743 research outputs found
Clustering of i-dropout galaxies at z=6 in GOODS and the UDF
We measured the angular clustering at z~6 from a large sample of i-dropout
galaxies (293 with z<27.5 from GOODS and 95 with z<29.0 from the UDF). Our
largest and most complete subsample (having L>0.5L*) shows the presence of
clustering at 94% significance. For this sample we derive a (co-moving)
correlation length of r_0=4.5^{+2.1}_{-3.2} h_{72}^{-1} Mpc and bias
b=4.1^{+1.5}_{-2.6}, using an accurate model for the redshift distribution. No
clustering could be detected in the much deeper but significantly smaller UDF,
yielding b<4.4 (1 sigma). We compare our findings to Lyman break galaxies at
z=3-5 at a fixed luminosity. Our best estimate of the bias parameter implies
that i-dropouts are hosted by dark matter halos having masses of ~10^11 M_sun,
similar to that of V-dropouts at z~5. We evaluate a recent claim that at z>5
star formation might have occurred more efficiently compared to that at z=3-4.
This may provide an explanation for the very mild evolution observed in the UV
luminosity density between z=6 and z=3. Although our results are consistent
with such a scenario, the errors are too large to find conclusive evidence for
this.Comment: minor changes to match published versio
Vitamin D status and the risk of type 2 diabetes: the Melbourne Collaborative Cohort Study
Aims: Inverse associations between vitamin D status and risk of type 2 diabetes observed in epidemiological studies could be biased by confounding and reverse causality. We investigated the prospective association between vitamin D status and type 2 diabetes and the possible role of reverse causality. Methods: We conducted a case-cohort study within the Melbourne Collaborative Cohort Study (MCCS), including a random sample of 628 participants who developed diabetes and a sex-stratified random sample of the cohort (n=1,884). Concentration of 25-hydroxyvitamin D (25(OH)D) was measured using liquid chromatography-tandem mass spectrometry in samples collected at recruitment. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of type 2 diabetes for quartiles of 25(OH)D relative to the lowest quartile and per 25 nmol/L increase in 25(OH)D, adjusting for confounding variables. Results: The ORs for the highest versus lowest 25(OH)D quartile and per 25 nmol/L increase in 25(OH)D were 0.60 (95% CI: 0.44, 0.81) and 0.76 (95% CI: 0.63, 0.92; p=0.004), respectively. In participants who reported being in good/very good/excellent health approximately four years after recruitment, ORs for the highest versus lowest 25(OH)D quartile and per 25 nmol/L increase in 25(OH)D were 0.46 (95% CI: 0.29, 0.72) and 0.71 (95% CI: 0.56, 0.89; p=0.003), respectively. Conclusions: In this sample of middle-aged Australians, vitamin D status was inversely associated with the risk of type 2 diabetes, and this association did not appear to be explained by reverse causality
BBC2 and world cinema
© Edinburgh University Press. This article examines the origins of BBC2's reputation as a purveyor of films from around the world, exploring the significance and impact of the strand World Cinema (1965-74) and assessing the range and diversity of its offer. Foreign-language titles had been broadcast by the Corporation since before the Second World War, due partly to their ready availability at a time when Hollywood films were 'off limits', given the hostility of American (and British) film companies towards the new rival medium of television. During this early period, however, these continental films were not popular, undoubtedly due to the fact that subtitles were very difficult to read on small, low-definition television screens. BBC2, with its commitment to minority tastes and interests and its use of both the higher-definition 625-line UHF system and colour, was perfectly placed to revive and foster interest in world cinema. For those who urged broadcasters to adopt and maintain an enlightened film policy, World Cinema became exemplary, as a rare exception to the general rules in early television of editing for content or length, block buying (the practice of buying the rights to a mixed package of films in order to acquire certain gems) and haphazard scheduling. For a generation of cinephiles, World Cinema was a formative and educative experience. Particular attention is paid here to the first five years of World Cinema, which saw the strand give attention to a variety of 'New Waves' and relay experiences from behind the Iron Curtain and further afield
Vitamin D in the general population of young adults with autism in the Faroe Islands
Vitamin D deficiency has been proposed as a possible risk factor for developing autism spectrum disorder (ASD). 25-Hydroxyvitamin D3 (25(OH)D3) levels were examined in a cross-sectional population-based study in the Faroe Islands. The case group consisting of a total population cohort of 40 individuals with ASD (aged 15â24Â years) had significantly lower 25(OH)D3 than their 62 typically-developing siblings and their 77 parents, and also significantly lower than 40 healthy age and gender matched comparisons. There was a trend for males having lower 25(OH)D3 than females. Effects of age, month/season of birth, IQ, various subcategories of ASD and Autism Diagnostic Observation Schedule score were also investigated, however, no association was found. The very low 25(OH)D3 in the ASD group suggests some underlying pathogenic mechanism
Mycobacterium tuberculosis pks12 Produces a Novel Polyketide Presented by CD1c to T Cells
CD1c-mediated T cells are activated by a mycobacterial phospholipid antigen whose carbohydrate structure precisely corresponds to mammalian mannosyl ÎČ-1-phosphodolichol (MPD), but contains an unusual lipid moiety. Here, we show that this T cell antigen is a member of a family of branched, alkane lipids that vary in length (C30-34) and are produced by medically important mycobacteria such as M. tuberculosis and M. bovis Bacille-Calmette-Guerin. The alkane moiety distinguished these mycobacterial lipid antigens from mammalian MPDs and was necessary for activation of CD1c-restricted T cells, but could not be accounted for by any known lipid biosynthetic pathway. Metabolic labeling and mass spectrometric analyses suggested a mechanism for elongating lipids using alternating C2 and C3 units, rather than C5 isopentenyl pyrophosphate. Inspection of the M. tuberculosis genome identified one candidate gene, pks12, which was predicted to encode the largest protein in M. tuberculosis, consisting of 12 catalytic domains that correspond to key steps in the proposed pathway. Genetic deletion and complementation showed that Pks12 was necessary for antigen production, but did not affect synthesis of true isoprenols. These studies establish the genetic and enzymatic basis for a previously unknown type of polyketide, designated mycoketide, which contains a lipidic pathogen-associated molecular pattern
Has the COVID-19 pandemic influenced suicide rates differentially according to socioeconomic indices and ethnicity? More evidence is needed globally
Abstract The COVID-19 pandemic has harmed many people's mental health globally. Whilst the evidence generated thus far from high-income countries regarding the pandemic's impact on suicide rates is generally reassuring, we know little about its influence on this outcome in lower- and middle-income countries or among marginalised and disadvantaged people. There are some signals for concern regarding the pandemic's potentially unequal impact on suicide rates, with some of the affected demographic subgroups and regions being at elevated risk before the pandemic began. However, the evidence-base for this topic is currently sparse, and studies conducted to date have generally not taken account of pre-pandemic temporal trends. The collection of accurate, complete and comparable data on suicide rate trends in ethnic minority and low-income groups should be prioritised. The vulnerability of low-income groups will likely be exacerbated further by the current energy supply and cost-of-living crises in many countries. It is therefore crucial that reassuring messaging highlighting the stability of suicide rates during the pandemic does not lead to complacency among policymakers.</jats:p
The unusual NIV]-emitter galaxy GDS J033218.92-275302.7: star formation or AGN-driven winds from a massive galaxy at z=5.56
Aims: We investigate the nature of the source GDS J033218.92-275302.7at
redshift ~ 5.56. Methods: The SED of the source is well sampled by 16 bands
photometry, from UV-optical, near infrared and mid-infrared (MID-IR).The
detection of signal in the MID-IR Spitzer/IRAC bands 5.8, 8.0 um -- where the
nebular emission contribution is less effective -- suggests the presence of a
Balmer break, signature of an underlying stellar population formed at earlier
epochs. The optical spectrum shows a clear Lya emission line together with
semi-forbidden NIV] 1483.3-1486.5 also in emission. Results: From the SED
fitting and the Lya modelling it turns out that the source seems to have an
evolved component with stellar mass of ~5 x10^(10) Msolar and age ~ 0.4 Gyrs,
and a young component with an age of ~ 0.01 Gyrs and SFR in the range of 30-200
Msolar yr^(-1). The limits on the effective radius derived from the ACS/z850
and VLT/Ks bands indicate that this galaxy is denser than the local ones with
similar mass. A relatively high nebular gas column density is favored from the
Lya line modelling (NHI>=10^(21) cm^(-2)). A vigorous outflow (~ 450 km/s) has
been measured from the optical spectrum,consistent with the Lya modelling. From
ACS observations it turns out that the region emitting Lya photons is spatially
compact and of the same order of the effective radius estimated at the ~1400A
rest-frame wavelength, whose emission is dominated by the stellar continuum
and/or AGN. The gas is blown out from the central region,but given the mass of
the galaxy it is uncertain whether it will pollute the IGM to large distances.
We argue that a burst of star formation in a dense gas environment is active
(possibly containing hot and massive stars and/or a low luminosity AGN),
superimposed to an already formed fraction of stellar mass (abridged).Comment: 13 pages, 9 figures (published on A&A). Here replaced with a typo
fixed in the footnote of Sect. 4.2 and with four updated references. Results
unchange
Spitzer Observations of Massive Red Galaxies at High Redshift
We investigate the properties of massive galaxies at z=1-3.5 using HST
observations, ground-based near-IR imaging, and Spitzer Space Telescope
observations at 3-24 micron. We identify 153 distant red galaxies (DRGs) with
J-K > 2.3 mag (Vega) in the southern GOODS field. This sample is approximately
complete in stellar mass for passively evolving galaxies above 10^11 solar
masses and z < 3. The galaxies identified by this selection are roughly split
between objects whose optical and near-IR rest-frame light is dominated by
evolved stars combined with ongoing star formation, and galaxies whose light is
dominated by heavily reddened starbursts. Very few of the galaxies (< 10%) have
no indication of current star formation. Using SFR estimates that include the
reradiated IR emission, the DRGs at z=1.5-3 with stellar masses > 10^11 solar
masses have specific SFRs (SFRs per unit stellar mass) ranging from 0.2 to 10
Gyr^-1, with a mean value of ~2.4 Gyr^-1. The DRGs with stellar masses > 10^11
solar masses and 1.5 < z < 3 have integrated specific SFRs greater the global
value over all galaxies. In contrast, we find that galaxies at z = 0.3-0.75
with these stellar masses have integrated specific SFRs less than the global
value, and more than an order of magnitude lower than that for massive DRGs at
z = 1.5-3. At z < 1, lower-mass galaxies dominate the overall cosmic mass
assembly. This suggests that the bulk of star formation in massive galaxies
occurs at early cosmic epochs and is largely complete by z~1.5. [Abridged]Comment: Accepted for publication in the Astrophysical Journal. 25 pages, 14
figure
Attentional Processing in C57BL/6J Mice Exposed to Developmental Vitamin D Deficiency
Epidemiological evidence suggests that Developmental Vitamin D (DVD) deficiency is associated with an increased risk of schizophrenia. DVD deficiency in mice is associated with altered behaviour, however there has been no detailed investigation of cognitive behaviours in DVD-deficient mice. The aim of this study was to determine the effect of DVD deficiency on a range of cognitive tasks assessing attentional processing in C57BL/6J mice. DVD deficiency was established by feeding female C57BL/6J mice a vitamin D-deficient diet from four weeks of age. After six weeks on the diet, vitamin D-deficient and control females were mated with vitamin D-normal males and upon birth of the pups, all dams were returned to a diet containing vitamin D. The adult offspring were tested on a range of cognitive behavioural tests, including the five-choice serial reaction task (5C-SRT) and five-choice continuous performance test (5C-CPT), as well as latent inhibition using a fear conditioning paradigm. DVD deficiency was not associated with altered attentional performance on the 5C-SRT. In the 5C-CPT DVD-deficient male mice exhibited an impairment in inhibiting repetitive responses by making more perseverative responses, with no changes in premature or false alarm responding. DVD deficiency did not affect the acquisition or retention of cued fear conditioning, nor did it affect the expression of latent inhibition using a fear conditioning paradigm. DVD-deficient mice exhibited no major impairments in any of the cognitive domains tested. However, impairments in perseverative responding in DVD-deficient mice may indicate that these animals have specific alterations in systems governing compulsive or reward-seeking behaviour
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