An experimental cancer treatment that alters the DNA of patients has won a key approval to proceed with its first human tests using the controversial gene-altering tool known as Crispr.
An experimental cancer treatment that alters the DNA of patients has won a key approval to proceed with its first human tests using the controversial gene-altering tool known as Crispr.
Authors:Hammond et alAbstract:The New Horizons spacecraft has found evidence for geologic activity on the surface of Pluto, including extensional tectonic deformation of its water ice bedrock (see Moore et al. ). One mechanism that could drive extensional tectonic activity is global surface expansion due to the partial freezing of an ocean. We use updated physical properties for Pluto and simulate its thermal evolution to understand the survival of a possible subsurface ocean. For thermal conductivities of rock less than 3 W m−1 K−1, an ocean forms and at least partially freezes, leading to recent extensional stresses in the ice shell. In scenarios where the ocean freezes and the ice shell is thicker than 260 km, ice II forms and causes global volume contractions. Since there is no evidence for recent compressional tectonic features, we argue that ice II has not formed and that Pluto's ocean has likely survived to present day.
Obliquity Variability of a Potentially Habitable Early Venus
Barnes et al
Venus currently rotates slowly, with its spin controlled by solid-body and atmospheric thermal tides. However, conditions may have been far different 4 billion years ago, when the Sun was fainter and most of the carbon within Venus could have been in solid form, implying a low-mass atmosphere. We investigate how the obliquity would have varied for a hypothetical rapidly rotating Early Venus. The obliquity variation structure of an ensemble of hypothetical Early Venuses is simpler than that Earth would have if it lacked its large moon (Lissauer et al., 2012), having just one primary chaotic regime at high prograde obliquities. We note an unexpected long-term variability of up to ±7° for retrograde Venuses.
Orbital ATK’s continuing preparations to return its Antares rocket to flight operations has resulted in an updated preliminary launch date in the August timeframe. The launch – involving the OA-5 Cygnus spacecraft to the International Space Station (ISS) – requires static fire test data analysis to be completed, along with final trajectory shaping work.
When do laser weapons finally become real? The low-hanging fruit for a near-term application looks like it’s shooting down enemy drones before they can target US forces. Both the Army and Marines are testing vehicle-mounted “counter-UAS” (Unmanned Aerial System) lasers, while the Navy already has a bulkier model aboard the USS Ponce in the Persian Gulf.
The Marine Corps is moving towards a future in which small dispersed units can protect themselves from incoming enemy drones with laser weapons and from missiles and aircraft with Stinger missiles, with both weapons netted into a detection system and mounted atop Humvees, Joint Light Tactical Vehicles and other combat vehicles.
The Navy is “fully committed” to developing and fielding advanced directed energy weapons to deal with emerging threats and to reduce the cost per shot, the Navy’s number two officer said today.
“We need to push technology forward” and do it faster than historic advances in fielding new weapons capabilities, Vice Chief of Naval Operations Adm. William Moran said at the Directed Energy Summit, cohosted by Booz Allen Hamilton and the Center for Strategic and Budgetary Assessment.
Moran noted that the Navy had “already authorized a defensive weapon” and deployed it, citing the laser system mounted on the USS Ponce (AFSB(I)-15), which is on station in the U.S. Central Command theater.
The 30 kilowatt solid-state XN-1 laser on Ponce has been authorized for use as a defensive weapon, he said. The Navy “will field a 100-kilowatt system in the near future,” he added.
Using genetic markers, researchers have for the first time shown how cultivating a specific crop led to the expansion of a pollinator species. In this case, the researchers found that the spread of a bee species in pre-Columbian Central and North America was tied to the spread of squash agriculture.
"We wanted to understand what happens when the range of a bee expands," says Margarita López-Uribe, a postdoctoral researcher at North Carolina State University and lead author of a paper describing the work. "What does that mean for its genetic variability? And if the genetic variability declines, does that harm the viability of the species?"
To explore these questions, researchers looked at the squash bee (Peponapis pruinosa), which is indigenous to what is now central Mexico and the southwestern United States. Squash bees are specialists, collecting pollen solely from the flowers of plants in the genus Cucurbita, such as squash, zucchini and pumpkins.
Before contact with Europeans, native American peoples had begun cultivating Cucurbita crops. Over time, these agricultural practices spread to the north and east.
"We wanted to know whether P. pruinosa spread along with those crops," López-Uribe says.
To find out, researchers looked at DNA from squash bee individuals, collected from throughout the species' range. P. pruinosa can now be found from southern Mexico to California and Idaho in the west, and from Georgia in the southeast to Quebec in the north.
By assessing genetic markers in each bee's DNA, the researchers could identify genetic signatures associated with when and where the species expanded.
A new anthracothere (Artiodactyla) from the early Oligocene, Fayum, Egypt, and the mystery of African ‘Rhagatherium’ solved
Sileem et al
Recent work on new anthracothere (Mammalia, Artiodactyla) specimens from the Jebel Qatrani Formation, early Oligocene, Fayum, Egypt, has revealed the presence of a new genus. Nabotherium new genus is described on the basis of a partial skull, several mandibular and maxillary specimens, and isolated teeth. The new genus exhibits a distinctive combination of features not seen in other Paleogene anthracotheres. The most noticeable characteristics of the new genus include the presence of large and well-developed upper and lower canines, caniniform third incisors, the presence of only a short diastema between the canine and first premolar, and broad, bunodont cheek teeth. This is in contrast to other contemporary anthracotheres, including other forms from the Fayum, which show a spatulate third incisor, a reduced canine, a much longer canine-premolar diastema, and more narrow, bunoselenodont cheek teeth. The presence of a relatively short rostrum with closely packed incisors, low-crowned and simple premolars, and low-crowned, bunodont molars indicates that members of the new genus would have been more efficient at crushing foods than slicing vegetation, and suggests a more varied herbivorous and frugivorous diet than was favored by other, more bunoselenodont Fayum anthracotheres.
The manus of Mylodon darwinii Owen (Tardigrada, Mylodontidae) and its phylogenetic implications
Haro et al
The first nearly complete and articulated manus of the ground sloth Mylodon darwinii, from the upper Pleistocene of Argentina, is described. It shares similarities with Mylodonopsis ibseni from Brazil, including a cuneiform with a distinct pisiform facet, an obliquely concave ulnar facet, and a prominent distolateral process, as well as a gracile metacarpal III. It shares a flattened pisiform with Glossotherium robustum. The trapezoid is unique in the obliquely elongate proportions of its dorsal surface. Shapes of the articular facets indicate different functions in digits II and III, with the former having a greater range of motion and the latter greater stability at the joints. Clear arboreal or fossorial adaptations are absent. A phylogenetic analysis recovered M. darwinii as closely related to M. ibseni and agrees with larger phylogenetic analyses of sloths based on craniomandibular evidence. Our data support more than two mylodontine dispersal events to North America.
Carbonate rocks and related facies with vestiges of biomarkers: Clues to redox conditions in the Mesoproterozoic ocean
Patranabis-Deb et al
The Raipur Group of the Chattisgarh Basin preserves two major Late Mesoproterozoic carbonate platforms. The lower platform is about 490-m thick, separated from the upper platform (~ 670 m thick) by a 500-m thick calcareous shale. Carbonate strata cover almost 40% of the Chattisgarh Basin outcrop and represent two major platform types: a) a non-stromatolitic ramp (the Charmuria/Sarangarh Limestone) and b) a platform developed chiefly in the intertidal to shallow subtidal environment with prolific growth of stromatolites (the Chandi/Saradih Limestone). The first platform consists primarily of the black Timarlaga limestone that is locally replaced by early diagenetic dolomite. This carbonate platform experienced strong storm waves and was subsequently drowned by a major transgression, during which extensive black limestone–marl rhythmite was deposited, followed by deposition of the Gunderdehi Shale. The carbonate factory was later re-established with development of an extensive stromatolite-dominated Charmuria/Sarangarh platform that ranged from restricted embayment to open-marine conditions. Sea-level change played a major role in controlling the broad facies pattern and platform evolution. The δ13C signatures of the Chattisgarh limestones, falling within a relatively narrow range (0 to + 4‰) are typical for Upper Mesoproterozoic carbonate rocks. δ18O values, however, have a greater range (− 5.7 to − 13.3‰) indicating significant diagenetic alteration of some samples. Likely dysoxic or anoxic conditions prevailed during deposition of the black Timarlaga limestone and well-oxygenated conditions during deposition of the Gunderdehi Shale and Saradih/Chandi stromatolite. The lack of 17β,21α (moretanes) and high Tmax values suggest mature organic matter in the non-stromatolitic ramp. A paucity of diagnostic eukaryotic steroids indicates that algae were rare in the Chattisgarh Basin. A high content of hopanes supports a generally bacterially-dominated Proterozoic ocean in which various stromatolites flourished.
It’s a major component of solid rocket propellants. It allows water to exist as liquid on Mars, despite atmospheric pressure at the Martian surface being roughly 0.6 percent that on Earth. It also can be broken down to release oxygen that astronauts and future colonists in a Mars settlement could breathe.
It’s called perchlorate and it’s abundant on Mars –10,000 times more abundant in Martian dirt than in soils and sands of Earth. That may sound like a good thing, considering the useful properties of perchlorate, but there’s also a flip side.
Being a negative ion, perchlorate (ClO4–) forms various salts, but it has detrimental health effects. Potassium perchlorate is used as a drug to treat certain forms of hyperthyroidism (overactive thyroid). But exposure to environmental perchlorate causes the opposite of hyperthyroidism, namely hypothyroidism — an underactive thyroid.
It would be devastating for Martian colonists.
United Launch Alliance says it has identified and resolved the problem on its most recent Atlas 5 launch, a March 22 flight for Orbital ATK that successfully delivered the unmanned Cygnus space station resupply vehicle to orbit.
In a statement June 15, the Denver-based company said an “unexpected shift in fuel pressure differential” across a mixture ratio control valve in the RD-180 engine, nearly four minutes after liftoff, caused the engine to run oxidizer-rich.
That depleted the supply of liquid oxygen and shut down the engine prematurely, even though there was still “significant fuel” left on the first stage. Atlas 5’s Centaur upper stage compensated for the first stage performance shortfall with an extended burn, delivering Cygnus to its intended orbit “well within the required accuracy.”
As difficult as any rocket is the engineering required to created powered armor that carries its own weight without burdening the wearer, an military exoskeleton like Heinlein’s Mobile Infantry or Marvel’s Iron Man. The Special Operations Command is researching such a system, TALOS, but when asked about its applicability to the rest of the Army, Allyn was skeptical.
“Currently, in the conventional force, I doubt we could afford it in the near term,” at least on any large scale, said Allyn. So are you at least interested? “I wouldn’t say as yet I’m interested because I try not to get interested in things I cant afford,” Allyn said with a smile. “I don’t go to the Jaguar and Mercedes dealerships.”
Of course, if the Army got more money, it could make different choices. Currently the service is “mortgaging” long-term modernization to pay for near-term readiness, Allyn said, which puts a damper on all new technologies. “The way out obviously is increased topline — and there’s not a likelihood of receiving that,” Allyn said.
Giant Ice Age species including elephant-sized sloths and powerful sabre-toothed cats that once roamed the windswept plains of Patagonia, southern South America, were finally felled by a perfect storm of a rapidly warming climate and humans, a new study has shown.
Research led by the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, published today in Science Advances, has revealed that it was only when the climate warmed, long after humans first arrived in Patagonia, did the megafauna suddenly die off around 12,300 years ago.
The timing and cause of rapid extinctions of the megafauna has remained a mystery for centuries.
"Patagonia turns out to be the Rosetta Stone - it shows that human colonisation didn't immediately result in extinctions, but only as long as it stayed cold," says study leader Professor Alan Cooper, ACAD Director. "Instead, more than 1000 years of human occupation passed before a rapid warming event occurred, and then the megafauna were extinct within a hundred years."
Owenettids and procolophonids from the lower Keuper shed new light on the diversity of parareptiles in the German Middle Triassic
Martinelli et al
We report three isolated humeri of small-sized parareptiles, which represent two different taxa, from the lower Keuper (Erfurt Formation) of Germany. They constitute the first definitive evidence of parareptiles in the lower Keuper. The specimens represent the first records of an owenettid procolophonian (aff. Barasaurus) from Europe and of a putative gracile-built procolophonid. This indicates the coexistence in the Middle Triassic of Germany of two procolophonian lineages that first appeared in the fossil record in the late Permian and survived the Permian–Triassic extinction. Although based on isolated limb bones, they highlight the taxonomic diversity of the still poorly known tetrapod assemblage of the lower Keuper in southwestern Germany.
Ocean oxidation during the deposition of basal Ediacaran Doushantuo cap carbonates in the Yangtze Platform, South China
Lang et al
Precipitation of cap carbonate lithologies is a key feature of Cryogenian global glaciations. Negative carbonate carbon isotopic compositions (δ13Ccarb) of these cap carbonates have been variably interpreted as massive drawdown of atmospheric CO2 via extensive continental chemical weathering, methane oxidation, or postglacial upwelling. Each of these interpretations argues a non-steady state of carbon cycle in the aftermath of Marinoan global glaciation. To further explore the postglacial marine carbon cycle, we measured δ13Ccarb of cap carbonates from six localities in the Yangtze Platform, South China. The studied cap carbonates were deposited in a variety of sedimentary environments, ranging from the open shelf, slope, to basin facies. Cap carbonates deposited in different environments show distinct stratigraphic trends of δ13Ccarb. In the open shelf, δ13Ccarb profile of the Songlin section remains almost constant (-3 to -4‰), while the δ13Ccarb of the Jiulongwan section records a negative excursion, decreasing from -3.5‰ to -7‰. δ13Ccarb of cap carbonates deposited in the slope environment does not show stable stratigraphic trend. In the basin environment, δ13Ccarb demonstrates a sharp decline in the middle part of cap carbonates to the nadir value of ∼ -11‰. The negative δ13Ccarb excursion is best interpreted in terms of oxidation of dissolved organic carbon (DOC), thus recording a pulse of ocean oxidation during cap carbonate precipitation. Clearly absence of negative δ13Ccarb excursion in all slope and most open shelf sections may imply that such oxidation event was not ubiquitous in the Yangtze Platform. We speculate that the renewed thermohaline circulation during deglaciation brought oxic surface water into ocean interior, which oxidized the basin environment of the Yangtze Platform. However, the deglacial thermohaline circulation was not strong enough to cause complete oxidation of the ocean. The sporadic oxidation in the open shelf, on the other hand, might result from the terrestrial influx of oxidant from postglacial continental weathering. Our study suggests that ocean oxidation, though sporadic, might have occurred during cap carbonate precipitation, and predated the first appearance of putative animal embryos.
Turkish President Recep Tayyip Erdoğan has stressed the significance of the defense industry, saying that Turkey will soon start producing an aircraft carrier after an Anatolian ship, which is a sub type of amphibious vehicle.
Erdoğan's remarks were made in his speech at a launching ceremony of the Istanbul Naval Shipyard.
"There isn't any obstacle to producing our own aircraft carrier. It is possible with this determined government and state," said Erdoğan.
Many of us in India dream of becoming astronauts who reach out for the stars when we are young, despite India not having a human space program. As we grow up, we start to live up to the expectations of our society and make our ends meet by not chasing such wild dreams, but rather by shaping our talent to contribute to other opportunities by taking jobs in the government, private sector, or academia. There are some who achieve their dreams of working in the space sector and join the Indian Space Research Organisation (ISRO) as scientists and engineers.
However, there are some who continue to dream about reaching for the stars, much like they did in their childhood, and take risks to chase those dreams. Over the last few years we are witnessing the emergence of NewSpace in India, with a vision to build world-class enterprises that do business based on developing space assets. Many of these NewSpace companies are built on the inspiration of creating a company like SpaceX in India. This is a moonshot, but one that matches the growing spirit of entrepreneurship in India. However, what makes a SpaceX?
Modeling glacial flow on and onto Pluto's Sputnik Planum
Umurhan et al
Observations of Pluto's surface made by the New Horizons spacecraft indicates present-day nitrogen ice glaciation in and around the basin known as Sputnik Planum. Motivated by these observations, we have developed an evolutionary glacial flow model of solid nitrogen ice taking into account its published thermophysical and rheologies properties. This model assumes that glacial ice layers flow laminarly and have low aspect ratios which permits a vertically integrated mathematical formulation. We assess the conditions for the validity of laminar nitrogen ice motion by revisiting the problem of the onset of solid-state buoyant convection of nitrogen ice for a variety of bottom thermal boundary conditions. Subject to uncertainties in nitrogen ice rheology, nitrogen ice layers are estimated to flow laminarly for thicknesses less than 400-1000 meters. The resulting mass-flux formulation for when the nitrogen ice flows as a laminar dry glacier is characterized by an Arrhenius-Glen functional form. The flow model developed is used here to qualitatively answer some questions motivated by observed glacial flow features found on Sputnik Planum. We find that the wavy transverse dark features found along the northern shoreline of Sputnik Planum may be a transitory imprint of shallow topography just beneath the ice surface suggesting the possibility that a major shoreward flow event happened relatively recently within the last few hundred years. Model results also support the interpretation that the prominent darkened features resembling flow lobes observed along the eastern shoreline of the Sputnik Planum basin may be a result of wet nitrogen glacial ice flowing into the basin from the pitted highlands of eastern Tombaugh Regio.
Venus has an "electric wind" strong enough to remove the components of water from its upper atmosphere, which may have played a significant role in stripping Earth's twin planet of its oceans, according to new results from ESA's (European Space Agency) Venus Express mission by NASA-funded researchers.
"It's amazing, shocking," said Glyn Collinson, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "We never dreamt an electric wind could be so powerful that it can suck oxygen right out of an atmosphere into space. This is something that has to be on the checklist when we go looking for habitable planets around other stars." Collinson is lead author of a paper about this research published June 20, 2016, in the journal Geophysical Research Letters.
The European-built service module for NASA’s Orion crew-transport vehicle will be three months late in being shipped to the United States following modifications to the design recommended by a June 16 program review, a senior European Space Agency official said June 17.
The new shipment date has been tentatively set for late April, rather than late January. ESA, NASA and the two main industrial teams – Airbus Defence and Space for the service module and Lockheed Martin Space Systems, which is prime contractor for Orion — met June 16 at ESA’s Estec facility in Noordwijk, Netherlands, to conclude a service module critical design review.
Nico Dettman, head of ESA’s space transportation department, said the delay is partly a result of the fact that several components could not yet be assessed in the full critical design review and need more time to be integrated into the design.
The area in the outer reaches of the Earth's atmosphere is a swarm of manmade objects, moving at tens of thousands of miles per hour and traversing a region hundreds of thousands of times larger than all of Earth's oceans combined. This complicates the operation of satellites for military use. DARPA has just announced its plans to come to grips with this chaotic region with the launch of a project aimed at revolutionizing the US military's command and control capabilities in space.
The first stage of the project, known as the Hallmark Software Testbed (Hallmark-ST) aims to design cutting-edge software architecture capable of supporting tools and data from a diverse range of sources.
Fire in a Weichselia-dominated coastal ecosystem from the Lower Cretaceous (Barremian) of the Kurnub Group in NW Jordan
Abu Hamad et al
Large intervals of the Cretaceous are considered as a ‘high-fire’ period in Earth's history. However, so far most studies dealing in greater detail with the fossil evidence of palaeo-wildfires, i.e. fossil charcoal, originate from the northern hemisphere (i.e. North America, Europe, Asia) whereas there are large stratigraphic and geographic gaps on the Cretaceous southern continents. The present paper deals with the fossil contents (plant macro-remains, palynomorphs and charcoal) of a lignite lens from the lower part of the Lower Cretaceous Kurnub Group near King Talal Dam in Jordan. The data provide evidence for the repeated occurrence of palaeo-wildfires in coastal ecosystems on the northern margin of Gondwana during the Barremian. The fossil content of the lens indicates that the vegetation, which was repeatedly affected by fire, has been dominated by the matoniaceous tree fern Weichselia reticulata. Palynological data from the lignite, as well as the repeated occurrence of wildfires point to an at least seasonally dry (or at least less humid) climate during deposition of the lignite.
Early mammals evolved in a burst during the Jurassic period, adapting a nocturnal lifestyle when dinosaurs were the dominant daytime predator. How these early mammals evolved night vision to find food and survive has been a mystery, but a new study publishing June 20 in Developmental Cell suggests that rods in the mammalian eye, extremely sensitive to light, developed from color-detecting cone cells during this time to give mammals an edge in low-light conditions.
Cone cells are specialized for certain wavelengths of light to help animals detect color, while rods can detect even a single photon and are specialized for low-light vision. "The majority of mammals have rod-dominant retinas, but if you look at fish, frogs, or birds, the vast majority are cone-dominated--so the evolutionary question has always been, 'What happened?'" says Anand Swaroop, a retina biologist at the National Eye Institute, part of the National Institutes of Health. "We've been working for a long time to understand the fundamental mechanisms behind rod and cone development."
Mercury enrichment and Hg isotopes in Cretaceous–Paleogene boundary successions: Links to volcanism and palaeoenvironmental impacts
Sial et al
We investigate the use of Hg as a proxy for volcanism by studying four distal and two proximal sections in relation to the Deccan volcanic center, straddling the Cretaceous–Paleogene (KPg) boundary at (a) Højerup (Denmark), Bottaccione and Padriciano (Italy), (b) Meghalaya and Jhilmili (India), and (c) Bajada del Jagüel (Argentina). Hg sequestration by organic matter results in constant Hg/TOC ratio and linear correlation between Hg content of the sediments and total organic carbon (TOC).
Elevated Hg concentrations that deviate from this linear relationship represent most likely true Hg anomalies and these notable Hg/TOC spikes (all TOC <1 al="" also="" and="" are="" at="" between="" biozone="" bottaccione="" boundary="" cf2="" clear="" correlation="" foraminiferal="" found="" h="" hg="" i="" ii="" iii="" in="" jerup="" jhilmili="" kpg="" meghalaya="" no="" occurs="" p1a="" planktic="" section.="" sections="" spike="" sub="" subzone="" the="" within="">21>
<1 250="" 750="" a="" aerosols="" agents="" al2o3="" also="" and="" anomalies="" anoxia="" any="" are="" at="" before="" between="" biozone="" bottaccione="" boundary="" br="" carbon="" cf2="" clear="" correlation="" critical="" deccan="" dioxide="" downward="" enrichments="" episodes="" exhaled="" exists="" for="" foraminiferal="" found="" from="" h="" hg="" i="" ii="" iii="" in="" into="" is="" jerup="" jhilmili="" kpg="" kyr="" l="" lasted="" meghalaya="" mo="" no="" not="" occurs="" of="" on="" other="" p1a="" paleoenvironments.="" penetration="" phase-2="" planktic="" possibility="" probably="" proxy.="" ratios="" reached="" record="" redox="" represented="" result="" resulted="" scavenging="" seafloor="" section.="" sections.="" sections="" sediments="" spike="" started="" stratigraphic="" strong="" studied="" subzone="" sulfuric="" supported="" that="" the="" threshold="" toxic="" true="" volcanic="" which="" within=""> Hg isotopes were analyzed in samples from all KPg boundary sections in this study and from Bidart, France, the latter for comparison. Hg isotopes yielded δ202Hg values ranging from −1 to −2‰ and Δ201Hg signatures from 0 to 0.05‰ (spike II in Højerup, Bottaccione and Meghalaya KPg boundary layers) consistent with volcanic emission of Hg (0 to −2‰). The δ202Hg in spike I in Meghalaya and Padriciano and spike III in Jhilmili is consistent with volcanic emission of Hg. Two samples from Bajada del Jagüel and four from Bidart, however, display isotope signals compatible with volcanic emission/chondrite Hg. The results of three other samples are characteristic for reworked sediment, soil and/or peat. Most of the data show small positive Δ201Hg, in favor of long-term atmospheric transport prior to deposition, supporting a volcanic origin for the Hg. The present study broadens, therefore, the potential use of Hg as stratigraphic marker and, moreover, confirms that in the critical KPg transition, Hg was enriched in paleoenvironments at three distinct stages during the Deccan phase-2.1>
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Deeply channelled Precambrian rivers: Remote sensing and outcrop evidence from the 1.2 Ga Stoer Group of NW Scotland
Ielpi et al
The current paradigm on Precambrian fluvial sedimentology assumes that pre-vegetation environments did not allow for the establishment of deep, stable channels. However, few studies have documented a continuum of fluvial-depositional architectures along km-scale transects where clusters of channel bodies can be observed in their entirety. The Stoer Group consists of a 1.2 Ga rift-basin fill, its type area occurring at Stoer Peninsula, NW Scotland. Ground observations on classic coastal sections are integrated with remote sensing on a restored transect 7 km wide, representing 400 m of stratigraphy. The transect spans a set of palaeovalleys carved on high-relief gneissic basement. Remote sensing and ground-based sedimentology unveil a set of depositional domains, including: (i) perennial channels filled with downstream-lateral accretionary bars; (ii) poorly drained muddy floodbasins; (iii) well-drained sandy floodbasins containing splays and distributary channels, at times meandering; (iv) gravelly piedmonts composed of talus cones and fluvial-fan deposits; and (v) aeolian fields comprising dunes, ponded interdunes, and sandsheets. These depositional domains reveal an original geomorphic complexity higher than previously recognized for Precambrian terrestrial environments.
The occurrence of clustered channel bodies alongside or within both muddy and sandy depositional domains indicates that stable fluvial channels developed independently from the cohesive nature of the substrate. Their development was possibly aided by drainage focusing along valley thalwegs. Three types of fluvial channels have been identified: laterally extensive, multistorey channels akin to mobile, weakly sinuous rivers; vertically stacked, multistorey channels reminiscent of confined, weakly sinuous rivers; and laterally extensive, multilateral channels, indicative of highly mobile, moderately sinuous rivers. Eighty-four preserved channel fills display width-to-thickness ratios fully overlapping with those of post-vegetation and modern braided rivers, disproving the commonly held notion that pre-vegetation rivers could only generate sheet-like sandbodies. This study provides new insights on Precambrian fluvial styles, and underscores the potential of remote-sensing methods to analyze very large exposures of fluvial rocks.
Taiwan’s Deputy Defense Minister Pai Hunghui brief[ed] legislators on the Republic of China Navy’s ship building plans for the long-term on Jun. 20. He was questioned by lawmakers in the morning after the local media reported in advance the previous day on what the Navy plans to reveal at a press event later that afternoon.
Two scientists have come up with a depressing new hypothesis that attempts to explain why cancer is so hard to stop.
Maybe, they suggest, cancer's not working against us. Maybe the disease is actually an evolutionary 'final checkpoint' that stops faulty DNA from being passed down to the next generation.
Authors:Lellouch et alAbstract:Observations of the Pluto-Charon system, acquired with the ALMA interferometer on June 12-13, 2015, have yielded a detection of the CO(3-2) and HCN(4-3) rotational transitions from Pluto, providing a strong confirmation of the presence of CO, and the first observation of HCN, in Pluto's atmosphere. The CO and HCN lines probe Pluto's atmosphere up to ~450 km and ~900 km altitude, respectively. The CO detection yields (i) a much improved determination of the CO mole fraction, as 515+/-40 ppm for a 12 ubar surface pressure (ii) clear evidence for a well-marked temperature decrease (i.e., mesosphere) above the 30-50 km stratopause and a best-determined temperature of 70+/-2 K at 300 km, in agreement with recent inferences from New Horizons / Alice solar occultation data. The HCN line shape implies a high abundance of this species in the upper atmosphere, with a mole fraction >1.5x10-5 above 450 km and a value of 4x10-5 near 800 km. The large HCN abundance and the cold upper atmosphere imply supersaturation of HCN to a degree (7-8 orders of magnitude) hitherto unseen in planetary atmospheres, probably due to the slow kinetics of condensation at the low pressure and temperature conditions of Pluto's upper atmosphere. HCN is also present in the bottom ~100 km of the atmosphere, with a 10-8 - 10-7 mole fraction; this implies either HCN saturation or undersaturation there, depending on the precise stratopause temperature. The HCN column is (1.6+/-0.4)x10^14 cm-2, suggesting a surface-referred net production rate of ~2x10^7 cm-2s-1. Although HCN rotational line cooling affects Pluto's atmosphere heat budget, the amounts determined in this study are insufficient to explain the well-marked mesosphere and upper atmosphere's ~70 K temperature. We finally report an upper limit on the HC3N column density (< 2x10^13 cm-2) and on the HC15N / HC14N ratio (< 1/125).
Waterfront on the Martian Planitia: Algorithmic emergent catchments on disordered terrain
Handmer et al
Under a terraforming scenario, a reactivated hydrological cycle on Mars will result in upwards movement of water due to evaporation and precipitation. If Mars' embryonic fossilized catchments provide inadequate drainage, Mars' limited supplies of water may be absorbed entirely by crater lakes and glaciers, with negative consequences for the terraforming effort. We demonstrate a stable, convergent algorithm for the efficient modeling of water flow over disordered terrain. This model is applied to Mars Orbital Laser Altimeter data and successfully predicts the formation of fossilized waterways and canyons visible only at much higher resolution. This exploratory study suggests that despite its impossibly rugged appearance, ancient water flows have carved channels that provide effective drainage over the majority of Mars' surface. We also provide one possible reconstruction of a terraformed surface water distribution.
The Navy on Saturday christened the guided missile destroyer USS Michael Monsoor (DDG-1001), named in honor of a Navy SEAL who was awarded the Medal of Honor for heroism in Iraq.
Monsoor recognizes the service and sacrifice of Petty Officer 2nd Class (SEAL) Michael A. Monsoor, who was killed when he jumped on an enemy hand grenade to save his comrades during combat in Ramadi, Iraq, in 2006.
Sally Monsoor, petty officer Monsoor’s mother, smashed the traditional bottle of sparkling wine across the bow to formally christen the ship during the June 18 ceremony at the General Dynamics Bath Iron Works shipyard in Bath, Maine.
Monsoor is the second ship in the Zumwalt class of futuristic guided missile destroyers, which have a stealth design that gives the 610-foot-long, 15,000-ton warship the radar cross section of a fishing boat. The Zumwalt ships are armed with two 155mm guns to provide long-range, precise fire support for Marines ashore and have an integrated power system that drives the ship and energizes all of its housekeeping and combat systems. Monsoor will be prepared for builder’s trials and then Navy acceptance trials later this year and is expected to be delivered to the Navy in 2017.
Air Force Space Command has created a blueprint for fighting and winning wars in space, known by the innocuous title of the Space Enterprise Vision.
The existence of the plan is not classified but many of its working elements are.
The SEV is “an all-encompassing look at all the things we need to do to create more resilience in our space forces, enhance them, and respond to threats,” Air Force Space Command spokesman Col. John Dorrian says.
It includes current weapon systems and those planned for the near future, as well as changes to training and organization. It isn’t a direct result of the government-wide Space Portfolio Review, according to Dorrian, but it is “related.” A large part of the reason for that distinction, I think, is because the SPR dealt in great detail with US spy satellites, which Space Command does not control.
China on Monday revealed its latest supercomputer, a monolithic system with 10.65 million compute cores built entirely with Chinese microprocessors. This follows a U.S. government decision last year to deny China access to Intel's fastest microprocessors.
There is no U.S.-made system that comes close to the performance of China's new system, the Sunway TaihuLight. Its theoretical peak performance is 124.5 petaflops, according to the latest biannual release today of the world's Top500 supercomputers. It is the first system to exceed 100 petaflops. A petaflop equals one thousand trillion (one quadrillion) sustained floating-point operations per second.
The most important thing about Sunway TaihuLight may be its microprocessors. In the past, China has relied heavily on U.S. microprocessors in building its supercomputing capacity. The world's next fastest system, China's Tianhe-2, which has a peak performance of 54.9 petaflops, uses Intel Xeon processors.
470 million years ago, somewhere in our Solar System, there was an enormous collision between two asteroids. We know this because of the rain of meteorites that struck Earth at that time. But inside that rain of meteorites, which were all of the same type, there is a mystery: an oddball, different from the rest. And that oddball could tell us something about how rocks from space can change ecosystems, and allow species to thrive.
This oddball meteorite has a name: Osterplana 65. It’s a fossilized meteorite, and it was found in a limestone quarry in Sweden. Osterplana 65 fell to Earth some 470 mya, during the Ordovician period, and sank to the bottom of the ocean. There, it became sequestered in a bed of limestone, itself created by the sea-life of the time.
Networks of highly branched stigmarian rootlets developed on the first giant trees
Hetherington et al
Lycophyte trees, up to 50 m in height, were the tallest in the Carboniferous coal swamp forests. The similarity in their shoot and root morphology led to the hypothesis that their rooting (stigmarian) systems were modified leafy shoot systems, distinct from the roots of all other plants. Each consists of a branching main axis covered on all sides by lateral structures in a phyllotactic arrangement; unbranched microphylls developed from shoot axes, and largely unbranched stigmarian rootlets developed from rhizomorphs axes. Here, we reexamined the morphology of extinct stigmarian systems preserved as compression fossils and in coal balls from the Carboniferous period. Contrary to the long-standing view of stigmarian systems, where shoot-like rhizomorph axes developed largely unbranched, root-hairless rootlets, here we report that stigmarian rootlets were highly branched, developed at a density of ∼25,600 terminal rootlets per meter of rhizomorph, and were covered in root hairs. Furthermore, we show that this architecture is conserved among their only extant relatives, herbaceous plants in the Isoetes genus. Therefore, despite the difference in stature and the time that has elapsed, we conclude that both extant and extinct rhizomorphic lycopsids have the same rootlet system architecture.
Over 90 per cent of mammal species were wiped out by the same asteroid that killed the dinosaurs in the Cretaceous period 66 million years ago, significantly more than previously thought.
A study by researchers at the Milner Centre for Evolution at the University of Bath and published in the Journal of Evolutionary Biology, reviewed all mammal species known from the end of the Cretaceous period in North America. Their results showed that over 93 per cent became extinct across the Cretaceous-Paleogene (K-Pg) boundary, but that they also recovered far more quickly than previously thought.
The scientists analysed the published fossil record from western North America from two million years before the Cretaceous-Paleogene boundary, until 300,000 years after the asteroid hit. They compared species diversity before and after this extinction event to estimate the severity of the event and how quickly the mammals recovered. The extinction rates were much higher than previous estimates based on more limited data sets.
Dr Nick Longrich from the Milner Centre for Evolution, in the University of Bath's Department for Biology & Biochemistry, explained: "The species that are most vulnerable to extinction are the rare ones, and because they are rare, their fossils are less likely to be found. The species that tend to survive are more common, so we tend to find them.
Authors:Fairchild et alAbstract:The Late Cryogenian Warm Interval (LCWI) refers to a non-glacial interval that separates presumed representatives of the Sturtian and Marinoan panglaciations. Its duration is poorly constrained radiometrically and its deposits are relatively poorly known in most geographic regions. This paper aims to constrain the duration, palaeoenvironments and petrogenesis of such deposits in the classic region of NE Spitsbergen, Svalbard. The succession comprises a 200–205 m dolomitic shale (Macdonaldryggen Member, known as E3, of the Elbobreen Formation) overlain by oolitic dolomite Slangen Member (E4), 15–25 m thick, with limestone developed at top and base of E3 in the south of the area. The assumed age context of the succession has been confirmed by the presence of a typical Sturtian cap carbonate profile of negative to positive δ13C, and primary Sr isotope compositions of basal E3 limestones <0 .7072="" 0.7076.="" and="" br="" e3="" limestones="" of="" upper=""> 0>
<0 .7072="" 0.7076.="" and="" br="" e3="" limestones="" of="" upper=""> At the base of E3, interstratification of cap carbonate with ice-rafted and redeposited glacial sediments occurs. Early diagenetic stabilization of carbonate mineralogy from a precursor, possibly ikaite, to calcite or dolomite is inferred. E3 is predominantly dolomitic silt-shale, with sub-millimetre lamination, lacking sand or current-related sedimentary structures. Thin fine laminae are partly pyritized and interpreted as microbial mats. Dolomite content is 25–50%, with δ13C values consistently around +4‰, a value attributed to buffering by dissolution of a precursor metastable carbonate phase. Local calcite cement associates with low δ13C values. The carbonates form silt-sized, chemically zoned rhombic crystals from an environment with dynamically changing Fe and Mn. Three-dimensional reconstructions of cm-scale disturbance structures indicate that they represent horizontally directed sock-like folds, developed by release of overpressure into thin surficial sediment overlying an early-cemented layer.
A shoaling upwards unit near the top of E3 displays calcium sulphate pseudomorphs in dolomite in the north, but storm-dominated limestones in the south, both being overlain by peritidal oolitic dolomites, exposed under the succeeding Wilsonbreen glacial deposits. There is no Trezona δ13C anomaly, possibly implying top-truncation of the succession.
Regular 0.5 m-scale sedimentary rhythms, reflecting subtle variations in sediment texture or composition occur throughout E3 and are interpreted as allocyclic. They are thought to be mainly primary in origin, locally modified slightly during early diagenetic cementation. Rhythms are proposed to represent ca. 18 kyr precession cycles, implying 6–8 Myr deposition between glaciations.0>
The Royal Canadian Navy's (RCN's) Canadian Surface Combatant (CSC) requirement is to be streamlined and an existing design chosen instead of a new one, Canada's Minister of Public Services and Procurement, Judy Foote, announced on 13 June.
The CSC project is intended to replace the RCNs Halifax-class frigates and Iroquois-class destroyers, becoming the mainstay of the RCN's surface fleet for the 21st century.
An initial requirement was for a newly-designed vessel, but this has now changed. The Canadian government will instead look to select an existing warship design and then modify it to suit the RCN's needs. There will be up to 15 ships built, but construction will not begin until after Canada's Arctic Offshore Patrol Ships (AOPS) are built.
Watch the fourth flight of the same New Shepard hardware this Sunday. Liftoff is planned for approximately 10:15 am ET and the live webcast starts half an hour earlier at 9:45 am ET at www.blueorigin.com.
On this flight, we’ll intentionally fail one string of parachutes on the capsule. There are three strings of chutes and two of the three should still deploy nominally and, along with our retrothrust system, safely land the capsule. Works on paper, and this test is designed to validate that. We’ll also use this flight to continue pushing the envelope on the booster.
Climate change is by definition a global phenomenon, but there are few locations feeling its immediate impacts like Australia's Great Barrier Reef. Just a month after local scientists were left reeling as warming seas triggered the worst coral bleaching event in its history, researchers are now reporting the reef's only endemic mammal species has become extinct as a result of rising sea levels, describing its demise as the first mammal species to be killed off by human-induced global warming.
Titan's organic aerosols: Molecular composition and structure of laboratory analogues inferred from pyrolysis gas chromatography mass spectrometry analysis
Morrisson et al
Analogues of Titan's aerosols are of primary interest in the understanding of Titan's atmospheric chemistry and climate, and in the development of in situ instrumentation for future space missions. Numerous studies have been carried out to characterize laboratory analogues of Titan aerosols (tholins), but their molecular composition and structure are still poorly known. If pyrolysis gas chromatography mass spectrometry (pyr-GCMS) has been used for years to give clues about their chemical composition, highly disparate results were obtained with this technique. They can be attributed to the variety of analytical conditions used for pyr-GCMS analyses, and/or to differences in the nature of the analogues analyzed, that were produced with different laboratory set-ups under various operating conditions.
In order to have a better description of Titan's tholin's molecular composition by pyr-GCMS, we carried out a systematic study with two major objectives: (i) exploring the pyr-GCMS analytical parameters to find the optimal ones for the detection of a wide range of chemical products allowing a characterization of the tholins composition as comprehensive as possible, and (ii) highlighting the role of the CH4 ratio in the gaseous reactive medium on the tholin's molecular structure. We used a radio-frequency plasma discharge to synthetize tholins with different concentrations of CH4 diluted in N2. The samples were pyrolyzed at temperatures covering the 200–700°C range. The extracted gases were then analyzed by GCMS for their molecular identification.
The optimal pyrolysis temperature for characterizing the molecular composition of our tholins by GCMS analysis is found to be 600°C. This temperature choice results from the best compromise between the number of compounds released, the quality of the signal and the appearance of pyrolysis artifacts. About a hundred molecules are identified as pyrolysates. A common major chromatographic pattern appears clearly for all the samples even if the number of released compounds can significantly differ. The hydrocarbon chain content increases in tholins when the CH4 ratio increases. A semi-quantitative study of the nitriles (most abundant chemical family in our chromatograms) released during the pyrolysis shows the existence of a correlation between the amount of a nitrile released and its molecular mass, similarly to the previous quantification of nitriles in the plasma gas-phase. Moreover, numerous nitriles are present both in tholins and in the gas phase, confirming their suspected role in the gas phase as precursors of the solid organic particles.
A small asteroid has been discovered in an orbit around the sun that keeps it as a constant companion of Earth, and it will remain so for centuries to come.
As it orbits the sun, this new asteroid, designated 2016 HO3, appears to circle around Earth as well. It is too distant to be considered a true satellite of our planet, but it is the best and most stable example to date of a near-Earth companion, or "quasi-satellite."
"Since 2016 HO3 loops around our planet, but never ventures very far away as we both go around the sun, we refer to it as a quasi-satellite of Earth," said Paul Chodas, manager of NASA's Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California. "One other asteroid -- 2003 YN107 -- followed a similar orbital pattern for a while over 10 years ago, but it has since departed our vicinity. This new asteroid is much more locked onto us. Our calculations indicate 2016 HO3 has been a stable quasi-satellite of Earth for almost a century, and it will continue to follow this pattern as Earth's companion for centuries to come."
Sen. Bill Nelson (D-FL) brokered an agreement among Senators who have been at sharp odds over how to transition U.S. rocket launches away from reliance on Russian RD-180 engines to a new American-made engine. The Nelson amendment passed the Senate this morning by voice vote as part of the FY2017 National Defense Authorization Act (NDAA). The NDAA itself then passed the Senate by a vote of 85-13.
In brief, the compromise sets December 31, 2022 as the end date for use of the RD-180 by the United Launch Alliance (ULA) for Atlas V launches of national security satellites. It also limits to 18 the number of RD-180s that can be used between the date that the FY2017 NDAA is signed into law (enacted) and that end date.
The Air Force wants to replace the aging but beloved A-10 “Warthog” with a robotic “flying coke machine” that loiters over the battlefield, dispensing firepower at the touch of a button, the outgoing Chief of Staff said this morning. (More on that concept below). Gen. Mark Welsh also wants a “sixth-generation fighter” that can defeat the most advanced air defenses. But he can’t afford either.
As the service downsizes, both dollars and skilled people are in too short supply, Welsh said. The force has its hands full fielding the new “fifth generation” F-35A Joint Strike Fighter and keeping all its aging fourth-generation (and older) planes in the air.
Origins of food crops connect countries worldwide
Khoury et al
Research into the origins of food plants has led to the recognition that specific geographical regions around the world have been of particular importance to the development of agricultural crops. Yet the relative contributions of these different regions in the context of current food systems have not been quantified. Here we determine the origins (‘primary regions of diversity’) of the crops comprising the food supplies and agricultural production of countries worldwide. We estimate the degree to which countries use crops from regions of diversity other than their own (‘foreign crops’), and quantify changes in this usage over the past 50 years. Countries are highly interconnected with regard to primary regions of diversity of the crops they cultivate and/or consume. Foreign crops are extensively used in food supplies (68.7% of national food supplies as a global mean are derived from foreign crops) and production systems (69.3% of crops grown are foreign). Foreign crop usage has increased significantly over the past 50 years, including in countries with high indigenous crop diversity. The results provide a novel perspective on the ongoing globalization of food systems worldwide, and bolster evidence for the importance of international collaboration on genetic resource conservation and exchange.
Evidence for semi-sessile early juvenile life history in Cretaceous ammonites
Stinnesbeck et al
Here we present evidence for a semi-sessile early juvenile stage of ammonites. Our hypothesis is based on fossil evidence in early diagenetic limestone concretions discovered in platy limestone deposits of Cenomanian age in the northern state of Coahuila, Mexico. In these locations densely packed post-embryonic shell assemblages were attached to fossilized algal or bacterial mats and preserved in sediments deposited under permanently anoxic bottom conditions. Tiny ammonites, as well as gastropods and byssate pectinid bivalves are abundant and restricted to these mats. They do not occur elsewhere in the sediment. The ammonite hatchlings were apparently unable to escape from mats sinking to the hostile sea floor and must thus have been semi-sessile, similar to the associated gastropods and bivalves.