High-Energy Spectra of Active Galactic Nuclei. II. Absorption in Seyfert Galaxies

Absorption by cold material in a large sample of active galaxies has been analyzed in order to study statistically the behavior of absorbed sources. The analysis indicates that on the basis of the column density alone, sources can be divided into low-absorption ([NH/NHGal] ? 50) and high-absorption ([NH/NHGal] ? 50) objects. While the second group consists mostly of narrow emission line galaxies (Seyfert galaxies of type 1.9-2), the first group is less homogenous, being formed by a mixture of broad and narrow emission line objects (Seyfert 1-2 galaxies). A study of the distribution of the column density values by means of bootstrap analysis confirms the reality of this effect. One group consisting of optically selected objects is well explained within the unified theory as nuclei obscured by a molecular torus. The second group made up of X-ray- and IRAS-selected objects is more difficult to define: in these sources the absorption is underestimated owing to difficulties (1) in fitting complex absorption spectra or (2) in measuring NH values in Compton-thick sources or the absorption has a different origin than in the torus. Possible correlations of absorption with X-ray luminosity, axial ratio, and Balmer decrement have also been investigated. Previous suggestions that lower luminosity AGNs tend to be more highly absorbed than those with higher luminosity are not confirmed by the present data; neither is any evidence for a correlation of NH with axial ratio (b/a) found except for a preference of Seyfert 1-1.5 galaxies to be in face-on galaxies. While some sources (Seyfert 1-1.5 galaxies and low-absorption objects) have X-ray absorption compatible with Balmer decrement, high-absorption objects have column densities much higher than predicted from optical observations. These results are in agreement with the unified theory since the torus parameters are expected to be independent of luminosity, its orientation should be random with respect to the host galaxy, and its location should be in between the broad- and narrow-line regions. A study of the NH variability indicates that in a large fraction (70%) of the sources for which the analysis could be done, NH varies on timescales from months to years. In Seyfert 1-1.5 galaxies, the variability is associated with a region in or near the broad-line region and is explained in terms of partial covering and/or warm absorption models. In Seyfert 2 galaxies, the only variability observed is that associated with narrow emission line galaxies. The study of the column density distributions indicates that Seyfert 1-1.5 galaxies are characterized by NH = 18+9?7 ? 1021 atoms cm-2. Seyfert 1.9-2 galaxies have instead NH = 96+54?35 ? 1021 atoms cm-2 and a larger dispersion; if this group is divided into low- and high-absorption objects, NH = 14.5+7.2?5.3 ? 1021 atoms cm-2 and NH = 132.8+80.1?52.6 ? 1021 atoms cm-2, respectively, are obtained. The observed dispersion in each group is consistent with being entirely due to column density variability

A Comparative Astrochemical Study Of The High-Mass Protostellar Objects NGC 7538 IRS 9 and IRS 1

We report the results of a spectroscopic study of the high-mass protostellar object NGC 7538 IRS 9 and compare our observations to published data on the nearby object NGC 7538 IRS 1. Both objects originated in the same molecular cloud and appear to be at different points in their evolutionary histo- ries, offering an unusual opportunity to study the temporal evolution of envelope chemistry in objects sharing a presumably identical starting composition. Observations were made with the Texas Echelon Cross Echelle Spectrograph (TEXES), a sensitive, high spectral resolution (R = {\lambda}/{\Delta}{\lambda} \simeq 100,000) mid-infrared grating spectrometer. Forty-six individual lines in vibrational modes of the molecules C2H2, CH4, HCN, NH3 and CO were detected, including two isotopologues (13CO, 12C18O) and one combination mode ({\nu}4 + {\nu}5 C2H2). Fitting synthetic spectra to the data yielded the Doppler shift, excitation temperature, Doppler b parameter, column density and covering factor for each molecule observed; we also computed column density upper limits for lines and species not detected, such as HNCO and OCS. We find differences among spectra of the two objects likely attributable to their differing radiation and thermal environments. Temperatures and column densities for the two objects are generally consistent, while the larger line widths toward IRS 9 result in less saturated lines than those toward IRS 1. Finally, we compute an upper limit on the size of the continuum-emitting region (\sim2000 AU) and use this constraint and our spectroscopy results to construct a schematic model of IRS 9.Comment: 23 pages, 15 figures, 6 tables; accepted for publication in Ap

Linkage between solid-phase apportionment and bioaccessible arsenic, chromium and lead in soil from Glasgow, Scotland, UK

The chemical composition of soil from the Glasgow (UK) urban area was used to identify the controls on the availability of potentially harmful elements (PHEs) in soil to humans. Total and bioaccessible concentrations of arsenic (As), chromium (Cr) and lead (Pb) in 27 soil samples, collected from different land uses, were coupled to information on their solid-phase partitioning derived from sequential extraction data. The total element concentrations in the soils were in the range <0.1–135mgkg–1 for As; 65–3680mgkg–1 for Cr and 126–2160mgkg–1 for Pb, with bioaccessible concentrations averaging 27, 5 and 27% of the total values, respectively. Land use does not appear to be a predictor of contamination; however, the history of the contamination is critically important. The Chemometric Identification of Substrates and Element Distribution (CISED) sequential chemical extraction and associated self-modelling mixture resolution analysis identified three sample groupings and 16 geochemically distinct phases (substrates). These were related to iron (n=3), aluminium–silicon (Al–Si; n=2), calcium (n=3), phosphorus (n=1), magnesium (Mg; n=3), manganese (n=1) and easily extractable (n=3), which was predominantly made up of sodium and sulphur. As, Cr and Pb were respectively found in 9, 10 and 12 of the identified phases, with bioaccessible As predominantly associated with easily extractable phases, bioaccessible Cr with the Mg-dominated phases and bioaccessible Pb with both the Mg-dominated and Al–Si phases. Using a combination of the Unified Barge Method to measure the bioaccessibility of PHEs and CISED to identify the geochemical sources has allowed a much better understanding of the complexity of PHE mobility in the Glasgow urban environment. This approach can be applied to other urban environments and cases of soil contamination, and made part of land-use planning

Reference Array and Design Consideration for the next-generation Event Horizon Telescope

We describe the process to design, architect, and implement a transformative enhancement of the Event Horizon Telescope (ngEHT). This program - the next-generation Event Horizon Telescope (ngEHT) - will form a networked global array of radio dishes capable of making high-fidelity real-time movies of supermassive black holes (SMBH) and their emanating jets. This builds upon the EHT principally by deploying additional modest-diameter dishes to optimized geographic locations to enhance the current global mm/submm wavelength Very Long Baseline Interferometric (VLBI) array, which has, to date, utilized mostly pre-existing radio telescopes. The ngEHT program further focuses on observing at three frequencies simultaneously for increased sensitivity and Fourier spatial frequency coverage. Here, the concept, science goals, design considerations, station siting and instrument prototyping are discussed, and a preliminary reference array to be implemented in phases is described.Comment: Submitted to the journal Galaxie

Conceptual Design for a Dual-Bell Rocket Nozzle System Using a NASA F-15 Airplane as the Flight Testbed

The dual-bell rocket nozzle was first proposed in 1949, offering a potential improvement in rocket nozzle performance over the conventional-bell nozzle. Despite the performance advantages that have been predicted, both analytically and through static test data, the dual-bell nozzle has still not been adequately tested in a relevant flight environment. In 2013 a proposal was constructed that offered a NASA F-15 airplane as the flight testbed, with the plan to operate a dual-bell rocket nozzle during captive-carried flight. If implemented, this capability will permit nozzle operation into an external flow field similar to that of a launch vehicle, and facilitate an improved understanding of dual-bell nozzle plume sensitivity to external flow-field effects. More importantly, this flight testbed can be utilized to help quantify the performance benefit with the dual-bell nozzle, as well as to advance its technology readiness level. This presentation provides highlights of a technical paper that outlines this ultimate goal, including plans for future flights to quantify the external flow field of the airplane near the nozzle experiment, as well as details on the conceptual design for the dual-bell nozzle cold-flow propellant feed system integration within the NASA F-15 Propulsion Flight Test Fixture. The current study shows that this concept of flight research is feasible, and could result in valuable flight data for the dual-bell nozzle

Pest population dynamics are related to a continental overwintering gradient

Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests

The SSDC Role in the LICIACube Mission: Data Management and the MATISSE Tool

Light Italian Cubesat for Imaging of Asteroids (LICIACube) is an Italian mission managed by the Italian Space Agency (ASI) and part of the NASA Double Asteroid Redirection Test (DART) planetary defense mission. Its main goals are to document the effects of the DART impact on Dimorphos, the secondary member of the (65803) Didymos binary asteroid system, characterizing the shape of the target body and performing dedicated scientific investigations on it. Within this framework, the mission Science Operations Center will be managed by the Space Science Data Center (ASI-SSDC), which will have the responsibility of processing, archiving, and disseminating the data acquired by the two LICIACube onboard cameras. In order to better accomplish this task, SSDC also plans to use and modify its scientific webtool Multi-purpose Advanced Tool for Instruments for the solar system Exploration (MATISSE), making it the primary tool for the LICIACube data analysis, thanks to its advanced capabilities for searching and visualizing data, particularly useful for the irregular shapes common to several small bodies

The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities

Measured spectral shifts due to intrinsic stellar variability (e.g., pulsations, granulation) and activity (e.g., spots, plages) are the largest source of error for extreme-precision radial-velocity (EPRV) exoplanet detection. Several methods are designed to disentangle stellar signals from true center-of-mass shifts due to planets. The Extreme-precision Spectrograph (EXPRES) Stellar Signals Project (ESSP) presents a self-consistent comparison of 22 different methods tested on the same extreme-precision spectroscopic data from EXPRES. Methods derived new activity indicators, constructed models for mapping an indicator to the needed radial-velocity (RV) correction, or separated out shape- and shift-driven RV components. Since no ground truth is known when using real data, relative method performance is assessed using the total and nightly scatter of returned RVs and agreement between the results of different methods. Nearly all submitted methods return a lower RV rms than classic linear decorrelation, but no method is yet consistently reducing the RV rms to sub-meter-per-second levels. There is a concerning lack of agreement between the RVs returned by different methods. These results suggest that continued progress in this field necessitates increased interpretability of methods, high-cadence data to capture stellar signals at all timescales, and continued tests like the ESSP using consistent data sets with more advanced metrics for method performance. Future comparisons should make use of various well-characterized data sets—such as solar data or data with known injected planetary and/or stellar signals—to better understand method performance and whether planetary signals are preserved

Transcriptional diversity during lineage commitment of human blood progenitors.

Blood cells derive from hematopoietic stem cells through stepwise fating events. To characterize gene expression programs driving lineage choice, we sequenced RNA from eight primary human hematopoietic progenitor populations representing the major myeloid commitment stages and the main lymphoid stage. We identified extensive cell type-specific expression changes: 6711 genes and 10,724 transcripts, enriched in non-protein-coding elements at early stages of differentiation. In addition, we found 7881 novel splice junctions and 2301 differentially used alternative splicing events, enriched in genes involved in regulatory processes. We demonstrated experimentally cell-specific isoform usage, identifying nuclear factor I/B (NFIB) as a regulator of megakaryocyte maturation-the platelet precursor. Our data highlight the complexity of fating events in closely related progenitor populations, the understanding of which is essential for the advancement of transplantation and regenerative medicine.The work described in this article was primarily supported by the European Commission Seventh Framework Program through the BLUEPRINT grant with code HEALTH-F5-2011-282510 (D.H., F.B., G.C., J.H.A.M., K.D., L.C., M.F., S.C., S.F., and S.P.G.). Research in the Ouwehand laboratory is further supported by program grants from the National Institute for Health Research (NIHR, www.nihr.ac.uk; to A.A., M.K., P.P., S.B.G.J., S.N., and W.H.O.) and the British Heart Foundation under nos. RP-PG-0310-1002 and RG/09/12/28096 (www.bhf.org.uk; to A.R. and W.J.A.). K.F. and M.K. were supported by Marie Curie funding from the NETSIM FP7 program funded by the European Commission. The laboratory receives funding from the NHS Blood and Transplant for facilities. The Cambridge BioResource (www.cambridgebioresource.org.uk), the Cell Phenotyping Hub, and the Cambridge Translational GenOmics laboratory (www.catgo.org.uk) are supported by an NIHR grant to the Cambridge NIHR Biomedical Research Centre (BRC). The BRIDGE-Bleeding and Platelet Disorders Consortium is supported by the NIHR BioResource—Rare Diseases (http://bioresource.nihr.ac.uk/; to E.T., N.F., and Whole Exome Sequencing effort). Research in the Soranzo laboratory (L.V., N.S., and S. Watt) is further supported by the Wellcome Trust (Grant Codes WT098051 and WT091310) and the EU FP7 EPIGENESYS initiative (Grant Code 257082). Research in the Cvejic laboratory (A. Cvejic and C.L.) is funded by the Cancer Research UK under grant no. C45041/A14953. S.J.S. is funded by NIHR. M.E.F. is supported by a British Heart Foundation Clinical Research Training Fellowship, no. FS/12/27/29405. E.B.-M. is supported by a Wellcome Trust grant, no. 084183/Z/07/Z. Research in the Laffan laboratory is supported by Imperial College BRC. F.A.C., C.L., and S. Westbury are supported by Medical Research Council Clinical Training Fellowships, and T.B. by a British Society of Haematology/NHS Blood and Transplant grant. R.J.R. is a Principal Research Fellow of the Wellcome Trust, grant no. 082961/Z/07/Z. Research in the Flicek laboratory is also supported by the Wellcome Trust (grant no. 095908) and EMBL. Research in the Bertone laboratory is supported by EMBL. K.F. and C.v.G. are supported by FWO-Vlaanderen through grant G.0B17.13N. P.F. is a compensated member of the Omicia Inc. Scientific Advisory Board. This study made use of data generated by the UK10K Consortium, derived from samples from the Cohorts arm of the project.This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science on 26/9/14 in volume 345, number 6204, DOI: 10.1126/science.1251033. This version will be under embargo until the 26th of March 2015

spatially-explicit test of the refuge strategy for delaying insecticide resistance

The refuge strategy is used worldwide to delay the evolution of pest resistance to insecticides that are either sprayed or produced by transgenic Bacillus thuringiensis (Bt) crops. This strategy is based on the idea that refuges of host plants where pests are not exposed to an insecticide promote survival of susceptible pests. Despite widespread adoption of this approach, large-scale tests of the refuge strategy have been problematic. Here we tested the refuge strategy with 8 y of data on refuges and resistance to the insecticide pyriproxyfen in 84 populations of the sweetpotato whitefly (Bemisia tabaci) from cotton fields in central Arizona. We found that spatial variation in resistance to pyriproxyfen within each year was not affected by refuges of melons or alfalfa near cotton fields. However, resistance was negatively associated with the area of cotton refuges and positively associated with the area of cotton treated with pyriproxyfen. A statistical model based on the first 4 y of data, incorporating the spatial distribution of cotton treated and not treated with pyriproxyfen, adequately predicted the spatial variation in resistance observed in the last 4 y of the study, confirming that cotton refuges delayed resistance and treated cotton fields accelerated resistance. By providing a systematic assessment of the effectiveness of refuges and the scale of their effects, the spatially explicit approach applied here could be useful for testing and improving the refuge strategy in other crop-pest systems. pesticide resistance | predictive evolutionary models | pest management | resistance management P opulation growth will continue to favor agricultural intensification for decades. Because agricultural intensification is associated with increased pest pressure, pesticides generally help to increase yield (1-3). Although significant progress has been made to reduce reliance on pesticides (4, 5), an increasing number of insects and mites exhibit field-evolved resistance to synthetic pesticides, Bacillus thuringiensis (Bt) sprays, and transgenic Bt crops (6, 7). Negative consequences of resistance include increased pesticide use, disruption of food webs and ecosystem services, increased risk to human health, and loss of profits for farmers and industry (1, 3). One of the main strategies for delaying resistance promotes survival of susceptible pests by providing refuges, which are areas of host plants where pests are not exposed to an insecticide. Theory predicts that refuges will slow the evolution of resistance by reducing the fitness advantage of resistant individuals (7-9). Refuges can also reduce the heritability of resistance when susceptible individuals mate with resistant individuals surviving exposure to an insecticide (7). Empirical support for the refuge strategy was provided by short-term laboratory and greenhouse experiments (10, 11). Although these experiments test the hypothesis that mating between susceptible and resistant individuals delays the evolution of resistance, they do not consider several factors that affect resistance in the field (7-9), and thus only provide partial support for effectiveness of the refuge strategy in the field. Retrospective analyses of variation in resistance evolution in the field also suggest that refuges have been effective, but these previous tests have been based primarily on comparisons among species, or qualitative comparisons within species based on a limited number of widely separated geographic areas (12, 13). In such tests, factors that vary among species or geographic areas can confound the effects of refuges. Accordingly, large-scale field tests of the refuge strategy for a single species within a geographic area where factors affecting resistance are similar are needed to test the refuge strategy more rigorously. Moreover, tests of predictive refuge strategy models are required to determine if the refuge strategy can delay resistance (14). Furthermore, to improve our ability to develop efficient refuge strategies, empirical approaches are necessary to characterize effects of refuges on resistance evolution (7, 15). Here we tested the refuge strategy using 8 y of data on refuges and resistance to the insecticide pyriproxyfen in 84 populations of the sweetpotato whitefly (Bemisia tabaci) sampled in cotton fields of central Arizona. We studied the B biotype of B. tabaci, also known as the Asia Minor-Middle East 1 species, which is a key pest of cotton and other crops in Arizona and worldwide (16). The insect growth regulators pyriproxyfen (a juvenile hormone analog) and buprofezin (a chitin synthesis inhibitor) are selective insecticides that have been used for whitefly control in Arizona cotton (Gossypium spp.) since 1996 (17, 18). A single application of either insecticide on cotton when B. tabaci populations start to increase has substantially reduced sprays of broad-spectrum insecticides, helped to conserve natural enemies, and restored farmers &apos; profits (18, 19). To deter rapid evolution of resistance, farmers in Arizona generally have not used pyriproxyfen to control B. tabaci on crops other than cotton Although B. tabaci is polyphagous, few whitefly crops other than cotton are available in central Arizona from June to September, when pyriproxyfen is sprayed on cotton. In principle, crops that could act as refuges include spring melons (Citrullus lanatus and Cucumis melo), alfalfa (Medicago sativa) and cotton not treated with pyriproxyfen (referred to hereafter as untreated cotton). B. tabac