10,884 research outputs found
High-temperature Hydrogen Chloride Releases from Mixtures of Sodium Chloride with Sulfates: Implications for the Chlorine-Mineralogy as Determined by the Sample Analysis at Mars Instrument on the Curiosity Rover in Gale Crater, Mars
Hydrogen chloride releases above 500 C occurred in several samples analyzed by the Sample Analysis at Mars (SAM) evolved gas analyzer on the Curiosity rover in Gale crater. These have been attributed to reactions between chlorides (original or from oxychlorine decomposition) and water. Some of these HCl releases that peaked below the melting temperature of common chlorides did not co-evolve with oxygen or water, and were not explained by laboratory analog work (Figure 1). Therefore, these HCl releases were not caused by MgCl2 or soley due to reactions between water and melting chlorides. The goal of this work was to explain the HCl releases that did not co-evolve with oxygen or water and occurred below the melting point of common chlorides, which have not been explained by previous laboratory analog work. This work specifically evaluates the role of evolved SO2 in the production of HCl
Nature and Nurture in Dark Matter Halos
Cosmological simulations consistently predict specific properties of dark
matter halos, but these have not yet led to a physical understanding that is
generally accepted. This is especially true for the central regions of these
structures. Recently two major themes have emerged. In one, the dark matter
halo is primarily a result of the sequential accretion of primordial structure
(ie `Nature'); while in the other, dynamical relaxation (ie `Nurture')
dominates at least in the central regions. Some relaxation is however required
in either mechanism. In this paper we accept the recently established
scale-free sub-structure of halos as an essential part of both mechanisms.
Consequently; a simple model for the central relaxation based on a self-similar
cascade of tidal interactions, is contrasted with a model based on the
accretion of adiabatically self-similar, primordial structure. We conclude that
a weak form of this relaxation is present in the simulations, but that is
normally described as the radial orbit instability.Comment: 25 pages, 3 figures, fig with parts 1 to d, fig 3 with parts a to
Game restocking and the introduction of sarcoptic mange in wild rabbit in north-eastern Spain
Implications of Halo Inside-out Growth on the X-Ray Properties of Nearby Galaxy Systems within the Preheating Scenario
We present an entirely analytic model for a preheated, polytropic
intergalactic medium in hydrostatic equilibrium within a NFW dark halo
potential in which the evolution of the halo structure between major merger
events proceeds inside-out by accretion. This model is used to explain, within
a standard CDM cosmogony, the observed X-ray properties of nearby
relaxed, non-cooling flow groups and clusters of galaxies. We find that our
preferred solution to the equilibrium equations produces scaling relations in
excellent agreement with observations, while simultaneously accounting for the
typical structural characteristics of the distribution of the diffuse baryons.
In the class of preheating models, ours stands out because it offers a unified
description of the intrahalo medium for galaxy systems with total masses above
\sm 2\times 10^{13}\msun, does not produce baryonic configurations with large
isentropic cores, and reproduces faithfully the observed behavior of the gas
entropy at large radii. All this is achieved with a moderate level of energy
injection of about half a keV, which can be easily accommodated within the
limits of the total energy released by the most commonly invoked feedback
mechanisms, as well as with a polytropic index of 1.2, consistent with both
many observational determinations and predictions from high-resolution
gas-dynamical simulations of non-cooling flow clusters. More interestingly, our
scheme offers a physical motivation for the adoption of this specific value of
the polytropic index, as it is the one that best ensures the conservation after
halo virialization of the balance between the total specific energies of the
gas and dark matter components for the full range of masses investigated.Comment: 18 pages, 11 figures, accepted for publication in the Astrophysical
Journa
PDB60 ASSOCIATION OF INADEQUATE METABOLIC CONTROL AND CO-MORBIDITIES AND HEALTH RESOURCE UTILIZATION IN PATIENTS WITH DIABETES MELLITUS IN A SPANISH POPULATION
IDCS J1426.5+3508: Cosmological implications of a massive, strong lensing cluster at Z = 1.75
The galaxy cluster IDCS J1426.5+3508 at z = 1.75 is the most massive galaxy
cluster yet discovered at z > 1.4 and the first cluster at this epoch for which
the Sunyaev-Zel'Dovich effect has been observed. In this paper we report on the
discovery with HST imaging of a giant arc associated with this cluster. The
curvature of the arc suggests that the lensing mass is nearly coincident with
the brightest cluster galaxy, and the color is consistent with the arc being a
star-forming galaxy. We compare the constraint on M200 based upon strong
lensing with Sunyaev-Zel'Dovich results, finding that the two are consistent if
the redshift of the arc is z > 3. Finally, we explore the cosmological
implications of this system, considering the likelihood of the existence of a
strongly lensing galaxy cluster at this epoch in an LCDM universe. While the
existence of the cluster itself can potentially be accomodated if one considers
the entire volume covered at this redshift by all current high-redshift cluster
surveys, the existence of this strongly lensed galaxy greatly exacerbates the
long-standing giant arc problem. For standard LCDM structure formation and
observed background field galaxy counts this lens system should not exist.
Specifically, there should be no giant arcs in the entire sky as bright in
F814W as the observed arc for clusters at z \geq 1.75, and only \sim 0.3 as
bright in F160W as the observed arc. If we relax the redshift constraint to
consider all clusters at z \geq 1.5, the expected number of giant arcs rises to
\sim15 in F160W, but the number of giant arcs of this brightness in F814W
remains zero. These arc statistic results are independent of the mass of IDCS
J1426.5+3508. We consider possible explanations for this discrepancy.Comment: 7 pages, 4 figures, Accepted to The Astrophysical Journa
Detection of vortex tubes in solar granulation from observations with Sunrise
We have investigated a time series of continuum intensity maps and
corresponding Dopplergrams of granulation in a very quiet solar region at the
disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board
the balloon-borne solar observatory Sunrise. We find that granules frequently
show substructure in the form of lanes composed of a leading bright rim and a
trailing dark edge, which move together from the boundary of a granule into the
granule itself. We find strikingly similar events in synthesized intensity maps
from an ab initio numerical simulation of solar surface convection. From cross
sections through the computational domain of the simulation, we conclude that
these `granular lanes' are the visible signature of (horizontally oriented)
vortex tubes. The characteristic optical appearance of vortex tubes at the
solar surface is explained. We propose that the observed vortex tubes may
represent only the large-scale end of a hierarchy of vortex tubes existing near
the solar surface.Comment: Astrophysical Journal Letters: Sunrise Special Issue, reveived 2010
June 16; accepted 2010 August
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