In Greek mythology, Icarus is the son of the master craftsman Daedalus, the creator of the Labyrinth. Often depicted in art, Icarus and his father attempt to escape from Crete by means of wings that his father constructed from feathers and wax. Icarus's father warns him first of complacency and then of hubris, asking that he fly neither too low nor too high, because the sea's dampness would clog his wings or the sun's heat would melt them. Icarus ignored his father's instructions not to fly too close to the sun, whereupon the wax in his wings melted and he fell into the sea. This tragic theme of failure at the hands of hubris contains similarities to that of Phaëthon. Wikipedia.


Time filter

Source Type

News Article | February 28, 2017
Site: phys.org

NASA's Curiosity Mars rover, on the lower slope of Mount Sharp—a layered mountain inside the crater—has begun a second campaign of investigating active sand dunes on the mountain's northwestern flank. The rover also has been observing whirlwinds carrying dust and checking how far the wind moves grains of sand in a single day's time. Gale Crater observations by NASA's Mars Reconnaissance Orbiter have confirmed long-term patterns and rates of wind erosion that help explain the oddity of having a layered mountain in the middle of an impact crater. "The orbiter perspective gives us the bigger picture—on all sides of Mount Sharp and the regional context for Gale Crater. We combine that with the local detail and ground-truth we get from the rover," said Mackenzie Day of the University of Texas, Austin, lead author of a research report in the journal Icarus about wind's dominant role at Gale. The combined observations show that wind patterns in the crater today differ from when winds from the north removed the material that once filled the space between Mount Sharp and the crater rim. Now, Mount Sharp itself has become a major factor in determining local wind directions. Wind shaped the mountain; now the mountain shapes the wind. The Martian atmosphere is about a hundred times thinner than Earth's, so winds on Mars exert much less force than winds on Earth. Time is the factor that makes Martian winds so dominant in shaping the landscape. Most forces that shape Earth's landscapes—water that erodes and moves sediments, tectonic activity that builds mountains and recycles the planet's crust, active volcanism—haven't influenced Mars much for billions of years. Sand transported by wind, even if infrequent, can whittle away Martian landscapes over that much time. Gale Crater was born when the impact of an asteroid or comet more than 3.6 billion years ago excavated a basin nearly 100 miles (160 kilometers) wide. Sediments including rocks, sand and silt later filled the basin, some delivered by rivers that flowed in from higher ground surrounding Gale. Curiosity has found evidence of that wet era from more than 3 billion years ago. A turning point in Gale's history—when net accumulation of sediments flipped to net removal by wind erosion—may have coincided with a key turning point in the planet's climate as Mars became drier, Day noted. Scientists first proposed in 2000 that the mound at the center of Gale Crater is a remnant from wind eroding what had been a totally filled basin. The new work calculates that the vast volume of material removed—about 15,000 cubic miles (64,000 cubic kilometers)—is consistent with orbital observations of winds' effects in and around the crater, when multiplied by a billion or more years. Other new research, using Curiosity, focuses on modern wind activity in Gale. The rover this month is investigating a type of sand dune that differs in shape from dunes the mission investigated in late 2015 and early 2016. Crescent-shaped dunes were the feature of the earlier campaign—the first ever up-close study of active sand dunes anywhere other than Earth. The mission's second dune campaign is at a group of ribbon-shaped linear dunes. "In these linear dunes, the sand is transported along the ribbon pathway, while the ribbon can oscillate back and forth, side to side," said Nathan Bridges, a Curiosity science team member at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The season at Gale Crater is now summer, the windiest time of year. That's the other chief difference from the first dune campaign, conducted during less-windy Martian winter. "We're keeping Curiosity busy in an area with lots of sand at a season when there's plenty of wind blowing it around," said Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory, Pasadena, California. "One aspect we want to learn more about is the wind's effect on sorting sand grains with different composition. That helps us interpret modern dunes as well as ancient sandstones." Before Curiosity heads farther up Mount Sharp, the mission will assess movement of sand particles at the linear dunes, examine ripple shapes on the surface of the dunes, and determine the composition mixture of the dune material. Images taken one day apart of the same piece of ground, including some recent pairs from the downward-looking camera that recorded the rover's landing-day descent, show small ripples of sand moving about an inch (2.5 centimeters) downwind. Meanwhile, whirlwinds called "dust devils" have been recorded moving across terrain in the crater, in sequences of afternoon images taken several seconds apart. After completing the planned dune observations and measurements, Curiosity will proceed southward and uphill toward a ridge where the mineral hematite has been identified from Mars Reconnaissance Orbiter observations. The Curiosity science team has decided to call this noteworthy feature the "Vera Rubin Ridge," commemorating Vera Cooper Rubin (1928-2016), whose astronomical observations provided evidence for the existence of the universe's dark matter. As Curiosity focuses on the sand dunes, rover engineers are analyzing results of diagnostic tests on the drill feed mechanism, which drives the drill bit in and out during the process of collecting sample material from a rock. One possible cause of an intermittent issue with the mechanism is that a plate for braking the movement may be obstructed, perhaps due to a small piece of debris, resisting release of the brake. The diagnostic tests are designed to be useful in planning the best way to resume use of the drill. The rover team is also investigating why the lens cover on Curiosity's arm-mounted Mars Hand Lens Imager (MAHLI) did not fully open in response to commands on Feb. 24. The arm has been raised to minimize risk of windborne sand reaching the lens while the cover is partially open. Diagnostic tests of the lens cover are planned this week. During the first year after Curiosity's 2012 landing in Gale Crater, the mission fulfilled its main goal by finding that the region once offered environmental conditions favorable for microbial life. The conditions in long-lived ancient freshwater Martian lake environments included all of the key chemical elements needed for life as we know it, plus a chemical source of energy that is used by many microbes on Earth. The extended mission is investigating how and when the habitable ancient conditions evolved into conditions drier and less favorable for life. This sequence of images shows a dust-carrying whirlwind, called a dust devil, on lower Mount Sharp inside Gale Crater, as viewed by NASA's Curiosity Mars Rover during the summer afternoon of the rover's 1,613rd Martian day, or sol (Feb. 18, 2017). Credit: NASA/JPL-Caltech/TAMU More information: Mackenzie Day et al. Observations of an aeolian landscape: From surface to orbit in Gale Crater, Icarus (2016). DOI: 10.1016/j.icarus.2015.09.042


News Article | November 1, 2016
Site: www.rdmag.com

A team of researchers have presented a new model for the origin of Saturn's rings based on results of computer simulations. The results of the simulations are also applicable to rings of other giant planets and explain the compositional differences between the rings of Saturn and Uranus. The findings were published on October 6 in the online version of Icarus. The lead author of the paper is HYODO Ryuki (Kobe University, Graduate School of Science), and co-authors are Professor Sébastien Charnoz (Institute de Physique du Globe/Université Paris Diderot), Professor OHTSUKI Keiji (Kobe University, Graduate School of Science), and Project Associate Professor GENDA Hidenori (Earth-Life Science Institute, Tokyo Institute of Technology). The giant planets in our solar system have very diverse rings. Observations show that Saturn's rings are made of more than 95% icy particles, while the rings of Uranus and Neptune are darker and may have higher rock content. Since the rings of Saturn were first observed in the 17th century, investigation of the rings has expanded from earth-based telescopes to spacecraft such as Voyagers and Cassini. However, the origin of the rings was still unclear and the mechanisms that lead to the diverse ring systems were unknown. The present study focused on the period called the Late Heavy Bombardment that is believed to have occurred 4 billion years ago in our solar system, when the giant planets underwent orbital migration. It is thought that several thousand Pluto-sized (one fifth of Earth's size) objects from the Kuiper belt existed in the outer solar system beyond Neptune. First the researchers calculated the probability that these large objects passed close enough to the giant planets to be destroyed by their tidal force during the Late Heavy Bombardment. Results showed that Saturn, Uranus and Neptune experienced close encounters with these large celestial objects multiple times. Next the group used computer simulations to investigate disruption of these Kuiper belt objects by tidal force when they passed the vicinity of the giant planets (see Figure 2a). The results of the simulations varied depending on the initial conditions, such as the rotation of the passing objects and their minimum approach distance to the planet. However they discovered that in many cases fragments comprising 0.1-10% of the initial mass of the passing objects were captured into orbits around the planet (see Figures 2a, b). The combined mass of these captured fragments was found to be sufficient to explain the mass of the current rings around Saturn and Uranus. In other words, these planetary rings were formed when sufficiently large objects passed very close to giants and were destroyed. The researchers also simulated the long-term evolution of the captured fragments using supercomputers at the National Astronomical Observatory of Japan. From these simulations they found that captured fragments with an initial size of several kilometers are expected to undergo high-speed collisions repeatedly and are gradually shattered into small pieces. Such collisions between fragments are also expected to circularize their orbits and lead to the formation of the rings observed today (see Figures 2b, c). This model can also explain the compositional difference between the rings of Saturn and Uranus. Compared to Saturn, Uranus (and also Neptune) has higher density (the mean density of Uranus is 1.27g cm-3, and 1.64g cm-3 for Neptune, while that of Saturn is 0.69g cm-3). This means that in the cases of Uranus (and Neptune), objects can pass within close vicinity of the planet, where they experience extremely strong tidal forces. (Saturn has a lower density and a large diameter-to-mass ratio, so if objects pass very close they will collide with the planet itself). As a result, if Kuiper belt objects have layered structures such as a rocky core with an icy mantle and pass within close vicinity of Uranus or Neptune, in addition to the icy mantle, even the rocky core will be destroyed and captured, forming rings that include rocky composition. However if they pass by Saturn, only the icy mantle will be destroyed, forming icy rings. This explains the different ring compositions. These findings illustrate that the rings of giant planets are natural by-products of the formation process of the planets in our solar system. This implies that giant planets discovered around other stars likely have rings formed by a similar process. Discovery of a ring system around an exoplanet has been recently reported, and further discoveries of rings and satellites around exoplanets will advance our understanding of their origin.


News Article | February 23, 2017
Site: phys.org

Data from the New Horizons flyby finished downloading to Earth in October, and while it will take many years for scientists to complete their inventory and model the results, early studies offer intriguing hints of its complex chemistry, perhaps even some form of pre-biological processes below Pluto's surface. Complex layers of organic haze; water ice mountains from some unknown geologic process; possible organics on the surface; and a liquid water ocean underneath—all of these features point to a world with much more vibrancy than scientists have long presumed. "The connection with astrobiology is immediate—it's right there in front of your face. You see organic materials, water and energy," said Michael Summers, a planetary scientist on the New Horizons team who specializes in the structure and evolution of planetary atmospheres. Summers has co-authored two research papers on the topic, with the first, "The Photochemistry of Pluto's Atmosphere as Illuminated by New Horizons," published in the journal Icarus in September. The second paper, "Constraints on the Microphysics of Pluto's Photochemical Haze from New Horizons Observations" is in press at the same journal. In first looking at the images of Pluto, Summers was reminded of a world he has studied for decades while working at George Mason University. Titan, an icy orange colored moon of Saturn, is the only moon in the Solar System with a substantial atmosphere and a liquid (methane) hydrological cycle. It has hydrocarbon chemistry, including ethane and methane lakes that have compounds that may be precursors to the chemistry required for life. Unlike Titan, Pluto's atmosphere is thin and sparse, with haze reaching out at least 200 kilometers (125 miles) above the surface, at least ten times higher than scientists expected. But above 30 km (19 miles) Pluto displays a similar paradox to Titan with condensation happening in a region that's too warm in temperature for haze particles to occur NASA's Cassini spacecraft saw the same oddity in the highest reaches of Titan's atmosphere (the ionosphere) at about 500 to 600 kilometers above the surface (roughly 310 or 370 miles). Through modeling, scientists determined that the condensation is partially the result of Titan's photochemistry, whereby ultraviolet sunlight breaks down methane, triggering the formation of hydrocarbons. "This haze formation is initiated in the ionosphere, where there are electrically charged particles (electrons and ions)," Summers said. "The electrons attach to the hydrocarbons and make them stick together. They become very stable, and as they fall through the atmosphere they grow by other particles sticking to them. The bigger they are, the faster they fall. On Titan, as you go down in the atmosphere the haze particles get more numerous and much larger than on Pluto" In retrospect, Summers said it shouldn't have been too much of a surprise that Pluto likely has the same process. Like Titan, it has a nitrogen atmosphere with methane as a minor component. The main difference, however, is Pluto's atmosphere is just 10 millibars at the surface, compared to Titan's 1.5 bar. (A bar is a metric unit of pressure, with 1 bar equal to 10,000 pascal units, or slightly less than the average atmospheric pressure on Earth at sea level.) The atmospheric pressure difference of the two bodies also affects the shape of the haze particles as Titan's particles taking much longer to fall to the surface and ultimately become spherical, while Pluto's haze particles fall more rapidly and grow into fractals. With the possible production of hydrocarbons and nitriles (another organic molecule) on Pluto, even more interesting pre- chemistry for life could take place, Summers said. "You can start building complex pre-biotic molecules," he said. An example is hydrogen cyanide, possibly a key molecule leading to prebiotic chemistry. What's also abundant on Titan are tholins, complex organic compounds created when the Sun's ultraviolet light strikes the haze particles. It's rare on Earth, but common on Titan and may have contributed to its orange color. There is also a reddish hue on parts of Pluto's surface, which could be from a layer of tholins, Summers said. His quick calculation estimates these tholins could be 10 to 30 meters thick, providing more organic material per square meter than a forest on Earth. This material may also change its chemical composition as cosmic rays (high-energy radiation particles) strike the surface. Intriguingly, reddish material was also spotted near Pluto's ice volcanoes, or calderas. It's possible that the dwarf planet could have a subsurface ocean similar to that suspected on Titan, Saturn's Enceladus and Jupiter's Europa. These moons, however, have a tidal source of energy within, created by orbiting their huge central planets and interacting gravitationally with other moons. Pluto is bereft of such heating, but it's possible that radioactivity in its interior could be keeping the inside liquid, Summers said. "These are the things you need for life: organics, raw material and energy," Summers said. While it's a stretch right now to say Pluto is hospitable for life, Summers said he is looking forward to doing more modeling. "I've been studying Pluto all my life, and never expected to talk about these things being there." Explore further: NASA image: Pluto's haze in bands of blue


News Article | February 15, 2017
Site: astrobiology.com

Mars was characterized by cataclysmic groundwater-sourced surface flooding that formed large outflow channels and that may have altered the climate for extensive periods during the Hesperian era. In particular, it has been speculated that such events could have induced significant rainfall and caused the formation of late-stage valley networks. We present the results of 3-D Global Climate Model simulations reproducing the short and long term climatic impact of a wide range of outflow channel formation events under cold ancient Mars conditions. We find that the most intense of these events (volumes of water up to 107km3 and released at temperatures up to 320 Kelvins) cannot trigger long-term greenhouse global warming, regardless of how favorable are the external conditions (e.g. obliquity and seasons). In any case, outflow channel formation events at any atmospheric pressure are unable to produce rainfall or significant snowmelt at latitudes below 40∘N. On the long term, for an obliquity of ∼45∘ and atmospheric pressures > 80 mbar, we find that the lake ice (formed quickly after the outflow event) is transported progressively southward through the mechanisms of sublimation and adiabatic cooling. At the same time, and as long as the initial water reservoir is not entirely sublimated, ice deposits remain in the West Echus Chasma Plateau region where hints of hydrological activity contemporaneous with outflow channel formation events have been observed. However, because the high albedo of ice drives Mars to even colder temperatures, snowmelt produced by seasonal solar forcing is difficult to attain. Comments: 67 pages, 21 figures, accepted for publication in Icarus Subjects: Earth and Planetary Astrophysics (astro-ph.EP) DOI: 10.1016/j.icarus.2017.01.024 Cite as: arXiv:1701.07886 [astro-ph.EP] (or arXiv:1701.07886v1 [astro-ph.EP] for this version) Submission history From: Martin Turbet [v1] Thu, 26 Jan 2017 21:51:03 GMT (5416kb,D) http://xxx.lanl.gov/abs/1701.07886


News Article | February 18, 2017
Site: www.cnet.com

The women who helped pioneer space travel have rocketed into the public eye thanks to the acclaimed movie "Hidden Figures". We spoke to NASA's chief historian to learn more about the remarkable true story of these pioneering mathematicians, engineers and computer scientists, and to explore how the film dramatises their struggles. (Beware of some minor spoilers.) Based on the book by Margot Lee Shetterly, the Oscar-nominated "Hidden Figures" focuses on the lives of three black American women who worked at the National Advisory Committee for Aeronautics (NACA), later renamed NASA. Katherine Johnson, played in the film by Taraji P. Henson, was a brilliant geometry expert who worked as a computer -- that is, a person who computes. Mary Jackson, played by Janelle Monae, was a mathematician and aerospace engineer. And Dorothy Vaughan, played by Oscar-nominated Octavia Spencer, was the first black supervisor at NACA and one of the first computer programmers. NASA's chief historian, Bill Barry, explains that the film, which has been nominated for a slew of awards, depicts many real events from their lives. "One thing we're frequently asked," he says, "is whether or not John Glenn actually asked for Katherine Johnson to 'check the numbers.'" The answer is yes: Glenn, the first American in orbit and later, at the age of 77, the oldest man in space, really did ask for Johnson to manually check calculations generated by IBM 7090 computers (the electronic kind) churning out numbers at Goddard Space Flight Center in Greenbelt, Maryland. Though the film shows Glenn asking for Johnson's approval from the launch pad, she was actually called in well before the launch. Calculating the output for 11 different variables to eight significant digits took a day and a half. Her calculations matched the computer's results exactly. Not only did her conclusions give Glenn and everyone else confidence in the upcoming launch, but they also proved the critical computer software was reliable. To add to the accuracy of the film, NASA consulted on the film's script, answering questions and providing photographs, documents and films for the filmmakers. NASA even loaned a few items for use as props in the movie. For example, look out for the painting on the wall of NASA's offices (pictured here over Kevin Costner's shoulder). That painting was part of a series depicting the history of flight from Icarus to the 20th century, which actually hung on the walls of the real Langley Lab in the NACA days. The paintings were in storage and in need of restoration when they were loaned to the movie and placed on set in Atlanta as a link to the real offices. The film compresses the sequence of real events to set the story around 1961, when Glenn's first mission took place. "If the film was a documentary, many of the events would have been spread out over the late 1940s through the early 1960s," says Barry. For example, a lot happened in 1958, the year NACA became NASA: Mary Jackson qualified as NASA's first black engineer, Katherine Johnson joined the newly formed Space Task Group, and segregation ended. In real life, the head of the Space Task Group was a man named Bob Gilruth. Unlike the fictional character played by Kevin Costner, he didn't dramatically take a crowbar to a restroom sign. "Desegregation of bathroom and dining facilities happened gradually and quietly over the 1950s at Langley lab," explains Barry. Langley lab was a federal facility but was located in Virginia, which had state-mandated segregation. "There was some tension between local and federal 'rules' on this issue," says Barry. Segregation effectively ended when specialised workers were distributed among offices and facilities instead of being grouped together in pools. The segregated West Computing Unit, which comprised African-American women, was eliminated in the spring of 1958. Women like Johnson, Jackson and Vaughan blazed the trail for America in space and for black women back on Earth. From the hidden figures of the past to the scientists and engineers of today, you can go to NASA's website to meet the diverse range of extraordinary people with their eyes on the stars. "Hidden Figures" is in cinemas in the UK this weekend. The Oscars take place on 26 February. Solving for XX: The industry seeks to overcome outdated ideas about "women in tech." Tech Culture: From film and television to social media and games, here's your place for the lighter side of tech.


News Article | March 2, 2017
Site: www.cnet.com

They delivered pizza by reindeer, and we did not blink. They offered us pizza-ordering tattoos and we said, "Sign me up." But now, pizza technology has gone too far. With the launch of the Pie Tops, Pizza Hut's Bluetooth-enabled food-ordering sneakers, the restaurant chain has become the modern day Icarus of fast food, shooting hoops too close to the sun. The concept is simple. You're chilling out, maxing, relaxing all cool, when the urge for a slice of pepperoni hits you. But why use one of Pizza Hut's phone- or desktop-optimised interfaces to order? Why not do it the way your grandparents did: By pressing a Bluetooth button in your geo-located, high-top sneakers? Frankly, we should have seen this coming. Fast food companies have been selling us these kinds of marketing gimmicks for so long now, we feel stupid for just wanting to get a humble slice of pie the old fashioned way. Instead, we're so deep in the cheese dreams of caffeinated ad executives selling us nostalgic cola-driven fantasies of '80s takeout, nothing means anything any more. If you're not ordering a pizza via a tattoo on your arm, then you're turning your pizza box into a DJ turntable. Fresh! Then came pizza via emoji and pizza delivery via robot or drone. But in virtually all these cases, you're getting nothing more than a gimmick. Want a drone pizza? Well, that trial delivered a handful of pizzas in a carefully curated marketing "activation" in one town in New Zealand. Want a pizza DJ deck? Only five were ever made. And if you want your pizza to be delivered by a rolling robot, it'll probably be cold by the time it arrives -- that prototype hasn't even left the lab after a flashy unveiling in Australia last year. The Pie Tops are the same. Created by custom sneaker brand the Shoe Surgeon, just 64 pairs of these high tops have been made ahead of Pizza Christmas (also known as March Madness). So will you buy a pair of pizza shoes? Probably not. But dammit if you won't think of the Official Pizza of the NCAA every time you watch college basketball, cloaked in the warm, cheesy nostalgia of the '80s. That's some excellent marketing right there. And all Pizza Hut had to do was make 64 pairs of sneakers. It's Complicated: This is dating in the age of apps. Having fun yet? These stories get to the heart of the matter. Batteries Not Included: The CNET team reminds us why tech is cool.


News Article | February 21, 2017
Site: phys.org

(Phys.org)—A pair of researchers with the Physical Research Laboratory in India studying data sent back from NASA's Mars Atmosphere and Volatile Evolution (MAVEN) probe has found possible evidence of the development of rings around the planet. In their paper published in the journal Icarus, Jayesh Pabari and P. J. Bhalodi describe the data, what the probe has measured, and the likelihood that some of the dust that surrounds Mars may one day accumulate into a set of rings encircling the planet. Scientists have speculated for many years that one day (20 to 70 million years from now), Mars will have rings around its equator similar to those seen around Saturn today—this is because the material that makes up its two biggest moons is unstable and likely to result in the moons tearing apart as they are drawn closer to the planet by its gravity. But now, it appears that the process might already have begun. In this new effort, the researchers found evidence in data from MAVEN that suggests at least some of the dust encircling the planet came from one or both of its biggest moons, Phobos and Deimos. Data from MAVEN had already shown that there was a cloud of dust surrounding Mars, but it is still not clear how big the particles are. Space scientists believe that most of the dust that is thrown into the atmosphere when the planet and its moons are struck by asteroids is composed of particles so tiny that they are carried away by the solar wind. The new analysis by Pabari and Bhalodi, which compared dust and rock particles found in the Martian upper atmosphere with those predicted by models, showed that most of the dust in the cloud was interplanetary. But there was also a small component (approximately 0.6 percent) that appeared likely to have come from one of the two moons. The researchers are quick to point out that spotting moon particles in an outer atmospheric cloud is not evidence of proto-ring development, but suggest it is possible. They note it will not be possible to determine if such activity is truly occurring until a probe is sent to Mars that is capable of fully analyzing material in the dust cloud. More information: J.P. Pabari et al, Estimation of micrometeorites and satellite dust flux surrounding Mars in the light of MAVEN results, Icarus (2017). DOI: 10.1016/j.icarus.2017.01.023 Recently, MAVEN observed dust around Mars from ∼150 km to ∼1000 km and it is a puzzling question to the space scientists about the presence of dust at orbital altitudes and about its source. A continuous supply of dust from various sources could cause existence of dust around Mars and it is expected that the dust could mainly be from either the interplanetary source or the Phobos/Deimos. We have studied incident projectiles or micrometeorites at Mars using the existing model, in this article. Comparison of results with the MAVEN results gives a new value of the population index S, which is reported here. The index S has been referred in a power law model used to describe the number of impacting particles on Mars. In addition, the secondary ejecta from natural satellites of Mars can cause a dust ring or torus around Mars and remain present for its lifetime. The dust particles whose paths are altered by the solar wind over its lifetime, could present a second plausible source of dust around Mars. We have investigated escaping particles from natural satellites of Mars and compared with the interplanetary dust flux estimation. It has been found that flux rate at Mars is dominated (∼2 orders of magnitude higher) by interplanetary particles in comparison with the satellite originated dust. It is inferred that the dust at high altitudes of Mars could be interplanetary in nature and our expectation is in agreement with the MAVEN observation. As a corollary, the mass loss from Martian natural satellites is computed based on the surface erosion by incident projectiles.


Evolution by natural selection depends on the relationship between individual traits and fitness. Variation in individual fitness can result from habitat (territory) quality and individual variation. Individual quality and specialization can have a deep impact on fitness, yet in most studies on territorial species the quality of territory and individuals are confused. We aimed to determine if variation in breeding success is better explained by territories, individual quality or a combination of both. We analysed the number of fledglings and the breeding quality index (the difference between the number of fledglings of an individual/breeding pair and the average number of fledglings of the monitored territories in the same year) as part of a long term (16 years) peregrine falcon (Falco peregrinus ) monitoring program with identification of individuals. Using individual and territory identities as correlates of quality, we built Generalised Linear Models with Mixed effects, in which random factors depicted different hypotheses for sources of variation (territory/individual quality) in the reproductive success of unique breeding pairs, males and females, and assessed their performance. Most evidence supported the hypothesis that variation in breeding success is explained by individual identity, particularly male identity, rather than territory. There is also some evidence for inter year variations in the breeding success of females and a territory effect in the case of males. We argue that, in territorial species, individual quality is a major source of variation in breeding success, often masked by territory. Future ecological and conservation studies on habitat use should consider and include the effect of individuals, in order to avoid misleading results. © 2014 Zabala, Zuberogoitia.


A system and machine-implemented method is provided for managing broadcast of content to webpages. In one embodiment, a set of graphical elements is displayed, the display of graphical elements including selectable elements for channels, campaigns, and uniform resource locators (URLs). A set of selections is received based on the set of graphical elements. A set of webpages is identified based on the set of selections received. The set of webpages corresponds to URLs. Each of the webpages includes embed codes that enables the webpages to receive the broadcast of content. The broadcast of content to the identified set of webpages may be controlled. Content may include one or more of advertising content, audio data, video data, multimedia content, interactive media, gaming content, and application data.


News Article | February 28, 2017
Site: news.yahoo.com

Mars might be lifeless, but it’s far from silent. Wind has shaped the Red Planet for billions of years, carving out valleys and mountains on its rugged surface. Now, NASA’s Curiosity rover has captured staggering footage of so-called dust devils carrying sand across the planet. The data is helping scientists to untangle one of Mars’s most puzzling phenomena: a layered mountain in the middle of an impact crater. The mysterious feature is explained by evidence of long-term patterns and rates of wind erosion captured by Curiosity, researchers said. “The orbiter perspective gives us the bigger picture ― on all sides of Mount Sharp and the regional context for Gale Crater. We combine that with the local detail and ground-truth we get from the rover,” said Mackenzie Day lead author of a research report in the journal Icarus about wind’s role in Gale crater. Today, Mount Sharp shapes the wind. But in the past, wind shaped the mountain, according the footage relayed by Curiosity. It might look dramatic, but wind on Mars is much less forceful than it is on Earth, as the Martian atmosphere is 100 times thinner than our own. But over billions of years, it’s had quite an impact on the planet, gradually shaping and reshaping its desert landscape. An outcrop with fine layers of rock The sand which formed these finely layered rocks were deposited by wind long ago as dunes migrated Sloping buttes and layered outcrops in the Murray Buttes region

Loading Icarus collaborators
Loading Icarus collaborators