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Analytical Treatment of Conductive Cooling in the Crust
Numerous thermal problems occur in connection with tectonic and magmatic processes in the earth’s crust. It is customary to describe these processes, such as magmatic intrusions or volcanic events, as thermal equilibration processes based on heat conduction. Whereas tectonic events can hardly by treated without convective heat transport, intrusions or volcanic events can be modelled with thermal equilibration based on conduction only. In geological reality this assumption is too simple. For example, in the cooling of a magma body, water migrates through the country rock and transports a considerable amount of heat. However, simplifications can and must be made in the construction of models. In doing so one must treat the cooling process with enough accuracy to produce meaningful results while taking into consideration the errors resulting from these simplifications.
KeywordsLava Flow Half Space Country Rock Magma Body Volcanic Event
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Across south-eastern Australia this morning, people are waking up to forecasts of scorching heat for the week ahead. Players and spectators heading to the Australian Open should prepare for some baking hot days at the tennis: 35°C today, rising to 41°C on Tuesday, with temperatures in the high 30s or low 40s expected to linger until the weeekend. Coming after a relatively mild summer weekend, many of us will be wondering why it's got so hot, so quickly.
Heatwave picture from Shutterstock
That was the question my colleagues and I asked ourselves a year ago, when we began looking at the causes of severe heat waves. In particular, we wanted to know what made the 2009 summer heat wave — which set new records for the most days above 40°C in many parts of south-eastern Australia, and which killed hundreds of people — quite so deadly. Were there any hidden culprits behind the record-breaking spell of fierce heat?
What we discovered was that a seemingly unrelated tropical cyclone off the Western Australian coast contributed to making the south-eastern Australian heat wave worse.
And what's about to happen with this week's heat is a textbook example of what we found.
Watching wild weather in the west
This week, a tropical low is forecast to intensify over northern Western Australia, and a trough will extend from north-west to south-east across the state. Whether or not a tropical cyclone develops, the effects of these low pressure systems will be felt as far away as Melbourne and Hobart.
Our recent research in the internationally peer-reviewed journal Geophysical Research Letters explains how tropical lows and tropical cyclones affect heat waves in south-eastern Australia.
In late January 2009, Tropical Cyclone Dominic hit the Western Australian coastline, causing minor structural damage and bringing down power lines in the small Pilbara town of Onslow. Flooding of a nearby river resulted in significant crop damage, and caused a train to derail near Kalgoorlie.
But as cyclones go, Dominic wasn't so bad: at its peak, the cyclone only reached category 2 status, well below the most severe category 5 level.
Yet as our research showed, even at that level, the cyclone over in Western Australia still had powerful downstream effects for the extreme heat wave across South Australia, southern New South Wales, Victoria and Tasmania in late January and into early February 2009.
During this heat wave, Ambulance Victoria was swamped with a record number of emergency calls, while the Adelaide morgue ran out of room.
Later, the Victorian Department of Health estimated that 374 "excess deaths" occurred in the week of January 26 to February 1 2009. Although it is not possible to directly attribute mortality solely to the heat wave, there was a clear spike above the normal death rate, highlighting the health risks of heat waves, particularly for elderly people.
So how did Tropical Cyclone Dominic increase the intensity of that heat wave? And how do tropical lows in Australia's west — like the one we're seeing again this week — affect the weather as far away as south-eastern Australia?
When the pressure's on
It turns out that the position of the tropical cyclone, rather than its size or severity, is what really makes a difference.
It doesn't even need to be a full-blown cyclone; as we're currently seeing, even a tropical low can have a big impact on south-eastern Australia's weather.
Heat waves in Victoria are associated with slow-moving high pressure systems, or anticyclones. These surface highs hang around over the Tasman Sea for several days, bringing hot northerly winds from the interior of the continent.
During heat waves in Victoria, there is also a similar anticyclone at higher levels in the atmosphere.
These upper level anticyclones form when very long, planetary-scale waves in the atmosphere (known as Rossby waves) break to the south of Australia.
Our recent research showed for the first time in Australia how those upper level anticyclones have been present in all of the most severe heat waves in Victoria over the past two decades.
How cyclones work
The circulation around tropical cyclones at low levels is cyclonic, as air spirals in a clockwise direction (in the Southern Hemisphere; it spirals the other way in the Northern Hemisphere) into the centre of the storm where the pressure is lowest.
At upper levels, the air flows out again from the centre, and its nature changes to anticyclonic, switching to rotate in an anti-clockwise direction.
This outflowing air can intensify heat waves over Victoria in two ways. The first is when the outflow "nudges" the upper level jet stream, the band of strong westerly winds that circle the globe at mid-latitudes in both hemispheres.
When the outflowing air from the tropical cyclone nudges the jet stream south of western Australia, the disturbance generates more waves. This results in a stronger upper level anticyclone over Victoria.
The second way in which the intensification can occur is a direct result of the anticyclonic properties of the outflowing air. The outflowing air can be carried by the winds directly into the upper level anticyclone over Victoria.
The more intense the upper level anticyclone over Victoria, the more persistent it will be. This makes it more likely that a heat wave will form as higher temperatures continue for several days.
You can imagine this as being a bit like putting a pebble into a stream. The larger the pebble, the harder it will be for the water to shift it, and the more likely it is that the pebble will remain in place for a while as the water flows around it.
The cyclone effectively makes the pebble that is the anticyclone a little bit bigger, so that it stays stationary for longer.
Our improved understanding of how heat waves form should help weather forecasters better predict when extreme heat waves will hit Victoria.
It will also help in studies of how the intensity and duration of heat waves might change in the future due to climate change.
But in the short-term, when the heat is on at Rod Laver Arena this week: take a look way out west — and watch out for those cyclones.
Tess Parker is a PhD candidate at Monash University. She has been supported in part by the Australian Research Council Centre of Excellence for Climate System Science.
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WHOI Unveils Website on its Role in Gulf Oil Spill Research
One year after the explosion of the Deepwater Horizon drilling platform in the northern Gulf of Mexico, the Woods Hole Oceanographic Institution (WHOI) is unveiling a new multimedia website, Science in a Time of Crisis. The site features scientists and engineers who continued the WHOI legacy of oil spill research by providing an objective insight into the immediate and potential impacts of the historic event, which took 11 lives and released millions of gallons of oil and gas into the Gulf over three months.
Science in a Time of Crisis provides an inside look at how people at the institution mobilized to provide the Obama Administration, the National Oceanic and Atmospheric Administration (NOAA), U.S. Coast Guard, U.S. Geological Survey and other groups responding to the spill with invaluable research and leadership capability in investigating the effects of the Deepwater Horizon spill and how to deal with deep water spills in the future.
Within days of the start of the largest accidental marine oil spill in history, WHOI scientists, engineers, technicians, and administrators were among those called upon to help with the response. More than 100 people from the institution, utilizing a wide range of equipment, vehicles, and vessels, have participated in the research effort since the accident on April 20, 2010.
In a series of comprehensive videos, which include interviews with many of the scientists and engineers involved, the website presents a picture of the spill’s events and impacts through a range of WHOI’s scientific and technical capabilities: estimating flow rate; mapping Gulf currents; modeling the deep-water plume; visualizing the oil; studying the critically important oil/bacteria relationship; tracing the dispersants; studying impacts on the Gulf’s deep-water habitats. All of this work was possible only because of the expertise and technology developed at WHOI over many decades for basic research in ocean sciences.
"WHOI's good work in response to the oil spill is testimony to the world-class work we do here regularly," said WHOI Trustee Robert James, who, along with his wife Anne, made a generous donation to WHOI to fund the project. “The nation needed a deep bench of scientists with relevant experience and the technology to get the job done. Our nation is fortunate that WHOI made these people and tools accessible to study the spill. Our job now is to communicate to the world the depth and breadth of WHOI expertise across all disciplines."
One video focuses on four generations of WHOI scientists who have studied the 1969 spill of 189,000 gallons of No. 2 home heating oil into Buzzards Bay, Massachusetts. Their work on Buzzards Bay produced the longest and most detailed study of an oil spill in history. Today, the research is widely considered to be the most important baseline study that scientists have for assessing the long-term effects of oil spills in marine environments. Since then, WHOI has played a role studying other major oil spills over the years.
Another details the efforts of WHOI scientist Rich Camilli and WHOI engineer Andy Bowen to produce the most direct measurement of the disaster’s flow rate and provide invaluable information for the response efforts. And another video follows Chris Reddy, Camilli and others as—utilizing a novel mass spectrometer and the underwater vehicle Sentry—they confirm the existence of a 22-mile-long underwater plume of hydrocarbons that gushed from the wellhead.
The website, which can be accessed at www.whoi.edu/deepwater horizon, also features a timeline of the spill and its aftermath and a technology slideshow, and related resources. The site links to the “Oil in the Ocean” website (whoi.edu/oilinocean), a comprehensive source for information on WHOI research related to natural and human-made sources of oil in the ocean.
Bob James emphasized that in addition to uncovering data that shed light directly on the oil spill, the work also has yielded a lot of other data that could provide insights into many other areas of study. WHOI scientists acted with “alacrity and responsibility in realizing that a lot of ancillary data gained in their work could be of further use if mined properly for the good of research,” he said.
"Our scientists had the presence of mind to take comprehensive samples and lay out a plan to analyze data for the sake of science and the scientific method," he said. "We will learn things from that collateral data that could help us answer many other scientific questions."
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.
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A multimedia presentation featuring scientists and engineers who continued the Woods Hole Oceanographic Institution legacy of oil spill research by providing an objective insight into the immediate and potential impacts of the Deepwater Horizon spill in the Gulf of Mexico. ">
A multimedia presentation featuring scientists and engineers who continued the Woods Hole Oceanographic Institution legacy of oil spill research by providing an objective insight into the immediate and potential impacts of the Deepwater Horizon spill in the Gulf of Mexico. | <urn:uuid:8e15cf49-870f-4632-9240-6a0100c9db74> | 3.125 | 1,109 | News (Org.) | Science & Tech. | 29.872803 | 95,582,717 |
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Beak: hard mouth parts of animals such as those found on birds.
Entomologist: name for scientist who studies insects.
The insects that experts call bugs have many different body shapes, sizes and colors. However, the one thing they all have in common is a long slender beak shaped mouth part that looks like a straw. They use this beak to poke through plants and occasionally animal skin and suck out sap or blood.
Most true bugs have their front pair of wings partially hardened and only the tips clear, it looks like they have half a wing. Entomologists use this strange wing shape to give this group of insects their official name, “Hemiptera”, which means half wing in Greek. Their rear pair of wings is shorter than the front half wings and are completely clear except for the thin lines that run their length. These lines are called veins and strengthen the wing in flight and help provide folds to store the wing under the front wings when not flying.
Hemiptera also have antennae with very few joints (segments), usually about five. Their number of foot joints (tarsi) is also small with usually no more than three. All the other insect groups that look similar to Hemiptera, like cockroaches and some beetles, have much longer antennae and feet with more segments in them.
How true bugs are organized is shown in the diagram below. The order for all true bugs is Hemiptera which is divided into four suborders, Auchenorrhyncha, Coleorrhyncha, Heteroptera and Stemorrhyncha.
Dr. Biology. (2010, October 06). True Bug Characteristics. ASU - Ask A Biologist. Retrieved July 17, 2018 from https://askabiologist.asu.edu/true-bug-anatomy
Dr. Biology. "True Bug Characteristics". ASU - Ask A Biologist. 06 October, 2010. https://askabiologist.asu.edu/true-bug-anatomy
Dr. Biology. "True Bug Characteristics". ASU - Ask A Biologist. 06 Oct 2010. ASU - Ask A Biologist, Web. 17 Jul 2018. https://askabiologist.asu.edu/true-bug-anatomy | <urn:uuid:e1bd45e6-3621-446f-9142-7eff006b131d> | 3.59375 | 503 | Knowledge Article | Science & Tech. | 63.535671 | 95,582,718 |
Mars is approaching Earth for a 15-year close encounter on July 27. The Red Planet is now so bright that it is experiencing forms of atmospheric optics normally reserved for objects like the sun and the moon. Recently, an astronomer in Sweden watching Mars witnessed a rare green flash. Visit Spaceweather.com for a video of the phenomenon and more information about the Martian brightening.
On the heels of a new study showing that flight attendants have an elevated risk of cancer compared to the general population, Spaceweather.com and the students of "Earth to Sky Calculus" recently boarded a plane to New Zealand carrying an array of cosmic ray sensors. During their 13-hour flight across the South Pacific, the team detected secondary cosmic rays in the passenger compartment almost 40 times stronger than on the ground below. Their "haul" of radiation included a significant number of neutrons captured in portable bubble chambers. Read Spaceweather.com for the full story.
A comet that could become visible to the naked eye in August has exploded in brightness, suddenly increasing its luminosity 16-fold. Whatever happened on Comet PANSTARRS (C/2017 S3) on July 1 has given it an expanding green atmosphere almost twice the size of the planet Jupiter. Visit Spaceweather.com for pictures and more information about this approaching comet.
Password managers are a pain to set up, but they make us feel safe. Read this story and think again!
Massachusetts Institute of Technology (MIT) welcomes constructive ideas that might help solve the world's problems, grouped into four categories: LEARN, CURE, FUEL, MAKE. Contest winners in each category will go to the United Nations on March 7, 2017, to present their ideas. Learn more, read the challenges, and propose solutions at this link: SOLVE
New installation at Coyote Point in San Mateo lets visitors visualize how sea-level rise impacts bayside and coastside.
The San Francisco Chronicle "Insight" section Sunday, April 17, is loaded with goodies for anyone interested in social media, print media, Internet trolls, selfie obsessions, smartphone abuse, technology addiction, etc. Here are two of the best pieces:
Sign up here to get an email whenever the International Space Station passes overhead. Warning: Don't bother on foggy or cloudy nights.
Here's some intriguing new research on what makes smart people happier: Is it more friends or more space?
It's complicated: part religion, part politics, part astrophysics. Historian and columnist Dr. Amanda Foreman explains at the link above.
Is Caltrans paying attention?
The night of February 23-24, observers across the western half of North America witnessed a spectacular cluster of bright lights in the sky. It was the re-entry and disintegration of a Chinese rocket body. Coincidentally, a geomagnetic storm was in progress at the time and more than one photographer caught the rocket's debris cutting across curtains of Northern Lights. Visit spaceweather.com for photos and more information. | <urn:uuid:6168121f-3007-4c75-9f6c-d902f74bcd22> | 3.015625 | 627 | Content Listing | Science & Tech. | 46.296386 | 95,582,736 |
CHINESE BOFFINS claim to have taken an important step towards the creation of "unhackable" communications, transmitting a quantum signal 1,200km from China's communications satellite Micius to Earth.
The experiment, the results of which are published in Science, demonstrates "satellite-based distribution of entangled photon pairs to two locations separated by 1203 kilometres on Earth, through two satellite-to-ground downlinks," the scientists wrote.
The experiment is significant because it could pave the way for a highly secure global communications system.
Quantum entanglement is the phenomenon by which the quantum states of two subatomic particles are connected. Changing the state of one by observing it or otherwise interfering will instantaneously change the state of the other, even if they are at opposite sides of the universe. This means information can be transmitted securely because if anyone changes or even observes the data, this will be obvious to the receiving party.
However, controlling the states of entangled particles in the real world is a uniquely challenging task. Transmitting entangled particles through fibres or through the open air tends to break the entanglement as the particles interact with the medium. However, they are much more stable in the near-vacuum conditions of space.
In the current experiment, a laser beam projected from the satellite was split into two polarised states. One of these beams was used to transmit the entangled photons, while the other served to receive the photons. The scientists found that photons retained their entangled states during their journey to Earth.
"The obtained effective link efficiency is orders of magnitude higher than that of the direct bidirectional transmission of the two photons through telecommunication fibres," Juan Yin, lead author and physicist at the Science and Technology University of China in Shanghai, said.
Of course, conveying real-world communication data between two points is a very different matter from transmitting a pair of entangled photons, at least using current methods, and the way that quantum signals will be relayed between satellites remains to be worked out.
Nevertheless, the leap in the distance over which such transmissions are now possible surely brings the era of ultra-secure communications a step closer. µ
Celebrity Apprentice star says Europe has 'taken advantage of the US'
1995 called, they want their news item back
LG's gaming-focused monitor is impressive and affordable
It's now safe to eat croissants over your laptop again | <urn:uuid:58d246f5-004c-4169-9b7d-72e699720513> | 3.34375 | 493 | News Article | Science & Tech. | 24.104333 | 95,582,748 |
+44 1803 865913
By: Eugenie Regan
128 pages, photos
Irish Butterflies and Insects is an attractive introduction to the fascinating, hidden world of Ireland's littlest animals. They are the most abundant and diverse animals in Ireland yet are often an overlooked part of Irish fauna.
Here are some of the most commonly encountered species complete with full-colour, detailed illustrations to aid identification. Creatures profiled are dragonflies, butterflies and moths, beetles, grasshoppers, bees, ants and a few less-liked species as well such as fleas and wasps. This book is perfect field guide for anyone out and about who wants to know just what they have spotted.
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On behalf of Parque Nacional Nahuel Huapi I would like to thank NHBS. The book will be very useful for my students.
Search and browse over 110,000 wildlife and science products
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Wildlife, science and conservation since 1985 | <urn:uuid:732abb22-90f7-41e8-915b-4111b88bf316> | 2.84375 | 233 | Product Page | Science & Tech. | 47.229326 | 95,582,760 |
study of transplanting dates on drought resistant rice cultivars
Droughts are a major hazard to both natural and human-dominated environments and those, especially of long duration and high intensity, can be highly damaging and leave long-lasting effects. This book describes the climatic conditions that give rise to droughts, and their various forms and chief attributes. Past droughts are described including those that had severe impacts on human societies. As a disturbance, droughts can be thought of as “ramps” in that they usually build slowly and take time to become evident. As precipitation is reduced, flows from catchments into aquatic systems decline. As water declines in water bodies, ecological processes are changed and the biota can be drastically reduced, though species and populations may survive by using refuges. Recovery from drought varies in both rates and in degrees of completeness and may be a function of both refuge availability and connectivity. For the first time, this book reviews the available rather scattered literature on the impacts of drought on the flora, fauna and ecological processes of aquatic ecosystems ranging from small ponds to lakes and from streams to estuaries. The effects of drought on the biota of standing waters and flowing waters and of temporary waters and perennial systems are described and compared. In addition, the ways in which human activity can exacerbate droughts are outlined. In many parts of the world especially in the mid latitudes, global warming may result in increases in the duration and intensity of droughts. Drought and Aquatic Ecosystems is essential reading for freshwater ecologists, water resource managers and advanced students. | <urn:uuid:83e4d6af-6bc2-4eef-b907-a9d1936a6439> | 3.828125 | 329 | Truncated | Science & Tech. | 25.824284 | 95,582,775 |
When lines and circles are all the same!
May 22, 2012
Bailey Hall 207
Refreshments will be served in Bailey Hall 204 at 4:30
After points, lines are the simplest geometric objects. But what can be considered a 'line', really? Does it always have to be straight? Complex numbers can provide an innovative approach to this question; they not only help us understand euclidean geometry better, but also suggest other models for geometry.
|Union College Math Department Home Page|
Comments to: email@example.com
Created automatically on: Mon Jul 23 04:06:12 EDT 2018 | <urn:uuid:cd1104b9-9f64-4855-83c5-8176fb737e12> | 2.609375 | 129 | News (Org.) | Science & Tech. | 59.28875 | 95,582,780 |
Species Detail - Whirlpool Ramshorn (Anisus (Disculifer) vortex) - Species information displayed is based on the dataset "All Ireland Non-Marine Molluscan Database".
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Anisus (Disculifer) vortex
Threatened Species: Vulnerable
28 January (recorded in 1995)
30 October (recorded in 1973)
Conchological Society of Great Britain and Ireland, All Ireland Non-Marine Molluscan Database, National Biodiversity Data Centre, Ireland, Whirlpool Ramshorn (Anisus (Disculifer) vortex), accessed 23 July 2018, <https://maps.biodiversityireland.ie/Dataset/1/Species/123335> | <urn:uuid:81b37205-9cdd-4dc6-bb01-102e8099bbf3> | 2.5625 | 208 | Structured Data | Science & Tech. | 14.440765 | 95,582,785 |
The Java language is a general-purpose programming language for platform-independent software development. As described in Java White Papers (Sun Microsystems, Inc.), “Java is simple, object-oriented, distributed, interpreted, robust, secure, architecture-neutral, portable, high-performance, multithreaded and dynamic.”
KeywordsClass Object Java Program File Object Class String Class Customer
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Published on Feb 16, 2016
The objective: I wanted to find out how temperature affects a plant's ability to transport nutrients. From my research, I learned that transpiration and respiration increase as temperature increases. I thought the plants in room temperature would transport the most nutrients because the plants in the other temperatures were too hot or too cold.
Ten white carnations were placed in each of three mugs with 200 ml of water.
Then 1/4 teaspoon of food coloring was added into each mug.
Each mug was placed in a box in a different temperature zone with a thermometer in each mug.
A plant light was placed over each box and observations and measurements were made every few hours recording the results.
The results showed that flowers which were in 110 degrees Fahrenheit soaked up the most water. However, the petals of the flowers dried out.
The flowers in the 68 degrees Fahrenheit transported a little more water than the flowers at room temperature (78 degrees Fahrenheit).
The hypothesis was incorrect because it was thought that the flowers in room temperature would transport the most nutrients, but actually, the flowers in the heated temperature soaked up the most water.
This information is important for growing plants at the right temperature so they will be healthy.
If this project was repeated, the flowers would be placed in solutions 10 degrees apart to find out how much the slightest temperature change would affect the plant's ability to transport nutrients.
The purpose of this project was to determine if different temperatures would affect a plant's ability to transport nutrients; the data showed that plants exposed to warmer temperatures soaked up the most water.
Science Fair Project done By Kayla Billiou | <urn:uuid:5411c58b-c3f3-4a2c-af1a-52f5c2e1a424> | 4.15625 | 337 | Personal Blog | Science & Tech. | 46.017055 | 95,582,812 |
Small C++ program to display images in a (modern) terminal using RGB ANSI codes and unicode block graphic characters.
There are various similar tools (such as
timg) using the unicode half block character to display two 24bit pixels per character cell. This program enhances the resolution by mapping 4x8 pixel cells to different unicode characters, using the following algorithm:
For each 4x8 pixel cell of the (potentially downscaled) image:
- Find the color channel (R, G or B) that has the biggest range of values for the current cell
- Split this range in the middle and create a corresponding bitmap for the cell
- Compare the bitmap to the assumed bitmaps for various unicode block graphics characters
- Re-calculate the foregound and background colors for the chosen character.
See the difference by disabling this optimization using the
-0 option. Or just take a look at the comparsion image at the end of this text.
sudo apt install imagemagick || yum install ImageMagick git clone https://github.com/stefanhaustein/TerminalImageViewer.git cd TerminalImageViewer/src/main/cpp make sudo make install
tiv [options] <filename(s)>
The shell will expand wildcards. By default, thumbnails and file names will be displayed if more than one image is provided. To display a list of options, just run the command without any parameters.
- If you see strange horizontal lines, the characters don't fully fill the character cell. Remove additional line spacing in your terminal app
- Wrong colors? Try -256 to use a 256 color palette instead of 24 bit colors
If multiple images match the filename spec, thumbnails are shown.
Comparison to Using Half-Block Characters Only
The top image was generated with the character optization diabled via the | <urn:uuid:d394ee10-5b23-43e7-8c16-595eec45ea2a> | 2.625 | 399 | Product Page | Software Dev. | 38.275456 | 95,582,817 |
posted by Randy
I am so lost on these problems.
Write a geometric sequence that starts with 3 and has a common ratio of 5. What is the 23rd term in the sequence.
Write an arithmetic sequence that has a common difference of 4 and the eighth term is 13. What is the first term? What is the 23rd term in the sequence.
Write an arithmetic sequence where 12 is the first term of 12, and the tenth term is 39. What is the first term? What is the 23rd term in the sequence.
Two consecutive terms of a geometric sequence, in order are 10 and 12. What is the ratio. What is the term before 10? What is the term after 12?
well, they have said that
The 23rd term is thus 3*5^22
That is, you start with 3 and multiply by 5 22 more times to get to the 23rd term.
Next, we have
a + 7*4 = 13
so, a = -15
T23 = -15 + 22*4
Any two consecutive terms of a geometric sequence have a common ratio. In this case, we have
r = 12/10 = 6/5
So, to get the term before 10, divide by 6/5
To get the term after 12, multiply by 6/5 | <urn:uuid:5daf561f-4194-4f3b-9761-a0c0adcb22ef> | 3.796875 | 276 | Q&A Forum | Science & Tech. | 94.321742 | 95,582,819 |
The glitter of gold may hold more than just beauty, or so says a team of researchers from the Massachusetts Institute of Technology (MIT) that is working on ways to use tiny gold rods to fight cancer, deliver drugs and more.
But before gold nanorods can live up to their potential, scientists must figure out how to overcome one major difficulty: The surfaces of the tiny particles are coated with an unco-operative molecule (a byproduct of the synthesis process) that prevents researchers from creating nanorods with the features they want.
“The surface chemistry is really key to everything,” said Kimberly Hamad-Schifferli, assistant professor of biological and mechanical engineering at MIT. “For all of these nifty applications to work, someone’s got to sit down and do the dirty work of understanding the surface.”
Hamad-Schifferli and her colleagues published two papers this month describing ways to manipulate the nanorods’ surface, which could allow researchers to design nanorods with specific useful functions.
As their name implies, gold nanorods are tiny cylinders of gold, about 10 billionths of a metre wide and 40 billionths of a metre long.
They differ from traditional, spherical gold nanoparticles in one very important respect – they can absorb infrared light. That means they can theoretically be activated by infrared laser without damaging surrounding cells, which do not absorb infrared light.
Before that can happen, scientists must figure out how to deal with an organic molecule known as CTAB that coats the outer surface of gold nanorods and tends to detach from and reattach itself to the surface. The molecule, a byproduct of the synthesis reaction that produces the nanorods, makes it difficult to attach other molecules for delivery, such as drugs or DNA.
The team’s two recent papers describe how the CTAB influences heat dissipation and how to remove the CTAB and replace it with another organic molecule.
In the first paper, published online on 12 August in the Journal of Physical Chemistry C, they found that a low concentration of the CTAB in the surrounding solution accelerates heat dissipation after the nanorod is hit with infrared light. When the concentration of CTAB is high, heat is dissipated more slowly.
That information could help scientists design nanorods that fight cancer agents by burning away tumour cells when activated with infrared light.
In the second paper, published online on 22 August in the journal Langmuir, the team demonstrated how to replace CTAB with a more useful molecule – a sulphur-containing group known as a thiol. This molecule binds more strongly to the nanorod, so it doesn’t detach and reattach like CTAB. In addition, other molecules, such as DNA, can be easily attached to the end of the thiol.
These surface chemistry studies are critical to lay the groundwork for development of gold nanorods, according to Hamad-Schifferli.
“People have dreamed up all of these cool applications for nanorods, but one of the biggest bottlenecks to making this a reality is this interface,” she said.
In the future, Hamad-Schifferli and her colleagues hope to build gold nanorods that carry DNA designed for a specific function in the target cell. For example, the DNA could shut down production of a protein that is being over expressed.
This article was written by Anne Trafton and originally appeared on the MIT News Office Web site on 22 August 2008. | <urn:uuid:a7a96269-0c66-4cfc-856d-0aa2fc8df14f> | 3.96875 | 739 | Truncated | Science & Tech. | 33.6843 | 95,582,824 |
The Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA's Aqua satellite captured a visible image of Soulik on July 9 at 1:25 UTC (July 8 at 9:25 p.m. EDT). The image shows a tight concentration of thunderstorms around the typhoon's center and feeder bands of thunderstorms wrapping into the center from the northeast and southwest.
This visible image from July 9 at 1:25 UTC was taken by the MODIS instrument that flies aboard NASA's Aqua satellite shows strong thunderstorms around Tropical Storm Soulik's center.
Credit: NASA Goddard MODIS Rapid Response Team
According to the Joint Typhoon Warning Center, on July 9 at 1500 UTC (11 a.m. EDT), Typhoon Soulik had maximum sustained winds near 95 knots (109 mph/176 kph) and is still strengthening.
Soulik's center was located near 20.3 north latitude and 138.1 east longitude, about 678 nautical miles (780 miles/1,256 km) east-southeast of Kadena Air Base, Japan. Soulik is moving to the west-southwest at 12 knots (13.8 mph/22.2 kph) and generating very rough seas with wave heights to 32 feet (9.7 meters).
Soulik is intensifying as it moves west across the open Pacific and is expected to make a landfall in southeastern China sometime over the weekend of July 13 and 14.
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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.
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In the moth Manduca sexta, also known as the tobacco hornworm and recognisable by its distinctive blue-green caterpillar, adult body size is largely determined at the end of larval life, when the caterpillar has reached it final weight and is about to metamorphose into a moth.
In a study published today in the open access journal Journal of Biology, Frederik Nijhout, from Duke University in Durham, USA and colleagues built a new mathematical model that allows them to predict the size of an adult moth, on the basis of three parameters: the initial weight of the juvenile caterpillar, its growth rate and the rate at which the effect of a developmental hormone decays. These three factors are independent of each other and each of them is determined by many genes.
The regulation of body size is therefore the result of the interactions among many genes involved in many different processes. These processes are themselves strongly influenced by external factors such as temperature and nutrition and Nijhout et al.’s study therefore sheds light on how environmental and genetic factors can interact to determine final adult body size. Their new model is likely to have broad applicability and could explain size variations in flies and other insects as well as in moths.
Juliette Savin | alfa
Pollen taxi for bacteria
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Biological signalling processes in intelligent materials
18.07.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
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
18.07.2018 | Life Sciences
18.07.2018 | Life Sciences
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Current measurements at Campus Wechloy
Last sky image
Air temperature and relative humidity
Wind direction and -speed
Today's course of wind direction and -speed are shown as a timeseries. Both parameters are displayed as 10 minute averages. Furthermore the maximum windspeed of the last 10 minutes (gusts) are shown in the upper graph. The sensor is installed about 6.5m above the rooftop.
past 7 days
The course of the solar irradiance ( top: global radiation (red), diffuse radiation (green), theoretical clear sky radiation (dotted); bottom: direct normal radiation ) measured every second but displayed as minutely averages.
past 7 days
High-resolution measurements (1s sample rate) of last 20 minutes to visualize the short-term variability of solar irradiance due to passing clouds.
On the rooftop of the building W2 on the Campus Wechloy ( Pos.: 53°9'8.38''N 8°9'57.68''E ) several meteorological and solar energy related instruments for scientific research are installed.
The cloud camera is the webcam-based surveillance camera Vivotek FE8172V. The fish eye lens allows a field of view of 180°. Images are collected and archived every 10 seconds. Cloud coverage and dominant cloud types are calculated automatically based on machine learning algorithms.
Photo: cloud camera with fish eye lens; Copyright: John Kalisch
Air temperature and relative humidity are measured with a Theodor Friedrichs Typ 3031 in a ventilated housing.
Wind speed and direction
The wind measurement takes place in 6.5 meters above the roof with a cup anemometer and wind vane from the manufacturer Thies. Measurements are acquired every second but averaged for visualization to 10 minute averages.
Photo: wind measurements on Campus Wechloy. Copyright: Thomas Schmidt
Global and Diffuse radiation
Surface solar irradiance ( global and diffuse ) are measured with Kipp & Zonen CM11 pyranometers. The sensor for diffuse radiation is mounted on a suntracker with shadow balls in order to block the direct sun. Since december 2013 both sensors are actively ventilated to prevent water droplets and icing on its domes.
Foto: Sun tracker with CM11 Pyranometer for diffuse radiation measurements; Copyright: John Kalisch
Direct normal radiation
Direct Normal Radiation (DNI) is measured with the "normal incidence pyrheliometer" NIP from Eppley.
Photo: Sun tracker with Eppley NIP for measuring direct normal radiation; Copyright: John Kalisch
Spectrally resolved radiation is measured with a RAMSES ACC VIS of the manufacturer TRIOS. It measures in the range of 350 - 900 nm wavelength.
Foto: Spectral radiometer RAMSES. Copyright: Thomas Schmidt | <urn:uuid:1a93fa74-88d6-44ba-8d91-2a0a9045cf39> | 2.71875 | 583 | Knowledge Article | Science & Tech. | 35.083245 | 95,582,871 |
Over the course of two days, from Nov. 1 to Nov. 3, NASA's Aqua satellite watched from space as Tropical cyclone Nuri strengthened into a Super Typhoon and "opened" or developed an eye.
On Nov. 1, when the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite captured a visible image of Super Typhoon Nuri at 04:30 UTC (12:30 a.m. EDT) and it had not yet developed an eye.
On Nov. 3 at 04:20 UTC (12:20 a.m. EDT) NASA's Aqua satellite captured this image of Super Typhoon Nuri after it developed an eye.
Image Credit: NASA Goddard MODIS Rapid Response Team
On Nov. 3 at 04:20 UTC (12:20 a.m. EDT) MODIS on Aqua passed over Super Typhoon Nuri again after it developed an eye. By Nov. 3 the bands of thunderstorms spiraling into the center of the low-level circulation had become more tightly wrapped.
The image also showed that the widest band of thunderstorms were over the northern and eastern quadrants of the storm.
At 1500 UTC (10 a.m. EST) on Nov. 3, Nuri's maximum sustained winds had reached 155 knots (178.4 mph/ 287.1 kph), making it a Category 5 hurricane on the Saffir-Simpson wind scale. Some minor intensification is expected before the storm begins to weaken on Nov. 4.
Nuri was centered near 20.2 north latitude and 133.9 east longitude, about 514 nautical miles (591.5 miles/ 951.9 km) southeast of Kadena Air Base, Okinawa, Japan. It was moving to the northeast at 10 knots (11.5 mph/18.5 kph).
Nuri is expected to pass west of Iwo To on Nov. 5 as it continues moving in a northeasterly direction. For current weather conditions in Iwo To (also known as Iwojima), visit: http://weather.noaa.gov/weather/current/RJAW.html
Nuri is expected to intensify further before weakening. Adverse conditions will cause the storm to go on a weakening trend and the storm is expected to become extra-tropical after three or four days.
NASA's Goddard Space Flight Center
Rob Gutro | 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....
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Problem of points
The problem of points, also called the problem of division of the stakes, is a classical problem in probability theory. One of the famous problems that motivated the beginnings of modern probability theory in the 17th century, it led Blaise Pascal to the first explicit reasoning about what today is known as an expectation value.
The problem concerns a game of chance with two players who have equal chances of winning each round. The players contribute equally to a prize pot, and agree in advance that the first player to have won a certain number of rounds will collect the entire prize. Now suppose that the game is interrupted by external circumstances before either player has achieved victory. How does one then divide the pot fairly? It is tacitly understood that the division should depend somehow on the number of rounds won by each player, such that a player who is close to winning will get a larger part of the pot. But the problem is not merely one of calculation; it also includes deciding what a "fair" division should mean in the first place.
Luca Pacioli considered such a problem in his 1494 textbook Summa de arithmetica, geometrica, proportioni et proportionalità. His method was to divide the stakes in proportion to the number of rounds won by each player, and the number of rounds needed to win did not enter his calculations at all.
In the mid-16th century Niccolò Tartaglia noticed that Pacioli's method leads to counterintuitive results if the game is interrupted when only one round has been played. In that case, Pacioli's rule would award the entire pot to the winner of that single round, though a one-round lead early in a long game is far from decisive. Tartaglia constructed a method that avoids that particular problem by basing the division on the ratio between the size of the lead and the length of the game. This solution is still not without problems, however; in a game to 100 it divides the stakes in the same way for a 65–55 lead as for a 99–89 lead, even though the former is still a relatively open game whereas in the latter situation victory for the leading player is almost certain. Tartaglia himself was unsure whether the problem was solvable at all in a way that would convince both players of its fairness: "in whatever way the division is made there will be cause for litigation".
Pascal and Fermat
The problem arose again around 1654 when Chevalier de Méré posed it to Blaise Pascal. Pascal discussed the problem in his ongoing correspondence with Pierre de Fermat. Through this discussion Pascal and Fermat not only came up with a convincing, self-consistent solution to the division of the stakes, but also developed concepts that continue to be fundamental in probability to this day.
The starting insight for Pascal and Fermat was that the division should not depend so much on the history of the part of the interrupted game that actually took place, as on the possible ways the game might have continued, were it not interrupted. It is intuitively clear that a player with a 7–5 lead in a game to 10 has the same chance of eventually winning as a player with a 17–15 lead in a game to 20, and Pascal and Fermat therefore thought that interruption in either of the two situations ought to lead to the same division of the stakes. In other words, what is important is not the number of rounds each player has won yet, but the number of rounds each player still needs to win in order to achieve overall victory.
Fermat now reasoned thus: if one player needs r more rounds to win and the other needs s, the game will surely have been won by someone after '"`UNIQ--postMath-00000001-QINU`"' additional rounds. Therefore, imagine that the players were to play '"`UNIQ--postMath-00000002-QINU`"' more rounds; in total these rounds have '"`UNIQ--postMath-00000003-QINU`"' different possible outcomes. In some of these possible futures the game will actually have been decided in fewer than '"`UNIQ--postMath-00000004-QINU`"' rounds, but it does no harm to imagine the players continuing to play with no purpose. Considering only equally long futures has the advantage that one easily convinces oneself that each of the '"`UNIQ--postMath-00000005-QINU`"' possibilities is equally likely. Fermat was thus able to compute the odds for each player to win, simply by writing down a table of all '"`UNIQ--postMath-00000006-QINU`"' possible continuations and counting how many of them would lead to each player winning. Fermat now considered it obviously fair to divide the stakes in proportion to those odds.
Fermat's solution, certainly "correct" by today's standards, was improved by Pascal in two ways. First, Pascal produced a more elaborate argument why the resulting division should be considered fair. Second, he showed how to calculate the correct division more efficiently than Fermat's tabular method, which becomes completely impractical (without modern computers) if '"`UNIQ--postMath-00000007-QINU`"' is more than about 10.
Instead of just considering the probability of winning the entire remaining game, Pascal devised a principle of smaller steps: Suppose that the players had been able to play just one more round before being interrupted, and that we already had decided how to fairly divide the stakes after that one more round (possibly because that round lets one of the players win). The imagined extra round may lead to one of two possible futures with different fair divisions of the stakes, but since the two players have even chances of winning the next round, they should split the difference between the two future divisions evenly. In this way knowledge of the fair solutions in games with fewer rounds remaining can be used to calculate fair solutions for games with more rounds remaining.
It is easier to convince oneself that this principle is fair than it is for Fermat's table of possible futures, which are doubly hypothetical because one must imagine that the game sometimes continues after having been won. Pascal's analysis here is one of the earliest examples of using expectation values instead of odds when reasoning about probability. Shortly after, this idea would become a basis for the first systematic treatise on probability by Christiaan Huygens. Later the modern concept of probability grew out of the use of expectation values by Pascal and Huygens.
The direct application of Pascal's step-by-step rule is significantly quicker than Fermat's method when many rounds remain. However, Pascal was able to use it as a starting point for developing more advanced computational methods. Through clever manipulation of identities involving what is today known as Pascal's triangle (including several of the first explicit proofs by induction) Pascal finally showed that in a game where one player needs r points to win and the other needs s points to win, the correct division of the stakes is in the ratio of (using modern notation)
Though Pascal's derivation of this result was independent of Fermat's tabular method, it is clear that it also describes exactly the counting of different outcomes of '"`UNIQ--postMath-00000009-QINU`"' additional rounds that Fermat suggested.
- Anders Hald: A history of Probability and Statistics and their Applications before 1750. Wiley 2003, ISBN 978-0-471-47129-5, p. 35, 54
- Keith Devlin: The Unfinished Game: Pascal, Fermat, and the Seventeenth-Century Letter that Made the World Modern. Basic Books 2010, ISBN 978-0465018963
- Lua error in Module:Citation/CS1 at line 746: Argument map not defined for this variable.
- The Early Development of Mathematical Probability
- Problem of points at MathForum
- Lua error in Module:Citation/CS1 at line 746: Argument map not defined for this variable. Section 11.3.1
- Tartaglia, quoted by Katz (op.cit.), from Oystein Ore, "Pascal and the Invention of Probability Theory", American Mathematical Monthly 67 (1960), 409–419, p.414.
- Pascal, letter to Fermat, quoted in F. N. David (1962) Games, Gods, and Gambling, Griffin Press, p. 239.
- Katz, op.cit., Section 11.3.2
- Lua error in Module:Citation/CS1 at line 746: Argument map not defined for this variable. Digital facsimile at the Cambridge University Library (in French) with short English summary | <urn:uuid:83546f5f-aeb6-4e92-bc3d-ccc4091c5fd4> | 3.375 | 1,808 | Knowledge Article | Science & Tech. | 44.601411 | 95,582,891 |
Reconnection, the merging of magnetic field lines of opposite polarity near the surface of the sun, Earth and some black holes, is believed to be the root cause of many spectacular astronomical events such as solar flares and coronal mass ejections, but the reason for this is not well understood. Researchers at Los Alamos National Laboratory now have a new theory that may explain the instability and advance the understanding of these phenomena.
Theorists Giovanni Lapenta of Los Alamos National Laboratorys Plasma Theory group and Dana Knoll of the Labs Fluid Dynamics group presented their findings at the American Geophysical Union meeting in San Francisco at the Moscone Convention Center.
The theory is based on a 19th century mathematical observation called Kelvin-Helmholtz instability. "What we are trying to determine is why magnetic field lines loop out from the surface of the sun, reconnect and then fall back," said Lapenta. "And why these systems, which look very stable, are in fact quite unstable."
Kevin Roark | 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
12.07.2018 | Event News
03.07.2018 | Event News
23.07.2018 | Science Education
23.07.2018 | Health and Medicine
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Inscentinel Honeybees Sniff For Explosives
Inscentinel Ltd. has found a way to use honeybees as sensitive, chemical-trace-detecting micromachines. The bees are first trained and then literally harnessed into a special cassette to aid in the process of biochemical molecular recognition.
(Inscentinel honebees at work)
Honeybees are trained to recognize particular odors (for example, that of explosive compounds), and then to associate that smell with a food reward. Bees are able to recognize odors that are as faint as only a few parts per trillion in an air sample. When the bees detect the special odor, they extend their proboscis in expectation of receiving food.
(Inscentinel honebees at strapped into their cartridge)
Trained bees are then carefully strapped into a cartridge. A sample of air is introduced into their little chamber. A digital camera watches the bees carefully; if the bees detect a trace of the odor that they have been trained to recognize, image recognition software will see the bees extend their proboscis in the camera image.
(Inscentinel honeybee cartridge loads into detector)
Once the bees have finished their "shift," they are returned to their hive. The company prides itself on keeping its bees happy and healthy.
Researchers seem to be finding more and more reasons to partner with insects. Roboticist Garnet Hertz created a robot that was actually controlled by a Madagascar hissing cockroach (see Cockroach-Controlled Mobile Robot). Honeybees may someday be used to provide positive ID for people (see Honey Bees Can Recognize You!)
Scientists are also carefully studying insect behavior to get hints on how to better construct cooperative robots (see Bees Key To Cooperative Robots). Researchers have actually built tiny robots to socialize with cockroaches and learn their behaviors (see Insbot Robot Cockroaches Make Friends And Influence... Roaches)
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Dates of sea ice movement and sea ice distance in McMurdo Sound, Antarctica from MODIS and SSMI imagery between 1978-2015 (McMurdo Predator Prey project)
Daly, Kendra L.
Ainley, David G.
MetadataShow full item record
LocationMcMurdo Sound, Antarctica
westlimit: 163; southlimit: -78.5; eastlimit: 166; northlimit: -76
Fast/sea ice movement was quantified from visible-wavelength images from the Moderate-resolution Imaging Spectroradiometer (MODIS) aboard the Aqua and Terra satellites (250 m resolution; processing occurred for 2002/03-2014/15 seasons and Terra satellite date from 2000-2002 were not used) and sea ice concentration derived from the Scanning Multichannel Microwave Radiometer- and Special Sensor Microwave Imager-family passive microwave sensors (SSM/I; 25 km resolution; 1978/79-2014/15). MODIS data were acquired in one of two ways, from either processing of Level 1 swath data into “true color” images using SeaDAS software v. 6.4 (2002-2012), or from the Corrected Reflectance (True Color) layers of the NASA Worldview website (http://worldview.earthdata.nasa.gov/; 2012-2015). Fast ice areas were generated manually from clear-sky images by drawing polygons in GIS software; pack ice was excluded from analysis. The fast ice in MODIS images was sometimes obscured by clouds, so for days with missing imagery we interpolated linearly between valid data. From the MODIS imagery, we also measured the direct linear distance between McMurdo Station and the nearest open water. For SSM/I, daily or bi-daily fractional sea ice cover was extracted from data available at the National Snow and Ice Data Center (NSIDC). SSM/I ice concentration was retrieved from the NSDIC web site and ftp site (http://nsidc.org/data/seaice/). To minimize the biases inherent to the different data processing algorithms and in order to reduce the daily variability introduced by the movement of pack ice, we took the maximum of either the Bootstrap or NASATEAM processed values (Comiso, 2000; Cavalieri and others, 2015), and then used a 5-day median filter to smooth changes in sea ice concentration. To further compensate for short-term oscillations we masked ice concentrations greater than 80% when extracting the dates of changes in sea ice cover. For detecting the timing of sea ice changes, sea ice concentrations below 15% were excluded from our analysis, following the methods of Comiso and Steffen (2001).> To simplify discussion in the following, we use the inclusive term “fast/sea ice” to refer to fast ice as determined by MODIS and sea ice as determined by SSM/I. Fast/sea ice area was plotted over time, and the following sequential pattern of fast/sea ice events is identified: (1) initial fast/sea ice retreat from winter maximum; (2) final rapid fast/sea ice retreat to minimum extent; (3) fast/sea ice cover minimum in the entire McMurdo Sound; and (4) fast/sea ice advance. From the MODIS data, we additionally determined (5) fast ice cover minimum on the west side of the Sound; and (6) fast ice cover minimum on the east side of the Sound. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/674819
Dataset: McMurdo Sound sea ice movement dates
Suggested CitationDataset: Kim, Stacy, Daly, Kendra L., Ainley, David G., Ballard, Grant, "Dates of sea ice movement and sea ice distance in McMurdo Sound, Antarctica from MODIS and SSMI imagery between 1978-2015 (McMurdo Predator Prey project)", 2017-07-07, DOI:10.1575/1912/bco-dmo.708227, https://hdl.handle.net/1912/9081
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Daly, Kendra L.; Kim, Stacy; Ainley, David G.; Ballard, Grant (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2017-05-11)CTD data were collected as part of an ecosystem study in McMurdo Sound, which is located at the southern extent of the Ross Sea in the Southern Ocean. The major goal of this multi-disciplinary project was to assess the ...
Daly, Kendra L.; Ballard, Grant; Kim, Stacy; Ainley, David G. (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: email@example.com, 2017-05-11)Discrete chlorophyll a data were collected as part of an ecosystem study in McMurdo Sound, which is located at the southern extent of the Ross Sea in the Southern Ocean. The major goal of this multi-disciplinary project ...
Icebreaker dates and ice edge distance in McMurdo Sound, Antarctica from austral years 1956/1957 to 2014/2015 (McMurdo Predator Prey project) Kim, Stacy; Daly, Kendra L.; Ainley, David G.; Ballard, Grant (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2017-07-07)The icebreaker channel from the fast ice edge to McMurdo Station has been created each year since 1956, with the location of the channel remaining consistent, by and large, over the entire period. Dates of the icebreaker ... | <urn:uuid:7103251e-4d4b-4553-b2f7-cebf3a4e48df> | 3 | 1,293 | Structured Data | Science & Tech. | 48.463218 | 95,582,929 |
Species Detail - Broom-tip (Chesias rufata) - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
insect - moth
23 April (recorded in 2007)
16 July (recorded in 2005)
National Biodiversity Data Centre, Ireland, Broom-tip (Chesias rufata), accessed 19 July 2018, <https://maps.biodiversityireland.ie/Species/78799> | <urn:uuid:13c6e5fe-5a84-4398-8e5b-a1c7d639e044> | 2.5625 | 144 | Structured Data | Science & Tech. | 46.098 | 95,582,955 |
What a relief! The title of world's largest organism may no longer belong to that creepy giant fungus lying under the ground in northern Michigan. A new, more comely candidate from Utah has been nominated.
It was a shock last April to learn that the dainty mushrooms found on the forest floor in Michigan's Upper Peninsula were but the visible manifestations of a single genetically uniform fungus. It had been extending its tentacles beneath the ground for more than 1,500 years, maybe even 10,000 years, before butting into other underground giants.
That mega-fungus now covers more than 30 acres and weighs 100 tons. And scientists think even bigger fungi may lie undetected elsewhere. Who can blame this page for fretting, at the time, that the fungi might inherit the earth?
Now comes welcome news that an even larger organism has been identified in the Wasatch Mountains of Utah. It's a huge stand of 47,000 quaking aspen trees and stems, growing from a single root system, that covers 106 acres, is genetically uniform and acts as a single organism. When the trees change color in the fall, they do so in unison, like the card section at halftime of a football game.
Surely this is a more fitting champion. It weighs 6,000 tons, 60 times as much as the fungus. Its root system is alleged to be intact, whereas the fungus was acknowledged to have many tiny breaks in its network of tentacles and mushrooms. And it can march over hill and dale, as it has for thousands of years.
Most important, it is beautiful and non-threatening, an inspiration to artists rather than a subject for horror movies.Continue reading the main story
Identifying the largest organisms was once a simple task. You could see them whole, as living entities bounded by skin or an outer covering. The largest were thought to be whales, elephants and giant sequoia trees; the giants of yore were the dinosaurs.
But now, armed with the fancy new tools of genetic analysis, scientists are tempted to define as an organism anything that is genetically uniform and clumped more or less together. Even if no one can see the whole thing, or even be sure it is intact.
Give record-conscious scientists enough time and they will surely find an even bigger organism to crown as champion. Can something be lurking, as yet undetected, beneath the quaking aspens?Continue reading the main story | <urn:uuid:be61e17b-49bc-45a9-a42c-1aba020c8101> | 3 | 498 | Truncated | Science & Tech. | 55.403279 | 95,582,970 |
The Jupiter trojans, commonly called Trojan asteroids or just Trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. They are named for heroes in the ancient Greek tales of the Trojan War. Relative to Jupiter, each Trojan librates around one of Jupiter's two stable Lagrange points: L4, lying 60° ahead of the planet in its orbit, and L5, 60° behind. Jupiter trojans are distributed in two elongated, curved regions around these Lagrangian points with an average semi-major axis of about 5.2 AU.
The first Jupiter trojan discovered, 588 Achilles, was spotted in 1906 by German astronomer Max Wolf. A total of 6,515 Jupiter trojans have been found as of May 2017[update]. By convention they are each named after a mythological figure from the Trojan War, hence the name "Trojan". The total number of Jupiter trojans larger than 1 km in diameter is believed to be about 1 million, approximately equal to the number of asteroids larger than 1 km in the asteroid belt. Like main-belt asteroids, Jupiter trojans form families.
Jupiter trojans are dark bodies with reddish, featureless spectra. No firm evidence of the presence of water, or any other specific compound on their surface has been obtained, but it is thought that they are coated in tholins, organic polymers formed by the Sun's radiation. The Jupiter trojans' densities (as measured by studying binaries or rotational lightcurves) vary from 0.8 to 2.5 g·cm−3. Jupiter trojans are thought to have been captured into their orbits during the early stages of the Solar System's formation or slightly later, during the migration of giant planets.
The term "trojan" has come to be used more generally to refer to other small Solar System bodies with similar relationships to larger bodies: for example, there are both Mars trojans and Neptune trojans, and Saturn has trojan moons.[Note 1] NASA has announced the discovery of an Earth trojan. The term "Trojan asteroid" is normally understood to specifically mean the Jupiter trojans because the first Trojans were discovered near Jupiter's orbit and Jupiter currently has by far the most known Trojans.
In 1772, Italian-born mathematician Joseph-Louis Lagrange, in studying the restricted three-body problem, predicted that a small body sharing an orbit with a planet but lying 60° ahead or behind it will be trapped near these points. The trapped body will librate slowly around the point of equilibrium in a tadpole or horseshoe orbit. These leading and trailing points are called the L4 and L5 Lagrange points.[Note 2] The first asteroids trapped in Lagrange points were observed more than a century after Lagrange's hypothesis. Those associated with Jupiter were the first to be discovered.
E. E. Barnard made the first recorded observation of a trojan, (12126) 1999 RM11 (identified as A904 RD at the time), in 1904, but neither he nor others appreciated its significance at the time. Barnard believed he had seen the recently discovered Saturnian satellite Phoebe, which was only two arc-minutes away in the sky at the time, or possibly an asteroid. The object's identity was not understood until its orbit was calculated in 1999.
The first accepted discovery of a trojan occurred in February 1906, when astronomer Max Wolf of Heidelberg-Königstuhl State Observatory discovered an asteroid at the L4 Lagrangian point of the Sun–Jupiter system, later named 588 Achilles. In 1906–1907 two more Jupiter trojans were found by fellow German astronomer August Kopff (624 Hektor and 617 Patroclus). Hektor, like Achilles, belonged to the L4 swarm ("ahead" of the planet in its orbit), whereas Patroclus was the first asteroid known to reside at the L5 Lagrangian point ("behind" the planet). By 1938, 11 Jupiter trojans had been detected. This number increased to 14 only in 1961. As instruments improved, the rate of discovery grew rapidly: by January 2000, a total of 257 had been discovered; by May 2003, the number had grown to 1,600. As of February 2014[update] there are 3,898 known Jupiter trojans at L4 and 2,049 at L5,
The custom of naming all asteroids in Jupiter's L4 and L5 points after famous heroes of the Trojan War was suggested by Johann Palisa of Vienna, who was the first to accurately calculate their orbits. Asteroids in the L4 group are named after Greek heroes (the "Greek node or camp" or "Achilles group"), and those at the L5 point are named after the heroes of Troy (the "Trojan node or camp"). The asteroids 617 Patroclus and 624 Hektor were named before the Greece/Troy rule was devised, resulting in a Greek spy in the Trojan node and a Trojan spy in the Greek node.
Numbers and massEdit
Estimates of the total number of Jupiter trojans are based on deep surveys of limited areas of the sky. The L4 swarm is believed to hold between 160–240,000 asteroids with diameters larger than 2 km and about 600,000 with diameters larger than 1 km. If the L5 swarm contains a comparable number of objects, there are more than 1 million Jupiter trojans 1 km in size or larger. For the objects brighter than absolute magnitude 9.0 the population is probably complete. These numbers are similar to that of comparable asteroids in the asteroid belt. The total mass of the Jupiter trojans is estimated at 0.0001 of the mass of Earth or one-fifth of the mass of the asteroid belt.
Two more recent studies indicate that the above numbers may overestimate the number of Jupiter trojans by several-fold. This overestimate is caused by (1) the assumption that all Jupiter trojans have a low albedo of about 0.04, whereas small bodies may have an average albedo as high as 0.12; (2) an incorrect assumption about the distribution of Jupiter trojans in the sky. According to the new estimates, the total number of Jupiter trojans with a diameter larger than 2 km is 6,300 ± 1,000 and 3,400 ± 500 in the L4 and L5 swarms, respectively. These numbers would be reduced by a factor of 2 if small Jupiter trojans are more reflective than large ones.
The number of Jupiter trojans observed in the L4 swarm is slightly larger than that observed in L5. Because the brightest Jupiter trojans show little variation in numbers between the two populations, this disparity is probably due to observational bias. Some models indicate that the L4 swarm may be slightly more stable than the L5 swarm.
The largest Jupiter trojan is 624 Hektor, which has an average diameter of 203 ± 3.6 km. There are few large Jupiter trojans in comparison to the overall population. With decreasing size, the number of Jupiter trojans grows very quickly down to 84 km, much more so than in the asteroid belt. A diameter of 84 km corresponds to an absolute magnitude of 9.5, assuming an albedo of 0.04. Within the 4.4–40 km range the Jupiter trojans' size distribution resembles that of the main-belt asteroids. Nothing is known about the masses of the smaller Jupiter trojans. The size distribution suggests that the smaller Trojans are the products of collisions by larger Jupiter trojans.
Jupiter trojans have orbits with radii between 5.05 and 5.35 AU (the mean semi-major axis is 5.2 ± 0.15 AU), and are distributed throughout elongated, curved regions around the two Lagrangian points; each swarm stretches for about 26° along the orbit of Jupiter, amounting to a total distance of about 2.5 AU. The width of the swarms approximately equals two Hill's radii, which in the case of Jupiter amounts to about 0.6 AU. Many of Jupiter trojans have large orbital inclinations relative to Jupiter's orbital plane—up to 40°.
Jupiter trojans do not maintain a fixed separation from Jupiter. They slowly librate around their respective equilibrium points, periodically moving closer to Jupiter or farther from it. Jupiter trojans generally follow paths called tadpole orbits around the Lagrangian points; the average period of their libration is about 150 years. The amplitude of the libration (along the Jovian orbit) varies from 0.6° to 88°, with the average being about 33°. Simulations show that Jupiter trojans can follow even more complicated trajectories when moving from one Lagrangian point to another—these are called horseshoe orbits (currently no Jupiter Trojan with such an orbit is known).
Dynamical families and binariesEdit
Discerning dynamical families within the Jupiter trojan population is more difficult than it is in the asteroid belt, because the Jupiter trojans are locked within a far narrower range of possible positions. This means that clusters tend to overlap and merge with the overall swarm. By 2003 roughly a dozen dynamical families were identified. Jupiter-trojan families are much smaller in size than families in the asteroid belt; the largest identified family, the Menelaus group, consists of only eight members.
In 2001, 617 Patroclus was the first Jupiter trojan to be identified as a binary asteroid. The binary's orbit is extremely close, at 650 km, compared to 35,000 km for the primary's Hill sphere. The largest Jupiter trojan—624 Hektor— is probably a contact binary with a moonlet.
Jupiter trojans are dark bodies of irregular shape. Their geometric albedos generally vary between 3 and 10%. The average value is 0.056 ± 0.003 for the objects larger than 57 km, and 0.121 ± 0.003 (R-band) for those smaller than 25 km. The asteroid 4709 Ennomos has the highest albedo (0.18) of all known Jupiter trojans. Little is known about the masses, chemical composition, rotation or other physical properties of the Jupiter trojans.
The rotational properties of Jupiter trojans are not well known. Analysis of the rotational light curves of 72 Jupiter trojans gave an average rotational period of about 11.2 hours, whereas the average period of the control sample of asteroids in the asteroid belt was 10.6 hours. The distribution of the rotational periods of Jupiter trojans appeared to be well approximated by a Maxwellian function,[Note 3] whereas the distribution for main-belt asteroids was found to be non-Maxwellian, with a deficit of periods in the range 8–10 hours. The Maxwellian distribution of the rotational periods of Jupiter trojans may indicate that they have undergone a stronger collisional evolution compared to the asteroid belt.
In 2008 a team from Calvin College examined the light curves of a debiased sample of ten Jupiter trojans, and found a median spin period of 18.9 hours. This value was significantly higher than that for main-belt asteroids of similar size (11.5 hours). The difference could mean that the Jupiter trojans possess a lower average density, which may imply that they formed in the Kuiper belt (see below).
Spectroscopically, the Jupiter trojans mostly are D-type asteroids, which predominate in the outer regions of the asteroid belt. A small number are classified as P or C-type asteroids. Their spectra are red (meaning that they reflect more light at longer wavelengths) or neutral and featureless. No firm evidence of water, organics or other chemical compounds has been obtained as of 2007[update]. 4709 Ennomos has an albedo slightly higher than the Jupiter-trojan average, which may indicate the presence of water ice. Some other Jupiter Trojans, such as 911 Agamemnon and 617 Patroclus, have shown very weak absorptions at 1.7 and 2.3 μm, which might indicate the presence of organics. The Jupiter trojans' spectra are similar to those of the irregular moons of Jupiter and, to a certain extent, comet nuclei, though Jupiter trojans are spectrally very different from the redder Kuiper belt objects. A Jupiter trojan's spectrum can be matched to a mixture of water ice, a large amount of carbon-rich material (charcoal), and possibly magnesium-rich silicates. The composition of the Jupiter trojan population appears to be markedly uniform, with little or no differentiation between the two swarms.
A team from the Keck Observatory in Hawaii announced in 2006 that it had measured the density of the binary Jupiter trojan 617 Patroclus as being less than that of water ice (0.8 g/cm3), suggesting that the pair, and possibly many other Trojan objects, more closely resemble comets or Kuiper belt objects in composition—water ice with a layer of dust—than they do the main-belt asteroids. Countering this argument, the density of Hektor as determined from its rotational lightcurve (2.480 g/cm3) is significantly higher than that of 617 Patroclus. Such a difference in densities suggests that density may not be a good indicator of asteroid origin.
Origin and evolutionEdit
Two main theories have emerged to explain the formation and evolution of the Jupiter trojans. The first suggests that the Jupiter trojans formed in the same part of the Solar System as Jupiter and entered their orbits while it was forming. The last stage of Jupiter's formation involved runaway growth of its mass through the accretion of large amounts of hydrogen and helium from the protoplanetary disk; during this growth, which lasted for only about 10,000 years, the mass of Jupiter increased by a factor of ten. The planetesimals that had approximately the same orbits as Jupiter were caught by the increased gravity of the planet. The capture mechanism was very efficient—about 50% of all remaining planetesimals were trapped. This hypothesis has two major problems: the number of trapped bodies exceeds the observed population of Jupiter trojans by four orders of magnitude, and the present Jupiter trojan asteroids have larger orbital inclinations than are predicted by the capture model. Simulations of this scenario show that such a mode of formation also would inhibit the creation of similar trojans for Saturn, and this has been borne out by observation: to date no trojans have been found near Saturn.
The second theory proposes that the Jupiter trojans were captured during the migration of the giant planets described in the Nice model. In the Nice model the orbits of the giant planets became unstable 500–600 million years after the Solar System's formation when Jupiter and Saturn crossed their 1:2 mean-motion resonance. Encounters between planets resulted in Uranus and Neptune being scattered outward into the primordial Kuiper belt, disrupting it and throwing millions of objects inward. When Jupiter and Saturn were near their 1:2 resonance the orbits of pre-existing Jupiter trojans became unstable during a secondary resonance with Jupiter and Saturn. This occurred when the period of the trojans' libration about their Lagrangian point had a 3:1 ratio to the period at which the position where Jupiter passes Saturn circulated relative to its perihelion. This process was also reversible allowing a fraction of the numerous objects scattered inward by Uranus and Neptune to enter this region and be captured as Jupiter's and Saturn's orbits separated. These new trojans had a wide range of inclinations, the result of multiple encounters with the giant planets before being captured. This process can also occur later when Jupiter and Saturn cross weaker resonances.
In a revised version of the Nice model Jupiter trojans are captured when Jupiter encounters an ice giant during the instability. In this version of the Nice model one of the ice giants (Uranus, Neptune, or a lost fifth planet) is scattered inward onto a Jupiter-crossing orbit and is scattered outward by Jupiter causing the orbits of Jupiter and Saturn to quickly separate. When Jupiter's semi-major axis jumps during these encounters existing Jupiter trojans can escape and new objects with semi-major axes similar to Jupiter's new semi-major axis are captured. Following its last encounter the ice giant can pass through one of the libration points and perturb their orbits leaving this libration point depleted relative to the other. After the encounters end some of these Jupiter trojans are lost and others captured when Jupiter and Saturn are near weak mean motion resonances such as the 3:7 resonance via the mechanism of the original Nice model.
The long-term future of the Jupiter trojans is open to question, because multiple weak resonances with Jupiter and Saturn cause them to behave chaotically over time. Collisional shattering slowly depletes the Jupiter trojan population as fragments are ejected. Ejected Jupiter trojans could become temporary satellites of Jupiter or Jupiter-family comets. Simulations show that the orbits of up to 17% of Jupiter trojans are unstable over the age of the Solar System. Levison et al. believe that roughly 200 ejected Jupiter trojans greater than 1 km in diameter might be travelling the Solar System, with a few possibly on Earth-crossing orbits. Some of the escaped Jupiter trojans may become Jupiter-family comets as they approach the Sun and their surface ice begins evaporating.
On 4 January 2017 NASA announced that Lucy was selected as one of their next two Discovery Program missions. Lucy is set to explore six Jupiter trojans. It is scheduled for launch in 2021 and will arrive at the L4 Trojan cloud in 2027 after a fly-by of a main-belt asteroid. It will then return to the vicinity of Earth for a gravity assist to take it to Jupiter's L5 Trojan cloud where it will visit 617 Patroclus.
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- Northon, Karen (4 January 2017). "NASA Selects Two Missions to Explore the Early Solar System". NASA. Retrieved 5 January 2017.
- Dreier, Casey; Lakdawalla, Emily (30 September 2015). "NASA announces five Discovery proposals selected for further study". The Planetary Society. Retrieved 1 October 2015.
|Wikimedia Commons has media related to Jupiter Trojans.|
- "Minor Planet Center's List of Trojan Minor Planets".
- Sheppard, Scott. "The Trojan Page".
- Lykawka, P. S.; Horner (2010). "The Capture of Trojan Asteroids by the Giant Planets During Planetary Migration". Monthly Notices of the Royal Astronomical Society. 405 (1383). arXiv: . Bibcode:2010MNRAS.405.1375L. doi:10.1111/j.1365-2966.2010.16538.x.
- NASA's WISE Colors in Unknowns on Jupiter Asteroids (NASA 2012-322 : 15 October 2012)
- on YouTube | <urn:uuid:10327ea9-d87e-4d37-afb3-d18291b81511> | 3.90625 | 6,258 | Knowledge Article | Science & Tech. | 64.620949 | 95,582,977 |
Aim For tree species, adult survival and seedling and sapling
recruitment dynamics are the main processes that determine forest
structure and composition. Thus, studying how these two life stages may
be affected by climate change in the context of other abiotic and biotic
variables is critical to understand future population trends. The aim of
this study was to assess the sustainability of cork oak (Quercus suber)
forests at the core of its distributional range under future climatic
Location Southern Spain.
Methods Using forest inventory data collected at two periods 10 years
apart, we performed a comprehensive analysis to evaluate the role of
different abiotic and biotic factors on adult survival and recruitment
Results We found that both life stages were influenced by climatic
conditions, but in different ways. Adult tree survival was negatively
impacted by warmer spring temperatures, while recruitment was positively
affected by warmer winter temperatures. Our results also revealed the
importance of soil texture as a modulator of winter precipitation
effects on adult survival. With higher winter precipitation, adult
survival increased in sandy soils and decreased in clayish soils.
Therefore, under predicted future climate scenarios of wetter winters
and warmer temperatures, the presence of cork oaks is more likely to
occur in sandy soils vs. clayish soils. Biotic conditions also affected
these life stages. We found a negative effect of heterospecific but not
conspecific trees on both adult survival and seedling recruitment.
Main conclusions Overall, the sustainability of the studied forests will
be highly dependent not only on future climatic trends, but also on
their interaction with other key factors - soil properties in particular
- that modulate the effects of climate on demographic rates.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:03eacfc2-5da8-4e4b-893d-a19048a591c1> | 3 | 386 | Academic Writing | Science & Tech. | 14.184137 | 95,582,990 |
Ants dress the wounds their mates have suffered in battle. Such behaviour is believed to be unique among animals.
The African Matabele ants (Megaponera analis) tend to the wounds of their injured comrades. And they do so rather successfully: Without such attendance, 80 percent of the injured ants die; after receiving "medical" treatment, only 10 percent succumb to their injuries.
Erik T. Frank, Marten Wehrhan and Karl Eduard Linsenmair from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, made this astonishing discovery. Their results have been published in the journal "Proceedings of the Royal Society B". No other insects are known to dress the wounds of their comrades. The JMU biologists even believe that such behaviour is unique in the entire animal kingdom.
Ants go on high-risk raids
Matabele ants have a high risk of getting injured every day: The insects, which are widely distributed in Sub-Saharan Africa, set out to raid termites two to four times a day. Proceeding in long files of 200 to 600 animals, they raid termites at their foraging sites, killing many workers and hauling the prey back to their nest where they are ultimately eaten.
However, the ants meet fierce resistance from the well-armoured termite soldiers that are very adept at using their powerful jaws to fend off the attackers. Injury and mortality among the ants occur during such combats. For example, the ants frequently lose limbs that are bitten off by termite soldiers. When an ant is injured in a fight, it calls its mates for help by excreting a chemical substance which makes them carry their injured comrade back to the nest. Erik T. Frank already described this rescue service in 2017.
But the Würzburg biologists dug deeper: What happens once the injured ants are back in the nest? The ants treat the open wounds of their injured fellows by "licking" them intensively, often for several minutes. "We suppose that they do this to clean the wounds and maybe even apply antimicrobial substances with their saliva to reduce the risk of bacterial or fungal infection," Frank explains.
Severely injured ants are left behind on the battlefield
The team from the JMU Biocentre uncovered more exciting details about the emergency rescue service of the Matabele ants. Badly injured ants missing five of their six legs, for example, get no help on the battleground. The decision who is saved and who is left behind is made not by the rescuers but by the injured ants themselves.
Slightly injured ants keep still and even pull in their remaining limbs to facilitate transport. Their badly injured counterparts in contrast struggle and lash out wildly. "They simply don't cooperate with the helpers and are left behind as a result," Frank says. So the hopeless cases make sure that no energy is invested in rescuing them.
Slightly injured ants keep still
When Matabele ants are only slightly injured, they move much more slowly than normal once potential helpers are near. This behaviour probably increases their chances of being noticed by the other ants rushing back to the nest in a column. Or it may be that ants can localize the "save-me-substance" more easily in resting ants.
More questions arise
The new insights give rise to new questions: How do ants recognize where exactly a mate was injured? How do they know when to stop dressing the wounds? Is treatment purely preventive or also therapeutic, after an infection has occurred?
Erik T. Frank will continue to tackle these and other questions at the University of Lausanne in Switzerland where he has been doing postdoc research since February 2018. He recently completed his doctoral thesis at JMU.
Frank ET, Wehrhahn M, Linsenmair KE. 2018 Wound treatment and selective help in a termite-hunting ant. Proc. R. Soc. B 20172457. http://dx.doi.org/10.1098/rspb.2017.2457
Dr. Erik T. Frank, University of Lausanne, Department of Ecology and Evolution, T +41 21 692 4176, email@example.com
Video on Youtube showing medical care for a wounded ant, copyright by Erik T. Frank
Robert Emmerich | idw - Informationsdienst Wissenschaft
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
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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23.07.2018 | Science Education | <urn:uuid:5e3d8844-d292-4331-adcc-cbfef41d7ab1> | 3.6875 | 1,503 | Content Listing | Science & Tech. | 47.133674 | 95,583,004 |
The copypartialdictionary( function partially copies a dictionary (see Data Dictionaries).
This function has two parameters:
dictionary – is the name of the field or variable that contains the original dictionary (must contain binary data).
key – is the name of the key to copy. If you need to copy more than one key/value pair, more than one key parameter can be used.
The copypartialdictionary( function takes one or more key names and copies the associated key/value pairs from the original dictionary into a new one. For example, suppose you created a dictionary and stored it in variable named contact.
fileglobal contact,mailto contact=initializedictionary("First","John","Last","Wilson", "Address","3987 Olive","City","Tustin","State","CA","Zip","92841", "Phone","562-309-5923","Email","email@example.com")
Later, you could use the copypartialdictionary( function to create a second dictionary, called mailto, that contains just the address information (without the phone number, e-mail, or any other entries that may have been added to the original dictionary):
|10.0||Updated||Carried over from Panorama 6.0, but now available as a function. Also, this operation no longer corrupts the dictionary if the same key is listed more than once.| | <urn:uuid:86954ebe-18a1-4ae9-b1fe-26320194fedb> | 2.65625 | 293 | Documentation | Software Dev. | 32.498525 | 95,583,012 |
- Paper report
- Open Access
Arabidopsis chromosome 4 sequence
- Todd Richmond
© BioMed Central Ltd 2000
Received: 8 February 2000
Published: 27 April 2000
Members of the Arabidopsis Genome Initiative, including the European Union Arabidopsis Genome Sequencing Consortium and The Cold Spring Harbor, Washington University in St Louis and PE Biosystems Arabidopsis Sequencing Consortium, have completed sequencing one of the first two plant chromosomes.
Significance and context
Arabidopsis thaliana is the model organism of choice for modern plant biologists. Its small genome, the excellent genetic and physical maps of the genome and the lack of large amounts of repetitive DNA made it the first choice for plant genome sequencing. In 1996, a multinational organization, the Arabidopsis Genome Initiative (AGI), was formed to coordinate the worldwide effort to sequence the first higher plant. Made up of labs from the United States, Europe and Japan, AGI set a goal for the completion of the Arabidopsis genome by 2004. The members divided up the five chromosomes between them and began sequencing. Advances in sequencing and computing technology have pushed forward their initial timetable, however, and two papers report the completion of the first two plant chromosomes. Mayer et al. report the sequencing of chromosome 4, which represents about 17% of the genome. In a companion paper in the same issue of Nature, Lin et al. report the sequencing of chromosome 2, which represents approximately 15% of the Arabidopsis genome. These sequences are two of the largest pieces of DNA sequence ever assembled and together represent almost a third of the Arabidopsis genome. The complete sequences of chromosomes 2 and 4 offer unique insights into large-scale genomic organization, plant heterochromatic DNA, non-coding regions, gene duplication events, and gene family organization.
The paper summarizes years of work by hundreds (if not thousands) of people in dozens of labs spread over three continents. The key features of chromosome 4 are as follows. The long arm of chromosome 4 is 14.5 Mb, the short arm is 3.0 Mb (plus nearly 3.5 Mb of ribosomal DNA repeats). Nearly 50% of the sequence encodes for protein, for a total of 3,744 predicted proteins. Each gene is about 4.6 kb in length, containing an average of 5.2 exons. The actual or potential cellular function for approximately 60% of the genes can be predicted on the basis of similarity to other characterized proteins. Only 33% of the predicted genes are represented among the available 45,000 Arabidopsis expressed sequence tags (ESTs). Of these, 6% of the genes match 75% of the ESTs. Note that it is not clear if the authors are referring at this point only to the chromosome 4 sequence or to all Arabidopsissequence available; it is clearly important to sequence normalized EST libraries in order to maximize the amount of non-redundant sequence gathered. Almost 8% of the predicted genes have no ESTs and no similarity to other proteins; these may represent spurious gene predictions or plant-specific genes expressed at low levels.
The authors give some statistics on various motifs and structural topologies found in the predicted proteins. They also attempt to classify the proteins into major functional categories (such as metabolism and transcription). The only major surprise is the large number of genes involved in disease and defense responses. This is largely due to several large clusters of leucine-rich repeat genes, including one family of 15 contiguous genes. A surprisingly large number of genes are arranged in tandem copies. Of genes with products that have significant similarity to other proteins in Arabidopsis, 12% are arrayed in tandem clusters, ranging from pairs of genes to the 15 leucine-rich repeat genes. This hints at the underlying mechanism of how plants generate sequence diversity and evolve new metabolic and regulatory functions. The final section covers the centromeric heterochromatin region of chromosome 4, a roughly 4 Mb region. The majority of repetitive elements in the Arabidopsis genome are found in the centromeric regions of the chromosomes, and include dispersed repeats, representatives of most of the transposons found in other plant species, long terminal repeat (LTR) and non-LTR retroelements, and Athila retroelements. Although every description of Arabidopsis thaliana as a model organism cites the fact that it has very low amounts of repetitive DNA, this paper and the accompanying description of chromosome 2 offer a highly detailed characterization of its repetitive elements. These results are, for the most part, consistent with previous findings and estimates.
Information on Arabidopsis and its genome sequence is available from The Arabidopsis Information Resource (TAIR), MIPS Arabidopsis thaliana database (MATDB), Kazusa Arabidopsis data opening site (KAOS), The Institute for Genomic Research's Arabidopsis thaliana annotation database. Sequence-based, genetic and physical maps of the Arabidopsis genome are available from the Cold Spring Harbor Laboratory.
This paper, and its companion, just begin to scratch the surface of the overwhelming amount of information contained in the sequence of two plant chromosomes. Comparing this paper with the chromosome 2 paper, the interest of the primary authors is clear. While Lin et al. emphasize chromosome structure and organization, Mayer et al. appear more interested in protein-coding sequences and the functional classification of the predicted proteins. Once the entire Arabidopsis genome (ecotype Columbia) is completed and the complete sequence of the Landsberg ecotype is released to researchers, a flood of papers is likely to overwhelm the plant community. In a sense, this is somewhat frustrating, as we will be forced to rely on others to analyze and summarize the important information, even though not all researchers agree on what data is important, how to present it or how to interpret it. As a case in point, both the chromosome 2 and the chromosome 4 papers make reference to the large duplication event shared by the two chromosomes. Lin et al. report that this duplication is 4.6 Mb long, with several translocations or inversions, encompassing a total of 1,100 genes. Mayer et al. report that the two chromosomes share four blocks of conserved sequence, two of which are inverted, totaling 2.5 Mb in length. Which interpretation is correct? Another source of frustration is the lack of consistency in reporting results. While Lin et al., reporting on chromosome 2, place more emphasis on the overall chromosome structure and the organization and distribution of various elements, Mayer et al. place more emphasis on the genes, predicted functions and structural components. It makes this reporter wish that the two teams had coordinated with one another, divided up the various areas of interest and done a complete report on those areas for both chromosomes. For now, we must be satisfied with a partial analysis. The upcoming completion of the Arabidopsis genome will truly be a landmark. For the first time, we will have the complete genetic blueprint for a flowering plant. The initial data, especially from Lin et al., suggest that all plants have a common set of genes for many functions. It is already clear that many of the genes found in other plants are present in Arabidopsis, even when comparing across the monocot/dicot and angiosperm/gymnosperm divisions. But until another plant, such as rice, is completely sequenced, it will be difficult to evaluate the size of that set of common genes. With the Arabidopsis genome expected to be finished by the end of the year, we can then move on to the more complex area of functional genomics and begin to elucidate the function of the estimated 25,000 proteins that make up a flowering plant. | <urn:uuid:6617bf66-1146-4aec-8b86-bf24f74623c3> | 2.59375 | 1,582 | Academic Writing | Science & Tech. | 31.013835 | 95,583,013 |
Chapter 22. CDL Concepts
Table of Contents
22.1. About this chapter
This chapter serves as a brief introduction to the concepts involved in eCos (Embedded Configurable Operating System). It describes the configuration architecture and the underlying technology to a level required for the embedded systems developer to configure eCos. It does not describe in detail aspects such as how to write reusable components for eCos: this information is given in the Component Writer’s Guide.
Software solutions for the embedded space place particularly stringent demands on the developer, typically represented as requirements for small memory footprint, high performance and robustness. These demands are addressed in eCos by providing the ability to perform compile-time specialization: the developer can tailor the operating system to suit the needs of the application. In order to make this process manageable, eCos is built in the context of a Configuration Infrastructure: a set of tools including a Configuration Tool and a formal description of the process of configuration by means of a Component Definition Language.
eCos is tailored at source level (that is, before compilation or assembly) in order to create an eCos configuration. In concrete terms, an eCos configuration takes the form of a configuration save file (with extension .ecc) and set of files used to build user applications (including, when built, a library file against which the application is linked).
22.2. Component Repository
eCos is shipped in source in the form of a component repository - a directory hierarchy that contains the sources and other files which are used to build a configuration. The component repository can be added to by, for example, downloading from the net.
22.3. Component Definition Language
Part of the component repository is a set of files containing a definition of its structure. The form used for this purpose is the Component Definition Language (CDL). CDL defines the relationships between components and other information used by tools such as the eCos Configuration Tool. CDL is generally formulated by the writers of components: it is not necessary to write or understand CDL in order for the embedded systems developer to construct an eCos configuration.
The building blocks of an eCos configuration are called packages. Packages are the units of software distribution. A set of core packages (such as kernel, C library and math library) additional packages provided by eCosCentric (such as C++ library and USB device support): additional third-party packages will be available in future.
A package may exist in one of a number of versions. The default version is the current version. Only one version of a given package may be present in the component repository at any given time.
Packages are organized in a tree hierarchy. Each package is either at the top-level or is the child of another package.
The eCos Package Administration Tool can be used to add or remove packages from the component repository. The eCos Configuration Tool can be used to include or exclude packages from the configuration being built.
22.5. Configuration Items
Configuration items are the
individual entities that form a configuration. Each item
corresponds to the setting of a C pre-processor macro (for
The code of eCos itself is written to test such pre-processor
macros so as to tailor the code. User code can do
Configuration items come in the following flavors:
None: such entities serve only as place holders in the hierarchy, allowing other entities to be grouped more easily.
Boolean entities are the most common flavor; they correspond to units of functionality that can be either enabled or disabled. If the entity is enabled then there will be a #define; code will check the setting using, for example, #ifdef
Data entities encapsulate some arbitrary data. Other properties such as a set or range of legal values can be used to constrain the actual values, for example to an integer or floating point value within a certain range.
Booldata entities combine the attributes of Boolean and Data: they can be enabled or disabled and, if enabled, will hold a data value.
Like packages, configuration items exist in a tree-based hierarchy: each configuration item has a parent which may be another configuration item or a package. Under some conditions (such as when packages are added or removed from a configuration), items may be “re-parented” such that their position in the tree changes.
Expressions are relationships between CDL items. There are three types of expression in CDL:
Table 22.1. CDL Expressions
|Expression Type||Result||Common Use (see Table 22.2, “Configuration properties”)|
|Ordinary||A single value||legal_values property|
|List||A range of values (for example “1 to 10”)||legal_values property|
|Goal||True or False||requires and active_if properties|
Each configuration item has a set of properties. The following table describes the most commonly used:
Table 22.2. Configuration properties
|Flavor||The “type” of the item, as described above|
|Enabled||Whether the item is enabled|
|Current_value||The current value of the item|
|Default_value||An ordinary expression defining the default value of the item|
|Legal_values||A list expression defining the values the item may hold (for example, 1 to10)|
|Active_if||A goal expression denoting the requirement for this item to be active (see below: Inactive Items)|
|Requires||A goal expression denoting requirements this item places on others (see below: Conflicts)|
|Calculated||Whether the item as non-modifiable|
|Macro||The corresponding C pre-processor macro|
|File||The C header file in which the macro is defined|
|URL||The URL of a documentation page describing the item|
|Hardware||Indicates that a particular package is related to specific hardware|
A complete description of properties is contained in the Component Writer’s Guide.
22.5.3. Inactive Items
Descendants of an item that is disabled are inactive: their values may not be changed. Items may also become inactive if an active_if expression is used to make the item dependent on an expression involving other items.
Not all settings of configuration items will lead to a coherent configuration; for example, the use of a timeout facility might require the existence of timer support, so if the one is required the other cannot be removed. Coherence is policed by means of consistency rules (in particular, the goal expressions that appear as CDL items requires and active_if attributes [see above]). A violation of consistency rules creates a conflict, which must be resolved in order to ensure a consistent configuration. Conflict resolution can be performed manually or with the assistance of the eCos tools. Conflicts come in the following flavors:
An unresolved conflict means that there is a reference to an entity that is not yet in the current configuration
An illegal value conflict is caused when a configuration item is set to a value that is not permitted (that is, a legal_values goal expression is failing)
An evaluation exception conflict is caused when the evaluation of an expression would fail (for example, because of a division by zero)
An unsatisfied goal conflict is caused by a failing requires goal expression
A bad data conflict arises only rarely, and corresponds to badly constructed CDL. Such a conflict can only be resolved by reference to the CDL writer.
A template is a saved configuration - that is, a set of packages and configuration item settings. Templates are provided with eCos to allow you to get started quickly by instantiating (copying) a saved configuration corresponding to one of a number of common scenarios; for example, a basic eCos configuration template is supplied that contains the infrastructure, kernel, C and math libraries, plus their support packages.
|2018-07-06||Open Publication License| | <urn:uuid:d7ca5b01-d221-4a05-8f7d-cc4b0dfd9cb4> | 2.734375 | 1,646 | Documentation | Software Dev. | 27.604511 | 95,583,015 |
This paper reports on field studies and model development aimed at understanding coliform fate and transport in the Quabbin Reservoir, an oligotrophic drinking water supply reservoir. An investigation of reservoir currents suggested the importance of wind driven phenomena, and that both lateral and vertical circulation patterns exist. In-situ experiments of coliform decay suggested dependence on light intensity and yielded an appropriate decay coefficient to be used in CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model. Modeling confirmed the sensitivity of reservoir outlet concentration to vertical variability within the reservoir, meteorological conditions, and location of coliform source.
Coliform transport in a pristine reservoir: modeling and field studies
Elisa Garvey, John E. Tobiason, Michael Hayes, Evelyn Wolfram, David A. Reckhow, James W. Male; Coliform transport in a pristine reservoir: modeling and field studies. Water Sci Technol 1 January 1998; 37 (2): 137–144. doi: https://doi.org/10.2166/wst.1998.0124
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Renshaw cells are inhibitory interneurons which are located in the gray matter of the spinal cord. They are associated in two ways with an alpha motor neuron.
Renshaw cells receive an excitatory collateral from the alpha neuron's axon, as they monitor how vigorously that neuron is firing. They also send an inhibitory axon to synapse with the cell body of the initial alpha neuron and/or an alpha motor neuron of the same motor pool. Thus, Renshaw cell inhibition represents a negative feedback mechanism. A Renshaw cell may be supplied by more than one alpha motor neuron collateral and it may synapse on multiple motor neurons. | <urn:uuid:0ef6e96a-dc51-4f3b-b8df-710655c621dc> | 2.765625 | 136 | Knowledge Article | Science & Tech. | 36.137905 | 95,583,062 |
Butterfly: Wingspan: 1 3/4 - 2 5/8 inches (4.45-6.6 cm. Upperside has uneven brown, yellow, and orange pattern. Forewing has a black patch, a small white spot in the orange field below the patch, and a white bar at the leading edge. Underside of hindwing has two large eyespots. Winter form is smaller and paler; summer form larger with bright coloring.
ID Tip: Two large eyespots on under surface of hindwing.
Egg: Small pale green, barrel-shaped eggs are laid singly on host plant leaves.
Caterpillar: Variable in color: Greenish yellow with narrow black rings; black with creamy rings. Dark, branched spines are red at the base. There is a pair of white spots on each segment. Caterpillars are solitary feeders and construct nests from various parts of their host plant. Tiny larvae use leaf hairs to construct tiny nests; larger caterpillars arrange leaves, flower heads, and detritus to form tight shelters. Several structures are typically built during the caterpillar's development.
Chrysalis: Color varies: gray or various degrees of gold and brown. A wide dark line extends from head to tail. There are rows of triangular projections tipped with black dots as well as black dots on other parts of the chrysalis. Often formed within a leaf-enfolded nest.
American Ladies are yearlong residents in Alabama and probably occupy every county in Alabama.
American Ladies are closely related to and strongly resemble Painted Ladies, but they are more cold tolerant. Painted Ladies must recolonize the state every year, while American Ladies are encountered early spring through late fall and occasionally even in winter. They are habitat generalists, living almost anywhere as long as their host plants are present.
Male American Ladies sip moisture and nutrients from damp soil. Females are often observed flying low in search of their ground-hugging host plants. Both sexes avidly nectar at a variety of plants and are often among those early spring butterflies that nectar from wild plum blossoms.
A dot on the county map indicates that there is at least one documented record of the species within that county. In some cases, a species may be common throughout the county, in others it may be found in only a specific habitat.
The sightings bar graphs depict the timing of flight(s) within each of three geographic regions. Place your cursor on a bar within the graph to see the number of individuals recorded during that period.
The abundance calendar displays the total number of individuals recorded within each week of the month. Both the graphs and the calendar are on based data collection that began in 2000.
The records analyzed here are only a beginning. As more data is collected, these maps and graphs will paint a more accurate picture of distribution and abundance in Alabama. Submit your sightings to firstname.lastname@example.org.
Sightings in the following counties: Autauga, Baldwin, Barbour, Bibb, Blount, Bullock, Calhoun, Chambers , Chilton, Choctaw, Clay, Cleburne, Colbert, Coosa, Covington, Dale, Dallas, DeKalb, Elmore, Escambia, Etowah, Franklin, Geneva, Greene, Hale, Houston, Jackson, Jefferson, Lauderdale, Lawrence, Lee, Macon, Madison, Madison , Marion, Marshall, Mobile, Monroe, Perry, Pickens, Pike, Randolph, Shelby, St. Clair, Sumter, Talladega, Tallapoosa, Tuscaloosa, Walker, Winston
View county names by moving the mouse over a county or view a map with county names
A wide variety of open areas, including gardens
Plants known as “everlastings” including pussytoes (Antennaria spp.) and cudweeds (Gamachaeta spp.) are reported throughout the range.
These hosts plants have been verified in Alabama: Plantain Leaf Pussytoes (Antennaria plantaginifolia), Cudweed spp. (Gamochaeta spp.)
For more information about the documented host plants and/or nectar plants, please visit the Alabama Plant Atlas using the following links:
Plant pussytoes to attract American Ladies. This garden-worthy groundcover will grow in sun or shade, and tolerates dry conditions. It will form a carpet of soft gray-green foliage, and throughout much of Alabama, American Ladies are almost sure to find it.
Consider letting your lawn areas be "natural." Cudweed is often a component in these lawns and can provide caterpillar food for American Lady caterpillars.
Include a variety of nectar-rich flowers such as Black Eyed Susans (Rudbeckia spp.), Butterfly Milkweed (Asclepias tuberosa), Joe Pye Weeds (Eutrochium spp.), asters (Symphyotrichum spp.), ironweeds (Vernonia spp.), Purple Coneflower (Echinacea purpurea), and Blue Mistflower/Wild Ageratum (Conoclinium coelestinum) in your landscape to provide food for butterflies like American Ladies throughout the growing season. | <urn:uuid:9d17ffd5-6ea2-459d-ab40-7aec9a8a0a38> | 2.921875 | 1,099 | Knowledge Article | Science & Tech. | 41.975383 | 95,583,068 |
The estuarine waters of the St. Johns River in Jacksonville, FL provide critical habitat for Atlantic bottlenose dolphins (Tursiops truncatus). However, due to the urban location of this community the risk of anthropogenic (human) disturbance is high. In September 2010, an Unusual Mortality Event (UME) was declared for Jacksonville’s estuarine dolphins in response to an unprecedented number of dolphin strandings/deaths in the St. Johns River. Unfortunately, the investigation into potential causes for these strandings was inconclusive due to limited knowledge of this community at that time. Our UNF Dolphin Research Program, initiated in March 2011, has strived to fill this knowledge gap through a systematic study of the behavioral ecology of the dolphins that inhabit the St. Johns River in Jacksonville, Florida.
Through weekly vessel-based photo-identification and behavioral surveys, our research team has identified over 520 individual dolphins in the St. Johns River (SJR). Dolphins are consistently sighted throughout our survey route, Mayport inlet to downtown Jacksonville, approximately 40 km up-river. Contrary to previous reports from the 1990’s, the SJR provides significant year-round habitat for a resident community of dolphins. In the past seven years, our team has developed a long-term photographic catalog and sighting history database of individual dolphins that we can use to address numerous research questions. For example, these data have enabled us to 1) identify critical habitat areas used for resting, mating/calving and foraging, 2) determine site fidelity and seasonal movement patterns, and 3) calculate life history parameters, particularly those related to reproductive success (e.g., calving rates, inter-birth intervals, and calf survival), as these are important indicators of the health and sustainability of the population. We routinely provide summaries of our findings directly to management agencies as these data are critical for assessing the potential impact of anthropogenic disturbance on this dolphin community.
As founding members of the Northeast Florida Dolphin Research Consortium, we are also working collaboratively with eight other research groups to determine the population abundance of estuarine bottlenose dolphins throughout the northeast Florida region (Fernandina Beach to Ponce Inlet). To do so, we conduct synoptic abundance surveys each summer and winter. Participation in this large-scale effort will clarify the larger ranging patterns of the St. Johns River dolphins, and thereby their cumulative exposure to anthropogenic disturbance.
In addition to the management oriented population monitoring work described above, another area of focus for our lab is social structure (association patterns) and complexity (e.g., male mating strategies). Our research has documented that some male SJR dolphins exhibit an exceptionally rare mating strategy, multi-level alliances, in which pairs of males cooperate with one another to obtain greater access to females. We are currently working to better understand the selection pressures that might have led to increased social complexity in this dolphin community. In the near future, we intend to expand the behavioral component of our research by investigating maternal care strategies and calf development.
Our research team has a strong track record of presenting research findings at regional, national and international scientific conferences. A list of selected presentations (2015-2017) is provided below.
Note: All research is conducted under authorization from NOAA Fisheries (GA LOC 14157 and Permit 18182) and UNF IACUC.
Photo-identification work with local dolphins. | <urn:uuid:b57bac08-49d8-4418-8de9-aaacdedb82dd> | 3.234375 | 697 | Academic Writing | Science & Tech. | 20.842519 | 95,583,085 |
At DESY’s X-ray source PETRA III, scientists have followed the growth of tiny wires of gallium arsenide live. Their observations reveal exact details of the growth process responsible for the evolving shape and crystal structure of the crystalline nanowires. The findings also provide new approaches to tailoring nanowires with desired properties for specific applications. The scientists, headed by Philipp Schroth of the University of Siegen and the Karlsruhe Institute of Technology (KIT), present their findings in the journal Nano Letters. The semiconductor gallium arsenide (GaAs) is widely used, for instance in infrared remote controls, the high-frequency components of mobile phones and for converting electrical signals into light for fibre optical transmission, as well as in solar panels for deployment in spacecraft.
To fabricate the wires, the scientists employed a procedure known as the self-catalysed Vapour-Liquid-Solid (VLS) method, in which tiny droplets of liquid gallium are first deposited on a silicon crystal at a temperature of around 600 degrees Celsius. Beams of gallium atoms and arsenic molecules are then directed at the wafer, where they are adsorpted and dissolve in the gallium droplets. After some time, the crystalline nanowires begin to form below the droplets, whereby the droplets are gradually pushed upwards. In this process, the gallium droplets act as catalysts for the longitudinal growth of the wires. “Although this process is already quite well established, it has not been possible until now to specifically control the crystal structure of the nanowires produced by it. To achieve this, we first need to understand the details of how the wires grow,” emphasises co-author Ludwig Feigl from KIT.
To observe the growth as it takes place, Schroth’s group installed a mobile experimental chamber, specially developed by KIT for X-ray experiments and partially funded by the Federal Ministry of Education and Research (BMBF), in the brilliant X-ray beam of DESY’s synchrotron radiation source PETRA III at experimental station P09. At one-minute intervals the scientists took X-ray pictures, which allowed both the internal structure and the diameter of the growing nanowires to be simultaneously determined. In addition, they measured the fully-grown nanowires using the scanning electron microscope at the DESY NanoLab. “To ensure the success of such complex measurements, an extensive period of growth characterisation and optimisation at the UHV Analysis Lab at KIT was a prerequisite,” explains co-author Seyed Mohammad Mostafavi Kashani from University of Siegen.
Over a period of about four hours, the wires grew to a length of some 4000 nanometres. One nanometre (nm) is one millionth of a millimetre. However, not only did the wires become longer during this time, but also thicker: their diameter increased from an initial 20 nm to up to 140 nm at the top of the wire, still making them around 500 times thinner than a human hair.
“One rather exciting feature is that the images taken under the electron microscope show the nanowires to have a slightly different shape,” says co-author Thomas Keller from DESY NanoLab. Although the wires were thicker at the top than at the bottom, just as indicated by the X-ray data, the diameter measured under the electron microscope was larger in the lower region of the wire than what was observed using X-rays.
“We found out that the growth of the nanowires is not only due to the VLS mechanism but that a second component also contributes, which we were able to observe and quantify for the first time in this experiment. This additional sidewall growth lets the wires gain width,” explains Schroth. Independently of VLS growth, the vapour deposited material also attaches itself directly to the side walls, particularly in the lower region of the nanowire. This additional contribution can be determined by comparing the X-ray measurements taken early on during the growth of the wire, with the electron microscope measurement after growth has ended.
Furthermore, the gallium droplets are constantly becoming larger as further gallium is added in the course of the growth process. Using growth models, the scientists were able to deduce the shape of the droplets, which had also been affected by the increasing droplet size. The effect of this is far-reaching: “As the droplet changes in size, the angle of contact between the droplet and the surface of the wires also changes. Under certain circumstances, the wire then suddenly continues growing with a different crystal structure,” says Feigl. Whereas the fine nanowires initially crystallise in a hexagonal, so-called wurtzite structure, this behaviour changes after some time and the wires adopt a cubic zinc blende structure as they continue to grow. This change is important when it comes to applications, since the structure and shape of the nanowires have important consequences for the properties of the resulting material.
Such detailed findings not only lead to a better understanding of the growth process; they also provide approaches for customising future nanowires to have special properties for specific applications – for example to improve the efficiency of a solar cell or a laser.
This research is also part of the strategic collaboration between the two Helmholtz Centres KIT and DESY within the framework of the Helmholtz programme “From Matter to Materials and Life” (MML).
DESY is one of the world’s leading particle accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – ranging from the interaction of tiny elementary particles to the behaviour of innovative nanomaterials and the vital processes that take place between biomolecules to the great mysteries of the universe. The accelerators and detectors that DESY develops and builds at its locations in Hamburg and Zeuthen are unique research tools. DESY is a member of the Helmholtz Association, and receives its funding from the German Federal Ministry of Education and Research (BMBF) (90 per cent) and the German federal states of Hamburg and Brandenburg (10 per cent). | <urn:uuid:e61f20ab-a4e3-4a3a-b161-2a84be6408af> | 3.328125 | 1,294 | News Article | Science & Tech. | 25.404688 | 95,583,086 |
Lush underwater forests in mesophotic reefs of the Gulf of Guinea
KeywordsSurface Layer Dense Distribution Fishing Cool Water Warm Water
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
The Gulf of Guinea, in West Africa, harbors some of the least known tropical reefs in the world. Shallow reefs in this region are mainly rocky and have limited scleractinian growth (Laborel 1974). Circulation patterns restrict warm waters to the surface layer and cooler waters to below 20–30 m depth (Laborel 1974). Reefs lying below these depths, in cool water, have not yet been described. Here, we report a mesophotic reef ecosystem dominated by black corals between 30 and 50 m depth off Lagoa Azul, northwest São Tomé Island (0°24′33″N, 6°36′30″E). At 28–30 m depth, temperature declined abruptly, from 29 °C to 22 °C, and the reef shifted from rocky/biogenic patches (scleractinians Montastrea cavernosa, Siderastrea sp., and coralline algae) among sand to high-canopy black corals on rocky substrate. The black corals were mainly the greenish Antipathes gracilis (Fig. 1a) and a white-colored species, possibly Tanacetipathes spinescens (Fig. 1b; Wirtz and d’Acoz 2008), and also included the whip coral Stichopathes lutkeni. Colonies were largely ramified and formed canopies reaching 1–2 m height (Fig. 1c). The dense distribution of colonies between 35 and 50 m depth resembled a large underwater forest, intensified by the green coloration of A. gracilis (Fig. 1d). Canopies gave shelter to schools of fish, especially Paranthias furcifer, Clepticus africanus, and Lutjanus fulgens (Fig. 1e). In situ observation of canoes fishing and abandoned gear (Fig. 1f), as well as fishermen interviews, revealed that this area is heavily fished with occasional blasting. This reef may also be affected by the development of a deepwater port ~7 km from the area. The fragile structure of black corals in this hitherto undescribed and potentially unique ecosystem should be considered in the management and conservation of São Tomé’s reefs.
We thank Rufford Foundation and Fundação Calouste Gulbenkian for providing funds.
- Laborel J (1974) West African reef corals: an hypothesis on their origin. In: Proceedings of the 2nd international coral reef symposium, vol 1, pp 425–443Google Scholar
- Wirtz P, d’Acoz CU (2008) Crustaceans associated with Cnidaria, Bivalvia, Echinoidea and Pisces at São Tomé and Príncipe islands. Arquipél Life Mar Sci 25:63–69Google Scholar
© Springer-Verlag Berlin Heidelberg 2016 | <urn:uuid:8273bc38-6ac7-436f-a144-3a85e4b1d149> | 3.28125 | 669 | Academic Writing | Science & Tech. | 49.150206 | 95,583,090 |
Our aim is to investigate past climate and environmental changes in Greenland using mineral and sedimentary deposits founds in caves. In doing so, we are constructing the first cave-based climate records for Greenland and the wider High Arctic, as well as improving our understanding of climate change during times and in places that are beyond the limit of the ice cores.
Why is this important?
The Arctic region is expected to experience some of the greatest climate and environmental changes in the next centuries as a result of climate change, and the consequences of these changes will be experienced worldwide, for instance through rising sea-levels or changes to Northern Hemisphere weather systems. Improving understanding of how the Arctic will develop in a warmer world is therefore of paramount importance, and one way to achieve this is to look at periods of warmer climate in the recent geological past.
Understanding how the climate has changed in the past can be achieved by investigating a number of different geological archives, as well as by running sophisticated climate models on computers. In Greenland, deep ice cores drilled from the interior of the ice sheet have provided extremely high-quality data that has revolutionised our understanding of past climate change, both in the Arctic and further afield, particularly during our present warm climate period (known as the Holocene interglacial), as well as during the last ice age (glacial). Through our work in the caves of Greenland, our aim is to address some knowledge gaps, for instance warm climate periods further back in time than the ice cores can reach, as well as in places where the ice sheet is not present, such as arid coastal regions. To achieve this, we undertook our first expedition in August, 2015, to caves at 80°N in Northeast Greenland, and in the summer of 2018, we will aim to visit new sites at 70°N in East Greenland.
Cave-based climate records
Calcite cave deposits such as stalagmites and stalactites are collectively known as speleothems, and these form from drip waters that have percolated from the surface, through soil and limestone, and into a cave. Since the drip waters were once connected with the atmosphere and soil above the cave, they contain valuable information related to temperature, moisture, and vegetation processes, which become locked layer upon layer within the cave deposit.
Palaeoclimatologists (people who study past climate change) are able to analyse the chemical signature that is contained within a speleothem, and from this they can construct a record of how the climate and environment has changed during the time that the speleothem was growing. The chemical element that is most commonly analysed for climate interpretation is oxygen, whilst the method most commonly used to find out when the speleothem was growing is called uranium-thorium dating.
Oxygen records in speleothems
In order to understand how the climate has changed in the past, we use the element oxygen. The nucleus of an oxygen atom contains 8 protons and either 8,9 or 10 neutrons, which, when added together, gives a mass of either 16,17, or 18. These oxygen atoms with different masses are forms of isotopes (but they can be found in other elements too).
In palaeoclimatology studies, we are interested in the relationship between oxygen-16 and oxygen-18 (there is so little oxygen-17 in the world that we don’t worry about this one). Because oxygen-18 is heavier than oxygen-16, it requires more energy to evaporate water (H20) that contains an oxygen-18 atom than it does one that contains an oxygen-16 atom. During times of warmer climate, precipitation therefore contains a higher proportion of oxygen-18 relative to oxygen-16, and since speleothems ultimately form from rainwater, the isotopic signature of the rainfall gets locked within the calcite layers of the speleothem.
For analysis of oxygen isotopes, the Innsbruck Quaternary Research Group typically takes between 4-10 samples per millimetre, enabling the greatest chance of capturing rapid climate change events. Understanding how fast the climate is capable of changing from one state to another is currently one of the key questions that climate-change scientists are working to answer.
For a really fun explanation that uses cats to show how oxygen isotopes are used in palaeoclimate studies, see here.
Uranium-thorium dating of speleothems
In speleothem-palaeoclimatology, it is important to establish when the speleothem was growing so that the climate record can be placed in a wider context. To do this, a method called uranium-thorium dating is typically used, and this can be applied to speleothems that grew over the last 650,000 years. Uranium is highly soluble, consequently the water that the speleothem forms from will contain some very small quantity that is locked into the speleothem at the time of formation. Uranium is radioactive however, and will decay at a known rate with time and turn into thorium, which was not present in the speleothem at the time of formation. The ratio of thorium to uranium can be analysed to very high accuracy and precision, enabling the date of formation to be calculated. | <urn:uuid:af483d83-e509-45d5-ba8c-a7c7fbb39b19> | 3.71875 | 1,092 | Knowledge Article | Science & Tech. | 24.055419 | 95,583,099 |
Climate change: 1.5°C is closer than we imagine
Global warming of 1.5°C is imminent, likely in just a decade from now.
That’s the stunning conclusion to be drawn from a number of recent studies.
So how does that square with the 2015 Paris Agreement’s goal of “holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C” (above a late-nineteenth-century baseline)?
The Paris text was a political fix in which grand words masked inadequate deeds.
The voluntary national emission reduction commitments since Paris now put the world on a path of 3.4°C of warming by 2100, and more than 5°C if high-end risks including carbon-cycle feedbacks are taken into account.
The Paris outcome is a path of emissions continuing to rise for another fifteen years, when it was already clear that “if the 1.5°C limit should not be breached in any given year, the budget already overspent today ”.
Two years ago, Prof. Michael E. Mann noted: “And what about 1.5°C stabilisation? We’re already overdrawn.”
In fact, the emission scenarios associated with the Paris goal shows that the temperature will “overshoot” the 1.5°C target by up to half a degree, before cooling back to it by the end of this century.
Those scenarios rely unduly on unproven Bio-Energy with Carbon Capture and Storage (BECCS) technology, because the Paris Agreement does not encompass the steep emissions reductions that are required right now.
Average global warming is now 1.1°C above the late nineteenth century, and the rate of warming is likely to accelerate due to record levels of greenhouse gas emissions, and because efforts to clean up some of the world’s dirtiest power plants is reducing the emission of aerosols (mainly sulphates) which have a very short-term cooling impact.
So now, in 2018, the benchmark of 1.5°C of warming is just a decade away or even less, according to multiple lines of evidence from climate researchers:
HENLEY and KING: In 2017 Melbourne researchers Ben Henley and Andrew King published Trajectories toward the 1.5°C Paris target: Modulation by the Interdecadal Pacific Oscillation on the impact of the Interdecadal Pacific Oscillation (IPO) on future warming, (The IPO is characterized by sea surface temperature fluctuations and sea level pressure changes in the north and south Pacific Ocean that occur on a 15-30 year cycle.
In the IPO’s positive phase, surface temperatures are warmer due to the transfer of ocean heat to the atmosphere. The IPO has been in a negative phase since 1999 but recent predictions suggest that it is now moving to a positive phase.)
The authors found that “in the absence of external cooling influences, such as volcanic eruptions, the midpoint of the spread of temperature projections exceeds the 1.5°C target before 2029 , based on temperatures relative to 1850–1900”.
In more detail,”a transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026 ”, and “if the Pacific Ocean remains in its negative decadal phase, the target will be reached around 5 years later, in 2031 ”.
Caption: Projected temperature rises with IPO in positive mode (red) and negative mode (blue) (Henley and King, 2017)
JACOB et al: A set of four future emission scenarios, known as Representative Concentration Pathways (RCPs) have been used since 2013 as a guide for climate research and modelling.
The four pathways, known as RCPs 2.6, 4.5, 6 and 8.5, are based on the total energy imbalance in the energy system by 2100. RCP8.5 is the highest, and is the current emissions path.
In Climate Impacts in Europe Under +1.5°C Global Warming, released this year, Daniela Jacob and her co researchers found that the world is likely to pass the +1.5°C threshold around 2026 for RCP8.5, and “for the intermediate RCP4.5 pathway the central estimates lie in the relatively narrow window around 2030 .
In all likelihood, this means that a +1.5°C world is imminent.”
KONG AND WANG: In a study of projected permafrost change, Responses and changes in the permafrost and snow water equivalent in the Northern Hemisphere under a scenario of 1.5 °C warming, researchers Ying Kong and Cheng-Hai Wang use a multi-model ensemble mean from 17 global climate models, with results showing that the threshold of 1.5°C warming will be reached in 2027, 2026, and 2023 under RCP2.6, RCP4.5, RCP8.5, respectively.
On the present, high-emissions RCP8.5 path, the estimated permafrost area will be reduced by 25.55% or 4.15 million square kilometres.
XU and RAMANTHAN: A recent study by Yangyang Xu and Veerabhadran Ramanathan, Well below 2 °C: Mitigation strategies for avoiding dangerous to catastrophic climate changes, looked at the high-end or “fat-tail” risks of climate change, in an analysis of the existential risks in a warming world.
One of two baseline scenarios used, named Baseline-Fast, assumed an 80% reduction in fossil fuel energy intensity by 2100 compared to 2010 energy intensity.
In this scenario, the level of atmospheric carbon dioxide had reached 437 parts per million (ppm) by 2030 and the warming was 1.6°C, suggesting that the 1.5°C would be exceed around 2028 . The study is discussed in more detail here.
ROGELJ et al: In Scenarios towards limiting global mean temperature increase below 1.5C, Joeri Rogelj and co-researchers plot future emissions and warming based on five distinct “Shared Socioeconomic Pathways” (SSPs).
These “present five possible future worlds that differ in their population, economic growth, energy demand, equality and other factors”, according to CarbonBrief.
The fourth and fifth paths are the world we now live in: SSP4 is a world of “high inequality”, whilst SSP5 is a world of “rapid economic growth” and “energy intensive lifestyles”. If we look at these paths charted against projected temperatures, then SSP5 exceeds 1.5°C in 2029 and SSP4 by 2031.
Projected global mean temperature for five Shared Socioeconomic Pathways (CarbonBrief)
SCHURER et al: In Interpretations of the Paris climate target, Andrew Schurer and colleagues demonstrated that the IPCC uses a
definition of global mean surface temperature which underestimates the amount of warming over the pre-industrial level. The underestimation is around 0.3°C, and a higher figure includes the effect of calculating warming for total global coverage rather than for the coverage for which observations are
available, and warming from a true pre-industrial, instead of a late-nineteenth century, baseline. If their finding were applied, warming would now be 1.3°C or more, and hitting the 1.5°C benchmark just half a decade away.
CONSEQUENCES: In their 2017 paper on catastrophic climate risks, Xu and Ramanathan defined 1.5°C as a benchmark for “dangerous” climate change, compared to the convention policy-making mark of 2°C.
But even this lower mark may be too optimistic, given the impacts we have seen at both poles in the last decade.
In any case, it contemplating the imminent reality of the 1.5°C benchmark, it is important to consider what is at stake:
• In another decade and by 1.5°C, we may well have witnessed an Arctic free of summer sea ice, a circumstance that just two decades ago was not expected to occur for another hundred years.
The consequences would be devastating.
• In 2012, then NASA climate science chief James Hansen told Bloomberg that: “Our greatest concern is that loss of Arctic sea ice creates a grave threat of passing two other tipping points – the potential instability of the Greenland ice sheet and methane hydrates… These latter two tipping points would have consequences that are practically irreversible on time scales of relevance to humanity.” One highly-regarded research paper in 2012 estimated that “the warming threshold leading to a monostable, essentially ice-free state is in the range of 0.8–3.2°C, with a best estimate of 1.6°C” for the Greenland ice sheet.
• In 2015, researchers looked at the damage to system elements — including water security, staple crops land, coral reefs, vegetation and UNESCO World Heritage sites — as the temperature increases. They found all the damage from climate change to vulnerable categories like coral reefs, freshwater availability and plant life could happen before 2°C warming is reached, and much of it before 1.5°C warming.
• In 2009, Australian scientists contributed to an important research paper which found that preserving more than 10% of coral reefs worldwide would require limiting warming to below 1.5°C. Recent research found that the surge in ocean warming around the Great Barrier Reef in 2016, which led to the loss of half the reef, has a 31% probability of occuring in any year at just the current level of warming. In other words, severe bleaching and coral loss is likely on average every 3–4 years, whereas corals take 10–15 years to recover from such events.
• At 1.5°C, the loss of permafrost area is estimated to be four million square kilometres, and there is evidence that a 1.5oC global rise in temperature compared to the pre-industrial level is enough to start a general permafrost melt.
• The frequency of extreme El Nino events is likely to double by 1.5°C of warming.
• At 1.5°C, it is very likely that conclusions first aired in 2014 –– that sections of the West Antarctic Ice Sheet have already passed their tippings point for a multi-metre sea-level rise –– will have been confirmed. Four years ago scientists found that “the retreat of ice in the Amundsen Sea sector of West Antarctica was unstoppable, with major consequences – it will mean that sea levels will rise 1 metre worldwide… Its disappearance will likely trigger the collapse of the rest of the West Antarctic ice sheet, which comes with a sea-level rise of between 3–5 metres. Such an event will displace millions of people worldwide.” Leading cryosphere researcher Eric Rignot muses: “You look at West Antarctica and you think: How come it’s still there?
• By 1.5°C, a sea-level rise of many metres, and perhaps tens of metres will have been locked into the system. In past climates, carbon dioxide levels of around 400 ppm (which we exceed three years ago) have been associated with sea levels around 25 metres above the present. And six years ago, Prof. Kenneth G. Miller notes that “the natural state of the Earth with present carbon dioxide levels is one with sea levels about 20 meters higher than at present”.
Clearly, as James Hansen and co-authors wrote last year, “the world has overshot the appropriate target for global temperature”.
They noted a danger of 1.5°C or 2°C targets is that they are far above the Holocene temperature range and if such temperature levels are allowed to long exist they will spur “slow” amplifying feedbacks which have potential to run out of humanity’s control, so “limiting the period and magnitude of temperature excursion above the Holocene range is crucial to avoid strong stimulation of slow feedbacks”.
And in all this evidence, what worries me most?
It is my experience that with few exceptions neither climate policy-makers nor climate action advocates have a reasonable understanding of the imminence of 1.5°C and its consequences.
David Spratt is Research Director for Breakthrough National centre for Climate Restoration, www.breakthroughonline.org.au/ | <urn:uuid:ec751981-f588-415d-859d-3a4f341197eb> | 3.328125 | 2,653 | Personal Blog | Science & Tech. | 53.069333 | 95,583,104 |
In 2004, we revisited a Michigan stream invaded by rusty crayfish (Orconectes rusticus) to determine if this species continued to expand its downstream range and negatively impact the stream food web. Compared to a 1992 study, we predicted that rusty crayfish would increase in density and downstream distribution from a small lake, resulting in further reduction of in-stream resources such as organic matter, benthic invertebrates, and periphyton. To determine current crayfish distributions and impacts, we conducted a longitudinal survey of crayfish abundance, ran a 28-d leaf breakdown experiment, and sampled benthic substrates. Leaf packs of sugar maple (Acer saccharum) leaves were placed at three sites with differing crayfish densities (high, intermediate, and none). Breakdown rates were compared across the three sites and for two treatments (closed leaf bags excluding crayfish and open bags allowing crayfish access). Benthic invertebrates were sampled from leaf bags and invertebrates and periphyton were sampled from cobbles. In contrast to 1992, we found that the maximum downstream distance of rusty crayfish declined from 4 km to less than 3 km downstream from the lake. Leaves in open bags decayed significantly faster (k = 0.143) than did leaves in closed bags at all sites (k = 0.079) (p = 0.0005). The site lacking crayfish had significantly higher densities of invertebrates compared to both high and intermediate crayfish density sites (p = 0.005). Although we found that rusty crayfish reduced standing stocks of leaves and invertebrates, we did not detect measurable changes in periphyton biomass,. Therefore, rusty crayfish have not dispersed further downstream since 1992, but where present, these omnivores significantly reduce resource availability via the consumption of leaf material and benthic invertebrates.
Mendeley saves you time finding and organizing research
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Ancient aquatic amphibians developed the ability to feed on land before completing the transition to terrestrial life, researchers from Harvard University report this week in the Proceedings of the National Academy of Sciences.
Their work is based on analysis of the skulls of the first amphibians, which arose 375 million years ago, and their fish ancestors. The shapes of the junctions between adjacent skull bones -- termed "sutures" -- in the tops of these fish and amphibian skulls reveal how these extinct animals captured prey, say authors Molly J. Markey and Charles R. Marshall.
"Based on experimental data obtained from living fish, we found that the shapes of sutures in the skull roof indicate whether a fish captures its prey by sucking it into the mouth -- like a goldfish -- or by biting on it directly, like a crocodile," says Markey, a postdoctoral researcher and lecturer in Harvard's Department of Earth and Planetary Sciences. "A biting or chewing motion would result in a faint pushing together of the frontal bones in the skull, while a sucking motion would pull those bones ever so slightly apart. By comparing the skull roofs of living fish to those of early amphibians and their fishy ancestors, we were able to determine whether the fossil species fed by suction or by biting."
Using this approach, Markey and Marshall found that in one key transitional species, the aquatic amphibian Acanthostega, the shapes of the junctions between adjacent skull bones are consistent with biting prey. This finding, the scientists say, suggests that the water-dwelling Acanthostega may have bitten on prey at or near the water's edge.
"Going from the aquatic realm to land involved a series of adaptations to facilitate changes in locomotion, respiration, reproduction, sensation, and feeding," Markey says. "In water, suction is an efficient method of feeding, but it does not work in the much less dense air environment. Early terrestrial inhabitants would thus have had to develop the means for chomping prey."
Markey and Marshall first measured the skull roof sutures, those areas where the bones of the skull roof meet, in the living fish Polypterus as it fed. They then analyzed the same cranial junctions in several fossils -- the early amphibian Acanthostega, its fishy ancestor Eusthenopteron, and the extinct terrestrial amphibian Phonerpeton -- to determine how these bones may have moved relative to each other during feeding. By analyzing the tiny forces that the sutures experienced during feeding, such as tension or compression, the researchers could determine how the skull roof likely deformed as the animals ate.
Living fish exhibit an incredible array of tooth and jaw shapes, suggesting that, ironically, direct analysis of fossil jaws would be a less precise means of determining the feeding methods of extinct species, Markey says.
"Analysis of the sutures of the early amphibian species Acanthostega revealed that, while it had many adaptations to an aquatic lifestyle, it was more likely a biter than a sucker," Markey says. "The analysis suggests that amphibians evolved a bite before emerging onto land as fully terrestrial animals."
Steve Bradt | EurekAlert!
O2 stable hydrogenases for applications
23.07.2018 | Max-Planck-Institut für Chemische Energiekonversion
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
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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02-23-2018 10:44 PM
Astronomers See Evidence of Something Unexpected in the Universe
It will be interesting to see what is discovered in the course of trying to understand why these results disagree.
The team’s new study extends the number of stars analyzed to distances up to 10 times farther into space than previous Hubble results.
But Riess’s value reinforces the disparity with the expected value derived from observations of the early universe’s expansion, 378,000 years after the big bang — the violent event that created the universe roughly 13.8 billion years ago. Those measurements were made by the European Space Agency’s Planck satellite, which maps the cosmic microwave background, a relic of the big bang. The difference between the two values is about 9 percent. The new Hubble measurements help reduce the chance that the discrepancy in the values is a coincidence to 1 in 5,000
Planck’s result predicted that the Hubble constant value should now be 67 kilometers per second per megaparsec (3.3 million light-years), and could be no higher than 69 kilometers per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it is moving 67 kilometers per second faster. But Riess’s team measured a value of 73 kilometers per second per megaparsec, indicating galaxies are moving at a faster rate than implied by observations of the early universe.
The Hubble data are so precise that astronomers cannot dismiss the gap between the two results as errors in any single measurement or method. “Both results have been tested multiple ways, so barring a series of unrelated mistakes,” Riess explained, “it is increasingly likely that this is not a bug but a feature of the universe.”
The disagreement in these results could possibly indicate an expected new (to us) property of the Universe.
I find this article interesting not just because it is reporting results that are exciting on their own, but because it is reporting the disparity in results and shows scientists trying understand what is happening rather than covering it up, an accusation aimed at science that has been seen being made by the anti-science conspiracy nutjobs.
Links and Information Forum please.
What if Eleanor Roosevelt had wings? -- Monty Python
One important characteristic of a theory is that is has survived repeated attempts to falsify it. Contrary to your understanding, all available evidence confirms it. --Subbie
If evolution is shown to be false, it will be at the hands of things that are true, not made up. --percy
The reason that we have the scientific method is because common sense isn't reliable. -- Taq | <urn:uuid:7874e9db-ee2f-492a-a10f-184168b24f90> | 3.359375 | 582 | Comment Section | Science & Tech. | 45.217813 | 95,583,157 |
Image courtesy of Los Alamos National Laboratory
LOS ALAMOS, N.M. — Using neutron crystallography, a Los Alamos research team has mapped the three-dimensional structure of a protein that breaks down polysaccharides, such as the fibrous cellulose of grasses and woody plants, a finding that could help bring down the cost of creating biofuels. The research focused on a class of copper-dependent enzymes called lytic polysaccharide monooxygenases (LPMOs), which bacteria and fungi use to naturally break down cellulose and closely related chitin biopolymers.
“In the long term, understanding the mechanism of this class of proteins can lead to enzymes with improved characteristics that make production of ethanol increasingly economically feasible,” said Julian Chen, a Los Alamos National Laboratory scientist who participated in the research.
A multi-institution team used the neutron scattering facility at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory and the Advanced Light Source (ALS) synchrotron X-ray source at Lawrence Berkeley National Laboratory to study LPMO. Both SNS and ALS are DOE Office of Science User Facilities.
Los Alamos Bioscience Division scientists Chen, Clifford Unkefer, and former postdoctoral fellow John Bacik, working with collaborators at Oak Ridge National Laboratory, Lawrence Berkeley Laboratory, and the Norwegian University of Life Sciences, solved the structure of a chitin-degrading LPMO from the bacterium Jonesia denitrificans (JdLPMO10A). The team’s results are published in the journal Biochemistry (http://pubs.acs.org/doi/abs/10.1021/acs.biochem.7b00019?journalCode=bichaw).
One of the biggest challenges biofuel scientists face is finding cost-effective ways to break apart polysaccharides such as starches and cellulose, which are widely distributed in plants, into their subcomponent sugars for biofuel production. LPMO enzymes, which are seen as key to this process, use a single copper ion to activate oxygen, a critical step for the enzyme’s catalytic degrading action.
While the specific mechanism of LPMO action remains uncertain, it is thought that catalysis involves initial formation of a superoxide by electron transfer from the reduced copper ion. By understanding the location of the copper ion and the constellation of atoms near it, the researchers hope to elucidate more about the enzyme’s function. To do this, they rely on first determining the structure of the enzyme.
Although a number of X-ray crystallographic structures are currently available for LPMOs from fungal and bacterial species, this new structure is more complete. The investigators used X-ray crystallography to resolve the three-dimensional structure in clear detail of all the atoms except for hydrogens, the smallest and most abundant atoms in proteins. Hydrogen atom positions are important for elucidating functional characteristics of the target protein and can best be visualized using a neutron crystallography. The investigators used this complementary technique, to determine the three-dimensional structure of the LPMO, but highlighting the hydrogen atoms.
Notably, in this study the crystallized LPMO enzyme has been caught in the act of binding oxygen. Together with the recent structures of LPMOs from a wide variety of fungal and bacterial species, the results of this study indicate a common mechanism of degrading cellulosic biomass despite wide differences in their protein sequences. This study has furthered insight into the mechanism of action of LPMOs, particularly the role of the copper ion and the nature of the involvement of oxygen.
Biofuels research is part of the Los Alamos National Laboratory’s mission focus on integrating research and development solutions to achieve the maximum impact on strategic national security priorities such as new energy sources.
Funding: The Los Alamos component of the research was funded by the DOE Office of Science and imaging analysis was performed at DOE Office of Science user facilities. The work was also supported by The Research Council of Norway and the Norwegian Academy of Science and Letters.
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- Open Access
The Korean Bird Information System (KBIS) through open and public participation
- In-Hwan Paik†1,
- Jeongheui Lim†2,
- Byung-Sun Chun3,
- Seon-Duck Jin1,
- Jae-Pyoung Yu1,
- Joon-Woo Lee3,
- Jong Bhak2 and
- Woon-Kee Paek1Email author
© Paik et al; licensee BioMed Central Ltd. 2009
Published: 3 December 2009
The importance of biodiversity conservation has been increasing steadily due to its benefits to human beings. Recently, producing and managing biodiversity databases have become much easier because of the information technology (IT) advancement. This made the general public's participation in biodiversity conservation much more practical than ever. For example, an openfree web service can be devised for a wider spectrum of people to collaborate with each other for sharing biodiversity information. Bird migration is one such area of the collaboration. Korean migratory birds are usually traceable in the important routes of the East Asian-Australia Flyway (EAAF), and they play a key role as an environmental change indicator of the Earth. Therefore, the preservation of migratory birds requires an information system which involves a broader range of voluntary and interactive knowledge network to process bird information production, circulation, and dissemination.
The Korean Bird Information System (KBIS) aims to construct a cooperative partnership domestically and internationally through the acquisition, management, and sharing of Korean bird information involving both expert and non-expert groups. KBIS has six goals: data standard, system linkage, data diversity, utilization, bird knowledge network, and statistics. The key features of KBIS are to provide a simple search, gallery (photographs), and community to lead the participation of numerous non-experts, especially amateur bird watchers. The function of real-time observation data submission through the internet has been accomplished. It also provides bird banding database, statistics, and taxon network for experts. Especially, the statistics part provides the user with easy understanding of ecological trends of species based on the time and region.
KBIS is a tool for the conservation and management of bird diversity and ecosystem that encourages users to participate by providing the openfree data access and real-time data input web-interface. It will enhance bird knowledge networking activities locally, nationally, and internationally. In addition, it provides opportunities to enhance the public awareness for the preservation of bird diversity and species information in relevant localities through the database construction and networking activities. It can be found at http://korbird.naris.go.kr.
Korea is located in the midst of the eastern Asian and Australian migratory bird flight paths which have been serving as an important habitat for over 50 million water birds, equivalent to about 250 populations. However, because of coastal land reclamation and development policies, the Korean wetlands have been rapidly decreasing . As birds migrating across national boundaries are at the top echelon of the food chain, the preservation and management of bird species requires a global effort.
Birds serve an important role as an indicator of the earth's environmental issues [3–5], pollution [6, 7], and habitat environment . As indicator species, birds require cooperative monitoring network with not only expert groups but the general public as well. Through such cooperation, the construction of a bird information network has been actively carrying out in the world.
As an exemplary case, the Avian Knowledge Network (AKN) is an outgrowth of voluntary participation of citizens to build databases for bird species and habitat information, thereby contributing to effective and efficient bird preservation and management. Recently, the knowledge associated with pre-existing knowledge management have shifted their strategy which focused on technicality and efficiency before and this shift in strategy further developed into a two-way feedback structure as a knowledge network in the form of self-organization and co-evolution of knowledge, which in fact borrowed its concept from the ecological principles. In this sense, the AKN is striving to construct a bird knowledge network, a voluntary knowledge community by occasioning the huge observational information supplied by birth watchers to be shared with ornithologists, conservation biologists, and land managers through the utility and real-time accessibility rendered possible by eBird .
Currently, the development of a biodiversity information system which can be shared, accessible, and utilized by on-line is underway by various institutions globally . This trend is attributable to the low costs incurred and the resulting high-efficiency for requisite research, collection, application, and publication of biodiversity information which in turn contributes to the preservation, sustainable use, and management of biodiversity resources [16, 17].
Recently, web environments, such as Web 2.0 which is defining characteristics with users' participation and data sharing, have emphasized to maximize the utility and accessibility of the vast number of bird observations made by recreational and professional bird watchers. There are some contributing factors to promote such web environment: the development of GPS and digital cameras, public awareness concerning sustainable society, public science, Flicker , Youtube , and personal media. Especially, since biodiversity is involved with global partnerships, the aforementioned web environment is perfectly in accord with the necessity for the development of biodiversity information system.
Based on this background, as a device for Korean bird diversity preservation and management, we developed KBIS to access and share the bird sightings and locations with birding community made by experts and non-experts.
System development strategy
For the data standardization regarding bird species and habitats, the guidelines and classification systems from Global Biodiversity Information Facility (GBIF) and Wetlands International have been adopted. The banding DB has been made compatible with those of domestic and international. To accelerate practical use encouraging the acquisition and application of observational data from the public, the functions of 'Gallery' and 'My page' have been adopted. The former is primarily comprised of photographs taken by domestic bird watchers. The latter is for exchanging opinions and comments to control any incorrect information and for setting up personal information. A statistics function has been developed to show the bird populations based on the time or geographical location and the most current location of each group and population.
Data standard and protocol
Results and discussion
The user interface of KBIS is mainly comprised of data search (e.g., integrated search and simple search in My Guide Book), search results, data input (in banding DB, gallery, and my page), input results, and statistics.
The future development of KBIS will include several new functions. First, the bird species identification program by its morphology will be developed to encourage easier participation of inexperienced users. Second, efforts will be made to increase the collection of various contents through the linkage with NARIS and GBIF. Third, KBIS will enforce the data error management function. Because the generation, publication, and utilization of the extensive bird knowledge network with many participation by the general public will be more required for data reliability. Finally, we plan to implement the mobile application interface so that researchers can easily and rapidly deposit and monitor data in real time for sampling locations, collections, and observations.
KBIS's goal is to maximize the utility and accessibility of the vast number of bird observations, based on the interaction between recreational and professional bird watchers. KBIS has adopted international guidelines, such as Darwin Core 2.0 and DiGIR protocol, for data standard and exchange protocol. For the data quality control, the entered data are accompanied by comments and go through the verification by expert's reviews. The ecological information of bird was generated from observational and habitat data. The statistical function based on the region and time is accomplished to identify the variation and ecological tendencies of birds. With these various functions, KBIS are expected to play a great role in the conservation and protection of birds, collaborative partnerships, and environmental governance to the biodiversity community.
Other papers from the meeting have been published as part of BMC Genomics Volume 10 Supplement 3, 2009: Eighth International Conference on Bioinformatics (InCoB2009): Computational Biology, available online at http://www.biomedcentral.com/1471-2164/10?issue=S3.
We thank Byung-Ho Kang, Seung-hun Baek, Hee-Yeun Lee and Seong-Yong Yang, who provided technical assistance while constructing the database. This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Ministry of Education, Science and Technology (No. 20090080150, 20090080140 and M10869030001-08N6903-00110) in 2009. The authors thank Maryana Bhak for editing.
This article has been published as part of BMC Bioinformatics Volume 10 Supplement 15, 2009: Eighth International Conference on Bioinformatics (InCoB2009): Bioinformatics. The full contents of the supplement are available online at http://www.biomedcentral.com/1471-2105/10?issue=S15.
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- AKN - Avian Knowledge Network[http://www.avianknowledge.net/]
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- Jantsh E: The Self-Organizing Universe: Scientific and Buman Implications of the Emerging Paradigm of Evolution. Pergamon Press, New York; 1980.Google Scholar
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- Lim JH, Bhak J, Oh HM, Kim CB, Park YH, Paek WK: An Integrated Korean Biodiversity and Genetic Information Retrieval System. BMC Bioinformatics 2008, 9: 12–24. 10.1186/1471-2105-9-12View ArticleGoogle Scholar
- GBIF - Global Biodiversity Information Facility[http://www.gbif.org/]
- NARIS - Korean Natural History Research Information[http://www.naris.go.kr/]
- DiGIR - Distributed Generic Information Retrieval protocol[http://www.digir.net/]
- Darwin Core 2.0[http://www.digir.net/]
- RIS - The Information Sheet on Ramsar Wetlands[http://www.wetlands.org/rsis/]
- Wetlands International[http://www.wetlands.org/]
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:7a6dac75-4af2-467b-ab36-6060d4c7c5d2> | 3.046875 | 2,829 | Academic Writing | Science & Tech. | 33.434968 | 95,583,163 |
Evidence for the existence of such genetic variation for aging rates—a central tenet in the evolutionary theory that explains why animals would show physiological declines as they grow older—had largely been lacking in natural populations until now, the researchers said.
“We’ve found that individuals differ in their rates of aging, or senescence, and that these differences are (at least in part) caused by genetic effects so they will be inherited,” said Alastair Wilson of the University of Edinburgh. “While the genetic effects we found are completely consistent with existing theory, scientists hadn’t previously managed to test this theory properly except in controlled laboratory experiments.
“We’ve also done this work on long-lived mammals,” he added. “For someone interested in the evolution of aging and senescence in humans, these are going to be more relevant organisms than Drosophila [fruit flies].”
Scientists normally expect genetic mutations having bad effects to be removed by natural selection, Wilson explained. Conversely, selection will lead to an increase in the frequency of mutations that are beneficial. “On this basis, any genes with bad effects on survival or reproduction should be removed by selection,” he said. “But if that were true then there is no reason for individuals to deteriorate as they get old.”
Aging therefore raises a critical question: How has natural selection failed to remove genetic effects responsible for such reduced fitness among older individuals? Current evolutionary theory explains this phenomenon by showing that, as a result of the risk of death from environmental causes that individuals experience over the course of their lives, the force of selection inevitably weakens with age, he continued. This, in turn, means that genetic mutations having detrimental effects that are only felt late in life may persist in a population. Although widely accepted, this theory rests on the assumption that there is genetic variation for aging in natural systems.
To look for such genetic variation in the new study, the researchers examined wild Soay sheep and red deer living on two Scottish islands. Those populations were ideal for the study because they provide unparalleled levels of data, including individual survival and reproductive success, for large numbers of long-lived animals, Wilson said. In both study systems, individually marked animals are followed throughout their lives from birth until death, and their relationships to one another are known.
In both the red deer and sheep populations, they found evidence for age-specific genetic effects on “fitness”—a measure combining the animals’ probability of survival and reproduction. “The present study provides, to our knowledge, the first evidence for additive genetic variance in aging rates from a wild, non-model study organism,” the researchers concluded. “Furthermore, the age-specific patterns of additive genetic (co)variation evident in the two populations examined here were entirely consistent with the hypothesis that declines in fitness with age are driven by a weakening of natural selection.”
Cathleen Genova | alfa
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Seminal fluid contains protein factors that, when transferred from a male to a female at mating, affect reproductive success.
This is true of many different animals, from crickets to primates. In fruit flies, for instance, seminal fluid proteins influence the competitive ability of a male's sperm, and alter the female's post-mating behavior by dampening her interest in other males and cueing her to lay eggs. There is also some speculation, not yet proven, that having the wrong seminal fluid proteins might be one of several barriers to cross-breeding between closely related species.
Although several seminal fluid proteins have been characterized, little has been known about the exact kinds of transferred male proteins present in the female shortly after mating -- how many there are, their relative abundance, their structure, specific functions, and interactions with proteins from either the female or the seminal fluid of other males who mate with the same female. Gathering such information involves proteomics, the large-scale study of the nature and actions of proteins in living systems.
Using a new proteomic method, scientists at the University of Washington (UW) have discovered more than 80 proteins, previously not known to have a role in reproduction, that were transferred to female fruit flies in seminal fluids. Before this study, nearly 20 of the genes encoding these proteins were not even known to exist. The researchers also confirmed the presence of more than 70 additional proteins other scientists had predicted would be found.
The results were published in the July 29 issue of Public Library of Science (PLoS) Biology. The authors were Geoffrey D. Findlay, a doctoral candidate in the UW Department of Genome Sciences; Xianhua Yi, formerly a postdoctoral researcher at the UW and now with Momento Pharmaceuticals, Cambridge, Mass.; Michael J. MacCoss, assistant professor of genome sciences whose lab designs and tests new proteomic technologies; and Willie J. Swanson, associate professor of genome sciences whose lab studies the evolution and function of reproductive proteins. The Swanson lab looks at how changes in these proteins may lead to male/female mismatches and infertility from incompatibility, analogous to rejecting an organ transplant.
MacCoss said that it was surprising to observe how rapidly seminal fluid proteins evolve in fruit flies.
Each male fruit fly, Findlay said, has an evolutionary advantage if he can increase the competitive ability of his sperm. When the female retreats to lay eggs, he wants them to be his offspring.
To this end, the male's seminal fluid proteins aim to ensure that his sperm are successfully stored in the female's reproductive tract, cue the female to lay eggs immediately after receiving his sperm, and make the female less likely to mate again with another male. The proteins may also attempt to "disarm" the seminal proteins transferred to the female by other males. If a male's seminal proteins can outperform his competitors', he'll be more successful in passing on his genes to the next generation.
"Don't forget the female," Findlay added. "She's not a passive participant in the chemical struggle." The first male she mates with may not be the best father for her offspring, so it may not be in her interest to lay all of her eggs with his sperm. It is widely suspected that proteins in the female reproductive tract are co-evolving with their male counterparts to look out for the female's own reproductive interests.
"There is cooperation and conflict between the male and female," Findlay said. Each is pushing the envelop to serve his or her own reproductive interests. When the interests of males and females don't match, the sexes undergo an evolutionary struggle for control of the outcome. The competition among males, and the conflict between the sexes, may be driving the evolutionary patterns of their respective reproductive proteins.
This constant interplay between male and female proteins has caused seminal fluid content to differ between closely related species of fruit flies. The researchers showed this in two ways. First, by making DNA sequence comparisons, they found that when the same proteins appear in different species, the molecules often have different sequences and have diverged more quickly than would be expected by chance. Second, using proteomics, they identified proteins that are found only in certain species' seminal fluid.
Work in other labs has shown that female fruit flies that get too many shots of seminal fluid may pay with their lives. As the number of matings increase for a female, her behavior is more constantly under the influence of male seminal proteins and may move further away from the optimal for the female's physiological well-being. The males are not trying to kill the female, Findlay explained, but the toxic effect of mating is potentially a byproduct of protein manipulation.
Previous studies of seminal fluid proteins took years because each protein had to be painstakingly culled out.
"Separating transferred proteins from an animal's own proteins is like searching for a needle in a haystack," said MacCoss. "We modified a technique to label the females' proteins by feeding them yeast carrying a stable isotope. This made the female proteins in the specimens invisible to our mass spectrometer. We then could pick out the transferred male proteins." This same isotope labeling method, MacCoss said, could be used to detect other proteins transferred from one organism to another, such as from a nursing mother to her baby or from a pathogen to the animal it infects.
How does knowledge about fruit fly seminal fluid proteins help improve understanding of fertility and infertility in other living things or in human couples?
"The specific genes and proteins might be different, but it's likely that other genes and proteins fulfilling similar reproductive functions will be found in other species. Seminal fluid proteins are of critical importance in reproductive fitness," said Swanson, "but it's not as easy as saying, 'If we find this in fruit flies, this means it's in people.'"
Leila Gray | Newswise Science News
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16.07.2018 | Tokyo Institute of Technology
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
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Did you make it to work on time this morning? Go ahead and thank the traffic gods, but also take a moment to thank your brain. The brain’s impressively accurate internal clock allows us to detect the passage of time, a skill essential for many critical daily functions. Without the ability to track elapsed time, our morning shower could continue indefinitely. Without that nagging feeling to remind us we’ve been driving too long, we might easily miss our exit.
But how does the brain generate this finely tuned mental clock? Neuroscientists believe that we have distinct neural systems for processing different types of time, for example, to maintain a circadian rhythm, to control the timing of fine body movements, and for conscious awareness of time passage. Until recently, most neuroscientists believed that this latter type of temporal processing – the kind that alerts you when you’ve lingered over breakfast for too long – is supported by a single brain system. However, emerging research indicates that the model of a single neural clock might be too simplistic. A new study, recently published in the Journal of Neuroscience by neuroscientists at the University of California, Irvine, reveals that the brain may in fact have a second method for sensing elapsed time. What’s more, the authors propose that this second internal clock not only works in parallel with our primary neural clock, but may even compete with it.
Past research suggested that a brain region called the striatum lies at the heart of our central inner clock, working with the brain’s surrounding cortex to integrate temporal information. For example, the striatum becomes active when people pay attention to how much time has passed, and individuals with Parkinson’s Disease, a neurodegenerative disorder that disrupts input to the striatum, have trouble telling time.
But conscious awareness of elapsed time demands that the brain not only measure time, but also keep a running memory of how much time has passed. Scientists have long known that a part of the brain called the hippocampus is critically important for remembering past experiences. They now believe that it might also play a role in remembering the passage of time. Studies recording electrical brain activity in animals have shown that neurons in the hippocampus signal particular moments in time. But the hippocampus isn’t always necessary for tracking time. Remarkably, people with damage to their hippocampus can accurately remember the passage of short time periods, but are impaired at remembering long time intervals. These findings hint that the hippocampus is important for signaling some – but not all – temporal information. If this is the case, what exactly is this time code used for, and why is it so exclusive?
In their new study, the researchers tried to unravel this mystery by training rats to discriminate between different time intervals. They then rewarded the rats with treats when they indicated, by choosing between different odors, that they could tell how much time had passed. Before some of the trials the scientists injected a chemical that temporarily inactivates the hippocampus. This allowed them to test whether a functional hippocampus is necessary to distinguish between different time intervals.
The rats with inactive hippocampi could tell the difference between vastly different time intervals (e.g., 3 versus 12 minutes) just as well as the control rats, but performed no better than chance at detecting differences between similar periods of time (e.g., 8 versus 12 minutes). This suggests that the hippocampus is important for distinguishing between similar time intervals, but isn’t needed when the intervals are very different. But oddly enough, this pattern only held up at long time periods; rats with nonfunctional hippocampi were not just normal at discriminating between similar time periods at short scales (e.g., 1 versus 1.5 minutes), but they in fact performed better.
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The large shelf bordering Alaska extends across many physiographic and climatic regions. It is, therefore, not simple to classify the entire shelf into a few identifiable environments. The most commonly used parameters for defining the sedimentary environments are the sediment parameters. Lacking thorough knowledge of the hydrodynamic and other related information, the sedimentary parameters fail to fully elucidate the critical aspects of deposition, and especially the characteristic process over a large area. They may, however, fully characterize the sediments on a regional basis, particularly in a region with one or two identifiable detritus sources and with not too complex transporting agents.
KeywordsSedimentary Environment Sediment Texture Geochemical Parameter Shelf Environment Sediment Parameter
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- McManus, D. A., J. C. Kelly, and J. S. Creager. (1969). Continental Shelf Sedimentation in an Arctic Environment. Geol. Soc. Amer. Bull. 80: 1961–1984.Google Scholar | <urn:uuid:228ba0bb-bfa1-4ce9-b645-9a4012e721d2> | 2.546875 | 211 | Truncated | Science & Tech. | 20.124598 | 95,583,201 |
The one-year old European Emissions Trading Scheme received its first annual report card on May 15, 2006. The Ecosystem Marketplace asks the experts to weigh in on the market's successes and failures in the wake of the report. Scientists, economists, presidents and parliamentarians from 21 Western European nations launched the European Union Emissions Trading Scheme (EU ETS) in February 2005 as an ambitious free-market attack on global climate change. The market has been hailed as a financially lucrative and environmentally effective mechanism to spur polluters to cut carbon monoxide emissions, but the Scheme's first annual results released on May 15 unleashed aftershocks that are still shaking exchanges around the world. Crafted in response to the Kyoto protocol, the ETS allocated carbon-emission credits (intended to be 1 percent below baseline emissions) to each participating nation. The nations then divvied up these belt-tightening credits between 12,000 major polluters, including power, iron, steel, cement and paper plants. The plants could offset excess emissions by purchasing credits from more efficient plants or by building carbon-absorbing projects in less expensive developing countries. The market was to be the world's most ambitious environmental market yet and a harbinger of things to come. The first annual report on the market's progress, however, reveals that only Britain and a handful of other countries set their credit allocations low enough to require polluters to cut emissions. The remaining nations have leftover credits, indicating that their credit levels were set too high, enriching power plant owners by allowing them to sell their excess credits, but doing little to stem the carbon dioxide emitted into the atmosphere. Credits that had been trading at 31 euros per metric ton before the report data was leaked suddenly plunged to less than one-third that price. The market tumble set off a band of critics who say they are frustrated by the Scheme's design and uncertain of its ability to drive real environmental gain. Defenders, meanwhile, emphasize that this first year was intended only as a trial run to work out the kinks of a carbon-trading program slated to go into effect in 2008. Many also point to the innovative and effective projects built in third-world countries as a result of the trading scheme. Still, with $10 billion in carbon credits traded during the past year according to World Bank figures, it seems reasonable to ask what benefit the environment reaped from this massive effort. Has the Herculean effort behind the EU ETS been worth it?
Speaking from his London office as rain pounded the windowpanes, physicist Alex Rau, co-founder of Climate Wedge, a firm focused on expanding the voluntary market for carbon offsets, pointed out, "no one thought this first year would make a meaningful dent in the climate problem. This is training wheels for all of us. You run into things and fall over once or twice on training wheels. This is just a road test." Failures, others add, can offer valuable lessons in finding the right balance for using market forces to fight global warming. Economist John Reilly, associate director and author of "An Analysis of the European Emission Trading Scheme" for MIT's Joint Program on the Science and Policy of Global Change, said he was relieved when the cost of carbon credits collapsed. Carbon credits, he observed, would be expected to trade for a high price if there was a high demand for them, but since carbon-emissions reduction had been slated to be only one percent this first year, the credits' earlier price tag seemed to indicate that either "the market was screwed up or that it was incredibly costly to reduce carbon emissions." The broadest lesson learned during the Scheme's inaugural run, most economists and environmentalists agree, is that emissions targets must be accurately set at a level that drives investment. The Scheme could learn from the California model; instead of allowing polluters to fiddle with emissions data, California requires companies to submit current emission numbers so that the market has a solid baseline. The market must also be transparent, releasing emissions figures quarterly instead of annually. And instead of leaking results to stakeholders erratically (as happened this month), results should be released in a systematic, professional manner. Ironically, the price drop could be considered a victory for the environment, Reilly said. It provides reassurance to Scheme members as well as other large carbon-emission producers such as the United States that emissions can be cut at a reasonable cost.
Knocking at the Door
Paging through data documenting the rapid accumulation of greenhouse gases in the atmosphere, Steve Pacala of Princeton University's Carbon Mitigation Initiative says that the world has little time to waste when it comes to combating climate change. A glimpse at the data reveals that even if the ETS realizes its promise to cut emissions from Western European nations by 8 percent below 1990 levels, it would not significantly dent the greenhouse gases causing climate change. Instead, a massive effort involving most countries and fossil-fuel emitters is urgently required. As is, the amount of CO2 trapped in the atmosphere will double within the next 50 years and quadruple by the turn of the century. That, Pacala said during a break between proctoring final exams, would "bring out the monsters behind the door"—melting the Greenland ice cap, washing away coastal cities, spreading famine, and intermixing hurricanes with prolonged droughts. Scientific ability to predict climate change, Pacala says, is not yet sophisticated enough to say how many gigatons of CO2 emitted into the atmosphere will produce how many degrees of warming. It can, however, extrapolate that seven billion tons—seven gigatons—of carbon emissions must be prevented from entering the atmosphere during the next 50 years if we are to level off at 500 parts per million (ppm)—a point less than double the current atmospheric concentration of 380 ppm, but roughly double where the carbon level stood at 280 parts per million for thousands of pre-industrial years. Pacala uses the simple example of bakery-pie slices to explain how to achieve this seven-gigaton cut. He slices the pie into seven wedges that are 1 gigaton high and 50 years long. Western Europe's emissions comprise about 1 wedge of the pie. If the ETS successfully cuts emissions by 8 % by 2012—a serious challenge considering its limited success this past year—and continues with similar emission cuts for the next 40 years, it would be on track towards cutting out one wedge of the emissions pie. Still, six of the seven wedges remain—1 ½ representing United States emissions, another 1 ½ slices from Eastern Europe and three wedges from China, India and other developing nations. Had the Scheme's first trial year succeeded in cutting emissions by 1 percent, its portion of the 7-gigaton emissions pie would have been approximately one-fiftieth of a single slice in Pacala's seven-slice pie. Even a completely successful ETS carried out for nearly five decades, would not circumvent the cataclysmic events associated with increased global warming. That is, of course, unless the ETS were part of a larger worldwide effort to cut emissions. The European Trading Scheme's trial year, then, should also be evaluated for its ability to inspire copycats. And here, at last, we stumble upon some awe-inspiring success.
The Ripple Effect
Within the United States, California and at least eight northeastern states are developing cap and trade schemes. Venture capitalists are pouring money into green technology. General Electric just announced better-than-expected revenues thanks to its investments in renewable technologies. And a slew of funds have been set up to look at the carbon market, such as Rau's Climate Wedge, the world's first voluntary carbon-offset fund for large-scale institutional buyers. European energy plants, meanwhile, have been taking advantage of the Scheme's link to the Clean Development Mechanism (CDM) of the Kyoto Protocol, which allows industrialized countries to fund emissions reductions projects in the developing world in exchange for emissions reduction credits. European utilities with excess emissions have built innovative zero-emissions-energy projects such as wind farms, landfill-gas-recovery projects and high-efficiency boilers. Karan Capoor, a senior financial specialist at the World Bank, says this demonstrates that the market has been effective at going wherever it can to find low-cost-compliance solutions. Meanwhile, a surprising offshoot of the program is that it turns what had been an aid-model for third-world countries into a trade model. "When companies found it too costly to reduce their own emissions, they came up with a flood of projects in developing countries," Capoor said. "That's a clear success story."
Hunting for Lemons
All this talk of market lessons and new investments still does not address the original question; how will the world measure the environmental impact of the EU ETS to determine if it is an efficient approach to combating climate change? Most environmentalists, cognizant of the up-hill-battle they are fighting just to convince governments protective of their industries' bottom line that global warming is a scientific reality, have joined their economist colleagues in acknowledging that a market approach holds the most promise for reducing greenhouse gas emissions. "I'm a big believer of trading systems as a way to deal with large-scale-energy-intensive installations," says Eileen Claussen, president of the Pew Center on Global Climate Change. Annie Petsonk, international counsel for Environmental Defense's Global and Regional Air Program adds that she is particularly pleased with some of the innovations triggered by the CDM. "You can't predict whose lemons will make lemonade because people only thought of them as lemons before," she explains. "The Scheme triggered a big hunt for these lemons." One of her favorite "lemons" is a new technology that turns manure into methane that can be purified and used as natural gas. Inspired by the active market in Europe, people continue jumping on the bandwagon in the hopes of capitalizing on a perceived first-mover advantage in new emission-free, energy-producing industries. Since the Scheme and similar markets add a cost to emitting carbon, they will make zero-emission-emitting facilities financially viable. If these innovations become widely used, there could be a true global effort to address climate change, allowing Pacala's pie to be sliced by industries instead of geography. Of the seven wedges or gigatons of carbon emissions that must be prevented from entering the atmosphere, two could be saved by inducing industries to build better cars and other small but popular emitters. Increasing the size of carbon sinks such as forests, which naturally absorb carbon, and switching to conservation tillage on agricultural land, which keeps carbon locked up in the soil, could save another wedge. And four could come from transferring large-scale power plants into zero-emissions emitters. According to Pacala, the technology is already available. He is working with BP to build zero-emission power plants that capture CO2 before it is emitted, converting it into a solvent that can then be injected into the ground to allow oil pumps to extract more oil from already active drilling fields. Only a global attack on fossil fuel emissions, Pacala concludes, can sidestep otherwise imminent but nightmarish scenarios of populated cities washing away, towns swallowed into the Earth's faults and nations suffering through droughts and famine. "The market could be the most efficient way of solving global warming," Pacala reasons, before adding: "One way or another, we have to solve this." Alice Kenny is a prize-winning science writer and a regular contributor to the Ecosystem Marketplace. She may be reached at firstname.lastname@example.org. First published: May 31, 2006 Please see our Reprint Guidelines for details on republishing our articles. | <urn:uuid:3256c3eb-ea9a-47f8-8f24-b32e01aa4958> | 2.890625 | 2,392 | Nonfiction Writing | Science & Tech. | 32.905917 | 95,583,229 |
Physicists Crack Science of Ice Formation
News Feb 28, 2013
And the higher the solute concentration, the slower ice forms. That's why solutes, or "cryoprotectants," are added to proteins, cells, tissues and even dead bodies to slow down ice formation during cryopreservation.
Intrigued by this rather poorly understood process, Cornell physicists have discovered that, for a variety of common cryoprotectants, the time for ice to form has a simple exponential variation with concentration. It's the first molecular-level understanding of exactly how solutes slow down ice formation, and it has implications in fields ranging from climate physics to cryopreservation and artificial insemination.
Matthew Warkentin, a physics postdoctoral associate, together with professors of physics Robert Thorne and James Sethna, published these findings online in Physical Review Letters in January.
Ice forms in supercooled pure water in about 1 microsecond (one-millionth of one second). That time gets multiplied by 10 for every incremental increase in solute concentration. In a 50 percent glycerol-water solution, for example, ice formation can take almost a minute.
The simple exponential behavior suggested that there might be a correspondingly simple explanation, Warkentin said.
In order for ice to form, a small cluster of about 50 water molecules must form a crystalline "nucleus"; a smaller cluster will tend to shrink and disappear, but larger clusters will keep growing as long as liquid water is available. The researchers postulated that the solute molecules "get in the way" of water molecules trying to form a nucleus.
By calculating the probability of finding a nucleus-size volume free of the solute molecules that were preventing nucleation, they derived the exponential dependence on solute concentration and were able to quantitatively replicate data for eight different solutes, ranging from salt to sugar to alcohol. The resulting simple theory used statistical mechanics to extend classical nucleation theory.
In looking at the implications of the work for climate change, for example, Thorne said that modern climate models must take into account a measure of the Earth's reflectiveness, which is influenced by cloud cover. This in turn requires understanding of when and why cloud particles crystallize or remain liquid.
Furthermore, cryopreservation is widely used in medicine and biotechnology, where ice formation can be lethal to cells and tissues. Fertility clinics routinely freeze sperm, eggs and fertilized embryos, and nearly all domestic cattle and swine are propagated using cryopreserved semen, Thorne said.
Aside from its simplicity, an exciting feature of the new theory is that it is generalizable to other liquids and to any system undergoing nucleation, the researchers added.
The work was supported by the National Science Foundation and the National Institutes of Health.
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1 m3 of wood planks costs 179 EUR. How much will I pay for 11 planks measuring 6 cm, 10 cm and 6 m?
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The scientific community concurs that the occurrence of harmful algal blooms (HABs) is increasing worldwide. The annual loss from HABs worldwide is probably more than $1 billion, including both mortality and unmarketable products. The annual human cost has been estimated at 2,000 cases of poisoning with 15% mortality. Because there is no international record of economic loss and human intoxication incidents by HABs, these numbers are almost certainly underestimates.
In a recent issue of Northeastern Naturalist, University of Rhode Island biological oceanographers Paul E. Hargraves and Lucie Maranda described the occurrence of 46 phytoplankton species that are potentially toxic to humans, or harmful to marine life, or both. The area from which they compiled their information includes the southeast coast of Nova Scotia to the Hudson River estuary in New York and out to the edge of the continental shelf. The research was supported by the National Science Foundation and the National Oceanic and Atmospheric Administration.
Hargraves and Maranda included in their list species considered potentially toxic to humans if one or more strains of the species is known to produce toxins affecting humans, the species in strongly implicated or proven to cause human illness or fatality, or the species has produced a positive reaction in mammalian toxicity tests. They also included species harmful to marine life if one or more strains are known to produce substances harmful to normal life processes, or the species is strongly implicated or proved to cause mortality under laboratory or natural conditions.
Lisa Cugini | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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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.
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12.07.2018 | Event News
03.07.2018 | Event News
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Metallography and Microstructure of Ancient and Historic Metals
by David A. Scott
Publisher: Oxford University Press 1991
Number of pages: 176
This book provides an introduction to the structure and morphology of ancient and historic metallic materials. It deals extensively with many practical matters relating to the mounting, preparation, etching, polishing, and microscopy of metallic samples and includes an account of the way in which phase diagrams can be used to assist structural interpretation.
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Download or read it online for free here:
- The National Academies Press
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Friday, June 28, 2013
Our galaxy has greater than before its diameter is ten times
The astronomers, led by John Stoke by the University of Colorado at Boulder (USA), reported that the new observations spectrograph Space Telescope "Hubble" forced them to rethink the size of the halo of spiral galaxies such as our Milky Way. So - and significantly change our estimates of their mass.
This entire glowing disc, which we used to call the Milky Way, represents only the tip of the iceberg, nine-tenths of which are lost in the darkness.
If today the size of the disk of the Milky Way is estimated to be 100,000 light years, and the halo of the galaxy has assumed the dimensions of the disk at tens of thousands of light years, it is now a group of Mr. Drain argues that the diameter of the halo of gas exceeds one million light years - more than ten time visible disk of the Milky Way, or about ten quintillion kilometers.
In general, the "home" of our solar system is a hundred times more extensive than we had imagined it.
Well, while this gas is found in a given because it was driven by supernova explosions from the main disk. But he did not get lost in intergalactic space, and gradually began to converge again with the Galaxy and getting into the drive, take part in the formation of stars.
Building on the work of predecessors in terms of chemical composition and density of the gas clouds, huge halo John's team Stoke evaluates its mass approximately equal to the total mass of stars the average twist galaxy. It was a big surprise, said the head of research.
So now baryonic (normal) matter of galactic disks can easily multiply almost twice that in the future may slightly reduce the proportion of dark matter in the total mass of the universe.
Earlier theoretical predictions of the mass of gas in spiral galaxies give the result, about five times superior to the one that was observed by astronomers. New evidence to reconcile practice with theory, emphasizes the scientist.
The study report presented at a conference on the interactions of galaxies. It was June 27, 2013 at the University of Edinburgh (UK).
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The university has produced a press release on Mason's Porter's work on network communities. Below is a copy of the press release:
A new way of finding community structure within networks – anything from social networks such as Facebook, to power grids, political voting networks, and protein interaction networks in biology – could help us understand how people are connected and how connections change over time. The new technique, developed by a team from the University of North Carolina, University of Oxford, and Harvard University, aims to be more realistic than conventional approaches, which only capture one type of connection or a network at only one moment in time.
The new approach captures the totality of connections within a network and could be used to examine the different ways communities form; for example, analysing relationships between University students and staff across many different connections such as Facebook friendship, College affiliation, and subject studied. Alternatively, it could be used to track how one type of connection – such as Facebook friendship – changes over time.
The technique is not limited to social networks as community detection has the potential to find important groups in many other applications, such as protein-protein interaction networks, transportation networks, and political voting networks.
A report of the team’s work, advancing the theory of community detection, will be published in this week’s Science.
‘Capturing the complexity of people's relationships through networks such as Facebook and how these relationships change over time is a huge challenge,’ said Dr Mason Porter of Oxford University's Mathematical Institute, an author of the report. ‘Our new approach, which can be applied to any type of network, is potentially much better than existing methods at identifying what makes a 'community' within a network and at tracking how such groupings evolve over time.’
Until now, it was only possible to detect communities using computer algorithms in very special cases – in particular, only in networks that are treated as if they don't change over time and as if they have only one type of connection.
The new computational method can be used with what researchers call ‘multislice’ networks, in which each ‘slice’ might represent a social network at one snapshot in time or a different set of connections between the same set of individuals. These ‘slices’ are combined into a larger mathematical object, which can contain a potentially huge amount of data and is difficult to analyse. Previous community-finding methods could only deal with each slice separately, and it was necessary to compare the results obtained from different slices using ad hoc tools (if it was possible at all) and the new method overcomes this key challenge.
‘It's very easy to use ‘ad hoc’ methods and miss something that is potentially interesting or important in such complex networks,’ said Dr Porter. ‘Whilst our new approach doesn't dictate what you will find, it does potentially give you a much better chance of finding interesting connections if they're there.’
- A report of the research, entitled ‘Community Structure in Time-Dependent, Multiscale, and Multiplex Networks’, is published in Science on 14 May, embargoed until 19:00 BST/14:00 EST (US) 13 May 2010. | <urn:uuid:e5ae9111-ea1a-4311-8a61-aaf9f62c8689> | 2.53125 | 667 | News (Org.) | Science & Tech. | 20.235779 | 95,583,342 |
Whether you’re building an Android application in Unity or programming it from scratch, you must set up the Android Software Development Kit (SDK) before you can buildThe process of compiling your project into a format that is ready to run on a specific platform or platforms. More info
See in Glossary and run any code on your Android device.
Download and install the Java Development Kit (JDK). Unity requires the 64-bit version JDK 8 (1.8).
You can install the Android SDK using command line tools orthrough Android Studio. Android Studio provides an easy to use GUI based tool, but installs additional software on your computer. Using the command line tools is a smaller download and does not install additional software, but it can be more challenging to use.
Install or unpack the Android SDK. After installing, open the Android SDK Manager and add: at least one Android SDK Platform, the Platform Tools, the Build Tools, and the USB drivers if you’re using Windows.
To install an Android platform SDK and the associated tools:
Download the Android Software command line tool.
Unzip the tools folder to a location on your hard drive.
Open a command-prompt window.
Navigate to the bin folder in the location where you unzipped the tools folder: “install folder” > tools > bin
Use the sdkmanager command line tool to retrieve the list of packages that you can install. The installable packages include the Platform SDKs, Build Tools, Platform tools, and other tools.
Select a version of the Platform SDK to install. Platform SDKs take the following form in the list: platforms;android-xx. The xx indicates the SDK level. The larger the number, the newer the package. Typically, you can install the latest available version. But, there might be cases in which Google has released a new version of the SDK that causes errors when you build your Unity Project. In that case you must uninstall the SDK and install an earlier version. The general format of the command for package installation is sdkmanager <package name>. You can install the corresponding Platform Tools and Build Tools at the same time.
Example: sdkmanager “platform-tools” “platforms;android–27” “build-tools;27.0.3”
If you are running on Windows, install the USB device drivers.
This installs the SDK in a directory named “platforms” in the directory in which you unzipped the tools folder. Example: c:\<install folder>\platforms
Install Android studio from the Android developer portal. The Android developer portal provides detailed installation instructions.
When installing the Android platform SDK and other tools, you can typically install the latest available version. There might be cases in which Google has released a new version of the SDK that causes errors when you build your Unity Project. In that case you must uninstall the SDK and install an earlier version.
Install the associated Platform and Build tools at the same time. If you are running on Windows, install the USB device drivers.
To enable USB debugging, you must enable Developer options on your device. To do this, find the build number in your device’s Settings menu. The location of the build number varies between devices. The stock Android setting can be found by navigating to Settings > About phone > Build number. For specific information on your device and Android version, refer to your hardware manufacturer.
Note: On Android versions prior to 4.2 (Jelly Bean), the Developer options aren’t hidden. Go to Settings > Developer options, then enable USB debugging.
After you navigate to the build number using the instructions above, tap on the build number seven times. A pop-up notification saying “You are now X steps away from being a developer” appears, with “X” being a number that counts down with every additional tap. On the seventh tap, Developer options are unlocked.
Connect your device to your computer using a USB cable. If you are developing on a Windows computer, you might need to install the a device specific USB driver. See the manufacture web site for your device for additional information.
The setup process differs for Windows and macOS, and is explained in detail on the Android developer website. For more information on connecting your Android device to the SDK, refer to the Running Your App section of the Android Developer documentation.
Go to Settings > Developer options, and check the USB debugging checkbox to enable debug mode when the device is connected to a computer via USB.
The first time you create a Project for Android (or if Unity later fails to locate the SDK), Unity asks you to locate the folder in which you installed the Android SDK.
If you installed the SDK using the sdkmanager, you can find the folder in <android tools install location>\platforms\<android sdk folder>.
c:\<android tools install location>\platforms\android–27
If you installed the SDK when you installed Android Studio, you can find the location in the Android Studio SDK Manager. To open the SDK Manager from Android Studio, click Tools > Android > SDK Manager or click SDK Manager in the toolbar.
To change the location of the Android SDK, in the menu bar go to Unity > Preferences > External Tools.
If you are using the IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary scripting backendA framework that powers scripting in Unity. Unity supports three different scripting backends depending on target platform: Mono, .NET and IL2CPP. Universal Windows Platform, however, supports only two: .NET and IL2CPP. More info
See in Glossary for Android, you need the Android Native Development Kit (NDK). It contains the toolchains (such as compiler and linker) needed to build the necessary libraries, and finally produce the output package (APK). If you are not targeting the IL2CPP back end, you can skip this step.
Download Android NDK version r13b (64-bit) from the NDK Downloads web page. Extract the android-ndk folder to a directory on your computer and note the location.
The first time you build a Project for Android using IL2CPP, you are asked to locate the folder in which you installed the Android NDK. Select the root folder of your NDK installation. To change the location of the Android NDK, in the Unity Editor, navigate to the menu: Unity > Preferences to display the Unity Preferences dialog box. Here, click External Tools.
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This article needs attention from an expert in Physics.(September 2016)
Pascal's law (also Pascal's principle or the principle of transmission of fluid-pressure) is a principle in fluid mechanics that states that a pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. The law was established by French mathematician Blaise Pascal in 1647–48.
Pascal's principle is defined as
A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.
This principle is stated mathematically as:
- is the hydrostatic pressure (given in pascals in the SI system), or the difference in pressure at two points within a fluid column, due to the weight of the fluid;
- ρ is the fluid density (in kilograms per cubic meter in the SI system);
- g is acceleration due to gravity (normally using the sea level acceleration due to Earth's gravity, in SI in metres per second squared);
- is the height of fluid above the point of measurement, or the difference in elevation between the two points within the fluid column (in metres in SI).
The intuitive explanation of this formula is that the change in pressure between two elevations is due to the weight of the fluid between the elevations. Alternatively, the result can be interpreted as a pressure change caused by the change of potential energy per unit volume of the liquid due to the existence of the gravitational field.[further explanation needed] Note that the variation with height does not depend on any additional pressures. Therefore, Pascal's law can be interpreted as saying that any change in pressure applied at any given point of the fluid is transmitted undiminished throughout the fluid.
If a U-tube is filled with water and pistons are placed at each end, pressure exerted against the left piston will be transmitted throughout the liquid and against the bottom of the right piston. (The pistons are simply "plugs" that can slide freely but snugly inside the tube.) The pressure that the left piston exerts against the water will be exactly equal to the pressure the water exerts against the right piston. Suppose the tube on the right side is made wider and a piston of a larger area is used; for example, the piston on the right has 50 times the area of the piston on the left. If a 1 N load is placed on the left piston, an additional pressure due to the weight of the load is transmitted throughout the liquid and up against the larger piston. The difference between force and pressure is important: the additional pressure is exerted against the entire area of the larger piston. Since there is 50 times the area, 50 times as much force is exerted on the larger piston. Thus, the larger piston will support a 50 N load - fifty times the load on the smaller piston.
Forces can be multiplied using such a device. One newton input produces 50 newtons output. By further increasing the area of the larger piston (or reducing the area of the smaller piston), forces can be multiplied, in principle, by any amount. Pascal's principle underlies the operation of the hydraulic press. The hydraulic press does not violate energy conservation, because a decrease in distance moved compensates for the increase in force. When the small piston is moved downward 100 centimeters, the large piston will be raised only one-fiftieth of this, or 2 centimeters. The input force multiplied by the distance moved by the smaller piston is equal to the output force multiplied by the distance moved by the larger piston; this is one more example of a simple machine operating on the same principle as a mechanical lever.
Pascal's principle applies to all fluids, whether gases or liquids. A typical application of Pascal's principle for gases and liquids is the automobile lift seen in many service stations (the hydraulic jack). Increased air pressure produced by an air compressor is transmitted through the air to the surface of oil in an underground reservoir. The oil, in turn, transmits the pressure to a piston, which lifts the automobile. The relatively low pressure that exerts the lifting force against the piston is about the same as the air pressure in automobile tires. Hydraulics is employed by modern devices ranging from very small to enormous. For example, there are hydraulic pistons in almost all construction machines where heavy loads are involved.
Pascal's barrel is the name of a hydrostatics experiment allegedly performed by Blaise Pascal in 1646. In the experiment, Pascal supposedly inserted a long vertical tube into a barrel filled with water. When water was poured into the vertical tube, the increase in hydrostatic pressure caused the barrel to burst.
The experiment is mentioned nowhere in Pascal's preserved works and it may be apocryphal, attributed to him by 19th-century French authors, among whom the experiment is known as crève-tonneau (approx.: "barrel-buster"); nevertheless the experiment remains associated with Pascal in many elementary physics textbooks.
Applications of Pascal's law
- The underlying principle of the hydraulic jack and hydraulic press.
- Force amplification in the braking system of most motor vehicles.
- Used in artesian wells, water towers, and dams.
- Scuba divers must understand this principle. At a depth of 10 meters under water, pressure is twice the atmospheric pressure at sea level, and increases by about 100 kPa for each increase of 10 m depth.
- Usually Pascal's rule is applied to confined space (static flow), but due to the continuous flow process, Pascal's principle can be applied to the lift oil mechanism (which can be represented as a U tube with pistons on either end). However, the lift height will be in microns because energy will be drained and pressure will be diminished after each impact with the lifting material, but force exerted will be equal.
- Applied force in cylinder P1A1.
- The underlying principle of hot isostatic pressing
- "Pascal's principle - Definition, Example, & Facts". britannica.com. Archived from the original on 2 June 2015. Retrieved 9 May 2018.
- "Pascal's Principle and Hydraulics". www.grc.nasa.gov. Archived from the original on 5 April 2018. Retrieved 9 May 2018.
- "Pressure". hyperphysics.phy-astr.gsu.edu. Archived from the original on 28 October 2017. Retrieved 9 May 2018.
- Bloomfield, Louis (2006). How Things Work: The Physics of Everyday Life (Third Edition). John Wiley & Sons. p. 153. ISBN 0-471-46886-X.
- Acott, Chris (1999). "The diving "Law-ers": A brief resume of their lives". South Pacific Underwater Medicine Society journal. 29 (1). ISSN 0813-1988. OCLC 16986801. Archived from the original on 2011-04-02. Retrieved 2011-06-14..
- O'Connor, J.J.; Robertson, E.F. (August 2006). "Étienne Pascal". University of St. Andrews, Scotland. Archived from the original on 19 April 2010. Retrieved 5 February 2010.
- Merriman, Mansfield (1903). Treatise on hydraulics (8 ed.). J. Wiley. p. 22.
- perhaps first in an educational context; the attribution is found under this name in A. Merlette, L'encyclopédie des écoles, journal de l'enseignement primaire et professionnel (1863) p. 284 Archived 2017-02-06 at the Wayback Machine.: l'expérience du crève-tonneau réalisée pour la première fois par le célèbre Biaise Pascal. Ernest Menu de Saint-Mesmin, Problèmes de mathématiques et de physique: donnés dans les Facultés des science et notamment à la Sorbonne, avec les solutions raisonnées, L. Hachette (1862), p. 380 Archived 2017-02-06 at the Wayback Machine..
- see e.g. E. Canon-Tapia in: Thor Thordarson (ed.) Studies in Volcanology, 2009, ISBN 9781862392809, p. 273. | <urn:uuid:970749fb-6e0f-4c85-a0d1-8fcfb3d8ae30> | 4.21875 | 1,738 | Knowledge Article | Science & Tech. | 55.656203 | 95,583,376 |
Researchers at the University of Minnesota and Seoul National University shed light on efficiencies of socially networked local delivery
What if your cell phone and social network could help deliver packages for you – AND reduce greenhouse gas emissions?
This may be more likely, easier and more beneficial to the environment than you might think, researchers at the University of Minnesota’s Institute on the Environment and Seoul National University report in the current issue of Environmental Science & Technology.
Online shopping may be economical and convenient from the shopper’s standpoint, but it can also carry a hefty environmental price. Particularly, the “last mile” of local delivery is the retail system’s largest contributor to fossil fuel consumption, CO2 and local air emissions. Replacing traditional home truck delivery with pickup locations can help in some instances. But in the suburbs, such systems can actually increase overall travel distances and emissions as personal vehicles detour from their normal daily activity to make the pickup.
That is, according to the ES&T article, unless you can find a few good friends to help.
The study used spatial and agent-based models to investigate the potential environmental benefits of enlisting social networks to help deliver packages. While sensitive to how often trusted and willing friends can be found in close proximity to both the package and the recipient within a day, results indicate that very small degrees of network engagement can lead to very large efficiency gains.
Compared to a typical home delivery route, greenhouse gas emissions reductions from a socially networked pickup system were projected to range from 45 percent to 98 percent, depending on the social connectedness of the recipients and the willingness of individuals in their social networks to participate.
“What is important is that sharing be allowed in the system, not how many ultimately chose to share time or resources,” says study co-author Timothy Smith, director of IonE’s NorthStar Initiative for Sustainable Enterprise. “We find that providing the relatively few really inefficient actors in the network the opportunity to seek the help of many better positioned actors can radically improve performance.”
This is particularly relevant today, Smith says, as online retailers such as Amazon begin introducing delivery pickup lockers in grocery, convenience and drug stores.
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Frozen biological material, for example food, can be kept for a long time without perishing. A study by researchers at the University of Gothenburg, Sweden is close to providing answers as to why.
A cell's proteins are programmed to carry out various biological functions. The protein's level of activity and its ability to successfully carry out these functions is dependent on the amount of water by which it is surrounded. For example, dry proteins are completely inactive. A critical amount of water is required in order for the function to get going, after which point the protein's level of activity increases concurrently with an increase in the amount of water. Proteins achieve full biological activity when the surrounding water has approximately the same weight as the protein.
Researchers at the University of Gothenburg and Chalmers University of Technology have together with a group of American researchers used advanced experimental techniques to study how movements in the water that surrounds the protein cause movements in the protein itself. The study, which is being published in the journal PNAS, indicates that the dynamics in the surrounding water have a direct effect on the protein's dynamics, which, in turn, should affect the activity.
The results explain, for example, why biological material such as foodstuffs or research material can be stored at low temperatures for a long period of time without perishing.
"When the global movements in the surrounding water freeze, then significant movements within the protein also come to a stop. This results in the protein being preserved in a state of minimum energy and biological activity comes to a stop," says researcher Helén Jansson at the Swedish NMR Centre, University of Gothenburg.Press information: Krister Svahn
Krister Svahn | idw
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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...
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Synchrotron radiation for long wavelength spectroscopy
- 22 Downloads
A fundamental radiometric measurement has been carried out in the spectral region 1–140 cm−1 which demonstrates the higher brightness of the synchrotron radiation source at Daresbury Laboratory over a high pressure mercury arc lamp source. Comparison of the output powers from the SRS and the mercury lamp revealed that the SRS has a particular advantage in the region where the wavelength of the emitted photon becomes very longer. The gain factor of the SRS at 10 cm−1 was at least 10 times of the mercury lamp at a storage ring current of about 90 mA.
A single period wiggler is considered to be a favorable device which will provide a higher level of photon fluxes from an electron storage ring in the long wavelength region.
KeywordsSynchrotron Radiation Storage Ring Mercury Lamp Ring Current Synchrotron Radiation Source
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Farmer John's N cows (1≤N≤1000) want to organize an emergency "moo-cast" system for broadcasting important messages among themselves.
Instead of mooing at each-other over long distances, the cows decide to equip themselves with walkie-talkies, one for each cow. These walkie-talkies each have a limited transmission radius, but cows can relay messages to one-another along a path consisting of several hops, so it is not necessary for every cow to be able to transmit directly to every other cow.
The cows need to decide how much money to spend on their walkie-talkies. If they spend \$X, they will each get a walkie-talkie capable of transmitting up to a distance of √X. That is, the squared distance between two cows must be at most X for them to be able to communicate.
Please help the cows determine the minimum integer value of X such that a broadcast from any cow will ultimately be able to reach every other cow.
The first line of input contains N.
The next N lines each contain the x and y coordinates of a single cow. These are both integers in the range 0…25,000.
Write a single line of output containing the integer X giving the minimum amount the cows must spend on walkie-talkies.
4 1 3 5 4 7 2 6 1 | <urn:uuid:037d6416-b7b9-4e66-a05f-a72fc0e5cf77> | 3.046875 | 375 | Tutorial | Science & Tech. | 71.580108 | 95,583,385 |
While we generally think of water in nature as a cool liquid that we can see -- streams, lakes, oceans -- there is a great deal of “hot fluid” activity taking place far out of sight, deep within the earth, that influences what ultimately takes place on the surface, including the amount of rainfall and the buildup of new land mass.
Illustration shows the layers of the earths subsurface.
What exactly is the nature of that hidden fluid deep beneath the surface and what changes does it undergo as it seeks an ever-deeper venue?
Answer to these questions can be found in article in a recent issue of the journal Nature by Dr. Ronit Kessel of the Hebrew University’s Institute of Earth Sciences and her collaborators Prof. Max Schmidt, Prof. Peter Ulmer and Dr. Thomas Pettke from the Swiss Federal Institute of Technology, Zurich. In the article, the researchers report on a unique study in which fluids released from submerging earth plates at depths of 120-180 kilometers and temperatures between 700 and 1200 degrees centigrade are characterized for the first time.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
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Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Scientists have measured the nutritional value of herbivore dinosaurs' diet by growing their food in atmospheric conditions similar to those found roughly 150 million years ago.
Strawberries and tomatoes are among the most widely consumed fruits and vegetables worldwide. However, many people are allergic to them, especially if they have been diagnosed with birch pollen allergy. A team from the Technical University of Munich has investigated which strawberry or tomato varieties contain fewer allergens than others and to what extent cultivation or preparation methods are involved.
Researchers have calculated the capacity of North American forests to sequester carbon in a detailed analysis that for the first time integrates natural processes and climate changes that are likely to alter growth over the next 60 years.
New research from scientists at Point Blue Conservation Science and The Nature Conservancy shows how financial incentive programs can create vital habitat for waterbirds, filling a critical need in drought years. Researchers used satellite images to evaluate two issues: 1) the impact of the 2013-2015 drought on waterbird habitat in the Central Valley; and, 2) the amount of habitat created by incentive programs.
The genome of the algae species Chara braunii has been decoded. It already contains the first genetic characteristics that enabled the water plants' evolutionary transition to land.
University of Guelph researchers have discovered unsuitable soil at higher altitudes may be halting the advancement of treelines. This finding dispells the commonly held assumption that climate change is enabling trees to move farther uphill and northward. The researchers looked at plant growth at higher altitudes in the Canadian Rockies, grew spruce and fir seedlings at varying elevations and collected soil samples from the same areas to grow spruce seeds in growth chambers .
An international team, which included three University of Maryland researchers, sequenced and analyzed the genome of Chara braunii, a freshwater green alga closely related to land plants. By comparing Chara's genome to multiple land plant genomes, the team was able to identify many important genes that originated in a common ancestor shared by Chara and land plants.
University of Kansas scientists discovered that polyps have no qualms about treating a nonrelated individual like part of the family. This goes way beyond sharing meals or even a roof. Polyps of the marine hydrozoan Ectopleura larynx allow nonrelated individuals to fuse their bodies to the familial colony and share what is essentially skin and a stomach. The findings appeared yesterday in the journal Evolution Letters.
Invasive plants have the ability to adapt to new environments -- and even behave like a native species, according to University of Stirling research.
Biologists at the Ruhr-Universität Bochum characterized new, unknown photoreceptors from the bioluminescent flashlight fish Anomalops katoptron. The photoreceptors known as opsins allow the fish to detect light with a specific wavelength. As published on the July 11, 2018, in PLOS ONE the scientists found new opsin variants, which are specialized to detect low intensity blue light in the wavelength range of bioluminescent light emitted by the fish. The blue light can be used to influence the fish behavior. | <urn:uuid:d2d1ccf2-95be-461a-bcf3-9fae01ecca10> | 2.96875 | 648 | Content Listing | Science & Tech. | 22.852346 | 95,583,397 |
About Catfish (Wels)
The Wels or Danubian catfish is the largest of the world’s 15 catfish families. In the wild it can reach a length of 14.7 feet (4.5m). This fish is an ugly fish with a long, tapering body and tiny, stunted tail. It’s head is huge and flattened. The mouth is large with strong rubbery lips and many small teeth. From the upper jaw there are two very long barbules and four smaller barbules that hang below the fish’s chin.
The Wels Catfish was introduced to Britain approximately 100 years ago, with the first fish being stocked into Woburn Abbey lakes by the then Duke of Bedford.
Wels lay eggs in the early spring, and the eggs are shed in weedbeds along the edge of the water.
It is a very active hunter. Much of its food consists of fish, but it will also take frogs, rats, small waterbirds and dead creatures. It is mainly a nocturnal species. This giant catfish spends most of the daylight hours in the dense weedbeds. Sometimes during hot, thundery weather it will indulge in a daylight feeding frenzy.
The color of the Wels Catfish is normally a dark, mottled brown with yellow blotched sides and yellow white underparts. Albino catfish also occur. | <urn:uuid:ec30c068-a4b8-406f-81a5-b6f61d38199e> | 3.125 | 290 | Knowledge Article | Science & Tech. | 72.01684 | 95,583,440 |
ann13085 — Mededeling
The Return of the Robot Rovers
Prototype European Mars rover visits Paranal
14 oktober 2013
In early October 2013, the Atacama Desert became the site of a Mars simulation for a week, as a team of scientists and engineers visited the area to test out their prototype Mars rover.
The test site is located close to ESO's Paranal Observatory and was selected due to its harsh climate and its physical resemblance to the red planet. Additionally, the Atacama Desert is known for its virtually sterile soil, largely due to the lack of moisture in the region: this makes the area particularly suitable for simulating the lifeless Martian environment.
The recent trials in Chile have featured a rover named Bridget (provided by Astrium, Stevenage in the UK), which is part of the SAFER field trials (Sample Acquisition Field Experiment with a Rover). ESA's 2018 ExoMars mission is acting as the reference mission for the trial.
The project aims to give the science team first-hand experience of remotely operating a rover, and acquiring field data from the three instruments during a field trial. The rover operation will be run so as to be as near to a real mission as possible for the science team and the remote control centre. Parallel testing is taking place from the UK's remote control centre based at the Satellite Applications Catapult Centre in Harwell.
The three instruments on trial are CLUPI (a close-up imager), which is the equivalent of a geologist's hand lens used for examining the fine details of rocks, a PanCam (panoramic camera) emulator called AUPE-2, and a ground penetrating radar called WISDOM, which will provide a detailed view of the Martian subsurface structure.
To further add to the realism of the simulated mission, the team also used an unmanned aerial vehicle (UAV or drone) to survey the area from the sky, providing a digital elevation model to assist the team with the rover's navigation. This is similar to the way in which data is acquired from Mars orbit.
It is not the first time that the harsh Chilean landscape has been used as a proving ground for Martian robotic explorers — an earlier rover visited Paranal in June 2012. And in June 2013 Carnegie Mellon University and the SETI (Search for Extraterrestrial Intelligence) Institute sent a solar-powered rover named Zoe to the region to test instruments used for the detection of microbes in extreme environments.
The SAFER field trial is being overseen by ESA's Directorate of Technical and Quality Management, with its international industrial team led by the UK Science and Technology Facilities Council's RAL Space. The team includes Astrium, Aberystwyth University, Scisys, Joanneum Research in Austria, Space Exploration Institute in Switzerland, the Mullard Space Science Laboratory of University College London, the University of Leicester, and the LATMOS research lab of the Centre National de la Recherche Scientifique in France.
The activity is being funded by ESA's Basic Technology Research Programme, with additional co-funding from the UK Space Agency.
Head of Communications, RAL Space
Rutherford Appleton Laboratory
Didcot, United Kingdom
Tel: +44 1 235 445 742
Cell: +44 783 763 4683
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Over de Mededeling | <urn:uuid:d77903bf-584f-4928-8b92-6a2ae1813949> | 3.09375 | 722 | News (Org.) | Science & Tech. | 23.512833 | 95,583,452 |
The positron is the antiparticle of the electron. The positron has the same mass as an electron, an electric charge of +1, and a spin of 1/2. When a low-energy positron collides with a low-energy electron, there is mutual annihilation, which results in the production of two gamma ray photons. Positrons can be generated by positron emission radioactive decay, or by pair production from a sufficiently energetic photon. The positrón was discovered by Carl David Anderson in 1932 when he studied the cosmic ray. | <urn:uuid:d99fde60-a559-4a95-b362-acb444fd5e81> | 3.734375 | 111 | Knowledge Article | Science & Tech. | 42.339517 | 95,583,477 |
P>1. A simulation study of the feedback of phytoplankton biomass on temperature stratification in the large, monomictic Lake Constance was undertaken. Phytoplankton biomass affects the light extinction coefficient (LEC) of the water and, in turn, the vertical distribution of short-wave radiation, which shapes the temperature stratification in the lake. 2. A sensitivity study of the variation in LEC using the hydrodynamic model DYRESM showed that a high LEC is associated with stronger stratification, shallower thermoclines, higher surface temperatures and reduced heat content during the heating phase of the lake. During the cooling phase, a shallower thermocline at high LEC leads to a faster decrease in water temperature so that during autumn, a high LEC is associated with lower surface temperatures. Thermal structure was particularly sensitive to changes in LEC when its value was below 0.5 m-1. 3. When LEC is simulated dynamically with the coupled hydrodynamic-ecological model DYRESM-CAEDYM, its value is a function of phytoplankton dynamics that change vertically and temporally. Comparing simulations with and without dynamic LEC (i.e. with and without phytoplankton dynamics) produced a complex picture: during the vegetation period, we often found a warmer surface layer and colder water beneath in the simulations with dynamic LEC, as expected from the higher LEC when phytoplankton is abundant. However, since phytoplankton biomass (as LEC) fluctuates and because of occasional cooling phases, the patterns were comparatively weak and not consistent over the whole growing season. 4. The most obvious patterns emerged by comparing simulations of oligotrophic and eutrophic conditions. In the eutrophic state, with its higher LEC, stratification was stronger and characterized by higher surface water temperatures, a shallower thermocline and colder water temperatures between 5 and 10 m depth. 5. Statistical analysis of long-term data of water temperatures in Lake Constance, corrected for external forcing by air temperature, revealed a significant tendency towards warmer temperatures at 7.5 and 10 m depths with decreasing LECs over the course of reoligotrophication. This finding is consistent with our model results.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:3ae02c0c-a9b6-4bf0-8d2b-0c6779a0e146> | 2.515625 | 499 | Academic Writing | Science & Tech. | 22.969934 | 95,583,507 |
Famous for his whale studies,
JGM (Hans) Thewissen turned his attention to bats as a postdoctoral fellow in 1984. His co-author, SK Babcock, was a graduate student at the time.
includes their intention of reviewing then current controversies despite “extremely sparse” fossil evidence. They mentioned the hundreds of Eocene bat skeletons known from the Messel quarry near Darmstadt, Germany, but note that even late Paleocene bats were “nearly as specialized as their modern relatives.” Their report preceded by several years the publication of Onychonycteris (Simmons, Seymour, Habersetze and Gunnell 2008), the most primitive bat known at present.
Two kinds of bats were noted, Megachiroptera and Microchiroptera.
“Megabats have a simple shoulder joint and a clawlike nail on thumb and index finger, whereas mi-crobats have a complicated shoulder joint and a claw only on the thumb.” Microbats use echolocation to eat insects with their sharp crested teeth. Megabats generally do not, but a few do. They are herbivores with blunt molars.
Earlier we looked at
the dual origins of turtles, whales, seals and the four origins of the “pterodactyloid”-grade pterosaurs. Workers have wondered if mega bats and micro bats also had dual origins. This was the main theme of the Thewissen and Babcock paper, penned before the widespread advent and adoption of computer-based phylogenetic analysis. Instead, everyone looked at a few to many traits and pulled a Larry Martin. Sometimes they were right. Othertimes, they were wrong to slightly wrong. Smith and Madkour 1980 first proposed a dual origin for bats by looking at the penis.
Thewissen and Bacock renege on their headline promise when they report,
“If the problem of bat origins is ever solved, it will be after a careful anal-ysis of all characterso f interesti n the bats and their potential relatives.” Of course this was shortly before PAUP and MacClade came on the scene the same year.
Thewissen and Babcock report:
“Both microbats and megabats have a propatagial muscle complex, but it is surprisingly different in the two groups.” In mega bats this complex has four proximal origins,
- the back of the skull
- the side of the face
- the ventral side of the neck and
- the midline of the chest
compared to only two origins in micro bats (1 and 4). There is also variation within micro bats and within mega bats. As readers know, there is no way to understand this unless outgroups have one or the other pattern and they don’t (at present). Thewissen and Babcock report, “gliding flight has evolved six times in mammals.” But gliders don’t make good flyers. To fly one needs thrust provided by flapping. How and why bats started flapping has really been the key underlying, unanswered question, which we looked at earlier here and here.
Back in 1910
WK Gregory concluded after careful study that bats, flying lemurs, tree shrews, elephant shrews and primates were closely related and called that group (clade) Archonta. According to the large reptile tree (LRT, 1043 taxa) many of these taxa are indeed related. Elephant shrews are not, which Thewissen and Babcock later note. Elephant shrews are also the only ones from that list that are not arboreal climbers. Thewissen and Babcock add the clade Plesiadapiformes, which were thought to be rodent-like primates, but turn out to be primate-like rodents nesting close to multituberculates in the LRT.
Figure 1. Bat cladogram. Here pangolins are the nearest living relatives of bats.
like Cynocephalus, also have a propatagium that originates from the side of the face and midline of the neck, but the nerves within them terminate in different places in bats. The LRT recovers flying lemurs close relatives to bats, but pangolins, like Manis, are closer.
Thewissen and Babcock conclude:
“We believe that the evidence from the propatagial muscle complex of bats supports the idea that all bats share a single ancestor with wings. This idea is consistent with bats going through a flying lemur-like stage before acquiring active flight.”
the LRT recovers a topology in which the last common ancestor of flying lemurs and bats was likely arboreal, but not a leaping glider. That means membranes developed in parallel (close convergence). Remember, gliders don’t become flappers. And flappers usually develop flapping for reasons other than flight, then co-opt flapping traits for flight.
The ancestors of bats and pangolins
have had a long time to diverge. Likely that was in the Late Jurassic because we have the pangolin ancestor, Zhangheotherium, appearing in the Early Cretaceous. That puts the last common ancestor of flying lemurs, pangolins and bats, Ptilocercus, back in the Middle Jurassic, several tens of millions of years after the likely first appearances of therian mammals, like the living and very late surviving Didelphis and Monodelphis sometime in the Early Jurassic. Earlier we looked at the origin of bats here, here and here.
Figure 2. Select basal cynodonts and mammals set chronologically. The divergence times for placentals (Eutheria), marsupials (Metatheria) and monotremes (Mammalia) are estimated here.
Simmon NB, Seymour KL, Habersetzer J, Gunnell GF 2008. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451 (7180): 818–21. doi:10.1038/nature06549. PMID 18270539.
Smith, J. D., and G. Madkour. 1980. Penial morphology and the question of chiropteran phylogeny. Pages 347-365 in D. E. Wilson and A. L. Gardner, eds. Proceedings of the 5th International Bat ResearchC onference. Texas Tech Press, Lubbock.
Thewissen JGM and Babcock SK 1992. The origin of flight in bats. BioScience 42(5):340–345. | <urn:uuid:da4cc0b4-8d26-470b-9e21-d7d6e44d7013> | 3.25 | 1,404 | Academic Writing | Science & Tech. | 49.095853 | 95,583,524 |
The report, to be published in the Feb. 15 issue of the journal Science, describes the series of observations that began March 28, 2006, when a collaboration known as Optical Gravitational Microlensing Equipment (OGLE) detected a signal, possibly due to a planet in microlensing event OGLE-2006-BLG-109, that the researchers had discovered and announced two days earlier.
After the OGLE group announced this possible detection of a planetary system via e-mail, other astronomers from the Microlensing Follow-Up Network (MicroFUN), Microlensing Observations in Astrophysics (MOA) and Probing Lensing Anomalies NETwork (PLANET) collaborations also began intensive, round-the-clock observations of this event. The combined data from these four groups revealed a series of brightness variations over the ensuing 11 days that indicated that two planets orbit a star half the mass of the sun located 5,000 light years from Earth. This star, called OGLE-2006-BLG-109L, and its planets were discovered using a technique known as gravitational microlensing.
Early calculations by the report’s lead author, Scott Gaudi of Ohio State University, and the MicroFUN group indicated that most of the telltale brightness variations were due to a planet with a mass similar to that of Saturn, but that there was a brief additional brightening observed from Israel and Chile that could only be explained by an additional planet with nearly the mass of Jupiter. However, Gaudi’s calculations did not provide a perfect fit to the data and involved several approximations.
Subsequently, Bennett performed more sophisticated calculations in his office at Notre Dame using his own advanced computer program that included an important additional feature: the orbital motion of the Saturn-mass planet.
“Even though we observed the micolensing effect of the Saturn for less than 0.3 percent of its orbit, the observations simply could not be explained without accounting for the orbit,” Bennett said.
Critical assistance with these calculations was provided by Sergei Nikolaev at Lawrence Livermore National Laboratory, who devoted much supercomputer time to the calculations.
The result was one of the most complicated calculations of a star-planet system using the gravitational microlensing method.
Gravitational microlensing takes advantage of the fact that light is bent as the rays pass close to a massive object, like a star. The gravity from the mass of the intervening object, or lens star, warps surrounding space and acts like a giant magnifying glass. As predicted by Albert Einstein and later confirmed, this phenomena causes an apparent brightening of the light from the background “source” star. The effect is seen only if the astronomer’s telescope lies in almost perfect alignment with the source star and the lens star. Astronomers are then able to detect planets orbiting the lens star if the light from the background star also is warped by the planets.
The discovery of the double planet system was a triumph for astronomers who use this method, which is of such high sensitivity that it can detect planets similar to those in our own solar system, with the exception of Mercury.
“These planets could not have been detected without any other technique,” Bennett said.
“The light curve of this event revealed an unprecedented amount of information about the planetary host star and the planets,” he continued.
The effect of the orbital motion of the Earth can be detected in the light curve, and this reveals that the mass of the host star is half the mass of the sun. This mass estimate was confirmed by subsequent observations of the planetary host star with the Keck telescope.
The light curve also reveals the orbital motion of the Saturn-mass planet during the 11 days when the planetary signal was visible.
To date, only 25 multiple planet systems have been observed. A majority are very dissimilar to our solar system and that of OGLE-2006-BLG-109L.
The Jupiter- and Saturn-sized planets orbiting OGLE-2006-BLG-109L are only the fifth and sixth planets that have been detected using the gravitational lensing method. Gaudi and Bennett conclude that if the OGLE-2006-BLG-109L planetary system is typical, then it is possible that they would have similar planets as our own solar system.
William Gilroy | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
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17.07.2018 | Power and Electrical Engineering | <urn:uuid:ede9ba94-0558-40a2-9753-74d2d6cbfb7b> | 3.59375 | 1,538 | Content Listing | Science & Tech. | 39.98705 | 95,583,525 |
Atoms and molecules are the basic building blocks of all “normal” matter in the universe. They make up everything from the simple chemical bonds of water to complex structures like humans. Atoms and molecules have different charges and configurations which create different structures with different properties.
An atom consists of a dense central nucleus that is surrounded by a “cloud” of negatively charged electrons. The nucleus contains positively charged protons and neutral neutrons. The electrons are bounded in the nucleus by an electromagnetic force. Atoms will group together by chemical bonds based on the force of the atoms to create chemical bonds.
Atoms will be positive, negative or neutrally charged based on the number of protons and electrons. If an atom is positive or negatively charged it is referred to as an ion. Atoms are classified based on the number of protons and neutrons in the nucleus. Atoms can be different sizes with respect to the number of proton, neutrons and electrons in the atomic configuration.
A molecule is an electrically neutral group of two or more atoms that are held together by covalent chemical bonds. Molecules are different from ions due to the neutral charge they maintain. Molecules, like atoms, can take on different sizes and configuration based on the type of atoms and the length of the bonds. Molecules are distinguished by their molecular formula, which is defined by the ratio of atoms involved in creating the molecule.© BrainMass Inc. brainmass.com July 19, 2018, 12:20 am ad1c9bdddf | <urn:uuid:34f3e457-6413-4507-a1ed-4eb2e8af3b36> | 4.28125 | 317 | Knowledge Article | Science & Tech. | 37.816154 | 95,583,536 |
A coordinate bond, also known as a dative covalent bond, is the linkage of two atoms by a pair of electrons, both electrons being provided by one of the atoms (the donor). The coordinate bond is formally identical with the covalent bond. An atom capable of accepting the electrons is the acceptor, the molecule donating the electrons is the donor or ligand. Coordinate linkages occur widely in inorganic complexes.
A coordination compound, also called a complex compound, is a type of chemical compound in which one or more groups or molecules each form a coordinate bond, usually a transition element. The complex may be either a complex ion or a neutral molecule, as in nickel carbonyl (Ni(CO)4). Some coordination compounds, such as heme and chlorophyll, have biological importance.
Chelation is a chemical reaction in which a certain type of organic compound, known as a chelating agent, combines with a metal ion by forming coordinate bonds with two or more atoms of the organic compound. Examples of chelating agents include tartaric acid (CHOHCOOH)2 and ethylenediamine (CH2NH2)2.
The coordination number is the number of chemical bonds made to a central number in a specified complex salt, such as the number of anions (negative ions) surrounding a cation (positive ion). | <urn:uuid:eb712da4-e618-405a-aec4-08abd67468c8> | 3.875 | 283 | Knowledge Article | Science & Tech. | 31.053571 | 95,583,570 |
29 December 2014 | 2014 was a big year for species conservation. Although controversial, several new approaches to conservation were put into practice this year as the US Fish and Wildlife Service (FWS) made significant listing decisions under the Endangered Species Act. Plus, the voluntary initiatives to conserve endangered and at-risk species continues to evolve as does the debate over their effectiveness. Needless to say, 2014 was a busy year for FWS regulators, conservation bankers and western landowners and developers.
Choosing whether to list or not list the lesser prairie chicken was a big story of 2013 and continued to make headlines well into 2014. The bird’s habitat doubles as prime land for energy development meaning a threatened or endangered listing status would impact the multiple economic activities occurring in the area. The potential consequences of a listing decision spurred landowners and energy interests into action developing voluntary programs intended to conserve the prairie chicken and restore its population without a federal listing.
These programs, in turn, spurred controversy as environmentalists argued the conservation methods they used lacked the rigor of compliance. Several conservation bankers, in particular, came out against the plans claiming they undermined bank business while leaving the species in peril.
In the end, the bird’s rapidly declining population spoke for itself. In late March, the FWS listed the prairie chicken as threatened under the ESA albeit with some exceptions. Farmers, ranchers and other land-users who had voluntary conservation measures approved were exempt from ESA regulations.
Because of these new and somewhat unusual approaches, prairie chicken conservation has big implications for the future of species conservation and is an issue that will undoubtedly unfold more in 2015.
However, the prairie chicken wasn’t the only bird making headlines in 2014. The greater sage-grouse, hailing from the same family as the prairie chicken and containing many of the same problems, is a candidate species with dwindling and fragmented habitat in the western US. And like the prairie chicken, the possibility of an ESA listing had environmentalists, landowners and energy developers scrambling to protect it.
The environmental NGO, Environmental Defense Fund, has developed a habitat exchange for the sage grouse. And two of the 11 states the bird resides in have developed conservation plans. Also this year, the FWS presented its range-wide compensatory mitigation framework for the greater sage-grouse to guide the states in implementing meaningful conservation.
The Service must make a listing decision on the sage-grouse by September 30, 2015. But recently, Congress threw a wrench into the process. In its latest spending bill, representatives didn’t allocate any funds towards listing the bird.
But while this provision is seemingly bad news for the grouse, some environmentalists are viewing it with cautious optimism. They say it gives them time to demonstrate how well the voluntary initiatives, many of them already up and running, can work. The FWS also noted the spending bill provision doesn’t affect conservation plans at state and local levels.
The Big Conference
Species conservation was also a big topic at this year’s National Mitigation and Ecosystem Banking Conference (NMEBC) that was set in Denver. Lesser prairie chicken and greater sage grouse conservation dominated an entire session with in-depth presentations on specific plans and cases.
The NMEBC was far more diverse this year than last and thus, much more engaging. It was wide-ranching in terms of discussing pertinent issues facing the industry today. The conference covered the ongoing debate between the government run habitat conservation plans and conservation banking as well as water rights for wetland banking in the US west. There was also a lot of focus on the Department of Interior’s new mitigation strategy and how that would affect banking.
Good or Bad News for Unlisted Species?
Perhaps one of the biggest announcements to come out of this year’s conference was the possibility of a crediting system for unlisted species created by the FWS and administered at state level. The Service released a draft policy over the summer that began an open comment period that ran throughout the fall.
While feelings were somewhat mixed, some from the banking world took issue with another voluntary initiative. Wayne White, the President of the National Mitigation Banking Association (NMBA) argued because the program’s standards for conservation are lower, the cost to conserve is lower also which then doesn’t provide proper conservation for the species and undermines the true cost of mitigation.
But White, like others, sees potential in a program recognizing conservation credits for unlisted species. But it must be done right, says Timothy Male of Mission: Wildlife.
It’s definitely a topic to follow in 2015. Now that the public comment period is over, the FWS will look to incorporate those comments into the proposal as well as make other revisions before making it final.
On the international policy front, Spain’s new Environmental Assessment Act, passed late in 2013, has big implications for conservation banking. Early in the year, David íƒâ€šlvarez García of the Spanish organization Mercados de Medio Ambiente, which focuses on market based biodiversity conservation solutions, discussed his take on the new rule.
A Year for Events
2014 was a big year for events. Peru’s hosting of the year-end climate talks spurred much talk on the state of biodiversity in the country. Peru is one of the most biologically diverse places on Earth.
And in June, the Business and Biodiversity Offsets Programme (BBOP) hosted the “To No Net Loss of Biodiversity and Beyond”summit at the London Zoo.
The event brought together professionals from a multitude of sectors that included energy, finance, nonprofit and government in an effort to demonstrate a no net loss of biodiversity-and a net gain even-in the face of development. The event was a big success and was livestreamed to accommodate all those expressing interest.
Harmonizing the Agenda
It was also a big year for integration in terms of integrating global biodiversity targets into other parts of the global agenda. The year’s events indicate this. The United Nation’s climate conference took notice of the linkages between biodiversity and climate with an event and declaration. The declaration called for more integrative research on biodiversity and climate change while the event presented on current knowledge.
Two months before these climate talks, the UN’s Convention on Biological Diversity’s (CBD) 12th Conference of Parties (COP 12) took place in Pyeongchang, South Korea. The theme of this year’s conference was Biodiversity for Sustainable Development. A huge topic of discussion was ensuring integration of biodiversity into the UN’s post 2015 Sustainable Development Goals (SDGs). As negotiations over these goals restart next year in January, this is another issue to follow in 2015.
And like at the climate talks, cross-sector collaboration was brought up during sessions at COP 12. One such session, focused on finance, discussed the emerging links between sustainable forest management and biodiversity conservation.
A guidebook was also released this year that explores these synergies though it’s specifically looking at reducing emissions from deforestation and forest degradation (REDD). A Sourcebook: Biodiversity Monitoring for REDD+ offers a four-stage framework that begins by explaining the objectives of monitoring biodiversity for REDD+, then identifies specific indicators that can be used. After that, it progresses into implementation and communication to relevant audiences.
More to Come
Other topics of 2014 surfaced as significant stories as well. The basic unawareness of biodiversity offsets-unless it’s under attack- among consumers is one. It’s a big problem, according to a researcher on the subject who says growth and regulatory support depends on public opinion.
Another issue needing to be addressed is the difference in cost between mitigation and the federal fine when failing to mitigate a development impact properly.
Most of these issues are unresolved or continuing to develop and will be making headlines in 2015. | <urn:uuid:a6b68ca6-55c7-436e-b4f2-4d7b88449fd3> | 2.59375 | 1,640 | Knowledge Article | Science & Tech. | 30.372427 | 95,583,578 |
Reindeer, from Northern Europe or Asia, are often thought of as a domesticated animal, one that may pull Santa's sled. Caribou, similar in appearance but living in the wilderness of North America, are thought of as conducting an untamed and adventurous life.
However, new research published in the journal Nature Climate Change suggests that there are more similarities about these two animals than previously thought and change in climate played a role in their evolution.
A group of 21 researchers from two continents, including Marco Musiani of the University of Calgary, looked closely at the DNA of reindeer in Scandinavia and Asia as well as tundra and woodland caribou in North America to find out more about how their environments were affected in the past and will be influenced in the future by climate change.
As one of the most northern species, caribou will feel the effects of global warming, says Musiani, a professor in the faculties of Environmental Design and Veterinary Medicine and co-author of the study.
"The woodland caribou is already an endangered species in southern Canada and the United States. The warming of the planet means the disappearance of their critical habitat in these regions. Caribou need undisturbed lichen-rich environments and these types of habitats are disappearing," said Musiani, noting that the study projected how the environment will change by the year 2080.
Musiani said the research demonstrates that the animals are not as different from a genetic point of view as some might think given the geographic spread of reindeer and caribou. The two sister groups occur throughout Europe, Asia and North America, from Norway to Eastern Canada.
Researchers found that caribou living in North America, but just south of the continental ice became isolated and evolved their unique characteristics during the last glaciation. At that point, Europe, Asia and Alaska were connected by a land bridge; reindeer occurred there and also evolved separately.
"Then, at meltdown the two groups, reindeer from the North and caribou from the South, reunited and interbred in areas previously glaciated such as the southern Canadian Rockies," says Musiani.
The researchers looked at how the animals were distributed over 21,000 years as the climate changed and at present and found that caribou in Alaska and northern Canada are strikingly similar to reindeer. More typical North American caribou occur only in the lowland forested regions further south."Animals more closely related to reindeer occur in North America, throughout its northern and western regions, with some transitional zones, such as the one remarkably placed in the southern Canadian Rockies," said Musiani.
Musiani is available for interviews on request.
Stephane Massinon | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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When a proton – the bare nucleus of a hydrogen atom – transfers from one molecule to another, or moves within a molecule, the result is a hydrogen bond, in which the proton and another atom like nitrogen or oxygen share electrons. Conventional wisdom has it that proton transfers can only happen using hydrogen bonds as conduits, "proton wires" of hydrogen-bonded networks that can connect and reconnect to alter molecular properties.
Uracil is one of the four bases of RNA (carbon atoms are brown, nitrogen purple, oxygen red, hydrogen white). Because methyl groups discourage hydrogen bonding, methylated uracil should be incapable of proton transfer. But after ionization of methylated uracil dimers, a proton moves by a different route, from one monomer to the other. Credit: Lawrence Berkeley National Laboratory, University of Southern California
Hydrogen bonds are found everywhere in chemistry and biology and are critical in DNA and RNA, where they bond the base pairs that encode genes and map protein structures. Recently a team of researchers using the Advanced Light Source (ALS) at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) discovered to their surprise that in special cases protons can find ways to transfer even when hydrogen bonds are blocked. The team's results appear in Nature Chemistry.
Stacking the odd molecules
A group led by Musahid Ahmed, a senior scientists in Berkeley Lab's Chemical Sciences Division (CSD), has long collaborated with a theoretical research group at the University of Southern California (USC) headed by Anna Krylov. In recent work to understand how bases are bonded in staircase-like molecules like DNA and RNA, Krylov's group made computer models of paired, ring-shaped uracil molecules, and investigated what might happen to these doubled forms (dimers) when they were subjected to ionization – the removal of one or more electrons with resulting net positive charge.
Uracil is one of the four nucleobases of RNA, whose structure is similar to DNA except that, while both use the bases adenine, cytosine, and guanine, in DNA the fourth base is thymine and in RNA it's uracil. The USC group used a uracil dimer labeled 1,3-dimethyluracil – "a strange creature that doesn't necessarily exist in nature," says CSD's Amir Golan, who led the Berkeley Lab team at the ALS. The purpose of this strange creature, Golan says, is to block hydrogen bonding of the two identical monomers of the uracil dimer by attaching a methyl group to each, "because methyl groups are poison to hydrogen bonds."
The uracils could still bond in the vertical direction by means of pi bonds, which are perpendicular to the usual plane of bonding among the flat rings of uracil and other nucleobases. "Pi stacking" is important in the configuration of DNA and RNA, in protein folding, and in other chemical structures as well, and pi stacking was what interested the USC researchers. They brought their theoretical calculations to Berkeley Lab for experimental testing at the ALS's Chemical Dynamics beamline 9.0.2.
To examine how the molecules were bonded, Golan and his colleagues first created a gaseous molecular beam of real methylated uracil monomers and dimers, then ionized them with a beam of energetic ultraviolet light from the ALS synchrotron. The resulting species were weighed in a mass spectrometer to see how the uracil had responded to the extra boost of energy.
"Uracils could be joined by hydrogen bonds or by pi bonds, but these uracils had been methylated to block hydrogen bonds. So what we expected to see when we ionized them was that if they were bonded, they would have to be stacked on top of each other," Golan says. Instead of holding together by pi bonds, however, when ionized some uracil dimers had fallen apart into monomers that carried an extra proton.
Where the protons come from
"What we did not expect to see was proton transfer," Golan says. "Surprising as this was, we needed to find where the protons were coming from. The methyl groups consist of a single carbon atom and three hydrogen atoms, but methylated uracil has other hydrogens too. Still, the methyl groups were the natural suspects."
To test this hypothesis, the researchers invited colleagues from Berkeley Lab's Molecular Foundry to join the collaboration. They created methyl groups in which the hydrogen atoms – which like most hydrogen had single protons as their nuclei – were replaced by deuterium atoms, "heavy hydrogen" atoms with nuclei consisting of a proton and a neutron of virtually the same mass.
The molecular beam experiment was repeated at the ALS, and once again some of the methylated uracil dimers fell apart into monomers upon ionization. This time, however, the tell-tale monomers were not simply protonated, they were deuterated.
Says Golan, "By looking at the mass of the fragments we could see that instead of uracil plus one" – the mass of a single proton – "they were uracil plus two" – a proton and neutron, or deuteron. "This proved that indeed the transferred protons came from the methyl groups."
The experiment showed that proton transfer in this case followed a very different route from the usual process of hydrogen bonding. Here the transfer involved not just an attraction between molecular arrangements that were slightly positively charged and others that were slightly negatively charged, as in a hydrogen bond. Instead it required significant rearrangements of the two uracil dimer fragments, to allow protons of hydrogen atoms in the methyl group on one monomer to move closer to an oxygen atom in the other. Theoretical calculations of the new pathway were led by USC's Krylov and Ksenia Bravaya.
The moral of the story, says Golan, is that methyl groups do not always kill proton transfer. "Granted, this was a model system – what we did was ionize the uracil systems in the gas phase instead of in solution, as would be the case in a living organism," he says. "Nevertheless, we showed that proton transfer is possible without hydrogen-bonding networks. Which means there could be unsuspected pathways for proton transfer in RNA and DNA and other biological processes – especially those that involve pi-stacking – as well as in environmental chemistry and in purely chemical processes like catalysis."
The next step: a range of new experiments to directly map proton transfer rates and gain structural insight into the transfer mechanism, with the goal of visualizing these unexpected new pathways for proton transfer.
"Ionization of dimethyluracil dimers leads to facile proton transfer in the absence of H-bonds," by Amir Golan, Ksenia B. Bravaya, Romas Kudirka, Oleg Kostko, Stephen R. Leone, Anna I. Krylov, and Musahid Ahmed, is published by Nature Chemistry and appears in advance online publication at http://www.nature.com/nchem/index.html. Golan, Kostko, Leone, and Ahmed are with Berkeley Lab's Chemical Sciences Division, and Golan and Leone are also with the Departments of Chemistry and Physics at the University of California at Berkeley. Bravaya and Krylov are with the University of Southern California. Kudirka is with Berkeley Lab's Materials Sciences Division. This work was supported principally by the U.S. Department of Energy's Office of Science, and by the Department of Defense and the National Science Foundation.
For more about the Chemical Dynamics Beamline at the ALS, visit www.chemicaldynamics.lbl.gov.
For more about Anna Krylov's research, visit iopenshell.usc.edu/krylovgroup/.
The Advanced Light Source is a third-generation synchrotron light source producing light in the x-ray region of the spectrum that is a billion times brighter than the sun. A DOE national user facility, the ALS attracts scientists from around the world and supports its users in doing outstanding science in a safe environment. For more information visit www-als.lbl.gov/.
The Molecular Foundry is one of five DOE Nanoscale Science Research Centers (NSRCs), national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize, and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. For more information about the DOE NSRCs, please visit science.energy.gov.
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, please visit the Office of Science website at science.energy.gov/.
Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit www.lbl.gov.
Paul Preuss | EurekAlert!
Further reports about: > Advanced Investigator Grant > CHEMISTRY > Chemical Sciences > DNA > Materials Science > Molecular Target > Nature Immunology > RNA > Science TV > biological process > chemical engineering > chemical process > chemical structure > computer model > hydrogen atom > hydrogen bonding > hydrogen bonds > methyl group > protein structure > single proton > specimen processing
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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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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Last year, a Long March 2D rocket took off from the Jiuquan Satellite Launch Centre in the Gobi Desert carrying a satellite called Micius, named after an ancient Chinese philosopher who died in 391 B.C. The rocket placed Micius in a Sun-synchronous orbit so that it passes over the same point on Earth at the same time each day. Micius is a highly sensitive photon receiver that can detect the quantum states of single photons fired from the ground. That’s important because it should allow scientists to test the technological building blocks for various quantum feats such as entanglement, cryptography, and teleportation.
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Unexpected and conflicting results from research around irrigation practices and their influence on greenhouse gas emissions have Lincoln University PhD student Jen Owens contemplating a more complex scenario and a few possible explanations.
Ms Owens carried out a field experiment on a commercial dairy farm measuring nitrous oxide emissions and soil oxygen concentrations under urine patches subjected to varying rates of irrigation. Her studies are integrated with a three-year research programme by Landcare Research into greenhouse gas emissions from intensive dairying.
Nitrous oxide is a potent greenhouse gas linked to climate change. Most of New Zealand’s nitrous oxide emissions come from grazed pastures where soil is affected by nitrogen inputs such as ruminant urine. Nitrous oxide emissions from urine patches are a problem for New Zealand given the intensification of dairying.
“While many dairy farms are using irrigation to improve pasture production to meet the nutritional needs of their cows, little is known about what happens to the nitrous oxide emissions from urine patches when they are irrigated,” says Ms Owens.
Her field experiment explored the possibility that irrigation may modify soil oxygen concentrations, potentially reducing nitrous oxide emissions from urine patches. She found that soil oxygen concentrations under a more frequently irrigated urine patch were lower when compared to a less frequent irrigation regime.
These lower soil oxygen concentrations were expected to lead to lower nitrous oxide emissions. However, this didn’t happen, suggesting a more complex scenario.
“Nitrous oxide emissions were not affected by irrigation frequency but we were surprised to find the more frequent irrigation rate lead to potentially greater nitrous oxide uptake by microbes. These two results appear to conflict with each other.”
A possible explanation for this is that the potential for the production of nitrous oxide has increased in response to lower soil oxygen, as well as the potential for soil microbes to consume nitrous oxide. So in effect we are measuring the net effect of these two processes.”
Based on the results from the study, Ms Owens has performed a number of smaller experiments under controlled conditions to better understand how soil biology is driven by the soil’s physical status.
“These experiments have helped us interpret how irrigation influences nitrous oxide emissions from urine patches.
“We’ve also started looking at urine patch induced nitrous oxide emissions on other soil types and during different times of the year, winter instead of summer, to validate and further explore the impact of soil oxygen concentrations.”
Ms Owens’ research is being funded by Landcare Research. | <urn:uuid:82de0093-493e-4fbb-8f06-765515c7d145> | 3.046875 | 515 | Academic Writing | Science & Tech. | 18.900321 | 95,583,653 |
In continuum mechanics the macroscopic velocity, also flow velocity in fluid dynamics or drift velocity in electromagnetism, is a vector field used to mathematically describe the motion of a continuum. The length of the flow velocity vector is the flow speed and is a scalar.
The flow velocity u of a fluid is a vector field
The flow speed q is the length of the flow velocity vector
and is a scalar field.
The flow velocity of a fluid effectively describes everything about the motion of a fluid. Many physical properties of a fluid can be expressed mathematically in terms of the flow velocity. Some common examples follow:
The flow of a fluid is said to be steady if does not vary with time. That is if
If a fluid is incompressible the divergence of is zero:
That is, if is a solenoidal vector field.
A flow is irrotational if the curl of is zero:
That is, if is an irrotational vector field.
A flow in a simply-connected domain which is irrotational can be described as a potential flow, through the use of a velocity potential with If the flow is both irrotational and incompressible, the Laplacian of the velocity potential must be zero:
The vorticity, , of a flow can be defined in terms of its flow velocity by
Thus in irrotational flow the vorticity is zero.
The velocity potential
- Velocity gradient
- Velocity potential
- Drift velocity
- Group velocity
- Particle velocity
- Strain rate
- Stream function
- Pressure gradient
- Duderstadt, James J.; Martin, William R. (1979). "Chapter 4:The derivation of continuum description from transport equations". In Wiley-Interscience Publications. Transport theory. New York. p. 218. ISBN 978-0471044925.
- Freidberg, Jeffrey P. (2008). "Chapter 10:A self-consistent two-fluid model". In Cambridge University Press. Plasma Physics and Fusion Energy (1 ed.). Cambridge. p. 225. ISBN 978-0521733175.
- Courant, R.; Friedrichs, K.O. (1999) [unabridged republication of the original edition of 1948]. Supersonic Flow and Shock Waves. Applied mathematical sciences (5th ed.). Springer-Verlag New York Inc. p. 24. ISBN 0387902325. OCLC 44071435. | <urn:uuid:70dcce68-ba8a-4721-bba9-080958195571> | 3.53125 | 518 | Knowledge Article | Science & Tech. | 55.987306 | 95,583,657 |
Comparison of muonated free radicals formed in pure liquids with those in dilute solutions: Origins of radicals
LCR spectroscopy was used to explore the mechanism by which muonated free radicals form in unsaturated organic liquids. This was achieved by comparing the relative yields of the different radicals formed from the compound as a pure liquid with those found when it was studied as a solute in dilute aqueous micelle solutions. In the latter medium, thermalized muonium atoms are the only precursors. Two types of examples were evaluated: first, styrene and allylbenzene since they give a full range of side-chain and ring addition products: and second, methyl acrylate and acrylonitrile since the former alone shows conformational s-cis-trans isomerism. Both types of process were expected to be particularly sensitive to the nature and charge of the reactive species involved. The results suggest that neutral muonium is the dominant precursor in all these liquids, with ‘hot’ muonium perhaps contributing about 30% of the radicals.
KeywordsThin Film Styrene Acrylate Full Range Reactive Species
Unable to display preview. Download preview PDF.
- (a)R.F. Kiefl,Hyp. Int., 32 (1986) 707.Google Scholar
- E. Roduner,The Positive Moun as a Probe in Free Radical Chemistry, Springer Series in Chemical Physics, No 49 (Springer, Berlin, 1988).Google Scholar
- M. V. Barnabas, K. Venkateswaran and D.C. walker, J. Amer. Chem. Soc., (in press).Google Scholar | <urn:uuid:a07bf151-a15d-409f-8929-a5165ba69acb> | 2.546875 | 354 | Academic Writing | Science & Tech. | 45.103153 | 95,583,658 |
To make a tally chart, single lines are drawn next to one another until reaching five, where the fifth line crosses the four other lines diagonally. This is a simple charting method that can be used quickly for surveys or other needs.
A:A linear inequality is similar to a linear equation; however, where a linear equation has an equals sign, a linear inequality uses an inequality symbol. Inequality symbols include > (greater than), < (less than), ≤ (less than or equal to), ≥ (greater than or equal to) and ≠ (not equal to).
A:Math is important in life for its practical, everyday applications like cooking and baking, financing a home and providing the right tip at a restaurant. It is also used by professionals to solve problems.
A:A kilogram is approximately 2.20 pounds. The kilogram is the base unit the metric system uses for mass. Beginning in July 1959, the internationally accepted standard for the avoirdupois pound became exactly 0.45359237 kg.
A:People use algebra in their daily lives when they make decisions about health, fitness, financial and money matters and when cooking. Algebra involves the use of known variables and fixed numbers in equations to find the values of unknown numbers.
A:Some things that come in groups of seven include the days of the week, the books in the Harry Potter series, the notes in a typically major or minor scale, the games in the playoff series for Major League Baseball and the Pillars of the House of Wisdom in the Book of Proverbs. Other groups of seven include the number of heavens in Islam and the chakras in Hinduism.
A:According to Saint Louis University, the ancient Egyptians created the square root and most likely used it for architecture, building pyramids and other daily activities that required math. Most of the present-day knowledge of Egyptian math comes from papyri written during the 12th dynasty.
A:The basic parts of a multiplication problem consist of at least two factors that are multiplied together to result in one product. More than two factors can be involved in a multiplication problem, but the answer always consists of only one product.
A:A factor is a number or expression that divides another number or expression evenly without a remainder. For instance, two, four, five and 10 are factors of 20 because 20 can be divided by all those smaller numbers an exact number of times. Prime numbers are positive integers greater than one that have exactly two factors. A composite number has more than two factors.
A:A Pythagorean triple is a set of three positive integers, (a, b, c), such that a right triangle can be formed with the legs a and b and the hypotenuse c. The most common Pythagorean triples are (3, 4, 5), (5, 12, 13), (8, 15, 17) and (7, 24, 25).
A:A nonlinear function in math creates a graph that is not a straight line, according to Columbia University. Three nonlinear functions commonly used in business applications include exponential functions, parabolic functions and demand functions. Quadratic functions are common nonlinear equations that form parabolas on a two-dimensional graph.
A:A few examples of how logarithms are used in the real world include measuring the magnitude of earthquakes or the intensity of sound and determining acidity. A logarithm explains how many times a number is multiplied to a power to reach another number. It is expressed as loge(x) and is commonly written as ln(x).
A:A Riemann sum is a method of approximating the area under the curve of a function. It adds together a series of values taken at different points of that function and multiplies them by the intervals between points. The midpoint Riemann sum uses the x-value in the middle of each of the intervals.
A:According to class notes from Bunker Hill Community College, calculus is often used in medicine in the field of pharmacology to determine the best dosage of a drug that is administered and its rate of dissolving. Usually, the drug is slowly dissolved in the stomach.
A:A line graph is a graph that charts the relationship between two variables or a progression of a single quantity through time. Without the lines connecting points of data, it would be difficult to make sense of the data being presented if there was no overall trend between the dots. A bar graph, on the other hand, is meant to compare two or more statistics, such as population figures.
A:Several types of graphs are used for displaying information in mathematics including the bar graph; pie chart or circle graph; histogram; stem and leaf plot; dot plot; scatter plot; and time-series graphs. The type of graph chosen depends on whether the data is quantitative, qualitative or paired.
A:Graphs are beneficial because they summarize and display information in a manner that is easy for most people to comprehend. Graphs are used in many academic disciplines, including math, hard sciences and social sciences. They make appearances in corporate settings, serving as useful tools to convey financial information and facilitate data analysis.
A:The primary advantage of using a graph or chart in a presentation is that they help the audience to visualize the point of the presentation. Graphs emphasize the main point, make the data more convincing, provide a compact way of presenting information and help audiences stay engaged. Disadvantages of graphs include being time consuming to construct and costly to produce. They also require technology that some may lack.
A:A pie graph is an effective visual tool used for showing how something breaks into parts. A pie graph is essentially a circle sliced into 100 pieces. Each category or part represented in the pie graph is given a piece of the pie to represent the percentage that it comprises of the whole. | <urn:uuid:85bee169-6836-4869-817c-2f0cb27028b2> | 3.984375 | 1,210 | Content Listing | Science & Tech. | 43.729734 | 95,583,674 |
Antarctica: Soon to be snowy no more?
For quite a while, there has been great concern over the consequences of global warming. There are reports of the Arctic ice caps melting faster than they should, tornadoes and other weather-related disasters happening more recently, and of the coral reefs dying out and turning a bland shade of white due to the unfavorable conditions.
Environmental activists such as David Suzuki are doing their best to inform the world of the trouble the human race is doing to the Earth, though their efforts are only so effective.
As a result of their inability to communicate their message effectively enough, or perhaps as a consequence of our inability to change our environmental flaws, it was found to rain in the Arctic, despite its stereotypically snowy climate. Though this may seem insignificant, massive ice melt events have become more and more common.
For instance, in 2016, a significant portion of the Ross Ice Shelf melted over a period of 15 days. During this period, 300,000 square miles of ice melted into the sea. Over time, these melts could cause rising ocean levels, in turn leading to low-lying towns and cities being flooded.
Antarctic expert David Bromwich mentions that the never-before-seen rain offers “a possible glimpse of the future.” Even though the ice is slowly melting today, the resulting warm water will eat through the remaining ice shelves. This domino effect would make once-solid ice shelves become much more unstable and all the more likely to melt into the ocean.
El Niño To Blame?
A theory as to why the rain appeared is that an El Niño happened, which traditionally brings warmth to the area. The event brings warm, moist air from the ocean and transports it to the Ross Ice Shelf among other parts of Antarctica. Perhaps the most shocking consequence of this event is that it causes rain in a desert–that’s right, Antarctica is a desert.
The major loss of Antarctica’s ice is expected to result in as much as 4 feet in sea level increase, which would cause great floods across the world.
However, there is a sliver of hope in this madness. There is still time, albeit very little, for us to change our ways of saving the Earth. If that doesn’t happen, perhaps the more maniacal person would enjoy the other solution: wiping the human race off the planet completely. It has been estimated that within 23 days, the Earth would restore itself to a balanced state. | <urn:uuid:5e37d6da-a3e7-400e-8be5-17bff6673b95> | 3.734375 | 511 | Personal Blog | Science & Tech. | 48.223873 | 95,583,705 |
Sample of question (Please refer to attached PDF document for full details):
We have at our disposal an amount of energy equaling 3.5kJ and we wish to allocate 1 mole of gas which occupies volume V.© BrainMass Inc. brainmass.com July 16, 2018, 6:53 am ad1c9bdddf
In A) you made mistake in the first part. The internal energy for a diatomic molecule near or below room temperature is
5/2 N k T = 5/2 n R T.
This is because the molecule has besides kinetic energy also internal energy in the form of rotational energy. In a purely classical approach, it should also have vibrational energy, but that contribution is frozen at and below room temperatures. You can see this as follows. You can count the degrees of freedom for the molecule in two ways. Any possible motion of the molecule, can always be described as the motion of the two atoms separately. Then because each atom has 3 degrees of freedom (each atom can move in 3 independent directions), the total number of degrees of freedom is 6. Now these 6 degrees of freedom can also be accounted of by consideing that the two atoms form a molecule and then considering the possible degrees of freedom for the molecule.
The center of mass of the molecule has 3 degrees of freedom.
There are 2 independent ways to choose a rotation axis for the molecule ...
We explain why the internal energy of a gas of diatomic moleculs is 5/2 N k T near or below room temperature and we explain the derivation of the formula for the Fermi energy of an electron gas. | <urn:uuid:1182f35d-a708-4fc3-8fa6-0ec214761553> | 3.21875 | 338 | Q&A Forum | Science & Tech. | 57.748852 | 95,583,707 |
Species Detail - Chlorociboria aeruginosa - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Chlorosplenium discoideum, Peziza aeruginosa
(Vahl) Seaver ex C.S. Ramamurthi, Korf & L.R. Batra
25 May (recorded in 2013)
14 September (recorded in 1957)
National Biodiversity Data Centre, Ireland, Chlorociboria aeruginosa, accessed 16 July 2018, <https://maps.biodiversityireland.ie/Species/157785> | <urn:uuid:68aaa3a5-8131-40a0-8d9b-5a56130beb42> | 2.546875 | 179 | Structured Data | Science & Tech. | 36.428661 | 95,583,709 |
The double bond of cycloartenol (compound 7 in diagram) is methylated by SAM to give a carbocation that undergoes a hydride shift and loses a proton to yield a compound with a methylene side-chain. Both of these steps are catalyzed by sterol C-24 methyltransferase (Step E1 in diagram). Compound 8 is then catalyzed by sterol C-4 demethylase (E2) and loses a methyl group to produce cycloeucalenol. Subsequent to this, the cyclopropane ring is opened with cycloeucalenol cycloisomerase (E3) to form 10 . Compound 10 loses a methyl group and undergoes an allylic isomerization to form Gramisterol 11 . This step is catalyzed by sterol C-14 demethylase (E4), sterol Δ14-reductase (E5), and sterol Δ8-Δ7-isomerase (E6). The last methyl group is removed by sterol demethylase (E7) to form episterol 12 . Episterol 12 is methylated by SAM to produce a second carbocation, which loses a proton to yield 13 . This step is catalyzed by 24-methylenesterol C-methyltransferase (E8). Compound 13 now undergoes reduction by NADPH and modifications in the β-ring to form β-sitosterol. | <urn:uuid:cd7959d6-71b5-4efb-8e9f-225f3be42d06> | 2.5625 | 303 | Knowledge Article | Science & Tech. | 42.381483 | 95,583,719 |
ARI has partnered with Dr. Aleck Wang of the Woods Hole Oceanographic Institution to monitor water quality parameters in the East Channel of the Mackenzie River Delta near the town of Inuvik.
The goal of this monitoring program is to take time-series measurements of the carbon system in the Mackenzie River, a major Arctic river in the western Canadian Arctic. This work is a first step towards long-term measurements and studies of the impacts of global warming on the carbon system in the Mackenzie River, its estuary, and adjacent coastal waters.
Technicians from ARI collect a bottle of water once per month and treat the sample with mercuric chloride. Water salinity, temperature, and depth are measured in-situ at the sampling site. Water samples are then filtered and collected into glass bottles, and shipped to Woods Hole Oceanographic Institution for further analysis. At the Woods Hole lab, pH and alkalinity are measured along with a variety of carbon parameters, including partial pressure of CO2 and total dissolved inorganic carbon.
ARI has partnered with Dr. Christopher Burn from Carleton University to monitor permafrost in the Mackenzie Delta region of the western Canadian Arctic.
The objective of this monitoring program is to understand how climate change is affecting permafrost in the western Arctic. The ice content of permafrost terrain affects its stability, and as ice melts this can result in damage to infrastructure and changes to the landscape. For instance, as permafrost melts, roads and water ways may experience slumping along their borders, and buildings built on pilings may start to tilt.
For many years, Dr. Burn has studied changes in permafrost stability and ground temperature at various locations in the western Arctic, ranging from Herschel Island on the Yukon North Slope, through the Mackenzie Delta, to Paulatuk on the Arctic Ocean coast of the NWT. At each site, ground temperature sensors are installed in steel pipes and the ground temperatures are measured and recorded several times each year.
Once a month, ARI technicians visit two different sites near Inuvik and record ground temperatures. One site is near the Inuvik airport and the other is at NRC Lake in the Mackenzie Delta.
AIR QUALITY MONITORING
ARI has partnered with the GNWT Department of Environment and Natural Resources (ENR) to maintain an Air Quality Station in Inuvik.
Air is one of our most precious resources, and is vital to life on earth. Maintaining good air quality in the NWT is an important factor in environmental protection and the protection of human health. Sources of air pollution that affect our air quality are both natural, such as emissions from forest fires, and anthropogenic (man-made), such as industrial, vehicular, and home heating emissions. The pollutants monitored at the Inuvik Air Quality Station include carbon monoxide, particulate matter of various sizes, ozone, sulfate, and nitrogen-containing gases.
ENR generally regulates air quality activities on NWT Commissioner’s Land under the Environmental Protection Act. In Inuvik, ARI provides maintenance, quality control checks and calibration of instruments for the Inuvik Air Quality Station.
If you have any questions about ARI environmental monitoring programs, please email us at firstname.lastname@example.org. | <urn:uuid:30de3607-f33f-456a-acd9-584269d37dd1> | 2.984375 | 681 | Knowledge Article | Science & Tech. | 30.791074 | 95,583,739 |
Viruses propagate by infecting a host cell and reproducing inside. This not only affects humans and animals, but bacteria as well. This type of virus is called bacteriophage. They carry so called auxiliary metabolic genes in their genome, which are responsible for producing certain proteins that give the virus an advantage. Researchers at the University of Kaiserslautern and the Ruhr University Bochum have analysed the structure of such a protein more closely. It appears to stimulate the photosynthesis of host bacteria. The study has now been published in the prestigious journal ‘The Journal of Biological Chemistry’.
When viruses infect a cell, they use it as a factory to replicate themselves. “They abuse the bacteria to produce new virus proteins,” says microbiology professor Dr Nicole Frankenberg-Dinkel, from the TU Kaiserslautern. “This creates new viruses that are assembled in the host cell.”
The association between the virus protein and bacterial pigment is incredibly stable. Furthermore, the complex is highly fluorescent.
Credits: AG Frankenberg-Dinkel
Bacteriophages also carry what are known as auxiliary metabolic genes in their DNA. “These are responsible for producing various proteins. They appear to give the virus an advantage, for instance, by stimulating the host cell`s metabolism,” adds professor Dr Eckhard Hofmann, who leads the protein crystallography group at the Ruhr University Bochum.
In this study, the researchers concentrated on bacteriophages that infect blue-green algae, also known as cyanobacteria. Their work focused on a certain protein, whose structure they analysed more closely. “Our findings indicate that it plays an important role in the assembly of light-harvesting complexes in host bacteria,” explains Frankenberg-Dinkel.
These complexes allow the microorganisms to harvest the energy of sunlight. Just like plants, they conduct photosynthesis – using light energy to convert carbon dioxide and water into carbohydrates and oxygen. “These light-harvesting complexes consist of proteins and coloured pigments,” the Kaiserslautern professor continues. In the case of blue-green algae, a pink coloured pigment (phycoerythrobilin) is particularly important.
Frankenberg-Dinkel and Hofmann’s team has proved that the virus protein (‘phycobiliprotein lyase CpeT’) binds the coloured pigment. Moreover, the team determined that the association between the virus protein and bacterial pigment is incredibly stable. “By looking under the microscope, we have also seen that the complex is highly fluorescent,” Frankenberg-Dinkel states.
The results of the study show that the viral protein stimulates the assembly of light-harvesting complexes. “This gives the virus an evolutionary advantage,” Frankenberg-Dinkel says. “They ensure a high rate of photosynthesis in the bacteria during infection, meaning sufficient energy is available for the production of new viruses.”
This mechanism is widespread among viruses that infect blue-green algae. However, further studies will have to clarify why the genome of the viruses only contains certain auxiliary metabolic genes. Bacteriophages are among the most prevalent biological entities on earth. They are not considered living creatures. Scientists have discovered many new bacteriophages in recent years. Researching them will provide important clues to their biological function.
The study has now been published in the scientific journal ‘The Journal of Biological Chemistry’ as the title article: ‘Distinct Features of Cyanophage-encoded T-type Phycobiliprotein Lyase CpeT’
Prof Dr Nicole Frankenberg-Dinkel
University of Kaiserslautern
Tel.: +49 (0)631 205-2353
Prof Dr Eckhard Hofmann
Ruhr University Bochum
Tel.: +49 (0)234 32-24463
Katrin Müller | Technische Universität Kaiserslautern
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
Biological signalling processes in intelligent materials
18.07.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
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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Strain can be used to engineer unusual properties at the nanoscale. Researchers in Tobias Kippenberg's lab at EPFL have harnessed this effect to engineer an extremely low loss nanostring. When plucked, the string vibrates for minutes with a period of a microsecond (equivalent to a standard guitar note playing for a month). Using it as an ultrasensitive microphone, the researchers hope to be able to "hear" the sound of photons in a laser beam. The work is published in Science.
A lesson in stress management
For a mechanical engineer, stress is usually a nuisance. Properly managed, however, it can also be a powerful tool: An elastic body responds to stress by adjusting the distance between its atoms (strain), which can be used to control the properties of its electrons. One example of such "elastic strain engineering" is the modern transistor, whose operating speed is enhanced by stressing its silicon gate material.
Stress can also be used to engineer the properties of an elastic body. Stretching a guitar string, for example, will change not only its sound (its vibrational frequency), but also its quality factor (the number of vibrations produced by a single pluck). This effect, known as "dissipation dilution," in undesirable in many musical circles, but in other fields can be a tremendous advantage.
Bigger is not always better
One such field is nanomechanics, where the quality factor an oscillator dictates its utility for applications such as force sensing. Over the last decade, strained nanomechanical oscillators have emerged as an important paradigm owing to their anomalously high quality factors; however, this trend is not as much a design choice as an artifact of large stresses naturally produced at the nanoscale.
Armed with a powerful set of tools at EPFL's Center of MicroNanoTechnology, researchers in Kippenberg's lab set about engineering nanomechanical devices with deliberately enhanced stress and dissipation dilution. They found that a string is an ideal geometry for this, although its motion must be localized away from its supports and co-localized with its internal stress profile.
To meet these requirements, the researchers patterned the string into a periodic structure in which vibrations could be trapped around a central defect: a phononic crystal. To co-localize strain, the defect is carefully tapered, and the entire pattern is printed onto a string of roughly 10 nm thick and 1 cm long (the equivalent of stretching the Golden Gate bridge across the Pacific ocean).
Measurements made on nanostring devices at room temperature reveal localized modes that vibrate at 1 MHz for tens of minutes, corresponding to a quality factor of 800 million. Transposed onto a standard guitar string, an equivalent "note" would play for a month.
Listening to light
By dint of their small mass and extreme quality factors, nanostrings similar to those developed in the Kippenberg lab are expected to have an important impact on traditional sensing applications. Operated as force sensors, for example, they are capable of detecting local disturbances at the level of attonewtons, equivalent to the gravitational pull between human beings.
One intriguing application is to detect weak light forces. By coupling a nanostring to an optical waveguide, Kippenberg's lab recently demonstrated the ability to "hear" the gentle sound of photons flowing in a laser beam (each imparting a tiny radiation pressure force to the string). In a surprising twist, they showed how this measurement could be used to generate a nonclassical state of light known as squeezed light, which can be used to enhance the sensitivity of an optical interferometer.
They are now asking a different question: is it possible to use the same light field to "see" the vacuum fluctuations of the nanostring (a consequence of its phonon¬-like nature)? "Heisenberg's uncertainty principle predicts that the two capabilities are commensurate," says Dalziel Wilson, one of the paper's authors. "Operating at this so-called standard quantum limit offers the possibility of cooling a tangibly-sized mechanical object from room temperature to absoluate zero (its motional ground state), the starting point for myriad quantum experiments."
A. H. Ghadimi, S. A Fedorov, N. J. Engelsen, M. J. Bereyhi, R. Schilling, D. J. Wilson, T. J. Kippenberg. Elastic Strain Engineering for Ultra-Low Mechanical Dissipation. Science (12 April 2018) DOI: 10.1126/science.aar6939 | <urn:uuid:69f57ea6-13f0-437a-8660-cb54497629fe> | 3.71875 | 952 | Knowledge Article | Science & Tech. | 35.889219 | 95,583,775 |
Chapter 2 of Automating Excel
The first question that any VBA beginner needs answering is - how do I access the data stored in the spreadsheet. The answer is easy, but it introduces ideas of objects and their properties and methods. This is where the real programming starts.
- Chapter 1 - Getting started with Excel VBA
- Chapter 2 - Getting at the Data
Getting at the Data
When you discover how easy VBA is to use you really want to rush on ahead and start doing something with it.
The trouble is that there seems to be a mystery barrier between VBA and the application that you are working with - Excel in this case.
It seems easy enough to add a module to a workbook (see the first part of this series - Getting started with Excel VBA ) and enter lines of VBA code that do something but how do you get at the data that is stored in a worksheet?
In normal spreadsheet use getting at the data is the most trivial of operations - you just point at it or you write a formula that references it.
entered into a cell tells the spreadsheet to add the data in cell A1 to the data in cell A2.
Most VBA users initially think that this sort of formula must be the way to get at worksheet data within a VBA program - it isn’t.
When they find out how it is done the usual reaction is to complain about how silly it is not to use the spreadsheet way of working. The reason for this apparent attempt at making things more difficult is that VBA is not a programming language designed for spreadsheets.
In principle you can use VBA with any type of application and the technique for getting at the data within that application remains the same. So we sacrifice simplicity for generality - but it isn’t that difficult, honest!
Step One - A single cell the hard way!
It is a good idea to start off by looking at the way that you can refer to the data stored in an individual cell. Be warned that this is the full unexpurgated version, there are simpler ways to write this.
For example, if you want to get the value stored in cell A1 you might write
temp= Application.Workbooks("Book1"). _
Well I told you it was long!
However if you think of it as a sort of “address” that works by moving from the more general to the more specific you should be able to follow what is going on.
Each part of the “address” is separated from the rest by a dot and you read it from left to right as usual. The Application part just means the Excel program itself.
A running copy of Excel can have a number of Workbooks open and so Workbooks(“Book1”) picks out the one called “Book1”.
Each Workbook is made up of a number of sheets and Worksheets(“Sheet1”) picks out the one called “Sheet1”.
Finally Range(“A1”) picks out the cell within the sheet that we are looking for.
The cell has a number of possible properties that we might be interested in - colour, height, width etc. - and so we also need Value to indicate that it is the value stored in it we want.
In practice we usually don’t need to quote a “full address” in this way to get at the data stored in a cell but you need to be aware how it appears it in its entirety and understand the principles.
If you would like to try this instruction out then open Excel and get to the VBA editor. Then use the Insert Module command and enter the lines:
temp = Application. _
Make sure that there is something stored in cell A1 and run this subroutine. You should see a message box appear displaying the correct value.
You might be wondering what the underscore at the end of some of the lines is all about.
temp = Application. _
The simple answer is that if you need to split a single command over more than one line you need to break the line with a space and then an underscore. This is the "continuation" character indicating that the instruction goes onto the next line.
Sometimes it is good to break lines in this way so that the meaning becomes clear.
Step Two - Objects and propertiesThis long address approach to specifying that you want to access the data in cell A1 may seem to be unreasonable but it fits in with the general approach of VBA and most modern programming languages.
The idea is that there are things called “objects” and an object can have properties.
For example, a spreadsheet cell is an object and one of its properties is its value. That is Range(“A1”) specifies the cell object at A1 and Range(“A1”).Value gives you its value property.
This sounds OK but how does it result in the long string of names and dots that we encountered above?
The answer is that objects are allowed to have other objects as properties.
Sounds complicated and to be honest you don’t have to think about it in this way if you don’t want to - but it is the right way to do it.
For example, the Application object can have a number of workbook objects among its properties, which in turn have worksheet objects and each of these have a collection of cell objects.
You can think of this as an object “hierarchy” - application at the top, then workbook, then worksheet, then a cell range and so on..
Using VBA to control applications such as Excel is very much a matter of learning what objects there are and how they are arranged.
You will also discover that the VBA language includes an “object browser” that allows you to look at the hierarchy and select objects from it. For example, if you start the browser by pressing F2 you can look at Worksheet and discover that it has a Range property.
We will return to the object browser later.
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Calorimeters and Calorimetry
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Calorimetry is the science associated with determining the changes in energy of a system by measuring the heat exchanged with the surroundings. Now that sounds very textbooky; but in this last part of Lesson 2, we are going to try to make some meaning of this definition of calorimetry. In physics class (and for some, in chemistry class), calorimetry labs are frequently performed in order to determine the heat of reaction or the heat of fusion or the heat of dissolution or even the specific heat capacity of a metal. These types of labs are rather popular because the equipment is relatively inexpensive and the measurements are usually straightforward. In such labs, a calorimeter is used. A calorimeter is a device used to measure the quantity of heat transferred to or from an object. Most students likely do not remember using such a fancy piece of equipment known as a calorimeter. Fear not; the reason for the lack of memory is not a sign of early Alzheimer's. Rather, it is because the calorimeter used in high school science labs is more commonly referred to as a Styrofoam cup. It is a coffee cup calorimeter - usually filled with water. The more sophisticated cases include a lid on the cup with an inserted thermometer and maybe even a stirrer.
Coffee Cup Calorimetry
So how can such simple equipment be used to measure the quantity of heat gained or lost by a system? We have learned on the previous page, that water will change its temperature when it gains or loses energy. And in fact, the quantity of energy gained or lost is given by the equation
Q = mwater•Cwater•ΔTwater
where Cwater is 4.18 J/g/°C. So if the mass of water and the temperature change of the water in the coffee cup calorimeter can be measured, the quantity of energy gained or lost by the water can be calculated.
The assumption behind the science of calorimetry is that the energy gained or lost by the water is equal to the energy lost or gained by the object under study. So if an attempt is being made to determine the specific heat of fusion of ice using a coffee cup calorimeter, then the assumption is that the energy gained by the ice when melting is equal to the energy lost by the surrounding water. It is assumed that there is a heat exchange between the iceand the water in the cup and that no other objects are involved in the heat exchanged. This statement could be placed in equation form as
Qice = - Qsurroundings = -Qcalorimeter
The role of the Styrofoam in a coffee cup calorimeter is that it reduces the amount of heat exchange between the water in the coffee cup and the surrounding air. The value of a lid on the coffee cup is that it also reduces the amount of heat exchange between the water and the surrounding air. The more that these other heat exchanges are reduced, the more true that the above mathematical equation will be. Any error analysis of a calorimetry experiment must take into consideration the flow of heat from system to calorimeter to other parts of the surroundings. And any design of a calorimeter experiment must give attention to reducing the exchanges of heat between the calorimeter contents and the surroundings.
The coffee cup calorimeters used in high school science labs provides students with a worthwhile exercise in calorimetry. But at the professional level, a cheap Styrofoam cup and a thermometer isn't going to assist a commercial food manufacturer in determining the Calorie content of their products. For situations in which exactness and accuracy is at stake, a more expensive calorimeter is needed. Chemists often use a device known as a bomb calorimeter to measure the heat exchanges associated with chemical reactions, especially combustion reactions. Having little to nothing to do with bombs of the military variety, a bomb calorimeter includes a reaction chamber where the reaction (usually a combustion reaction) takes place. The reaction chamber is a strong vessel that can withstand the intense pressure of heated gases with exploding. The chamber is typically filled with mostly oxygen gas and the fuel. An electrical circuit is wired into the chamber in order to electrically ignite the contents in order to perform a study of the heat released upon combustion. The reaction chamber is surrounded by a jacket of water with a thermometer inserted. The heat released from the chamber warms the water-filled jacket, allowing a scientist to determine the quantity of energy released by the reaction.
Solving Calorimetry Problems
Now let's look at a few examples of how a coffee cup calorimeter can be used as a tool to answer some typical lab questions. The next three examples are all based on laboratory experiments involving calorimetry.
Example Problem 1:
A physics class has been assigned the task of determining an experimental value for the heat of fusion of ice. Anna Litical and Noah Formula dry and mass out 25.8-gram of ice and place it into a coffee cup with 100.0 g of water at 35.4°C. They place a lid on the coffee cup and insert a thermometer. After several minutes, the ice has completely melted and the water temperature has lowered to 18.1°C. What is their experimental value for the specific heat of fusion of ice?
The basis for the solution to this problem is the recognition that the quantity of energy lost by the water when cooling is equal to the quantity of energy required to melt the ice. In equation form, this could be stated as
Qice = -Qcalorimeter
(The negative sign indicates that the ice is gaining energy and the water in the calorimeter is losing energy.) Here the calorimeter (as in the Qcalorimeterterm) is considered to be the water in the coffee cup. Since the mass of this water and its temperature change are known, the value of Qcalorimeter can be determined.
Qcalorimeter = m•C•ΔT
Qcalorimeter = (100.0 g)•(4.18 J/g/°C)•(18.1°C - 35.4°C)
Qcalorimeter = -7231.4 J
The negative sign indicates that the water lost energy. The assumption is that this energy lost by the water is equal to the quantity of energy gained by the ice. So Qice = +7231.4 J. (The positive sign indicates an energy gain.) This value can be used with the equation from the previous page to determine the heat of fusion of the ice.
Qice = mice•ΔHfusion-ice
+7231.4 J = (25.8 g)•ΔHfusion-ice
ΔHfusion-ice = (+7231.4 J)/(25.8 g)
ΔHfusion-ice = 280.28 J/g
ΔHfusion-ice = 2.80x102 J/g (rounded to two significant figures)
Example Problem 2:
A chemistry student dissolves 4.51 grams of sodium hydroxide in 100.0 mL of water at 19.5°C (in a calorimeter cup). As the sodium hydroxide dissolves, the temperature of the surrounding water increases to 31.7°C. Determine the heat of solution of the sodium hydroxide in J/g.
Once more, the solution to this problem is based on the recognition that the quantity of energy released when sodium hydroxide dissolves is equal to the quantity of energy absorbed by the water in the calorimeter. In equation form, this could be stated as
QNaOH dissolving = -Qcalorimeter
(The negative sign indicates that the NaOH is losing energy and the water in the calorimeter is gaining energy.) Since the mass and temperature change of the water have been measured, the energy gained by the water (calorimeter) can be determined.
Qcalorimeter = m•C•ΔT
Qcalorimeter = (100.0 g)•(4.18 J/g/°C)•(31.7°C - 19.5°C)
Qcalorimeter = 5099.6 J
The assumption is that this energy gained by the water is equal to the quantity of energy released by the sodium hydroxide when dissolving. So QNaOH-dissolving = -5099.6 J. (The negative sign indicates an energy lost.) This quantity is the amount of heat released when dissolving 4.51 grams of the sodium hydroxide. When the heat of solution is determined on a per gram basis, this 5099.6 J of energy must be divided by the mass of sodium hydroxide that is being dissolved.
ΔHsolution = QNaOH-dissolving / mNaOH
ΔHsolution = (-5099.6 J) / (4.51 g)
ΔHsolution = -1130.7 J/g
ΔHsolution = -1.13x103 J/g (rounded to three significant figures)
Example Problem 3:
A large paraffin candle has a mass of 96.83 gram. A metal cup with 100.0 mL of water at 16.2°C absorbs the heat from the burning candle and increases its temperature to 35.7°C. Once the burning is ceased, the temperature of the water was 35.7°C and the paraffin had a mass of 96.14 gram. Determine the heat of combustion of paraffin in kJ/gram. GIVEN: density of water = 1.0 g/mL.
As is always the case, calorimetry is based on the assumption that all the heat lost by the system is gained by the surroundings. It is assumed that the surroundings is the water that undergoes the temperature change. In equation form, it could be stated that
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A vacuum-sealed miniature X-ray tube based on carbon nanotube field emitters
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A vacuum-sealed miniature X-ray tube based on a carbon nanotube field-emission electron source has been demonstrated. The diameter of the X-ray tube is 10 mm; the total length of the tube is 50 mm, and no external vacuum pump is required for the operation. The maximum tube voltage reaches up to 70 kV, and the X-ray tube generates intense X-rays with the air kerma strength of 108 Gy·cm2 min−1. In addition, X-rays produced from the miniature X-ray tube have a comparatively uniform spatial dose distribution.
KeywordsInsertion Position Braze Process Electron Beam Size Spatial Dose Distribution Alumina Ceramic Tube
A miniature X-ray tube is a small X-ray generation device generally with a diameter of less than 10 mm [1, 2, 3, 4, 5]. Because of the feasible installation in a spatially constrained area and the possibility of electrical on/off control, miniature X-ray tubes can be widely used for nondestructive X-ray radiography, handheld X-ray spectrometers [1, 2], electric brachytherapy, and interstitial or intracavitary radiation therapy or imaging with the substitution of radioactive isotopes [3, 4, 5]. Miniature X-ray tubes have been developed mostly using thermionic electron sources [3, 4] or secondary X-ray emission .
Meanwhile, X-ray tubes based on carbon nanotube (CNT) field-emission electron sources have been extensively developed because CNT emitters have several advantages compared with thermionic electron sources. The advantages of CNT emitters include (1) cold electron sources, and hence, little heat is generated inside the tube which is important for the minimization of an X-ray tube; (2) simplicity and easy controllability in a pulse operation [7, 8]; (3) high current density for electron and X-ray microscopy devices [9, 10]. Several types of X-ray tubes have also been developed using CNT field emitters [11, 12, 13, 14, 15]. However, the miniature X-ray tubes are mostly not vacuum-sealed and thus should be operated in a vacuum chamber or with a vacuum pump. In addition, the maximum operating voltages of the miniature X-ray tubes were less than 30 kV. As a consequence, the X-ray tubes have limited practical applications.
In this paper, we report that we have developed a vacuum-sealed miniature X-ray tube using a CNT field emitter. The miniature X-ray tube can be operated up to 70 kV and produces X-rays with very high intensities and a comparatively uniform spatial distribution.
Fabrication of the miniature X-ray tube
Figure 1c,d show a photograph and an X-ray radiograph (XR) of the fabricated miniature X-ray tube, which show the exterior and the interior of the tube, respectively. The diameter of the X-ray tube is 10 mm, and the total length is 50 mm. The weight of the tube is only 14.5 g. All of the connection parts of the X-ray tube are tightly vacuum-sealed. The both ends of the alumina ceramic tube were vacuum-brazed with a focusing electrode assembly and a connecting anode, respectively. Both electrodes were made of Kovar (Carpenter Technology Corporation, Reading, PA, USA) that has a similar thermal expansion coefficient to alumina. The connecting anode was used to interconnect a ceramic tube and a Be X-ray window that have different thermal expansion coefficients. The connecting anode and the Be window were also vacuum-brazed. All the components of the X-ray tube were baked at 550°C for 10 h, and subsequently, these were brazed through a single-step brazing process at 680°C for 30 min in a vacuum furnace. Before the brazing process, electron emission and transport tests of the X-ray tube have been carried out inside a vacuum chamber. The position of the cathode inside the focusing electrode could be finely controlled through this process. A non-evaporable getter film was installed around the focusing electrode to evacuate the X-ray tube. The getter was activated during the brazing process. The outer part of the sealed X-ray tube, except the target, was covered with a layer of silicone resin to improve high-voltage insulation between the cathode and the X-ray target. We observed that the fabricated X-ray tube was stably operated up to 70 kV without any high-voltage breakdown or discharge at both the inner vacuum side and the outer air side.
Results and discussion
Performance and characterization of the X-ray tube
Figure 2b shows the dose rate of X-ray that is produced from the miniature X-ray tube and the stability of the dose rate with time. The dose rate was measured with an ionization chamber and an electrometer (PTW 34013 and Unidos-E both from PTW, Freiburg, Germany) at 1 cm apart from the X-ray tube in air. The air kerma strength of the X-ray tube operating at 50 kV with the tube current of 252 μA was as high as 108.1 Gy·cm2 min−1, which is approximately 15 times higher than that of a 10-Ci HDR 192Ir radioisotope source that is widely used for brachytherapy. The fluctuation of the X-ray dose rate was as low as ±2.7%. In addition, the X-ray tube has worked for over 2 months with no significant change in the electron beam current (0.25 mA at 50 kV) and the X-ray dose rate. The X-ray tube has been continuously operated for approximately 1 h/day. Consequently, the developed miniature X-ray tube produces high enough X-ray output and exhibits very good short-term and long-term stabilities.
To further evaluate the performance of the miniature X-ray tube, the X-ray focal spot size was measured following the European standard EN 12543–5. An XR image of a copperplate (thickness 0.1 mm) was taken with a magnification factor of 1.25 (Figure 4b). The image profiles in both the horizontal and vertical directions were analyzed, and from the analysis, the X-ray focal spot size was calculated to be 3.72 mm in the horizontal direction and 3.64 mm in the vertical direction. The focal spot size of the X-ray corresponds to the electron beam size at the X-ray target. Therefore, the measurement results for the X-ray focal spot size suggest that the inner diameter (7 mm) of the present miniature X-ray tube can be reduced, and accordingly, the X-ray tube can be further minimized.
In summary, we have demonstrated a vacuum-sealed miniature X-ray tube based on CNT field-emission electron source. The X-ray tube can be operated up to 70 kV, and high-dose X-rays are generated with a comparatively good spatial dose distribution. Due to the small electron beam size in the X-ray tube, the prototype X-ray tube can be further miniaturized. We believe that such a vacuum-sealed miniature X-ray tube can be used for various industrial and medical diagnostic/therapy purposes.
SHH has a Ph.D. in Nuclear Engineering and is a president of a ventured company. HJK and JMH are MS students. SOC is a professor of Nuclear Engineering.
This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2011–0018418) and the R&D Program of MKE/KEIT (10035553).
- 17.Herrmannsfeldt WB, Herrmannsfeldt GA: EGN Electron Optics Program. California: SLAC, Stanford; 1993.Google Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. | <urn:uuid:47df5b1b-16c0-443f-86a7-12cf81cd22d3> | 2.9375 | 1,772 | Academic Writing | Science & Tech. | 49.763396 | 95,583,826 |
A comet is a clump of frozen gases mixed with dust. These "dirty snowballs" cast off gas and dust whenever they venture near the sun. What powers this activity is frozen water transforming from solid ice to gas, a process called sublimation. Jets powered by ice sublimation release dust, which reflects sunlight and brightens the comet. Typically, a comet's water content remains frozen until it comes within about three times Earth's distance to the sun, or 3 astronomical units (AU), so astronomers regard this as the solar system's "snow line."
"Comet Garradd was producing lots of dust and gas well before it reached the snow line, which tells us that the activity was powered by something other than water ice," said Dennis Bodewits, an assistant research scientist at the University of Maryland, College Park, and the study's lead investigator. "We plan to use Swift's unique capabilities to monitor Garradd as it moves beyond the snow line, where few comets are studied."
Comets are known to contain other frozen gases, such as carbon monoxide and dioxide (CO and CO2), which sublimate at colder temperatures and much farther from the sun. These are two of the leading candidates for driving cometary activity beyond the snow line, but phase transitions between different forms of water ice also may come into play.
C/2009 P1 was discovered by Gordon J. Garradd at Siding Spring Observatory, Australia, in August 2009. Astronomers say that the comet is "dynamically new," meaning that this is likely its first trip through the inner solar system since it arrived in the Oort cloud, the cometary cold-storage zone located thousands of AU beyond the sun.
Comet Garradd was closest to the sun on Dec. 23, 2011, and passed within 118 million miles (1.27 AU) of Earth on March 5, 2012. The comet remains observable in small telescopes this month as it moves south though the constellations Ursa Major and Lynx.
Although Swift's prime task is to detect and rapidly locate gamma-ray bursts in the distant universe, novel targets of opportunity allow the mission to show off its versatility. One of Swift's instruments, the Ultraviolet/Optical Telescope (UVOT) is ideally suited for studying comets.
The instrument includes a prism-like device called a grism, which separates incoming light by its wavelength. While Swift's UVOT cannot detect water directly, the molecule quickly breaks up into hydrogen atoms and hydroxyl (OH) molecules when exposed to ultraviolet sunlight. The UVOT detects light emitted by hydroxyl and other important molecular fragments — such as cyanide (CN), carbon monosulfide (CS) and diatomic and triatomic carbon (C2 and C3, respectively) — as well as the sunlight reflected off of cometary dust.
"Tracking the comet's water and dust production and watching its chemistry change as it moves deeper into the solar system will help us better understand how comets work and where they formed," said Stefan Immler, a researcher and Swift team member at NASA's Goddard Space Flight Center in Greenbelt, Md.
Swift last observed the comet on April 1, when it was 1.53 AU away and just past the orbit of Mars. Although detailed results are not yet available, Bodewits estimates that Comet Garradd was shedding about 400 gallons of water each second -- enough to fill an Olympic-size swimming pool in under 30 minutes.
But the water given off by the comet was only about half of the dust mass it produced. Bodewits estimates that each second, Garradd was losing about 7,500 pounds (3.5 metric tons, or about twice the typical mass of a small car) in the form of dust and icy grains.
Thanks to Garradd's brightness and the UVOT's sensitivity and resolution, researchers can monitor the comet when it is beyond the grasp of most ground-based observatories. Plans call for observations at eight different distances from the sun out to about 5.5 AU, which the comet will reach in April 2013.Francis Reddy
Francis Reddy | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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In this interactive object, the learner practices identifying charges on ions.
Shapes of Simple Molecules - Part 1
By Dr. Miriam Douglass, Dr. Martin McClinton
In this animated and interactive object, learners observe how two, three, or four groups of electrons around the central atom cause the shape of the molecule to be linear, trigonal planar, bent, tetrahedral, or pyramidal. Seven examples and eight interactive questions are provided.
Calculation of Atomic Weight from Isotopic Composition
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Learners examine the method for calculating the atomic weight of copper from the natural percent composition of each of its two isotopes.
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Learners calculate gas density from the standard molar volume and observe how the density increases with the increasing molecular weight of the gas.
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Using an Indicator
By Janet Braun, Barbara Anderegg
Students read about the basics of using an indicator.
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Use Ohm's law, Watt's law, and the power equation to derive formulas for the DC power wheel.
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In this learning activity you'll calculate problems using the negative both inside and outside of the parenthesis.
Multiplying and Dividing Signed Numbers
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Students read the rules used in multiplying and dividing signed numbers. They view examples and work practice problems.
Multiplication of a String of Signed Numbers
Students read how to organize their work when multiplying more than two signed numbers. A review and practice problems complete the activity.
Basics and formulas for Spreadsheets
Creative Commons Attribution-NonCommercial 4.0 International License.
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In many species, the male’s fortunes in the mating stakes are decided by a conspicuous breeding dress. A study of brightly coloured fish has now demonstrated that this has less to do with aesthetics than with the sensitivity of female eyes, which varies as a result of adaptation to the environment.
Females more attuned to blue will choose a metallic blue mate, while those better able to see red will prefer a bright red male. These mating preferences can be strong enough to drive the formation of new species – provided that habitat diversity is not reduced by human activities.
The role of selection in the formation of new species has yet to be fully explained in evolutionary biology. The development of brightly coloured cichlid species in African lakes within only a few thousand years – a brief period on the evolutionary timescale – supports the hypothesis that mating preferences may contribute to speciation, without populations being geographically isolated from each other. In the case of cichlids, it has been suggested that selection is attributable to differences in colour perception. Compelling evidence for this theory has now been provided for the first time in a study just published in the journal Nature.
Seeing and being seen
In the study, evolutionary biologist Ole Seehausen (Eawag and Bern University) and his co-authors demonstrate that female cichlids from Lake Victoria whose eyes are more sensitive to blue tend to prefer blue-coloured males, while females with photoreceptors better able to detect red light choose males with red nuptial coloration. The different visual receptor pigments were distinguished by the team on the basis of DNA and protein sequences. The DNA sequence of the genes underlying the visual pigments also shows that specialization did not occur by chance but was in turn due to natural selection. Colour sensitivity differs according to the water depth at which the fish are found. Females living in deeper water are more sensitive to red, and those in shallower water are more sensitive to blue. The adaptation of visual receptors to the prevailing ambient light colour confers an advantage on fish in a certain depth range. They are better able to navigate and, for example, will find more food than non-adapted fish. At the same time, the males have evidently also adapted to this situation: males with a red breeding dress predominate in deeper water, while blue-coloured males are dominant in shallower water.
Two species are formed when ambient light changes only gradually with increasing water depth, a condition given in relatively clear waters. This means that there is sufficient room for the different genetic variants to exploit the competitive advantage conferred by their visual specialization and colour in their particular niche.
Reasons for dramatic decline of species
Besides demonstrating one way in which new species can be formed, the latest findings provide a mechanistic explanation for the dramatic loss of species diversity that has occurred in Lake Victoria over the past 25 years. Eutrophication of the lake due to agricultural runoff, deforestation and urbanization has substantially increased the turbidity of the water. As a result, ambient light changes dramatically within only a few metres of the water column. Accordingly, the different ecological niches are now so small and so close together that the mechanism of genetic adaptation can no longer operate. Thus, the authors found that at sites with turbid water, rather than separate red and blue species, an intermediate form predominated, not specifically adapted to either of the light niches. It is very likely that merging of species, driven by environmental changes, has contributed significantly to the decline of cichlid species diversity in Lake Victoria from more than 500 to the present total of around 250 species within merely 25 cichlid generations.
Box: What is a species?
Various concepts of a species are found in evolutionary biology. What all have in common is that populations of organisms are assigned to different species if they coexist in nature over many generations in the same site without genetically merging. Numerous species hybridize occasionally but remain differentiated if mechanisms exist to restrict gene flow. The definition of a species as a group of individuals not capable of interbreeding with members of other species is a popular misconception.
Andri Bryner | alfa
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
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Plant mothers talk to their embryos via the hormone auxin
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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In the wake of last month's meteor strike in Russia and a close asteroid flyby on the same day, members of Congress asked NASA, White House and Air Force officials what they're doing to combat the threat of near-Earth asteroids during a hearing today on Capitol Hill.
By and large, the experts stressed that the two space rock events were a coincidence and that the chance of a catastrophic asteroid impact to Earth any time soon is remote. On Feb. 15, a surprise meteor exploded in the sky over Russia's Ural Mountains, just hours before the 150-foot-wide (40 meters) asteroid 2012 DA14 flew close by Earth in a pass that had been predicted beforehand by scientists.
"The odds of a near-Earth object strike causing massive causalities and destruction of infrastructure are very small, but the potential consequences of such an event are so large that it makes sense to take the risk seriously," John Holdren, science advisor to President Barack Obama, told the Science, Space and Technology Committee of the U.S. House of Representatives.
Still, Rep. Lamar Smith (R-Texas), chairman of the Science, Space and Technology Committee, said it was "not reassuring" to learn that NASA has so far detected only about 10% of the near-Earth objects that are wider than 87 miles (140 kilometers) across. Holdren estimated that there may be hundreds of thousands of such objects within one-third the distance from Earth to the sun that remain unknown.
In 2005, Congress directed NASA to detect, track and characterize 90% of these space rocks —those near-Earth asteroids larger than 87 miles (140 m). The space agency's chief, Charles Bolden, said today that NASA was unlikely to meet that deadline given its current budget.
"Our estimate right now is at the present budget levels it will be 2030 before we're able to reach the 90% level as prescribed by Congress," Bolden said.
Bolden criticized the lawmakers for slowing NASA down through budget cuts. "You all told us to do something, and between the administration and the Congress, the bottom line is the funding did not come," Bolden said.
Furthermore, he said the goal of finding a way to respond to asteroid threats has been repeatedly put off by lawmakers who cite a lack of money.
Rep. Bill Posey (R-Fla.) asked what NASA would do if a large asteroid headed on a collision course with Earth was discovered today with only three weeks before impact.
"The answer to you is, 'if it's coming in three weeks, pray,'" Bolden said. "The reason I can't do anything in the next three weeks is because for decades we have put it off."
Budget concerns also hamper the military's ability to monitor near-Earth objects and other space threats, such as orbital debris (defunct satellites and spent rocket stages that litter Earth orbit).
"We are clearly less capable under sequestration," Gen. William Shelton, the current commander of the U.S. Air Force Space Command, told the committee. He said that any further budget cuts could have dire consequences.
"Our dependence on space, not only for our way of life but also for military operations, is very high, so we would sacrifice that," Shelton said.
Image via Chip Somodevilla/Getty Images
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The meaning of collinear is, lying on a same straight line. So, if the points lie on a straight line, they are called collinear points. Actually, two points are commonly used to represent a ray, a line segment and a straight line graphically. Displaying more than two points on a line is unusual. However, it is essential to show more than two points on a line to know about a case.
Actually, a straight line passes through some points on a plane to form a line. Those points are actually part of the plane, now become part of the line too and they lie on the same straight line. Therefore, the points which lie on a line are called collinear points. Considering the representation of a line, if three or more than two points are displayed on a line, they are called collinear points.
Consider a straight line . It is having two points and on the same line. , , and are total four points and all four points lie on the same straight line. The total points are more than two and lie on the same straight line.
Therefore, the points , , and are collinear points.
List of most recently solved mathematics problems.
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January 17 @ 2:00 pm - 3:00 pm
Acoustic-gravity waves, theory & applications
Abstract: Acoustic–gravity waves (AGWs) are compression-type waves generated as a response to a sudden change in the water pressure, e.g. due to nonlinear interaction of surface waves, submarine earthquakes, landslides, falling meteorites and objects impacting the sea surface. AGWs can travel at near the speed of sound in water (ca. 1500 m/s), but can also penetrate through the sea-floor surface amplifying their speed, which turns them into excellent precursors. “Acoustic–gravity waves” is an emerging field that is rapidly gaining popularity among the scientific community, as it finds broad utility in physical oceanography, marine biology, geophysics, water engineering, and quantum analogues. This talk is an overview on AGWs, with emphasis on recent
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Show that sum of n natural number is equal to n(n plus 1) over 2 for n 1 2 3...
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Show that sum of n natural number is equal to n(n + 1)/2 for n=1 2 3...
using mathematical induction.
We need to start from basis, step, and conclusion.
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ENVS 3340 Alternative Energy (Fall: 3 )
Modern civilization relies upon energy to support nearly all aspects of social and economic activity. Historically, this energy has come from fossil fuels (coal, oil, and natural gas). However, important questions concerning the availability of these energy sources, as well as their social and environmental impacts, have contributed to an increasing interest in the development of alternative sources of energy (solar, wind, geothermal, biomass, tidal and wave). Through an interdisciplinary lens, this course will explore the dynamics of this energy transition with a particular focus on sustainable energy systems and alternative energy resources. Students will be introduced to the technological, economic, political, and environmental dimensions of both conventional and alternative energy resources.
Instructor(s): Duran Fiack
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From Cosmic Birth to Living Earths: The Future of UVOIR Space Astronomy
by Julianne Dalcanton, et al.
Publisher: arXiv 2015
Number of pages: 176
For the first time in history, humans have reached the point where it is possible to construct a revolutionary space-based observatory that has the capability to find dozens of Earth-like worlds, and possibly some with signs of life. This same telescope, designed as a long-lived facility, would also produce transformational scientific advances in every area of astronomy and astrophysics from black hole physics to galaxy formation, from star and planet formation to the origins of the Solar System.
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by Max Fairbairn
The text covers principles of planetary photometry: radiance and the equation of transfer, diffuse reflection and transmission, albedo, scattering and absorption, net flux and exitance, and a brief history of the Lommel-Seeliger law.
by T. L. Wilson - arXiv
An overview of the techniques of radio astronomy. It contains a short history, details of calibration procedures, coherent/heterodyne and incoherent/bolometer receiver systems, observing methods for single apertures and interferometers, etc.
by George Leonard Hosmer - Wiley
The purpose of this volume is to furnish a text in Practical Astronomy especially adapted to the needs of civil-engineering students who can devote but little time to the subject, and who are not likely to take up advanced study of Astronomy.
by Andrew J. Butrica - NASA History Division
A comprehensive history of this surprisingly significant scientific discipline. Quite rigorous and systematic in its methodology, To See the Unseen explores the development of the radar astronomy specialty in the larger community of scientists. | <urn:uuid:981ad597-c589-4bb7-a265-f15167536c9a> | 3.015625 | 376 | Content Listing | Science & Tech. | 17.978185 | 95,583,918 |
A beginners guide to the weather
Learn about the weather and the climate. Our instructional videos offer in-depth discussions of key meteorological topics.
Extended video discussion on the "Great American" solar eclipse which takes place on Monday, August 21st, 2017.
Recap of the amazing derecho event on 6/29/12
Learn how space weather and solar activity are studied and how they influence Earth's weather system
A review of the basic principles of computer forecast models.
An in-depth look at the key equations and input data used in computer weather forecast models.
Discussion about El Nino and La Nina and the impact on the global weather system
A discussion about the myriad forecast models in use today, and how they complement each other via ensemble forecasting
An explanaition of stratospheric warming in the atmosphere
Discussion and details of the phenomenon known as Cold Air Damming
Analysis of the Hurricane Sandy Storm Surge
The back door cold front is an important feature in the Northeast US during the spring season.
Detailed analysis of an Oklahoma tornado.
Several conditions must be right for radiational fog to form and they are discussed in detail during this video discussion.
The weather phenomenon known as "lake-effect snow" is described in detail in this video discussion.
A fast-moving low pressure system dropping southeastward from Canada into the Northeast US during the winter season is commonly referred to by meteorologists as a "clipper" and this weather phenomenon is described in detail in this video discussion.
GOES and POES are two crucial satellite systems used by meteorologists for weather forecasting and climate monitoring purposes.
The North Atlantic Oscillation (NAO) is an important wintertime "teleconnection" for the Mid-Atlantic region. Knowledge of the NAO index is critical for weather forecasting in this region and it is described in detail during this video discussion.
The Pacific Ocean is by far the largest ocean in the world and knowledge of temperature and pressure patterns there are crucial. Similar to the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO) is another important "teleconnection" for the Mid-Atlantic region.
The weather plays a crucial role in the distance a baseball can travel and this video describes in details the many parameters involved such as wind speed, humidity and temperature.
The processes involved with tropical storm formation are described in this video discussion.
Hurricane Sandy (October 2012) generated a damaging storm surge for parts of the New Jersey coastline, but left other areas without serious problems. The processes involved with a storm surge are described in this video discussion with a focus on Hurricane Sandy.
Upper atmosphere winds are crucial to weather forecasting and occasionally there are "blocking" patterns that produce very slow movement of surface-level systems. The "omega" block is one such type of atmospheric wind flow that can grind surface systems to a halt and it is described in detail in this video.
It can be quite useful for weather forecasters to compare past weather events to current events if their are some similarities in the overall atmospheric pattern. Indeed, "analog forecasting" was a useful tool in the prediction of the "Blizzard of February 2014" that pounded the Mid-Atlantic region. | <urn:uuid:9759ef08-6161-45b1-9caa-2542e1d1d791> | 3.328125 | 663 | Content Listing | Science & Tech. | 27.554968 | 95,583,937 |
BizStore » Books » Biocode: The New Age of Genomics
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Publication Date: 2015-05-26
Publisher: Oxford University Press
Studio: Oxford University Press
The living world runs on genomic software - what Dawn Field and Neil Davies call the 'biocode' - the sum of all DNA on Earth. In Biocode, they tell the story of a new age of scientific discovery: the growing global effort to read and map the biocode, and what that might mean for the future. The structure of DNA was identified in 1953, and the whole human genome was mapped by 2003. Since then the new field of genomics has mushroomed and is now operating on an industrial scale. Genomes can now be sequenced rapidly and increasingly cheaply. The genomes of large numbers of organisms from mammals to microbes, have been mapped. Getting your genome sequenced is becoming affordable for many. You too can check paternity, find out where your ancestors came from, or whether you are at risk of some diseases. Some check out the pedigree of their pets, while others turn genomes into art. A stray hair is enough to crudely reconstruct the face of the owner. From reading to constructing: the first steps to creating artificial life have already been taken.
Some may find the rapidity of developments, and the potential for misuse, alarming. But they also open up unprecedented possibilities. The ability to read DNA has changed how we view ourselves and understand our place in nature. From the largest oceans, to the insides of our guts, we are able to explore the biosphere as never before, from the genome up. Sequencing technology has made the invisible world of microbes visible, and biodiversity genomics is revealing whole new worlds within us and without. The findings are transformational: we are all ecosystems now. Already the first efforts at 'barcoding' entire ecological communities and creating 'genomic observatories' have begun. The future, the authors argue, will involve biocoding the entire planet. | <urn:uuid:5c200231-e873-4886-8be4-9c76e73ff7f0> | 2.53125 | 440 | Content Listing | Science & Tech. | 36.288802 | 95,583,938 |