4,924 research outputs found
Effects of BMI on bone loading due to physical activity
The aim of the current study was to compare bone loading due to physical activity between lean and, overweight and obese individuals. Fifteen participants (lower BMI group: BMI<25 kg/m2, n=7; higher BMI group: 25 kg/m2 < BMI < 36.35 kg/m2, n=8) wore a tri-axial accelerometer on one day to collect data for the calculation of bone loading. The International Physical Activity Questionnaire (short form) was used to measure time spent at different physical activity levels. Daily step counts were measured using a pedometer. Differences between groups were compared using independent t-tests. Accelerometer data revealed greater loading dose at the hip in lower BMI participants at a frequency band of 0.1â2 Hz (P=.039, Cohenâs d =1.27) and 2â4 Hz (P=.044, d =1.24). Lower BMI participants also had a significantly greater step count (P=.023, d =1.55). This corroborated with loading intensity (d â„ 0.93) and questionnaire (d =0.79) effect sizes to indicate higher BMI participants tended to spend more time in very light, and less time in light and moderate activity. Overall participants with a lower BMI exhibited greater bone loading due to physical activity; participants with a higher BMI may benefit from more light and moderate level activity to maintain bone health.Kelloggâs Compan
Reciprocal and dynamic polarization of planar cell polarity core components and myosin
Citation: Newman-Smith, E., Kourakis, M. J., Reeves, W., Veeman, M., & Smith, W. C. (2015). Reciprocal and dynamic polarization of planar cell polarity core components and myosin. eLife, 2015(4). doi:10.7554/eLife.05361The Ciona notochord displays PCP-dependent polarity, with anterior localization of Prickle (Pk) and Strabismus (Stbm). We report that a myosin is polarized anteriorly in these cells and strongly colocalize with Stbm. Disruption of the actin/myosin machinery with cytochalasin or blebbistatin disrupts polarization of Pk and Stbm, but not of myosin complexes, suggesting a PCP-independent aspect of myosin localization. Washout of cytochalasin restored Pk polarization, but not if done in the presence of blebbistatin, suggesting an active role for myosin in core PCP protein localization. On the other hand, in the pk mutant line aimless myosin polarization in approximately one third of the cells, indicating a reciprocal action of core PCP signaling on myosin localization. Our results indicate a complex relationship between the actomyosin cytoskeleton and core PCP components in which myosin is not simply a downstream target of PCP signaling, but also required for PCP protein localization. © 2015, eLife. All rights reserved
Evidence for Orbital Motion of Material Close to the Central Black Hole of Mrk 766
Time-resolved X-ray spectroscopy has been obtained for the narrow line
Seyfert galaxy Mrk766 from XMM-Newton observations. We present analysis in the
energy-time plane of EPIC pn data in the 4-8 keV band with energy resolution
R~50. A component of Fe Ka emission detected in the maps shows a variation of
photon energy with time that appears both to be statistically significant and
to be consistent with sinusoidal variation. We investigate the interpretation
that there exists a component of line emission from matter in a Keplerian orbit
around a supermassive black hole. The orbit has a period ~165 ks and a
line-of-sight velocity ~13,500 km/s. This yields a lower limit for the central
mass of M > 4.9x10^5 solar masses within a radius of 3.6 x 10^13 cm (2.4 A.U.).
The orbit parameters are consistent with higher black hole masses, but the lack
of any substantial gravitational redshift of the orbit implies an upper limit
to the black hole mass of 4.5x10^7 solar masses.Comment: 20 pages, 6 figures (some colour). Accepted for publication in A&A.
Only minor changes since V1 (including reordering of Figs 1a & b
XMM-Newton monitoring of X-ray variability in the quasar PKS 0558-504
We present the temporal analysis of X-ray observations of the radio-loud
Narrow-Line Seyfert 1 galaxy (NLS1) PKS 0558-504 obtained during the XMM-Newton
Calibration and Performance Verification (Cal/PV) phase. The long term light
curve is characterized by persistent variability with a clear tendency for the
X-ray continuum to harden when the count rate increases. Another strong
correlation on long time scales has been found between the variability in the
hard band and the total flux. On shorter time scales the most relevant result
is the presence of smooth modulations, with characteristic time of ~ 2 hours
observed in each individual observation. The short term spectral variability
turns out to be rather complex but can be described by a well defined pattern
in the hardness ratio-count rate plane.Comment: 6 pages, 7 figures, accepted for publication in A&A special issue on
first results from XM
Estimating the Permanent Loss of Groundwater Storage in the Southern San Joaquin Valley, California
In the San Joaquin Valley, California, recent droughts starting in 2007 have increased the pumping of groundwater, leading to widespread subsidence. In the southern portion of the San Joaquin Valley, vertical subsidence as high as 85 cm has been observed between June 2007 and December 2010 using Interferometric Synthetic Aperture Radar (InSAR). This study seeks to map regions where inelastic (not recoverable) deformation occurred during the study period, resulting in permanent compaction and loss of groundwater storage. We estimated the amount of permanent compaction by incorporating multiple data sets: the total deformation derived from InSAR, estimated skeletal-specific storage and hydraulic parameters, geologic information, and measured water levels during our study period. We used two approaches, one that we consider to provide an estimate of the lowest possible amount of inelastic deformation, and one that provides a more reasonable estimate. These two approaches resulted in a spatial distribution of values for the percentage of the total deformation that was inelastic, with the former estimating a spatially averaged value of 54%, and the latter a spatially averaged value of 98%. The former corresponds to the permanent loss of 4.14*108 m3 of groundwater storage, or roughly 5% of the volume of groundwater used over the study time period; the latter corresponds to the loss of 7.48*108 m3 of groundwater storage, or roughly 9% of the volume of groundwater used. This study demonstrates that a data-driven approach can be used effectively to estimate the permanent loss of groundwater storage
The variable X-ray spectrum of Markarian 766 - I. Principal components analysis
Aims: We analyse a long XMM-Newton spectrum of the narrow-line Seyfert 1
galaxy Mrk 766, using the marked spectral variability on timescales >20ks to
separate components in the X-ray spectrum. Methods: Principal components
analysis is used to identify distinct emission components in the X-ray
spectrum, possible alternative physical models for those components are then
compared statistically. Results: The source spectral variability is
well-explained by additive variations, with smaller extra contributions most
likely arising from variable absorption. The principal varying component,
eigenvector one, is found to have a steep (photon index 2.4) power-law shape,
affected by a low column of ionised absorption that leads to the appearance of
a soft excess. Eigenvector one varies by a factor 10 in amplitude on
time-scales of days and appears to have broad ionised Fe K-alpha emission
associated with it: the width of the ionised line is consistent with an origin
at about 100 gravitational radii. There is also a strong component of
near-constant emission that dominates in the low state, whose spectrum is
extremely hard above 1 keV, with a soft excess at lower energies, and with a
strong edge at Fe K but remarkably little Fe K-alpha emission. Although this
component may be explained as relativistically-blurred reflection from the
inner accretion disc, we suggest that its spectrum and lack of variability may
alternatively be explained as either (i) ionised reflection from an extended
region, possibly a disc wind, or (ii) a signature of absorption by a disc wind
with a variable covering fraction. Absorption features in the low state may
indicate the presence of an outflow.Comment: 14 pages, accepted for publication in Astronomy & Astrophysic
Rational bidding using reinforcement learning: an application in automated resource allocation
The application of autonomous agents by the provisioning and usage of computational resources is an attractive research field. Various methods and technologies in the area of artificial intelligence, statistics and economics are playing together to achieve i) autonomic resource provisioning and usage of computational resources, to invent ii) competitive bidding strategies for widely used market mechanisms and to iii) incentivize consumers and providers to use such market-based systems.
The contributions of the paper are threefold. First, we present a framework for supporting consumers and providers in technical and economic preference elicitation and the generation of bids. Secondly, we introduce a consumer-side reinforcement learning bidding strategy which enables rational behavior by the generation and selection of bids. Thirdly, we evaluate and compare this bidding strategy against a truth-telling bidding strategy for two kinds of market mechanisms â one centralized and one decentralized
Estimating antimicrobial usage based on sales to beef and dairy farms from UK veterinary practices
Does manipulation of breakfast behaviour effect reported level of pre-prandial hunger and serum ghrelin levels?
Breakfast is commonly described as being beneficial for health and people who eat breakfast have frequently been reported as having a lower body mass index compared to people who skip breakfast; however reasons for this potential association are still not clear. The aim of this study was to focus particularly on pre-prandial hunger and serum ghrelin levels in lean and overweight breakfast eaters and breakfast skippers (n Œ 37) when asked to consume breakfast for 7 days and skip breakfast for 7 days. Measurements were taken at the start and the end of each breakfast condition. Habitual breakfast eaters reported greater levels of hunger in each breakfast condition compared with breakfast skippers (p <0.05). Changing to the alternative breakfast condition did not influence hunger scores. There were no differences in total ghrelin levels between breakfast eaters and breakfast skippers, the different breakfast conditions nor were there any differences between measurements made at baseline and after 7 days. It was concluded that this relatively short intervention had no significant effect on breakfast time hunger; it is possible that seven days was not sufficient to modify habitual breakfast behaviour or patterns of ghrelin secretion
The Quark-Hadron Phase Transition, QCD Lattice Calculations and Inhomogeneous Big-Bang Nucleosynthesis
We review recent lattice QCD results for the surface tension at the finite
temperature quark-hadron phase transition and discuss their implications on the
possible scale of inhomogeneities. In the quenched approximation the average
distance between nucleating centers is smaller than the diffusion length of a
protron, so that inhomogeneities are washed out by the time nucleosynthesis
sets in. Consequently the baryon density fluctuations formed by a QCD phase
transition in the early universe cannot significantly affect standard big-bang
nucleosynthesis calculations and certainly cannot allow baryons to close the
universe. At present lattice results are inconclusive when dynamical fermions
are included.Comment: 8 pages, LaTe
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