Thermal degradation of organics for pyrolysis in space: Titan’s atmospheric aerosol case study
He et al
Pyrolysis coupled with mass spectry is among the instrumentation the most implemented in planetary exploration probes to analyze the chemical composition of extraterrestrial solid samples. It is used to analyze the volatile species which can be thermally extracted from the samples, including the organic fraction which is of primary interest for astrobiological purposes. However the thermal degradation of these organic materials, which can be very complex in nature or very different from organics commonly present on Earth, is badly known. This leads to a restriction in the optimization of space instrumentation, and in the interpretation of the measurements. In the present work we propose a complete overview of the thermal degradation processes studied on a model of complex organic material produced in an extraterrestrial environment, i.e. laboratory analogues of Titan’s atmospheric aerosols. The thermal evolution of the studied analogues is monitored by following their mass loss, the emitted heating flux, and the evolution of their chemical composition through infrared spectroscopy and elemental analysis. The gaseous products released from the material are also analyzed by mass spectrometry, allowing to better constrain the mechanisms of chemical evolution of the samples. The complex organic material analyzed is found not to be fully decomposed when heated up to about 800 °C, with the evidence that nitrogen is still deeply incorporated in the remaining graphitic carbon nitride residue. The most appropriate pyrolysis temperature to chemically probe the studied material is found to be about 450 °C because at this temperature are detected the largest gaseous molecules which should be the most representative ones of the material pyrolyzed.
Wednesday, November 26, 2014
Not long ago, it would have taken several years to run a high-resolution simulation on a global climate model. But using some of the most powerful supercomputers now available, Lawrence Berkeley National Laboratory (Berkeley Lab) climate scientist Michael Wehner was able to complete a run in just three months.
What he found was that not only were the simulations much closer to actual observations, but the high-resolution models were far better at reproducing intense storms, such as hurricanes and cyclones. The study, "The effect of horizontal resolution on simulation quality in the Community Atmospheric Model, CAM5.1," has been published online in the Journal of Advances in Modeling Earth Systems.
"I've been calling this a golden age for high-resolution climate modeling because these supercomputers are enabling us to do gee-whiz science in a way we haven't been able to do before," said Wehner, who was also a lead author for the recent Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). "These kinds of calculations have gone from basically intractable to heroic to now doable."
Using version 5.1 of the Community Atmospheric Model, developed by the Department of Energy (DOE) and the National Science Foundation (NSF) for use by the scientific community, Wehner and his co-authors conducted an analysis for the period 1979 to 2005 at three spatial resolutions: 25 km, 100 km, and 200 km. They then compared those results to each other and to observations.
One simulation generated 100 terabytes of data, or 100,000 gigabytes. The computing was performed at Berkeley Lab's National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility. "I've literally waited my entire career to be able to do these simulations," Wehner said.
The higher resolution was particularly helpful in mountainous areas since the models take an average of the altitude in the grid (25 square km for high resolution, 200 square km for low resolution). With more accurate representation of mountainous terrain, the higher resolution model is better able to simulate snow and rain in those regions.
"High resolution gives us the ability to look at intense weather, like hurricanes," said Kevin Reed, a researcher at the National Center for Atmospheric Research (NCAR) and a co-author on the paper. "It also gives us the ability to look at things locally at a lot higher fidelity. Simulations are much more realistic at any given place, especially if that place has a lot of topography."
An advanced, new long-legged bird from the Early Cretaceous of the Jehol Group (northeastern China): insights into the temporal divergence of modern birds
Liu et al
We describe a new ornithuromorph bird species, Gansus zheni from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation (Jehol Group), Liaoning Province, China. A cladistic analysis resolves Gansus zheni as the sister taxon of the roughly contemporaneous Gansus yumenensis (Xiagou Formation, Gansu Province), and together as the most immediate outgroup to Ornithurae. Gansus zheni is the most advanced bird known today for the Jehol Biota. Its discovery provides the best-documented case of inter-basinal correlations (Jehol and Changma basins of Liaoning and Gansu provinces, respectively) using low-taxonomic clades of fossil birds. The existence of close relatives of Ornithurae in deposits formed at about 120 million years ago helps to mitigate the long-standing controversy between molecular and paleontological evidence for the temporal divergence of modern birds (Neornithes).
Features, provenance, and tectonic significance of Carboniferous-Permian glacial marine diamictites in the Southern Qiangtang–Baoshan block, Tibetan Plateau
Fan et al
In this study, we conducted profile measurements, gravel composition analyses, and U-Pb dating on detrital zircons from a representative glacial marine diamictite in the Gangmaco–Dabure area of the Southern Qiangtang–Baoshan block, Tibetan Plateau. We conclude that the diamictite was formed in a glacial marine environment from the outer edge of the continental shelf to the continental slope and deep sea, in what is now the Southern Qiangtang–Baoshan block. Four distinct glacial-interglacial cycles were identified in the diamictite, which record a minimum of four stages of Gondwana glaciation in the area of the Southern Qiangtang–Baoshan block. Combined with regional geological information, we also conclude that during the Carboniferous-Permian, sediments containing the glacial marine diamictite derived from Gondwana, in the region extending from India to the Tethys Himalaya area, Lhasa and Southern Qiangtang–Baoshan blocks, recorded the transition from continental, neritic to abyssal environments. Gravel assemblages and U-Pb dating of detrital zircons in the glacial marine diamictite indicate that the provenance of the diamictite was Indian Gondwana. We infer that during the Late Paleozoic, the northern margin of the Indian Gondwana continued to be influenced by the Early Palaeozoic tectonic set-up, when Indian Gondwana was under an erosional regime, and the Tethys Himalaya area, Lhasa and Southern Qiangtang–Baoshan blocks were deposited on a passive continental margin.
Large sulfur isotope fractionations associated with Neoarchean microbial sulfate reduction
Zhelezinskaia et al
The minor extent of sulfur isotope fractionation preserved in many Neoarchean sedimentary successions suggests that sulfate-reducing microorganisms played an insignificant role in ancient marine environments, despite evidence that these organisms evolved much earlier. We present bulk, microdrilled, and ion probe sulfur isotope data from carbonate-associated pyrite in the ~2.5-billion-year-old Batatal Formation of Brazil, revealing large mass-dependent fractionations (approaching 50 per mil) associated with microbial sulfate reduction, as well as consistently negative Δ33S values (~ –2 per mil) indicative of atmospheric photochemical reactions. Persistent 33S depletion through ~60 meters of shallow marine carbonate implies long-term stability of seawater sulfate abundance and isotope composition. In contrast, a negative Δ33S excursion in lower Batatal strata indicates a response time of ~40,000 to 150,000 years, suggesting Neoarchean sulfate concentrations between ~1 and 10 μM.
Tuesday, November 25, 2014
The French government is suspending a deal to deliver two Mistral-class warships to the Russian Navy “until further notice” citing the ongoing conflict in Ukraine, according to a Tuesday statement from the office of President François Hollande.
In response, Russian defense officials have pledged to take legal action against France if the Hollande government does not reverse its stance, according to Russian media.
“The President of the Republic believes that the current situation in the east of Ukraine still does not allow the transfer of the first Russian Mistral-type ships to Russia,” read a translation of the statement from Élysée Palace.
“He has decided that it is appropriate to suspend, until further notice, the examination of the request for export authorization for the first [Mistral] to the Russian Federation.”
Flying far is more important than flying fast, Japanese fighter technologists have found in studies aimed at defining their country’s next combat aircraft. Looking for ways for their air force to fight outnumbered, researchers are also emphasizing that Japan’s next fighter should share targeting data, carry a big internal load of large, high-performance missiles and be able to guide them while retreating.
The results of this work may be committed to full-scale development within four years. Japan is holding open the possibility of a joint international program, which the finance ministry would surely prefer, but the defense ministry looks wary of being trapped in a late-running cooperative effort over which it has little control. Specifically national requirements such as the preference for range over speed may also nudge Japan toward going it alone.
Engineers from the defense ministry’s Technical Research & Development Institute (TRDI) and IHI Corp. are well into preliminary development of a surprisingly powerful turbofan for the twin-engine fighter, which would enter service around 2030 as the F-3. TRDI is also handling the studies into the airframe, probably with strong engineering support from Mitsubishi Heavy Industries, which would build the airframe, and Mitsubishi Electric, the country’s dominant military electronic systems supplier.
Registration now is open for NASA’s Cube Quest Challenge, the agency’s first in-space competition that offers the agency’s largest-ever prize purse.
Competitors have a shot at a share of $5 million in prize money and an opportunity to participate in space exploration and technology development, to include a chance at flying their very own CubeSat to the moon and beyond as secondary payload on the first integrated flight of NASA’s Orion spacecraft and Space Launch System (SLS) rocket.
“NASA’s Cube Quest Challenge will engage teams in the development of the new technologies that will advance the state of the art of CubeSats and demonstrate their capabilities as viable deep space explorers,” said Michael Gazarik, associate administrator for NASA’s Space Technology Mission Directorate at NASA Headquarters in Washington. “Prize competitions like this engage the general public and directly contribute to NASA’s goals while serving as a tool for open innovation.”
Africa is home to 7 out of 10 of the world’s fastest-growing economies. It’s population is also the “youngest” in the world, with 50% of the population being 19 years old or younger. And amongst these young people are scores of innovators and entrepreneurs who are looking to bring homegrown innovation to their continent and share it with the outside world.
Nowhere is this more apparent than with the #Africa2Moon Mission, a crowdfunded campaign that aims to send a lander or orbiter to the Moon in the coming years.
Spearheaded by the Foundation for Space Development – a non-profit organization headquartered in Capetown, South Africa – the goal of this project is to fund the development of a robotic craft that will either land on or establish orbit around the Moon. Once there, it will transmit video images back to Earth, and then distribute them via the internet into classrooms all across Africa.
Disentangling the roles of late Miocene palaeogeography and vegetation – Implications for climate sensitivity
Bradshaw et al
The impact of rising CO2 on future climate remains uncertain but the evidence for high CO2 in the palaeorecord suggests that past climates could provide a potentially quantifiable indication of climate in a high-CO2 world. One such past time period is the late Miocene (11.6–5.3 Ma), for which CO2 reconstructions indicate higher levels than those of preindustrial, and similar to the present atmospheric level (~ 400 ppm). The late Miocene palaeorecord suggests a much warmer and wetter Northern Hemisphere than preindustrial. However, vegetation feedbacks are an important component of the climate system and vegetation distribution reconstructions from the palaeorecord have been shown to be very different to the present vegetation distribution. We examine the roles that different vegetation and palaeogeography play in climate sensitivity for the late Miocene and consider the implications for potential future climate change. To do this we use coupled atmosphere-ocean-vegetation simulations of late Miocene and potential modern climates forced by three different CO2 concentrations with vegetation perturbation experiments and make quantitative comparisons to the palaeorecord. Optimal regions to target late Miocene palaeodata acquisition for the purposes of informing about future climate include North America, northern Africa, Australia, Paraguay and southern Brazil, and northeastern Asia. These regions are those which the model results predict to be most sensitive to CO2 forcing, but where the local temperature response to CO2 forcing is similar between the simulated potential modern and late Miocene climates. The model results suggest that climate sensitivity to CO2 forcing is directly affected by the palaeogeographic configuration and that the inferred climate sensitivity for doubled CO2 is 0.5–0.8 °C higher for the late Miocene than we might expect for future climate because of differences in synergy. The greater land mass at high northern latitudes during the late Miocene and the differences in vegetation distribution predictions that result, combined with differences in ocean circulation and the effect of sea ice, make the late Miocene boundary conditions more sensitive to CO2 forcing than the modern boundary conditions.
Tides on Europa: The membrane paradigm
Jupiter’s moon Europa has a thin icy crust which is decoupled from the mantle by a subsurface ocean. The crust thus responds to tidal forcing as a deformed membrane, cold at the top and near melting point at the bottom. In this paper I develop the membrane theory of viscoelastic shells with depth-dependent rheology with the dual goal of predicting tidal tectonics and computing tidal dissipation. Two parameters characterize the tidal response of the membrane: the effective Poisson’s ratio View the MathML sourceν¯ and the membrane spring constant Λ , the latter being proportional to the crust thickness and effective shear modulus. I solve membrane theory in terms of tidal Love numbers, for which I derive analytical formulas depending on View the MathML sourceΛ,ν¯, the ocean-to-bulk density ratio and the number View the MathML sourcek2∘ representing the influence of the deep interior. Membrane formulas predict h2h2 and k2k2 with an accuracy of a few tenths of percent if the crust thickness is less than one hundred kilometers, whereas the error on l2l2 is a few percents. Benchmarking with the thick-shell software SatStress leads to the discovery of an error in the original, uncorrected version of the code that changes stress components by up to 40%. Regarding tectonics, I show that different stress-free states account for the conflicting predictions of thin and thick shell models about the magnitude of tensile stresses due to nonsynchronous rotation. Regarding dissipation, I prove that tidal heating in the crust is proportional to Im(Λ)Im(Λ) and that it is equal to the global heat flow (proportional to Im(k2)Im(k2)) minus the core-mantle heat flow (proportional to View the MathML sourceIm(k2∘)). As an illustration, I compute the equilibrium thickness of a convecting crust. More generally, membrane formulas are useful in any application involving tidal Love numbers such as crust thickness estimates, despinning tectonics or true polar wander.
China's anti-logging, conservation and ecotourism policies are accelerating the loss of old-growth forests in one of the world's most ecologically fragile places, according to studies led by a Dartmouth College scientist.
The findings shed new light on the complex interactions between China's development and conservation policies and their impact on the most diverse temperate forests in the world, in "Shangri-La" in northwest Yunnan Province. Shangri-La, until recently an isolated Himalayan hinterland, is now the epicenter of China's struggle to wed sustainable economic development with environmental protection. The province is known for its scenic, ecological and ethnic diversity, but it also is one of the poorest regions in China, populated by indigenous subsistence cultures that rely on forests for their livelihoods. The province was largely undisturbed until the 1950s when state logging companies started clear-cutting old-growth forests to fuel China's national economic boom. But catastrophic flooding along the Yangtze River in the 1990s prompted the Chinese government to implement multiple forest protection policies, including nature reserves, a commercial logging ban, reforestation programs and ecotourism, as a sustainable development strategy. The logging ban prohibits commercial timber harvesting, but allows logging by local people on a quota basis.
In a new study in the journal Biological Conservation, researchers used satellite imagery and statistical analysis to evaluate three overlapping forest conservation strategies -- protected areas, a commercial logging ban and Tibetan sacred forests - in northwest Yunnan Province. The results show that protected-area status conserved old-growth forests, while the logging ban increased total forest cover but accelerated old-growth logging in sacred forests. The sacred forests have effectively protected old-growth trees from clear-cutting for centuries despite major upheavals in the region's history, including the logging era and the Cultural Revolution. But recent official environmental protection policies have displaced these ancient community-managed protections. In a related 2012 study in the journal Remote Sensing of Environment, researchers used three decades of satellite imagery to measure rates and patterns of old-growth deforestation in response to the environmental protection and sustainable development policies. The results, surprisingly, showed that old-growth logging accelerated: old-growth forests covered 26 percent of the area in 1990 but only 20 percent in 2009. And, paradoxically, old-growth forest loss occurred most rapidly where ecotourism was most prominent. "Our results show that the negative impacts of ecotourism-based economic development on the environment outweighed conservation efforts," says lead author Jodi Brandt, a postdoctoral researcher at Dartmouth and formerly at the University of Wisconsin-Madison and University of Michigan.
The oldest Cretaceous North American sauropod dinosaur
D'emic et al
Sauropod dinosaurs have been found in sediments dating to most of the Cretaceous Period on all major Mesozoic landmasses, but this record is spatiotemporally uneven, even in relatively well-explored North American sediments. Within the 80 million-year-span of the Cretaceous, no definitive sauropod occurrences are known in North America from two ca. 20–25 million-year-long gaps, one from approximately the Berriasian–Barremian and the other from the mid-Cenomanian–late Campanian. Herein, we present an undescribed specimen that was collected in the middle part of the twentieth century that expands the known spatiotemporal distribution of Early Cretaceous North American sauropods, partially filling the earlier gap. The material is from the Berriasian–Valanginian-aged (ca. 139 Ma) Chilson Member of the Lakota Formation of South Dakota and appears to represent the only non-titanosauriform from the Cretaceous of North America or Asia. It closely resembles Camarasaurus and may represent a form closely related to that genus that persisted across the Jurassic–Cretaceous boundary.
New insights into the scales of the Devonian tetrapod Tulerpeton curtum Lebedev, 1984
Mondéjar-Fernández et al
The Devonian origin of tetrapods and their transition from aquatic to terrestrial habitats is one of the most important episodes in vertebrate evolutionary history (e.g., Coates, 1996; Janvier, 1996; Jarvik, 1996; Daeschler et al., 2006; Clack, 2012). Among the multiple changes that took place during the so-called ‘fish-tetrapod transition,’ those concerning the integumentary dermal skeleton have received little attention. Nonetheless, the skin and associated dermal ossifications of early tetrapods determine key aspects of their metabolism, way of life, and locomotion (e.g., Bystrow, 1947; Castanet et al., 2003; Markey and Marshall, 2007; Witzmann, 2007, 2011).
The main integumentary ossifications of early tetrapods are scales and osteoderms. Osteoderms are plates of dermal bone made by intradermal ossification that often bear a pitted outer surface. By contrast, dermal scales originate from the mesodermal layer of the dermis, are thinner than osteoderms, are often round or elongate ovals in outline, and may overlap (Castanet et al., 2003). Most Palaeozoic tetrapods were broadly covered with ossified dermal scales, mainly in their ventral and lateral regions (Romer, 1956; Janvier, 1996). However, dermal scales were lost in several tetrapod groups during the late Palaeozoic and Mesozoic, and replaced by osteoderms as the main integumentary mineralized structures (Vickaryous and Sire, 2009; Witzmann and Soler-Gijón, 2010).
Devonian tetrapods (such as Ichthyostega and Acanthostega) are considered as mainly aquatic animals, with limited walking abilities (Ahlberg et al., 2005; Pierce et al., 2012), as evidenced by the retention of primitive traits such as a caudal fin supported by osseous fin rays, a lateral line system, internal gills, and a dermal scale covering (Coates, 1996; Jarvik, 1996; Clack, 2012). Within Tetrapoda, the transition to land (or terrestrialization) during the Devonian and Carboniferous (Clack, 2012; Steyer, 2012) affected the squamation, modifying size, shape, overlapping pattern, and the bone tissue of the scales (see Witzmann, 2011, for a thorough review). However, the current lack of knowledge on the squamation of the earliest tetrapods does not allow testing or drawing of broader evolutionary scenarios. Here we furnish the first highly detailed three-dimensional reconstructions of the scales of the Devonian tetrapod Tulerpeton, thereby providing new interpretations on the morphological and microstructural evolution of the squamation in early tetrapods.
Neoarchean carbonate–associated sulfate records positive Δ33S anomalies
Paris et al
Mass-independent fractionation of sulfur isotopes (reported as Δ33S) recorded in Archean sedimentary rocks helps to constrain the composition of Earth’s early atmosphere and the timing of the rise of oxygen ~2.4 billion years ago. Although current hypotheses predict uniformly negative Δ33S for Archean seawater sulfate, this remains untested through the vast majority of Archean time. We applied x-ray absorption spectroscopy to investigate the low sulfate content of particularly well-preserved Neoarchean carbonates and mass spectrometry to measure their Δ33S signatures. We report unexpected, large, widespread positive Δ33S values from stratigraphic sections capturing over 70 million years and diverse depositional environments. Combined with the pyrite record, these results show that sulfate does not carry the expected negative Δ33S from sulfur mass-independent fractionation in the Neoarchean atmosphere.
Monday, November 24, 2014
One reason I'm not worried about the possibility that we will soon make machines that are smarter than us, is that we haven't managed to make machines until now that are smart at all. Artificial intelligence isn't synthetic intelligence: It's pseudo-intelligence.
This really ought to be obvious. Clocks may keep time, but they don't know what time it is. And strictly speaking, it is we who use them to tell time. But the same is true of Watson, the IBM supercomputer that supposedly played Jeopardy! and dominated the human competition. Watson answered no questions. It participated in no competition. It didn't do anything. All the doing was on our side. We played Jeapordy! with Watson. We used "it" the way we use clocks.
Philosophers and biologists like to compare the living organism to a machine. And once that's on the table, we are lead to wonder whether various kinds of human-made machines could have minds like ours, too.
Japan has announced the selection of the Northrop Grumman RQ-4 Global Hawk for its high-altitude unmanned aerial vehicle (UAV) requirement and the Bell-Boeing V-22 Osprey for its tilt-rotor requirement.
The Ministry of Defence (MoD) also confirmed that it would buy a Northrop Grumman E-2D Advanced Hawkeye airborne early warning and control (AEW&C) aircraft. All three requirements were announced in the fiscal year 2015 budget request.
Minister for Defence Production Rana Tanveer Hussain told Dawn on Friday the matter was being discussed with Chinese authorities.
It is for the first time that a senior government functionary has confirmed talks with China over purchase of the longer-range stealth aircraft — an issue that has been a subject of speculation in defence circles since the 10th edition of the Zhuhai Air Show (China) held earlier this month, when the aircraft was unveiled.
The Jane’s Defence Weekly had quoted an unnamed Pakistani official as saying that the PAF was holding talks with China for the purchase of 30 to 40 of the Shenyang FC-31 fighter planes and that discussions had gone beyond initial inquiries.
The FC-31 is being developed by China primarily for the export market. Chinese officials claim that several countries have expressed interest in the aircraft believed to be comparable to US F-35 Joint Strike Fighter.
A prototype of the aircraft, designated as J-31, has been flown by the Chinese aircraft research and development firm Shenyang Aviation Company for a couple of years now.
What particularly interests the PAF is that FC-31 prototype (J-31) and JF-17 use the same Russian Klimov RD-93 engines.
Pakistan is increasingly relying on China as a reliable source for its defence procurements.
Mr Hussain said that Pakistan was also interested in Chinese attack helicopter Z-10.
Isotope compositions (C, O, Sr, Nd) of vertebrate fossils from the Middle Eocene oil shale of Messel, Germany: Implications for their taphonomy and palaeoenvironment
The Middle Eocene oil shale deposits of Messel are famous for their exceptionally well-preserved, articulated 47-Myr-old vertebrate fossils that often still display soft tissue preservation. The isotopic compositions (O, C, Sr, Nd) were analysed from skeletal remains of Messel's terrestrial and aquatic vertebrates to determine the condition of geochemical preservation. Authigenic phosphate minerals and siderite were also analysed to characterise the isotope compositions of diagenetic phases. In Messel, diagenetic end member values of the volcanically-influenced and (due to methanogenesis) 12C-depleted anoxic bottom water of the meromictic Eocene maar lake are isotopically very distinct from in vivo bioapatite values of terrestrial vertebrates. This unique taphonomic setting allows the assessment of the geochemical preservation of the vertebrate fossils. A combined multi-isotope approach demonstrates that enamel of fossil vertebrates from Messel is geochemically exceptionally well-preserved and still contains near-in vivo C, O, Sr and possibly even Nd isotope compositions while bone and dentine are diagenetically altered.
Enamel of the hippomorph perissodactyl Propalaeotherium has low δ13C values (− 9 ± 0.7‰), typical for C3-plant-feeders. Dentine of the same teeth has δ13C values 15–17‰ higher, amongst the highest δ13Cbioapatite values reported for terrestrial vertebrates. This reflects diagenetic carbonate exchange with the strongly 12C-depleted anoxic lake bottom water. Enamel 87Sr/86Sr values (~ 0.711 ± 0.001) are consistent with Propalaeotherium feeding on Palaeozoic bedrocks surrounding Lake Messel and suggests that the basaltic tuff ring around the maar was already eroded 640 ka after its formation. Dentine has, however, much lower, volcanically influenced 87Sr/86Sr (~ 0.706) due to diagenetic Sr uptake from the lake water/oil shale. Enamel δ18Op values (~ 18 ± 0.6‰) of Propalaeotherium are 2–3‰ lower than those of bones and scales of aquatic vertebrates that lived in the 18O-enriched lake water. Using transfer functions, a δ18OH2O value of − 5 ± 1‰ for meteoric water and a MAT of ~ 18 ± 2.5 °C were reconstructed for Messel.
A lander mission to probe subglacial water on Saturn׳s moon Enceladus for life
Konstantinidis et al
The plumes discovered by the Cassini mission emanating from the south pole of Saturn׳s moon Enceladus and the unique chemistry found in them have fueled speculations that Enceladus may harbor life. The presumed aquiferous fractures from which the plumes emanate would make a prime target in the search for extraterrestrial life and would be more easily accessible than the moon׳s subglacial ocean.
A lander mission that is equipped with a subsurface maneuverable ice melting probe will be most suitable to assess the existence of life on Enceladus. A lander would have to land at a safe distance away from a plume source and melt its way to the inner wall of the fracture to analyze the plume subsurface liquids before potential biosignatures are degraded or destroyed by exposure to the vacuum of space. A possible approach for the in situ detection of biosignatures in such samples can be based on the hypothesis of universal evolutionary convergence, meaning that the independent and repeated emergence of life and certain adaptive traits is wide-spread throughout the cosmos. We thus present a hypothetical evolutionary trajectory leading towards the emergence of methanogenic chemoautotrophic microorganisms as the baseline for putative biological complexity on Enceladus. To detect their presence, several instruments are proposed that may be taken aboard a future subglacial melting probe.
The “Enceladus Explorer” (EnEx) project funded by the German Space Administration (DLR), aims to develop a terrestrial navigation system for a subglacial research probe and eventually test it under realistic conditions in Antarctica using the EnEx-IceMole, a novel maneuverable subsurface ice melting probe for clean sampling and in situ analysis of ice and subglacial liquids. As part of the EnEx project, an initial concept study is foreseen for a lander mission to Enceladus to deploy the IceMole near one of the active water plumes on the moon׳s South-Polar Terrain, where it will search for signatures of life.
The general mission concept is to place the Lander at a safe distance from an active plume. The IceMole would then be deployed to melt its way through the ice crust to an aquiferous fracture at a depth of 100 m or more for an in situ examination for the presence of microorganisms.
The driving requirement for the mission is the high energy demand by the IceMole to melt through the cold Enceladan ices. This requirement is met by a nuclear reactor providing 5 kW of electrical power. The nuclear reactor and the IceMole are placed on a pallet lander platform. An Orbiter element is also foreseen, with the main function of acting as a communications relay between Lander and Earth.
After launch, the Lander and Orbiter will perform the interplanetary transfer to Saturn together, using the on-board nuclear reactor to power electric thrusters. After Saturn orbit insertion, the Combined Spacecraft will continue using Nuclear Electric Propulsion to reach the orbit of Enceladus. After orbit insertion at Enceladus, the Orbiter will perform a detailed reconnaissance of the South-Polar Terrain. At the end of the reconnaissance phase, the Lander will separate from the Orbiter and an autonomously guided landing sequence will place it near one of the active vapor plumes. Once landed, the IceMole will be deployed and start melting through the ice, while navigating around hazards and towards a target subglacial aquiferous fracture.
An initial estimation of the mission׳s cost is given, as well as recommendations on the further development of enabling technologies. The planetary protection challenges posed by such a mission are also addressed.
Total volcanic stratospheric aerosol optical depths and implications for global climate change
Ridley et al
Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming. Satellite observations of aerosol optical depth (AOD) above 15 km have demonstrated that small-magnitude volcanic eruptions substantially perturb incoming solar radiation. Here we use lidar, AERONET and balloon-borne observations to provide evidence that currently available satellite databases neglect substantial amounts of volcanic aerosol between the tropopause and 15 km at mid to high latitudes, and therefore underestimate total radiative forcing resulting from the recent eruptions. Incorporating these estimates into a simple climate model, we determine the global volcanic aerosol forcing since 2000 to be −0.19 ± 0.09 Wm−2. This translates into an estimated global cooling of 0.05 to 0.12 °C. We conclude that recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases that neglect volcanic aerosol effects below 15 km.
Short note on a non-pterodactyloid pterosaur from Upper Jurassic deposits of Inner Mongolia, China
Cheng et al
Daohugou is an important locality of the Jurassic Yanliao Biota, where only two pterosaurs have been described so far (Jeholopterus and Pterorhynchus). Here we report a new genus and species, Daohugoupterus delicatus gen. et sp. nov. (IVPP V12537), from this region, consisting of a partial skeleton with soft tissue. The skull is laterally compressed, differing from Jeholopterus. The antorbital fenestra is larger than in Pterorhynchus. The upper temporal fenestra is unusually small. The short cervical vertebrae bearing cervical ribs indicate that it is a non-pterodactyloid flying reptile. The sternal plate is triangular, being much wider than long. The deltopectoral crest of humerus is positioned proximally and does not extend further down the shaft, a typical feature of basal pterosaurs. Daohugoupterus also differs from the wukongopterids and scaphognathids from the Tiaojishan Formation at Linglongta, regarded to be about the same age as the Daohugou Bed. The new specimen increases the Jurassic non-pterodactyloid pterosaur diversity of the Yanliao Biota and is the smallest pterosaur from Daohugou area so far.
Simorhinella baini: Examining the Morphology of a Lycosuchid Therocephalian From Middle Permain South Africa
Adult morphology of the therocephalian Simorhinella baini from the middle Permian of South Africa and the taxonomy, paleobiogeography, and temporal distribution of the Lycosuchidae
Abdala et al
The Middle Permian tetrapod fauna of the South African Beaufort Group is taxonomically diverse and includes representatives of all major therapsid groups, including the earliest records of Eutheriodontia. In the Middle Permian, eutheriodonts are represented mainly by large therocephalians, which made up a large proportion of the vertebrate predators in these faunas. Here we describe the skull and partial skeleton of a large therocephalian from the uppermost Tapinocephalus Assemblage Zone (AZ) of South Africa. A combination of features, including the short snout, presence of three to four upper postcanines and presence of teeth on the pterygoid processes, indicates that the new specimen belongs to the earliest-diverging therocephalian family, Lycosuchidae. The presence of a well-developed midline ridge on the ventral surface of the vomer indicates that the new specimen can be referred to Simorhinella baini, a species previously represented only by a tiny juvenile skull. The new specimen forms the basis for a taxonomic re-evaluation of the Lycosuchidae as well as of the geographic and stratigraphic range of the family. We recognize two valid species within the Lycosuchidae: the type species Lycosuchus vanderrieti represented by five specimens and Simorhinella baini represented by two specimens, with an additional 22 specimens currently identifiable as Lycosuchidae incertae sedis. Lycosuchid specimens range throughout the Tapinocephalus and Pristerognathus AZs; specimens of Simorhinella are restricted to the Tapinocephalus AZ, whereas Lycosuchus specimens are documented in both the Tapinocephalus and Pristerognathus AZs.
Trait-based diversification shifts reflect differential extinction among fossil taxa
Wagner et al
Evolution provides many cases of apparent shifts in diversification associated with particular anatomical traits. Three general models connect these patterns to anatomical evolution: (i) elevated net extinction of taxa bearing particular traits, (ii) elevated net speciation of taxa bearing particular traits, and (iii) elevated evolvability expanding the range of anatomies available to some species. Trait-based diversification shifts predict elevated hierarchical stratigraphic compatibility (i.e., primitive→derived→highly derived sequences) among pairs of anatomical characters. The three specific models further predict (i) early loss of diversity for taxa retaining primitive conditions (elevated net extinction), (ii) increased diversification among later members of a clade (elevated net speciation), and (iii) increased disparity among later members in a clade (elevated evolvability). Analyses of 319 anatomical and stratigraphic datasets for fossil species and genera show that hierarchical stratigraphic compatibility exceeds the expectations of trait-independent diversification in the vast majority of cases, which was expected if trait-dependent diversification shifts are common. Excess hierarchical stratigraphic compatibility correlates with early loss of diversity for groups retaining primitive conditions rather than delayed bursts of diversity or disparity across entire clades. Cambrian clades (predominantly trilobites) alone fit null expectations well. However, it is not clear whether evolution was unusual among Cambrian taxa or only early trilobites. At least among post-Cambrian taxa, these results implicate models, such as competition and extinction selectivity/resistance, as major drivers of trait-based diversification shifts at the species and genus levels while contradicting the predictions of elevated net speciation and elevated evolvability models.
Geochemical and Sm-Nd isotopic characteristics of the Late Archaean-Palaeoproterozoic Dhanjori and Chaibasa metasedimentary rocks, Singhbhum craton, E. India: Implications for provenance, and contemporary basin tectonics
De et al
In significant contrast to other cratonic blocks of India, the Singhbhum cratonic successions record continuous depositional record from the Palaeoarchaean to Mesoproterozoic. Although the sedimentary facies characteristics and mode of stratigraphic sequence building of the Dhanjori and Chaibasa Formations are well known, sedimentary geochemistry, provenance and tectonic milieu of deposition of these two formations are hitherto unknown. The current manuscript presents geochemical and Sm-Nd isotopic data from the Dhanjori and Chaibasa Formations for the first time and combine previous sedimentological data with the goal to expand the framework for understanding the depositional and tectonic setting of these two formations. The Sm-Nd isotopic data for the Chaibasa clastics is unambiguous with respect to provenance. Average ɛNd (t = 2.2 Ga) = −0.8 ± 1.0 and average Nd model age (TDM) = 2.51 ± 0.08 Ga with average 147Sm/144Nd ratios = 0.1114 ± 0.0041 for phyllites and quartzites indicate an extremely homogeneous source signature consistent with a late Archaean “juvenile” crustal provenance, possibly a dominantly upper crustal provenance. The Sm-Nd isotopic data from the older Dhanjori Formation also indicate broadly similar provenance as comparable lithologies in the younger Chaibasa Formation. Our Sm-Nd isotopic data is entirely consistent with the previous sedimentological data and confirms a terrestrial, rift-dominated tectonic setting for the Dhanjori Formation (proximal sources, poorly mixed provenance) and a marginal marine to offshore setting for the more homogeneous Nd isotopic signature of the Chaibasa Formation (distal sources, well mixed provenance).
Friday, November 21, 2014
Validating Atmospheric Reanalysis Data Using Tropical Cyclones as Thermometers
Temperatures in the upper-troposphere of the atmosphere, near the tropopause, play a key role in the evolution of tropical cyclones (TC) by controlling their potential intensity (PI), which describes the thermodynamically-based maximum TC intensity that the environment will support. Accurately identifying past trends in PI is critical for understanding the causes of observed changes in TC intensity, but calculations of PI trends using different atmospheric reanalysis products can give very different results, due largely to differences in their representation of upper-tropospheric temperatures. Without a means to verify the fidelity of the upper tropospheric temperatures, PI trends calculated from these products are very uncertain.
Here, a method is introduced to validate the upper-tropospheric temperatures in the reanalysis products by using the TCs themselves as thermometers. Using a 30-year global dataset of TC cloud-top temperatures, and three widely-utilized atmospheric reanalysis products – MERRA, ERA-Interim, and NCEP/NCAR – it is shown that storm-local upper-level temperatures in the MERRA and ERA-Interim data vary similarly to the TC cloud-top temperatures on both interannual and decadal timescales, but the NCEP/NCAR data have substantial biases that introduce an increasing trend in storm-local PI not found in the other two products. The lack of global storm-local PI trends is due to a balance between temporal increases in the mean state and the poleward migration of TCs into lower climatological PI, and has significant implications for the detection and attribution of mean TC intensity trends.
Robots are increasingly replacing humans in a variety of mundane tasks, like bolting a car together or making lollipops, but now they are moving into the security business.
Microsoft recently installed a fleet of 5-feet-tall, 300-pound robots to protect its Silicon Valley campus. The robots are packed with HD security cameras and sensors to take in their organic, protein-based surroundings. There’s also an artificial intelligence on board that can sound alarms when the robot notices something awry. It can also read license plates and cross-reference them to see if they’re stolen.
The K5 robots come from a California company called Knightscope, which calls the robots “autonomous data machines” that provide a “commanding but friendly presence.” Sounds like something a robot manufacturer would say.
Logical Limitations to Machine Ethics with Consequences to Lethal Autonomous Weapons
Engleert et al
Lethal Autonomous Weapons promise to revolutionize warfare -- and raise a multitude of ethical and legal questions. It has thus been suggested to program values and principles of conduct (such as the Geneva Conventions) into the machines' control, thereby rendering them both physically and morally superior to human combatants.
We employ mathematical logic and theoretical computer science to explore fundamental limitations to the moral behaviour of intelligent machines in a series of "Gedankenexperiments": Refining and sharpening variants of the Trolley Problem leads us to construct an (admittedly artificial but) fully deterministic situation where a robot is presented with two choices: one morally clearly preferable over the other -- yet, based on the undecidability of the Halting problem, it provably cannot decide algorithmically which one. Our considerations have surprising implications to the question of responsibility and liability for an autonomous system's actions and lead to specific technical recommendations.
Soooo....does that imply PEOPLE are not Turing Machines??? *evil grin*
The US Office of Naval Research (ONR) is to brief industry on plans for the development of an Anti-Submarine Warfare (ASW) Mission Package (ASWMP) for its future Large Displacement Unmanned Undersea Vehicle (LDUUV).
This so-called 'Leap Ahead Project' is intended to develop ASW techniques and technologies in the areas of mission autonomy, situational awareness, and undersea sensors.
ONR's LDUUV Innovative Naval Prototype programme is developing a fully autonomous, long endurance UUV capable of extended operation (more than 60 days) in cluttered littoral environments. The programme has to date built three vehicles and is developing energy, autonomy, and core systems to operate in complex ocean environments.
According to the CEO of the Russian Helicopters Alexander Mikheev, the technical configuration of the joint Russian and Chinese heavy-lift transport helicopter is going to be determined by February 2015.
"We are currently developing the program of cooperation and division of responsibility of both the parties. We are determining the activities that each party is going to be in charge of. It is important to define which design bureaus are going to be engaged and what expertise and technologies we are going to use. In two or three months we are going to hold certain negotiations, where the configuration and flight performance of this helicopter will become clear," said Mr. Mikheev to the press at the international Air Show China-2014 opened in Zhuhai on Tuesday.
It was previously reported that the Russian and Chinese heavy-lift helicopter was planned to be developed based on the technologies of Mi-26T — the heaviest helicopter in the world produced by Rostvertol (part of Russian Helicopters).
CEO also noted that the new helicopter is not going to be similar to or a modernized version of the Russian heavy-lift Mi-26T helicopter.
Flying far is more important than flying fast, Japanese fighter technologists have found in studies aimed at defining their country’s next combat aircraft. Researchers are also emphasizing that Japan’s next fighter should share targeting data and carry a big internal load of large, high-performance missiles.
link. (behind paywall)
Finally, Aboulafia said the Navy may be interested in developing a super-capable air-dominance or air-to-air fighter capability as a new, next-generation aircraft to replace the F-14 Tomcat – an aircraft known for its air-to-air fighter capability.
buried at the end of the previous link.
The Navy is beginning to work on a a next-generation carrier-launched fighter jet to replace the existing F/A-18 Super Hornet and Growler aircraft by 2030 and supplement the F-35C the Pentagon is still developing, service officials said.
The Navy effort, called the F/A-XX program, includes early work on the desired technological capabilities for the new aircraft. The idea is to have a new aircraft ready and producible by the time existing F/A-18s reach their end-of-service dates.
The Navy is analyzing industry proposals on the F/A-XX it started collecting two years ago. Navy officials are trying to pick out what they like and eliminating the rest.
This effort is going on as the Navy considers various upgrades of the existing inventory of F/A-18s in order to extend its service life well into and beyond the 2030s. Nevertheless, unless more aircraft such as Growlers are purchased for future production, Boeing’s domestic production of the F/A-18 will come to an end in the next several years.
The new aircraft might also seek to develop the ability to fire hypersonic weapons, however such a development would hinge upon successful progress with yet-to-be-proven technologies such as scramjets, Aboulafia added.
Super cruise technology would enable the new fighter jet to cruise at supersonic speeds without needing afterburner, he explained.
Smart aircraft skins would involve dispersing certain technologies or sensors across the fuselage and further integrating them into the aircraft itself, Aboulafia said.
‘Smart skins with distributed electronics means that instead of having systems mounted on the aircraft, you would have apertures integrated on the skin of the aircraft,” he said.
This could reduce drag, increase speed and maneuverability while increasing the technological ability of the sensors.
Coryphoid Palm Leaf Fossils from the Maastrichtian–Danian of Central India with Remarks on Phytogeography of the Coryphoideae (Arecaceae)
Authors:Srivastava et al
Abstract:Premise of researchA large number of fossil coryphoid palm wood and fruits have been reported from the Deccan Intertrappean beds of India. We document the oldest well-preserved and very rare costapalmate palm leaves and inflorescence like structures from the same horizon.MethodologyA number of specimens were collected from Maastrichtian–Danian sediments of the Deccan Intertrappean beds, Ghughua, near Umaria, Dindori District, Madhya Pradesh, India. The specimens are compared with modern and fossil taxa of the family Arecaceae.Pivotal resultsSabalites dindoriensis sp. nov. is described based on fossil leaf specimens including basal to apical parts. These are the oldest coryphoid fossil palm leaves from India as well as, at the time of deposition, from the Gondwana- derived continents.ConclusionsThe fossil record of coryphoid palm leaves presented here and reported from the Eurasian localities suggests that this is the oldest record of coryphoid palm leaves from India and also from the Gondwana- derived continents suggesting that the coryphoid palms were well established and wide spread on both northern and southern hemispheres by the Maastrichtian–Danian. The coryphoid palms probably dispersed into India from Europe via Africa during the latest Cretaceous long before the Indian Plate collided with the Eurasian Plate.
Forming Ganymede’s grooves at smaller strain: Toward a self-consistent local and global strain history for Ganymede
Bland et al
The ubiquity of tectonic features formed in extension, and the apparent absence of ones formed in contraction, has led to the hypothesis that Ganymede has undergone global expansion in its past. Determining the magnitude of such expansion is challenging however, and extrapolation of locally or regionally inferred strains to global scales often results in strain estimates that exceed those based on global constraints. Here we use numerical simulations of groove terrain formation to develop a strain history for Ganymede that is generally consistent at local, regional, and global scales. These simulations reproduce groove-like amplitudes, wavelengths, and average slopes at modest regional extensions (10–15%). The modest strains are more consistent with global constraints on Ganymede’s expansion. Yet locally, we also find that surface strains can be much larger (30–60%) in the same simulations, consistent with observations of highly-extended impact craters. Thus our simulations satisfy both the smallest-scale and largest-scale inferences of strain on Ganymede. The growth rate of the topography is consistent with (or exceeds) predictions of analytical models, and results from the use of a non-associated plastic rheology that naturally permits localization of brittle failure (plastic strain) into linear fault-like shear zones. These fault-like zones are organized into periodically-spaced graben-like structures with stepped, steeply-dipping faults. As in previous work, groove amplitudes and wavelengths depend on both the imposed heat flux and surface temperature, but because our brittle strength increases with depth, we find (for the parameters explored) that the growth rate of topography is initially faster for lower heat flows. We observe a transition to narrow rifting for higher heat flows and larger strains, which is a potential pathway for breakaway margin or band formation.
Rapid climate change did not cause population collapse at the end of the European Bronze Age
Armit et al
The impact of rapid climate change on contemporary human populations is of global concern. To contextualize our understanding of human responses to rapid climate change it is necessary to examine the archeological record during past climate transitions. One episode of abrupt climate change has been correlated with societal collapse at the end of the northwestern European Bronze Age. We apply new methods to interrogate archeological and paleoclimate data for this transition in Ireland at a higher level of precision than has previously been possible. We analyze archeological 14C dates to demonstrate dramatic population collapse and present high-precision proxy climate data, analyzed through Bayesian methods, to provide evidence for a rapid climatic transition at ca. 750 calibrated years B.C. Our results demonstrate that this climatic downturn did not initiate population collapse and highlight the nondeterministic nature of human responses to past climate change.
Working at the edge of a coal mine in India, a team of Johns Hopkins researchers and colleagues have filled in a major gap in science's understanding of the evolution of a group of animals that includes horses and rhinos. That group likely originated on the subcontinent when it was still an island headed swiftly for collision with Asia, the researchers report Nov. 20 in the online journal Nature Communications.
Modern horses, rhinos and tapirs belong to a biological group, or order, called Perissodactyla. Also known as "odd-toed ungulates," animals in the order have, as their name implies, an uneven number of toes on their hind feet and a distinctive digestive system. Though paleontologists had found remains of Perissodactyla from as far back as the beginnings of the Eocene epoch, about 56 million years ago, their earlier evolution remained a mystery, says Ken Rose, Ph.D., a professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.
Rose and his research team have for years been excavating mammal fossils in the Bighorn Basin of Wyoming, but in 2001 he and Indian colleagues began exploring Eocene sediments in Western India because it had been proposed that perissodactyls and some other mammal groups might have originated there. In an open-pit coal mine northeast of Mumbai, they uncovered a rich vein of ancient bones. Rose says he and his collaborators obtained funding from the National Geographic Society to send a research team to the mine site at Gujarat in the far Western part of India for two weeks at a time once every year or two over the last decade.
The mine yielded what Rose says was a treasure trove of teeth and bones for the researchers to comb through back in their home laboratories. Of these, more than 200 fossils turned out to belong to an animal dubbed Cambaytherium thewissi, about which little had been known. The researchers dated the fossils to about 54.5 million years old, making them slightly younger than the oldest known Perissodactyla remains, but, Rose says, it provides a window into what a common ancestor of all Perissodactyla would have looked like. "Many of Cambaytherium's features, like the teeth, the number of sacral vertebrae, and the bones of the hands and feet, are intermediate between Perissodactyla and more primitive animals," Rose says. "This is the closest thing we've found to a common ancestor of the Perissodactyla order."
Cambaytherium and other finds from the Gujarat coal mine also provide tantalizing clues about India's separation from Madagascar, lonely migration, and eventual collision with the continent of Asia as the Earth's plates shifted, Rose says. In 1990, two researchers, David Krause and Mary Maas of Stony Brook University, published a paper suggesting that several groups of mammals that appear at the beginning of the Eocene, including primates and odd- and even-toed ungulates, might have evolved in India while it was isolated. Cambaytherium is the first concrete evidence to support that idea, Rose says. But, he adds, "It's not a simple story."
Through the careful study of modern and early fossil tortoise, researchers now have a better understanding of how tortoises breathe and the evolutionary processes that helped shape their unique breathing apparatus and tortoise shell. The findings published in a paper, titled: Origin of the unique ventilatory apparatus of turtles, in the scientific journal, Nature Communications, on Friday, 7 November 2014, help determine when and how the unique breathing apparatus of tortoises evolved.
Lead author Dr Tyler Lyson of Wits University's Evolutionary Studies Institute, the Smithsonian Institution and the Denver Museum of Nature and Science said: "Tortoises have a bizarre body plan and one of the more puzzling aspects to this body plan is the fact that tortoises have locked their ribs up into the iconic tortoise shell. No other animal does this and the likely reason is that ribs play such an important role in breathing in most animals including mammals, birds, crocodilians, and lizards."
Instead tortoises have developed a unique abdominal muscular sling that wraps around their lungs and organs to help them breathe. When and how this mechanism evolved has been unknown.
"It seemed pretty clear that the tortoise shell and breathing mechanism evolved in tandem, but which happened first? It's a bit of the chicken or the egg causality dilemma," Lyson said. By studying the anatomy and thin sections (also known as histology), Lyson and his colleagues have shown that the modern tortoise breathing apparatus was already in place in the earliest fossil tortoise, an animal known as Eunotosaurus africanus.
CONFIRMING THE METAZOAN CHARACTER OF A 565 MA TRACE-FOSSIL ASSEMBLAGE FROM MISTAKEN POINT, NEWFOUNDLAND
Liu et al
Surface locomotory trace fossils from the Mistaken Point Formation of Newfoundland, dated at ∼ 565 Ma, suggest that organisms capable of controlled locomotion and possessing muscular tissue may have existed among Avalonian Ediacaran macrofossil assemblages. Here we describe the Mistaken Point trace-fossil assemblage in full, discuss its stratigraphic context within the Mistaken Point Formation, and explore the competing hypotheses for the formation of the traces. We find that the trace fossils, preserved within a turbidite succession in a deep-marine depositional environment, are not attributable to abiogenic structures, to Ediacaran tubular or filamentous body fossils, to rangeomorph stems, or to a host of late Ediacaran and early Phanerozoic ichnofossils. Specimens within the assemblage show some similarities to the ichnogenera Helminthoidichnites and Archaeonassa, but discrepancies in certain aspects of their structure mean that we do not formally attribute them to these ichnotaxa at this time. The Mistaken Point ichnofossils possess morphological characteristics indicative of formation by an organism with a round base. Comparison with traces formed by modern organisms of such character appears to rule out formation by protistan, echinoderm, or annelid styles of movement, but is consistent with organisms moving via muscular controlled locomotion in a similar way to some modern mollusks and actinian cnidarians. We suggest therefore that the Mistaken Point trace-fossil assemblage reveals the presence of muscular metazoans in late Ediacaran deep-marine ecosystems. Such organisms cannot yet be attributed to specific phyla, but their inferred locomotory mechanisms share closest similarities with those utilized by extant actinians.
On the track of the elusive sudbury impact: geochemical evidence for a chondrite or comet bolide
Petrus et al
Siderophile and lithophile trace element data for 69 samples from the Sudbury impact crater fill (Onaping Formation) and quartz diorite offset dikes help constrain the sources of the established moderately elevated platinum group element signature associated with the impact structure. The siderophile element distribution of the crater fill requires contributions from bulk continental crust, mafic rocks and a chondritic component. A mantle component is absent, but the involvement of mid to lower crust is implied. After considering post-impact hydrothermal alteration, melt heterogeneity, and mafic target admixture, the projectile elemental ratios were determined on a more robust data subset. Chondrite discrimination diagrams of these ratios identify an ordinary or enstatite chondrite as the most probable source of meteoritic material in the Sudbury crater fill. However, the relative and absolute siderophile element distributions within the impact structure as well as bolide size models are congruent with the bolide being a comet that had a chondritic refractory component.
Thursday, November 20, 2014
China will aim for a peak in greenhouse gas emissions by 2030, while the United States will strive to cut total emissions by more than a quarter by 2025, as the two countries try to drive through a new global climate pact in Paris next year.
According to a joint announcement by President Xi Jinping and U.S. counterpart Barack Obama in Beijing on Wednesday, China will aim to reach peak CO2 emissions by "around 2030" and strive to achieve the target earlier, while the United States would slash emissions by 26 percent to 28 percent from the 2005 level.
Senior U.S. administration officials said the commitments, which are the result of months of dialogue between the world's top two CO2 emitters, would encourage other nations to make pledges and deliver "a shot of momentum" into negotiations for a new global agreement set to go into force in 2020.
"It is a very good sign for both countries and injects strong momentum (into negotiations), but the targets are not ambitious enough and there is room for both countries to negotiate an improvement," said Tao Wang, climate scholar at the Tsinghua-Carnegie Center for Global Policy in Beijing.
China also pledged to increase the share of non-fossil fuels in its energy mix to around 20 percent by 2030, from less than 10 percent in 2013, a move that could require 1,000 gigawatts of new nuclear and renewable capacity, but Wang said the figure took China little further than "business as usual".
"That figure isn't high, because China aims to reach about 15 percent by 2020, so it is only a five percentage point increase in 10 years, and given the huge growth in renewables, it should be higher," he said.
The Brazilian Air Force (Força Aérea Brasileira: FAB) expects to field "at least" 108 Saab Gripen E/F combat aircraft by the time deliveries are complete, a senior service official disclosed on 18 November.
Speaking under the Chatham House Rule at the IQPC Fighter Conference in London, the officer said that the aircraft will be delivered in three batches running from 2019 through to 2032, adding that the USD5.4 billion contract announced in October for 36 aircraft represents just the first batch (these will be delivered by 2024).
A lack of experience and training, as well as poor tactics and intelligence not being acted on are the primary reasons for losses being incurred by the Ukrainian Air Force in the restive east of the country, a senior service official noted on 19 November.
Speaking under the Chatham House Rule at the IQPC Fighter Conference in London, the officer said that these are the main factors behind the loss of 10 helicopters, nine combat aircraft, and three airlifters lost to separatist air defences to date.
"In total, we have lost five Mi-8 ['Hip'] and five Mi-24 ['Hind'] helicopters; six Su-25 ['Frogfoot'], one Su-24 ['Fencer'], and two MiG-29 ['Fulcrum'] fighters; as well as one An-26 ['Curl'], one An-30 ['Clank'], and one Il-76 ['Candid'] transport aircraft. In my personal view, the reasons [behind these losses] are that in 23 years since independence we have never had to use our aircraft or pilots in combat before, and so there is no experience; we have not given enough money to training; our tactics have not always been the right ones; and intelligence of man-portable air defence systems [MANPADS] has not always been acted on," he said.
As evidenced by the high loss rate, Ukraine's ageing inventory is struggling in the current combat conditions. "Our Su-27s, Su-24s, Su-25s, MiG-29s, and L-39s were built mostly in the late 1980s and early 1990s. They are inferior in combat [to more modern types], and their physical condition is obsolete," the official noted.
While this fleet could probably be maintained in an airworthy condition for about another 10 years (with Ukrainian electronic and system upgrades), the official said, the air force is looking at a medium- to long-term replacement.
The types being considered are the Lockheed Martin F-16C Block 52, Eurofighter Typhoon, Dassault Rafale, Saab Gripen E/F, and Boeing F/A-18E/F Super Hornet. "We are looking at [acquiring] these aircraft from about 2020 to 2030," he said, adding that Ukraine is looking at options for fielding an unmanned combat air vehicle also.
Early design work on the Navy’s next generation amphibious warship — based on the San Antonio-class (LPD-17) hull — has begun ahead of a planned 2020 procurement, Navy officials said on Wednesday.
The design work for the LX(R) after a longer-than-usual back and forth on the analysis of alternatives (AOA) discussion for the future class of 11-ships with a request for proposal to industry due out in 2017, said Capt. Erik Ross with Office of the Chief of Naval Operations amphibious warfare division (OPNAV N95).
The Navy’s effort to replace the aging Whidbey Island and Harpers Ferry 16,000-ton landing ship docks (LSD-41/49) is focused on driving cost out of the new class at the direction of the Navy’s chief shipbuilder, Sean Stackley, Assistant Secretary of the Navy for Research, Development & Acquisition (RDA), Ross said.
“The whole reason the AoA was paused was for us to get smarter on cost estimates earlier,” Ross told reporters during NDIA’s Expeditionary Warfare Conference.
“Historically ship building programs they go along and they cost more and the [Chief of Naval Operations] and Mr. Stackley said, [no].”
The lead ship of a San Antonio derived LX(R) would cost about $1.64 billion with follow-ons costing about $1.4 billion for a total of 11 ships, according to information from the service.
Last month the service decided to use the LPD-17 hull as the basis for LX(R), according to a memo signed by Secretary of the Navy Ray Mabus. That decision was largely based on the trend of the three ships that comprise the Navy and Marine Amphibious Ready Group/Marine Expeditionary Unit (ARG/MEU) operating more independently as disaggregated forces, Ross said.
Russia's new Armata main battle tank (MBT) is too expensive, according to Russian Military-Industrial Commission deputy chairman Oleg Bochkarev.
According to comments reported by state news agency TASS, Bochkarev said the pricing for a three-year contract with Uralvagonzavod (UVZ) had been agreed, but implied that for subsequent vehicles the unit price would need to decrease.
UVZ deputy general director Vyacheslav Khalitov told Interfax-AVN on 18 November that the cost of Russia's new Armata MBT would "stabilise" when large-scale serial production begins. He added that new systems and components are expensive and represent 80% of the tank's cost. A production contract for 2015-17 has been signed, according to Khalitov.
Palynology of Aptian and upper Albian (Lower Cretaceous) amber-bearing outcrops of the southern margin of the Basque-Cantabrian basin (northern Spain)
Barrón et al
The Lower Cretaceous deposits of the southern margin of the Basque-Cantabrian basin (northern Spain) are characterised by continental deposits interbedded with amber-bearing marine-influenced facies. These facies crop out in various localities and have yielded well-preserved palynological assemblages. The palynoflora is dominated by gymnosperm pollen grains, and shows relatively diversified spore content but scarce dinoflagellate cysts. The palynofloral evidence and regional geological setting indicate that the studied successions are dated as Aptian (Montoria-La Mina outcrop) and late Albian (Peñacerrada 1 and 2 and Salinillas de Buradón outcrops, and the Pancorbo site). Angiosperm pollen does not constitute a significant part of the Aptian assemblages but becomes diversified and numerically abundant in those dated as late Albian. Although broadly similar to contemporaneous palynofloras from eastern Spain, the Aptian assemblages of Montoria-La Mina do not yield tricolpate angiosperm pollen. Conversely, the inferred late Albian assemblages show a high content in polyaperturate angiosperm pollen grains, as occurs in other localities in Portugal, Western Europe and North America. The studied palynoflora shows significant differences from published assemblages located further north, in western France and Canada.
Iron snow dynamo models for Ganymede
Ganymede’s internal magnetic field is dominated by the axial dipole. The measurements by the Galileo spacecraft only place an upper limit on the quadrupole moment. Ganymede’s magnetic field has the lowest ratio of quadrupole power to dipole power for all known planetary dynamos, not only at the planetary surface but possibly also at the top of the dynamo region. The dynamo operates in a fluid iron core that probably contains a significant amount of sulfur. Crystallization of the core will then proceed from the top by formation of iron snow in a layer that develops a stable compositional gradient. Remelting of the snow at the bottom of this layer enriches the underlying fluid in iron and drives compositional convection. Here we explore the consequences for the dynamo process of this scenario by numerical modeling. Convection is driven by an imposed buoyancy flux at the top of a convecting core region that is surrounded by a conducting fluid shell with a strongly stabilizing density gradient. Only horizontal flow is allowed in the outer shell. It is shown that this is a valid approximation in the case where the stabilizing density contrast in the upper shell exceeds by far the unstable density contrast in the convecting region. We vary the basic control parameters, concentrating on the regime where the magnetic field is dominantly dipolar. Compared to reference cases without an extra layer above the dynamo, we find that a stable fluid conducting layer with a thickness of 100 km or larger reduces the ratio of quadrupole power R2R2 to dipole power R1R1 by a factor of at least four. With a stable outer layer R2/R1R2/R1 is compatible with the Galileo observations for all tested dipolar models, whereas in the absence of such layer R2/R1R2/R1 is too large or at best marginally compatible. For plausible values of the buoyancy flux the models reproduce Ganymede’s observed dipole moment. A stable layer that is comparable in thickness to the unstable region is found to promote a hemispherical type of dynamo whose field in incompatible with observations. This may indicate that the snow layer in Ganymede’s core has a moderate depth extent.
Ancient DNA unravels the truth behind the controversial GUS Greenlandic Norse fur samples: the bison was a horse, and the muskox and bears were goats
Sinding et al
The Norse Greenlandic archaeological site known as ‘the Farm Beneath the Sand’ (GUS) has sourced many well-preserved and unique archaeological artefacts. Some of the most controversial finds are tufts of hair, which previous morphological-based examination concluded derive from bison, black bear, brown bear and muskox, all species whose natural presence in South Greenland is unlikely. If true, the consequences are potentially significant, as they could imply Viking trading with, or hunting within, North America. To validate these previous findings, we genetically profiled the samples, through mitochondrial 16S DNA analysis. The results revealed that the putative bison was, in fact horse, while the bears and muskox were goat. The results demonstrate the importance of using genetic analyses to validate results derived from morphological analyses on hair, in particular where such studies lead to sensational claims.