657 research outputs found
Contact-Induced Nonlinearity in Oscillating Belts and Webs
This study is motivated by issues in belt dynamics and paper forming where the oscillatory motion of the contact point between the belt and pulley or the web and roll is important. The objective is to evaluate the influence of the nonlinear contact boundary conditions on the dynamics of the belt or web. To accomplish this objective, two models are analyzed using perturbation methods. The first model represents a string on an elastic foundation (an approximation of the paper forming process) and the second model represents a tensioned beam (accessory drive belt). The first correction to the fundamental natural frequency and the dynamic belt/web length are determined as a function of the governing parameters. For both models, the change in belt length is found to be proportional to the radius of the pulley/roll and the initial belt/web energy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69021/2/10.1177_107754639500100404.pd
Proteomic profiling of bovine M. longissimus lumborum from Crossbred Aberdeen Angus and Belgian Blue sired steers varying in genetic merit for carcass weight
Bovine skeletal muscle is a tissue
of significant value to the beef industry and global
economy. Proteomic analyses offer the opportunity to
detect molecular mechanisms regulating muscle growth
and intramuscular fat accumulation. The current study
aimed to investigate differences in protein abundance
in skeletal muscle tissue of cattle from two breeds of
contrasting maturity (early vs. late maturing), adiposity,
and muscle growth potential, namely, Belgian Blue
(BB) Ă Holstein Friesian and Aberdeen Angus (AA) Ă
Holstein Friesian. Twenty AA (n = 10) and BB (n = 10)
sired steers, the progeny of sires of either high or low
genetic merit, expressed as expected progeny difference
for carcass weight (EPDcwt), and bred through
AI, were evaluated as 4 genetic groups, BB-High,
BB-Low, AA-High, and AA-Low (n = 5 per treatment).
Chemical composition analysis of M. longissimus
lumborum showed greater protein and moisture and
decreased lipid concentrations for BB-sired compared
with AA-sired steers. To investigate the effects
of both sire breed and EPDcwt on M. longissimus
lumborum, proteomic analysis was performed using
2-dimensional difference gel electrophoresis followed by mass spectrometry. Proteins were identified from
their peptide sequences, using the National Center for
Biotechnology Information (NCBI) and Swiss-prot
databases. Metabolic enzymes involved in glycolysis
(glycogen phosphorylase, phosphoglycerate mutase)
and the citric acid cycle (aconitase 2, oxoglutarate
dehydrogenase) were increased in AA- vs. BB-sired
steers. Expression of proteins involved in cell structure,
such as myosin light chain isoforms and troponins I
and T, were also altered due to sire breed. Furthermore,
heat shock protein ÎČ-1 and peroxiredoxin 6, involved
in cell defense, had increased abundance in muscle of
AA-sired relative to BB-sired steers. Protein abundance
of glucose-6-phosphate isomerase, enolase-3, and
pyruvate kinase was greater in AA-sired animals of
High compared with Low EPDcwt. Changes in the
expression of these proteins were supported by gene
expression analysis using quantitative real-time PCR.
This information will aid in our understanding of
genetic infl uences controlling muscle growth and fat
accumulation and could contribute to future breeding
programs to increase lean tissue gain of beef cattle
Dynamics of ions in the selectivity filter of the KcsA channel
The statistical and dynamical properties of ions in the selectivity filter of the KcsA ion channel are considered on the basis of molecular dynamics (MD) simulations of the KcsA protein embedded in a lipid membrane surrounded by an ionic solution. A new approach to the derivation of a Brownian dynamics (BD) model of ion permeation through the filter is discussed, based on unbiased MD simulations. It is shown that depending on additional assumptions, ionâs dynamics can be described either by under-damped Langevin equation with constant damping and white noise or by Langevin equation with a fractional memory kernel. A comparison of the potential of the mean force derived from unbiased MD simulations with the potential produced by the umbrella sampling method demonstrates significant differences in these potentials. The origin of these differences is an open question that requires further clarifications
The relationship between anogenital distance and fertility, and genome-wide associations for anogenital distance in Irish Holstein-Friesian cows
peer-reviewedThe evaluation of anogenital distance (AGD), the distance from the center of the anus to base of the clitoris, as a potential fertility trait for genetic selection in dairy cows has generated recent interest. The objectives of this cross-sectional observational study were to (1) characterize the distribution and variability of AGD, (2) determine factors associated with AGD, (3) estimate heritability for AGD, (4) identify single nucleotide polymorphisms (SNP) associated with phenotypic variation of AGD, and (5) validate the relationship between categories of AGD and fertility in Irish Holstein-Friesian cows. Anogenital distance was measured using digital calipers in 1,180 Holstein cows (mean ± standard deviation: 225 ± 79 d in milk) from 10 dairy herds located in Munster, Ireland. In addition, age (yr), weight (kg), height at hip (cm), and body condition score (BCS) at the time of AGD measurement were determined in a subset of 281 cows. Genotype information available from 908 cows was subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina Inc., San Diego, CA) for genome-wide association analysis of phenotypic variation in AGD. Overall, AGD had a normal distribution and high variability (mean ± standard deviation; 119.2 ± 11.6 mm). Anogenital distance was weakly but positively associated with cow age, hip height, and body weight, and negatively associated with BCS; the phenotypic variation in AGD that was explainable by these variables was small (coefficient of determination; R2 = 0.09, 0.06, 0.10, and 0.02, respectively). The estimated heritability for AGD was 0.37 (standard error of mean ± 0.08). Six SNP of suggestive significance were identified on Bos taurus autosomes 6, 15, 20, and 26; however, none of these SNP was related to previously identified candidate genes for fertility. Cows were categorized into quartiles (Q1; 86 to 111 mm; n = 311, Q2; 112 to 120 mm; n = 330; Q3; 121 to 127 mm; n = 265, and Q4; 128 to 160 mm; n = 274) based on AGD and the association with reproductive outcomes examined (21-d submission rate, pregnancy to first AI, pregnancy rate within 21, 42 and 84-d after the farm mating start date, and number of times bred). None of the reproductive variables differed significantly between AGD categories. In summary, despite identification of high variability and moderate heritability for AGD in Irish Holstein-Friesian cows, reproductive outcomes did not differ between categories of AGD. This latter result differs from our previous finding of an inverse relationship between AGD and pregnancy outcomes in first- and second-parity Canadian Holstein cows, emphasizing the need to test and validate this new phenotype in diverse cow populations
Thinking about growth : a cognitive mapping approach to understanding small business development
School of Managemen
Deceleration and trapping of heavy diatomic molecules using a ring-decelerator
We present an analysis of the deceleration and trapping of heavy diatomic
molecules in low-field seeking states by a moving electric potential. This
moving potential is created by a 'ring-decelerator', which consists of a series
of ring-shaped electrodes to which oscillating high voltages are applied.
Particle trajectory simulations have been used to analyze the deceleration and
trapping efficiency for a group of molecules that is of special interest for
precision measurements of fundamental discrete symmetries. For the typical case
of the SrF molecule in the (N,M) = (2, 0) state, the ring-decelerator is shown
to outperform traditional and alternate-gradient Stark decelerators by at least
an order of magnitude. If further cooled by a stage of laser cooling, the
decelerated molecules allow for a sensitivity gain in a parity violation
measurement, compared to a cryogenic molecular beam experiment, of almost two
orders of magnitude
Gossip in organisations: Contexts, consequences and controversies
This article examines the key themes surrounding gossip including its contexts, the various outcomes (positive and negative) of gossip as well as a selection of challenges and controversies. The challenges which are highlighted revolve around definitional issues, methodological approaches, and ethical considerations. Our analysis suggests that the characteristics and features of gossip lend itself to a process-oriented approach whereby the beginning and, particularly, end points of gossip are not always easily identified. Gossip about a subject or person can temporarily disappear only for it to re-surface at some later stage. In addition, questions pertaining to the effects of gossip and ethical-based arguments depend on the nature of the relationships within the gossip triad (gossiper, listener/respondent and target)
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in âs = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fbâ1 of protonâproton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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