1,527 research outputs found
CO map and steep Kennicutt-Schmidt relation in the extended UV disk of M63
Results from the UV satellite GALEX revealed large extensions of disks in
some nearby spiral galaxies, extending out to 3 to 4 times the isophotal
radius, r25. M63 is a remarkable example of a spiral galaxy with one of the
most extended UV disks, so it offers the opportunity to search for the
molecular gas and characterize the star formation in outer disk regions as
revealed by the UV emission. We obtained deep CO(1-0) and CO(2-1) observations
on the IRAM 30 m telescope along the major axis of the M63 disk from the center
out to the galactocentric radius rgal = 1.6 r25 and over a bright UV region at
rgal = 1.36 r25. CO(1-0) is detected all along the M63 major axis out to r25,
and CO(2-1) is confined to rgal = 0.68 r25, which may betray lower excitation
temperatures in the outer disk. CO(1-0) is also detected in the external bright
UV region of M63. The radial profiles of the CO emission and of the Halpha, 24
micron, NUV and FUV star formation tracers and HI taken from the literature
show a severe drop with the galactocentric radius, such that beyond r25 they
are all absent with the exception of a faint UV emission and HI. The CO
emission detection in the external UV region, where the UV flux is higher than
the UV flux observed beyond r25, highlights a tight correlation between the CO
and UV fluxes, namely the amount of molecular gas and the intensity of star
formation. This external UV region is dominated by the atomic gas, suggesting
that HI is more likely the precursor of H2 rather than the product of UV
photodissociation. A broken power law needs to be invoked to describe the
Kennicutt-Schmidt (K-S) relation of M63 from the center of the galaxy out to
rgal = 1.36 r25. While all along the major axis out to r25 the K-S relation is
almost linear, in the external UV region the SFR regime is highly nonlinear and
characterized by a steep K-S relation and very low star formation efficiency.Comment: 12 pages, 8 figures, A&A accepte
Race, Ethnicity, Class, and School Dropouts: A Policy Perspective
The author presents a review of literature on conditions and circumstances that cause youth to drop out before finishing high school. The essay explains the key features of both cultural and structural theories of low academic performance, and the author argues these theories might profitably be fused in order to formulate effective dropout prevention/intervention policies. The author recommends use of the public health model for prevention and intervention and synthesizes the findings of three recent reports on effective dropout programs
EFFECT OF LIPID SUPPLEMENTATION ON RUMINAL EPITHELIAL MEMBRANE FATTY ACID COMPOSITION AND SHORT-CHAIN FATTY ACID ABSORPTION
Inclusion of lipid into diets increases the energy density and, depending on the type of lipid, may alter the fatty acid (FA) composition of tissues. Effects of dietary lipid on the digestive and immune function gastrointestinal tract have been evaluated, but effects on how dietary FA affect short-chain fatty acid (SCFA) absorption have not been investigated. The objective of this study was to determine the effect of dietary lipid supply and lipid type on the FA composition of the ruminal epithelium and absorption of SCFA. Twenty-one Holstein steers (194.1 ± 26.77 kg) were randomly assigned to the control (CON; 2.2% ether extract) or 1 of 2 lipid supplementation treatments (5% ether extract) utilizing saturated (SAT) or unsaturated sources and protected fat (UNSAT). After 30 d, calves were killed and samples of ruminal digesta, blood, and ruminal tissue were collected for FA analysis, and ruminal tissue was used for ex vivo measurement of acetate, propionate, and butyrate uptake and flux. Data were analyzed as a randomized complete block design using the mixed model of SAS with the fixed effect of treatment and the random effect of block. Calves fed SAT and UNSAT had greater (P < 0.01) concentration of total FA in ruminal fluid than CON. Feeding UNSAT increased the monounsaturated (P < 0.001) and polyunsaturated (P = 0.002) FA content in ruminal fluid relative to SAT and CON. The concentration of FA in the ruminal epithelium did not differ among treatments but there was a tendency (P = 0.069) for SAT calves to have more total FA and saturated FA (P = 0.053) than UNSAT. Moreover, UNSAT calves had greater (P = 0.006) omega-3 FA concentration in the ruminal epithelium than CON and SAT calves. Calves fed SAT had greater (P = 0.038) total propionate uptake with greater passive diffusion (P = 0.015) than CON and UNSAT. Calves fed SAT also had greater total butyrate uptake (P = 0.008). However, there were no differences for acetate, propionate, or butyrate flux among treatments. Thus, it is concluded that the provision of dietary lipid alters the FA composition of the ruminal epithelium and the uptake of propionate and butyrate with the greatest response when saturated lipid sources are provided
Comparison of price between a healthy and unhealthy diet in the Metropolitan Region, Chile
Indexación: Scopus; Scielo.Obesity remains a serious public health problem worldwide and in Latin America. The implementation of dietary guidelines is a strategy used in Chile and other Latin-American countries to promote healthy eating habits. Evidence from studies in US and Europe suggests that healthy eating patterns have a higher price compared to unhealthy food options. However, this has not been evaluated in Chile. Our goal was to compare the price and relation to energetic density of a healthy diet (HD) that follows the Chilean dietary with an unhealthy diet (UD) in the Metropolitan Region (MR), the most densely populated demographical division in Chile. The HD was obtained from the publication "Cocinasaludable: comoincluir 5 porciones de frutas y verduras por dia", a book of recipessponsored by theChilean governmentto promote intake of fruits and vegetables that fulfills the Chilean dietary guidelines. The UD was obtained by replacing recipesand food items from the DS with processed foods and recipes typically consumed in Chile. The price database was compiled from databases of the Chilean Government and on-line retailers at MR. The UD has higher energy density, has higher energy from fats and a lower healthy eating index compared with the HD. Price analysis indicated an inverse relation between caloric density and price for food groups and that the UD has an overall lower price compared to the HD. Our results suggest that the higher price of a HD in compliance with the Chilean dietary guidelines could hinder their implementation in the MR, and the transition towards healthy eating habits among its population.http://www.scielo.org.ve/scielo.php?script=sci_arttext&pid=S0004-0622201600040000
Kinematics of disk galaxies in (proto-)clusters at z=1.5
We observed star-forming galaxies at z~1.5 selected from the HyperSuprimeCam
Subaru Strategic Program. The galaxies are part of two significant
overdensities of [OII] emitters identified via narrow-band imaging and
photometric redshifts from grizy photometry. We used VLT/KMOS to carry out
Halpha integral field spectroscopy of 46 galaxies in total. Ionized gas maps,
star formation rates and velocity fields were derived from the Halpha emission
line. We quantified morphological and kinematical asymmetries to test for
potential gravitational (e.g. galaxy-galaxy) or hydrodynamical (e.g.
ram-pressure) interactions. Halpha emission was detected in 36 targets. 34 of
the galaxies are members of two (proto-)clusters at z=1.47, confirming our
selection strategy to be highly efficient. By fitting model velocity fields to
the observed ones, we determined the intrinsic maximum rotation velocity Vmax
of 14 galaxies. Utilizing the luminosity-velocity (Tully-Fisher) relation, we
find that these galaxies are more luminous than their local counterparts of
similar mass by up to ~4 mag in the rest-frame B-band. In contrast to field
galaxies at z<1, the offsets of the z~1.5 (proto-)cluster galaxies from the
local Tully-Fisher relation are not correlated with their star formation rates
but with the ratio between Vmax and gas velocity dispersion sigma_g. This
probably reflects that, as is observed in the field at similar redshifts, fewer
disks have settled to purely rotational kinematics and high Vmax/sigma_g
ratios. Due to relatively low galaxy velocity dispersions (sigma_v < 400 km/s)
of the (proto-)clusters, gravitational interactions likely are more efficient,
resulting in higher kinematical asymmetries, than in present-day clusters.
(abbr.)Comment: Accepted for publication in A&A. 11 pages, 8 figures, 1 tabl
Multiwavelength Study of NGC 281 Region
We present a multiwavelength study of the NGC 281 complex which contains the
young cluster IC 1590 at the center, using deep wide-field optical UBVI_c
photometry, slitless spectroscopy along with archival data sets in the
near-infrared (NIR) and X-ray. The extent of IC 1590 is estimated to be ~6.5
pc. The cluster region shows a relatively small amount of differential
reddening. The majority of the identified young stellar objects (YSOs) are low
mass PMS stars having age <1-2 Myr and mass 0.5-3.5 M_\odot. The slope (\Gamma)
of the mass function for IC 1590, in the mass range 2 < M/M_\odot \le 54, is
found to be -1.11+-0.15. The slope of the K-band luminosity function
(0.37+-0.07) is similar to the average value (~0.4) reported for young
clusters. The distribution of gas and dust obtained from the IRAS, CO and radio
maps indicates clumpy structures around the central cluster. The radial
distribution of the young stellar objects, their ages, \Delta(H-K) NIR-excess,
and the fraction of classical T Tauri stars suggest triggered star formation at
the periphery of the cluster region. However, deeper optical, NIR and MIR
observations are needed to have a conclusive view of star formation scenario in
the region. The properties of the Class 0/I and Class II sources detected by
using the Spitzer mid-infrared observations indicate that a majority of the
Class II sources are X-ray emitting stars, whereas X-ray emission is absent
from the Class 0/I sources. The spatial distribution of Class 0/I and Class II
sources reveals the presence of three sub-clusters in the NGC 281 West region.Comment: 29 pages, 21 figures and 11 tables, Accepted for the publication in
PAS
Wnt/β-catenin signaling stimulates the expression and synaptic clustering of the autism-associated Neuroligin 3 gene
Indexación: Scopus.Synaptic abnormalities have been described in individuals with autism spectrum disorders (ASD). The cell-adhesion molecule Neuroligin-3 (Nlgn3) has an essential role in the function and maturation of synapses and NLGN3 ASD-associated mutations disrupt hippocampal and cortical function. Here we show that Wnt/β-catenin signaling increases Nlgn3 mRNA and protein levels in HT22 mouse hippocampal cells and primary cultures of rat hippocampal neurons. We characterized the activity of mouse and rat Nlgn3 promoter constructs containing conserved putative T-cell factor/lymphoid enhancing factor (TCF/LEF)-binding elements (TBE) and found that their activity is significantly augmented in Wnt/β-catenin cell reporter assays. Chromatin immunoprecipitation (ChIP) assays and site-directed mutagenesis experiments revealed that endogenous β-catenin binds to novel TBE consensus sequences in the Nlgn3 promoter. Moreover, activation of the signaling cascade increased Nlgn3 clustering and co-localization with the scaffold PSD-95 protein in dendritic processes of primary neurons. Our results directly link Wnt/β-catenin signaling to the transcription of the Nlgn3 gene and support a functional role for the signaling pathway in the dysregulation of excitatory/inhibitory neuronal activity, as is observed in animal models of ASD.https://www.nature.com/articles/s41398-018-0093-y.pd
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
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