1,480 research outputs found
Lymphotoxins and cytomegalovirus cooperatively induce interferon-beta, establishing host-virus détente
Tumor necrosis factor (TNF)-related cytokines regulate cell death and survival and provide strong selective pressures for viruses, such as cytomegalovirus (CMV), to evolve counterstrategies in order to persist in immune-competent hosts. Signaling by the lymphotoxin (LT)-β receptor or TNF receptor-1, but not Fas or TRAIL receptors, inhibits the cytopathicity and replication of human CMV by a nonapoptotic, reversible process that requires nuclear factor κB (NF-κB)-dependent induction of interferon-β (IFN-β). Efficient induction of IFN-β requires virus infection and LT signaling, demonstrating the need for both host and viral factors in the curtailment of viral replication without cellular elimination. LTα-deficient mice and LTβR-Fc transgenic mice were profoundly susceptible to murine CMV infection. Together, these results reveal an essential and conserved role for LTs in establishing host defense to CMV
Disk-resolved spectral reflectance properties of Phobos from 0.3-3.2 micron: Preliminary integrated results from Phobos 2
The Phobos 2 mission provided multispectral observations of Phobos over a large wavelength range and with relatively high spectral resolution. Here, researchers integrate results from three multispectral detectors by determining the ultraviolet-visible near infrared spectral properties of color and brightness features recognized in VSK TV images. Researchers present evidence that there are two fundamental spectral units within the region of overlapping coverage by the detectors. They describe the units' spectral and reflectance properties and discuss the implications of these results for the composition of Phobos
3D-Laser-Scanning Technique Applied to Bulk Density Measurements of Apollo Lunar Samples
In order to better interpret gravimetric data from orbiters such as GRAIL and LRO to understand the subsurface composition and structure of the lunar crust, it is import to have a reliable database of the density and porosity of lunar materials. To this end, we have been surveying these physical properties in both lunar meteorites and Apollo lunar samples. To measure porosity, both grain density and bulk density are required. For bulk density, our group has historically utilized sub-mm bead immersion techniques extensively, though several factors have made this technique problematic for our work with Apollo samples. Samples allocated for measurement are often smaller than optimal for the technique, leading to large error bars. Also, for some samples we were required to use pure alumina beads instead of our usual glass beads. The alumina beads were subject to undesirable static effects, producing unreliable results. Other investigators have tested the use of 3d laser scanners on meteorites for measuring bulk volumes. Early work, though promising, was plagued with difficulties including poor response on dark or reflective surfaces, difficulty reproducing sharp edges, and large processing time for producing shape models. Due to progress in technology, however, laser scanners have improved considerably in recent years. We tested this technique on 27 lunar samples in the Apollo collection using a scanner at NASA Johnson Space Center. We found it to be reliable and more precise than beads, with the added benefit that it involves no direct contact with the sample, enabling the study of particularly friable samples for which bead immersion is not possibl
The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
The All-Sky Automated Survey for Supernovae (ASAS-SN) is working towards
imaging the entire visible sky every night to a depth of V~17 mag. The present
data covers the sky and spans ~2-5~years with ~100-400 epochs of observation.
The data should contain some ~1 million variable sources, and the ultimate goal
is to have a database of these observations publicly accessible. We describe
here a first step, a simple but unprecedented web interface
https://asas-sn.osu.edu/ that provides an up to date aperture photometry light
curve for any user-selected sky coordinate. Because the light curves are
produced in real time, this web tool is relatively slow and can only be used
for small samples of objects. However, it also imposes no selection bias on the
part of the ASAS-SN team, allowing the user to obtain a light curve for any
point on the celestial sphere. We present the tool, describe its capabilities,
limitations, and known issues, and provide a few illustrative examples.Comment: 8 pages, 9 figures, submitted to PAS
A dynamical model of surrogate reactions
A new dynamical model is developed to describe the whole process of surrogate
reactions; transfer of several nucleons at an initial stage, thermal
equilibration of residues leading to washing out of shell effects and decay of
populated compound nuclei are treated in a unified framework. Multi-dimensional
Langevin equations are employed to describe time-evolution of collective
coordinates with a time-dependent potential energy surface corresponding to
different stages of surrogate reactions. The new model is capable of
calculating spin distributions of the compound nuclei, one of the most
important quantity in the surrogate technique. Furthermore, various observables
of surrogate reactions can be calculated, e.g., energy and angular distribution
of ejectile, and mass distributions of fission fragments. These features are
important to assess validity of the proposed model itself, to understand
mechanisms of the surrogate reactions and to determine unknown parameters of
the model. It is found that spin distributions of compound nuclei produced in
O+U O+U and O+U
O+U reactions are equivalent and much less than
10, therefore satisfy conditions proposed by Chiba and Iwamoto (PRC 81,
044604(2010)) if they are used as a pair in the surrogate ratio method.Comment: 17 pages, 5 figure
UGPS J194310+183851 : an Unusual Optical and X-ray Faint Cataclysmic Variable?
©2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is the final published pdf, which was originally published at https://doi.org/10.1093/mnras/stac1718 Funding Information: We acknowledge the use of public data from the Swift data archive. We also acknowledge the use of the WHT: the William Herschel Telescope and its service programme are operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. We would like to thank the operations teams at both facilities for the quick and efficient observations. CM acknowledges support from the UK's Science and Technology Facilities Council (ST/S505419/1). NM and WJC are funded by University of Hertfordshire studentships; furthermore CM, PWL, NM, WJC, ZG, and JED recognize the computing infrastructure provided via STFC grant ST/R000905/1 at the University of Hertfordshire. JS acknowledges support from the P ackard F oundation and National Science Foundation grant AST-1714825. Portions of this work were performed while SJS held a NRC Research Associateship award at the Naval Research Laboratory. Work at the Naval Research Laboratory is supported by NASA DPR S-15633-Y. ZG acknowledges the financial support from ANID (CONICYT) through the FONDECYT project No. 3220029. Publisher Copyright: © 2022 The Author(s).The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared filters in the UKIDSS Galactic Plane Survey (UGPS) allows for the discovery of variability on the time-scale of minutes. We report on the nature of one such object, through the use of optical spectroscopy, time series photometry, and targeted X-ray observations. We propose that UGPS J194310.32+183851.8 is a magnetic cataclysmic variable star of novel character, probably featuring a longer than average spin period and an orbital period likely to be shorter than the period gap (i.e. Porb < 2 h). We reason that the star is likely a member of the short-period intermediate-polar subclass that exists below this period boundary, but with the additional feature that system's spectral energy distribution is fainter and redder than other members of the group.Peer reviewe
Working conditions, work-life conflict and wellbeing in UK prison officers: the role of affective rumination and detachment
Although prison officers experience the working conditions associated with work-life conflict, little research has explored this issue. This study draws upon the work-home resources model (ten Brummelhuis & Bakker, 2012) to investigate relationships between working conditions (demands and experiences of aggression) and time-based, strain-based and behavior-based work-life conflict in UK prison officers (n = 1,682). Associations between working conditions, work-life conflict, and emotional exhaustion were also examined. Two recovery behaviors (affective rumination and detachment) were considered as potential moderators of associations between working conditions and emotional exhaustion. High levels of all work-life conflict dimensions were found which were related to working conditions and emotional exhaustion. Some evidence was found that higher rumination and lower detachment exacerbated the positive association between both job demands and aggression and emotional exhaustion. The implications of the findings for the wellbeing and professional functioning of prison officers are discussed, together with key areas for future research
Passive sorting of asteroid material using solar radiation pressure
Understanding dust dynamics in asteroid environments is key for future science missions to asteroids and, in the long-term, also for asteroid exploitation. This paper proposes a novel way of manipulating asteroid material by means of solar radiation pressure (SRP). We envisage a method for passively sorting material as a function of its grain size where SRP is used as a passive in-situ ‘mass spec-trometer’. The analysis shows that this novel method allows an effective sorting of regolith material. This has immediate applications for sample return, and in-situ resource utilisation to separate different regolith particle sizes
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