389 research outputs found
Star Formation in Massive Protoclusters in the Monoceros OB1 Dark Cloud
We present far-infrared, submillimetre, and millimetre observations of bright
IRAS sources and outflows that are associated with massive CS clumps in the
Monoceros OB1 Dark Cloud. Individual star-forming cores are identified within
each clump. We show that combining submillimetre maps, obtained with SCUBA on
the JCMT, with HIRES-processed and modelled IRAS data is a powerful technique
that can be used to place better limits on individual source contributions to
the far-infrared flux in clustered regions. Three previously categorized "Class
I objects" are shown to consist of multiple sources in different evolutionary
stages. In each case, the IRAS point source dominates the flux at 12 and 25
microns. In two cases, the IRAS point source is not evident at submillimetre
wavelengths. The submillimetre sources contribute significantly to the 60 and
100 micron fluxes, dominating the flux in the 100 micron waveband. Using fluxes
derived from our technique, we present the spectral energy distribution and
physical parameters for an intermediate-mass Class 0 object in one of the
regions. Our new CO J=2-1 outflow maps of the three regions studied indicate
complex morphology suggestive of multiple driving sources. We discuss the
possible implications of our results for published correlations between outflow
momentum deposition rates and "source" luminosities, and for using these
derived properties to estimate the ratio of mass ejection rates to mass
accretion rates onto protostars.Comment: 12 pages, 11 gzipped gif figures, LaTex file and MNRAS style files,
accepted by MNRAS, v2: reference typos and author affiliation have been
correcte
Spitzer observations of NGC2264: The nature of the disk population
NGC2264 is a young cluster with a rich circumstellar disk population which
makes it an ideal target for studying the evolution of stellar clusters. Our
goal is to study its star formation history and to analyse the primordial disk
evolution of its members. The study presented is based on data obtained with
Spitzer IRAC and MIPS, combined with deep NIR ground-based FLAMINGOS imaging
and previously published optical data. We build NIR dust extinction maps of the
molecular cloud associated with the cluster, and determine it to have a mass of
2.1x10^3Msun above an Av of 7mag. Using a differential K_s-band luminosity
function of the cluster, we estimate the size of its population to be
1436242 members. The star formation efficiency is ~25%. We identify the
disk population: (i) optically thick inner disks, (ii) anaemic inner disks, and
(iii) disks with inner holes, or transition disks. We analyse the spatial
distribution of these sources and find that sources with thick disks segregate
into sub-clusterings, whereas sources with anaemic disks do not. Furthermore,
sources with anaemic disks are found to be unembedded (Av<3mag), whereas the
clustered sources with thick disks are still embedded within the parental
cloud. NGC2264 has undergone more than one star-forming event, where the
anaemic and extincted thick disk population appear to have formed in separate
episodes. We also find tentative evidence of triggered star-formation in the
Fox Fur Nebula. In terms of disk evolution, our findings support the emerging
disk evolution paradigm of two distinct evolutionary paths for primordial
optically thick disks: a homologous one where the disk emission decreases
uniformly at NIR and MIR wavelengths, and a radially differential one where the
emission from the inner region of the disk decreases more rapidly than from the
outer region (forming transition disks).Comment: accepted for publishing in A&
Grounding topologies for resilient, integrated composite electrical power systems for future aircraft applications
The upwards trend for the use of electrical power on state of the art more-electric aircraft (MEA) has resulted in a significant changes to the electrical power system (EPS) for these platforms due to increased use of DC, higher voltage and power levels, and decentralized architectures. A dual trend is the increasing use of carbon fibre reinforced polymer (CFRP) for aircraft structures, due to the superior mechanical properties of CFRP compared to metallic structures. However, the poorer electrical conductivity of CFRP results in the aircraft structure no longer being fully integrated with the electrical power system. There is a need to integrate these two systems to fully maximize the performance benefits of CFRP, and optimize the weight and volume of the electrical power system. A first step in this integration is to identify an appropriate fault management strategy, which enables the detection of higher resistance ground faults through CFRP. This includes the consideration of appropriate grounding topologies. This paper proposes the implementation of a high resistance grounding topology, which enables the detection and location of a fault via spectral analysis of the voltage across the grounding resistor. From this, implications for wider EPS and CFRP designs to enable the reduction in the use of bulky cable harnesses, providing the first step to CFRP becoming an integral part of the EPS, are discussed
Immune activation in irritable bowel syndrome: can neuroimmune interactions explain symptoms?
Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal (GI) tract characterized by pain or discomfort from the lower abdominal region, which is associated with altered bowel habit. Despite its prevalence, there is currently a lack of effective treatment options for patients. IBS has long been considered as a neurological condition resulting from alterations in the brain gut axis, but immunological alterations are increasingly reported in IBS patients, consistent with the hypothesis that there is a chronic, but low-grade, immune activation. Mediators released by immune cells act to either dampen or amplify the activity of GI nerves. Release of a number of these mediators correlates with symptoms of IBS, highlighting the importance of interactions between the immune and the nervous systems. Investigation of the role of microbiota in these interactions is in its early stages, but may provide many answers regarding the mechanisms underlying activation of the immune system in IBS. Identifying what the key changes in the GI immune system are in IBS and how these changes modulate viscerosensory nervous function is essential for the development of novel therapies for the underlying disorder.Patrick A. Hughes, Heddy Zola, Irmeli A. Penttila, L. Ashley Blackshaw, Jane M. Andrews, and Doreen Krumbiege
Neck circumference is associated with adipose tissue content in thigh skeletal muscle in overweight and obese premenopausal women
Neck circumference (NC) has been proposed as a simple and practical tool, independently associated
with cardiometabolic risk factors. However, the association of NC with inter-muscular adipose
tissue (IMAT) is still to be determined. We aimed to examine the association of NC with thigh IMAT,
and visceral adipose tissue (VAT) measured with computed tomography (CT) in overweight/obese
women. 142 premenopausal overweight and obese Caucasian women participated in this crosssectional study. NC was measured with an inextensible metallic tape above the thyroid cartilage
according to International Society for Advancement of Kinanthropometry protocol. Thigh IMAT and
VAT volumes were measured with a single cross-sectional CT. Regarding the covariates, fat mass (FM)
was assessed with dual-energy x-ray absorptiometry and physical activity was objectively measured
with accelerometry. NC was positively associated with thigh IMAT and VAT volumes (standardized
ÎČ coefcient: ÎČ=0.45, P-value= â€0.001, ÎČ=0.60, P=â€0.001; respectively), which persisted after
adjusting for age, height, overall FM or moderate-to-vigorous physical activity. Our fndings show that
NC is associated with thigh IMAT volume in overweight and obese premenopausal Caucasian women,
regardless of the amount of lower-body fatness. These results suggest underscoring the relevance of NC
as a marker of adipose tissue content in thigh skeletal muscle.Portuguese Foundation for Science and Technology
Sapiens 358007/99Oeiras City CouncilBecel PortugalRoche Pharmaceuticals PortugalCompal PortugalUniversity of Granada Plan Propio de Investigacion 2016 -Excellence actions: Unit of Excellence on Exercise and Health (UCEES)Junta de AndaluciaEuropean Union (EU)
SOMM17/6107/UGRFundacion Carolina
C.201657496
New Insights into Blastocystis spp.: A Potential Link with Irritable Bowel Syndrome
International audienceBlastocystis spp. belong to the phylum Stramenopila, a complex and heterogeneous evolutionary assemblage of heterotrophic and photosynthetic protozoa [1]. Interestingly, this is the only stramenopile living in the lower digestive tract of humans, and it also lives in other mammals, birds, reptiles, amphibians, and insects [1]. Even though isolates were reported to be morphologically indistinguishable, an extensive genetic variation among isolates from both humans and animals has been observed. Thirteen subtypes (ST1-ST13), with the first nine being found in humans, have been identified based on genes coding for the small-subunit ribosomal RNA [2]. Preferential repartition of STs exists among animals that appear to constitute the main reservoir for environmental dissemination and human contamination
A pseudospectral approach to the McWhorter and Sunada equation for two-phase flow in porous media with capillary pressure
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