832 research outputs found
A very deep Chandra observation of Abell 1795: The Cold Front and Cooling Wake
We present a new analysis of very deep Chandra observations of the galaxy
cluster Abell 1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to
resolve the thermodynamic structure of the Intracluster Medium (ICM) on length
scales of ~ 1 kpc near the cool core. We find several previously unresolved
structures, including a high pressure feature to the north of the BCG that
appears to arise from the bulk motion of Abell 1795's cool core. To the south
of the cool core, we find low temperature (~ 3 keV), diffuse ICM gas extending
for distances of ~ 50 kpc spatially coincident with previously identified
filaments of H-alpha emission. Gas at similar temperatures is also detected in
adjacent regions without any H-alpha emission. The X-ray gas coincident with
the H-alpha filament has been measured to be cooling spectroscopically at a
rate of ~ 1 Solar Masses/ yr, consistent with measurements of the star
formation rate in this region as inferred from UV observations, suggesting that
the star formation in this filament as inferred by its H and UV
emission can trace its origin to the rapid cooling of dense, X-ray emitting
gas. The H-alpha filament is not a unique site of cooler ICM, however, as ICM
at similar temperatures and even higher metallicities not cospatial with
H emission is observed just to the west of the H-alpha filament,
suggesting that it may have been uplifted by Abell 1795's central active
galaxy. Further simulations of cool core sloshing and AGN feedback operating in
concert with one another will be necessary to understand how such a dynamic
cool core region may have originated and why the H-alpha emission is so
localized with respect to the cool X-ray gas despite the evidence for a
catastrophic cooling flow.Comment: 14 Pages, 10 Figures, Resubmitted to ApJ after first referee report,
Higher Resolution Figures available upon reques
Rapid characterisation of large earthquakes by multiple seismic broadband arrays
An automatic procedure is presented to retrieve rupture parameters for large earthquakes along the Sunda arc subduction zone. The method is based on standard array analysis and broadband seismograms registered within 30°–100° epicentral distance. No assumptions on source mechanism are required. By means of semblance the coherency of <i>P</i> waveforms is analysed at separate large-aperture arrays. Waveforms are migrated to a 10°&times;10° wide source region to study the spatio-temporal evolution of earthquakes at each array. The multiplication of the semblance source maps resulting at each array increases resolution. Start, duration, extent, direction, and propagation velocity are obtained and published within 25 min after the onset of the event. First preliminary results can be obtained even within 16 min. Their rapid determination may improve the mitigation of the earthquake and tsunami hazard. Real-time application will provide rupture parameters to the GITEWS project (German Indonesian Tsunami Early Warning System). The method is applied to the two <i>M</i>8.0 Sumatra earthquakes on 12 September 2007, to the <i>M</i>7.4 Java earthquake on 2 September 2009, and to major subduction earthquakes that have occurred along Sumatra and Java since 2000. Obtained rupture parameters are most robust for the largest earthquakes with magnitudes <i>M</i>&ge;8. The results indicate that almost the entire seismogenic part of the subduction zone off the coast of Sumatra has been ruptured. Only the great Sumatra event in 2004 and the <i>M</i>7.7 Java event on 17 July 2006 could reach to or close to the surface at the trench. Otherwise, the rupturing was apparently confined to depths below 25 km. Major seismic gaps seem to remain off the coast of Padang and the southern tip of Sumatra
Parallelization of chip-based fluorescence immuno-assays with quantum-dot labelled beads
This paper presents an optical concept for the read-out of a parallel, bead-based fluorescence immunoassay conducted on a lab-on-a-disk platform. The reusable part of the modular setup comprises a detection unit featuring a single LED as light source, two emission-filters, and a color CCD-camera as standard components together with a spinning drive as actuation unit. The miniaturized lab-on-a-disk is devised as a disposable. In the read-out process of the parallel assay, beads are first identified by the color of incorporated quantum dots (QDs). Next, the reaction-specific fluorescence signal is quantified with FluoSpheres-labeled detection anti-bodies. To enable a fast and automated read-out, suitable algorithms have been implemented in this work. Based on this concept, we successfully demonstrated a Hepatitis-A assay on our disk-based lab-on-a-chip
The guinea pig ileum lacks the direct, high-potency, M2-muscarinic, contractile mechanism characteristic of the mouse ileum
We explored whether the M2 muscarinic receptor in the guinea pig ileum elicits a highly potent, direct-contractile response, like that from the M3 muscarinic receptor knockout mouse. First, we characterized the irreversible receptor-blocking activity of 4-DAMP mustard in ileum from muscarinic receptor knockout mice to verify its M3 selectivity. Then, we used 4-DAMP mustard to inactivate M3 responses in the guinea pig ileum to attempt to reveal direct, M2 receptor-mediated contractions. The muscarinic agonist, oxotremorine-M, elicited potent contractions in ileum from wild-type, M2 receptor knockout, and M3 receptor knockout mice characterized by negative log EC50 (pEC50) values ± SEM of 6.75 ± 0.03, 6.26 ± 0.05, and 6.99 ± 0.08, respectively. The corresponding Emax values in wild-type and M2 receptor knockout mice were approximately the same, but that in the M3 receptor knockout mouse was only 36% of wild type. Following 4-DAMP mustard treatment, the concentration–response curve of oxotremorine-M in wild-type ileum resembled that of the M3 knockout mouse in terms of its pEC50, Emax, and inhibition by selective muscarinic antagonists. Thus, 4-DAMP mustard treatment appears to inactivate M3 responses selectively and renders the muscarinic contractile behavior of the wild-type ileum similar to that of the M3 knockout mouse. Following 4-DAMP mustard treatment, the contractile response of the guinea pig ileum to oxotremorine-M exhibited low potency and a competitive-antagonism profile consistent with an M3 response. The guinea pig ileum, therefore, lacks a direct, highly potent, M2-contractile component but may have a direct, lower potency M2 component
CXC chemokines in angiogenesis
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141036/1/jlb0001.pd
Multipartite Entanglement and Frustration
Some features of the global entanglement of a composed quantum system can be
quantified in terms of the purity of a balanced bipartition, made up of half of
its subsystems. For the given bipartition, purity can always be minimized by
taking a suitable (pure) state. When many bipartitions are considered, the
requirement that purity be minimal for all bipartitions can engender conflicts
and frustration arises. This unearths an interesting link between frustration
and multipartite entanglement, defined as the average purity over all
(balanced) bipartitions.Comment: 15 pages, 7 figure
High-frequency seismic radiation from Maule earthquake (Mw 8.8, 2010 February 27) inferred from high-resolution backprojection analysis
The Maule earthquake (2010 February 27, Mw 8.8, Chile) broke the subduction megathrust along a previously locked segment. Based on an international aftershock deployment, catalogues of precisely located aftershocks have become available. Using 23 well-located aftershocks, we calibrate the classic teleseismic backprojection procedure to map the high-frequency seismic radiation emitted during the earthquake. The calibration corrects traveltimes in a standard earth model both with a static term specific to each station, and a ‘dynamic’ term specific to each combination of grid point and station. The second term has been interpolated over the whole slipping area by kriging, and is about an order of magnitude smaller than the static term. This procedure ensures that the teleseismic images of rupture development are properly located with respect to aftershocks recorded with local networks and does not depend on accurate hypocentre location of the main shock.
We track a bilateral rupture propagation lasting ∼160 s, with its dominant branch rupturing northeastwards at about 3 km s−1. The area of maximum energy emission is offset from the maximum coseismic slip but matches the zone where most plate interface aftershocks occur. Along dip, energy is preferentially released from two disconnected interface belts, and a distinct jump from the shallower belt to the deeper one is visible after about 20 s from the onset. However, both belts keep on being active until the end of the rupture. These belts approximately match the position of the interface aftershocks, which are split into two clusters of events at different depths, thus suggesting the existence of a repeated transition from stick-slip to creeping frictional regime
Brain stem tumors in children less than 3 months: Clinical and radiologic findings of a rare disease
\ua9 The Author(s) 2024.Purpose: Brain stem tumors in children < 3 months at diagnosis are extremely rare. Our aim is to study a retrospective cohort to improve the understanding of the disease course and guide patient management. Methods: This is a multicenter retrospective analysis across the European Society for Pediatric Oncology SIOP-E HGG/DIPG Working Group linked centers, including patients with a brainstem tumor diagnosed between 2009 and 2020 and aged < 3 months at diagnosis. Clinical data were collected, and imaging characteristics were analyzed blindly and independently by two neuroradiologists. Results: Five cases were identified. No patient received any therapy. The epicenter of two tumors was in the medulla oblongata alone and in the medulla oblongata and the pons in three. For patients with tumor in equal parts in the medulla oblongata and the pons (n = 3), the extension at diagnosis involved the spinal cord; for the two patients with the tumor epicenter in the medulla oblongata alone (n = 2), the extension at diagnosis included the pons (n = 2) and the spinal cord (n = 1). Biopsy was performed in one patient identifying a pilocytic astrocytoma. Two patients died. In one patient, autopsy revealed a high-grade glioma (case 3). Three survivors showed either spontaneous tumor regression (n = 2) or stable disease (n = 1). Survivors were followed up for 10, 7, and 0.6 years, respectively. One case had the typical imaging characteristics of a dorsal exophytic low-grade glioma. Conclusions: No patient fulfilled the radiologic criteria defining a high-grade glioma. Central neuroradiological review and biopsy may provide useful information regarding the patient management
ixpeobssim: a Simulation and Analysis Framework for the Imaging X-ray Polarimetry Explorer
ixpeobssim is a simulation and analysis framework, based on the Python
programming language and the associated scientific ecosystem, specifically
developed for the Imaging X-ray Polarimetry Explorer (IXPE). Given a source
model and the response functions of the telescopes, it is designed to produce
realistic simulated observations, in the form of event lists in FITS format,
containing a strict super-set of the information provided by standard IXPE
level-2 files. The core ixpeobssim simulation capabilities are complemented by
a full suite of post-processing applications, allowing for the implementation
of complex, polarization-aware analysis pipelines, and facilitating the
inter-operation with the standard visualization and analysis tools
traditionally in use by the X-ray community. We emphasize that, although a
significant part of the framework is specific to IXPE, the modular nature of
the underlying implementation makes it potentially straightforward to adapt it
to different missions with polarization capabilities.Comment: 12 pages, 6 figures. Accepted for publication on SoftwareX; source
code available at https://github.com/lucabaldini/ixpeobssi
Muscarinic receptor subtypes and signalling involved in the attenuation of isoprenaline-induced rat urinary bladder relaxation
β-Adrenoceptors are important mediators of smooth muscle relaxation in the urinary bladder, but the concomitant presence of a muscarinic agonist, e.g., carbachol, can attenuate relaxation responses by reducing potency and/or efficacy of β-adrenoceptor agonists such as isoprenaline. Therefore, the present study was designed to explore the subtypes and signalling pathways of muscarinic receptors involved in the attenuation of isoprenaline-induced isolated rat detrusor preparations using novel subtype-selective receptor ligands. In radioligand binding studies, we characterized BZI to be a M3-sparing muscarinic agonist, providing selective M2 stimulation in rat bladder, and THRX-182087 as a highly M2-selective antagonist. The use of BZI and of THRX-182087 in the presence of carbachol enabled experimental conditions with a selective stimulation of only M2 or M3 receptors, respectively. Confirming previous findings, carbachol attenuated isoprenaline-induced detrusor relaxation. M2-selective stimulation partly mimicked this attenuation, indicating that both M2 and M3 receptors are involved. During M3-selective stimulation, the attenuation of isoprenaline responses was reduced by the phospholipase C inhibitor U 73,122 but not by the protein kinase C inhibitor chelerythrine. We conclude that both M2 and M3 receptors contribute to attenuation of β-adrenoceptor-mediated relaxation of rat urinary bladder; the signal transduction pathway involved in the M3 component of this attenuation differs from that mediating direct contractile effects of M3 receptors
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