58 research outputs found
HM+ and HM+?He (M = Group 2 metal): chemical or physical interactions?
We investigate the HM+–He complexes (M = Group 2 metal) using quantum chemistry. Equilibrium geometries are linear for M = Be and Mg, and bent for M = Ca–Ra; the explanation for this lies in the differing nature of the highest occupied molecular orbitals in the two sets of complexes. The difference primarily occurs as a result of the formation of the H–M+ bond, and so the HM+ diatomics are also studied as part of the present work. The position of the He atom in the complexes is largely determined by the form of the electron density. HM+. . . He binding energies are obtained and are surprisingly high for a helium complex. The HBe+. . . He value is almost 3000 cm−1, which is high enough to suspect contributions from chemical bonding. This is explored by examining the natural orbital density and by population analyses
Thermal Infrared MMTAO Observations of the HR 8799 Planetary System
We present direct imaging observations at wavelengths of 3.3, 3.8 (L',band),
and 4.8 (M band) microns, for the planetary system surrounding HR 8799. All
three planets are detected at L'. The c and d component are detected at 3.3
microns, and upper limits are derived from the M band observations. These
observations provide useful constraints on warm giant planet atmospheres. We
discuss the current age constraints on the HR 8799 system, and show that
several potential co-eval objects can be excluded from being co-moving with the
star. Comparison of the photometry is made to models for giant planet
atmospheres. Models which include non-equilibrium chemistry provide a
reasonable match to the colors of c and d. From the observed colors in the
thermal infrared we estimate T_eff < 960 K for b, and T_eff=1300 and 1170 K for
c and d, respectively. This provides an independent check on the effective
temperatures and thus masses of the objects from the Marois 2008 results.Comment: 16 pages, 6 figures, accepted to Ap
U.S. Army Small Space Update
In December 2010, the U.S. Army flew its first satellite in 50 years, the SMDC-ONE CubeSat. Placed in a very low orbit, the first SMDC-ONE mission lasted only 35 days but enjoyed great success in demonstrating the viability of CubeSats to perform exfiltration of unattended ground sensors data and serve as a communications relay between ground stations over 1000 land miles apart. The success of SMDC-ONE helped shape the U.S. Army’s Space and Missile Defense Command’s (SMDC) programmatic goals for finding new and innovative ways to implement space applications and technologies that aid the warfighter. Since 2010, SMDC has flown ten additional CubeSats including the three SMDC Nanosatellite Program-3 (SNaP) CubeSats currently on orbit (launched October 2015). This paper addresses several SMDC satellite-related development efforts including SNaP, Army Resilient Global On-the-move SATCOM (ARGOS) Ka-band communications microsatellites, Kestrel Eye (an imaging microsatellite), Kestrel Eye Ground Station (KEGS), Common Ground Station (CGS) for all future Army small satellites, supporting technologies including Small Business Innovative Research (SBIR) efforts, the Concepts Analysis Laboratory, SMDC Space Laboratory, the ACES RED effort and earlier responsive launch vehicle activities. Several of the lessons learned from previous as well as ongoing satellite activities are also covered
An Analysis of the Legal, Social, and Political Issues Raised by Asbestos Litigation
This Special Project examines the most important issues of the asbestos problem and advocates a congressional solution (1) to relieve the courts of the thousands of present and potential asbestos cases, (2) to protect future claimants\u27 rights to adequate compensation, and (3) to provide for equitable participation by all responsible parties, which, in addition to asbestos manufacturers,include the federal government, insurance companies, and the tobacco industry. The first six parts of the Special Project examine the various issues of asbestos litigation: theories of liability in products liability suits against asbestos manufacturers, causation,defenses, statutory limitations on actions, collateral estoppel, and punitive damages. The Special Project then discusses in parts VIII,IX, and X the methods used by asbestos manufacturers to attempt to spread their liability through asserting insurer liability, the exclusive remedy of workers\u27 compensation, and indemnity and contribution from the United States. Finally, the Special Project evaluates and analyzes recent developments in the asbestos litigation area, including proposals for federal legislative compensation programs and business alternatives available to asbestos manufacturers facing enormous asbestos-related liabilities...
This Special Project critically has examined the most important issues concerning the asbestos problem. It has considered the complex legal, legislative, and social questions that society must confront in order to resolve this predicament. Only swift action by Congress in the form of a fair and comprehensive compensation scheme for victims of asbestos-related disabilities will initiate a solution to this difficult and pervasive problem
First Light LBT AO Images of HR 8799 bcde at 1.65 and 3.3 Microns: New Discrepancies between Young Planets and Old Brown Dwarfs
As the only directly imaged multiple planet system, HR 8799 provides a unique
opportunity to study the physical properties of several planets in parallel. In
this paper, we image all four of the HR 8799 planets at H-band and 3.3 microns
with the new LBT adaptive optics system, PISCES, and LBTI/LMIRCam. Our images
offer an unprecedented view of the system, allowing us to obtain H and 3.3$
micron photometry of the innermost planet (for the first time) and put strong
upper-limits on the presence of a hypothetical fifth companion. We find that
all four planets are unexpectedly bright at 3.3 microns compared to the
equilibrium chemistry models used for field brown dwarfs, which predict that
planets should be faint at 3.3 microns due to CH4 opacity. We attempt to model
the planets with thick-cloudy, non-equilibrium chemistry atmospheres, but find
that removing CH4 to fit the 3.3 micron photometry increases the predicted L'
(3.8 microns) flux enough that it is inconsistent with observations. In an
effort to fit the SED of the HR 8799 planets, we construct mixtures of cloudy
atmospheres, which are intended to represent planets covered by clouds of
varying opacity. In this scenario, regions with low opacity look hot and
bright, while regions with high opacity look faint, similar to the patchy cloud
structures on Jupiter and L/T transition brown-dwarfs. Our mixed cloud models
reproduce all of the available data, but self-consistent models are still
necessary to demonstrate their viability.Comment: Accepted to Ap
Structural Extremes in a Cretaceous Dinosaur
Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic
The problem of constitutional legitimation: what the debate on electoral quotas tells us about the legitimacy of decision-making rules in constitutional choice
Proponents of electoral quotas have a ‘dependent interpretation’ of democracy, i.e. they have formed an opinion on which decision-making rules are fair on the basis of their prior approval of the outcomes these rules are likely to generate. The article argues that this position causes an irresolvable problem for constitutional processes that seek to legitimately enact institutional change. While constitutional revision governed by formal equality allows the introduction of electoral quotas, this avenue is normatively untenable for proponents of affirmative action if they are consistent with their claim that formal equality reproduces biases and power asymmetries at all levels of decision-making. Their critique raises a fundamental challenge to the constitutional revision rule itself as equally unfair. Without consensus on the decision-making process by which new post-constitutional rules can be legitimately enacted, procedural fairness becomes an issue impossible to resolve at the stage of constitutional choice. This problem of legitimation affects all instances of constitutional choice in which there are opposing views not only about the desired outcome of the process but also about the decision-making rules that govern constitutional choice
A computational framework for complex disease stratification from multiple large-scale datasets.
BACKGROUND: Multilevel data integration is becoming a major area of research in systems biology. Within this area, multi-'omics datasets on complex diseases are becoming more readily available and there is a need to set standards and good practices for integrated analysis of biological, clinical and environmental data. We present a framework to plan and generate single and multi-'omics signatures of disease states. METHODS: The framework is divided into four major steps: dataset subsetting, feature filtering, 'omics-based clustering and biomarker identification. RESULTS: We illustrate the usefulness of this framework by identifying potential patient clusters based on integrated multi-'omics signatures in a publicly available ovarian cystadenocarcinoma dataset. The analysis generated a higher number of stable and clinically relevant clusters than previously reported, and enabled the generation of predictive models of patient outcomes. CONCLUSIONS: This framework will help health researchers plan and perform multi-'omics big data analyses to generate hypotheses and make sense of their rich, diverse and ever growing datasets, to enable implementation of translational P4 medicine
Measurement of parity violation in the elastic scattering of polarized electrons from \u3csup\u3e12\u3c/sup\u3eC
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 12C nuclei. Our result is Aexpt=0.60±0.14±0.02 ppm, where the first error is statistical and the second is systematic. With a beam polarization of 0.37, we compute the isoscalar vector hadronic coupling constant γ̃ to be 0.136±0.032±0.009. The standard model predicts γ̃ =0.155 at the tree level, in agreement with our data
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