суббота, 8 сентября 2018 г.

Better Net In the UK and many temperate countries, mosquitoes…

Better Net

In the UK and many temperate countries, mosquitoes are mostly just a seasonal annoyance. But in countries where malaria is prevalent, they can be deadly. The malaria parasite, transmitted by the insects’ bite, infects approximately 200 million people a year, killing roughly half a million. Bed nets like the ones pictured, typically treated with an insecticide, are an effective way of preventing bites, but, as the results of a recent trial show, such nets can be improved. A new type of net treated with a chemical cocktail – an insecticide and a hormone that limits mosquito reproduction – has been tested in Burkina Faso where, compared with traditional nets, the new ones led to a 12 percent reduction in the number of malaria cases in two years. That’s a sizeable drop – if the results were extrapolated to the country’s population, the new nets could prevent more than a million cases of malaria.

Written by Ruth Williams

You can also follow BPoD on Instagram, Twitter and Facebook

Archive link

Long March 2C launches Haiyang-1C

CASC – China Aerospace Science and Technology Corporation logo.

September 8, 2018

Haiyang-1C launched by Long March 2C

On September 7, 2018, China launched its third ocean survey satellite of the Haiyang-1 series on Friday, with the launch taking place from the Taiyuan Satellite Launching Center at 03:15 UTC. A Long March-2C (Chang Zheng-2C) rocket was used to loft the new satellite.

Haiyang-1C will be used to monitor and prevent oceanic pollution, resource investigation, construction of bayou and ports, and for the development of coastal areas, using the system to monitor ocean temperatures.

Haiyang-1C (HY-1C) launched by Long March-2C

Onboard HY-1C there are two instruments: The China Ocean Colour & Temperature Scanner (COCTS), a medium-resolution optical imager developed by SITP (Shanghai Institute of Technical Physics) of CAS (China Academy of Sciences), and the Coastal Zone Imager (CZI), a multispectral push broom CCD instrument developed by the Beijing Institute of Space Machines and Electricity, CAST.

Developed for measuring the ocean color and sea surface temperature, the 50 kg COCTS will be used for determining the Aerosol Optical Depth, Aerosol column burden, biomass, the Colour Dissolved Organic Matter (CDOM) and the Earth surface albedo.

Haiyang-1C satellite

The 15 kg CZI will be used to analyze the vegetation and coastal zone, determining the biomass, the Fraction of Absorbed PAR (FAPAR), Fraction of vegetated land, Land cover and the Leaf Area Index (LAI). The CZI used on Haiyang-1C was improved to 50 m resolution (from 250 m from the Haiyang-1B) and also has a wider image swath.

HY-1C is now able to image at up to 20 degrees pitch angles which would minimize problems from sun spots. The satellite lifetime is now five years (up from 3-5 years on HY-1B).

For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html

Images, Video, Text, Credits: CASC/China Central Television (CCTV)/SciNews/NASA Spaceflight.com/Rui C. Barbosa.

Greetings, Orbiter.chArchive link

Haylie Chambered Tomb or ‘Haco’s Tomb’, Haylie, Largs, Scotland,...

Haylie Chambered Tomb or ‘Haco’s Tomb’, Haylie, Largs, Scotland, 8.9.18.

A Neolithic chambered tomb which once had three internal chambers. Until the 18th century, it was a covered cairn.

Source link

2018 September 8 Real Time Perseid Video Credit &…

2018 September 8

Real Time Perseid
Video Credit & Copyright: Till Credner, AlltheSky.com

Explanation: Bright meteors and dark night skies made this year’s Perseid meteor shower a great time for a weekend campout. And while packing away their equipment, skygazers at a campsite in the mountains of southern Germany found at least one more reason to linger under the stars, witnessing this brief but colorful flash with their own eyes. Presented as a 50 frame gif, the two second long video was captured during the morning twilight of August 12. In real time it shows the development of the typical green train of a bright Perseid meteor. A much fainter Perseid is just visible farther to the right. Plowing through Earth’s atmosphere at 60 kilometers per second, Perseids are fast enough to excite the characteristic green emission of atomic oxygen at altitudes of 100 kilometers or so.

∞ Source: apod.nasa.gov/apod/ap180908.html

Torhouse Stone Circle, nr. Wigtown, Dumfries and Galloway, Scotland, 31.8.18.A prominent...

Torhouse Stone Circle, nr. Wigtown, Dumfries and Galloway, Scotland, 31.8.18.

A prominent stone circle created by early farmers in the area. Potentially part of a ritual complex combined with a nearby stone row.

Source link

The Legacy of NASA’s Dawn, Near End of Mission

NASA – Dawn Mission patch.

Sept. 7, 2018

Revealing Solar System Time Capsules, Breaking Engineering Barriers

NASA’s Dawn mission is drawing to a close after 11 years of breaking new ground in planetary science, gathering breathtaking imagery, and performing unprecedented feats of spacecraft engineering.

Dawn’s mission was extended several times as it explored Ceres and Vesta, which when combined, make up 45 percent of the mass of the main asteroid belt. Now, the spacecraft is about to run out of a key fuel, hydrazine. When that happens, most likely between September and October, Dawn will lose its ability to communicate with Earth. It will remain in a silent orbit around Ceres for decades.

“Although it will be sad to see Dawn’s departure from our mission family, we are intensely proud of its many accomplishments,” said Lori Glaze, acting director of the Planetary Science Division at Headquarters in Washington. “Not only did this spacecraft unlock scientific secrets at these two small but significant worlds, it was also the first spacecraft to visit and orbit bodies at two extraterrestrial destinations during its mission. Dawn’s science and engineering achievements will echo throughout history.”

Dusk for Dawn: NASA Mission to the Asteroid Belt

Video above: NASA’s Dawn spacecraft turned science fiction into science fact by using ion propulsion to explore the two largest bodies in the main asteroid belt, Vesta and Ceres. The mission will end this fall, when the spacecraft runs out of hydrazine, which keeps it oriented and in communication with Earth. Video Credit: JPL.

Dawn launched from Cape Canaveral Air Force Station in September 2007, strapped on a Delta II-Heavy rocket. From 2011 to 2012, the spacecraft swept over Vesta, capturing images of craters, canyons and even mountains of this planet-like world.

Then in 2015, Dawn’s cameras spotted a cryovolcano and mysterious bright spots on Ceres, which scientists later found might be salt deposits produced by the exposure of briny liquid from Ceres’ interior.

“Dawn’s legacy is that it explored two of the last uncharted worlds in the inner Solar System,” said Marc Rayman of NASA’s Jet Propulsion Laboratory, Pasadena California, who serves as Dawn’s mission director and chief engineer. “Dawn has shown us alien worlds that, for two centuries, were just pinpoints of light amidst the stars. And it has produced these richly detailed, intimate portraits and revealed exotic, mysterious landscapes unlike anything we’ve ever seen.”

Engineering Feats

Dawn is the only spacecraft to orbit a body in the asteroid belt. And it is the only spacecraft to orbit two extraterrestrial destinations. These feats were possible thanks to ion propulsion, a tremendously efficient propulsion system familiar to science-fiction fans and space enthusiasts. Dawn pushed the limits of the system’s capabilities and stamina, showing how useful it is for other missions that aim to visit multiple destinations.

Pushed by ion propulsion, Dawn reached Vesta in 2011 and investigated it from surface to core during 14 months in orbit. In 2012, engineers maneuvered Dawn out of orbit, and steered it though the asteroid belt for more than two years before inserting it into orbit around the dwarf planet Ceres, where it has been collecting data since 2015.

Artist’s view of Dawn spacecraft. Image Credits: NASA/JPL

The mission targeted Ceres and Vesta because they function as time capsules, intact survivors of the earliest part of our history.

“Vesta and Ceres have each told their story of how and where they formed, and how they evolved — a fiery magmatic history that led to rocky Vesta and a cooler, water-rich history that resulted in the ancient ocean world Ceres,” said Carol Raymond of JPL, principal investigator of the Dawn mission. “These treasure troves of information will continue to help us understand other bodies in the Solar System far into the future.”

Spectacular Ceres

On Ceres’s surface, scientists found the chemistry of an ancient ocean. “What we found was completely mind-blowing. Ceres’ history is just splayed all over its surface,” Raymond said.

Some of the bright spots turned out to be brilliant, salty deposits, made mainly of sodium carbonate that made its way to the surface in a slushy brine from within or below the crust.

The findings reinforce the idea that dwarf planets, not just icy moons like Enceladus and Europa, could have hosted oceans during their history — and potentially still do. Analyses from Dawn data suggest there still may be liquid under Ceres’ surface and that some regions were geologically active relatively recently, feeding from a deep reservoir.

Bright Spots On Ceres

Image above: Bright surface features on the dwarf planet Ceres known as faculae were first discovered by NASA’s Dawn spacecraft in 2015. This mosaic of one such feature, Cerealia Facula, combines images obtained from altitudes as low as 22 miles (35 km) above Ceres’ surface. The mosaic is overlain on a topography model based on images obtained during Dawn’s low altitude mapping orbit (240 miles or 385 km altitude). No vertical exaggeration was applied. The center of Cerealia Facula is located at 19.7 degrees north latitude and 239.6 degrees south longitude. During its mission of over a decade, the Dawn spacecraft has studied the asteroid Vesta and dwarf planet Ceres, celestial bodies believed to have formed early in the history of the solar system. The mission’s goal is to characterize the early solar system and the processes that dominated its formation. Image Credit: NASA.

One of Dawn’s biggest reveals on Ceres lay in the region of Ernutet Crater. Organic molecules were found in abundance. Organics are among the building blocks of life, though Dawn’s data can’t determine if Ceres’ organics were formed from biological processes.

“There is growing evidence that the organics in Ernutet came from Ceres’ interior, in which case they could have existed for some time in the early, interior ocean,” said Julie Castillo-Rogez, Dawn’s project scientist and deputy principal investigator at JPL.

Vibrant Vesta

At Vesta, Dawn mapped the craters of this planet-like world and revealed that its northern hemisphere had experienced more large impacts than expected, suggesting there were more large objects in the asteroid belt early on than scientists thought.

In 1996, the Hubble space telescope relayed images of a mountain at the center of an enormous Vesta basin now called Rheasilvia. Dawn’s mapping showed it to be twice the height of Mt. Everest, and it revealed canyons that rival the Grand Canyon in size.

Dawn also confirmed Vesta as the source of a very common family of meteorites.

Nearing the End

Dawn has continued to gather high-resolution images, gamma ray and neutron spectra, infrared spectra and gravity data at Ceres. Nearly once a day, it will swoop over Ceres about 22 miles (35 kilometers) from its surface — only about three times the altitude of a passenger jet — gathering valuable data until it expends the last of the hydrazine that feeds thrusters controlling its orientation.

Because Ceres has conditions of interest to scientists who study chemistry that leads to the development of life, NASA follows strict planetary protection protocols for the disposal of the Dawn spacecraft. Unlike Cassini, which deliberately plunged into Saturn’s atmosphere to protect the system from contamination — Dawn will remain in orbit around Ceres, which has no atmosphere.

Engineers designed Dawn’s final orbit to ensure it will not crash for at least 20 years — and likely decades longer.

Rayman, who led the team that flew Dawn throughout the mission and into its final orbit, likes to think of Dawn’s end this way: as “an inert, celestial monument to human creativity and ingenuity.”

More on Dawn’s mission legacy is here: https://dawn.jpl.nasa.gov/mission/toolkit/

The Dawn mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. JPL is responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team.

For a complete list of mission participants, visit: https://dawn.jpl.nasa.gov/mission

More information about Dawn is available at the following sites:



Images (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/JoAnna Wendel​/Tony Greicius/JPL/Gretchen McCartney.

Greetings, Orbiter.chArchive link

Japan Is Go for Monday Cargo Launch to Station

ISS – Expedition 56 Mission patch.

September 7, 2018

Japan’s seventh cargo mission (HTV-7) to the International Space Station is in the final stages of preparation for launch on Monday at 7:32 p.m. EDT. Mission controllers are monitoring the weather at the Tanegashima Space Center launch site while the Expedition 56 crew is preparing for its arrival early Friday.

JAXA’s (Japan Aerospace Exploration Agency) HTV-7 is delivering a wide variety of science gear to support new research aboard the orbital lab. The new facilities will enable astronauts to observe physical processes at high temperatures, protein crystal growth and genetic alterations as well as a variety of other important space phenomena.

Image above: The Japanese HTV-6 cargo vehicle is seen during final approach to the International Space Station on Dec. 13, 2016. Image Credit: NASA:

HTV-7, also known as Kounotori, is also carrying six new lithium-ion batteries that robotics controllers will remove then install on the station’s port 4 truss structure. Astronauts Alexander Gerst, Drew Feustel and Ricky Arnold will complete the battery maintenance work over two spacewalks set for Sept. 20 and 26.

Feustel will lead the effort to capture Kounotori when he commands the Canadarm2 robotic arm to reach out and grapple it Friday at 7:40 a.m. He trained today with Flight Engineer Serena Auñón-Chancellor, who will back him up in the Cupola, practicing capture techniques on a computer.

International Space Station (ISS). Image Credit: NASA/STS-134

All six crew members got together at the end of the day for more eye checks. The sextet from the U.S., Russia and Germany used an ultrasound device, with assistance from doctors on the ground, and scanned each other’s eyes.

Related links:

Expedition 56: https://www.nasa.gov/mission_pages/station/expeditions/expedition56/index.html

JAXA’s (Japan Aerospace Exploration Agency) HTV-7: http://global.jaxa.jp/projects/iss_human/index.html

Spacewalks: https://www.nasa.gov/mission_pages/station/spacewalks

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.chArchive link

The incredible lightness of the Higgs

CERN – European Organization for Nuclear Research logo.

7 Sep 2018

Why is the Higgs boson so light? That’s one of the questions that has been bothering particle physicists since the famous particle was discovered in 2012. This is because the theory of how the particle interacts with the most massive of all observed elementary particles, the top quark, involves corrections at a fundamental (quantum) level that could result in a Higgs mass much larger than the measured value of 125 GeV. How large? Perhaps as much as sixteen orders of magnitude larger than the measured Higgs mass. Since the Higgs mass is so light, this suggests more particles could exist that cancel the quantum corrections from the top quark (and other heavy particles).

In a paper posted online and submitted to the journal Physical Review Letters, the ATLAS collaboration reports results of a combination of searches for a new particle – dubbed a vector-like top quark – that could help keep the Higgs boson light.

Image above: View of the ATLAS detector. The ATLAS collaboration reports results of a combination of searches for a new particle – dubbed a vector-like top quark – that could be the culprit behind the Higgs lightness. (Image: Claudia Marcelloni/ATLAS CERN).

Various proposals attempt to cancel out the large quantum corrections to the Higgs boson mass. Many of them involve vector-like top quarks, which are hypothetical particles not predicted by the Standard Model of particle physics. Unlike the Standard Model top quark, which always decays to a bottom quark and a W boson, vector-like top quarks would decay in one of three different ways, if they decayed to Standard Model particles. Specifically, a vector-like top quark would decay to a bottom quark and a W boson, or to a Z boson and a top quark, or still to a Higgs boson and a top quark.

To maximise the chances of finding vector-like top quarks, the ATLAS collaboration conducted several different types of search using data from proton–proton collisions collected at the Large Hadron Collider (LHC) in 2015 and 2016 at an energy of 13 TeV; each individual search is sensitive to a particular set of particle decays. They then combined the results to increase the sensitivity to vector-like top quarks, yet found no sign of them.

Despite this, their analysis allowed them to expand the reach of individual searches and place the most stringent lower bounds on the mass of vector-like top quarks to date. The analysis excludes vector-like top quarks with masses below about 1300 GeV for any combination of the three top-quark decays into Standard Model particles. The previous best lower limit from an individual search was 1190 GeV.

It will now get more challenging: for masses heavier than 1300 GeV a single vector-like top quark is created more often than a pair. But with a wealth of data coming from the LHC, the search continues.


CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related links:

Physical Review Letters: https://arxiv.org/abs/1808.02343

Higgs boson: https://home.cern/topics/higgs-boson

Standard Model of particle physics: https://home.cern/about/physics/standard-model

ATLAS: https://home.cern/about/experiments/atlas

Large Hadron Collider (LHC): https://home.cern/topics/large-hadron-collider

For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/

Image (mentioned), Text, Credits: CERN/Ana Lopes.

Best regards, Orbiter.chArchive link

How the clownfish earned its stripes: Colour pattern evolution in coral reef fishes

Coral reef fishes, including clownfish, display a wide variety of colors but it remains unclear how these colors evolved or how they develop throughout a fish’s life. Research published in BMC Biology sheds new light on the evolution of different stripe patterns in clownfish and on how these patterns change as individuals from different species grow from larvae into adults.

How the clownfish earned its stripes: Colour pattern evolution in coral reef fishes
The full spectrum of clown fish colors is not limited to orange or red but ranges from yellow to black. Species differ
in the number of white stripes they display: zero, one (head), two (head and trunk), or three (head, trunk, and tail).
Four species of clown fish (genus Amphiprion), clockwise from top left: A. ephippium, A. frenatus,
A. ocellaris, and A. bicinctus [Credit: ©John E. Randall]

Dr Vincent Laudet, the corresponding author at Sorbonne University, France said: “We show that the ancestor of today’s clownfish possessed three white stripes. Then, as some species evolved they lost stripes and we reveal a surprising similarity between this loss of stripes during species evolution and the development of different stripe patterns in individuals from different species today. “

Studying two species of clownfish – Amphiprion ocellaris and Amphiprion frenatus – that have three stripes or a single head stripe, respectively, the authors found that shortly after hatching, the larvae of neither species had any stripes. Subsequently, both species acquired stripes on head and trunk at the same time, with A. oscellaris acquiring a third stripe near the tail and A. frenatus losing the trunk stripe before reaching adulthood.

Examining development information for 26 additional species of clownfish, the authors observed that at least nine species have more stripes as juveniles than they do as adults, which prompted the authors to investigating the development of stripes across the evolution of clownfish.

Dr Laudet said: “Interestingly, every clownfish species existing today gains stripes from front to back after they are born, before individuals of some species lose stripes again from back to front as they grow into adults, which is similar to the loss of stripes observed during clownfish evolution; while all clownfish started out with three stripes – that is their last common ancestor had three stripes – as they diversified into what are now 30 different species, some clownfish lost stripes in a pattern that is similar to how today’s clownfish lose stripes as they grow up.”

How the clownfish earned its stripes: Colour pattern evolution in coral reef fishes
Fifteen-day-old juvenile clown fish (A. ocellaris). It already fully displays two anterior stripes,
on the head and trunk, while a third is forming on the tail [Credit: © Natacha Roux]

Dr Laudet added: “It is also interesting that while clownfish species vary in their number of stripes from zero to three, there is limited variation in how these stripes are organised. In all two-striped species, the stripe nearest the tail has been lost, while the head and the trunk stripes are retained. All one-striped species have retained the head stripe and have lost the trunk and tailfin stripes. So, some fish have no stripes at all, while others have one stripe near the head, one stripe each near the head and on the trunk, or three stripes near the head, on the trunk, and near the tail, but you will never find a clownfish with just one stripe near the tail, or one stripe near the tail and one near the head.”

In order to investigate the molecular mechanisms that underlie stripe formation and loss, the authors treated clownfish larvae with a substance known to suppress stripe development in zebrafish. The substance works by targeting certain receptors in iridophores; the cells that produce a reflective/ iridescent color. The authors found that larvae treated with the substance did not fully develop stripes or developed no stripes at all in a dose-dependent manner.

The findings suggest that the white stripes in clownfish are produced by iridophores and that a decrease in the number of these cells will inhibit stripe formation.

Dr Laudet said: “Because coral reef fishes provide examples of complex color patterns, they offer a unique opportunity to better understand the origin of these traits. Unraveling the mysteries of why pigmentation patterns from coral reef fish are so diverse, how they evolved and where their diversity originated will help us to understand the formation of very complex phenotypes.”

The authors also suggest a possible purpose for the different stripe patterns; they may allow clownfish to recognize individuals belonging to the same species, including potential partners for reproduction.

Source: CNRS [September 04, 2018]



Researchers study how wolf predation shapes elk antler evolution

What happens when you mix a biologist who studies beetle horns with scientists who spend their time exploring predator-prey dynamics? You get a better understanding of why elk shed their antlers much later than males of any other North American species.

Researchers study how wolf predation shapes elk antler evolution
University of Montana researchers Matt Metz and Mark Hebblewhite examine the remains of an elk
[Credit: National Park Service]

University of Montana researchers and their partners recently published a study in Nature Ecology and Evolution chronicling an evolutionary tie between wolves and when bull elk shed their antlers.

The authors were UM doctoral candidate Matt Metz, along with UM co-authors Doug Emlen and Mark Hebblewhite, Dan Stahler and Doug Smith of the National Park Service, and Dan MacNulty of Utah State University.

They discovered that wolves in Yellowstone National Park preferentially hunted bulls who already had shed their antlers over those who still had them during late winter. The finding suggests that antlers are used for more than just competing for cows – that they help deter predators, too – which could help explain why bulls shed their antlers long after the rut.

“Because wolves often prefer elk in these systems, male elk uniquely keep their antlers for much of the winter,” Metz said. “Other species, say moose in our study system, shed their antlers beginning in December. We believe elk evolved to keep their antlers longer than any other North American deer because they use their antlers as an effective deterrent against wolf predation.”

Antlers evolved to improve breeding success. The bigger the antlers, the more likely a bull is to successfully breed cows during the fall. In many species, these types of weapons also serve secondary purposes, but those reasons are not always well understood, as is the case for elk.

Bulls shed their antlers beginning at the end of each winter and immediately start growing another set. Getting rid of antlers as soon as possible removes a cumbersome burden and gives individual bulls a jumpstart at growing antlers for next year’s rut.

But as a whole, elk shed their antlers months later compared to other North American deer species, and shedding is staggered over a two month period beginning in March, suggesting there might be other reasons to keep antlers around a little longer.

Researchers study how wolf predation shapes elk antler evolution
Wolves and an elk face off in Yellowstone National Park
[Credit: Dan Stahler, National Park Service]

“Antlers are the product of sexual selection, where males are competing over breeding opportunities in a short time window in the fall,” Metz said. “Here we show that the evolution of antlers was also influenced by other things in an elk’s environment, like wolf predation, and that a secondary function also helped to shape the characteristics of this structure, such as when antlers are shed.”

Metz, a longtime Yellowstone wolf researcher, analyzed over a decade’s worth of data from the Yellowstone Wolf Project, a long-term study recording interactions between wolves and their prey.

Wolves in Yellowstone often kill bull elk during the winter months, but Metz and his co-authors found that wolves strongly preferred to kill individuals who had already shed their antlers – even though they were often in better condition than bulls who still had their rack. The results showed that antlers are indeed an important predatory deterrent for elk – a secondary function that could help explain variation in antler retention time across species in temperate climates.

“These males that shed their antlers first are more vulnerable to being killed by wolves despite being in better nutritional condition,” Metz said. “The individuals who are in the best condition are the first to drop their antlers to get a leg up on growing larger antlers for the next season and therefore gain the greatest reproductive success. Wolves mostly target individuals who are very young, old or in poor nutritional condition, which are characteristics that make them vulnerable. Here we identified a new, unexpected vulnerability – shedding antlers early.”

The study highlights an evolutionary Catch-22: Weapons come with both benefits and costs. Bulls who drop their antlers early may grow relatively larger antlers in the upcoming year, winning more cows, but they’re also at greater risk to become dinner first.

For younger bulls unlikely to be successful in the upcoming rut anyway, the risk is too high. These males are among the last to cast their antlers.

Metz earned a B.S. in wildlife biology from UM and has studied predator-prey dynamics in Yellowstone since 2002.

“The study first came about through observations that I had when I worked as a seasonal field technician for the Yellowstone Wolf Project in the early 2000s,” he said. “We usually see antler-casting starting at the tail-end of March. But the winter of 2004-05 was milder, and bulls were shedding their antlers a little earlier.”

Researchers study how wolf predation shapes elk antler evolution
Wolves chase an elk that has shed its antlers in Yellowstone National Park
[Credit: Doug Smith, National Park Service]

One day he and another researcher spotted a wolf-killed elk.

“We hiked into it, and it was an antlerless male in early March,” Metz said. “We hadn’t seen any living bull elk without antlers yet on the landscape. We thought, ‘That’s kind of interesting.’ We just started to notice this relationship where we would observe wolves encountering male elk, and they seemed to be focusing on those who had already shed their antlers. It took 13 years of data to actually test this idea.”

Along the way, Metz pulled in other co-authors, including UM professors Hebblewhite and Emlen.

“To me, one of the coolest things about this project is how it started,” said Hebblewhite, a wildlife biology professor in UM’s W.A. Franke College of Forestry and Conservation who focuses on large-mammal predator-prey systems. “It started with Matt just being observant, noticing something in nature, and then diving into it over a decade to find out why. This is the heart of the scientific process.”

Hebblewhite has studied wolves and their prey for a quarter century, but this is the first time he’d stopped to consider what makes antlers antlers. “A lot of the time, the reasons we study nature are to control or manage it, to make it do something we want for us,” he said. “This is a case of wonder at its finest.”

Emlen, an evolutionary biologist and professor in the Division of Biological Sciences, said what was most fun about the project was the nature of the collaboration, which crossed departments and disciplines.

“Matt is a wolf biologist. And Hebblewhite is an elk biologist, but he doesn’t focus on antlers,” Emlen said. “I work on rhino beetles, and I study animal weapons – beetle horns. I spend most of my time thinking about why weapons are so big. It’s been a blast to work on antlers, because those are giant weapons. It’s been a wild ride. That a beetle biologist who studies weapons can collaborate with elk and wolf biologists adds a fun twist to the story.”

Source: University of Montana [September 04, 2018]



Episodic and intense rain caused by ancient global warming

A new study by scientists at the University of Bristol has shown that ancient global warming was associated with intense rainfall events that had a profound impact on the land and coastal seas.

Episodic and intense rain caused by ancient global warming

Episodic and intense rain caused by ancient global warming
Top panel shows modelled change in annual mean rainfall (as a %) given a global warming at the PETM, ~56 million
years ago. Bottom panel shows the same thing but for extremes in rainfall. The key thing is that in some regions,
the rainfall decreases (top panel is red) but the extremes in rainfall increase (bottom panel is blue), such
as in southern Africa, the Amazon, or northern Australia. This is what we mean by a “decoupling”
[Credit: BRIDGE/University of Bristol]

The Palaeocene-Eocene Thermal Maximum (PETM), which occurred about 56 Million years ago, is of great interest to climate scientists because it represents a relatively rapid global warming event, with some similarities to the human-induced warming of today.

Although there have been many investigations of how much the Earth warmed at the PETM, there have been relatively few studies of how that changed the hydrological cycle.

This newly published work shows that rainfall increased in some places and decreased in others, according to expectations, but that much of the world experienced more intense and episodic (or ‘flashy’) rainfall events.

Lead author Dr Matt Carmichael from the University’s Schools of Chemistry and Geographical Sciences, said: “With the same climate models used to study future climate change, we studied how a doubling of carbon dioxide concentrations would affect rainfall patterns on a world with Eocene geography.

“This increased the overall global precipitation — warmer air holds more water. But it also changed the pattern and frequency of extreme events.

“The tropics became wetter and the incidence of extreme events increased, by as much as 70 percent in some tropical regions.

“In other places, total annual precipitation and the number of extreme events became decoupled; in other words, they became drier, with less frequent but more extreme events. All of this illustrates the complexity of how global warming will affect our local, regional and global rainfall patterns.”

Co-author Professor Rich Pancost from Bristol’s School of Earth Sciences, explained how these findings agree with a range of geological and chemical features of the Palaeocene-Eocene global warming.

He said: “This warming event is associated with major changes in how soil and sediment were eroded and moved around the landscape.

“In many places, river systems that had been transporting silt or sand became associated with fist-sized rocks or even boulders; and more sediment was transported to and buried in coastal margins. In some locations, the rate of sediment accumulation increased by a factor of ten. But at the same time, there is also evidence that these systems became more arid.

“Our climate simulations reconcile this for many locations, showing an increase in aridity with fewer but more intense rainfall events. Those events were likely responsible for increased energy in these systems, moving around more material and larger objects. Ultimately it flushed more sediment to the ocean, causing eutrophication, blooms of algae and in some cases hypoxia.”

Co-author Professor Dan Lunt from the School of Geographical Sciences added: “There are many similar events in Earth history, where warming appears to have been associated with changes in rainfall and sedimentary systems.

“Although we have not investigated them here, it is very likely that our results are translatable — because the physics that underpins them remains the same. Thus, the collective body of research confirms that global warming in the past and the future will be associated with more ‘flashy’ rainfall, with implications for flooding and water management.”

Professor Pancost said: “Past climate has lessons for our future. Not only do the models show evidence for more intense rainfall events — with all of the implications that entails — but they are consistent with all of our other data.

“In fact, they explain inconsistencies in our other data and confirm some long-established hypotheses. In doing so, they foreshadow our potential future with complex and dramatic changes in rainfall, more flooding and more soil erosion.”

The study is published in Earth and Planetary Science Letters.

Source: University of Bristol [September 04, 2018]



Youngest accretion disk detected in star formation

An international team led by Chin-Fei Lee at the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) has discovered a very small accretion disk formed around one of the youngest protostars, with the Atacama Large Millimeter/submillimeter Array (ALMA). This discovery poses a constraint on current theory of disk formation stronger than before, by pushing the disk formation time by a factor of a few earlier. Moreover, a compact rotating outflow has been detected. It may trace a disk wind carrying away angular momentum from the disk and thus facilitate the disk formation.

Youngest accretion disk detected in star formation
Jet, disk, and outflow in the HH 211 protostellar system. (Top) A composite image showing the jet system.
(Bottom) A zoom-in to the innermost region around the central protostar, showing the disk and outflow there.
Asterisks mark the possible position of the central protostar. Gray arrows show the jet axis. Orange image
shows the dusty disk at submillimeter wavelength obtained with ALMA. Blue and red images show the
blueshifted and redshifted parts of the outflow coming out from the disk rotating around the jet axis
[Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.]

“ALMA is so powerful that it can resolve an accretion disk with a radius as small as 15 astronomical units (AU),” says Chin-Fei Lee at ASIAA. “Since this disk is about a few times younger than the previously resolved youngest disk, our result has provided a stronger constraint on current theory of disk formation by pushing the disk formation time by a factor of a few earlier. Moreover, together with the previous results of the older disks, our disk result favors a model where the disk radius grows linearly with the protostellar mass, and thus supporting the ‘early-start, slow-growth’ scenario against the ‘slow-start, rapid-growth’ scenario for accretion disk formation around protostars.”
HH 211 is one of the youngest protostellar systems in Perseus at a distance of about 770 light-years. The central protostar has an age of only about 10,000 years (which is about 2 millionths of the age of our Sun) and a mass of less than 0.05 solar mass. It drives a powerful bipolar jet and thus must accrete material efficiently.

Youngest accretion disk detected in star formation
Size comparison between the HH 211 disk (Left) and HH 212 disk (Right, adopted from Lee et al. 2017). Note
 that HH 211 disk has been rotated to align with the HH 212 disk in order to facilitate the comparison
 [Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al.]

Previous search at a resolution of about 50 AU only found a hint of a small dusty disk near the protostar. Now with ALMA at a resolution of 7 AU, which is about 7 times finer, the dusty disk at submillimeter wavelength not only has been detected but also spatially resolved. It is a nearly edge-on accretion disk feeding the central protostar and has a radius of about 15 AU. The disk is thick, indicating that the submillimeter light emitting grains have yet to settle to the midplane. Unlike the previously resolved older edge-on disk HH 212 which appears as a large “hamburger,” this younger edge-on disk appears as a small “bun.” Thus, it seems that an edge-on disk will grow from a small “bun” to a large “hamburger” in a later phase. Moreover, a compact rotating outflow has been detected, and it may trace a disk wind carrying away angular momentum from the disk and thus facilitate the disk formation.

The observations open up an exciting possibility of directly detecting and characterizing small disks around the youngest protostars through high-resolution imaging with ALMA, which provides strong constraints on theories of disk formation and thus the feeding process in star formation.

The study is published in The Astrophysical Journal.

Source: Academia Sinica Institute of Astronomy and Astrophysics [September 05, 2018]



Relationship established between brightness and diet of black holes

A group of researchers led by Paula Sánchez-Sáez, a doctoral student in the Department of Astronomy of the Universidad de Chile, managed to determine that the rate of variability in the light emitted by material being swallowed by supermassive black holes in nuclei of active galaxies is determined by the accretion rate, that is, how much matter they are “eating.”

Relationship established between brightness and diet of black holes
This artist’s concept depicts a supermassive black hole at the centre of a galaxy. The blue colour here represents
 radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole,
called a torus, is made up of gas and dust [Credit: Growtopia Wiki – Fandom]

“The light emitted by the material that is falling (its brightness) changes a lot over time, without a stable pattern, so we say that they show variability. We know that it varies, but we still do not know clearly why. If one observes other objects, such as stars or galaxies without active nuclei, their brightness is constant over time, but if we look at galaxies with active nuclei their brightness rises and falls, and is completely unpredictable. We studied how the amplitude of this variation in the emitted light (or in simple words, the amplitude of the variability) is related, with the average luminosity emitted by the AGN, the mass of the super massive black hole, and the AGN accretion rate (which corresponds to how much material the black hole consumes in a year). The results of our analysis show that, contrary to what was believed, the only important physical property to explain the amplitude of the variability is the AGN accretion rate,” explains the young researcher.
The study determined that there is only one physical property that could predict the variability of these objects: the accretion rate. “This is nothing but how much material is falling into this supermassive black hole. So if it is on a diet, or if it is swallowing a lot or if it does not fit anymore in his mouth… that will determine if they vary much or little. And what we detect is that the less they swallow, the more they vary,” explains Paulina Lira, an academic from the Department of Astronomy of the Universidad de Chile, and a researcher at the CATA Center for Excellence in Astrophysics.

For Paula Sánchez-Sáez, first author of the study, the importance of this discovery is to try to elucidate what is the physical mechanism behind this variability, one of the most inherent characteristics of the active galactic nuclei. “The results obtained in this study challenge the old paradigm that the amplitude of the AGN variability depended mainly on the luminosity of the AGN. This was believed because measuring the mass of black holes is not always possible, so the measurement of accretion rates could only be done accurately for a few objects, but with the SDSS data it was possible to measure these physical properties for a sample of the order of 2,000 objects, which were also observed by the QUEST-La Silla AGN Variability Survey. In addition, from our variability survey, we were able to obtain very good quality light curves for a large sample of objects, so we could study the variability of each object independently, which was not possible before for a large sample of AGN. Combining the fact that we had precise measurements of AGN physical properties, in addition to a good characterization of the variability of individual AGN, we could determine that the main factor that determines the amplitude of the variability is the accretion rate, or in more technical words the Eddington ratio,” she says.

The data used in this work comes from two sources. For the variability analysis they used data from the QUEST-La Silla AGN Variability Survey (led by Paulina Lira), which was carried out between 2010 and 2015, observing 5 extragalactic fields. For the study of the physical properties of the AGN, they used public spectral data from the Sloan Digital Sky Survey (SDSS).

In the future, the researchers will seek to study the time scale of variability of these active galactic nuclei. “Another very important property is the time scale of variability of these objects. To measure this property accurately we need to have light curves with a coverage of more than 10 years. So we must wait until future surveys, such as the Large Synoptic Survey Telescope (LSST), provide more photometric data, so we can combine these data with our data from QUEST-La Silla AGN variability survey to extend our light curves to an order of 20 years,” says Paula.

The findings are published in The Astrophysical Journal.

Source: University of Chile [September 05, 2018]



New exoplanet twice the size of Earth discovered

Wolf 503b, an exoplanet twice the size of Earth, has been discovered by an international team of Canadian, American and German researchers using data from NASA’s Kepler Space Telescope. The find is described in a new study whose lead author is Merrin Peterson, an Institute for research on exoplanets (iREx) graduate student who started her master’s degree at Université de Montréal (UdeM) in May.

New exoplanet twice the size of Earth discovered
A size comparison of the Earth, Wolf 503b and Neptune. The color blue for Wolf 503b
 is imaginary; nothing is yet known about the atmosphere or surface of the planet
[Credit: NASA Goddard/Robert Simmon (Earth), NASA/JPL (Neptune)]

Wolf 503b is about 145 light years from Earth in the Virgo constellation; it orbits its star every six days and is thus very close to it, about 10 times closer than Mercury is to the Sun.

“The discovery and confirmation of this new exoplanet was very rapid, thanks to the collaboration that I and my advisor, Björn Benneke, are a part of,” Peterson said. “In May, when the latest release of Kepler K2 data came in, we quickly ran a program that allowed us to find as many interesting candidate exoplanets as possible. Wolf 503b was one of them.”

The program the team used identifies distinct, periodic dips that appear in the light curve of a star when a planet passes in front of it. In order to better characterize the system Wolf 503b is part of, the astronomers first obtained a spectrum of the host star at the NASA Infrared Telescope Facility. This confirmed the star is an old ‘orange dwarf’, slightly less luminous than the Sun but about twice as old, and allowed a precise determination of the radius of both the star and its companion.

To confirm the companion was indeed a planet and to avoid making a false positive identification, the team obtained adaptive optics measurements from Palomar Observatory and also examined archival data. With these, they were able to confirm that there were no binary stars in the background and that the star did not have another, more massive companion that could be interpreted as a transiting planet.

Wolf 503b is interesting, firstly, because of its size. Thanks to the Kepler telescope, we know that most of the planets in the Milky Way that orbit close to their stars are about as big as Wolf 503b, somewhere between that the size of the Earth and Neptune (which is 4 times bigger than Earth). Since there is nothing like them in our solar system, astronomers wonder whether these planets are small and rocky ‘super-Earths’ or gaseous mini versions of Neptune. One recent discovery also shows that there are significantly fewer planets that are between 1.5 and 2 times the size of Earth than those either smaller or larger than that. This drop, called the Fulton gap, could be what distinguishes the two types of planets from each other, researchers say in their study of the discovery, published in 2017.

“Wolf 503b is one of the only planets with a radius near the gap that has a star that is bright enough to be amenable to more detailed study that will better constrain its true nature,” explained Björn Benneke, an UdeM professor and member of iREx and CRAQ. “It provides a key opportunity to better understand the origin of this radius gap as well as the nature of the intriguing populations of ‘super-Earths’ and ‘sub-Neptunes’ as a whole.”

The second reason for interest in the Wolf 503b system is that the star is relatively close to Earth, and thus very bright. One of the possible follow-up studies for bright stars is the measurement of their radial velocity to determine the mass of the planets in orbit around them. A more massive planet will have a greater gravitational influence on its star, and the variation in line-of-sight velocity of the star over time will be greater. The mass, together with the radius determined by Kepler’s observations, gives the bulk density of the planet, which in turn tells us something about its composition. For example, at its radius, if the planet has a composition similar to Earth, it would have to be about 14 times its mass. If, like Neptune, it has an atmosphere rich in gas or volatiles, it would be approximately half as massive.

Because of its brightness, Wolf 503 will also be a prime target for the upcoming James Webb Space Telescope. Using a technique called transit spectroscopy, it will be possible to study the chemical content of the planet’s atmosphere, and to detect the presence of molecules like hydrogen and water. This is crucial to verify if it is similar to that of the Earth, Neptune or completely different from the atmospheres of planets in our solar system.

Similar observations can’t be made of most planets found by Kepler, because their host stars are usually much fainter. As a result, the bulk densities and atmospheric compositions of most exoplanets are still unknown.

“By investigating the nature of Wolf 503b, we’ll understand more about the structure of planets near the radius gap and more generally about the diversity of exoplanets present in our galaxy,” said Peterson. “I look forward to learning more about it.”

Source: Université de Montréal [September 05, 2018]



Prehistoric Pottery, Fragments and Rock Art, Stranraer Museum, Scotland, 1.9.18.A...

Prehistoric Pottery, Fragments and Rock Art, Stranraer Museum, Scotland, 1.9.18.

A selection of decorated pottery and pottery fragments from the Bronze Age and later. The museum also displays a single slab of ‘cup and ring’ rock art.

Source link


    Солнечное затмение 14 декабря 2020 года  — полное  солнечное затмение  142  сароса , которое лучше всего будет видно в юго-восточной час...