24,114 research outputs found
Spleen findings in drowning
A retrospective study of spleen findings in 42 victims of drowning and a comparison group of 42 cases of asphyxiation due to other causes (hanging, ligature strangulation and manual strangulation), that were matched for sex, age, body weight and build, was performed. Significantly smaller spleen weights (P < 0.05), spleen weight:body weight ratios (P < 0.01) and spleen weight:liver weight ratios (P < 0.01) were found in the victims of drowning. The difference in weight was 18%. A significant negative correlation between spleen weight and blood alcohol concentration was found in the study group (r = −0.44; P < 0.01), but not in the control group. The possibility that the findings are due to a stress reaction caused by hypoxia in the presence of cooling and an influence of alcohol on reflex mechanisms is discussed
Strangulation as the primary mechanism for shutting down star formation in galaxies
Local galaxies are broadly divided into two main classes, star-forming
(gas-rich) and quiescent (passive and gas-poor). The primary mechanism
responsible for quenching star formation in galaxies and transforming them into
quiescent and passive systems is still unclear. Sudden removal of gas through
outflows or stripping is one of the mechanisms often proposed. An alternative
mechanism is so-called "strangulation", in which the supply of cold gas to the
galaxy is halted. Here we report that the difference between quiescent and star
forming galaxies in terms of stellar metallicity (i.e. the fraction of metals
heavier than helium in stellar atmospheres) can be used to discriminate
efficiently between the two mechanisms. The analysis of the stellar metallicity
in local galaxies, from 26,000 spectra, clearly reveals that strangulation is
the primary mechanism responsible for quenching star formation, with a typical
timescale of 4 billion years, at least for local galaxies with a stellar mass
less than 10^11 solar masses. This result is further supported independently by
the stellar age difference between quiescent and star-forming galaxies, which
indicates that quiescent galaxies of less than 10^11 solar masses are on
average observed four billion years after quenching due to strangulation.Comment: Published in Nature on 14 May 2015 (
http://dx.doi.org/10.1038/nature14439
The roles of ram-pressure stripping and minor mergers in evolution of galaxies
We investigate environmental effects on evolution of bright cluster galaxies
in a Lambda-dominated cold dark matter universe using a combination of
dissipationless N-body simulations and a semi-analytic galaxy formation model.
We incorporate effects of ram-pressure stripping (RPS) and minor merger-induced
small starburst (minor burst) into our model. By considering minor burst,
observed morphology-radius relation is successfully reproduced. When we do not
consider minor burst, the RPS hardly increases the intermediate B/T population.
In addition, the RPS and minor burst are not important for colours or star
formation rates of galaxies in the cluster core if star formation time-scale is
properly chosen, because the star formation is sufficiently suppressed by
consumption of the cold gas. We also find that SF in bulge-dominated galaxies
is mainly terminated by starburst induced by major mergers in all environments.Comment: To appear in the proceedings of IAU colloq. No. 195, "Outskirts of
Galaxy Clusters: intense life in the suburbs", Torino, 12-16 March 2004, 5
pages, 2 figures, uses IAU macr
Properties of Galaxy Groups in the SDSS: II.- AGN Feedback and Star Formation Truncation
Successfully reproducing the galaxy luminosity function and the bimodality in
the galaxy distribution requires a mechanism that can truncate star formation
in massive haloes. Current models of galaxy formation consider two such
truncation mechanisms: strangulation, which acts on satellite galaxies, and AGN
feedback, which predominantly affects central galaxies. The efficiencies of
these processes set the blue fraction of galaxies as function of galaxy
luminosity and halo mass. In this paper we use a galaxy group catalogue
extracted from the Sloan Digital Sky Survey (SDSS) to determine these
fractions. To demonstrate the potential power of this data as a benchmark for
galaxy formation models, we compare the results to the semi-analytical model
for galaxy formation of Croton et al. (2006). Although this model accurately
fits the global statistics of the galaxy population, as well as the shape of
the conditional luminosity function, there are significant discrepancies when
the blue fraction of galaxies as a function of mass and luminosity is compared
between the observations and the model. In particular, the model predicts (i)
too many faint satellite galaxies in massive haloes, (ii) a blue fraction of
satellites that is much too low, and (iii) a blue fraction of centrals that is
too high and with an inverted luminosity dependence. In the same order, we
argue that these discrepancies owe to (i) the neglect of tidal stripping in the
semi-analytical model, (ii) the oversimplified treatment of strangulation, and
(iii) improper modeling of dust extinction and/or AGN feedback. The data
presented here will prove useful to test and calibrate future models of galaxy
formation and in particular to discriminate between various models for AGN
feedback and other star formation truncation mechanisms.Comment: 16 pages, 5 figures, submitted to MNRA
Cluster induced quenching of galaxies in the massive cluster XMMXCSJ2215.9-1738 at z~1.5 traced by enhanced metallicities inside half R200
(Abridged) We explore the massive cluster XMMXCSJ2215.9-1738 at z~1.5 with
KMOS spectroscopy of Halpha and [NII] covering a region that corresponds to
about one virial radius. Using published spectroscopic redshifts of 108
galaxies in and around the cluster we computed the location of galaxies in the
projected velocity vs. position phase-space to separate our cluster sample into
a virialized region of objects accreted longer ago (roughly inside half R200)
and a region of infalling galaxies. We measured oxygen abundances for ten
cluster galaxies with detected [NII] lines in the individual galaxy spectra and
compared the MZR of the galaxies inside half R200 with the infalling galaxies
and a field sample at similar redshifts. We find that the oxygen abundances of
individual z~1.5 star-forming cluster galaxies inside half R200 are comparable,
at the respective stellar mass, to the higher local SDSS metallicity values. We
find that the [NII]/Halpha line ratios inside half R200 are higher by 0.2 dex
and that the resultant metallicities of the galaxies in the inner part of the
cluster are higher by about 0.1 dex, at a given mass, than the metallicities of
infalling galaxies and of field galaxies at z~1.5. The enhanced metallicities
of cluster galaxies at z~1.5 inside half R200 indicate that the density of the
ICM in this massive cluster becomes high enough toward the cluster center such
that the ram pressure exceeds the restoring pressure of the hot gas reservoir
of cluster galaxies. This can remove the gas reservoir initiating quenching;
although the galaxies continue to form stars, albeit at slightly lower rates,
using the available cold gas in the disk which is not stripped.Comment: Accepted for publication in A&
Trouble in Toyland: The 26th Annual Survey of Toy Safety
Presents findings on toys that may pose choking hazards, are excessively loud, or contain lead, phthalates, or other toxins. Outlines federal standards and makes recommendations for consumers, policy makers, and the Consumer Product Safety Commission
CLASH-VLT: Strangulation of cluster galaxies in MACSJ0416.1-2403 as seen from their chemical enrichment
(abridged) We explore the Frontier Fields cluster MACS J0416.1-2403 at
z=0.3972 with VIMOS/VLT spectroscopy from the CLASH-VLT survey covering a
region which corresponds to almost three virial radii. We measure fluxes of 5
emission lines of 76 cluster members enabling us to unambiguously derive O/H
gas metallicities, and also SFRs from Halpha. For intermediate massses we find
a similar distribution of cluster and field galaxies in the MZR and mass vs.
sSFR diagrams. Bulge-dominated cluster galaxies have on average lower sSFRs and
higher O/Hs compared to their disk-dominated counterparts. We use the location
of galaxies in the projected velocity vs. position phase-space to separate our
cluster sample into a region of objects accreted longer time ago and a region
of recently accreted and infalling galaxies. We find a higher fraction of
accreted metal-rich galaxies (63%) compared to the fraction of 28% of
metal-rich galaxies in the infalling regions. Intermediate mass galaxies
falling into the cluster for the first time are found to be in agreement with
predictions of the fundamental metallicity relation. In contrast, for already
accreted star-forming galaxies of similar masses, we find on average
metallicities higher than predicted by the models. This trend is intensified
for accreted cluster galaxies of the lowest mass bin, that display
metallicities 2-3 times higher than predicted by models with primordial gas
inflow. Environmental effects therefore strongly influence gas regulations and
control gas metallicities of log(M/Msun)<10.2 (Salpeter IMF) cluster galaxies.
We also investigate chemical evolutionary paths of model galaxies with and
without inflow of gas showing that strangulation is needed to explain the
higher metallicities of accreted cluster galaxies. Our results favor a
strangulation scenario in which gas inflow stops for log(M/Msun)<10.2 galaxies
when accreted by the cluster.Comment: Version better matched to the published version, including table with
observed and derived quantities for the 76 cluster galaxie
Where do "red and dead" early-type void galaxies come from?
Void regions of the Universe offer a special environment for studying
cosmology and galaxy formation, which may expose weaknesses in our
understanding of these phenomena. Although galaxies in voids are observed to be
predominately gas rich, star forming and blue, a sub-population of bright red
void galaxies can also be found, whose star formation was shut down long ago.
Are the same processes that quench star formation in denser regions of the
Universe also at work in voids?
We compare the luminosity function of void galaxies in the 2dF Galaxy
Redshift Survey, to those from a galaxy formation model built on the Millennium
Simulation. We show that a global star formation suppression mechanism in the
form of low luminosity "radio mode" AGN heating is sufficient to reproduce the
observed population of void early-types. Radio mode heating is environment
independent other than its dependence on dark matter halo mass, where, above a
critical mass threshold of approximately M_vir~10^12.5 M_sun, gas cooling onto
the galaxy is suppressed and star formation subsequently fades. In the
Millennium Simulation, the void halo mass function is shifted with respect to
denser environments, but still maintains a high mass tail above this critical
threshold. In such void halos, radio mode heating remains efficient and red
galaxies are found; collectively these galaxies match the observed space
density without any modification to the model. Consequently, galaxies living in
vastly different large-scale environments but hosted by halos of similar mass
are predicted to have similar properties, consistent with observations.Comment: 6 pages, 3 figures, accepted MNRA
Descriptive Analysis of Sexual Assault Nurse Examinations in Anchorage: 1996-2004
This project examined the characteristics of 1,383 sexual assault victimizations recorded by sexual assault nurse examiners in Anchorage, Alaska from 1996 to 2004. The report documents the demographic characteristics of patients, pre-assault characteristics, assault characteristics, post-assault characteristics, exam characteristics and findings, suspect characteristics, and legal resolutions.National Institute of Justice, Office of Justice Programs, U.S. Department of Justice. Grant No. 2004-WB-GX-0003Index of Tables and Figures / Acknowledgments \ Executive Summary
Descriptive Analysis / Sexual Assaults in Anchorage: 1996-2004 / Sexual Assault Nurse Examinations / Purpose of this Study / Methodology / Sample and Data Limitations / Demographic Characteristics of Patients / Pre-Assault Characteristics / Assault Characteristics / Post-Assault Characteristics / Exam Characteristics and Findings / Suspect Characteristics / Legal Resolutions / Appendix A – Data Collection Instrumen
Intra-uterine fetal demise caused by amniotic band syndrome after standard amniocentesis
The amniotic band syndrome represents a prime example of exogenous disruption of an otherwise normal feta I development. It may be a sequel of invasive diagnostic procedures such as amniocentesis or fetal blood sampling. A 38-year-old gravida II, para II delivered a morphologically normal male stillborn at term. The pregnancy history had been unremarkable but for an early 2nd-trimester amniocentesis. Cause of the intra-uterine fetal demise was noted to be an amniotic band constricting the umbilical cord, An amniotic band is a rare but potentially fatal condition which may be induced by, e.g., invasive prenatal procedures. Such bands are not usually diagnosed prenatally; however, selected patients with augmented risk may profit from intensive ultrasound evaluation including Doppler studies. Copyright (C) 2000 S. Karger AG, Basel
- …
