337 research outputs found
A one parameter representation for the Isgur-Wise function
We use a lattice QCD heavy-light wavefunction to generate a single
parameter, model independent description of the Isgur-Wise function. Using
recent data we find the zero-recoil slope to be , while
the second derivative turns out to be .Comment: Latex (uses epsf macro), 7 pages of text, 2 postscript figures
included
Perception of Affordances for Dribbling in Soccer:Exploring Children as Architects of Skill Development Opportunity
This study examined affordance perception for soccer dribbling using a mixed-methods approach in male grassroots soccer players. We examined how children construct and perceive skills practices for dribbling in soccer. Fourteen boys aged 10–11 years (Mean ± SD = 10.8 ± 0.4 years) who were regularly engaged in grassroots soccer participated in the present study. Children were provided with ten soccer cones and asked to create their own soccer dribbling pattern that would enable them to maximise the number of touches with a football and then dribble the ball in the pattern they had created for a 1 min period. Children were interviewed to explore their perception of affordances for soccer dribbling. The test of gross motor development-3 was used to assess fundamental movement skills (FMS), and the UGent soccer dribbling test was used to assess soccer dribbling skills. Children self-rated their own ability for soccer dribbling, as did their coaches. Pearson’s correlations were employed to examine the associations between quantitative variables, and thematic analysis was used to explore qualitative data. Results of the present study suggest that those children who created patterns with less space between cones accrued more touches of the football in their dribbling task (r = −0.671, p = 0.03). Children with a higher perception of their own dribbling ability had higher scores for FMS (r = 0.604, p = 0.049). Those children who scored better in actual soccer dribbling had higher scores for FMS (r = −0.746, p = 0.012) and were rated as better dribblers by their coaches (r = −0.67, p = 0.03). Interview data suggest a feedback loop between perception of ability and actual ability, which influenced the dribbling patterns that were created. This suggests that dribbling performance is scaled to the (perceived) action capabilities of the children, and children can act as architects in their own skill developmen
Semileptonic form factors - a model-independent approach
We demonstrate that the B->D(*) l nu form factors can be accurately predicted
given the slope parameter rho^2 of the Isgur-Wise function. Only weak
assumptions, consistent with lattice results, on the wavefunction for the light
degrees of freedom are required to establish this result. We observe that the
QCD and 1/m_Q corrections can be systematically represented by an effective
Isgur-Wise function of shifted slope. This greatly simplifies the analysis of
semileptonic B decay. We also investigate what the available semileptonic data
can tell us about lattice QCD and Heavy Quark Effective Theory. A rigorous
identity relating the form factor slope difference rho_D^2-rho_A1^2 to a
combination of form factor intercepts is found. The identity provides a means
of checking theoretically evaluated intercepts with experiment.Comment: 18 pages, Revtex, 4 postscript figures, uses epsfig.st
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The identity of crop pollinators helps target conservation for improved ecosystem services
Insect pollinated mass flowering crops are becoming more widespread and there is a need to understand which insects are primarily responsible for the pollination of these crops so conservation measures can be appropriately targeted in the face of pollinator declines. This study used field surveys in conjunction with cage manipulations to identify the relative contributions of different pollinator taxa to the pollination of two widespread flowering crops, field beans and oilseed rape. Flower visiting pollinator communities observed in the field were distinct for each crop; while field beans were visited primarily by a few bumblebee species, multiple pollinator taxa visited oilseed, and the composition of this pollinator community was highly variable spatially and temporally. Neither pollinator community, however, appears to be meeting the demands of crops in our study regions. Cage manipulations showed that multiple taxa can effectively pollinate both oilseed and field beans, but bumblebees are particularly effective bean pollinators. Combining field observations and cage manipulations demonstrated that the pollination demands of these two mass flowering crops are highly contrasting, one would benefit from management to increase the abundance of some key taxa, whilst for the other, boosting overall pollinator abundance and diversity would be more appropriate. Our findings highlight the need for crop specific mitigation strategies that are targeted at conserving specific pollinator taxa (or group of taxa) that are both active and capable of crop pollination in order to reduce pollination deficits and meet the demands of future crop production
Quadriceps volumes are reduced in people with patellofemoral joint osteoarthritis
Objectives: This study aimed to (1) compare the volumes of vastus medialis (VM), vastus lateralis (VL), vastus intermedius and rectus femoris and the ratio of VM/VL volumes between asymptomatic controls and patellofemoral joint osteoarthritis (PFJ OA) participants; and (2) assess the relationships between cross-sectional area (CSA) and volumes of the VM and VL in individuals with and without PFJ OA. Methods: Twenty-two participants with PFJ OA and 11 controls aged ≥40 years were recruited from the community and practitioner referrals. Muscle volumes of individual quadriceps components were measured from thigh magnetic resonance (MR) images. The CSA of the VM and lateralis were measured at 10 equally distributed levels (femoral condyles to lesser femoral trochanter). Results: PFJ OA individuals had smaller normalized VM (mean difference 0.90 cm ·kg , α = 0.011), VL (1.50 cm ·kg , α = 0.012) and rectus femoris (0.71 cm ·kg , α = 0.009) volumes than controls. No differences in the VM/VL ratio were observed. The CSA at the third level (controls) and fourth level (PFJ OA) above the femoral condyles best predicted VM volume, whereas the VL volume was best predicted by the CSA at the seventh level (controls) and sixth level (PFJ OA) above the femoral condyles. Conclusion: Reduced quadriceps muscle volume was a feature of PFJ OA. Muscle volume could be predicted from CSA measurements at specific levels in PFJ OA patients and controls
Application of Structure Equation Modeling for Inferring a Serial Transcriptional Regulation in Yeast
Revealing the gene regulatory systems among DNA and proteins in living cells is one of the central aims of systems biology. In this study, I used Structural Equation Modeling (SEM) in combination with stepwise factor analysis to infer the protein-DNA interactions for gene expression control from only gene expression profiles, in the absence of protein information. I applied my approach to infer the causalities within the well-studied serial transcriptional regulation composed of GAL-related genes in yeast. This allowed me to reveal the hierarchy of serial transcriptional regulation, including previously unclear protein-DNA interactions. The validity of the constructed model was demonstrated by comparing the results with previous reports describing the regulation of the transcription factors. Furthermore, the model revealed combinatory regulation by Gal4p and Gal80p. In this study, the target genes were divided into three types: those regulated by one factor and those controlled by a combination of two factors
Associations between movement behaviours and obesity markers among preschoolers compliant and non-compliant with sleep duration:A latent profile analysis
This study identifies physical activity (PA) and sedentary behaviour (SB) clusters in preschoolers compliant (C) or non-compliant (NC) with sleep recommendations; and associates these clusters with obesity markers. PA and SB were objectively assessed (Actigraph WGT3-X) in 272 preschoolers (4.4 ± 0.7 years old). Sleep duration was parent-reported, and preschoolers were classified as C (3–4 years old: 600–780 min/day; 5 years old: 540–660 min/day) or NC with sleep recommendations. Body mass index (BMI) and waist circumference (WC) were assessed according to international protocols. Moderate to vigorous physical activity (MVPA) and light physical activity (LPA) were categorized as low/high (60 min/day or <180 min/180 min/day, respectively). SB was defined according to mean values between clusters. Latent profile analysis was performed. Associations between the observed clusters and obesity markers were determined using linear regression (RStudio; 1.3.1073). Four cluster solutions for C and NC preschoolers were identified. A negative association between C/Low MVPA cluster and BMI, and a positive association between NC/Low MVPA and BMI (β = −0.8, 95%CI = −1.6;−0.1, and β = 0.9, 95%CI = 0.1;1.7, respectively) were observed. No association was seen for SB clusters. Adequate sleep duration may have a protective role for preschoolers’ BMI, even if the children do not comply with MVPA recommendations
The Kentucky Noisy Monte Carlo Algorithm for Wilson Dynamical Fermions
We develop an implementation for a recently proposed Noisy Monte Carlo
approach to the simulation of lattice QCD with dynamical fermions by
incorporating the full fermion determinant directly. Our algorithm uses a
quenched gauge field update with a shifted gauge coupling to minimize
fluctuations in the trace log of the Wilson Dirac matrix. The details of tuning
the gauge coupling shift as well as results for the distribution of noisy
estimators in our implementation are given. We present data for some basic
observables from the noisy method, as well as acceptance rate information and
discuss potential autocorrelation and sign violation effects. Both the results
and the efficiency of the algorithm are compared against those of Hybrid Monte
Carlo.
PACS Numbers: 12.38.Gc, 11.15.Ha, 02.70.Uu Keywords: Noisy Monte Carlo,
Lattice QCD, Determinant, Finite Density, QCDSPComment: 30 pages, 6 figure
S to P wave form factors in semi-leptonic B decays
We apply HQET to semi-leptonic and meson decays into the observed
charmed wave states. In order to examine the sensitivity of the results to
the choice of a specific model, we perform all calculations using several
different meson models, and find that uncertainty introduced by the choice of a
particular model is about 30\%. Specifically, assuming and
, we obtain branching ratios of and for B\rar D_{1}l\bar{\nu}_{l} and B\rar D_{2}^{*}l\bar{\nu}_{l}
decays, respectively.Comment: Latex (uses epsf macro), 36 pages of text, 11 postscript figures
include
Unveiling Soft Gamma-Ray Repeaters with INTEGRAL
Thanks to INTEGRAL's long exposures of the Galactic Plane, the two brightest
Soft Gamma-Ray Repeaters, SGR 1806-20 and SGR 1900+14, have been monitored and
studied in detail for the first time at hard-X/soft gamma rays.
This has produced a wealth of new scientific results, which we will review
here. Since SGR 1806-20 was particularly active during the last two years, more
than 300 short bursts have been observed with INTEGRAL. and their
characteristics have been studied with unprecedented sensitivity in the 15-200
keV range. A hardness-intensity anticorrelation within the bursts has been
discovered and the overall Number-Intensity distribution of the bursts has been
determined. In addition, a particularly active state, during which ~100 bursts
were emitted in ~10 minutes, has been observed on October 5 2004, indicating
that the source activity was rapidly increasing. This eventually led to the
Giant Flare of December 27th 2004, for which a possible soft gamma-ray (>80
keV) early afterglow has been detected.
The deep observations allowed us to discover the persistent emission in hard
X-rays (20-150 keV) from 1806-20 and 1900+14, the latter being in a quiescent
state, and to directly compare the spectral characteristics of all Magnetars
(two SGRs and three Anomalous X-ray Pulsars) detected with INTEGRAL.Comment: 8 pages, 7 figures, Presented at the conference "Isolated Neutron
Stars: from the Surface to the Interior", London, UK, 24-28 April 200
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