6,356 research outputs found
Four Love Poems from \u3cem\u3eOne Hundred Poems of the Dharma Gate\u3c/em\u3e by Jakuzen
Translated from Japanese and Chinese by Stephen D. Miller and Patrick Donnell
The Outer Limits of Galaxy Clusters: Observations to the Virial Radius with Suzaku, XMM, and Chandra
The outskirts of galaxy clusters, near the virial radius, remain relatively
unexplored territory and yet are vital to our understanding of cluster growth,
structure, and mass. In this presentation, we show the first results from a
program to constrain the state of the outer intracluster medium (ICM) in a
large sample of galaxy clusters, exploiting the strengths of three
complementary X-ray observatories: Suzaku (low, stable background), XMM-Newton
(high sensitivity), and Chandra (good spatial resolution). By carefully
combining observations from the cluster core to beyond r_200, we are able to
identify and reduce systematic uncertainties that would impede our spatial and
spectral analysis using a single telescope. Our sample comprises nine clusters
at z ~ 0.1-0.2 fully covered in azimuth to beyond r_200, and our analysis
indicates that the ICM is not in hydrostatic equilibrium in the cluster
outskirts, where we see clear azimuthal variations in temperature and surface
brightness. In one of the clusters, we are able to measure the diffuse X-ray
emission well beyond r_200, and we find that the entropy profile and the gas
fraction are consistent with expectations from theory and numerical
simulations. These results stand in contrast to recent studies which point to
gas clumping in the outskirts; the extent to which differences of cluster
environment or instrumental effects factor in this difference remains unclear.
From a broader perspective, this project will produce a sizeable fiducial data
set for detailed comparison with high-resolution numerical simulations.Comment: 8 pages, 6 figures. To appear in the proceedings of the Suzaku 2011
Conference, "Exploring the X-ray Universe: Suzaku and Beyond.
The Management and Security Expert (MASE)
The Management and Security Expert (MASE) is a distributed expert system that monitors the operating systems and applications of a network. It is capable of gleaning the information provided by the different operating systems in order to optimize hardware and software performance; recognize potential hardware and/or software failure, and either repair the problem before it becomes an emergency, or notify the systems manager of the problem; and monitor applications and known security holes for indications of an intruder or virus. MASE can eradicate much of the guess work of system management
Visualization of diffusion limited antimicrobial peptide attack on supported lipid membranes
Understanding the mechanism of action of antimicrobial peptides (AMP) is fundamental to the development and design of peptide based antimicrobials. Utilizing fast-scan atomic force microscopy (AFM) we detail the attack of an AMP on both prototypical prokaryotic (DOPC:DOPG) and eukaryotic (DOPC:DOPE) model lipid membranes on the nanoscale and in real time. Previously shown to have a favourable therapeutic index, we study Smp43, an AMP with a helical-hinge-helical topology isolated from the venom of the North African scorpion Scorpio maurus palmatus. We observe the dynamic formation of highly branched defects being supported by 2D diffusion models and further experimental data from liposome leakage assays and quartz crystal microbalance-dissipation (QCM-D) analysis, we propose that Smp43 disrupts these membranes via a common mechanism, which we have termed ‘diffusion limited disruption’ that encompasses elements of both the carpet model and the expanding pore mechanism
Lipid coated liquid crystal droplets for the on-chip detection of antimicrobial peptides
We describe a novel biosensor based on phospholipid-coated nematic liquid crystal (LC) droplets and demonstrate the detection of Smp43, a model antimicrobial peptide (AMP) from the venom of North African scorpion Scorpio maurus palmatus. Mono-disperse lipid-coated LC droplets of diameter 16.7 ± 0.2 μm were generated using PDMS microfluidic devices with a flow-focusing configuration and were the target for AMPs. The droplets were trapped in a bespoke microfluidic trap structure and were simultaneously treated with Smp43 at gradient concentrations in six different chambers. The disruption of the lipid monolayer by the Smp43 was detected (<6 μM) at concentrations well within its biologically active range, indicated by a dramatic change in the appearance of the droplets associated with the transition from a typical radial configuration to a bipolar configuration, which is readily observed by polarizing microscopy. This suggests the system has feasibility as a drug-discovery screening tool. Further, compared to previously reported LC droplet biosensors, this LC droplet biosensor with a lipid coating is more biologically relevant and its ease of use in detecting membrane-related biological processes and interactions has the potential for development as a reliable, low-cost and disposable point of care diagnostic tool
Extended X-Ray Emission from QSOs
We report Chandra ACIS observations of the fields of 4 QSOs showing strong
extended optical emission-line regions. Two of these show no evidence for
significant extended X-ray emission. The remaining two fields, those of 3C
249.1 and 4C 37.43, show discrete (but resolved) X-ray sources at distances
ranging from ~10 to ~40 kpc from the nucleus. In addition, 4C 37.43 also may
show a region of diffuse X-ray emission extending out to ~65 kpc and centered
on the QSO. It has been suggested that extended emission-line regions such as
these may originate in the cooling of a hot intragroup medium. We do not detect
a general extended medium in any of our fields, and the upper limits we can
place on its presence indicate cooling times of at least a few 10^9 years. The
discrete X-ray emission sources we detect cannot be explained as the X-ray jets
frequently seen associated with radio-loud quasars, nor can they be due to
electron scattering of nuclear emission. The most plausible explanation is that
they result from high-speed shocks from galactic superwinds resulting either
from a starburst in the QSO host galaxy or from the activation of the QSO
itself. Evidence from densities and velocities found from studies of the
extended optical emission around QSOs also supports this interpretation.Comment: Accepted by ApJ. 9 pages including 5 figure
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