Cthulhu vs cat!
Wednesday, July 31, 2013
Venus Was Catastrophically Resurfaced by Volcanoes
Monte Carlo models of the interaction between impact cratering and volcanic resurfacing on Venus: The effect of the Beta-Atla-Themis anomaly
Authors:
1. I. Romeo (a)
Affiliation:
a. Departamento de Geodinámica, Universidad Complutense de Madrid, C/ José Antonio Novais 12; CP-28040 Madrid, Spain
Abstract:
Detailed Monte Carlo models of the interaction of impact cratering and volcanic resurfacing, which included the Beta-Atla-Themis (BAT) volcanic concentration, were used to test different planetary resurfacing histories. The results were compared with: 1) the randomness of the spatial distribution of craters, 2) the number of modified craters, 3) the number of dark-floored craters due to volcanic flooding, 4) the frequency-area distribution of volcanic units, 5) the frequency-size distribution of craters and modified craters, and (6) the spatial distribution of craters and modified craters with respect to the BAT anomaly. Two catastrophic and two equilibrium resurfacing models were tested. The two catastrophic models consisted of one with a drastic decay and the other with a moderate decay of volcanic activity following the catastrophic event. The two equilibrium models consisted of one with a gradual decay of volcanic activity at the end of the model and the other with a magmatic event followed by a gradual decay of volcanic activity. Both equilibrium models and catastrophic model with moderate decay fail to reproduce the small reduction of the crater density in the BAT area. The model that best fits all the observations is a global catastrophic resurfacing event followed by a drastic decay of volcanic activity. Thus, a Venus global catastrophic resurfacing event erasing all previous craters with little post-resurfacing volcanism is supported by this study.
Hey, Science Fiction Writers: You Can Impress More With Reality
A valid N body simulation solution. Now, your uber advanced race which can do anything can at least do something like this...science has moved on since the 1970s.
wow.
Two 6,000 Year Old Neolithic Barrows Excavated in UK
The remains of two large 6000-year-old halls, each buried within a prehistoric burial mound, have been discovered by archaeologists from The University of Manchester and Herefordshire Council -- in a UK first.
The sensational finds on Dorstone Hill, near Peterchurch in Herefordshire, were thought to be constructed between 4000 and 3600 BC.
Some of the burnt wood discovered at the site shows the character of the building's structure above ground level -- in another UK first.
The buildings, probably used by entire communities, are of unknown size, but may have been of similar length to the Neolithic long barrows beneath which they were found – 70metres and 30m long.
They were, say the team, deliberately burnt down after they were constructed and their remains incorporated into the two burial mounds.
However -- much detail has been preserved in the larger barrow: structural timbers in carbonized form, postholes showing the positions of uprights, and the burnt remains of stakes forming internal partitions.
Most importantly, the core of each mound is composed of intensely burnt clay, representing the daub from the walls of the buildings.
The buildings were likely to have been long structures with aisles, framed by upright posts, and with internal partitions.
The smaller barrow contains a 7m by 2.5m mortuary chamber, with huge sockets which would have held upright tree trunks at each end.
These massive posts bracketed a linear 'trough' lined with planks, which would have held the remains of the dead.
Descent of the Orangutan
Orangutans might be the king of the swingers, but primatologists in Borneo have found that the great apes spend a surprising amount of time walking on the ground. The research, published in the American Journal of Primatology found that it is common for orangutans to come down from the trees to forage or to travel, a discovery which may have implications for conservation efforts.
An expedition led by Brent Loken from Simon Fraser University and Dr. Stephanie Spehar from the University of Wisconsin Oshkosh, travelled to the East Kalimantan region of Borneo. The region's Wehea Forest is a known biodiversity hotspot for primates, including the Bornean orangutan subspecies, Pongo pygmaeus morio, the least studied of orangutan subspecies.
"Orangutans are elusive and one reason why recorded evidence of orangutans on the ground is so rare is that the presence of observers inhibits this behaviour," said Loken. "However, with camera traps we are offered a behind the scenes glimpse at orangutan behaviour."
The team positioned ground-based cameras across a 38-square-kilometre region of the forest and succeeded in capturing the first evidence of orangutans regularly coming down from the trees.
The amount of time orangutans spent on the forest floor was found to be comparable to the ground-dwelling pig-tailed macaque, Macaca nemestrina, which is equally abundant in Wehea Forest. Over 8-months orangutans were photographed 110 times, while the macaques were photographed 113 times.
The reason orangutans come down from the trees remains a mystery. However, while the absence of large predators may make it safer to walk on the forest floor, a more pressing influence is the rapid and unprecedented loss of Borneo's orangutan habitat.
Is Mercury a Signal for Mass Vulcanism Across the KT/K=Pg Boundary?
Mercury as a proxy for volcanic activity during extreme environmental turnover: The Cretaceous-Paleogene transition
Authors:
1. A.N. Sial (a)
2. L.D. Lacerda (b)
3. V.P. Ferreira (a)
4. R. Frei (c)
5. R.A. Marquillas (d)
6. J.A. Barbosa (e)
7. C. Gaucher (f)
8, C.C. Windmöller (g)
9, N.S. Pereira (a)
Affiliations:
a. NEG-LABISE, Department of Geology, Federal University of Pernambuco, Recife, PE, 50740-530, Brazil
b. LABOMAR, Institute of Marine Sciences, Federal University of Ceará, Fortaleza, 60165-081, Brazil
c. Institute of Geography and Geology, University of Copenhagen, Oster Volgade 10, Copenhagen, Denmark, 1350
d. Universidad de Salta, Salta, Argentina CONICET, Buenos Aires 177, 4400 Salta, Argentina
e. LAGESE, Department Geology, Federal University of Pernambuco, Recife, 50740-530, Brazil
f. Facultad de Ciencias, Universidad de La Republica, Montevideo, Uruguay
g. Department of Chemistry, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
Abstract:
The usually low geological background concentrations of Hg makes this trace element suitable for identifying accumulation pulses in sediments that can be tentatively related to weathering processes and thus to climatic changes. Intense volcanism has witnessed the Cretaceous‒Paleogene transition (KTB) and was, perhaps, responsible for dramatic climatic changes and decrease in biodiversity and mass extinction. We have used Hg concentrations as a proxy for volcanic activity and atmospheric Hg and CO2 buildup across the KTB at three localities. In the Salta Basin, Argentina, Hg contents display several spikes across the KTB, with a maximum value of 250 ng.g− 1. In three drill cores across the KTB in the Paraíba Basin, northeastern Brazil, Hg contents increase from the late Maastrichtian to early Danian and Hg spikes predate the KTB, perhaps, as a record of volcanic activity before (but very close to) this transition. At Stevns Klint, Denmark, Hg contents reached almost 250 ng.g− 1 within a 5 cm thick-clay layer, the Fiskeler Member (‘Fish Clay’) that comprises the KTB. Some co-variation between Hg and Al2O3 contents has been observed in all of the studied sections across the KTB, suggesting that Hg is probably adsorbed onto clays. Thermo-desorption experiments in selected samples from the Yacoraite Formation showed Hg+ 2 as the major species present, which is in agreement with a volcanic origin. Combined Hg and C-isotope chemostratigraphy may become a powerful tool for the eventual assessment of the role of volcanic activity during extreme climatic and biotic events, such as those during the KTB.
Carbon Dioxide Depleted in Late Archean Sea Water
Decrease of seawater CO2 concentration in the Late Archean: An implication from 2.6 Ga seafloor hydrothermal alteration
Authors:
1. Takazo Shibuya (a, b, c)
2. Miyuki Tahata (d)
3. Yuichiro Ueno (d)
4. Tsuyoshi Komiya (e)
5. Ken Takai (a, b, f)
6. Naohiro Yoshida (g, h)
7. Shigenori Maruyama (e)
8. Michael J. Russell (c)
Affiliations:
a. Precambrian Ecosystem Laboratory (PEL), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
b. Submarine Hydrothermal System Research Group, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
c. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
d. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
e. Department of Earth Science and Astronomy, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
f. Subsurface Geobiology Advanced Research (SUGAR) project, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan
g. Department of Environmental Science and Technology, Tokyo Institute of Technology, G1-25, 4259 Nagatsuta, Yokohama, 226-8502, Japan
h. Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, G1-25, 4259 Nagatsuta, Yokohama, 226-8502, Japan
Abstract:
Before continents attained a critical aerial dimension on the early Earth, hydrothermal carbonation of subseafloor crust is considered to have played the dominant role in fixing CO2 from the CO2-rich ocean. However, it is uncertain how and when the seawater CO2 level decreased and the strong carbonation of oceanic crust ceased. Here we report the depth profiles of the volume concentration and the carbon isotopes of calcites in the Late Archean/Paleoproterozoic volcanic rocks (Fortescue and Hamersley groups), exposed in the southwestern Pilbara Craton, Western Australia. The depth profiles indicate that 2.6 Ga seafloor hydrothermal carbonation is well preserved in the study area and that the CO2 content of subseafloor crust per seafloor unit area is estimated to be clearly lower than those in the Early and Middle Archean and similar to the Phanerozoic equivalents. This suggests that the CO2 concentration in seawater decreased from the Middle Archean to the Late Archean. This period broadly corresponds to the time of the first appearance of supercontinent on Earth. The amalgamation of continents has the potential to decrease seawater CO2 concentration due to the removal of platform carbonate to continental interior. Subsequent fragmentation of supercontinent likely cause the carbonate deposition around newly created continental shelves. It is therefore implied that seawater CO2 concentration in the early Earth was lowered by not only the hydrothermal carbonation of subseafloor crust but also through the formation and breakup of supercontinent in the Late Archean.
Tuesday, July 30, 2013
New Horizons Plan for the Pluto Encounter
Scientists on the New Horizons mission are beginning to plan in earnest how they will evaluate the data that will begin flowing back from Pluto in less than two years, when the nuclear-powered probe begins sending “better than Hubble” imagery of the distant body and its satellites.
The spacecraft's Long-Range Reconnaissance Imager (Lorri) has already resolved Pluto and Charron, its largest satellite, into two distinct objects (see image, page 22). With the resolution improving by the day, the mission team has planned and uploaded its flyby choreography, and has sent out a call to astronomers for parallel observation from Earth and its environs before, during and after the July 14, 2015, encounter.
The team also has completed a rehearsal with the spacecraft, and conducted a detailed scientific workshop at the Johns Hopkins University's Applied Physics Laboratory (APL) here, where New Horizons was built. There are no plans to retarget the probe again.
HD 189733b: Blue Exoplanet with Silicon Rain Seen in the X Ray Spectrum, a First
This is not a new detection of an exoplanet – this same exoplanet, named HD 189733b has been one of the most-observed planets orbiting another star, and was recently in the news for Hubble confirming the planet’s ocean-blue atmosphere and the likelihood of having glass raining down on the planet.
But being able to see the exoplanet in X-rays is good news for future studies and perhaps even detections of planets around other stars.
“Thousands of planet candidates have been seen to transit in only optical light,” said Katja Poppenhaeger of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study, which will be published in the Aug. 10 edition of The Astrophysical Journal. “Finally being able to study one in X-rays is important because it reveals new information about the properties of an exoplanet.”
Run Away Green House State Might be Easier to Achieve Than Previously Thought
Low simulated radiation limit for runaway greenhouse climates
Authors:
1. Colin Goldblatt (a)
2. Tyler D. Robinson (b)
3. Kevin J. Zahnle (c)
4. David Crisp (d)
Affiliations:
a. School of Earth and Ocean Sciences, University of Victoria, PO Box 3065, Victoria, British Columbia, V8W 3V6, Canada
b. Astronomy Department, University of Washington, Box 351580, Seattle, Washington 98195-1580, USA
c. Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-3, Moffett Field, California 94035, USA
d. Jet Propulsion Laboratory, MS 183-501, 4800 Oak Grove Drive, Pasadena, California 91109, USA
Abstract:
The atmospheres of terrestrial planets are expected to be in long-term radiation balance: an increase in the absorption of solar radiation warms the surface and troposphere, which leads to a matching increase in the emission of thermal radiation. Warming a wet planet such as Earth would make the atmosphere moist and optically thick such that only thermal radiation emitted from the upper troposphere can escape to space. Hence, for a hot moist atmosphere, there is an upper limit on the thermal emission that is unrelated to surface temperature. If the solar radiation absorbed exceeds this limit, the planet will heat uncontrollably and the entire ocean will evaporate—the so-called runaway greenhouse. Here we model the solar and thermal radiative transfer in incipient and complete runaway greenhouse atmospheres at line-by-line spectral resolution using a modern spectral database. We find a thermal radiation limit of 282 W m−2 (lower than previously reported) and that 294 W m−2 of solar radiation is absorbed (higher than previously reported). Therefore, a steam atmosphere induced by such a runaway greenhouse may be a stable state for a planet receiving a similar amount of solar radiation as Earth today. Avoiding a runaway greenhouse on Earth requires that the atmosphere is subsaturated with water, and that the albedo effect of clouds exceeds their greenhouse effect. A runaway greenhouse could in theory be triggered by increased greenhouse forcing, but anthropogenic emissions are probably insufficient.
Halticosaurus orbitoangulatus Was Not a Dinosaur
Reassessment of cf. Halticosaurus orbitoangulatus from the Upper Triassic (Norian) of Germany – a pseudosuchian, not a dinosaur
Authors:
1. HANS-DIETER SUES FLS (a)
2. RAINER R. SCHOCH (b)
Affiliations:
a. Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, MRC 121, P.O. Box 37012, Washington, DC 20013-7012, USA
b. Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191 Stuttgart, Germany
Abstract:
The holotype of cf. Halticosaurus orbitoangulatus Huene, 1932, comprises an incomplete and macerated but associated skull of an archosaurian reptile from the middle (second) Stubensandstein (middle Löwenstein Formation; Upper Triassic: Norian) of Baden-Württemberg, Germany. It was originally interpreted as a theropod dinosaur but more recently it has been suggested that this taxon has crocodylomorph affinities. Detailed preparation of the holotype of cf. H. orbitoangulatus has revealed much new anatomical information and permitted reassessment of its affinities. The maxilla lacks both a distinct antorbital fossa and a medial bony lamina bordering the antorbital fenestra. The lateral surface of the dentary bears a pronounced horizontal ridge. The squamosal differs from that of basal crocodylomorphs in being L-shaped rather than arcuate in dorsal view, lacking a dorsolateral overhang, and lacking an interlocking contact with the paroccipital process as, for example, in the basal crocodylomorph Saltoposuchus connectens from the same horizon and locality. Phylogenetic analysis placed cf. H. orbitoangulatus amongst loricatan pseudosuchians (but not amongst Crocodylomorpha) rather than amongst theropod dinosaurs. The holotype of cf. H. orbitoangulatus represents a previously unrecognized taxon of loricatan pseudosuchian, which is here named Apatosuchus orbitoangulatus and set apart from other known Norian-age non-crocodylomorph loricatans by its apparently much smaller size. © 2013 The Linnean Society of London
More Evidence of the Devonian Shift From Hot House to Ice House Global COnditions
Sequence stratigraphic hierarchy of the Upper Devonian Foreknobs Formation, central Appalachian Basin, USA: Evidence for transitional greenhouse to icehouse conditions
Authors:
1. Wilson S. McClung (a)
2. Kenneth A. Eriksson (b)
3. Dennis O. Terry Jr. (c)
4. Clifford A. Cuffey (a)
Affiliations:
a. Chevron USA Inc, 15 Smith Rd, Midland, TX 79705
b. Department of Geosciences, Virginia Tech, Blacksburg, VA 24061
c. Department of Earth and Environmental Science, Temple University, Philadelphia, PA 19122
Abstract:
The Foreknobs Formation (Upper Devonian; Upper Frasnian to basal Famennian) comprises the uppermost marine strata of the progradational “Catskill clastic wedge” of the south-central Appalachian Mountains (Virginia-West Virginia; USA). The Foreknobs Formation consists of 14 lithofacies arranged in four facies associations which record the following depositional settings: 1) storm-dominated distal to proximal offshore to shoreface (facies association A); 2) sharp-based conglomeratic shoreface (facies association B); 3) fluvial redbed (facies association C); and 4) incised-valley fill (IVF; facies association D). Vertical juxtaposition and stacking patterns of lithofacies and facies associations permits recognition of a hierarchy of three scales of cyclicity. Up to 70 short-term 5th-order cycles, each averaging ~ 65 Kyr, consist of coarsening-upward parasequences of storm-dominated offshore marine facies in the distal setting which correspond to high frequency (unconformity bound) sequences (HFS) of fluvial redbed strata overlain by offshore marine strata in the proximal setting. These facies relationships are a consequence of 10 – 15 m of sea-level fluctuations. Up to 12 intermediate-term 4th-order cycles, each averaging ~ 375 Kyr, consist of stacked 5th-order cycles. The 4th-order cycles are bounded by regressive surfaces of marine erosion (RSME) at the base of sharp-based conglomeratic shoreface sandstones in the distal setting that correspond with paleosols in the proximal setting. In some cases, the 5th-order cycles within each 4th-order cycle exhibit stacking patterns indicative of increasing or decreasing accomodation space. These facies relationships are a consequence of 25 – 35 m of sea-level fluctuations. Three complete and portions of two additional 3rd-order cycles, each averaging ~ 1.12 Myr, consist of stacked 4th-order cycles. The 3rd-order sea-level trends reflected in the Foreknobs Formation are nearly identical to published eustatic sea-level curves. Incised-valley fills are present at one of the 3rd-order cycle boundaries and are a consequence of a 35 – 45 m sea-level fluctuation. The amplitudes of the inferred sea-level fluctuations are comparable to the expansion and contraction of ice volumes within the current Greenland and Antarctic ice sheets which suggests glacioeustasy was the primary control on sea-level fluctuations and cyclicity within the Foreknobs Formation. Such an interpretation is consistent with knowledge of Devonian climate, transitioning from Middle Devonian greenhouse to Late Devonian icehouse, as indicated by evidence of glaciation during parts of the Late Devonian in South America and the Appalachians.
Monday, July 29, 2013
First Planet Found Around Brown Dwarf
Astrophysical calculations show that any star that is smaller than about 1/10th of the mass of the sun cannot sustain hydrogen fusion reactions at its core. These failed stars never light up. Instead they wander the galaxy as warm, dark balls of hydrogen known as brown dwarfs.
Brown dwarfs probably form through the same process that lead to ordinary stars but merely on a smaller scale. If that’s correct, planets should also form in the protoplanetary disks of gas and dust around brown dwarfs. Indeed, astronomers have seen a number of protoplanetary disks of this type.
Until now, however, they’ve never seen a planet orbiting a brown dwarf. That’s not really surprising.
The standard methods for detecting planets look for the way a star wobbles as a planet orbits or at how its magnitude changes as a planet passes in front. But given that brown dwarfs are dim and difficult to see, these methods have yet to produce fruit.
All that changes today with the announcement by an international team of astronomers that they’ve discovered a planet orbiting a brown dwarf the first time. These guys have made their discovery using an entirely different method of detection called gravitational lensing. This occurs when one body passes in front of another and its gravity focuses light from the more distant object towards Earth. That works regardless of the brightnesses involved.
The brown dwarf in question is almost 6000 light years from Earth in the Fish Hook constellation. Astronomers first noticed an unusual change in its brightness in April 2012. Further investigation showed that this was indeed a lensing event.
These guys conclude that the brown dwarf is being orbited by a planet about twice the mass of Jupiter at a distance of just under one astronomical unit. The brown dwarf itself is about 10 times larger than its companion.
Terrestrial Planets, Migrating Jovians and Mars
TERRESTRIAL PLANET FORMATION DURING THE MIGRATION AND RESONANCE CROSSINGS OF THE GIANT PLANETS
Authors:
1. Patryk Sofia Lykawka (a)
2. Takashi Ito (b)
Affiliations:
a. Astronomy Group, Faculty of Social and Natural Sciences, Kinki University, Shinkamikosaka 228-3, Higashiosaka-shi, Osaka 577-0813, Japan
b. National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
Abstract:
The newly formed giant planets may have migrated and crossed a number of mutual mean motion resonances (MMRs) when smaller objects (embryos) were accreting to form the terrestrial planets in the planetesimal disk. We investigated the effects of the planetesimal-driven migration of Jupiter and Saturn, and the influence of their mutual 1:2 MMR crossing on terrestrial planet formation for the first time, by performing N-body simulations. These simulations considered distinct timescales of MMR crossing and planet migration. In total, 68 high-resolution simulation runs using 2000 disk planetesimals were performed, which was a significant improvement on previously published results. Even when the effects of the 1:2 MMR crossing and planet migration were included in the system, Venus and Earth analogs (considering both orbits and masses) successfully formed in several runs. In addition, we found that the orbits of planetesimals beyond a ~ 1.5-2 AU were dynamically depleted by the strengthened sweeping secular resonances associated with Jupiter's and Saturn's more eccentric orbits (relative to the present day) during planet migration. However, this depletion did not prevent the formation of massive Mars analogs (planets with more than 1.5 times Mars's mass). Although late MMR crossings (at t less than 30 Myr) could remove such planets, Mars-like small mass planets survived on overly excited orbits (high e and/or i), or were completely lost in these systems. We conclude that the orbital migration and crossing of the mutual 1:2 MMR of Jupiter and Saturn are unlikely to provide suitable orbital conditions for the formation of solar system terrestrial planets. This suggests that to explain Mars's small mass and the absence of other planets between Mars and Jupiter, the outer asteroid belt must have suffered a severe depletion due to interactions with Jupiter/Saturn, or by an alternative mechanism (e.g., rogue super-Earths).
KAI Proposes Grippen Sized Fighter For K-X-E Stealth Fighter
Korea Aerospace Industries (KAI) has published a drawing of a moderately stealthy fighter concept based on its T-50 series of supersonic trainers and light-attack aircraft. The concept aircraft is far smaller and less ambitious than the all-new, twin-engine KF-X designs promoted by the Agency for Defense Development, the leading proponent of building an indigenous South Korea fighter.
Some South Korean industry officials doubt that the country has the technical resources to build the KF-X, especially if major civil aerospace programs go ahead at the same time; a 90-seat turboprop airliner is also proposed. But a KF-X derived from a current type would demand less engineering and may benefit from stronger pricing by avoiding competition with the Lockheed Martin F-35, although Saab is already in the market for advanced but moderately sized fighters with its Gripen E/F.
The T-50 and its FA-50 light fighter derivative are themselves based on the F-16 and were developed with help from Lockheed Martin, but the stealthy concept, called KF-X-E, departs from the F-16 planform used for the earlier aircraft. Some wing and fuselage edges are parallel, and the trailing edges of the main and tail planes are swept forward. The fuselage sides have chines. Nose volume of the KF-X-E appears to be small, limiting the size of the radar antenna, but the airframe seems to have more volume overall than the T-50, offering more space for internal fuel and thereby minimizing the need for external tanks and their radar reflections.
Retention of the single tail on the KF-X-E is emblematic of the limited ambition of the designers, who appear to have aimed at achieving a level of stealth above that of the Eurofighter Typhoon and Boeing F/A-18E/F Super Hornet but well below that of the Lockheed Martin F-22 and F-35. The latter two, like other stealth aircraft, have canted twin tail fins.
Similarly, the air inlets of the KF-X-E have boundary-layer diverters; recent stealth aircraft handle the boundary layer with aerodynamic shaping and no diverters. The KF-X-E may be too small for internal weapons stowage. No engine details are known, but South Korea may want to replace the T-50's General Electric F404, whose future application appears limited to the T-50 series, with another probably more powerful type. Candidates would include the GE F414 and Eurojet EJ200.
Did Humans Cause the Madagascar Extinctions? Or Not?
Stone tools and foraging in northern Madagascar challenge Holocene extinction models
Authors:
1. Robert E. Dewar (a)
2. Chantal Radimilahy (b)
3. Henry T. Wright (c,d)
4. Zenobia Jacobs (e)
5. Gwendolyn O. Kelly (f)
6. Francesco Berna (g)
Affiliations:
a. Department of Anthropology, Yale University, New Haven, CT 06520-8277;
b. Institute des Civilisations–Musée d’Art et d’Archéologie, L’Université d’Antananarivo, BP 564, Isoraka, Antananarivo, Madagascar;
c. Museum of Anthropology, University of Michigan, Ann Arbor, MI 48109-1079;
d. The Santa Fe Institute, Santa Fe, NM 87501;
e. Centre for Archaeological Science, University of Wollongong, Wollongong, NSW, Australia 2522;
f. Department of Anthropology, University of Wisconsin, Madison, WI 53706; and
g. Department of Archaeology, Simon Fraser University, Burnaby, BC, Canada V5A 1S6
Abstract:
Past research on Madagascar indicates that village communities were established about AD 500 by people of both Indonesian and East African heritage. Evidence of earlier visits is scattered and contentious. Recent archaeological excavations in northern Madagascar provide evidence of occupational sites with microlithic stone technologies related to foraging for forest and coastal resources. A forager occupation of one site dates to earlier than 2000 B.C., doubling the length of Madagascar’s known occupational history, and thus the time during which people exploited Madagascar’s environments. We detail stratigraphy, chronology, and artifacts from two rock shelters. Ambohiposa near Iharana (Vohémar) on the northeast coast, yielded a stratified assemblage with small flakes, microblades, and retouched crescentic and trapezoidal tools, probably projectile elements, made on cherts and obsidian, some brought more that 200 km. 14C dates are contemporary with the earliest villages. No food remains are preserved. Lakaton’i Anja near Antsiranana in the north yielded several stratified assemblages. The latest assemblage is well dated to A.D. 1050–1350, by 14C and optically stimulated luminescence dating and pottery imported from the Near East and China. Below is a series of stratified assemblages similar to Ambohiposa. 14C and optically stimulated luminescence dates indicate occupation from at least 2000 B.C. Faunal remains indicate a foraging pattern. Our evidence shows that foragers with a microlithic technology were active in Madagascar long before the arrival of farmers and herders and before many Late Holocene faunal extinctions. The differing effects of historically distinct economies must be identified and understood to reconstruct Holocene histories of human environmental impact.
I would think I would have heard this all over the place. Its a bit odd that I have not. Its a pretty important: when was Madagascar settled? If it was settled as the conventional wisdom states, then people are the direct driver of the extinctions. We show up and BOOM. If it was settled earlier, it was the later farmer culture which caused the extinctions.
Since no food traces have been found, that leave sa lot of questions. Since no skeletal remains or burials sites have been found, I have to wonder...is there any history of forest folk or trolls or such Madagascar? It would be amusing if there was another hominin...one which made it into historic times. Yes, that counts as a crazy thought. However, I need to fix issues with Crazy Thought 4.
Sunday, July 28, 2013
More Info on the Mars 2020 Rover
NASA’s planned Mars 2020 rover likely will both continue the astrobiological exploration of Mars begun by the Curiosity rover and provide stepping stones to the next stages of Martian exploration.
Two weeks ago, NASA’s Mars 2020 rover Science Definition Team (SDT) delivered its report recommending the science goals for the mission. Probably to the surprise of no one, the team recommended essentially the same science goals as had several previous SDT’s on what NASA’s next mission to Mars should do. Like the Curiosity rover currently on Mars and the planned European and Russian ExoMars rover mission, the 2020 rover will look for clues as to whether Mars ever contained the conditions to enable life and whether traces of life or pre-biotic chemistry remain.
The mission will also provide an important transition to the next phases of Mars exploration by caching samples that could eventually be returned to Earth and testing technologies for future human and robotic missions.
Saturday, July 27, 2013
Friday, July 26, 2013
Thor's Hero Shrew
A new hero emerges: another exceptional mammalian spine and its potential adaptive significance
Authors:
1. William T. Stanley (a)
2. Lynn W. Robbins (b)
3. Jean M. Malekani (c)
4. Sylvestre Gambalemoke Mbalitini (d)
5. Dudu Akaibe Migurimu (d)
6. Jean Claude Mukinzi (d)
7. Jan Hulselmans (e)
8. Vanya Prévot (f)
9. Erik Verheyen (e,f)
10. Rainer Hutterer (g)
11. Jeffrey B. Doty (h)
12. Benjamin P. Monroe (h)
13. Yoshinori J. Nakazawa (h)
14. Zachary Braden (h)
15. Darin Carroll (h)
16. Julian C. Kerbis Peterhans (a,i)
17. John M. Bates (a)
18. Jacob A. Esselstyn (j)
Affiliations:
a. Science and Education, Field Museum of Natural History, Chicago, IL, USA
b. Department of Biology, Missouri State University, Springfield, MO, USA
c. Department of Biology, University of Kinshasa, Kinshasa, Democratic Republic of Congo
d. Laboratory of Ecology and Animal Resource Management, University of Kisangani, Kisangani, Democratic Republic of Congo
e. Department of Biology, University of Antwerp, Antwerpen, Belgium
f. Vertebrate Department, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
g. Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany
h. Centers for Disease Control and Prevention, Atlanta, GA, USA
i. College of Professional Studies, Roosevelt University, Chicago, IL, USA
j. 0Department of Biological Sciences and Museum of Natural Science, Louisiana State University, Baton Rouge, LA, USA
Abstract:
The hero shrew's (Scutisorex somereni) massive interlocking lumbar vertebrae represent the most extreme modification of the vertebral column known in mammals. No intermediate form of this remarkable morphology is known, nor is there any convincing theory to explain its functional significance. We document a new species in the heretofore monotypic genus Scutisorex; the new species possesses cranial and vertebral features representing intermediate character states between S. somereni and other shrews. Phylogenetic analyses of DNA sequences support a sister relationship between the new species and S. somereni. While the function of the unusual spine in Scutisorex is unknown, it gives these small animals incredible vertebral strength. Based on field observations, we hypothesize that the unique vertebral column is an adaptation allowing these shrews to lever heavy or compressive objects to access concentrated food resources inaccessible to other animals.
Awesome pop sci write up over at Running Ponies, but without the snarkiness of old.
Brown Dwarfs Are Not Good Candidates for Habitable Worlds
Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary
Authors:
1. Rory Barnes (a,b)
2. René Heller (c)
Affiliations:
a. Astronomy Department, University of Washington, Seattle, Washington, USA.
b. NASA Astrobiology Institute–Virtual Planetary Laboratory Lead Team.
c. Leibniz Institute for Astrophysics Potsdam (AIP), Potsdam, Germany.
Abstract:
White and brown dwarfs are astrophysical objects that are bright enough to support an insolation habitable zone (IHZ). Unlike hydrogen-burning stars, they cool and become less luminous with time; hence their IHZ moves in with time. The inner edge of the IHZ is defined as the orbital radius at which a planet may enter a moist or runaway greenhouse, phenomena that can remove a planet's surface water forever. Thus, as the IHZ moves in, planets that enter it may no longer have any water and are still uninhabitable. Additionally, the close proximity of the IHZ to the primary leads to concern that tidal heating may also be strong enough to trigger a runaway greenhouse, even for orbital eccentricities as small as 10−6. Water loss occurs due to photolyzation by UV photons in the planetary stratosphere, followed by hydrogen escape. Young white dwarfs emit a large amount of these photons, as their surface temperatures are over 104 K. The situation is less clear for brown dwarfs, as observational data do not constrain their early activity and UV emission very well. Nonetheless, both types of planets are at risk of never achieving habitable conditions, but planets orbiting white dwarfs may be less likely to sustain life than those orbiting brown dwarfs. We consider the future habitability of the planet candidates KOI 55.01 and 55.02 in these terms and find they are unlikely to become habitable.
Proposed Spectra of Habitable Worlds Around KGF Class Stars
Spectral Fingerprints of Earth-like Planets Around FGK Stars
Authors:
1. Sarah Rugheimer (a)
2. Lisa Kaltenegger (a,b)
3. Andras Zsom (b,c)
4. Antígona Segura (d)
5. Dimitar Sasselov (a)
Affiliations:
a. Harvard Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA.
b. MPIA, Heidelberg, Germany.
c. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
d. Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México, D.F., México.
Abstract:
We present model atmospheres for an Earth-like planet orbiting the entire grid of main sequence FGK stars with effective temperatures ranging from Teff=4250 K to Teff=7000 K in 250 K intervals. We have modeled the remotely detectable spectra of Earth-like planets for clear and cloudy atmospheres at the 1 AU equivalent distance from the VIS to IR (0.4 to 20 μm) to compare detectability of features in different wavelength ranges in accordance with the James Webb Space Telescope and future design concepts to characterize exo-Earths. We have also explored the effect of the stellar UV levels as well as spectral energy distribution on a terrestrial atmosphere, concentrating on detectable atmospheric features that indicate habitability on Earth, namely, H2O, O3, CH4, N2O, and CH3Cl.
The increase in UV dominates changes of O3, OH, CH4, N2O, and CH3Cl, whereas the increase in stellar temperature dominates changes in H2O. The overall effect as stellar effective temperatures and corresponding UV increase is a lower surface temperature of the planet due to a bigger part of the stellar flux being reflected at short wavelengths, as well as increased photolysis. Earth-like atmosphere models show more O3 and OH but less stratospheric CH4, N2O, CH3Cl, and tropospheric H2O (but more stratospheric H2O) with increasing effective temperature of main sequence stars. The corresponding detectable spectral features, on the other hand, show different detectability depending on the wavelength observed.
We concentrate on directly imaged planets here as a framework to interpret future light curves, direct imaging, and secondary eclipse measurements of atmospheres of terrestrial planets in the habitable zone at varying orbital positions.
Oreopithecus Was Not an Obligate Biped
For decades, the movement of an ancient ape species called Oreopithecus bambolii has been a matter of debate for scientists. Did it walk like a human across its swampy Mediterranean island or did it move through the trees like other apes?
According to a new study, led by University of Texas at Austin anthropologists Gabrielle A. Russo and Liza Shapiro, the 9- to 7-million-year-old ape from Italy did not, in fact, walk habitually on two legs.
The findings refute a long body of evidence, suggesting that Oreopithecus had the capabilities for bipedal (moving on two legs) walking.
The study, published in a forthcoming issue of the Journal of Human Evolution, confirms that anatomical features related to habitual upright, two-legged walking remain exclusively associated with humans and their fossil ancestors.
"Our findings offer new insight into the Oreopithecus locomotor debate," says Russo, who is currently a postdoctoral research fellow at Northeast Ohio Medical University. "While it's certainly possible that Oreopithecus walked on two legs to some extent, as apes are known to employ short bouts of this activity, an increasing amount of anatomical evidence clearly demonstrates that it didn't do so habitually."
As part of the study, the researchers analyzed the fossil ape to see whether it possessed lower spine anatomy consistent with bipedal walking. They compared measurements of its lumbar vertebrae (lower back) and sacrum (a triangular bone at the base of the spine) to those of modern humans, fossil hominins (extinct bipedal human ancestors), and a sample of mammals that commonly move around in trees, including apes, sloths and an extinct lemur.
The lower spine serves as a good basis for testing the habitual bipedal locomotion hypothesis because human lumbar vertebrae and sacra exhibit distinct features that facilitate the transmission of body weight for habitual bipedalism, says Russo.
According to the findings, the anatomy of Oreopithecus lumbar vertebrae and sacrum is unlike that of humans, and more similar to apes, indicating that it is incompatible with the functional demands of walking upright as a human does.
"The lower spine of humans is highly specialized for habitual bipedalism, and is therefore a key region for assessing whether this uniquely human form of locomotion was present in Oreopithecus," says Shapiro, a professor of anthropology. "Previous debate on the locomotor behavior of Oreopithecus had focused on the anatomy of the limbs and pelvis, but no one had reassessed the controversial claim that its lower back was human-like."
Anisian Triassic Diapsid Megachirella wachtleri Redescribed
Redescription and phylogenetic relationships of Megachirella wachtleri Renesto et Posenato, 2003 (Reptilia, Diapsida)
Authors:
1. Silvio Renesto (a)
2. Massimo Bernardi (b,c)
Affiliations:
a. DISTA Dipartimento di Scienze Teoriche ed Applicate, Universita` degli Studi dell’Insubria, Via Dunant 3, 21100 Varese, Italy
b. Museo delle Scienze, Via Calepina 14, 38100 Trento, Italy
c. School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
Abstract:
Megachirella wachtleri Renesto et Posenato, 2003, a well preserved partial reptile skeleton from the Middle Triassic of the Dolomites (N. Italy), was originally considered a lepidosauromorph, but no phylogenetic analysis was carried out. Consequently, the taxon was overlooked in later phylogenetic analyses of the Diapsida. Here, the holotype and only known specimen of M. wachtleri is redescribed, allowing an investigation of its phylogenetic relationships. Phylogenetic analyses confirm that Megachirella is a lepidosauromorph close to the crown group lepidosaurs (Squamata + Rhynchocephalia). Megachirella enhances our knowledge of the series of morphological modifications that led to the origin of the Lepidosauria, the most diverse clade of extant reptiles.
Thursday, July 25, 2013
Marsupial Origins in Australia Gets More Complicated
Two tiny fossils are prompting an overhaul of theories about marsupial evolution after they revealed unexpected links to South America – and possibly Africa.
One of the fossils, found at the Tingamarra site in south-eastern Queensland, is a 55 million-year-old ankle bone from a mouse-sized marsupial previously known only from South America. The second is a tooth, which derives from a formerly unknown species that shows similarities to fossils found in South America and, surprisingly, North Africa.
The two fragments are set to overturn the conventional theory about the evolution of marsupials, which holds that there was a single migration from the part of the Gondwana 'supercontinent' that became South America to the part that became Australia.
"The origins of Australian marsupials suddenly got a lot more complicated!" said palaeontologist Dr Robin Beck, an ARC DECRA postdoctoral fellow at the University of NSW.
"All the species of modern day marsupials here are quite closely related. The species represented by the ankle-bone belongs to an entirely different group – a group that we know lived in South America but, up until now, we thought never made it to Australia. The tooth is more of a mystery: are its origins in South America, Africa or somewhere else?
"It is impossible to explain the presence of these new fossils in Australia using the single dispersal model. Instead, there may have been multiple movements of marsupials between South America and Australia."
Keep in mind, metatherians were close to, if not truly, dominant in North America prior to the KT Extinction. It was that extinction which set placentals, eutherians really, on their rise to dominance. Otherwise, they would not have.
Limits to Habitability of Exoplanets From Tidal Heating
Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating
Authors:
1. Rory Barnes (a,b)
2. Kristina Mullins (a,b)
3. Colin Goldblatt (a,b,c)
4. Victoria S. Meadows (a,b)
5. James F. Kasting (b,d)
6. René Heller (e)
Affiliations:
a. Astronomy Department, University of Washington, Seattle, Washington, USA
b. NASA Astrobiology Institute–Virtual Planetary Laboratory Lead Team, USA
c. Department of Earth and Ocean Science, University of Victoria, Victoria, Canada
d. Department of Geosciences, The Pennsylvania State University, State College, Pennsylvania, USA.
e. Leibniz Institute for Astrophysics Potsdam (AIP), Potsdam, Germany
Abstract:
Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high-enough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets “Tidal Venuses” and the phenomenon a “tidal greenhouse.” Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with masses less than 0.3 MSun may be in danger of desiccation via tidal heating. We have applied these concepts to Gl 667C c, a 4.5 MEarth planet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.
Two Papers on Habitable ExoMoons
Capture of Terrestrial-Sized Moons by Gas Giant Planets
Author:
1. Darren M. Williams (a)
Affiliation:
a. Penn State Erie, The Behrend College, School of Science, Erie, Pennsylvania
Abstract:
Terrestrial moons with masses greater than 0.1 M possibly exist around extrasolar giant planets, and here we consider the energetics of how they might form. Binary-exchange capture can occur if a binary-terrestrial object (BTO) is tidally disrupted during a close encounter with a giant planet and one of the binary members is ejected while the other remains as a moon. Tidal disruption occurs readily in the deep gravity wells of giant planets; however, the large encounter velocities in the wells make binary exchange more difficult than for planets of lesser mass. In addition, successful capture favors massive binaries with large rotational velocities and small component mass ratios. Also, since the interaction tends to leave the captured moons on highly elliptical orbits, permanent capture is only possible around planets with sizable Hill spheres that are well separated from their host stars.
Exomoon Habitability Constrained by Illumination and Tidal Heating
Authors:
1. Rene´ Heller (a)
2. Rory Barnes (b,c)
Affiliations:
a. Leibniz-Institute for Astrophysics Potsdam (AIP), Potsdam, Germany
b. Astronomy Department, University of Washington, Seattle, Washington, USA
c. NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
Abstract:
The detection of moons orbiting extrasolar planets (“exomoons”) has now become feasible. Once they are discovered in the circumstellar habitable zone, questions about their habitability will emerge. Exomoons are likely to be tidally locked to their planet and hence experience days much shorter than their orbital period around the star and have seasons, all of which works in favor of habitability. These satellites can receive more illumination per area than their host planets, as the planet reflects stellar light and emits thermal photons. On the contrary, eclipses can significantly alter local climates on exomoons by reducing stellar illumination. In addition to radiative heating, tidal heating can be very large on exomoons, possibly even large enough for sterilization. We identify combinations of physical and orbital parameters for which radiative and tidal heating are strong enough to trigger a runaway greenhouse. By analogy with the circumstellar habitable zone, these constraints define a circumplanetary “habitable edge.” We apply our model to hypothetical moons around the recently discovered exoplanet Kepler-22b and the giant planet candidate KOI211.01 and describe, for the first time, the orbits of habitable exomoons. If either planet hosted a satellite at a distance greater than 10 planetary radii, then this could indicate the presence of a habitable moon.
Mars Icebreaker Life Mission
The Sample Handling System for the Mars Icebreaker Life Mission: From Dirt to Data
Authors:
1. Arwen Davé (a,b)
2. Sarah J. Thompson (a,c)
3. Christopher P. McKay (a)
4. Carol R. Stoker (a)
5. Kris Zacny (d)
6. Gale Paulsen (d)
7. Bolek Mellerowicz (d)
8. Brian J. Glass (a)
9. David Willson (a,e)
10. Rosalba Bonaccorsi (a,f)
11. Jon Rask (g)
Affiliations:
a. NASA Ames Research Center, Moffett Field, California.
b. Lockheed Martin IS&GS, Moffett Field, California.
c. Stinger Ghaffarian Technologies, Inc., Moffett Field, California.
d. Honeybee Robotics, Pasadena, California.
e. KISS Institute for Practical Robotics, Moffett Field, California.
f. SETI Institute, Mountain View, California.
g. Dynamac Inc., Space Biosciences Division, NASA Ames Research Center, Mountain View, California.
Abstract:
The Mars Icebreaker Life mission will search for subsurface life on Mars. It consists of three payload elements: a drill to retrieve soil samples from approximately 1 m below the surface, a robotic sample handling system to deliver the sample from the drill to the instruments, and the instruments themselves. This paper will discuss the robotic sample handling system.
Collecting samples from ice-rich soils on Mars in search of life presents two challenges: protection of that icy soil—considered a “special region” with respect to planetary protection—from contamination from Earth, and delivery of the icy, sticky soil to spacecraft instruments. We present a sampling device that meets these challenges. We built a prototype system and tested it at martian pressure, drilling into ice-cemented soil, collecting cuttings, and transferring them to the inlet port of the SOLID2 life-detection instrument. The tests successfully demonstrated that the Icebreaker drill, sample handling system, and life-detection instrument can collectively operate in these conditions and produce science data that can be delivered via telemetry—from dirt to data. Our results also demonstrate the feasibility of using an air gap to prevent forward contamination. We define a set of six analog soils for testing over a range of soil cohesion, from loose sand to basalt soil, with angles of repose of 27° and 39°, respectively. Particle size is a key determinant of jamming of mechanical parts by soil particles. Jamming occurs when the clearance between moving parts is equal in size to the most common particle size or equal to three of these particles together. Three particles acting together tend to form bridges and lead to clogging. Our experiments show that rotary-hammer action of the Icebreaker drill influences the particle size, typically reducing particle size by 100 μm.
A New Wiwaxia Fossils From Cambrian China
New Wiwaxia material from the Tsinghsutung Formation (Cambrian Series 2) of Eastern Guizhou, China
Authors:
1. HAI-JING SUN (a)
2. YUAN-LONG ZHAO (a)
3. JIN PENG (a)
4. YU-NING YANG (a)
Affiliation:
a. College of Resources and Environmental Engineering, Guizhou University, Guiyang 550003, People's Republic of China
Abstract:
Wiwaxia is an extinct early metazoan with uncertain affinities, which is well represented in strata of Cambrian Series 2–3 age. Well-preserved representatives of Wiwaxia are known from the Burgess Shale Biota and the Kaili Biota. Here, new material of Wiwaxia corrugata (Matthew, 1899) is reported from the upper part of the Tsinghsutung Formation (Cambrian Series 2) near Balang Village, Guizhou Province, China. These specimens have a close evolutionary relationship to Wiwaxia taijiangensis Zhao, Qian & Lee, 1994 from the overlying Kaili Formation. New Wiwaxia material from the Tsinghsutung Formation and observations of specimens with articulated individuals from the Kaili Formation suggest that Wiwaxia taijiangensis should be a junior synonym of W. corrugata. A new study indicates that W. corrugata has a wide geographic distribution, a short geological history and evolutionary uniqueness and provides new data on taphonomy of this genus.
Gerta Keller Disputes Geochronology of Chicxulub and K-Pg/K-T Boundary (again)
Chicxulub impact spherules in the North Atlantic and Caribbean: age constraints and Cretaceous–Tertiary boundary hiatus
Authors:
1. GERTA KELLER (a)
2. HASSAN KHOZYEM (b)
3. THIERRY ADATTE (b)
4. NALLAMUTHU MALARKODI (c)
5. JORGE E. SPANGENBERG (d)
6. WOLFGANG STINNESBECK (e)
Affiliations:
a. Department of Geosciences, Princeton University, Princeton NJ 08544, USA
b. Institut de Science de la Terre et de l'Environment (ISTE), Université de Lausanne, Lausanne, CH-1015 Switzerland
c. Department of Geology, Bangalore University, Bangalore 560 056, India
d. Mineralogy and Geochemistry Institute, University of Lausanne, Anthropole, Lausanne, CH-1015 Switzerland
e. Institute für Geowissenschaften der Universität Heidelberg, 69120 Heidelberg, Germany
Abstract:
The Chicxulub impact is commonly believed to have caused the Cretaceous–Tertiary boundary mass extinction and a thin impact spherule layer in the North Atlantic and Caribbean is frequently cited as proof. We evaluated this claim in the seven best North Atlantic and Caribbean Cretaceous–Tertiary boundary sequences based on high-resolution biostratigraphy, quantitative faunal analyses and stable isotopes. Results reveal a major Cretaceous–Tertiary boundary unconformity spanning most of Danian subzone P1a(1) and Maastrichtian zones CF1–CF2 (~400 ka) in the NW Atlantic Bass River core, ODP Sites 1049A, 1049C and 1050C. In the Caribbean ODP Sites 999B and 1001B the unconformity spans from the early Danian zone P1a(1) through to zones CF1–CF4 (~3 Ma). Only in the Demerara Rise ODP Site 1259B is erosion relatively minor and restricted to the earliest Danian zone P0 and most of subzone P1a(1) (~150 ka). In all sites examined, Chicxulub impact spherules are reworked into the early Danian subzone P1a(1) about 150–200 ka after the mass extinction. A similar pattern of erosion and redeposition of impact spherules in Danian sediments has previously been documented from Cuba, Haiti, Belize, Guatemala, south and central Mexico. This pattern can be explained by intensified Gulf stream circulation at times of climate cooling and sea level changes. The age of the Chicxulub impact cannot be determined from these reworked impact spherule layers, but can be evaluated based on the stratigraphically oldest spherule layer in NE Mexico and Texas, which indicates that this impact predates the Cretaceous–Tertiary boundary by about 130–150 ka.
Wednesday, July 24, 2013
A Former Foreign Intelligence Surveillance Court Judge: Reform the Court
CONGRESS created the Foreign Intelligence Surveillance Court in 1978 as a check on executive authority. Recent disclosures about vast data-gathering by the government have raised concerns about the legitimacy of the court’s actions. Congress can take a simple step to restore confidence in the court’s impartiality and integrity: authorizing its judges to appoint lawyers to serve the public interest when novel legal issues come before it.
The court is designed to protect individual liberties as the government protects us from foreign dangers. In 1972, the Supreme Court ruled that the Nixon administration had violated the Fourth Amendment by conducting warrantless surveillance on a radical domestic group, the White Panthers, who were suspected of bombing a C.I.A. recruiting office in Ann Arbor, Mich. In 1975 and 1976, the Church Committee, a Senate panel, produced a series of reports about foreign and domestic intelligence operations, including surveillance by the F.B.I. of suspected communists, radicals and other activists — including, notoriously, the Rev. Dr. Martin Luther King Jr.
The Foreign Intelligence Service Act set up the FISA Court in response. To obtain authority to intercept the phone and electronic communications of American citizens and permanent residents, the government must only show probable cause that the target has a connection to a foreign government or entity or a foreign terrorist group. It does not have to show, as with an ordinary search warrant, probable cause that the target is suspected of a crime.
For decades, the court worked under the radar. That changed after 2005, when The New York Times disclosed a National Security Agency program of surveillance of e-mail to and from foreign countries. Though the surveillance was conducted outside of FISA (Congress later specified that FISA court approval was required), the disclosures brought the court to the public’s attention. Criticism of the court (on which I served for six years after 9/11, while the caseload grew enormously) revived recently after revelations that the N.S.A., without court orders specifying individual targets, gathered troves of data from companies like Google and Facebook.
[..]
James Robertson, a retired federal judge who served with me on the FISA court, recently called for greater transparency of the court’s proceedings. He has proposed the naming of an advocate, with high-level security clearance, to argue against the government’s filings. He suggested that the Privacy and Civil Liberties Oversight Board, which oversees surveillance activities, could also provide a check. I would go even further.
In an ordinary criminal case, the adversarial process assures legal representation of the defendant. Clearly, in top-secret cases involving potential surveillance targets, a lawyer cannot, in the conventional sense, represent the target.
Congress could, however, authorize the FISA judges to appoint, from time to time, independent lawyers with security clearances to serve “pro bono publico” — for the public’s good — to challenge the government when an application for a FISA order raises new legal issues.
During my six years on the court, there were several occasions when I and other judges faced issues none of us had encountered before. A staff of experienced lawyers assists the court, but their help was not always enough given the complexity of the issues.
The low FISA standard of probable cause — not spinelessness or excessive deference to the government — explains why the court has so often granted the Justice Department’s requests. But rapid advances in technology have outpaced the amendments to FISA, even the most recent ones, in 2008.
Having lawyers challenge novel legal assertions in these secret proceedings would result in better judicial outcomes. Even if the government got its way all or most of the time, the court would have more fully developed its reasons for letting it do so. Of equal importance, the appointed lawyer could appeal a decision in the government’s favor to the Foreign Intelligence Surveillance Court of Review — and then to the Supreme Court. No opportunity for such review exists today, because only the government can appeal a FISA court ruling.
Potential Biosignatures in Superearth Exoplanet Atmospheres
Potential Biosignatures in Super-Earth Atmospheres II. Photochemical Responses
Authors:
1. J.L. Grenfell (a)
2. S. Gebauer (a)
3. M. Godolt (a)
4. K. Palczynski (a)
5. H. Rauer (a,b)
6. J. Stock (b)
7. P. von Paris (d)
8. R. Lehmann (c)
9. F. Selsis (d)
Affiliations:
a. Zentrum für Astronomie und Astrophysik, Technische Universität Berlin (TUB), Berlin, Germany.
b. Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
c. Alfred-Wegener-Institut für Polar- und Meeresforschung, Potsdam, Germany.
d. Université de Bordeaux and CNRS, LAB, UMR 5804, Floirac, France.
Abstract:
Spectral characterization of super-Earth atmospheres for planets orbiting in the habitable zone of M dwarf stars is a key focus in exoplanet science. A central challenge is to understand and predict the expected spectral signals of atmospheric biosignatures (species associated with life). Our work applies a global-mean radiative-convective-photochemical column model assuming a planet with an Earth-like biomass and planetary development. We investigated planets with gravities of 1g and 3g and a surface pressure of 1 bar around central stars with spectral classes from M0 to M7. The spectral signals of the calculated planetary scenarios have been presented in an earlier work by Rauer and colleagues. The main motivation of the present work is to perform a deeper analysis of the chemical processes in the planetary atmospheres. We apply a diagnostic tool, the Pathway Analysis Program, to explore the photochemical pathways that form and destroy biosignature species. Ozone is a potential biosignature for complex life. An important result of our analysis is a shift in the ozone photochemistry from mainly Chapman production (which dominates in Earth's stratosphere) to smog-dominated ozone production for planets in the habitable zone of cooler (M5–M7)-class dwarf stars. This result is associated with a lower energy flux in the UVB wavelength range from the central star, hence slower planetary atmospheric photolysis of molecular oxygen, which slows the Chapman ozone production. This is important for future atmospheric characterization missions because it provides an indication of different chemical environments that can lead to very different responses of ozone, for example, cosmic rays. Nitrous oxide, a biosignature for simple bacterial life, is favored for low stratospheric UV conditions, that is, on planets orbiting cooler stars. Transport of this species from its surface source to the stratosphere where it is destroyed can also be a key process. Comparing 1g with 3g scenarios, our analysis suggests it is important to include the effects of interactive chemistry.
Did the Ancient Egytpians Document the Eclipsing Binary Algol
DID THE ANCIENT EGYPTIANS RECORD THE PERIOD OF THE ECLIPSING BINARY ALGOL—THE RAGING ONE?
Authors:
1. L. Jetsu (a)
2. S. Porceddu (a)
3. J. Lyytinen (a)
4. P. Kajatkari (a)
5. J. Lehtinen (a)
6. T. Markkanen (a)
7. J. Toivari-Viitala (b)
Affiliations:
a. Department of Physics, FI-00014 University of Helsinki, P.O. Box 64, Finland
b. Department of World Cultures, FI-00014 University of Helsinki, P.O. Box 59, Finland
Abstract:
The eclipses in binary stars give precise information of orbital period changes. Goodricke discovered the 2.867 day period in the eclipses of Algol in the year 1783. The irregular orbital period changes of this longest known eclipsing binary continue to puzzle astronomers. The mass transfer between the two members of this binary should cause a long-term increase of the orbital period, but observations over two centuries have not confirmed this effect. Here, we present evidence indicating that the period of Algol was 2.850 days three millennia ago. For religious reasons, the ancient Egyptians have recorded this period into the Cairo Calendar (CC), which describes the repetitive changes of the Raging one. CC may be the oldest preserved historical document of the discovery of a variable star.
DARPA's Hydra Unmanned Submarine Program
Unmanned vehicles designers at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., will brief industry next month on a project to develop an unmanned submersible designed to transport and deploy unmanned aerial vehicles (UAVs) and unmanned underwater vehicles (UUVs) stealthily close to enemy operations.
DARPA will conduct industry briefings on the Hydra program from 8 a.m. to 5 p.m. on 5 Aug. 2013 at the Johns Hopkins University Applied Physics Laboratory – Kossiakoff Center in Laurel, Md. Briefings will precede release on a broad agency announcement (BAA) for the Hydra program, DARPA officials say.
The Hydra program will develop and demonstrate an unmanned undersea system with a new kind of unmanned-vehicle delivery system that inserts UAVs and UUVs. stealthily into operational environments to respond quickly to situations around the world without putting U.S. military personnel at risk.
The Hydra large UUV is to use modular payloads inside a standardized enclosure to deploy a mix of UAVs and UUVs, depending on the military situation. Hydra will integrate existing and emerging technologies in new ways to create an alternate means of delivering a variety of payloads close to where they’re needed, DARPA officials say.
The Hydra program also will seek to develop and demonstrate not only the unmanned vehicle mothership, but also examples of the UAVs and UUVs that could be carried into battle covertly.
The rising number of ungoverned states, piracy, and proliferation of sophisticated defenses severely stretches current resources and influences U.S. military capability to conduct special operations and contingency missions, DARPA scientists say.
The Hydra program represents a way to add undersea capacity that can be tailored to support each mission. Technologies are to be adaptable to several different delivery options, including airborne, surface, and subsurface. The Hydra program could enable other new capabilities not currently performed from undersea, DARPA officials explain.
The program will demonstrate individual high-risk components and systems before the military commits to a specific full-system approach, and refine technologies prior to operational demonstrations of the UAV and UUV payloads.
Hydra will have three phases. First, the program will define concepts, develop component capabilities, and reduce subsystem risks with one or more contracts in several technical areas. Later, the program will develop and test a full system. Technical areas involve modular enclosures, air vehicle payloads, undersea payloads, concepts of operation, and supporting technologies.
3D Printing Causing a Collision of Copyright And Use
The world of 3D printing designers was set abuzz recently, when popular designer Asher Nahmias pulled his work from a well-known online store in protest after Stratasys, one of the biggest 3D printer manufacturers, improperly used one of his designs.
The incident – not the first and surely not the last – represented a curious reversal of sorts. Often, discussions about copyright or patent infringement related to 3D printing revolve around the idea of individuals stealing designs from corporations.
In this scenario, it was the reverse, highlighting just how much confusion there is around rights in 3D printing and how much work needs to be done to figure out how best to protect against improper use.
"With all the things this technology is capable of delivering in terms of improving designs and enhancing sustainability and delivering better personalized medical treatment, there are also a lot of unintended consequences," said Avi Reichental, president and CEO of 3D Systems, a 3D printer maker that itself has also been accused of improperly using Nahmias' designs. "Piracy and patent infringement and copyright infringement are going to be part and parcel of the unintended consequences powered by the same technology that can do so much good."
The Paleoecology of Oxfordian Jurassic Wyoming, USA
Palaeoecology of the marine reptiles of the Redwater Shale Member of the Sundance Formation (Jurassic) of central Wyoming, USA
Authors:
1. JUDY A. MASSARE (a)
2. WILLIAM R. WAHL (b)
3. MIKE ROSS (c)
4. MELISSA V. CONNELY (d)
Affiliations:
a. Earth Sciences Department, SUNY College at Brockport, Brockport, NY 14420, USA
b. Wyoming Dinosaur Center, Thermopolis, WY 82443, USA
c. 2614 Navarre Street, Casper, WY 82601, USA
d. Earth Science Department, Casper College, Casper, WY 82601, USA
Abstract:
The Redwater Shale Member (Oxfordian) of the Sundance Formation was deposited in the foreland basin of the Cordillera during the last and largest marine transgression of the Jurassic in North America. One ichthyosaur (Ophthalmosaurus natans), two cryptocleidoid plesiosaurs (Tatenectes laramiensis, Pantosaurus striatus) and one pliosauromorph (Megalneusaurus rex) are known from the Redwater Shale Member. Ichthyosaurs are much more abundant than plesiosaurs, making up almost 60% of the fauna. No actinopterygian fish have been found, although four species have been identified from the lower Sundance Formation. At least one hybodont shark and one neoselachian are known from rare isolated teeth. The main food source for the marine reptiles was belemnoids, as indicated by preserved gut contents for all four species. In comparison, the better known and slightly older Peterborough Member of the Oxford Clay Formation of England, has a much higher taxonomic and ecological diversity, especially in the plesiosaurs, marine crocodiles, and fish. The lower diversity in the Redwater Shale Member probably reflects a much lower primary productivity in the Sundance Sea, as well as restricted migration from the open ocean to the north.
Turonian Cretaceous Marine Amniotes From the Bohemian Basin
Turonian marine amniotes from the Bohemian Cretaceous Basin, Czech Republic
Authors:
1. BENJAMIN P. KEAR (a)
2. BORIS EKRT (b)
3. JOSEF PROKOP (c)
4. GEORGIOS L. GEORGALIS (d)
Affiliations:
a. Palaeobiology Programme, Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden
b. Department of Paleontology, National Museum Prague; Václavské námĕstí 68, 115 79 Prague, Czech Republic
c. Department of Physical Electronics, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19, Prague, Czech Republic
d. School of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54 124 Greece
Abstract:
Despite being known for over 155 years, the Late Cretaceous marine amniotes of the Bohemian Cretaceous Basin in the Czech Republic have received little recent attention. These fossils are however significant because they record a diverse range of taxa from an incompletely known geological interval: the Turonian. The presently identifiable remains include isolated bones and teeth, together with a few disarticulated skeletons. The most productive stratigraphical unit is the Lower–Middle Turonian Bílá Hora Formation, which has yielded small dermochelyoid sea turtles, a possible polycotylid plesiosaur and elements compatible with the giant predatory pliosauromorph Polyptychodon. A huge protostegid, together with an enigmatic cheloniid-like turtle, Polyptychodon-like dentigerous components, an elasmosaurid and a tethysaurine mosasauroid have also been found in strata corresponding to the Middle–Upper Turonian Jizera Formation and Upper Turonian – Coniacian Teplice Formation. The compositional character of the Bohemian Cretaceous Basin fauna is compatible with coeval assemblages from elsewhere along the peri-Tethyan shelf of Europe, and incorporates the globally terminal Middle–Upper Turonian occurrence of pliosauromorph megacarnivores, which were seemingly replaced by mosasauroids later in the Cretaceous.
