Near-Infrared Counterparts to Chandra X-ray Sources toward the Galactic Center. I. Statistics and a Catalog of Candidates

We present a catalog of 5184 candidate infrared counterparts to X-ray sources detected towards the Galactic center. The X-ray sample contains 9017 point sources detected in this region by the Chandra X-ray Observatory, including data from a recent deep survey of the central 2 x 0.8 deg of the Galactic plane. A total of 6760 of these sources have hard X-ray colors, and the majority of them lie near the Galactic center, while most of the remaining 2257 soft X-ray sources lie in the foreground. We cross-correlated the X-ray source positions with the 2MASS and SIRIUS near-infrared catalogs, which collectively contain stars with a 10-sigma limiting flux of K_s<=15.6 mag. In order to distinguish absorbed infrared sources near the Galactic center from those in the foreground, we defined red and blue sources as those which have H-K_s>=0.9 and <=0.9 mag, respectively. We find that 5.8(1.5)% of the hard X-ray sources have real infrared counterparts, of which 228(99) are red and 166(27) are blue. The red counterparts are probably comprised of WR/O stars, HMXBs, and symbiotics near the Galactic center. We also find that 39.4(1.0)% of the soft X-ray sources have blue infrared counterparts; most of these are probably coronally active dwarfs in the foreground. There is a noteworthy collection of ~20 red counterparts to hard X-ray sources near the Sagittarius-B H II region, which are probably massive binaries that have formed within the last several Myr. For each of the infrared matches to X-ray sources in our catalog we derived the probability that the association is real, based on the results of the cross-correlation analysis. The catalog will serve spectroscopic surveys to identify infrared counterparts to X-ray sources near the Galactic center.Comment: Submitted to ApJ January 16, 2009; accepted July 21, 2009; 30 pages, 6 figure

Obscured by “Willful Blindness”: States’ Preventive Obligations and the Meaning of Acquiescence Under the Convention Against Torture

As U.S. asylum law becomes more restrictive, relief under the U.N. Convention Against Torture (CAT) has become the last hope for safety for many asylum seekers. But for those who face torture at the hands of non-State actors, CAT relief has proven extraordinarily hard to win. The CAT’s torture definition encompasses privately-inflicted harm only when it occurs with the consent or acquiescence of a public official. Agency decisions initially took this to mean that officials must willfully accept or tacitly approve the private party’s actions. Courts have rejected that approach as overly restrictive. But what they have adopted in its place—a “willful blindness” test under which CAT applicants must show that officials would turn a blind eye to the torture they face—is also problematic. Under this standard, even where government officials take only half-hearted or patently inadequate steps to combat acts of privately-inflicted torture such as domestic violence, honor killings, gang violence, or mob attacks on LGBTQI people, courts frequently conclude that acquiescence has not been shown. As long as officials are doing something, the decisions reason, they are not willfully blind. This Article argues that willful blindness should not be the test for acquiescence. The term “acquiescence” is defined in a Senate ratification understanding to require that a public official have awareness of the torturous activity and breach a legal responsibility to intervene to prevent it. This definition, which has been incorporated into U.S. law, makes clear that when officials are aware of torturous activity—and in most cases there is no doubt that a country’s government is aware of widespread patterns of abuse—what matters is whether they breach their legal responsibility to take preventive action. Drawing on previously overlooked aspects of the history of the CAT’s drafting and U.S. ratification, this Article argues that officials acquiesce to torture if they fail to meet their legal responsibility under international law to take effective preventive measures. The State’s responsibility to exercise “due diligence” to prevent, investigate, prosecute, and punish acts of torture by non-State actors is widely recognized under the CAT and other human rights treaties. The U.N. Committee Against Torture has found that when States fail to exercise due diligence, they enable private parties to commit acts of torture with impunity, and thereby acquiesce. That approach accords with how the U.S., during the treaty negotiations, originally defined “acquiescence” when it proposed adding the term to the CAT’s torture definition. It also fits in comfortably with the text and purpose of the treaty and its U.S. ratification understandings. The Article concludes by considering what a due diligence standard for acquiescence would look like in practice and addresses potential objections to its appropriateness and administrability. It also offers a proposal to amend the CAT regulations to clarify the acquiescence standard

Extent of Fermi-surface reconstruction in the high-temperature superconductor HgBa2_2CuO4+δ_{4+\delta}

High magnetic fields have revealed a surprisingly small Fermi-surface in underdoped cuprates, possibly resulting from Fermi-surface reconstruction due to an order parameter that breaks translational symmetry of the crystal lattice. A crucial issue concerns the doping extent of this state and its relationship to the principal pseudogap and superconducting phases. We employ pulsed magnetic field measurements on the cuprate HgBa$_2$CuO$_{4+\delta}$ to identify signatures of Fermi surface reconstruction from a sign change of the Hall effect and a peak in the temperature-dependent planar resistivity. We trace the termination of Fermi-surface reconstruction to two hole concentrations where the superconducting upper critical fields are found to be enhanced. One of these points is associated with the pseudogap end-point near optimal doping. These results connect the Fermi-surface reconstruction to both superconductivity and the pseudogap phenomena.Comment: 5 pages. 3 Figures. PNAS (2020

Project Manager ‘Management Competency’ vs. ‘Technical Competency’. Which Is More Important to Overall Project Management Success?

Project managers apply multiple skills and competencies in the course of successfully delivering projects. Management and technical competencies represent two major competency categories associated with project management. In this study, the relationship between management and technical competency was investigated and a weak, yet positive correlation was observed as an outcome of this quantitative study

Massive Stellar X-ray Sources in the Galactic Center

We present results of a spectroscopic survey of bright near-infrared counterparts to X-ray point sources from a deep Chandra survey of the Galactic nuclear bulge. K-band spectroscopy has revealed 13 new Wolf-Rayet and O-supergiant counterparts to Chandra sources in the Galactic center (GC). Although they are systematically softer in X-rays than the general GC source population of accretion powered cataclysmic variables (CVs), their X-ray colors indicate a hard component consistent with emission from plasmas with E > 2 keV. Such hard X-ray emission is not ubiquitous among single Wolf-Rayet and O stars, but is common among Wolf-Rayet+OB binaries with colliding supersonic winds. Although we regard colliding-wind binary hypothesis as the most likely scenario, it remains possible that several of these objects are wind-accreting neutron stars or black holes in supergiant high-mass X-ray binaries, or extraordinary single stars emitting hard X-rays

Temporal variability and the relationship between benthic meiofaunal and microbial populations of a natural coastal petroleum seep

Previous studies of the Isla Vista petroleum seep in the Santa Barbara Channel found much higher abundances of macrofauna and concentrations of adenosine triphosphate (ATP) in sediments near petroleum seepage compared to those from nonseep areas. To further assess the possible effect of petroleum on organisms at the base of benthic food webs, population abundances of meiobenthos and their suspected microbial food (bacteria and diatoms) were measured biweekly for one year at three stations with differing petroleum exposure. Determinations of suspended particulate matter and the abundance and gut contents of juvenile fishes were also made at seep and nonseep stations. Nematodes and bacteria had higher abundances in areas of active petroleum seepage than in areas of moderate seepage (within 20 m) or no seepage (1.4 km away). Bacterial productivity (based on the frequency of dividing cells) was 340% greater in sediments from areas of active seepage compared to those from a nonseep station. Sediments within the seep, but away from active seepage, had rates of bacterial productivity 15 times greater than a nonseep comparison site. Densities of harpacticoid copepods and their probable principal food, diatoms, were not affected by petroleum seepage. Suspended organic matter caught in settling traps was not different between seep and nonseep stations. In addition, there was no evidence that predation pressure by juvenile fish on meiofauna was different between stations. The higher bacterial biomass and productivity in areas of petroleum seepage are consistent with the hypothesis that petroleum carbon is available for assimilation by sediment bacteria. The enhanced level of microbial carbon associated with the petroleum seep is available for consumption by benthic invertebrates and could explain the higher abundances of macrofauna and meiofauna found there

Spatial Attention, Precision, and Bayesian Inference: A Study of Saccadic Response Speed

Inferring the environment's statistical structure and adapting behavior accordingly is a fundamental modus operandi of the brain. A simple form of this faculty based on spatial attentional orienting can be studied with Posner's location-cueing paradigm in which a cue indicates the target location with a known probability. The present study focuses on a more complex version of this task, where probabilistic context (percentage of cue validity) changes unpredictably over time, thereby creating a volatile environment. Saccadic response speed (RS) was recorded in 15 subjects and used to estimate subject-specific parameters of a Bayesian learning scheme modeling the subjects' trial-by-trial updates of beliefs. Different response models—specifying how computational states translate into observable behavior—were compared using Bayesian model selection. Saccadic RS was most plausibly explained as a function of the precision of the belief about the causes of sensory input. This finding is in accordance with current Bayesian theories of brain function, and specifically with the proposal that spatial attention is mediated by a precision-dependent gain modulation of sensory input. Our results provide empirical support for precision-dependent changes in beliefs about saccade target locations and motivate future neuroimaging and neuropharmacological studies of how Bayesian inference may determine spatial attentio

Discrepant Effects of Human Interferon-gamma on Clinical and Immunological Disease Parameters in a Novel Marmoset Model for Multiple Sclerosis

The core pathogenic process in the common marmoset model of multiple sclerosis (MS) is the activation of memory-like T cells specific for peptide 34 to 56 derived from the extracellular domain of myelin/oligodendrocyte glycoprotein (MOG34-56). Immunization with MOG34-56 in incomplete Freund’s adjuvant is a sufficient stimulus for in vivo activation of these T cells, together with the induction of MS-like disease and CNS pathology. Ex vivo functional characteristics of MOG34-56 specific T cells are specific cytolysis of peptide pulsed target cells and high IL-17A production. To indentify possible functions in this new model of T helper 1 cells, which play a central pathogenic role in MS models induced with complete Freund’s adjuvant, we tested the effect of human interferon-γ (IFNγ) administration during disease initiation of the disease (day 0–25) and around the time of disease expression (psd 56–81). The results show a clear modulatory effect of early IFNγ treatment on humoral and cellular autoimmune parameters, but no generalized mitigating effect on the disease course. These results argue against a prominent pathogenic role of T helper 1 cells in this new marmoset EAE model