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Since its first release, the most critical element in Entity Framework
has been the
ObjectContext. It is this
class that allows us to interact with a database using a conceptual model.
The context lets us express and execute queries, track changes to objects
and persist those changes back to the database. The
ObjectContext class interacts with other important
Entity Framework classes such as the
ObjectSet, which enables set operations on our
entities in memory, and
which is the brains behind executing queries. All of these classes are
replete with features and functionality—some of it complex and much of it
only necessary for special cases. After two iterations of Entity Framework
(in .NET 3.5 SP1 and .NET 4) it was clear that developers were most commonly
using a subset of the features, and unfortunately, some of the tasks we
needed to do most frequently were difficult to discover and code.
Recognizing this, the Entity Framework team set out to make it easier
for developers to access the most frequently used patterns for working with
objects within Entity Framework. Their solution was a new set of classes
that encapsulate this subset of
ObjectContext features. These new classes use the
ObjectContext behind the scenes, but
developers can work with them without having to tangle with the
ObjectContext unless they need to specifically use
some of the more advanced features. The new set of classes was originally
released as part of Entity Framework 4.1 (EF 4.1).
The prominent classes in this simplified API surface are the
DbQuery. This entire package of new logic is
referred to as the DbContext API. The new API contains more than just the
DbContext class, but it is the
DbContext that orchestrates all of the new
The DbContext API is available in the EntityFramework.dll assembly, which also contains the logic that drives Entity Framework Code First. This assembly is separate from .NET and is even deployed separately as the EntityFramework NuGet package. A major portion of the Entity Framework is part of the .NET Framework (primarily System.Data.Entity.dll). The components that are included in .NET are considered the “core components” of Entity Framework. The DbContext API is completely dependent on these core components of Entity Framework. The Entity Framework team has indicated that they are working to move more of these core components out of .NET and into the EntityFramework.dll assembly. This will allow them to deliver more features between releases of the .NET Framework.
In Table 1-1, you can see a list of the high-level features and classes in the DbContext API, how they relate to the API surface from Entity Framework 4 (EF4), their general purpose, and their benefits.
Table 1-1. Overview of DbContext API features
DbContext API feature
Relevant EF4 feature/class
Benefit of DbContext API
Represent a session with the database. Provide query, change tracking and save capabilities.
Exposes and simplifies most commonly used features of ObjectContext.
Provide set operations for entity types, such as Add, Attach and Remove. Inherits from DbQuery to expose query capabilities.
Exposes and simplifies most commonly used features of ObjectSet.
Provide querying capabilities.
The query functionality of DbQuery is exposed on DbSet, so you don’t have to interact with DbQuery directly.
Change Tracker API
Get access to change tracking information and operations (e.g., original values, current values) managed by the context.
Simpler and more intuitive API surface.
Provide automatic validation of data at the data layer. This API takes advantage of validation features already existing in .NET 4.
New to DbContext API.
Code First Model Building
Reads classes and code-based configurations to build in-memory model, metadata and relevant database.
New to DbContext API.
The DbContext API is not released as part of the .NET Framework. In order to be more flexible (and frequent) with releasing new features to Code First and the DbContext API, the Entity Framework team distributes EntityFramework.dll through Microsoft’s NuGet distribution feature. NuGet allows you to add references to your .NET projects by pulling the relevant DLLs directly into your project from the Web. A Visual Studio extension called the Library Package Manager provides an easy way to pull the appropriate assembly from the Web into your projects. Figure 1-1 displays a screenshot of the Library Package Manager being used to download and add the EntityFramework NuGet package into a project. | <urn:uuid:626421fe-82bc-4c61-893f-c7e6213cdb53> | 2.625 | 975 | Documentation | Software Dev. | 39.40473 | 95,569,692 |
Placed in the Apiaceae (Umbelliferae) in Michigan Flora. Quite different from all our other Araliaceae and sometimes placed in its own family, Hydrocotylaceae.
1. Petioles attached near center of leaf blade (leaves peltate).
1. Petioles marginal, attached at sinus of a reniform blade.
2. Umbels sessile or subsessile.
2. Umbels on long peduncles.
All species found in Hydrocotyle
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 17, 2018. https://michiganflora.net/genus.aspx?id=Hydrocotyle. | <urn:uuid:d9fc819d-079e-403c-b9d0-67297c9baf03> | 2.8125 | 181 | Knowledge Article | Science & Tech. | 44.114902 | 95,569,698 |
Corals recovering on the Coffs Coast
CORALS in waters off the Coffs Coast are returning to health in the wake of one of the largest bleaching events in recent history.
Early research suggests coral mortality rates have been limited to the northern side of South Solitary Island after water surface temperatures as high at 27.5 degrees were recorded in the Solitary Islands Marine Park over summer.
The hot temperatures initially caused an outbreak as far as South West Rocks, but cooling temperatures in recent weeks have turned fortunes around.
Steven Dalton from Southern Cross University said many corals had started to regain their colour.
"We have done follow-up observations in a lot of the affected areas and it looks like the micro algae is coming back into the tissue of the corals which is a good sign," he said.
"There are still a couple of sites where there's going to be a reasonable amount of mortality in the most affected species.
"It's a community of thousands of polyps living together attached - some parts may not die, which are normally in the shaded areas.
"If we don't get any more heating events in next four to five years it should recover."
SCU has joined research efforts on the Great Barrier Reef and Torres Strait to monitor widespread devastation of coral systems.
"It will give us an indication about how things are travelling over a longer period of time, for example if there is increasing severity, how will coral community react to that?" Steven said.
Researchers will conduct another survey in the South Solitary Islands after winter. | <urn:uuid:9df01db1-68a3-4187-9763-af6c5d648a24> | 2.78125 | 319 | News Article | Science & Tech. | 42.560897 | 95,569,701 |
In a study published in the April 30 issue of the academic journal Chemistry & Biology, UK pharmaceutical sciences graduate student Abby Ho mentored by assistant professor Kyung-Bo Kim and ophthalmology and visual sciences assistant professor Royce Mohan describe a compound that acts directly on LMP2, a component of the immune proteasome variant that has been identified abundantly expressed in certain types of tumors, including some prostate cancers.
The compound, dubbed UK-101, inhibits LMP2 while not attacking normal cells, indicating that it could be an effective cancer treatment that does not produce the kinds of unpleasant side effects reported by many patients currently treated with broadly acting proteasome inhibitors and chemotherapeutics.
Kim and Mohan also suggest that UK-101 may be useful in treating a number of diseases in which LMP2 is involved. The researchers are particularly excited about UK-101’s potential in treating inflammatory conditions associated with arthritis, rheumatism and cardiovascular diseases.
The researchers report success in using the compound in tests in prostate cancer cells. Importantly, Kim and Mohan point out that in test using highly sensitive vascular endothelial cells obtained from blood vessels that UK-101 was found to be non toxic because they lacked expression of this LMP2 immunoproteasome target.
Dan Adkins | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:4a9a0ea1-6541-46cd-87e8-f4dbce3f5e3a> | 2.796875 | 935 | Content Listing | Science & Tech. | 36.391038 | 95,569,702 |
NASA's DNA Sequencing in Space is a Success
News Aug 31, 2016
Two hundred miles above Earth, NASA has conducted the first genome sequencing in space, and researchers at UC San Francisco helped analyze the data sent back from the International Space Station and confirm that the process was a success.
Using a hand-held, USB-powered sequencing device called the MinION, astronaut Kate Rubins, PhD, sequenced samples of mouse, bacteria and virus DNA. This portable sequencing technology could eventually help diagnose sick astronauts, monitor space station food, water, and environment for microbes, and identify extraterrestrial life forms.
As part of a collaboration with NASA on the Biomolecular Sequencer project, Earth-bound researchers – a bicoastal team at UCSF and Weill Cornell Medical College – analyzed the sequencing data from space and compared it to identical samples sequenced on the ground. The analysis would tell whether the journey to space and conditions aboard the space station affected the sequencing results.
Charles Chiu, MD, PhD, director of the UCSF-Abbott Viral Diagnostics and Discovery Center, led the team at UCSF. “Up until recently technology for sequencing in space hasn’t been available because sequencers are generally large bulky instruments,” Chiu said.
The pocket-sized MinION employs a technology known as nanopore sequencing, which sends an ionic current through tiny pores in natural cell membranes. As DNA molecules pass through these nanopores one by one, the changes in ion flow are recorded and used to decode the DNA sequence. A sequencing run can take as little as 10 minutes.
Chiu said a big unknown was whether the microgravity in space would affect the microfluidics of the sequencing device.
“It didn’t turn out to be a huge problem,” Chiu said. His team’s analysis of the space and Earth data found comparable results. “We essentially got equivalent data, and it’s of very high quality, probably within the top 20 percent of nanopore runs that we do routinely here on Earth,” Chiu said.
Besides its portability, another advantage of nanopore sequencing is its ability to rapidly sequence any and all genetic material in a sample, even from organisms that have never been encountered before. Most conventional sequencing methods are confined to a target approach – researchers have to know what they’re looking for and must set up the sequencing accordingly.
Chiu has used nanopore sequencing to test for emerging outbreaks like Ebola and Zika without the need to design a custom diagnostic test. The MinION, made by Oxford Nanopore Technologies, has been employed at field laboratories in some of the remotest areas on Earth – and may someday take a trip to Mars.
In this initial proof-of-principle experiment, the samples were prepared on Earth. On future missions, sample preparation, sequencing, and real-time analysis on a laptop could all be completed in space, and the capacity to do so would be critical for long-term space exploration, Chiu said.
“Onboard sequencing makes it possible for the crew to know what is in their environment at any time,” said project manager and NASA microbiologist Sarah Castro-Wallace, PhD, in a press release. “That allows us on the ground to take appropriate action – do we need to clean this up right away, or will taking antibiotics help or not? We can resupply the station with disinfectants and antibiotics now, but once crews move beyond the station’s low Earth orbit, we need to know when to save those precious resources and when to use them.”
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New Algorithms Help Extract 3-D Biological Structure from Limited Data
Example of a clean single-particle diffraction image (left) and the same diffraction image after noise contamination (right). Credit: UC Berkeley
Understanding the 3-D molecular structure of important nanoobjects like proteins and viruses is crucial in biology and medicine. With recent advances in X-ray technology, scientists can now collect diffraction images from individual particles, ultimately allowing researchers to visualize molecules at room temperature.
However, determining 3-D structure from these single-particle diffraction experiments is a significant hurdle. For instance, current data acquisition rates are very limiting, typically resulting in fewer than 10 useful snapshots per minute, limiting the amount of features that can be resolved. Additionally, the images are often highly corrupted with noise and other experimental artefacts, making it difficult to properly interpret the data.
To meet these challenges, a team of researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) has developed a new algorithmic framework called multi-tiered iterative phasing (M-TIP) that utilizes advanced mathematical techniques to determine 3-D molecular structure from very sparse sets of noisy, single-particle data. This approach essentially allows researchers to extract more information from experiments with limited data. Applied mathematicians Jeffrey Donatelli and James Sethian, and physical bioscientist Peter Zwart introduced this framework by expanding on an algorithm that they originally developed to solve the reconstruction from a related X-ray scattering experiment, called fluctuation X-ray scattering. A paper describing the M-TIP framework was published June 26 in the Proceedings of the National Academy of Sciences.
“This approach has the potential to revolutionize the field,” says Zwart. “Given that it is hard to get a lot of good data, approaches that reduce the amount of data needed to successfully image 3-D nanoobjects are likely to receive a warm welcome.”
Donatelli, Sethian and Zwart are all part of CAMERA (The Center for Advanced Mathematics for Energy Research Applications), whose mission is to create the state-of-the-art mathematics required to handle data from many of DOE’s most advanced scientific facilities. CAMERA is jointly funded by the Advanced Scientific Computing Research and Basic Energy Sciences programs in DOE’s Office of Science.
Single Particle Diffraction
The recent advent of X-ray free-electron lasers (XFELs) has enabled several new experimental techniques for studying biomolecules that were infeasible with traditional light sources. One such technique is single-particle diffraction, which collects a large number of X-ray diffraction snapshots with only a single particle in the beam. By leveraging the extreme power of XFELs, researchers can collect measurable signals even from the tiniest particles.
One big advantage offered by this single-particle diffraction technique is the ability to study how different copies of a molecule vary or change in shape. Since each image comes from a single particle, these variations can be captured in the experiment, in contrast to traditional imaging methods like crystallography or small-angle X-ray scattering, where researchers can only measure an average over all different states of the molecular sample.
However, determining the 3-D structure from single-particle diffraction data is challenging. To begin, when each particle is imaged, its orientation is unknown and needs to be recovered in order to properly combine the data into a 3-D diffraction volume. This problem is compounded if the molecule can take on different shapes, which requires additional classification of the images. Furthermore, phase information is not recorded in diffraction images and must be recovered in order to complete the reconstruction. Finally, even with powerful XFELs, the number of scattered photons is very small, resulting in extremely noisy images, which can be further contaminated by systematic background and detector readout issues.
Previous approaches are based on solving the reconstruction problem in separate steps, where each individual problem is addressed separately. Unfortunately, a drawback to these serial approaches is that they do not easily leverage prior known features about what the molecule looks like. In addition, any error committed in one step is propagated to the next, resulting in a further increase in error. This “error snowball” ultimately degrades the quality of the reconstruction obtained in the final step.
Best of Both Worlds
Instead of solving the computational problems in separate steps, the team’s M-TIP algorithm solves all parts of the problem concurrently. This approach leverages prior information about the structure to greatly reduce the degrees of freedom of the problem in all steps, and consequently reduce the required information needed to achieve a 3-D reconstruction.
“Standard black-box optimization techniques can incorporate prior knowledge into the reconstruction but throw away all of the structure of the problem, whereas solving it in completely separate serial substeps exploits the structure of the problem but throws away almost all prior information about what the solution might look like,” Donatelli said. “M-TIP leverages the best of both worlds by exploiting the structure of the problem to break up the computation into several manageable chunks and then iteratively refining over all of these chunks to arrive at a solution which is consistent with both the data and any structural constraints.”
Using this technique, the team was able to determine 3-D structure from extremely low image counts from simulated data, as low as 6 to 24 images for noise-free data and 192 images from highly contaminated data.
Breaking New Ground
This work is part of a new collaboration initiative between SLAC National Accelerator Laboratory, CAMERA, the National Energy Research Scientific Computing Center (NERSC) and Los Alamos National Laboratory as part of DOE’s Exascale Computing Project (ECP). The goal of the project is to develop the computational tools necessary to perform real-time data analysis from experiments being conducted at SLAC’s Linac Coherent Light Source (LCLS). With upgrades to the beamline, LCLS-II plans to generate several terabytes of data per second, which, for example, will allow scientists to greatly expand upon current single-particle experiments. Analyzing all of this data in real-time will require new algorithms and large computing machines. The M-TIP algorithm will serve as part of this process.
“These are some of the most challenging problems in computational data science,” says Sethian. “To tackle them, we need to exploit a range of technologies, including emerging exascale computing architectures, sophisticated high speed networks, and the most advanced mathematical algorithms available. Bringing CAMERA scientists together with exascale application projects has opened the door to building tools to approach some pressing problems in biology and materials sciences.”
The researchers note that these are just the first steps. In order for the method to be ready to be deployed, other hurdles have to be overcome.
“Experimental science is messy,” says Zwart. “There are additional experimental effects that have to be taken into consideration in order for us to get the best possible results.”
“Fortunately, M-TIP is a very modular technique,” adds Donatelli, “so, it is well suited to modeling many of these additional effects without needing to change the core algorithmic framework.”
The team is currently working on studying these effects as part of the Single Particle Initiative, a large, multi-institutional collaboration dedicated to addressing theoretical and practical issues in X-FEL-based single molecule imaging, ultimately leading to providing the scientific community with the tools needed to break new ground in biology, medicine and energy sciences.
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1) A material will float on the surface of a liquid if the material has a density of less than that of the liquid. Given density of water as 1.0g/mL, will a block having a volume of 1.2*10^4 in^3 and weighing 350 lb float or sink?
2) The density of pure silver is 10.5g/cm^3 at 20 degrees C. If 5.25 grams of pure silver pellets is added to a graduated cylinder containing 11.2 mL of water, to what volume will the water in the cylinder rise?© BrainMass Inc. brainmass.com July 19, 2018, 7:07 pm ad1c9bdddf
Please see the attached file.
You might want to ...
The solution provides a step by step process to solve the two problems. | <urn:uuid:ebb86060-4249-402d-b444-08e23648497a> | 3.40625 | 172 | Tutorial | Science & Tech. | 97.068125 | 95,569,725 |
Hail bounces off the roof of the car with a velocity of +15 m/s. Ignoring the weight of the hailstones, what is the force exerted by the hail on the roof.© BrainMass Inc. brainmass.com July 19, 2018, 6:54 pm ad1c9bdddf
Let's assume that the hailstones reflect off the roof elastically, so that the change in vertical velocity is 30 meters/second. Suppose that during the hailstorm the mass flux of the hail is J.
J is the mass per square meter per second that is raining down. If the ...
A detailed solution is given. | <urn:uuid:09daa499-2832-48cf-8b3e-b0114beee710> | 3.078125 | 136 | Q&A Forum | Science & Tech. | 85.567783 | 95,569,726 |
Building sophisticated Java applets means learning about threading--if you need to read data from a network, for example, you can't afford to let a delay in its delivery lock up your entire applet. Java Threads introduces the Java threading API and uses non-computing analogies--such as scenarios involving bank tellers--to explain the need for synchronization and the dangers of deadlock. Scott Oaks and Henry Wong follow up their high-level examples with more detailed discussions on building a thread scheduler in Java, dealing with advanced synchronization issues, and handling exceptions.
If you are a Java programmer and you are thinking of using threads to make your work more responsive or even faster given todays symmetric multiprocessing hardware, then this is an excellent book. It probably isnt academic enough for use in formal education but as a practical guide to how not to do things, and hopefully how to do things better, it is excellent. - Harry Fairhead, VSJ, May 2005 | <urn:uuid:15f1c9cf-807e-4841-b703-b39d98f3265e> | 2.875 | 202 | User Review | Software Dev. | 28.420847 | 95,569,727 |
Is true for any number a,b,c equality:?
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The root of the equation ? is: ? | <urn:uuid:df1ee5a5-7c40-4366-8818-f3c5dea523d3> | 2.734375 | 608 | Content Listing | Science & Tech. | 78.919903 | 95,569,728 |
A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. For this reason, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms (supercell, squall line, multi-cell, and single-cell), supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2-4 hours.
Supercells are often put into three classification types: Classic, Low-precipitation (LP), and High-precipitation (HP). LP supercells are usually found in climates that are more arid, such as the high plains of the United States, and HP supercells are most often found in moist climates. Supercells can occur anywhere in the world under the right pre-existing weather conditions, but they are most common in the Great Plains of the United States in an area known as Tornado Alley and in the Tornado Corridor of Argentina, Uruguay and southern Brazil.
- 1 Characteristics
- 2 Geography
- 3 Anatomy of a supercell
- 4 Supercell variations
- 5 Effects
- 6 Examples
- 7 Gallery
- 8 See also
- 9 References
- 10 External links
Supercells are usually found isolated from other thunderstorms, although they can sometimes be embedded in a squall line. Typically, supercells are found in the warm sector of a low pressure system propagating generally in a north easterly direction in line with the cold front of the low pressure system. Because they can last for hours, they are known as quasi-steady-state storms. Supercells have the capability to deviate from the mean wind. If they track to the right or left of the mean wind (relative to the vertical wind shear), they are said to be "right-movers" or "left-movers," respectively. Supercells can sometimes develop two separate updrafts with opposing rotations, which splits the storm into two supercells: one left-mover and one right-mover.
Supercells can be any size – large or small, low or high topped. They usually produce copious amounts of hail, torrential rainfall, strong winds, and substantial downbursts. Supercells are one of the few types of clouds that typically spawn tornadoes within the mesocyclone, although only 30% or fewer do so.
Supercells can occur anywhere in the world under the right weather conditions. The first storm to be identified as the supercell type was the Wokingham storm over England, which was studied by Keith Browning and Frank Ludlam in 1962. Browning did the initial work that was followed up by Lemon and Doswell to develop the modern conceptual model of the supercell. To the extent that records are available, supercells are most frequent in the Great Plains of the central United States and southern Canada extending into the southeastern U.S. and northern Mexico; east-central Argentina and adjacent regions of Uruguay; Bangladesh and parts of eastern India; South Africa; and eastern Australia. Supercells occur occasionally in many other mid-latitude regions, including Eastern China and throughout Europe. The areas with highest frequencies of supercells are similar to those with the most occurrences of tornadoes; see tornado climatology and Tornado Alley.
Anatomy of a supercell
The current conceptual model of a supercell was described in Severe Thunderstorm Evolution and Mesocyclone Structure as Related to Tornadogenesis by Leslie R. Lemon and Charles A. Doswell III. (See Lemon technique).
Supercells derive their rotation through tilting of horizontal vorticity (an invisible horizontal vortex) caused by wind shear. Strong updrafts lift the air turning about a horizontal axis and cause this air to turn about a vertical axis. This forms the deep rotating updraft, the mesocyclone.
A cap or capping inversion is usually required to form an updraft of sufficient strength. The cap puts an inverted (warm-above-cold) layer above a normal (cold-above-warm) boundary layer, and by preventing warm surface air from rising, allows one or both of the following:
- Air below the cap warms and/or becomes more moist
- Air above the cap cools
This creates a warmer, moister layer below a cooler layer, which is increasingly unstable (because warm air is less dense and tends to rise). When the cap weakens or moves, explosive development follows.
In North America, supercells usually show up on Doppler radar as starting at a point or hook shape on the southwestern side, fanning out to the northeast. The heaviest precipitation is usually on the southwest side, ending abruptly short of the rain-free updraft base or main updraft (not visible to radar). The rear flank downdraft, or RFD, carries precipitation counterclockwise around the north and northwest side of the updraft base, producing a "hook echo" that indicates the presence of a mesocyclone.
Structure of a supercell
This "dome" feature appears above the strongest updraft location on the anvil of the storm. It is a result of a very powerful updraft; enough to break through the upper levels of the troposphere. An observer who is at ground level too close to the storm is unable to see the overshooting top due to the fact that the anvil blocks the sight of this feature. The overshooting is visible from satellite images as a "bubbling" amidst the otherwise smooth upper surface of the anvil cloud.
An anvil forms when the storm's updraft collides with the upper levels of the lowest layer of the atmosphere, or the troposphere, and has nowhere else to go due to the laws of fluid dynamics- specifically pressure, humidity, and density. The anvil is very cold and virtually precipitation free even though virga can be seen falling from the forward sheared anvil. Since there is so little moisture in the anvil, winds can move freely. The clouds take on their anvil shape when the rising air reaches 15,200–21,300 metres (50,000–70,000 ft) or more. The anvil's distinguishing feature is that it juts out in front of the storm like a shelf. In some cases, it can even shear backwards, called a backsheared anvil, another sign of a very strong updraft.
This area, typically on the southern side of the storm in North America, is relatively precipitation free. This is located beneath the main updraft, and is the main area of inflow. While no precipitation may be visible to an observer, large hail may be falling from this area. A region of this area is called the Vault. It is more accurately called the main updraft area.
The wall cloud forms near the downdraft/updraft interface. This "interface" is the area between the precipitation area and the precipitation-free base. Wall clouds form when rain-cooled air from the downdraft is pulled into the updraft. This wet, cold air quickly saturates as it is lifted by the updraft, forming a cloud that seems to "descend" from the precipitation-free base. Wall clouds are common and are not exclusive to supercells; only a small percentage actually produce a tornado, but if a storm does produce a tornado it usually exhibits wall clouds that persist for more than ten minutes. Wall clouds that seem to move violently up or down, and violent movements of cloud fragments (scud or fractus) near the wall cloud are indications that a tornado could form.
Mammatus (Mamma, Mammatocumulus) are bulbous or pillow-like cloud formations extending from beneath the anvil of a thunderstorm. These clouds form as cold air in the anvil region of a storm sinks into warmer air beneath it. Mammatus are most apparent when they are lit from one side or below and are therefore at their most impressive near sunset or shortly after sunrise when the sun is low in the sky. Mammatus are not exclusive to supercells and can be associated with developed thunderstorms and cumulonimbus.
Forward Flank Downdraft (FFD)
This is generally the area of heaviest and most widespread precipitation. For most supercells, the precipitation core is bounded on its leading edge by a shelf cloud that results from rain-cooled air within the precipitation core spreading outward and interacting with warmer, moist air from outside of the cell. Between the precipitation-free base and the FFD, a "vaulted" or "cathedral" feature can be observed. In high precipitation supercells an area of heavy precipitation may occur beneath the main updraft area where the vault would alternately be observed with classic supercells.
Rear Flank Downdraft (RFD)
The RFD of a supercell is a very complex and not yet fully understood feature. RFD mainly occur within classic and HP supercells although RFDs have been observed within LP supercells. The RFD of a supercell is believed to play a large part in tornadogenesis by further tightening rotation within the surface mesocyclone. RFDs are caused by mid level steering winds of a supercell colliding with the updraft tower and moving around it in all directions; specifically the flow that is redirected downward is referred to as the RFD. This downward surge of relatively cool mid level air, due to interactions between dew points, humidity, and condensation of the converging of air masses, can reach very high speeds and is known to cause widespread wind damage. The radar signature of an RFD is a hook like structure where sinking air has brought with it precipitation.
A vault is not observed with all supercells. The vault can only be identified visibly due to it visibly appearing to be free of precipitation but usually containing large hail. On Doppler radar, the region of very high precipitation echos with a very sharp gradient perpendicular to the RFD.
A flanking line is a line of smaller cumulonimbi or cumulus that form in the warm rising air pulled in by the main updraft. Due to convergence and lifting along this line, landspouts sometimes occur on the outflow boundary of this region.
Radar features of a supercell
- Hook echo or Pendant
The "hook echo" is the area of confluence between the main updraft and the rear flank downdraft (RFD). This indicates the position of the mesocyclone, and probably a tornado.
- Bounded weak echo region (or BWER)
This is a region of low radar reflectivity bounded above by an area of higher radar reflectivity with an untilted updraft. This is evidence of a strong updraft, and oftentimes the presence of a tornado.
- Inflow notch
A "notch" of weak reflectivity on the inflow side of the cell. This is not a V-Notch.
- V Notch
A "V" shaped notch on the leading edge of the cell, opening away from the main downdraft. This is an indication of divergent flow around a powerful updraft.
- Hail spike
Supercell thunderstorms are sometimes classified by meteorologists and storm spotters into three categories. However, not all supercells fit neatly into any one category, being hybrid storms, and many supercells may fall into different categories during different periods of their lifetimes. The standard definition given above is referred to as the Classic supercell. All types of supercells typically produce severe weather.
Low Precipitation (LP)
LP supercells contain a small and relatively light precipitation (rain/hail) core that is well separated from the updraft. The updraft is intense and LPs are inflow dominant storms. The updraft tower is typically more strongly tilted and the deviant rightward motion lesser than for other supercell types. The forward flank downdraft (FFD) is noticeably weaker than for other supercell types and the rear-flank downdraft (RFD) is much weaker—even visually absent in many cases. Like classic supercells, LP supercells tend to form within stronger mid-to-upper level storm-relative wind shear, however, the atmospheric environment leading to their formation is not well understood. The moisture profile of the atmosphere, particularly the depth of the elevated dry layer, also appears to be important and the low-to-mid level shear may also be important.
This type of supercell may be easily identifiable with "sculpted" cloud striations in the updraft base or even a "corkscrewed" or "barber pole" appearance on the updraft, and sometimes an almost "anorexic" look compared to classic supercells. This is because they often form within drier moisture profiles (often initiated by dry lines) leaving LPs with little available moisture despite high mid-to-upper level environmental winds. They most often dissipate rather than turning into classic or HP supercells, although it is still not unusual for LPs to do the latter, especially when moving into a much moister air mass. LPs were first formally described by Howard Bluestein in the early 1980s although storm chasing scientists noticed them throughout the 1970s. Classic supercells may wither yet maintain updraft rotation as they decay, becoming more like the LP type in a process known as "downscale transition" that also applies to LP storms and this process is thought to be how many LPs dissipate.
LP supercells rarely spawn tornadoes and those that form tend to be weak, small, and high based tornadoes but strong tornadoes have been observed. These storms although generating lesser precipitation amounts and producing smaller precipitation cores can generate huge hail. LPs may produce hail larger than baseballs in clear air where no rainfall is visible. LPs are thus hazardous to people and animals caught outside as well as to storm chasers and spotters. Due to the lack of a heavy precipitation core, LP supercells often exhibit relatively weak radar reflectivity without clear evidence of a hook echo, when in fact they are producing a tornado at the time. LP supercells may not even be recognized as supercells in reflectivity data unless one is trained or experienced on their radar characteristics. This is where observations by storm spotter and storm chasers may be of vital importance in addition to Doppler velocity (and polarimetric) radar data. High-based shear funnel clouds sometimes form midway between the base and the top of the storm, descending from the main Cb (cumulonimbus) cloud. Lightning discharges may be less frequent compared to other supercell types, but on occasion LPs are prolific sparkers, and the discharges are more likely to occur as intracloud lightning rather than cloud-to-ground lightning.
In North America, these storms most prominently form in the semi-arid Great Plains during the spring and summer months. Moving east and southeast, they often collide with moist air masses from the Gulf of Mexico, leading to the formation of HP supercells in areas just to the west of Interstate 35 before dissipating (or coalescing into squall lines) at variable distances farther east. LP supercells have been observed as far east as Illinois and Indiana, however. LP supercells can occur as far north as Montana, North Dakota, and even in the Prairie Provinces of Alberta, Saskatchewan, and Manitoba in Canada. They have also been observed by storm chasers in Australia and Argentina (the Pampas).
LP supercells are quite sought after by storm chasers, because the limited amount of precipitation makes sighting tornadoes at a safe distance much less difficult than with a classic or HP supercell and more so because of the unobscured storm structure unveiled. During spring and early summer, areas in which LP supercells are readily spotted include southwestern Oklahoma and northwestern Texas, among other parts of the western Great Plains.
High Precipitation (HP)
The HP supercell has a much heavier precipitation core that can wrap all the way around the mesocyclone. These are especially dangerous storms, since the mesocyclone is wrapped with rain and can hide a tornado (if present) from view. These storms also cause flooding due to heavy rain, damaging downbursts and weak tornadoes, although they are also known to produce strong to violent tornadoes. They have a lower potential for damaging hail than Classic and LP supercells, although damaging hail is possible. It has been observed by some spotters that they tend to produce more cloud-to-ground and intracloud lightning than the other types. Also, unlike the LP and Classic types, severe events usually occur at the front (southeast) of the storm. The HP supercell is the most common type of supercell in the United States east of Interstate 35, in the southern parts of the provinces of Ontario and Quebec in Canada, and in the central portions of Argentina and Uruguay.
Mini-supercell or low-topped supercell
Whereas classic, HP, and LP refer to different precipitation regimes and mesoscale frontal structures, another variation was identified in the early 1990s by Jon Davies. These smaller storms were initially called mini-supercells but are now commonly referred to as low-topped supercells. These are also subdivided into Classic, HP and LP types.
Severe events associated with a supercell almost always occur in the area of the updraft/downdraft interface. In the Northern Hemisphere, this is most often the rear flank (southwest side) of the precipitation area in LP and classic supercells, but sometimes the leading edge (southeast side) of HP supercells.
While tornadoes are perhaps the most dramatic of these severe events, all are dangerous. High winds caused by powerful outflow can reach over 148 km/h (92 mph) and downbursts can cause tornado-like damage. Flooding is the leading cause of death associated with severe weather.
Note that none of these severe events are exclusive to supercells, although these events are highly predictable once a supercell has formed.
This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: some examples are not supercells. (See the talk page.) (April 2011) (Learn how and when to remove this template message)
The supercell is a global phenomenon, appearing in places all over the world in slightly varying forms.
Some reports suggest that the deluge on 26 July 2005 in Mumbai, India was caused by a supercell when there was a cloud formation 15 kilometres (9.3 mi) high over the city. On this day 944 mm (37.2 in) of rain fell over the city, of which 700 mm (28 in) fell in just four hours. The rainfall coincided with a high tide, which exacerbated conditions.[not in citation given]
Supercells occur commonly from March–May in Bangladesh, West Bengal and the bordering north-eastern Indian states including Tripura. Supercells that produce very high winds with hail and occasional tornadoes are observed in these regions, with them also occurring along the Northern Plains of India and Pakistan. On March 23, 2013, a massive tornado ripped through Brahmanbaria district in Bangladesh, killing 20 and injuring 200.
On April 14, 1999, a severe storm later classified as a supercell hit the east coast of New South Wales. It is estimated that the storm dropped 500,000 tonnes (490,000 long tons; 550,000 short tons) worth of hailstones during its course. At the time it was the most costly disaster in Australia's insurance history, causing an approximated A$2.3 billion worth of damage, of which A$1.7 billion was covered by insurance.
On February 27, 2007, a supercell hit Canberra, dumping nearly thirty-nine centimetres (15 inches) of ice in Civic. The ice was so heavy that a newly built shopping center's roof collapsed, birds were killed in the hail produced from the supercell, and people were stranded. The following day many homes in Canberra were subjected to flash flooding, caused either by storm water infrastructure's inability to cope or through mud slides from cleared land.
On 6 March 2010, supercell storms hit Melbourne. The storms caused flash flooding in the center of the city and tennis ball-sized (10 cm or 4 in) hailstones hit cars and buildings, causing more than $220 million worth of damage, and sparking 40,000-plus insurance claims. In just 18 minutes, 19 cm (7.5 in) of rain fell, causing havoc as streets were flooded and trains, planes and cars were brought to a standstill.
That same month, on March 22, 2010 a supercell hit Perth. This storm was one of the worst in the city's history, causing hail stones of 6 centimetres (2.4 in) in size and torrential rain. The city had its average March rainfall in just seven minutes during the storm. Hail stones caused severe property damage, from dented cars to smashed windows. The storm itself caused more than 100 million dollars in damage.
On November 27, 2014 a supercell hit the inner city suburbs including the CBD of Brisbane. Hailstones up to softball size cut power to 71,000 properties, injuring 39 people, and causing a damage bill of $1 billion AUD. A wind gust of 141 km/h was recorded at Archerfield Airport
An area in South America known as the Tornado Corridor is considered to be the second most frequent location for severe weather, after Tornado Alley in the United States. The region, which covers portions of Argentina, Uruguay, Paraguay, and Brazil during the spring and summer, often experiences strong thunderstorms, which may include tornadoes. One of the first known South American supercell thunderstorms to include tornadoes occurred on September 16, 1816 and destroyed the town of Rojas (240 kilometres (150 mi) west of the city of Buenos Aires).
On September 20, 1926, an EF4 tornado struck the city of Encarnación (Paraguay), killing over 300 people and making it the second deadliest tornado in South America. On 21 April 1970, the town of Fray Marcos in the Department of Florida, Uruguay experienced an F4 tornado that killed 11, the strongest in the history of the nation. January 10, 1973 saw the most severe tornado in the history of South America: The San Justo tornado, 105 km north of the city of Santa Fe (Argentina), was rated EF5, making it the strongest tornado ever recorded in the southern hemisphere, with winds exceeding 400 km/h. On April 13, 1993, in less than 24 hours in the province of Buenos Aires was given the largest tornado outbreak in the history of South America. There were more than 300 tornadoes recorded, with intensities between F1 and F3. The most affected towns were Henderson (EF3), Urdampilleta (EF3) and Mar del Plata (EF2). In December 2000, a series of twelve tornadoes (only registered) affected the Greater Buenos Aires and the province of Buenos Aires, causing serious damage. One of them struck the town of Guernica, and, just two weeks later, in January 2001, an EF3 again devastated Guernica, killing 2 people.
The December 26, 2003 Tornado F3 happened in Cordoba, with winds exceeding 300 km/h, which hit Córdoba Capital, hit just 6 km from the city center, in the area known as CPC Route 20, especially neighborhoods of San Roque and Villa Fabric, killing 5 people and injuring hundreds. The tornado that hit the State of São Paulo in 2004 was one of the most destructive in the state. Destroyed several industrial buildings, with 400 houses, left 1 dead and 11 wounded. The tornado was rated EF3, but many claim it was a tornado EF4. In November 2009, four tornadoes category F1 and F2 reached the town of Posadas (capital of the province of Misiones, Argentina), generating serious damage in the city. Three of the tornado affected area of the airport, causing damage in Barrio Belén. On April 4, 2012, the Gran Buenos Aires was hit by the storm Buenos Aires, with intensities F1 and F2, which left nearly 30 dead in various locations.
On February 21, 2014, in Berazategui (province of Buenos Aires), a tornado of intensity F1 caused material damage including a car was, with two occupants inside, which was elevated a few feet off the ground and flipped over asphalt, both the driver and his passenger were slightly injured. The tornado caused no fatalities. The severe weather that occurred on Tuesday 8/11 had features rarely seen in such magnitude in Argentina. In many towns of La Pampa, San Luis, Buenos Aires and Cordoba, intense hail stones fell up to 6 cm in diameter. On Sunday December 8, 2013, severe storms took place in the center and the coast. The most affected province was Córdoba, storms and supercells type "bow echos" also developed in Santa Fe and San Luis.
In 2009, on the night of Monday May 25, a supercell formed over Belgium. It was described by Belgian meteorologist Frank Deboosere as "one of the worst storms in recent years" and caused much damage in Belgium - mainly in the provinces of East Flanders (around Ghent), Flemish Brabant (around Brussels) and Antwerp. The storm occurred between about 1:00am and 4:00am local time. An incredible 30,000 lightning flashes were recorded in 2 hours - including 10,000 cloud-to-ground strikes. Hailstones up to 6 centimetres (2.4 in) across were observed in some places and wind gusts over 90 km/h (56 mph); in Melle near Ghent a gust of 101 km/h (63 mph) was reported. Trees were uprooted and blown onto several motorways. In Lillo (east of Antwerp) a loaded goods train was blown from the rail tracks.
On August 18, 2011, the rock festival Pukkelpop in Kiewit, Hasselt (Belgium) may have been seized by a supercell with mesocyclone around 18:15. Tornado-like winds were reported, trees of over 30 centimetres (12 in) diameter were felled and tents came down. Severe hail scourged the campus. Five people reportedly died and over 140 people were injured. One more died a week later. The event was suspended. Buses and trains were mobilised to bring people home.
On June 28, 2012, three supercells affected England. Two of them formed over the Midlands, producing hailstones reported to be larger than golfballs, with conglomerate stones up to 10 cm across. Burbage in Leicestershire saw some of the most severe hail. Another supercell produced a tornado near Sleaford, in Lincolnshire.
A third supercell affected the North East region of England. The storm struck the Tyneside area directly and without warning during evening rush hour causing widespread damage and travel chaos, with people abandoning cars and being trapped due to lack of public transport. Flooded shopping malls were evacuated, Newcastle station was shut, as was the Tyne & Wear Metro, and main road routes were flooded leading to massive tailbacks. 999 land line services were knocked out in some areas and the damage ran to huge amounts only visible the next day after water cleared. Many parts of County Durham and Northumberland were also affected, with thousands of homes across the North East left without power due to lightning strikes. Lightning was seen to hit the Tyne Bridge (Newcastle).
In Europe, the mini-supercell, or low-topped supercell, is very common, especially when showers and thunderstorms develop in cooler polar air masses with a strong jet stream above, especially in the left exit-region of a jetstreak.
The Tornado Alley is a region of the central United States where severe weather is common, particularly tornadoes. Supercell thunderstorms can affect this region at any time of the year, but they are most common in the spring. Tornado watches and warnings are frequently necessary in the spring and summer. Most places from the Great Plains to the East Coast of the United States and north as far as the Canadian Prairies, the Great Lakes region, and the St. Lawrence River will experience one or more supercells each year.
A massive tornado outbreak on May 3, 1999 spawned an F5 tornado in the area of Oklahoma City that had the highest recorded winds on Earth. This outbreak spawned over 66 tornadoes in Oklahoma alone. On this day throughout the area of Oklahoma, Kansas and Texas, over 141 tornadoes were produced. This outbreak resulted in 50 fatalities and 895 injuries.
A series of tornadoes, which occurred in May 2013, caused severe devastation to Oklahoma City in general. The first tornado outbreaks occurred on May 18 to May 21 when a series of tornadoes hit. From one of the storms developed a tornado which was later rated EF5, which traveled across parts of the Oklahoma City area, causing a severe amount of disruption. This tornado was first spotted in Newcastle. It touched the ground for 39 minutes, crossing through a heavily populated section of Moore. Winds with this tornado peaked at 210 miles per hour (340 km/h). Twenty-three fatalities and 377 injuries were caused by the tornado. Sixty-one other tornadoes were confirmed during the storm period. Later on in the same month, on the night of May 31, 2013, another eight deaths were confirmed from what became the widest tornado on record which hit El Reno, Oklahoma, one of a series of tornadoes and funnel clouds which hit nearby areas.
South Africa witnesses several supercell thunderstorms each year with the inclusion of isolated tornadoes. On most occasions these tornadoes occur in open farmlands and rarely cause damage to property, as such many of the tornadoes which do occur in South Africa are not reported. The majority of supercells develop in the central, northern, and north eastern parts of the country. The Free State, Gauteng, and Kwazulu Natal are typically the provinces where these storms are most commonly experienced, though supercell activity is not limited to these provinces. On occasion, hail reaches sizes in excess of golf balls, and tornadoes, though rare, also occur.
On 6 May 2009, a well-defined hook echo was noticed on local South African radars, along with satellite imagery this supported the presence of a strong supercell storm. Reports from the area indicated heavy rains, winds and large hail.
On October 2, 2011, two devastating tornadoes tore through two separate parts of South Africa on the same day, hours apart from each other. The first, classified as an EF2 hit Meqheleng, the informal settlement outside Ficksburg, Free State which devastated shacks and homes, uprooted trees, and killed one small child. The second, which hit the informal settlement of Duduza, Nigel in the Gauteng province, also classified as EF2 hit hours apart from the one that struck Ficksburg. This tornado completely devastated parts of the informal settlement and killed two children, destroying shacks and RDP homes.
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Fortran 90 for Beginners
Download free Fortran 90 Programming language course material, tutorial training, a PDF file by Tadziu Hoffmann & Joachim Puls.
Kotlin tutorial in PDF
This Kotlin pdf tutorial will teach you how to develop with Kotlin on Android Studio as part of the mobile development for Android platforms.
Kotlin Programming Language
This PDF tutorial is intended to beginners to help them understand the basics of Kotlin programming language. Download Free training document under 52 pages. | <urn:uuid:f602debb-7883-4348-b05b-dea9e4df0453> | 2.9375 | 378 | Product Page | Software Dev. | 39.889438 | 95,569,754 |
Below excerpts are from a July 16th editorial in Newsday. The full article is available here.
A federal jury has deemed East Hampton Town responsible for the erosion of beach in front of nearly a dozen residential properties in Montauk…
The jetties were built by the Army Corps of Engineers, but the town, which ironically has one of the region’s more enlightened coastal philosophies, is on the hook because it technically owns the structures.
UC San Diego biologists who examined the biological impact of replenishing eroded beaches with offshore sand found that such beach replenishment efforts could have long-term negative impacts on coastal ecosystems.
The scientists, who studied the effects of beach replenishment efforts on the abundance of intertidal invertebrates at eight different beaches in San Diego County, discovered that the movement of sand onto those beaches resulted in a more than twofold reduction in the abundance of intertidal invertebrates after 15 months.
“Such reductions may have far reaching consequences for sandy beach ecosystems,” the researchers warn in their paper, “as community declines can reduce prey availability for shorebirds and fish.”
Read the full article by clicking here. | <urn:uuid:b05ceb8a-5f02-408f-97a0-7936b740d162> | 2.875 | 241 | Truncated | Science & Tech. | 21.216579 | 95,569,765 |
For discussing the functions of different structures of all organisms.
Moderators: honeev, Leonid, amiradm, BioTeam
- Posts: 43
- Joined: Thu Sep 14, 2006 1:15 am
What's the relationship between 'urea' and 'urine'? Is that much urea forms urine? Please tell me, thanks.
- Inland Taipan
- Posts: 6832
- Joined: Thu Mar 03, 2005 10:18 pm
- Location: Romania(small and unimportant country)
Kidding right? Look up what urine is made of on wikipedia or google or anything...
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
- Posts: 7
- Joined: Thu Feb 15, 2007 4:14 pm
Urea, also known as uric acid, is a fundamental component of urine.
- Posts: 32
- Joined: Thu Aug 04, 2005 6:52 pm
- Location: Romania
urea and uric acid are two very different things. Urea is a product of protein catabolism while uric acid is a product of nitrous bases catabolism. So different formulas different origin. Similar name.
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- Joined: Thu Mar 02, 2006 5:29 pm
- Location: New York, USA
Urea and uric acid can both be products of protein breakdown - whole groups of animals differ by which final product they excrete.
Who is online
Users browsing this forum: No registered users and 2 guests | <urn:uuid:36bf1ccb-bc1a-483a-ad08-4633f5889591> | 2.71875 | 351 | Comment Section | Science & Tech. | 67.442456 | 95,569,769 |
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Found most commonly in these habitats: 47 times found in rainforest, 14 times found in disturbed forest, 18 times found in lowland rainforest, 7 times found in tropical wet forest, 8 times found in Primary forest, 6 times found in primary rainforest, 8 times found in tropical dry forest, 6 times found in tropical rainforest, 7 times found in Cerca de los Laboratorios, 3 times found in wet forest, ...
Found most commonly in these microhabitats: 76 times Malaise trap, 6 times under stone, 12 times ex sifted leaf litter, 11 times ex rotten log, 0 times Pitfall trap, 6 times SCH, 1 times ex rotting log, 7 times Claro, 5 times Ground nest, 6 times Sura, 5 times STR, ...
Collected most commonly using these methods: 84 times M, 56 times Malaise, 12 times Malaise trap, 6 times search, 7 times MaxiWinkler, 4 times Winkler, 3 times MW 50 sample transect, 5m, 2 times at light, 2 times Blacklight, 3 times Hand, 2 times hand collected, ...
Elevations: collected from 10 - 2230 meters, 548 meters average
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Antweb is funded from private donations and from grants from the National Science Foundation, DEB-0344731, EF-0431330 and DEB-0842395. c:2 | <urn:uuid:e6e1adc8-62cf-4274-9119-6ca2c1a3e39e> | 2.90625 | 401 | Knowledge Article | Science & Tech. | 65.197912 | 95,569,779 |
Invasive Weeds Could Shed Light on Climate-Coping
News Mar 20, 2013
Understanding their well-honed coping mechanisms could inform strategies for ecological management, says a Cornell crop and soil researcher.
While other species are expected to suffer from environmental fluctuations, changes in temperature may help invasive weeds expand their ranges. Many weeds are capable of relatively rapid genetic change as well, further enhancing their ability to colonize new areas.
The findings stem from the study, "Predicting Weed Invasion in Canada Under Climate Change: Evaluating Evolutionary Potential," published in the Canadian Journal of Plant Science (92:2012) by weed ecologist Antonio DiTommaso, associate professor of crop and soil sciences and the Richard C. Call, Director of Agricultural Sciences, and biologist David Clements of Trinity Western University.
"The standard modeling approach treats plants like static entities," DiTommaso said. "But changes in weed distributions may also reflect evolutionary change in the plants themselves. We've already seen them change in response to human influences such as farming practices."
For many years, scientists thought weeds would not develop herbicide resistance on a comparable scale to the insecticide resistance that emerged in the 1950s and 1960s; now, herbicide resistance is widespread, showing weeds have a strong potential to evolve in the presence of intense selection pressure, DiTommaso said.
In the study, the researchers looked at four different weed species -- Himalayan balsam, velvetleaf, Japanese knotweed and johnsongrass -- that were expanding their ranges northward within North America. They observed evidence for potential evolutionary responses to climate change in each species, despite population genetic differences.
DiTommaso said that the study's findings will help address the spread of weeds and the economic and ecological damage it could cause. He's also intrigued by what weeds can teach us about inhabiting and restoring degraded areas.
"Most people define weeds simply as plants out of place, but from an ecological point of view they're just especially good at colonizing disturbed sites and staying abundant under repeated disturbance," he said. "Ecologically, they're just survivors."
DiTommaso said weeds are also are essential to agriculture and human well-being, protecting and restoring the soil and providing surgery when areas are torn up for fields, burned or otherwise altered.
"Weeds are pioneers that initiate a process that can eventually restore whatever forest, savanna, prairie or other ecosystem was native there," he said.
Still, weeds are the most costly category of agricultural pests and cause more yield loss worldwide than insect pests, crop pathogens or warm-blooded pests.
"No year goes by when you don't have to deal with them -- they're like taxes or death. Diseases and pests can come in one year and go the next, but weeds are constant," he said.
DiTommaso also pointed out that weeds are considered the main production constraint for the rapidly expanding organic agricultural sector.
"We need to ... develop and implement safe, effective and sustainable strategies for dealing with [weeds]. But we should also consider what it is that allows these wild plants to be so resilient," he said.
"Perhaps some of the strategies that make them troublesome could help us better design cropping systems, especially in light of predicted climate change."
Evolution Does Repeat Itself After AllNews
A team of University of Konstanz biologists led by Professor Axel Meyer shows that evolutionary outcomes can be predicted: In a new publication in the journal “Evolution Letters”, they are able to identify some of the factors that contribute to recurrent patterns of diversity and similarity in cichlids. | <urn:uuid:f17da3a2-d225-44cd-9281-74a8bd07a63f> | 3.359375 | 756 | News Article | Science & Tech. | 25.643274 | 95,569,780 |
You are required to implement a calculator Android activities. The way the Calculator works is similar to the Windows calculator. The user types the first number using the keypad buttons of the calculator, presses an operation, then the user types the second number using the keypad buttons of the calculator (no keyboard input required). If it clicks the ‘=’ it performs the operation. If it clicks an operation button, it performs the previous calculation, shows the result of the first calculation and waits for the second operand of the new operation. When the user presses delete, it deletes the last number that was pressed to create a number (e.g., if the number is 123, after pressing delete, the number now is 12).
• You are required to implement four operations (+, -, *, /)
• The numbers must be input by using the buttons
• Check for divisions by 0. An indication that an error has happened should appear if the user tries to divide by 0. If so, the memory of the calculator is cleared (it performs the same operation as if the user has clicked the Clear button).
25 freelancer đang chào giá trung bình ₹1102 cho công việc này
Hi there, I do Android and I would like to do this project if given the opportunity. I can create the calculator based on the requirements you have posted. Let me know if you are interested.
hey sir i'm goood in java and android studio i make calculator like this message me to see it and i can do what you want and when i complete your project you can check and accept
Hey there. I have once created this type of calculator app for my college project i still have the code and working app in my mobile. Contact me if you want to get it done! Regards Noraiz. | <urn:uuid:5d378d61-8f5b-4166-9d90-3979cc172b7b> | 2.515625 | 390 | Tutorial | Software Dev. | 56.874118 | 95,569,794 |
An Introduction to Programming in Emacs Lisp
by Robert J. Chassell
Publisher: Free Software Foundation, Inc. 2002
Number of pages: 314
This is an introduction to Programming in Emacs Lisp, for people who are not programmers. Although Emacs Lisp is usually thought of in association only with Emacs, it is a full computer programming language. You can use Emacs Lisp as you would any other programming language. This introduction to Emacs Lisp is designed to get you started: to guide you in learning the fundamentals of programming, and more importantly, to show you how you can teach yourself to go further.
Home page url
Download or read it online for free here:
by E.C. Berkeley, D.G. Bobrow - The MIT Press
LISP is a remarkable and powerful language, because not only does it govern the operation of a computer, but also it is a mathematical language of great power for processing processes in mathematics, logic, and symbol manipulation in general.
by David J. Cooper, Jr. - Franz Inc.
The purpose of this book is to showcase the features of Common Lisp, and to give you a quick-start guide for using Common Lisp as a development environment. This guide gives you all the tools you need to begin writing Lisp applications.
by Daniel Holden - buildyourownlisp.com
In this book you'll learn the C programming language, and at the same time learn how to build your very own programming language, a minimal Lisp, in under 1000 lines of code. This book is not suitable as a first programming language book ...
by Robert A. MacLachlan
This text documents internal details of the CMU Common Lisp compiler and run-time system. CMU Common Lisp is a public domain implementation of Common Lisp that runs on Unix workstations. It provides some useful information on the CMUCL compiler. | <urn:uuid:938e6a29-5b72-4aed-950f-6d42b167d750> | 3.078125 | 383 | Product Page | Software Dev. | 56.182732 | 95,569,810 |
Shifting ice a problem for Antarctica penguins
Shifting sea ice around Antarctica is already disrupting penguin colonies as the world's climate warms, according to a new report by a team of polar scientists.
The researchers looked at the complex relationship between emperor and Adelie penguins and their changing habitats and studied how a projected temperature increase in coming decades of 2 degrees Celsius, or 3.6 Fahrenheit, might affect the way the animals build nests, find food and raise their young.
Emperor penguins - the largest of all the awkward birds that thrive only in cold climates - are the most severely threatened by oncoming changes, the report says. The birds live, lay eggs and raise chicks on solid sea ice, but when that "fast ice" thins and breaks up as temperatures rise, their habitat shrinks, the report notes.
But the slightly smaller and more agile Adelie penguins are also being forced to shift their nesting grounds when increased snowfalls cover the rocky terrain where they build their nests and have raised their young for millennia, the researchers say.
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At the very least, the report states, the penguins' range stands to be compacted, "increasing susceptibility to the effects of warming."
The study was led by David Ainley, a penguin specialist with a Los Gatos ecological consulting firm who spent 10 months on the snowbound continent. The research was supported primarily by the National Science Foundation and published by the Ecological Society of America.
Faster warming expected
The Intergovernmental Panel in Climate Change has forecast that, by the end of this century, the world's climate will have warmed by 2 degrees Celsius. But Ainley and his colleagues calculate that the 2-degree "benchmark" will be reached between 15 and 42 years from now.
The winds of the "polar jet stream" that sweep around the continent, Ainley said in an interview, have become stronger and are causing greater upwelling of ocean currents in many areas along the coast. That means large areas of thick ice are becoming thinner, while areas of open water - known as "polynyas" - are growing larger.
Those polynyas are critical to the lives of the penguins because, the report says, "they reduce the commuting time and energy expenditure between colony and food supply" - namely, fish. But the report adds, "the factors that bring increased polynyas also bring decreased sea ice thickness, a direct problem for emperor penguins."
The most deadly effect of the changes was already visible 30 years ago among emperor penguins on Adelie Land, along Antarctica's east coast, where the 2005 Academy Award-winning documentary "The March of the Penguins" was filmed, Ainley said.
Winds there, at Pointe Géologie, swept the solid ice where female penguins laid their eggs and the male emperors kept the eggs warm and reared the chicks. Under those fierce winds, the thinned and unstable ice broke off. Though the males could swim, the chicks drowned. Within a decade, the emperor colony's population dropped from 6,000 pairs to 3,000, Ainley said.
Another decline forecast
In his group's report, the scientists foresee another significant population decline among emperor Penguins at Pointe Géologie in the next few decades.
"There's been a transformation in the last couple of decades, particularly on the other side of the continent along the Antarctic peninsula where the disappearance of sea ice has been dramatic," Ainley said.
The report warns that increased snowfall caused by warming temperatures "causes problems, as Adelie penguins cannot find nesting stones or snow-free nesting habitat."
In addition, because Adelie penguins must dive for their fish beneath pack ice, the birds must swim farther from land for their food as those broad floes melt - another threat to the survival of their colonies, Ainley said. | <urn:uuid:35bdffef-e6f5-4179-9aab-3277e0ad5724> | 3.203125 | 988 | News Article | Science & Tech. | 32.750081 | 95,569,832 |
For astronomer Alexander von Boetticher, false positives in data are actually a good thing.
That’s how von Boetticher and his colleagues at the University of Cambridge discovered the smallest star ever measured. The star showed up in data from a British-led mission known as the Wide Angle Search for Planets, or WASP. WASP looks for potential exoplanets by looking for dimming in the brightness of stars, a signal that an object is passing in front and blocking the light. The mission has detected dozens of planets this way. Sometimes, the source of the dimming turns out to be something else entirely. “Every now and then, instead of finding an exoplanet orbiting some star, it actually finds a very small star that’s orbiting a star,” von Boetticher said.
The newly discovered star, known as EBLM J0555-57Ab, is located about 600 light-years away and is slightly bigger than Saturn. The star is likely as small as stars get; it has just enough mass to fuse hydrogen into helium in its core. The process is known as nuclear fusion, and it’s what makes stars stars. Any smaller, and EBLM J0555-57Ab would no longer be able to sustain this reaction. It would become a brown dwarf, a substellar object that emits mostly infrared, not visible, light. The discovery is described in a recent paper in the journal Astronomy & Astrophysics.
The newly discovered star is one half of a binary system, a common configuration in which two stars closely orbit each other. The nature of this system helps researchers make precise measurements of the smaller star, von Boetticher said. In a binary system, the smaller object exerts a gravitational pull that makes the larger object move back and forth ever so slightly. Scientists can observe this wobbling effect through telescopes and use it to determine the properties of the smaller object, like its mass and radius. These figures can help determine the nature of the object. “If it’s really heavy and it’s really small, it’s likely to be a star,” von Boetticher said. “If it’s light and small, then it’s likely a planet.”
Small stars like EBLM J0555-57Ab are difficult to observe directly, even with powerful telescopes, because they emit so little light. “But when they orbit in a binary system, then you can use indirect detection methods,” von Boetticher said.
Small stars make good candidates in the search for exoplanets, von Boetticher said. Red dwarfs, smaller and cooler than stars like our sun, are the most common type of star in the universe. When you’re looking for exoplanets—and potentially habitable ones—the more star candidates, the better. The transit of a planet in front of a star—the phenomenon that WASP looks out for—is also more pronounced and easier to spot when the star is smaller in size. Earlier this year, scientists discovered seven Earth-sized planets orbiting a red dwarf called TRAPPIST-1, located about 40-light years away. Some of the planets orbit in the star system’s habitable zone, where conditions for liquid water could arise, but some scientists think TRAPPIST-1 may emit enough ultraviolet radiation to wipe out their atmospheres.
The discovery of EBLM J0555-57Ab illustrates the variety of stars in the universe. From our vantage point on Earth, all stars look the same—tiny pinpoints of light against a dark sky. That picture doesn’t do justice to the stars out there, which come in all kinds of different sizes, from dwarfs the size of Saturn to hypergiants hundreds of times larger than our sun.
“I think many people know that stars can be really, really big, much larger than the sun, but not many people are aware that they can also be as small as some of the large planets in our solar system,” von Boetticher said.
We want to hear what you think. Submit a letter to the editor or write to firstname.lastname@example.org. | <urn:uuid:c93d7443-0d46-4e51-9514-b2c5e54486da> | 4.34375 | 884 | News Article | Science & Tech. | 54.089875 | 95,569,833 |
A Limiting Distribution (also called an asymptotic distribution) is the hypothetical distribution — or convergence — of a sequence of distributions. As it is hypothetical, it isn’t a distribution in the general sense of the word. The asymptotic distribution theory attempts to find a limiting distribution to a series of distributions.
Some of these distributions are well-known. For example, the sampling distribution of the t-statistic will converge to a standard normal distribution if the sample size is large enough. Sometimes the limiting probability distribution can be found by studying the behavior of CDFs or PDFs. Theorems like Slutsky’s can also be used to explore convergence in probability distributions.
Why do we need to find hypothetical distributions?
In basic statistics, the process is to take a random sample of observations and fit that data to a known distribution like the normal distribution or t distribution. When you fit data to a model, it isn’t an exact science. Fitting data exactly to a known distribution is usually very difficult in real life due to limited sample sizes, resulting in a “best guess” based on what you know (or what your software knows) about behavior of large sample statistics. The limiting/asymptotic distribution can be used on small, finite samples to approximate the true distribution of a random variable–one that you would find if the sample size was large enough.
Limiting probability distributions are important when it comes to finding appropriate sample sizes. When a sample size is large enough, then a statistic’s distribution will form a limiting distribution (assuming such a distribution exists).
Limiting Distribution and the CLT
The Central Limit Theorem (CLT) uses the limit concept to describe the behavior of sample means.
The CLT tells us that the sampling distribution of the sampling means approaches a normal distribution as the sample size increases — no matter what the shape of the population distribution. What this is saying is, if you take more samples (especially large ones) the graph of the sample means will look more and more like a normal distribution, even if your graph is skewed or otherwise non-normal. In other words, the Limiting Distribution for a large set of sample means is the Normal Distribution.
Epps (2013) gives the term a more formal framework:
Suppose Xn is a random sequence with cdf Fn(Xn and X is a random variable with cdf F(x).
If Fn converges to F as n > ∞ (for all points where F(x) is continuous), then the distribution of xn converges to x. This distribution is called the limiting distribution of xn.
In simpler terms, we can say that the limiting probability distribution of Xn is the limiting distribution of some function of Xn.
Limiting Distribution and Markov Chains
One of the more common areas where the term Limiting Distribution shows up is in the study of Markov Chains. As time n > ∞, a Markov chain has a limiting distribution π = (πj)j∈s. A value for π can be found by solving a series of linear equations.
Epps, T. (2013). Probability and Statistical Theory for Applied Researchers.
If you prefer an online interactive environment to learn R and statistics, this free R Tutorial by Datacamp is a great way to get started. If you're are somewhat comfortable with R and are interested in going deeper into Statistics, try this Statistics with R track.Comments? Need to post a correction? Please post on our Facebook page. | <urn:uuid:a50d1d20-7dff-4313-83d0-8a275b4b8f1f> | 3.859375 | 739 | Tutorial | Science & Tech. | 45.546458 | 95,569,873 |
How many differently shaped rectangles can you build using these equilateral and isosceles triangles? Can you make a square?
Experimenting with variables and friezes.
This problem is based on the idea of building patterns using transformations.
How many different transformations can you find made up from combinations of R, S and their inverses? Can you be sure that you have found them all?
This article looks at the importance in mathematics of representing places and spaces mathematics. Many famous mathematicians have spent time working on problems that involve moving and mapping. . . .
Have you ever noticed how mathematical ideas are often used in patterns that we see all around us? This article describes the life of Escher who was a passionate believer that maths and art can be. . . .
Jenny Murray describes the mathematical processes behind making patchwork in this article for students.
Sort the frieze patterns into seven pairs according to the way in which the motif is repeated.
Does changing the order of transformations always/sometimes/never produce the same transformation?
Explore the effect of reflecting in two intersecting mirror lines.
See the effects of some combined transformations on a shape. Can you describe what the individual transformations do?
Patterns that repeat in a line are strangely interesting. How many types are there and how do you tell one type from another?
Why not challenge a friend to play this transformation game?
This task develops knowledge of transformation of graphs. By framing and asking questions a member of the team has to find out which mathematical function they have chosen.
A gallery of beautiful photos of cast ironwork friezes in Australia with a mathematical discussion of the classification of frieze patterns.
Proofs that there are only seven frieze patterns involve complicated group theory. The symmetries of a cylinder provide an easier approach.
Explore the effect of reflecting in two parallel mirror lines.
Here is a solitaire type environment for you to experiment with. Which targets can you reach?
An introduction to groups using transformations, following on from the October 2006 Stage 3 problems.
Scientist Bryan Rickett has a vision of the future - and it is one in which self-parking cars prowl the tarmac plains, hunting down suitable parking spots and manoeuvring elegantly into them.
A cylindrical helix is just a spiral on a cylinder, like an ordinary spring or the thread on a bolt. If I turn a left-handed helix over (top to bottom) does it become a right handed helix?
Draw all the possible distinct triangles on a 4 x 4 dotty grid. Convince me that you have all possible triangles.
What would be the smallest number of moves needed to move a Knight from a chess set from one corner to the opposite corner of a 99 by 99 square board?
Explore the effect of combining enlargements.
Triangles are formed by joining the vertices of a skeletal cube. How many different types of triangle are there? How many triangles altogether?
With one cut a piece of card 16 cm by 9 cm can be made into two pieces which can be rearranged to form a square 12 cm by 12 cm. Explain how this can be done.
Blue Flibbins are so jealous of their red partners that they will not leave them on their own with any other bue Flibbin. What is the quickest way of getting the five pairs of Flibbins safely to. . . .
Can you dissect a square into: 4, 7, 10, 13... other squares? 6, 9, 12, 15... other squares? 8, 11, 14... other squares?
Show how this pentagonal tile can be used to tile the plane and describe the transformations which map this pentagon to its images in the tiling.
Can you find a way to turn a rectangle into a square? | <urn:uuid:88a94b86-a6fa-43b9-8b5b-6808ac93a7b6> | 3.5 | 797 | Content Listing | Science & Tech. | 58.209743 | 95,569,915 |
|Did you know ...||Search Documentation:|
|ISO Input and Output Streams|
The predicates described in this section provide ISO compliant I/O, where streams are explicitly created using the predicate open/3. The resulting stream identifier is then passed as a parameter to the reading and writing predicates to specify the source or destination of the data.
This schema is not vulnerable to filename and stream ambiguities as well as changes to the working directory. On the other hand, using the notion of current-I/O simplifies reusability of code without the need to pass arguments around. E.g., see with_output_to/2.
SWI-Prolog streams are, compatible with the ISO standard, either input or output streams. To accommodate portability to other systems, a pair of streams can be packed into a stream-pair. See stream_pair/3 for details.
SWI-Prolog stream handles are unique symbols that have no syntactical
representation. They are written as
which is not valid input for read/1.
They are realised using a blob of type
stream (see blob/2
and section 12.4.7).
appendopens the file for writing, positioning the file pointer at the end. Mode
updateopens the file for writing, positioning the file pointer at the beginning of the file without truncating the file. Stream is either a variable, in which case it is bound to an integer identifying the stream, or an atom, in which case this atom will be the stream identifier.86New code should use the
alias(Alias)option for compatibility with the ISO standard.
SWI-Prolog also allows SrcDest to be a term
In this form, Command is started as a child process and if
write, output written to Stream
is sent to the standard input of Command. Viso versa, if Mode
read, data written by Command to the standard
output may be read from Stream. On Unix systems, Command
is handed to popen() which hands it to the Unix shell. On Windows, Command
is executed directly. See also process_create/3
If SrcDest is an IRI, i.e., starts with
://, where <scheme>
is a non-empty sequence of lowercase ASCII letters open/3,4
calls hooks registered by register_iri_scheme/3.
Currently the only predefined IRI scheme is
access to the resource database. See
The following Options are recognised by open/4:
?- open(data, read, Fd, [alias(input)]). ..., read(input, Term), ...
write. See also stream_property/2 and especially section 22.214.171.124 for a discussion of this feature.
full(default) defines full buffering,
linebuffering by line, and
falseimplies the stream is fully unbuffered. Smaller buffering is useful if another process or the user is waiting for the output as it is being produced. See also flush_output/[0,1]. This option is not an ISO option.
true(default), the stream is closed on an abort (see abort/0). If
false, the stream is not closed. If it is an output stream, however, it will be flushed. Useful for logfiles and if the stream is associated to a process (using the
updatemode. Currently, List is a list of atoms that describe the permissions of the created file.87Added after feedback from Joachim Shimpf and Per Mildner. Defined values are below. Not recognised values are silently ignored, allowing for adding platform specific extensions to this set.
Note that if List is empty, the created file has no
associated access permissions. The create options map to the POSIX mode
option of open(), where
read map to 0444,
to 0222 and
execute to 0111. On POSIX systems, the final
permission is defined as (mode &
textis derived from the Prolog flag encoding. For
binarystreams the default encoding is
octet. For details on encoding issues, see section 2.19.1.
eof_code, which makes get0/1 and friends return -1, and read/1 and friends return the atom
end_of_file. Repetitive reading keeps yielding the same result. Action
eof_code, but repetitive reading will raise an error. With action
reset, Prolog will examine the file again and return more data if the file has grown.
none, which does not lock the file. The value
sharedmeans other processes may read the file, but not write it. The value
exclusivemeans no other process may read or write the file.
Locks are acquired through the POSIX function fcntl() using the
F_SETLKW, which makes a blocked call wait for the lock to
be released. Please note that fcntl() locks are advisory and
therefore only other applications using the same advisory locks honour
your lock. As there are many issues around locking in Unix, especially
related to NFS (network file system), please study the fcntl() manual
page before trusting your locks!
lock option is a SWI-Prolog extension.
text(default), Prolog will write a text file in an operating system compatible way. Using type
binarythe bytes will be read or written without any translation. See also the option
true), the open call returns immediately with an exception if the file is locked. The exception has the format
permission_error(lock, source_sink, SrcDest).
reposition is not supported in SWI-Prolog.
All streams connected to a file may be repositioned.
/dev/null) or exploit the counting properties. The initial encoding of Stream is
utf8, enabling arbitrary Unicode output. The encoding can be changed to determine byte counts of the output in a particular encoding or validate if output is possible in a particular encoding. For example, the code below determines the number of characters emitted when writing Term.
write_length(Term, Len) :- open_null_stream(Out), write(Out, Term), character_count(Out, Len0), close(Out), Len = Len0.
If the closed stream is the current input, output or error stream, the stream alias is bound to the initial standard I/O streams of the process. Calling close/1 on the initial standard I/O streams of the process is a no-op for an input stream and flushes an output stream without closing it.88This behaviour was defined with purely interactive usage of Prolog in mind. Applications should not count on this behaviour. Future versions may allow for closing the initial standard I/O streams.
close(Stream, [force(true)])as the only option. Called this way, any resource errors (such as write errors while flushing the output buffer) are ignored.
false. See also open/4.
true, a BOM (Byte Order Mark) was detected while opening the file for reading, or a BOM was written while opening the stream. See section 126.96.36.199 for details.
F_SETFDusing the flag
FD_CLOEXECon Unix and (negated)
past. See also at_end_of_stream/[0,1].
error. See open/4 for details.
appendand the SWI-Prolog extension
dos, text streams will emit
\rfrom input streams. Default depends on the operating system.
error(throw an I/O error exception),
\...\escape code) or
&#...;XML character entity). The initial mode is
prologfor the user streams and
errorfor all other streams. See also section 2.19.1 and set_stream/2.
trueif the stream is associated with a terminal. See also set_stream/2.
ignore. The latter is intended to deal with service processes for which the standard output handles are not connected to valid streams. In these cases write errors may be ignored on
if the stream refers to some other object. Mode is one of
Stream-pairs can be used by all I/O operations on streams, where the operation selects the appropriate member of the pair. The predicate close/1 closes the still open streams of the pair.89As of version 7.1.19, it is allowed to close one of the members of the stream directly and close the pair later. The output stream is closed before the input stream. If closing the output stream results in an error, the input stream is still closed. Success is only returned if both streams were closed successfully.
position(Pos)property. See also seek/4.
position(Pos)property. Field is one of
byte_count. See also line_count/2, line_position/2, character_count/2 and byte_count/2.90Introduced in version 5.6.4 after extending the position term with a byte count. Compatible with SICStus Prolog.
eof, indicating positioning relative to the start, current point or end of the underlying object. NewLocation is unified with the new offset, relative to the start of the stream.
Positions are counted in `units'. A unit is 1 byte, except for text files using 2-byte Unicode encoding (2 bytes) or wchar encoding (sizeof(wchar_t)). The latter guarantees comfortable interaction with wide-character text objects. Otherwise, the use of seek/4 on non-binary files (see open/4) is of limited use, especially when using multi-byte text encodings (e.g. UTF-8) or multi-byte newline files (e.g. DOS/Windows). On text files, SWI-Prolog offers reliable backup to an old position using stream_property/2 and set_stream_position/2. Skipping N character codes is achieved calling get_code/2 N times or using copy_stream_data/3, directing the output to a null stream (see open_null_stream/1). If the seek modifies the current location, the line number and character position in the line are set to 0.
If the stream cannot be repositioned, a
is raised. If applying the offset would result in a file position less
than zero, a
domain_error is raised. Behaviour when seeking
to positions beyond the size of the underlying object depend on the
object and possibly the operating system. The predicate seek/4
is compatible with Quintus Prolog, though the error conditions and
signalling is ISO compliant. See also stream_property/2
eof_actiononly applies to the read stream,
representation_errorsonly applies to the write stream and trying to set
line_positionon a pair results in a
permission_errorexception. See also stream_property/2 and open/4.
set_stream(S, current_input)is the same as set_input/1, and by setting the alias of a stream to
user_input, etc., all user terminal input is read from this stream. See also interactor/0.
close_on_execproperty. See stream_property/2.
bomcauses the stream to check whether the current character is a Unicode BOM marker. If a BOM marker is found, the encoding is set accordingly and the call succeeds. Otherwise the call fails.
detect. It will be set to
\rcharacter was removed.
timeout_error(read, Stream), _)
binary. See also open/4 and the
encodingproperty of streams. Switching to
binarysets the encoding to
octet. Switching to
textsets the encoding to the default text encoding.
set_stream(S, record_position(true))resets the position the start of line 1.
current_inputof the calling thread. Out becomes
current_output. If Error equals Out an unbuffered stream is associated to the same destination and linked to
user_error. Otherwise Error is used for
user_error. Output buffering for Out is set to
lineand buffering on Error is disabled. See also prolog/0 and set_stream/2. The clib package provides the library
library(prolog_server), creating a TCP/IP server for creating an interactive session to Prolog. | <urn:uuid:fc133b69-6ca5-4f17-a80c-1fd69cb92c41> | 2.84375 | 2,655 | Documentation | Software Dev. | 55.583155 | 95,569,930 |
Mesoscopic physics has started with the study of various kinds of interference effects of the electronic wave, but the features of electrons as a particle also show up in various interesting phenomena. For example, consider a small tunnel junction connected to an electrical source of constant voltage V (Fig. 1.6.1a). Suppose an electron tunnels from one electrode to the other through the insulator between them. If the junction is very small, its capacitance is small too, unless the insulator between the electrodes is extremely thin. Then the charging energy e 2/2C can be as large as temperature times the Boltzmann constant, and is not negligible. Therefore, the tunneling is not realized unless the voltage V is large enough for this energy to be compensated by the energy eV.
KeywordsFermi Energy Charge Energy Differential Resistance Coulomb Blockade Mesoscopic System
Unable to display preview. Download preview PDF.
- 2.M.H. Devoret and H. Grabert, Single Charge Tunneling. Coulomb Blockade Phenomena inNanostructures (Proceedings of a NATO Advanced Study Institute, Les Houches, 1991 (Plenum, London, 1992 ), p. 1Google Scholar
- 5.C. Kittel, Quantum Theory of Solids (John Wiley & Sons), p. 190Google Scholar
- 10.J. Friedel, Phil. Mag. 43 (1952) 153; Advance in Physics 3(1954) 446Google Scholar
- 14.L.T, Grazman and M.E. Raikh, JETP Lett. 44, 452 (1988)Google Scholar
- 16.V.L. Berezinskii, Soviet Phys. JETP 32, 493 (1971)Google Scholar | <urn:uuid:f4d53931-cd24-494a-af26-381eeffae9d6> | 2.6875 | 370 | Truncated | Science & Tech. | 59.515695 | 95,569,951 |
Washington: NASA is sending scientists around the world this year – from the edge of the Greenland ice sheet to the coral reefs of the South Pacific – to delve into challenging questions about how our planet is changing and what impact humans are having on it.
While Earth science field experiments are nothing new for NASA, the next six months will be a particularly active period with eight major new campaigns taking researchers around the world on a wide range of science investigations, the US space agency said in a statement.
“Combining the long-term global view from space with detailed measurements from field experiments is a powerful way of deciphering what’s happening in our world,” said Michael Freilich, director of NASA’s Earth Science Division in Washington.
The first of the new projects, currently in the field, is an examination of the extent to which the oceans around Greenland are melting the edges of the ice sheet from below.
Air quality is the focus of the Korea US-Air Quality (KORUS-AQ) campaign in South Korea, which begins in May. This joint study between NASA and the Republic of Korea is aimed at advancing the ability to monitor air pollution from space, with coordinated observations from aircraft, ground sites, ships and satellites.
Also in May, the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) takes to the sea and air for the second year to study how the world’s largest plankton bloom gives rise to small organic particles that influence clouds and climate.
Throughout much of this year, teams of scientists working on the Arctic Boreal Vulnerability Experiment (ABoVE) will be in the tundra and forests of Alaska and northwestern Canada investigating the role of climate in wild fires, thawing permafrost, wildlife migration habits and insect outbreaks, NASA said.
In June, the Coral Reef Airborne Laboratory (CORAL) project team will begin testing airborne and in-water instruments in Hawaii to assess the condition of threatened coral-based ecosystems. CORAL’s next stop will be Australia’s Great Barrier Reef.
Three airborne research campaigns will take to the skies this summer, focusing on critical climate-related components of the atmosphere. Flying tracks over the Pacific and Atlantic oceans thousands of miles long, the team of the Atmospheric Tomography (ATom) mission will gather measurements on more than 200 different chemical species from the ocean surface up to approximately seven miles in the atmosphere to understand how the movement and transformation of short-lived greenhouse gases, such as ozone and methane, contribute to climate change.
Focusing on the skies over the eastern half of the United States, the Atmospheric Carbon and Transport – America (ACT-America) research team will track the movement of atmospheric carbon to better understand the sources and sinks of greenhouse gases. Flights will originate from Louisiana, Nebraska and Virginia.
The Observations of Clouds above Aerosols and their Interactions (ORACLES) study will use airborne instruments to probe the impact on climate and rainfall of the interaction between clouds over the southeastern Atlantic Ocean and smoke from massive vegetation burning in southern Africa.
NASA believes that a better understanding of how the smoke particles alter stratocumulus clouds that play a key role in regional and global surface temperatures and precipitation will help improve current climate models. | <urn:uuid:cb4e00a5-5864-4433-b31b-02ab03dc7df5> | 3.78125 | 674 | News Article | Science & Tech. | 20.351971 | 95,569,956 |
Scientists are developing new ways to alter the genetic code of living organisms. John Oliver explores the risks, rewards, and wolf-related hazards of gene editing.... Read More إقرأ المزيد | Share it now!
This year, Mars reaches its long-awaited opposition on July 27—and is visible all night. Look for its south polar cap and dark features that shift as the planet rotates. You will also spot constellations Scorpius and Sagittarius, and the annual Delta Aquarid meteor shower.... Read More إقرأ المزيد | Share it now!
30 Doradus (the Tarantula Nebula) is a very bright and active star-forming region outside of the Milky Way galaxy, at 160,000 light-years away. “30 Dor” is home to the central star cluster NGC 2070, including the most active region, R136, which appears in the central-right area of the image. R136 is a few million years old and contains many thousands of young stars, including several of the largest known. The bright blue stars shine out of the cleared cavity that is excavated by stellar winds. The redder stars are still partially embedded in the cloud material, seen in shadow except where illuminated by the cavity stars. In the infrared view the embedded stars shine more clearly through the intervening cloud material. ... Read More إقرأ المزيد | Share it now!
This sequence uses infrared (Spitzer) and visible (Hubble) images to reveal the formation of stars within a large cloud of hydrogen gas and dust. The warm gas lights up in the infrared view as red, and the hydrocarbon dust appears in green. The starlight from young stars appears in blue. The flood of starlight provides extra illumination throughout the dusty environment and in front of the cloud. The threads of gas, reminiscent of clouds on Earth, are compressed and pushed into knots by the winds from forming stars throughout the region. The clouds appear as shadows in this visible-light view. However, in areas where the gas has mostly been cleared or thinned, glowing cavities can be seen inside these cocoons. The combined view hints at the nebula’s complex three-dimensional structure.... Read More إقرأ المزيد | Share it now! | <urn:uuid:866300c8-fde5-44c0-b3ff-08ed9be28681> | 2.734375 | 495 | Content Listing | Science & Tech. | 65.299369 | 95,569,960 |
or log in
The compound of hydrogen and oxygen. Colourless, odourless liquid; heavier than water.
A white, crystalline compound that breaks down when affected by light.
Colourless, odourless, heavier-than-air gas. Necessary for the photosynthesis of plants.
A colourless, odourless gas, an important component of the atmosphere, indispensable to...
A compound ion formed when a water molecule releases a proton.
Limestone is a widely and diversely used material.
Colourless liquid that gives off smoke in moist air.
The presence of hydronium ions relative to hydroxide ions determines a solution´s pH. | <urn:uuid:a552f107-1d36-4c71-adbe-bb2ae276c8a5> | 2.953125 | 144 | Content Listing | Science & Tech. | 37.209855 | 95,569,962 |
+44 1803 865913
By: KH Mann
406 pages, 15 col plates, 128 illus
Undergraduate textbook on coastal marine ecosystems. The content is accessible - chapters cover various environments and scientific principles are applied to steps in the management and decision-making process.
Praise from Reviewers: "Ecology of Coastal Waters: With Implications for Management, Second Edition is a thorough synthesis that describes the processing of materials in nearshore ecosystems, with an emphasis on the importance of this information for policy issues. The book will be useful as a text for upper-level undergraduate and graduate students interest in coastal marine ecology and resource management. Ken Mann's style is easy to read and informative.--Merryl Alber, PhD, Department of Marine Sciences, University of Georgia "I found few books that give a broad introduction to this subject. Mann's book appears to fill this gap, and I will very likely adopt it as a text when it is published."--Chris Tanner, PhD, Department of Biology, St. Mary's College of Maryland
Preface.1. The Subject and the Approach.Part One: Estuarine Ecosystems and their Components.2. Estuaries: their Physical Properties in Relation to their Biological Functioning.3. Salt-Marshes.4. Mangroves.5. Seagrass Systems.6. The Fate of Macrophyte Detritus.7. Estuarine Planktonic Systems.8. Estuarine Benthic Systems.9. Fish and Shellfish in Estuaries.10. The Integrated Functioning of Estuaries. Part Two: Coastal Systems: Rocky Shortes and Beaches.11. Intertidal Rocky Shores.12. Subtidal Rocky Shores.13. Sandy Beaches. Part Three: Shelf Ecosystems.14. Planktonic Systems on the Continental Shelves.15. Coastal Upwelling Ecosystems.16. Coral Reefs.17. Fish Production on the Continental Shelves. Part Four: Synthesis.18. The Whole-Ecosystem Approach to Managing Coastal Waters: Questions for the Future. References. Suggestions for Further Reading: recent Developments and More. Advanced Topics. Index.
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Wildlife, science and conservation since 1985 | <urn:uuid:aba7a101-d978-4b85-be6d-ceeb8a7b3f38> | 2.71875 | 524 | Product Page | Science & Tech. | 49.427813 | 95,569,983 |
Access Class Properties through Instance Name
Can I access class properties through an instance name?
Yes, you can access class properties through an instance name, as long as there is no instance property that has the same name as a class property.
When you reference a property through the instance name in the following form:
Python will search for the given property name in instance_name.__dict__ first. If match found, return the value. If not match found, continue with the next step.
In the next step, Python will search the given property name in class_name.__dict__. If match found, return the value. If not match found, return error.
The following Python code shows you a good example of accessing class property through a instance name:
>>> class user(): ... nextID = 1 ... def __init__(self,name="Joe",age=25): ... self.id = user.nextID ... self.name = name ... self.age = age ... user.nextID = user.nextID + 1 ... >>> x = user() >>> x.nextID 2
2017-09-09, 183👍, 0💬
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Where to find tutorials on how to work with MySQL Database in PHP? A collection of tutorials to answ...
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Where to find tutorials on Python programming language? I want to learn Python. Here is a large coll...
How To Control Table Widths? Usually, browsers will calculate the table width based on the content w... | <urn:uuid:552aafd0-e8e8-4874-b25e-d7affd07ce94> | 2.96875 | 361 | Content Listing | Software Dev. | 75.042465 | 95,569,985 |
Can you arrange the digits 1, 1, 2, 2, 3 and 3 to make a Number Sandwich?
Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?
How many moves does it take to swap over some red and blue frogs? Do you have a method?
Can you mentally fit the 7 SOMA pieces together to make a cube? Can you do it in more than one way?
Can you work out how to win this game of Nim? Does it matter if you go first or second?
The idea of this game is to add or subtract the two numbers on the dice and cover the result on the grid, trying to get a line of three. Are there some numbers that are good to aim for?
A game for 2 people. Take turns placing a counter on the star. You win when you have completed a line of 3 in your colour.
Place the 16 different combinations of cup/saucer in this 4 by 4 arrangement so that no row or column contains more than one cup or saucer of the same colour.
There are nine teddies in Teddy Town - three red, three blue and three yellow. There are also nine houses, three of each colour. Can you put them on the map of Teddy Town according to the rules?
Four friends must cross a bridge. How can they all cross it in just 17 minutes?
The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
Everthing you have always wanted to do with dominoes! Some of these games are good for practising your mental calculation skills, and some are good for your reasoning skills.
A game for 2 players. Take turns to place a counter so that it occupies one of the lowest possible positions in the grid. The first player to complete a line of 4 wins.
A game for 2 players that can be played online. Players take it in turns to select a word from the 9 words given. The aim is to select all the occurrences of the same letter.
An ordinary set of dominoes can be laid out as a 7 by 4 magic rectangle in which all the spots in all the columns add to 24, while those in the rows add to 42. Try it! Now try the magic square...
Use these four dominoes to make a square that has the same number of dots on each side.
A game for 2 players. Set out 16 counters in rows of 1,3,5 and 7. Players take turns to remove any number of counters from a row. The player left with the last counter looses.
The Tower of Hanoi is an ancient mathematical challenge. Working on the building blocks may help you to explain the patterns you notice.
Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.
Factor track is not a race but a game of skill. The idea is to go round the track in as few moves as possible, keeping to the rules.
Given the nets of 4 cubes with the faces coloured in 4 colours, build a tower so that on each vertical wall no colour is repeated, that is all 4 colours appear.
A game for 2 players with similaritlies to NIM. Place one counter on each spot on the games board. Players take it is turns to remove 1 or 2 adjacent counters. The winner picks up the last counter.
Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?
Can you spot the similarities between this game and other games you know? The aim is to choose 3 numbers that total 15.
Can you put the 25 coloured tiles into the 5 x 5 square so that no column, no row and no diagonal line have tiles of the same colour in them?
Can you use small coloured cubes to make a 3 by 3 by 3 cube so that each face of the bigger cube contains one of each colour?
Can you be the first to complete a row of three?
Show how this pentagonal tile can be used to tile the plane and describe the transformations which map this pentagon to its images in the tiling.
A game in which players take it in turns to choose a number. Can you block your opponent?
Is it possible to use all 28 dominoes arranging them in squares of four? What patterns can you see in the solution(s)?
There are lots of different methods to find out what the shapes are worth - how many can you find?
How many differently shaped rectangles can you build using these equilateral and isosceles triangles? Can you make a square?
A game that demands a logical approach using systematic working to deduce a winning strategy
Using the digits 1, 2, 3, 4, 5, 6, 7 and 8, mulitply a two two digit numbers are multiplied to give a four digit number, so that the expression is correct. How many different solutions can you find?
Using the 8 dominoes make a square where each of the columns and rows adds up to 8
In the ancient city of Atlantis a solid rectangular object called a Zin was built in honour of the goddess Tina. Your task is to determine on which day of the week the obelisk was completed.
Using the interactivity, can you make a regular hexagon from yellow triangles the same size as a regular hexagon made from green triangles ?
Eulerian and Hamiltonian circuits are defined with some simple examples and a couple of puzzles to illustrate Hamiltonian circuits.
Take ten sticks in heaps any way you like. Make a new heap using one from each of the heaps. By repeating that process could the arrangement 7 - 1 - 1 - 1 ever turn up, except by starting with it? | <urn:uuid:4eabb9fb-7b66-4e49-947f-cdc88e1bf9d0> | 2.71875 | 1,282 | Content Listing | Science & Tech. | 75.224172 | 95,569,994 |
Types and Structure of Ribonucleic Acid
Edited by Jen Moreau, Marisha, SarMal, Sharingknowledge
Ribonucleic acid (RNA) is a polymeric molecule and like the DNA (deoxyribonucleic acid), is composed of nucleotides. Unlike DNA, RNA is a single stranded molecule with chain lengths ranging from 10 to more than 1000 nucleotides and serves various biological functions in an organism's cell. These functions include coding, decoding, carrying genetic information, regulation, and expression of genes in living organisms. A nucleotide is the building block of ribonucleic acid; consisting of three sub-units: nitrogenous base, a five-carbon sugar, and a phosphate group.
While proteins are widely known to be responsible for catalysis in cells, some RNA also play crucial roles as catalysts in biological reactions. For example, ribozyme catalyzes chemical reactions in a similar fashion as protein enzymes.
There are three main characteristics that distinguish RNA from other types of nucleic acids:
- 1An example of an RNA complementary pairing is HIV viral RNA. Once the virus enters the host cell, HIV viral RNA is converted to a double-stranded RNA by the enzyme 'reverse transcriptase.'RNA is a single-stranded molecule, however, it can form a double-stranded molecule through complementary pairing.Advertisement
- 2Ribose has a hydroxyl group (OH) on the 2' carbon and deoxyribose does not. Deoxy stands for the lack of one oxygen atom that is present in ribose sugar, making deoxyribose more stable than ribose.The sugar on the RNA molecule contains a ribose sugar on its backbone.
- 3Purines are composed of adenine (A) and guanine (G), while pyrimidines are made up of cytosine (C), and uracil which is written as (You). Thymine (T) may also be present along with uracil depending on the type of ribonucleic acid. Consequently, the nitrogenous bases in RNA are adenine, guanine, uracil, and cytosine.There are two types of nitrogenous bases in any ribonucleic acid, namely -- purine and pyrimidine.
Comparison with DNA
DNA (Deoxyribonucleic acid) is a nucleic acid which carries the genetic instruction in all living organisms. The genetic information includes growth, development, reproduction, and functioning of an organism. Like an RNA molecule, DNA is also composed of nucleotides. Slight differences exist between the nucleotides of the two, as well as in the arrangement of the molecules. Although these differences may appear subtle, they contribute towards significant functional differences in the two molecules.
The chemical structure of RNA differs from DNA in the following ways:
- 1Occasionally, RNA can be paired to form a double strand.DNA is a double-stranded helical molecule, as compared to RNA which is usually single stranded.
- 2In the nitrogenous base of DNA, thymine is paired with adenine while in RNA, the thymine is replaced by uracil.
- 3The DNA molecule contains a deoxyribose sugar as opposed to the ribose sugar found in RNA.
Synthesis of RNA
The synthesis of RNA is called transcription. As the name implied, transcription is a process of transcribing or transferring DNA nucleotide sequence information into RNA sequence information. The synthesis is catalyzed by an enzyme called RNA polymerase. During the initiation of transcription, RNA polymerase unwinds a short stretch of double-helical DNA to produce a single-stranded DNA template from which it takes instructions. The enzyme then progresses in the 3′ to 5′ direction to synthesize a complementary RNA molecule.
There are different classes of RNA:
- 1Messenger RNA (mRNA)
- 2Ribosomal RNA (rRNA)
- 3Transfer RNA (tRNA)
- 4Small interfering RNA (siRNA)
- 5Micro RNA (miRNA)
- 6Small nuclear RNA (snRNA)
Messenger RNA (mRNA) carries information about the protein to be synthesized to the ribosome. The ribosome is found in both prokaryotes and eukaryotes and serves as the site of protein synthesis. Ribosomes link amino acids together in the order specified by the mRNA, thus an mRNA can be called as the architect in protein synthesis, while ribosome is the constructor.
Ribosomal ribonucleic acid (rRNA) is made up of two components, protein, and RNA. rRNA binds tRNA and other accessory molecules for synthesis. The RNA component of the ribosome has a catalytic function like an enzyme.
Transfer RNA (tRNA) is another class of ribonucleic acid and acts as the middleman between mRNA and rRNA in the synthesis of protein. tRNA has two arms, with one of the arms attached to amino acids, while the other binds to the mRNA. Amino acids are carried by tRNA and connected by a peptide bond during the process of translation, to produce a protein.
MicroRNA (miRNA) is a non-coding RNA of 20-22 nucleotide length, that plays an important role in gene silencing. miRNA binds to mRNA, thus silencing the gene. The application of miRNA continues to be explored in biotechnology to stop the reproduction of unwanted genes in cancer therapy. The failure of miRNA to efficiently silence unwanted genes often result in the uncontrolled synthesis of the protein, which is a hallmark for cancer. Efforts are continuing to attempt to increase the activity of miRNA in cells for stricter post-transcriptional regulation of gene expression.
Small interfering RNA (siRNA) are double-stranded RNA and contain about 19 nucleotides. siRNA, along with miRNA bind to mRNA and promotes gene silencing. While miRNA converts mRNA to 'processing bodies' which are then either stored or destroyed, the siRNA differs in that it always destroys the mRNA.
Small nuclear RNA (snRNA) is involved in the process of gene splicing. siRNA is often found in the intron region of genes encoding proteins that are involved in the ribosome synthesis. The average length of snRNA is 150 nucleotides. The specific mechanism by which snRNA regulates RNA modification is still unknown.
Referencing this Article
If you need to reference this article in your work, you can copy-paste the following depending on your required format:
APA (American Psychological Association)
Types and Structure of Ribonucleic Acid. (2017). In ScienceAid. Retrieved Jul 22, 2018, from https://scienceaid.net/Ribonucleic_Acid
MLA (Modern Language Association) "Types and Structure of Ribonucleic Acid." ScienceAid, scienceaid.net/Ribonucleic_Acid Accessed 22 Jul 2018.
Chicago / Turabian ScienceAid.net. "Types and Structure of Ribonucleic Acid." Accessed Jul 22, 2018. https://scienceaid.net/Ribonucleic_Acid.
Categories : Biology
Recent edits by: SarMal, Marisha, Jen Moreau | <urn:uuid:72aa0503-181e-4f28-b86e-b8b82d3893f8> | 4.21875 | 1,523 | Knowledge Article | Science & Tech. | 31.456355 | 95,569,997 |
In research on the never-ending war between pathogen and host, scientists at the Pasteur Institute in Paris have discovered a novel defensive weapon, a cytoskeletal protein called septin, that humans cells deploy to cage the invading Shigella bacteria that cause potentially fatal human diarrhea, according to a presentation on Dec. 5, at the American Society for Cell Biology Annual Meeting in Denver.
Pascale Cossart, Ph.D., and Serge Mostowy, Ph.D., reported that the septin cages not only targeted the pathogens for degradation by autophagy, the cell's internal garbage disposal system, but also prevented the Shigella bacteria from spreading to other cells by impeding the pathogens' access to actin, a different component of the cell skeleton.
Shigella requires actin to rocket around the host cell before punching into an adjacent cell, said the Pasteur researchers, who made their discovery in human cells grown in culture in the laboratory.
First discovered in yeast as rings that pinch off dividing cells, septins are Guanosine-5'-triphosphate (GTP)-binding proteins that are integral to a cell's dynamic skeleton. Cossart, a Howard Hughes Medical Institute (HHMI) investigator, and Mostowy continue to investigate the properties of the individual septins, which total 14 in humans, to understand how they associate with other proteins as parts of complex nano-machines.
Before their studies revealed septin's new role in innate immunity, Cossart and Mostowy said that the cytoskeletal protein already was implicated in the pathogenesis of many human disorders including leukemia and colon cancer as well as Parkinson's and Alzheimer's diseases.
This research was supported by the Howard Hughes Medical Institute, European Research Council, Fondation Recherche Médicale, the Canadian Louis Pasteur Foundation, and Canadian Institutes of Health Research.
CONTACT:Pascale Cossart, Ph.D.
John Fleischman | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Also protects against bone loss from aging or lack of estrogen
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The secret appears to be a secreted signaling protein called Wnt10b. Known to inhibit the development of adipose tissue in mice, Wnt10b also stimulates the growth of bone cells, according to a new study that will be published February 21 in the Online Early Edition of the Proceedings of the National Academy of Sciences. "High levels of Wnt10b expression in bone marrow directly increased bone mass and density in our experimental mice," says Ormond A. MacDougald, Ph.D., associate professor of molecular and integrative physiology in the U-M Medical School. "This is the first identification of a specific signaling protein in the Wnt family that regulates bone formation."
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. In simpler terms, a mass spectrum measures the masses within a sample. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical structures of molecules, such as peptides and other chemical compounds.
In a typical MS procedure, a sample, which may be solid, liquid, or gas, is ionized, for example by bombarding it with electrons. This may cause some of the sample's molecules to break into charged fragments. These ions are then separated according to their mass-to-charge ratio, typically by accelerating them and subjecting them to an electric or magnetic field: ions of the same mass-to-charge ratio will undergo the same amount of deflection. The ions are detected by a mechanism capable of detecting charged particles, such as an electron multiplier. Results are displayed as spectra of the relative abundance of detected ions as a function of the mass-to-charge ratio. The atoms or molecules in the sample can be identified by correlating known masses (e.g. an entire molecule) to the identified masses or through a characteristic fragmentation pattern.
In 1886, Eugen Goldstein observed rays in gas discharges under low pressure that traveled away from the anode and through channels in a perforated cathode, opposite to the direction of negatively charged cathode rays (which travel from cathode to anode). Goldstein called these positively charged anode rays "Kanalstrahlen"; the standard translation of this term into English is "canal rays". Wilhelm Wien found that strong electric or magnetic fields deflected the canal rays and, in 1899, constructed a device with perpendicular electric and magnetic fields that separated the positive rays according to their charge-to-mass ratio (Q/m). Wien found that the charge-to-mass ratio depended on the nature of the gas in the discharge tube. English scientist J.J. Thomson later improved on the work of Wien by reducing the pressure to create the mass spectrograph.
The word spectrograph had become part of the international scientific vocabulary by 1884. Early spectrometry devices that measured the mass-to-charge ratio of ions were called mass spectrographs which consisted of instruments that recorded a spectrum of mass values on a photographic plate. A mass spectroscope is similar to a mass spectrograph except that the beam of ions is directed onto a phosphor screen. A mass spectroscope configuration was used in early instruments when it was desired that the effects of adjustments be quickly observed. Once the instrument was properly adjusted, a photographic plate was inserted and exposed. The term mass spectroscope continued to be used even though the direct illumination of a phosphor screen was replaced by indirect measurements with an oscilloscope. The use of the term mass spectroscopy is now discouraged due to the possibility of confusion with light spectroscopy. Mass spectrometry is often abbreviated as mass-spec or simply as MS.
Sector mass spectrometers known as calutrons were developed by Ernest O. Lawrence and used for separating the isotopes of uranium during the Manhattan Project. Calutron mass spectrometers were used for uranium enrichment at the Oak Ridge, Tennessee Y-12 plant established during World War II.
In 2002, the Nobel Prize in Chemistry was awarded to John Bennett Fenn for the development of electrospray ionization (ESI) and Koichi Tanaka for the development of soft laser desorption (SLD) and their application to the ionization of biological macromolecules, especially proteins.
Parts of a mass spectrometerEdit
A mass spectrometer consists of three components: an ion source, a mass analyzer, and a detector. The ionizer converts a portion of the sample into ions. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample, which are then targeted through the mass analyzer and into the detector. The differences in masses of the fragments allows the mass analyzer to sort the ions by their mass-to-charge ratio. The detector measures the value of an indicator quantity and thus provides data for calculating the abundances of each ion present. Some detectors also give spatial information, e.g., a multichannel plate.
The following example describes the operation of a spectrometer mass analyzer, which is of the sector type. (Other analyzer types are treated below.) Consider a sample of sodium chloride (table salt). In the ion source, the sample is vaporized (turned into gas) and ionized (transformed into electrically charged particles) into sodium (Na+) and chloride (Cl−) ions. Sodium atoms and ions are monoisotopic, with a mass of about 23 u. Chloride atoms and ions come in two isotopes with masses of approximately 35 u (at a natural abundance of about 75 percent) and approximately 37 u (at a natural abundance of about 25 percent). The analyzer part of the spectrometer contains electric and magnetic fields, which exert forces on ions traveling through these fields. The speed of a charged particle may be increased or decreased while passing through the electric field, and its direction may be altered by the magnetic field. The magnitude of the deflection of the moving ion's trajectory depends on its mass-to-charge ratio. Lighter ions get deflected by the magnetic force more than heavier ions (based on Newton's second law of motion, F = ma). The streams of sorted ions pass from the analyzer to the detector, which records the relative abundance of each ion type. This information is used to determine the chemical element composition of the original sample (i.e. that both sodium and chlorine are present in the sample) and the isotopic composition of its constituents (the ratio of 35Cl to 37Cl).
Techniques for ionization have been key to determining what types of samples can be analyzed by mass spectrometry. Electron ionization and chemical ionization are used for gases and vapors. In chemical ionization sources, the analyte is ionized by chemical ion-molecule reactions during collisions in the source. Two techniques often used with liquid and solid biological samples include electrospray ionization (invented by John Fenn) and matrix-assisted laser desorption/ionization (MALDI, initially developed as a similar technique "Soft Laser Desorption (SLD)" by K. Tanaka for which a Nobel Prize was awarded and as MALDI by M. Karas and F. Hillenkamp).
Hard ionization and soft ionizationEdit
In mass spectrometry, ionization refers to the production of gas phase ions suitable for resolution in the mass analyser or mass filter. Ionization occurs in the ion source. There are several ion sources available; each has advantages and disadvantages for particular applications. For example, electron ionization (EI) gives a high degree of fragmentation, yielding highly detailed mass spectra which when skilfully analysed can provide important information for structural elucidation/characterisation and facilitate identification of unknown compounds by comparison to mass spectral libraries obtained under identical operating conditions. However, EI is not suitable for coupling to HPLC, i.e. LC-MS, since at atmospheric pressure, the filaments used to generate electrons burn out rapidly. Thus EI is coupled predominantly with GC, i.e. GC-MS, where the entire system is under high vacuum.
Hard ionization techniques are processes which impart high quantities of residual energy in the subject molecule invoking large degrees of fragmentation (i.e. the systematic rupturing of bonds acts to remove the excess energy, restoring stability to the resulting ion). Resultant ions tend to have m/z lower than the molecular mass (other than in the case of proton transfer and not including isotope peaks). The most common example of hard ionization is electron ionization (EI).
Soft ionization refers to the processes which impart little residual energy onto the subject molecule and as such result in little fragmentation. Examples include fast atom bombardment (FAB), chemical ionization (CI), atmospheric-pressure chemical ionization (APCI), electrospray ionization (ESI), and matrix-assisted laser desorption/ionization (MALDI).
Inductively coupled plasmaEdit
Inductively coupled plasma (ICP) sources are used primarily for cation analysis of a wide array of sample types. In this source, a plasma that is electrically neutral overall, but that has had a substantial fraction of its atoms ionized by high temperature, is used to atomize introduced sample molecules and to further strip the outer electrons from those atoms. The plasma is usually generated from argon gas, since the first ionization energy of argon atoms is higher than the first of any other elements except He, O, F and Ne, but lower than the second ionization energy of all except the most electropositive metals. The heating is achieved by a radio-frequency current passed through a coil surrounding the plasma.
Photoionization mass spectrometryEdit
Photoionization can be used in experiments which seek to use mass spectrometry as a means of resolving chemical kinetics mechanisms and isomeric product branching. In such instances a high energy photon, either X-ray or uv, is used to dissociate stable gaseous molecules in a carrier gas of He or Ar. In instances where a synchrotron light source is utilzed, a tuneable photon energy can be utilized to acquire a photoionization efficiency curve which can be used in conjunction with the charge ratio m/z to fingerprint molecular and ionic species.
Other ionization techniquesEdit
Others include glow discharge, field desorption (FD), fast atom bombardment (FAB), thermospray, desorption/ionization on silicon (DIOS), Direct Analysis in Real Time (DART), atmospheric pressure chemical ionization (APCI), secondary ion mass spectrometry (SIMS), spark ionization and thermal ionization (TIMS).
Mass analyzers separate the ions according to their mass-to-charge ratio. The following two laws govern the dynamics of charged particles in electric and magnetic fields in vacuum:
- (Newton's second law of motion in non-relativistic case, i.e. valid only at ion velocity much lower than the speed of light).
Here F is the force applied to the ion, m is the mass of the ion, a is the acceleration, Q is the ion charge, E is the electric field, and v × B is the vector cross product of the ion velocity and the magnetic field
Equating the above expressions for the force applied to the ion yields:
This differential equation is the classic equation of motion for charged particles. Together with the particle's initial conditions, it completely determines the particle's motion in space and time in terms of m/Q. Thus mass spectrometers could be thought of as "mass-to-charge spectrometers". When presenting data, it is common to use the (officially) dimensionless m/z, where z is the number of elementary charges (e) on the ion (z=Q/e). This quantity, although it is informally called the mass-to-charge ratio, more accurately speaking represents the ratio of the mass number and the charge number, z.
There are many types of mass analyzers, using either static or dynamic fields, and magnetic or electric fields, but all operate according to the above differential equation. Each analyzer type has its strengths and weaknesses. Many mass spectrometers use two or more mass analyzers for tandem mass spectrometry (MS/MS). In addition to the more common mass analyzers listed below, there are others designed for special situations.
There are several important analyser characteristics. The mass resolving power is the measure of the ability to distinguish two peaks of slightly different m/z. The mass accuracy is the ratio of the m/z measurement error to the true m/z. Mass accuracy is usually measured in ppm or milli mass units. The mass range is the range of m/z amenable to analysis by a given analyzer. The linear dynamic range is the range over which ion signal is linear with analyte concentration. Speed refers to the time frame of the experiment and ultimately is used to determine the number of spectra per unit time that can be generated.
A sector field mass analyzer uses a static electric and/or magnetic field to affect the path and/or velocity of the charged particles in some way. As shown above, sector instruments bend the trajectories of the ions as they pass through the mass analyzer, according to their mass-to-charge ratios, deflecting the more charged and faster-moving, lighter ions more. The analyzer can be used to select a narrow range of m/z or to scan through a range of m/z to catalog the ions present.
The time-of-flight (TOF) analyzer uses an electric field to accelerate the ions through the same potential, and then measures the time they take to reach the detector. If the particles all have the same charge, the kinetic energies tends to be identical, and their velocities, in this case, will depend only on their masses. Ions with a lower mass will reach the detector first. However, in reality, even particles with the same m/z can arrive at different times at the detector, because they have different initial velocities. The initial velocity is not dependent on the mass of the ion what becomes a problem for the TOF-MS. The difference in initial velocity turns into difference in the final velocity. In this way, ions with the same m/z are going to arrive at different times in the detector. For fixing this problem, time-lag focusing/delayed extraction has been coupled with TOF-MS.
Quadrupole mass filterEdit
Quadrupole mass analyzers use oscillating electrical fields to selectively stabilize or destabilize the paths of ions passing through a radio frequency (RF) quadrupole field created between 4 parallel rods. Only the ions in a certain range of mass/charge ratio are passed through the system at any time, but changes to the potentials on the rods allow a wide range of m/z values to be swept rapidly, either continuously or in a succession of discrete hops. A quadrupole mass analyzer acts as a mass-selective filter and is closely related to the quadrupole ion trap, particularly the linear quadrupole ion trap except that it is designed to pass the untrapped ions rather than collect the trapped ones, and is for that reason referred to as a transmission quadrupole. A magnetically enhanced quadrupole mass analyzer includes the addition of a magnetic field, either applied axially or transversely. This novel type of instrument leads to an additional performance enhancement in terms of resolution and/or sensitivity depending upon the magnitude and orientation of the applied magnetic field. A common variation of the transmission quadrupole is the triple quadrupole mass spectrometer. The “triple quad” has three consecutive quadrupole stages, the first acting as a mass filter to transmit a particular incoming ion to the second quadrupole, a collision chamber, wherein that ion can be broken into fragments. The third quadrupole also acts as a mass filter, to transmit a particular fragment ion to the detector. If a quadrupole is made to rapidly and repetitively cycle through a range of mass filter settings, full spectra can be reported. Likewise, a triple quad can be made to perform various scan types characteristic of tandem mass spectrometry.
Three-dimensional quadrupole ion trapEdit
The quadrupole ion trap works on the same physical principles as the quadrupole mass analyzer, but the ions are trapped and sequentially ejected. Ions are trapped in a mainly quadrupole RF field, in a space defined by a ring electrode (usually connected to the main RF potential) between two endcap electrodes (typically connected to DC or auxiliary AC potentials). The sample is ionized either internally (e.g. with an electron or laser beam), or externally, in which case the ions are often introduced through an aperture in an endcap electrode.
There are many mass/charge separation and isolation methods but the most commonly used is the mass instability mode in which the RF potential is ramped so that the orbit of ions with a mass a > b are stable while ions with mass b become unstable and are ejected on the z-axis onto a detector. There are also non-destructive analysis methods.
Ions may also be ejected by the resonance excitation method, whereby a supplemental oscillatory excitation voltage is applied to the endcap electrodes, and the trapping voltage amplitude and/or excitation voltage frequency is varied to bring ions into a resonance condition in order of their mass/charge ratio.
Cylindrical ion trapEdit
The cylindrical ion trap mass spectrometer (CIT) is a derivative of the quadrupole ion trap where the electrodes are formed from flat rings rather than hyperbolic shaped electrodes. The architecture lends itself well to miniaturization because as the size of a trap is reduced, the shape of the electric field near the center of the trap, the region where the ions are trapped, forms a shape similar to that of a hyperbolic trap.
Linear quadrupole ion trapEdit
A linear quadrupole ion trap is similar to a quadrupole ion trap, but it traps ions in a two dimensional quadrupole field, instead of a three-dimensional quadrupole field as in a 3D quadrupole ion trap. Thermo Fisher's LTQ ("linear trap quadrupole") is an example of the linear ion trap.
A toroidal ion trap can be visualized as a linear quadrupole curved around and connected at the ends or as a cross section of a 3D ion trap rotated on edge to form the toroid, donut shaped trap. The trap can store large volumes of ions by distributing them throughout the ring-like trap structure. This toroidal shaped trap is a configuration that allows the increased miniaturization of an ion trap mass analyzer. Additionally all ions are stored in the same trapping field and ejected together simplifying detection that can be complicated with array configurations due to variations in detector alignment and machining of the arrays.
As with the toroidal trap, linear traps and 3D quadrupole ion traps are the most commonly miniaturized mass analyzers due to their high sensitivity, tolerance for mTorr pressure, and capabilities for single analyzer tandem mass spectrometry (e.g. product ion scans).
Orbitrap instruments are similar to Fourier transform ion cyclotron resonance mass spectrometers (see text below). Ions are electrostatically trapped in an orbit around a central, spindle shaped electrode. The electrode confines the ions so that they both orbit around the central electrode and oscillate back and forth along the central electrode's long axis. This oscillation generates an image current in the detector plates which is recorded by the instrument. The frequencies of these image currents depend on the mass-to-charge ratios of the ions. Mass spectra are obtained by Fourier transformation of the recorded image currents.
Orbitraps have a high mass accuracy, high sensitivity and a good dynamic range.
Fourier transform ion cyclotron resonanceEdit
Fourier transform mass spectrometry (FTMS), or more precisely Fourier transform ion cyclotron resonance MS, measures mass by detecting the image current produced by ions cyclotroning in the presence of a magnetic field. Instead of measuring the deflection of ions with a detector such as an electron multiplier, the ions are injected into a Penning trap (a static electric/magnetic ion trap) where they effectively form part of a circuit. Detectors at fixed positions in space measure the electrical signal of ions which pass near them over time, producing a periodic signal. Since the frequency of an ion's cycling is determined by its mass-to-charge ratio, this can be deconvoluted by performing a Fourier transform on the signal. FTMS has the advantage of high sensitivity (since each ion is "counted" more than once) and much higher resolution and thus precision.
Ion cyclotron resonance (ICR) is an older mass analysis technique similar to FTMS except that ions are detected with a traditional detector. Ions trapped in a Penning trap are excited by an RF electric field until they impact the wall of the trap, where the detector is located. Ions of different mass are resolved according to impact time.
The final element of the mass spectrometer is the detector. The detector records either the charge induced or the current produced when an ion passes by or hits a surface. In a scanning instrument, the signal produced in the detector during the course of the scan versus where the instrument is in the scan (at what m/Q) will produce a mass spectrum, a record of ions as a function of m/Q.
Typically, some type of electron multiplier is used, though other detectors including Faraday cups and ion-to-photon detectors are also used. Because the number of ions leaving the mass analyzer at a particular instant is typically quite small, considerable amplification is often necessary to get a signal. Microchannel plate detectors are commonly used in modern commercial instruments. In FTMS and Orbitraps, the detector consists of a pair of metal surfaces within the mass analyzer/ion trap region which the ions only pass near as they oscillate. No direct current is produced, only a weak AC image current is produced in a circuit between the electrodes. Other inductive detectors have also been used.
Tandem mass spectrometryEdit
A tandem mass spectrometer is one capable of multiple rounds of mass spectrometry, usually separated by some form of molecule fragmentation. For example, one mass analyzer can isolate one peptide from many entering a mass spectrometer. A second mass analyzer then stabilizes the peptide ions while they collide with a gas, causing them to fragment by collision-induced dissociation (CID). A third mass analyzer then sorts the fragments produced from the peptides. Tandem MS can also be done in a single mass analyzer over time, as in a quadrupole ion trap. There are various methods for fragmenting molecules for tandem MS, including collision-induced dissociation (CID), electron capture dissociation (ECD), electron transfer dissociation (ETD), infrared multiphoton dissociation (IRMPD), blackbody infrared radiative dissociation (BIRD), electron-detachment dissociation (EDD) and surface-induced dissociation (SID). An important application using tandem mass spectrometry is in protein identification.
Tandem mass spectrometry enables a variety of experimental sequences. Many commercial mass spectrometers are designed to expedite the execution of such routine sequences as selected reaction monitoring (SRM) and precursor ion scanning. In SRM, the first analyzer allows only a single mass through and the second analyzer monitors for multiple user-defined fragment ions. SRM is most often used with scanning instruments where the second mass analysis event is duty cycle limited. These experiments are used to increase specificity of detection of known molecules, notably in pharmacokinetic studies. Precursor ion scanning refers to monitoring for a specific loss from the precursor ion. The first and second mass analyzers scan across the spectrum as partitioned by a user-defined m/z value. This experiment is used to detect specific motifs within unknown molecules.
Another type of tandem mass spectrometry used for radiocarbon dating is accelerator mass spectrometry (AMS), which uses very high voltages, usually in the mega-volt range, to accelerate negative ions into a type of tandem mass spectrometer.
Common mass spectrometer configurations and techniquesEdit
When a specific combination of source, analyzer, and detector becomes conventional in practice, a compound acronym may arise to designate it succinctly. One example is MALDI-TOF, which refers to a combination of a matrix-assisted laser desorption/ionization source with a time-of-flight mass analyzer. Other examples include inductively coupled plasma-mass spectrometry (ICP-MS), accelerator mass spectrometry (AMS), thermal ionization-mass spectrometry (TIMS) and spark source mass spectrometry (SSMS).
Certain applications of mass spectrometry have developed monikers that although strictly speaking would seem to refer to a broad application, in practice have come instead to connote a specific or a limited number of instrument configurations. An example of this is isotope ratio mass spectrometry (IRMS), which refers in practice to the use of a limited number of sector based mass analyzers; this name is used to refer to both the application and the instrument used for the application.
Separation techniques combined with mass spectrometryEdit
An important enhancement to the mass resolving and mass determining capabilities of mass spectrometry is using it in tandem with chromatographic and other separation techniques.
A common combination is gas chromatography-mass spectrometry (GC/MS or GC-MS). In this technique, a gas chromatograph is used to separate different compounds. This stream of separated compounds is fed online into the ion source, a metallic filament to which voltage is applied. This filament emits electrons which ionize the compounds. The ions can then further fragment, yielding predictable patterns. Intact ions and fragments pass into the mass spectrometer's analyzer and are eventually detected.
Similar to gas chromatography MS (GC/MS), liquid chromatography-mass spectrometry (LC/MS or LC-MS) separates compounds chromatographically before they are introduced to the ion source and mass spectrometer. It differs from GC/MS in that the mobile phase is liquid, usually a mixture of water and organic solvents, instead of gas. Most commonly, an electrospray ionization source is used in LC/MS. Other popular and commercially available LC/MS ion sources are atmospheric pressure chemical ionization and atmospheric pressure photoionization. There are also some newly developed ionization techniques like laser spray.
Capillary electrophoresis–mass spectrometryEdit
Capillary electrophoresis–mass spectrometry (CE-MS) is a technique that combines the liquid separation process of capillary electrophoresis with mass spectrometry. CE-MS is typically coupled to electrospray ionization.
Ion mobility spectrometry-mass spectrometry (IMS/MS or IMMS) is a technique where ions are first separated by drift time through some neutral gas under an applied electrical potential gradient before being introduced into a mass spectrometer. Drift time is a measure of the radius relative to the charge of the ion. The duty cycle of IMS (the time over which the experiment takes place) is longer than most mass spectrometric techniques, such that the mass spectrometer can sample along the course of the IMS separation. This produces data about the IMS separation and the mass-to-charge ratio of the ions in a manner similar to LC/MS.
The duty cycle of IMS is short relative to liquid chromatography or gas chromatography separations and can thus be coupled to such techniques, producing triple modalities such as LC/IMS/MS.
Data and analysisEdit
Mass spectrometry produces various types of data. The most common data representation is the mass spectrum.
Certain types of mass spectrometry data are best represented as a mass chromatogram. Types of chromatograms include selected ion monitoring (SIM), total ion current (TIC), and selected reaction monitoring (SRM), among many others.
Other types of mass spectrometry data are well represented as a three-dimensional contour map. In this form, the mass-to-charge, m/z is on the x-axis, intensity the y-axis, and an additional experimental parameter, such as time, is recorded on the z-axis.
Mass spectrometry data analysis is specific to the type of experiment producing the data. General subdivisions of data are fundamental to understanding any data.
Many mass spectrometers work in either negative ion mode or positive ion mode. It is very important to know whether the observed ions are negatively or positively charged. This is often important in determining the neutral mass but it also indicates something about the nature of the molecules.
Different types of ion source result in different arrays of fragments produced from the original molecules. An electron ionization source produces many fragments and mostly single-charged (1-) radicals (odd number of electrons), whereas an electrospray source usually produces non-radical quasimolecular ions that are frequently multiply charged. Tandem mass spectrometry purposely produces fragment ions post-source and can drastically change the sort of data achieved by an experiment.
Knowledge of the origin of a sample can provide insight into the component molecules of the sample and their fragmentations. A sample from a synthesis/manufacturing process will probably contain impurities chemically related to the target component. A crudely prepared biological sample will probably contain a certain amount of salt, which may form adducts with the analyte molecules in certain analyses.
Results can also depend heavily on sample preparation and how it was run/introduced. An important example is the issue of which matrix is used for MALDI spotting, since much of the energetics of the desorption/ionization event is controlled by the matrix rather than the laser power. Sometimes samples are spiked with sodium or another ion-carrying species to produce adducts rather than a protonated species.
Mass spectrometry can measure molar mass, molecular structure, and sample purity. Each of these questions requires a different experimental procedure; therefore, adequate definition of the experimental goal is a prerequisite for collecting the proper data and successfully interpreting it.
Interpretation of mass spectraEdit
Since the precise structure or peptide sequence of a molecule is deciphered through the set of fragment masses, the interpretation of mass spectra requires combined use of various techniques. Usually the first strategy for identifying an unknown compound is to compare its experimental mass spectrum against a library of mass spectra. If no matches result from the search, then manual interpretation or software assisted interpretation of mass spectra must be performed. Computer simulation of ionization and fragmentation processes occurring in mass spectrometer is the primary tool for assigning structure or peptide sequence to a molecule. An a priori structural information is fragmented in silico and the resulting pattern is compared with observed spectrum. Such simulation is often supported by a fragmentation library that contains published patterns of known decomposition reactions. Software taking advantage of this idea has been developed for both small molecules and proteins.
Analysis of mass spectra can also be spectra with accurate mass. A mass-to-charge ratio value (m/z) with only integer precision can represent an immense number of theoretically possible ion structures; however, more precise mass figures significantly reduce the number of candidate molecular formulas. A computer algorithm called formula generator calculates all molecular formulas that theoretically fit a given mass with specified tolerance.
A recent technique for structure elucidation in mass spectrometry, called precursor ion fingerprinting, identifies individual pieces of structural information by conducting a search of the tandem spectra of the molecule under investigation against a library of the product-ion spectra of structurally characterized precursor ions.
Mass spectrometry has both qualitative and quantitative uses. These include identifying unknown compounds, determining the isotopic composition of elements in a molecule, and determining the structure of a compound by observing its fragmentation. Other uses include quantifying the amount of a compound in a sample or studying the fundamentals of gas phase ion chemistry (the chemistry of ions and neutrals in a vacuum). MS is now in very common use in analytical laboratories that study physical, chemical, or biological properties of a great variety of compounds.
As an analytical technique it possesses distinct advantages such as: Increased sensitivity over most other analytical techniques because the analyzer, as a mass-charge filter, reduces background interference, Excellent specificity from characteristic fragmentation patterns to identify unknowns or confirm the presence of suspected compounds, Information about molecular weight, Information about the isotopic abundance of elements, Temporally resolved chemical data.
A few of the disadvantages of the method is that it often fails to distinguish between optical and geometrical isomers and the positions of substituent in o-, m- and p- positions in an aromatic ring. Also, its scope is limited in identifying hydrocarbons that produce similar fragmented ions.
Isotope ratio MS: isotope dating and tracingEdit
Mass spectrometry is also used to determine the isotopic composition of elements within a sample. Differences in mass among isotopes of an element are very small, and the less abundant isotopes of an element are typically very rare, so a very sensitive instrument is required. These instruments, sometimes referred to as isotope ratio mass spectrometers (IR-MS), usually use a single magnet to bend a beam of ionized particles towards a series of Faraday cups which convert particle impacts to electric current. A fast on-line analysis of deuterium content of water can be done using flowing afterglow mass spectrometry, FA-MS. Probably the most sensitive and accurate mass spectrometer for this purpose is the accelerator mass spectrometer (AMS). This is because it provides ultimate sensitivity, capable of measuring individual atoms and measuring nuclides with a dynamic range of ~1015 relative to the major stable isotope. Isotope ratios are important markers of a variety of processes. Some isotope ratios are used to determine the age of materials for example as in carbon dating. Labeling with stable isotopes is also used for protein quantification. (see protein characterization below)
Membrane-Inlet Mass Spectrometry: Measuring gasses in solutionEdit
Membrane-inlet Mass Spectrometry, combines the Isotope ratio MS with a reaction chamber/cell separated by a gas-permeable membrane. This method allows the study of gasses as they evolve in solution. This method has been extensively used for the study of the production of oxygen by Photosystem II.
Trace gas analysisEdit
Several techniques use ions created in a dedicated ion source injected into a flow tube or a drift tube: selected ion flow tube (SIFT-MS), and proton transfer reaction (PTR-MS), are variants of chemical ionization dedicated for trace gas analysis of air, breath or liquid headspace using well defined reaction time allowing calculations of analyte concentrations from the known reaction kinetics without the need for internal standard or calibration.
Pharmacokinetics is often studied using mass spectrometry because of the complex nature of the matrix (often blood or urine) and the need for high sensitivity to observe low dose and long time point data. The most common instrumentation used in this application is LC-MS with a triple quadrupole mass spectrometer. Tandem mass spectrometry is usually employed for added specificity. Standard curves and internal standards are used for quantitation of usually a single pharmaceutical in the samples. The samples represent different time points as a pharmaceutical is administered and then metabolized or cleared from the body. Blank or t=0 samples taken before administration are important in determining background and ensuring data integrity with such complex sample matrices. Much attention is paid to the linearity of the standard curve; however it is not uncommon to use curve fitting with more complex functions such as quadratics since the response of most mass spectrometers is less than linear across large concentration ranges.
Mass spectrometry is an important method for the characterization and sequencing of proteins. The two primary methods for ionization of whole proteins are electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). In keeping with the performance and mass range of available mass spectrometers, two approaches are used for characterizing proteins. In the first, intact proteins are ionized by either of the two techniques described above, and then introduced to a mass analyzer. This approach is referred to as "top-down" strategy of protein analysis. The top-down approach however is largely limited to low-throughput single-protein studies. In the second, proteins are enzymatically digested into smaller peptides using proteases such as trypsin or pepsin, either in solution or in gel after electrophoretic separation. Other proteolytic agents are also used. The collection of peptide products are then introduced to the mass analyzer. When the characteristic pattern of peptides is used for the identification of the protein the method is called peptide mass fingerprinting (PMF), if the identification is performed using the sequence data determined in tandem MS analysis it is called de novo peptide sequencing. These procedures of protein analysis are also referred to as the "bottom-up" approach. A third approach however is beginning to be used, this intermediate "middle-down" approach involves analyzing proteolytic peptide larger than the typical tryptic peptide.
Mass spectrometry (MS), with its low sample requirement and high sensitivity, has been predominantly used in glycobiology for characterization and elucidation of glycan structures. Mass spectrometry provides a complementary method to HPLC for the analysis of glycans. Intact glycans may be detected directly as singly charged ions by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) or, following permethylation or peracetylation, by fast atom bombardment mass spectrometry (FAB-MS). Electrospray ionization mass spectrometry (ESI-MS) also gives good signals for the smaller glycans. Various free and commercial software are now available which interpret MS data and aid in Glycan structure characterization.
As a standard method for analysis, mass spectrometers have reached other planets and moons. Two were taken to Mars by the Viking program. In early 2005 the Cassini–Huygens mission delivered a specialized GC-MS instrument aboard the Huygens probe through the atmosphere of Titan, the largest moon of the planet Saturn. This instrument analyzed atmospheric samples along its descent trajectory and was able to vaporize and analyze samples of Titan's frozen, hydrocarbon covered surface once the probe had landed. These measurements compare the abundance of isotope(s) of each particle comparatively to earth's natural abundance. Also on board the Cassini–Huygens spacecraft was an ion and neutral mass spectrometer which had been taking measurements of Titan's atmospheric composition as well as the composition of Enceladus' plumes. A Thermal and Evolved Gas Analyzer mass spectrometer was carried by the Mars Phoenix Lander launched in 2007.
Mass spectrometers are also widely used in space missions to measure the composition of plasmas. For example, the Cassini spacecraft carried the Cassini Plasma Spectrometer (CAPS), which measured the mass of ions in Saturn's magnetosphere.
Respired gas monitorEdit
Mass spectrometers were used in hospitals for respiratory gas analysis beginning around 1975 through the end of the century. Some are probably still in use but none are currently being manufactured.
Found mostly in the operating room, they were a part of a complex system, in which respired gas samples from patients undergoing anesthesia were drawn into the instrument through a valve mechanism designed to sequentially connect up to 32 rooms to the mass spectrometer. A computer directed all operations of the system. The data collected from the mass spectrometer was delivered to the individual rooms for the anesthesiologist to use.
The uniqueness of this magnetic sector mass spectrometer may have been the fact that a plane of detectors, each purposely positioned to collect all of the ion species expected to be in the samples, allowed the instrument to simultaneously report all of the gases respired by the patient. Although the mass range was limited to slightly over 120 u, fragmentation of some of the heavier molecules negated the need for a higher detection limit.
Preparative mass spectrometryEdit
The primary function of mass spectrometry is as a tool for chemical analyses based on detection and quantification of ions according to their mass-to-charge ratio. However, mass spectrometry also shows promise for material synthesis. Ion soft landing is characterized by deposition of intact species on surfaces at low kinetic energies which precludes the fragmentation of the incident species. The soft landing technique was first reported in 1977 for the reaction of low energy sulfur containing ions on a lead surface.
- Dumas method of molecular weight determination
- Helium mass spectrometer
- Isotope dilution
- MassBank (database), a Japanese spectral database
- Mass spectrometry imaging
- Mass spectrometry software
- Micro-arrays for mass spectrometry
- Nanoscale secondary ion mass spectrometry
- Quadrupole magnet
- Time-resolved mass spectrometry
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The mode of a set of data values is the value that appears most often. It is the value at which the data is most likely to be sampled. A mode of a continuous probability distribution is often considered to be any value x at which its probability density function has a locally maximum value, so any peak is a mode.
Python is very robust when it comes to statistics and working with a set of large range of values. The statistics module has a very large number of functions to work with very large data-sets. The mode() function is one of such methods. This function returns the robust measure of a central data point in a given range of data-sets.
Given data-set is : [1, 2, 3, 4, 4, 4, 4, 5, 6, 7, 7, 7, 8] The mode of the given data-set is 4 Logic : 4 is the most occurring/ most common element from the given list
Syntax : mode([data-set]) Parameters : [data-set] which is a tuple, list or a iterator of real valued numbers as well as Strings. Return type : Returns the most-common data point from discrete or nominal data. Errors and Exceptions : Raises StatisticsError when there are two modes present in a single list, or when data set is empty .
Code #1 : This piece will demonstrate mode() function through a simple example.
# Python code to demonstrate the # use of mode() function # mode() function a sub-set of the statistics module # We need to import statistics module before doing any work import statistics # declaring a simple data-set consisting of real valued # positive integers. set1 =[1, 2, 3, 3, 4, 4, 4, 5, 5, 6] # In the given data-set # Count of 1 is 1 # Count of 2 is 1 # Count of 3 is 2 # Count of 4 is 3 # Count of 5 is 2 # Count of 6 is 1 # We can infer that 4 has the highest population distribution # So mode of set1 is 4 # Printing out mode of given data-set print("Mode of given data set is % s" % (statistics.mode(set1)))
Mode of given data set is 4
Code #2 : In this code we will be demonstrating the mode() function a various range of data-sets.
# Python code to demonstrate the # working of mode() function # on a various range of data types # Importing the statistics module from statistics import mode # Importing fractions module as fr # Enables to calculate harmonic_mean of a # set in Fraction from fractions import Fraction as fr # tuple of positive integer numbers data1 = (2, 3, 3, 4, 5, 5, 5, 5, 6, 6, 6, 7) # tuple of a set of floating point values data2 = (2.4, 1.3, 1.3, 1.3, 2.4, 4.6) # tuple of a set of fractional numbers data3 = (fr(1, 2), fr(1, 2), fr(10, 3), fr(2, 3)) # tuple of a set of negaitve integers data4 = (-1, -2, -2, -2, -7, -7, -9) # tuple of strings data5 = ("red", "blue", "black", "blue", "black", "black", "brown") # Printing out the mean of the above data-sets print("Harmonic mean of data set 1 is % s" % (mode(data1))) print("Harmonic mean of data set 2 is % s" % (mode(data2))) print("Harmonic mean of data set 3 is % s" % (mode(data3))) print("Harmonic mean of data set 4 is % s" % (mode(data4))) print("Harmonic mean of data set 5 is % s" % (mode(data5)))
Harmonic mean of data set 1 is 5 Harmonic mean of data set 2 is 1.3 Harmonic mean of data set 3 is 1/2 Harmonic mean of data set 4 is -2 Harmonic mean of data set 5 is black
Code #3 : In this piece of code will demonstrate when StatisticsError is raised
# Python code to demonstrate the # statistics error in mode function ''' StatisticsError is raised while using mode when there are two equal modes present in a data set and when the data set is empty or null ''' # importing statistics module import statistics # creating a data set consisting of two equal data-sets data1 =[1, 1, 1, -1, -1, -1] # In the above data set # Count of 1 is 3 # Count of -1 is also 3 # StatisticsError will be raised print(statistics.mode(data1))
Traceback (most recent call last): File "/home/38fbe95fe09d5f65aaa038e37aac20fa.py", line 20, in print(statistics.mode(data1)) File "/usr/lib/python3.5/statistics.py", line 474, in mode 'no unique mode; found %d equally common values' % len(table) statistics.StatisticsError: no unique mode; found 2 equally common values
Applications : The mode() is a statistics function and mostly used in Financial Sectors to compare values/prices with past details, calculate/predict probable future prices from a price distribution set. mean() is not used seperately but along with two other pillars of statistics mean and meadian creates a very powerful tool which can be used to reveal any aspect of your data.
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Euclidean m -Space & Linear Equations. Row Reduction of Linear Systems. Matrix. A matrix is a rectangular array of numbers. This array is enclosed in brackets or parentheses. Each number in a matrix is called and element or entry of that matrix.
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Row Reduction of Linear Systems
A matrix is a rectangular array of numbers.
This array is enclosed in brackets or parentheses.
Each number in a matrix is called and element or entry of that matrix.
Each horizontal line of numbers in a matrix is called a row.
Each vertical line of numbers in a matrix is called a column.
Matrix arise from a linear system in standard form by deleting all unknowns operations and equal signs.
A vertical line is drawn along the equal signs to separate the constant column.
When an unknown is missing in an equation, the coefficient zero is inserted in the augmented matrix.
Multiply a row by a nonzero scalar.
Interchange the positions of two rows.
Replace a row by the sum of itself and a multiple of another row.
x1 + x2 + 2x3 = 8
-x1 - 2x2 + 3x3 = 1
3x1 - 7x2 + 4x3 = 10
When one matrix can be obtained from another matrix by a finite sequence of row operations, the two matrices are said to be row-equivalent.
The underlying linear systems of two row-equivalent matrices have same solutions.
A matrix is in row reduced echelon form if it satisfies the following conditions:
The process of transforming an augmented matrix to an equivalent row-reduced echelon form is called the Gauss-Jordan Elimination.
A matrix is in row echelon form if it satisfies the following conditions: | <urn:uuid:b7fc70b4-4afa-4c5d-b6e0-a1588d0b5b2d> | 3.71875 | 436 | Documentation | Science & Tech. | 49.970422 | 95,570,097 |
Radar satellites supply the data used to map sea level and ocean currents. However, up until now the radar's "eyes" have been blind where the oceans are covered by ice. Researchers at the Technical University of Munich (TUM) have now developed a new analysis method to solve this problem.
The melting of the polar ice cap would have a drastic effect: Sea level would rise by several meters around the world, impacting hundreds of millions of people who live close to coasts. "This means one of the most important questions of our time is how climate change is affecting the polar regions," explains Dr. Marcello Passaro of the TUM German Geodetic Research Institute.
The blind spot of the radar "eye"
But changes in sea level and ocean currents in the ice-covered regions of the Arctic and Antarctic in particular are very difficult to detect. The reason: The radar signals of the altimeter satellites that have been surveying the surfaces of the earth and oceans for more than two decades are reflected by the ice at the poles. This renders the water underneath the ice invisible.
But ocean water also passes through cracks and openings in the permanent ice, reaching the surface. "These patches of water are however very small and the signals are highly distorted by the surrounding ice. Here standard evaluation methods like those used for measurements made on the open seas are incapable of returning reliable results," Passaro points out. Together with an international team he has now developed a data analysis method which sharpens the focus of the radar's eyes.
An algorithm for all occasions
The core of this virtual "contact lens" is the adaptive algorithm ALES+, (Adaptive Leading Edge Subwaveform). ALES+ automatically identifies the portion of the radar signal which is reflected by water and derives sea level values using this information only.
This makes it possible to precisely measure the altitude of the ocean water which reaches the surface through ice cracks and openings. By comparing several years of measurements, climate researchers and oceanographers can now draw conclusions about changes in sea level and ocean currents.
"The special thing about our method is that it is adaptive," Passaro notes. "We can use one and the same algorithm to measure sea level in both open and ice-covered ocean areas. ALES+ can also be used for coastal waters, lakes and rivers. Here the signals are highly varied, but always exhibit certain characteristic properties which the system then learns." The scientists were able to use a test scenario in the Greenland Sea to demonstrate that ALES+ returns water levels for ice-covered and open ocean regions which are significantly more precise than the results of previous evaluation methods.
More information: The research is a part of the Sea Level Climate Change Initiative of the European Space Agency.
Passaro, M., S. Kildegaard Rose, O. Andersen, E. Boergens, F. M. Calafat, D. Dettmering, J. Benveniste: ALES+: Adapting a homogenous ocean retracker for satellite altimetry to sea ice leads, coastal and inland waters. Remote Sensing of Environment, 2018,
Müller F.L., Dettmering D., Bosch W., Seitz F.: Monitoring the Arctic
Seas: How satellite altimetry can be used to detect open water in sea-ice regions. Remote Sensing, 9(6), 551, DOI:10.3390/rs9060551, 2017. https:/
Photos for editorial use:
Dr. Marcello Passaro
Technical University of Munich
German Geodetic Research Institute and Chair of Geodetic Geodynamics
Tel.: +49 (89) 23031-1214 | <urn:uuid:467ffc8c-8f56-446a-b6d6-6664348a6444> | 3.90625 | 760 | News (Org.) | Science & Tech. | 42.481452 | 95,570,112 |
Дата публикации: 2018-05-27 12:48
specific reaction conditions
Lewis structures do not indicate the shapes of molecules, however they do show the numbers and types of bonds between atoms
The Royal Society of Chemistry (RSC) has agreed to the IES proposal and added five keywords to their Journals that are now available for authors and reviewers to select when they are describing their areas of expertise. The change applies across all of RSC journals.
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The idea is that resonance is only possible when the proton has been lost, and that the lower energy of the 697 resonating 698 structure provides the driving force for the loss of the proton, and thus is the source of the acidity carboxylic group. (By the way, this view of the cause of carboxylic acidity has been criticized other factors that may well be more important are also involved.)
To calculate enthalpy change for some amount of substance other than 6 mol, the molar enthalpy value is obtained from a reference source, and then the following formula is used:
All forms of radiation move through a vacuum at the speed of light which is x 658 M/S and have wavelike characteristics
The rate law for a chemical reaction was found to be: Rate = k[NO7 (g)][F7 (g)]
The following elementary steps have been proposed: NO7 (g) + F (g) → NO7F (g)
There are also examples of molecules whose existence is beyond question, but for which no satisfactory Lewis structures can be written. Two examples are the triiodide ion I 8 655 , and the bifluoride ion HF 7 655 . | <urn:uuid:a689f05d-f01b-497a-be7e-55b6f5171324> | 2.671875 | 433 | Knowledge Article | Science & Tech. | 27.351014 | 95,570,119 |
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As drought continues and water levels plummet in Cape Town’s dams, residents are facing a slew of new emergency measures.
Messages of conservation have fallen on deaf ears, the city said, necessitating a crackdown on usage.
“We have reached a point of no return. Despite our urging for months, 60 percent of Capetonians are callously using more than 87 litres per day,” Mayor Patricia de Lille said.
This week, the government is set to vote on the introduction of a punitive tariff, which will charge residents using above 6,000 liters per month exponentially higher rates for their water.
As of Feb. 1, usage will be restricted to 50 liters per person per day to make up for months of overuse.
Though desalination plants are set to go online in February and drilling into the aquifer will also take place, officials say the additional resources are too little too late.
“The people who are still wasting water seem to believe that Day Zero just can't happen or that the city’s seven augmentation projects - set to produce around 200 million litres per day – will be enough to save us,” de Lille said.
“This is not the case and, while our water augmentation programme will make Cape Town more water resilient in the future, it was never going to be enough to stop Day Zero,” she said.
The city has announced water collection points, which will become the only way to obtain water for personal use if dam levels continue to drop.
Taps will be shut off and residents will be able to retrieve 25 liters per person each day from one of 200 collection points across the city.
'We’re deep, deep, deep in crisis': Cape Town may become 1st major city in world to run out of water
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With Cape Town boasting a population of 4 million, many residents say it’s not a practical solution.
Residents have accused the government of insufficient planning and water mismanagement among other things, but experts say this situation was largely unpredictable and not one officials at a city level would typically plan for.
“Whilst the city may have been a bit slow to enforce stronger restrictions once the severity of the drought became obvious, I don’t think they had any way of predicting just how bad it was,” Kristy Carden, researcher for the University of Cape Town’s Urban Water Management Research Unit, told AccuWeather.
“Climate scientists have suggested that the cumulative effect of the three below-average rainfall years equates to something approaching a once-in-1,000-years drought occurrence, not something that would be planned for at city level,” Carden said.
With the rainy season still months away, it’s likely the situation will worsen before it gets better.
"The dry season typically continues into early April, so the likelihood for significant rainfall the next two months is low," AccuWeather Meteorologist Eric Leister said.
Comments that don't add to the conversation may be automatically or manually removed by Facebook or AccuWeather. Profanity, personal attacks, and spam will not be tolerated.
The intense record heat baking the south-central United States is expected to get trimmed back early this week, but a sweep of refreshing air is not on the horizon.
This past weekend's rainstorm was only the start of an abnormally wet pattern that will elevate the flood risk in the eastern United States into the end of the month.
Despite NASCAR moving up the start time of the Foxwoods Resort Casino 301, rain has hung on and delayed the race at Loudon, New Hampshire.
Yet another round of severe weather is threatening the southeastern United States to close out this weekend.
The remainder of July will be dominated by a resurgence of heat across the northwestern United States.
An uptick in monsoon rainfall is expected to heighten the flood threat across eastern and northern India this week. | <urn:uuid:e514bcb1-613a-4e5e-aeba-e080a59dec36> | 2.625 | 853 | News Article | Science & Tech. | 40.492098 | 95,570,125 |
Summertime hail could all but disappear from the eastern flank of Colorado's Rocky Mountains by 2070, according to a new modeling study by scientists from NOAA and several other institutions.
Less hail damage could be good news for gardeners and farmers, said Kelly Mahoney, Ph.D., lead author of the study and a postdoctoral scientist at NOAA's Earth System Research Laboratory in Boulder, Colo. But a shift from hail to rain can also mean more runoff, which could raise the risk of flash floods, she said.
"In this region of elevated terrain, hail may lessen the risk of flooding because it takes a while to melt," Mahoney said. "Decision makers may not want to count on that in the future."
For the new study, published this week in the journal Nature Climate Change, Mahoney and her colleagues used "downscaling" modeling techniques to try to understand how climate change might affect hail-producing weather patterns across Colorado.
The research focused on storms involving relatively small hailstones (up to pea-sized) on Colorado's Front Range, a region that stretches from the foothill communities of Colorado Springs, Denver and Fort Collins up to the Continental Divide. Colorado's most damaging hailstorms tend to occur further east and involve larger hailstones not examined in this study.
In the summer on the Front Range, precipitation commonly falls as hail above an elevation of 7,500 feet. Decision makers concerned about the safety of mountain dams and flood risk have been interested in how climate change may affect the amount and nature of precipitation in the region.
Mahoney and her colleagues began exploring that question with results from two existing climate models that assumed that levels of climate-warming greenhouse gases will continue to increase in the future (for instance, carbon dioxide, which is at about 390 parts per million today, increases in the model to 620 ppm by 2070).But the weather processes that form hail – thunderstorm formation, for example – occur on much smaller scales than can be reproduced by global climate models. So the team "downscaled" the global model results twice: first to regional-scale models that can take regional topography and other details into account (this step was completed as part of the National Center for Atmospheric Research's North American Regional Climate Change Assessment Program). Then, the regional results were further downscaled to weather-scale models that can simulate the details of individual storms and even the in-cloud processes that create hail.
"We found a near elimination of hail at the surface," Mahoney said.
In the future, increasingly intense storms may actually produce more hail inside clouds, the team found. However, because those relatively small hailstones fall through a warmer atmosphere, they melt quickly, falling as rain at the surface or evaporating back into the atmosphere. In some regions, simulated hail fell through an additional 1,500 feet (~450 meters) of above-freezing air in the future, compared to the past.
The research team also found evidence that extreme precipitation events across all of Colorado may become more extreme in the future, while changes in hail patterns may depend on hailstone size -- results that are being explored in more detail in ongoing work.
Mahoney's postdoctoral research was supported by the PACE program (Postdocs Applying Climate Expertise) administered by the University Corporation for Atmospheric Research and funded by NOAA, the Bureau of Reclamation and the Western Water Assessment. PACE connects young climate scientists with real-world problems such as those faced by water resource managers.
"With climate change, we are examining potential changes in the magnitude and character of precipitation at high elevations," said John England, Ph.D., flood hydrology specialist at the Bureau of Reclamation in Denver, Colo. "The Bureau of Reclamation will now take these scientific results and determine any implications for its facilities in the Front Range of Colorado."
NOAA's mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.
Co-authors of the new paper, "Changes in hail and flood risk in high-resolution simulations over the Colorado Mountains," include Michael Alexander (NOAA/Earth System Research Laboratory); Gregory Thompson (National Center for Atmospheric Research) and Joseph Barsugli and James Scott (NOAA/Cooperative Institute for Research in Environmental Sciences, CIRES).
Katy Human | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
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Technology for Sustainable Development
This chapter contains four presentations on technologies for sustainable development. The first by M. Levine, having examined a number of old and new technologies for increasing energy efficiency, discusses the need for international collaborations, especially between North and South. Pointing out China as becoming one of the major concerns for global environment due to its rapid economic development, he argues that there is a huge potential for improving its relatively poor performance. For this, he demonstrates the importance of policy orientation toward energy efficiency in China on one hand, and on the other a program of international cooperation through technology transfer, capital investments and above all the exchange of ideas on sustainable development. The last analysis, touching on the possibility of achieving economic development as well as environmental protection, is the main point of interest.
Both the second by K. Yamada and the third by H. Ishitani provide the scope of possibilities which new technologies can offer to the ostensibly contradicting demands today, namely the ever increasing need for energy supply on the one hand and the more severe measures of environmental protection on the other. Yamada demonstrates the possibility of large scale utilization of photovoltaic systems and argues that this increasingly popular technology does have a tremendous future in terms of providing a kind energy source to the globe. Alternatively, Ishitani examines the possibility of technology for CO2 disposal into the deep ocean. This paper provoked a number of counter-arguments, especially from those from the South. However, as he mentions in his paper, this attempt is important in developing technology for safer recycling of the end products, in this case CO2—the technology for which remains still at an embryonic stage.
The last presentation is by R. Huang who touches on climate and environmental change in East Asia, or more correctly, China. As seen above, China is simultaneously experiencing rapid economic development and degradation of its eco-system. Having examined the widespread flood and drought patterns in China’s recent past, he argues that a clear correlation between economic development and environmental problems can be seen. Because China’s is a developing economy, what is needed is both international cooperation, to set an upper limit to global warming, and also concrete actions, within and outside China, for the resolution of such dilemmas.
KeywordsEnergy Efficiency River Valley Summer Precipitation Energy Service Yangtze River Valley
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By: SK Deshmukh and MK Rai
474 pages, Tabs
Fungi are the largest group among living organisms after insects. The total fungal species is estimated to be 1.5 million, of which 72,000 have been reported and c.1500 are added every year. This book attempts to cover the various aspects of fungi.
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Authors: George Rajna
A research team from the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has found the first evidence that a shaking motion in the structure of an atomically thin (2-D) material possesses a naturally occurring circular rotation. Topological effects, such as those found in crystals whose surfaces conduct electricity while their bulk does not, have been an exciting topic of physics research in recent years and were the subject of the 2016 Nobel Prize in physics. A new technique developed by MIT researchers reveals the inner details of photonic crystals, synthetic materials whose exotic optical properties are the subject of widespread research. In experiments at SLAC, intense laser light (red) shining through a magnesium oxide crystal excited the outermost “valence” electrons of oxygen atoms deep inside it. LCLS works like an extraordinary strobe light: Its ultrabright X-rays take snapshots of materials with atomic resolution and capture motions as fast as a few femtoseconds, or millionths of a billionth of a second. For comparison, one femtosecond is to a second what seven minutes is to the age of the universe. A ‘nonlinear’ effect that seemingly turns materials transparent is seen for the first time in X-rays at SLAC’s LCLS. Leiden physicists have manipulated light with large artificial atoms, so-called quantum dots. Before, this has only been accomplished with actual atoms. It is an important step toward light-based quantum technology. In a tiny quantum prison, electrons behave quite differently as compared to their counterparts in free space. They can only occupy discrete energy levels, much like the electrons in an atom - for this reason, such electron prisons are often called "artificial atoms". When two atoms are placed in a small chamber enclosed by mirrors, they can simultaneously absorb a single photon. Optical quantum technologies are based on the interactions of atoms and photons at the single-particle level, and so require sources of single photons that are highly indistinguishable – that is, as identical as possible. Current single-photon sources using semiconductor quantum dots inserted into photonic structures produce photons that are ultrabright but have limited indistinguishability due to charge noise, which results in a fluctuating electric field. A method to produce significant amounts of semiconducting nanoparticles for light-emitting displays, sensors, solar panels and biomedical applications has gained momentum with a demonstration by researchers at the Department of Energy's Oak Ridge National Laboratory. A source of single photons that meets three important criteria for use in quantum-information systems has been unveiled in China by an international team of physicists. Based on a quantum dot, the device is an efficient source of photons that emerge as solo particles that are indistinguishable from each other. The researchers are now trying to use the source to create a quantum computer based on "boson sampling". With the help of a semiconductor quantum dot, physicists at the University of Basel have developed a new type of light source that emits single photons. For the first time, the researchers have managed to create a stream of identical photons. Optical photons would be ideal carriers to transfer quantum information over large distances. Researchers envisage a network where information is processed in certain nodes and transferred between them via photons. While physicists are continually looking for ways to unify the theory of relativity, which describes large-scale phenomena, with quantum theory, which describes small-scale phenomena, computer scientists are searching for technologies to build the quantum computer using Quantum Information. In August 2013, the achievement of "fully deterministic" quantum teleportation, using a hybrid technique, was reported. On 29 May 2014, scientists announced a reliable way of transferring data by quantum teleportation. Quantum teleportation of data had been done before but with highly unreliable methods. The accelerating electrons explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the Wave-Particle Duality and the electron’s spin also, building the Bridge between the Classical and Quantum Theories. The Planck Distribution Law of the electromagnetic oscillators explains the electron/proton mass rate and the Weak and Strong Interactions by the diffraction patterns. The Weak Interaction changes the diffraction patterns by moving the electric charge from one side to the other side of the diffraction pattern, which violates the CP and Time reversal symmetry. The diffraction patterns and the locality of the self-maintaining electromagnetic potential explains also the Quantum Entanglement, giving it as a natural part of the Relativistic Quantum Theory and making possible to build the Quantum Computer with the help of Quantum Information.
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Deep Decoupling Oscillations of the Oceanic Thermohaline Circulation
The polar ice and ocean sediment cores contain a record of large and sudden climate changes around the North Atlantic Ocean. Evidence for ocean circulation changes occurring synchronously with the terrestrial climate changes has been found in forams from sediment cores which show colder sea surface temperatures and increased deep nutrient levels during the cold Younger Dryas period (Boyle and Keigwin, 1987). The increased nutrients have been interpreted as evidence that North Atlantic Deep Water formation was reduced during the Younger Dryas. A natural conclusion is that such a reduction would have contributed to the cold climate by diminished importation of heat to high, northern hemisphere latitudes. The 18O record from the Greenland ice cores reveals that similar climate oscillations with 500 to 2,000 year warm periods separating the cold periods occurred frequently during the last glaciation (Johnson et al., 1992). These “interstadials” began with abrupt warmings (within decades) followed by gradual or stepwise coolings. Broecker et al. (1990) have suggested that variability of the salinity of the Atlantic Ocean caused by melting ice sheets and water vapor export from the Atlantic forces oscillations in the thermohaline overturning.
KeywordsSurface Heat Flux Couple Phase Zonal Wind Stress Salt Flux Polar Ocean
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for i in range(0,50): t=threading.Thread(target=runcode, args=(i,)) t.daemon=True t.start() t.join(60.0)
Wait until the thread terminates. This blocks the calling thread until the thread whose join() method is called terminates – either normally or through an unhandled exception – or until the optional timeout occurs.
When the timeout argument is present and not None, it should be a floating point number specifying a timeout for the operation in seconds (or fractions thereof). As join() always returns None, you must call isAlive() after join() to decide whether a timeout happened – if the thread is still alive, the join() call timed out.
When the timeout argument is not present or None, the operation will block until the thread terminates.
A thread can be join()ed many times.
join() raises a RuntimeError if an attempt is made to join the current thread as that would cause a deadlock. It is also an error to join() a thread before it has been started and attempts to do so raises the same exception. | <urn:uuid:2a1c0895-d9fa-4bcc-a1f4-f208ca3c9a0e> | 2.578125 | 236 | Documentation | Software Dev. | 66.832334 | 95,570,184 |
Building on their creation of the first-ever mechanical device that can measure the mass of individual molecules, one at a time, a team of scientists has created nanodevices that can also reveal their shape. Such information is crucial when trying to identify large protein molecules or complex assemblies of protein molecules.
They may deal in gold, atomic staples and electron volts rather than cement, support beams and kilowatt-hours, but chemists have drafted new nanoscale blueprints for low-energy structures capable of housing pharmaceuticals and oxygen atoms.
The study investigates the ability of amino-functionalized multi-walled carbon nanotubes to cross the Blood-Brain Barrier (BBB) by two ways: in vitro using a co-culture BBB model comprising primary porcine brain endothelial cells and primary rat astrocytes and, in vivo, following a systemic administration of radiolabelled f-MWNTs.
Ash trees in 22 eastern states of U.S.A. are being decimated by emerald ash borers (EABs), an Asian beetle that arrived in Michigan more than two decades ago. The pest has even spread westwards into Kansas and Colorado. Nothing seemed to be effective against EABs, until decoys designed to mimic female EABs were found in 2012 by a group of researchers to be successful in enticing male EABs for mating. Last year, the same researchers found the decoys could be used to electrocute and kill the seduced males.
In an effort that reaches back to the 19th-century laboratories of Europe, a discovery by chemistry researchers establishes new research possibilities for silicon chemistry and the semiconductor industry. The study gives details on the first time chemists have been able to trap molecular species of silicon oxides.
Using a technique that introduces tiny wrinkles into sheets of graphene, researchers have developed new textured surfaces for culturing cells in the lab that better mimic the complex surroundings in which cells grow in the body. | <urn:uuid:37db4b88-c4da-4512-8d20-296165cf43e8> | 3.046875 | 407 | Content Listing | Science & Tech. | 28.997452 | 95,570,187 |
Large waterbird breeding events are one-third as likely to occur in one of Australia's most important wetlands after floods were sharply curbed by expanded irrigation, researchers have found.
Major floods in the Narran Lakes on the Condamine and Balonne rivers in the northern Murray-Darling Basin are needed for species such as straw-necked ibis to breed.
However, over the past five decades, water resource development has cut the frequency of these floods from one every 4.2 years to one in 11.4 years, according to a study published in Biological Conservation.
The restoration of environmental flows under the $13 billion Murray-Darling Basin Plan is predicted to lift the frequency of large flooding, the modelling shows.
But even then, such events will occur only about once every 6.7 years, or on 59 per cent fewer occasions, than during pre-development periods.
"Reduced opportunities for breeding are likely to result in significant reductions in ibis productivity in the long term," the paper said. Water resource development had already cut the juvenile ibis numbers by an estimated 2.3 million.
"It used to flood fairly frequently [in the Narran Lakes]," said Kate Brandis, a research fellow at the Centre of Ecosystem Science at the University of NSW and lead author of the paper.
"That doesn't tend to happen any more."
Narran Lakes is one of 16 basin wetlands listed for their international importance under the Ramsar Convention, a treaty to which Australia is a signatory. The region is home to 46 waterbird species and, in 1983, supported the largest ibis colony every recorded in Australia, about 400,000 pairs, the paper noted.
The researchers studied the lakes' straw-necked ibis - distinct from the white ibis, common in cities such as Sydney - because they were "by far the most dominant" waterbird and Narran had the largest concentration of them, Richard Kingsford, a UNSW professor and co-author of the paper, said.
Waterbirds such as ibises "are really good indicators of river flows and ecosystem health, and their breeding essentially is a barometer of how well that wetland is doing", Professor Kingsford said.
Floods need to be big enough - greater than 154 billion litres - and last long enough to attract waterbirds and provide food for them to forage, court mates, build nests, and rear and fledge chicks.
Ibises need three to five months of inundation for successful breeding cycles.
However, with the expansion of irrigation, particularly upstream around St George in Queensland since the 1990s, major floods reaching the Narran Lakes are been reduced.
"The water resources have sort of taken off the really big floods, so we end up with more frequent smaller-sized floods of smaller volume and smaller duration," Dr Brandis said.
"The big ones are nowhere near as large in terms of volume or in duration."
Maintaining ibis numbers has implications for farmers. The birds are known as a "farmer's friend", feasting on the locusts and grasshoppers that would otherwise consume crops.
Despite those benefits and Ramsar obligations, the federal government recommended a cut of 42 billion litres of year to the rivers supplying the lakes.
That reduction was formalised this week with passage of the northern basin review amendments cutting environmental water savings by 70 billion litres.
A spokeswoman for the Murray-Darling Basin Authority defended the plan.
"Ecological modelling work by the [authority] clearly demonstrates that the Narran Lakes will experience around 30 per cent more bird breeding events due to the Basin Plan," she said.
Environmental flows provided through the plan "will ensure the Narran Lakes vegetation is in better health and is better able to support migratory birds when they arrive at the lakes."
But Dr Brandis said the latest reduction"will just exacerbate what we've seen".
The researchers' modelling did not take into account future climate change - nor does the basin plan. The plan was also based on "best guesses" about wildlife, she said.
"There’s a huge lack in our understanding of the basic biology of some of these birds," Dr Brandis said. "We don’t know how long they live, how frequently they need to breed ... to account from them accurately in any modelling of water needs."
Morning & Afternoon Newsletter | <urn:uuid:f7c86e15-2ab4-42fe-8202-65bceaa18589> | 3.265625 | 906 | News Article | Science & Tech. | 44.335135 | 95,570,208 |
Small cetaceans: The Forgotten Whales, released today, states that inadequate conservation measures are pushing small cetaceans – such as dolphins, porpoises and small whales – toward extinction as their survival is overshadowed by efforts to save their larger cousins.
"Although great whale species of the world are by no means secure and still require conservation attention, the situation is just as critical for these smaller, seemingly forgotten species," said Dr. Susan Lieberman, Director of the Species Programme for WWF-International.
While great whales are now protected (to an extent) by the international commercial whaling moratorium, in effect since 1986, small cetacean hunts continue around the globe, largely unmanaged and unchecked by the international community.
For example, the hunt of 16,000 Dall's porpoises every year in Japan is considered unsustainable. Yet several of the pro-whaling nations taking part in the International Whaling Commission (IWC) meeting this week object to discussing small cetacean conservation.
"It is time for the IWC and its members to take full responsibility for the conservation future of all whales great and small. The IWC – and the world - must not ignore the small whales of our planet until it is too late," said Dr. Lieberman.
A significant disadvantage smaller whale species face compared to great whales is a crippling lack of data on their numbers and habits. Forty of the 69 small cetacean species, or 58 percent, are classified by IUCN as 'data deficient', meaning that there is not enough information available to even determine whether they are threatened or not.
"It must never be assumed that "Data Deficient" means that the species is out of danger— rather, it means that the world's top scientists just don't know," the report says.
Only four out of 15 Species, or 27 percent, of great whales are listed as data deficient, even though many of the reasons why smaller whale species are difficult to study also apply to the great whales.
According to the IUCN Red List, population trends – whether the species is increasing or decreasing in number – are unknown for 60 of the 69 small cetacean species. The nine remaining species are in decline.
Great whales also have more protection in international conservation efforts. Almost all great whale species, for example, have the strongest level of protection offered by CITES – a conservation convention which regulates international trade in protected wildlife species – compared to just 17 percent of dolphin and porpoises species. In addition, the Convention on Migratory Species (CMS) protects 87 percent of great whale species, but less than half of smaller whale species.
Small cetaceans fulfill a critical role in their environment, stabilising and ensuring a healthy and productive ecosystem. They also are part of the highly profitable whale and dolphin watching industry worldwide, which generates over US $1.5 billion each year.
"If small cetaceans are not central to negotiations on current whaling, it is possible that conservation successes achieved for great whales could simply result in a shift of problems from great whales to small cetaceans," the report states.
IWC 61 runs June 22 to 26 in Madeira, Portugal.
Sarah Janicke | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
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1. let H be a subgroup of a group G such that g ֿ ¹ hg elements in H for all h elements in H. Show every left coset gH is the same as the right coset Hg.
2. prove that if G is an abelian group, written multiplicatively, with identity element e, then all elements, x, of G satisfying the equation x²=e form a sub group H of G
3. show that if a elements in G where G is a finite group with the identity, e, then there exist n elements in Z+ such that a ⁿ =e
4. prove the generalisation of the first part of this question: consider the set H of all solutions, x, of the equation x ⁿ =e for fixed integer n ≥1 in an abelian group, G with identity , e.
5. if ◦ is a binary operation on a set, S an element, x elements in S is an idempotent for ◦ if x ◦ x= x. prove that a group has exactly one idempotent element.
6. define the term 'normal subgroup'. Give an example of a group, G, and a normal subgroup, H, of G
7. prove that every group, G, with identity, e, such that x ◦ x=e for all x G is abelian .
8. draw the cayley tables for the Z and V. for each group, list the pairs of inverses
9. determine whether the following are hohmorphisms. Let:
i. ϕ : Z → R under addition be given by ϕ (n) =n.
ii let G be any group and let : G→ G be given by ϕ (g)=g ֿ ¹
for g elements in G
10. show that if G is nonablelian, the quot6ient group G/Z(G) is not cyclic ( i know that some how i have to show the equivalent contrapositive, ie that if G/Z(G) is cyclic then g is ablelian and hence Z(G)=G)
11. show that the intersection of normal subgroups of a group G is again a normal subgroup of G© BrainMass Inc. brainmass.com July 23, 2018, 5:54 am ad1c9bdddf
First, I claim that gH is contained in Hg. For each element gh in gH, since ghg^(-1)=r^(-1)hr, where r=g^(-1), then ghg^(-1) is an element of H. So we can find some h' in H, such that ghg^(-1)=h'. Then gh=h'g is an element in Hg. So gH is contained in Hg.
Second, I claim that Hg is contained in gH. For each element hg in Hg, since g^(-1)hg is an element in H, then we can find some h' in H, such that g^(-1)hg=h'. So hg=gh' is an element in gH. Thus Hg is contained in gH.
Suppose H is the subset of G such that for any x in H, x^2=e. Now I show that H is a subgroup of G. For any x,y in H, we know x^2=y^2=e. Then y^(-1)^2=y^2^(-1)=e^(-1)=e. Since G is abelian, then (xy^(-1))^2=x^2*y^(-1)^2=e*e=e. So xy^(-1) is an element in H. Therefore, H is a subgroup of G.
G is a finite group, we can suppose |G|=k. For any element a in G, we consider the following k+1 elements: a,a^2,a^3,...,a^k,a^(k+1). All of them belong to G. But G has only k ...
This solution is comprised of a detailed explanation to solve group theories problem. | <urn:uuid:a5132586-0a15-4573-b340-3382760cfc05> | 2.703125 | 912 | Tutorial | Science & Tech. | 103.597307 | 95,570,233 |
Water on the Moon
Interview with USGS scientist Dr. Roger Clark about his Sept. 24 Science article that suggests water exists on the moon. Imaging spectroscopy led Clark and others to this discovery which opens the possibilities into further moon exploration.
Location Taken: US
Heidi Koontz: Welcome and thanks for tuning in to this episode of CoreCasts. I'm Heidi Koontz and I'm here today with Roger Clark. Roger, thanks for taking the time to chat with me about your latest science article.
Roger Clark: OK, thank you.
Heidi Koontz: "Water on the moon," isn't this impossible?
Roger Clark: Well, it's a complex, long story and I'll try and make it brief. But from the formation of the moon, it's thought that a Mars-sized body collided with the Earth and broke a part of the Earth and that material then collected into the moon. During that process, everything was molten and it was thought that all the volatile compounds like water were lost.
Some people don't necessarily agree with that, but most planetary and lunar scientists have believed this for a long time. And the Apollo samples have supported that theory that they don't have much water, but there actually was some water in them. But when the Apollo samples were returned to the Earth in vacuum-sealed boxes, but every one of the fields failed so that when the space capsules came down, Earth atmosphere leaked in along with Earth water. And it was thought for many years that all the water people were seeing was actually due to Earth contamination, and it was very, very difficult to prove otherwise.
About a year ago, a group out of Brown University published a paper where they broke open little glass grains and actually found water inside them and proved for the first time very tiny amounts of water.
Heidi Koontz: And you said that the Cassini last passed by the moon in 1999? That was 10 years ago. Haven't things changed up there?
Roger Clark: Well, the Cassini spacecraft when it flew by the Earth was turned on for a very short time - the instruments. And we took some data and then we were turned back off. So, we collected that data, but we didn't have the calibration in order to understand what the data meant. Well, we turned it on briefly at Jupiter but also didn't get to collect calibration data. We didn't get calibration data until we got to Saturn in 2004.
For detecting tiny amounts of water, water is on the spacecraft. And it's very, very difficult to calibrate an instrument in space because there's still residual water on the instrument. So, we need to look at standards where we don't think there's any water like stars. And it took quite a while to gather the star data.And it wasn't until summer of last year, 2008, that this was figured out what the better calibration is that would allow us to make this discovery. And the first papers with this new calibration were just submitted at the beginning of this year. And so, this is the moon one and there's another one. So, the papers started to flow out from this calibration.
Heidi Koontz: OK, interesting. So, your field of science, spectroscopy, is pretty amazing. Can you give a little insight into how this tool helps better understand this water on the surface of the moon?
Roger Clark: Well, spectroscopy is a method for breaking up light into different wavelengths, much like a rainbow does. Or if you have a prism in a science class, you can use the prism to break up the light; only, that's just visible light. There's also infrared, ultraviolet and other wavelengths. And we use infrared wavelengths further out than longer wavelengths than you could see. So, about five times longer wavelengths, four to five times longer than red light. And it's at those wavelengths where the water molecule has an absorption where it absorbs light of that wavelength and it's that specific set of wavelengths that enables us to see the water, specific compounds. This is just one example; we'll do lots more.
Heidi Koontz: Well, it seems like spectroscopy is a great application for many different scientific endeavors.
Roger Clark: Well, yes. It's a combination of both spectroscopy to understand things and imaging. So, that's the field of imaging spectroscopy, which is a relatively new field mainly because technology has only gotten to this point to allow us to do this over the last, say, 20 years. So, there are now imaging spectrometers flying around the Earth in aircrafts and satellites. There is an imaging spectrometer around Mars called "CRISM" and then the Cassini Visual and Infrared Mapping Spectrometer that's flying around Saturn at the moment.
Heidi Koontz: OK. So, what do you think this means for the future of moon exploration?
Roger Clark: Well, with the discovery of spread water on the surface of the moon in direct sunlight is a pretty amazing discovery because that is in particularly the place where it was thought if there was any water, the sun and solar wind and cosmic rays would bake out all of the water so it should be dry, but this shows that it is not.
So, our next step is trying to understand why it's there in the first place. And we have a lot of data from the M3 Moon Mineralogy Chandrayaan-1 Mission. And we'll be analyzing that data to try and understand as much as we can from that data set which should be a lot. And then, hopefully we'll get a new instrument that can do an even more detailed job to tell us more of the story.
Heidi Koontz: So, those are your next steps?
Roger Clark: Yes.
Heidi Koontz: Well, Roger, thank you for taking the time today and good luck with your future endeavors.
Roger Clark: OK, thank you. | <urn:uuid:33e6187f-ff79-48cc-a342-315f3e3be8cd> | 3.734375 | 1,241 | Audio Transcript | Science & Tech. | 62.074247 | 95,570,242 |
A soccer player kicks a ball at an intial speed of 11.0 m/s at an angle of 40.0 degrees to the ground.
a) How far will the ball travel horizontally?
b) How long is it in the air?© BrainMass Inc. brainmass.com July 16, 2018, 10:50 am ad1c9bdddf
a.) The horizontal displacement of the ball
R = u^2*sin(2Theta)/g
u = ...
This answer is provided in 62 words. It uses brief equations to find displacement and time of the ball once it has been kicked. | <urn:uuid:6fa9859a-981b-4495-964c-9107cad44029> | 3.625 | 131 | Q&A Forum | Science & Tech. | 100.168077 | 95,570,249 |
That is the conclusion of a “proof of concept” experiment described in the Dec. 2 issue of the journal Current Biology. The study found that when the biological clocks of cyanobacteria (blue-green algae) were stopped in their daylight setting, the amount of several biomolecules that they were genetically altered to produce increased by as much as 700 percent when grown in constant light.
“We have shown that manipulating cyanobacteria’s clock genes can increase its production of commercially valuable biomolecules,” said Carl Johnson, Stevenson Professor of Biological Sciences at Vanderbilt University, who performed the study with collaborators at the J. Craig Venter Institute in Rockville, MD and Waseda University in Tokyo. “In the last 10 years, we have figured out how to stop the circadian clocks in most species of algae and in many higher plants as well, so the technique should have widespread applicability.”
If it lives up to its promise, bioclock stopping could have significant economic benefits: Microalgae are used for a wide variety of commercial applications ranging from anti-cancer drugs to cosmetics to bioplastics to biofuels to neutraceuticals. In addition, biotech companies are currently rushing to set up “biofactories” that use microorganisms to create a wide variety of substances that are too difficult or expensive to synthesize using conventional chemical methods. Many of them are based on microorganisms that have biological clocks.
In the current study, the researchers discovered that two components of the clock, KaiA and KaiC, act as switches that turn the cell’s daytime and nighttime genes on and off. They have dubbed this “yin-yang” regulation.
When KaiA is upregulated – produced in larger amounts – and KaiC is downregulated – produced in smaller amounts – then the 95 percent of cell’s genes that are active during daylight are turned on, and the 5 percent of the cell’s genes that operate during the night are turned off. However, when KaiC is upregulated and KaiA is downregulated then the day genes are turned off and the night genes are turned on.
To see what effects this capability has on the bacteria’s ability to produce commercially important compounds, the researchers inserted a gene for human insulin in some of the cyanobacteria cells, a gene for a fluorescent protein (luciferase) in other cells and a gene for hydrogenase, an enzyme that produces hydrogen gas, in yet others. They found that the cells with the locked clocks produced 200 percent more hydrogenase, 500 percent more insulin and 700 percent more luciferase when grown in constant light than they did when the genes were inserted in cells with normally functioning clocks.
Coauthors of the study include Research Associate Professor Yao Xu, Postdoctoral Fellow Ximing Qin and Graduate Student Jing Xiong from Vanderbilt; Assistant Professor Philip Weyman and Group Leader Qing Xu from the J. Craig Venter Institute in Rockville, Md., and Graduate Student Miki Umetani and Professor Hideo Iwasaki at Waseda University in Tokyo.
The research was funded by National Institute of General Medical Sciences grants GM067152 and GM088595, Department of Energy grant DE-FG36-05GO15027, Japanese Society for the Promotion of Science grants 23657138 and 23687002, the Asahi Glass Foundation and the Yoshida Scholarship Foundation.
Visit Research News @ Vanderbilt for more research news from Vanderbilt. [Media Note: Vanderbilt has a 24/7 TV and radio studio with a dedicated fiber optic line and ISDN line. Use of the TV studio with Vanderbilt experts is free, except for reserving fiber time.]
David F. Salisbury | Vanderbilt University
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:06795776-223f-4f31-a572-08607732414a> | 3.5 | 1,420 | Content Listing | Science & Tech. | 37.605481 | 95,570,254 |
Images of the approach of NASA's spacecraft Dawn to the celestial body images suggest features such as large craters on the body's surface
The mission of NASA's Dawn spacecraft to the asteroid belt has entered into its second phase: after a more than year-long stay at the asteroid Vesta and an onward journey through space lasting almost two and a half years, Dawn is now quickly approaching the dwarf planet Ceres.
Ceres in sight: the camera system onboard of spacecraft DAWN captured this image of the dwarf planet from a distance of 380,000 kilometres, this corresponds roughly to the distance between the Earth and the moon. After careful image processing, features on the surface of Ceres become quite clear.
Current images already reach an image contrast surpassing all previously known images of Ceres and show first surface features such as craters. The camera system on board was developed under the lead of the Max Planck Institute for Solar System Research.
The dwarf planet Ceres is a mysterious world, about which little is known. With a diameter of about 950 kilometers and a nearly spherical shape Ceres is more reminiscent of a planet than of the much smaller and irregularly shaped asteroids. Scientist deem it possible that 4.5 billion years ago, Ceres was on the best way to becoming a full-fledged planet – and got stuck in the middle of this evolution. Thus, in Ceres an early state of our solar system is preserved. In addition, the body's composition may well be as fascinating as its past: beneath the surface researchers suspect a frozen or maybe even liquid layer of water.
In the current images Ceres covers 27 pixels. “Already, the images hint at first surface structures such as craters”, says Dr. Andreas Nathues from the MPS, Framing Camera Lead Investigator. A striking bright spot can also be discerned. After careful image processing, these structures become even clearer. Due to the optical design of the camera system, the data surpass all previously known images in the resolution of these details. “We have identified all of the features seen by Hubble on the side of Ceres we have observed, and there are also suggestions of remarkable structures awaiting us as we move even closer,” says Nathues.
"It is exciting to see the surface of a new world slowly come into view," said Dr. Mark Sykes, CEO of the Planetary Science Institute in Tucson (USA), and a member of the Dawn Science Team. "Just confirming features observed by Hubble ten years earlier is important. With the recent detection of water vapor emission by Herschel Space Observatory, we will be looking for evidence of cryovolcanism and other processes to explain it.”
The researchers soon want to check whether Ceres is accompanied by smaller moons, and use the Framing Cameras’ color filters to get a first impression of the surface composition. "We are on the verge of testing hypotheses about an ice-rich surface resulting in relaxed equatorial craters and seeing if there are tectonics and other structures that will give us clues about interior oceans.”, says Nathues.
In September 2007 the Dawn spacecraft embarked on its journey to the asteroid belt which lies between the orbits of Mars and Jupiter. In 2011, the mission reached the asteroid Vesta and accompanied it for more than a year. MPS-scientists have succeeded in creating precise color maps of the asteroid and proven, among other things, that some materials on its surface did not originate from Vesta itself, but reached the asteroid by means of impacts. Since September 2012 Dawn has been en route to Ceres. After the camera system has pointed its gaze at starfields for more than two years, it is now again obtaining images of a target object on a regular basis.
The Dawn mission to Vesta and Ceres is managed by NASA’s Jet Propulsion Laboratory for NASA's Science Mission Directorate (SMD), Washington. It is a project of the Discovery Program, managed for SMD by NASA'sMarshall Space Flight Center, Huntsville, Ala. The University of California, Los Angeles, is responsible for overall Dawn mission science. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.
The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Göttingen, Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The framing camera project is funded by the Max Planck Society, DLR, and NASA.
Dr. Birgit Krummheuer
Max Planck Institute for Solar System Research, Göttingen
Phone: +49 551 384979-462
Fax: +49 551 384979-240
Dr. Andreas Nathues
Framing Camera Lead Investigator
Phone: +49 551 384979-433
Dr. Birgit Krummheuer | Max Planck Institute for Solar System Research, Göttingen
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
Theorists publish highest-precision prediction of muon magnetic anomaly
16.07.2018 | DOE/Brookhaven National Laboratory
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences
16.07.2018 | Physics and Astronomy | <urn:uuid:2390978a-4d11-4dcf-b97c-7cc2cc90584a> | 3.34375 | 1,676 | Content Listing | Science & Tech. | 42.635858 | 95,570,255 |
The growing problem of changing environmental conditions caused by climate destabilization is well recognized as one of the defining issues of our time. The root problem is greenhouse gas emissions, and the fundamental solution is curbing those emissions. Climate geoengineering has often been considered to be a last-ditch response to climate change, to be used only if climate change damage should produce extreme hardship. Although the likelihood of eventually needing to resort to these efforts grows with every year of inaction on emissions control, there is a lack of information on these ways of potentially intervening in the climate system. As one of a two-book report, this volume of Climate Intervention discusses albedo modification - changing the fraction of incoming solar radiation that reaches the surface. This approach would deliberately modify the energy budget of Earth to produce a cooling designed to compensate for some of the effects of warming associated with greenhouse gas increases. The prospect of large-scale albedo modification raises political and governance issues at national and global levels, as well as ethical concerns. Climate Intervention: Reflecting Sunlight to Cool Earth discusses some of the social, political, and legal issues surrounding these proposed techniques. It is far easier to modify Earth's albedo than to determine whether it should be done or what the consequences might be of such an action. One serious concern is that such an action could be unilaterally undertaken by a small nation or smaller entity for its own benefit without international sanction and regardless of international consequences. Transparency in discussing this subject is critical. In the spirit of that transparency, Climate Intervention: Reflecting Sunlight to Cool Earth was based on peer-reviewed literature and the judgments of the authoring committee; no new research was done as part of this study and all data and information used are from entirely open sources. By helping to bring light to this topic area, this book will help leaders to be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.
|Publication date:||31st May 2015|
|Author:||Committee on Geoengineering Climate: Technical Evaluation and Discussion of Impacts, National Research Council, Board on Atmosphe|
|Publisher:||National Academies Press|
|Categories:||Meteorology & climatology,| | <urn:uuid:65133836-bf43-4abb-9f2b-b0e97a417084> | 2.65625 | 460 | Product Page | Science & Tech. | 11.428077 | 95,570,256 |
Working with Ren’Py:
- Part 1: Downloading and Configuring
- Part 2: Editing and Creating Characters
- Part 3: Scenes and Showing Images
- Part 4: Menus, Labels, and Jumps
- Part 5: Variables and Conditional Statements
- Part 6: Transitions
- Part 7: Building Distributions
- Part 1: Screen Language
- Part 2: Position Style Properties
- Part 3: Animation and Transformation Language
- Part 4: Text and Button
- Part 5: Bar and VBar
- Part 6: Textbutton and Imagebutton
- Part 7: Input, Key, and Mousearea
Ren’Py is a engine for creating visual novels. It comes with a suite of tools for taking code and transforming it into programs that can be run on Windows, Mac, Linux, and even, with a little more work, mobile platforms like Android and iOS.
Beyond the showing of text and images, Ren’Py can also be extended through introducing new user interface elements, changing its defaults images, and combining Python with its own code to create even more interactive projects.
Animation and Transformation Language
Much like the screen language of Ren’Py is used to arrange elements, there is also an animation and transformation language (ATL) used to create and change other displayables. Serving as a way to create custom effects, the ATL in Ren’Py can be used to build complex animations and interactions using position properties and other special keywords.
Animation (ATL Blocks with Images)
The animation and transformation language can be used with images to create ATL Blocks, sets of rules that apply to or change existing displayables and then produce a new one.
To create a simple, two-frame animation in Ren’Py, for example, two images can be switched with the pause keyword to show an image, stop for a second, show a second image, pause, and then loop again using the repeat keyword.
In the above example, pause and repeat are two of the special keywords used in the animation and transformation language. The first, pause, is a warper and the second, repeat, is a type of transformation.
A warper is special type of function for changing things over time. Examples include pause, linear, ease, and the pair of easein and easeout. (Many others also exist.)
The repeat statement restarts the block in which it is a part. It can also loop a limited number of time when given a number.
Transformation are created through the keyword transform and can be used as part of other displayables and screens. Like image blocks, they can also be combined with other statements and warpers.
The transform ctc_appear uses the alpha transform property with the pause and linear warpers.
To use a transform with a screen, it is used through the at keyword. Containers in a screen are shown at a transform.
Chaining Animations and Transformations
The contains statement can be used to combine animations and transformations. After creating a transform, it can be contained in another another block. When used in an image block, for example, showing the image will trigger not only the contained transformation, but whatever additional statements are within its own block. | <urn:uuid:49566681-666b-4d07-afa6-62aa2619a235> | 2.84375 | 675 | Tutorial | Software Dev. | 41.040988 | 95,570,293 |
Eastern barred bandicoots were once common in Victoria, but foxes and other threats have decimated numbers so badly that they only remain in captivity
at three fenced reserves and on one small island.
The low numbers have resulted in low genetic diversity which is now a threat to plans to rebuild numbers in breeding programs in order to reintroduce them back to areas where foxes have been eradicated.
A partnership between Mount Rothwell, the Threatened Species Recovery Hub of the National Environmental Science Programme and others is addressing the issue with an innovative breeding program.
Threatened Species Recovery Hub researcher Dr Andrew Weeks says that while the approach called ‘gene pool mixing’ is relatively new within conservation programs it is the kind of thing that has been happening in agricultural programs for years.
“Basically we are bringing Eastern Barred Bandicoots from Tasmania and crossing them with Victorian animals in order to introduce new genes to the Victorian bandicoot population,” said Dr Weeks, from the University of Melbourne who are a partner in the Threatened Species Recovery Hub.
“Improving the genetic diversity will be really important for avoiding problems associated with inbreeding.
“The added genetic diversity is also important for giving the bandicoots a chance to adapt to future challenges, like climate change.
Image: One of the young Eastern Barred Bandicoot hybrids bred at Mt Rothwell. Photo: Mt Rothwell.
Ms Annette Rypalski, the Manager of the Mt Rothwell centre said that so far the initial trial of crossing five Tasmanian bandicoots with Victorian animals has gone extremely well.
“So far we had nine successful litters, with juveniles beginning to emerge from their mother’s nests. Interestingly, the average number of young from each litter appears to be higher than the average litter size for Victorian only parents.
“We are carefully monitoring the health of all of the animals, and will also study whether the hybrid offspring show any other differences, like being bigger and having better survival of their young.
“The first hybrid offspring are now almost three months old and we are about to release them into one of our dedicated five hectare semi-wild enclosures.
“Seeing them in a wild setting is magical, because you get the feeling of what things were like before problems like foxes and rabbits arrived,” Ms Rypalski said.
Mt Rothwell, 45km west of Melbourne, is a privately owned 453 ha conservation reserve surrounded by 11km of predator proof fence. The centre is home to free-living populations of some of Victoria’s most endangered species.
The research is part of the Threatened Species Recovery Hub which undertakes research to support the recovery of Australia’s threatened species.
The Hub is a collaboration between 10 of Australia’s leading Universities and the Australian Wildlife Conservancy, and receives support from the Australian Government’s National Environmental Science Programme.
Available for interview – Dr Andrew Weeks, The University of Melbourne, firstname.lastname@example.org, 0401 289 165
Media support - Jaana Dielenberg, TSR Hub Science Communication Manager, 0413 585 709, email@example.com
Photos and night vision video of the bandicoots at Mt Rothwell is available in dropbox to accompany this story. Photographers must be credited. Do not add to stock libraries
Top image: Eastern Barred Bandicoot, Photo: JJ Harrison_CC BY SA 3.0
Most people know that cats kill many birds and mammals, but they also have impacts on less charismatic species.
Australian cats are killing about 650 million reptiles per year, according to new research published in the journal Wildlife Research.
You have to be pretty lucky to make a living by combining your passion and interests, and that’s exactly how Dr Daniel White feels about his current state of affairs. Dan began his career studying genes, and has since applied his science to saving species. Here he describes how.
The TSR Hub recognises that outcomes for threatened species will be improved by increasing Indigenous involvement in their management. In response to this, the Hub is guided by an Indigenous Reference Group and has a number of projects across Australia that are collaborating with Indigenous groups on threatened species research on their country.
A new contagious fungal plant disease has entered Australia, myrtle rust. It’s highly mobile, can reproduce rapidly and is infecting many species across a broad geographic range. Containment and eradication responses have so far been unsuccessful.
Australia is losing large old hollow-bearing trees in our mountain ash forests due to logging, fires and climate change. A team at the Australian National University have been investigating the importance of these trees, the implications of their loss and things we can do to ensure we have enough mountain giants for the future. | <urn:uuid:bcf3d7e1-f60b-4a58-bbe9-84661fe4c80a> | 3.4375 | 1,008 | News Article | Science & Tech. | 33.532658 | 95,570,306 |
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"How to Observe the Sun Safely, 2nd Edition" gives all the basic information and advice the amateur astronomer needs to get started in observing our own ever-fascinating star. Unlike many other astronomical objects, you do not need a large telescope or expensive equipment to observe the Sun. And it is possible to take excellent pictures of the Sun with today's low-cost digital cameras! This title concentrates on providing practical, on-the-spot advice to the amateur astronomer who is interested in observing the Sun, using commercially available equipment. This book surveys what is visible on the Sun, before describing how to record solar features and measure solar activity levels. There is also an account of how to use H-alpha and Calcium-K filters to observe and record prominences and other features of the solar chromosphere, the Sun's inner atmosphere. Because we are just entering a period of high activity on the Sun, following a long, quiet period, many more amateur astronomers will become interested in observing it. The second edition includes an update of Chapter 2 to reflect advances in solar observing equipment since 2002, and a section on building a solar projection box, originally included in the main body of this chapter has been moved to Appendix A. Also Chapter 6 thru 8 have been completely revised to give amateur astronomers advice on how to use film to photograph the Sun, and how to use digital cameras. This new edition also includes more than twice as many illustrations as the first and almost half of them new images. | <urn:uuid:2a3388d2-826b-45a1-b718-7fec6108bf44> | 3.046875 | 317 | Product Page | Science & Tech. | 26.21 | 95,570,329 |
Cell function correlates strongly with structure or morphology. For example, cellular activities such as differentiation and apoptosis can be distinguished by changes in morphology. Consequently, morphological features provide powerful and often critical markers for cell assay and clinical applications.1,2 Because of the complexity in cell morphology, conventional microscopy methods have to be used, which are labor-intensive for data acquisition and analysis. Therefore, it is highly desired to develop an automated method for rapid assay of large populations of single cells about their morphology with flow cytometry technology. Conventional and commercially available flow cytometers, however, are designed to acquire fluorescence signals or images as the major source of information for rapid cell assay. This approach, however, provides very limited information on cell morphology. The three-dimensional (3-D) morphology and molecular polarization information of single cells have been shown to correlate strongly with the spatial distribution of scattered light from the cell illuminated by highly coherent light.126.96.36.199.–8 We have previously developed a flow cytometry method for rapid acquisition of cross-polarized diffraction image pairs with two cameras.910.11.12.–13 The new method, termed as polarization diffraction imaging flow cytometry (p-DIFC), has been shown to be capable of distinguishing cell lines of high similarity in their 3-D morphology.10
Despite the capacity for morphology-based cell assay, a significant problem still exists that affects performance of the p-DIFC method using conventional CCD cameras. The images of the cells are acquired under the flow condition, which could markedly reduce the image contrast by motion blur (MB) with these cameras. The image blurring makes it harder to perform accurate image analysis and cell assay. A time-delay-integration (TDI) imaging method can be applied to control and reduce the MB. A TDI camera has multiple lines of pixels whose charges are transferred at a speed controlled with an external clock pulse-train. If the charge transfer speed of pixel lines is equal to the speed of the moving image, MB can be eliminated.14 A TDI camera has been developed and used to investigate the effect of MB on characteristic parameters extracted from cross-polarized diffraction images of microspheres and biological cells using different image-processing algorithms.15
In this report, we focus our attention on the quantitative analysis of the MB in measured diffraction images in the frequency domain with the modulation transfer function (MTF). The MTF-based analysis enables us to validate a tool for numerically “blurring” diffraction images acquired with the matched speeds between line transfer and moving image in p-DIFC measurements, and investigate the effect of MB on pattern analysis of the images from the same cell. We have also proposed a single parameter of frequency modulus for quantification of MB based on the Fourier transform of the measured diffraction images. The MB analysis was carried out on measured diffraction images acquired with MCF-7 and K562 cells moving at seven different speeds. These results provide insights into the effect and evaluation of MB to further improve the p-DIFC method with the TDI camera, and allow the use of the average frequency modulus to assess MB quantitatively.
Motion Blur Assessment
We designed and developed a TDI-camera-based imaging system for variation and elimination of MB in the acquired diffraction images from the moving cells.15 Quantitative assessment of MB is needed to characterize blurring in diffraction images. Often, a spatial domain image analysis approach is used for blur assessment in conventional image data. But the diffraction images concerned here carry light scattering noise, and the frequency domain approach with MTF becomes more suitable for MB assessment.
MB could occur when the object moves relative to the imaging sensor. In this study, the diffraction images from the moving object are acquired at off-focus position to improve image contrast.16,17 A diffraction image acquired at an off-focus position with MB can be described in frequency domain by its spatial frequency spectrum as17 Our purpose here is to analyze the effect of MB given by the modulus of from the measured diffraction images and quantify MB with a TDI camera as the imaging sensor.
The degree of MB can be determined from the distance and orientation of the image’s movement on the image sensor during an exposure time . For our study, the cell and its image on the camera sensor move along the -direction (see Fig. 2), while the incident beam propagates along the -axis. Therefore, the degraded image in terms of incident light energy can be expressed as integration of a series of light rays shifting through different positions of or1819.–20 Figure 1 presents four cases of calculated by Eq. (5) for imaging systems with TDI cameras and different mismatch ratios, and a comparison to a system with a conventional CCD camera of the same image speed and equivalent exposure time. These results show quantitatively that the TDI camera can reduce and eliminate MB effectively and produce images of larger bandwidths than those acquired with conventional CCD cameras.
Figure 1 shows that the MB can be eliminated by synchronization at with a TDI camera, and the remains maximized at 1 for all frequencies. Once the mismatch ratio starts to increase, MB occurs with the values of markedly reduced in the frequency domain. We can quantify the frequency decrease of a blurred image to evaluation of the degree of MB by an averaged modulus of its Fourier transform , defined as
Polarization Diffraction Imaging Flow Cytometry System With One Time-Delay-Integration Camera
Figure 2 shows the p-DIFC system constructed for this study based on previous research.10,12,21 A cw laser of 532 nm in wavelength (MGL-III-532-100 mW) is focused by two cylindrical lenses on the core fluid in an elliptical spot with major diameter of about 300 μm along the -axis and minor diameter of about , and the polarization and power of the incident beam are controlled by one half-wavelength plate and one Glan prism. The coherent side-scatter by the illuminated cells is collected by an infinity-corrected, nontelecentric objective lens (378-805-3, Mitutoyo), followed by a Wollaston prism (LSP-3A14, Laser Institute, QFNU) of aperture. The p-polarized and s-polarized scattered light after the Wollaston prism, separated by 10 deg in directions, are focused with a tube lens of focal length onto the TDI-CCD sensor (S10201-4 Hamamatsu). The imaging system can be translated along the -axis toward the flow chamber from the focused position of at which the core fluid is on the object plane of the imaging system.
Different from conventional CCD cameras, the TDI cameras allow synchronization between the cell speed and line-pixel transfer frequency as discussed above. To determine cell speed, we measured the flow rate of the sheath fluid, which is proportional to the cell speed 22 and can be controlled by the sheath fluid pressure. The line-pixel transfer frequency of the TDI camera was set to be 16.67 KHz with an in-house developed software. Given the number of pixel lines of the TDI-CCD sensor as 128 and the sensor height as 1.536 mm, the synchronous image speed can be calculated from
We used polystyrene microspheres of diameter and a conventional CCD camera (Lumenera Lt225) of a 6-mm height () sensor for flow-speed measurement. The shadow lengths of the imaged microspheres, proportional to the exposure time, were used to determine the speed of microspheres. The exposure time of the conventional camera was set to 3 ms, so the image speed can be determined by
For the objective and tube lens of focal length , the magnification of the imaging system () is given by 18.75, and the microspheres’ speed or core-fluid speed is given by
After sample injection into the core-fluid reservoir, the particle or the core-fluid speed was adjusted by the sheath fluid pressure and measured by the shadow lengths. For three different speed settings, five measurements were performed to obtain the averaged core-fluid speed with an interval of 20 min between measurements. The averaged values and standard deviations show that the maximum relative change is 2%, which indicates that the flow speed was stably controlled.
Diffraction Image Acquisition
After the measurement of flow speed with microspheres, two cancer cell lines were used to investigate the effect of MB on diffraction images. The human breast carcinoma cell line MCF-7 and chronic myelogenous leukemia cell line K562 (ATCC, Manassas, Virginia) were chosen for this study due to their large difference in morphological structures. The cells were maintained in the RPMI 1640 culture medium supplemented with 10% fetal bovine serum. The adherent MCF-7 cells were detached from culture flask with trypsin-EDTA to prepare suspension cell samples in culture medium before each measurement. Cross-polarized diffraction images of the cells were acquired at the off-focus position of with seven different flow speeds.
Simulated Motion Blur in Diffraction Images
To accurately investigate the effect of MB on cell classification, it is highly desired to obtain diffraction images with different degrees of MB from the same cell. This is very difficult, if not impossible, to achieve in p-DIFC measurements, because no two cells are identical even if they belong to the same type. For this purpose, we applied an existing filtering algorithm in MATLAB® (7.2, MathWorks) with simulated MB in diffraction images acquired with a TDI camera under the condition of zero speed-mismatch ratio or . The applied MATLAB® algorithm (fspecial) convolutes an input image with a kernel for window-smoothing the input image over a length of pixels along a specified direction.
Results and Discussion
The MB similarly affects the different polarized diffraction images. The raw diffraction images from the TDI camera were cropped to obtain pixels near the maximum pixel of each polarized diffraction image for analysis. Figures 3(a) and 3(b) present examples of p-polarized diffraction images acquired at three different values of core-fluid speed with one TDI camera and similar images with a conventional CCD camera of exposure time and . It is clear that the diffraction images acquired with the TDI camera at or show severe degradation due to MB, which is also the case for the one acquired with a conventional CCD camera. In contrast, the images acquired with the TDI camera at the zero speed-mismatch ratio of display minimal blur. Figure 3(c) further presents two diffraction images with numerically simulated MB using different values of for pixel numbers of window-smoothing along the vertical direction on the TDI-acquired image shown in Fig. 3(a). One can observe that the two related images in Figs. 3(b) and 3(c) with versus pixels or versus 48 pixels present similar MB even though they were acquired from different cells.
To analyze the p-polarized diffraction images in the frequency domain, 2-D Fourier transforms were performed on to obtain , and the results of normalized by the central peak or DC component are shown in Fig. 4 with the vertical -axis corresponding to the vertical -axis of motion in images of Fig. 3. Since the Fourier components are concentrated in the low-frequency range or the central region, the spectral images in Fig. 4 present only the middle part of the 2-D frequency image with pixels and values of central peaks as 255. Comparison of the images in Figs. 4(a) and 4(b) indicates clearly that MB reduces the frequency information along the -axis in frequency domain and agrees well with the MTF analysis. The results of frequency analysis of the p-DIFC image data acquired with the TDI camera can also be compared with those acquired with the conventional CCD camera in Fig. 4(a), which shows that larger frequency band or information can be obtained with the TDI camera than with the conventional CCD. Furthermore, comparison of the spectral images in Figs. 4(b) and 4(c) proves that the simulated MB on diffraction images acquired with produces distributions in frequency space similar to those in measured images with . It should be noted that the similarity is achieved with the images acquired from different cells of K562 or MCF-7. These results validate a very useful tool to accurately model the effect of MB on image patterns and cell classification with polarized diffraction images acquired with a TDI camera. A study is underway with this tool to investigate the effects of MB on GLCM parameters extracted from the diffraction images of cells acquired under the condition of zero speed-mismatch.
In addition to the modulus image , one can also quantify MB by a single parameter of averaged frequency modulus defined in Eq. (6). The mean values and standard deviations of were obtained from five randomly selected p-polarized images of pixels at different values of core-fluid speed and are plotted in Fig. 5(a). In the same figure, we also plot the same modulus parameter versus core flow speed from the images obtained with simulated MB performed on those images acquired with zero speed-mismatch by window-smoothing over pixels. It can be seen that both the mean values and standard deviations of spectral amplitude reduce with the increased speed-mismatch, which significantly affects the accuracy of pattern analysis for cell assay and classification. The high similarity between the two sets of curves of diffraction images acquired with a TDI camera at different core flow speed and those by simulated MB shows further that the simulated MB can be used for analysis of MB using only the diffraction images acquired with zero speed-mismatch. We note that the conventional blur evaluation parameter of averaged gradient does not perform well in the case of diffraction images presented in this study. The parameter is typically defined by the following for a given image along the direction of MB or -axis18Fig. 4 are less than 2 pixels and are not sensitive to the speed-mismatch ratio, because the central peak is dominated by the DC noise, which can be observed from the images of plotted in log-scale for in Fig. 4.
Finally, it is interesting to examine whether the MB can be effectively removed by deconvolution. For this purpose, a MATLAB® function (deconvwnr) was applied to the measured diffraction images to perform Wiener-filter-based deconvolution. The deconvolution function requires appropriate selection of three parameters of pixel-smoothing length , direction of motion in degree from the horizontal direction of the blurred image, and value of as the noise-signal-power-ratio (NSPR) to achieve best effect of deblur. The optimized results of deconvolution are shown in Fig. 6 by applying the MATLAB® function on the blurred images acquired with a flow speed of and as presented in Fig. 3(b). One can clearly see that even with the optimized parameters of deconvolution, the MB cannot be fully removed if the speed-mismatch becomes large. Furthermore, the deconvolution calculations are computationally expensive and are difficult to apply for rapid image analysis required in p-DIFC method.
A diffraction imaging method and system with one TDI camera has been developed for acquisition of diffraction images of flowing cells. We performed MTF analysis of the measured diffraction images from two different cancer cell lines and validated a numerical method for the simulation of motion-blurring effects on images acquired with zero speed-mismatch. These results show that the MTF analysis provides an accurate approach for characterization of the MB effect on diffraction images and significant insights on improvement of image analysis by eliminating blur with a TDI camera. We further show that the averaged modulus of a diffraction image in the frequency domain yields a much improved single parameter than does the averaged gradient calculated directly from the diffraction image for the quantification of MB.
The authors would like to thank Dr. Fu Zheng of TJMU for preparing the MCF-7 and K562 cell samples. X. H. Hu acknowledges support by the Tianjin Science and Technology Commission and Y. Feng acknowledges support by the NSFC (Grant Nos. 81171342 and 81201148).
He Wang received his BS degree in biomedical engineering at Shandong University in 2010. His current research interests include biological cell imaging and development of TDI cameras.
Changrong Jin received his BS degree in biomedical engineering at Hebei University of Technology in 2013. His current research interests include microscope imaging and visualization of biological information.
Yuanming Feng is a professor of biomedical engineering at Tianjin University. His research interests include diffraction imaging flow cytometry and measurement technique of radiation-induced apoptosis.
Dandan Qi received her BS degree in biomedical engineering at the Hebei University of Technology in 2013. Her current research interests include diffraction imaging and morphology of biological cells.
Yu Sa received his BS and PhD degrees from Tianjin University, and he is a lecturer in the Department of Biomedical Engineering of Tianjin University. His research interests include instrument development, diffraction imaging, and computational fluid dynamics modeling studies.
Xin-Hua Hu received his BS and MS degrees from Nankai University, Tianjin, China, in 1982 and 1985, an MS degree in physics from Indiana University in 1986, and a PhD in physics in 1991 from the University of California at Irvine. He joined the physics faculty in 1995 and is currently a professor at East Carolina University. His main research interests relate to the investigations of light scattering and their applications in probing tissues and cells. | <urn:uuid:96fa2efa-6f5f-41bc-adbe-0036b30c6795> | 2.5625 | 3,681 | Academic Writing | Science & Tech. | 32.866072 | 95,570,360 |
Today, farming often involves transporting crops long distances so consumers from Maine to California can enjoy Midwest corn, Northwest cherries and other produce when they are out of season locally. But it isn't just the fossil fuel needed to move food that contributes to agriculture's carbon footprint.
New research published in the journal Biogeosciences provides a detailed account of how carbon naturally flows into and out of crops themselves as they grow, are harvested and are then eaten far from where they're grown. The paper shows how regions that depend on others to grow their food end up releasing the carbon that comes with those crops into the atmosphere.
"Until recently, climate models have assumed that the carbon taken up by crops is put back into nature at the same place crops are grown," said the paper's lead author, environmental scientist Tristram West of the Department of Energy's Pacific Northwest National Laboratory. "Our research provides a more accurate account of carbon in crops by considering the mobile nature of today's agriculture."
Carbon, carbon everywhere
Carbon is the basis of life on Earth, including plants. During photosynthesis, plants take in carbon dioxide and convert it into carbon-based sugars needed to grow and live. When a plant dies, it decomposes and releases carbon dioxide back into the atmosphere. After eating plants, animals and humans release the plants' carbon as either carbon dioxide while breathing or as methane during digestion.
But the geography of this natural carbon cycle has shifted with the rise of commercial agriculture. Crops are harvested and shipped far away from where they're grown, instead of being consumed nearby. As a result, agriculturally active regions take in large amounts of carbon as crops grow. And regions with larger populations that consume those crops release the carbon.
The result is nearly net zero for carbon, with about the same amount of carbon being taken in as is released at the end. But the difference is where the carbon ends up. That geography matters for those who track every bit of carbon on Earth in an effort to estimate the potential impacts of greenhouse gases.
Digging into data
Agricultural carbon is currently tracked through two means: Towers placed in farm fields that are equipped with carbon dioxide sensors, and computer models that crunch data to generate estimates of carbon movement between land and the atmosphere. But neither method accounts for crops releasing carbon in areas other than where they were grown.
To more accurately reflect the carbon reality of today's agricultural crops, West and his co-authors combed through extensive data collected by various government agencies such as the Department of Agriculture, the U.S. Census Bureau and the Environmental Protection Agency.
Looking at 17 crops – including corn, soybeans, wheat and cotton – that make up 99 percent of total U.S. crop production, the researchers calculated the carbon content of harvested crops by county for each year from 2000 to 2008.
Next they used population numbers and data on human food intake to estimate, by age and gender, how much carbon from crops humans consume. On the flip side, the co-authors also calculated how much carbon humans release when they exhale, excrete and release flatulence. They did the same analysis on livestock and pets.
But not all food makes it to the dinner table. The researchers accounted for the crops that are lost due to spoilage or during processing, which ranges from 29 percent of collected dairy to as much as 57 percent of harvested vegetables. Beyond food, they determined the amount of carbon that goes into plant-based products such as fabric, cigarettes and biofuels. And they noted how much grain is stored for future use and the crops that are exported overseas.
National crop carbon budget
Combining all these calculations, the researchers developed a national crop carbon budget. Theoretically, all the carbon inputs should equal the carbon outputs from year to year. The researchers came very close, with no more than 6.1 percent of the initial carbon missing from their end calculations. This indicated that the team had accounted for the vast majority of the carbon from America's harvested crops.
The team found overall that the crops take in – and later return – about 37 percent of the U.S.'s total annual carbon dioxide emissions, but that amount varies by region. Carbon sinks, or areas that take in more carbon than release it, were found in the agriculturally active regions of the Midwest, Great Plains and lands along the southern half of the Mississippi River. Regions with larger populations and less agriculture were found to be carbon sources, or areas that release more carbon than they take in. The calculations indicated the Northeast, Southeast and much of the Western U.S. and Gulf Coast were carbon sources. The remaining regions – the western interior and south-central U.S. – flip-flopped between being minor carbon sinks or sources, depending on the year.
Informing policy decisions
Next, West would like his team's methods applied to forestry, which also involves the movement of carbon-containing products from one locale to another. Comprehensive carbon calculations for agriculture and forestry could be used in connection with previous carbon estimates that were based on carbon dioxide sensor towers or carbon computer models.
"These calculations substantially improve what we know about the movement of carbon in agriculture," West said. "Reliable, comprehensive data like this can better inform policies aimed at managing carbon dioxide emissions." This research was funded by NASA through the North American Carbon Program.
REFERENCE: West, T. O., Bandaru, V., Brandt, C. C., Schuh, A. E., and Ogle, S. M.: Regional uptake and release of crop carbon in the United States, Biogeosciences, 8, 2037-2046, doi: 10.5194/bg-8-2037-2011, 2011. Published online Aug. 3, 2011. http://www.biogeosciences.net/8/2037/2011/
Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America's most intractable problems in energy, the environment and national security. PNNL employs 4,900 staff, has an annual budget of nearly $1.1 billion, and has been managed by Ohio-based Battelle since the lab's inception in 1965. Follow PNNL on Facebook, LinkedIn and Twitter.
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Franny White | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Look at the Great Salt Lake and you might think of the vast body of water as lifeless. That’s far from the truth, of course. Not only is the Great Salt Lake home to an incredible number of brine shrimp—fodder for migrating birds looking to refuel—it also boasts microscopic life that’s adapted to the harsh conditions of the super-salty water. They’re called halophiles, and the Natural History Museum of Utah exhibit staff came up with a perfect recipe to help them thrive in an exhibit about the local lake.
There’s no single biological category for halophiles. “Most of them are bacteria,” Museum exhibit services supervisor Will Black said, “but they could also be eukaryotes,” or organisms made up of a cell or cells containing their DNA inside a nucleus. Regardless of their classification, though, Black notes that what makes halophiles distinct is right there in their name: halophile is Greek for “salt-loving.”
The Great Salt Lake is a great place for salt-loving life. “The north arm of the Great Salt Lake is commonly at saturation levels, about 27 percent salt,” Black said, and extreme halophiles are typically found wherever salt in the water reaches over 20 percent. So, with that in mind, Black and the exhibits team set about trying to culture halophiles for the museum’s exhibit.
Getting life to grow in such salty conditions is rough. Using a device called a Winogradsky column, which helps culture bacteria and other microorganisms, Black and colleagues tried to get organisms to grow in high salt conditions like those found naturally in the lake. Barely anything other than green algae grew in the column for the first four tries, but, on the fifth try, halophiles finally thrived, given off by their red color.
The process took months. “I collected water and sediment from the north arm of the lake on October 20, 2017,” Black said, mixing the natural materials with nutrients in the Winogradsky column back at the museum. The special recipe included plenty of base materials for the halophiles to draw from, including sawdust, chalk, dry milk, rice, gypsum, epsom salt, fertilizer, and even Parmesan cheese, among other ingredients. Heated and lit to simulate the proper conditions, and the halophiles began to take hold.
“It’s amazing how red it is,” Black said, which mimics the look of the Great Salt Lake. “The north arm of the lake can be very pink or red at times of the year, and this color comes from the extreme halophiles.” What thrives in the exhibit’s column is a close-up look at the inner life of the famous lake. | <urn:uuid:6a015dc2-4d5c-437f-a699-b9d0fa3bdd63> | 3.25 | 599 | News (Org.) | Science & Tech. | 49.081362 | 95,570,404 |
By Simon Peatman
The Madden-Julian Oscillation (MJO) is one of the most important meteorological phenomena in the tropics. With a timescale of 30–90 days it bridges the gap between weather and climate (Zhang, 2013), potentially providing predictability over several weeks. It consists of large-scale envelopes of, alternately, organized convection and clear skies, propagating slowly (∼5 m s-1) eastwards from the Indian Ocean, through the Maritime Continent, to the Pacific; and an associated planetary-scale circulation. The MJO interacts with several other phenomena, including the El Niño–Southern Oscillation (Tang and Yu, 2008), monsoons (Lavender and Matthews, 2009; Singh et al., 2017), tropical cyclones (Klotzbach, 2014) and the diurnal cycle (Peatman et al., 2014).
In 1971, Roland Madden and Paul Julian published a study of 10 years of radiosonde data from Canton Island, Kiribati (Madden and Julian, 1971), noting a “very pronounced maximum” in the co-spectrum of zonal wind at 850 and 150 hPa, with period 41–53 days (Figure 1). They hypothesized the cause to be a “large circulation cell oriented in zonal planes and centred in the mid-Pacific”, thousands of kilometres in scale and located near the equator. The following year a further study (Madden and Julian, 1972) analysed data from 25 stations throughout the tropics (and beyond) and determined that the oscillation was indeed a zonally-oriented planetary-scale circulation, confined to 10°N–10°S, which propagates from the Indian Ocean to the Pacific (Figure 2).
Figure 1: Co-spectra of u850 and u150 (dashed, left axis); and surface pressure and u850 (solid, right axis) from radiosonde data from Canton Island, Kiribati. From Madden and Julian (1971).
Figure 2: Schematic diagram of the MJO circulation and convection, with eastward propagation indicated between successive panels. Tropopause height and pressure anomaly are sketched at the top and bottom respectively of each panel. From Madden and Julian (1972).
However, it has recently emerged that although Madden and Julian were unaware of this oscillation before their 1971 paper, they were not the first to have demonstrated its existence. As described by Li et al. (in press), a study published in Chinese eight years earlier (Xie et al., 1963) found a 40–50 day oscillation in radiosonde data from several tropical locations. The Xie study, devoted to typhoon genesis, noted “[t]here is a quite definite relationship between the time, location and frequency of typhoon genesis and the location and strength of the basic flow in the low latitudes”, thus not only discovering the intraseasonal oscillation but also its relation to tropical cyclogenesis in one paper! They further suggested the “oscillation might be helpful for the extended-range forecast of initiation and development of typhoons”, a fact which is still to be fully exploited by forecasters today.
Xie et al. (1963) plotted time series of u700 from three weather stations, shown from east to west down the page in Figure 3: Thiruvananthapuram (Kerala, India), Ho Chi Minh City (Vietnam) and Zamboanga (Philippines). These were hand-drawn and had no temporal filtering applied to the data. They noted “[t]here is a consistent phase change of the zonal wind from Station 43371 [Thiruvananthapuram] to Station 98836 [Zamboanga]. When the westerlies intensified in India, they also intensified in south-east Asia, with a slight temporal delay… The change of zonal wind with time at these stations exhibited a wave-like oscillatory characteristic, with an average oscillatory period of around one-and-a-half months.” We can now recognize this as the MJO circulation, with intraseasonal timescale and eastward propagation.
Figure 3: Time series of u700 against month from three stations (rows; longitudes overlaid in blue — see main text for details) during 1958–1960 (columns). Black dots denote typhoons. From Xie et al. (1963). Red arrows added by Li et al. (in press) to highlight intraseasonal periods.
The Real-Time Multivariate MJO (RMM) indices (Wheeler and Hendon, 2004), computed from OLR and zonal wind, are widely used to plot MJO propagation but date to 1974 only. However, Oliver and Thompson (2012) reconstructed the indices back to 1905 by regressing against surface pressure data. Using the reconstructed indices we can plot the propagation events documented by Xie et al. (1963; Figure 4). There is reasonable agreement – e.g. anomalous low-level westerlies in July 1958 (Figure 3), as seen in Figure 2A, roughly correspond to phases 5–6 (Figure 4b); while anomalous low-level easterlies in late July–August, as seen in Figures 2C–E, roughly correspond to phases 8–2.
The Xie paper is not widely known, mainly because it was published in Chinese. Who knows how many other important papers may exist in non-English journals, unknown to the wider academic world? The analysis of the intraseasonal oscillation by Xie et al (1963) was less detailed than that by Madden and Julian (1971, 1972), and it was unarguably the latter brace of papers which brought the oscillation to the attention of the tropical community. However, if it should come to be known as the XMJO, in recognition of Xie et al.’s pioneering study of 1963, I for one would not complain.
Figure 4: (a) MJO diagram showing the location of active convection in each phase. (b-d, below) MJO events for the times shown in Figure 3, using the reconstructed RMM indices of Oliver and Thompson (2012).
Klotzbach, P. J., 2014. The Madden–Julian Oscillation’s Impacts on Worldwide Tropical Cyclone Activity. J. Climate, 27, 2317–2330.
Lavender, S. L. and Matthews, A. J., 2009. Response of the West African Monsoon to the Madden–Julian Oscillation. J. Climate, 22, 4097–4116.
Li, T., Wang, L., Peng, M., Wang, B., Zhang, C., Lau, W. and Kuo, H.-C. (in press), A Paper on the Tropical Intraseasonal Oscillation Published in 1963 in a Chinese Journal. Bull. Amer. Meteor. Soc..
Madden, R. A. and Julian, P. R., 1971. Detection of a 40–50 Day Oscillation in the Zonal Wind in the Tropical Pacific. J. Atmos. Sci., 28, 702–708.
Madden, R. A. and Julian, P. R., 1972. Description of Global-Scale Circulation Cells in the Tropics with a 40–50 Day Period. J. Atmos. Sci., 29, 1109–1123.
Oliver, E. C. J. and Thompson, K. R., 2012. A Reconstruction of Madden-Julian Oscillation Variability from 1905 to 2008. J. Climate, 25, 1996–2019.
Peatman, S. C., Matthews, A. J. and Stevens, D. P., 2014. Propagation of the Madden–Julian Oscillation through the Maritime Continent and scale interaction with the diurnal cycle of precipitation. Q. J. R. Meteorol. Soc., 140, 814–825.
Singh, M., Bhatla, R. and Pattanaik, D. R., 2017. An apparent relationship between Madden–Julian Oscillation and the advance of Indian summer monsoon. Int. J. Climatol., 37, 1951–1960.
Tang, Y. and Yu, B., 2013. MJO and its relationship to ENSO. J. Geophys. Res., 113, D14106.
Xie, Y.-B., Chen, S.-J., Zhang, I.-L., and Hung, Y.-L., 1963. A preliminarily statistic and synoptic study about the basic currents over southeastern Asia and the initiation of typhoons. Acta Meteorologica Sinica, 33, 206–217.
Wheeler, M. C. and Hendon, H. H., 2004. An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction. Mon. Wea. Rev., 132, 1917–1932.
Zhang, C., 2013. Madden–Julian Oscillation: Bridging Weather and Climate. Bull. Amer. Meteor. Soc., 94, 1849–1870. | <urn:uuid:b6104908-b00c-4364-b79c-d81182d630f8> | 3.546875 | 1,913 | Academic Writing | Science & Tech. | 63.995089 | 95,570,422 |
- Open Access
Tropospheric ozone column retrieval from OMI data by means of neural networks: a validation exercise with ozone soundings over Europe
© Di Noia et al.; licensee Springer. 2013
Received: 15 July 2011
Accepted: 18 January 2013
Published: 19 February 2013
The retrieval of the tropospheric ozone column from satellite data is very important for the characterization of tropospheric chemical and physical properties. However, the task of retrieving tropospheric ozone from space has to face with one fundamental difficulty: the contribution of the tropospheric ozone to the measured radiances is overwhelmed by a much stronger stratospheric signal, which has to be reliably filtered. The Tor Vergata University Earth Observation Laboratory has recently addressed this issue by developing a neural network (NN) algorithm for tropospheric ozone retrieval from NASA-Aura Ozone Monitoring Instrument (OMI) data. The performances of this algorithm were proven comparable to those of more consolidated algorithms, such as Tropospheric Ozone Residual and Optimal Estimation. In this article, the results of a validation of this algorithm with measurements performed at six European ozonesonde sites are shown and critically discussed. The results indicate that systematic errors, related to the tropopause pressure, are present in the current version of the algorithm, and that including the tropopause pressure in the NN input vector can compensate for these errors, enhancing the retrieval accuracy significantly.
Tropospheric ozone is a key player in a number of atmospheric processes that affect both climate and air quality. Its climatic impact is expressed by a radiative forcing of about 0.35 W/m2, as estimated by the intergovernmental panel on climate change (IPCC) fourth assessment report . Such radiative forcing makes tropospheric ozone the fourth atmospheric greenhouse gas by importance, following water vapor, carbon dioxide and methane . As for the air quality, tropospheric ozone has both a positive and a negative role; its positive role lies in the fact that it acts as a precursor of the idroxyl radical, which is able to remove several pollutants from the middle troposphere through oxidation reactions ; its negative role lies in its toxicity for both humans and crops when it reaches high concentrations near the Earth’s surface [3, 4].
Monitoring the concentration of tropospheric ozone from a satellite platform offers the advantage of a temporally and spatially continuous observation, allowing the identification of long-range transport processes [5, 6], and the generation of temporally extended records, which are useful for the investigation of long term trends [7–9].
In the last two decades, the advent of a new generation of satellite hyperspectral atmospheric sounders, which make simultaneous radiance measurements with high spectral resolution and sampling rate, covering the ultraviolet (UV), visible (VIS) and infrared (IR) spectral ranges, has greatly enhanced our capability to detect and quantify several tropospheric trace gases, including ozone .
Among the tropospheric gases that can be monitored from space, ozone is one of the most problematic ones. In fact, the contribution of tropospheric ozone to the measured radiance signal must be separated from the contribution of stratospheric ozone, which is much larger, due to the fact that most of the atmospheric ozone is found in the stratosphere. In order to accomplish this, several techniques were developed during the last 20 years. The rationale behind the first tropospheric ozone retrieval algorithms was to isolate the stratospheric ozone column by means of limb measurements [11, 12] or total ozone retrievals over high-altitude clouds [13, 14], and then subtract it from a co-located or neighboring measurement of the total ozone column. In the case of limb measurements, the separation between stratosphere and the troposphere is achieved thanks to the limb viewing geometry, whose line of sight does not encounter the atmospheric layers located beneath the upper troposphere/lower stratosphere (UTLS). In the case of measurements over high clouds, it is assumed that such clouds shield the underlying troposphere, and that the stratospheric ozone field does not have a significant horizontal variability within a certain number of neighboring pixels. If these assumptions hold true, it is possible to say that total ozone column retrievals over high altitude clouds actually represent stratospheric columns, which can be subtracted from total ozone columns retrieved over neighboring clear-sky pixels to yield an approximated value for the tropospheric ozone column. This type of approach has been mainly used over the Tropics, where high convective clouds are more frequent.
During the last decade, the improved sensitivity to the lower tropospheric layers that was achieved with new satellite instruments—including the Global Ozone Monitoring Experiment (GOME), the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and the Ozone Monitoring Instrument (OMI)—has enabled the development of algorithms that directly derive tropospheric ozone information from ozone profiles retrieved through an optimal estimation (OE) scheme [15–18].
OE retrieval schemes make use of forward radiative transfer models (RTMs), which are computationally intensive and require a consistent characterization of the whole atmospheric state, including the properties of clouds, aerosols and spectrally interfering trace gases (i.e., gases that have absorption features in the same spectral region as the trace gas of interest), which in most cases must be assumed a priori. This can cause the retrieval process to be slow and sensitive to wrong a priori assumptions, as well as to forward modeling errors .
An alternative approach to the direct determination of tropospheric ozone from satellite measurements is represented by neural network (NN) algorithms. Instead of explicitly using a forward model, NNs attempt to approximate the relationship between the measured radiance and the atmospheric parameter of interest directly by means of a nonlinear regression on a given training set . In the case of atmospheric retrievals, the training set for a NN algorithm will consist of simultaneous realizations of the radiometric measurements and the geophysical process of interest. In addition, other parameters that can be useful to better constrain the relationship between the radiance measurements and the parameter to be retrieved (e.g., information on the observation geometry, other atmospheric parameters) can be given as inputs to a NN. For the training of a NN to be successful, a large and comprehensive training set must be built, possibly covering all the atmospheric situations that can be encountered in reality (e.g., heavy pollution events, tropopause folds).
Although the training process can be slow, a trained NN is able to operate very quickly, which is an attractive feature for operational retrievals. Furthermore, NNs allow to handle heterogeneous data in an easy way. This is an important feature when a complex model relating a large number of different quantities (e.g., atmospheric optical thickness, tropopause height and tropospheric ozone column) cannot be explicitly formulated, although it is known that a physical correlation between these quantities exists. On the other hand, a disadvantage of NNs lies in the difficult interpretation of their results. Such difficulty arises from the fact that the physical relationships underlying the retrieval process are represented by a NN in a purely numerical form, without any reference to the causal relationships that link the observed data. Because of this, NN retrieval schemes do not provide diagnostics that measure the relative contribution of each atmospheric layer to the retrievals and the number of independent pieces of information provided by the algorithm—such as the averaging kernels and the degrees of freedom for signal (DFS) —whose computation requires an RTM.
NNs have been successfully applied in several branches of atmospheric remote sensing , including retrievals of ozone profiles [22, 23], total ozone and tropospheric ozone column [25–27]. Recently, a new NN algorithm for tropospheric ozone retrieval over the northern mid-latitudes from OMI data—named OMI tropospheric ozone column neural network (OMI-TOC NN)—has been proposed . In the present article, the results of a validation of this latter algorithm with ozone soundings performed at a number of European stations are presented.
The article is organized as follows. In Section 2, a brief overview of the NASA Aura-OMI mission is given. In Section 3, a description of the OMI-TOC NN algorithm is given. In Section 4, the ozonesonde sites used for this validation and the co-location criteria are described. In Section 5, the validation results are shown, the temporal trends in the retrieval errors are discussed, and the importance of a parameter which was not originally used in the NN input vector—namely, the tropopause pressure—is demonstrated. The conclusions are drawn in Section 7.
2 The NASA-Aura mission and the OMI instrument
The NASA EOS Aura mission , started in 2004 with the launch of the homonymous satellite, aims at the study of the atmospheric composition, chemistry and dynamics. The scientific instrumentation onboard the Aura satellite includes the OMI instrument, as well as the tropospheric emission spectrometer (TES), the microwave limb sounder (MLS) and the HIgh resolution dynamics limb sounder (HIRDLS).
The OMI instrument is a nadir UV/VIS imaging spectrometer, that measures direct and backscattered solar radiation in three channels; namely, the UV1 channel (270–310 nm), the UV2 channel (310–365 nm) and the VIS channel (365–500 nm). The UV1 and UV2 channels are the most important ones for ozone monitoring, because they cover the Hartley and Huggins absorption bands of the ozone molecule. The VIS channel is used for observations of clouds, aerosols and other atmospheric trace gases (e.g., nitrogen dioxide, formaldehyde). However, it does not cover the region of the ozone Chappuis absorption bands where the ozone absorption cross section is largest (i.e., about 530–610 nm), and thus it cannot be directly exploited in ozone retrievals.
OMI can observe the Earth’s atmosphere in three observation modes. In the main mode—called the Global measurement mode—OMI has a swath width of 2600 km, a nadir pixel size of 13×48 km2(along- × across-track) for the UV1 channel and 13×24 km2 for the UV2 and VIS channels. The pixel size increases in the swath direction for increasing distances from the satellite ground track. The OMI average spectral resolution is of about 0.4 nm in the UV1 and UV2 channels and about 0.6 nm in the VIS channel. The OMI Global measurement mode provides almost global coverage in one day. In principle, a complete daily global coverage is possible at midlatitudes. However, a complex instrumental effect, called row anomaly—which started to appear in the Level 1B data on June 25th of 2007—creates some gaps in the instrumental coverage. More informations on this effect are available from the Royal Dutch Meteorological Institute (Koninklijk Nederlands Meteorologisch Instituut (KNMI)) website .
In addition to the Global mode, two so-called “zoom-in” observation modes are available. In both modes the nadir pixel size is reduced to 13×12 km2. In the Spatial zoom-in mode the pixel size is reduced at the expense of the swath width, which decreases to 725 km; in the Spectral zoom-in mode the reduction comes at the expense of the wavelength range, which is limited to 306–432 nm . Zoom-in observations are only performed during selected orbits.
3 The OMI-TOC NN algorithm
Summary of the stations used in the training set of the OMI-TOC NN. After
The input vector for the OMI-TOC NN consists of OMI spectral reflectances at 19 selected wavelengths, extracted from OMI Level 1b data; the solar zenith angle (SZA) and the total ozone column taken from the operational OMI Level 2 product. Only Global measurement mode data were used, because only this observation mode provides daily global coverage. The 19 wavelengths were selected according to an extended pruning (EP) technique . This technique aims at reducing the dimensionality of an input vector for a NN by retaining only the most informative inputs, i.e., those who have the strongest influence on the NN output. Six of the selected wavelengths belong to the 305–307 nm range (covered by the OMI UV1 channel), while the remaining 13 wavelengths lie in the 322–325 nm range (covered by the OMI UV2 channel). The spectroscopic relevance of these two spectral ranges in the context of ozone retrievals is discussed in .
The dimensionality reduction of the reflectance spectra is useful for a number of reasons. First, using full spectra would lead to a very big input vector, which would in turn cause a need for a larger training dataset and longer training times. Second, there would be the risk of including irrelevant information in the input vector, which may compromise the learning capabilities of the NN (e.g., by causing overfitting).
In order to homogenize the spatial resolution of the input spectra, the UV2 reflectances were degraded to the spatial resolution of the OMI UV1 channel (see Section 2). The resolution degradation was performed through simple arithmetical averages between pairs of adjacent spatial pixels in the across-track direction.
The output quantity for the NN, i.e., the retrieved parameter, is the integrated ozone column between the surface and the 200 hPa pressure level. From now on, the name tropospheric ozone column (TOC) will be used when referring to this quantity. However, it must be pointed out that the choice of a static upper integration limit in the definition of the TOC—regardless of the actual tropopause height—might be rather inaccurate. The problems that can arise as a consequence of this choice are shown and critically discussed in Section 5.
4 Validation set and intercomparison methodology
Six European ozonesonde stations were used in the validation of the OMI-TOC NN: Ankara (Turkey), Izaña (Canary Islands, Spain), Lerwick (Shetland Islands, United Kingdom), Valentia Island (Republic of Ireland), L’Aquila and San Pietro Capofiume (Italy). No data from such stations were used during the training of the OMI-TOC NN. Data acquired between October 2004 and December 2008 were considered in this validation exercise. This is the same period that is covered by the training dataset of the OMI-TOC NN. This choice was made in order to ensure that eventual problems in the algorithm are not caused by instrumental changes that may have occurred after the period covered by the training set.
The data for Ankara, Lerwick and Valentia Observatory were taken from the World Ozone and Ultraviolet Data Center (WOUDC) archive. The data for Izaña were taken from the public archive of the network for the detection of atmospheric composition change (NDACC).
In addition to the data available from WOUDC and NDACC, data from two the two Italian ozonesonde stations of L’Aquila and San Pietro Capofiume were used.
The L’Aquila ozone soundings were performed by the University of L’Aquila and the Centre of Excellence for the integration of remote sensing techniques and modeling for the forecast of severe weather (Centro di Eccellenza di Telerilevamento e Modellistica numerica per la Previsione di eventi Severi (CETEMPS)). The ozonesonde station is located at the CETEMPS atmospheric observatory, Casale Calore di San Vittorino (42.3°N, 13.31°E, 683 m a.s.l.), near the town of L’Aquila. The ozonesondes are SPC-6A type electrochemical concentration cell (ECC) sondes [32, 33], interfaced with Vaisala RS-92 PTH (Pressure, Temperature, Humidity) radiosondes.
The ozone sounding activity at L’Aquila is performed within the framework of a collaboration between CETEMPS, L’Aquila University and the Italian Ministry for the Environment and Territory. The first soundings were performed in 1994. Since 2004, about two soundings per month have been regularly carried out on average. In the past, L’Aquila ozonesonde data were used in the validation of ozone profiles retrieved by the Michelson interferometer for passive atmospheric sounding (MIPAS), onboard Envisat [34, 35].
The San Pietro Capofiume ozone soundings were performed under the responsibility of the Italian National Research Council (Consiglio Nazionale delle Ricerche (CNR)) Institute for Atmospheric and Climate Sciences (Istituto di Scienze dell’Atmosfera e del Clima (ISAC)). The San Pietro Capofiume ozonesondes are ENSCI-Z type ECC sondes, interfaced with Vaisala RS-80 PTH radiosondes.
In the past, ozone soundings were regularly performed at San Pietro Capofiume from 1991 to 1995 [36, 37], and a specific campaign was organized in 1997 . In 2004 and 2005, a sporadic sounding activity was carried out. However, it was subsequently interrupted due to scarcity of research funds. The data acquired during 2004 and 2005 were used in this study.
Within the above mentioned set of locations, different climatological characteristics are represented. This allows the geographical generalization capabilities of the OMI-TOC NN algorithm to be assessed, even at the upper and lower boundaries of the latitudinal range covered by the training set. Izaña is close to the African continent and not far from the Tropic of Cancer, and thus can be regarded as an hybrid midlatitude/subtropical station, being influenced by air masses coming from both the midlatitudes and the subtropics . Lerwick and Valentia are characterized by an oceanic climate, and are subjected to advections of both midlatitude and polar air masses . Hence, these stations can either behave as polar or midlatitude stations depending on the location of the polar front. Ankara, L’Aquila and San Pietro Capofiume can be regarded as typical midlatitude stations. Furthermore, all the stations are located in geographical areas that are not covered by the training set of the OMI-TOC NN algorithm. For this reason, validating the algorithm over this set of locations can give a reliable insight on its geographical generalization capabilities, as well as on its limitations.
In order to generate the validation set, the same co-location criteria as those used in the development of the OMI-TOC NN algorithm were followed. Specifically, an ozone sounding and an OMI pixel were considered as co-located if two criteria were met: (i) the nominal coordinates of the ozonesonde station and those of the pixel center were no more than ±1°apart; and (ii) no more than 12 hours had elapsed between the ozone sounding and the Aura overpass on the ozonesonde station.
Summary of the stations used in the validation presented in this article
San Pietro Capofiume
Republic of Ireland
5 Validation results
One possible reason for the systematic underestimation of TOCs higher than 60 DU lies in the choice of 200 hPa as a static upper integration limit for the retrieved ozone column. In fact, if this TOC definition is used, extreme TOC values can be expected when the actual tropopause pressure exceeds 200 hPa (i.e., when the actual tropopause height is lower than the upper integration limit used in the OMI-TOC NN), because a large portion of stratospheric air—which is very rich in ozone—is included in the column over which the ozone profile is integrated in order to derive TOC. As a result, including the tropopause pressure in the input vector can help the NN discriminate such cases of enhanced TOC, and hence improve the overall retrieval accuracy.
6 Correction of tropopause related errors
RMSE on training, test and validation sets for the OMI-TOC NN and its modified version
TOC Std. [DU]
Mod. OMI-TOC NN
Error statistics for the OMI-TOC NN and its modified version for all the ozonesonde stations considered in this article
Modified OMI-TOC NN
The improvements are evident on Ankara and L’Aquila, and dramatic on Lerwick and Valentia Observatory. Such improvements were not found on Izaña, which still appears to be the most problematic station amongst those shown in this article. From a visual inspection of the upper right panel of Figure 3, it is evident that the tropopause pressures over Izaña were most often far below 150 hPa (i.e., the tropopause was considerably higher than the corresponding altitude level) with regard to the ozone soundings used in this validation exercise. This suggests that Izaña mostly behaved as a tropical station, and thus portends poor performances of the OMI-TOC NN with air masses of tropical origin. This behavior appears reasonable, because the OMI-TOC NN was trained using only midlatitude data. Anyway, further investigations are ongoing in order to interpret this result.
In this article, the results of a validation of a NN algorithm for tropospheric ozone column retrieval from OMI data—named the OMI-TOC NN—are shown. The validation was performed over six ozonesonde stations distributed across the European continent. This validation set is considered as a benchmark for the retrieval performances of the algorithm, as it represents a number of climatological situations that can be encountered over Europe.
A good agreement over Ankara, L’Aquila and San Pietro Capofiume—the most central stations in terms of latitude—was found. However, strong negative biases are present over Lerwick, Valentia Observatory and Izaña, especially in conditions of high TOC values. In order to investigate the reasons for this problem, the retrieval bias of the OMI-TOC NN algorithm was analyzed as a function of the tropopause pressure values taken from the NCEP/NCAR Reanalysis 1. A significant correlation between tropopause pressure and retrieval error was found. As a consequence, a new version of the OMI-TOC NN, having the NCEP/NCAR tropopause pressures in its input vector, was designed, and its results were evaluated over the same validation set.
The modified OMI-TOC NN algorithm exhibited a considerably improved retrieval accuracy, in terms of RMSE, over the whole validation set. The improvements were found to be most significative on the northernmost stations of Lerwick and Valentia Observatory, where cases of low tropopauses (i.e., high tropopause pressures) are most frequent. However, no improvements were observed on Izaña, where tropopause pressures larger than 200 hPa are quite unlikely. The results of the modified OMI-TOC NN on Izaña also suggest that using the tropopause pressure as an input for the algorithm is still not sufficient to improve the retrieval accuracy in cases of high tropopauses. In the future, this issue will be addressed by including tropical ozonesonde stations in the training set.
A major point that might be raised on the basis of these results is that using 200 hPa as upper integration limit in the TOC definition is not a sensible choice in order to characterize the tropospheric ozone column. Further versions of the OMI-TOC NN algorithm should provide estimates of the ozone column up to the actual tropopause, whether it be defined based on the NCEP/NCAR Reanalysis or by other means (e.g., dynamical tropopause).
This study had been carried out in the framework of the ESA Project C1P.2930. All the PIs of the ozonesonde stations whose data are used in this study are gratefully acknowledged. The ozone monitoring activities of CETEMPS are partly funded by the Italian Ministero dell’Ambiente e della Tutela del Territorio e del Mare. The data for Ankara, Lerwick and Valentia Observatory ozonesonde stations were retrieved from the World Ultraviolet Data Center (WOUDC) archive (http://www.woudc.org). The data for the Izaña ozonesonde station were obtained as part of the Network for the Detection of Atmospheric Composition Change (NDACC) and are publicly available (see http://www.ndacc.org). The NCEP Reanalysis data are provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/.
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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:e722ba00-53e7-4c81-ac6b-456f257cf811> | 2.59375 | 8,676 | Truncated | Science & Tech. | 43.220813 | 95,570,434 |
Conceptual and Philosophical Problems of Quantum Mechanics
In the preceding chapters we have tried to develop the conceptual basis of quantum mechanics. In addition, various exercises have demonstrated how quantum theory can be used to solve real physical problems. Of course, these problems represent only a small fraction of the many applications of quantum mechanics; numerous experimental results involving physics and chemistry can be explained successfully by adopting this theory. Up to now, no prediction made by quantum mechanics has been disproved experimentally. In spite of this success, conceptual problems of the theory exist; in fact, there have been many attempts to interpret quantum mechanics in a new way or even to replace it by another theory based on a more obvious conceptual and philosophical foundation.
KeywordsWave Function Quantum Mechanic Hide Variable Spin Component Spin Vector
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Circuit is attached
(a) Calculate the value of the current through the 12 V battery shown in
(b) Calculate the power dissipated in R1, R2 and R.
Let us assume current through R be I3 and comping out of battery of 12 V, i.e., all 3 currents are incident towards a junction.
E1 = 13 V
E2 = 14 V
E3 = 12 V
R1 = 1 ohm
R2 = 2 ohm
R = 3 ohm
At one of the two junctions, by Kirchhoff's current law (KCL),
I1 + I2 + I3 = 0 ...(1)
For closed ...
In a given electric circuit, by using Kirchhoff current and voltage law, currents are estimated in associated resistances. Also, power dissipation in the resistances are estimated. | <urn:uuid:a00587e2-b23d-48b7-bc6d-08b55870175c> | 3.375 | 188 | Tutorial | Science & Tech. | 83.25092 | 95,570,446 |
Radiation damage to proteins is a topic of intense interest to those involved in radiation effects in biology, and also to those involved in radiotherapy. Although it has been widely studied, fundamental processes in protein damage are very hard to specify because of the complexity of the final damage products. But the non-invasive technique of electron-spin resonance is ideally suited to the task of detecting and identifying the primary and secondary products as these are expected to contains unpaired electrons (that is, free-radicals) and such species are uniquely detected by this sensitive form of spectroscopy. Our present study shows that a major radical species formed by electron loss in a range of proteins is the backbone amido radical, -N.(CO)-, characterized by hyperfine coupling to one 14N nucleus. These centres are efficiently trapped in proteins at low temperatures. In contrast, the expected backbone electron-capture centres, -NH(CO.-)-, are not readily trapped and electron transfer occurs until the ejected electron is trapped by some electrophilic centre. Such electron mobility was in fact established in our previous work on oxyhaemoglobin (FeO2----FeO2-), superoxide dismutase (Cu(II)----Cu(I] haemocyanin (Cu(II)O2Cu(I)----Cu(I)O2Cu(II] and various proteins containing S-S bonds (-S-S-)----(-S.-S-) (refs 1-4 respectively). This is strongly supported by our observation that such electrons are captured by DNA molecules, giving T.- centres, when nucleohistones are irradiated, and that Fe(CN)3-(6) ions readily scavenge such electrons from proteins which are devoid of highly electrophilic centres.
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SOUTH AUSTRALIAN BUTTERFLIES
INTRODUCTION AND HABITATS
Butterflies are predominantly a tropical group of insects. It is not surprising, therefore, that the majority of the 400 odd species recorded in Australia have a distribution which includes, or is restricted to, the tropical and subtropical north and east of the continent. Seventy-eight of these species, less than one fifth of the Australian fauna, have been recorded in South Australia. This group of butterflies, though small, is rich and diverse in the southern endemic colder elements of the Australian butterfly fauna.
South Australia is a dry state. The average rainfall is 235 mm (9 "). The state can be divided into two broad vegetation areas, each largely dependent on the amount of rainfall it receives, and demarcated by the 250 mm rainfall isohyet. That area receiving the lower rainfall is the arid and semi-arid north which accounts for about 80 % of the state and is generally termed the Eyrean Zoogeographic Region. It is predominantly pastoral country. In this area, most of the meagre rainfall occurs during the hot summer monsoon months.
Nearer the coast is the area receiving rainfall greater than 250 mm which is termed the Bassian Zoographic Region. Here, the rainfall occurs mostly during the cold winter months. It is the start of the dense, temperate woodland habitat. It is also the start of intensive agriculture within the state, and consequently it has suffered the most from clearing, and it is estimated that 90 % of this region has been cleared contributing to the current dryland salinity crisis. About 60 % of the state's butterflies are largely endemic to this region. There are three subregions within this zoogeographic region. The dry woodland (mallee) habitat, the generally elevated forests and wet woodlands, and the very narrow coastal habitat.
The hot arid and semi-arid lands are located in the Far North Pastoral region and comprise 80 % of the state. It is a generally low area below 600 m and Lake Eyre itself is below sea-level. Higher rocky areas occur in the Gawler, Olary and northern Flinders Ranges (in southern areas), and the Mann, Musgrave and Tomkinson Ranges in the far north-west. Vegetation is largely controlled by rainfall and soil type. Habitats are extensive and monotonous. The vegetation is often very sparse, particularly in the Lake Eyre Basin east of the Stuart Highway, consisting of very open acacia or eucalyptus woodland, blue-bush and salt-bush shrubland, and grasslands. Sometimes the vegetation is better developed along ephemeral waterways or within the dune fields. The vegetation improves nearer the southern limits of the region where extensive, open mallee (dryland Eucalyptus) and myall (Acacia papyrocarpa) woodlands may occur.
Many of the migrant butterflies breed in this area after good rains, with five species of butterflies largely confined to the region. Some of the butterflies probably lead a nomadic existence, moving along the ephemeral waterways. Butterfly populations are believed to be mostly stable here, although the region has been poorly surveyed for butterflies. The area suffers from the effects of overgrazing from feral (camels, goats and rabbits) and domestic animals. In some areas there has been very little self generation of woody flora since the coming of European settlement (1836), due to the combined effects of periodic drought and overgrazing by the animals. Existing woody flora in such areas are as old or older than this settlement! In this area also occur the breeding grounds for the plague locust. Control of the locust by the aerial application of poisonous sprays has had a devastating effect on the local biodiversity, but hopefully new technology through the use of a Metarhizium fungus may see a lasting improvement in the environment.
The Everard, Mann, Musgrave and Tomkinson Ranges reach a maximum elevation of 1440 m. The vegetation in these ranges consists mainly of the very prickly, tussocky spinifex grass (Triodia sp), while the vegetation on the surrounding dune plains comprises mulga (Acacia aneura) woodland infested with the pale-leaf mistletoe (Amyema maidenii). Some of the valley areas contain spring water and better vegetation which support resident populations of arid-land butterflies.
This habitat dominates the southern 20 % of the state, and generally occurs in the areas receiving rainfall greater than 250 mm. This vegetation type is dominated by dryland Eucalyptus species but also contains many other smaller wood or shrub land communities dominated by either Acacia, Banksia, she-oaks (Allocasuarina), native pines (Callitris), or Melaleuca. It is interspersed with occasional broadacre native grasslands. The understorey is also complex and diverse, containing many butterfly foodplants including quandongs, Choretrum, dryland sedges, grasses, and small shrubs and herbs.
Much of this mallee vegetation is tolerant of periodic bushfires, with the Eucalyptus regenerating from lignotubers, while the Acacia and the understorey and other associated vegetation are actually dependent on the bushfires for regeneration, with the seed-base requiring the heat of the fire to weaken the hard outer seed capsule and the smoke from the fire to impart certain chemicals for germination and enhanced early growth. There is often a bushfire produced early growth cycle of certain flora immediately after the fire that includes Leguminosae and Santalaceae, to a later mature flora dominated by different plants than those present during the early part of the cycle. There are certain butterflies which have adapted to these early immature and late mature periods of the bushfire cycle.
Eucalyptus Forest and Open Wet Woodland
The forest and wet woodland habitats are confined to the higher rainfall areas of South Australia. They occur in south-east Eyre Peninsula, western Kangaroo Island, the Mt Lofty and southern Flinders Ranges, and in the Lower South-east. They often have a diverse understory of medium and small shrubs, herbs, sedges and grasses. Although small in area, this habitat is home to a large range of butterflies. Two species are uniquely confined to this habitat in the Mt Lofty Ranges.
This is a cool and wet area, with annual rainfall greater than 700 mm. The vegetation is unique, comprising forest, wet woodland and swamps with close affinities to the Grampians and Great Dividing Range in Victoria. This habitat area also contains a unique butterfly fauna with eleven of the species present not to be found anywhere else in South Australia. More unique species are likely to be found in the future, although some species are also now probably extinct as a result of the extensive clearing and swamp drainage that has occurred in the region.
Wetlands are an important habitat of low lying areas, associated with creeks, rivers, lakes and estuaries. Springs are also a very important contributor to wetlands. Sedges (Cyperaceae family), and in particular the large saw-sedge Gahnia species are an important vegetation component of wetlands. Some wetlands are dominated by sedges, and are called sedge-lands. Sedges are the dominant foodplant for the Hesperillini skippers and several brown butterflies. Due to the severe degradation of our wetlands by fragmentation and draining, nearly all of the butterflies dependent upon wetlands for habitat or foodplant are now threatened.
Native grasslands occur locally throughout the state. In the dry pastoral and mallee areas they occur as Austrostipa (spear-grass), Astrebla (mitchell grass), and Triodia (spinifex) dominated grasslands. In the wetter forest and marsh areas Poa tussock-grasses sometimes dominate the understorey. Grasslands can occur in broadacre form but more often contain isolated trees and shrubs, and occur with rushes, sedges, and small herbs. Many species of butterflies associate with grasslands, with certain skippers and brown satyrid butterflies being totally dependent on this habitat. Native grasslands have historically been severely degraded by over-grazing and stock trampling, and consequently many of the associated butterflies are threatened, including the White-veined Grass-skipper and the Cynone Grass-skipper.
This is a very narrow zone adjacent to the sea, varying from high cliffs to sand dunes and estuarine ecosystems. There is a wide range of very specific vegetation types and habitats, including estuarine mangroves, sedge wetlands and samphire marshes, shrubland and mallee in the dunes, and low coastal heaths along the cliffs. It is often a harsh habitat due to the salt laden winds, but many butterflies thrive in the environment.
The urban region is the habitat of common butterflies, and is also briefly frequented by migrating butterflies. Flowering garden plants are the resting and re-fuelling stations for butterflies as flowers contain nectar, the main food source for the adults. Buddleias, lantanas and many other plants can attract butterflies to the garden. There are about twenty species of butterflies which are commonly seen in gardens in the southern parts of the state, and include the Australian Painted Lady, the Australian Admiral, the Meadow Argus, the Monarch and various migrant butterflies such as the Caper White and the Small Grass-yellow.
Migrant and Vagrant butterflies
These species either periodically or annually migrate in numbers (migrants), or singly (vagrants) within South Australia, over short or long distances. Many butterfly species have this tendency (especially the females in the case of vagrants), and particularly during favourable seasons, as it is mostly used as a means of dispersal in Australia. This habit is particularly strong in the white, yellow and nymph butterflies. These butterflies are common near their food plants in their normal breeding habitat, which is usually either in the northern pastoral areas of the state, or interstate. Many of the species from the latter two areas are biologically unsuited to the southern parts of the state and do not establish even if the food plant is present. There are about 30 butterflies presently recorded from South Australia that have migration tendencies.
For further landcover and climatology information check the following.
Note: URL's and government information tend to change rapidly, and so the above
addresses may no longer be accurate. Last check
of links 8 January 2007
Author: R. GRUND, © copyright, 20 July 1999, all rights reserved. Updated 8 January 2007. | <urn:uuid:471c96b3-4da5-4372-807c-27b6c9b634a1> | 3.6875 | 2,225 | Knowledge Article | Science & Tech. | 32.460832 | 95,570,471 |
Secrets to be unveiled from the mysterious meteorite, say scientist at NASA
Earlier in the year, NASA’s weather telescopes detected a mysterious meteorite whizzing through the atmosphere and taking a plunge into the Pacific Ocean. What amazed the team at NASA was that the meteorite had hardly lost most of its content during entry into Earth’s atmosphere.
Marc Fries, NASA’s planetary scientist, suggests that Earth may have a unique meteorite visit our planet for in a long time. The space rocks were found to not to crack, break or burn apart while making an entry into Earth’s hot atmosphere at tremendous speeds — something that’s usual with every other meteorite entry. "This one is special, is tougher than your typical meteor,” said Fries, in an interview.
However, NASA has previously never extracted space rocks from the ocean. Therefore, this is the first time the premiere space agency will attempt to scavenge meteorites from the ocean bed. The area where the rocks have landed is shallow and goes down up to 330 feet.
As NASA will rely on an exploration vehicle, called Nautilus, to hunt for the mysterious rocks. The vehicle is equipped with robotic probes with magnetic arms that will pull out the meteorite, if it’s metallic in nature (meteorites are usually full of metals).
The unique properties of this mysterious meteorite has got the team excited at NASA. It is expected that this space rock will eventually unfold new secrets of the universe that may not have been unveiled yet. | <urn:uuid:25e6dae7-52a5-42fc-affb-cf32b94eb6b6> | 3.65625 | 321 | Truncated | Science & Tech. | 42.088698 | 95,570,474 |
Hydrogeological characterisation of groundwater over Brazil using remotely sensed and model products
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For Brazil, a country frequented by droughts and whose rural inhabitants largely depend on groundwater, reliance on isotope for its monitoring, though accurate, is expensive and limited in spatial coverage. We exploit total water storage (TWS) derived from Gravity Recovery and Climate Experiment (GRACE) satellites to analyse spatial-temporal groundwater changes in relation to geological characteristics. Large-scale groundwater changes are estimated using GRACE-derived TWS and altimetry observations in addition to GLDAS and WGHM model outputs. Additionally, TRMM precipitation data are used to infer impacts of climate variability on groundwater fluctuations. The results indicate that climate variability mainly controls groundwater change trends while geological properties control change rates, spatial distribution, and storage capacity. Granular rocks in the Amazon and Guarani aquifers are found to influence larger storage capability, higher permeability ( >10-4 m/s) and faster response to rainfall (1 to 3 months' lag) compared to fractured rocks (permeability <10-7 m/s and lags > 3 months) found only in Bambui aquifer. Groundwater in the Amazon region is found to rely not only on precipitation but also on inflow from other regions. Areas beyond the northern and southern Amazon basin depict a ‘dam-like’ pattern, with high inflow and slow outflow rates (recharge slope > 0.75, discharge slope < 0.45). This is due to two impermeable rock layer-like ‘walls' (permeability <10-8 m/s) along the northern and southern Alter do Chão aquifer that help retain groundwater. The largest groundwater storage capacity in Brazil is the Amazon aquifer (with annual amplitudes of > 30 cm). Amazon's groundwater declined between 2002 and 2008 due to below normal precipitation (wet seasons lasted for about 36 to 47% of the time). The Guarani aquifer and adjacent coastline areas rank second in terms of storage capacity, while the northeast and southeast coastal regions indicate the smallest storage capacity due to lack of rainfall (annual average is rainfall <10 cm).
Showing items related by title, author, creator and subject.
Hydrogeology of the Lake Muir–Unicup Catchment, Western Australia: an ecologically important area experiencing hydrologic changeSmith, Margaret G (2010)Identified in the Western Australian Government’s 1996 Salinity Action Plan as an important natural diversity area at risk from changing hydrology, the Lake Muir– Unicup Natural Diversity Catchment is in need of urgent ...
Burgess, W.; Shamsudduha, M.; Taylor, R.; Zahid, A.; Ahmed, K.; Mukherjee, Abhijit; Lapworth, D.; Bense, V. (2017)Groundwater-level fluctuations represent hydraulic responses to changes in groundwater storage due to aquifer recharge and drainage as well as to changes in stress that include water mass loading and unloading above the ...
Bonsor, H.; MacDonald, A.; Ahmed, K.; Burgess, W.; Basharat, M.; Calow, R.; Dixit, A.; Foster, S.; Gopal, K.; Lapworth, D.; Moench, M.; Mukherjee, Abhijit; Rao, M.; Shamsudduha, M.; Smith, L.; Taylor, R.; Tucker, J.; van Steenbergen, F.; Yadav, S.; Zahid, A. (2017)© 2017, The Author(s). The Indo-Gangetic aquifer is one of the world’s most important transboundary water resources, and the most heavily exploited aquifer in the world. To better understand the aquifer system, typologies ... | <urn:uuid:9966c2d9-7267-4e0b-a210-c93356dbaaed> | 2.75 | 804 | Academic Writing | Science & Tech. | 40.367169 | 95,570,489 |
A NASA-led science team has created an accurate, high-resolution map of the height of Earth’s forests. The map will help scientists better understand the role forests play in climate change and how their heights influence wildlife habitats within them, while also helping them quantify the carbon stored in Earth’s vegetation.
Quoted from NASA map sees Earth’s trees in a new light on ScienceDaily: Top News
An international team of astronomers using the NASA/ESA Hubble Space Telescope and the European Southern Observatory’s Very Large Telescope has made the Cosmicopia at NASA/GSFC -- Ask Us -- Earth and Moon Geosttionry Stellite Dt Note: Imgery nd loops on this site re tended for formtionl purposes only, they re not considered Tags: eastern, infrared, noaa, goes, SpaceWeather. -- News and information Noctilucent Clouds The seson for noctilucent clouds he northern hemisphere is underwy. Check here dily for the ltest imges from 's IM spcecrft. The Wilkson Microwve nisotropy Probe (W), origlly known s the Microwve nisotropy Probe (), ws spcecrft opertg from 2001 to 2010 | <urn:uuid:236e2af7-02ca-41ec-9012-803b18e6fbf1> | 3.296875 | 259 | News Article | Science & Tech. | 30.148857 | 95,570,506 |
Self-contained power plants could supply growing energy demand in poor countries.
Now more than ever, the world needs nuclear energy, says this year’s Nobel Peace Prize laureate, Mohamed ElBaradei. In a talk at MIT last week he cited a new report from the International Energy Agency that said world energy demand will increase by 50 percent in the next 25 years. Meanwhile, carbon dioxide emissions, which are a leading cause of global warming, will increase by the same percentage. Nuclear power could provide a significant amount of that power, without producing the carbon dioxide, says ElBaradei.
It’s an argument that’s attracting more and more proponents these days. But traditional nuclear power plants are very expensive to build, which can be a serious obstacle to their construction in poor countries. One solution being proposed, according to ElBaradei, is to build hundreds of small nuclear power plants, each designed to serve a single town. Such plants could be built for a fraction of the cost of the current large-scale regional ones. And they could be installed without the need to also build an extensive and expensive power grid. As a country’s energy needs grow, more plants can be added to keep up. Such plants might also be a good solution for remote communities.
A countryside dotted with hundreds of small reactors might seem like a safety and nuclear proliferation nightmare. But, according to ElBaradei, director general of the International Atomic Energy Agency, they can be built with safeguards against meltdowns and theft of materials by would-be terrorists.
Researchers at Argonne National Laboratory in Argonne, IL, described a concept for such a small-scale reactor this summer. One of the safeguards is a passive cooling system, which continues to work even if power goes down. The reactors could also operate for 30 years without refueling, which would mean fewer deliveries that could be hijacked. And stealing the fuel while it was in the reactor would require bringing to the site extensive heavy equipment, which would be easily visible by satellite, according to David Wade, senior technical advisor at Argonne and one of the developers of the concept.
“It’s good to have a reactor that requires a minimum of maintenance and refueling” for remote locations in some situations, says Mujid Kazimi, a nuclear engineer at MIT. He says that similar small reactors are under development in Argentina and Brazil, and Toshiba has recently offered to build one for an Alaskan town.
The Argonne concept uses a reactor cooled by liquid lead that allows for high operating temperatures and efficient use of the fuel, which is programmed to produce energy slowly over the 30-year cycle. The lead coolant also circulates without the need for the expensive back-up diesel generators required by today’s plants. “If it is built correctly, it will be able to be cooled by natural convection alone,” says Kazimi, who was not part of the concept development team.
The power plant would be mostly buried underground for protection, and surrounded by a back-up passive air cooling system – hot air rises out of the exhaust stack and cool air is pulled in through low vents. This system would run continuously, essentially wasting about one percent of the heat generated, yet ensuring that the reactor would cool off in the case of a problem.
The reactor is partially self-regulating. If the temperature rises, the structures containing the fuel expand, causing the fuel to spread out, and slowing down the frequency of the neutron collisions that create the nuclear reaction. This, in turn, causes the temperature to fall. These features, says Wade, should simplify the control of the plant and prevent meltdowns.
The lead will also serve as a safety measure. The fuel will be delivered inside the lead in a solid form, to be melted on site. When this module is removed and replaced after thirty years, the lead will cool off – now encasing the used fuel. This can be returned to a central facility for reprocessing, after which almost all of the spent fuel can be reused, says Wade.
On the downside, building small reactors means losing out on the economy of scale that has driven a trend toward bigger and bigger reactors, says Wade. He hopes to make up for this by creating ways to mass-produce the reactors in modules that can be quickly assembled on site.
For Wade, small reactors are part of a vision for large-scale changes. “What we’re trying to do is not only change the technology, but also exploit it, by changing the infrastructures. You can ship thirty years of energy with a single core loading, to provide energy security for a country without the need to install the infrastructure [for processing the fuel] right on its own territory.” ElBaradei says designs such as the one developed at Argonne could actually “reduce access to sensitive nuclear material” if countries agreed to share fuel facilities. “We cannot afford to have every country sitting on an enrichment factory or reprocessing facility,” he says. If a country with such a facility begins to feel threatened, it “would be able to develop nuclear weapons within a matter of months.”
“We who live in the nuclear age are approaching a crossroads, a moment of truth,” ElBaradei told the audience at MIT. “Will this technology continue to be harnessed as a servant of development? Or will we become the victim of its destructive power?” For now, he says, “the benefits of nuclear energy are needed more than ever.”
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:afaa6e81-05d5-4d7d-bbfb-cafa5897e35d> | 3.40625 | 1,186 | News Article | Science & Tech. | 42.922518 | 95,570,508 |
Specialists of the Institute of Maritime Biology, Far-Easernt Branch, Russian Academy of Sciences, and Primorsky (Maritime) Production and Acclimatization Station of the Federal State Administration Primorrybvod suggest that maritime scallop should be acclimatized in low-populated waters of the Barents and White Seas. The new region suits in all respects for the Far-Eastern shellfish, which is able to feed both people and maritime inhabitants.
Northern waters of the Atlantic and Pacific Oceans are very similar in terms of living conditions, but Atlantic Ocean is far less inhabited. These are consequences of the quaternary glaciation, when arctic species could not live in freezing shallow water even in warm periods and irreversibly adapted themselves to living in sea depths. Vacant places remained nearby the coasts, which people fill in with the Pacific species. Russia has already acclimatized the king crab and salmon fish in these waters. The maritime scallop is one of the most promising maritime animal species for cultivation. Growing of scallop in the sea does not require feed, and its meat is very delicious and good for health (its consumption reduces the risk of atherosclerosis development). The Far-East Population has been eating maritime scallops since the Stone Age, but now these mollusca cost more than USD 10 per kilogram. Whitebait of scallop serves feed for crabs and fish.
Places for maritime scallop’s acclimatization should be chosen taking into account its likes. This mollusc likes cool salt water and rather strong streams, but it needs quiet places for spawning, so that the stream should not be carried away into the cold open ocean. The seabed should not be uliginous, otherwise the mollusc may be sucked in. Fine sand, that the waves raise easily and carry out to the coast together with scallops, does not fit either. The maritime scallop’s habitat should stay under water even during the low tide: the scallop would not endure staying in the air for more than an hour. The Russian specialists are sure there are sufficient locations in the Barents and White Seas to meet these requirements. The only thing the maritime mollusc will have to get used to is specific light mode of the extreme north. But the king crab has accommodated itself to the polar night, the scallop will also get accustomed to it, especially because the peak of its activity falls on nighttime.
Sergey Komarov | alfa
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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19.07.2018 | Materials Sciences | <urn:uuid:ac142101-9c89-49f7-82ca-213c26714c45> | 2.953125 | 1,184 | Content Listing | Science & Tech. | 40.763372 | 95,570,535 |
Confocal Microscopy of Live Xenopus Oocytes, Eggs, and Embryos
The use of the confocal microscope to study living Xenopus eggs affords the opportunity to obtain four-dimensional (4-D) data (three-dimensional [3-D] data over time) throughout early development of these large cells. Microscopy of living cells often reveals important information about dynamic cellular events that cannot be gleaned from analyses of fixed cells; however, certain compromises must be made to assure cell viability. Several approaches are typically used for examining living cells. One approach is to collect successive images at fixed time intervals over extended periods of time (e.g., time-lapse data collection), examining either the same optical plane or multiple different planes (3-D data sets, referred to as a z-series). Another approach is to collect, as rapidly as possible, multiple images over relatively short periods of time, again from a single optical plane or many different optical planes. In either case, it is imperative that the data be collected without altering normal cell function. Although multiphoton microscopy is the preferred approach for studying living cells, as it results in less damage to the cell, it is difficult with Xenopus oocytes and embryos because the energy of the longer wavelengths used is absorbed by the pigment granules, causing intense local heating (Larabell, personal observations). We have found, however, that standard confocal microscopy using a krypton-argon laser can be used to examine Xenopus eggs and embryos with undetectable adverse effects as determined by the ability of the eggs to develop into swimming tadpoles (1,2).
KeywordsOptical Plane Animal Pole Transport Zone Organelle Movement Animal Hemisphere | <urn:uuid:1d0aeaf1-cce3-4d69-b0b8-56ac3520233d> | 2.953125 | 353 | Academic Writing | Science & Tech. | 9.916667 | 95,570,579 |
California joins global assault on killer seaweed / Europeans provide ideas for destroying resilient, toxic algae
2003-01-20 04:00:00 PDT Hvar, Croatia -- Beneath the surface of Starigrad Bay, the finger-shaped inlet that serves as this Adriatic island's main harbor, the invasion is well under way.
Just off the main ferry landing, the seafloor is carpeted in luxuriant green foliage, a thick meadow of beautiful seaweed stretching uninterrupted as far as the eye can see. The delicate, bright green plants have covered rocks, sand, mud and virtually everything else in their path.
Before 1995, nobody in Croatia had ever seen this voracious tropical interloper, which is toxic to most marine animals and rapidly replaces other sea-bottom ecosystems. In the future, researchers fear, those diving off its Adriatic coast may see little else.
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Others fear California could be next.
Dubbed the "killer algae" by European scientists, Caulerpa taxifolia seems to know no bounds. Prized by aquarium owners as an ornamental plant, the seaweed has been unwittingly spread from its home in the tropical Pacific to Europe, Australia and, most recently, Southern California, where authorities are trying to snuff it out before it takes over everything.
"If, God forbid, Caulerpa comes to San Francisco Bay on somebody's boat anchor or (discarded home) aquarium water, there are areas that are probably warm enough to support it," says Susan Williams, director of UC Davis' Bodega Marine Laboratory in Bodega Bay.
PLANT MUTATED IN CAPTIVITY
Caulerpa taxifolia normally grows in small, discreet clusters in tropical Pacific waters, dying if the water temperature drops below 70 degrees. But something happened after specimens of the plant were imported in the 1970s by the Wilhelmina Zoo in Stuttgart, Germany, which displayed the plant in its tropical aquarium.
Somehow, the normally timid plant mutated in captivity, producing a strain capable of surviving for months in waters as cold as 50 degrees. The mutated strain also grows several times larger than its normal tropical size and spreads much faster, capable of colonizing most bottom types.
The Wilhelmina Zoo gave samples of the pretty weed to other institutions throughout Europe. In 1984, an employee of the Oceanographic Museum of Monaco discovered a single square-meter patch of the alien seaweed growing in the sea beneath the museum. Scientists dismissed the escaped seaweed as an amusing curiosity and expected the plants to die over the winter.
Instead, Caulerpa spread far and wide, hitching rides from port to port on boat anchors and fishing gear. Today, it covers 32,000 acres of the Mediterranean seafloor, replacing diverse native bottom habitat from Tunisia to Croatia to Spain.
"For the Mediterranean Sea, it is too late. It can never be eradicated," says Alexander Meinesz, professor of biology at the University of Nice-Sophia Antipolis in France, who first alerted the scientific community to the seaweed's threat. "All of the (near-shore) areas of the Mediterranean will be more or less invaded by this species," he says.
ALGAE 'SPREADS LIKE CANCER'
Caulerpa was carried hundreds of miles across the sea to the Adriatic island of Hvar on the anchor of a passing yacht seven years ago. Now, it covers almost 100 acres of sea bottom and continues to spread.
"It gets bigger every year," laments Ante Zuljevic of the Institute of Oceanography and Fisheries in nearby Split, whose efforts to eradicate the invasive seaweed merely slow its expansion. "Caulerpa spreads like cancer in a human being. Our hope is that we can keep it in check until somebody finds a way to stop it."
Like some B-grade science-fiction alien, Caulerpa has gone global, showing up in bays and estuaries around Sydney and Adelaide in Australia. It also was found growing in a saltwater lagoon in Carlsbad, 20 miles north of San Diego, in July 2000. It has since been discovered in Huntington Harbor in Orange County, 50 miles north of the first site.
U.S. scientists and authorities have advantages over their colleagues in the Mediterranean: They can draw from the painful lessons Europe has learned during its 14-year struggle with the renegade algae.
Europeans have discovered that once Caulerpa gets established in a particular area, it is very difficult to eradicate. Since 1991, French scientists and authorities have tried many methods: smothering the plants with salt, sucking them up with vacuum hoses, uprooting them by hand, and smothering them under tarps. In each case, the algae quickly bounced back.
Fortunately, eradication efforts in Southern California started early. Because both of the affected sites are located in nearly enclosed lagoons, scientists hope the seaweed can be completely wiped out before it spreads to the open ocean and beyond.
"If Caulerpa had to invade, at least these lagoons present a manageable situation," says Williams, the UC Davis scientist who has been closely watching the project. "We're very concerned that they will get out of these lagoons."
COMPANY MAKING HEADWAY IN STATE
Keith Merkel, head of Merkel & Associates, the company that is trying to get rid of the Caulerpa, says the firm made eradication its top priority early on. European scientists told them, "Don't mess with this stuff. Your single focus should be to kill it."
The San Diego company covers Caulerpa stands with tarps, then kills them by applying chlorine underneath the covering. Rachel Woodfield, the head of the eradication program, says the method appears to be working. In her last underwater surveys of the Carlsbad infestation site, she found only a 4-square- foot area of Caulerpa, down from 11,000 square feet initially.
"The battle is by no means won," Woodfield says, noting that all it takes is a single Caulerpa fragment to spark an infestation. "We want to find no Caulerpa at all for several years before we can declare victory."
Susan Ellis, invasive species coordinator at the California Department of Fish and Game, says that preventing new introductions will require the cooperation of aquarium hobbyists and the businesses that sell marine plants to them.
"It's clear from the type of strain that this Caulerpa came from the aquarium trade," she says.
Caulerpa taxifolia and other members of the Caulerpa genus are extremely popular among aquarium hobbyists, who use them as an ornamental plant. As recently as 2001, the invasive Mediterranean strain of Caulerpa was being sold by 10 percent of Southern California's saltwater aquarium stores, according to a survey by biologists Steven Murray and Susan Frisch of California State University at Fullerton.
"In many of the stores we visited, 'Caulerpa' was used as a synonym for seaweed," Murray says. More than half the stores sold some variety of the Caulerpa genus, and 95 percent stocked "live rock," pieces of stone containing live marine organisms, including seaweed fragments.
But aquarium hobbyists are passionate about the Caulerpa genus, which comprises 73 species, many of which are difficult to tell apart, even for experts like Murray and Williams. When state legislators proposed a bill banning possession or sale of the entire genus, they were swamped with hundreds of letters,
e-mails, and phone calls from angry aquarium owners.
"We had a nationwide outcry," recalls David Weaver, a legislative assistant to Assemblyman Tom Harman, R-Huntington Beach (Orange County), who introduced the bill. "Their message was that banning the entire genus would have dire effects on aquarium owners."
In the end, legislators banned only nine Caulerpa species: three known to be invasive and six look-alikes. Williams is concerned that the law will be unworkable because of the difficulty of telling Caulerpa species apart. "There is a scientific consensus that all Caulerpas should be banned from the aquarium trade," she says. "The risk is just too great."
Woodfield, speaking on a cell phone from a boat on the infested Carlsbad lagoon, urged aquarium hobbyists not to release plants and animals into nature,
especially Caulerpa. "If you have caulerpa, get rid of it," she says. "Get it out of your tank, put it in a plastic bag and freeze it, and throw it away." | <urn:uuid:4e0425e0-b54d-4716-b215-f00447b86127> | 2.75 | 1,969 | News Article | Science & Tech. | 38.450068 | 95,570,584 |
TeachMeFinance.com - explain Morning Glory
Morning Glory --
An elongated cloud band, visually similar to a roll cloud, usually appearing in the morning hours, when the atmosphere is relatively stable. Morning glories result from perturbations related to gravitational waves in a stable boundary layer. They are similar to ripples on a water surface; several parallel morning glories often can be seen propagating in the same direction.
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Copyright © 2005 by Mark McCracken, All Rights Reserved. TeachMeFinance.com is an informational website, and should not be used as a substitute for professional medical, legal or financial advice. Information presented at TeachMeFinance.com is provided on an "AS-IS" basis. Please read the disclaimer for details. | <urn:uuid:83368d18-968d-48ae-9ff7-d84215632e8d> | 2.640625 | 161 | Knowledge Article | Science & Tech. | 28.905109 | 95,570,591 |
Under traffic regulations, car lights can illuminate the road up to a maximum of 30 m. To check the reach of the dipped-beam lights of their car, Peter stopped car at 1.5 m from the wall. The dipped-beam headlights are 60 cm high. At what height on the wall does Peter have to draw a mark to see if his dipped lights are on properly?
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Volcanoes are intimately tied to the history of humanity, they help forge...
By: Alwyn Scarth and Jean-Claude Tanguy
243 pages, Col photos, b/w photos, figs, maps
Comprehensive introduction to European volcanoes. Divided into regional chapters, it reflects both the variety of the volcanic structures, forms and eruptions, and the stimulus to the prolific research that they have inspired over the centuries. In each chapter, the causes, initiation and growth of the volcanoes are outlined, and special attention is drawn to highlights of their behaviour and their impact on the peoples around them. Regional areas covered include the Mediterranean, the Atlantic, and recent volcanoes of France and Germany.
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Plants perennial, with both fertile and sterile shoots; cespitose,
not rhizomatous. Culms 10-120 cm, erect, usually glabrous, sometimes
scabridulous or villous. Leaves mostly basal or evenly distributed; sheaths variously
pubescent or glabrous; ligules 0.5-4 mm, truncate or rounded; blades (3)10-20(40)
cm long, 1-5 mm wide, flat, folded, or involute, erect and stiff or ascending
and lax. Panicles (5)20-30(50) cm long, (0.5)1-2.5(5) cm wide, from
spikelike to open, often interrupted basally, green, purplish, or tawny,
usually silvery-shiny; branches with the spikelets evenly distributed. Spikelets 5-7.5
mm, sessile, subsessile, or on pedicels to 1.5(3.5) mm, with 2(3) florets; rachilla
internodes 0.5-1.5 mm; rachilla hairs to 1 mm. Glumes subequal
to unequal, lanceolate, usually smooth, sometimes scattered scabrous or
pilose, with wide scarious margins, apices acute to acuminate, sometimes
apiculate; lower glumes 3-4(5.5) mm; upper glumes 4-7 mm
long, equaling or exceeding the lowest florets, less than twice as wide
as the lower glumes; callus hairs to 1 mm; lemmas 3-6(7)
mm, narrowly to broadly lanceolate, glabrous, scabridulous, or pilose,
apices bifid, teeth usually less than 1 mm, awned, awns 3-8 mm, arising
from the upper 1/3 of the lemmas, geniculate, twisted basally; anthers 0.7-1.4
mm. Caryopses 1.5-3(4) mm, glabrous. 2n = 14, 28, 42.
Trisetum spicatum grows in moist meadows, forests, rock ledges,
and tundra slopes and screes, at 0-4300 m. Its range includes both North
and South America and Eurasia. Many infraspecific taxa have been based
on the variation in vestiture and openness of the panicle, but none appears
to be justified (see Finot et al. 2004 for a different opinion). Trisetum
montanum Vasey appears to represent no more than an extreme phase. Trisetum
spicatum differs from T. sibiricum in
its pubescent sheaths and denser, usually narrower panicles.
Culms tufted, 1-5 dm, antrorsely hairy above, retrorsely so (or glabrous) below; sheaths retrorsely hairy; blades flat or involute, glabrous or hairy, 1-3 mm wide; infl 3-10 cm, dense, or interrupted at base, spikelets mostly 2-fld; first glume linear-oblong, 3-5 mm, 1- veined; second glume lanceolate to oblanceolate, 4-6 mm, 3-veined; hairs of the rachilla 0.5 mm; lemmas slightly surpassing the glumes, the terminal teeth 1.3-2 mm, narrowly triangular; awn flexuous, 3.5-5 mm; anthers 0.6-1.4 mm; 2n=14, 28, 42. Arctic and alpine meadows and shores; circumboreal, s. to the higher mts. of U.S., Hispaniola, Mex., and s. S. Amer.; in our range s. to N.Y., Pa., Mich., and Minn., and in N.C. The numerous proposed vars. are ill-defined and confluent.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp. | <urn:uuid:d5107223-5e2c-4091-a414-bf7c8119effa> | 2.859375 | 918 | Knowledge Article | Science & Tech. | 76.637541 | 95,570,606 |
The conference, held the institute of Parasitología y Biomedicina "López-Neyra", CSIC in Granada, Spain, on 23 February 2009, was part of an ESF initiative to develop a coherent strategy for RNA research in Europe in recognition of the potential of RNA to result in new approaches to treating human diseases.
For many years it was believed that RNA’s sole function in cells was to transmit genetic information from DNA during the manufacture of proteins – the cell’s workhorse molecules. However, in recent years it has become clear that RNA has many more sophisticated functions and that there are more types of RNA than previously known.
The field exploded into activity with the discovery in 1998 by US researchers Andrew Fire and Craig Mello of a phenomenon called RNA interference, meaning that genes can be ‘silenced’ by RNA. This discovery, for which Fire and Mello were awarded the Nobel Prize in 2006, revolutionised the way scientists think about how genetic information is controlled in cells, and has opened the possibility of using gene silencing as a therapy where rogue genes cause disease.
“Research into RNA has great promise for both basic science and biotechnology and medicine,” said the meeting’s chairman, Professor Lars Thelander of Umeå University in Sweden. “Most pharmaceutical companies now have RNA projects, but the field is still in its early days and it could be another ten years before we see products appearing in the clinics.”
Professor Thomas Cech of the Howard Hughes Medical Institute in the US told the meeting how he discovered that RNA could also act as a biological catalyst – something that it was previously thought was the preserve of proteins representing a wonderful example of the versatility of RNA function. The discovery gave rise to new ideas about how life on Earth might have started and resulted in Professor Cech being awarded a Nobel Prize in 1989.
The Granada “Consensus Conference” was organised by ESF as part of a ‘Forward Look’ entitled ‘RNA World: a new frontier in biomedical research’ aimed at developing a strategy for research in RNA over the next ten years. Three earlier workshops had examined various aspects of RNA research to identify where gaps in our knowledge lie and what is required to plug these gaps and fulfil the promise that RNA holds. Forward Looks are a key part of ESF’s work, examining important areas of science and technology in consultation with leading scientists and policy makers to develop a strategic framework for research.
A Forward Look report on RNA research is due to be published later this year, detailing the scientific questions that need to be answered and giving politicians and policy makers the information they need when deciding where to direct research funding to ensure that Europe remains globally competitive in this key area of emerging science.
Sofia Valleley | EurekAlert!
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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The Environment : Answers to three important questions on Visual photoshop 4 full version Basic for Applications.
NET Reference : A Visual Basic programming language tutorial for Macon State College students that is applicable for anyone interested in Web Development.
A VB Intro : An introductory guide to Visual Basic with four lessons.
Object Oriented Programming and Visual Basic : An overview of object oriented programming.Visual Basic Tutorial : A nine-part Visual Basic tutorial.But THE big difference is the.Programming Guidelines : A Visual Basic.NET coding programming standards.Learning Barriers : This paper identifies six learning barriers associated windows xp x64 sp2 key with Visual Basic.NET.The Visual Basic 6 environment, defining terms, creating a Visual Basic Project.Excel/Visual Basic Primer : An introduction to using Excel spreadsheets with Visual Basic for Applications.The answer is all kinds.Welcome to the Visual Basic Tutorial Center.Computing : Introduction to Visual Basic concepts and examples.Visual Basic Tutorial in 1996 and since then the web site has attracted millions of visitors.It is the top-ranked Visual Basic tutorial website in many search engines including Google.Many versions of VB were released since 1991, the most popular one and still empirical market microstructure pdf widely used by many VB programmers is none other than VB6.
We provide hundreds of easy lessons and sample codes to help you master Visual Basic 6 programming.
B eginners a ll-purpose, s ymbolic, i nstruction, c ode, thus the acronym (word formed from the first letter of several words, in upper-case).
ADO Database Control : A tutorial for adding an ADO database control.Intro to Visual Basic : 17 pages to learning Visual Basic programming.What is Visual Basic?Access Tutorial : An introduction to Visual Basic programming language.We provide hundreds of easy lessons and sample codes to help you master Visual Basic programming.For one thing, the word Basic in Visual Basic is not an acronym anymore.Practice project - Building a Football Scoreboard. | <urn:uuid:5ebc7450-f53f-499d-a8b1-ff9efb30a4b4> | 2.6875 | 415 | Content Listing | Software Dev. | 39.994638 | 95,570,615 |
Siemens 3D Printing Robot Spiders
Siemens is creating 3D printers that crawl like spiders, cooperating to autonomously create objects.
The work is at an early stage, but it hints at where manufacturing may be headed, thanks to more sophisticated robot hardware, smarter control software, and new ways of forming components using 3-D printing. Unlike a conventional robotic production line, which has to be carefully reconfigured for each new product, a team of mobile manufacturing bots would simply be given the latest design and left to go to work.
The robots are equipped with 3-D cameras for mapping their surroundings. But they need to be able to localize themselves with a high degree of accuracy in order to work together effectively. Currently they are too imprecise to build anything very complex, and they will need to become far more sophisticated before actual manufacturing becomes feasible...
The robots are partially automated, but will eventually become more fully autonomous, learning how to interact with their environment...
I'm pretty sure I've seen this future somewhere before. In Charles Sheffield's 1979 novel The Web Between the Worlds, he describes remarkable spider robots that work together to build space structures. They are effectively 3D printers.
The two great ovoid bodies were hanging near the surface of the asteroid, about a hundred meters apart. The eight thin metallic legs were pointed downwards, balanced delicately a few centimeters clear of the surface. Between them, probing deep into the interior of the asteroid, was set the long proboscis. As Rob watched, the great, faceted eyes turned towards him. The Spiders were aware of his presence. Somewhere deep in their organic components lurked a hint of consciousness.
Corrie had been fascinated by them from the first moment she saw one. "Why eight legs?" she had asked.
Rob had shrugged. "It extrudes material like a spider. How many legs wouldi you have given it?
Via Technology Review.
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A 'Genuine Nanorobotic Production Factory'
'Microscopic machinery, smaller than ants, smaller than pins, working energetically, purposefully - constructing something...' - Philip K Dick, 1955.
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You can also use it to make a roof - on an asteroid.
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In this section I will try to present philosophical aspects behind NodeJS covering design principles and programming techniques inspired its development.
- Hollywood Principle: “Don’t call us we will call you”. To understand this here’s a small story – a struggling actor goes to some director and ask for role, currently the director don’t have any suitable assignment for him, and he don’t want to be bothered again and again, so he asked actor to leave his contact detail to his assistant and says – “don’t call me I will call you if some assignment is there”. This principle initiated the callback mechanism, whereby one task depending on other task for some processing, simply submit request along with a callback method/function to be called by other task when result is available. This way tasks do not block important resources like ‘thread’ in waiting.
- Asynchronous Call: To understand this first understand that ‘asynchronous’ is the state of being ‘not synchronised’; synchronous process generally wait for final result to be calculated whether success or failure. In asynchronous call you submit your request along with callback handler that must be triggered when result is prepared and returned, your process doesn’t wait rather continue with its flow. To achieve this ofcourse threads are required but that will be handled by nodejs for developer its single threaded programming model.
executeQuery("select empid from employee", resultHandler(data))
||Here your resultHandler is a callback handler.
Please see http://blog.mixu.net/2011/02/01/understanding-the-node-js-event-loop/ for more detail on single thread model.
executeQuery("select empid from employee", resultHandler(data));
||Here you can see displaying process running info to user is called after db call is made; and this will display process window because your execution flow is not blocked by the call of ‘executeQuery’, also you are not doing anything special to achieve this it will be handled out of the box.
Conclusion: Hollywood principle is the key design principle behind non-blocking implementation, and callback and event loop is the technique to achieve asynchronous/non-blocking behaviour.
- Node is designed to be used for applications that are heavy on input/output, but light on computation (computation intensive task should be delegated out of node).
- To leverage single thread programming model (for developers) to achieve simplicity, while handling complex multithreading in the background out of the box.
- To reduce memory overhead that is inherent in request per thread model.
If you say double d = 0.14 and d*100 result will be 14.000000000000002
for detail checkout : http://www.thatisjava.com/java-programming/1715/
Once an interviwer asked me – we know using “instanceof” is bad, can we avoid using it with the help of some pattern (give the name)?
In my 9 years of java programming career I don’t remember that I have used instanceof apart from overriding “equals” method. So first of all this question that “can we avoid its usage with the help of some pattern” made me confuse and I was not able to answer it, later on after doing some reading and trying out some examples I came to the conclusion that its not a right question. Design consideration to avoid “instanceof” in your code totally depend on the problem that you are solving or the requirement you are implementing. Let me explain in detail.
- Is using “instanceof” is bad: Can you avoid its usage when overriding equals method in your java bean? answer is NO. In a situation similar to equals method you cannot avoid its usage, but so far I have not seen any such situation, so presently I think we can avoid its usage apart from equals method, and there is no silver bullet pattern.
- Please read this artical – “http://butunclebob.com/ArticleS.UncleBob.VisitorVersusInstanceOf”, the solution in this article is done using visitor pattern with reflection to avoid “instanceof” usage. What I feel about this solution is that there is no need of visitor and reflection in the solution, however there could be a situation where visitor will help, and my intent here is to show that there is no silver bullet pattern to avoid “instanceof”. The problem mentioned in the above article is – We have courses and we want to generate report about each course, so separate classes are created for courses and course report generators (to achieve separation of concern). The solution provided in the article is trying to identify report generator based on course and then call methods on that report generator to generate report, here the use of reflection with visitor can be easily avoided if we shift data part in course classes (course title, duration, sysRequired, etc) and report generation behaviour in generic report generator or specific report generator. Lets look at generic report generator.
You can see with generic report generator there is no need to check instanceof courses or course report generator, also with the help of builder pattern you can change report structure as required (ex: building report by using only buildTitle and buildBody).
// use course title to generate report title.
Now lets see specific report generator, we can have JavaReportGenerator and AOODReportGenerator, now in solution every time we create a specific report generator we register it (think of Map having course as key and course report generator as value), further we can use factory to return course report generator by providing course to it.
This way we can clearly avoid instanceof and reflection usage as defined in the article above, rather you can see in many situations you can avoid instanceof and reflection using appropriate patterns. Some people think that in case you want to call specific method which was introduced by the sub-class/sub-implementor* needs type checking using “instanceof” (however I think this is wrong as new implementation should go in base class, and sub-classes can avoid this implementation if they want to), but this can be avoided using generics if you are using jdk 5 or above or by using specific report generator implementation.
Some people think “instanceof” introduce lot of if else statement and to avoid that – visitor pattern will help, well I think its wrong, as stated above – refactoring of such code depends on particular implementation, factory, state, builder etc, any pattern can be used depending on the situation. you can even use Predicate (high level pattern**) – please see http://www.infoq.com/presentations/3-Patterns-Cleaner-Code
* in case of interface where you don’t want to break existing implementation by introducing new method in interface.
** pattern mix of several pattern
- Ubuntu 12.0.4 64 Bit
- VMware Player 5.0.1
Use below command to stop all vmware services
sudo /etc/init.d/vmware stop
sudo /etc/init.d/vmware-USBArbitrator stop
Submit EMR Job from Talend
- Amazon account with AccessKey and SecretKey.
- AWS SDK for Java.
- Talend Studio for BigData.
- Pre knowledge on how to create job in Talend.
- Create new job in Talend.
- Use component ‘tLibraryLoad’ and ‘tJava’, and connect them as shown below.
- tLibrary settings: add aws sdk jars in tLibrary using advance settings.
- Use tJava advance settings to import all required dependencies.
- Code to submit MR job to EMR in tJava.
System.out.println(“Starting T Java component for EMR job.”);
//Set creadential (accessKey and secretKey)
//String accessKey = “”;
//String secretKey = “”;
AWSCredentials credentials = new BasicAWSCredentials(accessKey, secretKey);
AmazonElasticMapReduceClient emrClient = new AmazonElasticMapReduceClient(credentials);
StepFactory stepFactory = new StepFactory();//Hadoop jar step
HadoopJarStepConfig jarStepConfig = new HadoopJarStepConfig();
ArrayList<String> args = new ArrayList<String>();
// Debug step config that will help us bad times.
StepConfig enableDebugging = new StepConfig();
// hadoop step config
StepConfig hadoopJarConf = new StepConfig();
// instance config
JobFlowInstancesConfig instancesConfig = new JobFlowInstancesConfig();
// Job request creation.
RunJobFlowRequest request = new RunJobFlowRequest();
// finally submitting job.
RunJobFlowResult result = emrClient.runJobFlow(request);
- Run your job and see the output at Amazon EMR job console.
- In case of failure you can select your job and click ‘Debug’ to see error logs. | <urn:uuid:afab1c33-5bbb-43d1-b0f0-7b7a8d17fd96> | 2.875 | 1,925 | Personal Blog | Software Dev. | 36.760909 | 95,570,622 |
Authors: H. Park, J. Jeong, Y. Kim
Affilation: Hongik University, Korea
Pages: 356 - 359
Keywords: plasma-on-a-chip, atmospheric plasma
We present a plasma-on-a-chip operated in a current controlled bias scheme for atmospheric plasma generation. The plasma-on-a-chip was fabricated using micromachining techniques and includes an array of vertically formed micro gaps between an anode and a cathode, ranging from 5 um to 10 um 1. Use of a few micron gap enables atmospheric plasma generation at a relatively low voltage (~250 V). To enhance stability of the glow discharge, a current controlled bias scheme is suggested using a current mirror circuit. Compared to voltage controlled bias scheme, the current controlled scheme may improve stability of the glow discharge by suppressing excessive current flow occurred during the glow discharge, which may be caused by electrode-sputtering induced gap narrowing or elevated temperature. Such current controlled discharge is also desirable for gas emission spectroscopy where mixed gases with different breakdown voltages are present. Electron and gas temperatures of the generated atmospheric plasma were measured to be 2550 K and 1000 K, respectively. The plasma-on-a-chip presented in this work can be used as a compact versatile plasma source which enhances portability of various plasma applications, such as gas detections and surface treatments.
Nanotech Conference Proceedings are now published in the TechConnect Briefs | <urn:uuid:f2abd7ed-e5a3-4a8b-98ad-a9bd6e2ad4b8> | 2.625 | 298 | Academic Writing | Science & Tech. | 24.632056 | 95,570,625 |
This book is about object-oriented programming with ANSI c. It is latest version 6th edition of ANSI C Pdf Ebook. You can also buy the latest edition of Programming in ANSI C 6th Edition by E. Balaguruswamy pdf from below link.
Here is another option, which is let us c pdf and solutions book, this is a very helpful book for learning c language. All basic and advanced knowledge is cover well. This is the best compositor for balaguruswamy. So just download this lets us c pdf it from below links.
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ANSI now issues two kinds of codes. Although ANSI is apparently the more superior among them both, in addition, there are downsides to using it. ASCII doesn’t have this problem as it is the same wherever you’re on the planet.
TABLE OF CONTENTS:
1. Overview of C
2. Constants Variables, and Data Types
3. Operators and Expressions
4. Managing Input and Output Operations
5. Decision Making and Branching
6. Decision Making and Looping
8. Character Arrays and Strings
9. User-Defined Functions
10. Structures and Unions
12. File Management in C
13. Dynamic Memory Allocation and Linked Lists
14. The Preprocessor
15. Developing a C Program: Some Guidelines
I always love to read this book. It has the vast collection of problems to solve. It helps TO improve your programming and logical thinking in c language. To allow a compiler to check that you are using functions correctly. ANSI c pdf allows you to include a function prototype. Which tell the type of the role and type of each parameter, before you define the function.
Download ANSI C revised 6th edition Programming e-book. The e-book Programming in ANSI C authored by E Balagurusamy, he is the best as well as the popular face in the “Information Technologies literacy movements in India”.There is only another significant change is that you can declare parameter types along with the function.
Again, you can see that this is just a small change. Notice that even if you are using an ANSI compiler you don’t have to use prototypes and the K&R version of the code will work perfectly well. In 1990, an international ANSI standard for C was established which differs from K&R C in the number of ways. The really important difference is the use of function prototypes. Or you can be called it as Initialization of Function.
Download ANSI C revised 6th edition Programming e-book. The e-book Programming in ANSI C authored by E Balagurusamy, he is the best as well as really popular face in the “Information Technologies literacy movements in India”. There is only another major change is that you can declare parameter types along with the function.
Again, you can see that this is just a small change. Notice that even if you are using an ANSI compiler you don’t have to use prototypes and the K&R version of the code will work perfectly well.
Hope you get to understand what is ANSI C? Read the full post on Programming in ANSI C 6th Edition by E. Balaguruswamy pdf free download below.
This unique eBook is actually released in such a manner, that it must be used not only by undergraduate learners in Computer systems but also many pros of Information Modern technology.
This version preserves the articulate circulation and continual, that has been the effectiveness of the book.
- Case Reports with the end of your chapters illustrate real-life applications utilizing in C.
- Code with comments is provided all through the book to illustrate. How the variety of features in the language are placed together. Also, help to accomplish specified tasks
- This book programming in ANSI c helps many programmers in any manner.
- “Just Remember” section with the end from the chapters lists out helpful hints and potential issue.
- Guidelines for developing productive C applications are offered during the final chapter,
- also has a list of some faults that a less experienced C programmer could make.
- Programming Projects mentioned during the appendix give insight.
- how to integrate the several capabilities of C when dealing with significant troubles
Download free pdf Programming in ANSI C 4th Edition by E. Balaguruswamy
In this book, you would get the overall conception of updated Programming language C. This 4th edition of ANSI C book by E. balaguruswamy is available for download.
You must learn about the operators, decision making, constants, variables, branching, looping, pointers, memory allocation, arrays, strings,user-defined function, structure and unions, preprocessor etc. programming in ANSI c is the best book for c language.
You can also solve the exercise with the help of “Exercise solution ebook” of Programming in ANSI C pdf ebook.
Summary Of The Book
For those who are a beginner or new to C language, Programming in ANSI C: Virtual Lab for C Programming 6th Edition is the best book available to initiate the learning process.
Programming in ANSI C: Virtual Lab for C Programming teaches programming language in an easy, as well as logical way. There are a number of tests which help you. You can evaluate automatically and receive feedback.
Dependencies aren’t supported, it will stay a full build. Any perl is going to do, even cygwin. It also includes a resource compiler, letting you compile your Windows resources. TinyCC Assembler supports a lot of the gas syntax. The majority of the compilers that could be safely classified under that category was moved to that page. When the programmer understands these possible problem spots, they are simple, for the large part, to avoid when writing C code. At precisely the same time, most editing changes which don’t modify logic or alignment isn’t going to alter the object code.
The tokens are the very same as C. All internal symbols are at present mangled. If no neighborhood symbol stack is active, it’s added in the worldwide symbol stack. The most suitable operator has to be positive. The range of the variables declared within this context extends to the close of the statement containing the conditional expression.
C is among the oldest currently used programming languages and is among the most commonly used programming languages. ANSI C depends on the POSIX standard. The most recent version of this topic are available at switch Statement (C).
It is possible to skip it if you don’t mean to modify the TCC code. Be aware that the programs aren’t compiled to native code except to code to get executed for the virtual CPU. In case the source code is made in another language and could be shared with others, please contact IDAutomation. A Windows file is currently supplied in the distribution. This document covers these types of incompatibilities. The switch statement can incorporate numerous case instances, but no two case constants within the identical switch statement can have the exact price. This isn’t a major issue in the event the file would be opened in the very same country since there is a high probability they share the exact same code pages.
Arrays are regarded as pointers with the flag collection. All variables in C has to be declared before it is possible to use them and they have to be initialized with an assignment. It’s invalid to call a function that doesn’t have a prior declaration in scope. Never call a function before it’s been declared. Specifically, this is not likely to work for prototyped functions which take a variable number of arguments. This is known as a function that is just a code snippet that asks the computer to process instructions and provide the proper output. For that reason, it can’t be utilized in any manufacturing system.
Sequences have various lengths. The structure has the context required to read a file, for instance, present line number. It contains all the necessary information for a given section. Unfortunately, at the time that I write this, it’s provided just in source form, and you’ll have to compile it yourself.
Incomplete information will hamper your probability of a timely reaction. Detailed information exists at the very top of these files. Additional reference might be made to the true ANSI publication. It is only a handy reference to the typical C library. This guide isn’t a definitive look at the whole ANSI C standard. This guide gives a practical look at the normal C programming language.
The only really important distinction is the usage of function prototypes. Nevertheless, it is something to think about. Now, it might not be the ideal solution. All efforts are taken to be sure the info contained herein is correct, but no guarantees are created. It’s possible to desactivate assembler support if you desire a more compact TinyCC executable (the C compiler doesn’t depend on the assembler). To enable the compiler to check that you’re using functions correctly ANSI C permits you to incorporate a function prototype which provides the sort of the function and the form of each parameter before you define the function.
The kind of switch expression and case constant-expression has to be integral. Verify the languages at the base of this submit. The C language is a quick performing, portable and simple to use language. This usage couldn’t be made compatible with prototypes, therefore ANSI C utilizes a different system.
The pdf version of this book is made the available download for an academic and educational purpose only, i.e. for students and learners this book on the internet.
If you think this violates the Copyright policies of the book/publication, inform me achatap[at]gmail.com, and this post will be removed from the website. | <urn:uuid:ddcecaab-57ba-4f1a-abf2-49a92896a3af> | 2.796875 | 2,125 | Product Page | Software Dev. | 50.307517 | 95,570,656 |
Project for the Photometry of Clusters of Galaxies
The main methods of investigating the structures of clusters of galaxies up to the present time are based on simple galaxy counts. N-body simulations of ensembles of point masses were used to explain these observations. But clusters of galaxies are not ensembles of point masses. The large spectrum of masses of galaxies in clusters as well as the spatial extension of the galaxies will influence the evolution of clusters in a dominant manner. Up to now there exist only very few investigations of the distribution of masses in clusters. They are restricted to the problem of mass segregation in some clusters, as Coma or Centaurus. Such discussions are based upon photometry of galaxies in clusters. Today we consider photometry on photographic plates as the only economic method for the investigation of luminosities of a large number of galaxies. But there is an important disadvantage of this method. It concerns its insufficient accuracy. There are the following main reasons for photometric errors:
Scale errors due to bad calibration of sensitometers and to light diffusion.
Instabilities of the measuring device.
Inhomogeneities in the photographic emulsion.
KeywordsPhotographic Emulsion Point Masse Morphological Type Light Diffusion Photographic Plate
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Unable to display preview. Download preview PDF.
- Baier, F. W., and Ziener, R.: 1988, Astron. Nachr., in preparationGoogle Scholar
- Guiderdoni, B.: 1984, Lecture Notes in Physics, Volume 232, New Aspects of Galaxy Photometry, Proceedings of the. Specialized Meeting of the Eight IAU European Regional Astronomy Meeting, Toulouse, September, 17–21, 1984, Page 211Google Scholar
- Taniguchi, Y.: 1986, The Science Report of the Tohoku University, Eight Series, Vol. 6, No 3Google Scholar
- Vaucouleurs, G. de: 1977, “The Evolution of Galaxies and Stellar Populations”, Yale University Conference, May 19–21Google Scholar
- Ziener, R.: 1976, Dissertation, AdW der DDRGoogle Scholar
- Ziener, R.: 1987, This workshopGoogle Scholar
© Springer-Verlag Berlin Heidelberg 1988 | <urn:uuid:f40f9278-f5a1-46ad-acce-8359d2a54551> | 2.78125 | 491 | Academic Writing | Science & Tech. | 35.191071 | 95,570,657 |
Oh, Verkade said, that's just a prank. Go hide around the corner and do some peeking until the joker shows up again. Thirty minutes later Hendricker was back in Verkade's office.
"You've got to see this," Verkade remembers him saying.
What they saw was a wooden stick falling apart and sinking into the chemical compound that had been the basis for Verkade's doctoral dissertation.
"That's an interesting observation," Verkade said at the time.
It was so interesting he asked Iowa State to consider a patent application. But that was a long time before breaking down plant fibers to produce ethanol was linked to energy independence and national security. So the university didn't move on a patent back then. And Verkade, now a University Professor in chemistry, moved on with his work in catalysis and molecular design.
A few years ago, George Kraus, another University Professor of chemistry at Iowa State, brought up Verkade's story of the dissolving wood. He said that compound could be a way to break down the tough cellulose that forms the structure of a plant's cell walls. Breaking down the cellulose can release the simple sugars that are fermented into ethanol. Making that happen could add some value to Iowa crops or the fibrous co-products of ethanol production.
Verkade followed up with a proposal for U.S. Department of Energy funding from the Midwest Consortium for Biobased Products and Bioenergy led by Purdue University in West Lafayette, Ind. He won a two-year, $125,000 grant and enlisted the research help of Reed Oshel, an Iowa State graduate student in biorenewable resources and technology.
They started using the chemical compound on distillers dried grains, a co-product of ethanol production. The initial results weren't encouraging. Verkade was ready to stop pursuing additional funding for the project.
But, earlier this fall, the researchers treated the distillers dried grains with equal measures of the chemical compound and water. That mixture broke down 85 to 95 percent of the cellulose so it could be dissolved in water.
"That opened a whole new door for us," Verkade said. "We knew we were tearing some things up in the cellulose."
They've since tried experiments on model compounds of cellulose. Those experiments have been promising. And now they're working to see if a simpler, cheaper version of the compound can also break down cellulose.
"We have preliminary evidence that it works, too," Verkade said.
Verkade isn't identifying the compound until he can explore the potential for patents. But he's working on a grant proposal that would keep the research going. There are still questions to answer about the compound's performance and characteristics as a pre-treatment for converting cellulose to ethanol. Verkade also wants to see how the compound works on corn stalks, switchgrass and other crops grown for their fiber. And tests need to be done to determine the compound's compatibility with fermentation enzymes.
"This is an exciting time," said the 72-year-old chemist. "I'm now cautiously optimistic about this."
John Verkade | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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- 1 Final Non Access Modifiers
- 2 Abstract Non Access Modifier
- 3 Synchronized Non Access Modifier
- 4 Native Non Access Modifier
- 5 Strictfp Non Access Modifier
In this article you will learn about Non Access Modifiers in Java. Below are the Non Access Modifiers available in Java.
Final Non Access Modifiers
Final modifiers are applicable to :
Final Class :
A Class when set to final cannot be extended by any other Class.
Example: A String Class in java.lang package
Final Method :
A Method when set to final cannot be overridden by any subclass.
Final Variable :
When a variable is set to final, its value cannot be changed. Final variables are like constants.
Example : public static final int i = 10;
Abstract Non Access Modifier
Abstract modifiers are applicable to:
An abstract Class can have abstract Methods. A Class can also be an abstract class without having any abstract Methods in it. If a Class has an abstract Method , the Class becomes an abstract Class.
Abstract Method :
Abstract Methods are those Methods which does not have a body but only a signature.
Example : public abstract void method();
Synchronized Non Access Modifier
Synchronized modifiers are applicable to
Synchronized Methods can be accessed by only one thread at a time.
Native Non Access Modifier
Native modifiers are applicable to
Naive Methods indicate that the method is implemented on a platform dependent code.
Strictfp Non Access Modifier
Strictfp modifiers are applicable to
Strictfp Class / Method
Strictfp non access modifier forces floating point or floating point operation to adhere to IEEE 754 standard.
Note*: Strictfp non access modifier cannot be applied on a variable.
- Non Access Modifiers available in Java are Static, final, abstract, synchronized & Volatile
- Static keyword can be applied to Variables & Methods.
- Static Variable are those variables which are not associated to any instance but it is associated to class means all instances will access the same single copy of variable.
- Local variables can not be declared as Static.
- Static keyword can also be applied to Methods. They will work for all the instances and they will not be dependent on instances created.
- Final modifier can be applied to method and variables.
- Final is the only modifier which will be available to local variable.
- Once declared as final value of the variable can not be changed.
- Final variable don’t get default value opposed to instance variable coz value can’t be changed once assigned.
- Final method can not be overriden. | <urn:uuid:82ea193a-81c1-46be-88df-9dd7a5611451> | 3.6875 | 554 | Documentation | Software Dev. | 39.279971 | 95,570,674 |
The project is very simple, u have to extract license plate area of the car.
You don't have to do text recognition, just the extraction of the plate.
In Malaysia, license plates are black and this project is from Malaysia.
Since the license plates are black, the text inside the plate is a light color (mostly white).
Below is one approach that I recommend being a coder myself:
One method could be to extract all the pixels whose color is black or near black, and discard all other colors or pixels in the image. Whether the color of a pixel is black or near black can be recognized as below:
Say RBG of the color is (X, Y, Z) coordinates.
Black is (0,0,0). Distance of a color (X,Y,Z) from black (0,0,0) is sqrt((X-0)^2+(Y-0)^2+(Z-0)^2) or sqrt(X^2+Y^2+Z^2). Now if this distance is smaller than a threshold (t, say 50). Further, if this doesn't turn out to be accurate model, u can further incorporate another limit that Abs(X-Y), Abs(Y-Z), Abs(Z-X) should be less than some threshold, d, to give it a tendency of choosing either or near black or near grey.
Once all the dark pixels are extracted, make a vertical line at the center of the image. Loop through all the chosen dark pixels that fall on that line. Now some of these pixels are definitely going to be a part of the plate. Follow connected component labeling algo on each pixel to recursively mark all the pixels that are connected directly or indirectly to the current pixel in the loop. Once connected components have been performed, one of the components out of all will be the plate, which can be identified easily through some trivial logic (I leave up to you to figure out, but u can ask me if u can't figure out).
However, you are free to use your own methods, the above was just a suggestion of how I would do it.
Below is the description directly from the client:
Write a python script to process an image of cars and extract the license plate.
Text recognition is not needed, only extraction of the rectangular area of the license plate.
Following algorithms could be helpful to implement.
(Below techniques are only suggested by me, but you can use any method/algos or combination of algos. In the end, you will end up with an algorithm around histogram algo)
1-grey scale - [url removed, login to view]
2-binary - [url removed, login to view]
3-erosion - [url removed, login to view]
4-dialation - [url removed, login to view]
5-edge detection - [url removed, login to view]
6-histogram - [url removed, login to view]
And you may use PIL, numpy, matplot, opencv libraries.
Whoever bids $150 or less first will be awarded the project right away. Only if none of the bidders bid $150 or less, then I will increase the price.
11 freelancers estão ofertando em média $176 para esse trabalho
Hello, Can you send me a sample image of the license. It is easy for me to do, But i want to make sure it is all you need :) Please send me the image that needs to extract license plate area of the car
I did this project before Please send me the sample images to give you the plan for this project. I have been working in opencv for 8 years. Please check my profle for more information | <urn:uuid:4fa7286f-9ada-4640-be53-6302414e8e70> | 2.78125 | 796 | Product Page | Software Dev. | 59.921637 | 95,570,676 |
Groundbreaking research by the National Physical Laboratory's (NPL) Quantum Detection Group and an international team of collaborators is underpinning the biggest change in the Système Internationale d'unités (SI Units) since the system began 50 years ago.
It has long been the goal of scientists to relate all of the unit definitions to fundamental constants of nature, making them stable and universal, and giving them closer links to each other and the quantities they measure.
Key units to be redefined are the kilogram (mass) and the ampere (electric current). Presently the kilogram is defined by a physical lump of platinum-iridium and the ampere is defined via the force produced between two wires.
The goal is to define the kilogram in terms the Planck constant h and the ampere in terms of the electron charge e.
Making this change relies on the exactness of the relationships that link these constants to measurable quantities.
The quantum Hall effect defines a relationship between these two fundamental physical constants. Experiments are needed to test the quantum Hall effect in different materials in order to prove whether or not it is truly universal.
Until recently the effect was exclusively observed in a few semiconductor materials. A few years ago the quantum Hall effect was also observed by the same team in graphene, a completely different type of material with a very different electronic structure.
This research directly compared the quantum Hall effect in graphene with that observed in a traditional semiconductor material. Graphene is hotly tipped to surpass conventional materials in many important applications, partly due to its extraordinary electrical properties.
The results confirmed that the quantum Hall effect is truly universal with an uncertainty level of 86 parts per trillion, supporting the redefinition of the kilogram and ampere. The quantum Hall effect in graphene is so good that it should be the material of choice for quantum resistance metrology.
The discovery was today highlighted in Nature as a leading piece of research.
JT Janssen, NPL Science Fellow and the lead author of the research, said: "Many metrology laboratories around the world have been striving to do this experiment and it is a real achievement that the NPL team and its co-workers were the first to get this key result. It turns out that the quantum Hall effect in graphene is very robust and easy to measure - not bad for a material that was only discovered six years ago."
More information: Read paper in New Journal of Physics: http://iopscience. … 13/9/093026/
National Physical Laboratory | <urn:uuid:7a95f067-f55e-4c9a-8f84-0bf076e9c1e1> | 3.578125 | 523 | News (Org.) | Science & Tech. | 31.284602 | 95,570,685 |
Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?
This magic square has operations written in it, to make it into a maze. Start wherever you like, go through every cell and go out a total of 15!
There are 44 people coming to a dinner party. There are 15 square tables that seat 4 people. Find a way to seat the 44 people using all 15 tables, with no empty places.
This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?
Zumf makes spectacles for the residents of the planet Zargon, who have either 3 eyes or 4 eyes. How many lenses will Zumf need to make all the different orders for 9 families?
Using the statements, can you work out how many of each type of rabbit there are in these pens?
This problem is based on the story of the Pied Piper of Hamelin. Investigate the different numbers of people and rats there could have been if you know how many legs there are altogether!
Can you arrange 5 different digits (from 0 - 9) in the cross in the way described?
Cherri, Saxon, Mel and Paul are friends. They are all different ages. Can you find out the age of each friend using the information?
On my calculator I divided one whole number by another whole number and got the answer 3.125. If the numbers are both under 50, what are they?
Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?
This article for teachers describes how modelling number properties involving multiplication using an array of objects not only allows children to represent their thinking with concrete materials,. . . .
If you had any number of ordinary dice, what are the possible ways of making their totals 6? What would the product of the dice be each time?
There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?
In a Magic Square all the rows, columns and diagonals add to the 'Magic Constant'. How would you change the magic constant of this square?
In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?
Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?
Use your logical-thinking skills to deduce how much Dan's crisps and ice-cream cost altogether.
Number problems at primary level that require careful consideration.
A group of children are using measuring cylinders but they lose the labels. Can you help relabel them?
Can you find which shapes you need to put into the grid to make the totals at the end of each row and the bottom of each column?
There were chews for 2p, mini eggs for 3p, Chocko bars for 5p and lollypops for 7p in the sweet shop. What could each of the children buy with their money?
Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?
Can you each work out the number on your card? What do you notice? How could you sort the cards?
What do you notice about the date 03.06.09? Or 08.01.09? This challenge invites you to investigate some interesting dates yourself.
Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.
This challenge asks you to investigate the total number of cards that would be sent if four children send one to all three others. How many would be sent if there were five children? Six?
Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
A game for 2 people. Use your skills of addition, subtraction, multiplication and division to blast the asteroids.
Can you design a new shape for the twenty-eight squares and arrange the numbers in a logical way? What patterns do you notice?
If the answer's 2010, what could the question be?
Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?
The triangles in these sets are similar - can you work out the lengths of the sides which have question marks?
The Scot, John Napier, invented these strips about 400 years ago to help calculate multiplication and division. Can you work out how to use Napier's bones to find the answer to these multiplications?
We can arrange dots in a similar way to the 5 on a dice and they usually sit quite well into a rectangular shape. How many altogether in this 3 by 5? What happens for other sizes?
Well now, what would happen if we lost all the nines in our number system? Have a go at writing the numbers out in this way and have a look at the multiplications table.
What is the sum of all the three digit whole numbers?
The clockmaker's wife cut up his birthday cake to look like a clock face. Can you work out who received each piece?
There are over sixty different ways of making 24 by adding, subtracting, multiplying and dividing all four numbers 4, 6, 6 and 8 (using each number only once). How many can you find?
Peter, Melanie, Amil and Jack received a total of 38 chocolate eggs. Use the information to work out how many eggs each person had.
Mr McGregor has a magic potting shed. Overnight, the number of plants in it doubles. He'd like to put the same number of plants in each of three gardens, planting one garden each day. Can he do it?
Given the products of adjacent cells, can you complete this Sudoku?
Can you find different ways of creating paths using these paving slabs?
Here is a chance to play a version of the classic Countdown Game.
Skippy and Anna are locked in a room in a large castle. The key to that room, and all the other rooms, is a number. The numbers are locked away in a problem. Can you help them to get out?
Here are the prices for 1st and 2nd class mail within the UK. You have an unlimited number of each of these stamps. Which stamps would you need to post a parcel weighing 825g?
Look on the back of any modern book and you will find an ISBN code. Take this code and calculate this sum in the way shown. Can you see what the answers always have in common?
EWWNP means Exploring Wild and Wonderful Number Patterns Created by Yourself! Investigate what happens if we create number patterns using some simple rules.
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones. | <urn:uuid:78746f59-ad2b-4814-9e44-06280dd0b977> | 3.125 | 1,565 | Content Listing | Science & Tech. | 72.025198 | 95,570,694 |
A sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central hexavalent sulfur atom is double bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents.
The general structural formula is R–S(=O)2–R′ where R and R′ are the organic groups. Thioethers, often referred to as sulfides, are often the precursors to sulfones by organic oxidation through the intermediate formation of sulfoxides. For example, dimethyl sulfide is oxidized to dimethyl sulfoxide and then to dimethyl sulfone. In the Ramberg-Bäcklund Reaction and the Julia olefination sulfones are converted to alkenes through the elimination of sulfur dioxide.
The industrially useful sulfone is sulfolane, a cyclic molecule with the formula (CH2)4SO2. It is typically prepared, not by oxidation of the thioether, but by addition of sulfur dioxide to 1,3-butadiene, followed by hydrogenation of the resulting sulfolene.
Some polymers containing sulfone groups have gained prominence in the field of engineering plastics. Various materials exhibit high strength and resistance to oxidation, corrosion, high temperatures, and creep under stress. For example, some are valuable as replacements for copper in domestic hot water plumbing. Precursors to such polymers are the sulfones bisphenol S and 4,4'-dichlorodiphenyl sulfone.
Examples of sulfones in pharmacology include dapsone, a drug formerly used as an antibiotic to treat leprosy, dermatitis herpetiformis, tuberculosis, or pneumocystis pneumonia (PCP). Several of its derivatives, such as promin, have similarly been studied or actually been applied in medicine, but in general sulfones are of far less prominence in pharmacology than for example the sulfonamides.
In the literature, particularly lay literature, sulfones commonly are confused with sulfonamides, though the latter have one carbon and one nitrogen atom attached to the sulfur atom, instead of two carbon atoms. The pharmacological mechanisms accordingly differ from that of the sulfonamides. However, in practice one commonly sees frequent references to dapsone and promin as sulfonamides. Probably this is partly because few pharmaceuticals are in fact sulfones. The use of the long-standing alternative spelling sulphone is discouraged by IUPAC; it is definitely undesirable to have two spellings in simultaneous common use, and it was agreed to discontinue the ph spelling as the more archaic.
|Wikimedia Commons has media related to Sulfones.|
- Hornback, Joseph (2006). Organic Chemistry. Australia: Thomson Brooks/Cole. ISBN 978-0-534-38951-2.
- Carey, Francis A.; Sundberg, Richard J. (2007). Advanced Organic Chemistry. Berlin: Springer. ISBN 978-0-387-68354-6.
- Folkins, Hillis O. (2005). "Benzene". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_475.
- Fink, Johannes (2008). High Performance Polymers. Norwich: William Andrew. ISBN 978-0-8155-1580-7.
- Craig, Charles R.; Stitzel, Robert E. (2004). Modern Pharmacology with Clinical Applications. Hagerstwon: Lippincott Williams & Wilkins. ISBN 978-0-7817-3762-3.
- Drill, Victor Alexander; Di Palma, Joseph R. (1971). Drill's Pharmacology in Medicine. New York: McGraw-Hill. ISBN 978-0-07-017006-3. | <urn:uuid:b69e3667-e978-4dd9-8fda-639ddffd5120> | 3.34375 | 816 | Knowledge Article | Science & Tech. | 37.196328 | 95,570,705 |
Gemini Observatorys new spectrograph, without the help of adaptive optics, recently captured images that are among the sharpest ever obtained of astronomical objects from the ground.
Along with the images and spectra acquired during recent commissioning of the Gemini Multi-Object Spectrograph (GMOS) on the 8-metre Gemini South Telescope in Chile, one image is particularly compelling. This Gemini image reveals remarkable details, previously only seen from space, of the Hickson Compact Group 87 (HCG87). HCG87 is a diverse group of galaxies located about 400 million light years away in the direction of the constellation Capricornus. A striking comparison with the Hubble Space Telescope image of this object, including resolution data, can be viewed at http://www.gemini.edu/media/images_2003-3.html
"Historically, the main advantage of large ground-based telescopes, like Gemini, is the huge mirrors that collect significantly more light for spectroscopy than is possible with a telescope in space," said Phil Puxley, Gemini Associate Director of the Gemini South Telescope located on Cerro Pachón, Chile. He explains "The Hubble Space Telescope is able to do things that are impossible from the ground. However, ground-based telescopes like Gemini, when conditions are right, approach the quality of optical images now only possible from space. One key area - spectroscopy of faint objects, which requires large apertures and fine image quality - is where large telescopes like Gemini provide a powerful, complementary capability to space-based telescopes."
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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The Bay Delta's Cutest Endangered Species Hangs On | KCET
The Bay Delta's Cutest Endangered Species Hangs On
An explanatory series focusing on one of the most complex issues facing California: water sharing. And at its core is the Sacramento-San Joaquin Bay Delta. Stay with kcet.org/baydelta for all the project's stories.
Not all endangered species are majestic, or unusual-looking, or unfamiliar. Some of them look like they might merit legions of squeeing fans on YouTube. And one such critter still ekes out a living in San Francisco Bay's beleaguered but recovering salt marshes.
An oddly attractive plant called pickleweed grows in the Bay's salt marshes. Its segmented stems, often tinted a bright red (especially in cold winters), are usually covered in a frosty rime of salt. Pickleweed is able to grow in salt water partly because it can excrete that salt rather than accumulating it in its stems' tissue.
If an animal was to subsist on pickleweed, it would need to be able to cope with all that salt -- especially since most of the available drinking water would have salt in it as well. Fortunately for the salt marsh harvest mouse, this surprisingly cute endangered species is able to do just that.
Listed as Endangered under the Federal Endangered Species Act in 1970, the three-inch mouse -- Reithrodontomys raviventris -- relies almost completely on pickleweed as cover and as food.
Two subspecies of salt marsh harvest mouse live in the Bay's salt marshes. A southern subspecies, Reithrodontomys raviventris raviventris, inhabits what's left of the Central and South Bay's pickleweed marshes, while the northern -- Reithrodontomys raviventris halicoetes -- ekes out a continued existence in the marshes that fringe San Pablo and Suisun bays. You can distinguish between the two subspecies either by where you happen to see one, or by the color of their bellies. The southern subspecies has the reddish belly for which the species got the monicker "raviventris," while the northern mice have white bellies.
Close relatives of the plains harvest mouse of Mexico and the central U.S., salt marsh harvest mice are well-adapted to the specific conditions in the pickleweed. Their kidneys are highly efficient at removing salt from their bloodstream. The northern subspecies can actually subsist indefinitely on seawater. While the southern mouse can't quite commit that far to the saline life, it seems to prefer brackish water over fresh. And both subspecies eat large amounts of the salt-encrusted stems of pickleweed without apparent problems.
The mice are able swimmers, which helps at high tide, as well as any time that pickleweed cover across the slough looks tempting. That ability only goes so far, though. During high tides, when pickleweed stands might become completely submerged for hours on end, salt marsh harvest mice will often retreat to higher ground covered with salt-tolerant vegetation.
If there is any such "escape habitat" handy, that is. In the Central and South portions of San Francisco Bay tides are higher than they are farther north, and that -- combined with the aggressive shoreline development of much of that part of the Bay -- means high tides can leave the southern subspecies with nowhere to retreat to. That can mean losing nests of baby mice to drowning, as well as making it easier for predators to pick off adult mice who are forced out into the open.
Among the local animals likely to eat such exposed mice are feral cats, foxes, herons, egrets, gulls, and even Ridgway's rails, there being no solidarity among endangered species.
Fortunately, salt marsh harvest mice are pretty gregarious and unaggressive, meaning that a lot of them can share the same stretch of pickleweed habitat, if that habitat is big enough to support a viable population.
That's the rub, though: there's a size below which a pickleweed stand can't support a viable mouse population. And so habitat fragmentation of the Bay's saltmarsh, with once-broad stands of pickleweed broken up by roads, fill, riprap, commercial development, and other intrusions, have hit the salt marsh harvest mouse hard. Less than 10 percent of its original habitat exists at all, and much of that may be too fragmented, or too polluted or populated by imported predators such as cats, to do the mice any good.
As critically endangered species go, though, the salt marsh harvest mouse is luckier than some. As we wrote here, a burgeoning wetland protection movement in the 1970s changed public opinion about the salt marsh, and helped protect and even restore some of the last bits of the mouse's remaining habitat.
As that understanding spread, the mouse and its neighbor the Ridgway's rail became keystone species, in a sense: by protecting their habitat, we protect the habitat and the fates of other species dependent on the salt marsh, though few of them are as charismatic as a cute mouse.
For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.
The stocks of two of the largest private prison contractors skyrocketed in the month after President Trump’s inauguration and have continued to grow.
Here are some of the coolest ways to chill out in the greater Palm Springs area.
A special ten-hour marathon revisting the best of "Visiting With Huell Howser" begins Sunday, August 5 at 10:00 a.m. on KCET.
Following a screening of “Eighth Grade”, writer/director Bo Burnham and actress Elsie Fisher attended a Q&A hosted by Cinema Series host Pete Hammond.
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Porifera , Cnidaria and Ctenophora Specimen Lab. 1. What phylum is this organism in?. 2. What class is the sponge classified in?. 3. Why?. 4. What type of symmetry does this organism exhibit?.
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5. The hard spike-y structures are spicules. What two materials can spicules be made of? Circle the material you think this sponge’s spicules are made of.
16. Jellyfish have two body plans. The ephyra is the transitional body form produced by a ____asexually. The ephrya grows to become an organism with the _______ form. | <urn:uuid:81805e53-2524-4b50-a0c8-8303e1342fb7> | 3.125 | 209 | Truncated | Science & Tech. | 60.164559 | 95,570,766 |
Concept: Measurement of biodiversity
Two recent studies have reanalyzed previously published data and found that when data sets were analyzed independently, there was limited support for the widely accepted hypothesis that changes in the microbiome are associated with obesity. This hypothesis was reconsidered by increasing the number of data sets and pooling the results across the individual data sets. The preferred reporting items for systematic reviews and meta-analyses guidelines were used to identify 10 studies for an updated and more synthetic analysis. Alpha diversity metrics and the relative risk of obesity based on those metrics were used to identify a limited number of significant associations with obesity; however, when the results of the studies were pooled by using a random-effect model, significant associations were observed among Shannon diversity, the number of observed operational taxonomic units, Shannon evenness, and obesity status. They were not observed for the ratio of Bacteroidetes and Firmicutes or their individual relative abundances. Although these tests yielded small P values, the difference between the Shannon diversity indices of nonobese and obese individuals was 2.07%. A power analysis demonstrated that only one of the studies had sufficient power to detect a 5% difference in diversity. When random forest machine learning models were trained on one data set and then tested by using the other nine data sets, the median accuracy varied between 33.01 and 64.77% (median, 56.68%). Although there was support for a relationship between the microbial communities found in human feces and obesity status, this association was relatively weak and its detection is confounded by large interpersonal variation and insufficient sample sizes.
The peanut (Arachis hypogaea) is an important oil crop. Breeding for high oil content is becoming increasingly important. Wild Arachis species have been reported to harbor genes for many valuable traits that may enable the improvement of cultivated Arachis hypogaea, such as resistance to pests and disease. However, only limited information is available on variation in oil content. In the present study, a collection of 72 wild Arachis accessions representing 19 species and 3 cultivated peanut accessions were genotyped using 136 genome-wide SSR markers and phenotyped for oil content over three growing seasons. The wild Arachis accessions showed abundant diversity across the 19 species. A. duranensis exhibited the highest diversity, with a Shannon-Weaver diversity index of 0.35. A total of 129 unique alleles were detected in the species studied. A. rigonii exhibited the largest number of unique alleles (75), indicating that this species is highly differentiated. AMOVA and genetic distance analyses confirmed the genetic differentiation between the wild Arachis species. The majority of SSR alleles were detected exclusively in the wild species and not in A. hypogaea, indicating that directional selection or the hitchhiking effect has played an important role in the domestication of the cultivated peanut. The 75 accessions were grouped into three clusters based on population structure and phylogenic analysis, consistent with their taxonomic sections, species and genome types. A. villosa and A. batizocoi were grouped with A. hypogaea, suggesting the close relationship between these two diploid wild species and the cultivated peanut. Considerable phenotypic variation in oil content was observed among different sections and species. Nine alleles were identified as associated with oil content based on association analysis, of these, three alleles were associated with higher oil content but were absent in the cultivated peanut. The results demonstrated that there is great potential to increase the oil content in A. hypogaea by using the wild Arachis germplasm.
Diversity indices might be used to assess the impact of treatments on the relative abundance patterns in species communities. When several treatments are to be compared, simultaneous confidence intervals for the differences of diversity indices between treatments may be used. The simultaneous confidence interval methods described until now are either constructed or validated under the assumption of the multinomial distribution for the abundance counts. Motivated by four example data sets with background in agricultural and marine ecology, we focus on the situation when available replications show that the count data exhibit extra-multinomial variability. Based on simulated overdispersed count data, we compare previously proposed methods assuming multinomial distribution, a method assuming normal distribution for the replicated observations of the diversity indices and three different bootstrap methods to construct simultaneous confidence intervals for multiple differences of Simpson and Shannon diversity indices. The focus of the simulation study is on comparisons to a control group. The severe failure of asymptotic multinomial methods in overdispersed settings is illustrated. Among the bootstrap methods, the widely known Westfall-Young method performs best for the Simpson index, while for the Shannon index, two methods based on stratified bootstrap and summed count data are preferable. The methods application is illustrated for an example.
Glacio-marine fjords occur widely at high latitudes and have been extensively studied in the Arctic, where heavy meltwater inputs and sedimentation yield low benthic faunal abundance and biodiversity in inner-middle fjords. Fjord benthic ecosystems remain poorly studied in the subpolar Antarctic, including those in extensive fjords along the West Antarctic Peninsula (WAP). Here we test ecosystem predictions from Arctic fjords on three subpolar, glacio-marine fjords along the WAP. With seafloor photographic surveys we evaluate benthic megafaunal abundance, community structure, and species diversity, as well as the abundance of demersal nekton and macroalgal detritus, in soft-sediment basins of Andvord, Flandres and Barilari Bays at depths of 436-725 m. We then contrast these fjord sites with three open shelf stations of similar depths. Contrary to Arctic predictions, WAP fjord basins exhibited 3 to 38-fold greater benthic megafaunal abundance than the open shelf, and local species diversity and trophic complexity remained high from outer to inner fjord basins. Furthermore, WAP fjords contained distinct species composition, substantially contributing to beta and gamma diversity at 400-700 m depths along the WAP. The abundance of demersal nekton and macroalgal detritus was also substantially higher in WAP fjords compared to the open shelf. We conclude that WAP fjords are important hotspots of benthic abundance and biodiversity as a consequence of weak meltwater influences, low sedimentation disturbance, and high, varied food inputs. We postulate that WAP fjords differ markedly from their Arctic counterparts because they are in earlier stages of climate warming, and that rapid warming along the WAP will increase meltwater and sediment inputs, deleteriously impacting these biodiversity hotspots. Because WAP fjords also provide important habitat and foraging areas for Antarctic krill and baleen whales, there is an urgent need to develop better understanding of the structure, dynamics and climate-sensitivity of WAP subpolar fjord ecosystems.
Seamounts are proposed to be hotspots of deep-sea biodiversity, a pattern potentially arising from increased productivity in a heterogeneous landscape leading to either high species co-existence or species turnover (beta diversity). However, studies on individual seamounts remain rare, hindering our understanding of the underlying causes of local changes in beta diversity. Here, we investigated processes behind beta diversity using ROV video, coupled with oceanographic and quantitative terrain parameters, over a depth gradient in Annan Seamount, Equatorial Atlantic. By applying recently developed beta diversity analyses, we identified ecologically unique sites and distinguished between two beta diversity processes: species replacement and changes in species richness. The total beta diversity was high with an index of 0.92 out of 1 and was dominated by species replacement (68%). Species replacement was affected by depth-related variables, including temperature and water mass in addition to the aspect and local elevation of the seabed. In contrast, changes in species richness component were affected only by the water mass. Water mass, along with substrate also affected differences in species abundance. This study identified, for the first time on seamount megabenthos, the different beta diversity components and drivers, which can contribute towards understanding and protecting regional deep-sea biodiversity.
Field studies of wild vertebrates are frequently associated with extensive collections of banked fecal samples-unique resources for understanding ecological, behavioral, and phylogenetic effects on the gut microbiome. However, we do not understand whether sample storage methods confound the ability to investigate interindividual variation in gut microbiome profiles. Here, we extend previous work on storage methods for gut microbiome samples by comparing immediate freezing, the gold standard of preservation, to three methods commonly used in vertebrate field studies: lyophilization, storage in ethanol, and storage in RNAlater. We found that the signature of individual identity consistently outweighed storage effects: alpha diversity and beta diversity measures were significantly correlated across methods, and while samples often clustered by donor, they never clustered by storage method. Provided that all analyzed samples are stored the same way, banked fecal samples therefore appear highly suitable for investigating variation in gut microbiota. Our results open the door to a much-expanded perspective on variation in the gut microbiome across species and ecological contexts.
Estimations of microbial community diversity based on metagenomic data sets are affected, often to an unknown degree, by biases derived from insufficient coverage and reference database-dependent estimations of diversity. For instance, the completeness of reference databases cannot be generally estimated since it depends on the extant diversity sampled to date, which, with the exception of a few habitats such as the human gut, remains severely undersampled. Further, estimation of the degree of coverage of a microbial community by a metagenomic data set is prohibitively time-consuming for large data sets, and coverage values may not be directly comparable between data sets obtained with different sequencing technologies. Here, we extend Nonpareil, a database-independent tool for the estimation of coverage in metagenomic data sets, to a high-performance computing implementation that scales up to hundreds of cores and includes, in addition, a k-mer-based estimation as sensitive as the original alignment-based version but about three hundred times as fast. Further, we propose a metric of sequence diversity (N d ) derived directly from Nonpareil curves that correlates well with alpha diversity assessed by traditional metrics. We use this metric in different experiments demonstrating the correlation with the Shannon index estimated on 16S rRNA gene profiles and show that N d additionally reveals seasonal patterns in marine samples that are not captured by the Shannon index and more precise rankings of the magnitude of diversity of microbial communities in different habitats. Therefore, the new version of Nonpareil, called Nonpareil 3, advances the toolbox for metagenomic analyses of microbiomes. IMPORTANCE Estimation of the coverage provided by a metagenomic data set, i.e., what fraction of the microbial community was sampled by DNA sequencing, represents an essential first step of every culture-independent genomic study that aims to robustly assess the sequence diversity present in a sample. However, estimation of coverage remains elusive because of several technical limitations associated with high computational requirements and limiting statistical approaches to quantify diversity. Here we described Nonpareil 3, a new bioinformatics algorithm that circumvents several of these limitations and thus can facilitate culture-independent studies in clinical or environmental settings, independent of the sequencing platform employed. In addition, we present a new metric of sequence diversity based on rarefied coverage and demonstrate its use in communities from diverse ecosystems.
We aimed to identify regional centres of plant biodiversity in South Australia, a sub-continental land area of 983,482 km2, by mapping a suite of metrics. Broad-brush conservation issues associated with the centres were mapped, specifically climate sensitivity, exposure to habitat fragmentation, introduced species and altered fire regimes. We compiled 727,417 plant species records from plot-based field surveys and herbarium records and mapped the following: species richness (all species; South Australian endemics; conservation-dependent species; introduced species); georeferenced weighted endemism, phylogenetic diversity, georeferenced phylogenetic endemism; and measures of beta diversity at local and state-wide scales. Associated conservation issues mapped were: climate sensitivity measured via ordination and non-linear modelling; habitat fragmentation represented by the proportion of remnant vegetation within a moving window; fire prone landscapes assessed using fire history records; invasive species assessed through diversity metrics, species distribution and literature. Compared to plots, herbarium data had higher spatial and taxonomic coverage but records were more biased towards major transport corridors. Beta diversity was influenced by sampling intensity and scale of comparison. We identified six centres of high plant biodiversity for South Australia: Western Kangaroo Island; Southern Mount Lofty Ranges; Anangu Pitjantjatjara Yankunytjatjara lands; Southern Flinders Ranges; Southern Eyre Peninsula; Lower South East. Species composition in the arid-mediterranean ecotone was the most climate sensitive. Fragmentation mapping highlighted the dichotomy between extensive land-use and high remnancy in the north and intensive land-use and low remnancy in the south. Invasive species were most species rich in agricultural areas close to population centres. Fire mapping revealed large variation in frequency across the state. Biodiversity scores were not always congruent between metrics or datasets, notably for categorical endemism to South Australia versus georeferenced weighted endemism, justifying diverse approaches and cautious interpretation. The study could be extended to high resolution assessments of biodiversity centres and cost:benefit analysis for interventions.
Traditional culture techniques have shown that increased bacterial colonization is associated with viral colonization; however, the influence of viral colonization on the whole microbiota composition is less clear. We thus aimed to understand the interaction of viral infections and the nasal microbiota in early life to appraise their roles in disease development. Thirty-two healthy, unselected infants were included in this prospective longitudinal cohort study within the first year of life. Biweekly nasal swabs (n = 559) were taken, and the microbiota was analyzed by 16S rRNA pyrosequencing, and 10 different viruses and 2 atypical bacteria were characterized by real-time PCR (combination of seven duplex samples). In contrast to asymptomatic human rhinovirus (HRV) colonization, symptomatic HRV infections were associated with lower alpha diversity (Shannon diversity index [SDI]), higher bacterial density (PCR concentration), and a difference in beta diversities (Jaccard and Bray-Curtis index) of the microbiota. In addition, infants with more frequent HRV infections had a lower SDI at the end of the study period. Overall, changes in the microbiota associated with symptomatic HRV infections were characterized by a loss of microbial diversity. The interaction between HRV infections and the nasal microbiota in early life might be of importance for later disease development and indicate a potential approach for future interventions. IMPORTANCE Respiratory viral infections are very frequent in infancy and of importance in acute and chronic disease development. Infections with human rhinovirus (HRV) are, e.g., associated with the later development of asthma. We found that only symptomatic HRV infections were associated with acute changes in the nasal microbiota, mainly characterized by a loss of microbial diversity. Infants with more frequent symptomatic HRV infections had a lower bacterial diversity at the end of the first year of life. Whether the interaction between viruses and the microbiota is one pathway contributing to asthma development will be assessed in the follow-ups of these children. Independent of that, measurements of microbial diversity might represent a potential marker for risk of later lung disease or monitoring of early life interventions.
The evolutionary dissimilarity between communities (phylogenetic beta diversity PBD) has been increasingly explored by ecologists and biogeographers to assess the relative roles of ecological and evolutionary processes in structuring natural communities. Among PBD measures, the PhyloSor and UniFrac indices have been widely used to assess the level of turnover of lineages over geographical and environmental gradients. However, these indices can be considered as ‘broad-sense’ measures of phylogenetic turnover as they incorporate different aspects of differences in evolutionary history between communities that may be attributable to phylogenetic diversity gradients. In the present study, we extend an additive partitioning framework proposed for compositional beta diversity to PBD. Specifically, we decomposed the PhyloSor and UniFrac indices into two separate components accounting for ‘true’ phylogenetic turnover and phylogenetic diversity gradients, respectively. We illustrated the relevance of this framework using simple theoretical and archetypal examples, as well as an empirical study based on coral reef fish communities. Overall, our results suggest that using PhyloSor and UniFrac may greatly over-estimate the level of spatial turnover of lineages if the two compared communities show contrasting levels of phylogenetic diversity. We therefore recommend that future studies use the ‘true’ phylogenetic turnover component of these indices when the studied communities encompass a large phylogenetic diversity gradient. | <urn:uuid:f8b82e7a-73e6-466d-928c-8339eb4372af> | 2.515625 | 3,540 | Academic Writing | Science & Tech. | 4.849679 | 95,570,783 |
An incredible photo from the Hubble Space Telescope showcases an enormous galaxy cluster that weighs in at a whopping 3 million billion suns.
Due to its massive size, the galaxy cluster has been nicknamed "El Gordo" (Spanish for "the fat one"). Research suggests the cluster is the largest, hottest and brightest X-ray galaxy cluster ever discovered in the distant universe, NASA officials said in a statement.
Galaxy clusters, groups of galaxies held together by gravity, are the biggest objects in the distant universe. These clusters take billions of years to form, as smaller groups of galaxies slowly move closer to each other, NASA officials said in the statement.
The El Gordo galaxy cluster — officially known as ACT-CL J0102-4915 — is located more than 7 billion light-years from Earth. The cluster was first discovered in 2012 by a trio of telescopes, the European Southern Observatory's Very Large Telescope, NASA's Chandra X-ray Observatory and the Atacama Cosmology Telescope in Chile. These observations showed that El Gordo is actually the product of two galaxy clusters, which are in the process of colliding at a speed of millions of kilometers per hour, according to the statement.
Dark matter and dark energy are believed to heavily influence the formation and evolution of galaxy clusters. Therefore, studying these clusters can help astronomers learn more about the elusive phenomenon, NASA officials said in the statement.
In fact, observations made by Hubble in 2014 showed that most of El Gordo's mass is concealed in the form of dark matter, according to the statement.
"Evidence suggests that El Gordo's 'normal' matter — largely composed of hot gas that is bright in the X-ray wavelength domain — is being torn from the dark matter in the collision," NASA officials said in the statement. "The hot gas is slowing down, while the dark matter is not."
The recent image, released by NASA on Jan. 16, was captured using Hubble's Advanced Camera for Surveys and Wide-Field Camera 3. El Gordo is one of 41 giant galaxy clusters surveyed as part of the Reionization Lensing Cluster Survey (RELICS), which is a joint observing program led by the Hubble and Spitzer space telescopes, according to the NASA statement.
RELICS is designed to search for the brightest distant galaxies in the universe. This data will be used to identify faraway clusters of interest for further study by the James Webb Space Telescope, which is scheduled to launch sometime in the spring of 2019. | <urn:uuid:366d43dc-f8e6-47cf-96bd-9267dfc3bdb3> | 3.515625 | 508 | News Article | Science & Tech. | 39.683423 | 95,570,807 |
Chemicals, disease and other stressors can increase a salmon's chance of being eaten or reduce its ability to catch food. We wrap up our series on the Salish Sea Marine Survival Project with a look at some of the lesser-known, but still significant factors contributing to salmon declines in the Salish Sea.
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Researchers are analyzing the harmful effects of creosote-treated wood pilings on Pacific herring and shellfish in Puget Sound. Studies show that piling removal projects can ease the impacts, but only if carefully done.
Eelgrass (Zostera marina L.) restoration in Puget Sound: development of a site suitability assessment process
The restoration of eelgrass (Zostera marina L.) is a high priority for Puget Sound ecosystem recovery. In 2011, the State of Washington set a restoration target to increase eelgrass abundance by 20% in Puget Sound by 2020. Locating areas to restore eelgrass effectively and efficiently has been challenging for researchers. A 2018 article in the journal Restoration Ecology reports on efforts to identify potential restoration sites using simulation modeling, a geodatabase for spatial screening, and test planting.
A recent influx of anchovies into Puget Sound may have saved some steelhead from predators, but researchers seek more evidence to prove the connection. Our series on the Salish Sea Marine Survival Project continues with a look at these and other potential impacts from predators on the region's salmon and steelhead.
A new study looks at social science and equity integration within the proceedings of the 2018 Salish Sea Ecosystem Conference. The study was produced on behalf of the Puget Sound Partnership for the Encyclopedia of Puget Sound.
During June, near normal air temperatures and continued low precipitation have resulted in highly variable freshwater inputs to Puget Sound. A large Noctiluca bloom extends across the South Central Basin of Puget Sound. Coccolithophores are blooming in Hood Canal. Macroalgae is drifting as mats on the water in Port Madison, South Central Basin, and South Sound. They are also piling up on beaches in South and Central Puget Sound and Whidbey Basin. Juvenile fish are migrating out of the estuaries and meeting a complex thermal habitat. New infrared images tell the story. Meet our ocean acidification expert, Stephen Gonski.
Getting bigger faster can help save juvenile Chinook salmon from a gauntlet of hungry predators ranging from birds and marine mammals to larger fish. We continue our series on the Salish Sea Marine Survival Project with a look at what helps salmon grow and prepare for life in the open ocean.
The 2018 Salish Sea Ecosystem Conference took place April 4-6 at the Washington State Convention Center in Seattle, WA. It featured 588 presentations across 17 topic areas.
An intensive research program in the U.S. and Canada is studying why so few salmon in the Salish Sea are returning home to spawn. They are uncovering a complex web of problems involving predators, prey and other factors that put salmon at risk as they migrate to the ocean. We begin a four-part series on the Salish Sea Marine Survival Project, including new findings presented at the 2018 Salish Sea Ecosystem Conference last spring in Seattle.
Rainfall in May was extremely low: The third lowest amount ever recorded. Rivers are responding differently depending upon whether they received water from rain or snow, which is melting rapidly. With projected drier and warmer conditions, can the remaining snowpack maintain healthy streamflows this summer? Seawater is already getting saltier than normal in response to the lack of rain. We see algal blooms in many colors. What is that orange stuff out there? It’s a Noctiluca bloom and organic material drifting at the surface stretching from South to Central Sound and Whidbey Basin.
Kids around the region are learning about the Salish Sea thanks to a new book that is being offered — in many cases free of cost — to Washington schools and libraries. Explore the Salish Sea by Joe Gaydos and Audrey Benedict inspires the next generation to appreciate and perhaps someday protect the environment close at hand.
A high-profile salmon escape led to a ban on salmon farms in Washington earlier this year. But just across the border, scientists say salmon farms in British Columbia expose migrating fish from Puget Sound to potential maladies like parasites, bacteria and dangerous viruses. They say simply getting rid of salmon farms in Washington does not put the potential impacts to rest.
A report from the Washington State Department of Health outlines results from a series of projects funded by the U.S. Environmental Protection Agency's National Estuary Program in 2011. These projects addressed pathogen pollution in Puget Sound through the management of human and animal waste. Restoring shellfish growing areas, avoiding shellfish closures, and protecting people from disease served as the primary objectives.
The U.S. Environmental Protection Agency awarded a Five-year Puget Sound Tribal Capacity Program grant (Grant #PA-00J27701) to the Skokomish Indian Tribe. The tribe received approximately $1 million over a five-year project period (10/1/2010-9/30/2015). The purpose of the Puget Sound Tribal Capacity Program is to assist Puget Sound tribes in participating in the development and implementation of the Puget Sound Action Agenda.
A report from the Northwest Indian Fisheries Commission describes the results of a series of 97 tribal projects related to Puget Sound recovery funded by the Environmental Protection Agency.
In December 2005, Washington Governor Christine Gregoire outlined an ambitious vision for Puget Sound. She appointed 21 leaders, including representatives from building and timber industries, shellfish growers, agriculture and environmental interests, port authorities, and local, state, federal, and tribal governments to the Puget Sound Partnership. The Partnership was given a 10-month assignment to “develop recommendations for preserving the health and ecosystem of Puget Sound, and to help educate and enlist the public in achieving recovery of the Sound by 2020.” The report was published in December 2006.
Ocean acidification may be twice as extreme in Puget Sound’s seagrass habitats, threatening Dungeness crabs
Ocean acidification could be up to twice as severe in fragile seagrass habitats as it is in the open ocean, according to a study published last April in the Proceedings of the National Academy of Sciences. The conditions may threaten Dungeness crabs by 2050 and will be especially pronounced in the winter, the study says.
Pacific herring exposed to stormwater in Puget Sound show some of the same effects as fish exposed to major oil spills. Symptoms include heart and developmental problems.
New studies show that eelgrass wasting disease is more common in warmer waters, leading to concerns over the future effects of climate change on eelgrass populations in Puget Sound. We continue our series on science findings from the 2018 Salish Sea Ecosystem Conference.
Genetic testing shows that invasive European green crabs in Puget Sound likely did not come from the Sooke Basin in British Columbia as previously thought. New findings on the crab's origins were presented at the 2018 Salish Sea Ecosystem Conference in Seattle.
State agencies tracking pollution levels in Puget Sound have discovered traces of oxycodone in the tissues of native bay mussels (Mytilus trossulus) from Seattle and Bremerton area harbors. The findings were presented at the 2018 Salish Sea Ecosystem Conference in Seattle.
Kelps are large seaweeds in the order Laminariales that form dense canopies in temperate rocky intertidal and subtidal habitats less than 30 m in depth. The kelp flora of the Pacific Northwest is one of the most diverse in the world.
Scientists are trying to learn how to restore Puget Sound’s diminishing kelp forests in an effort to stave off habitat loss for rockfish and other threatened species. We report on new findings presented at the 2018 Salish Sea Ecosystem Conference in Seattle.
By March, regional impacts of large-scale climate patterns normalized, and air temperatures, precipitation, and coastal downwelling were below normal. April brought abundant rain and rivers responded. With La Niña returning to ENSO-neutral conditions, will the favorable snowpack maintain beneficial streamflows through summer? In 2018, water conditions in Puget Sound are mostly expected, except in Hood Canal where conditions only changed recently. Many rivers and field drainage ditches release sediment. A strong red-brown bloom is present in Sinclair Inlet, a bright- brown bloom in Padilla Bay (Joe Leary Slough), and a bright green bloom in Bellingham Bay. It is colorful out there! You might see our team on the water sampling sediments this month.
Bridging the gap between nature and technology might be a challenge for the Puget Sound region, but tech leaders could play an important role in protecting and restoring the ecosystem, according to a panel of experts at last week’s Salish Sea Ecosystem Conference in Seattle.
Gov. Jay Inslee joined former Interior Secretary Sally Jewell to open three days of science talks at the Salish Sea Ecosystem Conference in Seattle. The conference includes about 700 scientific presentations on topics ranging from orcas to habitat restoration, from climate change to toxic chemicals.
Large-scale climate patterns and local weather patterns are returning to more normal conditions. La Niña helped build a favorable snowpack, projected to persist well into spring due to cooler weather. As a consequence, stream flows are largely normal. In Puget Sound, we see again normal water conditions and observe early spring blooms in Central Sound, northern Hood Canal, and Whidbey Basin. Herring are spawning in Admiralty Reach and further north. Salmon Bay in Seattle continues to have frequent oil sheens on the water.
Sediment Quality in Puget Sound: Changes in chemical contaminants and invertebrate communities at 10 sentinel stations, 1989–2015
A 2018 report from the Washington State Department of Ecology presents results from 27 years of sampling sediments and benthic invertebrates at 10 long-term stations throughout the greater Puget Sound area every year from 1989 through 2015.
As the region's population grows, scientists say we can expect to see increasing amounts of nitrogen and other elements flowing into Puget Sound. Known as “nutrients” these elements are naturally occurring and even necessary for life, but officials worry that nutrients from wastewater and other human sources are tipping the balance. That could mean big problems for fish and other marine life, gradually depleting the water of oxygen and altering the food web.
A regional sewage-treatment system in Thurston County has helped contain low-oxygen problems in Budd Inlet as the population continues to grow. The system cleans up some of the effluent for replenishing groundwater supplies.
High amounts of elements such as nitrogen can cause blooms of phytoplankton that sometimes trigger perturbations throughout the food web. This occurs most often in the spring and summer after the long, dark, cloudy days of winter begin to fade. | <urn:uuid:bb06e27e-6110-43dd-bddb-2764249b22e7> | 3.234375 | 2,559 | Content Listing | Science & Tech. | 32.969381 | 95,570,840 |
The application of biotechnology is increasing in areas such as agriculture, biochemistry or biomedicine. Growing bacteria or algae could be beneficial for supplying fuel, drugs, food or oxygen, among other products. An adequate knowledge of biological processes is becoming essential to estimate and control products production. Cyanobacteria are particularly appropriate for producing oxygen and biomass, by consuming mainly carbon dioxide and light irradiation. These capacities could be employed to provide human subsistence in adverse environments, as basic breathing and food needs would be satisfied. Cyanobacteria growing is carried out in bioreactors. As light irradiation is quite relevant for their behavior, photobioreactors are needed. Photobioreactors are designed to supply and control the amounts of elements they need, in order to maximize growth. The adequate design of photobioreactors greatly influences production throughput. This design includes, on the optical side, optical illumination and optical measurement of cyanobacteria growth. The influence of optical scattering is fundamental for maximizing cyanobacteria growing, as long as for adequately measure this growth. In this work, optical scattering in cyanobacteria suspensions is analyzed. Optical properties of cyanobacteria and its relationship with concentration is taken into account. Several types of cyanobacteria are considered. The influence of different beam spatial profiles and irradiances is studied by a Monte Carlo approach. The results would allow the consideration of the influence of optical scattering in the detected optical signal employed for growth monitoring, as a function of cyanobacteria type and optical beam parameters.
F. Fanjul-Vélez and J. L. Arce-Diego, "Light scattering influence in cyanobacteria suspensions inside a photobioreactor," Proc. SPIE 10492, Optical Interactions with Tissue and Cells XXIX, 104920K (Presented at SPIE BiOS: January 30, 2018; Published: 13 February 2018); https://doi.org/10.1117/12.2290173.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the conference proceedings. They include the speaker's narration along with a video recording of the presentation slides and animations. Many conference presentations also include full-text papers. Search and browse our growing collection of more than 12,000 conference presentations, including many plenary and keynote presentations. | <urn:uuid:31c2f35b-0641-468f-8579-7b0769fb1640> | 2.78125 | 479 | Academic Writing | Science & Tech. | 19.408392 | 95,570,890 |
What will space travelers drink?
What will space tourists drink? If we need to consumerize the space industry to ultimately mine asteroids, and if we need to mine asteroids in order to expand our growth — not just on Earth but through further exploration — what will we drink on the way there?
From the abstract in Nature: “Regardless of the specific composition or formation mechanism, we conclude that OH/H2O can be present on the Moon under thermal conditions more wide-ranging than previously recognized.”
On Second Thought, the Moon’s Water May Be Widespread and Immobile
The findings could help researchers understand the origin of the Moon’s water and how easy it would be to use as a resource. If the Moon has enough water, and if it’s reasonably convenient to access, future explorers might be able to use it as drinking water or to convert it into hydrogen and oxygen for rocket fuel or oxygen to breathe.
Sorting out what happens on the Moon could also help researchers understand the sources of water and its long-term storage on other rocky bodies throughout the solar system.
The researchers are still discussing what the findings tell them about the source of the Moon’s water. The results point toward OH and/or H2O being created by the solar wind hitting the lunar surface, though the team didn’t rule out that OH and/or H2O could come from the Moon itself, slowly released from deep inside minerals where it has been locked since the Moon was formed. | <urn:uuid:405640ac-b95a-4ab9-9daa-d6c81fa0f632> | 3.03125 | 313 | Personal Blog | Science & Tech. | 45.33598 | 95,570,916 |
1. A home builder installs electric baseboard heat and claims, "It is the cheapest and cleanest way to go." Apply your understanding of the second law of thermodynamics and net energy efficiency chain to evaluate this claim.
2. Someone tells you we can save energy by recycling it. How should you respond?
3. Should government tax breaks and other subsidies for fossil fuels and nuclear power be phased out and replaced with subsidies and tax breaks for improving energy efficiency and renewable energy alternatives. Explain© BrainMass Inc. brainmass.com July 16, 2018, 3:11 am ad1c9bdddf
also attached as live HTML with reference links:
1. Cheapest ... maybe. But only because many electric utilities often give a better rate if you're all electric. On a head-to-head comparison most would disagree and give gas the clear win for heat. See: http://www.allthingsfrugal.com/f.h_options.htm Although they are 2005 numbers
Cleanest .... it depends on what the electric utility is using to generate that electricity. However, as the US electric load is about 50% coal-fired, that is unlikely. Natural gas however, is mainly methane which burns relatively clean.
Addressing it from a ...
Answer ponders thermodynamic efficiency and policy implications of renewable energy in new construction | <urn:uuid:511cfff6-d71f-4e78-b524-05c34b474c79> | 2.796875 | 278 | Q&A Forum | Science & Tech. | 55.635254 | 95,570,929 |
Ada 95: The Craft of Object-Oriented Programming
by John English
Publisher: Prentice Hall 2001
Number of pages: 486
This book is a beginner’s introduction to Ada 95. It uses an example-driven approach that gradually develops small programs into large case-study type programs. The focus of this book is on using object-oriented approaches to write maintainable, extensive programs. Important and unique ADA features such as exception handling, user-defined types, procedures, functions, and packages are covered early in the text.
Home page url
Download or read it online for free here:
by Richard Riehle - AdaWorks
An introduction for experienced programmers new to Ada. The text highlights some key features of the language, with coded examples. It emphasizes syntax, control structures, subprogram rules, and how-to coding issues rather than design issues.
by Michael A. Smith
The text for students and programmers who wish to learn the object-oriented language Ada 95. It covers the basic constructs in the Ada 95, the object-oriented features of the language, and an introduction to the tasking features of Ada.
by Simon Johnston - Ada Home
This tutorial for C/C++ programmers shows them what Ada can provide and how to set about turning the experience they have gained in C/C++ into good Ada programming. It covers the Ada types, language constructs, Object Oriented programming, etc.
by Ken O. Burtch - PegaSoft
This text covers basic software development on Linux, a review of the core Ada 95 language, and an introduction to designing programs that work with the Linux kernel and standard C libraries. It also covers some of the Ada bindings. | <urn:uuid:146cfbad-cc50-4061-bdaf-69ec029bf6cf> | 2.765625 | 354 | Content Listing | Software Dev. | 42.710617 | 95,570,972 |