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What determines if you are confident in your decisions? In the perceptual domain, the standard answer to this question is usually “signal strength.” The idea is that we are more confident for larger, brighter, less noisy stimuli. Beyond that, however, our previous decisions also have an impact: after making a decision with high confidence, we are more likely to be very confident again. This is an example of the ubiquitous sequential effect that turns up everywhere in perception.
But what if your previous decision was for a different task altogether? Does your confidence on a completely different task still influence you when you are deciding on your current task?
Our design was simple: present 40 letters (Xs and Os) in different colors (red or blue), and then ask participants to judge whether there are more Xs or Os, and whether there are more blue or red letters. Even though the processing of letter form and color tend to be separated in the visual system, we find that, on a trial-by-trial basis, confidence on one task predicts the confidence on the other.
A number of analyses and control experiments confirmed that the effect is not due to trivial reasons such as motor priming, attentional fluctuations, or confidence drifts. What really convinced us, though, was our causal manipulation. We increased the difficulty of one of the tasks, so that confidence decreased. Lo and behold, we found a corresponding decrease in the confidence in the other task. In other words, the lowered confidence in the first task leaked into the second task.
Why does confidence leak happen? We think that people believe that the environment is consistent (autocorrelated) and thus an easy trial ought to be followed by another easy trial, even if the tasks are different. We constructed a Bayesian model that demonstrates how this assumption would naturally produce the observed confidence leak.
Who are the people that show more of this (suboptimal) confidence leak? In a separate experiment, we found that people with lower gray matter volume in the anterior prefrontal cortex (aPFC) exhibited higher confidence leak and so did people with lower metacognitive sensitivity.
It is interesting to consider the limits of the phenomenon. Would confidence leak appear for tasks that involve different modalities (e.g., vision and audition)? Would it happen for memory or general knowledge tasks? If our model is correct, as long as people are willing to assume that the difficulty of different tasks is correlated in the natural environment, confidence leak would invariably follow. | <urn:uuid:2e0d7eb5-c350-44c9-8517-da19bf5ded8c> | 2.859375 | 508 | Academic Writing | Science & Tech. | 38.913 | 95,511,173 |
(University of Miami Rosenstiel School of Marine & Atmospheric Science) Scientists have confirmed for the first time that radical changes of one volcano in southern Japan was the direct result of an erupting volcano 22 kilometers (13.7 miles) away. The observations from the two volcanos -- Aira caldera and Kirishima -- show that the two were connected through a common subterranean magma source in the months leading up to the 2011 eruption of Kirishima.
(University of Hawaii at Manoa) In a paper published this week in the journal Science, scientists have, for the first time, provided evidence for a known blazar, designated TXS 0506+056, as a source of high-energy neutrinos. At 8:54 p.m. on Sept. 22, 2017, the National Science Foundation-supported IceCube neutrino observatory at the South Pole detected a high energy neutrino from a direction near the constellation Orion. Just 44 seconds later an alert went out to the entire astronomical community.
(British Ecological Society) A large-scale study published by researchers from Royal Holloway University of London has drawn together the findings of a decade of agrochemical research to confirm that pesticides used in crop protection have a significant negative impact on the learning and memory abilities of bees.
(University of Houston) Antibiotic resistance is one of the world's most serious threats to public health, forcing the use of medications that are more toxic, more expensive and not always effective. Engineers at the University of Houston are studying whether the use of tiny amounts of antibiotics embedded in corn-based nanoparticles could help both animals and people avoid the problem.
(University of Texas at El Paso) Across the US Southwest, severe drought and land?use change are projected to increase in the future, contributing to more frequent and intense dust storms and eventually dry dust fallout and dust washout from the atmosphere with rain. How will Dust Bowl?like conditions affect raining dust events? We examined rainwater samples at two Texas sites (one arid, Guadalupe Mountains; one humid, Gulf coastal prairie) during 2012, a year of extreme drought and dust in Texas.
The idea of a perfect office temperature is something of a red herring. Ultimately, people just want to have a level of control over their environments-- Read more on ScientificAmerican.com | <urn:uuid:068a6405-4c43-417c-a944-cc39baa3f935> | 2.8125 | 484 | Content Listing | Science & Tech. | 31.00478 | 95,511,174 |
The detection and recording of atmospheric scattering data has received a tremendous amount of attention since the development of the laser. The work of such men as Myron Ligda and Ron Collis at the Stanford Research Institute and Georgio Fiocco at MIT has shown that the laser radar (or LIDAR) is a valuable tool for obtaining backscatter information on atmospheric phenomena. The General Electric Company has been actively engaged in laser measurements of the atmosphere since 1964. (Ref..1,2) A number of laser equipments were con-structed and used to obtain atmospheric data at various places in the country. Recently a large laser system was built for use in measuring Rayleigh and Raman scattering in two colors from the atmosphere by the Space Sciences Laboratory of the General, Electric Company in King of Prussia, Penn sylvania. The two color capabilities of the of the system are used to obtain data on the differences between Rayleigh and Mie scat tering which exhibit diffijirent scattering func tion at different wavelength.
Howard W. Halsey,
"Large Laser Radar For Atmospheric Probing", Proc. SPIE 0027, Remote Sensing of Earth Resources and the Environment, (1 May 1972); doi: 10.1117/12.978122; https://doi.org/10.1117/12.978122 | <urn:uuid:a2a239a1-0600-472e-802c-f0ab980c63da> | 3.4375 | 275 | Academic Writing | Science & Tech. | 49.128059 | 95,511,180 |
C programming language was invented by Dennis Ritchie in 1972 to put into action UNIX operating procedure. It truly is an ANSI/ISO typical normal reason, very important language that supports structured programming.
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C was designed at AT&T Bell Labs by Dennis Ritchie inside the early 1970's. It had been used to carry out Unix about the PDP-11. Dennis Ritchie and Brian Kernigan wrote the definitive book on C, which is recognized as K&R C. There have already been lots of improvements to C since it was first formulated, with prototypes in headers getting one of several much more clear kinds. C++ was an extension to the language made by Bjarne Stroustrup, it had been at first a preprocessor to C referred to as cfront that took in C++ code and output C code which was compiled utilizing the typical compiler.
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Dennis Ritchie, within the early 1970’s, developed C++ at AT&T Bell Labs. It absolutely was accustomed to execute UNIX about the PDP eleven. Brian Kernigan and Dennis Ritchie wrote the authoritative ebook on C++, which is recognized as K&R this article C++. There are actually plenty of developments in C with prototypes in headers staying one of several a lot more recognizable ones.
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The C family of programming languages is matched only by Java of their charm. In 2014, the C household (for instance C, C++ and C#) has a mixed current market share of 27.
An enormous variety of operator remembers and software are needed when making use of C++ based upon the complexity in the undertaking. At geeksprogramming, you work is in extremely capable hands.
C++ has a little difference when compared with C. C++ aid compilers for compilation of console programs. The general programming language generally focuses on the design in addition to kind-considerable, abstraction of lightweight. It tells the preprocessor to incorporate iostream with the conventional file. When the file unique termed as iostream has the statements of standard output-input sign libraries in C++. The libraries of C++ declared the namespace named with the library and STD which contains Along with the string that is through the traditional sort of string form.
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Perl’s roots in text processing have not been overlooked through the years. Individuals libraries, gathered while in the CPAN, offer you Prepared-made solutions to a remarkable range of difficulties.
hey frnds..! i wanna discover “C socket programming” am a starter so suggest some Web sites for me..!
The first line is easy, delay the activity for your presented variety, or portion of, seconds. This method requires a parameter of form Duration specified
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File.52: Prefer capturing by reference in lambdas that should be utilised regionally, such as passed to algorithms
offer Instance is type A is non-public; B : continuous A; personal variety A is new Integer; B : continual A := 0;
What on earth is expressed in code has outlined semantics and may (in basic principle) be checked by compilers and various resources.
entity which may be compiled By itself and so have to involve specs from other offers to take action. An Ada package human body at compile time will have to seek advice from its
We all know limitations of recent education method. Professors normally call for high-quality unique Inventive students performs for all subjects in the same time. They don’t listen to Specific situation and complications, which in some cases appears.
Discussion – references to far go to this web-site more in depth rationale and/or illustrations put exterior the key lists of policies
1 consequence of that may be that some policies is usually supported only by heuristics, as opposed to specific and mechanically verifiable checks.
If a thing (like Netlab) requirements a function named fcnchk, produce a file named fcnchk.m find more info Along with the contents demonstrated down below and put it exactly where Octave can discover it:
After the sockets are related, the server sends the info (day+time) on purchasers socket by way of consumers socket descriptor and consumer can study it by way of usual browse get in touch with about the its socket descriptor.
All programmers must know something about standard data buildings like stacks, queues and heaps. Graphs certainly are a immensely beneficial strategy, and two-three trees remedy loads of troubles inherent in additional essential binary trees.
Ada as well as newer verions of C++ assist exception dealing with for essential faults. Exception managing is made of a few components, the exception, raising
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Examine textual content from the file, normalizing whitespace and stripping HTML markup. We've got observed that functions help for making our perform reusable and readable. They
Considering that the compound assignment operators also return the value just after mutation, the next are equal for primitive styles:
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Should you don’t understand how to open up a command window on Home windows or maybe the Terminal on OS X and use it to run your applications, this lesson clarifies all.
You can regularly have to have to make comparisons involving one value and Various other worth. C has quite a few ‘relational operators’ to help you do this.
plus the Ada circumstance statement, this also extends to the fact that the when statement can capture several exceptions. Ranges of exceptions are not possible,
On this program I'll generally utilize the cost-free CodeLite C editor that my latest blog post is accessible for OS X, Home windows and Linux. This video demonstrates how to get CodeLite mounted in your computer.
for improvements and fixing bugs and spelling faults I have released. I'll try and continue to keep this part current on what should be accomplished and what I
The subject of pointers/references/obtain varieties is the most difficult, each language has its individual set of principles and tips. In C/C++ the thing you need to
but Let's say the array is by now initialized And that i desire to entirely substitute the values of The weather in that array in a single line
One of the most important items to halt C/C++ programmers within their tracks is that Ada is scenario insensitive, so commence Start out Commence are all the same.
A block incorporates a sequence check my source of statements. Blocks for functionality bodies in functionality definitions; to define the branches of if statements plus the bodies of whilst loops.
operator, plus the caller will end up with a const reference into a Fred. This enables the caller to examine the Fred
In the event the disorders fulfill then the when loop goes on performing its work in Every iteration ,even so if any situation fails then the consumer aspect method finishes but at server aspect it demonstrates an infinte loop functioning with none exit.
dismissed. Process Illustration of varieties thirteen . As you might count on with Ada's history in embedded and systems programming there are ways in which you'll be able to power a type into specific technique
Create class and sequence diagrams for your First code.Perform the refactorings under. Build class and sequence diagrams for the refactored code.Make observations around the variations, like any improvements, amongst the construction just before and soon after.
It will probably be important to pass thenumber of times rented. getCharge() and getFrequentRenterPoints() the two have things that may possibly differ with
If some thing is actually a very well-specified motion, independent it out from its bordering code and provides it a name.
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The keyword others sets any factors not explicitly dealt with. Slicing Array slicing is one area commonly accomplished with memcpy in C/C++. Have a
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These two generic packages give IO amenities for data files which include similar information. They are often instantiated in the same solution to the generic
Hi,Thanks for helps and excellent article content. Are you able to suggest a good ebook for complete socket programming??
Prefer copy semantics unless you are developing a “smart pointer”. Price semantics is The only to cause about and exactly what the conventional-library facilities count on.
I'm attempting to make a customer server plan . The server and Customer in my situation doesnt rest in the same process They can be check my source present in a dispersed LAN network. Now I would like to create a Server that has a worldwide IP Address ( I suppose it to be the IP address on the procedure through which it can be jogging).
You should Be at liberty to comment on problems, stuff you do not like and matters you want to find out. If I do not obtain the opinions then I can not take it forward,
At the very best of the decision tree where you receive the raw pointer Visit Your URL or reference from a wise pointer that retains the article alive.
C programming language is Just about the most extensive languages of all instances. C programming language is amongst the extensively utilized programming languages of all situations.
A huge amount of operator recalls and application are demanded when applying C++ relying on the complexity in the undertaking. At geeksprogramming, you're employed is in particularly capable arms.
C++ is as near as is possible to compatible with C, but no nearer. In follow, the main change is C++
C++ wasn’t intended to reveal what a perfect language seems like. It was meant to certainly be a sensible Software for
Right after-Gross sales: BA have initiated their loyalty club playing cards to clients. BA maintain interaction with their buyers by means of a range of channels for instance e-mails with advertising and marketing promotions and responses questionnaires. And, offering a misplaced baggage Service.
file along with the source code that wonderful-fantastic-grandpa wrote was shed twenty five a long time in the past, that ancient object file will simply call the
Industry Enhancement: Sector advancement focuses on acquiring The brand new market place of shoppers in new phase. British Airways is attempting their very best to receive back the small business class customers from their competitor Virgin Atlantic airline (see appendix 4).
one forty hour do the job 7 days. But in spite of in which you Obtain your education, make certain the courses Use a palms-on aspect,
Given that Portion six is currently being described on this line, this is an initialization, not an assignment. Initializations use constructors, whereas assignment utilizes operator=. It truly is a little deceptive, because you may well presume the = pretty much means get in touch with operator=, but in this context, = is simply Component of the syntax for initialization, not an true operator get in touch with. I suppose It is much better than having to use a distinct image for initialization and assignment!
Prior to deciding to start out this lesson, you should remember two math phrases: similar figures and ratio. Two geometric figures are related if their corresponding angles are equal as well as their corresponding sides are proportional. A ratio is actually a portion which compares two quantities. This photograph exhibits two equivalent four-sided figures.
Take note that BOBYQA only operates on capabilities of two or more variables. So if you should carry out derivative-free optimization with a operate of one variable then you must use the find_max_single_variable functionality.
C++ and its apps are frequently growing and evolving. And this is why Geeks Programming is on its toes, to remain up-to-date also to serve all of its shoppers in one of the simplest ways possible.
If your graph is tree-structured then this routine constantly provides the exact Remedy for the MAP dilemma.
You should Notice that item-oriented programming is not really a panacea. “OOP” would not just indicate “superior” – if there are no inherent hierarchical relationships amid the fundamental ideas in your trouble then no quantity of hierarchy and Digital functions will improve your code. The strength of OOP is there are several challenges that may be usefully expressed making use of course hierarchies – the most crucial from this source weak point of OOP is usually that as well Many of us endeavor to force a lot of helpful hints problems into a hierarchical mould. | <urn:uuid:3a1f2065-b13a-4f53-a160-fe7e460e63d4> | 2.984375 | 3,033 | Spam / Ads | Software Dev. | 42.994753 | 95,511,184 |
Our most popular show for older children and adults! Witness some truly ‘cool’ and sometimes explosive experiments using an incredibly cold substance – liquid nitrogen. Discover what really happens when liquids boil, learn about frost bite and find out why the Sydney Harbour Bridge shrinks on a cold day. Science concepts include thermal contraction/expansion, boiling points, pressure, temperature, the effects of freezing, cryogenics and changes of state.
Showing 2pm and 3pm weekdays these July school holidays | <urn:uuid:87e46edb-d2d0-4c3a-a0b4-a30540211cd2> | 2.609375 | 101 | Product Page | Science & Tech. | 33.934211 | 95,511,186 |
This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of NAD status.
Section: 23.5.5 [alg.find] Status: NAD Submitter: Pablo Halpern Opened: 2000-03-06 Last modified: 2016-12-23
Priority: Not Prioritized
View all other issues in [alg.find].
View all issues with NAD status.
The find function always searches for a value using operator== to compare the value argument to each element in the input iterator range. This is inconsistent with other find-related functions such as find_end and find_first_of, which allow the caller to specify a binary predicate object to be used for determining equality. The fact that this can be accomplished using a combination of find_if and bind_1st or bind_2nd does not negate the desirability of a consistent, simple, alternative interface to find.
[ Summit: ]
Reopened by Alisdair.
[ 2009-07 Frankfurt ]
The same thing can be achieved using find_if (as noted in the issue).
Moved to NAD.
In section 23.5.5 [alg.find], add a second prototype for find (between the existing prototype and the prototype for find_if), as follows:template<class InputIterator, class T, class BinaryPredicate> InputIterator find(InputIterator first, InputIterator last, const T& value, BinaryPredicate bin_pred);
Change the description of the return from:
Returns: The first iterator i in the range [first, last) for which the following corresponding conditions hold: *i == value, pred(*i) != false. Returns last if no such iterator is found.
Returns: The first iterator i in the range [first, last) for which the following corresponding condition holds: *i == value, bin_pred(*i,value) != false, pred(*) != false. Return last if no such iterator is found.
This is request for a pure extension, so it is not a defect in the current standard. As the submitter pointed out, "this can be accomplished using a combination of find_if and bind_1st or bind_2nd". | <urn:uuid:068b5319-fad4-4c5b-b17f-ce8fbb2b57a9> | 2.53125 | 473 | News (Org.) | Software Dev. | 51.269723 | 95,511,192 |
A newly discovered small molecule called IQ-1 plays a key role in preventing embryonic stem cells from differentiating into one or more specific cell types, allowing them to instead continue growing and dividing indefinitely, according to research performed by a team of scientists who have recently joined the stem-cell research efforts at the Keck School of Medicine of the University of Southern California. Their findings are being published today in an early online edition of the Proceedings of the National Academy of Sciences.
This discovery takes scientists another step closer to being able to grow embryonic stem cells without the “feeder layer” of mouse fibroblast cells that is essential for maintaining the pluripotency of embryonic stem cells, says the study’s primary investigator, Michael Kahn, Ph.D., who was recently named the first Provost’s Professor of Medicine and Pharmacy at USC. Such a layer is needed because it is currently the only proven method to provide the stem cells with the necessary chemical signals that prompt them to stay undifferentiated and to continue dividing over and over.
Still, growing human embryonic stem cells on a layer of mouse fibroblasts has never made much sense to the scientists forced to do just that. “Stem cells that grow on feeders are contaminated with mouse glycoproteins markers,” Kahn says. “If you use them into humans, you’d potentially have a horrible immune response.”
And so, in order to take any eventual stem cell-based treatments from the laboratory to the clinic, there needs to be a way to keep the cells growing and dividing without the use of mouse fibroblasts. The discovery of IQ-1, says Kahn, is a significant step in that direction.
What IQ-1 does, Kahn explains, is to block one arm of a cell-signaling pathway called the Wnt pathway, while enhancing the signal coming from the other arm of the Wnt pathway. The Wnt pathway is known to have dichotomous effects on stem cells i.e. both proliferative and differentiative. More specifically, IQ-1 blocks the coactivator p300 from interacting with the protein ß-catenin; this prevents the stem cells from being ‘told’ to differentiate into a more specific cell type. At the same time, IQ-1 enhances the interaction between the coactivator CBP and ß-catenin, which signals the cells to keep dividing and to remain as fully potent stem cells. “This way, you can essentially maintain the stem cell’s growth and potency for as long as you want,” Kahn says. The studies of IQ-1 and its effects reported in the newly published PNAS paper were performed at the University of Washington in Seattle by Kahn and his colleagues (along with collaborators from the Asahi Kasei Corporation in Shizuoka, Japan) using mouse embryonic stem cells, but Kahn notes that subsequent pilot studies using human embryonic stem cells, in collaboration with Dr. Qilong Ying at the Center for Stem Cell and Regenerative Medicine at the Keck School of Medicine, have confirmed that IQ-1 plays a similar role in that system as well.
“If we can create a totally chemically defined system for growing human embryonic stem cells without any risk of contamination, it would make life much easier for scientists than it is at the moment,” says Kahn. “And that’s our goal.” "Kahn's study provides us with striking new insights into the molecular regulatory machinery inside embryonic stem cells,” adds Martin Pera, Ph.D., director of the Center for Stem Cell and Regenerative Medicine at the Keck School of Medicine. “His team has identified a chemical that controls a critical switch that enables stem cells to multiply indefinitely in the laboratory. These findings will help lead to the development of new techniques to propagate pure populations of embryonic stem cells on a large scale, an essential prerequisite to the successful development of stem cell based therapies."
Jennifer Chan | 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...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Power and Electrical Engineering
17.07.2018 | Life Sciences
16.07.2018 | Physics and Astronomy | <urn:uuid:86732324-deb6-4d2b-b459-84552ece8a77> | 3.1875 | 1,498 | Content Listing | Science & Tech. | 42.688729 | 95,511,196 |
Given the concentration of a weak acid, calculate the pH of the solution. The Ka for acetic acid, CH3COOH, is 1.8x10^-5. Calculate the [H+] of a 0.20 M solution of acetic acid in water.© BrainMass Inc. brainmass.com July 19, 2018, 6:00 am ad1c9bdddf
CALCULATING THE pH OF A WEAK ACID
For acetic acid, CH3COOH, the Ka value is 1.8x10^-5. Calculate the concentration of H+ in a 0.20 M solution.
We were told that the initial concentration of CH3COOH was 0.20 M. Since no initial concentration values were given for H+ and CH3COO-, we assume that none was present. Therefore, we show this by placing a zero in the corresponding cells of the table below.
CH3COOH H+ CH3COO-
Initial Concentration 0.20 M 0 0
Change in Concentration
Since we began without any concentration of H+ and CH3COO-, we know that as CH3COOH ionizes, it will produce some of both of these chemical species. Since we do not know how much of these ...
In this solution I show you step by step (with a total of 6 steps), working out every step in detail, how to calculate the pH of this solution. We start off by filling out a table outlining initial concentrations, changes in concentrations, and final concentrations. Then, we develop a mathematical equation based on these values and the equilibrium expression. Finally, we utilize the quadratic formula to solve the expression and relate that solution to the concentration of H+ that we are looking for. | <urn:uuid:1ea4b6d8-084d-4c85-89dc-c6a34f22f48a> | 3.234375 | 375 | Tutorial | Science & Tech. | 68.652978 | 95,511,219 |
Widespread volcanic activity, cyanobacteria and global glaciation may sound like the plot of a new, blockbuster disaster movie, but in reality, they are all events in the mystery surrounding the development of our oxygen-rich atmosphere, according to a Penn State geoscientist.
The most extreme fluctuation in the Earths carbon cycle occurred about 2.2 billion years ago, according to Dr. Lee R. Kump, professor of geosciences and member of the Penn State Astrobiology Research Center, and the conventional explanation is that it marks the debut of our oxygen atmosphere. Recently, however, better geological dating and a better proxy measure of when oxygen occurred in the atmosphere suggest that the oxygen atmosphere appeared long before this supposedly seminal event. "The new dating and proxy clearly show that the rise of oxygen preceded its apparent cause by at least 100 million years," Kump told attendees at the Geological Society of America conference Nov. 8 in Denver.
The proxy measure of when significant oxygen appeared in the atmosphere is sulfur. In an oxygen atmosphere, which is very oxidizing, all sulfur eventually becomes sulfate, but in a reducing atmosphere – one without significant oxygen – sulfur deposits as sulfate, sulfite or even pure sulfur and retains an unusual isotopic signature of upper atmospheric processes. Better dating of these strange isotopes in rocks found them to be 2.3 billion years old or older and does suggest that oxygen appeared earlier than the carbon cycle perturbation.
Andrea Elyse Messer | EurekAlert!
In the ocean's twilight zone, tiny organisms may have giant effect on Earth's carbon cycle
19.07.2018 | Florida State University
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
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
19.07.2018 | Social Sciences
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The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of Fiona's cold cloud tops on August 31 at 1:05 p.m. EDT and showed two major areas of strong convection (rapidly rising air that forms the thunderstorms that power a tropical cyclone) north and south of the center of circulation. Some of the cloud tops were are cold as -63 degrees Fahrenheit.
Fiona is intensifying as it approaches the Northern Leeward Islands today, so there are watches and warnings in place. A Tropical Storm Warning is in effect for St. Martin and St. Barthelemy. A Tropical Storm Watch is in effect for Antigua, Barbuda, Montserrat, St. Kitts, Nevis, and Anguilla and St. Maarten, Saba, and St. Eustatius.
At 8 a.m. EDT on September 1, Fiona's maximum sustained winds were near 60 mph. It was about 70 miles northeast of Barbuda, near 18.2 North and 60.9 West. It was moving west-northwest near 15 mph with a minimum central pressure of 998 millibars.
The National Hurricane Center noted that tropical storm conditions could spread over portions of the Northern Leeward Islands later this morning and afternoon, and rainfall accumulations of 1 to 3 inches with isolated maximum amounts of 5 inches can be expected over portions of the Northern Leeward Islands.
Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.
Rob Gutro | 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
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:7a6f45ed-6f22-422f-8a7a-1deb616e4fcf> | 3.09375 | 902 | Content Listing | Science & Tech. | 47.996948 | 95,511,262 |
|A genetic marker is a gene or DNA sequence with a renowned position on a chromosome that can be utilised to recognise individuals or species. It can be described as a variety (which may originate due to mutation or alteration in the genomic loci) that can be discerned. A genetic marker may be a short DNA sequence, such as a sequence surrounding a lone base-pair change (lone nucleotide polymorphism, SNP) or a long one, like minisatellites.Genetic markers can be used to study the connection between an inherited disease and its genetic causes (for demonstration, a specific mutation of a gene that outcomes in a defective protein). It is known that parts of DNA that lie near each other on a chromosome are inclined to be inherited together. Genetic markers are engaged in genealogical DNA checking for genetic genealogy to determine genetic distance between persons or populations. Uniparental markers (on mitochondrial or Y chromosomal DNA) are revised for considering maternal or paternal lineages. Autosomal markers are utilised for all ancestry.Genetic markers have to be easily identifiable, affiliated with a specific locus and highly polymorphic because homozygotes do not supply any information. Detection of the marker can be directed by RNA sequencing, or indirect utilising allozymes. | <urn:uuid:7f94011f-8bab-4ace-aba3-d815bdce5950> | 3.90625 | 261 | Knowledge Article | Science & Tech. | 13.354935 | 95,511,297 |
|sequencing is figuring out the order of nucleotides, or bases, in a genome. News basically means any information regarding a particular thing. So there are many topics that can create news. They can be of different types for example, DNA news, RNA news, sequencing news, protein news, etc. these news can include information such as what is that topic about, the basic technology involved and the uses. So the news which includes information about sequencing is known as sequencing news. High-impact journals are those considered to be highly influential in their respective fields.
The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years. | <urn:uuid:e2ab9db4-eca4-4a86-95f1-32a99dceb191> | 3.28125 | 226 | Knowledge Article | Science & Tech. | 35.346613 | 95,511,298 |
Primates often react to possible predators by using intimidation displays, although the occurrence of these displays is dependent on the risk of predation. Functional explanations for these kinds of displays range from sexual selection to predator deterrence. The ability to respond to different predators can be socially acquired, and social traditions could explain population differences in response to the same potential predator.
In this study, wild groups of Cebus apella libidinosus are reported to bang stones to produce sound in a remarkable aggressive display. Six wild groups were observed, suggesting the primary function is a predator-deterrent behaviour. Although banging objects is an innate behaviour in capuchin monkeys, in all wild groups observed so far it has been observed only in a foraging context. Stone banging is a novel behavioural variant that is most likely learned socially. The absence of this display in other populations of capuchins, which have access to stones, suggests that stone banging could be a social tradition in the population studied.
Carla Holmes | alfa
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung
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 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:206947fa-2c7e-43b2-8138-6a4170ac014e> | 3.546875 | 846 | Content Listing | Science & Tech. | 35.817877 | 95,511,308 |
3D model (JSmol)
|Molar mass||87.08 g/mol|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Dehydroalanine (Cα,β-didehydroalanine, (alpha)-(beta)-di-dehydroalanine, or 2,3-didehydroalanine) is a dehydroamino acid. It is a hypothetic molecule that does not exist except as a residue found as a residue in peptides of microbial origin. It is unusual in having an unsaturated backbone.
Structure and reactivity
As a primary enamine, dehydroalanine is unstable with respect to tautomerization. It therefore does not exist in large amounts or as a stable pure substance. However, N-acylated derivatives, such as peptides and related compounds, are stable.
Despite its name, dehydroalanine is not derived biochemically from alanine. Instead, it arises via a post translational modification of serine or cysteine. These amino acids, as residues in peptide chains, undergo enzyme-mediated loss of water and hydrogen sulfide, respectively.
Most amino acid residues are unreactive toward nucleophiles, but those containing dehydroalanine or some other dehydroamino acids are exceptions. These are electrophilic due to the α,β-unsaturated carbonyl, and can, for example, alkylate other amino acids. This activity has made DHA useful synthetically to prepare lanthionine.
DHA can be formed from cysteine or serine by simple base catalysis without the need for an enzyme, which can happen during cooking and alkaline food preparation processes. It can then alkylate other amino acid residues, such as lysine, forming lysinoalanine cross-links and racemization of the original alanine. The resulting proteins are have lower nutritional quality for some species but higher nutritional quality for others. Some lysinoalanines may also cause kidney enlargement in rats.
Many dehydroalanine-containing peptides are toxic.
A dehydroalanine residue was long thought to be an important electrophilic catalytic residue in histidine ammonia-lyase and phenylalanine ammonia-lyase enzymes, but the active residue was later found instead to be a different unsaturated alanine derivative—3,5-dihydro-5-methyldiene-4H-imidazol-4-one—that is even more electrophilic.
- Siodłak, Dawid (2015). "α,β-Dehydroamino Acids in Naturally Occurring Peptides". Amino Acids. 47: 1–17. doi:10.1007/s00726-014-1846-4. PMC .
- Friedman, Mendel (1999). "Lysinoalanine in food and in antimicrobial proteins". In Jackson, Lauren S.; Knize, Mark G.; Morgan, Jeffrey N. Impact of Processing on Food Safety. 459. Springer. pp. 145–159. doi:10.1007/978-1-4615-4853-9_10. ISBN 978-1-4615-4853-9. PMID 10335374.
- Rétey, János (2003). "Discovery and role of methylidene imidazolone, a highly electrophilic prosthetic group". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 1647 (1–2): 179–184. doi:10.1016/S1570-9639(03)00091-8.
- Calabrese JC, Jordan DB, Boodhoo A, Sariaslani S, Vannelli T (September 2004). "Crystal structure of phenylalanine ammonia lyase: multiple helix dipoles implicated in catalysis". Biochemistry. 43 (36): 11403–16. doi:10.1021/bi049053+. PMID 15350127. | <urn:uuid:e104b795-980d-4033-bbdb-15d0b40b8851> | 2.859375 | 896 | Knowledge Article | Science & Tech. | 36.990672 | 95,511,319 |
The study found that inefficiency in the use of fossil fuels increased levels of CO2 by 17 percent, while the other 18 percent came from the decline in the efficiency of natural land and ocean sinks which soak up CO2 from the atmosphere.
The research by the Global Carbon Project, the University of East Anglia (UEA) and the British Antarctic Survey (BAS) shows that improvements in the carbon intensity of the global economy have stalled since 2000 after improving for 30 years, leading to the unexpected growth of atmospheric CO2.
The study also states that global CO2 emissions were up to 9.9 billion tons of carbon in 2006, 35 percent above emissions in 1990 (used as a reference year in the Kyoto Protocol).
Author Dr Corinne Le Quéré of the University of East Anglia and British Antarctic Survey says, “The decline in global sink efficiency suggests that stabilisation of atmospheric CO2 is even more difficult to achieve than previously thought. We found that nearly half of the decline in the efficiency of the ocean CO2 sink is due to the intensification of the winds in the Southern Ocean”.
The study’s lead author, Dr Pep Canadell, executive director of the Global Carbon Project, said: “In addition to the growth of global population and wealth, we now know that significant contributions to the growth of atmospheric CO2 arise from the slow-down of natural sinks and the halt to improvements in the carbon intensity of wealth production.”
Athena Dinar | 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.
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:b7804fc2-fa43-4060-a240-3a23f9a1e2e7> | 3.5 | 972 | Content Listing | Science & Tech. | 41.960303 | 95,511,323 |
Watch This Incredible, Year-Long Time-Lapse Video of the Earth and Also Learn Some Science
No matter how many people on the Internet would like to convince you otherwise, the Earth is a giant ball spinning through space at very high speeds, which makes it particularly difficult to photograph. NASA is up to the challenge, though, and this amazing time-lapse video shows a static view of the Earth from space (which will probably spawn some conspiracy theories in itself) over the course of a year and just might teach you a little science.
The video comes from the NOAA’s DSCOVR satellite, which sits about one million miles away from our home here on the ground at Lagrange point 1, a sort of gravitational balance point between the Earth and the Sun. That allows it to follow along with the Earth in its yearly orbit with a clear view of the planet in order to (from the video’s description) “monitor ozone and aerosol levels in Earth’s atmosphere, cloud height, vegetation properties and the ultraviolet reflectivity of Earth.
The primary objective of DSCOVR, a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force, is to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA.”
It also makes for some pretty compelling time-lapse photography. If you watch carefully, you can see the clouds shift and change, as well as watch the seasons run their course as first the south pole comes into view, and then the north. The satellite’s first, impressive image was released last year on July 20, and now we finally have a full year’s worth of the Earth to marvel at—or science is a lie, the Earth is flat, and the universe is boring. Take your pick.
—The Mary Sue has a strict comment policy that forbids, but is not limited to, personal insults toward anyone, hate speech, and trolling.— | <urn:uuid:ac832da3-367f-430f-9597-aa9370fab056> | 3.21875 | 428 | Personal Blog | Science & Tech. | 44.444147 | 95,511,328 |
The Magnet Doctors Are In
Imagine this: After months of installation, your equipment is on the floor and ready to go. The electron beam is on. You’re finally about to collect data, when suddenly the superconducting magnet in your detector stops working. Normally, when the electron beam hits your target it creates a spray of particles that the superconducting magnet steers into your detector. But today, the magnet is shutting off instead of steering anything, and the on-call engineer can’t figure out why. Who do you call?
The Magnet Group, of course!
The Magnet Group is a newly formed technical support group in the Experimental Nuclear Physics Division at the Department of Energy’s Jefferson Lab. Its members are like doctors for magnets: If a magnet is sick, they make it better. They can provide support to all of Jefferson Lab’s existing and future magnets, both superconducting and resistive.
The group’s origin story begins in 2013, when Jefferson Lab sought superconducting magnet engineers for the 12 GeV Upgrade. Senior management considered forming a magnet group back then, but ultimately decided not to, so that the engineers could concentrate on the new and refurbished magnets needed for the upgrade.
“Working on the 12 GeV Upgrade, we were spread out pretty much all over Jefferson Lab’s four halls,” says Ruben Fair, an electrical engineer. “We gathered a lot of experience, and we really didn’t want that information and expertise to disappear.”
When the upgrade was completed in 2017, Fair sought the creation of an official group of magnet masters, so that their expertise could be consolidated for the benefit of the whole lab. The group’s official birth date was Dec. 1, 2017, and Fair was appointed its leader.
Of the group’s eight members, two are designers, two are electrical engineers, one is a physicist and three are mechanical engineers with more than 200 years of accumulated experience between them from a wide variety of fields. The engineers work together with their designers and other groups at the laboratory to carry out calculations and to create and translate designs into reality.
The Magnet Group’s main function is to provide round-the-clock, magnet-related support to the physicists running experiments, for example when the lab’s electron beam was on recently. If the hall engineer on-call couldn’t resolve a magnet issue, a member of the group would come in to figure out what was wrong and to determine what could be done to allow the physicists to continue with their work.
“You couldn’t carry out the groundbreaking research done here without these magnets,” Fair says.
While superconducting magnets steer particles into the detectors, resistive magnets in the accelerator steer the electron beam itself. Both play critical roles in nuclear physics experiments.
Fair says that most magnets at Jefferson Lab are well designed, so they don’t have many issues. One of the issues that can arise with magnets is quenching, where the magnet suddenly switches from zero resistance to a resistive state and rapidly heats up, which causes the control system to run the magnet down to prevent it from overheating.
Another issue that would require a magnet master’s help involves control systems. Fair says that lately, the Magnet Group has been investigating some issues with what they believe are the electronics that monitor and control the magnets. These electronics run down the magnet to protect it, but the group thinks these monitoring systems might be too sensitive, flipping a magnet off because of over-sensitivity and not because there is a real problem. They plan to investigate this mystery further this summer.
In addition to troubleshooting existing magnets, the group also helps make new ones. Magnet Group members are currently working with physicists to design magnets for a proposed electron-ion collider as well as to prepare magnets for other upcoming projects in the halls. In addition, members of the Magnet Group participate in Department of Energy review panels for other national labs’ magnet designs, as well as evaluate proposals from national labs, universities and small companies. Others in the magnet field also contact them for advice.
However, Fair says the Magnet Group’s other main priority is assisting work groups at Jefferson Lab with the design and maintenance of magnets here. Members of the group can be reached via contact information displayed on the group’s website: https://www.jlab.org/physics/magnet-group/magnethome.
Contact: Kandice Carter, 757-269-7263, firstname.lastname@example.org.
By Chris Patrick
Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy's Office of Science.DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov. | <urn:uuid:ba1d7ea2-5100-4c60-b1ee-8e2d87a98c4b> | 2.796875 | 1,066 | News (Org.) | Science & Tech. | 45.411858 | 95,511,341 |
Solutions for Chapter 11
Determine the required magnitude of force P to maintain equilibrium of the linkage at θ = 60°. Each link has a mass of 20 kg.
A mechanism with two links and a roller is gives.
Force applies on roller is P
Mass of each link,
Weight of each link,
Equilibrium of linkage at
Length of each link,
Coordinates and y are measured from hinge point A which is fixed
Let us give a virtual displacement of to link AB. We need to differentiate (1) and (2) to get virtual displacement in y and
Differentiate (1) and (2),
Hinge force at A does not do any work as no displacement at A. virtual work done by weight W is positive as line of action is in e direction as positive sense of virtual displacement
Load P does positive virtual work as its line of action is also in positive sense of (Assuming is positive)
Using (3) and (4)
As, is negative virtual work done by P is negative
Therefore, required magnitude of force is | <urn:uuid:8f6d7bee-d771-4eb7-9689-645cd7ae4905> | 3.359375 | 226 | Tutorial | Science & Tech. | 40.361545 | 95,511,349 |
Aug 11, 2016 08:10 AM EDT
New research speculates that it might be possible for aliens to convert gas giants into stellar objects.
The quest for aliens should be started by looking for stellified objects
The paper which will be published in Journal of British Interplanetary Society, claims that scientists can find any sign of aliens by looking for stellified objects. Stellification is a process where Jovian-class planet turns into a star.
Quoting from Outer Places, "At first, the black hole would start consuming the planet, but then the mass amounts of radiation would prevent any further flow of material." The energy created with the radiation will illuminate the surface like any other star.
It is a dangerous process according to astronomers. If these objects do exist, it simply shows that aliens are smart enough to consider the risks of jeopardizing the solar system.
Previously, scientists believe that Jupiter may host aliens but it is hard to find evidence given the planet is made up of gas. Researchers are also targeting Jupiter's moon, Europa, as potential candidate to hold the evidence of life since it's covered with ice. This would be the suitable place to find signs of life since there is water, Express UK wrote.
The process to detect stellified planet may not be that easy but it could be possible because the astronomy observation has progressed dramatically since decades ago. Thus, albeit the difficult effort, it might be done sooner.
Milan Ćirković said that the first step begins with searching starts with very small size in terms of radius and mass. The scientist from Astronomical Observatory of Belgrade explained that if the suspect object is located in the binary system with one planet in habitable zone nearby - then it will make the potential candidate.
Furthermore, Cirkovic speculates that alien may have motifs like humans; for instance, the need to search energy, habitat, and other resources. There can be possibilities of aliens producing the brown dwarf - object too small to be called a star yet to large to be a planet.
See Now: Facebook will use AI to detect users with suicidal thoughts and prevent suicide© 2017 University Herald, All rights reserved. Do not reproduce without permission. | <urn:uuid:0d55759f-afdb-4c8c-987b-d189b6f18cfa> | 3.28125 | 451 | News Article | Science & Tech. | 40.992204 | 95,511,350 |
According to an article in the August issue of Microbiology Today, this technology has an added bonus: leftover enzymes can be used to scavenge precious metals from spent automotive catalysts to help make fuel cells that convert hydrogen into energy.
Hydrogen has three times more potential energy by weight than petrol, making it the highest energy-content fuel available. Research into using bacteria to produce hydrogen has been revived thanks to the rising profile of energy issues.
We throw away a third of our food in the UK, wasting 7 million tonnes a year. The majority of this is currently sent to landfill where it produces gases like methane, which is a greenhouse gas 25 more potent than carbon dioxide. Following some major advances in the technology used to make "biohydrogen", this waste can now be turned into valuable energy.
"There are special and yet prevalent circumstances under which micro-organisms have no better way of gaining energy than to release hydrogen into their environment," said Dr Mark Redwood from the University of Birmingham. "Microbes such as heterotrophs, cyanobacteria, microalgae and purple bacteria all produce biohydrogen in different ways."
When there is no oxygen, fermentative bacteria use carbohydrates like sugar to produce hydrogen and acids. Others, like purple bacteria, use light to produce energy (photosynthesis) and make hydrogen to help them break down molecules such as acids. These two reactions fit together as the purple bacteria can use the acids produced by the fermentation bacteria. Professor Lynne Macaskie's Unit of Functional Bionanomaterials at the University of Birmingham has created two bioreactors that provide the ideal conditions for these two types of bacteria to produce hydrogen.
"By working together the two types of bacteria can produce much more hydrogen than either could alone," said Dr Mark Redwood. "A significant challenge for the development of this process to a productive scale is to design a kind of photobioreactor that is cheap to construct and able to harvest light from a large area. A second issue is connecting the process with a reliable supply of sugary feedstock."
With a more advanced pre-treatment, biohydrogen can even be produced from the waste from food-crop cultivation, such as corn stalks and husks. Tens of millions of tonnes of this waste is produced every year in the UK. Diverting it from landfill into biohydrogen production addresses both climate change and energy security.
The University of Birmingham has teamed up with Modern Waste Ltd and EKB Technology Ltd to form Biowaste2energy Ltd, which will develop and commercialise this waste to energy technology.
"In a final twist, the hydrogenase enzymes in the leftover bacteria can be used to scavenge precious metals from spent automotive catalysts to help make fuel cell that converts hydrogen into electricity," said Professor Lynne Macaskie. "So nothing is wasted and an important new application can be found for today's waste mountain in tomorrow's non-fossil fuel transport and energy."
Lucy Goodchild | alfa
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....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
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20.07.2018 | Physics and Astronomy
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"These images, dramatic as they are, are not the best Galileo will provide. These are distant snapshots taken during Galileo's encounter with a different moon, Ganymede. We'll shoot a whole photo album when Galileo takes its targeted pass at Europa in December.
"We're not going to jump the gun. These pictures do not prove the existence of liquid water on Europa, and the higher-resolution pictures yet to come may not prove it. A few days ago, I greeted the possibility of ancient microbial life on Mars with skeptical optimism, and invited further scientific examination and debate. I greet the new pictures of Europa in the same light.
"The pictures are exciting and compelling, but not conclusive. The potential for liquid water on Europa is an intriguing possibility, and another step in our quest to explore the solar system, the stars, and the answer to the great mystery of whether life exists anywhere else in the cosmos.
"We won't wait for all the answers. We'll release the data as soon as it's available, and share the excitement of discovery not only with scientists, but with the American public, with educators, and especially with children. This is their space program, the American space program, and they should share in the awe and wonder of exploration.
"Once again, NASA will ask the scientific process to work. We'll ask the best minds in the world to analyze these pictures, and the pictures from our targeted pass at Europa. Then we'll ask the scientific community to suggest the best way to follow up on these fascinating findings. As always, NASA will seek to continue to expand knowledge, and find the fastest, best and most efficient ways to further this research."
Headquarters, Washington, DC (August 13, 1996) | <urn:uuid:e7ad8b75-0e1d-4861-afcd-b49b88e928f0> | 3.015625 | 357 | News (Org.) | Science & Tech. | 45.95775 | 95,511,363 |
Flows of Viscous Fluids
It was shown above that the flow of an ideal fluid in the field of a potential force produces no vortexes,—i.e., a potential flow remains potential at any time. In real flows, however, we regularly observe a production and destruction of vortexes. This is because the real fluid is a viscous one. The assumption that there is a slip at the boundary between a flowing fluid and a solid (as in the case of an ideal fluid) also turns out to be incorrect for a real fluid. All components of the velocity vanish on the surface of a body at rest, according to experiments. That is why the dust accumulates on the surfaces of bodies even when flow exists past these bodies (the dust on blades of a fan, for example).
KeywordsBoundary Layer Drag Coefficient Viscous Fluid Ideal Fluid Viscous Force
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London: An international team has observed massive "dead" galaxies in the universe four billion years after the Big Bang which can reveal the formation and evolution of huge galaxies today.
Furthermore, they identified progenitors of these dead galaxies when they were forming stars at an earlier cosmic epoch.
This study establishes a consistent picture of the history of massive galaxies over 11 billion years of cosmic time.
"We would like to explore galaxy evolution in more detail by carrying out an object-by-object study and by extending the method to an even earlier epoch," said Dr. Masato Onodera from Swiss Federal Institute of Technology in Zurich, Switzerland.
In the local universe, massive galaxies hosting more than about 100 billion stars are predominantly dead elliptical galaxies, without any signs of star-formation activity.
The team used Subaru Telescope at the summit of Mauna Kea, Hawaii, to observe multiple objects simultaneously, efficiently observing a sample of 24 faint galaxies.
They created a composite spectrum that would have taken 200 hours of Subaru Telescope`s time for a single spectrum of comparable quality.
They discovered that the stellar content of these galaxies is strikingly similar to that of massive elliptical galaxies seen locally.
The analysis shows that the age of the galaxies is already one billion years old when observed four billion years after the Big Bang.
They host 1.7 times more heavy elements relative to the amount of hydrogen.
The results reveal that these massive dead galaxies have evolved without further star formation.
The research was published in The Astrophysical Journal. | <urn:uuid:96202572-08de-417c-a862-acc1e7183800> | 3.171875 | 313 | Truncated | Science & Tech. | 28.1125 | 95,511,377 |
Projectile Motion Lab: Using a Toy Gun Purpose: The purpose of this investigation is to measure the vertical displacement, or height of the launch, and the horizontal displacement, or range, travelled by a projectile (bullet from toy gun). Questions: What is the shape of the actual path travelled by a projectile? How closely does an actual projectile’s results follow the theoretical predicted results? Hypothesis: The shape of the path travelled by the projectile, in this case the bullet of the gun, is a parabolic.
This means that is a curvy shape due to the bullet being launched in the air (making curve go up) and the earth’s gravity pulling it down (making curve go down). As the height of the bullet’s release increases the the time to reach the ground will increase, and therefore the range of the bullet will increase. This is because the bullet’s vertical velocity will decrease later as the height is higher up, having a larger time, and therefore a larger range. Materials: Toy Gun Fake Bullets Metre Sick Stop Watch General Observations: A metre stick was used to measure the height and the range of the bullet.
A stop was used to determine the time it took for the bullet to reach the ground. As the bullet was released, its path was parabolic. This means that its was curvy because it was first int air, but the gravity pulled it back down to the surface. The toy gun was steadily held in my hand. The initial height was the distance from the gun to the surface used. The gun shot out the bullets at a fairly fast speed. As the height was increased, the more time the bullet took to reach the ground. As the height was increased, the range was also higher.
Observation Table: Data of various heights used: | Height (cm) |Time (seconds) |Horizontal Distance (cm) | |25 |2. 26 |70. 7 | |50 |3. 19 |100 | |75 |3. 1 |122 | |100 |4. 52 |141 | Analysis: Picture of the launcher: Height vs. Range graph- Refer to attached data in the back. Position vs. Time graph- Refer to attached data in the back. The graph results definitely support the hypothesis. This is because as the height of the toy gun was increased, the horizontal distance increased.
Also, as the horizontal distance of the bullet increased, so did the time (vice- versa). The graphs were very similar due to the horizontal distance (cm) being constant on the y- axis of the graph. In the Horizontal Distance vs. Time graph, the time represented the corresponding heights of the Horizontal Distance vs Height graph. Making the graphs very similar. Determining the Vi of the Bullet: Vi = aav x ? t aav = -9. 81 m/s? ?t = 3. 19 seconds Vi = -9. 81 x 3. 19 Vi = 31. 3 m/s [v] *Therefore the initial velocity of the bullet is 31. 3 m/s [v]. Theoretical Ranges of the Bullet:
Formula- ? d = Vi x ? t |Height (cm): |Range/ Horizontal Displacement (cm) : | |25 |? d = 31. 3 x 2. 26 | | |? d = 70. 7 cm | |50 | ? d = 31. 3 x 3. 19 | | |? d = 99. 8 cm | |75 | ? d = 31. 3 x 3. 91 | | |? = 121 cm | |100 | ? d = 31. 3 x 4. 52 | | |? d = 142 cm | Experimental Percent Errors For each Range: Formula- % error = [ (experimental value – accepted
Sources of error: The first source of error was the toy gun’s bullet were not perfectly a cylinder. Since the bullets we made out of plastic foam there some ripped edges. This would definitely give a slightly inaccurate result sine the bullet would not consistently travel in the same way as it is going in a parabolic path. This would cause some twisting and turning of the bullet since the rips would collect air and make the bullet therefore move around (sort of like air pockets). The main problem with this is that the bullet is not consistently travelling in the exact same way.
Another source of error was that since the gun was shot from a human being’s hand it is really tough to keep the gun at the same angle (zero degrees) as it is shot. If the angle of the gun is not consistently shot at the same angle it will definitely impact the results because the horizontal distance (range) of the bullet will be different each time. If the gun has an angle pointing downward, the range will decrease. The bullet will be in the air for a smaller amount of time, covering less ground. If the gun is pointing upward the range will increase.
The bullet will be in the air for a longer period of time, covering more ground. There can be ways though to fix these sources of errors. For the first one where there were rips in the bullet, what one can do to fix the bullets is use tape to cover up the holes. Or, a better solution would to buy new, fresh bullets where there are no bend, rips or chance of disfunction. To make sure that the bullets angle is constant after each shot, what one can do is use a stand to place the gun in. This would make sure that the gun is not pointing down or upward, giving very accurate data of the range. Conclusion:
All projectiles travel in a parabolic path. Projectile motion is the motion of an object who’s path is affected by the force of gravity. Everything is affected by gravity, but it profoundly alters the motion of objects that are thrown or shot upward. The arching of the bullet in this experiment is caused by gravity, as well as its falling motion in general. Gravity causes change in the vertical velocity of the projectile. Objects experiencing projectile motion have a constant velocity in the horizontal direction, and a constantly changing velocity in the vertical direction. Thus, this is causing the parabolic shape.
The actual projectile’s results were really close to the theoretical results in this case. There were no outliers in the range. If the theoretical range and the actual range were not close it would be due to the tools used to measure the time and the distance. A metre stick was used to determine the horizontal range for the experiment. This is very inaccurate because the bullet dropped way to fast to see the actual landing spot. The landing spot was based on the eye. Also since a timer was used to determine the time of the bullet’s range this is again very inaccurate since the bullet dropped way to fast to use a stop watch.
Overall, the results in this case were luckily extremely close and accurate having a maximum percent error of 0. 00 8%. The reasons for the experimental error was mainly due to the tools used to measure data and, the inconsistency of the angle of the gun. As stated earlier a metre stick was used to determine the horizontal range for the experiment. This is very inaccurate because the bullet dropped way to fast to see the actual landing spot. The landing spot was based on the eye. Since a timer was used to determine the time of the bullet’s range this is again very inaccurate since the bullet dropped way to fast to use a stop watch.
Again as stated earlier, if the angle of the gun is not consistently shot at the same angle it will definitely impact the results because the horizontal distance (range) of the bullet will be different each time. If the gun has an angle pointing downward, the range will decrease. The bullet will be in the air for a smaller amount of time, covering less ground. If the gun is pointing upward the range will increase. The bullet will be in the air for a longer period of time, covering more ground. | <urn:uuid:e4354b93-4831-4aa5-94c7-e7609f91481f> | 3.8125 | 1,646 | Academic Writing | Science & Tech. | 66.039585 | 95,511,380 |
Astronomers looking at galaxies in the Universe’s distant past received a similar perplexing announcement when they found nine young, compact galaxies, each weighing in at 200 billion times the mass of the Sun.
The galaxies, each only 5,000 light-years across, are a fraction of the size of today's grownup galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.
Astronomers used the NASA/ESA Hubble Space Telescope and the W.M. Keck Observatory on Mauna Kea, Hawaii, to study the galaxies as they existed 11 billion years ago, when the Universe was less than 3 billion years old.
“Seeing the compact sizes of these galaxies is a puzzle", said Pieter G. van Dokkum of Yale University in New Haven, Connecticut, USA, who led the study. "No massive galaxy at this distance has ever been observed to be so compact. These galaxies would have to change a lot over 11 billion years, growing five times bigger. They could get larger by colliding with other galaxies, but such collisions may not be the complete answer. It is not yet clear how they would build themselves up to become the large galaxies we see today”.
To determine the sizes of the galaxies, the team used the Near Infrared Camera and Multi-Object Spectrometer on Hubble. The Keck observations were carried out with assistance of a powerful laser to correct for image blurring caused by the Earth's atmosphere. Only Hubble, Keck and ESO’s Very Large Telescope are really able to measure the sizes of these galaxies as they are very small and far away.
Van Dokkum and his colleagues studied the galaxies in 2006 with the Gemini South Telescope Near-Infrared Spectrograph, on Cerro Pachon in the Chilean Andes. Those observations provided the galaxies’ distances and showed that the stars are a half a billion to a billion years old. The most massive stars had already exploded as supernovae.
“In the Hubble Deep Field, astronomers found that star-forming galaxies are small”, said Marijn Franx of Leiden University, The Netherlands. “However, these galaxies were also very low in mass. They weigh much less than our Milky Way. Our study, which surveyed a much larger area than in the Hubble Deep Field, surprisingly shows that galaxies with the same weight as our Milky Way were also very small in the past. All galaxies look really different in early times, even massive ones that formed their stars early”.
The ultra-dense galaxies might comprise half of all galaxies of that mass 11 billion years ago, van Dokkum said, forming the building blocks of today’s largest galaxies.
How did these small, crowded galaxies form? One way, suggested van Dokkum, involves the interaction of dark matter and hydrogen gas in the nascent Universe. Dark matter is an invisible form of matter that accounts for most of the Universe’s mass. Shortly after the Big Bang, the Universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in pockets of the invisible material and began spinning rapidly in dark matter’s gravitational whirlpool, forming stars at a furious rate.
Based on the galaxies’ mass, which is derived from their colour, the astronomers estimated that the stars are spinning around their galactic disks at roughly 400 to 500 kilometres per second. Stars in today’s galaxies, by contrast, are travelling at about half that speed because they are larger and rotate more slowly than the compact galaxies.
These galaxies are ideal targets for the Wide Field Camera 3, which is scheduled to be installed aboard Hubble during Servicing Mission 4 in the fall of 2008.
The findings appeared in the April 10 issue of The Astrophysical Journal Letters.
Lars Christensen | alfa
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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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12.07.2018 | Event News
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|Aurelia aurita, Red Sea|
Aurelia aurita (also called the common jellyfish, moon jellyfish, moon jelly, or saucer jelly) is a widely studied species of the genus Aurelia. All species in the genus are closely related, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus. The most common method used to identify the species consists of selecting a jellyfish from a harbour using a device, usually a drinking glass and then photographing the subject. This means that they can be released in to the harbour shortly afterwards and return to their natural habitat.
The jellyfish is translucent, usually about 25–40 cm (10–16 in) in diameter, and can be recognized by its four horseshoe-shaped gonads, easily seen through the top of the bell. It feeds by collecting medusae, plankton, and mollusks with its tentacles, and bringing them into its body for digestion. It is capable of only limited motion, and drifts with the current, even when swimming.
The genus Aurelia is found throughout most of the world's oceans, from the tropics to as far north as latitude 70°N and as far south as 40°S. The species Aurelia aurita is found along the eastern Atlantic coast of Northern Europe and the western Atlantic coast of North America in New England and Eastern Canada. In general, Aurelia is an inshore genus that can be found in estuaries and harbors.
A. aurita lives in ocean water temperatures ranging from 6 to 31 °C (43 to 88 °F); with optimum temperatures of 9 to 19 °C (48 to 66 °F). It prefers temperate seas with consistent currents. It has been found in waters with salinity as low as 6 parts per thousand. The relation between summer hypoxia and moon jellyfish distribution is prominent during the summer months of July and August where temperatures are high and dissolved oxygen (DO) is low. Of the three environmental conditions tested, bottom DO has the most significant effect on moon jellyfish abundance. Moon jellyfish abundance is the highest when bottom dissolved oxygen concentration is lower than 2.0 mg L -1. Moon jellyfish show a strong tolerance to low DO conditions, which is why their population is still relatively high during the summer. Generally, hypoxia causes species to move from the oxygen depleted zone, but this is not the case for the moon jellyfish. Furthermore, bell contract rate, which indicates moon jellyfish feeding activity, remains constant although DO concentrations are lower than normal. During July and August it is observed that moon jellyfish aggregations of 250 individuals consumed an estimated 100% of the mesozooplankton biomass in the Seto Inland Sea. Other major fish predators that are also present in these coastal waters do not seem to show the same high tolerance to low DO concentrations that the moon jellyfish exhibit. The feeding and predatory performance of these fish significantly decreases when DO concentrations are so low. This allows for less competition between the moon jellyfish and other fish predators for zooplankton. Low DO concentrations in the coastal waters such as the Tokyo Bay in Japan and Seto Inland Sea prove to be advantageous for the moon jellyfish in terms of feeding, growth, and survival.
Aurelia aurita and other Aurelia species feed on plankton that includes organisms such as mollusks, crustaceans, tunicate larvae, rotifers, young polychaetes, protozoans, diatoms, eggs, fish eggs, and other small organisms. Occasionally, they are also seen feeding on gelatinous zooplankton such as hydromedusae and ctenophores. Both the adult medusae and larvae of Aurelia have nematocysts to capture prey and also to protect themselves from predators.
The food is caught with its nematocyst-laden tentacles, tied with mucus, brought to the gastrovascular cavity, and passed into the cavity by ciliated action. There, digestive enzymes from serous cell break down the food. There is little known about the requirements for particular vitamins and minerals, but due to the presence of some digestive enzymes, we can deduce in general that A. aurita can process carbohydrates, proteins and lipids.
Aurelia does not have respiratory parts such as gills, lungs or trachea, it respires by diffusing oxygen from water through the thin membrane covering its body. Within the gastrovascular cavity, low oxygenated water can be expelled and high oxygenated water can come in by ciliated action, thus increasing the diffusion of oxygen through cell. The large surface area membrane to volume ratio helps Aurelia to diffuse more oxygen and nutrients into the cells.
The basic body plan of Aurelia consists of several parts. The animal lacks respiratory, excretory, and circulatory systems. The adult medusa of Aurelia, with a transparent look, has an umbrella margin membrane and tentacles that are attached to the bottom. It has four bright gonads that are under the stomach. Food travels through the muscular manubrium while the radial canals help disperse the food. There is a middle layer of mesoglea, gastrodervascular cavity with gastrodermis, and epidermis. There is a nerve net that is responsible for contractions in swimming muscles and feeding responses. Adult medusae can have diameters up to 40 cm (16 in).
The medusae are either male or female. The young larval stage, a planula, has small ciliated cells and after swimming freely in the plankton for a day or more, settles on an appropriate substrate, where it changes into a special type of polyp called a "scyphistoma", which divides by strobilation into small ephyrae that swim off to grow up as medusae. There is an increasing size from starting stage planula to ephyra, from less than 1 mm in the planula stage, up to about 1 cm in ephyra stage, and then to several cm in diameter in the medusa stage.
Aurelia aurita is known to be eaten by a wide variety of predators, including the ocean sunfish (Mola mola), the leatherback sea turtle (Dermochelys coriacea), the scyphomedusa Phacellophora camtschatica, and a very large hydromedusa (Aequorea victoria). Recently it was reported from the Red Sea that Aurelia aurita was seasonally preyed upon by two herbivorous fish. Moon jellies are also fed upon by sea birds, which may be more interested in the amphipods and other small arthropods that frequent the bells of Aurelia, but in any case, birds do some substantial amount of damage to these jellyfish that often are found just at the surface of bays.
Aurelia jellyfish naturally die after living and reproducing for several months. It is probably rare for these moon jellies to live more than about six months in the wild, although specimens cared for in public aquarium exhibits typically live several to many years. In the wild, the warm water at the end of summer combines with exhaustive daily reproduction and lower natural levels of food for tissue repair, leaving these jellyfish more susceptible to bacterial and other disease problems that likely lead to the demise of most individuals. Such problems are responsible for the demise of many smaller species of jellyfish. In 1997, Arai summarized that seasonal reproduction leaves the gonads open to infection and degradation.
Aurelia sp. from the Monterey Bay Aquarium
- Dawson, Michael N. "Aurelia species". Retrieved 2008-08-12.
- Dawson, M. N.; Sen Gupta, A.; England, M. H. (2005). "Coupled biophysical global ocean model and molecular genetic analyses identify multiple introductions of cryptogenic species". Proc. Natl. Acad. Sci. USA. 102 (34): 11968–11973. doi:10.1073/pnas.0503811102. PMC .
- Dawson, M. N. (2003). "Macro-morphological variation among cryptic species of the moon jellyfish, Aurelia (Cnidaria: Scyphozoa)". Marine Biology. 143 (2): 369–379. doi:10.1007/s00227-003-1070-3.
- Russell, F. S. 1953. The Medusae of the British Isles II. Cambridge University Press, London, 81-186. http://www.mba.ac.uk/nmbl/publications/medusae_2/medusae_2.htm
- Rodriguez, R. J. February 1996. Aurelia aurita (Saucer Jelly, Moon Jelly, Common Sea Jelly Jellyfish) Narrative
- Shoji, J.; Yamashita, R.; Tanaka, M. (2005). "Effect of low dissolved oxygen concentrations on behavior and predation rates on fish larvae by moon jellyfish Aurelia aurita and by a juvenile piscivore, Spanish mackerel Scomberomorus niphonius". Marine Biology. 147 (4): 863–868. doi:10.1007/s00227-005-1579-8.
- Uye, S.; Fujii, N.; Takeoka, H. (2003). "Unusual aggregations of the scyphomedusa Aurelia aurita in coastal waters along western Shikoku, Japan". The Plankton Society of Japan. 50 (1): 17–21.
- Arai, M. N. (1997). A Functional Biology of Scyphozoa. London: Chapman and Hall. pp. 68–206. ISBN 0-412-45110-7.
- Rees, W. J. (1966). The Cnidaria and Their Evolution. London: Academic Press. pp. 77–104.
- Solomon, E. P.; Berg, L. R.; Martin, W. W. (2002). Biology (6th ed.). London: Brooks/Cole. pp. 602–608. ISBN 0-534-39175-3.
- Tree of Life - NJ Jellyfish - Aurelia aurita
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- He, J,; Zheng, L,; Zhang, W,; Lin, Y (2015). "Life Cycle Reversal in Aurelia sp.1 (Cnidaria, Scyphozoa)". PLoS ONE. 10 (12): e0145314. doi:10.1371/journal.pone.0145314. PMC . PMID 26690755.
- Strand, S. W.; Hamner, W. M. (1988). "Predatory behavior of Phacellophora camtschatica and size-selective predation upon Aurelia aurita (Scyphozoa: Cnidaria) in Saanich Inlet, British Columbia". Marine Biology. 99 (3): 409–414. doi:10.1007/BF02112134.
- Towanda, T.; Thuesen, E. V. (2006). "Ectosymbiotic behavior of Cancer gracilis and its trophic relationships with its host Phacellophora camtschatica and the parasitoid Hyperia medusarum" (PDF). Marine Ecology Progress Series. 315: 221–236.
- Bos A.R., Cruz-Rivera E. and Sanad A.M. (2016). "Herbivorous fishes Siganus rivulatus (Siganidae) and Zebrasoma desjardinii (Acanthuridae) feed on Ctenophora and Scyphozoa in the Red Sea". Marine Biodiveristy. doi:10.1007/s12526-016-0454-9.
- Mills, C. E. (1993). "Natural mortality in NE Pacific coastal hydromedusae: grazing predation, wound healing and senescence". Bulletin of Marine Science. 53 (Proceedings of the Zooplankton Ecology Symposium): 194–203. | <urn:uuid:508f744c-b077-43ab-b3b5-25faab74a652> | 3.59375 | 2,609 | Knowledge Article | Science & Tech. | 55.259953 | 95,511,397 |
Researchers from the University of Washington and the German Space Agency (DLR) measured the dramatic speeds of the fast-flowing glacier in 2012 and 2013. The results are published today in The Cryosphere, an open access journal of the European Geosciences Union (EGU).
Iceberg from Jakobshavn Isbræ, Disko Bay
Ian Joughin, PSC/APL/UW
“We are now seeing summer speeds more than 4 times what they were in the 1990s on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland,” says Ian Joughin, a researcher at the Polar Science Center, University of Washington and lead-author of the study.
In the summer of 2012 the glacier reached a record speed of more than 17 kilometres per year, or over 46 metres per day. These flow rates are unprecedented: they appear to be the fastest ever recorded for any glacier or ice stream in Greenland or Antarctica, the researchers say.
They note that summer speeds are temporary, with the glacier flowing more slowly over the winter months. But they add that even the annually averaged speedup over the past couple of years is nearly 3 times what it was in the 1990s.
This speedup of Jakobshavn Isbræ means that the glacier is adding more and more ice to the ocean, contributing to sea-level rise. “We know that from 2000 to 2010 this glacier alone increased sea level by about 1 mm. With the additional speed it likely will contribute a bit more than this over the next decade,” explains Joughin.
Jakobshavn Isbræ, which is widely believed to be the glacier that produced the large iceberg that sank the Titanic in 1912, drains the Greenland ice sheet into a deep ocean fjord on the coast of the island. At its calving front, where the glacier effectively ends as it breaks off into icebergs, some of the ice melts while the rest is pushed out, floating into the ocean. Both of these processes contribute about the same amount to sea-level rise from Greenland.
As the Arctic region warms, Greenland glaciers such as Jakobshavn Isbræ have been thinning and calving icebergs further and further inland. This means that, even though the glacier is flowing towards the coast and carrying more ice into the ocean, its calving front is actually retreating. In 2012 and 2013, the front retreated more than a kilometre further inland than in previous summers, the scientists write in the new The Cryosphere study.
In the case of Jakobshavn Isbræ, the thinning and retreat coincides with an increase in speed. The calving front of the glacier is now located in a deeper area of the fjord, where the underlying rock bed is about 1300 metres below sea level, which the scientists say explains the record speeds it has achieved. “As the glacier’s calving front retreats into deeper regions, it loses ice – the ice in front that is holding back the flow – causing it to speed up,” Joughin clarifies.
The team used satellite data to measure the speed of the glacier as part of US National Science Foundation (NSF) and NASA studies. “We used computers to compare pairs of images acquired by the German Space Agency’s (DLR) TerraSAR-X satellites. As the glacier moves we can track changes between images to produce maps of the ice flow velocity,” says Joughin.
The researchers believe Jakobshavn Isbræ is in an unstable state, meaning it will continue to retreat further inland in the future. By the end of this century, its calving front could retreat as far back as the head of the fjord through which the glacier flows, about 50 km upstream from where it is today.
Please mention the name of the publication (The Cryosphere) if reporting on this story and, if reporting online, include a link to the paper or to the journal website (http://www.the-cryosphere.net).*More information*
The researchers produced the data presented in the study under the NASA-sponsored Greenland Ice Mapping Project, and carried out the analysis of the data at the Center for Remote Sensing of Ice Sheets, sponsored by the US National Science Foundation.
The scientific article is available online, free of charge, from the publication date onwards, at http://www.the-cryosphere.net/recent_papers.html. *To obtain a copy of the paper before the publication date, please email Bárbara Ferreira at email@example.com.*
The discussion paper (before peer review) and reviewers comments is available at http://www.the-cryosphere-discuss.net/7/5461/2013/tcd-7-5461-2013.html.
The team is composed of Ian Joughin, Benjamin E. Smith and David E. Shean from the University of Washington, Seattle, US, and Dana Floricioiu from the German Aerospace Center (DLR), Weßling, Germany.
The European Geosciences Union (www.egu.eu) is Europe’s premier geosciences union, dedicated to the pursuit of excellence in the Earth, planetary, and space sciences for the benefit of humanity, worldwide. It is a non-profit interdisciplinary learned association of scientists founded in 2002. The EGU has a current portfolio of 15 diverse scientific journals, which use an innovative open access format, and organises a number of topical meetings, and education and outreach activities. Its annual General Assembly is the largest and most prominent European geosciences event, attracting over 11,000 scientists from all over the world. The meeting’s sessions cover a wide range of topics, including volcanology, planetary exploration, the Earth’s internal structure and atmosphere, climate, energy, and resources. The 2014 EGU General Assembly is taking place is Vienna, Austria from 27 April to 2 May 2014. For information regarding the press centre at the meeting and media registration, please check http://media.egu.eu.
If you wish to receive our press releases via email, please use the Press Release Subscription Form at http://www.egu.eu/news/subscribe/. Subscribed journalists and other members of the media receive EGU press releases under embargo (if applicable) 24 hours in advance of public dissemination.*Contacts*
Dr. Bárbara Ferreira | European Geosciences Union
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
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:43f509be-fdd6-4a4a-a3c2-4dbfe446efb5> | 3.921875 | 1,995 | Knowledge Article | Science & Tech. | 48.441209 | 95,511,411 |
A revolutionary new scientific method developed at the University of Leeds will improve the diversity of 'biologically active molecules', such as antibiotics and anti-cancer agents.
The researchers, who report their findings online today in the journal Nature Chemistry, took their inspiration from evolution in nature. The research may uncover new pharmaceutical drugs that traditional methods would never have found.
"Nature produces some amazing structures with really interesting biological activity, but the plant or animal did not design them. Instead the organisms gradually evolved both the chemical structures and the methods to produce them over millennia because they were of benefit. We wanted to capture the essence of this in our approach to discovering new drugs," said George Karageorgis, a PhD student from the School of Chemistry and the Astbury Centre for Structural Molecular Biology at the University of Leeds, and first author of the study.
The traditional method for discovering new drugs involves preparing new biologically active molecules by adjusting the chemical structure of an existing one slightly and analysing the results. This trial and error method is both time consuming and limits the variety of new types of drugs that are developed.
"There is a known problem with limited diversity in drug discovery. It's like a baker always going to the same storage cupboard and using the same ingredients, yet hoping to create something that tastes different," said Dr Stuart Warriner from the School of Chemistry and the Astbury Centre for Structural Molecular Biology at the University of Leeds, a co-author of the research paper.
"Our novel approach is like taking lots of different ingredients – including things you may never think will work together – and trying different combinations of these in each cup of a cupcake tray. If the result 'tastes' promising then we use this as the starting point for another set of experiments. Only at the end, when we have something really good, do we work out exactly what we have made."
In the study, the researchers investigated the reactions of 12 types of an organic molecule called a 'diazo' compound. The researchers chose to study reactions of diazo compounds as they have many possible outcomes, depending on the specific reaction conditions (such as the temperature and concentrations used) and the choice of the reaction catalyst.
Different types and quantities of the reaction 'ingredients' were added to each of the 96 wells of an experiment tray and the products of the reaction were then tested to see if they had the required biological effect.
"The key to our method is using very promiscuous reactions which can lead to many different interesting products. Normally, these are the sort of reactions that chemists would steer well clear of, but in this case it's actually an advantage and gives us the chance of finding some diverse and active structures," said Dr Warriner.
To assess the effectiveness of the reaction products as drugs, the researchers studied how well they could activate a particular biologically relevant protein called the 'androgen receptor', which is important in the progression of certain cancers.
The results informed two further rounds of experiments on the most promising candidates, from which the researchers eventually identified three biologically active molecules.
"It's very unlikely that anyone would have ever designed these molecules or thought to use these compound classes against this target, but we have reached that result very efficiently and rapidly using our methodology," said Karageorgis.
Professor Adam Nelson from the School of Chemistry and the Astbury Centre for Structural Molecular Biology at the University of Leeds, a co-author on the paper, concludes: "The beauty of our approach is that pharmaceutical companies could start using it tomorrow, as you don't need any specialist equipment. What we need to do now is to run further studies and add even more diversity to the potential products of our reactions to convince other scientists to adopt this new technique."
The Engineering and Physical Sciences Research Council (EPSRC) provided funding for the equipment used in this study. Karageorgis' PhD studies are supported by a University of Leeds scholarship.
George Karageorgis, Dr Stuart Warriner and Professor Adam Nelson are available for interview. Please contact Sarah Reed, Press Officer, University of Leeds, on 0113 34 34196 or email firstname.lastname@example.org
The research paper, 'Efficient Discovery of Bioactive Scaffolds by Activity-Directed Synthesis' (http://dx.doi.org/10.1038/nchem.2034), is published online by the journal Nature Chemistry on 24 August 2014.
University of Leeds
The University of Leeds is one of the largest higher education institutions in the UK and a member of the Russell Group of research-intensive universities. http://www.leeds.ac.uk
Sarah Reed | Eurek Alert!
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
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Albireo is the distinctive double star in the head of the constellation Cygnus. You can find it yourself if you look for the Summer Triangle amid the dusty trail of the Milky Way across the night sky.
The brighter, orange star of Albireo is a K3-class bright giant. That means it’s just a few thousand Kelvins (Celsius degrees plus 273) cooler than the sun. But it’s also larger—70 times the sun’s radius—and that makes it brighter than you would expect.
The blue star, on the other hand, is a B8-class dwarf. It has only about 3.5 times the sun’s radius, although it’s hotter by about 7422 Kelvins.
Neither star in Albireo is particularly unusual. There are doubtless millions, even billions, of other stars similar to each one. But Albireo certainly offers us the most striking contrast. Bright blue and red stars don’t often appear so close together.
But what exactly gives these stars their distinctive colors? Continue reading
Recognize this constellation?
Well, at the time stamp of about 2000 AD (CE), I think you will. It’s one of the most famous constellations in the night sky.
Well, technically, it’s not a constellation at all.
It’s an asterism—a commonly recognized grouping of stars that isn’t actually official as a constellation. There are tons of asterisms that you no doubt recognize…the Summer Triangle, the Great Square of Pegasus, the Big Dipper.
That’s right. That mess of stars up there that keeps changing for some reason…that’s the oft-recognized Big Dipper, part of the constellation Ursa Major.
So why the heck are the stars moving? Continue reading
We can’t see below the surface of the sun.
That makes sense, really. We can’t see below the surface of the Earth, either—we have to get creative if we want to find out what goes on below the crust.
In the sun’s case, we can’t see below its photosphere because the gases within are so dense, light can’t escape. And we depend on light to see anything.
So…if we can’t see inside the sun, how do we study it? Continue reading
You might, if you’ve ever seen the sun through a telescope before. What you’re seeing is the photosphere, the layer of the sun whose light reaches Earth. This is the only layer you’ll ever see, without the aid of a solar eclipse.
Wait a second…what do I mean, layers? I mean, I know what a layer is, but what kind of layers does the sun have?
Well, it’s got a few, just like the Earth. Continue reading
Have you ever heard the ice cream truck?
When I was little, I remember hearing the ice cream truck all the time. Just the sound of the opening notes of “Pop Goes the Weasel” were enough to propel me to the door, where I’d beg my parents to let me go out.
Of course, I didn’t always make it out front in time. But one day, my dad found a way to solve that problem—by actually getting in the car and chasing the ice cream truck.
I remember us driving around the neighborhood, following that white truck around. A few times, it slowed and stopped, but when we stopped too, it kept going again. It took a while for the driver to realize we were following him!
Eventually, we caught it, and had a good laugh over it. But the moral of the story is…have you ever noticed that you can tell if something is moving toward you or away from you, just by if it’s getting louder or quieter?
The same trick works for stars…sort of. Continue reading | <urn:uuid:b5f8a0fd-7300-4ecf-8692-53c74d761f1f> | 3.46875 | 848 | Content Listing | Science & Tech. | 74.488194 | 95,511,444 |
Most spiral galaxies in the Universe have a bar structure in their centre, and Hubble's image of NGC 1073 offers a particularly clear view of one of these. Galaxies' star-filled bars are thought to emerge as gravitational density waves funnel gas toward the galactic centre, supplying the material to create new stars. The transport of gas can also feed the supermassive black holes that lurk in the centres of almost every galaxy.
The NASA/ESA Hubble Space Telescope has taken a picture of the barred spiral galaxy NGC 1073, which is found in the constellation of Cetus (The Sea Monster). Our own galaxy, the Milky Way, is thought to be a similar barred spiral, and the study of galaxies such as NGC 1073 can help astronomers learn more about our celestial home. Credit: NASA & ESA
Some astronomers have suggested that the formation of a central bar-like structure might signal a spiral galaxy's passage from intense star-formation into adulthood, as the bars turn up more often in galaxies full of older, red stars than younger, blue stars. This storyline would also account for the observation that in the early Universe, only around a fifth of spiral galaxies contained bars, while more than two thirds do in the more modern cosmos.
While Hubble's image of NGC 1073 is in some respects an archetypal portrait of a barred spiral, there are a couple of quirks worth pointing out.
One, ironically, is almost — but not quite — invisible to optical telescopes like Hubble. In the upper left part of the image, a rough ring-like structure of recent star formation hides a bright source of X-rays. Called IXO 5, this X-ray source is likely to be a binary system featuring a black hole and a star orbiting each other. Comparing X-ray observations from the Chandra spacecraft with this Hubble image, astronomers have narrowed the position of IXO 5 down to one of two faint stars visible here. However, X-ray observations with current instruments are not precise enough to conclusively determine which of the two it is.
Hubble's image does not only tell us about a galaxy in our own cosmic neighbourhood, however. We can also discern glimpses of objects much further away, whose light tells us about earlier eras in cosmic history.
Right across Hubble's field of view, more distant galaxies are peering through NGC 1073, with several reddish examples appearing clearly in the top left part of the frame.
Image credit: NASA & ESALinks
Oli Usher | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | 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
12.07.2018 | Event News
03.07.2018 | Event News
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18.07.2018 | Materials Sciences
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This image was taken by ESA astronaut Alexander Gerst from the International Space Station on 30 June 2018 when the Moon and Mars were at its closest so far during his six-month Horizons mission.
Tiny creatures that lived in the dark—either underground or below the sea floor—were the dominant life forms on Earth for much of the planet's history, a study suggests.
In a new report published this week scientists from leading UK and Norwegian research institutions highlights the urgency to further investigate the least understood regions on Earth.
There may be more than a quadrillion tons of diamond hidden in the Earth's interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate ...
A multinational team of scientists has just found the first fragments of the small asteroid 2018 LA, which exploded harmlessly high above Africa on June 2. The University of Hawaiʻi's Asteroid Terrestrial-Impact Last Alert ...
New observations by three of the world's largest radio telescopes have revealed that an asteroid discovered last year is actually two objects, each about 3,000 feet (900 meters) in size, orbiting each other.
The Earth was apparently losing water.
The discovery of Earth's youngest-ever banded iron formation is changing how scientists understand the evolution of complex life, according to a study by University of Alberta geologists.
Zimbabwean President Emmerson Mnangagwa Tuesday launched a space agency, hailing it as a "milestone" as he campaigns ahead of elections at the end of the month.
Scientists from The Australian National University (ANU) and overseas have discovered the oldest colours in the geological record, 1.1 billion-year-old bright pink pigments extracted from rocks deep beneath the Sahara desert ... | <urn:uuid:5f4396ce-7603-46f4-a493-efdcec2bdd12> | 3.25 | 369 | Content Listing | Science & Tech. | 47.226 | 95,511,461 |
At the Massachusetts Institute of Technology he also worked on the differential analyser, an early type of mechanical computer developed by Vannevar Bush for obtaining numerical solutions to ordinary differential equations. Shannon published Mathematical theory of the differential analyzer in 1941. In the introduction to the paper he writes:-
The most important results [mostly given in the form of theorems with proofs] deal with conditions under which functions of one or more variables can be generated, and conditions under which ordinary differential equations can be solved. Some attention is given to approximation of functions (which cannot be generated exactly), approximation of gear ratios and automatic speed control.Shannon joined AT&T Bell Telephones in New Jersey in 1941 as a research mathematician and remained at the Bell Laboratories until 1972. Johnson writes in that Shannon:-
... became known for keeping to himself by day and riding his unicycle down the halls at night.D Slepian, a colleague at the Bell Laboratories wrote:-
Many of us brought our lunches to work and played mathematical blackboard games but Claude rarely came. He worked with his door closed, mostly. But if you went in, he would be very patient and help you along. He could grasp a problem in zero time. He really was quite a genius. He's the only person I know whom I'd apply that word to.Working with John Riordan, Shannon published a paper in 1942 on the number of two-terminal series-parallel networks. This paper extended results obtained by MacMahon who had published his early contribution in the Electrician in 1892.
Shannon published A Mathematical Theory of Communication in the Bell System Technical Journal (1948). This paper founded the subject of information theory and he proposed a linear schematic model of a communications system. This was a new idea. Communication was then thought of as requiring electromagnetic waves to be sent down a wire. The idea that one could transmit pictures, words, sounds etc. by sending a stream of 1s and 0s down a wire, something which today seems so obvious as we take this information from a server in St Andrews, Scotland, and view it anywhere in the world, was fundamentally new.
Shannon considered a source of information which generates words composed of a finite number of symbols. These are transmitted through a channel, with each symbol spending a finite time in the channel. The problem involved statistics with the assumption that if xn is the nth symbol produced by the source the xn process is a stationary stochastic process. He gave a method of analysing a sequence of error terms in a signal to find their inherent variety, matching them to the designed variety of the control system. In A Mathematical Theory of Communication , which introduced the word "bit" for the first time, Shannon showed that adding extra bits to a signal allowed transmission errors to be corrected. Slepian, in the introduction to , writes:-
Probably no single work in this century has more profoundly altered man's understanding of communication than C E Shannon's article, "A mathematical theory of communication", first published in 1948. The ideas in Shannon's paper were soon picked up by communication engineers and mathematicians around the world. They were elaborated upon, extended, and complemented with new related ideas. The subject thrived and grew to become a well-rounded and exciting chapter in the annals of science.On 27 March 1949 Shannon married Mary Elizabeth Moore. They had three sons and one daughter; Robert, James, Andrew Moore, and Margarita. He continued his work showing how Boolean algebra could be used to synthesise and simplify relay switching circuits. He also proved results on colouring the edges of a graph so that no two edges of the same colour meet at a vertex. Another important paper, published in 1949, was Communication theory of secrecy systems.
In 1952 Shannon devised an experiment illustrating the capabilities of telephone relays. He had held a position as a visiting professor of communication sciences and mathematics at the Massachusetts Institute of Technology in 1956, then from 1957 he was appointed to the Faculty there, but remained a consultant with Bell Telephones. In 1958 he became Donner Professor of Science :-
When he returned to MIT in 1958, he continued to threaten corridor-walkers on his unicycle, sometimes augmenting the hazard by juggling. No one was ever sure whether these activities were part of some new breakthrough or whether he just found them amusing. He worked, for example, on a motorised pogo-stick, which he claimed would mean he could abandon the unicycle so feared by his colleagues ...R G Gallager, a colleague who worked at the Massachusetts Institute of Technology, wrote:-
Shannon was the person who saw that the binary digit was the fundamental element in all of communication. That was really his discovery, and from it the whole communications revolution has sprung.His later work looked at ideas in artificial intelligence. He devised chess playing programs and an electronic mouse which could solve maze problems. The chess playing program appeared in the paper Programming a computer for playing chess published in 1950. This proposal led to the first game played by the Los Alamos MANIAC computer in 1956. This was the year that Shannon published a paper showing that a universal Turing machine may be constructed with only two states.
Latterly he felt that the communications revolution, which he had played a major role in starting, was going too far. He wrote:-
Information theory has perhaps ballooned to an importance beyond its actual accomplishments.Marvin Minsky described Shannon as follows:-
Whatever came up, he engaged it with joy, and he attacked it with some surprising resource which might be some new kind of technical concept or a hammer and saw with some scraps of wood. For him, the harder a problem might seem, the better the chance to find something new.He also applied his inventing genius to other areas :-
... he once invented a two-seater version of his unicycle, and it is probably true that no one was anxious to share it with him. A later invention, the unicycle with an off-centre hub, would bring people out into the corridors to watch him as he rode it, bobbing up and down like a duck.Shannon received many honours for his work. Among a long list of awards were the Alfred Nobel American Institute of American Engineers Award in 1940, the National Medal of Science in 1966, the Audio Engineering Society Gold Medal in 1985, and the Kyoto Prize in 1985. He was awarded the Marconi Lifetime Achievement Award by the Guglielmo Marconi International Fellowship Foundation in 2000. It was the first time that organization, known for its annual Fellowship Prize, gave this particular award.
He was afflicted by Alzheimer's disease, and he spent his last few years in a Massachusetts nursing home.
Article by: J J O'Connor and E F Robertson | <urn:uuid:799407c3-7593-49a8-98e6-b548acb40a7c> | 2.828125 | 1,393 | Knowledge Article | Science & Tech. | 42.565338 | 95,511,484 |
|Developer(s)||Rich Felker (dalias) and others|
|Initial release||February 11, 2011|
1.1.19 / February 22, 2018
|Operating system||Linux 2.6 or later|
|Platform||x86, x86 64, ARM, MIPS, Microblaze, PowerPC, powerpc64, x32, OpenRISC, s390x, SuperH|
musl is a C standard library intended for operating systems based on the Linux kernel, released under the MIT License. It was developed by Rich Felker with the goal to write a clean, efficient and standards-conformant libc implementation.
Musl was designed from scratch to allow efficient static linking and to have realtime-quality robustness by avoiding races, internal failures on resource exhaustion and various other bad worst-case behaviors present in existing implementations. The dynamic runtime is a single file with stable ABI allowing race-free updates and the static linking support allows an application to be deployed as a single portable binary without significant size overhead.
- "musl - obsolete versions". musl-libc.org. 2017-10-31. Retrieved 2018-01-14.>
- "Download musl". musl-libc.org. 2018-02-22. Retrieved 2018-03-07.
- Rich Felker et al. (2016-04-29). "COPYRIGHT". Retrieved 2016-09-26.
- "Introduction to musl". 2016-04-21. Retrieved 2016-09-26.
- "Compatibility". wiki.musl-libc.org. 2014-05-27. Retrieved 2016-09-26.
- Fietkau, Felix (2015-06-15). "OpenWrt switches to musl by default". openwrt-devel. Retrieved 2016-09-26.
- README.md on GitHub
- "morpheus:". Retrieved 2018-06-15.
- Official website
- Comparison of C/POSIX standard library implementations for Linux
- Matrix of C/POSIX standard libraries by architecture
- Project:Hardened musl on Gentoo wiki
- Rich Felker held a talk at the Embedded Linux Conference (ELC) 2015: ELC 2015 - Transitioning From uclibc to musl for Embedded Development - Rich Felker, Openwall
|This computer-programming-related article is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:e65a28fe-31bf-49df-9331-cd0f354a13a6> | 2.921875 | 529 | Knowledge Article | Software Dev. | 65.08614 | 95,511,498 |
The Greenland Ice Sheet is losing mass at an accelerating rate due to increased surface melt and flow acceleration in outlet glaciers. Quantifying future dynamic contributions to sea level requires accurate portrayal of outlet glaciers in ice sheet simulations, but to date poor knowledge of subglacial topography and limited model resolution have prevented reproduction of complex spatial patterns of outlet flow. Here we combine a high-resolution ice-sheet model coupled to uniformly applied models of subglacial hydrology and basal sliding, and a new subglacial topography data set to simulate the flow of the Greenland Ice Sheet. Flow patterns of many outlet glaciers are well captured, illustrating fundamental commonalities in outlet glacier flow and highlighting the importance of efforts to map subglacial topography. Success in reproducing present day flow patterns shows the potential for prognostic modelling of ice sheets without the need for spatially varying parameters with uncertain time evolution.
High spatial variability in the flow of the Greenland Ice Sheet is apparent from observations1, and capturing this variability is essential to any modelling effort targeting the future evolution of the Greenland Ice Sheet2, yet projections of ice discharge into the ocean remains a major wild card for twenty first century sea-level projections3,4. Ice flow is nonlinearly related to ice thickness, with small uncertainties in ice thickness potentially leading to large biases in discharge estimates5. Consequently, our ability to reproduce observed flow patterns, and thus ice discharge, is contingent on accurate knowledge of ice thickness; however, limited knowledge of thickness has hindered modelling efforts to date. In Greenland, the NASA airborne mission Operation IceBridge (OIB)6 has added many 1,000 km of radar-derived ice thickness profiles since 2009, nearly doubling the coverage available at that time. To help fill in remaining gaps, mass-conserving interpolation methods7 have been used to derive flow-compatible, high-resolution maps of ice thickness and subglacial topography8. The result has been a substantial improvement in our knowledge of subglacial topography, particularly in the deep channel-feeding outlet glaciers. At the same time, code parallelization, combined with high-performance computing, have begun to make high-resolution ice sheet modelling tractable.
Combining these advances allows us to pursue a set of numerical experiments to investigate whether spatially complex flow patterns in outlet glaciers can now be captured in whole-ice-sheet simulations using only ice-sheet-wide (spatially uniform) parameters, without local ‘tuning’ applied to individual grid cells.
Here we use the Parallel Ice Sheet Model (PISM)9, a computationally efficient, three-dimensional model10,11, coupled with models of subglacial hydrology and basal sliding, to simulate the velocity field of the Greenland Ice Sheet at high resolution (<1 km). We demonstrate that outlet glacier flow can be captured with high fidelity if ice thickness is well constrained and vertical shearing as well as membrane stresses are included in the model (without solving the full-stress configuration), while computing flow from vertical shearing alone and/or using low-resolution ice thickness leads to poor agreement with observations. Overall root mean squared (r.m.s.) velocity differences decrease with increasing model resolution. This indicates that ongoing improvements in the mapping of subglacial topography, together with improvements in modelling resolution, go a long ways towards improved whole-ice-sheet numerical simulations.
Calibration and validation
Using the ice sheet geometry given by ice thickness and subglacial topography from Morlighem et al.8 (data set MO2014), we calculated diagnostic velocity fields with PISM. We calibrated the model at a horizontal grid resolution of 1,500 m by using 15 runs to explore the parameter space defined by three spatially uniform parameters controlling ice dynamics and basal processes, selecting the run with the best fit to observed outlet glacier flow (see Methods and Supplementary Table 1).
We assessed model performance by comparing observed and simulated surface velocities along cross-flow profiles of 29 large (flux ≥∼3 Gt yr−1) outlet glaciers (Fig. 1a, Supplementary Table 2), which account for ∼2/3 of the ice-sheet discharge (∼520 Gt per year in 2008)4. Along these profiles, we sampled remotely sensed12 and modelled surface velocities every 250 m using bilinear interpolation. We quantified the model’s ability to capture the spatial variation in flow structure using the Pearson r correlation coefficient and the r.m.s. difference between observations and simulations along the 29 profiles. The correlation coefficient provides an indication of the model’s ability to capture the velocity variation along a profile (related to the channelization of flow), while the r.m.s. value captures the ability of the model to match the magnitude of the velocity, indicating how well the model reproduces discharge flux of each glacier.
Within the tested parameter space, 9 of 14 calibration experiments are within 25% of the smallest total r.m.s. difference (that is, the r.m.s. difference between observed and simulated velocity profiles summed over all outlet glaciers, see Supplementary Table 3); and all but one median correlation coefficient is larger than 0.74 (Supplementary Table 3). Observed horizontal surface velocities increase from near-zero at ice divides to ∼10 km per year in outlet glaciers, covering many orders of magnitude. This overall pattern is well represented in all calibration runs (Supplementary Fig. 1) where flow arises due to the sum of longitudinal stretching and vertical shearing. For comparison, in a simulation where ice flow is only due to vertical shearing (see Methods), outlet glacier flow is basically absent (Supplementary Fig. 2). This suggests that the spatial variability in flow can be explained to a large degree by the variability in ice thickness if membrane stresses are included.
With the calibrated model we performed simulations over a range of horizontal grid resolutions from 4,500 to 600 m. This allows us to address the impact of model resolution on simulation of flow in outlet glaciers, helping to set limits on the minimum resolution required to capture such flow.
Reproduction of flow pattern at the highest model resolution
Of the 29 analysed outlet glaciers, the flow of 4 is characterized by low-surface slopes and low driving stresses (‘ice-stream’-type), while all other glaciers flow through channels significantly deeper than the surrounding ice (‘isbræ’-type)13. At our highest model resolution (600 m) the calibrated model reproduces the velocity structure of ‘ice-stream’ type glaciers slightly better on our cross profiles (median r=0.93) than ‘isbræ’ type glaciers (median r=0.88). Flow speeds in the transitional zone 100–300 km inland (speeds approximately 20–100 m per year) are generally underestimated (Fig. 1a,b).
Along the cross-flow profiles, simulated flow structure agrees well (r>0.85) with observations for 17 of the 29 glaciers, agrees fairly well for 7 (0.5≤r≤0.85) and agrees poorly (r<0.5) for only 5, with a median of 0.88 (Fig. 1b–f).
Of the 14 fast-flowing marine-terminating glaciers with a well-represented flow structure (r>0.85), the simulated surface speeds of 4 are close to observed speeds (Daugaard–Jensen Gletscher, Narsap Sermia, Sermeq Avannarleq and Ukaasorsuaq), 8 are too low (Helheimgletscher, Jakobshavn Isbræ, Kangerdlugssuaq Gletscher, Kong Oscar Gletscher, Rink Isbræ, Steenstrup Gletscher, Store Gletscher, Sverdrup Gletscher) and the speeds of only 2 (Illulip Sermia and Upernavik Isstrøm C) are too high.
Two glaciers, Ryder Gletscher (r=0.71) and Storstrømmen (r<0), are surge-type glaciers whose flow shows large variations over time due to hydrologically controlled sliding14,15, largely uncoupled from surface slope and ice thickness, which may have led to a reduced fit. In addition, Graulv and the Køge Bugt glaciers have correlation coefficients less than or equal to 0.65, substantially lower than the median (0.88). For these glaciers, Morlighem et al.8 used kriging to derive ice thicknesses away from OIB measurements, while they used mass conserving interpolation techniques7 for all other glaciers, enabled by better OIB measurement coverage. We hypothesize that the poor match between simulated and observed flow for these glaciers results from poorly constrained ice thickness knowledge. While glaciers are rapidly changing, our model is diagnostic and should reflect the flow for the current geometry. Results for other glaciers with large dynamic adjustments, such as Jakobshavn Isbræ, are very encouraging.
Role of model resolution
The impact of poor model resolution on the simulation of outlet glacier flow is illustrated by resampling the MO2014 subglacial topography and ice thickness to a range of model grid spacings (Fig. 2). To quantify the impact of improved model resolution, we performed a linear regression analysis of the r.m.s. velocity difference for each glacier. A simulation at the lowest model resolution (4,500 m) has an r.m.s. velocity difference 42% higher than at 600 m (Fig. 3c). Overall we find that r.m.s. velocity differences decrease with increasing resolution (goodness-of-fit r2=0.95). Sixteen glaciers have statistically significant (P<0.05) improving trends. All but one of these (Humboldt Gletscher) are fast-flow marine-terminating glaciers (mean velocity >200 m yr−1) of the ‘isbræ’-type. Jakobshavn Isbræ, Greenland’s most prolific supplier of ice to the ocean, flows through a <10-km wide subglacial valley grounded well below sea level. A minimum resolution of ∼2 km is needed to resolve the valley geometry sufficiently to reproduce the high (>2 km yr−1) surface velocities (Fig. 2b, Supplementary Fig. 3). ‘Ice-stream’-type glaciers and surge-type glaciers (Ryder Gletscher and Storstrømmen) and ‘isbræ’-type glaciers with subglacial topographies derived by kriging (Graulv, Køge Bugt N and S; Supplementary Figs 3–5) do not benefit from increased resolution.
Role of ice thickness
To assess how much OIB measurements and mass-conserving interpolation methods have improved model simulations, we performed two simulations with an older ice thickness/subglacial topography data set (BA2001)16. The BA2001 data set is posted at 5,000 m, which we resampled to 600 and 4,500 m spacing. For these experiments, the total r.m.s. difference between modelled and observed flow of all 29 outlet glaciers are 49% (600 m) and 57% (4,500 m) higher than with the MO2014 ice thickness data set at 600-m resolution (Fig. 3, Supplementary Table 4). At the same time, the reproduction of the flow structure is substantially better when using the MO2014 data set at a model resolution of 600 m (median correlation coefficient ) than using the BA2001 data set ( and at 600 and 4,500 m model resolution, respectively). High model resolution alone clearly is insufficient to reproduce outlet glacier flow (Supplementary Figs 6–8) Furthermore resampling data sets to resolutions higher than the nominal resolution (for example, resampling the BA2001 data set to 600 m) does not generate physical information that is not already captured by the coarse data. We note that, in some cases, such resampling may produce an apparent improvement. However, this improvement is an artifact of the analysis method (Supplementary Note 1).
Role of flow type
Of Greenland’s 200+ outlet glaciers1, only 4 are ‘ice-stream’-type whereas the rest are ‘isbræ’-type. While our selection of 29 outlet glaciers includes all four ‘ice-stream’-type glaciers, any statistical analysis with only four samples requires caution.
The reproduction of the flow structure of ‘isbræ’-type glaciers at 600 m model resolution is substantially better (median correlation coefficient ) for the MO2014 data set than for BA2001 (0.54) at the same model resolution, as well as at 4,500 m model resolution (0.09). Also the r.m.s. velocity difference is much lower.
Compared to ‘isbræ’-type glaciers, ‘ice-stream’-type glaciers are less sensitive to both model and data set resolution. Furthermore, the total r.m.s. velocity differences of ‘ice-stream’-type glaciers is almost an order of magnitude smaller than for ‘isbræ’-type glaciers (Supplementary Table 4).
The structures of three ‘ice-stream’ type glaciers that are well represented at the highest resolution (79North, Petermann Gletscher and Zachariæ Isstrøm) are well represented at all grid resolutions. The improving trend of ‘ice-stream’-type glaciers is not statistically significant (Fig. 2a). This suggests that all grid resolutions sufficiently capture lateral variations in ice thickness and surface slope, which are typically small in ‘ice-stream’ type glaciers. For ‘ice-stream’-type glaciers accurate knowledge of ice thickness is less crucial to reproduce the flow structure than it is for ‘isbræ’-type glaciers. Nonetheless subglacial topography still needs to be well constrained to properly treat advance and retreat scenarios.
Humboldt Gletscher stands out in all aspects. Located in the northwestern corner of Greenland, the ∼90-km wide ‘ice-stream’ type glacier has a mean velocity <200 m yr−1. Humboldt's simulated flow structure agrees poorly with observations at all resolutions, shows the smallest improving trend, and has the lowest goodness-of-fit (r2=0.63). Simulated basal temperatures for Humboldt are very close to the pressure-adjusted melting point, and depending on grid resolution, basal motion may be activated or not in our simulations. The flow of Humboldt Gletscher is thus very sensitive to grid resolution and model parameters, unlike other glaciers studied. To explain this sensitivity, a more focused study might be warranted, possibly using time-dependent data assimilation and inverse methods such as in refs 17, 18.
The simulations presented in this study portray Greenland’s flow structure in unprecedented detail; most large outlet glaciers considered are well-captured at grid resolutions <1 km. Our results demonstrate that spatial variability in flow can be explained in large part by the spatial variability in ice thickness. We find that inversion of surface properties for individual glaciers is not essential to reproduce the overall flow pattern. Using simple parametrizations of basal motion and subglacial hydrology, we find good agreement between simulated and observed spatial flow patterns while the reproduction of the velocity magnitude requires further improvements, especially in the transitional zone 100–300 km inland (speeds ∼20–100 mper year). Disagreement between observed and simulated speeds may arise from inadequacies in parametrizing basal motion and subglacial hydrology. Also not all heat sources that affect the viscosity of ice are accounted for in our model. For example refreezing of surface meltwater (‘cryo-hydrologic warming’) can soften the ice and enhance flow, which may be relevant in the transitional zone19,20,21,22. Furthermore the ice flux from the interior may be misrepresented because interior ice thickness remains less well characterized, but might be just as important to capture outlet glacier flow downstream. Finally, we calibrated only three parameters and only at the locations of our profiles, which may partly explain the reduced fit in the interior. To further reduce the gap between observations and simulations, future work must elucidate the physics behind the remaining misfit between modelled and measured flow across the spectrum of outlet systems, in the transitional zone and the interior. A quantitative, physically based understanding of the mismatch can then guide future modelling efforts.
Here we have presented diagnostic simulations; future work should address whether the observed temporal variability can be explained by our simple parametrizations or whether more physically based models of subglacial hydrology are needed. Basal motion can be highly variable locally on short (<1 year) time scales23,24,25,26, arising from variations in the hydrological system. Development of adequate models of subglacial hydrology, applicable on an ice sheet wide scale, is still at an early stage (for example, ref. 27). On a regional scale, recent efforts show promise in capturing the seasonal evolution in flow speeds resulting from changes in basal resistance caused by surface meltwater delivery28.
Here we have used surface velocities as our metric of success. It could be argued that ice discharge is a more suitable metric of success. However, ice thickness is subject to larger observational uncertainties than ice velocity, making discharge (the product of ice thickness and vertically averaged horizontal velocities) a weaker metric. We note that our results would look even more favourable if we used flux as a metric, with 20 glaciers showing correlation coefficients exceeding 0.85 (Supplementary Fig. 9), and the fluxes of 6 marine-terminating glaciers being within observational uncertainty.
Clearly, large-scale observational efforts such as OIB improve our ability to model the parts of the system that are responsible for the bulk of the mass flux to the oceans. The simple metrics we introduced here help to quantify the impact of these additional measurements on whole ice-sheet simulations. Ice thickness measurements by many groups are ongoing and OIB, currently scheduled to continue until 2019, is expected to add many line kilometres of measurements by that time. Improvements such as those discussed here for Greenland would also be expected from additional investment in mapping subglacial topography for the Antarctic ice sheet.
Our simulations have implications for efforts targeted at projecting twenty first century sea level rise. IPCC’s Fourth Assessment Report called out the need to resolve the full stress configuration in ice-sheet models to simulate changes in outlet glaciers. Since then, ice sheet models have seen substantial improvements in their representation of flow physics (for example, refs 29, 30). We find that models that resolve both membrane and vertical stress gradients are capable of reproducing the observed flow structure with high fidelity. In regions with large transverse velocity gradients, such as shear margins, the mismatch between observed and simulated flow may be further reduced by resolving additional components of the stress balance.
The large improvements we have attained using only spatially uniform parameters suggest that there is much to be learned about outlet glacier flow from comparing suites of glaciers to each other. By modelling each outlet glacier with the same spatially uniform parameters, modelled flow variations are dependent locally only on the shape of the bed and surface. Discordance with observed velocity, if not due to errors in these shapes, then may reflect departure from the conditions assumed by these uniform parameters. If groups of glaciers that experience similar surface melt and accumulation patterns show similar departures, this would indicate a common response that is not captured by present physics. In this way, it should be possible to limit the degrees of freedom in the model as the parameter space is enhanced to better capture spatial patterns of flow. This type of analysis would not be well bounded or even tractable if locally variable parameters had been used to match the observed flow patterns of each glacier.
Successful prognostic models will have to demonstrate that both spatial and temporal variability in flow can be replicated2; here, we have shown significant progress in the former.
Along cross-profiles of 29 outlet glaciers (Supplementary Table 2) we sample observed and modelled surface velocities every 250 m using bilinear interpolation, and all metrics are then calculated from those profiles. Profiles are drawn roughly perpendicular to observed flow directions, following flightlines whenever possible. Observed surface velocities12 Us represent fall velocities of 2008; we assume that annually-averaged velocities U are 10±5% higher than fall speeds, U=1.1Us (ref. 26).
The flow component normal to the gate is given by U⊥=n·U, where n is the unit normal vector at each gate point such that n·U is positive. We calculate the uncertainty in surface velocities, σ, by adding 0.05U⊥ to the 1-sigma error of the data set, Ue:
Ice sheet model
Simulations are performed with the open-source Parallel Ice Sheet Model (PISM), which is thermomechanically coupled, polythermal, and includes a hybrid stress balance model10,31. The hybrid scheme combines the Shallow Ice Approximation (SIA)32 for vertical deformation and the Shallow Shelf Approximation (SSA)33 for longitudinal stretching. The effective viscosity of glacier ice, η, is given by
where E is the flow enhancement factor, τe is the effective stress, A is the enthalpy-dependent rate factor (softness), and n is the exponent of the power law. The small constant ɛ (units of stress) regularizes the flow law at low effective stress, avoiding the problem of infinite viscosity at zero deviatoric stress.
where τc is the yield stress, q is the pseudoplasticity exponent, and u0=100 m yr−1 is a threshold speed. Here we use a simple model of basal hydrology that connects basal water pressure and the rheology of soft sediments (‘undrained plastic bed’)36. While this model was motivated by observations from Ice Stream B in Antartica37, there is growing evidence of soft sediments beneath the Greenland Ice Sheet38,39,40,41. Furthermore, theoretical work42 suggests that hard beds, that is beds without soft sediments present, behave plastically at high basal water pressure. We assume that yield stress τc is proportional to effective pressure N (‘Mohr-Coulomb criterion’43),
Here δ=0.02 is a lower limit of the effective pressure, expressed as a fraction of overburden pressure, e0 is the void ratio at a reference effective pressure N0, Cc is the coefficient of compressibility of the sediment, W is the effective thickness of water and Wmax is the maximum amount of basal water. We use a non-conserving hydrology model that connects W to the basal melt rate (ref. 37):
where ρw is the density of water and Cd=1 mm yr−1 is a fixed drainage rate.
We prescribe the yield stress as a function of bed elevation44 by prescribing the till friction angle φ as a continuous function of the bed elevation, with φ=5° for bed elevations lower than 700 m below sea-level, φ=40° for bed locations higher than 700 m above sea-level, and changing linearly in between. While the bed elevation dependence is not derived strictly from first principles, outlet glaciers with bed elevations below sea-level have hydrologic systems tied to sea level at the terminus, and so run at high basal water pressure (that is, low effective pressure), and may be underlain by marine sediments45, which are weak46.
To assess the role of this bed elevation dependence, we performed a simulation where the yield stress is only a function of locally derived effective pressure, not dependent on bed elevation. In this simulation, fast flow is apparent in outlet glaciers; however, not of the right structure (Supplementary Figs 10–12). The total (all 29 outlet glaciers) r.m.s. difference is 27% higher than the calibrated simulation, indicating that using an elevation-dependent yield stress provides a much improved match to the flow structure of most investigated glaciers.
The initialization procedure follows closely the ‘flux-corrected paleo-climate’ initialization method in ref. 47. During the last 5,000 years of the initialization we apply a flux-correction method to obtain an ice sheet geometry in closer agreement with measurements47. For computational efficiency grid refinements are made during the initialization procedure. The runs are started on a 18,000 m grid at −125,000 years, then refined from 18,000 to 9,000 m at −25,000 years, to 4,500 m at −5,000 years, to 3,600 m at −1,000 years, to 1,800 m at −500 years, to 1,500 m at −300 years, to 1,200 m at −200 years, and finally to 900 m at −100 years. The vertical model resolution is 20 m.
We calibrate three ice-sheet-wide scalar parameters, the flow enhancement factor E, the exponent of the sliding law q, and the exponent of the flow law for the SSA n, while all other parameters are PISM default. The calibration is performed at 1,500-m grid resolution.
To calculate the velocity field that corresponds to a given parameter combination, one could solve the non-linear system of equations of steady state using the observed geometry and standard direct or iterative solution techniques. Without smoothing applied to the observed geometry, such a velocity field would reflect any inconsistencies between the calculated thermodynamic and hydrological initial state and observations. Instead we attempt to follow the physical transient using a flux correction method47 to iterate towards a geometry that is ‘close’ to the observed geometry and is consistent with the model and the applied forcing. Such a flux correction is used to minimize the difference between the modelled and the observed geometry. All experiments use the enthalpy field from the end of the initialization procedure at the corresponding grid resolution, except for 600-m grid resolution, which starts from the initialized state at 900-m grid resolution. All experiments are run for 100 years, sufficiently long to adjust to a given parameter combination. Flux correction does not respect observed ice thickness perfectly; especially in outlet glaciers near the grounding line, differences may locally exceed 100 m.
First we calibrate E by running the model in SIA-only mode and comparing simulated with observed surface speeds in slow-flowing (<20 m yr−1) areas. The r.m.s. differences between modelled and observed surface speed range from 6 m yr−1 (E=1.5) to 12 m yr−1 (E=3; Supplementary Fig. 13). Except for E=3, all r.m.s. differences are smaller than the observational error of 9 m yr−1. We choose E=1.25 to avoid overestimating the vertical shearing in slow-flowing areas.
Second, we calibrate the hybrid model by tuning the exponent of the pseudoplastic sliding law q, which connects bed-parallel basal shear stress and basal sliding, and the exponent flow law n for the SSA. For the SIA, we choose the default value n=3. To keep the parameter space manageable we test selected pairs of q and n (Supplementary Table 3). Here we use the r.m.s. difference along all profiles as our metric. The r.m.s. differences for all experiments are listed in Supplementary Table 3. By this metric, Experiment 7 with (q, n)=(0.6, 3.25) scores highest. Therefore, all subsequent simulations are performed with (q, n)=(0.6, 3.25).
How to cite this article: Aschwanden, A. et al. Complex greenland outlet glacier flow captured. Nat. Commun. 7:10524 doi: 10.1038/ncomms10524 (2016).
This work was supported by NASA grants No. NNX13AM16G, NNX15AC70G and NNX13AK27G, and by NSF grants PLR-122976 and PLR-0909552. M. Morlighem provided bed topography and ice thickness, E. Rignot and J. Mouginot provided SAR velocities. E. Enderlin provided ice discharge estimates. We thank D. Brinkerhoff, E. Bueler, R. Hock, C. Khroulev, C. Kienholz, J. MacGregor, J. Young and F. Ziemen for providing comments on the manuscript. All simulations were performed at the Arctic Region Supercomputing Center, University of Alaska Fairbanks. Analysis relies entirely on open-source software: numpy (general analysis), matplotlib (plotting), pandas (statistical analysis), netcdf4python (data import/export), gdal (data import/export) and QGIS (mapplane figures).
Supplementary Figures 1-13, Supplementary Tables 1-4, Supplementary Note 1 and Supplementary References. | <urn:uuid:328362e8-98e1-4ca3-8065-7c602b79d829> | 2.703125 | 6,128 | Academic Writing | Science & Tech. | 41.060267 | 95,511,502 |
A prospecting plan is presented to assay near Earth objects (NEO) for their potential to yield rocket fuel. The plan calls out small satellites as the near-term means to achieve low cost surveys and deep subsurface sampling of NEO composition. The water bearing classes of NEO to be considered are limited to those accessible in short time and with small thrusters. These include the water bearing clay objects (phylosilicates) at nearly trivial distances from Earth, and the recently identified water ice objects such as comet ([number sign]4015) 1979 VA. These objects are evaluated as small satellite prospecting and assay vehicle targets.
The 1992 discovery of a water-ice, near-Earth object (NEO) in the space near Earth is evaluated as a source of rocket fuel and life support materials for Earth orbit use. Nuclear thermal rockets using steam propellant are evaluated and suggested. The space geological formation containing such water-rich NEO's is described. An architecture couples near-Earth object fuels (neo-fuel) extraction with use in Earth orbits. Preliminary mass payback analyses show that space tanker systems fueled from space can return in excess of 100 times their launched mass from the NEO, per trip. Preliminary cost estimates indicate neo-fuel costs at Earth orbit can be 3 orders of magnitude below today's cost. A suggested resource verification plan is presented. | <urn:uuid:8d4dbf6b-7b48-4605-a15b-d71464728598> | 2.890625 | 277 | Knowledge Article | Science & Tech. | 41.35368 | 95,511,536 |
In this paper, an intelligent approach is proposed to optimize the orientation of continuous solar tracking systems on cloudy days. Considering the weather case, the direct sunlight is more important than the diffuse radiation in case of clear sky. Thus, the panel is always pointed towards the sun. In case of an overcast sky, the solar beam is close to zero, and the panel is placed horizontally to receive the maximum of diffuse radiation. Under partly covered conditions, the panel must be pointed towards the source that emits the maximum of solar energy and it may be anywhere in the sky dome. Thus, the idea of our approach is to analyze the images, captured by ground-based sky camera system, in order to detect the zone in the sky dome which is considered as the optimal source of energy under cloudy conditions. The proposed approach is implemented using experimental setup developed at PROMES-CNRS laboratory in Perpignan city (France). Under overcast conditions, the results were very satisfactory, and the intelligent approach has provided efficiency gains of up to 9% relative to conventional continuous sun tracking systems.
The use of alternative energy sources to meet energy demand reduces environmental damage. To diversify an energy matrix and to minimize global warming, a solar energy is gaining space, being an important source of renewable energy, and its potential depends on the climatic conditions of the region. Brazil presents a great solar potential for a generation of electric energy, so the knowledge of solar radiation and its characteristics are fundamental for the study of energy use. Due to the above reasons, this article aims to verify the climatic variability corresponding to the variations in solar radiation anomalies, in the face of climate change scenarios. The data used in this research are part of the Intercomparison of Interconnected Models, Phase 5 (CMIP5), which contributed to the preparation of the fifth IPCC-AR5 report. The solar radiation data were extracted from The Australian Community Climate and Earth System Simulator (ACCESS) model using the RCP 4.5 and RCP 8.5 scenarios that represent an intermediate structure and a pessimistic framework, the latter being the most worrisome in all cases. In order to allow the use of solar radiation as a source of energy in a given location and/or region, it is important, first, to determine its availability, thus justifying the importance of the study. The results pointed out, for the 75-year period (2026-2100), based on a pessimistic scenario, indicate a drop in solar radiation of the approximately 12% in the eastern region of Rio Grande do Sul. Factors that influence the pessimistic prospects of this scenario should be better observed by the responsible authorities, since they can affect the possibility to produce electricity from solar radiation.
Natural ventilation systems have increasingly been the subject of research due to rising energetic consumption within the building sector and increased environmental awareness. In the last two decades, the mounting concern of greenhouse gas emissions and the need for an efficient passive ventilation system have driven the development of new alternative passive technologies such as ventilated facades, trombe walls or solar chimneys. The objective of the study is the assessment of PCM panels in an in situ solar chimney for the establishment of a numerical model. The PCM integrated solar chimney shows slight performance improvement in terms of mass flow rate and external temperature and outlet temperature difference. An increase of 11.3659 m3/h can be observed during low wind speed periods. Additionally, the surface temperature across the chimney goes beyond 45 °C and allows the activation of PCM panels.
The integrated solar combined cycle (ISCC) system has a series of advantages such as increasing the system power generation, reducing the cost of solar power generation, less pollutant and CO2 emission. In this paper, the parabolic trough collectors with direct steam generation (DSG) technology are considered to replace the heat load of heating surfaces in heat regenerator steam generation (HRSG) of a conventional natural gas combined cycle (NGCC) system containing a PG9351FA gas turbine and a triple pressure HRSG with reheat. The detailed model of the NGCC system is built in ASPEN PLUS software and the parabolic trough collectors with DSG technology is modeled in EBSILON software. ISCC-DSG systems with the replacement of single, two, three and four heating surfaces are studied in this paper. Results show that: (1) the ISCC-DSG systems with the replacement heat load of HPB, HPB+LPE, HPE2+HPB+HPS, HPE1+HPE2+ HPB+HPS are the best integration schemes when single, two, three and four stages of heating surfaces are partly replaced by the parabolic trough solar energy collectors with DSG technology. (2) Both the changes of feed water flow and the heat load of the heating surfaces in ISCC-DSG systems with the replacement of multi-stage heating surfaces are smaller than those in ISCC-DSG systems with the replacement of single heating surface. (3) ISCC-DSG systems with the replacement of HPB+LPE heating surfaces can increase the solar power output significantly. (4) The ISCC-DSG systems with the replacement of HPB heating surfaces has the highest solar-thermal-to-electricity efficiency (47.45%) and the solar radiation energy-to-electricity efficiency (30.37%), as well as the highest exergy efficiency of solar field (33.61%).
Water is one of the most important and vulnerable natural resources due to human activities and climate change. Water-level continues declining year after year and it is primarily caused by sustained, extensive, and traditional usage methods. Improving water utilization becomes an urgent issue in order satisfy the increasing population needs. Desalination of seawater or brackish water could help in increasing water potential. However, a cost-effective desalination process is required. The most appropriate method for performing this desalination is solar-driven distillation, given its simplicity, low cost and especially the availability of the solar energy source. The main objective of this paper is to demonstrate the influence of coupling integrated basin plate by fins with preheating by solar collector on the performance of solar still. The energy balance equations for the various elements of the solar still are introduced. A numerical example is used to show the efficiency of the proposed solution.
Landfills present long-term threats to soil, air, groundwater and surface water due to the formation of greenhouse gases (methane gas and carbon dioxide) and leachate from decomposing garbage. The composition of leachate differs from site to site and also within the landfill. The leachates alter with time (from weeks to years) since the landfilled waste is biologically highly active and their composition varies. Mainly, the composition of the leachate depends on factors such as characteristics of the waste, the moisture content, climatic conditions, degree of compaction and the age of the landfill. Therefore, the leachate composition cannot be generalized and the traditional treatment models should be adapted in each case. Although leachate composition is highly variable, what different leachates have in common is hazardous constituents and their potential eco-toxicological effects on human health and on terrestrial ecosystems. Since leachate has distinct compositions, each landfill or dumping site would represent a different type of risk on its environment. Nevertheless, leachates consist always of high organic concentration, conductivity, heavy metals and ammonia nitrogen. Leachate could affect the current and future quality of water bodies due to uncontrolled infiltrations. Therefore, control and treatment of leachate is one of the biggest issues in urban solid waste treatment plants and landfills design and management. This work presents a treatment model that will be carried out "in-situ" using a cost-effective novel technology that combines solar evaporation/condensation plus forward osmosis. The plant is powered by renewable energies (solar energy, biomass and residual heat), which will minimize the carbon footprint of the process. The final effluent quality is very high, allowing reuse (preferred) or discharge into watercourses. In the particular case of this work, the final effluents will be reused for cleaning and gardening purposes. A minority semi-solid residual stream is also generated in the process. Due to its special composition (rich in metals and inorganic elements), this stream will be valorized in ceramic industries to improve the final products characteristics.
An experimental study was conducted for ascertaining electrical and thermal characteristics of a pair of photovoltaic (PV) modules integrated with solar wall of an outdoor room. A pre-fabricated outdoor room was setup for conducting outdoor experiments on a PV solar wall with passive and active ventilation through the outdoor room. The selective operating conditions for glass coated PV modules were utilized for establishing their electrical and thermal characteristics. The PV solar wall was made up of glass coated PV modules, a ventilated air column, and an insulating layer of polystyrene filled plywood board. The measurements collected were currents, voltages, electric power, air velocities, temperatures, solar intensities, and thermal time constant. The results have demonstrated that: i) a PV solar wall installed on a wooden frame was of more heat generating capacity in comparison to a window glass or a standalone PV module; ii) generation of electric power was affected with operation of vertical PV solar wall; iii) electrical and thermal characteristics were not significantly affected by heat and thermal storage losses; and iv) combined heat and electricity generation were function of volume of thermal and electrical resistances developed across PV solar wall. Finally, a comparison of temperature plots of passive and active ventilation envisaged that fan pressure was necessary to avoid overheating of the PV solar wall. The active ventilation was necessary to avoid over-heating of the PV solar wall and to maintain adequate ventilation of room under mild climate conditions.
This paper presents a paradigm for characterization and checking of human noise behavior. The definitions of ‘Noise’ and ‘Noise Behavior’ are devised. The concept of characterization and examining of Noise Behavior is obtained from the proposed paradigm of Psychoacoustics. The measurement of human noise behavior is discussed through definitions of noise sources and noise measurements. The noise sources, noise measurement equations and noise filters are further illustrated through examples. The theory and significance of solar energy acoustics is presented for life and its activities. Human comfort and health are correlated with human brain through physiological responses and noise protection. Examples of heat stress, intense heat, sweating and evaporation are also enumerated.
More than half of the urban population in Romania lives today in residential buildings made out of large prefabricated reinforced concrete panels. Since their initial design was made in the 1960’s, these housing units are now being technically and morally outdated, consuming large amounts of energy for heating, cooling, ventilation and lighting, while failing to meet the needs of the contemporary life-style. Due to their widespread use, the design of a system that improves their energy efficiency would have a real impact, not only on the energy consumption of the residential sector, but also on the quality of life that it offers. Furthermore, with the transition of today’s existing power grid to a “smart grid”, buildings could become an active element for future electricity networks by contributing in micro-generation and energy storage. One of the most addressed issues today is to find locally adapted strategies that can be applied considering the 20-20-20 EU policy criteria and to offer sustainable and innovative solutions for the cost-optimal energy performance of buildings adapted on the existing local market. This paper presents a possible adaptive design scenario towards sustainable retrofitting of these housing units. The apartments are transformed in order to meet the current living requirements and additional extensions are placed on top of the building, replacing the unused roof space, acting not only as housing units, but as active solar energy collection systems. An adaptive building envelope is ensured in order to achieve overall air-tightness and an elevator system is introduced to facilitate access to the upper levels.
Solar energy, since it is available every day, is seen as one of the most valuable renewable energy resources. Thus, the energy of sun should be efficiently used in various applications. The most known applications that use solar energy are heating water and spaces. High efficiency solar collectors need appropriate selective surfaces to absorb the heat. Selective surfaces (Selektif-Sera) used in this study are applied to flat collectors, which are produced by a roll to roll cost effective coating of nano nickel layers, developed in Selektif Teknoloji Co. Inc. Efficiency of flat collectors using Selektif-Sera absorbers are calculated in collaboration with Institute for Solar Technik Rapperswil, Switzerland. The main cause of high energy consumption in industry is mostly caused from low temperature level processes. There is considerable effort in research to minimize the energy use by renewable energy sources such as solar energy. A feasibility study will be presented to obtain the potential of solar thermal energy utilization in the textile industry using these solar collectors. For the feasibility calculations presented in this study, textile dyeing and finishing factory located at Kahramanmaras is selected since the geographic location was an important factor. Kahramanmaras is located in the south east part of Turkey thus has a great potential to have solar illumination much longer. It was observed that, the collector area is limited by the available area in the factory, thus a hybrid heating generating system (lignite/solar thermal) was preferred in the calculations of this study to be more realistic. During the feasibility work, the calculations took into account the preheating process, where well waters heated from 15 °C to 30-40 °C by using the hot waters in heat exchangers. Then the preheated water was heated again by high efficiency solar collectors. Economic comparison between the lignite use and solar thermal collector use was provided to determine the optimal system that can be used efficiently. The optimum design of solar thermal systems was studied depending on the optimum collector area. It was found that the solar thermal system is more economic and efficient than the merely lignite use. Return on investment time is calculated as 5.15 years.
Solar energy is available abundantly in the world, but it is not continuous and its intensity also varies with time. Due to above reason the acceptability and reliability of solar based thermal system is lower than conventional systems. A properly designed heat storage system increases the reliability of solar thermal systems by bridging the gap between the energy demand and availability. In the present work, two dimensional numerical simulation of the melting of heat storage material is presented in the horizontal annulus of double pipe latent heat storage system. Longitudinal fins were used as a thermal conductivity enhancement. Paraffin wax was used as a heat-storage or phase change material (PCM). Constant wall temperature is applied to heat transfer tube. Presented two-dimensional numerical analysis shows the movement of melting front in the finned cylindrical annulus for analyzing the thermal behavior of the system during melting.
This paper deals with the optimum tilt angle for the solar collector in order to collect the maximum solar radiation. The optimum angle for tilted surfaces varying from 0◦ to 90◦ in steps of 1◦ was computed. In present study, a theoretical model is used to predict the global solar radiation on a tilted surface and to obtain the optimum tilt angle for a solar collector in Bursa, Turkey. Global solar energy radiation on the solar collector surface with an optimum tilt angle is calculated for specific periods. It is determined that the optimum slope angle varies between 0◦ (June) and 59◦ (December) throughout the year. In winter (December, January, and February) the tilt should be 55◦, in spring (March, April, and May) 19.6◦, in summer (June, July, and August) 5.6◦, and in autumn (September, October, and November) 44.3◦. The yearly average of this value was obtained to be 31.1◦ and this would be the optimum fixed slope throughout the year.
To provide an efficient solar generation system, the embodiment design of a two axis solar tracker for an array of photovoltaic (PV) panels destiny to supply the power demand on off-the-grid areas was developed. Photovoltaic cells have high costs in relation to t low efficiency; and while a lot of research and investment has been made to increases its efficiency a few points, there is a profitable solution that increases by 30-40% the annual power production: two axis solar trackers. A solar tracker is a device that supports a load in a perpendicular position toward the sun during daylight. Mounted on solar trackers, the solar panels remain perpendicular to the incoming sunlight at day and seasons so the maximum amount of energy is outputted. Through a preview research done it was justified why the generation of solar energy through photovoltaic panels mounted on dual axis structures is an attractive solution to bring electricity to remote off-the-grid areas. The work results are the embodiment design of an azimuth-altitude solar tracker to guide an array of photovoltaic panels based on a specific design methodology. The designed solar tracker is mounted on a pedestal that uses two slewing drives‚ with a nominal torque of 1950 Nm‚ to move a solar array that provides 3720 W from 12 PV panels.
Solar thermal cooling system was installed on Mechanical Research Center (MRC) Building that is located in Universitas Indonesia, Depok, Indonesia. It is the first cooling system in Indonesia that utilizes solar energy as energy input combined with natural gas; therefore, the control system must be appropriated with the climates. In order to stabilize the cooling capacity and also to maximize the use of solar energy, the system applies some controllers. Constant flow rate and on/off controller are applied for the hot water, chilled water and cooling water pumps. The hot water circulated by pump when the solar radiation is over than 400W/m2, and the chilled water is continually circulated by pump and its temperature is kept constant 7 °C by absorption chiller. The cooling water is also continually circulated until the outlet temperature of cooling tower below than 27 oC. Furthermore, the three-way valve is used to control the hot water for generate vapor on absorption chiller. The system performance using that control system is shown in this study results.
Per capita energy usage in any country is exponentially increasing with their development. As a result, the country’s dependence on the fossil fuels for energy generation is also increasing tremendously creating economic and environmental concerns. Tropical countries receive considerable amount of solar radiation throughout the year, use of solar energy with different energy storage and conversion methodologies is a viable solution to minimize the ever increasing demand for the depleting fossil fuels. Salinity gradient solar pond is one such solar energy application. This paper reports the characteristics and performance of a thermally insulated, experimental salinity-gradient solar pond, built at the premises of the University of Kelaniya, Sri Lanka. Particular stress is given to the behavior of the evolution of the three layer structure exist at the stable state of a salinity gradient solar pond over a long period of time, under different environmental conditions. The operational procedures required to maintain the long term thermal stability are also reported in this article.
The tremendous increase in the population of the world creates the immediate need for the energy resources. All the people in the world need the sustainable energy resources which have low costs. Solar energy is appraised as one of the main energy resources in warm countries. The areas in the west of India like Rajasthan, Gujarat, etc. are immensely rich in solar energy resources. This paper deals with the development of dual axis solar tracker using Arduino board. Depending on the astronomical estimates of the sun from the GPS and sensor image processing outcomes, a methodology is proposed to locate the position of the sun to obtain the maximum solar energy. Based on the outcomes, the solar tracking system figures out whether to use image processing outcomes or astronomical estimates to attain the maximum efficiency of the solar panel. Finally, the experimental values obtained from the solar tracker for both the sunny and the rainy days are being tabulated.
The purpose of this paper is to present an active solar energy system to supply heating demands of the teaching staff dormitory of the Islamic Azad University of Ramhormoz. The design takes into account the solar radiations and climate data of Ramhormoz town and is based on the daily warm water consumption for health demands of 450 residents of the dormitory, which is equal to 27000 lit of 50-C° water, and building heating requirements with an area of 3500 m² well-protected by heatproof materials. First, heating demands of the building were calculated, then a hybrid system made up of solar and fossil energies was developed and finally, the design was economically evaluated. Since there is only roof space for using 110 flat solar water heaters, the calculations were made to hybridize solar water heating system with heat pumping system in which solar energy contributes 67% of the heat generated. According to calculations, the net present value “N.P.V.” of revenue stream exceeds “N.P.V.” of cash paid off in this project over three years, which makes economically quite promising. The return of investment and payback period of the project is 4 years. Also, the internal rate of return (IRR) of the project was 25%, which exceeds bank rate of interest in Iran and emphasizes the desirability of the project.
Temperature effect on the performance of a photovoltaic module is one of the main concerns that face this renewable energy, especially in hot arid region, e.g. United Arab Emirates. Overheating of the PV modules reduces the open circuit voltage and the efficiency of the modules dramatically. In this work, water-cooling is developed to enhance the performance of PV modules. Different scenarios are tested under UAE weather conditions: front, back and double cooling. A spraying system is used for the front cooling whether a direct contact water system is used for the back cooling. The experimental results are compared to non-cooling module and the performance of the PV module is determined for different situations. The experimental results show that the front cooling is more effective than the back cooling and may decrease the temperature of the PV module significantly. | <urn:uuid:b215e98d-5ab6-491c-8c27-f471558350a8> | 3.140625 | 4,602 | Content Listing | Science & Tech. | 25.854371 | 95,511,555 |
by Carlos Pedro Gonçalves
Below is a video of a simulation of the quantum game of life, implemented in Netlogo.
Following the previous blog post on this game, each cell (patch) can be in a vacuum state, or it can become punctured by a qubit state.
In the video, the grey cells correspond to the vacuum states that may potentially become occupied by a qubit state Q> = a0>+b1>, while the black and white cells have become occupied (in act) by a qubit state. Each color corresponding to one of the two basis states of the qubit, that is, white corresponds to 0> and black corresponds to 1>.
The actualization of each of the two qubit computational basis states occurs through a probabilistic process since there is decoherence in the qubit histories. The model works with two gate rules, a simple Haddamard rule, and a chaotic rule that exemplifies path dependent quantum computation. The video above uses path dependent quantum computation, in the dynamics of creation and anihilation as well as in the qubit information dynamics.
The video is also available at:
Ad Deum... - Source: By © Jérémie Silvestro / Wikimedia Commons, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=59393959 *quid est ergo tempus? (Augus...
6 days ago | <urn:uuid:f776e863-0dcb-4641-8691-caff9f8b1ca6> | 2.59375 | 308 | Personal Blog | Science & Tech. | 54.243699 | 95,511,567 |
Owing to habitat conversion and conflict with humans, many carnivores are of conservation concern. Because of their elusive nature, camera trapping is a standard tool for studying carnivores. In many vertebrates, sex-specific differences in movements - and therefore detection by cameras - are likely. We used camera trapping data and spatially explicit sex-specific capture-recapture models to estimate jaguar density in Emas National Park in the central Brazilian Cerrado grassland, an ecological hotspot of international importance. Our spatially explicit model considered differences in movements and trap encounter rate between genders and the location of camera traps (on/off road). We compared results with estimates from a sex-specific non-spatial capture-recapture model. The spatial model estimated a density of 0.29 jaguars 100km-2and showed that males moved larger distances and had higher trap encounter rates than females. Encounter rates with off-road traps were one tenth of those for on-road traps. In the non-spatial model, males had a higher capture probability than females; density was estimated at 0.62 individuals 100km-2. The non-spatial model likely overestimated density because it did not adequately account for animal movements. The spatial model probably underestimated density because it assumed a uniform distribution of jaguars within and outside the reserve. Overall, the spatial model is preferable because it explicitly considers animal movements and allows incorporating site-specific and individual covariates. With both methods, jaguar density was lower than reported from most other study sites. For rare species such as grassland jaguars, spatially explicit capture-recapture models present an important advance for informed conservation planning. © 2010 Elsevier Ltd.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:8ac5a946-54eb-4302-b65b-038bbc5f47a3> | 2.84375 | 371 | Academic Writing | Science & Tech. | 15.614445 | 95,511,586 |
Humans depend on the ocean for food, medicine, transportation and recreation, yet little is known about how these vast ecosystems spanning 70 percent of the Earth's surface are functioning and changing. Following a workshop sponsored by U.S. federal agencies in 2010, researchers at eight institutions have proposed a blueprint for establishing a cooperative marine biodiversity observation network to monitor trends in marine ecosystem health and the distribution and abundance of oceanic life. The research will appear online in BioScience Thursday and in the journal's May print issue.
Biodiversity observation networks are indispensible tools, allowing scientists to follow and predict ecosystem changes to facilitate proactive responses to environmental pressures, said study co-author Gustav Paulay, invertebrate zoology curator at the Florida Museum of Natural History on the UF campus.
"Biodiversity is important not only because it's what the natural world is about, but also because tracking it tells you how healthy things are," Paulay said. "As an indicator of ecosystem health and resilience, biodiversity is key for sustaining oceans that face accelerating environmental change."
Experts determined a national marine biodiversity observation network could be established using existing technology within five years with appropriate funding and collaboration, but the effort requires strong leadership to integrate all the necessary elements, Paulay said. The study provides a series of recommendations, including coordination of existing efforts, digitization of historical data -- including vast museum collections – and establishment of regional centers to process and identify specimens.
"Tracking diversity is not just about tracking fish, or whales, or corals, but everything," Paulay said. "To date, there have been few attempts to track biodiversity broadly in the ocean."
From tiny phytoplankton and massive marine mammals to awe-inspiring sea dragons and ancient reefs, every element is important for healthy ecosystems, Paulay said.
Outside the U.S., efforts to create a marine biodiversity observation network have begun regionally in New Zealand and the European Union. The Smithsonian Institution also launched the first worldwide network of coastal field sites in 2012, a long-term project to monitor the ocean's coastal ecosystems.
Jim Carlton, a professor at Williams College in Massachusetts and director of the Maritime Studies Program of Williams College and Mystic Seaport, said the concept of a marine network is critical because elements are inter-related, from water quality and issues with fisheries to the regular arrival of new invasive species.
"It's rather amazing that in 2013, we don't have a well-established marine biodiversity network -- how could we not?" said Carlton, who is not involved with the study. "All coasts around the world are changing and we have a remarkably poor understanding about the extent of that change in many areas."
People are more dependent on oceans than they may realize, and without a coordinated network, researchers will not know how to manage these ecosystems, he said.
"The oceans are feeding hundreds of millions of people, they control the Earth's climate, 90 percent of all world goods travel on the ocean and most people in the world live within 100 miles of the sea," Carlton said. "For recreation, we rely on the fact that we can go to a beach and not get sick. We depend upon a huge amount of these resources in ways that we often don't know, but it really means maintaining the health of the ocean."
Divers have witnessed the effects of climate change most clearly on coral reefs, whose delicate ecology is highly sensitive to changes in maximum ocean temperatures, Paulay said.
"The scale of change was driven home to me in Palau in 1998, during a survey soon after the 1998 Pacific-wide warming event," Paulay said. "Palau is one of the gems of the world in terms of marine environments and reef diversity. When we returned to sites that once had acre upon acre of vibrant staghorn and bottlebrush corals covering the bottom, we found but a desert of dead skeletons -- mortality was virtually 100 percent."
Study co-authors include Emmett Duffy of the College of William and Mary, Linda Amaral-Zettler of the Marine Biological Laboratory in Woods Hole, Mass., Daphne Fautin of the University of Kansas, Tatiana Rynearson of the University of Rhode Island, Heidi Sosik of the Woods Hole Oceanographic Institution, and John Stachowicz of the University of California, Davis.Writer: Danielle Torrent, email@example.com
Gustav Paulay | 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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20.07.2018 | Materials Sciences | <urn:uuid:49eaf1d8-f3fb-481a-a08a-542f73411347> | 3.328125 | 1,497 | Content Listing | Science & Tech. | 32.874402 | 95,511,602 |
If you’ve come across a rock that looks positively out-of-this-world, there’s a possibility it may be a meteorite. Although meteorites are relatively rare on Earth, they’re not impossible to find in the wild. However, you’ll want to make sure your find is indeed a stony or iron rock of cosmic origin and not a piece of ordinary terrestrial material. By checking for common visual and physical markers of a meteorite, you can determine whether the rock you’ve found is actually extraterrestrial in origin.
Part One of Two:
Looking for Visual IdentifiersEdit
1Discern if the rock is black or rusty brown. If the rock you’ve found is a freshly fallen meteorite, it will be black and shiny as a result of having burned through the atmosphere. After a long time spent on Earth, however, the iron metal in the meteorite will turn to rust, leaving the meteorite a rusty brown.
- This rusting starts out as small red and orange spots on the surface of the meteorite that slowly expand to cover more and more of the rock. You may still be able to see the black crust even if part of it has begun to rust.
- The meteorite may be black in color but with slight variations (e.g., steely bluish black). However, if the rock you’ve found isn’t at all close to black or brown in color, then it is not a meteorite.
2Confirm that the rock has an irregular shape. Contrary to what you might expect, most meteorites are not round. Instead, they are typically quite irregular, with sides of varying size and shape. Although some meteorites may develop a conical shape, most will not appear aerodynamic once they land.
- Although irregular in shape, most meteorites will have edges that are rounded rather than sharp.
- If the rock you’ve found is relatively normal in shape, or is round like a ball, it may still be a meteorite. However, the vast majority of meteorites are irregular in shape.
3Determine whether the rock has a fusion crust. As rocks pass through the Earth’s atmosphere, their surfaces begin to melt and air pressure forces the molten material back, leaving a featureless, melt-like surface called a fusion crust. If your rock’s surface looks like it has melted and shifted, it may be a meteorite.
- A fusion crust will most likely be smooth and featureless, though it may also include ripple marks and “droplets” where molten stone had moved and resolidified.
- If your rock does not have a fusion crust, it is most likely not a meteorite.
- The fusion crust may look like a black eggshell coating the rock.
- Rocks in the desert will sometimes develop a shiny black exterior that looks similar to fusion crust. If you found your rock in a desert environment, consider whether its black surface might be desert varnish.
4Check for flow lines where the surface may have melted. Flow lines are small streaks on the fusion crust from when the crust was molten and was forced backwards. If your rock has a crust-like surface with small streak lines across it, there’s a good chance it’s a meteorite.
- Flow lines may be small or not immediately apparent to the naked eye, as the lines can be broken or not completely straight. Use a magnifying glass and a discerning eye when looking for flow lines on the surface of a rock.
5Identify any pits and depressions on the rock’s surface. Although the surface of a meteorite is generally featureless, it may also include shallow pits and deep cavities that resemble thumbprints. Look for these on your rock to determine both if it’s a meteorite and what type of meteorite it is.
- Iron meteorites are particularly susceptible to irregular melting and will have deeper, more defined cavities, whereas stony meteorites may have craters that are smooth like the rock’s surface.
- These indentations are technically known as “regmaglypts,” though most people who work with meteorites will suffice to call them “thumbprints.”
6Make sure the rock isn’t porous or full of holes. Although craters and cavities on the surface may indicate that your rock is a meteorite, no meteorite has holes in its interior. Meteorites are dense pieces of solid rock; if the rock you’ve found is porous or bubbly in appearance, it’s unfortunately not a meteorite.
- If the rock you’ve found has holes in the surface, or appears “bubbly” as if it was once molten, it is definitely not a meteorite.
- Slag from industrial processes is often confused for meteorites, although slag has a porous surface. Other commonly mistaken types of rock include lava rocks and black limestone rocks.
- If you’re having trouble discerning between holes and regmaglypts, it may be useful to view side-by-side comparisons of these features online to learn how to spot the difference.
Part Two of Two:
Testing the Rock’s Physical PropertiesEdit
1Calculate the rock’s density if it feels heavier than normal. Meteorites are solid pieces of rock that are usually densely packed with metal. If the rock you’ve found looks like a meteorite, compare it to other rocks to ensure it’s relatively heavy, then calculate its density to determine if it’s a meteorite.
- You can calculate the density of the potential meteorite by dividing its weight by its volume. If a rock has a calculated density higher than 3 units, it is much more likely to be a meteorite.
2Use a magnet to see whether the rock is magnetic. Nearly all meteorites are at least somewhat magnetic, even if only weakly. This is due to the high concentration in most meteorites of iron and nickel, which are magnetic. If a magnet is not attracted to your rock, it’s almost certainly not a meteorite.
- Because many terrestrial rocks are also magnetic, the magnet test will not definitively prove your rock is a meteorite. However, failing to pass the magnet test is a very strong indication that your rock is probably not a meteorite.
- An iron meteorite will be much more magnetic than a stone meteorite and many will be strong enough to interfere with a compass held close to it.
3Scratch the rock against unglazed ceramic to see if it leaves a streak. A streak test is a good way to test your rock to rule out terrestrial materials. Scrape your rock against the unglazed side of a ceramic tile; if it leaves any streak other than a weak grayish one, it is not a meteorite.
- For an unglazed ceramic tile, you can use the unfinished bottom of a bathroom or kitchen tile, the unglazed bottom of a ceramic coffee mug, or the inside of a toilet tank cover.
- Hematite and magnetite rocks are commonly mistaken for meteorites. Hematite rocks leave a red streak, while magnetite rocks leave a dark gray streak, indicating that they are not meteorites.
- Keep in mind that many terrestrial rocks also do not leave streaks; thus, while the streak test can rule out hematite and magnetite, it will not definitively prove your rock is a meteorite on its own.
4File the surface of the rock and look for shiny metal flakes. Most meteorites contain metal that is visibly shiny under the surface of the fusion crust. Use a diamond file to file a corner of the rock and check the interior for telltale metals on the inside.
- You’ll need a diamond file to ground down the surface of a meteorite. The filing process will also take some time and a good bit of effort. If you’re unable to do this on your own, you can take it into a laboratory for specialist testing.
- If the interior of the rock is plain, it is most likely not a meteorite.
5Inspect the inside of the rock for small balls of stony material. Most meteorites that fall to Earth are of the type to have small round masses on the inside known as chondrules. These may look like smaller rocks and will vary in size, shape, and color.
- Although chondrules are generally located in the interiors of meteorites, weather erosion may cause them to be visible on the surface of meteorites that have been exposed to the elements for a sufficient amount of time.
- In most cases, you will need to break open the meteorite to check for chondrules.
How do I contact an expert that can help me determine whether my rock is a meteorite?Answered by wikiHow Contributor
- You should look into any website your state may have, or try contacting geology professors at any local colleges/universities. If all else fails, look for nearby scientific laboratories that study meteorites or other rocks.
Can lunar meteorites weigh more than 9 pounds?Answered by wikiHow Contributor
- Yes, they can. The heaviest lunar meteorite was "Big Muley," sample number 61016, later named in honor of Professor Muehlberger by Charlie Duke. It weighs 25.8 earth pounds (11.7 kilograms), but only 4.3 moon pounds (1.95 kilograms).
What if it has a metallic color after scratched?
There are Iron stones, couldn't it be mistaken for a meteorite if using a magnet?
How do I tell if the rock I found might be a meteorite and who would I contact about it?
Do meteorites have bubbles?
How can I tell if my rock is a meteorite?
- There are plenty of good books and websites out there. Educate yourself.
- Your chances of finding a real meteorite are very small. If you want to find one, deserts are the best places to look.
- Meteorites do have bubbles and they are called vesicles. All lunar meteorites are vesicular. Stony and iron meteorites do not have bubbles on the inside. Some stony meteorites have air bubbles on the outside.
- Because meteorites tend to have higher concentrations of nickel than terrestrial rocks, you can use a nickel test to determine whether your rock is a meteorite or not. This test can be done at any meteorite testing laboratory and will be more definitive than most of the tests above. | <urn:uuid:9bdf833a-1d91-4da2-a63b-0e63b60288bd> | 3.390625 | 2,224 | Tutorial | Science & Tech. | 50.165964 | 95,511,618 |
Kepler is a space observatory launched by NASA to discover Earth-like planets orbiting other stars. The spacecraft, named in honor of the 17th-century German astronomer Johannes Kepler, was launched on 7 March 2009. It has been active for 9 years, 4 months and 15 days as of July 22, 2018.
The Kepler mission is "specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets". A photometer continually monitors the brightness of over 145,000 main sequence stars in a fixed field of view. This data is transmitted to Earth, then analyzed. The aim is to find periodic dimming caused by extrasolar planets which cross in front of their host star. As of January 2013, there are a total of 2,740 candidates.
Kepler is part of NASA's Discovery Program of relatively low-cost primary science missions. The telescope's construction and initial operation were managed by NASA's Jet Propulsion Laboratory. To start with, the mission lifetime was 3.5 years. In 2012, this was extended to 2016, partly due to difficulties in processing and analyzing the huge volume of data collected by the spacecraft.
Kepler retires[change | change source]
The Kepler space telescope has had to give up its planet-hunting mission because its pointing system has problems which the engineers cannot fix.
References[change | change source]
- Koch, David; Gould, Alan (2009). "Kepler Mission". NASA. Retrieved 2009-03-14.
- DeVore, Edna (2008). "Closing in on Extrasolar Earths". SPACE.com. Retrieved 2009-03-14. External link in
- NASA Staff. "Kepler Launch". NASA. Retrieved 2009-09-18.
- Time since launch.
- NASA Staff. "Kepler Mission/QuickGuide". NASA. Retrieved 2011-04-20.
- AAS Staff. "Meeting Program and block schedule". American Astronomical Society. Retrieved 2011-04-20. – click the itinerary builder to get to the abstract of "Kepler planet detection mission: Introduction and first results".
- News (2012). "NASA approves Kepler mission extension". kepler.nasa.gov.
- "NASA extends planet-hunting Kepler mission through 2016". Space.com. 2012. Retrieved 2012-05-02.
- NASA's Kepler mission discovers 461 new planet candidates
- BBC Staff (2009). "Nasa launches Earth hunter probe". BBC News. Retrieved 2009-03-14.
- Stephen Clark (2012). "Kepler's exoplanet survey jeopardized by two issues". Spaceflight Now. Retrieved 17 October 2012.
- Kepler: Nasa retires prolific telescope from planet-hunting duties. BBC News Science & Environment, 2013. | <urn:uuid:35a8e8cf-a68f-41d6-b102-0cb702fb5e0f> | 3.875 | 603 | Knowledge Article | Science & Tech. | 62.454244 | 95,511,620 |
The Greenhouse Effect is the result of an interplay between the contents of our atmosphere and solar radiation. Our atmosphere is made of many different types of gasses. Nitrogen, oxygen and carbon dioxide are the principal ones. There are other gasses that can be found in trace amounts, such as ozone and methane that play an important role…
Some of the radiation is altered by the ozone layer, which inhibits ultraviolet radiation from passing directly to the surface to the earth. Much of the radiation that makes it to earth is absorbed and stored as heat in oceans and other large bodies of water. Radiation that strikes portions of the earth with a high albedo, such as solar ice caps and glaciers is reradiated back out into space. In fact, ultimately, the vast majority of solar radiation that enters the atmosphere is destined to be reradiated back into space. But a small percentage of that radiation gets trapped in the atmosphere as it tries to bounce back into space. Certain gasses, such as carbon dioxide and methane act to trap the radiation, causing the atmosphere to retain the radiation as heat. This warming of the earth’s atmosphere as a result of trapped radiation is called The Greenhouse Effect. Gasses such as carbon dioxide and methane are called greenhouse gases, due to their tendency to trap radiation, which causes the atmosphere to stay warm. Without The Greenhouse Effect, life on earth would be very different and impossible for humans. The Greenhouse Effect is directly related to the phenomenon known as Global Warming or Global Climate Change. The earth’s atmosphere is constantly changing. ...
Humans are the first species in the history of earth to burn massive amounts of fossil fuels such as coal, oil and natural gas. Burning these fuels puts carbon dioxide into the atmosphere. In recent years, the average global temperature has risen dramatically. Changes in global temperature usually happen very gradually, so many people are concerned that a rapid change in temperature will lead to destructive weather patterns, crop failures, increased spread of disease and insect pests (Roberts, 1994). Many scientists feel that this will lead to extinction on a mass scale and major disruptions to human activities. The continued introduction of greenhouse gasses such as carbon dioxide and methane that results from agricultural, manufacturing and transportation activities will surely result in a warmer global climate and stress on nearly all natural systems that sustain life on our planet. There are courses of action that can be taken to reduce or even reverse the warming trend that earth is now experiencing. One of the most immediate things we can to is to reduce the amount of greenhouse gasses we are putting into the atmosphere. Much of this comes from the transportation we use every day. Cars burn gasoline, which greatly contributes to the amount of carbon dioxide in the atmosphere. Driving less, or not at all, is one way we can slow global warming. Many people are living in communities that give them easy access to public transportation and to workplaces. More civil planners are providing spaces for walking paths and bicycle lanes in their plans. This means people have carbon free ways to get to work. Using alternative fuels and increasing fuel efficiency in cars is another way to prevent ...
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According to the paper, in the recent years with the modernization of this world, new and grave problems are arising for the people living in this world. With the help of modern science different types of troubles are being discovered in the globe on a daily basis. This essay would further describe the causes of Global Warming in relation to both the nature and human beings.
A number of researchers provide the example of the extremely cold weather recorded in the winter of 2003-2004 in the northeastern US. On the other hand, independent analyses by different researchers and scientists reveal that the climate of the earth has been showing increasingly warmer trends.
Basing their statement on this record they claim that the existence and prevalence of global warming is not convincing. On the other hand, independent analyses by different researchers and scientists reveal that the climate of earth has been showing increasingly warmer trends.
Australia is one of the world’s largest countries, with an estimated area of square kilometres 7,692,024. The country 'was formerly colonized by Britain and is still under the British monarchy. It was colonised by Europeans after it was discovered by European explorers in the 15th century.
The plan not only helps me in highlighting my weaknesses but also give me a clear picture where I am standing at certain date of the week and it also helps me to manage my finances in a much better and productive way through which I can change my spending into investments.
Nowadays the necessity of preservation of appropriate purity of the air is universally acknowledged; however, the problem of atmospheric pollution is sometimes ignored and underestimated in the developing world.
The pollution emitted by vehicles, factories etc is directly affecting the ozone layer and depleting it gradually, this can have a telling impact on our lives if not care of.
These green house gases trap heat in earth's atmosphere and thus result in increasing the temperature of earth. The excessive emission of these gases is one of the major Causes of Global Warming. The major source of carbon dioxide is the power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation.
The industrial advancement was said to remarkably cause greenhouse effect and global warming. As many establishments for instance are trying to produce offerings, more greenhouse gases like carbon dioxide and methane are directly emitted into the atmosphere. The rising number of vehicles due to industrialization has even led to the increase of greenhouse gases.
According to Schelling, the developing third world countries should take special care in the next few decades to reduce greenhouse effect as it is going to affect their climate and economy more than that of the
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A dense turf of foliose red seaweeds (including Plocamium cartilagineum, Cryptopleura ramosa and Delesseria sanguinea) on exposed or moderately exposed lower infralittoral rock, generally at or below the lower limit of the kelp. Most of the red seaweeds are common to the kelp zone above, while the faunal component of the biotope is made up of species that are found either in the kelp zone or the animal-dominated upper circalittoral below. The red seaweed species composition varies considerably and at some sites a single species may dominate (particularly Plocamium cartilagineum or Cryptopleura ramosa) As well as a varied red seaweed component, this biotope may also contain occasional kelp plants and patches of the brown foliose seaweed Dictyota dichotoma. In some areas Dictyota dichotoma may occur at high densities (see EIR.FoR.Dic). Other red seaweed-dominated biotopes occur in less wave-exposed areas (MIR.PolAhn), though they are affected by sand scour and are characterized by seaweeds that are resilient to the scouring. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).
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Many of the Rhodophyta e.g. Delesseria sanguinea, Plocamium cartilagineum, Dilsea carnosa and Corallina officinalis are perennial species that may persist for several years. For instance, Dickinson (1963) suggested a lifespan of 5-6 years for Delesseria sanguinea. However, Kain (1984) estimated that 1 in 20 specimens of Delesseria sanguinea may attain 9 - 16 years of age. Kain (1975) examined recolonization of cleared concrete blocks in a subtidal kelp forest. Red algae colonized blocks within 26 weeks in the shallow subtidal (0.8m) and 33 weeks at 4.4m. Delesseria sanguinea was noted within 41 weeks (8 months) at 4.4m in one group of blocks and within 56-59 days after block clearance in another group of blocks. This recolonization occurred during winter months following spore release and settlement, but not in subsequent samples (Kain, 1975). This suggests that colonization of Delesseria sanguinea in new areas is directly dependent on spore availability. Rhodophyceae have non flagellate, and non-motile spores that stick on contact with the substratum. Norton (1992) noted that algal spore dispersal is probably determined by currents and turbulent deposition. However, red algae produce large numbers of spores that may settle close to the adult especially where currents are reduced by an algal turf or in kelp forests.
Many of the sessile fauna present in the EIR.FoR biotope such as alcyonarians, ascidians and sponges, are present in the communities described by Sebens (1985) which were considered to be dynamic and fast growing. Smaller associated mobile species such as polychaetes and prosobranchs have planktonic larvae and would most likely colonize after a year. Large mobile species such as sea urchins, starfish and crabs would migrate into the area rapidly. The community may therefore take probably two or three years to reach maturity, but competitive interactions and the arrival of slower colonizing species could mean that dynamic stability is not achieved for several years.
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The biotope description and characterizing species is taken from Connor et al., (2004). This biotope is found on steep wave-surged entrances to gullies and caves and on unstable boulders in the entrance to caves and gullies. The rock may be abraded by the movement of the boulders and cobbles in heavy surge and tends to be dominated by dense foliose red seaweeds that grow rapidly in the calmer summer months. Beneath the foliose seaweeds the rock surface is typically covered with coralline crusts, which are longer-lived, and tolerant of abrasion. The flora of this biotope is relatively varied, depending upon the amount of light and degree of abrasion or rock mobility with red seaweeds such as Cryptopleura ramosa, Plocamium cartilagineum, Odonthalia dentata, Callophyllis laciniata, Phycodrys rubens, Hypoglossum hypoglossoides, Phyllophora crispa and Corallina officinalis. The brown seaweed Dictyota dichotoma also occurs in these conditions, since it is tolerant of some sand scour. As the key characterizing species that define and structure the biotope, evidence for the sensitivity of these species is considered in the sensitivity assessments.
During the summer months small fast-growing kelp plants can arise in this biotope, although the mobility of the substratum prevents the kelp from forming a kelp forest. Dense swathes of very young kelp such as Laminaria hyperborea are, however, not uncommon, these species are not considered to characterize the biotope and are not considered within the assessments. The faunal community consist of the anemone Urticina felina, the sponge Halichondria panicea and the ascidian Dendrodoa grossularia, the sensitivity of these species is considered generally within the sensitivity assessments. More mobile fauna include the echinoderms Asterias rubens and Echinus esculentus, the top shell Gibbula cineraria and the crab Cancer pagurus. The sensitivity of Echinus esculentus and the top shell are described generally in the sensitivity assessments as these species can structure biotopes by grazing on the algal turf and removing epifaunal recruits (Turner & Todd, 1991). Where grazing levels are high only coralline crusts may be present as the growing meristem is sheltered under the coralline surface and therefore resistant to grazing (Littler & Kitching, 1996).
Water movement and abrasion resulting from sediment instability are key factors structuring the biotope and significant alteration to these is likely to change the character of the biotope. Where pressures may alter these factors this is identified and discussed within the sensitivity assessments.
The red algae (Rhodophyta) and the brown algae Dictyota dichotoma that characterize this biotope have complex life histories and exhibit distinct morphological stages over the reproductive life history. Alternation occurs between asexual spore producing stages (tetrasporophytes) and male and female plants producing sexually (gametophytes). Life history stages can be morphologically different or very similar. Many red algae, including the characterizing species Plocamium cartilagineum, have prostrate creeping bases that produce erect branches whereas other species present in the biotope such as Dictyopteris membranacea, Callophyllis laciniata, Heterosiphonia plumosa the thallus or fronds arise from a small discoid holdfasts. The tetrasporophyte of Bonnemaisonia asparagoides is perennial and occurs as a crustose base that grows laterally, whereas the gametophyte is annual.
The spores of red algae are non-motile (Norton, 1992) and therefore entirely reliant on the hydrographic regime for dispersal. Norton (1992) reviewed dispersal by macroalgae and concluded that dispersal potential is highly variable, recruitment usually occurs on a much more local scale, typically within 10 m of the parent plant. Hence, it is expected that the red algal turf would normally rely on recruitment from local individuals and that recovery of populations via spore settlement, where adults are removed, would be protracted.
Littler & Kauker (1984) suggest that crustose bases are an adaptation to resist grazing and desiccation whereas the fronds are adapted for higher primary productivity and reproduction. The basal crusts of Corallina officinalis are tougher than the upright fronds (requiring a pressure of 94 g/mm2 to penetrate, compared to 43 g/mm2 respectively). Regeneration of the basal crusts provides a more rapid route to recovery than recolonization. Experiments in the intertidal in southern California found that areas of Corallina officinalis scraped back to crusts recovered four times more rapidly than sterilised plots where the crusts were removed (Littler & Kauker, 1984). Resistant crustose bases therefore enable the turf of red algae and the crustose corallines to withstand and recover from physical disturbance and scour while preventing the establishment of other species (Mathieson & Burns, 1975; Dudgeon & Johnson, 1992). Where these remain after an impact they provide a significant recovery mechanism. Species without crustose bases may also reproduce vegetatively, for example Dictyota dichotoma can reproduce vegetatively by fragmentation (Tronholm et al., 2010). Heterosiphonia plumosa, can also regrow from fragments (Boney, 1975).
Some species found in this biotope, such as Plocamium cartilagineum, Bonnemaisonia asparagoides and Delesseria sanguinea exhibit annual growth and die back, where growth is removed annually by abrasion or water action from winter storms reducing the biomass. Regrowth from holdfasts or crustose bases occurs in the spring (Kain, 1982, 1984, 1987; Maggs & Hommersand, 1993). Some temporal variation in abundance and biomass is therefore normal within this biotope. Macroalgae characterizing the biotope are either species with strategies to resist disturbance e.g. growing back from more resistant crustose bases or short-lived species that can reproduce annually and maintain presence via germlings. Dictyota dichotoma, for example, is an annual plant in North Carolina (where young germlings over-winter) and plants reach maturity and die back (Richardson, 1979).
Seasonality of reproduction varies between the red algal species within the site (Kain, 1982), so that timing of impacts will coincide with different phases of reproduction within species and may alter short-term recovery trajectories with effects on composition. In the Isle of Man, approximately 90 % of Plocamium cartilagineum, and Cryptopleura ramosa plants were fertile in late summer but less than 10% in spring, although some fertile plants were always present. The encrusting coralline Cruoria pellita showed little seasonality (Kain, 1982). Kain (1975) examined recolonization of cleared concrete blocks in a subtidal kelp forest. Red algae colonized blocks within 26 weeks in the shallow subtidal (0.8 m) and 33 weeks at 4.4 m. Delesseria sanguinea was noted within 41 weeks (8 months) at 4.4 m in one group of blocks and within 56-59 days in blocks cleared at two monthly intervals during winter months, but not in subsequent samples (Kain, 1975). This suggests that Delesseria sanguinea can recolonize areas, but is directly dependent on its reproductive season and spore availability. Rhodophyceae have non flagellate, and non-motile spores that stick on contact with the substratum. Norton (1992) noted that algal spore dispersal is probably determined by currents and turbulent deposition. However, red algae produce large numbers of spores that may settle close to the adult especially where currents are reduced by an algal turf or in kelp forests. It is likely that this species could recolonize an area from adjacent populations within a short period of time in ideal conditions but that recolonization from distant populations would probably take longer.
Although ubiquitous in marine coastal systems little is understood about the taxonomy, biology and ecology of the characterizing crustose corallines (Littler & Littler, 2013). Coralline crust is a generic term that in UK biotopes refers to nongeniculate (crustose) species from the family Corallinacea that could include Lithothamnion spp. and Phymatolithon spp. and Lithophyllum incrustans which is noted to form thick crusts in tidepools, especially in the south west (Adey & Adey, 1973) Due to the lack of evidence for species the assessments are generic, although species specific information is presented where available. A number of papers by Edyvean & Ford (1984a & b; 1986; 1987) describe aspects of reproduction and growth of encrusting coralline, Lithophyllum incrustans. Studies by Edyvean & Forde (1987) in populations of Lithophyllum incrustans in Pembroke south-west Wales suggest that reproduction occurs on average early in the third year. Reproduction may be sexual or asexual. Populations release spores throughout the year but abundance varies seasonally, with the populations studied in Cullercoats Bay, and Lannacombe Bay (North East and South West England, respectively) producing less spores in the summer. Spore release is initiated by changes in temperature or salinity (see relevant pressure information) at low tide so that spore dispersal is restricted to within the tide pool enhancing local recruitment. Within subtidal biotopes this is not possible and recruitment success may be altered (although this may be compensated by avoidance of desiccation). Spore survival is extremely low with only a tiny proportion of spores eventually recruiting to the adult population (Edyvean & Ford, 1986). The spores are released from structures on the surface called conceptacles, these are formed annually and are subsequently buried by a new layer of growth. Plants can be aged by counting the number of layers of conceptacles. Edyvean & Ford (1984) found that the age structure of populations sampled from Orkney (Scotland), Berwick (northern England) and Devon (England) were similarMortality seemed highest in younger year classes with surviving individuals after the age of 10 years appearing relatively long-lived (up to 30 years). In St Mary’s Northumberland, the population was dominated by the age 6-7 year classes (Edyvean & Ford, 1984). Growth rates were highest in young plants measured at Pembroke (south-west Wales) with an approximate increase in diameter of plants of 24 mm in year class 0 and 155 mm in year 1 and slowing towards an annual average horizontal growth rate of 3mm/year (Edyvean & Ford, 1987).
Some repair of damaged encrusting coralline occurs through vegetative growth. Chamberlain (1996) observed that although Lithophyllum incrustans was quickly affected by oil during the Sea Empress spill, recovery occurred within about a year. The oil was found to have destroyed about one third of the thallus thickness but regeneration occurred from thallus filaments below the damaged area. Recolonization by propagules is an important recovery mechanism; Airoldi (2000) observed that encrusting coralline algae recruited rapidly on to experimentally cleared subtidal rock surfaces in the Mediterranean Sea, reaching up to 68% cover in 2 months.
As a group, echinoderms are highly fecund; producing long lived planktonic larvae with high dispersal potential. However, recruitment in echinoderms is poorly understood, often sporadic and variable between locations and dependent on environmental conditions such as temperature, water quality and food availability. Recovery of populations may occur through repair of non-lethal damage, adult migration into impacted areas or larval colonisation. Lewis and Nichols (1979) found that adults were able to colonise an artificial reef in small numbers within 3 months and the population steadily grew over the following year. Similarly, Nichols (1981; 1984) reported that a site where all sea urchins were removed in 1978 had returned by a subsequent survey in 1979 (although no abundance was given). Recruitment of urchins is sporadic or annual, depending on locality and factors affecting larval pre-settlement and post-settlement survival. For example, in the heart urchin Echinocardium cordatum recruitment only occurred in 3 years out of a 10 year period (Buchanan, 1967). Millport populations of Echinus esculentus showed annual recruitment, whereas few recruits were found in Plymouth populations during Nichols studies between 1980 and 1981 (Nichols, 1984). Bishop and Earll (1984) suggested that the population of Echinus esculentus at St Abbs had a high density and recruited regularly whereas the Skomer population was sparse, ageing and had probably not successfully recruited larvae in the previous 6 years. Also, Echinus is slow to mature and it would take up to 8 years for adult biomass to be restored (MES, 2010). It is possible for Echinus to recolonize areas from which it is lost quickly by migration, where there is a large resident population in the surrounding area, such as on rocky or hard substrata. However, recruitment is more variable, annual in some cases or prolonged in others. Therefore, as Echinus esculentus is widespread and abundant around the coasts of the UK, a local population is likely to recover via migration from the surrounding area, and a resilience of ‘High’ (<2 years) is suggested, however it should be noted that in isolated areas dependent on recruitment alone, resilience would likely be ‘Medium’ (2-10 years). In contrast, Gibbula cineraria, another grazer within the biotope, is a fast growing species with a short-lifespan (Schöne et al., 2007) and pelagic dispersal stages (Underwood, 1972) and is considered to recover quickly (resilience is ‘High’ through migration from adjacent habitats and larval recolonization from any level of impact.
Resilience assessment. Where resistance is ‘High’ resilience is assessed as ‘High’ by default. Where resistance is ‘Medium’ then recovery is considered to be ‘High’ (<2 years) based on recolonization from the remaining population and vegetative growth and spread of perennial algae. Where resistance is ‘Low’ but crustose bases of red algae and parts of the crustose corallines remain then recovery is also assessed as ‘High’. However where resistance is ‘Low’ or ‘None’ and holdfasts are likely to be removed then resilience is assessed as ‘Medium’ (2-10 years).
NB: The resilience and the ability to recover from human induced pressures is a combination of the environmental conditions of the site, the frequency (repeated disturbances versus a one-off event) and the intensity of the disturbance. Recovery of impacted populations will always be mediated by stochastic events and processes acting over different scales including, but not limited to, local habitat conditions, further impacts and processes such as larval-supply and recruitment between populations. Full recovery is defined as the return to the state of the habitat that existed prior to impact. This does not necessarily mean that every component species has returned to its prior condition, abundance or extent but that the relevant functional components are present and the habitat is structurally and functionally recognizable as the initial habitat of interest. It should be noted that the recovery rates are only indicative of the recovery potential.
The key characterizing red algal species found in this biotope have a range of geographic distributions with some having a ‘southern distribution’ with their range encompassing warmer waters and others having a ‘northern’ distribution. Temperature tolerances are therefore likely to vary between species so that long-term changes in temperature have the potential to shift the species composition of this biotope to one more suited to the prevailing thermal regime. This biotope occurs in the subtidal and is therefore protected from exposure to air so that the thermal regime is more stable and desiccation is not a factor. Examples of distribution and thermal tolerances tested in laboratory experiments are provided as evidence to support the sensitivity assessment. Populations can acclimate to prevailing conditions (Davison, 1991; Lohrmann et al., 2004) which can alter tolerance thresholds and care should therefore be used when interpreting reported tolerances.
A number of the characterizing species found in the biotope such as Dictyopteris membranacea; Heterosiphonia plumosa, Cryptopleura ramosa, Plocamiujm cartilagineum and Lithophyllum incrustans are close to the northern edge of their reported distribution range in the UK (Kain, 1982, Guiry & Guiry, 2015). Cryptopleura ramosa, for example, is more common on southern shores of the UK (see MarLIN) and its distribution appears to be southern with worldwide records but none, from Canada, Scandinavia, Russia the Arctic or Antarctic (Guiry & Guiry, 2015) suggesting that it is likely to tolerate increased temperatures more successfully than decreased. The brown alga Dictyota dichotoma is also considered to be a warm-temperate species and is found throughout the NE Atlantic and Bermuda with the northern range extending to southern Norway and North Carolina (Richardson, 1979; Hoek, 1982; Tronholm et al., 2010). Based on the geographic range these species are considered more likely to tolerate chronic and acute increases in temperature at the pressure benchmark and a long-term change exceeding the pressure benchmark may increase habitat suitability. Tolerances within the southern group of red algae may vary, Cryptopleura ramosa, for example, is capable of surviving at 27 °C, while another characterizing species Plocamium cartilagineum, died within 12 hours in seawater at 27 °C (Gessner, 1970). (It should be noted that this temperature increase exceeds that of the benchmark level).
There is some evidence to suggest that blade growth in Delesseria sanguinea is delayed until ambient sea temperatures fall below 13 °C, although blade growth is likely to be intrinsically linked to gametangia development (see Kain, 1987). Delesseria sanguinea is tolerant of 23 oC for a week (Lüning, 1984) but dies rapidly at 25 oC. Rietema (1993) reported differences in temperature tolerance between North Sea and Baltic specimens. North Sea and Baltic specimens grew between 0-20 oC, survived at 23 oC but died at 25 oC rapidly (Rietema, 1993). Lüning (1990) reports optimal growth in Delesseria sanguinea between 10 - 15 oC and optimal photosynthesis at 20 oC. However, the upper limit of temperature tolerance is reduced by lowered salinity in Baltic specimens (Kinne, 1970; Kain & Norton, 1990). At low salinity photosynthesis is restricted to a narrow range of temperatures in adult thalli whereas juvenile thalli have a wider response range (Lobban & Harrison, 1997; fig 6.27). It is likely therefore that within the subtidal an increase in temperature of 2 oC in the long-term will have limited effect on survival, although it may affect initiation of new growth at the southern limits of the population. An increase of 5 oC in the short-term may affect survival if the ambient temperature is increased above 23 oC.
Increases in temperature at the pressure benchmark may impact the associated fauna. Echinus esculentus was recorded at temperatures between 0 -18 °C in the Limfjord, Denmark (Ursin, 1960). Bishop (1985) noted that gametogenesis proceeded at temperatures between 11 - 19 °C although continued exposure to 19 °C destroyed synchronicity of gametogenesis between individuals. Embryos and larvae developed abnormally after up to 24 hr at 15 °C (Tyler & Young, 1998) but normally at the other temperatures tested (4, 7 and 11 °C at 1 atmosphere). Bishop (1985) suggested that this species cannot tolerate high temperatures for prolonged periods due to increased respiration rate and resultant metabolic stress. Echinus esculentus is likely to have higher resistance to chronic long-term temperature change at the pressure benchmark but would probably be more intolerant of a short-term acute change (e.g. 5 °C for 1 week) in temperature. The impact of a chronic change may be exacerbated or mitigated by the timing of the exposure with changes in summer having the potential to exceed thermal tolerances, although winter increases may also be stressful where the species has acclimated to cooler waters. Effects on larval supply and recruitment may also result from chronic and acute changes depending on site-specific temperatures.
Sensitivity assessment. The associated red algae and Dictyota dichotoma are considered likely to be tolerant of an acute or chronic change at the pressure benchmark, with most species, particularly those with a southern distribution, able to tolerate an acute increase in temperature greater than the pressure benchmark (Gessner, 1970). For the grazing species Echinus esculentus however, increases in temperature could disrupt reproduction. The effects would depend on the magnitude, duration and footprint of the activities that result in this pressure. Biotope resistance is assessed as ‘High’ based on the red algae and resilience as ‘High’ (by default). This biotope is therefore considered to be ‘Not sensitive’ at the pressure benchmark. Sensitivity to longer-term, broad-scale perturbations such as increased temperatures from climate change could however be greater, based on degree of change, with direct effects on the composition of the red algae present or indirect effects arising from reduced grazing where reproduction success of Echinus esculentus is impacted.
The key characterizing red algal species found in this biotope have a range of geographic distributions with some having a ‘southern distribution’ with their range encompassing warmer waters and others having a ‘northern’ distribution. Temperature tolerances are therefore likely to vary between species so that long-term changes in temperature have the potential to shift the species composition of this biotope to one more suited to the prevailing thermal regime. Examples of distribution and thermal tolerances tested in laboratory experiments are provided as evidence to support the sensitivity assessment. Populations can acclimate to prevailing conditions (Davison, 1991; Lohrmann et al., 2004) which can alter tolerance thresholds. During experimental attempts to adapt red algae to cold by maintaining them at -1°C to + 1°C for several months, a drop in the lethal temperature tolerance of Delesseria sanguinea and a few other species was detected, in the order of 1 to 2°C (Gessner, 1970). Care should therefore be used when interpreting reported tolerances.
The brown alga Dictyota dichotoma is considered to be a warm-temperate species and is found throughout the NE Atlantic and Bermuda with the northern range extending to southern Norway and North Carolina (Richardson, 1979; Van den Hoek, 1982; Tronholm et al., 2010) and may be sensitive to decreased temperatures. Richardson (1979) demonstrated that the young germling stage of Dictyota dichotoma can overwinter in North Carolina at the northern edge of its distribution where winter water temperatures are less than 10 oC, providing a survival strategy. A number of the characterizing species found in the biotope such as Dictyopteris membranacea, Heterosiphonia plumosa, Plocamium cartilagineum, Cryptopleura ramosa, and Lithophyllum incrustans are also close to the northern edge of their reported distribution range in the UK (Kain, 1982, Guiry & Guiry, 2015). Cryptopleura ramosa, for example, is more common on southern shores of the UK (see MarLIN) and its distribution appears to be southern with worldwide records but none, from Canada, Scandinavia, Russia the Arctic or Antarctic (Guiry & Guiry, 2015) suggesting that it is likely to tolerate increased temperatures more successfully than decreased. Edyvean & Forde (1984b) suggest that populations of the crustose coralline, Lithophyllum incrustans, are affected by temperature changes and salinity and that temperature and salinity ‘shocks’ induce spawning. However, no information on thresholds was provided (Edyean & Ford, 1984b). Tolerance of reductions in temperature will vary within this group. In experiments Cryptopleura ramosa were partially or completely killed at 5 °C. Other species had a greater cold tolerance with Plocamium cartilagineum surviving at -2 °C (Gessner, 1970).
There is some evidence to suggest that blade growth in Delesseria sanguinea is delayed until ambient sea temperatures fall below 13 °C, although blade growth is likely to be intrinsically linked to gametangia development (see Kain, 1987). Rietema (1993) reported temperature differences in temperature tolerance between North Sea and Baltic specimens. North Sea and Baltic specimens grew between 0-20 oC, survived at 23 oC but died at 25 oC rapidly (Rietema, 1993). Lüning (1990) reports optimal growth in Delesseria sanguinea between 10 - 15 oC and optimal photosynthesis at 20 oC. However, the upper limit of temperature tolerance is reduced by lowered salinity in Baltic specimens (Kinne, 1970; Kain & Norton, 1990). At low salinity photosynthesis is restricted to a narrow range of temperatures in adult thalli whereas juvenile thalli have a wider response range (Lobban & Harrison, 1997; fig 6.27). It is therefore likely that an increase in temperature of 2 oC within the subtidal in the long-term will have limited effect on survival, although it may affect initiation of new growth at the southern limits of the population. An increase of 5 oC in the short-term may affect survival if the ambient temperature is increased above 23 oC. Species that occur north and south of the UK such as Bonnemaisonia asparagoides (Rueness & Åsen, 1982) are considered to be eurythermal and tolerant of a range of temperatures.
Echinus esculentus was recorded at temperatures between 0 -18°C in the Limfjord, Denmark (Ursin, 1960). Embryos and larvae developed abnormally after up to 24 hr at 15 °C but normally at the other temperatures tested (4, 7 and 11 °C at 1 atmosphere) (Tyler & Young, 1998). This species is therefore considered to be unaffected by decreases in temperature at the pressure benchmark
Sensitivity assessment. The characterizing red algae and Dictyota dichotoma are considered to be tolerant of an acute or chronic decrease in temperature at the pressure benchmark, with some species, particularly those with a northern distribution, able to tolerate an acute decrease in temperature greater than the pressure benchmark (Gessner, 1970). Changes in temperature may result in some shifts in community structure where thermal tolerances are exceeded `and more sensitive species die but these changes are not considered to alter the overall character of the biotope. Resistance is therefore assessed as ‘High’ and resilience as ‘High’ (by default) based on the red algae. This biotope is therefore considered to be ‘Not sensitive’ at the pressure benchmark
This biotope is recorded in full salinity habitats (Connor et al., 2004). Little evidence was found for salinity tolerances > 40 ppt (an increase at the pressure benchmark). The photosynthetic rates of Dictyopteris membranacea decrease after short-term exposure (30 minutes) to salinities above 55 ppt (Gessner, 1969). Respiratory rates are more sensitive and decreased sharply after 30 minute exposures to salinities above 20 ppt (Gessner, 1969). Rietema (1993) examined ecotypic differences between North Sea and Baltic populations of Delesseria sanguinea. Optimal growth occurred in Baltic specimens at 19 -23 psu and North Sea specimens at 33 psu. Optimal photosynthesis occurred at full salinity, even in specimens collected from 15 psu (Lehnberg, 1978; cited in Lobban & Harrison, 1997). Increased salinity at 40 psu drastically reduced photosynthesis in Baltic specimens (Kinne, 1971b).
No evidence concerning the specific tolerance of the grazer Echinus esculentus was found. Although Reid (1935) described its range as between 33.5 on the Norwegian Coast to 36.0 at Finisterre. Echinoderm larvae have a narrow range of salinity tolerance and develop abnormally and die if exposed to reduced or increased salinity. In general echinoderms are considered to be stenohaline species (Stickle & Diel, 1987) although acclimation to euryhaline conditions with periodic hyposalinity has been observed in some species (Russell, 2013).
Sensitivity assessment. Little evidence was found to assess the tolerance of the characterizing brown and red algae to hypersalinity at the pressure benchmark. Although some increases in salinity may be tolerated by the associated species present, this biotope is considered to be sensitive to a persistent increase in salinity to > 40 ppt (based on Delesseria sanguinea, Dictyopteris membranacea and Echinus esculentus). Biotope resistance is therefore assessed as ‘Low’ and recovery as ‘Medium’ (following restoration of usual salinity). Sensitivity is therefore assessed as ‘Medium’.
This biotope is recorded in full salinity habitats (Connor et al., 2004). Salinity tolerances vary between species. The red algae Cryptopleura ramosa,occur in variable salinity on tide-swept biotopes (IR.MIR.KT.FilRVS) and would probably survive a reduction in salinity at the pressure benchmark (18-30 ppt). However other species within the biotope are likely to be more sensitive and a change at the pressure benchmark is considered likely to reduce species richness and result in the loss of characterizing species. Available evidence for sensitivities is described below.
The photosynthetic and respiratory rates of Dictyopteris membranacea fall sharply after short-term exposure (30 minutes) to salinities below 20 ppt (Gessner, 1969). Even short-term exposure (1 minute) to freshwater will irreversibly destroy the photosynthetic capability of Dictyopteris membranacea. This intolerance to low salinities is the factor confining this species to subtidal habitats (Gessner, 1969).
At low salinities photosynthesis in adult Delesseria sanguinea occurs in a restricted temperature range, although juvenile thalli photosynthesise across a wider range of temperatures (Lehnberg, 1978; cited in Lobban & Harrison, 1997). Rietema (1993) examined ecotypic differences between North Sea and Baltic populations of Delesseria sanguinea. Optimal growth occurred in Baltic specimens at 19 -23 psu and North Sea specimens at 33 psu. North Sea specimens died at 7.5 - 11 psu. Delesseria sanguinea is likely to tolerate reduced salinity at the pressure benchmark, although growth and reproduction may be reduced in low salinity environments when compared to full salinity.
A comparative study of salinity tolerances of macroalgae collected from North Zealand in the South Kattegat (Denmark) where salinity is 16 psu. Showed that species generally had a high tolerance (maintained more than half of photosynthetic capacity) to short-term exposure (4 days) to salinities lower than 3.7 (Larsen & Sand-Jensen, 2006). Tolerances varied between species; Brongniartella byssoides and Delesseria sanguinea were among the least tolerant species tested (Larsen & Sand-Jensen, 2006). However, it should be noted that the test salinities far exceed the pressure benchmark.
Edyvean & Ford (1984b) suggest that populations of the crustose coralline Lithophyllum incrustans are affected by temperature changes and salinity and that temperature and salinity ‘shocks’ induce spawning but no information on thresholds was provided (Edyvean & Ford, 1984b). Populations of Lithophyllum incrustans were less stable in tide pools with a smaller volume of water that were more exposed to temperature and salinity changes due to lower buffering capacity. Sexual plants (or the spores that give rise to them) were suggested to be more susceptible than asexual plants to extremes of local environmental variables (temperature, salinity etc.) as they occur with greater frequency at sites where temperature and salinity were more stable (Edyvean & Ford, 1984b).
No evidence concerning the specific tolerance of Echinus esculentus was found, although Reid (1935) described its range as between 33.5 on the Norwegian Coast to 36.0 at Finisterre, Norway. Echinoderm larvae have a narrow range of salinity tolerance and develop abnormally and die if exposed to reduced or increased salinity (Russell, 2013). In general echinoderms are considered to be stenohaline species (Stickle & Diel, 1987) although acclimation to euryhaline conditions with periodic hyposalinity has been observed in some species (Russell, 2013). Populations in the sublittoral fringe probably encounter reduced salinity due to low water and fresh water runoff or heavy rain and may tolerate low salinity for short periods.
Sensitivity assessment. The available evidence illustrates that responses to this pressure will vary between species and that a change at the pressure benchmark is likely to alter the composition of the red algal turf that characterizes the biotope and may alter the biomass and density of more tolerant species. Resistance is therefore assessed as ‘Low’ (loss of 25-75% of individuals). Resilience (following the removal of this pressure) is assessed as ‘Medium’ (2-10 years) based on loss of characterizing coralline crusts and sensitivity is therefore assessed as ‘Medium’.
This biotope occurs across a range of flow speeds, from moderately strong (0.5-1.5 m/s) to areas where water flow is below 0.5 m/s (Connor et al., 2004). As water velocity increases foliose macroalgae can flex and reconfigure to reduce the size of the alga when aligned with the direction of flow, this minimises drag and hence the risk of dislodgement (Boller & Carrington, 2007). These characteristics allow these species to persist in areas that experience a range of flow speeds. Biogenic habitat structures, including the fronds of algae, reduce the effects of water flows on individuals by slowing and disrupting flow. Boller and Carrington (2006) found that the canopy created by a turf of Chondrus crispus reduced drag forces on individual plants by 15-65%. The compact, turf forming growth of the algal species characterizing this biotope will therefore reduce water flow and the risk of displacement through turbulence and friction.
The coralline crusts characterizing this biotope are securely attached and as these are flat are subject to little or no drag. Colonies of Lithophyllum incrustans appear to thrive in conditions exposed to strong water movement. Irvine & Chamberlain (1994). The suspension feeders within the biotope will also benefit from high water flows bringing food.
Records from the MNCR database were used as a proxy indicator of the resistance to wave height changes by Echinus esculentus (Tillin & Tyler-Walters, 2014). The latest version of the JNCC National Biodiversity Database was used as the source of the MNCR data. Echinus esculentus was recorded in biotopes from very weak (negligible) to moderately strong (0.5-1.5m/s) tidal streams, predominately in rock, mixed or very coarse sediment. Echinus esculentus move up the shore towards shallower waters when displaced, which is probably an adaptation to displacement to deeper waters by wave action (Lewis & Nichols, 1979a).Therefore, increased water flow is unlikely to kill individuals but may displace the population. However, once prior conditions return, the species would probably migrate back from the surrounding area.
Scour is a factor structuring this biotope in some areas and the species present are relatively scour tolerant (Connor et al., 2004). Changes in the flow may increase or decrease sediment transport and associated scour. Changes at the pressure benchmark are only likely to affect examples of this biotope that occur in sheltered areas with lower levels of water movement. Reductions in flow in areas where currents are weak may lead to increased deposition of silts and alter the character of the biotope, whereas an increase in water flow at the pressure benchmark may re-suspend and remove sand particles which are less cohesive than mud particles. The level of impact will depend on site specific hydrodynamic and sediment conditions. Some periodic movement of sediments and changes in coverage is part of the natural temporal variation. At the level of the pressure benchmark a change in water flow is considered unlikely to affect the habitat.
Sensitivity assessment. As the biotope can occur in a range of flow speeds, resistance of the biotope to changes in water flow is assessed as ‘High’ and resilience as ‘High’ (by default) so that the biotope is assessed as ‘Not sensitive’.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
Changes in emergence are not relevant to this biotope (group) which is restricted to fully subtidal habitats.
This biotope is recorded from locations that are judged to range from moderately exposed to exposed (Connor et al., 2004), while Dommasnes (1969) recorded turfs from very wave sheltered areas in Norway. The degree of wave exposure influences wave height, i.e. more exposed areas with a longer fetch waves would be predicted to be higher. As this biotope occurs across a range of exposures, this was therefore considered to indicate, by proxy, that biotopes in the middle of the wave exposure range would tolerate either an increase or decrease in significant wave height at the pressure benchmark. As water movement from wave action increases foliose macroalgae can flex and reconfigure to reduce the size of the alga when aligned with the direction of flow, this minimises drag and hence the risk of dislodgement (Boller & Carrington, 2007). These characteristics allow these species to persist in areas that experience a range of flow speeds resulting from wave action. The crustose corallines associated with this biotope have a flat growth form and are unlikely to be dislodged by increased wave action. Colonies of Lithophyllum incrustans appear to thrive in conditions exposed to strong water movement (Irvine & Chamberlain,1994).
A decrease in wave exposure at the pressure benchmark is unlikely to affect the brown and red algae directly. Decreases greater than the pressure benchmark that lead to reductions in boulder instability, abrasion and scour may lead to changes in the assemblage as species more characteristic of areas with less wave exposure are likely to colonize.
The available evidence suggests that associated species, including grazers occur across a range of wave exposures and are unlikely to be affected by a change in wave exposure at the pressure benchmark. Areas with high water velocities provide food to suspension feeders within the biotope such as sponges and anemones. Echinus esculentus can also occur within a range of wave exposure categories (Tillin & Tyler-Walters, 2014). An increase or decrease in wave height at the pressure benchmark is therefore considered to fall within the natural range of conditions experienced by this species. Echinus esculentus exhibit positive geotaxis and move up the shore towards shallower waters when displaced, which is probably adaptation to displacement to deeper waters by wave action (Lewis & Nichols, 1979a).
Sensitivity assessment. The biotope is found across a range of wave exposures, mid-range populations are considered to have 'High' resistance to a change in significant wave height at the pressure benchmark. Resilience is assessed as ‘High’, by default, and the biotope is considered ‘Not sensitive’.
|Not relevant (NR)||Not relevant (NR)||Not sensitive|
Not sensitive at the pressure benchmark that assumes compliance with all relevant environmental protection standards.
Contamination at levels greater than the pressure benchmark may adversely impact the biotope. No information was found concerning the effects of heavy metals on turf forming and encrusting coralline algae. Bryan (1984) suggested that the general order for heavy metal toxicity in seaweeds is: organic Hg> inorganic Hg > Cu > Ag > Zn> Cd> Pb. Contamination at levels greater than the pressure benchmark may adversely impact the biotope. Cole et al. (1999) reported that Hg was very toxic to macrophytes. The sub-lethal effects of Hg (organic and inorganic) on the sporelings of an intertidal red algae, Plumaria elegans, were reported by Boney (1971). 100% growth inhibition was caused by 1 ppm Hg.
Uptake of heavy metals from solution by seaweed is influenced by factors such as light, algal nitrogen content, frond age, length of emersion, temperature, salinity, season of the year and presence of other pollutants in the surrounding water (see Lobban & Harrison, 1997) and consequently seaweeds may not accurately reflect metal concentrations in the surrounding water. The order of metal toxicity to algae varies with the algal species and the experimental conditions, but generally the order is Hg> Cu> Cd> Ag> Pb> Zn (Rice et al., 1973; Rai et al., 1981), however insufficient information was available to comment further on the particular intolerance of algal species within the biotope. Kinne (1984) reported developmental disturbances in Echinus esculentus exposed to waters containing 25 µg / l of copper (Cu) and reduced species viability would result in the long-term as the species fail to successfully recruit. The information available is patchy but there would appear to be some intolerance of species within the biotope to heavy metals.
|Not relevant (NR)||Not relevant (NR)||Not sensitive|
Not sensitive at the pressure benchmark that assumes compliance with all relevant environmental protection standards.
Contamination at levels greater than the pressure benchmark may adversely impact the biotope. Smith (1968) reported that oil and detergent dispersants from the Torrey Canyon spill affected high water plans of Corallina officinalis more than low shore plants and some plants were protected in deep pools. In areas of heavy spraying, however, Corallina officinalis was killed (Smith, 1968). Regrowth of fronds had begun within two months after spraying ceased (Smith, 1968). O'Brien & Dixon (1976) suggested that red algae were the most sensitive group of algae to oil or dispersant contamination, possibly due to the susceptibility of phycoerythrins to destruction. They also reported that red algae are effective indicators of detergent damage since they undergo colour changes when exposed to relatively low concentrations of detergent. However, Smith (1968) reported that red algae such as Chondrus crispus, Mastocarpus stellatus and Laurencia pinnatifida were amongst the algae least affected by detergents. Laboratory studies by Grandy (1984) on the effects of oil and dispersants on several red algal species concluded that they were all sensitive to oil/dispersant mixtures, with little difference between adults, sporelings, diploid or haploid life stages.
Cole et al. (1999) suggested that herbicides were (not surprisingly) very toxic to algae and macrophytes. Hoare & Hiscock (1974) noted that with the exception of Phyllophora species, all red algae including encrusting coralline forms were excluded from the vicinity of an acidified halogenated effluent discharge in Amlwch Bay, Anglesey and intertidal populations of Corallina officinalis occurred in significant amounts only 600 m east of the effluent. Chamberlain (1996) observed that although Lithophyllum incrustans was quickly affected by oil during the Sea Empress spill, recovery occurred within about a year. The oil was found to have destroyed about one third of the thallus thickness but regeneration occurred from thallus filaments below the damaged area.
O'Brien & Dixon (1976) report that red algae are effective indicators of detergent damage since they undergo colour changes when exposed to relatively low concentrations. Smith (1968) reported that 10 ppm of the oil dispersive detergent BP 1002 killed the majority of specimens in 24 hrs in toxicity tests. However, the effects take several days to manifest; when killed the algae turn bright orange. Smith (1968) also demonstrated that 0.5 -1 ppm of the detergent BP1002 resulted in developmental abnormalities in echinopluteus larvae of Echinus esculentus. Echinus esculentus populations in the vicinity of an oil terminal in La Coruna Bay, Spain, showed developmental abnormalities in the skeleton. Hoare & Hiscock (1974) reported that red algae (e.g. Lithothamnia spp., Corallina officinalis, Polyides rotunda, Dilsea carnosa, Rhodymenia palmata and Desmarestia aculeata), echinoderms, Polyzoa and amphipod crustaceans appeared to be particularly intolerant of the reduction in water quality associated with the effluent discharged (containing free halogens, HCL & H2SO4) from a bromine extraction works into Amlwch Bay, Anglesey. Red algal species and the urchin Echinus esculentus are likely to be affected by synthetic chemicals.
Heavy mortality of Delesseria sanguinea occurred down to 12 m after the Torrey Canyon oil spill, although it was unclear how much of the effect was due to oil rather than dispersant contamination. Laboratory studies of the effects of oil and dispersants on several red algae species, including Delesseria sanguinea (Grandy, 1984; cited in Holt et al., 1995) concluded that they were all sensitive to oil/ dispersant mixtures, with little differences between adults, sporelings, diploid or haploid life stages. Holt et al. (1995) concluded that Delesseria sanguinea is probably generally sensitive to chemical contamination.
Most pesticides and herbicides were suggested to be very toxic for invertebrates, especially crustaceans (amphipods isopods, mysids, shrimp and crabs) and fish (Cole et al., 1999).
|Not relevant (NR)||Not relevant (NR)||Not sensitive|
Not sensitive at the pressure benchmark that assumes compliance with all relevant environmental protection standards.
Contamination at levels greater than the pressure benchmark may adversely impact the biotope. Smith (1968) reported that oil and detergent dispersants from the Torrey Canyon spill affected high water plans of Corallina officinalis more than low shore plants and some plants were protected in deep pools. In areas of heavy spraying, however, Corallina officinalis was killed (Smith, 1968). Regrowth of fronds had begun within two months after spraying ceased (Smith, 1968). O'Brien & Dixon (1976) suggested that red algae were the most sensitive group of algae to oil or dispersant contamination, possibly due to the susceptibility of phycoerythrins to destruction. They also reported that red algae are effective indicators of detergent damage since they undergo colour changes when exposed to relatively low concentration of detergent. However, Smith (1968) reported that red algae such as Chondrus crispus, Mastocarpus stellatus and Laurencia pinnatifida were amongst the algae least affected by detergents. Laboratory studies by Grandy (1984) on the effects of oil and dispersants on several red algal species concluded that they were all sensitive to oil/dispersant mixtures, with little difference between adults, sporelings, diploid or haploid life stages.
Cole et al. (1999) suggested that herbicides were (not surprisingly) very toxic to algae and macrophytes. Hoare & Hiscock (1974) noted that with the exception of Phyllophora species, all red algae including Delesseria sanguinea and encrusting coralline forms were excluded from the vicinity of an acidified halogenated effluent discharge in Amlwch Bay, Anglesey and intertidal populations of Corallina officinalis were abundant only 600m east of the effluent. Chamberlain (1996) observed that although Lithophyllum incrustans was quickly affected by oil during the Sea Empress spill, recovery occurred within about a year. The oil was found to have destroyed about one third of the thallus thickness but regeneration occurred from thallus filaments below the damaged area. Heavy mortality of Delesseria sanguinea occurred down to 12 m after the Torrey Canyon oil spill (probably due to a mixture of wave action and dispersant application). Laboratory studies of the effects of oil and dispersants on several red algae species, including Delesseria sanguinea (Grandy, 1984; cited in Holt et al., 1995) concluded that they were all sensitive to oil/ dispersant mixtures, with little differences between adults, sporelings, diploid or haploid life stages.
O'Brien & Dixon (1976) report that red algae are effective indicators of detergent damage since they undergo colour changes when exposed to relatively low concentrations. Smith (1968) reported that 10 ppm of the oil dispersive detergent BP 1002 killed the majority of specimens in 24hrs in toxicity tests. However, the effects take several days to manifest; when killed the algae turn bright orange.
Smith (1968) also demonstrated that 0.5 -1 ppm of the detergent BP1002 resulted in developmental abnormalities in echinopluteus larvae of Echinus esculentus. Echinus esculentus populations in the vicinity of an oil terminal in La Coruna Bay, Spain, showed developmental abnormalities in the skeleton. Hoare & Hiscock (1974) reported that red algae (e.g. Lithothamnia spp., Corallina officinalis, Polyides rotunda, Dilsea carnosa, Rhodymenia palmata and Desmarestia aculeata), echinoderms, Polyzoa and amphipod crustaceans appeared to be particularly intolerant of the reduction in water quality associated with the effluent discharged (containing free halogens, HCL & H2SO4) from a bromine extraction works into Amlwch Bay, Anglesey. Red algal species and the urchin Echinus esculentus are likely to be affected by synthetic chemicals.
Most pesticides and herbicides were suggested to be very toxic for invertebrates, especially crustaceans (amphipods isopods, mysids, shrimp and crabs) and fish (Cole et al., 1999).
|No evidence (NEv)||Not relevant (NR)||No evidence (NEv)|
|Not relevant (NR)||Not relevant (NR)||Not sensitive|
Not sensitive at the pressure benchmark that assumes compliance with all relevant environmental protection standards
|No evidence (NEv)||No evidence (NEv)||No evidence (NEv)|
The effects of reduced oxygenation on algae are not well studied. Plants require oxygen for respiration, but this may be provided by production of oxygen during periods of photosynthesis. Lack of oxygen may impair both respiration and photosynthesis (see review by Vidaver, 1972). A study of the effects of anoxia on the red alga, Delesseria sanguinea, revealed that specimens died after 24 hours at 15°C but that some survived at 5°C (Hammer, 1972).
No evidence is available to make a resistance assessment for the key characterizing species.Specific information concerning oxygen consumption and reduced oxygen tolerances were not found for the key characterizing species within the biotope. This pressure is not assessed due to lack of evidence.
Over geological timescales periods of increased nutrient availability have experienced increases in the distribution of crustose coralline species at the expense of corals (Littler & Littler, 2013), suggesting that this group have some tolerance for enhanced nutrient levels. Overall, Littler & Littler (2013) suggested that corallines as a group can tolerate both low and elevated levels of nutrients. The crustose coralline Lithophyllum incrustans was present at sites dominated by Ulva spp. in the Mediterranean exposed to high levels of nutrient enrichment from domestic sewage (Arévalo et al., 2007). Increased eutrophication of the Skagerrak strait has been linked to an increase in abundance of the characterizing species Phycodrys rubens. Increases in this species have also been observed with local eutrophication in shallow bays in the Baltic (Pedersén & Snoeijs 2001), suggesting this species is tolerant of some enrichment. An increase in abundance of red algae, including Delesseria sanguinea, was associated with eutrophication in the Skagerrak area, Sweden, especially in areas with the most wave exposure or water exchange (Johansson et al., 1998). However, where eutrophication resulted in high siltation rates, the delicate foliose red algae such as Delesseria sanguinea were replaced by tougher, erect red algae (Johansson et al., 1998). The brown alga Dictyopteris membranacea was formerly very abundant in the Lagoon of Venice but was replaced by Ulva rigida when levels of organic and inorganic pollution increased (Sfriso et al., 1992). This species like Cystoseira spp. requires, and is therefore indicative of high water quality.
Grazers in the biotope may benefit from increased availability of food resources, due to enhanced growth, and high levels of grazing may reduce the effects of eutrophication. Atalah & Crowe (2010) added nutrients to rockpools in controlled experiments. The rockpools were occupied by a range of algae including encrusting corallines, turfs of Mastocarpus stellatus, Chondrus crispus and Corallina officinalis and green and red filamentous algae. The invertebrates present were mostly Patella ulyssiponensis, the winkle Littorina littorea and the flat top shell Gibbula umbilicalis. Nitrogen and phosphorous enhancement was via the addition of fertilisers, as either 40 g/litre or 20 g/litre. The treatments were applied for seven months and experimental conditions were maintained every two weeks. A grazer and nutrient addition treatments was also applied where grazers were removed manually from pools and a 1 m strip bordering the pools. The experimental treatments do not directly relate to the pressure benchmark but indicate some general trends in sensitivity. In the pools the chronic addition of nutrients had no significant effect on the cover of crustose coralline algae or the red turfing algae. There was a significant interactive effect of grazing and nutrients however on the cover of crustose coralline algae. Pair-wise comparisons showed that cover of crustose coralline algae was significantly reduced where nutrients were added only under reduced grazing conditions, with an absolute decrease of 44 % (±8.0 S.E.) relative to the controls (P<,0.05). Grazers limit the effects of nutrient enrichment and in the absence of grazers significant changes in the structure of the algal assemblage from competition with green alga could emerge following eutrophication. However, the high levels of scour and abrasion in this biotope would prevent permanent colonization by larger perennial species and the ephemeral algae would be likely to be displaced by space-occupying red algae following disturbance and the creation of physical gaps in the habitat.
Sensitivity assessment. The pressure benchmark is relatively protective and may represent a reduced level of nutrient enrichment in previously polluted areas and may limit the growth of ephemeral green algae. Due to the tolerance of high levels of nutrient input demonstrated generally by encrusting corallines and red algal turfs, e.g. Belgrove et al., (2010) and Atalah & Crowe, (2010), resistance to this pressure is assessed as ‘High’ and resilience as ‘High’ so that the biotope is assessed as ‘Not sensitive’.
As the biotope occurs in tide swept or wave exposed areas (Connor et al., 2004), water movements will disperse organic matter reducing the level of exposure. The crusting coralline Lithophyllum incrustans were present at sites dominated by Ulva spp. in the Mediterranean that were exposed to high levels of organic pollution from domestic sewage (Arévalo et al., 2007). As turfs of red algae can trap large amounts of sediment the red algae are not considered sensitive to the sedimentation element of this pressure. Within trapped sediments associated species and deposit feeders would be able to consume inputs of organic matter.
The animals found within the biotope may be able to utilise the input of organic matter as food, or are likely to be tolerant of inputs at the benchmark level. Lawrence (1975) reported that sea urchins had persisted over 13 years on barren grounds near sewage outfalls, presumably feeding on dissolved organic material, detritus, plankton and microalgae, although individuals died at an early age. The ability to absorb dissolved organic material was suggested by Comely & Ansell (1988).
Sensitivity assessment. Based on resistance to sedimentation, exposure to wave action, and the dominance of red algal turfs in areas subject to sewage inputs, resistance is assessed as ‘High’ and resilience as ‘High’ (by default). The biotope is, therefore, considered to be ‘Not sensitive’ to this pressure at the benchmark.
All marine habitats and benthic species are considered to have a resistance of ‘None’ to this pressure and to be unable to recover from a permanent loss of habitat (resilience is ‘Very Low’). Sensitivity within the direct spatial footprint of this pressure is therefore ‘High’. Although no specific evidence is described confidence in this assessment is ‘High’, due to the incontrovertible nature of this pressure.
The loss of hard substratum would remove the rock habitat; sediments would be unsuitable for the attached brown and red algae that characterize this biotope and the associated epifauna such as Alcyonium digitatum and Caryophyllia smithii that characterize this biotope.
Artificial hard substratum may also differ in character from natural hard substratum, so that replacement of natural surfaces with artificial hard substratum may lead to changes in the biotope through changes in species composition, richness and diversity (Green et al., 2012; Firth et al., 2013) or the presence of non-native species (Bulleri & Airoldi, 2005). Many species have specific preferences for substratum type. Corallina officinalis shows optimal settlement on fine particle artificial substrata (0.5 - 1 mm surface particle diameter). Although spores will settle and develop as crustose bases on smooth surfaces, fronds were only initiated on rough surfaces. Corallina officinalis settled on artificial substrata within one week placement during the summer months in New England (Harlin & Lindbergh 1977). However, in the laboratory only fronds grew from bases attached to smooth surfaces (Wiedeman pers comm. Previous MarLIN review). Tests with stone panels fixed to the sublittoral, mid-tide and high-tide levels of varying roughness found that Ulva species settle preferentially on smoother, fine grained substratum (chalk, mottled sandstone) and Porphyra purpurea on rougher, granulated substratum (limestone, granite, basaltic larvae) (Luther, 1976) indicating species specific optimal habitats.
Sensitivity assessment. Based on the loss of suitable habitat, resistance is assessed as ‘None’ recovery is assessed as ‘Very Low’ as the change at the pressure benchmark is permanent. Sensitivity is therefore ‘High’.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
Not relevant to biotopes occurring on bedrock.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
The species characterizing this biotope are epifauna or epiflora occurring on rock and would be sensitive to the removal of the habitat. However, extraction of rock substratum is considered unlikely and this pressure is considered to be ‘Not relevant’ to hard substratum habitats.
The species characterizing this biotope occur on the rock and therefore have no protection from abrasion at the surface. No direct evidence was found to assess this pressure and evidence from intertidal studies on trampling on algal turfs has been used as a proxy. In general, studies show that turf forming algae appear to be relatively resistant to single events and low levels of trampling. Brosnan & Crumrine (1994), for example, found that in experimentally trampled plots the cover of foliose and canopy forming species declined while turf forming algae were relatively resistant. Similarly, a comparison of rocky intertidal ledges that received different amounts of visitors in Dorset, England, found that Corallina officinalis and encrusting corallines were present on both heavily visited and less visited ledges suggesting that these species has some resistance to trampling (Pinn & Rodgers, 2005). Fletcher and Frid (1996a; 1996b) noted a decrease in the understorey algal community of encrusting coralline algae and red algae, which was probably an indirect effect due to increased desiccation after removal of the normally protective fucoid canopy (Hawkins & Harkin, 1985) by trampling.
Schiel & Taylor (1999) reported the death of encrusting corallines one month after trampling due to removal of their protective canopy of fucoids by trampling (10 -200 tramples where one trample equals one transect walked by one person). A higher proportion of corallines died back in spring treatments presumably due to the higher levels of desiccation stress expected at this time of year. However, encrusting corallines increased within the following year and cover returned to control levels within 21 months (Schiel & Taylor, 1999). Mechanical abrasion from scuba divers was also reported to impact encrusting corallines, with cover of Lithophyllum stictaeforme greater in areas where diving was forbidden than visited areas (abundance, 6.36 vs 1.4; it is presumed this refers to proportion of cover, although this is not clear from the text, Guarinieri et al., 2012).
Dethier (1994) experimentally manipulated surface abrasion on a range of encrusting algae including Lithophyllum impressum. Crusts were brushed once each month for 1 minute, over 24 months with either a nylon or steel brush. Unbrushed controls grew by approximately 50 % whereas the cover of nylon and steel brushed crusts decreased by approximately 25% and 40% respectively (interpreted from figures in Dethier, 1994). In laboratory tests on three samples of Lithophyllum impressum chips, brushing with a steel brush for 1 minute once a week for 3 weeks, resulted in no cover loss of two samples while a third ‘thinned and declined’ (Dethier, 1994).
MacDonald et al., (1996) assessed benthic species sensitivity to fishing disturbance by ‘scoring’ each species ability to withstand the physical impact of a single fishing disturbance and recovery potential assuming no further fishing disturbance occurred. These authors classified the slow growing epifaunal species Echinus esculentus as being ‘very fragile’ and having ‘moderate’ recovery potential, based on life history characteristics. Kaiser et al. (2000) reported that Echinus esculentus were less abundant in areas subject to high trawling disturbance in the Irish Sea. This species was reported to suffer badly as a result of impact with passing scallop or queen scallop dredges (Bradshaw et al. 2000; Hall-Spencer & Moore, 2000a).
Sensitivity assessment. The impact of surface abrasion will depend on the footprint, duration and magnitude of the pressure. Based on evidence from intertidal step experiments and the relative robustness of encrusting corallines, Corallina officinalis turf and associated species, resistance, to a single abrasion event is assessed as ‘Medium’ and recovery as ‘High’, so that sensitivity is assessed as ‘Low’. Resistance and resilience will be lower (and hence sensitivity greater) to abrasion events that exert a greater crushing force and remove the bases than the trampling examples the assessment is based on). Resistance is therefore assessed as ‘Low’ and recovery as ‘Medium’ so that the sensitivity of the biotope defined by this species is assessed as ‘Medium’. Based on epifaunal position, size and fragility and the available evidence, Echinus esculentus is assessed as having ‘Low’ resistance to abrasion. Resilience is assessed as ‘High’ and therefore sensitivity is assessed as ‘Low’.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
The species characterizing this biotope group are epifauna or epiflora occurring on rock which is resistant to subsurface penetration. The assessment for abrasion at the surface only is therefore considered to equally represent sensitivity to this pressure.
In areas of high turbidity the brown seaweeds are replaced by red algae that are more tolerant of lower light levels and increased scour. Red algae possess only trace amounts of chlorophyll a (Lüning & Schmitz, 1988). Their main photosynthetic pigments are phycobiliproteins, which absorb optimally in the green light of deeper coastal waters. Photosynthesis in Delesseria sanguinea is inhibited by high light levels >200 µmol/m²/s, roughly equivalent to very clear shallow water in summer (Kain & Norton, 1990). However, in turbid coastal waters, where green light prevails, photosynthetic effectiveness increases with depth in red algae rich in phycoerythrin such as Delesseria sanguinea (Lüning, 1990). Delesseria sanguinea can grow in darkness using energy reserves stored in the stipe or lower regions of the frond ribs (Lüning, 1990). Increased turbidity would decrease the light levels at depth and may reduce the effective day length and induce reproduction earlier than in less turbid areas (Kain & Norton, 1990). Delesseria sanguinea is adapted to grow at depth or in the shade of other plants. Long-term (years) decreased turbidity may restrict its extent to shallower waters. Short-term changes may affect growth and reproduction, however, as a perennial, the adults will probably survive.
A decrease in turbidity that also resulted in a reduction in scour may allow kelp biotopes to extend in depth and replace this biotope. However, where significant scour still occurred from, for example periodic remobilisation of sand, then the biotope may not change in character.
Sensitivity assessment. This biotope is characterized by the presence of brown algae and may revert to a red algae only biotope in areas of high turbidity, such as the similar biotope IR.MIR.KR.XFoR, which is dominated by red seaweeds tolerant of turbidity including Plocamium cartilagineum and Calliblepharis ciliata (which may also be found in this biotope). The fauna in such biotopes is less diverse and at lower abundances (Connor et al., 2004). No information was found for suspended solid thresholds at which the brown seaweeds may be replaced and whether the brown algae could survive, with reduced growth, at the pressure benchmark. Resistance to an increase at the pressure benchmark is assessed as ‘Low’ and resilience (following a return to previous habitat conditions) is assessed as ‘Medium’, as red algal turfs may prevent recolonization by brown algae until physical gaps are formed. Sensitivity is therefore assessed as ‘Medium’. This biotope is considered to be 'Not sensitive' to a change in suspended solids, where levels of scour are unaffected.
A reduction in scour may allow less scour tolerant species and those adapted to higher light levels, such as kelps, to colonize the biotope. Resistance to a decrease in suspended solids, accompanied by a significant reduction in scour is assessed as ‘Medium’ as space pre-emption by red algae is likely to prevent colonization over the course of a year. Resilience (following a return to previous habitat conditions) is assessed as ‘High’. Sensitivity is therefore assessed as ‘Low’.
Increased abundance of algal turfs worldwide has been linked to sediment perturbations although not all the pathways and mechanisms of these effects are clear (see review by Airoldi, 2003). However, even the most tolerant of organisms would eventually suffer from inhibition and mortality following smothering although the thresholds for these effects have has not been identified (Airoldi, 2003).
Airoldi (2003) identified a number of morphological, physiological and life history traits that conferred high levels of tolerance to sedimentation. Those shared by characterizing species in the biotope are the regeneration of upright fronds from a perennial basal crust resistant to burial and scour, calcified thalli, apical meristems, large reproductive ouptuts, lateral vegetative growth and slow growth rates (Airoldi, 2003). Algae with tough thalli are more resistant to sedimentation and scour (Pedersén & Snoeijs, 2001).
In a review of the effects of sedimentation on rocky coast assemblages, Airoldi (2003) outlined the evidence for the sensitivity of encrusting coralline algae to sedimentation. The reported results are contradictory with some authors suggesting that coralline algae are negatively affected by sediments while others report that encrusting corallines are often abundant or even dominant in a variety of sediment impacted habitats (Airoldi, 2003 and references therein). Crustose corallines have been reported to survive under a turf of filamentous algae and sediment for 58 days (experiment duration) in the Galapagos (species not identified, Kendrick, 1991). The crustose coralline Hydrolithon reinboldii, has also been reported to survive deposition of silty sediments on subtidal reefs off Hawaii (Littler, 1973).
In an experimental study, Balata et al. (2007) enhanced sedimentation on experimental plots in the Mediterranean (close to Tuscany) by adding 400 g of fine sediment every 45 days on plots of 400 cm2 for 1 year. Nearby sites with higher and lower levels of sedimentation were assessed as control plots. Some clear trends were observed. Dictyota dichotoma was more abundant at sites with lower sedimentation (mean 2 and 6% of cover) and present in lower abundances (<1 %) at sites where sediments were added and at sites with naturally high sediment loads (Balata et al., 2007). Foliose algae, in general, were present in much greater abundances in areas with low sedimentation (mean cover of approximately 13% and 19%) and much reduced at experimental sites and those with high natural sedimentation (mean cover of approximately 2-3 %). Crustose corallines declined at medium and high levels of sedimentation but were still major space occupiers (100% cover). Some species of filamentous algae increased where sediment loads were naturally high or experimentally enhanced (Balata et al., 2007). The experiment relates to chronic low levels of sedimentation rather than a single acute event, as in the pressure benchmark, however the trends observed are considered to have some relevance to the pressure assessment. Foliose algae within the biotope are likely to be more sensitive to sedimentation than the characterizing encrusting corallines; however the presence of the foliose algae, including Dictyota dichotoma in sand scoured biotopes suggests some tolerance of sedimentation and associated scour.
Cooke (1957, cited in Cranmer, 1985) stated that echinoids ‘dislike mud’, possibly because of fine substratum affecting their respiratory capability (Dyer et al., 1983). However, the associated urchin species Echinus esculentus is likely to be able to tolerate small quantities of sediment deposition (MES, 2010). Comely and Ansell (1988) recorded large Echinus esculentus from kelp beds on the west coast of Scotland in which the substratum was seasonally covered with ‘high levels’ of silt. Last et al. (2011) found that a smaller epifaunal urchin Psammechinus miliaris is moderately tolerant of shorter term (12 days) burial events, with less than 25 % mortality of all buried specimens. Survivorship was partly due to the re-emergence of many specimens, even from depths of up to7 cm, particularly when buried under coarse sediment. After 12 days of burial, mortality in the specimens that remained buried was high. Percentage mortality increased with progressively finer sediment fractions.
Sensitivity assessment. Based on the biotope exposure to wave and water flow which will remobilise sediments and remove these, biotope resistance to this pressure, at the benchmark, is assessed as 'High', resilience is assessed as 'High' (by default) and the biotope is considered to be 'Not sensitive'. This is a likely result of the growth form of the characterizing foliose red algae and their presence in biotopes subject to sedimentation and scour (including the assessed biotope). The assessment considers that sediments are rapidly removed from the biotope and that the scour tolerance of the red algae and other species would prevent significant mortalities although some damage and abrasion may occur. However, if the deposit remained in place; i.e. due to the scale of the pressure or where biotopes were sheltered, or only seasonally subject to water movements or where water flows and wave action were reduced e.g. by the presence of tidal barrages, then resistance would be lower and sensitivity would be greater.
The available evidence for siltation pressures is outlined for the ‘light’ deposition pressure. At the pressure benchmark ‘heavy deposition’ represents a considerable thickness of deposit. Complete burial of algal turf and encrusting corallines and associated animals would occur. Removal of the sediments by wave action and tidal currents would result in considerable scour. The effect of this pressure will be mediated by the length of exposure to the deposit.
No evidence was found for the length of time Echinus esculentus could survive being buried under 30cm of sediment. In areas of high water flow, dispersion of fine sediments may be rapid and this will mitigate the magnitude of this pressure by reducing the time exposed and the depth of over burden that the species must crawl through.
Sensitivity assessment. Resistance is assessed as ‘Medium-Low’ as the impact on the characterizing and associated red algal species could be significant but may be mitigated by rapid removal. Resilience is assessed as ‘High’ based on vegetative re-growth from the scour-tolerant surviving bases of the characterizing species. Biotope sensitivity is therefore assessed as 'Low'. Resistance of Echinus esculentus to this pressure was assessed as ‘None’ by Tillin & Tyler-Walters (2014) due to the depth of overburden and the predicted low level of vertical migration. Resilience was assessed as ‘Medium’ (2-10 years) and sensitivity is therefore assessed as ‘Medium’. Sensitivity may be lower where the footprint of the deposit is small and migration of adults into the habitat from adjacent populations results in rapid recovery. The biotope assessment is based on the red algae, rather than Echinus esculentus.
|Not Assessed (NA)||Not assessed (NA)||Not assessed (NA)|
|No evidence (NEv)||No evidence (NEv)||No evidence (NEv)|
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
The red algae are generally flexible in terms of light requirements and can acclimate to different levels of light intensity and quality. Red algae possess only trace amounts of chlorophyll a (Lüning & Schmitz, 1988). Their main photosynthetic pigments are phycobiliproteins, which absorb optimally in the green light of deeper coastal waters. Photosynthesis in Delesseria sanguinea is inhibited by high light levels >200 µmol/m²/s, roughly equivalent to very clear shallow water in summer (Kain & Norton, 1990). However, in turbid coastal waters, where green light prevails, photosynthetic effectiveness increases with depth in red algae rich in phycoerythrin such as Delesseria sanguinea (Lüning, 1990). Delesseria sanguinea can grow in darkness using energy reserves stored in the stipe or lower regions of the frond ribs (Lüning, 1990). Increased turbidity would decrease the light levels at depth and may reduce the effective day length and induce reproduction earlier than in less turbid areas (Kain & Norton, 1990). Delesseria sanguinea is adapted to grow at depth or in the shade of other plants. Long-term (years) decreased turbidity may restrict its extent to shallower waters. Short-term changes may affect growth and reproduction, however, as a perennial, the adults will probably survive.
Coralline crusts are shade tolerant algae, often occurring under a macroalgal canopy that reduces light penetration. Encrusting corallines can occur in deeper water than other algae where light penetration is limited. Samples of Lithophyllum impressum suspended from a raft and shaded (50-75 % light reduction) continued to grow over two years (Dethier, 1994). Similarly Plocamium cartilagineum grows in shaded conditions beneath laminarian canopies, where irradiance is greater growth is lower and it appears that light levels of 0.5 mmol/m2/s are inhibitory (Kain, 1987). In areas of higher light levels, the fronds and bases may be lighter in colour due to bleaching (Colhart & Johansen, 1973). Other red algae in the biotope are flexible with regard to light levels and can also acclimate to different light levels.
Sensitivity assessment. As the key structuring and characterizing red algae species colonize a broad range of light environments from intertidal to deeper sub tidal and shaded understorey habitats the biotope is considered to have ‘High’ resistance and, by default, ‘High’ resilience and therefore is ‘Not sensitive’ to this pressure. The red algae are generally flexible in terms of light requirements and can acclimate to different levels of light intensity and quality. Coralline crusts are shade tolerant algae, often occurring under a macroalgal canopy that reduces light penetration. Encrusting corallines can occur in deeper water than other algae where light penetration is limited. Samples of Lithophyllum impressum suspended from a raft and shaded (50-75 % light reduction) continued to grow over two years (Dethier, 1994). Similarly Plocamium cartilagineum grows in shaded conditions beneath laminarian canopies: where irradiance is greater, growth is lower and it appears that light levels of 0.5 mmol/m2/s are inhibitory (Kain, 1987). In areas of higher light levels, the fronds and bases may be lighter in colour due to bleaching (Colhart & Johansen, 1973). Other red algae in the biotope are flexible with regard to light levels and can also acclimate to different light levels.
Barriers that reduce the degree of tidal excursion may alter propagule supply to suitable habitats from source populations. Conversely the presence of barriers may enhance local population supply by preventing the loss of larvae from enclosed habitats. Barriers and changes in tidal excursion are not considered relevant to the characterizing algae as species dispersal is limited by the rapid rate of settlement. Resistance to this pressure is assessed as 'High' and resilience as 'High' by default. This biotope is therefore considered to be 'Not sensitive'.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
Not relevant’ to seabed habitats. NB. Collision by grounding vessels is addressed under surface abrasion.
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
|Not relevant (NR)||Not relevant (NR)||Not relevant (NR)|
Key characterizing species within this biotope are not cultivated or translocated. This pressure is therefore considered ‘Not relevant’ to this biotope group.
A number of invasive red algae have been recorded in the UK, from reported habitat preferences Bonnemaisonia hamifera does not appear to be present in scoured environments although the harpoon weed, Asparagopsis armata is found in sandy pools (Guiry & Guiry, 2015). In North America Grateloupia turuturu is a major competitor of Chondrus crispus, although Grateloupia turuturu is present in the UK, this large foliose species may not be able to colonize this scoured biotope.
The invasive red algae Lophocladia lallemandi, that grows on Dictyota dichotoma in Mallorcan coastal waters, results in an increase in antioxidant biomarkers indicating stress and cellular damage that could lead to increased mortality (Tejada & Sureda, 2014). This species is not currently present in the UK but illustrates a potential effect on INIS on native species.
Sensitivity assessment. As scour within this biotope limits establishment of all but robust species, resistance to INIS is assessed as ‘High’ and resilience as ‘High’ (by default) so that the biotope is considered to be ‘Not sensitive’.
No evidence was found that microbial pathogens cause high levels of disease or mortality in this biotope. Diseased encrusting corallines were first observed in the tropics in the early 1990’s when the bacterial pathogen Coralline Lethal Orange Disease (CLOD) was discovered (Littler & Littler, 1995). All species of articulated and crustose species tested to date are easily infected by CLOD and it has been increasing in occurrence at sites where first observed and spreading through the tropics. Another bacterial pathogen causing a similar CLOD disease has been observed with a greater distribution and a black fungal pathogen first discovered in American Samoa has been dispersing (Littler & Littler, 1998). An unknown pathogen has also been reported to lead to white ‘target-shaped’ marks on corallines, again in the tropic (Littler et al., 2007). No evidence was found that these are impacting temperate coralline habitats.
Extracts of some red algae show antimicrobial, antiviral or antifungal properties providing some protection from pathogens. For example, Bonnemaisonia asparagoides produces surface-bound antibacterial compounds with a significant impact on the abundance and composition of the associated bacterial community (Nylund et al., 2010). Extracts of Dictyota dichotoma have antibiotic properties (Hornsey & Hide, 1974) and antiviral properties (Rabanal et al., 2014).
It is likely that populations within this biotope suffer some low-levels of infection of microbial pathogens and parasites. Specific examples include the red algal hemiparasite Gonimophyllum buffhamii, which occurs occasionally on subtidal Cryptopleura ramosa on southern and western coasts (Guiry & Guiry, 2015). Comely & Ansell (1988) recorded 28 invertebrate species associated with Echinus esculentus from the west coast of Scotland near Oban. These included the parasites Echinomermella grayi and Euonyx chelatus mentioned above and additionally 4 species of commensal polychaetes, a copepod and 10 amphipod species. The polychaete Adyte assimilis and the copepod Pseudoanthessius liber were regular commensals amongst the spines. Hyman (1955) states that Echinus esculentus is often infested with parasitic copepods e.g. Asterocheres echinola. Echinus esculentus is susceptible to 'Bald-sea-urchin disease', which causes lesions, loss of spines, tube feet, pedicellariae, destruction of the upper layer of skeletal tissue and death. It is thought to be caused by the bacteria Vibrio anguillarum and Aeromonas salmonicida. Bald sea-urchin disease was recorded from Echinus esculentus on the Brittany Coast. Although associated with mass mortalities of Strongylocentrotus franciscanus in California and Paracentrotus lividus in the French Mediterranean it is not known if the disease induces mass mortality (Bower 1996). No evidence of mass mortalities of Echinus esculentus associated with disease have been recorded in the UK.
Sensitivity assessment. Based on the available evidence for the characterizing coralline crust, red algae and other associated species the biotope is judged to have ‘High’ resistance to this pressure as no significant mortalities have been recorded. By default resilience is assessed as ‘High’ and the biotope is classed as ‘Not sensitive’ at the pressure benchmark.
Direct, physical impacts from harvesting are assessed through the abrasion and penetration of the seabed pressures. The sensitivity assessment for this pressure considers any biological/ecological effects resulting from the removal of target species on this biotope. No commercial application or harvesting of encrusting corallines was described in the literature.
The key characterizing foliose red algal species are not commercially targeted but have been investigated as alternative sources of the phycocolloid substances alginates and agar (Mathieson et al., 1984; Maggs, 1990) and in the future may be subject to harvesting.
The urchin Echinus esculentus may be harvested commercially as souvenirs for the tourist trade, or for human consumption (Comely & Ansell, 1988). Nichols (1981, 1984) examined the Cornish sea urchin fishery. It was noted that most commercial divers were inefficient at collecting the sea urchin, as many were obscured by weeds and other debris, or undersides of rocks, so that commercial divers probably leave behind a ‘fair proportion’ of the population. Intensive collecting did remove all urchins down to 15m from part of Lamora Cove, Cornwall in 1978. But the subsequent diving survey in 1979, showed that the urchins had returned (although no abundance was given), due to migration from deeper waters (Nichols 1981; 1984). At the time of the study (ca 1978-1984) about 0.5 million sea-urchins (Echinus) were collected annually. Nichols (1984) concluded that the fishery was sustainable, based on the few years studied. However, he cautioned against complete clearance due to the adverse effects on habitats. Also natural fluctuations in Echinus populations meant that it was not possible to determine an acceptable level of catch. He advised that population densities should not be allowed to fall below 0.2/m2, as this population density had been stable at Shallow Tinker Shoal, Plymouth for 24 years (Nichols 1984).
Sensitivity assessment. The species that are harvested, or potentially harvested, in this biotope are all attached or sedentary and relatively conspicuous. A single event of targeted harvesting could therefore efficiently remove individuals and resistance is assessed as ‘Low’. This assessment is supported by evidence from Sharp et al., (1993) on the proportion of biomass of Chondrus crispus removed commercially as no specific information was available for characterizing species. Resilience of the red seaweeds is assessed as ‘Medium’ (based on some damage occurring to perennial holdfasts and bases although see caveats in the resilience section) and biotope sensitivity is assessed as ‘Medium'. This assessment refers to a single collection event, long-term harvesting over wide spatial scales will lead to greater impacts, with lower resistance and longer recovery times. Commercial harvesting by divers of Echinus esculentus may be relatively inefficient, but at high intensities can remove 100% of the population (within the impacted area) resistance is assessed as ‘Low’ (significant mortality, 25-75% loss) and resilience is assessed as ‘High’. Sensitivity is therefore considered to be ‘Low’. The biotope sensitivity is based on the red seaweed assessment.
Incidental removal of the key characterizing species and associated species would alter the character of the biotope. The biotope is characterized by red and brown algae. The loss of these due to incidental removal as by-catch would alter the character of the biotope resulting in reclassification and result in the loss of species richness. The ecological services such as primary production and the habitat provided by these species would also be lost.
Sensitivity assessment. Removal of a large percentage of the characterizing species resulting in bare rock would alter the character of the biotope, species richness and ecosystem function. Resistance is therefore assessed as ‘Low’ and recovery as ‘Medium’ (based on removal of bases and holdfasts), so that biotope sensitivity is assessed as 'Low’.
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This review can be cited as:
Last Updated: 30/05/2002 | <urn:uuid:4b10b940-87ac-4eb1-84cc-de017662a6a0> | 2.75 | 30,634 | Knowledge Article | Science & Tech. | 41.21149 | 95,511,645 |
The TRMM satellite measured the rainfall from Typhoon Sanvu on May 24, 2012.TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data shows that Sanvu's heaviest rainfall was occurring in its northeastern quadrant where some intense storms were dropping rainfall at a rate greater than 50mm/hr (~2 inches/hr).
This TRMM image of rainfall from Typhoon Sanvu was taken on May 24, 2012. Sanvu's heaviest rainfall was occurring in its northeastern quadrant where some intense storms were dropping rainfall at a rate greater than 50mm/hr (~2 inches/hr). TRMM shows that the rainfall wraps around the eastern side of the storm, stretching from north to south, while the western side of the storm is deficient in rainfall. Light to moderate rainfall was falling at a rate between .78 inches and 1.57 inches per hour (20 to 40 mm).
Credit: NASA/TRMM, Hal Pierce
TRMM shows that the rainfall wraps around the eastern side of the storm, stretching from north to south, while the western side of the storm is deficient in rainfall.
On May 24 at 1500 UTC (11 a.m. EDT/U.S.), Typhoon Sanvu had maximum sustained winds near 65 knots (75 mph/120.4 kph). It was about 275 nautical miles south-southwest of Iwo To, Japan, near 21.2 North and 138.9 East.
Sanvu is causing high waves throughout the region, and waves have been estimated as high as 29 feet (8.8 meters). It is moving to the north at 9 knots (10.3 mph/16.6 kph).
Forecasters at the Joint Typhoon Warning Center now forecast the Sanvu will likely take a track very close to the island of Iwo To, Japan early on May 26. Iwo To was reporting thunderstorms and winds from the east-southeast by mid-day (U.S. EDT) on May 24 (May 25 local time) which are associated with the east-southeasterly flow from the approaching typhoon.
As Sanvu continues to approach, thunderstorms from the typhoon will be affecting the island on May 26.
Rob Gutro | EurekAlert!
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
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:f1a95aa6-7e9b-4472-9171-110494c4b824> | 2.5625 | 1,095 | Content Listing | Science & Tech. | 57.927776 | 95,511,651 |
According to Herbert Arthur Klein 'The Science of Measurement' p.113.
Synodic month 29 days, 12 hours, 44 minutes and 2.8 second.
Lunar year 354.367 days x 2.6 = 921.3542 days and this the perimeter of the pyramid in metres base 230.33855m... 755.7039 feet
9068.4 inches Petrie gives us 9068.8ins with mean difference 0.6.
Solar year 365.25 days x 26 (same number) = 9496.5 days this time divide by pi = 3022.829834 the perimeter of the Great pyramid base 755.7074585.
I don't believe it is a coincidence and I have long suspected that the metre is much closer to imperial measure than than thought by most including myself.
c copyright Jim Wakefield
|Solar and Lunar year found in base of the Great pyramid.||240||molder||29-Jun-18 02:43|
|Re: Solar and Lunar year found in base of the Great pyramid.||55||DavidK||29-Jun-18 06:34|
|Lunar year found in base of the Pyramid of the Sun Teotihuacan||28||molder||30-Jun-18 10:50|
|Re: Lunar year found in base of the Pyramid of the Sun Teotihuacan||34||DavidK||30-Jun-18 11:51|
|Re: Pedestal.....of the Sun and Moon||38||Thunderbird||30-Jun-18 22:16|
|Re: Pedestal.....of the Sun and Moon||38||molder||05-Jul-18 12:14| | <urn:uuid:e79c6bcb-4c19-4dd5-bcb3-d3888c9aabee> | 2.796875 | 364 | Comment Section | Science & Tech. | 104.277766 | 95,511,659 |
38. In an emergency stop to avoid an accident, a shoulder-strap seat belt holds a 60-kg passenger firmly in place. If the car were initially traveling at 90 km/h and came to a stop in 5.5 s along a straight, level road, what was the average force applied to the passenger by the seatbelt?
66. A person standing on a bridge at a height of 115 m above a river drops a 0.250-kg rock. (a) What is the rock's mechanical energy at the time of release relative to the surface of the river? (b) What are the rock's kinetic, potential, and mechanical energies after it has fallen 75.0 m? (c) Just before the rock hits the water, what are its speed and total mechanical energy? (d) Answer parts (a)-(c) for a reference point (y = 0) at the elevation where the rock is released. (Neglect air resistance.)
52. Imagine that you swing about your head a ball attached to the end of a string. The ball moves at a constant speed in a horizontal circle. (a) Can the string be exactly horizontal? Why? (b) If the mass of the ball is 0.250 kg, the radius of the circle is 1.50 m, and it takes 1.20 s for the ball to make one revolution, what is the ball's tangential speed? (c) What centripetal force are you imparting to the ball via the string?
56. A clock uses a pendulum that is 75 cm long. The clock is accidentally broken, and when it is repaired, the length of the pendulum is shortened by 2.0 mm. Consider the pendulum to be a simple pendulum. (a) Will the repaired clock gain or lose time? (b) By how much will the time indicated by the repaired clock differ from the correct time (taken to be the time determined by the original pendulum in 24 h)? (c) If the pendulum string were metal, would the surrounding temperature make a difference in the timekeeping of the clock? Explain.© BrainMass Inc. brainmass.com July 17, 2018, 7:28 pm ad1c9bdddf
The solution contains 4 pages providing full step-by-step explanations and derivations of the required expressions and numerical results. | <urn:uuid:476aa109-4ced-416b-a4a3-36306de93796> | 3.046875 | 490 | Tutorial | Science & Tech. | 77.806 | 95,511,667 |
Game Programming using Qt 5 Beginner's Guide, 2nd Edition
Create amazing games with Qt 5
|Authors||Pavel Strakhov, Witold Wysota, Lorenz Haas|
|Format||Paper book / ebook|
Qt is the leading cross-platform toolkit for all significant desktop, mobile, and embedded platforms and is becoming popular by the day, especially on mobile and embedded devices. It's a powerful tool that perfectly fits the needs of game developers. This book will help you learn the basics of Qt and will equip you with the necessary toolsets to build apps and games.
The book begins by how to create an application and prepare a working environment for both desktop and mobile platforms. You will learn how to use built-in Qt widgets and Form Editor to create a GUI application and then learn the basics of creating graphical interfaces and Qt's core concepts.
Further, you'll learn to enrich your games by implementing network connectivity and employing scripting. You will learn about Qt's capabilities for handling strings and files, data storage, and serialization.
Moving on, you will learn about the new Qt Gamepad module and how to add it in your game and then delve into OpenGL and Vulcan, and how it can be used in Qt applications to implement hardware-accelerated 2D and 3D graphics. You will then explore various facets of Qt Quick: how it can be used in games to add game logic, add game physics, and build astonishing UIs for your games.
By the end of this book, you will have developed the skillset to develop interesting games with Qt. | <urn:uuid:e34d646c-928f-4d56-8fea-90c84da05172> | 2.5625 | 329 | Product Page | Software Dev. | 47.450708 | 95,511,673 |
- Published on Wednesday, 11 July 2018 09:00
Quantum secret-sharing scheme for noisy environments
To protect the confidentiality of a message during its transmission, people encrypt it. However, noise in the transmission channels can be a source of concern regarding how faithful the message transmission may be after it has been decrypted. This is particularly important for secrets shared using quantum scale messengers. For example, a classical secret takes the shape of a string of zeros and ones, whereas a quantum secret is akin to an unknown quantum state of two entangled particles carrying the secret. This is because no two quantum particles can be in the same state at any given time. In a new study published in EPJ D, Chen-Ming Bai from Shaanxi Normal University, Xi’an, China, and colleagues calculate the degree of fidelity of the quantum secret once transmitted and explore how to avoid eavesdropping.
- Published on Tuesday, 12 June 2018 13:50
New study reveals theoretical calculation of new possible state for quantum particles which have received a photon
Quantum particles behave in mysterious ways. They are governed by laws of physics designed to reflect what is happening at smaller scales through quantum mechanics. Quantum state properties are generally very different to those of classical states. However, particles finding themselves in a coherent state are in a kind of quantum state which behaves like a classical state. Since their introduction by Erwin Schrödinger in 1926, coherent states of particles have found many applications in mathematical physics and quantum optics.
Now, for the first time, a team of mathematical physicists from Togo and Benin, call upon supersymmetry - a sub-discipline of quantum mechanics - to explain the behaviour of particles that have received a photon. These particles are subjected to particular potential energies known as shape-invariant potentials.
In a paper published in EPJ D, Komi Sodoga and colleagues affiliated with both the University of Lomé, Togo, and the University of Abomey-Calavi, in Cotonou, Benin, outline the details of their theory. These findings are relevant to scientists working on solving quantum optics and quantum mechanics applications.
- Published on Tuesday, 15 May 2018 14:10
The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥106) accumulated in such a device may be ejected all at once, so as to generate an intense pulse.
- Published on Thursday, 03 May 2018 10:58
Improving the spatial compression of a mixed matter-antimatter trapped plasma brings us one step closer to grasping the acceleration of antimatter due to Earth’s gravity
An international team of physicists studying antimatter have now derived an improved way of spatially compressing a state of matter called non-neutral plasma, which is made up of a type of antimatter particles, called antiprotons, trapped together with matter particles, like electrons.
- Published on Friday, 09 March 2018 09:06
In this new article in EPJ D, Franke et al. review the present understanding of Lamb shift, fine- and hyperfine structure of the 2S and 2P states in muonic helium-3 ions in anticipation of the results of the first measurements of several 2S -> 2P transition frequencies in the muonic helium-3 ion, 3He+. This ion is the bound state of a single negative muon μ- and a bare helium-3 nucleus (helion), 3He++.
- Published on Friday, 16 February 2018 12:16
New approximate cloning method avoids the previous limitations of quantum cloning to enhance quantum computing and quantum cryptography leaks
Cloning of quantum states is used for eavesdropping in quantum cryptography. It also has applications in quantum computation based on quantum information distribution. Uncertainty at the quantum scale makes exact cloning of quantum states impossible. Yet, they may be copied in an approximate way - with a certain level of probability - using a method called probabilistic quantum cloning, or PQC. In a new study published in EPJ D, Pinshu Rui from Anhui Xinhua and Anhui Universities, based in Hefei, China, and colleagues demonstrate that partial PQC of a given quantum state secretly chosen from a certain set of states, which can be expressed as the superposition of the other states, is possible.
- Published on Thursday, 21 December 2017 19:56
Atomic Spin Squeezing: not the Olympic sport of your dreams, but a way of enhancing measurement reliability at the quantum scale
Noise: it affects us all by distracting us. Noise also occurs at the quantum scale and can e.g. interfere with the measurements of atomic fountain clocks or with quantum information processing. This is because at that scale, there are effects that don't exist at larger scales. As such, finding ways to reduce quantum noise can enhance the precision of measurement in the examples given above. Now a team of physicists including Aranya Bhattacherjee from Jawaharlal Nehru University, New Delhi, India and colleagues are investigating ways of improving the analysis of quantum noise measurement in the case of spectroscopic investigations; their preliminary findings were released in a study in EPJ D. This method, called atomic spin squeezing, works by redistributing the uncertainty unevenly between two components of spin in these measurements systems, which operate at the quantum scale. The spin represents a degree of freedom of the quantum particles involved. Thus, the spin component with reduced uncertainty becomes more precise in delivering its measurement - as the two are inversely correlated. Potential applications include the development of future quantum networks.
- Published on Wednesday, 22 November 2017 09:49
Ion beam cancer therapy could be improved if ion-induced shock waves are discovered. A new study explores how these predicted waves can be observed
An arrow shooting through an apple, makes for a spectacular explosive sight in slow motion. Similarly, energetic ions passing through liquid droplets induce shock waves, which can fragment the droplets. In a study published in EPJ D, Eugene Surdutovich from Oakland University, Rochester, Michigan, USA with his colleagues from the MBN Research Centre, Frankfurt, Germany have proposed a solution to observe the predicted ion-induced shock waves. They believe these can be identified by observing the way incoming ions fragment liquid droplets into multiple smaller droplets. The discovery of such shock waves would change our understanding of the nature of radiation damage with ions to cancerous tumour. This matters for the optimisation of ion-beam cancer therapy, which requires a thorough understanding of the relation between the physical characteristics of the incoming ion beam and its effects on biological tissues.
EPJ D Colloquium - Two-dimensional laser-induced fluorescence in the gas phase: a spectroscopic tool for studying molecular spectroscopy and dynamics
- Published on Thursday, 16 November 2017 14:49
Two-dimensional laser-induced fluorescence (2D-LIF) extends the usual laser-induced fluorescence technique by incorporating a second dimension, namely the wavelengths at which the excited molecules emit, thereby significantly enhancing the information that can be extracted. It allows overlapping absorption features, whether they arise from within the same molecule or from different molecules in a mixture, to be associated with their appropriate "parent" state and/or molecule.
- Published on Tuesday, 26 September 2017 22:08
Improving the efficiency of quantum heat engines involves reducing the number of photons in a cavity, ultimately impacting quantum manipulation power
Traditionally, heat engines produce heat from the exchange between high-temperature and low-temperature baths. Now, imagine a heat engine that operates at quantum scale, and a system made up of an atom interacting with light (photons) confined in a reflective cavity of sub-atomic dimensions. This setup can either be at a high or low temperature, emulating the two baths found in conventional heat engines. Controlling the parameters influencing how such quantum heat engine models work could dramatically increase our power to manipulate the quantum states of the coupled atom-cavity, and accelerate our ability to process quantum information. In order for this to work, we have to find new ways of improving the efficiency of quantum heat engines. In a study published in EPJ D, Kai-Wei Sun and colleagues from Beihang University, Beijing, China, show methods for controlling the output power and efficiency of a quantum thermal engine based on the two-atom cavity. In the familiar heat engine model at macroscopic scale, referred to as the Carnot heat engine, the efficiency increases as a function of the ratio between the temperatures of the low-and high-temperature baths. By comparison, the efficiency of two-level quantum heat engines is related to the level of quantum entanglement in these two states, which are either at a low or a high temperature, and display the same probability of being occupied. | <urn:uuid:f443d75b-7516-4ffd-9f6a-678f57e34e47> | 2.65625 | 1,853 | Content Listing | Science & Tech. | 22.299136 | 95,511,721 |
Global warming stops at nothing – not even the groundwater, as a new study by researchers from ETH Zurich and KIT reveals: the groundwater’s temperature profiles echo those of the atmosphere, albeit damped and delayed.
For their study, the researchers were able to fall back on uninterrupted long-term temperature measurements of groundwater flows around the cities of Cologne and Karlsruhe, where the operators of the local waterworks have been measuring the temperature of the groundwater, which is largely uninfluenced by humans, for forty years. This is unique and a rare commodity for the researchers.
“For us, the data was a godsend,” stresses Peter Bayer, a senior assistant at ETH Zurich’s Geological Institute. Even with some intensive research, they would not have been able to find a comparable series of measurements. Evidently, it is less interesting or too costly for waterworks to measure groundwater temperatures systematically for a lengthy period of time. “Or the data isn’t digitalised and only archived on paper,” suspects the hydrogeologist.
Damped image of atmospheric warming
Based on the readings, the researchers were able to demonstrate that the groundwater is not just warming up; the warming stages observed in the atmosphere are also echoed. “Global warming is reflected directly in the groundwater, albeit damped and with a certain time lag,” says Bayer, summarising the main results that the project has yielded. The researchers published their study in the journal Hydrology and Earth System Sciences.
The data also reveals that the groundwater close to the surface down to a depth of around sixty metres has warmed up statistically significantly in the course of global warming over the last forty years. This water heating follows the warming pattern of the local and regional climate, which in turn mirrors that of global warming.
The groundwater reveals how the atmosphere has made several temperature leaps at irregular intervals. These “regime shifts” can also be observed in the global climate, as the researchers write in their study. Bayer was surprised at how quickly the groundwater responded to climate change.
Heat exchange with the subsoil
The earth’s atmosphere has warmed up by an average of 0.13 degrees Celsius per decade in the last fifty years. And this warming doesn’t stop at the subsoil, either, as other climate scientists have demonstrated in the last two decades with drillings all over the world. However, the researchers only tended to consider soils that did not contain any water or where there were no groundwater flows.
While the fact that the groundwater has not escaped climate change was revealed by researchers from Eawag and ETH Zurich in a study published three years ago, it only concerned “artificial” groundwater. In order to enhance it, river water is trickled off in certain areas. The temperature profile of the groundwater generated as a result thus matches that of the river water.
The new study, however, examines groundwater that has barely been influenced by humans. According to Bayer, it is plausible that the natural groundwater flow is also warming up in the course of climate change. “The difference in temperature between the atmosphere and the subsoil balances out naturally.” The energy transfer takes place via thermal conduction and the groundwater flow, much like a heat exchanger, which enables the heat transported to spread in the subsoil and level out.
The consequences of these findings, however, are difficult to gauge. The warmer temperatures might influence subterranean ecosystems on the one hand and groundwater-dependent biospheres on the other, which include cold areas in flowing waters where the groundwater discharges. For cryophilic organisms such as certain fish, groundwater warming could have negative consequences.
Consequences difficult to gauge
Higher groundwater temperatures also influence the water’s chemical composition, especially the chemical equilibria of nitrate or carbonate. After all, chemical reactions usually take place more quickly at higher temperatures. Bacterial activity might also increase at rising water temperatures. If the groundwater becomes warmer, undesirable bacteria such as gastro-intestinal disease pathogens might multiply more effectively. However, the scientists can also imagine positive effects. “The groundwater’s excess heat could be used geothermally for instance,” adds Kathrin Menberg, the first author of the study.
Menberg K, Blum P, Kurylyk BL, Bayer P: Observed groundwater temperature response to recent climate change. Hydrology and Earth System Sciences 2014, 18: 4453-4466, doi: 10.5194/hess-18-4453-2014
Roman Klingler | 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
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:08baa540-2b49-4477-80f0-38f07b666d4b> | 3.59375 | 1,520 | Content Listing | Science & Tech. | 35.016921 | 95,511,723 |
Glittering stars overhead. The sounds of crickets and frogs. The flash of lightning bugs. The lack of cell phone signals. Ahhh... The great outdoors. Whether you like to rough it with a tent or prefer the comforts of cabin camping, summer may find you packing up your gear and heading for the woods. Time off the main road raises many opportunities to explore science. With a bit of advance planning, you can explore projects that turn your campsite into an outdoor laboratory.
Whether you experiment before you go and take the results with you, or whether you plan to put your procedures into action from the campsite, these project ideas will help open your eyes to the questions lurking just outside the tent.
- Mixing Your Own Marshmallows
For some, the quest to make the perfect s'more is as important on a weekend camping trip as learning to identify mushrooms or pick out constellations. With chocolate, grahams, and marshmallows at stake, it's hard to really go wrong. Still, just like roasting a perfect hotdog, melting the perfect campfire treat is part of the fun of roughing it. Plan ahead, and you can make your own marshmallows to take on the road!
In this science project, you'll explore the role of corn syrup, gelatin, and sugar in making marshmallows. Plus, in the process, you'll learn a lot about the chemistry of cooking and how temperature transforms recipes that have seemingly similar ingredients into treats as different as caramels and lollipops! (Difficulty: 5-6)
- Are You in Hot Water? Use the Sun's Energy to Heat Your Own Water
There's no denying the benefits of good fire-starting skills when the sun goes down. Many seasons of "Survivor" have shown that rubbing two sticks together to get a spark isn't necessarily easy! In between practicing your fire-making, brush up on the power of renewable solar energy and put peak sun during the day to use as you turn plastic trash bags into batch solar collectors and let the sun do the work heating the water. (Difficulty: 2-4)
- Which kind of wood burns slower?*
Different woods burn at different rates. To get the best results from your evening fire, you'll need to experiment to find out which wood burns longest. This abbreviated project idea can help get you started thinking about an experimental design either at home or at the campsite. (Difficulty: 5)
- Now You're Cooking!
For a more involved look at solar energy, use the procedure in this project to build a small solar oven. It can take twice as long to cook a meal with solar power, so leave plenty of time. (Difficulty: 5-8)
- Where Did All the Stars Go?
Part of the wonder of camping is the chance to sit under an expanse of nighttime sky, far away (hopefully) from the lights and sounds of the city. A perfect project for all ages, counting stars before leaving home and then again at the campsite brings "light pollution" into easy-to-see context. (Difficulty: 1)
- Finding Your Way
Last summer on the blog, we wrote about stepping away from high-tech positioning and location technologies like GPS and learning to "orient" oneself using natural cues and clues. Whether you turn to the trees or the stars, there are many levels of "mapping" available around you—you just have to know how to read the map!
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Gadolinium: the essentials
Gadolinium atoms have 64 electrons and the shell structure is 18.104.22.168.9.2. The ground state electronic configuration of neutral gadolinium is [Xe].4f7.5d1.6s2 and the term symbol of gadolinium is 9D2.
Gadolinium is silvery white, has a metallic lustre, and is is malleable and ductile. It is ferromagnetic (strongly attracted by a magnet).
The metal is relatively stable in dry air, but in moist air it tarnishes with the formation of a loosely adhering oxide film which "spalls" off and exposes more surface to oxidation. The metal reacts slowly with water and is soluble in dilute acid. Gadolinium has the highest thermal neutron capture cross-section of any known element.
This sample is from The Elements Collection, an attractive and safely packaged collection of the 92 naturally occurring elements that is available for sale.
Gadolinium: physical properties
Gadolinium: heat properties
- Melting point: 1585 [1312 °C (2394 °F)] K
- Boiling point: 1585 [1312 °C (2394 °F)] K
- Enthalpy of fusion: 20.5 kJ mol-1
Gadolinium: atom sizes
- Atomic radius (empirical): 180 pm
- Molecular single bond covalent radius: 169 (coordination number 3) ppm
- van der Waals radius: 279 ppm
- Pauling electronegativity: 1.20 (Pauling units)
- Allred Rochow electronegativity: 1.11 (Pauling units)
- Mulliken-Jaffe electronegativity: (no data)
Gadolinium: orbital properties
- First ionisation energy: 593.37 kJ mol‑1
- Second ionisation energy: 1165.2 kJ mol‑1
- Third ionisation energy: 1980 kJ mol‑1
Gadolinium: crystal structure
Gadolinium: biological data
- Human abundance by weight: (no data) ppb by weight
Gadolinium has no biological role but is said to stimulate the metabolism.
Reactions of gadolinium as the element with air, water, halogens, acids, and bases where known.
Gadolinium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of gadolinium where known.
Gadolinium: compound properties
Bond strengths; lattice energies of gadolinium halides, hydrides, oxides (where known); and reduction potentials where known.
Gadolinium: historyGadolinium was discovered by Jean de Marignac in 1880 at Switzerland. Origin of name: named after J. "Gadolin", a Finnish chemist and minerologist.
Gadolinium has the highest cross section for the capture of thermal neutrons of any element and this is mainly due to the high cross section of Gd-157 (255,000 barn) and Gd-155 (61,000 barn). Natural Gadolinium is currently used as a burnable poison in nuclear fuel, but the use of Gd-155/157 only has been proposed as this would create an even more effective burnable poison. Gd-152 is used for the production of radioactive Gd-153 which is used for osteoporosis research and bone density measurements. Gd-160 is used in double beta decay research.
Isolation: gadolinium metal is available commercially so it is not normally necessary to make it in the laboratory, which is just as well as it is difficult to isolate as the pure metal. This is largely because of the way it is found in nature. The lanthanoids are found in nature in a number of minerals. The most important are xenotime, monazite, and bastnaesite. The first two are orthophosphate minerals LnPO4 (Ln deonotes a mixture of all the lanthanoids except promethium which is vanishingly rare) and the third is a fluoride carbonate LnCO3F. Lanthanoids with even atomic numbers are more common. The most comon lanthanoids in these minerals are, in order, cerium, lanthanum, neodymium, and praseodymium. Monazite also contains thorium and ytrrium which makes handling difficult since thorium and its decomposition products are radioactive.
For many purposes it is not particularly necessary to separate the metals, but if separation into individual metals is required, the process is complex. Initially, the metals are extracted as salts from the ores by extraction with sulphuric acid (H2SO4), hydrochloric acid (HCl), and sodium hydroxide (NaOH). Modern purification techniques for these lanthanoid salt mixtures are ingenious and involve selective complexation techniques, solvent extractions, and ion exchange chromatography.
Pure gadolinium is available through the reduction of GdF3 with calcium metal.
2GdF3 + 3Ca → 2Gd + 3CaF2
This would work for the other calcium halides as well but the product CaF2 is easier to handle under the reaction conditions (heat to 50°C above the melting point of the element in an argon atmosphere). Excess calcium is removed from the reaction mixture under vacuum. | <urn:uuid:b6ea50f0-a78c-4d7f-9603-da93e9d005ae> | 2.890625 | 1,175 | Knowledge Article | Science & Tech. | 38.732673 | 95,511,764 |
Plate Coral - Green (Fungia sp.)
Family: Fungiidae (Stony Corals)
Habitat: Reef slopes and flats, often on sediment bottoms, in areas with weak water flow.
Light: High Water Flow: Medium Space: 50+ gal.
Reef Safe: Yes Care Level: Easy Temperament: Aggressive
Diet: These corals have zooxanthellae which provide much of their nutrition. It is believed they also feed on microzooplankton and directly absorb some nutrients from the water.
Natural History: The Fungi produce a flat, radially ridged skeleton that is slightly dome-shaped and usually oval. Juveniles often start on rock substrate but break off and settle on sand or rubble as an adult. They are often green, bright purple, blue, or red. These corals may decalcify a section of body to generate asexual offspring or fragment to do the same. They can move (12 inches per day) and flip over to right themselves by repeated inflation and deflation of tissue.
Husbandry: Plate Corals often grow in crowded communities with different Fungiid species because they do not sting each other. They must be handled with care and should be placed on a soft rubble bottom. Care must be taken to remove or blow away accumulating debris. Mucus emission can cause damage to unrelated corals so they should be located a safe distance from other unrelated species. Fungiids benefit from regular feedings. Their colonies can reach 12 inches across.
AKA: Disc Coral, Mushroom Coral, Tongue Coral, Fungus Coral, Chinaman Hat Coral
In Stock: 08/09/14, No
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CL-EMB (Embedded Common Lisp and template system) is a library for embedding Common Lisp and template tags into normal text files. It can be used for dynamically generating HTML pages.
CL-HTTP is suite of an HTTP 1.1 compliant and SSL-capable tools for creating Web applications written in ANSI Common Lisp that includes: A Sophisticated Server, A Programatic Client, A Caching Proxy, ...
CLHP (the Common Lisp Hypertext Preprocessor) allows, like PHP, to embed Lisp code into a valid XML or HTML document using XML processing instructions. "The CLHP parser is integrated into the Apache w...
A library for encoding and decoding (HTML/SGML/XML) entities in Common Lisp.
The lisp-cgi-utils is a software package for developing CGI scripts with Common Lisp. It implements a very basic HTTP/CGI interface (sending headers, getting GET/POST and environment variables) and of...
A library for transforming XML data into calls to Lisp-functions or macros. It can be used for analyzing and trasforming XML data, building HTML templating engines, or providing alternate Lisp syntaxe... | <urn:uuid:72cadcad-3547-4f4e-97f9-803f7a72ab9b> | 2.546875 | 295 | Content Listing | Software Dev. | 57.235055 | 95,511,771 |
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While the autumn season may be best known for brilliant views of changing foliage and a heavy dose of pumpkin, there are many weather threats that should be anticipated during the fall.
From early signs of winter to tropical development, people should prepare for a wide variety of different weather phenomena that occur during the fall season. Several of which can be notably dangerous.
Here are five weather threats to watch out for this season:
Severe weather ramps up in a secondary peak
Like in the spring, the fall is a changing season with an increase in the clash between cold, dry air and warm, humid air. This clash of air masses can help spawn the development of severe thunderstorms.
"The peak is not as strong in the spring, primarily because there’s not as much heat and humidity around during this part of the year," AccuWeather Senior Meteorologist Andy Mussoline said.
The secondary peak of severe weather typically lasts from October into November, he added.
There is a smaller number of tornadoes on average across the country during October and November, compared to April and May, according to the National Climatic Data Center (NCDC).
Based on an averaging period from 1991-2010, the NCDC reports that 155 tornadoes form during April, while a whopping 276 occur in May. That number drops to 61 in October and 58 in November. Still, while the number isn't as large, it's important that people are always prepared for a severe weather event.
Severe storms can encompass areas from from the Plains to the Ohio Valley and Southeast, because it's easier for warm and humid air to reach those areas. The threat can also reach the Northeast, but it's not as high, because the region is farther removed from widespread heat and humidity, Mussoline said.
Fog can dangerously reduce visibility
Fog can severely impact the visibility for motorists, which can increase accident risk and lead to travel delays. On average, more than 28,500 vehicles crashes occur in the United States each year due to fog, according to the Federal Highway Administration (FHWA).
Fog is also a frequent disruptor of air travel, forcing many airlines to delay flights until conditions improve. While fog is not strictly limited to the fall season, it does tend to increase this time of year.
“There is a significant increase in fog events during the fall primarily due to longer and cooler nights,” Mussoline said. “Fog typically develops during the overnight hours and lasts into the early- to mid-morning hours.”
Early frosts can damage plants
Frost can bring an abrupt and unwanted end to the growing season for sensitive plants.
"The most susceptible areas to early season frosts are rural areas; suburban areas can provide better protection to any early season intrusions of cold air," Mussoline said.
The pavement is typically warm inside most cities, and this can prevent early frost from occurring, but out in more rural areas, pavement is not as prevalent.
Early-season snowstorms can knock out power
Snow that falls during autumn can be heavy and wet instead of light and powdery. With more leaves that haven't fallen, there is more of a surface area for the snow to accumulate on the trees.
This adds more more weight to the trees, meaning they could be more susceptible to snapping or having branches fall off, according to Mussoline. This can cause damage when trees topple onto cars or homes. It can also mean travel delays when they fall onto roadways, or power outages when they drop onto power lines.
Twenty-four percent of weather-related crashes each year occur on snowy, slushy or icy pavement and 15 percent occur during snowfall or sleet, according to the FHWA.
Hurricane season continues until Nov. 30
The Atlantic hurricane season begins in June, and even though the peak occurs on Sept. 10, the Atlantic Basin can remain quite active up until the very end of November, when the season concludes.
A key factor in why tropical cyclones can develop so late in the year is that sea surface temperatures remain warm enough. The ideal temperatures for tropical development are in the upper 20s to 30 degrees Celsius (80-86 degrees Fahrenheit), according to AccuWeather Senior Meteorologist Jim Andrews.
Even if parts of the Atlantic begin to cool, there are areas close to the equator, such as in the Caribbean, that remain warm enough for tropical activity to occur well into the fall, Andrews said.
There have been several destructive storms that have caused hardship to millions during the latter part of the season, including most recently, Hurricane Matthew. These systems show why it's important for people along the Gulf and East coasts to remain prepared all the way through Nov. 30.
Here are three of the most notorious late-season storms to impact the U.S.:
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.
Twelve people were injured when a flying lava bomb punctured the roof of a lava tour boat, causing a large hole in the vessel.
While Trump and Putin met for a summit in Helsinki, Finland, on Monday morning, a message about climate change was hung from a church by an environmental activist group.
En promedio, 37 niños mueren anualmente al ser olvidados dentro de un auto.
The tournament is being held in eastern Scotland, a region which has a history of extreme weather that can create chaos for golfers and spectators.
Following a push of dry air during the middle part of this week, a humid and rather wet weather pattern is forecast to evolve over the eastern third of the nation during the latter part of July.
The ongoing Kilauea volcano eruptions in Hawaii have led to the formation of a tiny, new piece of land made of lava, which was initially considered to be an island.
An organizing tropical threat will heighten the risk for flooding from the Philippines to Vietnam and Laos into midweek.
A grueling heat wave caused at least eight deaths across Japan since Saturday, and the dangerous conditions are not forecast to subside through the duration of the week. | <urn:uuid:efefccf1-56d7-4a42-9056-d9beaf7f0a2a> | 3.3125 | 1,288 | Listicle | Science & Tech. | 44.939079 | 95,511,784 |
The Dark Energy Camera, or DECam, peers deep into space from its mount on the 4-meter Victor Blanco Telescope high in the Chilean Andes.
Thirty percent of the camera’s observing time — about 105 nights per year — go to the team that built it: scientists working on the Dark Energy Survey.
Another small percentage of the year is spent on maintenance and upgrades to the telescope. So who else gets to use the 570-megapixel DECam, built at the Department of Energy's Fermilab? Dozens of other projects share its remaining time.
Many of them study objects far across the cosmos, but five of them investigate ones closer to home.
Overall, these five groups take up just 20 percent of the available time, but they’ve already taught us some interesting things about our planetary neighborhood and promise to tell us more in the future.
Stony Brook University’s Aren Heinze and the University of Western Ontario’s Stanimir Metchev used DECam for four nights in early 2014 to search for unknown members of our solar system’s main asteroid belt, which sits between Mars and Jupiter.
To detect such faint objects, one needs to take a long exposure. However, the paths of these asteroids lie close enough to Earth that taking an exposure longer than a few minutes results in blurred images. Heinze and Metchev’s fix was to stack more than 100 images taken in less than two minutes each.
With this method, the team expects to measure the positions, motions and brightnesses of hundreds of main belt asteroids not seen before. They plan to release their survey results in late 2015, and an early partial analysis indicates they’ve already found hundreds of asteroids in a region smaller than DECam’s field of view—about 20 times the area of the full moon.
Whole new worlds
Scott Sheppard of the Carnegie Institution for Science in Washington DC and Chad Trujillo of Gemini Observatory in Hilo, Hawaii, use DECam to look for distant denizens of our solar system. The scientists have imaged the sky for two five-night stretches every year since November 2012.
Every night, the DECam’s sensitive eye captures images of an area of sky totaling about 200 to 250 times the area of the full moon, returning to each field of view three times. Sheppard and Trujillo run the images from each night through software that tags everything that moves.
“We have to verify everything by eye,” Sheppard says. So they look through about 60 images a night, or 300 total from a perfect five-night observing run, a process that gives them a few dozen objects to study at Carnegie’s Magellan Telescope.
The scientists want to find worlds beyond Pluto and its brethren—a region called the Kuiper Belt, which lies some 30 to 50 astronomical units from the sun (compared to the Earth’s 1). On their first observing run, they caught one.
This new world, with the catalog name of 2012 VP113, comes as close as 80 astronomical units from the sun and journeys as far as 450. Along with Sedna, a minor planet discovered a decade ago, it is one of just two objects found in what was once thought of as a complete no man’s land.
Sheppard and Trujillo also have discovered another dwarf planet that is one of the top 10 brightest objects beyond Neptune, a new comet, and an asteroid that occasionally sprouts an unexpected tail of dust.
Northern Arizona University’s David Trilling and colleagues used the DECam for three nights in 2014 to look for “centaurs”—so called because they have characteristics of both asteroids and comets. Astronomers believe centaurs could be lost Kuiper Belt objects that now lie between Jupiter and Neptune.
Trilling’s team expects to find about 50 centaurs in a wide range of sizes. Because centaurs are nearer to the sun than Kuiper Belt objects, they are brighter and thus easier to observe. The scientists hope to learn more about the size distribution of Kuiper Belt objects by studying the sizes of centaurs. The group recently completed its observations and plan to report them later in 2015.
Lori Allen of the National Optical Astronomy Observatory outside Tucson, Arizona, and her colleagues are looking for objects closer than 1.3 astronomical units from the sun. These near-Earth objects have orbits that can cross Earth’s—creating the potential for collision.
Allen’s team specializes in some of the least-studied NEOs: ones smaller than 50 meters across.
Even small NEOs can be destructive, as demonstrated by the February 2013 NEO that exploded above Chelyabinsk, Russia. The space rock was just 20 meters wide, but the shockwave from its blast shattered windows, which caused injuries to more than 1000 people.
In 2014, Allen’s team used the DECam for 10 nights. They have 20 more nights to use in 2015 and 2016.
They have yet to release specific findings from the survey’s first year, but the researchers say they have a handle of the distribution of NEOs down to just 10 meters wide. They also expect to discover about 100 NEOs the size of the one that exploded above Chelyabinsk.
Most surveys looking for “space junk” — inactive satellites, parts of spacecraft and the like in orbit around the Earth — can see only pieces larger than about 20 centimeters. But there’s a lot more material out there.
How much is a question Patrick Seitzer of the University of Michigan and colleagues hope to answer. They used DECam to hunt for debris smaller than 10 centimeters, or the size of a smartphone, in geosynchronous orbit.
The astronomers need to capture at least four images of each piece of debris to determine its position, motion and brightness. This can tell them about the risk from small debris to satellites in geosynchronous orbit. Their results are scheduled for release in mid-2015.
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Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
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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Site-directed mutagenesis (SDM) is one of the key tools researchers use to prove causation in molecular biology and genetics. It can be used to characterize the function of certain regions in a promoter or gene, as well as to study the effects of inactivating/activating mutations. In biomedical research, modeling patient mutations using SDM can help determine if a variant is causal for a given disease. CRISPR has made genomic SDM relatively straightforward, but plasmid-based SDM has lagged behind. While commercial kits are available for making small point mutations, large deletions/insertions require complicated, often costly in vitro assembly methods. A new method, REPLACR-mutagenesis, harnesses the power of bacterial recombineering to create insertions, deletions, and substitutions - at the same efficiency as Gibson Assembly and GeneArt cloning - but at a much lower cost. Read on to find out how to replace your SDM method with REPLACR (Recombineering of Ends of Linearized Plasmids After PCR). | <urn:uuid:150b983b-9ba6-424b-a048-e835006c7c09> | 3.140625 | 218 | News (Org.) | Science & Tech. | 23.691923 | 95,511,813 |
What is identity? Standard Identities
Consider the following equation:
2(x+3) = 2x+6
What can you say about the above equation? In LHS, if you substitute the value of x =3, you will get 12. Even in RHS if you will substitute the value of the variable x with 3, you will get 12 as the answer.
In mathematics, an equation P = Q is called an identity if the following conditions are satisfied:
- Both side of the equality relation contain some variables.
- Both the sides give the same value, when the variable is substituted with a particular constant.
If an equality relation satisfies above two conditions, it will be an identity. There can be many relations in mathematics which can be called identities, but we need not need to remember all of them. There are few standard identities which are important in algebra, which can make the calculations simple.
The standard identities (algebraic) are as follows:
(a + b)2 = a2 + b2 + 2ab
(a – b)2 = a2 + b2 – 2ab
(a + b)3=a3 + b3 + 3ab(a + b)
(a – b)3=a3 – b3 – 3ab(a – b)
(a + b + c)2=a2 + b2 + c2 + 2ab + 2bc + 2ca
Let us try to prove the first identity and see whether it is valid or not.
Consider the LHS, (a+b)2 = (a+b) x (a+b) = a(a+b)+b(a+b) = a2+ab+ab+b2 = a2 + b2 + 2ab
Let us try to prove the above equality relation in another way.
Consider a square of side (a+b) divided in the following rectangles and squares:
The total area is given as the sum of areas of each figure, i.e. a2 + ab + ab + b2 = a2 + b2 + 2ab, which is equal to RHS. Hence the identity is valid. Therefore, whatever is the method of proving the identity it will always be true.
The standard identities discussed above are the algebraic identities. These standard identities hold true for any value of the variable.
Practise This Question | <urn:uuid:57148e8d-2e0f-4e5a-b5f4-e8170e0e32f2> | 4.625 | 507 | Tutorial | Science & Tech. | 65.684848 | 95,511,815 |
Wetting, the process of water interacting with a surface, is critical in our everyday lives and in many biological and technological systems. The contact angle is the angle at the interface where water, air and solid meet, and its value is a measure of how likely the surface is to be wetted by the water. Low contact-angle values demonstrate a tendency of the water to spread and adhere to the surface, whereas high contact-angle values show the surface’s tendency to repel water. The most common method for surface-wetting characterization is sessile-drop goniometry, due to its simplicity. The method determines the contact angle from the shape of the droplet and can be applied to a wide variety of materials, from biological surfaces to polymers, metals, ceramics, minerals and so on. The apparent simplicity of the method is misleading, however, and obtaining meaningful results requires minimization of random and systematic errors. This article provides a protocol for performing reliable and reproducible measurements of the advancing contact angle (ACA) and the receding contact angle (RCA) by slowly increasing and reducing the volume of a probe drop, respectively. One pair of ACA and RCA measurements takes ~15–20 min to complete, whereas the whole protocol with repeat measurements may take ~1–2 h. This protocol focuses on using water as a probe liquid, and advice is given on how it can be modified for the use of other probe liquids.
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Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Reliable measurement of the receding contact angle: https://doi.org/10.1021/la400009m
Guidelines to measurements of reproducible contact angles using a sessile-drop technique: https://doi.org/10.1680/si.13.00010
Characterization of super liquid-repellent surfaces: https://doi.org/10.1016/j.cocis.2014.04.009
The protocol is the result of a procedure gradually developed since wetting research was begun in the R.H.A.R. group, and we acknowledge the contributions of H. Mertaniemi, T. Verho and M. Latikka. This work was supported by the European Research Council ERC-2016-CoG (725513-SuperRepel) and the Academy of Finland (Centres of Excellence Programme 2014–2019). X.T. is grateful for the support of the One Hundred Talents Program of SYSU and the One Thousand Youth Talents Program of China.
The minimum advancing drop volumes (= the recommended starting volume for the receding contact-angle measurement) needed to reach RCA at 10 µL (Fig. 6), were obtained by solving the Young–Laplace equation by numerical integration, using Python programming language with Scipy library. The shape and size of the drop for different pairs of contact angle and drop volume were solved using a code that is provided in this supplementary file | <urn:uuid:3d96087a-be64-4cda-9e2b-f897e599bccb> | 2.96875 | 694 | Truncated | Science & Tech. | 47.003812 | 95,511,829 |
|View script||License||Download documentation as: HTML or editable|
|Download script||History||Other scripts by: peterwood · sunanda|
Script Library: 1215 scripts
Documentation for: make-word-list.r
script: make-word-lisr.r title: List words in a string author: Peter W A Wood date: 2-Apr-2007 Version: 1.0.0
USAGE: make-word-list config content index-name /for-search ARGUMENTS: config -- changes to the default configuration (Type: object or none) (See below) content -- the string for which words are to be extracted REFINEMENTS: /for-search -- The character specified as the "not-prefix" is not removed from the front of words
1.1. configuration object
The configuration object used by make-word-list function provides almost complete control over what makes a word. You only need to supply changes not all the entries in the configuration object. For example, the following configuration object will only recognise words starting with "a"
my-config: make object! [ word-start: charset [#"a"] probe make-word-list my-config "aword bword cword dad"The result would be ["aword" "ad"] If you are happy with the default settings, you can supply none instead of a parameter object.
1.2. /for-search refinement
There are many different reasons why you may want to extract the words from a string. Two of the most common are:
The two uses may in your application need to behave slightly differently, especially with regard to handling the not-prefix. As an example, the default make-word-list function acts differently when given a string that contains tildes -- a leading tilde is preserved with the /for-search refinement:
>> make-word-list none "I have some ~tildes in t~~~his ~string~" == ["have" "i" "in" "some" "string~" "tildes" "t~~~his"] >> make-word-list/for-search none "I have some ~tildes in t~~~his ~string~" == ["have" "i" "in" "some" "t~~~his" "~string~" "~tildes"] | <urn:uuid:bad1706e-b607-478e-8817-d0b8e8b8f148> | 2.859375 | 506 | Documentation | Software Dev. | 52.193665 | 95,511,830 |
Python Exercise: Colon of a tuple
Python tuple: Exercise-8 with Solution
Write a Python program to create the colon of a tuple.
from copy import deepcopy #create a tuple tuplex = ("HELLO", 5, , True) print(tuplex) #make a copy of a tuple using deepcopy() function tuplex_clone = deepcopy(tuplex) tuplex_clone.append(50) print(tuplex_clone) print(tuplex)
('HELLO', 5, , True) ('HELLO', 5, , True) ('HELLO', 5, , True)
Visualize Python code execution:
The following tool visualize what the computer is doing step-by-step as it executes the said program:
Python Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus. | <urn:uuid:efad5a76-ebef-4b00-a3ab-e1f88f4b6d21> | 2.90625 | 194 | Tutorial | Software Dev. | 29.568653 | 95,511,843 |
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Edited By: L Trabaud and R Prodon
345 pages, 142 Figs, 42 tabs
The book gathers most of the papers presented at the Third International Workshop on Fire Ecology held in Banyuls-sur-Mer (France), October 2001. The articles are grouped under the following topics: The response of trees, especially the pines, to fire; The response of Mediterranean shrublands to wildfire or to prescribed burning; The biological and physiological processes that concern plants at the species level; The biological processes that take place after fire in the edaphic compartment; The responses and the recolonisation processes of animals; and Management and conservation issues.
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Biologists Discover New Species of Sharks
Local recreational fisherman Steve Downs has found two new rare species of sharks in Australia. The news was released by Shark biologist Ryan Kempster.
The researcher from the Oceans Institute of the University of Western Australia said that these species had been caught off two years back at Rottnest Island. The fisherman found these some 430 metres down in the water.
For two years, a thorough investigation has been conducted into the discovery. The investigation involved DNA sequencing of the species. Following the same, the two species have been identified as mandarin dogfish (Cirrhigaleus barbifer).
Kempster avowed that these species have not been seen in the country ever before. But, the discovery now would help them in comprehending the species in a much better way. The study has been published in the journal Marine Biodiversity Records.
It has been told that the mystery sharks under a metre long were male. Also, one was female, some 1.2 metres long. The female shark, according to Kempster, had 22 unborn pups. She was the second pregnant female specimen of this species ever.
"This species was known to be found only between Indonesia and Japan, and also New Zealand. It's not known why the sharks were found so far from their normal habitat", affirmed Kempster.
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A million-years-old rock is flying home.
The antique rock, named “Sayh al Uhaymir 008,” or “SaU008,” was once component of one of a meteorite that landed on Earth after blowing off from Mars millions of years ago.
SaU008 was discovered in Oman in 1999 and is the only one of 200 similar rocks that’s strong enough to withstand the journey back home, according to NASA.
“Every year, we give hundreds of meteorite specimens to scientists all over the world to for study,” Caroline Smith, the principal curator of meteorites at London’s Natural History Museum – which provided the rock, said in the press release. “This is a first for us: sending one of our samples back home for the advantage of science.”
The meteorite piece will head back to Mars as part of NASA’s Mars 2020 rover mission. Once it comes, SaU008 will be blown to bits in order to calibrate a high-precision laser named ‘SHERLOC’ that will be positioned on the rover’s robotic arm.
SHERLOC is being designed to examine rock and chemical features as fine as human hair and will need something to help it get its bearings on the alien planet. In the past, NASA has used rocks, metals and pieces of glass to assist adjust similar technology to its new martian surroundings.
But this time around, NASA thought it might be more effective to use something that already has the same composition as the planet SHERLOC is being designed to explore.
“We’re studying thing on such a fine scale that slight misalignments, caused by changes in temperature or even the rover settling into sand, can need us to correct our aim,” Luther Beegle, NASA’s principal investigator, said. “By studying how the instrument sees a fixed target, we can understand how it will see a piece of the Martian surface.”
Once the laser is adjusted, it will photograph rocks on Mars and use a UV light to consider and search for signs of life. | <urn:uuid:5bc5a77c-4121-4a84-a6ff-17c779cbcf7f> | 3.40625 | 447 | News Article | Science & Tech. | 48.349679 | 95,511,901 |
Authors: George Rajna
It is one of the greatest mysteries in the universe: Why is there so much more matter than antimatter? From the data collected by the LHCb detector at the Large Hadron Collider, it appears that the particles known as charm mesons and their antimatter counterparts are not produced in perfectly equal proportions. The OPERA experiment, located at the Gran Sasso Laboratory of the Italian National Institute for Nuclear Physics (INFN), was designed to conclusively prove that muon-neutrinos can convert to tau-neutrinos, through a process called neutrino oscillation, whose discovery was awarded the 2015 Nobel Physics Prize. The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) has completed the installation of a novel antineutrino detector that will probe the possible existence of a new form of matter. The MINERvA collaboration analyzed data from the interactions of an antineutrino—the antimatter partner of a neutrino—with a nucleus. The inclusion of short-range interactions in models of neutrinoless double-beta decay could impact the interpretation of experimental searches for the elusive decay. The occasional decay of neutrons into dark matter particles could solve a long-standing discrepancy in neutron decay experiments. The U.S. Department of Energy has approved funding and start of construction for the SuperCDMS SNOLAB experiment, which will begin operations in the early 2020s to hunt for hypothetical dark matter particles called weakly interacting massive particles, or WIMPs. Thanks to low-noise superconducting quantum amplifiers invented at the University of California, Berkeley, physicists are now embarking on the most sensitive search yet for axions, one of today's top candidates for dark matter.
Comments: 69 Pages.
[v1] 2018-07-02 06:26:33
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Simon's fundamental rich-gets-richer model entails a dominant first-mover advantage
Physical Review E, 95, , 2017
Abstract: Herbert Simon's classic rich-gets-richer model is one of the simplest empirically supported mechanisms capable of generating heavy-tail size distributions for complex systems. Simon argued analytically that a population of flavored elements growing by either adding a novel element or randomly replicating an existing one would afford a distribution of group sizes with a power-law tail. Here, we show that, in fact, Simon's model does not produce a simple power law size distribution as the initial element has a dominant first-mover advantage, and will be overrepresented by a factor proportional to the inverse of the innovation probability. The first group's size discrepancy cannot be explained away as a transient of the model, and may therefore be many orders of magnitude greater than expected. We demonstrate how Simon's analysis was correct but incomplete, and expand our alternate analysis to quantify the variability of long term rankings for all groups. We find that the expected time for a first replication is infinite, and show how an incipient group must break the mechanism to improve their odds of success. Our findings call for a reexamination of preceding work invoking Simon's model and provide a revised understanding going forward.
[edit database entry]
Bongard's work focuses on understanding the general nature of cognition, regardless of whether it is found in humans, animals or robots. This unique approach focuses on the role that morphology and evolution plays in cognition. Addressing these questions has taken him into the fields of biology, psychology, engineering and computer science.
Danforth is an applied mathematician interested in modeling a variety of physical, biological, and social phenomenon. He has applied principles of chaos theory to improve weather forecasts as a member of the Mathematics and Climate Research Network, and developed a real-time remote sensor of global happiness using messages from Twitter: the Hedonometer. Danforth co-runs the Computational Story Lab with Peter Dodds, and helps run UVM's reading group on complexity.
Laurent studies the interaction of structure and dynamics. His research involves network theory, statistical physics and nonlinear dynamics along with their applications in epidemiology, ecology, biology, and sociology. Recent projects include comparing complex networks of different nature, the coevolution of human behavior and infectious diseases, understanding the role of forest shape in determining stability of tropical forests, as well as the impact of echo chambers in political discussions.
Hines' work broadly focuses on finding ways to make electric energy more reliable, more affordable, with less environmental impact. Particular topics of interest include understanding the mechanisms by which small problems in the power grid become large blackouts, identifying and mitigating the stresses caused by large amounts of electric vehicle charging, and quantifying the impact of high penetrations of wind/solar on electricity systems.
Bagrow's interests include: Complex Networks (community detection, social modeling and human dynamics, statistical phenomena, graph similarity and isomorphism), Statistical Physics (non-equilibrium methods, phase transitions, percolation, interacting particle systems, spin glasses), and Optimization(glassy techniques such as simulated/quantum annealing, (non-gradient) minimization of noisy objective functions). | <urn:uuid:dd614358-61e0-4a93-a910-8c9b647fb1a3> | 2.671875 | 667 | Academic Writing | Science & Tech. | 8.204484 | 95,511,917 |
(01 The Primer Fields dynamics )
The Primer Fields dynamics
(02 Plasma sphere around the Sun )
The plasma physicist David LaPoint suggests that there is much more to the Primer Fields dynamics than what meets the eye. He suggests that our sun operates within a sphere of highly concentrated plasma that is generated by powerful magnetic fields, which he calls the " Primer Fields," and that the plasma sphere around the Sun is magnetically confined by these fields.
If this was not so, our sun would be but a dim speck in the sky, without the large magnetic fields acting on it that surround it with a sphere of concentrated plasma. The Earth would be a cold planet then, extensively covered with ice, as it once was 700 million years ago. But is David LaPoint correct? Do they Primer Fields really exist outside the laboratory environment? Can they be seen? And if they do exist and are visible, is it possible for these vital fields to collapse?
So, let's explore what stands behind it all.
(03 David LaPoint uses two bowl-shaped magnets )
The key component of the Primer Fields theory is the existence of one or two bowl shaped electromagnetic fields. David LaPoint uses two bowl-shaped magnets of opposite magnetic polarity for his experiments conducted in a vacuum chamber.
(04 The Zeta Pinch effect )
In the environment of space, however, no bowl-shaped magnets hang in the sky. For the required magnetic fields to exist, they must be generated by the natural phenomenon of electricity flowing as plasma in space. And this is exactly what happens.
The term, plasma, refers to electrically charged particles that exist in free flowing form in space, primarily as protons and electrons, the stuff that atoms become made of when they are bound together. In space they are free flowing. However, flowing electricity creates magnetic fields, and by these fields the flowing electricity becomes pinched together.
When electricity is carried by two parallel wires, with the current flowing in the same direction, the wires are attracted to each other by the Lorentz force. The same happens in plasma in space where electricity is flowing freely without wires. Here the effect is called the Zeta Pinch effect.
(05 Plasma currents in space become compressed )
In space the flowing electric plasma particles are drawn to each other by th same magnetic forces that attract wires to each other. However while the wires remain physically fixed, plasma currents in space become compressed into ever-smaller magnetic confinement. By the confinement the current density is increased, which in turn pinches the plasma currents still tighter and tighter, forming a bowl-shaped magnetic field in the process at the very end of the pinched plasma stream.
(06 Electromagneticly confined 'high-density' plasma On the platform of the Primer Fields )
But something happens in the bowl when the plasma currents exceed a critical limit, as they converge to ever-tighter confinement. The currents and the resulting magnetic fields become unstable by the pinch effect, past a critical point. The currents become 'twisted into complex knots' whereby the bowl-shaped magnetic field that forms, opens up at the center. There, below the opening, an electromagneticly confined 'high-density' plasma stream is formed by a number of interacting effects.
On the platform of the Primer Fields the entire structure that we see that extends across 50 kilometers from top to bottom, forms in a fraction of a second. Typically the sprite remains active for about a single second, until the plasma flow becomes too weak to maintain the Primer Fields. At the point when the Primer Fields collapse, the entire structure simply vanishes.
(07 Interglacial period of the Sun's active time )
In comparing the sprite with the larger scale of the solar system, the sprite's one second active time is comparable to the solar system's interglacial period of the Sun's active time of roughly 12,000 years. The on-off process is the same in both cases, though different in scale.
(08 Let me illustrate now how the process functions )
Let me illustrate now how the process functions that forms the Primer Fields.
(09 Dense Plasma Focus Device )
'This is best illustrated by looking at another lab experiment, that is carried out with an instrument called the, Dense Plasma Focus Device. '
(10 A ring of electrodes )
The device is made up of a ring of electrodes that surround a hollow electrode at the center.
(11 A plasma sheet forms )
When an electric field is applied, a plasma sheet forms.
(12 The plasma sheet )
The plasma sheet is instantly drawn towards the opening of the central electrode, and is then drawn into it.
(13 The plasma becomes extremely pinched )
By it being drawn into the opening, the plasma becomes extremely pinched together.
(14 It becomes unstable )
There, it becomes unstable and begins to twist.
(15 The plasma twists itself into a spiral )
At first, the plasma twists itself into a spiral.
(16 Then the spiral becomes compacted )
Then the spiral becomes compacted.
(17 The more unstable the spiral becomes )
The more it becomes compacted the more unstable the spiral becomes, and becomes twisted.
(18 The twisting forms a complex knot )
Eventually, the twisting forms a complex knot.
(19 From a video about the Dense Plasma Focus Device )
The illustrations are snapshots taken from a video about the Dense Plasma Focus Device.
(20 A high-density plasma concentration forms )
In space the plasma instabilities that form the complex knots open the magnetic bowls that form at the end of the concentrated plasma currents. As the process unfolds further, a high-density plasma concentration forms outside of the magnetic holes. That's where the sun is located in a solar system and is powered thereby.
(21 When the plasma streams are too weak )
When, however, the plasma streams are too weak to cause an extreme pinch effect to happen, the plasma streams simply flow through the solar system without activating anything. The Sun thereby remains dim and not actively powered.
(22 When the Sun is powered )
When the Sun is powered by a dense plasma sphere surrounding it, the flow-through process still happens. Plasma flows out of the plasma sphere, since the Sun utilizes only a small portion of it. In the outflow another magnetic field is generated, but with the opposite polarity. The evidence suggests that all large electromagnetic structures that exist in space, when they are drawn to a sun, or on the larger scale to a galaxy, whereby the Primer Fields form, exist typically in complementary pairs.
(23 A number of interesting effects )
Between the two giant complementary electromagnetic bowls, a number of interesting effects come to light with interesting principles that are critical for the overall dynamic interactions.
(24 In the narrow space between )
The magnetic fields are the strongest at the focal point of the bowl-shaped magnetic structures. In the narrow space between the two complementary structures lies typically a solar system with a sun, or several suns, on the central axis, and with the planets orbiting on a thin ecliptic plain in the space between the two electromagnetic bowl-type fields.
(25 Two bowl-type electromagnetic fields work together )
While the two bowl-type electromagnetic fields are each separate entities, they work together functionally as a whole.
Their function is to concentrate the plasma flows that pervade all space and focus them into a tightly confined sphere in which our sun is located and is powered by it.
(26 A polarity flip point )
The remarkable concentration is accomplished in the laboratory by a set of two bowl-type structures, shown in red and blue, facing one-another with opposite (complementary) polarities.
The small point in the middle between the two magnetic bowl structures is where a polarity flip point is located. The flip point appears to be responsible for flipping the polarity of the Sun's magnetic field with every solar cycle.
The location of the flip point moves slightly when one of the two bowl structures becomes weaker than the other. This effect causes the polarity of the magnetic field of the Sun to assume the dominant polarity, and thus flip with the 11-year solar cycles that are simply resonance cycles between the complementary magnetic structures.
(27 Three functional magnetic elements )
The plasma concentration that is required for the Sun to function is dynamically produced in the illustrated structure by the interaction of its three functional magnetic elements that are structured around the respective hole in the magnetic bowls.
(28 Each has a specific function to fulfill )
Each of the three structures has a specific function to fulfill. The flip ring flips the orientation of plasma. It flips it under the magnetic confinement dome, while the choke ring below helps to keep it there.
(29 The flip ring )
The plasma particles that flow into the big red bowl are flipped upwards as they pass the flip ring (yellow). They are collected together there into a massive accumulation. The plasma particles become concentrated by this process. The concentration creates a 'high-pressure' environment.
(30 The magnetic choke ring )
The magnetic choke ring, within the opening of the magnetic bowl, focuses the 'escaping' plasma flow into a tightly concentrated stream beneath the hole. In some lab experiments, the focused stream expands into a sphere.
(31 The out-flowing stream )
When plasma is drawn out of the sphere in the flow-through process, a complementary bowl structure is formed with opposite orientation and opposite magnetic polarity. In this structure the out-flowing stream of lesser density is drawn into the bowls where expands in the reverse process, reverting back to the 'normal' density of the prevailing plasma stream.
The process that is illustrated here can be verified with laboratory experiments.
(32 A high-power plasma experiment )
In a high-power plasma experiment of the type that is conducted at the Los Alamos National Laboratory, the complementary bowl structure that the plasma currents form by their own interaction, is clearly visible. Also the containment dome that forms inside the bowls is visible in the experiment that is illustrated here.
In this particular experiment the magnetically focused plasma stream that flows between the bowls, did not form a sphere, for which a catalyst would be required, but it did form a distinct plasma ring around the focused stream, centered between the bowls.
(33 Archetypal drawings )
Evidence exists that the lab-created shape of plasma formed by the Primer Fields, was visible in ancient time in the sky. Archetypal drawings collected from widely separated regions on earth, show a remarkable similarity of their design with the lab-created plasma formations. The similarity suggests that the complementary plasma bowl shapes were common occurrences at one time, appearing and disappearing in the skies like so many UFO sightings today, or like the sprites still do under special conditions.
(34 The plasma jets )
David LaPoint also discovered two more features of the Primer Fields, for which widely known evidence exists, which are the plasma jets and the magnetic flip point. He discovered that when the plasma pressure under the confinement dome becomes too great, the dome will rupture at its weakest point, by which excess plasma escapes in a burst until the rift closes up again under the resulting lower pressure. By this plasma venting process the magnetic strength of the respective bowl structure weakens somewhat. The resulting imbalance shifts the convergence of the magnetic fields, and with it it shifts a magnetic flip point that David LaPoint also discovered, forms below the opening of the magnetic bowl.
(35 The 11-year solar cycles )
In the case of the solar system the resulting imbalance, which shifts the flip point, flips the Sun's magnetic field at the high point of the 11-year solar cycles are thereby recognized to be simply resonance cycles that oscillate between the two complementary electromagnetic structures of the solar system.
(36 Operation of the Red Square Nebua )
What the complete Primer Fields system that powers our solar system and the sun may look like in practice, can be seen illustrated in the operation of the Red Square Nebua that can serve as a model for this purpose. In this model we see all the essential features of the Primer Fields system clearly visible.
(37 Two complementary bowl-type structures in operation )
We see the two complementary bowl-type structures in operation. One concentrates the galactic plasma streams like a funnel. In the funnel we can see the flip ring, and below it the choke ring, below which a cone of concentrated plasma extends that focuses onto a sun, or a number of them. And we see the reverse happening for the outgoing plasma stream.
(38 Observed in a laboratory plasma-flow experiment )
We can see all the essential features reflected here that have been observed in a laboratory plasma-flow experiment.
(39 Our galaxy, when it is observed as a whole )
Our galaxy, when it is observed as a whole, also operates on essentially the same dynamic platform, though on a vastly larger scale than a solar system.
(40 The center of the galaxy )
But here too, we see unmistakable evidence of two complementary electromagnetic bowls that form highly condensed plasma concentrations under their respective confinement domes.
The concentration is visible in x-ray and gamma-ray emissions. We can also see the the extremely concentrated plasma sphere below the confinement domes and between the two bowl structures that are indicated by the existence of the confinement domes. The concentrated plasma sphere is also the center of the galaxy.
(41 Large intergalactic plasma streams )
Large intergalactic plasma streams feed into and out of the Primer Fields that form the confinement domes.
(42 Two long intergalactic connecting streams )
These two long intergalactic connecting streams, one incoming and one out-going, both have very long resonance cycles.
(43 very long electric resonance cycles )
These very long electric resonance cycles that correspond to the long distances between the galaxies, evidently affect the strength of the Primer Fields that power the galaxy, and are thereby the cause for the two long climate cycles that have been observed on Earth.
(44 Very long electric resonance cycles )
These very long electric resonance cycles - the sixty-two million year cycle, and the hundred-forty million year cycle - show up as long climate cycles that have been preserved in sediment records that enable us to look back in time more than 500 million years.
(45 Both near their minimum point )
Presently, the two very long climate cycles are both near their minimum point, whereby the weak plasma conditions have been created that have gripped the Earth for the last two million years, in which the ice ages happened.
(46 Breakdown of the Primer Fields )
During these weak conditions that have been slowly developing for the last five million years, which are getting still weaker, the breakdown of the Primer Fields that power our solar system has become a regular occurrence during the weakest times.
(47 The Primer Fields cannot form )
Then, when the plasma streams that flow through the solar system become so weak that they drop below a threshold, a point is reached when the pinch effect in the plasma streams is no longer strong enough to twist the plasma currents into knots to create the bowl-type magnetic structures with the void at the center that make up the Primer Fields. And so the Primer Fields cannot form. What once existed, suddenly exists no more.
(48 The Sun becomes inactive, dim, and cold )
The plasma currents become no longer concentrated then, but simply flow through the solar system without becoming focused around the Sun.
At this point the Sun simply turns off. It becomes inactive, dim, and cold. An Ice Age begins.
(49 The Pleistocene Epoch )
The ice ages didn't last as long in the earlier phase of the weakening conditions. They lasted only 41,000 years then. As the general weakening continued, the 100,000 years long ice ages began. This became named the Pleistocene Epoch.
Throughout the ice ages, in which the Primer Fields fail, the Sun becomes inactive for long periods. It becomes a dim yellow star that glows mostly by its stored up energy and whatever nuclear decay may be ongoing within it.
(50 The Sun remains not totally shut down )
However, evidence exists that the Sun remains not totally shut down during the long ice age glaciation periods, which typically last 100,000 years. The Earth would turn into a snowball if the Sun would remain inactive for 100,000 years. Fortunately, this doesn't happen. Periodically short pulses of high-density conditions do occur during the ice ages, which re-invigorate the plasma streams that enable the Primer Fields to form anew, whereby the Sun to becomes powered again. Unfortunately these pulses are short in duration. The Sun remains powered by these pulses for only a few decades, and then turns off again.
(51 The Dansgaard-Oeschger oscillations )
Evidence exists that these pulses occurred on a fairly regular basis. Their occurrence has created large climate oscillations. Evidence has been detected in ice core samples drilled from the Greenland ice sheets that these short periods when the Sun becomes active again, have occurred in intervals of 1470 years. The resulting oscillations have been named, the Dansgaard-Oeschger oscillations. | <urn:uuid:cc2e33f4-19e9-48bb-be99-7fc7596766aa> | 3.1875 | 3,580 | Knowledge Article | Science & Tech. | 39.298617 | 95,511,929 |
Real-life science closes in on Star Trek as scientists show they can to hack into blind people's visual cortex to let them 'see'
In Star Trek: The Next Generation, their congentially blind engineer, Jordy LaForge, is able to see thanks to a visor worn across his eyes.
Now, thanks to an Israeli team, real-life technology has taken one more step to catching up with science fiction.
They have shown that an amazing device can use sound to hack into the visual cortex of blind people to let them 'see'.
Dr Amir Amedi, left, models his Sensory Substitution Device, which looks remarkably like the visor work by Star Trek character Jordy La Forge, right
The Sensory Substitution Device, invented over 20 years ago by Dutch researcher Dr Peter Meijer, uses an algorithm to translate the position and appearance of an object into distinct tones.
With only a brief period of training, users can learn to interpret the 'soundscape' to show them the shape, location and position of people or objects, and even read written words.
Now, a team led by Dr Amir Amedi from the Hebrew University in Jerusalem has shown that the sounds created actually activate the visual cortices of congenitally blind people, giving them the opportunity to see, after a fashion.
Writing in the current issue of the journal Cerebral Cortex, Dr Amedi and his team tell how previous research has indicated that the visual cortex organizes data into two parallel pathways.
The 'what' pathway, known technically as the ventral occipito-temporal pathway, deals with form, identity, and color.
The dorsal occipito-parietal pathway. or the 'where/how' pathway, focuses on object location and coordinates visual data with motor function.
Brain hacking: This graphic shows how the Sensory Substitution Device works to give blind people a sense of sight
Amazingly, MRI scans showed blind people using Dr Meijer's device activated these pathways the same as people with normal vision would, showing that this separation of tasks in the visual cortex doesn't actually need eyesight to form.
'The brain is not a sensory machine, although it often looks like one; it is a task machine'
The discovery builds on previous work by the team which showed braille readers show activity in precisely the same part of the brain that lights up when sighted readers read.
In a statement, Dr Amedi argued that this means: 'The brain is not a sensory machine, although it often looks like one; it is a task machine.'
According to io9.com, the Isreali study is just one of several recently published to suggest that actual visual, auditory, or tactile data aren't necessary for the brain to interpret what is going on around it.
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2002 Outbreak May Claim 10,000 Harbor Seals
A researcher gathers samples from this summers outbreak along the Swedish west coast.
Photo by: Tero Härköne, Göteborg University.
Scientists from Göteborg University in Sweden and the Woods Hole Oceanographic Institution (WHOI) report in an upcoming issue of the journal Ecology Letters that the 2002 outbreak of phocine distemper virus, or PDV, in European harbor seals may reduce the population by more than half and that future outbreaks with similar characteristics would significantly increase the risk of population declines. Their findings are the first epidemiological data reported on the 2002 outbreak, which is still underway, and may help predict the recurrence of the outbreaks and the impact on the long-term growth and survival of the European harbor seal population.
The current outbreak of PDV, also called the seal plague, was first identified in May 2002 when large numbers of dead seals were reported in Denmark. By mid-September the number of deaths had passed 6,000 in Denmark and had spread to the Baltic, the Wadden Sea and East Anglia. A 1988 outbreak from the previously undescribed virus spread from Denmark to Sweden, the Netherlands and then to England, Scotland and Ireland, in what is now believed to be the largest such event in any marine mammal population. Within seven months all major European harbor seal colonies had been affected by the virus, although the death rate varied from 15 to 58 percent among regions. The virus is thought to have been introduced to the European harbor seal population by migrating harp seals observed in Danish waters in 1987 and 1988. No outbreak of the virus had been reported since 1988 until this year.
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- Digital Press Kit – Unmanned Aircraft Systems Traffic Management Tests
Digital Press Kit – Unmanned Aircraft Systems Traffic Management Tests
- SOFIA to Study Southern Skies in New Zealand
The Stratospheric Observatory for Infrared Astronomy, SOFIA, is heading to Christchurch, New Zealand, to study the skies over the Southern Hemisphere. | <urn:uuid:4bcfb5a4-69f4-468e-a84a-7d233fceb177> | 2.609375 | 464 | Content Listing | Science & Tech. | 15.577297 | 95,511,992 |
The first report of a bacterium whose genome contains man-made DNA building blocks opens the door for tailor-made organisms that could be used to produce new drugs and other products.
All living creatures have a DNA "alphabet" of just four letters, which encode instructions for the proteins that perform most of the key jobs inside cells. But expanding that alphabet to include artificial letters could give organisms the ability to produce new proteins never seen before in nature.
The man-made DNA could be used for everything from the manufacture of new drugs and vaccines to forensics, researchers say.
"What we have done is successfully store increased information in the DNA of a living cell," study leader Floyd Romesberg, a chemical biologist at The Scripps Research Institute in La Jolla, California, told Live Science. Yet many steps remain before Romesberg and his colleagues can get cells to produce artificial proteins.
The field of synthetic biology involves tinkering with DNA to create organisms capable of novel functions in medicine, energy and other areas.
The DNA alphabet consists of four letters, or bases: adenine, thymine, guanine and cytosine (A, T, G and C). Adenine pairs with thymine, and guanine pairs with cytosine. RNA is a genetic material similar to DNA, except it has a different chemical backbone and replaces the base thymine with uracil (U).
Living things translate DNA into proteins through a series of steps. First, enzymes "transcribe" the DNA into RNA. Then, structures called ribosomes translate the DNA into proteins, which are made up of strands of molecules called amino acids.
Ultimately, the researchers aim to create organisms that can produce artificial proteins. But first, they need to show that the DNA containing the man-made letters can be transcribed into RNA, and that this RNA can be translated into proteins.
In the study, Romesberg and his team created an new pair of DNA letters not found in nature and inserted the pair into cells of Escherichia coli bacteria. Getting the DNA into the cells is not easy, but the researchers were able to do it by way of a transporter, a protein that moves materials across cell membranes.
Inside the cells, the man-made DNA got spliced into a plasmid, a circular piece of DNA found in bacteria. The plasmids replicated, without rejecting the foreign DNA or affecting the cells' growth, the researchers reported.
Now that the scientists have demonstrated an organism can incorporate artificial DNA letters into its genome, the next step will be showing it can convert the DNA into new proteins, which could be used to produce better drugs.
Proteins have become an important new type of drug, because cells can do the work of making them and because molecular biology techniques can be used to help proteins "evolve" to have desired properties, Romesberg said. But proteins are limited to only 20 building blocks, known as amino acids.
"Compare this to a medicinal chemist, who explores a much greater diversity of structures in the small-molecule drugs they synthesize," Romesberg said. "We hope to be able to combine the best of both small-molecule and protein drugs."
The research paves the way for "designer" organisms with custom-made genomes that are capable of performing useful tasks, like making drugs. Already, researchers have created the first "synthetic organisms" — artificial bacteria and yeast — which have man-made DNA sequences in their genomes.
The researchers are now working on expanding the DNA alphabet of yeast cells, and eventually hope to do the same for mammalian cells, which have properties that make them better at producing protein drugs. Expanding the genetic alphabet of an entire multicellular organism such as a human wouldn't be possible with the current technique, however, because the artificial letters must be directly inserted into each cell, Romesberg said.
- 'Grandmother' Cells in the Brain Could Help the Body Shake Off Jet Lag
- Possible Oldest Fragment of Homer's 'Odyssey' Discovered in Greece
- You've Probably Never Heard of This STD. It Could Become the Next Superbug.
- NASA Discovered Evidence of Life on Mars 40 Years Ago, Then Set It On Fire
This article originally published at LiveScience here | <urn:uuid:569cd06d-a2de-4616-b61d-8bb3ed65b492> | 3.90625 | 893 | Truncated | Science & Tech. | 34.634206 | 95,511,998 |
The SQL standard specifies a huge number of keywords which may not be used as the names of tables, indices, columns, databases, user-defined functions, collations, virtual table modules, or any other named object. The list of keywords is so long that few people can remember them all. For most SQL code, your safest bet is to never use any English language word as the name of a user-defined object.
If you want to use a keyword as a name, you need to quote it. There are four ways of quoting keywords in SQLite:
‘keyword’ A keyword in single quotes is a string literal. “keyword” A keyword in double-quotes is an identifier. [keyword] A keyword enclosed in square brackets is an identifier. This is not standard SQL. This quoting mechanism is used by MS Access and SQL Server and is included in SQLite for compatibility. `keyword` A keyword enclosed in grave accents (ASCII code 96) is an identifier. This is not standard SQL. This quoting mechanism is used by MySQL and is included in SQLite for compatibility.
For resilience when confronted with historical SQL statements, SQLite will sometimes bend the quoting rules above:
Programmers are cautioned not to use the two exceptions described in the previous bullets. We emphasize that they exist only so that old and ill-formed SQL statements will run correctly. Future versions of SQLite might raise errors instead of accepting the malformed statements covered by the exceptions above.
SQLite adds new keywords from time to time when it takes on new features. So to prevent your code from being broken by future enhancements, you should normally quote any identifier that is an English language word, even if you do not have to.
The list below shows all possible keywords used by any build of SQLite regardless of compile-time options. Most reasonable configurations use most or all of these keywords, but some keywords may be omitted when SQL language features are disabled. Regardless of the compile-time configuration, any identifier that is not on the following 124 element list is not a keyword to the SQL parser in SQLite:
25 de junho de 2018
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Students in St. Louis and southern Mississippi will get to ask questions of NASA astronauts on the I [...]
Nearly two months after Orbital ATK, now part of Northrop Grumman, delivered several tons of supplie [...]
NASA has selected six women and men to join the elite corps of flight directors who will lead missio [...]
Next week astronauts aboard the International Space Station will host several downlinks as part of N [...]
A Russian cargo ship loaded with almost three tons of food, fuel and supplies is set to launch to th [...] | <urn:uuid:10d13990-9290-4fcb-be2a-70e2e1a5edbc> | 3.03125 | 823 | Content Listing | Software Dev. | 59.160921 | 95,512,008 |
The Inverse Square Law states that the power of such things like electromagnetic radiation, acoustic energy, gravity, etc. is inversely proportional to the distance from the source of the radiation.
As light leaves a point source it travels in linear waves that are, in effect, perpendicular to the source. As the light travels away from the source it becomes increasingly less bright. Inverse Square Law tells us that the intensity of light produced, drops inversely proportional to the distance squared.
So: Final Intensity in lumens= Initial Lumen Intensity/(Distance from Source) squared. L=L1/(D^2), where L=Lumens on stage, L1=Initial output, D=Distance
If lamp produces 16 lumens of light at 1 foot, at 2 feet it produces 4 lumens, at 4 feet it produces 1 lumen... by 10 feet it produces only 0.16 lumens.
This is a real problem if your stage is 100 feet from your lighting position. lighting instruments are designed to produce extremely high initial light output using reflection (mirrors), refraction (lenses), and really high lumen output lamps.
Instruments with tighter beam angles produce a higher lumen output than instruments with wide beam angles. This is due to the higher concentration and uniform directionality of the beam of light. Thus, if you hung a 50˚ fixture next to a 5˚ fixture and both are the same distance from the stage, are the same fixture type (e.g., both are source fours), and have the same lamp in them, the 5˚ will be brighter.
This same inverse square principle holds true for acoustic energy whether it be emitted by an instrument, speaker, person, etc. The [[Sound Pressure Level]], measured in [[Decibels]] (dB-SPL), at the point of measurement is equal to the original SPL level divided by the square of the distance to the source. Thus SPL=SPL1/(D^2).
Sound can also behave as an inverse proportion, so someone might want to check my accuracy here.
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- Created by | <urn:uuid:b9fb9f2b-7c69-4833-8d11-fb9c28d05a21> | 3.78125 | 446 | Knowledge Article | Science & Tech. | 56.728754 | 95,512,045 |
Linac Coherent Light Source (LCLS)
A special issue of a physics publication highlights the contributions of SLAC's X-ray laser and the few similar lasers around the globe in probing the interaction of light and matter at the scale of atoms and electrons.
Crews will install a powerful new instrument, start assembling a new "self-seeding" system that will focus soft X-ray laser pulses into a bright, narrow band of colors, and upgrade several laser systems during two months of routine downtime at SLAC's Linac Coherent Light Source (LCLS) X-ray laser.
In a new state-of-the-art lab at SLAC National Accelerator Laboratory, components of ribosomes – tiny biological machines that make new proteins and play a vital role in gene expression and antibiotic treatments – form crystals in a liquid solution.
Signs at the lab's entryway warn of the potential for contamination – these delicate samples can be damaged by human touch, a sneeze or a dust particle.
A high-energy SLAC laser that creates shock waves and superhot plasmas needs to cool for about 10 minutes between shots. In the meantime, the rapid-fire pulses produced by SLAC's Linac Coherent Light Source X-ray laser, which probes the extreme states of matter produced by this initial laser shot, are unused. | <urn:uuid:735f51d1-05fe-484c-983f-59922c68bf37> | 2.921875 | 281 | News (Org.) | Science & Tech. | 30.078333 | 95,512,061 |
Coupling and Cohesion are two properties that deserve your attention when you design software. These are important because they have a direct effect on how.
Software Engineering What is the meaning of 'high cohesion one of my professors used to say that we have to strive to achieve Low coupling and high cohesion.
I'm trying to boil down the concepts of coupling and cohesion to a concise is Bertrand Meyer's Object Oriented Software Construction. Regarding 'coupling.
The literary meanings of word cohesion are consistency and organization of different units. In computer science and software engineering, cohesion refers to the.
High Cohesion, Loose Coupling. High Cohesion. Cohesion in software engineering is the degree to which the elements of a certain module belong together.
Software Design Questions and Answers Modularity Principles Coupling c) Cohesion d) Software Design Questions and Answers.
A definition of cohesion and coupling as it pertains to software, Software Vs. Game Development What to Do When You Don't Feel Like Writing and You Have.
We mention Cohesion vs Coupling when we are talking about Software Design Principles. Those two principles were first introduced in the book Structured Design.
Cohesion The cornerstone of Software Design. The term cohesion (alongside coupling) when writing business rules in a commercial application. | <urn:uuid:1014b5f8-9d08-49a9-9f3d-ba827f1d264b> | 3.03125 | 266 | Content Listing | Software Dev. | 36.263599 | 95,512,089 |
Thanks to these measurements, obtained by the eight PEACE electron sensors onboard the four spacecraft, scientists now have their first insight into magnetic reconnection's detailed behaviour.
Magnetic reconnection is a process that can occur almost anywhere that a magnetic field is found. In a reconnection event, the magnetic field lines are squeezed together somehow and spontaneously reconfigure themselves. This releases energy. When it occurs near the surface of the Sun, such an event powers giant solar flares that can release thousands of millions of tonnes of electrically charged particles into space.
The Earth's magnetic field creates a buffer zone, the magnetosphere, between our planet's atmosphere and the particles released during these eruptions. The Sun also releases a steadier flow of charged particles called the solar wind. On the large-scale, any heading this way buffet the magnetosphere, and are deflected by it. Plasma physicists describe this behaviour with a theory called 'magneto-hydrodynamics' (MHD).
On smaller scales, however, the picture becomes rather more complicated. The particles can actually flow across the magnetic field lines.This makes the mathematics of the behaviour more difficult. First to misbehave are the ions (positively charged particles). These break away from simple MHD on scales of less than a few hundred kilometres. On even smaller scales, less than 10 kilometres, the electrons (negatively charged particles) begin playing by other rules, too.
The new Cluster measurements reveal the electric field on the scale of a few hundred kilometres. "This is the first ever measurement of this term," says Paul Henderson, from University College London's Mullard Space Science Laboratory, UK, who led the investigation.
On 17 August 2003, Cluster was flying high above the night-time hemisphere of the Earth with an average separation of 200 kilometres between spacecraft. Data from several instruments shows that at 18:00 CET, a reconnection event took place and swept across the spacecraft.
Using data from Cluster's Plasma Electron and Current Experiment (PEACE) Henderson and collaborators calculated the pressure of electrons at each spacecraft and then calculated the difference between them and the variation with time. Using these quantities they calculated the electric field present near a reconnection site.
"This is an impossible calculation to make without four spacecraft," says Henderson. Now that the scientists can calculate the electric field in such a way, they have a new window into the process of magnetic reconnection.
Magnetic reconnection within Earth's magnetosphere regularly takes place on the night-time side of our planet, where the flow of the solar wind stretches out the magnetic field into a long tail. When the field reconnects in this region, it triggers jets of energetic particles that can cause auroral lights but can also damage satellites.
This new Cluster result takes scientists a step closer to seeing the precise details of magnetic reconnection. "When you think that the magnetosphere stretches over a million kilometres through space, we are actually looking at a minuscule part of it," says Henderson.
And that's exactly what plasma scientists want – the microphysics.
Philippe Escoubet | alfa
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 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science | <urn:uuid:53427f09-8f24-48db-b564-f270c4fedf11> | 3.96875 | 1,283 | Content Listing | Science & Tech. | 35.880524 | 95,512,109 |
As additional carbon pollution continues to trap more and more heat in the atmosphere, the higher temperatures that result can come with a hef…
"South Florida is at risk particularly because their bedrock is porous. There are really high stakes here."
The global ocean conveyor belt is slowing down, impacting climate, sea levels and marine life.
Here’s how climate change may affect rapidly intensifying hurricanes.
Before the end of this century, the cherry blossoms in Washington, D.C. may bloom a month earlier on average than they do today.
These images show long-term sea level rise stakes for the Caribbean.
Winter is losing its cool. See how much milder the coldest night of the year will be by mid-century.
Sea level rise from climate change poses threats to Philadelphia, including most of its airport.
Following a year of weather extremes, disasters and policy clashes, we asked our readers to help us pick out the most important climate storie…
Antarctic ice sheet models double the sea-level rise expected this century if global emissions of heat-trapping pollution remain high.
Watch how lake effect snow is expected to change in the coming decades.
Here's how rising seas could grow FEMA floodplains.
Communities in danger of falling into the sea say assistance from the federal government has dried up.
A federal court has scuttled a plan to cut one of the most powerful climate pollutants on earth.
Economic, emissions and population trends point to a very small chance Earth will avoid warming more than 2°C.
The Southwest's monsoons are becoming more intense, even as less rain falls on average.
Cities are already suffering from the impacts of extreme heat. It'll only get worse as the climate changes.
Climate Central has developed a new tool that brings the reality of future heat to hometowns across the U.S.
Here's how the number of days with extreme heat will rise in the second half of the century.
Heat and humidity will reach deadly extremes in South Asia if greenhouse gas emissions aren't curtailed. | <urn:uuid:6cc7be3a-dd42-444b-b53b-f495c6067f88> | 3.140625 | 431 | Content Listing | Science & Tech. | 51.1175 | 95,512,113 |
Study highlights threat of intense tropical cyclones hitting East Asia
The intensity of tropical cyclones hitting East Asia has significantly increased over the past 30 years, according to a new study published today.
The coastlines of China, Korea and Japan in particular have experienced increasingly stronger cyclones, which the researchers have attributed to increasing sea surface temperatures and a change in atmospheric circulation patterns over the coastal seas.
According to the study, the changes in sea surface temperature and wind flows meant that cyclones were more likely to track along coastal seas from the South China Sea upwards, meaning that by the time the cyclones hit the north-east coast of Asia they had gathered more energy than usual and were at their maximum intensity.
The study, which has been published today, 16 January, in IOP Publishing’s journal Environmental Research Letters, involved an analysis of five separate data sets that documented the evolution of tropical cyclones across the north-west Pacific between 1977 and 2010.
The researchers also found that in south-east Asia, in countries such as Taiwan and Vietnam, there was no substantial change in the intensity of tropical cyclones. Here, they found that tropical cyclones had started to generate too close to land in the South China Sea to gather enough energy to reach maximum intensity as they approached land.
In addition to increasing sea surface temperatures in the western Pacific, which have notably warmed over the past 30 years, the researchers also attributed the changes to the strengthening of the Walker circulation—an ocean-based atmospheric circulation system that exists over the Pacific.
According to the researchers, the Pacific Walker circulation strengthens as the difference in sea surface temperature between the warmer western Pacific and the colder central-eastern Pacific increases. The result is that the wind flows associated with the circulation pattern force the tropical cyclones towards the north-east coast of Asia, where they reach maximum intensity.
Although the study only accounts for natural variations in sea surface temperature and the Walker circulation retrospectively, over the past 30 years, the researchers do predict that the tropical cyclones hitting East Asia will only strengthen under human-induced climate change.
Professor Chang-Hoi Ho, from Seoul National University, said: “Noticeable increases of greenhouse gases over the globe could influence rising sea surface temperature and change large-scale atmospheric circulation in the western North Pacific, which could enhance the intensity of tropical cyclones hitting land over East Asia.
“If the past changes in large-scale environments are a result of global warming, it can be assumed that, in the future, more catastrophic tropical cyclones will strike East Asia than ever before.
“The next stage of our research is to use climate models to predict future tropical cyclone landfall intensity in these regions.” | <urn:uuid:6b130ca6-f8c0-4ecf-a16b-8c0719038c80> | 3.453125 | 555 | News Article | Science & Tech. | 9.783772 | 95,512,122 |
__slots__. By default, instances of both old and new-style classes have a dictionary for attribute storage. This wastes space for objects. In this case, the special read-only attribute __self__ is set to the object denoted by The __slots__ declaration takes a sequence of instance variables and. As you may know every object in Python contains a dynamic dictionary that __ slots__ = ('x', 'y') #defining the slots. def __init__(self, *args, **kwargs).
VideoMagic Methods/ Special Methods/ Dunders - Python 3.5 - Part 1
Sie: Python __slots__
|Python __slots__||None This type has a single value. Methods corresponding to operations that are not supported by the particular kind of number implemented e. Note This method may still be bypassed when looking up special methods as the result of implicit invocation via language syntax or built-in functions. Iterator objects also need to implement this method; they are required to return themselves. A dict containing annotations of parameters.|
|Python __slots__||Enter search terms or a module, class or function. Simon July 7th, at 2: This renders the meaning of the program undefined. Bytes sudokuspielen de the values 0— usually represent the corresponding ASCII values, but the interpretation of values is up to the program. A tuple containing default argument values for those arguments that have defaults, or None if no arguments have a default value.| | <urn:uuid:fe83b7d9-efbe-4363-b740-b2f50e1bc7dd> | 2.640625 | 312 | Documentation | Software Dev. | 46.250769 | 95,512,123 |
Carbon dating kids
Is it still relevant now with advances in carbon and carbon repair? By Kurt Gensheimer So you’re about to mosey on over to your local bike shop and drop more coin for your first genuine racing bike than most people pay for an entire motorcycle.
You’re either new to the sport of cycling or you’ve been riding for a few years, learning the ropes on an old aluminum frame that’s one season away from the dumpster.
Update: Nov 29 Here’s one of the most engaging articles we’ve ever published.
Scientists know how fast carbon-14 decays, so by measuring how much of it is remaining in a dead organism, they can figure out how long it has been dead.
When scientists chipped the Iceman out of the block of ice he was found in, they tested his body to see how many carbon-14 atoms were remaining, which told them his age.
In 1960, he was awarded the Nobel Prize in Chemistry for this work.
He first demonstrated the accuracy of radiocarbon dating by accurately estimating the age of wood from an ancient Egyptian royal barge of which the age was known from historical documents. | <urn:uuid:7444f1ad-2c3a-4cbb-a154-58675536684e> | 3.171875 | 252 | Personal Blog | Science & Tech. | 53.223088 | 95,512,125 |
People living closer to the equator have darker skin due to higher UV radiation, and this is passed down through generations of people having higher levels of melanin, but is the same true for flowers? Researchers at the University of Pittsburgh say yes, but it’s not noticeable to the human eye.
“Pigmentation patterns getting darker towards lower latitudes is ... an ecological rule called ‘Gloger’s Rule’, and it’s been formulated towards animals, so this is kind of the first extension of this ecological rule to plants,” said researcher and grad student Matt Koski.
Although flowers do not appear darker, pollinators such as bees see the ultraviolet light in addition to the visible spectrum. When examining flowers in the UV spectrum, flowers have a dark "bull's eye" near pollen and nectar rewards. The researchers found that the bull’s eyes were larger closer to the equator.
The larger bull’s eye helps the flower to absorb the sun’s ultraviolet light, and leads the researchers to believe that without a large bull’s eye a flower would be damaged.
“In the lab we exposed flowers to UV, and protected flowers from UV, and measured pollen viability to find that UV radiation does damage pollen viability, and that having higher pigmentation can protect the pollen from UV damage,” said Koski.
The damage to the pollen is what they believe drives natural selection so that flowers with bigger bull’s eyes are more common closer to the equator. | <urn:uuid:a6ee1903-3642-4edb-9fa0-c189a96585d9> | 4.09375 | 320 | News Article | Science & Tech. | 48.383333 | 95,512,138 |
On June 28th, Cool Science did a show for the Colorado National Guard Child & Youth Program! This time around Cool Science demonstrated to the group of pre-teens some of the amazing properties of liquid nitrogen. When nitrogen is cooled to a temperature of -322 °F it becomes a liquid with bizarre properties.
One example is how liquid nitrogen instantly boils when it touches human skin because of the temperature difference. It’s about 100 degrees difference between the liquid and the average air temperature outside! The small pocket of evaporated gas created by the boiling process creates a little hover board for the remaining liquid nitrogen, and droplets roll off the skin without causing any damage. After the show the kids got to make ice cream and Dippin’ Dots with the super cool nitrogen.
It was clear from the day’s activities that many of the kids were fascinated by the science behind the simple physical process of evaporation and condensation, and best of all they got to learn about the science in fun and interesting ways. Who doesn’t enjoy some delicious ice cream! | <urn:uuid:debad043-b5f4-4101-aec2-8daaa8554a6d> | 3.5 | 222 | News (Org.) | Science & Tech. | 44.858333 | 95,512,184 |
Interpretation of gravity and magnetic anomalies at Lake Rotomahana: geological and hydrothermal implications
Tontini, F. Caratori
de Ronde, Cornel E. J.
Scott, Bradley J.
Tivey, Maurice A.
MetadataShow full item record
KeywordLake Rotomahana; Hydrothermal systems; Magnetic anomalies; Gravity anomalies; Phreatomagmatic eruptions; Basaltic dikes
We investigate the geological and hydrothermal setting at Lake Rotomahana, using recently collected potential-field data, integrated with pre-existing regional gravity and aeromagnetic compilations. The lake is located on the southwest margin of the Okataina Volcanic Center (Haroharo caldera) and had well-known, pre-1886 Tarawera eruption hydrothermal manifestations (the famous Pink and White Terraces). Its present physiography was set by the caldera collapse during the 1886 eruption, together with the appearance of surface activities at the Waimangu Valley. Gravity models suggest subsidence associated with the Haroharo caldera is wider than the previously mapped extent of the caldera margins. Magnetic anomalies closely correlate with heat-flux data and surface hydrothermal manifestations and indicate that the west and northwestern shore of Lake Rotomahana are characterized by a large, well-developed hydrothermal field. The field extends beyond the lake area with deep connections to the Waimangu area to the south. On the south, the contact between hydrothermally demagnetized and magnetized rocks strikes along a structural lineament with high heat-flux and bubble plumes which suggest hydrothermal activity occurring west of Patiti Island. The absence of a well-defined demagnetization anomaly at this location suggests a very young age for the underlying geothermal system which was likely generated by the 1886 Tarawera eruption. Locally confined intense magnetic anomalies on the north shore of Lake Rotomahana are interpreted as basalts dikes with high magnetization. Some appear to have been emplaced before the 1886 Tarawera eruption. A dike located in proximity of the southwest lake shore may be related to the structural lineament controlling the development of the Patiti geothermal system, and could have been originated from the 1886 Tarawera eruption.
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Journal of Volcanology and Geothermal Research 314 (2016): 84-94, doi:10.1016/j.jvolgeores.2015.07.002.
Suggested CitationPreprint: Tontini, F. Caratori, de Ronde, Cornel E. J., Scott, Bradley J., Soengkono, Supri, Stagpoole, Vaughan, Timm, Christian, Tivey, Maurice A., "Interpretation of gravity and magnetic anomalies at Lake Rotomahana: geological and hydrothermal implications", 2015-03, https://doi.org/10.1016/j.jvolgeores.2015.07.002, https://hdl.handle.net/1912/8157
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Central Anomaly Magnetization High documentation of crustal accretion along the East Pacific Rise (9°55′–9°25′N) Williams, Clare M.; Tivey, Maurice A.; Schouten, Hans A.; Fornari, Daniel J. (American Geophysical Union, 2008-04-09)Near-bottom magnetic data collected along the crest of the East Pacific Rise between 9°55′ and 9°25′N identify the Central Anomaly Magnetization High (CAMH), a geomagnetic anomaly modulated by crustal accretionary processes ...
Tominaga, Masako; Sager, William W. (John Wiley & Sons, 2010-05-12)The current M-anomaly geomagnetic polarity timescale (GPTS) is mainly based on the Hawaiian magnetic lineations in the Pacific Ocean. M-anomaly GPTS studies to date have relied on a small number of magnetic profiles, a ... | <urn:uuid:08c18e94-ad50-4510-b3f2-8037982243fe> | 2.640625 | 1,015 | Academic Writing | Science & Tech. | 33.396417 | 95,512,190 |
Hubble’s sharpest view of the Orion Nebula This dramatic image offers a peek inside a cavern of roiling dust and gas where thousands of stars are forming. The image, taken by the Advanced Camera for Surveys (ACS) aboard NASAs Hubble Space Telescope, represents the sharpest view ever taken of this region, called the Orion Nebula. More than 3,000 stars of various sizes appear in this image. Some of them have never been seen in visible light. These stars reside in a dramatic dust-and-gas landscape of plateaus, mountains, and valleys that are reminiscent of the Grand Canyon.
In one of the most detailed astronomical images ever produced, the NASA/ESA Hubble Space Telescope is offering an unprecedented look at the Orion Nebula. This turbulent star-formation region is one of astronomy’s most dramatic and photogenic celestial objects.
The crisp image reveals a tapestry of star formation, from the dense pillars of gas and dust that may be the homes of fledgling stars to the hot, young, massive stars that have emerged from their gas-and-dust cocoons and are shaping the nebula with their powerful ultraviolet light.
The new picture reveals large-scale structures never seen before, according to C. Robert O’Dell of Vanderbilt University in Nashville, USA "Only with the Hubble Space Telescope can we begin to understand them," O’Dell said.
Lars Christensen | alfa
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A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
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Independent populations that colonize similar environments and then evolve similar traits provide strong evidence for a deterministic response to natural selection. The resulting pattern has been variously called “parallel” or “convergent” depending on similarity among the starting populations and on one’s preferred definition.*
As parallel evolution provides some of the most convincing evidence for the power of natural selection, finding it has become a rite of passage for evolutionary biologists working in any given natural system, and it is a common stamp of approval for authors publishing on adaptation. Over the years, I have probably seen more than a hundred papers that examine phenotypes from multiple populations in two or more environments. Some statistical model is applied to the data and the main effect of “habitat type” is examined with great expectation. When this effect is significant, the paper trumpets its success in documenting the power of natural selection in shaping the diversity of life.
What often strikes me about such papers, however, is that the population means of the different habitat types often overlap considerably. That is, some populations in one habitat type have larger traits values and some have smaller trait values than populations in the other habitat type. This pattern implies to me that the coarse classification of habitat type is, in reality, not very predictive of phenotype and that many other factors must also be involved. Sadly, investigators rarely embrace and explore – or even acknowledge – this unexplained variation. We recently published a paper* that does so, and I was prompted to make a blog entry about it as a result of my seminar visit last week to the University of Connecticut.
Parallel/convergent evolution was a common theme in discussions with many UConn folks. Some labs studied situations where different organisms occupy similar environments and so would be expected to evolve similar traits (Schlutz lab: adaptation to the osmoregulatory challenges of fresh versus salt water by stickleback and alewives). Other labs studied situations where similar body forms evolved independently and so one would expect similar selective pressures to have been the cause (Jockush lab: large and small bodied skinks of different lineages in California). In South Africa, the plant genus Pelargonium is highly variable in leaf shape and growth form (Schlichting and Holsinger labs). So variable, in fact, that I (as a non-plant person) would never have imagined that they would all be in the same genus. Presumably all of these different shapes and forms in Pelargonium are the result of adaptation to different environments, and yet species with very different growth forms can be found side-by-side in the same environment. (OK, I only saw them in a greenhouse but I am told this is true in nature.) If adaptation is the cause of this group’s radiation, then why are two plant types of very different form found in the same environment? This dramatic non-parallelism is just the sort of thing I am talking about.
To investigate non-parallelism, Renaud Kaeuffer, Dan Bolnick, Katie Peichel, and I quantified ecological (diet), morphological (body shape, trophic traits, armor traits), and genetic (neutral and QTL-linked microsatellites) variation in each of six independent lake and stream population pairs of threespine stickleback*. Some traits were remarkably parallel. For example, all lake populations had stickleback with shallower average body depths than did all stream populations (no overlap in the population means). Other traits, however, were decidedly non-parallel. For example, the main effect of habitat type (lake or stream) explained essentially none of the variation in armor traits. So what is the cause of this variation in parallelism? By relating divergence in morphological traits to the degree of ecological divergence, we were able to show that deviations from non-parallelism are mostly likely the result of variation in selection. That is, variation in parallelism is caused by selective factors that do not map so cleanly onto the coarse habitat type classifications that we (and possibly other investigators) typically use. We are not the first group to find this, of course, but we certainly have fun embracing it.
The pressing question to my mind is just how common and strong are these effects? How similar will be the physiological adaptation of alewives and stickleback? To what extent is the variation in skink body shape the result of adaptation to particular environments – as opposed to some other effect? Is the variation in growth form in Pelargonium the result of variation in microhabitats with a general location – or is it the result of some other historical contingency? To what extent does variation in gene flow cause deviations from parallel evolution. We previously found this last effect to be strong in lake and stream stickleback, and it also seems critical in Mark Urban’s salamanders.
Just how parallel is parallel evolution – and why?
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This article may require cleanup to meet Wikipedia's quality standards. The specific problem is: contradictory examples (October 2015) (Learn how and when to remove this template message)
Regelation is the phenomenon of melting under pressure and freezing again when the pressure is reduced. Many sources state that regelation can be demonstrated by looping a fine wire around a block of ice, with a heavy weight attached to it. The pressure exerted on the ice slowly melts it locally, permitting the wire to pass through the entire block. The wire's track will refill as soon as pressure is relieved, so the ice block will remain solid even after wire passes completely through. This experiment is possible for ice at −10 °C or cooler, and while essentially valid, the details of the process by which the wire passes through the ice are complex. The phenomenon works best with high thermal conductivity materials such as copper, since latent heat of fusion from the top side needs to be transferred to the lower side to supply latent heat of melting.
If 1 mm diameter wire is used, over an ice cube 50 mm wide, the area the force is exerted on is 50 mm2. This is 50×10−6 m2.
Force (in newtons) equals pressure (in pascals) multiplied by area (in square metres).
If at least 500 atm (50 MPa) is required to melt the ice, a force of (50×106 Pa)(50×10−6 m2) = 2500 N is required, a force roughly equal to the weight of 250 kg on Earth.
Regelation was discovered by Michael Faraday. Regelation occurs only for substances, such as ice, that have the property of expanding upon freezing, for the melting points of those substances decrease with the increasing external pressure. The melting point of ice falls by 0.0072 °C for each additional atm of pressure applied. For example, a pressure of 500 atmospheres is needed for ice to melt at −4 °C.
For a normal crystalline ice far below its melting point, there will be some relaxation of the atoms near the surface. Simulations of ice near to its melting point show that there is significant melting of the surface layers rather than a symmetric relaxation of atom positions. Nuclear magnetic resonance provided evidence for a liquid layer on the surface of ice. In 1998, using atomic force microscopy, Astrid Doppenschmidt and Hans Jurgen Butt, measured the thickness of the liquid-like layer on ice to be between 12 nm at −24 °C and 70 nm at −0.7 °C. Surface melting was found to begin at temperatures as low as −33 °C.
The surface melting can account for the following:
- Low coefficient of friction of ice, as experienced by skaters.
- Ease of compaction of ice
- High adhesion of ice surfaces
Examples of regelation
- A glacier can exert a sufficient amount of pressure on its lower surface to lower the melting point of its ice. The melting of the ice at the glacier's base allows it to move from a higher elevation to a lower elevation. Liquid water may flow from the base of a glacier at lower elevations when the temperature of the air is above the freezing point of water.
- Ice skating is given as an example of regelation; however the pressure required is much greater than the weight of a skater. Additionally, regelation does not explain how one can ice skate at sub-zero (°C) temperatures.
- Compaction and creation of snow balls is another example from old texts. Again the pressure required is far greater than can be applied by hand. A counter example is that cars do not melt snow as they run over it.
- A supersolid skin that is elastic, hydrophobic, thermally more stable covers both water and ice. The skins of water and ice are characterized by an identical H-O stretching phonons of 3450 cm^-1. Neither the case of liquid forms on ice nor ice layer covers water, but the supersolid skin slipperizes ice and toughens the water skin
- Hydrogen bond (O:H-O) relaxation under compression. Compression shortens and stiffens the O:H nonbond and simultaneously lengthens and softens the H-O covalent bond, and negative pressure effect oppositely
- Melting point is proportional to the cohesive energy of the covalent bond. Therefore, compression lower the Tm
- Y. Huang, X. Zhang, Z. Ma, Y. Zhou, W. Zheng, J. Zhou, and C.Q. Sun, Hydrogen-bond relaxation dynamics: resolving mysteries of water ice. Coordination Chemistry Reviews 2015. 285: 109-165.
- C.Q. Sun, Relaxation of the Chemical Bond. Springer Series in Chemical Physics 108. Vol. 108. 2014 Heidelberg,807 pp. ISBN 978-981-4585-20-0.
- Drake, L. D.; Shreve, R. L. (1973). "Pressure Melting and Regelation of Ice by Round Wires". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. 332 (1588): 51. Bibcode:1973RSPSA.332...51D. doi:10.1098/rspa.1973.0013.
- Glossary of Meteorology: Regelation Archived 2006-02-25 at the Wayback Machine., American Meteorological Society, 2000
- Physics Today, December 2005, pp. 50–55.
- White, James. The Physics Teacher, 30, 495 (1992).
- Zhang, Xi; et al. (October 2014). "A common superslid skin covering both water and ice". PCCP. 16: 22987–22994. Bibcode:2014PCCP...1622987Z. doi:10.1039/C4CP02516D.
- Sun, Changqing (2014). Relaxation of the Chemical Bond. Springer. p. 807. ISBN 978-981-4585-20-0.
- Sun, Chang Qing; et al. (2012). "Hidden force opposing compression of ice". Chem. Sci. 3: 1455–1460. | <urn:uuid:25d8fe1d-6fd8-4e92-bd7f-8d786911d2fb> | 4.09375 | 1,317 | Knowledge Article | Science & Tech. | 66.926783 | 95,512,222 |
Study reveals clues to how drowsy microbes in Arctic tundra change to methane-makers as permafrost thaws
As the Arctic warms, tons of carbon locked away in Arctic tundra will be transformed into the powerful greenhouse gases carbon dioxide and methane, but scientists know little about how that transition takes place. Now, scientists looking at microbes in different types of Arctic soil have a new picture of life in permafrost that reveals entirely new species and hints that subzero microbes might be active.
Such information is key to prepare for the release of gigatons of methane, which could set the Earth on a path to irreversible global warming. Appearing in today's issue of Nature, the study will help researchers better understand when and how frozen carbon might get converted into methane.
The results suggest how microbes survive in the subzero temperatures of permafrost. "The microbes in permafrost are part of Earth's dark matter. We know so little about them because the majority have never been cultivated and their properties are unknown," said microbiologist Janet Jansson of the Department of Energy's Pacific Northwest National Laboratory. "This work hints at the life strategies they use when they've been frozen for thousands of years."
Permafrost, the layer of Arctic ground that is always frozen, lies underneath a layer that thaws and refreezes every year, which scientists call the "active layer".
Permafrost locks carbon away in vegetative matter. Microbes in the bog generate methane from this carbon, but researchers aren't sure how the soil microbes go from frozen to marshy methane producers.
"Estimates are that permafrost stores between 780 and 1,400 gigatons of terrestrial carbon. That's a huge reservoir," said Jansson. "What happens when permafrost thaws and trapped carbon is available for microbes?"
Previous experiments by Jansson and collaborators have shown that thawing frozen soil in the lab quickly leads to a burst of methane production, along with a change in the community of microbes. For this study, Jansson and colleagues wanted to examine how natural thawing affected microbes in tundra transitioning from permafrost to bog in the Arctic.
To get an overall picture of how the communities transform from frozen snoozers to bustling bacteria, they used a combination of molecular tools collectively known as "omics". These tools revealed the particular genes the microbes are equipped with, which genes they turn on, and the proteins they wield that allow them to survive on the resources around them.
To do this, Jansson and colleagues explored permafrost, active layer, and bog soil samples collected by researchers with the United States Geological Survey. They identified microbial genes and their activity with help from DOE's Joint Genome Institute in Walnut Creek CA. And they collaborated with scientists from several universities, national laboratories and biotechnology companies to identify proteins in the various soils. Beginning this research at DOE's Lawrence Berkeley National Laboratory, Jansson completed the analyses at DOE's Pacific Northwest National Laboratory.
Life in the cryosphere
Gene information told the researchers which microbe species were present in each layer, how closely they were related to each other and what they could potentially be doing. They found an undiscovered diversity of microbes in Arctic soils and were able to describe several completely novel microbes in each type of soil.
Gene activity and the presence of proteins, which are a microbe's tools for living, indicated what the microbes were doing. For example, even though the permafrost microbes lived at subzero temperatures and had a lot of proteins for protection against freezing conditions, they also wielded proteins that indicated they could move through the soil, use iron for energy or live on methane.
Soil microbes in the active layer had other protein tools that would let them find nutrients in an environment that goes through cycles of freezing and thawing.
As expected, the bog microbes showed gene activity and protein tools for producing methane, and the team identified many species whose main job is to make methane, called methanogens. However, the team was surprised to find several brand new species of them. Methanogens, old and new, took over the communities that lived in the bog.
"This work provides the first demonstration of this combination of omics tools to gain a more mechanistic understanding of life in permafrost and the changes that occur during natural thaw," said Jansson. "We know changes happen as permafrost turns into bog, but we don't yet know the significance of these changes at a molecular level."
This work was primarily supported by the Department of Energy's Office of Science, the United States Geological Survey and the Academy of Finland.
Reference: Jenni Hultman, Mark P. Waldrop, Rachel Mackelprang, Maude M. David, Jack McFarland, Steven J. Blazewicz, Jennifer Harden, Merritt R. Turetsky, A. David McGuire, Manesh B. Shah, Nathan C. VerBerkmoes, Lang Ho Lee, Kostas Mavrommatis, Janet K. Jansson. Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes, Nature March 4, 2015, doi:10.1038/nature14238. (In press.)
Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. Founded in 1965, PNNL employs 4,300 staff and has an annual budget of more than $1 billion. It is managed by Battelle for the U.S. Department of Energy's Office of Science. As the single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information on PNNL, visit the PNNL News Center, or follow PNNL on Facebook, Google+, LinkedIn and Twitter.
The U.S. Department of Energy Joint Genome Institute, User Facility of Lawrence Berkeley National Laboratory supported by the DOE Office of Science, is committed to advancing genomics in support of DOE missions related to clean energy generation and environmental characterization and cleanup. DOE JGI, headquartered in Walnut Creek, Calif., provides integrated high-throughput sequencing and computational analysis that enable systems-based scientific approaches to these challenges. Follow @doe_jgi on Twitter.
Mary Beckman | EurekAlert!
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Slender Scotch Burnet
Very similar to and sometimes difficult to distinguish from the Five-spot Burnet. In general, the forewing of the Narrow-bordered Five-spot Burnet is longer and more pointed, the upper angle of the hindwing is more pointed and the black border of the hindwing is narrower than those of the Five-spot Burnet. Sometimes, although infrequently, the red colour is replaced by yellow.
Sometimes found commonly. The moth flies in sunshine and is attracted to a range of flowers, including thistles, knapweeds, and scabious.
Size and Family
- Family – Burnets and Foresters (Zygaenids)
- Small Sized
- Wingspan Range - 30-38mm
- UK Biodiversity Action Plan: Not listed
- UK status: Common
- UK status: Rare (Red Data Book category 3)
- Occurs in Ireland only
Caterpillar Food Plants
Meadow Vetchling (Lathyrus pratensis), Red Clover (Trifolium pratense), Sainfoin (Onobrychis viciifolia)and Greater Bird’s-foot Trefoil (Lotus uliginosus). Occasionally also Common Bird’s-foot Trefoil (Lotus corniculatus), White Clover (Trifolium repens) and Bitter-vetch (Lathyrus linifolius).
Associated with rough grassland, both dry calcareous grasslands and on damper soils, undercliffs, roadside verges, embankments, woodland clearings and rides and the margins of wetlands. Subspecies jocelynae occurs on steep, coastal grassy slopes.
- Countries – England, Wales, Scotland, Ireland
- Well distributed over much of England north to the Scottish Borders and in north and south Wales. Found on Jersey. Subspecies jocelynae is restricted to Skye. Subspecies insularis is widespread in Ireland, particularly in the north.
- Distribution Trend Since 1970’s = Britain: | <urn:uuid:789aa12f-4d3f-4e81-bc43-15bbe290c372> | 3.15625 | 441 | Knowledge Article | Science & Tech. | 30.499345 | 95,512,252 |
Methane oxidation fueled by algal oxygen production
Methane emissions are strongly reduced in lakes with anoxic bottom waters. But here – contrary to what has previously been assumed – methane removal is not due to archaea or anaerobic bacteria. A new study on Lake Cadagno in Canton Ticino shows that the microorganisms responsible are aerobic proteobacteria. The oxygen they require is produced in situ by photosynthetic algae.
Sampling was performed from a platform on Lake Cadagno in Canton Ticino (southern Switzerland).
Jana Milucka, Max Planck Institute for Marine Microbiology, Bremen
In contrast to oceans, freshwater lakes – and tropical reservoirs – are significant sources of methane emissions. Methane, a greenhouse gas, arises from the degradation of organic material settling on the bottom. Although lakes occupy a much smaller proportion of the Earth’s surface than oceans, they account for a much larger proportion of methane emissions.
Well-mixed lakes, in turn, are the main contributors, while emissions from seasonally or permanently stratified lakes with anoxic bottom waters are greatly reduced. It has been assumed to date that the methane-removing processes occurring in such lakes are the same as those in marine systems. But a new study carried out on Lake Cadagno (Canton Ticino) by researchers from Eawag and the Max Planck Institute for Marine Microbiology (Bremen, Germany) shows that this is not the case.
The scientists demonstrated that methane is almost completely consumed in the anoxic waters of Lake Cadagno, but they did not detect any known anaerobic methane-oxidizing bacteria – or archaea, which are responsible for marine methane oxidation. Instead, water samples collected from a depth of around 12 metres were found to contain abundant aerobic proteobacteria – up to 240,000 cells per millilitre.
“We wondered, of course, how these aerobic bacteria can survive in anoxic waters,” says first author Jana Milucka of the Max Planck Institute for Marine Microbiology. To answer this question, the behaviour of the bacteria was investigated in laboratory experiments: methane oxidation was found to be stimulated only when oxygen was added to the samples incubated in vitro, or when they were exposed to light.
The scientists concluded that the oxygen required by the bacteria is produced by photosynthesis in neighbouring diatoms. Analysis by fluorescence microscopy showed that methane-oxidizing bacteria belonging to the family Methylococcaceae occur in close proximity to diatoms and can thus utilize the oxygen they generate (Fig. 2).
Thanks to the combined activity of bacteria and diatoms, methane is thus consumed in the lake rather than being released into the atmosphere. This type of methane removal has not previously been described in freshwater systems. Project leader Carsten Schubert of Eawag comments: “For lakes with anoxic layers, and also for certain marine zones, it looks as if the textbooks will have to be rewritten.”
Aerobic methane-oxidizing bacteria may play a significant role wherever sufficient light penetrates to anoxic water layers; according to Schubert, this is the case in most Swiss lakes. Similar observations have already been made in Lake Rotsee near Lucerne, in studies not yet published. Research will now focus on deeper lakes, where initial investigations suggest that different processes occur.
CH: Carsten Schubert, Eawag: +41 (0)58 765 2195; firstname.lastname@example.org
D: Marcel Kuypers, Max Plank Institute for Marine Microbiology, Bremen: +49 421 2028 602; email@example.com
or from the press officer
Manfred Schloesser, Max Plank Institute for Marine Microbiology, Bremen: +49 421 2028 704; firstname.lastname@example.org
Methane oxidation coupled to oxygenic photosynthesis in anoxic waters; Jana Milucka, Mathias Kirf, Lu Lu, Andreas Krupke, Phyllis Lam, Sten Littmann, Marcel MM Kuypers and Carsten J Schubert; The ISME Journal (International Society for Microbial Ecology), advance online publication, 13 February 2015; doi:10.1038/ismej.2015.12;
Dr. Manfred Schloesser | Max-Planck-Institut für marine Mikrobiologie
New research calculates capacity of North American forests to sequester carbon
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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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12.07.2018 | Event News
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There is definitely a need for renewable energy because we currently use mostly fossil fuels to produce our electric. Currently about 90% of electricity comes from fossil fuel power plants, coal, nuclear, and natural gas which leaves 10% of power coming from other sources ("Were Our Energy Comes From", 2012). Fossil fuels create air pollution that contains greenhouse gases which cause a variety of environmental issues. Wind farms are a group of wind turbines that are all connected to a grid. Wind turbines work by wind blowing across the blades creating lift and drag similar to an airplane. The lift propels the blade around spinning a connecting rod that spins a generator creating an electrical charge that sent out to costumers or stored in batteries for later use. There are many advantages of wind energy including, Wind energy is a green energy source, wind energy does not pollute the environment like fossil fuels, coal, natural gas and nuclear energy does. Generating electricity with wind energy does not involve any emissions of greenhouse gases. Wind energy is a renewable source of energy. Wind is naturally occurring and there is no way we can empty the resources, this is not the case for fossil fuels, which we heavily rely on today. Although some places are better suited, harnessing wind energy can be done almost everywhere. About the only restriction is if it can be made financially viable, the utility company can make a profit, offshore wind turbines expand exploitable resources even further. The price of wind energy continues to drop, and with advances in technology and equipment continue to push the price down. Additionally People can generate their own electricity with wind power in much the same manner as people do with solar panels. Some companies specialize in residential installations and there are also several DIY wind power kits on the market (Maehlum 2012). There are several disadvantages of wind energy as well wind energy is...
References: How do Wind Turbines work. (2012). Retrieved from http://www1.eere.energy.gov/wind/wind_how.html
Maehlum, M. (2012). Wind energy pros and cons. Retrieved from http://energyinformative.org/wind-energy-pros-and-cons/
Were our energy comes from. (2012). Retrieved from http://www.consumerenergyreport.com/research/where-our-electricity-comes-from/
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The findings, as described this week in the Proceedings of the National Academy of Sciences, use new observational techniques to address long-standing questions about subglacial water under Thwaites, a Florida-sized outlet glacier in the Amundsen Sea Embayment considered a key factor in projections of global sea level rise.
On its own, Thwaites contains enough fresh water to raise oceans by about a meter, and it is a critical gateway to the majority of West Antarctica’s potential sea level contribution of about 5 meters.
The new observations suggest the dynamics of the subglacial water system may be as important as well recognized ocean influences in predicting the fate of Thwaites Glacier.
Without an accurate characterization of the bodies of water deep under Thwaites, scientists have offered competing theories about their existence and organization, especially in the rapidly changing region where the glacier meets the ocean.
Using an innovation in airborne ice-penetrating radar analysis developed by lead author Dusty Schroeder, a doctoral candidate at the Institute for Geophysics, the Texas team shows that Thwaites’ subglacial water system consists of a swamp-like canal system several times as large as Florida’s Everglades lying under the deep interior of the ice sheet, shifting to a series of mainly stream-like channels downstream as the glacier approaches the ocean.
Scientists have attempted to use ice-penetrating radar to characterize subglacial water for many years, but technical challenges related to the effects of ice temperature on radar made it difficult to confirm the extent and organization of these water systems. Schroeder’s technique looking at the geometry of reflections solves this problem, because the temperature of the ice does not affect the angular distribution of radar energy.
“Looking from side angles, we found that distributed patches of water had a radar signature that was reliably distinct from stream-like channels,” said Schroeder. He compared the radar signature to light glinting off the surface of many small interconnected ponds when viewed out of an airplane window.
Distinguishing subglacial swamps from streams is important because of their contrasting effect on the movement of glacial ice. Swamp-like formations tend to lubricate the ice above them whereas streams, which conduct water more efficiently, are likely to cause the base of the ice to stick between the streams. (The effect is similar to the way rain grooves on a tire can help prevent a car from hydroplaning on a wet road.)
As a result of this change in slipperiness, the glacier’s massive conveyor belt of ice piles up at the zone where the subglacial water system transitions from swamps to streams.
This transition forms a stability point along a subglacial ridge that holds the massive glacier on the Antarctic continent.
“This is where ocean and ice sheet are at war, on that sticking point, and eventually one of them is going to win,” said co-author Don Blankenship, a senior research scientist from the Institute for Geophysics.
Observations of the subglacial stream-and-swamp dynamic and the sub-ice topography suggest that Thwaites Glacier is stable in the short term, holding its current position on the continent. However, the large pile of ice that has built up in the transition zone could rapidly collapse if undermined by the ocean warming or changes to the water system.
“Like many systems, the ice can be stabilized until some external factor causes it to jump its stability point,” said Blankenship. “We now understand both how the water system is organized and where that dynamic is playing itself out. Our challenge is to begin to understand the timing and processes that will be involved when that stability is breached.”
Current models predicting the fate of the glacier do not yet account for these dynamic, subglacial processes.
The findings rely on radar data acquired during airborne geophysical surveys over West Antarctica by the Institute for Geophysics, with operational support from the National Science Foundation. The analysis was enabled through intensive supercomputing supported by the university’s Texas Advanced Computing Center.
The research was funded through grants from the National Science Foundation and NASA, with additional support from both the Vetlesen Foundation and the Institute for Geophysics, which is a research unit of the university’s Jackson School of Geosciences.
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....
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Peter Suciu for redOrbit.com – Your Universe Online
Anyone who has a plasma TV in their living room likely knows those things give off a bit of heat, but few understand why. Most of us just focus on the life-like pictures on the screen. But nowadays, the scientifically curious can take part in open online courses like those offered by Khan Academy, MIT OpenCourseWare and iTunes U to learn about the science behind how nature and technology work. And the American Physical Society reported this week that the growing trend in online physics classes that will actually enable students to interact with real physical experiments.
This was one of the key reports presented at the 55th Annual Meeting of the American Physical Society’s (APS) Division of Plasma Physics (DPP), which is being held this week in Denver, Colorado.
Typically, online courses have relied on virtual labs that only simulate laboratory environments. This week the United States Department of Energy’s Princeton Plasma Laboratory (PPPL) announced that it has developed software for an experiment that can be observed and controlled from anywhere in the world. So while many of us might settle for trying to figure out why that plasma TV gives off more heat than a comparable LCD screen, students can take part in an online open-user experiment that could turn the heat up even more, specifically, from a 50,000-degree plasma.
The user can operate the experiment with a set up that can be observed and controlled from anywhere in the world. This particular experiment, “Remote Glow Discharge Experiment (RGDX),” allows users to operate the experiment via remote control and can watch the effect of the apparatus at PPPL via streaming web video.
The APS noted that this experiment consists of three main component that include, “A live-streaming video that constantly observes an experimental apparatus housed at PPPL; A set of online controls; and Information that explains what the user observes and controls, plus more in-depth resources that explore plasma and its uses.”
The RGDX consists of a hollow glass tube that holds air in a vacuum, and users can supply a surge of up to 2000 volts to generate a glow within it. The remote user can take complete control of the pressure inside the tube, and is guided through steps that gradually increase their level of engagement. This helps the users to understand new physical concepts, and those who want to go even deeper into the physics behind the phenomenon can find explanations for a variety of topics, including the physics behind the voltages, pressures and magnets.
The audience for the RGDX could be wide ranging, and include someone merely interested in controlling physical apparatus from afar, to undergraduate and graduate level students who are interested in studying the effects of phenomena such as various instabilities in plasma and even the physics behind it.
RGDX has been designed as a novel experiment, but also as part of an in-class physics course. The researchers noted that the software could be adapted to an array of far reaching experiments in the field of physics as well as other sciences.
The APS is a non-profit membership organization, which works to advance knowledge of physics through research journals, scientific meetings, and education, outreach, advocacy and international activities. This group currently represents more than 50,000 members, including physicists in academia, national laboratories and industry in the United States and throughout the world. | <urn:uuid:fea36337-99cc-4b69-bf36-c8296e3d5c1b> | 3.390625 | 687 | Truncated | Science & Tech. | 28.560595 | 95,512,297 |
This species has been found in only one geographic locality in the lowland versant (“vertiente llanera”) of the Venezuelan Sierra de Portuguesa, a belt of semi-deciduous forest which lies within the southern Lara state on the northernmost portion of the Andes mountain range in South America (La Marca 2009). Currently, this species is known to occur at an altitude range of between 800 and 1,700 m asl (La Marca 2009).
Habitat and Ecology
The main natural habitat type is semi-deciduous moist tropical forest that has been characterized as “bosque muy húmedo premontano” (Premontane Very Humid Forest) (La Marca 2009). This species has been found within a cascading mountain stream tributary in the Morador River, Portuguesa River basin. While the ecology of this species is poorly known (La Marca 2009), it is suspected to have similar reproduction habits as other congeners, i.e. eggs laid on land and later transported by one of the parents to a stream where they develop further.
About 25 individuals were observed in a population thought to be comprised of at least 50 individuals in 2004 (La Marca 2009).
There has been an observed major loss in natural semi-deciduous woodland due to the conversion to agriculture, mainly coffee plantations (La Marca 2009). However, it is unknown whether these general threat factors may be impacting this species' immediate habitat directly.
It is not known whether it may occur in any protected area. More information is needed on this species' distribution, population status, natural history and threats.
Red List Status
Data Deficient (DD)
Listed as Data Deficient given that this is a recently described species and little is known about its extent of occurrence (EOO), area of occupancy (AOO), status and ecological requirements.
IUCN SSC Amphibian Specialist Group 2013. Mannophryne speeri. The IUCN Red List of Threatened Species 2013: e.T190995A18469201. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T190995A18469201.en | <urn:uuid:66b9c438-f01b-42dc-8931-98b0c64d30f7> | 2.796875 | 473 | Knowledge Article | Science & Tech. | 50.55175 | 95,512,350 |
Accurate topographic data over the global land and ice masses have numerous applications in areas of geology, geophysics, hydrophysics and polar ice research. It is well established that interferometric synthetic aperture radar (InSAR) is a method which may provide a means of estimating global topography with high spatial resolution and height accuracy. ONe implementation approach, that of utilizing a single SAR system in a nearly repeating orbit, is attractive not only for cost and complexity reasons but also in that it permits inference of changes in the surface over the orbit repeat cycle echoes. This paper analyzes InSAR spatial geometry model and gives a phase error model. The paper also discusses the characteristics of InSAR echo signal. Finally, the general procedure of InSAR imaging is outlined. | <urn:uuid:fae471c2-5bf8-4dd6-8b64-7164c4312299> | 3.171875 | 159 | Academic Writing | Science & Tech. | 12.291429 | 95,512,356 |
- Research news
- Open Access
© BioMed Central Ltd 2002
Published: 19 June 2002
The current theory of eukaryotic gene expression suggests that each individual gene is under the control of its own promoter sequence. In the launch issue of Journal of Biology, Paul Spellman and Gerald Rubin at Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, show that the Drosophila genome contains groups of adjacent genes that have similar gene expression profiles, despite being functionally distinct (Journal of Biology 2002, 1:5).
Spellman and Rubin collected gene expression profiles under 88 different experimental conditions from a total of 267 GeneChip Drosophila Genome Arrays, which had been used to examine a number of experimental conditions in adult and embryonic fruit flies. After mapping the profile for each gene to the gene's chromosomal position they observed that about 20% of the genes occurred in physically adjacent groups that shared strikingly similar expression patterns.
Along the entire genome they identified about 200 of these groups, each containing between 10 and 30 genes. The average group size was 125 kbp (±90 kbp), with a range of 22 to 450 kbp. In addition they found that the groups are not related to chromosomal structures such as polytene bands or nuclear scaffolding sites. At present the mechanism underlying this phenomenon remains unclear, but they postulate that it may be related to 'open' domains of chromatin around a key gene, such that neighboring genes are 'carried along for the ride'.
"As further experiments are carried out it may be that our observation of similarly regulated groups will grow to include all genes - that is, the entire euchromatic genome may be structured in such domains," conclude the authors. | <urn:uuid:14d37619-6c46-4673-b91f-8d03407f365b> | 2.6875 | 359 | Truncated | Science & Tech. | 22.659415 | 95,512,362 |
Cornell University researchers have discovered that, unlike insects that wave their “feelers” around to acquire information, tiger beetles rigidly hold their antennae directly in front of them to mechanically sense their environments and avoid obstacles while running, according to a study published online in the journal Proceedings of the Royal Society B.
The findings raise questions about strategies used by other fast animals, such as birds of prey and some fish, to sense their environments when speed blinds. The research also has implications for autonomous vehicles that could use fixed antennae to detect obstacles.
“For an insect with really good vision that is active in the daytime normally, you would think it would not rely on antennae for sensing its environment,” said Cole Gilbert, Cornell professor of entomology and the paper’s senior author. Daniel Zurek, a postdoctoral researcher in Gilbert’s lab, is the paper’s first author.
“It has evolved important mechano-sensing behavior while running because it runs so fast,” Gilbert added.
In an earlier paper, Gilbert reported that tiger beetles run so fast, their eyes cannot capture enough light to form images of their prey. Therefore, the insects stop for just milliseconds to relocate prey, then start running again.
Gilbert and Zurek sought to learn how the running insects negotiate obstacles in their habitat, such as crevasses or grass stems, and what role their characteristically forward antennae play. To test this, the researchers set up a runway with a hurdle: In one experiment normal tiger beetles (of the species Cicindela hirticollis) ran the track and negotiated the hurdle, tilting their bodies up when their antennae touched the hurdle; in a second experiment, the researchers painted over the beetles’ eyes and found these blind beetles responded similarly. In the third test, they clipped the antennae of sighted beetles, and the insects smacked right into the hurdle.
The experiment revealed that for fast-moving tiger beetles, “eyes are not sufficient or necessary to avoid obstacles,” Gilbert said. “The antennae are held extremely rigid with the tips 1.5 millimeters off the ground, so they would potentially pick up any discontinuity in the surface.”
Gilbert questions how peregrine falcons and predatory fish compensate for blurry sight while speeding towards prey, potential research areas that no one has tested. The current study may provide a model for new questions. It’s possible, for example, that motion-blind fish perhaps employ their lateral line, sense organs found in aquatic vertebrates used to detect movement and vibration in water.
Also, autonomous vehicles could employ protruding antennae to sense their surroundings, as some of the first robots were fitted with, said Gilbert. “It would be cheaper than cameras,” he said. “For some applications, an antennae might be a solution, it is certainly one that worked evolutionarily for tiger beetles.”
The study was funded by the National Science Foundation
Joe Schwartz | Newswise
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
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
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18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
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+44 1803 865913
Volume 3 examines the chemical composition of the Earth's crust, starting with the continental crust and the rocks exposed therein, moving on to oceanic crust (MORB and oceanic plateaus) and finishing with island arc crust. In addition to providing a descriptive geochemistry of the Earth's crust, the volume summarizes the processes responsible for crustal formation and modification, exchange between the crust and other Earth reservoirs (mantle, oceans and atmosphere), and examines the secular evolution of the crust.
...The Crust is certainly the work that should be of greatest interest to workers in the field of economic geology. R.J. Goldfarb, US Geological Survey, Denver, CO, USA
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Scientists have found a new low-cost way to monitor urban pollution and atmospheric change, and it has nothing to do with technology. No, this method grows readily right on the rocks and trees: moss.
Moss is a natural bioindicator that responds to pollution and drought by changing shape and density or disappearing altogether. Mosses absorb water and nutrients from their immediate surroundings, which can be a good indicator of changes to ecosystems. By monitoring these changes in the moss's natural environment (or even in cultivated scenarios) scientists can ascertain the levels of pollution in the air that might cause harm to human health.
These findings were published in the Landscape and Urban Planning journal by Dr. Yoshitaka Oishi, an associate professor at Fukui Prefectural University. The study described the effect of nitrogen pollution, air quality and drought on moss found over a 1.9-mile area in Hachioji City in northwestern Tokyo. The study showed that severe stress from drought occurred on the moss in areas with high levels of nitrogen pollution, which raised concerns for Dr. Oishi over the impact on health and biodiversity in the region.
While the study focused on Japan, the potential for this new discovery is worldwide: Moss is prevalent in urban centers across the world, and 88 percent of city dwellers are exposed to levels of pollution every year that exceeds the World Health Organizations air quality guidelines. Southeast Asia and the eastern Mediterranean are particularly affected, as are countries in Latin America and Africa. Moss could be the cost-effective answer to monitoring just how bad these areas are getting.
"Mosses are a common plant in all cities so we can use this method in many countries ... they have a big potential to be bioindicators," Oishi told the Thomson Reuters Foundation.
This isn't the first time moss has been implemented as a solution to urban pollution. Brussels-based company Green City Solutions plants mobile walls of moss around cities, which act as small, portable CO2-catching planters called Citytrees. Measuring around 3.5 meters (about 3.8 yards), each Citytree cleans as much air as 275 trees, according Green City, as are designed to be self-watering, self-monitoring and aesthetically pleasing. So far, around 20 Citytrees have been installed in cities around the world.
Like Dr. Oishi, Green City is using moss because it is easy to grow, resilient, and are absorbent. Or as Zhengliang Wu, co-founder of Green City Solutions, put it, "Moss cultures have a much larger leaf surface area than any other plant. That means we can capture more pollutants."
These six sunscreens protect your skin without harming the ocean and vulnerable coral reefs.
Costco is dropping the Polish dog for acai bowls and soy protein salads.
When it comes to plastic bags, one question persists: Are they recyclable, or not?
Tsumoru Shintake has invented a turbine that converts wave energy into clean electricity currently powering hotels. | <urn:uuid:d4bdee04-aa11-428d-ac6c-8f319a7dbc3b> | 3.859375 | 620 | News Article | Science & Tech. | 45.414741 | 95,512,394 |
Boston University scientists produce clearest images of star-forming clouds
A team of astronomers from Boston University’s Institute for Astrophysical Research has produced the clearest map to-date of the giant gas clouds in the Milky Way that serve as the birthplaces of stars. Using a powerful telescope, the astronomers tracked emissions of a rare form of carbon monoxide called 13CO to chart a portion of our home galaxy and its star-forming molecular clouds.
The researchers hope the new illustration will aid in the identification of additional clouds and study of their internal structure to better understand the origin of stars like the sun, which began its life in such a cloud about 5 billion years ago. The data and images are published in the March issue of the Astrophysical Journal Supplement.
Kira Edler | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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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The Slacker's Guide to Physics: Electricity and Magnetism
by Yosun Chang
Number of pages: 39
This is an online textbook on lower division level calculus-based Electricity and Magnetism for the Science and Engineering majors. Reading this will provide you with an alternate and possibly more illuminating method of preparing for examinations and quizzes.
Home page url
Download or read it online for free here:
by Kasper van Wyk - Samizdat Press
A collection of answers to problems from a graduate course in electrodynamics. The problems are mainly from Jackson's Classical Electrodynamics, with some practice problems. The answers provide the reader with a guideline to understand the problems.
by Walter Wilcox - Baylor University
This is two semester graduate level text. Contents: Electrostatics; Boundary Value Problems in Electrostatics; Cylindrical and Spherical Coordinates; Magnetostatics; Time Varying Fields; Plane Electromagnetic Waves and Propagation in Matter; etc.
by Hermann A. Haus, James R. Melcher - MIT
The text is aimed at an audience that has seen Maxwell's equations in integral or differential form (second-term Freshman Physics) and had some exposure to integral theorems and differential operators (second term Freshman Calculus).
by Roy McWeeny - Learning Development Institute
Contents: Charges at rest: Electrostatics; Electric currents; Magnetism; Getting it all together: Maxwell's equations; Dynamos, motors, and electric power; Waves that travel through empty space; More on electric circuits - making the waves. | <urn:uuid:f96a8c12-0a7b-48a2-b211-dacbc9bb36a0> | 2.90625 | 333 | Content Listing | Science & Tech. | 19.670589 | 95,512,415 |