaries can be transferred to the target OBC via a supported file transfer method.
Binaries may be transferred to any location on the target board, however, they should be copied to /home/system/usr/bin if you would like them to be automatically accessible via the system PATH.
## Running on Target¶
Once transferred, the binary can be started with /path/to/binary-name, or by simply specifying the binary name if the file was transferred to a system PATH directory. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.40946078300476074, "perplexity": 17211.362334678946}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-51/segments/1575540527010.70/warc/CC-MAIN-20191210070602-20191210094602-00320.warc.gz"} |
https://repository.uantwerpen.be/link/irua/3071 | Title A study of the decay of tau leptons on the Z resonance at LEPA study of the decay of tau leptons on the Z resonance at LEP Author Abreu, P. Boeck, de, H. Verbeure, F. Faculty/Department Faculty of Sciences. Physics Research group Department of Physics Publication type article Publication 1992Berlin, 1992 Source (journal) Zeitschrift für Physik : C : particles and fields. - Berlin Volume/pages 55(1992), p. 555-568 ISSN 0170-9739 Carrier E Target language English (eng) Affiliation University of Antwerp Handle | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8291026949882507, "perplexity": 9675.692228240474}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988718957.31/warc/CC-MAIN-20161020183838-00126-ip-10-171-6-4.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/heavy-symmetric-top.824975/ | # Heavy Symmetric top
1. Jul 26, 2015
### Zeroxt
Hi, I have another problem:
Obtain from the Euler equations the condition:
These condition for a uniform precession of a heavy symmetric top, imposing that the condition of motion have to be a uniform precession without nutation.
I don't know which precisely is the condition to obtain the equation exposed before.
I hope you can help me.
2. Jul 31, 2015
### Greg Bernhardt
Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
Draft saved Draft deleted
Similar Discussions: Heavy Symmetric top | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.836719274520874, "perplexity": 3170.815487392104}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891814833.62/warc/CC-MAIN-20180223194145-20180223214145-00717.warc.gz"} |
http://mathcentral.uregina.ca/QQ/database/QQ.09.08/h/malcolm1.html | SEARCH HOME
Math Central Quandaries & Queries
Question from Malcolm: I am looking for a formula to find the volume of my pond. I know the average surface diameter and the average bottom arc length.(The arc from one bank through a point in the bottom and on to the surface on the other bank. I am not able to get a good measurement of the depth at this time. Can the volume be figured with the known measurements (the cord and the arc)? Thanks: MS
Malcolm,
You can make an approximation of the volume if you are willing to assume that the surface of the pond is circular and the bottom arcs are also circular. Even with these assumptions the mathematics is not straightforward.
With the circular assumptions the pond can be seen as a slice off a sphere of unknown radius R.
Suppose the diameter of the surface of the pond is d units, r = d/2 and the length of the arc formed by the bottom of the pool is a units. Let the central angle BCA be θ radians. (The expressions are easier in radians than in degrees.) The challenge is to find R for then Pythagoras theorem will allow us to find |CD|, the length of CD and then the depth of the pool, R - |CD|.
The relationship among R, a and θ is that a = R θ. Also from triangle DBC I know that sin(θ/2) = r/R. Putting these two equations together I get
sin(θ/2) = (r/a) θ
You have values for r and a and hence solving this equation for θ will allow you to use a = R θ to find R. Unfortunately there is no way to solve this equation for θ. The best that can be done is to approximate θ. There is some information on solving this equation for θ in our response to an earlier question.
Harley
Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9287634491920471, "perplexity": 434.90539760384104}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500094.26/warc/CC-MAIN-20230204044030-20230204074030-00505.warc.gz"} |
http://mathhelpforum.com/advanced-applied-math/158062-linear-programming-problem.html | 1. Linear Programming Problem
Consider the linear programming problem below:
Minimize g(x,y,z,w) = x - 2y + 3z - 4w
subject to x + 2y + 3z + 4w >= 5;
-y - 2w >= -1
x,y,z,w >= 0
a. Show that the objective function is bounded below on the constraint set.
c. Find all extreme point candidates by considering the six constraints as equations and solving the (6 4) systems of linear equations obtained from these constraints by taking them four at a time.
d. Solve the linear programming problem.
Any help would be greatly appreciated. If you could help me on c and d especially, I'd be much obliged. Too many variables to work with and it's in 4d so I can't graph it out. Thanks.
2. Originally Posted by bambamm
Consider the linear programming problem below:
Minimize g(x,y,z,w) = x - 2y + 3z - 4w
subject to x + 2y + 3z + 4w >= 5;
-y - 2w >= -1
x,y,z,w >= 0
a. Show that the objective function is bounded below on the constraint set.
c. Find all extreme point candidates by considering the six constraints as equations and solving the (6 4) systems of linear equations obtained from these constraints by taking them four at a time.
d. Solve the linear programming problem.
Any help would be greatly appreciated. If you could help me on c and d especially, I'd be much obliged. Too many variables to work with and it's in 4d so I can't graph it out. Thanks.
Put $u=y+2w$ and $v=x+3z$ and minimise $h(u,v)=v-2u$ subject to $1\ge u \ge 0$, $v \ge 0$
CB | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 5, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6383742690086365, "perplexity": 558.0281532435821}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988721392.72/warc/CC-MAIN-20161020183841-00313-ip-10-171-6-4.ec2.internal.warc.gz"} |
https://homework.cpm.org/category/CC/textbook/cca2/chapter/2/lesson/2.2.1/problem/2-90 | ### Home > CCA2 > Chapter 2 > Lesson 2.2.1 > Problem2-90
2-90.
The Gross National Product (GNP) of the United States in 1960 was 1.665 · 1012 dollars. Until 1989 it increased at a rate of 3.17% per year.
Use this information to answer each of the questions below. Homework Help ✎
1. What was the GNP in 1989?
$y=1.665·10^{12}(1.0317)^{29}$
Multiply the GNP in 1960 by 1.0317 twenty-nine times.
The GNP in 1989 is $4.116·10^{12}$ dollars.
2. Write an equation to represent the GNP t years after 1960, assuming that the rate of growth remained constant.
Remember that the GNP increases by 3.17% each year.
$y=1.66(10^{12})(1.0317)^t$
3. Do you think the rate of growth really remains constant? Explain.
If you don’t know or you aren’t sure, try looking it up on the internet. Look for a graph. You could enter GNP USA into a search engine. | {"extraction_info": {"found_math": true, "script_math_tex": 3, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6711490154266357, "perplexity": 2314.0435003242706}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027321160.93/warc/CC-MAIN-20190824152236-20190824174236-00198.warc.gz"} |
http://nbviewer.jupyter.org/github/ipython-books/cookbook-code/blob/master/notebooks/chapter05_hpc/01_numba.ipynb | This is one of the 100 recipes of the IPython Cookbook, the definitive guide to high-performance scientific computing and data science in Python.
# 5.1. Accelerating pure Python code with Numba and Just-In-Time compilation¶
In this example, we first write a pure Python version of a function that generates a Mandelbrot fractal. Then, we use Numba to compile it dynamically to native code.
In [ ]:
import numpy as np
We initialize the simulation and generate the grid in the complex plane.
In [ ]:
size = 200
iterations = 100
## Pure Python version¶
The following function generates the fractal.
In [ ]:
def mandelbrot_python(m, size, iterations):
for i in range(size):
for j in range(size):
c = -2 + 3./size*j + 1j*(1.5-3./size*i)
z = 0
for n in range(iterations):
if np.abs(z) <= 10:
z = z*z + c
m[i, j] = n
else:
break
In [ ]:
m = np.zeros((size, size))
mandelbrot_python(m, size, iterations)
In [ ]:
import matplotlib.pyplot as plt
%matplotlib inline
plt.imshow(np.log(m), cmap=plt.cm.hot,);
plt.xticks([]); plt.yticks([]);
In [ ]:
%%timeit m = np.zeros((size, size))
mandelbrot_python(m, size, iterations)
## Numba version¶
We first import Numba.
In [ ]:
import numba
from numba import jit, complex128
Now, we just add the @jit decorator to the exact same function.
In [ ]:
@jit(locals=dict(c=complex128, z=complex128))
def mandelbrot_numba(m, size, iterations):
for i in range(size):
for j in range(size):
c = -2 + 3./size*j + 1j*(1.5-3./size*i)
z = 0
for n in range(iterations):
if abs(z) <= 10:
z = z*z + c
m[i, j] = n
else:
break
In [ ]:
m = np.zeros((size, size))
mandelbrot_numba(m, size, iterations)
In [ ]:
%%timeit m = np.zeros((size, size))
mandelbrot_numba(m, size, iterations)
The Numba version is 250 times faster than the pure Python version here!
You'll find all the explanations, figures, references, and much more in the book (to be released later this summer).
IPython Cookbook, by Cyrille Rossant, Packt Publishing, 2014 (500 pages). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.38496437668800354, "perplexity": 7548.647215497957}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-13/segments/1490218189092.35/warc/CC-MAIN-20170322212949-00641-ip-10-233-31-227.ec2.internal.warc.gz"} |
https://2022.help.altair.com/2022/hwcfdsolvers/acusolve/topics/acusolve/udfgetelmnquads_acusolve_udf.htm | Return the number of quadrature points of the quadrature rule for the element set.
## Type
User Defined Element
## Parameters
udfHd
The opaque handle (pointer) which was passed to the user function.
## Return Value
Integer nQuads ;
nQuads = udfGetElmNQuads( udfHd ) ; | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.17975908517837524, "perplexity": 12967.691325507854}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-33/segments/1659882572833.78/warc/CC-MAIN-20220817001643-20220817031643-00398.warc.gz"} |
https://dml.cz/handle/10338.dmlcz/126232 | # Article
Full entry | PDF (1.2 MB)
Keywords:
existence; uniqueness; three-point mixed problem; method of lower and upper solutions; lower and upper solutions; resonance; Carathéodory conditions
Summary:
This paper is concerned with existence and uniqueness of solutions of the three-point problem $u'''=f(t,u,u',u''), u(c)=0,u'(a)=u'(b). u''(a)=u''(b), a\leq c\leq b$. The problem is at resonance, in the sense that the associated linear problem has non-trivial solutions. We use the method of lower and upper solutions.
References:
[1] A. R. Aftabizadeh J. Wiener: Existence and uniqueness theorems for third order boundary value problems. Rend. Sem. Mat. Univ. Padova 75 (1986), 130-141. MR 0847662
[2] A. R. Aftabizadeh J. M. Xu C. P. Gupta: Existence and uniqueness theorems for three-point boundary value problems. SIAM J. Math. Anal. 20 (1989), 716-726. DOI 10.1137/0520049 | MR 0990873
[3] R. P. Agarwal: On boundary value problems for y'" = f(x,y,y',y"). Bull. of the Inst. Math. Acad. Sinica 12 (1984), 153-157. MR 0765109 | Zbl 0542.34015
[4] R. P. Agarwal: Existence-uniqueness and iterative methods for third order boundary value problems. J. Comp. Anal. Math., to appear. MR 0883170 | Zbl 0617.34008
[5] J. Andres: On a boundary value problem for x'" = f(t,x,x',x"). Acta UPO, ser. mat. 27 (1988), 289-298. MR 1039896 | Zbl 0712.34032
[6] D. Barr T. Sherman: Existence and uniqueness of solutions of three-point boundary value problems. J. Diff. Eqs. 13 (1973), 197-212. DOI 10.1016/0022-0396(73)90014-4 | MR 0333326
[7] S. A. Bespalova J. A. Klokov: A three-point boundary value problem for a third-order nonlinear ordinary differential equation. Diff. uravn. 12 (1976), 963-970. (In Russian.) MR 0425230
[8] G. Carristi: A three-point boundary value problem for a third order differential equation. Boll. Um. Mat. Ital, C 4 1 (1985), 259-269. MR 0805218
[9] K. M. Das B. S. Lalli: Boundary value problems for y'" = f(x,y,y',y"). J. Math. Anal. Appl. 81 (1981), 300-307. DOI 10.1016/0022-247X(81)90064-0 | MR 0622819
[10] A. Granas R. Guenther J. Lee: Nonlinear Boundary Value Problems for Ordinary Differential Equatins. Polish Acad, of Sciences, 1985. MR 0808227
[11] M. Greguš: Third Order Linear Boundary Value Problems. D. Reidel Publishing Co., 1987. MR 0882545
[12] C. P. Gupta: On a third-order three-point boundary value problem at resonance. Diff. Int. Equations 2 (1989), 1-12. MR 0960009 | Zbl 0722.34014
[13] G. H. Hardy J. E. Littlewood G. Polya: Inequalities. IL, Moscow, 1970. (In Russian.)
[14] J. Henderson: Best interval lengths for boundary value problems for third order Lipschitz equations. SIAM J. Math Anal. 18 (1987), 293-305. DOI 10.1137/0518023 | MR 0876272 | Zbl 0668.34017
[15] S. Hu V. Lakshmikantham: Periodic boundary value problems for integro-differential equations of Volterra type. Nonlinear Anal. 10 (1986), 1203-1208. DOI 10.1016/0362-546X(86)90059-3 | MR 0866253 | Zbl 0622.45007
[16] I. T. Kiguradze: Some Singular Boundary Value Problems for Ordinary Differential Equations. Univ. Press, Tbilisi, 1975. (In Russian.) MR 0499402
[17] E. Lepina A. Lepin: Existence of a solution of the three-point BVP for a nonlinear third-order ordinary differential equation. Latv. M. E. 4 (1986), 247-256. (In Russian.)
[18] E. Lepina A. Lepin: Necessary and sufficient conditions for existence of a solution of a three-point BVP for a nonlinear third order differential equation. Latv. M. E. 8 (1970), 149-154. (In Russian.)
[19] K. N. Murthy D. R. K. S. Rao: On existence and uniqueness of solutions of two and three point boundary value problems. Bull. Calcuta Math. Soc. 73,3 (1981), 164-172. MR 0669619
[20] K. N. Murthy B. D. C. N. Prasad: Three-point boundary value problems, existence and uniqueness. Yokohama Math. J. 29 (1981), 101-105. MR 0649612
[21] K. N. Murthy B. D. C. N. Prasad: Application of Lyapunov theory to three-point boundary value problems. J. Math. Phys. Sci. 19 (1985), 225-234. MR 0863375
[22] L. I. Pospelov: Necessary and sufficient conditions for existence of a solution for some BVPs for the third order nonlinear ordinary differential equation. Latv. M. E. 8 (1970), 205-213. (In Russian.)
[23] D. J. O'Regan: Topological transversality: Applications to third order boundary value problems. SIAM J. Math. Anal. 18 (1987), 630-641. DOI 10.1137/0518048 | MR 0883557 | Zbl 0628.34017
[24] J. Rusnák: A three-point boundary value problem for third order differential equations. Math. Slovaca 33 (1983), 307-320. MR 0713954
[25] N. I. Vasiljev J. A. Klokov: Elements of the Theory of Boundary Value Problems for Ordinary Differential Equations. Zinatne, Riga, 1978. (In Russian.)
Partner of | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8827396631240845, "perplexity": 1771.0571663576159}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875144167.31/warc/CC-MAIN-20200219184416-20200219214416-00400.warc.gz"} |
https://jd2718.org/2011/04/24/rational-expressions-and-functions-unit-worksheets-quizzes/ | I created this year a unit on rational expressions and rational functions for some mixed precalc classes. We will end up with 10-11 days, some of them review.
I am proud of the idea. The execution? It will need much refinement. I liked the third worksheet especially (4 and 5, below) but it needs expansion, clarification, etc. The first two worksheets are probably fine as they are, but they are fairly standard stuff.
The first quiz is gimme. I taught most of these kids to factor 3 years ago, and did it again last year. The second was something new. Only about a quarter attempted the bonuses, but most of those were successful.
I think the third quiz is a wonderful idea, but it needs work. It was very open-ended, so the seniors who are ready to check out probably could come up with something, and the juniors who are scared of AP could write much more. But how to grade it?
1. Reducing, multiplying (worksheet: PC2 Rational Expr Reduce demo )
2. Adding and subtracting, review polynomial division, converting mixed expressions to rational expressions and back (worksheet: PC2 Adding Fractions demo )
3. Partial Fraction Decomposition (handout borrowed from a text the school uses for another course)
4. Graphing functions of the form $f(x) = k + \frac{a}{x-h}$ – the effects of k, a, and h (worksheet PC2 graphing a over x demo ) This worksheet is for day 5 as well
5. More graphing functions of the form $f(x) = k + \frac{a}{x-h}$ and slightly more complicated forms, eg $f(x) = mx + k + \frac{a}{x-h}$. Emphasis on asymptotes. Linear behavior of rational functions. Worksheet from 4 and 5 probably needs to be stretched with more guided examples, and over more than 2 lessons. My kids tolerated it, but it was tough.
6. Handgraphing rational functions Gelfand chapter 5 Functions and Graphs (there is a reason I had the school buy fifty of these suckers. I just didn’t really know the reason back four or so years ago when I pushed it through)
7. More handgraphing Gelfand chapter 7
8. Emphasis on end behavior – I borrowed someone else’s worksheet, didn’t work so well as it really wasn’t written for the purpose I tried to put it to.
9 and 10 will be for review and completion. Also for retaking quizzes that did not show knowledge of the subject. (this is not my general practice, but reflects the reality that these are days D minus 3, 2 and 1 before the AP exams.)
Quizzes:
Quiz 12: Adding or subtracting rational expressions (two challenging questions, factoring required) PC2 Quiz 12 demo Quiz 13: Decomposing a rational expression using the method of partial fractions (one question, plus bonuses) PC2 Quiz 13 demo Quiz 14: Graphing rational expressions. Two questions: read the graph, write the equation, and given the graph and the equation, explain the relationship between the algebra and the form. PC2 Quiz 14 demo | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 3, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2954012453556061, "perplexity": 1775.50045634404}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549423183.57/warc/CC-MAIN-20170720121902-20170720141902-00404.warc.gz"} |
http://opensoundscape.org/en/latest/tutorials/RIBBIT_pulse_rate_demo.html | # RIBBIT Pulse Rate model demonstration¶
RIBBIT (Repeat-Interval Based Bioacoustic Identification Tool) is a tool for detecting vocalizations that have a repeating structure.
This tool is useful for detecting vocalizations of frogs, toads, and other animals that produce vocalizations with a periodic structure. In this notebook, we demonstrate how to select model parameters for the Great Plains Toad, then run the model on data to detect vocalizations.
This work is described in:
RIBBIT is also available as an R package.
This notebook demonstrates how to use the RIBBIT tool implemented in opensoundscape as opensoundscape.ribbit.ribbit()
For help instaling OpenSoundscape, see the documentation
## Import packages¶
[1]:
# suppress warnings
import warnings
warnings.simplefilter('ignore')
#import packages
import numpy as np
from glob import glob
import pandas as pd
from matplotlib import pyplot as plt
import subprocess
#local imports from opensoundscape
from opensoundscape.audio import Audio
from opensoundscape.spectrogram import Spectrogram
from opensoundscape.ribbit import ribbit
# create big visuals
plt.rcParams['figure.figsize']=[15,8]
pd.set_option('display.precision', 2)
You can run the cell below, OR visit this link to downlaod the data (whichever you find easier):
https://pitt.box.com/shared/static/0xclmulc4gy0obewtzbzyfnsczwgr9we.zip
If you download using the link above, first un-zip the folder (double-click on mac or right-click -> extract all on Windows). Then, move the great_plains_toad_dataset folder to the same location on your computer as this notebook. Then you can skip this cell:
[2]:
#download files from box.com to the current directory
subprocess.run(["rm", "great_plains_toad_dataset.tar.gz"]) # Remove the file after its contents are unzipped
% Total % Received % Xferd Average Speed Time Time Time Current
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
100 8 0 8 0 0 6 0 --:--:-- 0:00:01 --:--:-- 0
100 11.6M 100 11.6M 0 0 5308k 0 0:00:02 0:00:02 --:--:-- 18.3M
[2]:
CompletedProcess(args=['rm', 'great_plains_toad_dataset.tar.gz'], returncode=0)
now, you should have a folder in the same location as this notebook called great_plains_toad_dataset
if you had trouble accessing the data, you can try using your own audio files - just put them in a folder called great_plains_toad_dataset in the same location as this notebook, and this notebook will load whatever is in that folder
### Load an audio file and create a spectrogram¶
[3]:
audio_path = np.sort(glob('./great_plains_toad_dataset/*'))[0]
#load the audio file into an OpenSoundscape Audio object
audio = Audio.from_file(audio_path)
#trim the audio to the time from 0-3 seconds for a closer look
audio = audio.trim(0,3)
#create a Spectrogram object
spectrogram = Spectrogram.from_audio(audio)
### Show the Great Plains Toad spectrogram as an image¶
A spectrogram is a visual representation of audio with frequency on the vertical axis, time on the horizontal axis, and intensity represented by the color of the pixels
[4]:
spectrogram.plot()
## Select model parameters¶
RIBBIT requires the user to select a set of parameters that describe the target vocalization. Here is some detailed advice on how to use these parameters.
Signal Band: The signal band is the frequency range where RIBBIT looks for the target species. Based on the spectrogram above, we can see that the Great Plains Toad vocalization has the strongest energy around 2000-2500 Hz, so we will specify signal_band = [2000,2500]. It is best to pick a narrow signal band if possible, so that the model focuses on a specific part of the spectrogram and has less potential to include erronious sounds.
Noise Bands: Optionally, users can specify other frequency ranges called noise bands. Sounds in the noise_bands are subtracted from the signal_band. Noise bands help the model filter out erronious sounds from the recordings, which could include confusion species, background noise, and popping/clicking of the microphone due to rain, wind, or digital errors. It’s usually good to include one noise band for very low frequencies – this specifically eliminates popping and clicking from being registered as a vocalization. It’s also good to specify noise bands that target confusion species. Another approach is to specify two narrow noise_bands that are directly above and below the signal_band.
Pulse Rate Range: This parameters specifies the minimum and maximum pulse rate (the number of pulses per second, also known as pulse repetition rate) RIBBIT should look for to find the focal species. Looking at the spectrogram above, we can see that the pulse rate of this Great Plains Toad vocalization is about 15 pulses per second. By looking at other vocalizations in different environmental conditions, we notice that the pulse rate can be as slow as 10 pulses per second or as fast as 20. So, we choose pulse_rate_range = [10, 20] meaning that RIBBIT should look for pulses no slower than 10 pulses per second and no faster than 20 pulses per second.
Clip Duration: This parameter tells the algorithm how many seconds of audio to analyze at one time. Generally, you should choose a clip_duration that is ~2x longer than the target species vocalization, or a little bit longer. For very slowly pulsing vocalizations, choose a longer window so that at least 5 pulses can occur in one window (0.5 pulses per second -> 10 second window). Typical values for clip_duration are 0.3 to 10 seconds. Here, because the The Great Plains Toad has a vocalization that continues on for many seconds (or minutes!), we chose a 2-second window which will include plenty of pulses.
• we can also set clip_overlap if we want overlapping clips. For instance, a clip_duration of 2 with clip_overlap of 1 results in 50% overlap of each consecutive clip. This can help avoid sounds being split up across two clips, and therefore not being detected.
• final_clip determines what should be done when there is less than clip_duration audio remaining at the end of an audio file. We’ll just use final_clip=None to discard any remaining audio that doesn’t make a complete clip.
Plot: We can choose to show the power spectrum of pulse repetition rate for each window by setting plot=True. The default is not to show these plots (plot=False).
[5]:
# minimum and maximum rate of pulsing (pulses per second) to search for
pulse_rate_range = [8,15]
# look for a vocalization in the range of 1000-2000 Hz
signal_band = [1800,2400]
# subtract the amplitude signal from these frequency ranges
noise_bands = [ [0,1000], [3000,3200] ]
#divides the signal into segments this many seconds long, analyzes each independently
clip_duration = 2 #seconds
clip_overlap = 0 #seconds
#if True, it will show the power spectrum plot for each audio segment
show_plots = True
## Search for pulsing vocalizations with ribbit()¶
This function takes the parameters we chose above as arguments, performs the analysis, and returns two arrays: - scores: the pulse rate score for each window - times: the start time in seconds of each window
The scores output by the function may be very low or very high. They do not represent a “confidence” or “probability” from 0 to 1. Instead, the relative values of scores on a set of files should be considered: when RIBBIT detects the target species, the scores will be significantly higher than when the species is not detected.
The file gpt0.wav has a Great Plains Toad vocalizing only at the beginning. Let’s analyze the file with RIBBIT and look at the scores versus time.
[6]:
#get the audio file path
#make the spectrogram
spec = Spectrogram.from_audio(audio.from_file(audio_path))
#run RIBBIT
score_df = ribbit(
spec,
pulse_rate_range=pulse_rate_range,
signal_band=signal_band,
clip_duration=clip_duration,
noise_bands=noise_bands,
plot=False
)
#show the spectrogram
print('spectrogram of 10 second file with Great Plains Toad at the beginning')
spec.plot()
# plot the score vs time of each window
plt.scatter(score_df['start_time'],score_df['score'])
plt.xlabel('window start time (sec)')
plt.ylabel('RIBBIT score')
plt.title('RIBBIT scores for 10 second file with Great Plains Toad at the beginning')
spectrogram of 10 second file with Great Plains Toad at the beginning
[6]:
Text(0.5, 1.0, 'RIBBIT scores for 10 second file with Great Plains Toad at the beginning')
as we hoped, RIBBIT outputs a high score during the vocalization (the window from 0-2 seconds) and a low score when the frog is not vocalizing
## Analyzing a set of files¶
[7]:
# set up a dataframe for storing files' scores and labels
# label is 1 if the file contains a Great Plains Toad vocalization, and 0 if it does not
df['label'] = [1 if 'gpt' in f else 0 for f in df.index]
# calculate RIBBIT scores
for path in df.index:
#make the spectrogram
spec = Spectrogram.from_audio(audio.from_file(path))
#run RIBBIT
score_df = ribbit(
spec,
pulse_rate_range=[8,20],
signal_band=[1900,2400],
clip_duration=clip_duration,
noise_bands=[[0,1500],[2500,3500]],
plot=False)
# use the maximum RIBBIT score from any window as the score for this file
# multiply the score by 10,000 to make it easier to read
df.at[path,'score'] = max(score_df['score']) * 10000
print("Files sorted by score, from highest to lowest:")
df.sort_values(by='score',ascending=False)
Files sorted by score, from highest to lowest:
[7]:
score label
So, how good is RIBBIT at finding the Great Plains Toad?
We can see that the scores for all of the files with Great Plains Toad (gpt) score above 10 except gpt4.wav (which contains only a very quiet and distant vocalization). All files that do not contain the Great Plains Toad score less than 3.5. So, RIBBIT is doing a good job separating Great Plains Toads vocalizations from other sounds!
Notably, noisy files like pops1.wav score low even though they have lots of periodic energy - our noise_bands sucessfully rejected these files. Without using noise_bands, files like these would receive very high scores. Also, some birds in “negatives” files that have periodic calls around the same pulse rate as the Great Plains Toad received low scores. This is also a result of choosing a tight signal_band and strategic noise_bands. You can try adjusting or eliminating these bands to see their effect on the audio.
(HINT: eliminating the noise_bands will result in high scores for the “pops” files)
## Run RIBBIT on multiple species simultaneously¶
If you want to search for multiple species, its best to combine the analysis into one function - that way you only have to load each audio file (and make it’s spectrogram) one time, instead of once for each species. (If you have thousands of audio files, this might be a big time saver.)
This code gives a quick exmaple of how you could use a pre-made dataframe (could load it in from a spreadsheet, for instance) of parameters for a set of species to run RIBBIT on all of them.
Note that this example assumes you are using the same spectrogram settings for each species - this might not be the case in practice, if some species require high time-resolution spectrograms and others require high frequency-resolution spectrograms.
[8]:
#we'll create a dataframe here, but you could also load it from a spreadsheet
species_df = pd.DataFrame(columns=['pulse_rate_range','signal_band','clip_duration','noise_bands'])
'pulse_rate_range':[8,20],
'signal_band':[1900,2400],
'clip_duration':2.0,
'noise_bands':[[0,1500],[2500,3500]]
}
species_df.loc['bird_series']={
'pulse_rate_range':[8,11],
'signal_band':[5000,6500],
'clip_duration':2.0,
'noise_bands':[[0,4000]]
}
species_df
[8]:
pulse_rate_range signal_band clip_duration noise_bands
great_plains_toad [8, 20] [1900, 2400] 2.0 [[0, 1500], [2500, 3500]]
bird_series [8, 11] [5000, 6500] 2.0 [[0, 4000]]
now let’s analyze each audio file for each species.
We’ll save the results in a table that has a column for each species.
[9]:
# set up a dataframe for storing files' scores and labels
# calculate RIBBIT scores
for path in df.index:
for species, species_params in species_df.iterrows():
#use RIBBIT for each species in species_df
#make the spectrogram
spec = Spectrogram.from_audio(audio.from_file(path))
#run RIBBIT
score_df = ribbit(
spec,
pulse_rate_range=species_params['pulse_rate_range'],
signal_band=species_params['signal_band'],
clip_duration=species_params['clip_duration'],
noise_bands=species_params['noise_bands'],
plot=False)
# use the maximum RIBBIT score from any window as the score for this file
# multiply the score by 10,000 to make it easier to read
df.at[path,species] = max(score_df['score']) * 10000
print("Files with scores for each species, sorted by 'bird_series' score:")
df.sort_values(by='bird_series',ascending=False)
Files with scores for each species, sorted by 'bird_series' score:
[9]:
looking at the highest scoring file for ‘bird_series’, it has the trilled bird sound at 5-6.5 kHz
[10]:
Spectrogram.from_audio(audio.from_file('./great_plains_toad_dataset/negative5.wav')).plot()
### Warning¶
when loading a dataframe from a file, lists of numbers like [8,20] might be read in as strings (“[8,20]”) rather than a list of numbers. Here’s a handy little piece of code that will load the values in the desired format
[11]:
#let's say we have the species df saved as a csv file
species_df.index.name='species'
species_df.to_csv('species_df.csv')
#define the conversion parameters for each column
import ast
generic = lambda x: ast.literal_eval(x)
conv = {
'pulse_rate_range':generic,
'signal_band':generic,
'noise_bands':generic
}
#now the species_df has numeric values instead of strings
species_df
[11]:
pulse_rate_range signal_band clip_duration noise_bands
species
great_plains_toad [8, 20] [1900, 2400] 2.0 [[0, 1500], [2500, 3500]]
bird_series [8, 11] [5000, 6500] 2.0 [[0, 4000]]
## Detail view of RIBBIT method¶
Now, let’s look at one 10 second file and tell ribbit to plot the power spectral density for each window (plot=True). This way, we can see if peaks are emerging at the expected pulse rates. Since our window_length is 2 seconds, each of these plots represents 2 seconds of audio. The vertical lines on the power spectral density represent the lower and upper pulse_rate_range limits.
In the file gpt0.wav, the Great Plains Toad vocalizes for a couple seconds at the beginning, then stops. We expect to see a peak in the power spectral density at 15 pulses/sec in the first 2 second window, and maybe a bit in the second, but not later in the audio.
[12]:
#create a spectrogram from the file, like above:
# 1. get audio file path
# 2. make audio object and trim (this time 0-10 seconds)
audio = Audio.from_file(audio_path).trim(0,10)
# 3. make spectrogram
spectrogram = Spectrogram.from_audio(audio)
clip_df = ribbit(
spectrogram,
pulse_rate_range=pulse_rate_range,
signal_band=signal_band,
clip_duration=clip_duration,
noise_bands=noise_bands,
plot=show_plots)
window: 0.0 to 2.0 sec
window: 2.0 to 4.0 sec
window: 4.0 to 6.0 sec
window: 6.0 to 8.0 sec
## Time to experiment for yourself¶
Now that you know the basics of how to use RIBBIT, you can try using it on your own data. We recommend spending some time looking at different recordings of your focal species before choosing parameters. Experiment with the noise bands and window length, and get in touch if you have questions!
Sam’s email: sam . lapp [at] pitt.edu
this cell will delete the folder great_plains_toad_dataset. Only run it if you wish delete that folder and the example audio inside it.
[13]:
from pathlib import Path
import shutil | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.26293522119522095, "perplexity": 3712.5497596543833}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030334644.42/warc/CC-MAIN-20220926020051-20220926050051-00375.warc.gz"} |
http://www.mathworks.com/help/comm/ref/comm.pammodulator-class.html?requestedDomain=www.mathworks.com&nocookie=true | # Documentation
### This is machine translation
Translated by
Mouseover text to see original. Click the button below to return to the English verison of the page.
# comm.PAMModulator System object
Package: comm
Modulate using M-ary PAM method
## Description
The `PAMModulator` object modulates using M-ary pulse amplitude modulation. The output is a baseband representation of the modulated signal. The M-ary number parameter, M, represents the number of points in the signal constellation and requires an even integer.
To modulate a signal using M-ary pulse amplitude modulation:
1. Define and set up your PAM modulator object. See Construction.
2. Call `step` to modulate the signal according to the properties of `comm.PAMModulator`. The behavior of `step` is specific to each object in the toolbox.
Note: Starting in R2016b, instead of using the `step` method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, ```y = step(obj,x)``` and `y = obj(x)` perform equivalent operations.
## Construction
`H = comm.PAMModulator` creates a modulator System object, `H`. This object modulates the input signal using the M-ary pulse amplitude modulation (M-PAM) method.
`H = comm.PAMModulator(Name,Value)` creates an M-PAM modulator object, `H`, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (`Name1`,`Value1`,...,`NameN`,`ValueN`).
`H = comm.PAMModulator(M,Name,Value)` creates an M-PAM modulator object, `H`. This object has the `ModulationOrder` property set to `M` and the other specified properties set to the specified values.
## Properties
`ModulationOrder` Number of points in signal constellation Specify the number of points in the signal constellation as a positive, integer scalar value. The default is `4`. When you set the `BitInput` property to `false`, ModulationOrder must be even. When you set the `BitInput` property to `true`, ModulationOrder must be an integer power of two. `BitInput` Assume bit inputs Specify whether the input is in bits or integers. The default is `false`. When you set this property to `true`, the `step` method input requires a column vector of bit values whose length is an integer multiple of log2(`ModulationOrder`). This vector contains bit representations of integers between `0` and `ModulationOrder`–1. When you set this property to `false`, the `step` method input must be a column vector of integer symbol values between `0` and `ModulationOrder`–1. `SymbolMapping` Constellation encoding Specify how the object maps an integer or group of log2(`ModulationOrder`) input bits to the corresponding symbol as one of `Binary` | `Gray`. The default is `Gray`. When you set this property to `Gray`, the object uses a Gray-encoded signal constellation. When you set this property to `Binary`, the input integer m, between $0\le m\le$`ModulationOrder`-1) maps to the complex value 2m– `ModulationOrder` + 1. `NormalizationMethod` Constellation normalization method Specify the method used to normalize the signal constellation as one of `Minimum distance between symbols` | ```Average power``` | `Peak power`. The default is ```Minimum distance between symbols```. `MinimumDistance` Minimum distance between symbols Specify the distance between two nearest constellation points as a positive, real, numeric scalar value. The default is `2`. This property applies when you set the `NormalizationMethod` property to `Minimum distance between symbols`. `AveragePower` Average power of constellation Specify the average power of the symbols in the constellation as a positive, real, numeric scalar value. The default is `1`. This property applies when you set the `NormalizationMethod` property to `Average power`. `PeakPower` Peak power of constellation Specify the maximum power of the symbols in the constellation as a positive, real, numeric scalar value. The default is `1`. This property applies when you set the `NormalizationMethod` property to `Peak power`. `OutputDataType` Data type of output Specify the output data type as one of `double` | `single` | `Custom`. The default is `double`.
## Methods
clone Create PAM modulator object with same property values constellation Calculate or plot ideal signal constellation getNumInputs Number of expected inputs to step method getNumOutputs Number of outputs from step method isLocked Locked status for input attributes and nontunable properties release Allow property value and input characteristics changes step Modulate using M-ary PAM method
## Examples
Modulate data using 16-PAM modulation, and visualize the data in a scatter plot.
``` % Create binary data for 100, 4-bit symbols data = randi([0 1],400,1); % Create a 16-PAM modulator System object with bits as inputs and % Gray-coded signal constellation hModulator = comm.PAMModulator(16,'BitInput',true); % Modulate and plot the data modData = step(hModulator, data); constellation(hModulator)```
## Algorithms
This object implements the algorithm, inputs, and outputs described on the M-PAM Modulator Baseband block reference page. The object properties correspond to the block parameters. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 1, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6600710153579712, "perplexity": 2133.88243126505}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-09/segments/1487501172404.62/warc/CC-MAIN-20170219104612-00368-ip-10-171-10-108.ec2.internal.warc.gz"} |
https://www.intechopen.com/books/electronic-properties-of-carbon-nanotubes/enhanced-control-of-single-walled-carbon-nanotube-properties-using-mpcvd-with-dc-electrical-bias | Open access peer-reviewed chapter
# Enhanced Control of Single-Walled Carbon Nanotube Properties Using MPCVD with DC Electrical Bias
By Matthew Maschmann, Timothy Fisher and Placidus Amama
Submitted: October 17th 2010Reviewed: April 5th 2011Published: July 27th 2011
DOI: 10.5772/16975
## 1. Introduction
The engineering properties of carbon nanotubes (CNTs) allow for an extraordinarily large potential application space including thermal management, integrated circuits, mechanical reinforcement, and medical devices, among others. CNTs are generally characterized by the quantity of concentric graphene shells comprising their cylindrical wall structure. CNTs consisting of a single graphene cylinder are characterized as single-walled CNTs (SWNTs), while multiple concentric graphene cylinders are called multi-walled CNTs (MWNTs). Typical diameters for SWNTs are approximately 1—3 nm, while MWNTs diameters range from approximately 2 nm to greater than 100 nm. The unique atomic arrangement of a SWNT dictates that each atom resides on both the interior and exterior of the structure, with the atomic orientation defined by a chiral vector relating the fully traversed perimeter of the SWNT to the unit vectors of a graphene sheet. Two thirds of SWNT chiralities are electrically semi-conducting, exhibiting an electronic band gap inversely proportional to their diameter, while the remaining third are metallic. Though the transport properties of MWNTs are degraded relative to SWNTs by the wall-to-wall interactions, they may still exceed the properties of traditional macroscale materials such as copper or aluminum. Despite the advantageous properties offered by CNTs, their integration into functional materials and devices in a manner that maximizes their benefit remains a significant technical and engineering challenge. Specific applications may demand a unique blend of characteristics such as diameter, alignment, purity, density, and chirality to maintain proper operation. In situ morphology and orientation control of CNTs during synthesis represents a promising path towards selectivity of these device-specific requirements, especially for applications requiring CNTs with engineered properties to be synthesized directly on a fucntionalized substrate. We examine the role of dc electrical bias during mircrowave plasma-enhanced chemical vapor deposition (MPCVD) synthesis of SWNTs using alignment, spatial density, chirality, and purity as metrics of interest. Further, we demonstrate enhanced thermal and electrial transport properties of MWNTs realized with application of substrate bias during MPCVD synthesis.
## 2. Plasma enhanced Chemical Vapor Deposition
There is a wide range of methods for producing CNTs such as laser ablation, arc discharge, pyrolysis, and chemical vapor deposition (Huczko, 2002; Rakov, 2000). Chemical vapor deposition (CVD) has emerged as the method of choice for producing CNTs because of its simplicity, flexibility and affordability as well as the potential for scalability and the precise control of CNT properties. In a typical CVD growth process, a carbon precursor such as a hydrocarbon gas is heated to 750-900°C in the presence of a suitable catalyst (e.g., Fe, Co, and Ni), and if all the other reaction conditions such as catalyst particle size, nature of the catalyst support, and gas composition are optimized, nucleation and growth of CNTs proceeds. The CVD process is highly unique because CNTs grow from catalyst ‘seeds,’ and several studies have shown that there is an intimate relationship between the catalyst properties and the nanotube properties (Amama, et al., 2005a; Hofmann, et al., 2003). In other words, with proper control of the catalyst properties, it is possible to grow CNTs of controlled properties via CVD (Amama, et al., 2007; Amama, et al., 2010; Crouse, et al., 2008; Maschmann, et al., 2005; Zhu, et al., 2010). As such, an appreciable amount of research is underway to fully understand catalyst evolution during synthesis (Amama, et al., 2010; Amama, et al., 2009; Kim, et al., 2010). The CVD process typically involves either thermally driven gas phase decomposition of a hydrocarbon gas (thermal CVD) or both thermal and plasma decomposition (plasma-enhanced CVD).
MPCVD growth has received significant attention mainly because of the potential for low temperature CNT synthesis required for compatiblity with standard nanofabrication and CMOS processes and the ability to produce highly graphitized, vertically aligned CNTs (Amama, et al., 2006a; Meyyappan, et al., 2003). A distinguishing feature of the MPCVD process is the presence of a highly reactive plasma environment, which enhances the decomposition of the hydrocarbon feedstock during CNT growth. The generation of highly energetic ions by the plasma and their subsequent transport to the growth surface are two critical factors that influence the growth properties (Yen, et al., 2005). Using the wide parameter space of the MPCVD, a key advantage over other CVD processes, low temperature growth (Amama, et al., 2006a; Boskovic, et al., 2002), CNT alignment (Maschmann, et al., 2006d), chiral (Li, et al., 2004) and diameter control (Amama, et al., 2006b) have been demonstrated. In many plasma-enhanced CVD studies, the plasma source used is microwave energy which is characterized by high plasma density with a resonant field that is able to concentrate the plasma, ensuring that significant electron loss to the surrounding does not occur (Yen, et al., 2005). The plasma intensity is controlled by the microwave power while the ion flux directed at the substrate may be controlled by a dc bias voltage applied to the growth substrate. These parameters operate indepdently in MPCVD and are capable of substantially altering the properties of CNTs.
## 3. Effect of DC electrical bias during SWNT synthesis
### 3.1. Negative polarity electrical bias
Strict vertical alignment of CNTs may be of significant advantage for many applications, including electron emitters, mechanical enhancement, and high-density electronics. Although direct synthesis of vertically aligned or vertically oriented SWNT arrays has been commonly reported in the literature (Iwasaki, et al., 2005; Maruyama, et al., 2005; Murakami, et al., 2004; Zhong, et al., 2005), most refer to a general packing of SWNTs of subsequent density that the growth front advances and remains in plane with the originating growth substrate. Closer examination of these arrays clearly reveals that individual CNTs within the array exhibit significant waviness and inconsistent orientation with respect to the substrate. Gravity assisted thermal CVD synthesis has reportedly resulted in freestanding vertical SWNTs by orienting the growth substrate upside down such that the SWNT growth direction corresponds to the direction of the gravitation field during synthesis (Yeh, et al., 2006). The vertical orientation using the gravity assisted technique seems to diminish for growth times greater than 1.5 minutes, as the free tips of sufficiently long SWNTs contact and are retained by growth substrate due to thermal vibrations (Yeh, et al., 2007). Others have designed catalyst systems embedded within a modified porous anodic alumina (PAA) template. SWNTs originating from within isolated vertical pore will follow the pore axis toward its opening, resulting in a vertical orientation (Maschmann, et al., 2006a; Maschmann, et al., 2006b). Though this technique successfully aligns individual SWNTs within the confined vertical pores, the free ends of SWNTs emerging from the pores adhere strongly to the top horizontal PAA surface rather than maintaining vertical alignment. SWNT functionalization within the vertical pore structure has been achieved (Franklin, et al., 2009a; Franklin, et al., 2009b), though the misaligned SWNTs on the top surface of the template may be unattractive for some applications. Assembly of freestanding vertical SWNTs from solution post-synthesis is also achievable through electrophoresis into predefined vertical vias etched in a silicon nitride mask (Goyal, et al., 2008). This technique yields variable SWNT deposition with respect to overall occupancy of pores and the number of SWNTs deposited per occupied pore, and SWNTs requires magnesium nitrate hexahydrate to encourage improved substrate adhesion. Though these techniques successfully generate vertically aligned SWNTs, each requires either substrate manipulation or significant catalyst processing, which may be undesirable or impractical for practical application.
Chiral selectivity, with respect to metallic or semiconducting behaviour, is important for optimal operation of many types of devices. Metallic CNTs are obviously well suited for applications requiring high current carrying capacity, such as electrical interconnects (Close, et al., 2008; Kreupl, et al., 2002); however, they may also be advantageous in devices requiring high sensitivity to small electrical potential changes, such as electro-chemical biological sensors (Claussen, et al., 2009). Field effect transistors utilizing semiconducting SWNT channels have been extensively studied and have been found to exhibit ballistic electronic transport even at room temperature operation (Franklin and Chen, 2010). Application of SWNT transistors in electronics offer obvious dimensional and efficiency advantages, and significant research continues in this area with respect to device processing and characterization. The strong preferential growth of semiconducting (Li, et al., 2004) or metallic (Harutyunyan, et al., 2009) SWNTs to population densities greater than 90% chirality selectivity have been reported in the literature by utilizing remote RF plasma and control of gas composition during annealing, respectively. We demonstrate the preferential selectivity of both vertical alignment and semiconducting chirality through the use of negative polarity substrate bias applied during SWNT synthesis using MPCVD.
To investigate the influence of DC electrical bias on SWNT synthesis, a SEKI AX5200S MPCVD reactor with electrically grounded chamber walls, shown schematically in Fig. 1. A hollow stainless steel rod contacts the bottom surface of an otherwise electrically isolated graphite heater stage and delivers a dc potential via a voltage-controlled current source (Sorensen DCS600-1.7E). A K-type thermocouple embedded in the rod monitored the stage temperature, while the growth substrate surface temperature was measured using a dual wavelength pyrometer (Williamson model 90). The silicon growth substrate rested on a 5.08-cm diameter, 3.30-mm thick molybdenum puck used to concentrate the plasma directly above the sample.
An MgO supported Co catalyst was utilized for each SWNT synthesis. The catalyst particles were prepared by a wet mechanical mixing and combustion synthesis procedure using a solution of molybdenum, cobalt nitrate hexahydrate, and magnesium nitrate to produce bimetallic Mo/Co catalyst particles embedded in a nanoporous MgO support (Maschmann, et al., 2006d; Maschmann, et al., 2006c). The susceptor was first heated to 900º C in 50 sccm of flowing hydrogen at a pressure of 10 Torr. A dc substrate bias between 0 and -250 V was applied gradually to the substrate at a rate of approximately - 25 V/second after ignition of a 200 W microwave plasma. Methane was then introduced at a flow rate of 5 sccm to initiate CNT growth. Each synthesis was 20 minutes in duration. The surface temperature of the substrate recorded by the pyrometer was approximately 770º C and relatively insensitive to the applied bias.
Characterization of the SWNT product was performed using a Hitachi S-4800 field emission scanning electron microscope (SEM) and Senterra micro-Raman spectrometer. Laser excitation wavelengths of 533 and 785 nm were selected for recording Raman spectra, with at least ten locations examined for each sample. SEM characterization was utilized to assess SWNT relative alignment with respect to the growth substrate, SWNT length, density, and diameter estimates of individual SWNTs and SWNT bundles. Multi-excitation wavelength Raman spectra analysis allowed for quantification of SWNT quality, diameter distributions, and relative trends with respect to SWNT chirality.
The application of negative bias strengthens the electric field inherently present in the plasma sheath region immediately above the substrate, thereby accelerating the impingement of positively charged ions, such as H+, towards the substrate. A plasma sheath is established as a result of the large mobility mismatch between ions and free electrons generated within the plasma. The relatively low mass of electrons allows them to acquire a translational speed many times greater than that of the relatively heavy ions and accelerate away from the central concentrated plasma sphere located above the substrate.
The bulk plasma is therefore electron deficient, setting up a net positive charge with respect to chamber walls, and an electric field is generated between the plasma and the surrounding surfaces. The highly anisotropic polarization of CNTs (Benedict, et al., 1995) establishes an interaction force between the CNT and the enhanced electric field near the growth substrate. The magnitude of interaction is of sufficient magnitude to orient SWNTs (Peng, et al., 2003; Ural, et al., 2002; Zhang, et al., 2001) and multi-walled CNTs (Jang, et al., 2003; Merkulov, et al., 2001; Meyyappan, et al., 2003) along electric field lines in situ during CVD synthesis as well as during post-synthesis processing procedures (Kamat, et al., 2004; Yamamoto, et al., 1998).
Negative polarity substrate bias was systematically varied between 0 and -250V in 50V increments (Maschmann, et al., 2006d). Cross-sectional SEM analysis revealed distinct trends with respect to both SWNT spatial density and orientation relative to the growth substrate, as seen in Fig. 2a-f. SWNTs grown in the absence of applied bias or at -50V had a tendency to form large diameter bundles that generally followed the profile of the MgO support particles. No preferential growth perpendicular to the growth substrate was observed. The SWNTs synthesized at -100V and -150V, however, demonstrated a strong tendency to break free of the support particle in favor of a vertical orientation, normal to that of the support particles. SWNTs grown at these bias levels also tended to form bundles, with many longer SWNT bundles formed vertically oriented loops. A decrease in overall spatial density relative to the synthesis preformed without bias may also be discerned. At the greater bias magnitudes of -200V and -250V, a strong preference to vertical alignment is observed, in addition to a marked decrease in SWNT spatial density. Very few SWNTs were observed along the perimeter of the catalyst support particles, as is typically observed when bias is omitted from synthesis. Freestanding SWNTs with lengths of several microns were frequently observed, though the free tips of these SWNTs were often obscured by thermal vibrations.
Raman spectra of the SWNTs synthesized with negative polarity bias revealed another trend not readily observable from SEM observation, likely due to SWNT bundling and the inherent resolution limitations of the SEM. The radial breathing mode (RBM) distributions gradually skewed to lower frequency Raman shifts with increased levels of negative bias. Because SWNT diameter is inversely proportional to RBM frequency (Bachilo, et al., 2002; Rao, et al., 1997), the RBM distributions shift suggests a trend towards larger diameter SWNTs (up to 2.5 nm) as negative bias is increased. Locating the RBM peaks relative to excitation wavelengths on a Kataura plot (not shown) indicates that SWNTs synthesized without bias are a mix of metallic and semiconducting chiralities (Maschmann, et al., 2006d). Magnitudes of negative bias at and above -150V shift the measured RBM frequencies into bands of exclusively semiconducting chiralities. Additionally, a decreasing trend in the G- to D-band ratio is a further indication of a decreased spatial density observed by SEM and is perhaps an indication of an increased occurrence of SWNT wall defects. The Lorentzian lineshape of the G-band obtained from SWNTs under high levels of negative bias further support the RBM trend indicating a high concentration of semi-conducting SWNTs (Brown, et al., 2001; Pimenta, et al., 1998). The predominance of larger diameter SWNTs and corresponding decrease in SWNT density is thought to be a result of enhanced H+ ion bombardment, which is known to preferentially etch small diameter SWNTs (Zhang, et al., 2005). Metallic SWNTs may have also been burned up as a result of transmitting a high current density.
### 3.2. Positive polarity electrical bias
Application of dc bias that is positive with respect to chamber walls is believed to decrease the magnitude of the electric field within the plasma sheath region near the growth substrate. H+ ions, generated in abundance within the plasma, therefore attain a lower translational velocity before encountering the growth substrate. In fact, because the substrate in this configuration is the surface of greatest potential relative to the grounded chamber, the ions are instead more readily attracted toward the chamber walls. The mitigation of potentially harmful H+ ion bombardment on the growth substrate is examined by varying the magnitude of positive polarity dc electrical bias during MPCVD SWNT synthesis, similarly to the methodology described in the previous section.
Substrate bias was varied between 0 and +200V in 50V increments while maintaining otherwise standard synthesis conditions. Bias levels of +250V or greater were attempted, but consistently led to plasma instabilities and were not further examined. Within the bias range of 0 and +100V, only incremental increases in SWNT spatial density were observed. SEM micrographs obtained from samples synthesized within this range of biases, shown in Fig. 4 (a) and (b), reveal SWNT bundles spanning tens of microns in length and tens of nanometers in diameter. No preferential vertical alignment of SWNTs is observed for these samples using cross-sectional SEM imaging (not shown). Larger biases of +150V and +200V resulted in dramatic increases in SWNT density, with a significant population of large-diameter SWNT ropes observed uniformly coating the support particle surfaces. Figures 4 (c-e) show typical SEM micrographs of SWNT products synthesized at +150 and +200V. The diameters of SWNT ropes often exceed 50 nm, with smaller feeder bundles ranging between 10-25 nm. Cross-sectional SEM analysis of these samples (Figure 4e) reveals that a small fraction of isolated SWNTs are freestanding and oriented in the direction normal to the support particle. Within the resolution limitations of the SEM, the vertical SWNTs synthesized at +200V bias appear to be smaller in diameter than the vertical SWNTs synthesized using negative bias (Fig. 3c-f). The hypothesized weakened ion bombardment, even relative to the neutral 0V bias case, may encourage the synthesis of CNTs of all orientations that may otherwise be etched by H+ ions, allowing these SWNTs to escape the bundling effect encountered by SWNTs that follow the profile of the support particles.
Raman spectroscopy yields further insights into the SWNTs produced using positive bias. While negative bias resulted in a shift in RBM peaks towards lower frequencies, the application of positive bias resulted in a shift in RBM peaks towards higher frequencies, as shown in Fig. 5. RBMs in the range of 100 – 200 cm-1 are present for all levels of positive bias for both 785 and 532 nm excitation wavelengths, but RBM frequencies greater than 250 cm-1 emerge at bias levels above +150V. Employing a 785 nm excitation wavelength, a RBM peak at 259 cm-1 emerges at +150V, while a peak at 261 cm-1 is present at +200V. Using a 532 nm excitation wavelength, a RBM peak at 251 cm-1 emerges at +200V. In terms of SWNT diameter distribution, the presence of these RBMs indicates the emergence of SWNTs with diameters less than 1 nm (Bachilo, et al., 2002; Rao, et al., 1997). As mentioned previously, this effect may be attributed to decreased H+ ion bombardment which tends to preferentially etch smaller diameter SWNTs. A mixture of metallic and semiconducting chiralities exist, based on the location of RBM peaks on a Kataura plot (not shown), indicating that no chiral selectivity is attained using positive polarity bias.
Examination of the G-band further indicates a significant difference in composition of SWNTs grown under negative and positive bias. A Breit-Wanger-Fano line shape, appearing as a shoulder on the G-band at approximately 1550 cm-1 in Fig. 5, is indicative of metallic SWNTs (Brown, et al., 2001; Pimenta, et al., 1998) and is absent in G-bands obtained for SWNTs grown using negative bias (Fig. 3). Additionally, the G- to D-band ratios are substantially greater when utilizing positive bias. While application of negative bias attracts and accelerates H+ ions to the growth substrate, thus damaging SWNT walls, the application of positive bias appears to adequately decrease the incoming velocity of H+ ions to the substrate and may protect SWNTs from excessive ion bombardment. Consequently, the ratio of G- to D-band ratio for SWNTs grown using positive applied bias increased from approximately 10 for samples grown without bias to approximately 40 for those grown at +200 V. Such a high ratio indicates a large quantity of high-quality SWNTs with little amorphous carbon.
## 4. Influence of DC electrical bias during MWNT synthesis
The influence of dc bias voltage during MPCVD synthesis of MWNTs from dendrimer-templated Fe2O3 nanoparticles will be discussed with respect to the the resulting thermal and electrial transport properties of MWNT arrays. The DC bias values exmained range from -200 to +200V, in 100V increments using similar experimental techniques discussed in the previous sections. The electrical resistance of the MWNTs were measured by obtaining the slope of I-V characterization of randomly selected individual MWNTs across lithographically defined Au/Ti electrodes. Five individual MWNTs were studied for each level of dc bias. The thermal performance was assessed by utilizing the MWNT arrays as a thermal interface. Thermal resistance of the CNT interface material was determined using a photoacoustic technique (Cola, et al., 2007). The thermal resistance measurement was performed at a single interface pressure of 10 psi. Three MWNT array interfaces from each synthesis bias level were produced and characterized.
Figure 6 exhibits the electrical and thermal resistance values as a function of applied substrate bias during MPCVD synthesis. Similar trends with respect to substrate bias exist among the data sets, suggesting that similar phenomena during synthesis may be affecting both thermal and electrical transport. MWNTs grown under positive dc bias (+200V) demonstrate the lowest resistances, while the highest resistances were observed for MWNTs grown under negative dc bias voltage (-100V). The lowest thermal interface resistance (23.9 mm2/K/W) was observed for MWNT arrays grown under a dc bias voltage of +200 V while MWNT arrays grown at -100 V showed the highest thermal interface resistance (27.1 mm2/K/W). Similarly, the lowest electrial resistance (5.5 kOhms) was attained at +200V, while the greatest electrical resistance (23 kOhms). The electrical resistance data exhibits a nearly linear decrease with respect to applied positive polarity bias, the thermal resistance observed at +100V was statistically equivalent to that observed at 0V bias. It is possible that the defect density present in MWNTs may contribute to the observed variation in electrical resistances as shown previously (Lan, et al., 2007).
The thermal and relectrical resistance trends are consistent with those exhibited by the G- to D-band ratio measured via Raman spectroscopy for the MWNT samples. As seen in Fig. 7, the relative ratio of the well graphitized carbon (G-band) to disordered carbon (D-band) steadily increases as a function of positive polarity dc bias. The ratio maxima occurs at +200V, consistent with the minimal thermal and electrical resistance measurmements. The minima at -100V corresponds to the maximum observed thermal and electrical resistance. The observed behavior of the IG/ID ratio is consistent with the full width at half maximum (FWHM) of the G-band at ~1596 cm-1. We hypothesize that negative dc bias voltage accelerated H+ ions, introducing defects on the CNTs. This effect is most pronounced for MWNTs grown under -100 V. The relatively consistent trend between the measured resistance data and the Raman spectra data gives further evidence of this hypothesis. Biasing the substrate positively, on the other hand, reduces electric field near the substrate, reducing the bombardment of H+ and other positively charged hydrocarbon ions generated in the plasma from the CNTs.
## 5. Conclusion
The parameter space for MPCVD synthesis of CNTs is vast, allowing a user a high level of fidelity with respect to control of CNT structure and morphology. The application of substrate bias independently from plasma power and other growth parameters is a unique and robust feature of MPCVD that enables in situ control of CNT alignment, quality, density, and chirality and extends the potential application space for plasma-grown CNTs. We have demonstrated that both the polarity and magnitude of the applied bias dictate the resulting CNT yield. Negative polarity bias lends itself to vertical orientation and is a means to preferentially synthesize larger diameter semiconducting SWNTs. Conversely, positive polarity bias dramatically increases the SWNT quality and yield while resulting in a mix of metallic and semiconducting chiralities. To the detriment of the technique, however, the quality metrics seem exclusive to a given bias polarity. For example, the synthesis of high density, vertical freestanding SWNTs has, to date, been a challenge through variation of bias alone, and more research is required to fully optimize the capabilities of applied bias during SWNT synthesis. For MWNT synthesis, the alignment capability of negative polarity bias is well established, though the application of positive polarity bias remains relatively unexplored. We observe that positive polarity bias at levels greater than +100V during MPCVD synthesis appears to demonstrate a protective role, partially shielding CNTs from harmful ion bombardment. As a result, MWNTs exhibit enhanced thermal and electrical conductivity. The degree of freedom offered by substrate bias during MPCVD synthesis offers a tremendous extension to traditional CNT synthesis capabilities and potential inroads to myriad applications requiring strict control of SWNT or MWNT properties.
## How to cite and reference
### Cite this chapter Copy to clipboard
Matthew Maschmann, Timothy Fisher and Placidus Amama (July 27th 2011). Enhanced Control of Single-Walled Carbon Nanotube Properties Using MPCVD with DC Electrical Bias, Electronic Properties of Carbon Nanotubes, Jose Mauricio Marulanda, IntechOpen, DOI: 10.5772/16975. Available from:
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https://www.physicsforums.com/threads/simple-differentition.171542/ | # Simple differentition
1. May 24, 2007
### wellY--3
hi,
I understand how to use the limiting chord process to find the gradient of a curve, but how do you do it when they ask for a certain point on the curve. for example
find the gradient using the limiting chord process on the curve y=x^2 +2 at the point (1,3)
If you sub the points into the equation it's no longer y= which you need to be able to use the formula they're wanting
2. Jun 2, 2007
### HallsofIvy
Staff Emeritus
Nothing to do with differential equations! I am moving this to "Calculus and Analysis".
"find the gradient using the limiting chord process on the curve y=x^2 +2 at the point (1,3)."
$$\lim_{h\rightarrow 0}\frac{f(1+h)-f(1)}{h}$$
With f(x)= x2+ 2, what is f(1)? What is f(1+h)?
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https://rfablet.github.io/portfolio/2019-07-01-paper-3 | # Learning Latent ODE-based embeddings
Published in IMT Atlantique, 2019
This study addresses the data-driven identification of latent dynamical representations of partially-observed systems, i.e. dynamical systems for which some components are never observed, with an emphasis on forecasting applications, including long-term asymptotic patterns. Whereas state-of-the-art data-driven approaches rely on delay embeddings and linear decompositions of the underlying operators, we introduce a framework based on the data-driven identification of an augmented state-space model using a neural-network-based representation. For a given training dataset, it amounts to jointly learn an ODE (Ordinary Differential Equation) representation in the latent space and reconstructing latent states. Through numerical experiments, we demonstrate the relevance of the proposed framework w.r.t. state-of-the-art approaches in terms of short-term forecasting performance and long-term behaviour. We further discuss how the proposed framework relates to Koopman operator theory and Takens' embedding theorem. Related paper: Ouala et al. Learning Latent Dynamics for Partially-Observed Chaotic Systems. arXiv 2019. (link) | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.815771222114563, "perplexity": 1207.6249242367742}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-34/segments/1596439741154.98/warc/CC-MAIN-20200815184756-20200815214756-00290.warc.gz"} |
https://geo.libretexts.org/Courses/Mt._San_Jacinto_College/Environmental_Science_101/05%3A_Economics_and_Policy | # 5: Economics and Policy
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5: Economics and Policy is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9426043629646301, "perplexity": 717.4881524653148}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296949958.54/warc/CC-MAIN-20230401094611-20230401124611-00604.warc.gz"} |
https://en.wikipedia.org/wiki/%E2%88%921_(number) | # −1
(Redirected from −1 (number))
← −2 −1 0 →
Cardinal −1, minus one, negative one
Ordinal −1st (negative first)
Arabic ١
Chinese numeral 负一，负弌，负壹
Bengali
Binary (byte)
S&M: 1000000012 2sC: 111111112
Hex (byte)
S&M: 0x10116 2sC: 0xFF16
In mathematics, −1 is the additive inverse of 1, that is, the number that when added to 1 gives the additive identity element, 0. It is the negative integer greater than negative two (−2) and less than 0.
Negative one bears relation to Euler's identity since eπi = −1.
In software development, −1 is a common initial value for integers and is also used to show that a variable contains no useful information.
Negative one has some similar but slightly different properties to positive one.[1]
## Algebraic properties
Multiplying a number by −1 is equivalent to changing the sign on the number. This can be proved using the distributive law and the axiom that 1 is the multiplicative identity: for x real, we have
${\displaystyle x+(-1)\cdot x=1\cdot x+(-1)\cdot x=(1+(-1))\cdot x=0\cdot x=0}$
where we used the fact that any real x times 0 equals 0, implied by cancellation from the equation
${\displaystyle 0\cdot x=(0+0)\cdot x=0\cdot x+0\cdot x\,}$
0, 1, −1, i, and −i in the complex or cartesian plane
In other words,
${\displaystyle x+(-1)\cdot x=0\,}$
so (−1) · x is the arithmetic inverse of x, or −x.
### Square of −1
The square of −1, i.e. −1 multiplied by −1, equals 1. As a consequence, a product of two negative real numbers is positive.
${\displaystyle 0=-1\cdot 0=-1\cdot [1+(-1)]}$
The first equality follows from the above result. The second follows from the definition of −1 as additive inverse of 1: it is precisely that number that when added to 1 gives 0. Now, using the distributive law, we see that
${\displaystyle 0=-1\cdot [1+(-1)]=-1\cdot 1+(-1)\cdot (-1)=-1+(-1)\cdot (-1)}$
The second equality follows from the fact that 1 is a multiplicative identity. But now adding 1 to both sides of this last equation implies
${\displaystyle (-1)\cdot (-1)=1}$
The above arguments hold in any ring, a concept of abstract algebra generalizing integers and real numbers.
### Square roots of −1
The complex number i satisfies x2 = −1, and as such can be considered as a square root of −1. The only other complex number x satisfying the equation x2 = −1 is −i.[2] In the algebra of quaternions, containing the complex plane, the equation x2 = −1 has an infinity of solutions.
## Exponentiation to negative integers
Exponentiation of a non-zero real number can be extended to negative integers. We make the definition that x−1 = 1/x, meaning that we define raising a number to the power −1 to have the same effect as taking its reciprocal. This definition then extended to negative integers preserves the exponential law xaxb = x(a + b) for real numbers a and b.
Exponentiation to negative integers can be extended to invertible elements of a ring, by defining x−1 as the multiplicative inverse of x.
−1 that appears next to functions or matrices does not mean raising them to the power −1 but their inverse functions or inverse matrices. For example, f−1(x) is the inverse of f(x), or sin−1(x) is a notation of arcsine function.
## Inductive dimension
The Inductive dimension of the empty set is defined to be −1.
## Computer representation
Most computer systems represent negative integers using two's complement. In such systems, −1 is represented using a bit pattern of all ones. For example, an 8-bit signed integer using two's complement would represent −1 as the bitstring "11111111", or "FF" in hexadecimal (base 16). If interpreted as an unsigned integer, the same bitstring of n ones represents 2n − 1, the largest possible value that n bits can hold. For example, the 8-bit string "11111111" above represents 28 − 1 = 255.
## References
1. ^ Mathematical analysis and applications By Jayant V. Deshpande, ISBN 1-84265-189-7
2. ^ "Ask Dr. Math". Math Forum. Retrieved 2012-10-14. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 6, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9545300006866455, "perplexity": 866.5173897871725}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-09/segments/1487501173872.97/warc/CC-MAIN-20170219104613-00321-ip-10-171-10-108.ec2.internal.warc.gz"} |
http://mathoverflow.net/questions/38660/higher-dimensional-nodes/38669 | # Higher dimensional nodes
A node on a curve is a singular point that locally looks like the intersection of two lines. I think the precise way to say this is that $p \in X$ is a (closed?) point on a scheme $X$ (of finite type over a field $k$?), then the completion of the local ring at $p$, $\widehat{\mathcal{O}}_{X,p}$ should be isomorphic to $k[[x,y]]/(xy)$ (the completion for the intersection of two lines).
The first question is whether this is correct.
The second question is whether you get the n-dimensional version of a node by requiring the completion of the local ring to look like intersection of $n+1$ coordinate planes: $k[[x_0,x_1,...,x_n]]/(x_0 x_1\cdots x_n)$.
The third question is: what exactly does it mean for such a singularity to be isolated? This is easy to imagine over $\mathbb{C}$ (there is analytic neighborhood containing no other singularity), but how to say this in something like the Zariski topology?
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The definition given in the curve case is correct when $p$ is a $k$-rational point. In general, for a curve over a field, your "formal" description is imposed at a point over $p$ on $X_ {\overline{k}}$. With some hard work, it can be shown that this forces $k(p)$ to be a separable extension of $k$. In section 2 of Ch. III of the book "Etale Cohomology and the Weil Conjecture" by Freitag-Kiehl they give an elegant (albeit somewhat technical) discussion of ordinary double points in all relative dimensions, especially relating the "formal" definition to an etale-local definition. – BCnrd Sep 14 '10 at 10:29
[Edit: Over an algebraically closed field] a node should be an isolated hypersurface singularity whose (projectivized) tangent cone is a nondegenerate quadric. This means that in local coordinates the equation has no linear part, and the quadratic part is nondegenerate.
For a curve your definition is equivalent to this one so it is correct. In higer dimensions it is very different. In fact your hypersurface has a non-isolated singularity (for instance, all points in the coordinate lines are singular).
For the last question, the singular points of an algebraic set (or variety, or scheme) are a Zariski closed subset, which splits in irreducible components. A singular point is isolated if it is one of the irreducible components (and it is not embedded, ie, it does not belong to any other irreducible component, but this has sense only in the scheme-theoretic case).
For the non algebraically closed field case, see BCnrd's comment and reference!
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Since Karl has observed nicely that analogies differ depending on what properties you want to be shared, this choice, the "ordinary double point", or odp, shares with a node the Milnor number being one. This singularity has no deformations except for smoothings. I.e. it cannot be changed locally except by being removed. On the "discriminant locus" parametrizing those hypersurfaces in a family which are singular, the points corresponding to hypersurfaces with an odp are (in good cases) the smooth points of the discriminant. Hence odp's are generic singularities in the sense of deformations. – roy smith Dec 16 '10 at 15:59
For example, one place where nodal curves show up is when doing generic projections of smooth curves in $\mathbb{P}^n$ to $\mathbb{P}^2$ (see Hartshorne, Chapter IV, Section 3). In general, you can take a $d$ dimensional projective variety and generically project it to $\mathbb{P}^{d+1}$. Such generic projections will be something called ''seminormal'' (see a paper by Greco and Traverso), and they will also be Gorenstein (they are hypersurfaces). These conditions are equivalent to being a node in dimension 1. On the other hand, these conditions on a singularity are not equivalent to the singularity being a generic projection in general. Rob Lazarsfeld also discusses generic projection singularities a little bit in his ''Positivity'' book.
Another place that nodal curves show up is in the usual compactifications of moduli spaces of curves. If you look at higher dimensional varieties, then presumably the correct generalization of a node is then something called semi-log canonical singularities''. This is again a distinct notion from these semi-log canonical hypersurfaces, see for example Rob Lazarfeld's book and also the dissertation of Davis Doherty (University of Washington, 2006). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9081957936286926, "perplexity": 293.60564997357}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386164038538/warc/CC-MAIN-20131204133358-00079-ip-10-33-133-15.ec2.internal.warc.gz"} |
https://math.stackexchange.com/questions/222755/is-the-injection-ellp-subset-ellq-continuous-for-pq/222772 | # Is the injection $\ell^p \subset \ell^q$ continuous for $p<q$?
It is easy to show that $\ell^p \subset \ell^q$ when $1 \leq p<q \leq + \infty$, but is the injection continuous?
If so is $\ell^{\infty}$ the direct limit $\lim\limits_{\rightarrow} \ \ell^p$ as topological space?
NB: If some result depends on the set we are working on, I am working on $\mathbb{R}$ or $\mathbb{C}$.
If $x=(x_n) \in \ell^p$ with $\|x\|_p = 1$, then $|x_n| \le 1$ for all $n$, so $|x_n|^q \le |x_n|^p$ for all $n$, and so $\|x\|_q = (\sum |x_n|^q)^{1/q} \le (\sum |x_n|^p)^{1/q} \le 1^{1/q}=1 = \| x\|_p$. Using $x=(1,0,0,\ldots)$, it is easy to see that the operator norm of the embedding of $\ell_p$ into $\ell_q$ is actually equal to $1$.
As to the second question, the sequence $(1,1,1,\ldots) \in \ell^\infty$ is not in the direct limit of the $\ell^p$-spaces, which suggests that the answer is no. In order to show that they are not homeomorphic, you can use the fact that $\ell^\infty$ is not separable, but each $\ell^p$ for $1\le p < \infty$ is, so the direct limit is separable, too. (Just take the image of countable dense sets in $\ell^1, \ell^2, \ell^3, \ldots$ in the direct limit, giving you a countable dense set in the direct limit.)
• I see :) +1. The same argument also yields that $\ell^{\infty}$ is not the inductive limit as Banach space ($\ell^1$-sum modulo usual relations). – commenter Oct 28 '12 at 15:07
• The argument for $\|x\|_q\leq\|x\|_p$ is not sufficient since the norms involve a power of $1/q$ and $1/p$, respectively. A proof can be found here How do you show that $\ell^p\subset \ell^q$ for $p\le q$? – AD. Feb 21 '14 at 6:43
• $\ell^p$ is a Banach space for each $1\leq p\leq \infty$;
• if $x^{(n)}\to x$ in $\ell^p$ then $x^{(n)}_k\to x_k$ for each integer $k$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.987568736076355, "perplexity": 68.0904036369073}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514574039.24/warc/CC-MAIN-20190920134548-20190920160548-00048.warc.gz"} |
https://www.atmos-chem-phys.net/20/7103/2020/ | Journal topic
Atmos. Chem. Phys., 20, 7103–7123, 2020
https://doi.org/10.5194/acp-20-7103-2020
Atmos. Chem. Phys., 20, 7103–7123, 2020
https://doi.org/10.5194/acp-20-7103-2020
Research article 16 Jun 2020
Research article | 16 Jun 2020
# Variability and past long-term changes of brominated very short-lived substances at the tropical tropopause
Variability and past long-term changes of brominated very short-lived substances at the tropical tropopause
Susann Tegtmeier1,a, Elliot Atlas2, Birgit Quack1, Franziska Ziska1, and Kirstin Krüger3 Susann Tegtmeier et al.
• 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
• 2Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
• 3Meteorology and Oceanography Section, Department of Geosciences, University of Oslo, Oslo, Norway
• anow at: Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Canada
Correspondence: Susann Tegtmeier (susann.tegtmeier@usask.ca)
Abstract
Halogenated very short-lived substances (VSLSs), such as bromoform (CHBr3), can be transported to the stratosphere and contribute to the halogen loading and ozone depletion. Given their highly variable emission rates and their short atmospheric lifetimes, the exact amount as well as the spatio-temporal variability of their contribution to the stratospheric halogen loading are still uncertain. We combine observational data sets with Lagrangian atmospheric modelling in order to analyse the spatial and temporal variability of the CHBr3 injection into the stratosphere for the time period 1979–2013. Regional maxima with mixing ratios of up to 0.4–0.5 ppt at 17 km altitude are diagnosed to be over Central America (1) and over the Maritime Continent–west Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The CHBr3 maximum over Central America is caused by the co-occurrence of convectively driven short transport timescales and strong regional sources, which in conjunction drive the seasonality of CHBr3 injection. Model results at a daily resolution reveal isolated, exceptionally high CHBr3 values in this region which are confirmed by aircraft measurements during the ACCENT campaign and do not occur in spatially or temporally averaged model fields. CHBr3 injection over the west Pacific is centred south of the Equator due to strong oceanic sources underneath prescribed by the here-applied bottom-up emission inventory. The globally largest CHBr3 mixing ratios at the cold point level of up to 0.6 ppt are diagnosed to occur over the region of India, Bay of Bengal, and Arabian Sea (3); however, no data from aircraft campaigns are available to confirm this finding. Inter-annual variability of stratospheric CHBr3 injection of 10 %–20 % is to a large part driven by the variability of coupled ocean–atmosphere circulation systems. Long-term changes, on the other hand, correlate with the regional sea surface temperature trends resulting in positive trends of stratospheric CHBr3 injection over the west Pacific and Asian monsoon region and negative trends over the east Pacific. For the tropical mean, these opposite regional trends balance each other out, resulting in a relatively weak positive trend of 0.017±0.012 ppt Br per decade for 1979–2013, corresponding to 3 % Br per decade. The overall contribution of CHBr3 together with CH2Br2 to the stratospheric halogen loading accounts for 4.7 ppt Br, in good agreement with existing studies, with 50 % and 50 % being injected in the form of source and product gases, respectively.
1 Introduction
It has long been recognized that the depletion of stratospheric ozone over the last 30 years is mainly caused by human-made chlorine- and bromine-containing substances, often referred to as ozone-depleting substances (ODSs) (Carpenter et al., 2014). The Montreal Protocol, crafted in 1987 to control the production and consumption of ODSs, has been very successful in reducing the emission of the long-lived halocarbons. As a result, the overall abundance of ODSs in the atmosphere has been decreasing since the beginning of the 21st century, and the stratospheric ozone layer is expected to recover around the middle of the 21st century (Austin and Butchart, 2003; Carpenter et al., 2014; Salawitch et al., 2019).
In contrast to long-lived halocarbons, the so-called very short-lived substances (VSLSs) with chemical lifetimes of less than 6 months (e.g. Ko et al., 2003) are not controlled by the Montreal Protocol and are even suggested to increase in the future (e.g. Pyle et al., 2007; Tegtmeier et al., 2015; Ziska et al., 2017). Brominated VSLSs are primarily of natural origin, emitted by oceanic macroalgae and phytoplankton (e.g. Quack and Wallace, 2003). Over the last years there has been increasing evidence from observational (e.g. Dorf et al., 2008; Sioris et al., 2006; McLinden et al., 2010; Brinckmann et al., 2012) and modelling (e.g. Warwick et al., 2006; Liang et al., 2010; Hossaini et al., 2012b, 2016; Tegtmeier et al., 2012) studies that VSLSs provide a significant contribution to stratospheric total bromine (Bry). Current estimates of this contribution are about 5 (3–7) ppt bromine (Engel et al., 2018; Navarro et al., 2015; Wales et al., 2018). The injection of VSLSs into the stratosphere in the form of source gases (SGs) or inorganic product gases (PGs) depends strongly on the efficiency of troposphere–stratosphere transport versus the degradation of the source gases (through photochemical loss) and product gases (through wet deposition). In particular, the question of heterogeneous release of bromine back to the gas phase, which determines the efficiency of wet deposition as a sink for Bry, is currently under discussion (e.g. Salawitch, 2006; Aschmann et al., 2011; Fernandez et al., 2014; Schmidt et al., 2016). Once brominated VSLSs have reached the stratosphere in the form of SG or PG, they participate in ozone depletion at middle and high latitudes (Braesicke et al., 2013; Yang et al., 2014; Sinnhuber and Meul, 2015). Through their relatively large impact on ozone in the lower stratosphere, they contribute −0.02 W m−2 to global radiative forcing (Hossaini et al., 2015).
The most abundant bromine-containing VSLSs are bromoform (CHBr3) and dibromomethane (CH2Br2) with atmospheric lifetime estimates ranging from 16 (50) d at the ocean surface to 29 (400) d in the tropical tropopause layer (TTL) for CHBr3 (CH2Br2) (Hossaini et al., 2012b). Both gases have potentially important source regions in tropical, subtropical, and shelf waters (e.g. Butler et al., 2007; Quack et al., 2007). The emissions of brominated VSLSs from the ocean into the atmosphere can be derived based on their concentration gradient between water and air, wind speed, sea surface temperature, and salinity (e.g. Nightingale et al., 2000; Quack and Wallace, 2003; Ziska et al., 2013). The magnitude and distribution of brominated VSLS emissions are poorly constrained given the sparse observational database of their oceanic and atmospheric concentrations (Ziska et al., 2013). Current emission inventories have been mostly derived via the top-down approach by adjusting the estimated VSLS emissions in a global atmospheric model to produce agreement of the model simulations with aircraft observations. For CHBr3, the current global top-down emissions range between 426 and 530 Gg Br yr−1 (Liang et al., 2010; Warwick et al., 2006; Ordóñez et al., 2012), while the bottom-up approach based on statistical gap filling of an observational database suggests smaller global fluxes of 164–236 Gg Br yr−1 (Ziska et al., 2013). A recent oceanic modelling study taking into account source and sink processes projects open-ocean emissions of around 72 Gg Br yr−1 in the form of CHBr3, not including the strong coastal sources (Stemmler et al., 2015). Quantitative evaluations of various emission inventories demonstrated that the performance of the individual inventories depends strongly on the region and model applied for the evaluation (Hossaini et al., 2013, 2016).
Stratospheric injection of trace gases with lifetimes of days to weeks is most efficient in regions of strong, high-reaching convective activity such as the west Pacific (e.g. Aschmann et al., 2009; Pisso et al., 2010; Marandino et al., 2013). The Asian monsoon represents another important pathway to the lower stratosphere (e.g. Randel et al., 2010; Tissier and Legras, 2016), entraining mostly South East Asian planetary boundary layer air with the potential to include emissions from the Indian Ocean and Bay of Bengal (Fiehn et al., 2017, 2018b). In both regions, the west Pacific and the Indian Ocean, these effective transport pathways may coincide with strong oceanic emissions (e.g. Ziska et al., 2013), potentially leading to anomalously large injection of brominated VSLSs. While aircraft measurements in the west Pacific have confirmed high concentrations of brominated VSLSs such as CHBr3 (Wales et al., 2018), the role of the Asian monsoon as an entrainment mechanism for VSLS is not clear due to the lack of observations in this region. Given the high variability of VSLS measurements in the TTL (Liang et al., 2010), the overall distribution and temporal short- and long-term changes are not well known. Modelling the VSLS distribution in this region depends on the magnitude and distribution of prescribed oceanic emissions, on the representation of tracer transport in the models, and on related uncertainties in both quantities (Hossaini et al., 2016). Reconciling snapshots of VSLS distributions derived from high-resolution aircraft measurements with lower spatially and temporally smoothed global modelling fields remains a challenge.
Changes in oceanic biogeochemical systems over the last decades most likely lead to changes in the marine VSLS production. However, due to the sparse data coverage and missing process understanding, it is currently not possible to quantify such long-term changes of the oceanic halocarbon production and consequences for the air–sea flux (Ziska et al., 2017). Changes in meteorological and oceanic surface parameters, which also impact the oceanic emission strength, on the other hand, have been quantified. Based on increasing sea surface temperature, salinity, and wind speed, VSLS emissions are projected to increase over the recent past (Ziska et al., 2013) and for future climate projections until 2100 (Tegtmeier et al., 2015; Ziska et al., 2017). At the same time, atmospheric transport of VSLSs is driven by changes of the atmospheric circulation. In particular, changes of tropical, high-reaching convection can be expected to have a large influence on the transport of VSLS from the ocean surface to the TTL (Aschmann et al., 2011; Hossaini et al., 2013). Long-term changes of VSLS injections into the stratosphere are difficult to predict as they are driven by various processes including changes in surface emissions, troposphere–stratosphere transport, and tropospheric chemistry (Pyle et al., 2007; Hossaini et al., 2012a).
In our study, we combine observational data sets derived during upper-TTL aircraft campaigns with Lagrangian model simulations and an observation-based VSLS emission climatology in order to analyse the spatial and temporal variability of VSLS injection into the stratosphere. Model simulations and data sets are introduced in Sect. 2. A detailed picture of the distribution of CHBr3 in the TTL (Sect. 3.1) is derived from Lagrangian transport simulations applied to a bottom-up, observation-based emission inventory. Analyses of the trajectory pathways and comparisons to aircraft observations allow us to evaluate how well we know the hotspots of CHBr3 injection (Sect. 3.2 to 3.4). We will investigate if such hotspots are mainly driven by oceanic or by atmospheric processes by analysing emission patterns and transport pathways derived from the Lagrangian simulations. We present the first estimates of the long-term changes of CHBr3 injection based on changing oceanic emissions and transport processes (Sect. 3.5). Finally, the overall contribution of CH2Br2 and CHBr3 to the stratospheric bromine loading is determined from the model simulations (Sect. 3.6) and compared to existing studies. A summary and discussion of the key results are given in Sect. 4.
2 Data and model
## 2.1 Global emission climatology
The global emission scenario from Ziska et al. (2013) is a bottom-up estimate of oceanic CHBr3, CH2Br2, and CH3I fluxes. Here we focus on the two brominated compounds. Static global surface concentration maps of the two compounds were generated from atmospheric and oceanic surface ship-borne in situ measurements collected within the HalOcAt (Halocarbons in the Ocean and Atmosphere) database project (https://halocat.geomar.de, last access: May 2019). In a first step, the in situ surface measurements were classified based on physical and biogeochemical characteristics of the ocean and atmosphere important for the CH2Br2 and CHBr3 distribution and sources. In a second step, the global 1× 1 grid was filled by extrapolating the in situ measurements within each classified region based on the ordinary least-square and robust-fit regression techniques. The method includes all in situ measurements available through the HalOcAt database at the time, regardless of season and year of the measurement. The resulting concentration maps are taken to represent climatological fields of a 23-year-long time period covering 1979 to 2013. Based on the global concentration maps, the oceanic emissions were calculated with the transfer coefficient parameterization of Nightingale et al. (2000), which was adapted to CHBr3 and CH2Br2 (Quack and Wallace, 2003). While the concentration maps do not provide any temporal variability, the emission parameterization is based on 6-hourly meteorological ERA-Interim data (Dee et al., 2011) allowing for relative emission peaks related to maxima in the horizontal wind fields and sea surface temperature. The emission inventory is available at 6-hourly, daily, and monthly temporal resolution or as a climatology product calculated as a long-term average emission field. Seasonal CHBr3 emission maps averaged over 1979–2013 are shown in the Supplement (Fig. S1).
## 2.2 Aircraft campaigns
We analyse the spatial and temporal variability of CHBr3 in the TTL based on the comparison of Lagrangian transport simulations to data from aircraft campaigns. CHBr3 measurements in the upper TTL are currently available from seven aircraft campaigns. Nearly all of the campaigns took place over Central America, except for the Airborne Tropical TRopopause EXperiment (ATTREX) campaign which was in large part conducted over the Pacific. Detailed information about the aircraft missions including location and time period is presented in Table 1.
Table 1Aircraft campaigns with CHBr3 measurements used in the study.
## 2.3 VSLS transport modelling
We are interested in the direct contribution of CHBr3 and CH2Br2 to the stratospheric halogen loading in the form of source and product gas contributions. Therefore, the atmospheric transport of the two compounds from the oceanic surface into the upper troposphere and TTL is simulated with the FLEXPART Lagrangian particle dispersion model (Version 9.2 beta; Stohl et al., 2005, 2010). The oceanic emissions, based on the air–sea flux data from Ziska et al. (2013), prescribe the amount of CHBr3 and CH2Br2 released in the FLEXPART simulations with each air parcel trajectory. The global air–sea flux, given on a 1× 1 grid, is used here at a monthly mean temporal resolution. For CHBr3, 90 trajectories are released per month from each grid box carrying the gas amount prescribed by the emission scenario. For the longer-lived CH2Br2, 45 trajectories are released per month. Once all brominated SGs and PGs have been removed from a trajectory through chemical decay and wet deposition, the trajectory is automatically terminated, so that the number of all active trajectories stays roughly constant (∼20 million) at all times after the initial spin-up period. The global CHBr3 simulations are run for 35 years from 1979 to 2013 with a spin-up period of 6 months in order to analyse in detail the spatial–temporal variability and long-term changes of stratospheric injection. For the longer-lived CH2Br2, the spatial–temporal variability is known to be much smaller (Hossaini et al., 2010), and runs are carried out for 3 years from 2011 to 2013 with a spin-up period of 18 months.
The transport in FLEXPART is driven by meteorological fields from the ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis model. FLEXPART includes parameterizations for moist convection (Forster et al., 2007) and turbulence in the boundary layer and free troposphere (Stohl and Thomson, 1999), dry deposition, and scavenging (Stohl et al., 2005). The runs are based on the 6-hourly fields of horizontal and vertical wind, temperature, specific humidity, convective precipitation, and large-scale precipitation from the ECMWF reanalysis product ERA-Interim (Dee et al., 2011) given at a horizontal resolution of 1× 1 on 60 model levels. A preprocessor retrieves the meteorological fields from the ECMWF archive, including the vertical wind, which is calculated in hybrid coordinates mass-consistently from spectral data. FLEXPART has been validated based on comparisons with measurement data from three large-scale tracer experiments (Stohl et al., 1998) and with results from intercontinental air pollution transport studies (e.g. Forster et al., 2001; Stohl and Trickl, 1999). Previous FLEXPART studies using a similar model setup as applied here have shown a very good agreement between diagnosed and observed VSLS profiles (e.g. Tegtmeier et al., 2013; Fuhlbrügge et al., 2016).
FLEXPART includes the simulation of chemical decay by reducing the tracer mass carried by each air parcel corresponding to its prescribed chemical lifetime. We set the atmospheric lifetime of CHBr3 (CH2Br2) to an altitude-dependent lifetime profile ranging from 16 (50) d at the ocean surface to 29 (400) d in the TTL (Hossaini et al., 2012b). The lifetime profiles were derived from simulations of the chemical tropospheric loss processes of CHBr3 and CH2Br2 with the chemical transport model TOMCAT (Chipperfield, 2006). Previously, profiles from TOMCAT have been shown to agree well with aircraft observations in the tropical troposphere (Hossaini et al., 2012b).
The bromine resulting from the photochemical loss of CHBr3 and CH2Br2, based on prescribed loss terms, contributes to the inorganic product gases. In the FLEXPART simulations, these product gases are grouped together as Bry and transported together with the VSLS source gases along the trajectory. Thus, we assume instantaneous conversion between organic intermediate product gases and Bry, which has been shown to be reasonable by Hossaini et al. (2010). Bry can be removed effectively from the troposphere through wet scavenging by rain or ice (Yang et al., 2005). FLEXPART includes in-cloud as well as below-cloud scavenging, which is initiated if the relative humidity as calculated from meteorological input data exceeds 80 % and the precipitation rate is larger than zero. In FLEXPART, the cloud scavenging ratio is used to model washout of soluble species. The ratio is calculated within FLEXPART with the help of the effective Henry's law coefficient, Heff, which describes the physical solubility of a species as well as the effects of dissociation. Among the members of the Bry family, HBr and HOBr can be washed out while the remaining species Br, BrO, BrONO2, and Br2 are not soluble. HBr has a very large acidity dissociation constant resulting in an effective Henry's law coefficient of 7.1×1013 M atm−1 for T=298 K and pH = 5 (Yang et al., 2005). While HBr provides the main pathway for wet removal of inorganic Bry, HOBr is also soluble due to physical solubility, but not due to dissociation (Frenzel et al., 1998) with ${H}_{\mathrm{eff}}=\mathrm{6.1}×{\mathrm{10}}^{\mathrm{3}}$ M atm−1. In order to determine which fractions of Bry are in the form of HBr and HOBr, we apply the Bry partitioning derived from p-TOMCAT simulations (Yang et al., 2010).
Based on analysed wind fields together with complex chemical schemes, p-TOMCAT simulates the tracer distribution in the troposphere and lower stratosphere including gaseous phase bromine chemistry. The three-dimensional Bry field from p-TOMCAT and its partitioning into HOBr, HBr, Br, BrO, BrONO2, and Br2 are given at a time step of 30 min. As the partitioning of the Bry field varies strongly with location and time, we apply it in a first step to every air parcel according to its location each time before the wet deposition is initiated. In a second step, wet deposition is calculated individually for each inorganic bromine species based on its solubility specified by the effective Henry's law coefficient, as described above. Once wet deposition is initiated the Bry fraction determined to be washed out is removed completely.
Dissolved inorganic bromine can be released back to the gas phase by heterogeneous chemical reactions (Abbatt, 2003; Salawitch, 2006), extending the tropospheric lifetime of Bry by altering the efficiency of wet deposition (von Glasow et al., 2004). The heterogeneous reactions on aerosols which reactivate bromine radicals from the reservoir species (Yang et al., 2005, 2010) are included in the chemical scheme of p-TOMCAT. This release of bromine back to the gas phase results in elevated BrO∕Bry ratios (Yang et al., 2010), and thus a lower fraction of Bry is subject to wet deposition compared to a scenario without the heterogeneous chemical reactions. As we use the p-TOMCAT Bry partitioning for our trajectory simulations, these aerosol effects have indirectly been taken into account when simulating the wet removal of Bry. Uncertainties in the modelled wet deposition arise from the parameterization of solubility via the effective Henry's law coefficient and from uncertainties in the Bry partitioning caused by errors in the aerosol loading and in the mechanism used for heterogeneous reactions. Clouds and aerosols within p-TOMCAT are not matched with those in FLEXPART, which might lead to an additional error source.
For the analysis of the spatial and temporal variability of CHBr3 in the TTL from FLEXPART simulations and aircraft observations in Sect. 3.1 to 3.5, we use mixing ratios at 17 km (approximate cold point) and mixing ratios averaged over 16–18 km (upper part of the TTL). In order to derive the amount of VSLS source and product gases entrained into the stratosphere from the model simulations in Sect. 3.6, we explicitly calculate the cold point along each trajectory based on the ERA-Interim meteorological fields as stratospheric entrainment point. The derived estimates of stratospheric VSLS entrainment depend on the meteorological input data sets and on various FLEXPART model parameters, such as the convective parameterization. The accurate representation of convection has been validated with tracer experiments and 222Rn measurements (Forster et al., 2007). The application of transport timescales based on vertical heating rates instead of vertical wind fields in the TTL between 15 and 17 km results in only minor differences of VSLS entrainment (Tegtmeier et al., 2012).
3 Results
## 3.1CHBr3 in the TTL
Figure 1a shows the long-term annual mean CHBr3 distribution at 17 km as derived from the Lagrangian transport calculations driven by monthly mean oceanic emission fields for the time period 1979–2013. Clearly, CHBr3 has a very pronounced spatial variability due to its short lifetime. The largest CHBr3 mixing ratios of up to 0.4 to 0.5 ppt can be found over (1) Central America, (2) the Maritime Continent and the tropical west Pacific, and (3) the tropical Indian Ocean (all regions are highlighted by black squares in Fig. 1a labelled from 1 to 3). Other tropical regions with only little convective uplift show smaller mixing ratios, mostly between 0.1 and 0.2 ppt.
Figure 1Modelled annual mean distribution of CHBr3 at 17 km for 1979–2013 (a) and the inter-monthly (b) and inter-annual (c) variations given by the standard deviations over all monthly, multi-annual mean, and annual mean values, respectively. Rectangles stand for regions of maximum CHBr3 mixing ratios and will be discussed in detail in Sect. 3.2 to 3.4.
Figure 2Modelled distribution of CHBr3 at 17 km for JJA, 1979–2013 (a), transit time of air masses from the ocean surface to the TTL (b), oceanic source regions for CHBr3 (c), and measurements of oceanic CHBr3 concentrations from the HalOcAt database used for Ziska et al. (2013) (d). The oceanic source regions in (c) are colour coded according to their contribution (% per 1× 1 grid box) to the amount of CHBr3 at 17 km in the black box over Central America (highlighted in a and b).
Entrainment of CHBr3 into the stratosphere also shows a large temporal variability. The seasonal variability is given here by the standard deviation over all monthly, multi-annual mean values (Fig. 1b). The by far most pronounced variability is found in the region of the Asian monsoon anticyclone, which is characterized by a strong seasonality of vertical transport processes (Randel et al., 2010). Furthermore, the distribution of CHBr3 at the cold point over Central America shows some seasonal variations, however, of smaller magnitude. The Maritime Continent and tropical west Pacific have only a very weak seasonal cycle. Overall, the seasonal variations are more pronounced in the Northern Hemisphere (NH) tropics and quite low in the Southern Hemisphere (SH) tropics. Seasonal CHBr3 entrainment averaged over 1979–2013 is shown in the Supplement (Fig. S2).
Inter-annual variations are given in the form of the standard deviation over all annual mean CHBr3 mixing ratios at 17 km (Fig. 1c). In comparison to the seasonal variability, the inter-annual variability is relatively small in the NH tropics but is of similar magnitude in the SH tropics. Drivers of the seasonal and inter-annual variability will be discussed in the following sections. We will analyse the three regions with maximum CHBr3 entrainment identified above and investigate the relative importance of emissions and transport processes for the overall distribution and seasonality of stratospheric injection.
## 3.2 Central America
CHBr3 in the TTL, on its way from the ocean surface to the stratosphere, shows a pronounced maximum over Central America between 0–20 N and 60–110 W (black square in Figs. 1a and 2a). This maximum is present all year, but most pronounced during NH summer and autumn. In the following, we will use the simulations for June–July–August to address the question of whether this maximum arises from very strong oceanic sources or from strong convective transport. The impact of transport on the CHBr3 distribution in the upper TTL is analysed by estimating the time air masses need from the ocean surface to 17 km based on the FLEXPART model simulations. The transport time of each trajectory is assigned to the location where the trajectory reaches 17 km. A map of the “ocean surface–17 km transit times” is derived by averaging over all trajectories on a 1× 1 grid. The tropical annual mean transit time is around 55 d with variations between 45 and 70 d (not shown here). Transit times over Central America for the June–July–August season are relatively short with values around 48 d (Fig. 2b). However, the transit times over the east and central Pacific are similar or even shorter, suggesting that the vertical transport in this region is as efficient as over Central America. Therefore, atmospheric transport timescales alone cannot explain the CHBr3 maximum over Central America.
Figure 3Modelled distribution of CHBr3 in the upper TTL from FLEXPART (background colouring) in comparison with aircraft campaign measurements (coloured symbols with white edges). In (a), (b), and (c), all individual measurements from the respective campaign and the model mean over the same time period are shown. Only in (d) is one individual flight (ACCENT flight from 20 September 1999) shown together with FLEXPART daily mean values to illustrate the large spatial variability including maximum values ≥2 ppt.
In addition to the transit time, we analyse the oceanic sources of CHBr3 over Central America. Each trajectory reaching the TTL over Central America (black square in Fig. 2a) contributes a certain amount of CHBr3 to this local maximum by carrying its prescribed oceanic emission (Ziska et al., 2013) from the surface to the cold point. The relative contribution (%) of each trajectory is assigned to its oceanic release point, thus quantifying which ocean region contributes the largest amounts of CHBr3 to the local maximum in the TTL. The relative contributions averaged over 1× 1 grid cells (Fig. 2c) demonstrate that the largest sources stem from the Gulf of Mexico, the Caribbean Sea, and the western North Atlantic. Some smaller contributions come from the west coast of North Africa and from the equatorial Atlantic. The co-occurrence of strong sources and the relatively short transport timescales over the Caribbean Sea and Central America mainly cause the local CHBr3 maximum in the Central American TTL. While transport timescales are also short (or even shorter) in the eastern Pacific, oceanic emissions are very small there, and vice versa more pronounced emissions over the Atlantic and along the coast of Africa do not cause a global maximum due to longer transport timescales.
The regional oceanic measurements in surface water, which were used to derive the extrapolated concentration and emission maps (Ziska et al., 2013), are given in Fig. 2d. The available data show, in particular, high oceanic CHBr3 concentrations at the Florida coastline and in the eastern part of the Gulf of Mexico. A reasonable number of measurements with a distinctive distribution are available in this region, supporting the extrapolated climatological source distribution, which leads to the CHBr3 maximum in the TTL over Central America discussed above.
Over the last decades, the atmospheric distribution of CHBr3 over Central America has been investigated by a number of different aircraft campaigns. We will use available upper air measurements to evaluate the distribution and variability of the model-derived CHBr3 fields. Details of the aircraft campaigns are given in Table 1. We show the spatial CHBr3 distribution in the TTL as observed during three different campaigns in comparison to the model simulations (Fig. 3). The altitude ranges in the upper TTL have been chosen so that each comparison includes a maximum number of observational data. While for the aircraft campaigns individual measurements are shown at the measurement locations, the model fields are averaged over the duration of the respective campaign. This method allows us to evaluate the spatial distribution of measured and modelled CHBr3 fields, but it has the disadvantage of comparing in situ data with temporally averaged fields. We will discuss how this can impact the comparison and how the temporal variability can be taken into account.
For the Pre-AVE campaign during NH winter, CHBr3 in the upper TTL (16–18 km) shows a latitudinal gradient with small values of 0–0.1 ppt in the northern subtropics and with higher values of up to 0.3–0.4 ppt around the Equator. The same gradient is also evident from the model simulation, resulting in an overall good agreement. Similarly, for the AVE campaign during NH summer, both the observations and the model results show a latitudinal gradient with increasing values towards lower latitudes. However, here the overall agreement is poor, since the model results are on average 50 % larger than the measurements.
Finally, for the ACCENT campaign during NH autumn, the observations reveal extremely high CHBr3 (up to 2 ppt) between 30 and 20 N. While CHBr3 is decreasing north and south of this area towards the range of 0.5–1 ppt, the values are still very high when compared to other campaigns over Central America. FLEXPART results, averaged over the time period of the ACCENT campaign (September 1999), show the largest monthly mean CHBr3 values of around 0.7 ppt, which are substantially smaller than the observations of 2 ppt. However, the model results look quite different and show large spatial inhomogeneities when evaluated at a daily mean resolution. Maximum model values are much higher for the daily resolution and in some locations, very close to the flight track, of similar size as the observations (around 2 ppt). The spotty features in the model simulations are a result of the high oceanic sources directly underneath interacting with localized convective transport. The latter brings localized air masses with very high CHBr3 mixing ratios from the boundary layer into the 15–17 km layer. The differences between monthly and daily mean model values make clear that CHBr3 model–measurement comparisons may be obscured by the high variability of the field. Given this high variability and the existing uncertainties in the diagnosed oceanic sources and atmospheric transport processes, it is very difficult for a model to predict the correct in situ values at a given time and measurement position. Nevertheless, if the large-scale emissions and transport fields are correct, spatial and temporal averaging of the model results can be expected to produce realistic mean VSLS fields and to improve the agreement with observations. Only in cases where rare events have been observed will averaging the CHBr3 fields not necessarily lead to a better agreement with the measurements, as demonstrated above for the ACCENT campaign. Consequently, it is important to include estimates of the spatial and temporal variability of the CHBr3 field in all comparisons.
Figure 4Seasonal cycle of CHBr3 in the upper TTL (15–17 km) over Central America from FLEXPART simulations (solid lines) averaged over 110–80 W and 5 S–15 N (green), 15–25 N (red), and 25–35 N (black) for 1999–2013. In addition, aircraft measurements (stars) and coincident FLEXPART values (filled circles) are shown averaged over the same latitude bins and corresponding to the respective year of the campaign. Temporal and spatial variability of average measurements (solid vertical lines) and coincident model values (dashed vertical lines) is shown in the form of the 1-sigma standard deviation over all values in the respective bin.
A summary of the CHBr3 model results compared to aircraft campaigns in the Central American region, taking into account spatial and temporal variability, is provided in Fig. 4. Here, we compare measurements averaged over different parts of the flight tracks (split by latitude) with FLEXPART coincidences averaged over the same latitudinal bins. The variability of the CHBr3 distribution from observations and coincident model values is given by the standard deviation over all values in the respective region. In addition, the FLEXPART seasonal cycle averaged over 110–80 W, the main longitudinal extent of the aircraft campaigns, and the entire campaign time period (1999–2013), is shown. The comparison of the three campaigns during NH winter shows an overall good agreement. For some latitude bins, the modelled mean values agree very well with the observations (e.g. Pre-AVE for 5 S–15 N); for other regions, differences of the mean values can be up to 50 %–100 %. However, all observational mean values are within the standard deviations of the modelled field, indicating good agreement of model and measurements.
Figure 5Seasonal cycles of CHBr3 at 17 km over Central America (black square in Fig. 2a) from FLEXPART simulations (red line), oceanic CHBr3 emissions averaged over the respective source region (black line), and the “surface–17 km” mean transit time (blue line) are shown.
Figure 6Modelled distribution of CHBr3 at 17 km, annual mean 1979–2013 (a), transit time of air masses from the ocean surface to the TTL (b), and oceanic source regions for CHBr3 at 17 km (c). Oceanic source regions are colour coded according to their contribution (% per 1× 1 grid box) to the amount of CHBr3 at 17 km in the black box over the west Pacific (highlighted in a and b).
For the campaigns during NH summer, mean differences are in general larger than during NH winter. At the same time, the temporal and spatial variability of the simulated and observed CHBr3 distribution is also larger so that most observations agree with the coincident model values within their uncertainties. The large differences between the individual campaigns during NH summer confirm the increased variability suggested by the model results. For two of the campaigns (AVE and TC4), FLEXPART overestimates the CHBr3 values during this time of the year, while for the other two campaigns (SEAC4RS and ACCENT), the observations and modelled values agree relatively well except for one outlier. Particularly high CHBr3 exists for the 15–25 N region, observed during the ACCENT campaign at the top altitude of a plume extending from 14 to 16 km near Houston, Texas. This value is larger than the model mean, although observational and model value uncertainties slightly overlap. In total, observations and model agree reasonably well with a larger variability during the NH summer and early autumn period. For this time of the year, the model also suggests a seasonal CHBr3 maximum which is confirmed by measurements from SEAC4RS and ACCENT, but not by the AVE and TC4 campaigns.
CHBr3 in the upper TTL over Central America shows pronounced seasonal variations as revealed by the comparisons to aircraft campaigns in Fig. 4. The CHBr3 seasonal cycle at 17 km shows a maximum from July to October (∼0.37 ppt) and a minimum from January to April (∼0.17 ppt) (Fig. 5a). Such seasonal variations can be caused by variations in the oceanic emissions or the atmospheric transport times. First, we analyse the seasonal cycle of CHBr3 emissions, averaged over the source region identified earlier, which show peak emissions from April to June of up to 320 pmol m−2 h−1. This peak in surface emissions in late spring–early summer is consistent with a peak in the TTL around 2 months later, as the mean transit time from the surface to 17 km in this region is about 55 d. Second, we analyse the seasonal cycle of the transit time and find a minimum from July to October, which is also consistent with the highest CHBr3 values in the TTL during the same time period. While the amplitude of the seasonal cycle in CHBr3 in the TTL is around 74 %, seasonal variation in the emissions and the transit time are only 36 % and 15 %, respectively. However, the amplitude in transit time does not directly translate into the amplitude in CHBr3 in the TTL, given the logarithmic nature of the atmospheric lifetime of chemical compounds. Overall, the interaction of both processes, oceanic emissions and atmospheric transport, causes the pronounced seasonal cycle of CHBr3 over Central America.
## 3.3 Maritime Continent and tropical west Pacific
CHBr3 in the TTL shows a pronounced maximum over the Maritime Continent and tropical west Pacific between 15 S–5 N and 130–220 E (black square in Figs. 1a and 6a). An important characteristic of this CHBr3 maximum (referred to as the west Pacific maximum hereinafter) is that the high values are not distributed symmetrically across the Equator but are shifted southwards. The maximum is present all year with no pronounced seasonal cycle (see Fig. 1b). In the following, we will use annual mean results to investigate if the high values arise from very strong oceanic sources or from strong convective transport. The transit time shows the smallest values of around 45 d in the west Pacific and over the Maritime Continent (Fig. 6b). The most important deviation from the CHBr3 distribution at 17 km is that over the west Pacific the shortest timescales and thus most efficient transport are not centred in the SH, but they are distributed symmetrically across the Equator.
Figure 7Modelled distribution of CHBr3 in the uppermost TTL from FLEXPART (background colouring) in comparison with ATTREX aircraft campaign measurements (coloured symbols with white edges) is given in (b) and (c). Zonal means of coincident model–measurement comparisons are given in (a) for FLEXPART and the ATTREX campaign in February–March 2014 in the west Pacific and in (d) for FLEXPART and the ATTREX campaign in February–March 2013 in the east Pacific. Temporal and spatial variability of measurements and coincident model values is shown in form of the 1σ standard deviations over all values in the respective zonal bin (horizontal lines).
Oceanic sources for CHBr3 in the west Pacific upper TTL (black square in Fig. 6a) stem mostly from the Pacific Ocean, the Maritime Continent, and also to a smaller degree Central America (Fig. 6c). The trajectory analysis clearly shows that the largest contribution comes from the west Pacific south of the Equator, while the oceanic contributions north of the Equator are lower. This pattern is directly related to the emission inventory used in this study (Ziska et al., 2013), which suggests overall stronger emissions in the southern Pacific Ocean (see Fig. S1 in the Supplement). However, available open-ocean surface measurements in both the NH and SH Pacific Ocean were sparse during the time of the construction of the inventory and mostly based on the TransBrom Sonne campaign (Krüger and Quack, 2013). The latitudinal gradient of the emission inventory with stronger emissions in the SH is based on the in situ measurements along one cruise track from Japan to Australia during October 2009 and may not be representative for other seasons and other west Pacific regions. Future ship campaigns are necessary to confirm or improve the existing emission inventory.
Pacific aircraft campaigns are used to further analyse the hemispheric differences of the diagnosed CHBr3 distribution. ATTREX measurements in the west Pacific in 2014 and in the east Pacific in 2013 are compared to FLEXPART simulations in Fig. 7. In both regions, the comparison reveals a reasonably good agreement with increasing CHBr3 values towards lower latitudes. In the west Pacific, measurements and coincident model values agree best south of 10 N, while north of this the model underestimates observations by up to 0.3 ppt. In the east Pacific, model values and measurements are closer in the NH and agree mostly within their error bars. South of the Equator, however, measurements are constantly larger with differences of up to 0.3 ppt. In total, the modelled CHBr3 entrainment over the Pacific is too small when compared to measurements, which could be due to an underestimation of the oceanic emissions in this region.
## 3.4 Tropical Indian Ocean
Annual mean CHBr3 in the uppermost TTL shows a pronounced maximum over India, the Bay of Bengal, and the Arabian Sea between 2–22 N and 35–110 E (Fig. 1a, referred to as the Indian Ocean maximum hereinafter). The simulations diagnose the globally highest TTL CHBr3 values of up to 0.5 ppt in the long-term mean over the southern tip of India. At the same time, the intermonthly standard deviation is very high over this region (Fig. 1b) due to pronounced seasonal variations. During NH summer (June–July–August), high CHBr3 values of around 0.6 ppt are found over a large region stretching from South East Asia all the way to northeast Africa between 10 and 25 N. During SH summer (December–January–February), smaller maximum values of around 0.4 ppt CHBr3 are diagnosed south of India over the Indian Ocean between 5 S and 10 N (Fig. 8).
Figure 8Modelled distribution of CHBr3 at 17 km for DJF and JJA 1979–2013 (a, b). Transit time of air masses from the ocean surface to the TTL for DJF and JJA (c, d). Oceanic source regions colour coded according to their contribution to CHBr3 at 17 km over Arabian Sea, India, and Bay of Bengal (black box in b) given in percent per 1× 1 grid box (e).
In order to evaluate the transport efficiency for oceanic short-lived trace gases in this region, the transit time is calculated from the trajectory analysis for the NH and SH summer seasons. During NH winter, transit times from the surface to the TTL show a very similar pattern as CHBr3 in the TTL, with the shortest transit times of around 45 d over the Indian Ocean coinciding with the largest CHBr3 abundance. During NH summer, on the other hand, the transit times minimize not in the region of maximum CHBr3 abundance, but instead south of this region where air masses can reach the TTL within 43 d. Between 10 and 25 N, the transport is still fast and the transit of short-lived species from their ocean sources will take around 48 d. Overall the transit time is similar to values found for the west Pacific and cannot solely account for the simulated maximum CHBr3 values.
CHBr3 contributing to the Indian Ocean TTL maximum mostly stems from the Bay of Bengal, the Arabian Sea, the equatorial region of the Indian Ocean, and the coastlines of South East Asian countries like China. Compared to the oceanic contributions identified for the Central America and west Pacific maxima, sources for the Indian Ocean CHBr3 maxima show a large regional extent including coastal and open-ocean emissions from 20 S to 30 N. Given that oceanic emissions from large parts of the Indian Ocean and adjacent coastal areas can be transported into the Asian monsoon region (Fiehn et al., 2017), the CHBr3 maxima can be explained by the strong oceanic emissions in this region combined with efficient boundary layer–TTL transport.
The global maximum of CHBr3 over India, Bay of Bengal, and the Arabian Sea is also subject to the largest uncertainties when compared to the other maxima found in our model simulations. For the construction of the emission inventory from Ziska et al. (2013), only one data set was available for the Indian Ocean (Yamamoto et al., 2001). The data set is based on measurements at seven stations in the open-ocean waters of the Bay of Bengal and reveals relatively high CHBr3 values between 8 and 15 ng L−1. Given the great distance of the sampling points from the coasts, the authors hypothesized that planktonic production is the most probable source for this high CHBr3 abundance. Independent measurements from the OASIS campaign in 2014 confirm the subtropical and tropical west Indian Ocean as a strong source for CHBr3 to the atmosphere, although open-ocean surface concentrations were overall lower with maximum values of 8 ng L−1 (Fiehn et al., 2017). A recent update of the Ziska bottom-up CHBr3 emission climatology (Fiehn et al., 2018b) suggests enhanced emissions in the tropical Indian Ocean, which would lead to even higher stratospheric entrainment in this region. While the high values from Yamamoto et al. (2001) were used locally for the emission climatology, the rest of the tropical Indian Ocean was filled by applying open-ocean data from the tropical Atlantic and Pacific. Consequently, the emission scenario for the Indian Ocean has large uncertainties, and further VSLS measurements are required to confirm or improve our estimates of the Indian Ocean as the region of strongest CHBr3 entrainment into the stratosphere.
## 3.5 Inter-annual and long-term changes
Long-term changes of tropical mean (30 N–30 S) CHBr3 mixing ratios at 17 km show a weak but significant trend of 0.017±0.012 ppt Br per decade, corresponding to a 10 % increase in CHBr3 over the whole time period (1979–2013). Regionally, the long-term changes are more pronounced and FLEXPART simulations suggest decreasing or increasing CHBr3 in the TTL depending on the location (Fig. 9). Over South America, Australia, and the central–east Pacific, the trend is not significant given the relatively small trend values compared to the inter-annual variability found here. For all other regions, CHBr3 shows a significant positive trend of 2 %–10 % per decade. CHBr3 over the Indian Ocean and Maritime Continent is highlighted in Fig. 9c as the region with the maximum trend (0.04 ppt Br per decade), mostly driven by the steep changes related to El Niño–Southern Oscillation (ENSO) over the time period 2000–2013 (Fiehn et al., 2018a). CHBr3 over the east Pacific is highlighted in Fig. 9b as an example of a negative but not significant trend (−0.017 ppt Br per decade).
Figure 9Modelled long-term change of CHBr3 (Br per decade) at 17 km for the time period 1979–2013 (a). Time series (annual means) averaged over the east Pacific and the Indian Ocean–Maritime Continent–west Pacific region are shown together with the trend (b, c). Time series (5-month running mean) are shown together with the ENSO index and Indian Ocean Dipole index (d, e).
The projected inter-annual and long-term changes of CHBr3 injections are driven by the variability of oceanic emissions (Ziska et al., 2013), convective transport from the surface to the TTL (Aschmann et al., 2011), and transport in the TTL (Krüger et al., 2009). Our model runs are based on CHBr3 emissions that allow for changes over time due to changing meteorological surface parameters (mostly ERA-Interim) but do not take into account oceanic biogeochemical and related CHBr3 production changes. Due to increasing sea surface temperature and wind speed, CHBr3 emissions increase considerably by 7.9 % from 1979 to 2013 (Ziska et al., 2017). Changes in the modelled atmospheric transport are driven by long-term changes in ERA-Interim parameters such as temperature, winds, and humidity fields, leading to an overall trend of CHBr3 at 17 km of 10 % for 1979–2013.
The two CHBr3 time series over the east Pacific and Indian Ocean–Maritime Continent (Fig. 9b and c) show the opposite long-term behaviour but also share some of the same patterns of inter-annual variability. In particular, signals like the steep CHBr3 decrease from 1997/1998 to 1999, the increase from 2008 to 2009/2010, and the relatively high values in 1982 are common to both time series. We analyse the common and separate drivers of the variability of the two time series further by comparing them to modes of tropical climate variability.
First, we compare the time series of stratospheric bromine in the east Pacific with the Multivariate ENSO Index (MEI; Wolter and Timlin, 2011) in Fig. 9d. The irregular ENSO variations in winds and sea surface temperatures over the tropical eastern Pacific Ocean drive changes in CHBr3 emissions and atmospheric transport, leading to a high correlation of the two time series (r=0.78). During El Niño years, water in the central and eastern Pacific becomes warmer than usual and the dry and steady easterly winds turn into warm and moist westerlies, leading to an increase in the oceanic emissions. This increase is driven by meteorological and oceanic surface variations but does not allow for possible changes in biogenic CHBr3 production related to changes in the eastern Pacific upwelling system (Hepach et al., 2016). At the same time, the warm east Pacific favours stronger convection, intensifying the VSLS transport into the TTL (Aschmann et al., 2011). Overall, El Niño years lead to enhanced CHBr3 injection over the east Pacific (e.g. 1982, 1986, 1991, and 1997), while La Niña corresponds to weaker CHBr3 injection (e.g. 1988, and 2010).
Second, variations in CHBr3 at 17 km over the Indian Ocean and Maritime Continent are shown together with the Indian Ocean Dipole (IOD) mode index (Fig. 9e), an indicator of the east–west temperature gradient across the tropical Indian Ocean (Saji et al., 1999). The two time series are weakly correlated (r=0.4), sharing some of their variability. The IOD is a coupled ocean–atmosphere phenomenon with anomalous cooling of the southeastern tropical Indian Ocean and anomalous warming of the western tropical Indian Ocean during a positive phase. Associated with these changes the convection normally situated over the eastern Indian Ocean warm pool shifts to the west. For some years, the positive phase results in slightly stronger CHBr3 emissions and more effective atmospheric transport (e.g. 1982–1983, 2006). In other years, strong IOD events will not impact the CHBr3 abundance over the Indian Ocean–Maritime Continent (e.g. 1997–1998). The relatively weak correlation of CHBr3 injection and IOD results from the influence of the ENSO signal on atmospheric transport in this region. A combination of sea surface temperature (SST) anomalies in the west Indian Ocean and the ENSO signal can have varying impacts on the CHBr3 injection depending on the time of year (Fiehn et al., 2018a). While positive SST anomalies together with El Niño conditions in boreal winter and spring enhance stratospheric VSLS injection, La Niña conditions in boreal autumn can also cause stronger-than-normal stratospheric injection. Overall, the inter-annual variability of the CHBr3 time series is driven by a combination of the ocean–atmosphere modes in the Indian and Pacific Ocean; however, the strong increase during 2009–2013 is not related to either of the two modes.
The overall pattern of long-term CHBr3 changes at 17 km shows a strong similarity to the long-term changes in sea surface temperature derived from ERA-Interim data (Fig. 10). While the global mean surface temperature has increased due to anthropogenic greenhouse gas emissions (IPCC, 2007), the spatial pattern of global warming is more complex. Most regions exhibit a warming trend over the 35-year period; however, much of the eastern Pacific cooled. This cooling may either be related to an unusual strong manifestation of internal variability in the observations or be caused by external regional forcings (e.g. Wang et al., 2012; Luo et al., 2012). ERA-Interim long-term temperature changes over the oceans show good agreement with HadCRUT, a combined data set of instrumental temperature records, with only small differences (Simmons et al., 2014). Most interesting for our analysis is the correlation between the SST trends and the long-term changes of stratospheric CHBr3 entrainment. Regions with large positive SST trends such as the Indian Ocean, east Atlantic, and Maritime Continent coincide with regions where the CHBr3 entrainment trend is strongest. The east Pacific, on the other hand, stands out as the region where the SST cooling trend coincides with decreasing CHBr3 entrainment. While this relation holds for many oceanic regions, we also find outliers such as the southern Indian Ocean, where SST trends are around zero but CHBr3 entrainment shows a strong positive trend. Based on our modelling approach, the interaction of two mechanisms causes the strong correlation between the SST and CHBr3 trends. Higher sea surface temperatures and stronger surface winds force a larger flux of CHBr3 out of the ocean into the atmosphere (Ziska et al., 2013) and at the same time cause enhanced convection, transporting surface air masses into the TTL (Tegtmeier et al., 2015). As the cold point tropopause altitude shows no significant trend in radiosondes or ERA-Interim data over the 1980–2013 time period (Tegtmeier et al., 2020), CHBr3 changes at 17 km correspond directly to changes of stratospheric CHBr3 entrainment. Future SST changes can be expected to drive a continued positive trend of stratospheric CHBr3 entrainment (Hossaini et al., 2012a).
Figure 10Modelled long-term change of FLEXPART CHBr3 (ppt Br per decade) at 17 km and ERA-Interim sea surface temperature (SST) (K per decade) for the time period 1979–2013.
## 3.6 Overall CHBr3 and CH2Br2 contribution to stratospheric bromine
CHBr3 together with CH2Br2 provide the main contribution of oceanic bromine to the stratosphere. CH2Br2 mixing ratios in the inner tropical belt (10 S–10 N) show less variability than CHBr3, consistent with the longer lifetime, and range between 0.9 and 1.4 ppt. The largest values can be detected over the west and central Pacific and are distributed evenly over both hemispheres (Fig. 11). There is no local CH2Br2 maxima over the Indian Ocean, as observed for CHBr3, since no strong localized sources in the region exist according to the Ziska et al. (2013) climatology. However, new ship measurements in the western Indian Ocean revealed high CH2Br2 surface water concentrations, i.e. south of Madagascar in July 2011 (Fiehn et al., 2017). Seasonal and inter-annual variations in CH2Br2 are much weaker than for CHBr3, resulting in a continuous bromine entrainment into the stratosphere.
Figure 11Modelled tropical annual mean distribution of CH2Br2 (ppt) at 17 km for 2011–2013.
Figure 12 shows the annual tropical mean CHBr3 and CH2Br2 profiles averaged over 1979–2013. At the surface, tropical mean values of 1 ppt CH2Br2 and 0.6 ppt CHBr3 are simulated, which are slightly smaller than reported observations (Ziska et al., 2013, and references therein). Mixing ratios in the free troposphere decrease by nearly 50 % (10 %) for CHBr3 (CH2Br2) when compared to the marine boundary layer. Both gases are well mixed in the free troposphere with nearly constant mixing ratios of 0.3 and 0.9 ppt for CHBr3 and CH2Br2, respectively, corresponding to 0.9 and 1.8 ppt bromine (Fig. 12a). CHBr3 shows a slight S shape with elevated abundances around 12–14 km related to strong convective outflow at this level bringing marine boundary layer air directly into the lower TTL. Above 14 km, CHBr3 mixing ratios start to decrease, reaching values of 0.22 ppt at 17 km close to the cold point, corresponding to 0.66 ppt bromine. CH2Br2 mixing ratios, on the other hand, stay nearly constant up to 18 km, as expected based on its quite long lifetime of 400 to 500 d in the TTL, reaching values of 0.9 ppt (1.8 ppt bromine).
Figure 12Modelled vertical profiles of CHBr3 and CH2Br2 (ppt Br) in the tropics (30 S–30 N) (a) and of CHBr3 for Central America (0–20 N, 70–110 W), west Pacific (15 S–5 N, 140 E–150 W), Indian Ocean (0–20 N, 40–110 E), and Atlantic (0–20 N, 20–50 W) (b) for 1979–2013.
CHBr3 profiles for four different regions (Fig. 12b) show that surface atmospheric mixing ratios are strongest in the Indian Ocean and Central America. Overall, maximum mixing ratios over the Indian Ocean result from strong surface emissions combined with a relatively strong transport and main convective outflow between 11 and 14 km, giving an S-shaped CHBr3 profile. Only for the west Pacific is transport into the stratosphere more efficient; however, smaller emissions lead to the total entrainment over this region being smaller than over the Indian Ocean.
Table 2 gives the contribution of CHBr3 and CH2Br2 to the stratospheric bromine loading based on SG injection alone and based on the sum of source and PG injection. CHBr3 and CH2Br2 have been evaluated directly at the cold point (as given by ERA-Interim) and contribute 2.4 ppt Br to stratospheric bromine loading directly in the form of SG entrainment with 25 % (75 %) resulting from CHBr3 (CH2Br2). The CHBr3 estimates of 0.2 ppt (corresponding to 0.6 ppt Br) are in agreement with other studies which range from 0.1 ppt (Warwick et al., 2006; Aschmann et al., 2009) to 0.35 ppt (Hossaini et al., 2012b). For CH2Br2, our results of 0.9 ppt (corresponding to 1.8 ppt Br) agree very well with other modelling studies (Hossaini et al., 2012b) which give estimates of 0.75–0.9 ppt. The overall contribution of the two gases in the form of SG and PG entrainment of 4.7 ppt is also in good agreement with earlier studies giving estimates ranging from 4–5 ppt (Hossaini et al., 2013) to 7.7 ppt (Liang et al., 2014).
Table 2Modelled contribution of CHBr3 and CH2Br2 to the stratospheric halogen loading in the form of source gas (SG) and total (SG + PG) contribution for 2011–2013.
Table 3Comparison of VSLS source gas (SG) contribution derived from this study and from aircraft measurements as well as product gas (PG) contribution derived from this study and studies linking aircraft measurements and modelling.
A detailed comparison of our results over the eastern and western tropical Pacific to results derived from ATTREX and CONTRAST aircraft measurements and related model calculations is given in Table 3. Considering that CHBr3 and CH2Br2 contribute >80 % of the total SG Br in the TTL, our SG estimates agree very well with the measurements (Navarro et al., 2015; Werner et al., 2017; Wales et al., 2018). PG estimates are in general characterized by larger uncertainties. The PG contribution can be inferred from atmospheric measurements of BrO, the most abundant Bry species, and the partitioning of inorganic Bry derived from a photochemical model (Koenig et al., 2017; Werner et al., 2017; Wales et al., 2018). Uncertainties in this method arise from modelling the Bry partitioning and from uncertainties in measuring BrO and can be as large as ±2.1 ppt (e.g. Wales et al., 2018).
Our study uses a simplified approach with a prescribed Bry partitioning including its spatial and temporal variations. We have carried out sensitivity studies to analyse how variations in the Bry partitioning impact the total amount of PG reaching the cold point tropopause (not shown here). Our studies show that uncertainties of 20 % in the partitioning will lead to variations of ±0.4 ppt in the PG entrainment. Such uncertainties in the Bry partitioning can result from errors in the aerosol loading and in the heterogeneous reactions. Distributions of total Bry and BrO in p-TOMCAT, the model used to derive the partitioning, have been shown to agree well with in situ and satellite observations (Yang et al., 2005, 2010). If the uncertainties in the partitioning would be as large as 50 %, the PG entrainment would show variations of ±1.1 ppt. Overall the PG entrainment based on our simplified approach agrees very well (within ±25 %) with estimates from other studies derived from BrO measurements and photochemical modelling (Table 3).
4 Discussion and summary
We combine observational data sets, including surface and upper-air measurements, with high-resolution atmospheric modelling in order to analyse the spatial and temporal variability of VSLS entrainment into the stratosphere. Oceanic CHBr3 in the TTL, on its way from the marine boundary layer into the stratosphere, shows a very high spatial and temporal variability. Regional maxima with mixing ratios of up to 0.4 to 0.5 ppt are simulated to be over Central America (1) and the Maritime Continent and tropical west Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The strongest stratospheric CHBr3 entrainment is projected to occur over the region of India, Bay of Bengal, and Arabian Sea (3); however, no data from aircraft campaigns are available to confirm this finding. Other tropical regions with only little convective uplift show smaller mixing ratios, mostly between 0.1 and 0.2 ppt. CHBr3 fields on daily mean or shorter timescales are characterized by pronounced spatial variations with highly localized injections.
The modelled CHBr3 maximum over Central America is caused by the co-occurrence of convectively driven short transport timescales and strong regional sources, with the latter being confirmed by data from various ship campaigns. Moreover, the combined seasonality of transport efficiency and emission strength causes the strong seasonality of CHBr3 at 17 km over Central America. The model simulations also show a high spatial variability of CHBr3 with strong latitudinal gradients, which is confirmed by available aircraft campaigns. The comparisons reveal that our model results are similar to the measurements for NH winter, but over- and underestimate (depending on the campaign) observations during NH summer, when the variability is largest. Exceptionally high CHBr3 observed during the ACCENT campaign is also evident in the model results, but only in the daily and not in the monthly mean values. Given that individual campaigns may not be representative of mean values but may rather describe one side of the large spectrum, differences between model simulations and measurements, such as the ones discussed above, have to be interpreted with caution.
The modelled CHBr3 maximum in the TTL over the west Pacific is centred south of the Equator. This distribution cannot be explained by transport timescales, which are similar north and south of the Equator and do not reveal strong hemispheric differences. Instead, strong oceanic sources south of Equator, prescribed based on limited available measurements, are responsible for the high CHBr3 mixing ratios in the SH. Measurements in the upper TTL from the ATTREX aircraft campaign show an overall good agreement with model results, but they also indicate that the model underestimates CHBr3 in the tropics. Furthermore, ATTREX measurements did not show any significant gradient between the NH and SH tropics near the tropopause. Given the scarcity of in situ measurements in the open-ocean water of the west Pacific, it may be possible that oceanic emission estimates used here are too low, especially north of the Equator. Future ship campaigns are needed to confirm spatial and temporal differences and to improve existing bottom-up emission climatologies.
The overall strongest maximum over India, Bay of Bengal, and Arabian Sea is caused by very large local sources. Transport from the ocean surface to 17 km is also efficient but not strong enough to solely explain the pronounced maxima. No upper-air measurements are available to back up this upper TTL maximum, and oceanic measurements used for the emission scenarios are also scarce. For the global tropical–extratropical distribution of CHBr3 entrainment, the largest uncertainties exist for estimated maxima in the region over India, Bay of Bengal, and Arabian Sea. In situ measurements of the oceanic sources and the atmospheric distribution are needed to reduce local uncertainties and confirm global mean values.
Our understanding of stratospheric VSLS entrainment is also limited by the fact that currently available emission inventories do not take seasonal variations in oceanic concentrations into account.
Inter-annual variability of stratospheric CHBr3 entrainment is to a large part driven by the variability of the coupled ocean–atmosphere circulation systems such as ENSO in the Pacific and IOD in the Indian Ocean. Long-term trends of the CHBr3 entrainment, on the other hand, show a pronounced correlation with the SST trends. Both relations are based on the fact that stratospheric CHBr3 entrainment is driven by strong sources and convective entrainment, which maximize for high surface temperatures and strong winds. Following the SST trends, long-term changes of CHBr3 entrainment are positive in the west Pacific and Asian monsoon region but negative in the east Pacific. The tropical mean trend accounts for an increase of 0.017±0.012 ppt Br per decade resulting in a 10 % increase over the 1979–2013 time period. The overall contribution of CHBr3 and CH2Br2 to the stratospheric halogen loading is 4.7 ppt Br with 50 % being entrained in the form of source gases and the other 50 % being entrained in the form of product gases.
Data availability
Data availability.
The bromoform and dibromomethane emission inventory data (Ziska et al., 2013) and the FLEXPART model output can be inquired about by contacting the authors.
Supplement
Supplement.
Author contributions
Author contributions.
ST, KK, and BQ developed the idea for this paper and the model experiments. ST carried out the FLEXPART model calculations and the comparison to the aircraft observations. EA provided aircraft data. FZ compiled the Ziska et al. (2013) climatology for this study. ST wrote the manuscript with contributions from all co-authors. KK and BQ led the ROMIC THREAT project.
Competing interests
Competing interests.
The authors declare that they have no conflict of interest.
Acknowledgements
Acknowledgements.
Susann Tegtmeier was funded by ROMIC THREAT (01LG1217A) when compiling the study and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – TE 1134/1 when writing the manuscript. Elliot Atlas was supported by grants from the NASA Upper Atmosphere. The authors are grateful to the ECMWF for making the reanalysis product ERA-Interim available. The authors would like to thank the editor, Jianzhong Ma, and the two anonymous reviewers for their helpful comments.
Financial support
Financial support.
This research has been supported by the BMBF (ROMIC THREAT (grant no. 01LG1217A)).
The article processing charges for this open-access
publication were covered by a Research
Centre of the Helmholtz Association.
Review statement
Review statement.
This paper was edited by Jianzhong Ma and reviewed by two anonymous referees.
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https://mathcracker.com/exponential-function-calculator | # Exponential Function Calculator
Instructions: Use this step-by-step Exponential Function Calculator, to find the function that describe the exponential function that passes through two given points in the plane XY. You need to provide the points $$(t_1, y_1)$$ and $$(t_2, y_2)$$, and this calculator will estimate the appropriate exponential function and will provide its graph.
First t ($$t_1$$) =
First y ($$f(t_1)$$) =
Second t ($$t_2$$) =
Second y: ($$f(t_2)$$) =
Points to evaluate (Optional. Comma or space separated) =
## Exponential Function Calculator from Two Points
The idea of this calculator is to estimate the parameters $$A_0$$ and $$k$$ for the function $$f(t)$$ defined as:
$f(t) = A_0 e^{kt}$
so that this function passes through the given points $$(t_1, y_1)$$ and $$(t_2, y_2)$$.
### But, how do you find an exponential function from points?
Technically, in order to find the parameters you need to solve the following system of equations:
$y_1 = A_0 e^{k t_1}$ $y_2 = A_0 e^{k t_2}$
Solving this system for $$A_0$$ and $$k$$ will lead to a unique solution, provided that $$t_1 = \not t_2$$.
Indeed, by dividing both sides of the equations:
$\displaystyle \frac{y_1}{y_2} = \frac{e^{k t_1}}{e^{k t_2}}$ $\displaystyle \Rightarrow \, \frac{y_1}{y_2} = e^{k (t_1-t_2)}$ $\displaystyle \Rightarrow \, \ln\left(\frac{y_1}{y_2}\right) = k (t_1-t_2)$ $\displaystyle \Rightarrow \, k = \frac{1}{t_1-t_2} \ln\left(\frac{y_1}{y_2}\right)$
In order to solve for $$A_0$$ we notice from the first equation that:
$A_0 = y_1 e^{-k t_1} = y_1 \frac{y_2}{y_1 e^{k t_2}} =\frac{y_2}{e^{k t_2}}$
### How do you calculate exponential growth?
It is not always growth. Indeed, if the parameter $$k$$ is positive, then we have exponential growth, but if the parameter $$k$$ is negative, then we have exponential decay.
The parameter $$k$$ will be zero only if $$y_1 = y_2$$ (the two points have the same height).
For specific exponential behaviors you can check our exponential growth calculator and the exponential decay calculator , which use specific parameters for that kinds of exponential behavior. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9529674649238586, "perplexity": 318.6407966068152}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780056752.16/warc/CC-MAIN-20210919065755-20210919095755-00370.warc.gz"} |