Sunday, June 30, 2013
Saturday, June 29, 2013
Aviation Week notes the three tiered approach the world has to stealth combatant aircraft. Stealth manned aircraft, stealthy drones and reduced RCS aircraft. Europe is going with reduced RCS manned aircraft and stealthy drones. Russia is going with stealthy and nonstealthy manned aircraft (with big question mark about its unmanned efforts). China is going stealthy all the way around, much like the US, (or as much of this the US can afford).
The space to watch is probably the US Navy. My guess would be you will see one or two wings of UCLASS UCAVs (probably X-47B derived). Then a couple wings of F-35Cs. You're going to have a wing of F/A-18Gs. The remainder of the fixed wing aircraft will be F/A-18E/Fs until around 2030. Then either it will be another replacement stealthy manned aircraft or UCAV.
At any rate, compare and contrast the Russian T-50/PAK-FA vs the American F-22 underbellies. Its so far from clean, which is necessary for stealth, I'm shocked. Is that an ugly weld I see on the Russian?Wow. Just plain wow.
Friday, June 28, 2013
This is going to annoy Noel. A lot.
Noel and I have been discussing the Robopocalypse in email for some time. Carlos, James and Doug have also been participants, for that matter. However, the basic thought has been whether or not the coming of automata, computer driven automata, will be a problem for people, especially for Americans (the rest of you, too, but we're both yanqi, and somewhat nationalist, so we're viewing our tribe first).
Yes, Virginia, the droids are going to take a lot of jobs. The argument is whether or not this is a bad thing (Noel, yes. Me, no). And whether or not the Singularity style uploads or their equivalent will allow force obsolesce of even the creative class or insight driven jobs (Noel, worried. Me, not concerned in the least; why is for a post after the holidays).
However, one point Noel makes very, very well is with the Robopocalypse, labor in the sense of manufacturing, construction, many basic service jobs, etc will be going away. Labor will be replaced by capital. This helps divorce productivity from population size. So long as you have the money to buy the equipment, the number of people running it will be quite low and wages will not dominate. Why send it off to China (originally for the wage differential), when the machines will cost the same here or there and you do not have transport costs for the end goods.
Now, this has some concerns (lower employment for production, even for many, many services) and how to solve that is something to be addressed. However, that's not the question I am going to address here. Its not the Crazy Thought.
If it takes $ to buy the machines of the Robopocalypse and it grows the economy greatly, it would seem to follow the more $ you have, the more you are able to build out and have the greater production and economic growth in the sense of lower level services.
The United States is the wealthiest nation in the world. Our economy is second to none and the part of the reason we're 'losing ground' to China (and in the future India) is their numerical superiority: if they had the same percentage of middle class, they'd have far, far more folks which to draw their creative class from and work the jobs we have, etc. And they'll do it for less for some time.
So. We're richer. Those machines cost $. Those machines negate China's advantage. or India's.
Seen the crazy thought yet?
If we, as in the United States, wanted to stay on top of the heap in the 21st and possibly later centuries, the Robopocalypse seems like a damned good way.
Influence of the Amazon River development and constriction of the Central American Seaway on Middle/Late Miocene oceanic conditions at the Ceara Rise
1. S. Heinrich (a)
2. K.A.F. Zonneveld (a, b)
a. Department of Geosciences, University of Bremen, P.O. Box 330 440, D-28334 Bremen, Germany
b. MARUM, Center for Marine environmental Sciences, University of Bremen, Leobener Straße, D-28359 Bremen, Germany
Sediment samples from ODP 154 Site 926A (Ceara Rise, western equatorial Atlantic Ocean) spanning the Neogene from 12.8 to 9.2 Ma were investigated on their calcareous dinoflagellate contents to better understand the oceanographic changes in relation to the closure of the Central American Seaway and the development of the Amazon River. Intervals with increased cyst accumulation rates and dissolution sensitive species occur from 12.4 Ma onward. They correspond to periods of enhanced North Atlantic Deep Water production indicating the presence of this water mass at the research site during these intervals. This suggests that pulses of North Atlantic Deep waters sporadically flew into the South Atlantic related to uplift phases of the Panama Sill.
At about 11.2 Ma the first appearance of Leonella granifera indicates river influence at the sample site. This first indication of river influence in the western equatorial Atlantic can be linked to the developing Amazon River. The cyst association changes at about 11.2 Ma from almost monospecific to highly diverse and the permanent presence and increased abundance of L. granifera suggests that river waters were able to reach the study site by now, probably as a result of the southward flowing North Brazil Current. After 10.5 Ma the cyst association indicates a decrease in Amazon influence at Site 926A. This change can be correlated to a reducing inflow of Pacific waters through the Central American Seaway leading to a reverse of the North Brazil Current to its modern northwards flow pattern.
Psittacosaurus, the 'parrot dinosaur' is known from more than 1000 specimens from the Cretaceous, 100 million years ago, of China and other parts of east Asia. As part of his PhD thesis at the University of Bristol, Qi Zhao, now on the staff of the Institute for Vertebrate Paleontology in Beijing, carried out the intricate study on bones of babies, juveniles and adults.
Dr Zhao said: "Some of the bones from baby Psittacosaurus were only a few millimetres across, so I had to handle them extremely carefully to be able to make useful bone sections. I also had to be sure to cause as little damage to these valuable specimens as possible."
With special permission from the Beijing Institute, Zhao sectioned two arm and two leg bones from 16 individual dinosaurs, ranging in age from less than one year to 10 years old, or fully-grown. He did the intricate sectioning work in a special palaeohistology laboratory in Bonn, Germany.
The one-year-olds had long arms and short legs, and scuttled about on all fours soon after hatching. The bone sections showed that the arm bones were growing fastest when the animals were ages one to three years. Then, from four to six years, arm growth slowed down, and the leg bones showed a massive growth spurt, meaning they ended up twice as long as the arms, necessary for an animal that stood up on its hind legs as an adult.
Professor Xing Xu of the Beijing Institute, one of Dr Zhao's thesis supervisors, said: "This remarkable study, the first of its kind, shows how much information is locked in the bones of dinosaurs. We are delighted the study worked so well, and see many ways to use the new methods to understand even more about the astonishing lives of the dinosaurs."
Experimental tumbling of echinoderms – taphonomic patterns and implications
1. Przemysław Gorzelak (a)
2, Mariusz A. Salamon (b)
a. Department of Biogeology, Institute of Paleobiology, Polish Academy of Sciences, Twarda Str. 51/55, 00–818 Warsaw, Poland
b. University of Silesia, Faculty of Earth Sciences, Department of Palaeontology and Biostratigraphy, Będzińska Str. 60, 41–200 Sosnowiec, Poland
Despite a wide array of published actualistic studies on echinoderm taphonomy the detailed pattern of decay and disarticulation of their skeletons is still not well understood. Here we provide results of tumbling experiments using a rotating barrel filled with artificial seawater and medium-sized quartz sand to mimic physical forces experienced by echinoderms during trasportation in high-energy conditions. In particular, we determined semi-quantitatively transportation-induced rates and patterns of damage and disintegration of freshly killed ophiuroid, asteroid and crinoid skeletons that were not allowed to decay initially. Our experiments showed that echinoderm specimens disintegrated in a characteristic sequence toward an increase of the degree of disarticulation, abrasion and roundness or thinness of echinoderm ossicles. The sequence of disintegration in crinoids began with the partial disintegration of distal arms after 2 hrs (a time equivalent to ~ 1 km of transport). The initial split of ophiuroid and asteroid arms and crinoid cirri occurred after 24 hrs (~ 12 km) and complete destruction of the asteroid mouth and ophiuroid disc area occurred after 72 hrs (~ 36 km). The duration of transport necessary to promote initial fragmentation in asteroid and ophiuroid arms and crinoid cirri into isolated ossicles was 120 hrs (~ 60 km). The complete disarticulation of crinoid, ophiuroid and asteroid arms and crinoid cirri occurred after 312 hrs (~ 156 km) and 408 hrs (~ 204 km), respectively. Although it has been argued that the quality of preservation can be a poor index of post-mortem transport, echinoderms allowed limited initial decay in the presence of rapid and relatively constant physical disturbance, an approximation of the distance of transport can be made.
Our data demonstrate that articulated ossicles can remain for several days, sufficient time for long (even a few hundred km) transporation. This finding illustrates that articulated echinoderm remains do not necessarily imply low energy and highlights the importance of a reliable discrimination of autochthonous and allochthonous components of fossil echinoderm assemblages. Application of isolated fossil echinoderm ossicles in e.g. paleoenvironmental and paleoecological reconstructions may lead to serious misinterpretations and should be supplemented by observations of abrasion traces.
Gemini Observatory's Planet-Finding Campaign finds that, around many types of stars, distant gas-giant planets are rare and prefer to cling close to their parent stars. The impact on theories of planetary formation could be significant.
Finding extrasolar planets has become so commonplace that it seems astronomers merely have to look up and another world is discovered. However, results from Gemini Observatory's recently completed Planet-Finding Campaign – the deepest, most extensive direct imaging survey to date – show the vast outlying orbital space around many types of stars is largely devoid of gas-giant planets, which apparently tend to dwell close to their parent stars.
"It seems that gas-giant exoplanets are like clinging offspring," says Michael Liu of the University of Hawaii's Institute for Astronomy and leader of the Gemini Planet-Finding Campaign. "Most tend to shun orbital zones far from their parents. In our search, we could have found gas giants beyond orbital distances corresponding to Uranus and Neptune in our own Solar System, but we didn't find any." The Campaign was conducted at the Gemini South telescope in Chile, with funding support for the team from the National Science Foundation and NASA. The Campaign's results, Liu says, will help scientists better understand how gas-giant planets form, as the orbital distances of planets are a key signature that astronomers use to test exoplanet formation theories.
Eric Nielsen of the University of Hawaii, who leads a new paper about the Campaign's search for planets around stars more massive than the Sun, adds that the findings have implications beyond the specific stars imaged by the team. "The two largest planets in our Solar System, Jupiter and Saturn, are huddled close to our Sun, within 10 times the distance between the Earth and Sun," he points out. "We found that this lack of gas-giant planets in more distant orbits is typical for nearby stars over a wide range of masses."
Two additional papers from the Campaign will be published soon and reveal similar tendencies around other classes of stars. However, not all gas-giant exoplanets snuggle so close to home. In 2008, astronomers using the Gemini North telescope and W.M. Keck Observatory on Hawaii's Mauna Kea took the first-ever direct images of a family of planets around the star HR 8799, finding gas-giant planets at large orbital separations (about 25-70 times the Earth-Sun distance). This discovery came after examining only a few stars, suggesting such large-separation gas giants could be common. The latest Gemini results, from a much more extensive imaging search, show that gas-giant planets at such distances are in fact uncommon.
Liu sums up the situation this way: "We've known for nearly 20 years that gas-giant planets exist around other stars, at least orbiting close-in. Thanks to leaps in direct imaging methods, we can now learn how far away planets can typically reside. The answer is that they usually avoid significant areas of real estate around their host stars. The early findings, like HR 8799, probably skewed our perceptions."
Body vs trace fossil evidence
Contemporaneous Trace and Body Fossils from a Late Pleistocene Lakebed in Victoria, Australia, Allow Assessment of Bias in the Fossil Record
1. Aaron Bruce Camens (a)
2. Stephen Paul Carey (b)
a. Biological Sciences, Flinders University, Bedford Park, Australia
b. Centre for Environmental Management, School of Science, Information Technology and Engineering, University of Ballarat, Ballarat, Australia
The co-occurrence of vertebrate trace and body fossils within a single geological formation is rare and the probability of these parallel records being contemporaneous (i.e. on or near the same bedding plane) is extremely low. We report here a late Pleistocene locality from the Victorian Volcanic Plains in south-eastern Australia in which demonstrably contemporaneous, but independently accumulated vertebrate trace and body fossils occur. Bite marks from a variety of taxa are also present on the bones. This site provides a unique opportunity to examine the biases of these divergent fossil records (skeletal, footprints and bite marks) that sampled a single fauna. The skeletal record produced the most complete fauna, with the footprint record indicating a markedly different faunal composition with less diversity and the feeding traces suggesting the presence, amongst others, of a predator not represented by either the skeletal or footprint records. We found that the large extinct marsupial predator Thylacoleo was the only taxon apparently represented by all three records, suggesting that the behavioral characteristics of large carnivores may increase the likelihood of their presence being detected within a fossil fauna. In contrast, Diprotodon (the largest-ever marsupial) was represented only by trace fossils at this site and was absent from the site's skeletal record, despite its being a common and easily detected presence in late Pleistocene skeletal fossil faunas elsewhere in Australia. Small mammals absent from the footprint record for the site were represented by skeletal fossils and bite marks on bones.
If construction projects in SF are any sign of the state of the economy, then things are definitely turning around. This one is much prettier than the current and other soon to be towers on Rincon. IMAAO.
Secular changes at the Earth's surface; evidence from palaeosols, some sedimentary rocks, and palaeoclimatic perturbations of the Proterozoic EonAuthor:1. Grant M. Young (a)Affiliation:a. Department of Earth Sciences, Western University, London, Ontario, Canada N6A 5B7Abstract:Secular changes in surficial processes and products are closely linked to plate tectonics, atmospheric composition, solar evolution and climate. Most siliciclastic sediments and rocks are derived from weathering profiles rather than directly from older rocks. Many palaeosols older than ~ 2.2 Ga show depletion in Fe(T), whereas in younger palaeosols, and modern soils, Fe is virtually immobile. This is thought to reflect the accumulation of free oxygen in the Earth's atmosphere, as is the ‘disappearance’ of iron formations after about 1.8 Ga. The temporal distribution of mature siliciclastic sedimentary rocks containing detrital pyrite and uraninite, and the subsequent appearance of fluvial and shallow marine red beds provide compelling evidence for oxygenation in early Palaeoproterozoic times. During periods of supercontinentality, especially at low palaeolatitudes, enhanced weathering of exposed rock surfaces led to production of thick, extensive quartzarenites, some of which are associated with glaciogenic rocks. Intense weathering during periods of supercontinentality would have decreased atmospheric CO2, leading to extensive glaciations near the beginning and end of the Proterozoic Eon, and initiating a feedback loop that resulted in strong climatic oscillations until continental break-up brought stability to the climatic regime. It has been proposed that atmospheric oxygenation took place during warm climatic episodes between these glaciations when abundant nutrients were flushed into the oceans, stimulating unprecedented cyanobacterial blooms. Although many other supercontinents have been proposed, these unusual climatic conditions probably reflect rare critical relationships among solar luminosity, atmospheric composition and palaeolatitudinal distribution of continental lithosphere. Reappearance of iron formations associated with some Neoproterozoic glaciations may be explained by hydrothermal activity in semi-isolated rift basins.
Thursday, June 27, 2013
Comparative Biomechanical Modeling of Metatherian and Placental Saber-Tooths: A Different Kind of Bite for an Extreme Pouched Predator
1. Stephen Wroe (a,b)
2. Uphar Chamoli (b,c)
3. William C. H. Parr (b)
4. Philip Clausen (a)
5. Ryan Ridgely (d)
6. Lawrence Witmer (d)
a. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
b. School of Engineering, University of Newcastle, Callaghan, NSW, Australia
c. St. George Clinical School, University of New South Wales, Sydney, NSW, Australia
d. Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
Questions surrounding the dramatic morphology of saber-tooths, and the presumably deadly purpose to which it was put, have long excited scholarly and popular attention. Among saber-toothed species, the iconic North American placental, Smilodon fatalis, and the bizarre South American sparassodont, Thylacosmilus atrox, represent extreme forms commonly forwarded as examples of convergent evolution. For S. fatalis, some consensus has been reached on the question of killing behaviour, with most researchers accepting the canine-shear bite hypothesis, wherein both head-depressing and jaw closing musculatures played a role in delivery of the fatal bite. However, whether, or to what degree, T. atrox may have applied a similar approach remains an open question. Here we apply a three-dimensional computational approach to examine convergence in mechanical performance between the two species. We find that, in many respects, the placental S. fatalis (a true felid) was more similar to the metatherian T. atrox than to a conical-toothed cat. In modeling of both saber-tooths we found that jaw-adductor-driven bite forces were low, but that simulations invoking neck musculature revealed less cranio-mandibular stress than in a conical-toothed cat. However, our study also revealed differences between the two saber-tooths likely reflected in the modus operandi of the kill. Jaw-adductor-driven bite forces were extremely weak in T. atrox, and its skull was even better-adapted to resist stress induced by head-depressors. Considered together with the fact that the center of the arc described by the canines was closer to the jaw-joint in Smilodon, our results are consistent with both jaw-closing and neck musculature playing a role in prey dispatch for the placental, as has been previously suggested. However, for T. atrox, we conclude that the jaw-adductors probably played no major part in the killing bite. We propose that the metatherian presents a more complete commitment to the already extreme saber-tooth ‘lifestyle’.
The movie, Aliens, has been credited with greatly influencing the attempt to create a lot of the technology which was explored around 2000: OICW vs the Pulse Rifle, the health and video feeds on the Colonial Marines vs Land Warrior, etc. One blog stated this video implies Avatar and halo influences instead.
Truthfully, the video is very, very conservative.
The one kneeling while doing the install of NERSC's first Cray-1 supercomputer back in 1978 is downstairs installing NERSC's newest supercomputer, or rather the expansion to it, yes, a cray. He's one of the longest serving Cray employees. He's been at Cray for 36 years. He did the install above after his first year at Cray.
We're honored to have him back.
If you watch, you might see him.
All stars begin their lives in groups. Most stars, including our Sun, are born in small, benign groups that quickly fall apart. Others form in huge, dense swarms that survive for billions of years as stellar clusters. Within such rich and dense clusters, stars jostle for room with thousands of neighbors while strong radiation and harsh stellar winds scour interstellar space, stripping planet-forming materials from nearby stars.
It would thus seem an unlikely place to find alien worlds. Yet 3,000 light-years from Earth, in the star cluster NGC 6811, astronomers have found two planets smaller than Neptune orbiting Sun-like stars. The discovery, published in the journal Nature, shows that planets can develop even in crowded clusters jam-packed with stars.
"Old clusters represent a stellar environment much different than the birthplace of the Sun and other planet-hosting field stars," says lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics (CfA). "And we thought maybe planets couldn't easily form and survive in the stressful environments of dense clusters, in part because for a long time we couldn't find them."
The two new alien worlds appeared in data from NASA's Kepler spacecraft. Kepler hunts for planets that transit, or cross in front of, their host stars. During a transit, the star dims by an amount that depends on the size of the planet, allowing the size to be determined. Kepler-66b and Kepler-67b are both less than three times the size of Earth, or about three-fourths the size of Neptune (mini-Neptunes).
Of the more than 850 known planets beyond our solar system, only four - all similar to or greater than Jupiter in mass - were found in clusters. Kepler-66b and -67b are the smallest planets to be found in a star cluster, and the first cluster planets seen to transit their host stars, which enables the measurement of their sizes.
Meibom and his colleagues have measured the age of NGC 6811 to be one billion years. Kepler-66b and Kepler-67b therefore join a small group of planets with precisely determined ages, distances, and sizes.
Considering the number of stars observed by Kepler in NGC 6811, the detection of two such planets implies that the frequency and properties of planets in open clusters are consistent with those of planets around field stars (stars not within a cluster or association) in the Milky Way galaxy.
"These planets are cosmic extremophiles," says Meibom. "Finding them shows that small planets can form and survive for at least a billion years, even in a chaotic and hostile environment."
Secular changes in sedimentation systems and sequence stratigraphy
1. Patrick G. Eriksson (a)
2. Santanu Banerjee (b)
3. Octavian Catuneanu (c)
4. Patricia L. Corcoran (d)
5. Kenneth A. Eriksson (e)
6. Eric E. Hiatt (f)
7. Marc Laflamme (g, 1)
8. Nils Lenhardt (a)
9. Darrel G.F. Long (h)
10. Andrew D. Miall (i)
11. Michael V. Mints (j)
12. Peir K. Pufahl (k)
13. Subir Sarkar (l)
14. Edward L. Simpson (m)
15. George E. Williams (n)
a. Department of Geology, University of Pretoria, Pretoria 0002, South Africa
b. Department of Earth Sciences, IIT Bombay, Pawai, Mumbai 400 076, India
c. Department of Earth and Atmospheric Sciences, 1–26 Earth Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E3
d. Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7
e. Department of Geological Sciences, Virginia Tech., Blacksburg, VA 24061, USA
f. Geology Department, University of Wisconsin, Oshkosh, Oshkosh, Wisconsin, 54901-8649, USA
g. Department of Paleobiology, Smithsonian Institution, Washington DC, 20013-7012, USA
h. Department of Earth Sciences, Laurentian University, Sudbury, Ontario, Canada P3E 2C6
i. Department of Geology, University of Toronto, 22 Russell Street, Toronto, Ontario, Canada M5S 3B1
j. Laboratory of the Early Precambrian Tectonics, Geological Institute of the Russian Academy of Sciences, Pyzhevsky Street 7, 109017 Moscow, Russia
k. Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6
l. Department of Geological Sciences, Jadavpur University, Kolkata 700 032, India
m. Department of Physical Sciences, Kutztown University of Pennsylvania, Kutztown, PA 19530, USA
n. Geology and Geophysics, University of Adelaide, Adelaide, SA 5005, Australia
The ephemeral nature of most sedimentation processes and the fragmentary character of the sedimentary record are of first-order importance. Despite a basic uniformity of external controls on sedimentation resulting in markedly similar lithologies, facies, facies associations and depositional elements within the rock record across time, there are a number of secular changes, particularly in rates and intensities of processes that resulted in contrasts between preserved Precambrian and Phanerozoic successions. Secular change encompassed (1) variations in mantle heat, rates of plate drift and of continental crustal growth, the gravitational effects of the Moon, and in rates of weathering, erosion, transport, deposition and diagenesis; (2) a decreasing planetary rotation rate over time; (3) no vegetation in the Precambrian, but prolific microbial mats, with the opposite pertaining to the Phanerozoic; (4) the long-term evolution of the hydrosphere–atmosphere–biosphere system. A relatively abrupt and sharp turning point was reached in the Neoarchaean, with spikes in mantle plume flux and tectonothermal activity and possibly concomitant onset of the supercontinent cycle. Substantial and irreversible change occurred subsequently in the Palaeoproterozoic, whereby the dramatic change from reducing to oxidizing volcanic gases ushered in change to an oxic environment, to be followed at ca. 2.4–2.3 Ga by the “Great Oxidation Event” (GOE); rise in atmospheric oxygen was accompanied by expansion of oxygenic photosynthesis in the cyanobacteria. A possible global tectono-thermal “slowdown” from ca. 2.45–2.2 Ga may have separated a preceding plate regime which interacted with a higher energy mantle from a ca. 2.2–2.0 Ga Phanerozoic-style plate tectonic regime; the “slowdown” period also encompassed the first known global-scale glaciation and overlapped with the GOE. While large palaeodeserts emerged from ca. 2.0–1.8 Ga, possibly associated with the evolution of the supercontinent cycle, widespread euxinia by ca. 1.85 Ga ushered in the “boring billion” year period. A second time of significant and irreversible change, in the Neoproterozoic, saw a second major oxidation event and several low palaeolatitude Cryogenian (740–630 Ma) glaciations. With the veracity of the “Snowball Earth” model for Neoproterozoic glaciation being under dispute, genesis of Pre-Ediacaran low-palaeolatitude glaciation remains enigmatic. Ediacaran (635–542 Ma) glaciation with a wide palaeolatitudinal range contrasts with the circum-polar nature of Phanerozoic glaciation. The observed change from low latitude to circum-polar glaciation parallels advent and diversification of the Metazoa and the Neoproterozoic oxygenation (ca. 580 Ma), and was succeeded by the Ediacaran–Cambrian transition which ushered in biomineralization, with all its implications for the chemical sedimentary record.
Wednesday, June 26, 2013
For most terrestrial life on Earth, oxygen is necessary for survival. But the planet's atmosphere did not always contain this life-sustaining substance, and one of science's greatest mysteries is how and when oxygenic photosynthesis—the process responsible for producing oxygen on Earth through the splitting of water molecules—first began. Now, a team led by geobiologists at the California Institute of Technology (Caltech) has found evidence of a precursor photosystem involving manganese that predates cyanobacteria, the first group of organisms to release oxygen into the environment via photosynthesis.
The findings, outlined in the June 24 early edition of the Proceedings of the National Academy of Sciences (PNAS), strongly support the idea that manganese oxidation—which, despite the name, is a chemical reaction that does not have to involve oxygen—provided an evolutionary stepping-stone for the development of water-oxidizing photosynthesis in cyanobacteria.
"Water-oxidizing or water-splitting photosynthesis was invented by cyanobacteria approximately 2.4 billion years ago and then borrowed by other groups of organisms thereafter," explains Woodward Fischer, assistant professor of geobiology at Caltech and a coauthor of the study. "Algae borrowed this photosynthetic system from cyanobacteria, and plants are just a group of algae that took photosynthesis on land, so we think with this finding we're looking at the inception of the molecular machinery that would give rise to oxygen."
Photosynthesis is the process by which energy from the sun is used by plants and other organisms to split water and carbon dioxide molecules to make carbohydrates and oxygen. Manganese is required for water splitting to work, so when scientists began to wonder what evolutionary steps may have led up to an oxygenated atmosphere on Earth, they started to look for evidence of manganese-oxidizing photosynthesis prior to cyanobacteria. Since oxidation simply involves the transfer of electrons to increase the charge on an atom—and this can be accomplished using light or O2—it could have occurred before the rise of oxygen on this planet.
"Manganese plays an essential role in modern biological water splitting as a necessary catalyst in the process, so manganese-oxidizing photosynthesis makes sense as a potential transitional photosystem," says Jena Johnson, a graduate student in Fischer's laboratory at Caltech and lead author of the study.
To test the hypothesis that manganese-based photosynthesis occurred prior to the evolution of oxygenic cyanobacteria, the researchers examined drill cores (newly obtained by the Agouron Institute) from 2.415 billion-year-old South African marine sedimentary rocks with large deposits of manganese.
Manganese is soluble in seawater. Indeed, if there are no strong oxidants around to accept electrons from the manganese, it will remain aqueous, Fischer explains, but the second it is oxidized, or loses electrons, manganese precipitates, forming a solid that can become concentrated within seafloor sediments.
"Just the observation of these large enrichments—16 percent manganese in some samples—provided a strong implication that the manganese had been oxidized, but this required confirmation," he says.
To prove that the manganese was originally part of the South African rock and not deposited there later by hydrothermal fluids or some other phenomena, Johnson and colleagues developed and employed techniques that allowed the team to assess the abundance and oxidation state of manganese-bearing minerals at a very tiny scale of 2 microns.
"And it's warranted—these rocks are complicated at a micron scale!" Fischer says. "And yet, the rocks occupy hundreds of meters of stratigraphy across hundreds of square kilometers of ocean basin, so you need to be able to work between many scales—very detailed ones, but also across the whole deposit to understand the ancient environmental processes at work."
Using these multiscale approaches, Johnson and colleagues demonstrated that the manganese was original to the rocks and first deposited in sediments as manganese oxides, and that manganese oxidation occurred over a broad swath of the ancient marine basin during the entire timescale captured by the drill cores.
"It's really amazing to be able to use X-ray techniques to look back into the rock record and use the chemical observations on the microscale to shed light on some of the fundamental processes and mechanisms that occurred billions of years ago," says Samuel Webb, coauthor on the paper and beam line scientist at the SLAC National Accelerator Laboratory at Stanford University, where many of the study's experiments took place. "Questions regarding the evolution of the photosynthetic pathway and the subsequent rise of oxygen in the atmosphere are critical for understanding not only the history of our own planet, but also the basics of how biology has perfected the process of photosynthesis."
Once the team confirmed that the manganese had been deposited as an oxide phase when the rock was first forming, they checked to see if these manganese oxides were actually formed before water-splitting photosynthesis or if they formed after as a result of reactions with oxygen. They used two different techniques to check whether oxygen was present. It was not—proving that water-splitting photosynthesis had not yet evolved at that point in time. The manganese in the deposits had indeed been oxidized and deposited before the appearance of water-splitting cyanobacteria. This implies, the researchers say, that manganese-oxidizing photosynthesis was a stepping-stone for oxygen-producing, water-splitting photosynthesis.
"I think that there will be a number of additional experiments that people will now attempt to try and reverse engineer a manganese photosynthetic photosystem or cell," Fischer says. "Once you know that this happened, it all of a sudden gives you reason to take more seriously an experimental program aimed at asking, 'Can we make a photosystem that's able to oxidize manganese but doesn't then go on to split water? How does it behave, and what is its chemistry?' Even though we know what modern water splitting is and what it looks like, we still don't know exactly how it works. There is a still a major discovery to be made to find out exactly how the catalysis works, and now knowing where this machinery comes from may open new perspectives into its function—an understanding that could help target technologies for energy production from artificial photosynthesis. "
Next up in Fischer's lab, Johnson plans to work with others to try and mutate a cyanobacteria to "go backwards" and perform manganese-oxidizing photosynthesis. The team also plans to investigate a set of rocks from western Australia that are similar in age to the samples used in the current study and may also contain beds of manganese. If their current study results are truly an indication of manganese-oxidizing photosynthesis, they say, there should be evidence of the same processes in other parts of the world.
Reinterpretation of the cranial morphology of Utatsusaurus hataii (Ichthyopterygia) (Osawa Formation, Lower Triassic, Miyagi, Japan) and its systematic implications
1. Robin S. Cuthbertson (a)
2. Anthony P. Russell (a)
3. Jason S. Anderson (b)
a. Department of Biological Sciences , University of Calgary , 2500 University Drive, Calgary , Alberta , Canada , T2N 1N4
b. Department of Comparative Biology and Experimental Medicine , University of Calgary, 3330 Hospital Drive , Calgary , Alberta , Canada , T2N 4N1
Utatsusaurus hataii is an early member of Ichthyopterygia from the Osawa Formation (Lower Triassic) of Miyagi Prefecture, Japan. Although the holotype of the species lacks a well-preserved cranium, UHR 30691 preserves a near-complete skull and may be referred to Utatsusaurus based on a similar geologic occurrence and, most importantly, the following shared features with the holotype: subthecodont tooth implantation; the presence of distomesially compressed tooth crowns; a humerus that is longer than wide; and an ulnar facet on the humerus that is as wide as the radial facet. The first complete description of the skull of UHR 30691 and the incorporation of data derived from it into a phylogenetic analysis retrieves a monophyletic Ichthyopterygia that is supported by 18 unambiguous synapomorphies. The updated analysis recovers Utatsusaurus in a basal clade with Parvinatator (united by one unambiguous feature), which collectively form the sister group to all other ichthyopterygians.
Can Reptile Embryos Influence Their Own Rates of Heating and Cooling?
1. Wei-Guo Du (a,b)
2. Ming-Chung Tu (a,c)
3. Rajkumar S. Radder (a)
4. Richard Shine (a)
a. School of Biological Sciences, University of Sydney, Sydney, New South Wales, Australia
b. Key Lab of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, People’s Republic of China
c. Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
Previous investigations have assumed that embryos lack the capacity of physiological thermoregulation until they are large enough for their own metabolic heat production to influence nest temperatures. Contrary to intuition, reptile embryos may be capable of physiological thermoregulation. In our experiments, egg-sized objects (dead or infertile eggs, water-filled balloons, glass jars) cooled down more rapidly than they heated up, whereas live snake eggs heated more rapidly than they cooled. In a nest with diel thermal fluctuations, that hysteresis could increase the embryo’s effective incubation temperature. The mechanisms for controlling rates of thermal exchange are unclear, but may involve facultative adjustment of blood flow. Heart rates of snake embryos were higher during cooling than during heating, the opposite pattern to that seen in adult reptiles. Our data challenge the view of reptile eggs as thermally passive, and suggest that embryos of reptile species with large eggs can influence their own rates of heating and cooling.
Qianshanornis rapax, gen. et sp. nov. (holotype, IBCAS QS027), from the middle Paleocene Wanghudun Formation of the Qianshan Basin in China, left foot in dorsal (A), dorsomedial (B), ventrolateral (C), lateral (D), and medial (E) views; F, Strigogyps sapea from the middle Eocene of Messel in Germany (SMF Me 1819), left tarsometatarsus in dorsal view; G–J, Qianshanornis rapax (holotype, IBCAS QS027), distal end of left foot in dorsodistal (G), dorsal (H), ventrolateral (I), and medial (J) views; K–M, first phalanx of left second toe of (K) Qianshanornis rapax, gen. et sp. nov. (holotype, IBCAS QS027, with matrix digitally removed), (L) Cathartes aura (Cathartidae), and (M) Cariama cristata (Cariamidae). In A–E the phalanges are numbered. Abbreviations: blg, dorsal bulge of distal end of first phalanx of second toe; ext, sulcus extensorius; fos, fossa on plantar surface of trochlea metatarsi II; fvd, foramen vasculare distale; phl, fossa parahypotarsalis lateralis. Scale bars equal 10 mm; same scale bar for A–E and G–I, respectively.
A Strigogyps-like bird from the middle Paleocene of China with an unusual grasping foot
1. Gerald Mayr (a)
2. Jian Yang (b)
3. Eric De Bast (c)
4. Cheng-Sen Li (b)
5. Thierry Smith (b)
a. Senckenberg Research Institute and Natural History Museum Frankfurt , Ornithological Section, Senckenberganlage 25, D-60325 , Frankfurt am Main , Germany
b. Institute of Botany, Chinese Academy of Sciences, State Key Laboratory of Systematic and Evolutionary Botany , Xiangshan , Beijing , 100093 , People's Republic of China
c. Royal Belgian Institute of Natural Sciences, Department of Paleontology , Rue Vautier 29, B-1000 , Brussels , Belgium
We describe a new avian species, Qianshanornis rapax, gen. et sp. nov., from the middle Paleocene Wanghudun Formation of the Qianshan Basin in Anhui Province, China. The holotype consists of an incomplete articulated foot and a few associated bones, mainly of the leg, wing, and pectoral girdle. Qianshanornis rapax is characterized by a derived foot morphology and may have had a hyperextendible second toe, which has so far only been reported for some Mesozoic taxa. The new species is markedly different from all other known Cenozoic birds and is here classified in the new taxon Qianshanornithidae. The leg bones, especially the distal end of the tibiotarsus, most closely resemble those of Strigogyps (Ameghinornithidae) from the Eocene, and possibly Oligocene, of Europe, but unlike the latter, the much smaller Q. rapax appears to have had well-developed flight capabilities.
It is nothing short of a world record in DNA research that scientists at the Centre for GeoGenetics at the Natural History Museum of Denmark (University of Copenhagen) have hit. They have sequenced the so far oldest genome from a prehistoric creature. They have done so by sequencing and analyzing short pieces of DNA molecules preserved in bone-remnants from a horse that had been kept frozen for the last 700.000 years in the permafrost of Yukon, Canada. By tracking the genomic changes that transformed prehistoric wild horses into domestic breeds, the researchers have revealed the genetic make-up of modern horses with unprecedented details. The spectacular results are now published in the international scientific journal Nature.
DNA molecules can survive in fossils well after an organism dies. Not as whole chromosomes, but as short pieces that could be assembled back together, like a puzzle. Sometimes enough molecules survive so that the full genome sequence of extinct species could be resurrected and over the last years, the full genome sequence of a few ancient humans and archaic hominins has been characterized. But so far, none dated back to before 70,000 years.
Now Dr. Ludovic Orlando and Professor Eske Willerslev from the Centre for GeoGenetics have beaten this DNA-record by about 10 times. Thereby the two researchers – in collaboration with Danish and international colleagues – have been able to track major genomic changes over the last 700.000 years of evolution of the horse lineage.
First, by comparing the genome in the 700,000 year old horse with the genome of a 43,000 year old horse, six present day horses and the donkey the researchers could estimate how fast mutations accumulate through time and calibrate a genome-wide mutation rate. This revealed that the last common ancestor of all modern equids was living about 4.0-4.5 million years ago. Therefore, the evolutionary radiation underlying the origin of horses, donkeys and zebras reaches back in time twice as long as previously thought. Additionally, this new clock revealed multiple episodes of severe demographic fluctuation in horse history, in phase with major climatic changes such as the Last Glacial Maximum, some 20,000 years ago.
De-extinction! De-Extinction! This one seems like an easy do!
A new skeleton of the giant hedgehog Deinogalerix from the Miocene of Gargano, southern Italy
1. Boris Villier (a)
2. Giorgio Carnevale (a)
a. Dipartimento di Scienze della Terra, Universit`a degli Studi di Torino, Via Valperga Caluso, 35 I-10125, Torino, Italy,
The giant Miocene erinaceid Deinogalerix from the Gargano paleoisland, southern Italy, represents one of the most spectacular cases of insular adaptation among terrestrial mammals. The type species of this genus, Deinogalerix koenigswaldi, was described for the first time early in the 1970s based on a nearly complete skeleton and the limits and composition of the genus were subsequently defined based on a large number of disarticulated remains. Recent excavations in the Gargano area led to the discovery of a second partially complete skeleton of Deinogalerix koenigswaldi. This material, which is described herein, consists of a well-preserved nearly complete skull and a large portion of the postcranial skeleton. As a result of its excellent preservation, this material allowed the description of previously unrecognized morphological features of the braincase, tympanic region, and forelimb. Finally, based on a comparative analysis of the skeletal features of Deinogalerix, its affinities within the Erinaceidae have been discussed. Several features observed on the skeleton documented in this paper conclusively demonstrate that this giant hedgehog is a member of the subfamily Galericinae and, more particularly, of the extinct tribe Galericini.
NVIDIA’s Chief Scientist, Bill Dally, tackled this issue in the ISC conference keynote address he delivered at the big event, entitled “Future Challenges of Large-scale Computing.”
Presenting to some of the high performance computing (HPC) industry’s foremost experts, Dally outlined challenges the industry needs to overcome to reach exascale by the end of this decade.
It boils down, in his view, to two major issues: power and programming.
It’s About Power, Forget Process
Theoretically, an exascale system – 100 times more computing capability than today’s fastest systems – could be built with only x86 processors, but it would require as much as 2 gigawatts of power.
That’s the entire output of the Hoover Dam.
On the other hand, the GPUs in an exascale system built with NVIDIA Kepler K20 processors would consume about 150 megawatts. So, a hybrid system that efficiently utilizes CPUs with higher-performance GPU accelerators is the best bet to tackle the power problem.
GPUs are something I pushed here at the the Lab from the retirement of the Cray vector machines until moving over to the data systems side. However, CPU programming is still problematic in many ways. Yet, this could be rectified. On the flipside...how many sites can STILL afford 150 MW of power for a single machine. Our new building won't be able to handle 300 MW of power (we keep two big machines on the floor at a time...)
I am refining the no singularity idea for the post. Friends have seen the extremely rough outline of the idea in email. it needs a couple more mental iterations before being committed to a post.
Tuesday, June 25, 2013
High latitude Albian climate variability: palynological evidence for long-term drying in a greenhouse worldAuthors:1. Barbara E. Wagstaff (a)2. Stephen J. Gallagher (a)3. Martin S. Norvick (a)4. David J. Cantrill (b)5. Malcolm W. Wallace (a)Affiliations:a. School of Earth Sciences, The University of Melbourne, Victoria 3010, Australiab. National Herbarium of Victoria, Royal Botanic Gardens Melbourne, South Yarra, Victoria 3141, AustraliaAbstract:Detailed “Quaternary-style” quantitative spore-pollen counts, with a pollen sum based on total gymnosperms, from a southern high palaeolatitude (66°) terrestrial sequence in Gippsland, southeast Australia has revealed strong vegetation and climate variability during the Albian. This variability is more pronounced than previously suggested in global Early Cretaceous vegetation and climate reconstructions. The quantitative spore-pollen record shows drying throughout the Albian based on upward decreasing total ferns and variation in podocarp and total Alisporites/Vitreisporites pollen. This record suggests that although global climate during the Albian is considered to have been warm, stable and equable, regional factors such as water availability and continentality were the main drivers of this vegetation change.
A team of astronomers, including Carnegie's Paul Butler, has combined new observations with existing data to reveal a solar system packed full of planets. The star Gliese 667C is orbited by between five and seven planets, the maximum number that could fit in stable, close orbits. A record-breaking three of these planets are super-Earths found in the so-called habitable zone around the star—the zone where liquid water could exist. This makes them good candidates for the search for life.
Gliese 667C is a very well-studied star. It is just over one third of the mass of our Sun, and it is part of a triple star system known as Gliese 667. Gliese 667 is remarkably similar to our solar system, compared to other stars studied in the search for habitable planets.
Previous studies of Gliese 667C found that the star hosts three planets, with one in the habitable zone. Now, a team of astronomers led by Guillem Anglada-Escudé of the University of Göttingen, a former Carnegie post-doc, reexamined observations taken between 2003 and 2012, along with new observations from a variety of telescopes, and found evidence for five, and possibly as many as seven, planets around the star.
If seven planets exist, they would completely fill the habitable zone; there are no more stable, long-lived orbits in which a planet could be so close to the star. Because Gliese 677C is part of a triple-star system, the other orange stars would be visible in daytime on each of these planets, and in nighttime they would provide the same illumination as the full moon on earth.
"We identified three strong signals in the star before, but it was possible that smaller planets were hidden in the data" said Anglada-Escudé. "We reexamined the existing data, added some new observations, and applied two different data analysis methods especially designed to deal with multi-planet signal detection. Both methods yielded the same answer: there are five very secure signals and up to seven low-mass planets in short-period orbits around the star."
Three of these planets are confirmed to be super-Earths—planets more massive than Earth, but less massive than giant planets like Uranus or Neptune—which are within the star's habitable zone.
"This is the first time that three such planets have been spotted orbiting in this zone in the same system," Butler said.
Compact systems around Sun-like stars have been found to be abundant in the Milky Way. However, many of these systems consist of super-Earths lying very close to their star, within the orbit of Mercury. In systems built around Sun-like stars, these orbits are very hot and planets there are unlikely to be habitable.
This is not the case for cooler and dimmer stars Planets found very close to such stars could still be habitable planet candidates. The Gliese 667C system is the first example of a system in which a low-mass star is seen to host several packed planets with habitable conditions.
This discovery illustrates that low-mass stars are currently the best targets for searching for potentially habitable planets, an important finding given that around 80% of the stars in our Milky Way galaxy, and many stars near to us, fall into this lower mass bracket. If such packed systems are common around low-mass stars, the number of potentially habitable planets in our galaxy could be much larger than previously expected.
Oh the dangers of writing SF about exoplanets these days... must be like how it was during the 1960s and 1970s for the Sol System.
Many pop sci write ups.
It would be hilarious if it was only ever a movie prop which was commissioned. Zero chance of that, but even so, its a funny thought.
New 40Ar/39Ar and K-Ar ages of the Viluy traps (Eastern Siberia): Further evidence for a relationship with the Frasnian–Famennian mass extinctionTiming is not everything, folks. Extinction pattern studies are needed, too.
1. J. Ricci (a, b)
2. X. Quidelleur (a, b)
3. V. Pavlov (c)
4. S. Orlov (c)
5. A. Shatsillo (c)
6. V. Courtillot (d, e)
a. Univ Paris-Sud, Laboratoire IDES, UMR8148, Orsay, F-91405; France
b. CNRS, Orsay, F-91405; France
c. Inst. Phys. Earth, Moscow 123995, Russia.
d. Equipe de Paléomagnétisme, Institut de Physique du Globe, UMR 7154, Sorbonne Paris Cité, F-75005, Paris, France
e. Sciences de la Terre, de l'Environnement et des Planètes, Université Paris Diderot, Sorbonne Paris Cité, F-75013, Paris, France
We present here new ages, combining both K-Ar and 40Ar/39Ar techniques, reinforcing the possible link between the Viluy traps (eastern Siberia) with the Late–Devonian mass extinctions. The Viluy traps (also referred to as the Yakutsk large igneous province) are associated with the breakup of the eastern margin of the Siberian platform as a triple-junction rift system, with volcanic outcropping along the Lena, Markha and Viluy rivers and an initial volume of volcanic products of about one million cubic kilometers. K-Ar ages obtained on seven samples from the Viluy rift display values ranging from 366 ± 5 to 381 ± 5 Ma, with a mean age of 374 ± 5 Ma. Our new 40Ar/39Ar results display well-defined step-heating plateau ages ranging from 362.3 ± 3.4 to 379.7 ± 3.5 Ma. Although most K-Ar and 40Ar/39Ar ages agree within about 1% uncertainty, which reinforces the validity of the K-Ar ages obtained with the Cassignol and Gillot unspiked technique (even in the Paleozoic), a slightly clearer scenario appears when only the 40Ar/39Ar ages are considered. Effectively, they cluster in two different groups with weighted mean ages of 364.4 ± 1.7 and 376.7 ± 1.7 Ma. These ages support a multi-phases emplacement of the Viluy traps, as is the case for many continental flood basalts. Because the age of the first volcanic phase is undistinguishable from recent determinations of the age of the Frasnian–Famennian boundary, our results further strengthen the hypothesis of a causal relationship between the two events. The second phase of emplacement of the Viluy traps occurred at the end of the Devonian, apparently slightly before the Devonian–Carboniferous boundary. Finally, except for the Ordovician–Silurian extinction which remains to be associated with a volcanic province, all major Phanerozoic mass extinctions have been correlated with the emplacement of a CFB, thereby reinforcing the possible causal link between these events.
That said, if this holds up, supercontinents are BAD NEWS for life.
Monday, June 24, 2013
Picture from here.
This is a take off from the First Crazy Thought (*) post which positing martian life getting pounded into oblivion despite being far ahead of Terran life. It plays into a comment James made and one he restated on his LJ with respect to the scenario.
We know about the habitable zone, sometimes called the Goldilocks Zone: not too hot, not too cold, but just right...for water worlds.
So, my crazy thought proposal is...for worlds and moons where methane plays the part of water, like say, Titan, the just right zone for those worlds ought to be called the Snegurochka Zone, named for the Snow Maiden in Russian folklore and more specifically, in modern times, daughter of grandfather Frost (Ded Moroz).
*. Second crazy thought will go up tomorrow evening.
Restoring the Silurian to Carboniferous northern active continental margin of the Mongol-Okhotsk Ocean in Mongolia - Hangay-Hentey accretionary wedge and seamount collisionAuthors:1. Désirée Ruppen (a)2. Alice Knaf (a)3. Denise Bussien (a)4. Wilfried Winkler (a)5. Anaad Chimedtseren (b)6. Albrecht von Quadt (c)Affiliations:a. Geological Institute, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerlandb. Mongolian University of Science and Technology, Ulaanbaatar 210646, P.O.Box 46/225, Mongoliac. Institute of Geochemistry and Petrology, Department of Earth Sciences, ETH Zurich, Clausiusstrasse 25, 8092 Zurich, SwitzerlandAbstract:Trapped between the Siberian Craton to the north, and the Tarim and North China blocks to the south, the Mongol-Okhotsk Belt represents a young portion of the Central Asian Orogenic Belt. The Andean-type orogeny was caused by the closure of the Mongol-Okhotsk Ocean, whose timing and mode of geodynamic evolution still needs to be clarified in more detail. This paper investigates the lithostratigraphic units of the Gorkhi Formation, which are comprised in the Hangay-Hentey terrane representing the accretionary prism of the northern continental margin of the Mongol-Okhotsk Ocean. In the tectonically disrupted slices of the Gorkhi Formation we identify a typical ocean plate stratigraphy with pelagic to hemipelagic and turbiditic sequences. Locally, shallow marine limestones are found associated with mafic volcanic rocks. XRF and LA-ICPMS measurements of these volcanic rocks clearly indicate an OIB signature. The geochemistry together with lithostratigraphic observations permit us to reconstruct the evolution of a seamount, ranging from its growth in shallow water depths and drowning due to subduction-related subsidence linked with subsequent radiolarian chert, hemipelagic shale and turbiditic sandstone cover sedimentation. Calc-alkaline felsic dikes later intruded the accreted silt and sandstone deposits. Standard sandstone provenance analysis, detrital zircon U-Pb laser ablation ICP-MS dating and Hf isotope ratios in the sandstones document a prevailing continental volcanic arc sourcing during Carboniferous from the northern margin of the Mongol-Okhotsk Ocean.
During the Permian era, the Earth was dominated by a single supercontinent called Pangea – "All-Earth". Animal and plant life dispersed broadly across this land, as documented by identical fossil species found on multiple modern continents. But a new study published in the Journal of Vertebrate Paleontology supports the idea that there was an isolated desert in the middle of Pangea with a fauna all its own.
Roaming this desert in what is now northern Niger was a very distinctive creature known as a pareiasaur. Pareiasaurs were large, herbivorous reptiles that were common across Pangea during the Middle and Late Permian, about 266-252 million years ago. "Imagine a cow-sized, plant-eating reptile with a knobby skull and bony armor down its back," said lead author Linda Tsuji. The newly discovered fossils belong to the aptly-named genus Bunostegos, which means "knobby [skull] roof."
Most pareiasaurs had bony knobs on their skulls, but Bunostegos sported the largest, most bulbous ones ever discovered. In life, these were probably skin-covered horns like those on the heads of modern giraffes. Although at first blush these features seem to suggest that Bunostegos was an evolutionarily advanced pareiasaur, it also had many primitive characteristics. Tsuji's analysis showed that Bunostegos was actually more closely related to older and more primitive pareiasaurs, leading to two conclusions: first, that its knobby noggin was the result of convergent evolution, and second, that its genealogical lineage had been isolated for millions of years.
So how do you isolate a population of cow-sized reptiles? Though there were no fences in the Permian, climatic conditions conspired to corral Bunostegos – along with several other reptiles, amphibians, and plants – and keep them constrained to the central area of the supercontinent. "Our work supports the theory that central Pangea was climatically isolated, allowing a unique relict fauna to persist into the Late Permian," said Christian Sidor, another author of the paper. This is surprising because areas outside this central region show fossil evidence of regular faunal interchange.
Geological data also show that central Pangea was hyperarid (extremely dry), effectively discouraging some animals from passing through, while keeping those within from venturing out. The long period of isolation under these parched conditions gave Bunostegos lineage time to evolve its unique anatomical features.
Paleontologist Gabe Bever, who was not involved with the study, said "Research in these lesser-known basins is critically important for meaningful interpretation of the Permian fossil record. Our understanding of the Permian and the mass extinction that ended it depends on discovery of more fossils like the beautifully bizarre Bunostegos."
A research team led by a University of Chicago scientist has discovered two key mutations that sparked a hormonal revolution 500 million years ago.
In a feat of "molecular time travel," the researchers resurrected and analyzed the functions of the ancestors of genes that play key roles in modern human reproduction, development, immunity and cancer. By re-creating the same DNA changes that occurred during those genes' ancient history, the team showed that two mutations set the stage for hormones like estrogen, testosterone and cortisol to take on their crucial present-day roles.
"Changes in just two letters of the genetic code in our deep evolutionary past caused a massive shift in the function of one protein and set in motion the evolution of our present-day hormonal and reproductive systems," said Joe Thornton, PhD, professor of human genetics and ecology & evolution at the University of Chicago, who led the study.
"If those two mutations had not happened, our bodies today would have to use different mechanisms to regulate pregnancy, libido, the response to stress, kidney function, inflammation, and the development of male and female characteristics at puberty," Thornton said.
The findings were published online June 24 in the Proceedings of the National Academy of Sciences.
Understanding how the genetic code of a protein determines its functions would allow biochemists to better design drugs and predict the effects of mutations on disease. Thornton said the discovery shows how evolutionary analysis of proteins' histories can advance this goal, Before the group's work, it was not previously known how the various steroid receptors in modern species distinguish estrogens from other hormones.
The team, which included researchers from the University of Oregon, Emory University and the Scripps Research Institute, studied the evolution of a family of proteins called steroid hormone receptors, which mediate the effects of hormones on reproduction, development and physiology. Without receptor proteins, these hormones cannot affect the body's cells.
Thornton's group traced how the ancestor of the entire receptor family—which recognized only estrogens—evolved into descendant proteins capable of recognizing other steroid hormones, such as testosterone, progesterone and the stress hormone cortisol.
To do so, the group used a gene "resurrection" strategy. They first inferred the genetic sequences of ancient receptor proteins, using computational methods to work their way back up the tree of life from a database of hundreds of present-day receptor sequences. They then biochemically synthesized these ancient DNA sequences and used molecular assays to determine the receptors' sensitivity to various hormones.
Thornton's team narrowed down the time range during which the capacity to recognize non-estrogen steroids evolved, to a period about 500 million years ago, before the dawn of vertebrate animals on Earth. They then identified the most important mutations that occurred during that interval by introducing them into the reconstructed ancestral proteins. By measuring how the mutations affected the receptor's structure and function, the team could re-create ancient molecular evolution in the laboratory.
They found that just two changes in the ancient receptor's gene sequence caused a 70,000-fold shift in preference away from estrogens toward other steroid hormones. The researchers also used biophysical techniques to identify the precise atomic-level mechanisms by which the mutations affected the protein's functions. Although only a few atoms in the protein were changed, this radically rewired the network of interactions between the receptor and the hormone, leading to a massive change in function.
Nitrogen isotope chemostratigraphy of the Ediacaran and Early Cambrian platform sequence at Three Gorges, South China
1. Ryohei Kikumoto (a)
2. Miyuki Tahata (a)
3. Manabu Nishizawa (b)
4. Yusuke Sawaki (a)
5. Shigenori Maruyama (a, c)
6. Shu Degan (d)
7. Han Jiang (d)
8. Tsuyoshi Komiya (e)
9. Ken Takai (b, c)
10. Yuichiro Ueno (a, b, c)
a. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152–8551, Japan
b. Precambrian Ecosystem Laboratory, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2–15 Natsushima-cho, Yokosuka 237–0061, Japan
c. Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152–8551, Japan
d. Department of Geology and Key Laboratory for Continental Dynamics, Northwest University, Xi'an 710069, China
e. Department of Earth Science and Astronomy, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153–8902, Japan
The appearance of multicellular animals and subsequent radiation during the Ediacaran/Cambrian transition may have significantly changed oceanic ecosystem. Nitrogen cycling is essential for primary productivity and thus its connection to animal evolution is important for understanding co-evolution of the Earth’s environment and life. Here, we first report coupled organic carbon and nitrogen isotope chemostratigraphy from the entire Ediacaran to Early Cambrian period by using drill core samples from the Yangtze Platform, South China. The results show that δ15NTN values were high (~ + 6‰) until middle Ediacaran, gradually dropped down to − 1‰ at the earliest Cambrian, then rose back to + 4‰ in the end of the Early Cambrian. Organic carbon and nitrogen contents widely varied with relatively constant C/N ratio in each stratigraphic unit, and do not apparently control the carbon and nitrogen isotopic trends. These observations suggest the δ15NTN and C/N trends mainly reflect secular changes in nitrogen cycling in the Yangtze Platform. Onset of the observed negative N isotope excursion coincided with a global carbon isotope excursion event (Shuram excursion). Before the Shuram event, the high δ15N probably reflects denitrification in a nitrate-limited oceanic condition. Also, degradation of dissolved and particulate organic matter could be an additional mechanism for the 15 N-enrichment, and may have been significant when the ocean was rich in organic matter. At the time of Shuram event, both δ13Ccarb and δ15NTN values were dropped probably due to massive re-mineralization of organic matter. This scenario is supported by anomalously low C/N ratio, implying enhanced respiration resulted in selective loss of carbon as CO2 with recycled organic nitrogen. After the Shuram event, δ15N value continued to decrease in spite of δ13Ccarb rose back to + 4‰. The continued δ15N drop appears to have coincided with decreasing phosphorus content in carbonate. This suggests ocean oxygenation may have generated more nitrate-rich condition with respect to phosphorus as a limiting nutrient. Similar to the Shuram event, another negative δ13Ccarb event in the Canglanpuan stage of the Early Cambrian is also characterized by carbon isotopic decoupling as well as the low C/N ratio. The results strongly support that the two stages of the decoupled negative δ13Ccarb excursions reflect disappearance of large organic carbon pool in the ocean. The two events appear to relate with appearance of new metazoan taxa with novel feeding strategies, suggesting the link between ocean oxygenation, nutrient cycling and appearance and adaptation of metazoan. The nitrogen isotope geochemistry is very useful to understand the link between the environmental, ecological and biological evolutions.
Sunday, June 23, 2013
Evolution from an anoxic to oxic deep ocean during the Ediacaran–Cambrian transition and implications for bioradiation
1. Jianguo Wang (a)
2. Daizhao Chen (a)
3. Detian Yan (b)
4. Hengye Wei (a)
5. Lei Xiang (a)
a. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
b. Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, University of Geosciences, Wuhan 430074, China
The Ediacaran–Cambrian transition, one of the most critical intervals in Earth's history, is marked by dramatic biological, oceanic and geochemical turnovers. Here high-resolution carbon and sulfur isotopic data respectively for organic carbon and pyrite, and iron speciation data are presented from the deep-water Liuchapo and Niutitang Formations on the Yangtze block, South China. The carbon isotopic data, together with biostratigraphic and radiometric dating, offer the compelling evidence for the placement of Ediacaran–Cambrian boundary within the Liuchapo Formation (chert succession), and for its correlation with shallow-water equivalents elsewhere. In this context, iron speciation and sulfur isotopic data further suggest a predominant anoxic and ferruginous deep ocean over the transitional time until the middle Early Cambrian (Atdabanian or Stage 3) when the deep ocean was rapidly oxygenated. Coincidently, during this interval, large-body metazoans (i.e., sponges) abruptly appeared in the deep ocean, which was temporally associated with the highly diversified large-body skeletonized animals (i.e., Chengjiang Biota) which colonized in shallow-water niches particularly in southwestern China. This scenario suggests a causal link between deep oceanic oxygenation and the explosive diversification of large-body skeletonized organisms in the Early Cambrian.
Saturday, June 22, 2013
Unlike China and Europe, the U.S. has yet to adopt and fund an exascale development program, and concerns about what that means to U.S. security are growing darker and more dire.
China's retaking of the global supercomputing crown was the starting point for discussion at an IBM-sponsored congressional forum this week on cognitive computing.
Cognitive computing systems have the capability of taking vast amounts of data and making what will be, for all intents, thoughtful decisions.
Efforts to draw attention to exascale in the U.S. House are being led Rep. Randy Hultgren (R-Ill.), who talked about China's new 33.89-petaflop system, Tianhe-2.
"It's important not to lose sight that the reality was that it was built by China's National University of Defense Technology," said Hultgren, who is finalizing a bill "that will push our nation toward exascale."
Hultgren is introducing legislation, the American Supercomputing Leadership Act, to require the U.S. Department of Energy to develop a coordinated exascale research program. The bill doesn't call for a specific spending level, but one source said about an annual appropriation of $200 million, if not more, will be sought.
That amount of money is well short of what's needed to build an exascale system, or a computer of 1,000 thousand petaflops. Each petaflop represents one thousand trillion floating point operations per second.
Earl Joseph, an HPC analyst at IDC, said that "$200 million is better than nothing, but compared to China and Europe it's at least 10 times too low."
Joseph said that it's his guess that the world will see an exascale system by 2015 or 2016 "installed outside the U.S. It will take a lot of power and it will be large, but it will provide a major capability."
I've seen this a few times before. First it was the evil japanese (back in the early 90s through the early 00s) and now its the scary chinese!
I have to snigger at Mr Joseph's time frame. oy. The contract will have to already been signed...and...uh.