5,389 research outputs found
The Distribution of ALFALFA Galaxies
The ALFALFA blind HI survey will enable a census of the distribution of
gas-rich galaxies in the local Universe. Sensitive to an HI mass of 10**7 solar
masses at the distance of the Virgo cluster, ALFALFA will probe the smallest
objects locally and provide a new consideration of near-field cosmology.
Additionally, with a larger, cosmologically significant sample volume and wider
bandwidth than previous blind surveys, a much larger number of detections in
each mass bin is possible, with adequate angular resolution to eliminate the
need for extensive follow-up observations. This increased sensitivity will
greatly enhance the utility of cosmological probles in HI. ALFALFA will
eventually measure the correlation function of HI selected galaxies in a large
local volume. The larger sample and volume size of the ALFALFA dataset will
also robustly measure the HI mass function (HIMF). Here, we present the
preliminary results on the distribution of local gas-rich galaxies from a first
ALFALFA catalog covering 540 deg**2.Comment: To appear in Proceedings of IAU Symp. Number 244, "Dark Galaxies and
Lost Baryons", June 2007, 2 pages including 1 figur
Contact-mediated control of radial migration of corneal epithelial cells
We thank Darrin Sheppard and other staff at the University of Aberdeen Medical Research Facility for specialist technical assistance. We thank Patsy D. Goast for overnight microscope monitoring. This work was performed under the Biotechnology and Bioscience Research Council Grant number BB/E015840/1 to JMC.Peer reviewedPublisher PD
Requirement of Pax6 for the integration of guidance cues in cell migration
Data accessibility. Cell trajectories data and a summary of directedness and angle values are deposited at Dryad: http://dx.doi.org/10.5061/dryad.53512. Funding MA was funded by an Alban International Research Studentship (code: E07D400602UY).Peer reviewedPublisher PD
The Clustering Characteristics of HI-Selected Galaxies from the 40% ALFALFA Survey
The 40% Arecibo Legacy Fast ALFA (ALFALFA) survey catalog (\alpha.40) of
approximately 10,150 HI-selected galaxies is used to analyze the clustering
properties of gas-rich galaxies. By employing the Landy-Szalay estimator and a
full covariance analysis for the two-point galaxy-galaxy correlation function,
we obtain the real-space correlation function and model it as a power law,
\xi(r) = (r/r_0)^(-\gamma), on scales less than 10 h^{-1} Mpc. As the largest
sample of blindly HI-selected galaxies to date, \alpha.40 provides detailed
understanding of the clustering of this population. We find \gamma = 1.51 +/-
0.09 and r_0 = 3.3 +0.3, -0.2 h^{-1} Mpc, reinforcing the understanding that
gas-rich galaxies represent the most weakly clustered galaxy population known;
we also observe a departure from a pure power law shape at intermediate scales,
as predicted in \Lambda CDM halo occupation distribution models. Furthermore,
we measure the bias parameter for the \alpha.40 galaxy sample and find that HI
galaxies are severely antibiased on small scales, but only weakly antibiased on
large scales. The robust measurement of the correlation function for gas-rich
galaxies obtained via the \alpha.40 sample constrains models of the
distribution of HI in simulated galaxies, and will be employed to better
understand the role of gas in environmentally-dependent galaxy evolution.Comment: 30 pages, 10 figures, accepted by Ap
Exogenous Amino Acids Regulate Trophectoderm Differentiation in the Mouse Blastocyst through an mTOR-Dependent Pathway
AbstractAt the late blastocyst stage, the epithelial trophectoderm cells of the mammalian embryo undergo a phenotypic change that allows them to invade into the uterine stroma and make contact with the maternal circulation. This step can be regulated in vitro by the availability of amino acids. Embryos cultured in defined medium lacking amino acids cannot form trophoblast cell outgrowths on fibronectin, an in vitro model of implantation, but remain viable for up to 3 days in culture and will form outgrowths when transferred into complete medium. The amino acid requirement is a developmentally regulated permissive event that occurs during a 4- to 8-h period at the early blastocyst stage. Amino acids affect spreading competence specifically by regulating the onset of protrusive activity and not the onset of integrin activation. Rapamycin, a specific inhibitor of the kinase mTOR/FRAP/RAFT1, blocks amino acid stimulation of embryo outgrowth, demonstrating that mTOR is required for the initiation of trophectoderm protrusive activity. Inhibition of global protein translation with cycloheximide also inhibits amino acid-dependent signals, suggesting that mTOR regulates the translation of proteins required for trophoblast differentiation. Our data suggest that mTOR activity has a developmental regulatory function in trophectoderm differentiation that may serve to coordinate embryo and uterus at the time of implantation
Comparison of Subjective Responses to Oral and Intravenous Alcohol Administration under Similar Systemic Exposures
Objective
To test whether an individual's subjective responses to alcohol are similar when the breath alcohol concentration (BrAC) trajectory resulting from oral administration is matched by intravenous administration.
Background
Individuals perceive the effects of alcohol differently, and the variation is commonly used in research assessing the risk for developing an alcohol use disorder. Such research is supported by both oral and intravenous alcohol administration techniques, and any differences attributable to the route employed should be understood.
Methods
We conducted a 2‐session, within‐subject study in 44 young adult, healthy, non‐dependent drinkers (22 females and 22 males). In the first session, subjects ingested a dose of alcohol which was individually calculated, on the basis of total body water, to yield a peak BrAC near 80 mg/dl, and the resulting BrAC trajectory was recorded. A few days later, subjects received an intravenous alcohol infusion rate profile, pre‐computed to replicate each individual's oral alcohol BrAC trajectory. In both sessions, we assessed 4 subjective responses to alcohol: SEDATION, SIMULATION, INTOXICATION, and HIGH; at baseline and frequently for 4 hours. We compared the individuals’ baseline‐corrected responses at peak BrAC and at half‐peak BrAC on both the ascending and descending limbs. We also computed and compared Pearson‐product moment correlations of responses by route of administration, the Mellanby measure of acute adaptation to alcohol, and the area under the entire response curve for each subjective response.
Results
No significant differences in any measure could be attributed to the route of alcohol administration. Eleven of 12 response comparisons were significantly correlated across the routes of alcohol administration, with 9 surviving correction for multiple measures, as did the Mellanby effect and area under the response curve correlations.
Conclusion
The route of alcohol administration has a minimal effect on subjective responses to alcohol when an individual's BrAC exposure profiles are similar
Doppler Radar for the Extraction of Biomechanical Parameters in Gait Analysis
The applicability of Doppler radar for gait analysis is investigated by
quantitatively comparing the measured biomechanical parameters to those
obtained using motion capturing and ground reaction forces. Nineteen
individuals walked on a treadmill at two different speeds, where a radar system
was positioned in front of or behind the subject. The right knee angle was
confined by an adjustable orthosis in five different degrees. Eleven gait
parameters are extracted from radar micro-Doppler signatures. Here, new methods
for obtaining the velocities of individual lower limb joints are proposed.
Further, a new method to extract individual leg flight times from radar data is
introduced. Based on radar data, five spatiotemporal parameters related to
rhythm and pace could reliably be extracted. Further, for most of the
considered conditions, three kinematic parameters could accurately be measured.
The radar-based stance and flight time measurements rely on the correct
detection of the time instant of maximal knee velocity during the gait cycle.
This time instant is reliably detected when the radar has a back view, but is
underestimated when the radar is positioned in front of the subject. The
results validate the applicability of Doppler radar to accurately measure a
variety of medically relevant gait parameters. Radar has the potential to
unobtrusively diagnose changes in gait, e.g., to design training in prevention
and rehabilitation. As contact-less and privacy-preserving sensor, radar
presents a viable technology to supplement existing gait analysis tools for
long-term in-home examinations.Comment: 13 pages, 9 figures, 2 tables, accepted for publication in the IEEE
Journal of Biomedical and Health Informatics (J-BHI
A potential library for primary MFL pedagogy: the case of Young Pathfinders
As readers of this journal will know very well, 2010 will see all KS2 (ages 7-11) pupils in England entitled to learn a modern foreign language in normal curriculum time. This development of the commitment to primary language learning should provide an excellent opportunity and experience for pupils, whilst at the same time requiring some radical changes for many teachers, schools and much of the wider language learning community.
Recent research has indicated general trends suggesting an increase in primary languages already, in anticipation of this development and even beforehand. One of the most recent studies indicates that 43% of primary children currently learn a foreign language at KS2, either in class or as an extra-curricular activity, although the extent of this learning varies considerably (Driscoll, Jones and Macrory, 2004). It has also been suggested (Muijs et al, 2005) that there are certain aspects of the process that will be particularly demanding if the challenge of providing this entitlement are to be met
Competitive and Information Effects of Cross‐Border Stock Listings
We examine the effect of 269 cross-border listings on rivals in the listing and domestic markets and find that U.S. rivals experience significant gains whereas domestic rivals do not. Both competitive and information effects are important in explaining the reaction of U.S. rivals. Regarding the competitive effects, the reaction of rivals is less favorable when listings originate in developed countries and more favorable when listing firms do not have prior operating presence in the United States. Regarding the information effects, the reaction is less favorable when listings are combined with equity offerings and more favorable when the listing is the first to occur within an industry
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Reduced Visual Cortex Gray Matter Volume and Thickness in Young Adults Who Witnessed Domestic Violence during Childhood
Exposure to interparental violence is associated with negative outcomes, such as depression, post-traumatic stress disorder and reduced cognitive abilities. However, little is known about the potential effects of witnessing domestic violence during childhood on gray matter volume (GMV) or cortical thickness. High-resolution 3.0 T volumetric scans (Siemens Trio Scanner) were obtained on 52 subjects (18–25 years) including 22 (6 males/16 females) with a history of visually witnessing episodes of domestic violence, and 30 (8 males/22 females) unexposed control subjects, with neither a current nor past DSM-IV Axis I or II disorder. Potential confounding effects of age, gender, level of parental verbal aggression, parental education, financial stress, full scale IQ, and total GMV, or average thickness were modeled using voxel based morphometry and FreeSurfer. Witnessing domestic violence subjects had a 6.1% GMV reduction in the right lingual gyrus (BA18) (P = 0.029, False Discovery Rate corrected peak level). Thickness in this region was also reduced, as was thickness in V2 bilaterally and left occipital pole. Theses regions were maximally sensitive to exposure to witnessing domestic violence between 11–13 years of age. Regional reductions in GMV and thickness were observed in both susceptible and resilient witnessing domestic violence subjects. Results in subjects witnessing domestic violence were similar to previously reported results in subjects with childhood sexual abuse, as the primary region affected was visual cortex. Brain regions that process and convey the adverse sensory input of the abuse may be specifically modified by this experience, particularly in subjects exposed to a single type of maltreatment. Exposure to multiple types of maltreatment is more commonly associated with morphological alterations in corticolimbic regions. These findings fit with preclinical studies showing that visual cortex is a highly plastic structure
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