Fluid model for a network operating under a fair bandwidth-sharing policy

We consider a model of Internet congestion control that represents the randomly varying number of flows present in a network where bandwidth is shared fairly between document transfers. We study critical fluid models obtained as formal limits under law of large numbers scalings when the average load on at least one resource is equal to its capacity. We establish convergence to equilibria for fluid models and identify the invariant manifold. The form of the invariant manifold gives insight into the phenomenon of entrainment whereby congestion at some resources may prevent other resources from working at their full capacity

Detection of brain functional-connectivity difference in post-stroke patients using group-level covariance modeling

Functional brain connectivity, as revealed through distant correlations in the signals measured by functional Magnetic Resonance Imaging (fMRI), is a promising source of biomarkers of brain pathologies. However, establishing and using diagnostic markers requires probabilistic inter-subject comparisons. Principled comparison of functional-connectivity structures is still a challenging issue. We give a new matrix-variate probabilistic model suitable for inter-subject comparison of functional connectivity matrices on the manifold of Symmetric Positive Definite (SPD) matrices. We show that this model leads to a new algorithm for principled comparison of connectivity coefficients between pairs of regions. We apply this model to comparing separately post-stroke patients to a group of healthy controls. We find neurologically-relevant connection differences and show that our model is more sensitive that the standard procedure. To the best of our knowledge, these results are the first report of functional connectivity differences between a single-patient and a group and thus establish an important step toward using functional connectivity as a diagnostic tool

The ontology of causal process theories

There is a widespread belief that the so-called process theories of causation developed by Wesley Salmon and Phil Dowe have given us an original account of what causation really is. In this paper, I show that this is a misconception. The notion of "causal process" does not offer us a new ontological account of causation. I make this argument by explicating the implicit ontological commitments in Salmon and Dowe's theories. From this, it is clear that Salmon's Mark Transmission Theory collapses to a counterfactual theory of causation, while the Conserved Quantity Theory collapses to David Fair's phsyicalist reduction of causation

Genomic identification, expression profiling, and functional characterization of CatSper channels in the bovine

peer-reviewedCation channels of sperm (CatSper) are sperm-specific calcium channels with identified roles in the regulation of sperm function in humans, mice, and horses. We sought to employ a comparative genomics approach to identify conserved CATSPER genes in the bovine genome, and profile their expression in reproductive tissue. We hypothesized that CATSPER proteins expressed in bull testicular tissue mediates sperm hyperactivation and their rheotactic response in the reproductive tract of the cow. Bioinformatic analysis identified all four known CATSPER genes (CATSPER 1-4) in the bovine genome, and profiling by quantitative real-time polymerase chain reaction identified site-specific variation in messenger ribonucleic acid (mRNA) expression for all four genes along the reproductive tract of the bull. Using a novel antibody against CATSPER 1, protein expression was confirmed and localized to the principal piece of bull sperm, in agreement with what has been reported in other species. Subsequent treatment of bull sperm with either the calcium chelator ethylene glycol tetraacetic acid; mibefradil, a specific blocker of CatSper channels in human sperm; or CATSPER1 antibody all significantly inhibited caffeine-induced hyperactivation and the rheotactic response, supporting the concept that the calcium influx occurs via CatSper channels. Taken together, the work here provides novel insights into expression and function of CatSper channels in bull testicular tissue and in the function of ejaculated sperm.peer-reviewe

Plane of nutrition before and after 6 months of age in Holstein-Friesian bulls: II. Effects on metabolic and reproductive endocrinology and identification of physiological markers of puberty and sexual maturation

peer-reviewedThe aim of this study was (1) to examine the effect of plane of nutrition during the first and second 6 mo of life on systemic concentrations of reproductive hormones and metabolites in Holstein-Friesian dairy bulls, and (2) to establish relationships with age at puberty and postpubertal semen production potential. Holstein-Friesian bull calves (n = 83) with a mean (standard deviation) age and body weight of 17 (4.4) d and 52 (6.2) kg, respectively, were assigned to a high or low plane of nutrition for the first 6 mo of life. At 24 wk of age, bulls were reassigned, within treatment, either to remain on the same diet or to switch to the opposite diet until puberty, resulting in 4 treatment groups: high-high, high-low, low-low, and low-high. Monthly blood samples were analyzed for metabolites (albumin, urea, total protein, β-hydroxybutyrate, glucose, nonesterified fatty acid, triglycerides and creatinine), insulin, insulin-like growth factor-1, leptin, adiponectin, FSH, and testosterone. A GnRH challenge was carried out at 16 and 32 wk of age (n = 9 bulls per treatment). Blood was collected at 15-min intervals for 165 min, with GnRH administered (0.05 mg/kg of body weight, i.v.) immediately after the third blood sample. Blood samples were subsequently analyzed for LH, FSH, and testosterone. Stepwise regression was used to detect growth and blood measurements to identify putative predictors of age at puberty and subsequent semen quality traits. Metabolic hormones and metabolites, in general, reflected metabolic status of bulls. Although FSH was unaffected by diet, it decreased with age both in monthly samples and following GnRH administration. Testosterone was greater in bulls on the high diet before and after 6 mo of age. Testosterone concentrations increased dramatically after 6 mo of age. Luteinizing hormone was unaffected by diet following GnRH administration but basal serum LH was greater in bulls on a high diet before 6 mo of age. In conclusion, the plane of nutrition offered before 6 mo of age influenced metabolic profiles, which are important for promoting GnRH pulsatility, in young bull

Effect of exposing rams to a female stimulus before semen collection on ram libido and semen quality

peer-reviewedRams with strong libido and desirable semen characteristics can provide more insemination doses per ejaculate and produce more progeny, improving population genetic linkage to improve the accuracy of EBV. The objective of this study was to determine if teasing rams, either by sight and smell alone (Exp. 1), or physical contact (Exp. 2), could improve libido and semen quality of rams. In Exp. 1, there were 3 treatments in which rams were exposed to the sight and smell of the ewe for 1 h: control treatment (n = 5) in which rams were exposed to a ewe not in estrus; non-novel treatment (n = 6) in which rams were exposed to a ewe in estrus and the same ewe was used for semen collection; and novel treatment (n = 6) in which rams were exposed to a ewe in estrus and a different ewe in estrus was used for semen collection. In Exp. 2, rams were individually given full access to a ewe, which had a cotton apron fi tted to cover her vulva, for 15 min. The 3 treatments in Exp. 2 were: control treatment (n = 5) in which rams were placed in a pen with a ewe not in estrus; a nonnovel treatment (n = 5) in which rams were placed in a pen with a ewe in estrus and the same ewe was used for semen collection; novel treatment (n = 6) in which rams were placed in a pen with a ewe in estrus and a different ewe in estrus was used for semen collection. Experiment 1 was repeated for 5 consecutive days and Exp. 2 was repeated for 4 consecutive days. Data on reaction time, number of mounts, semen volume, semen concentration, sperm wave motion, and progressive linear motion (Exp. 1 only) were collected and analyzed as a randomized complete block design, where rams were initially blocked for breed and age. In Exp. 1, there was an effect of day (P < 0.05) and a treatment × day interaction (P < 0.05) on semen volume, whereas there was also an effect of treatment (P < 0.05) and day (P < 0.01) on semen concentration, which was most evident on d 1. In Exp. 2, there was an effect of treatment on reaction time (P < 0.05) and semen volume (P = 0.08), which was most evident on d 1. This study demonstrates an acute effect on d 1 on semen concentration when rams were exposed to the sight and smell of a ewe in estrus. Alternatively, when rams were stimulated with physical contact of a ewe in estrus, an acute increase in semen volume was evident on d 1. These effects were not evident on subsequent days and thus the overall benefi ts on ram libido and semen quality of exposing rams to ewes in estrus are minimal.PUBLISHEDpeer-reviewe

Dielectrophoresis-Driven Spreading of Immersed Liquid Droplets

In recent years electrowetting-on-dielectric (EWOD) has become an effective tool to control partial wetting. EWOD uses the liquid−solid interface as part of a capacitive structure that allows capacitive and interfacial energies to adjust by changes in wetting when the liquid−solid interface is charged due to an applied voltage. An important aspect of EWOD has been its applications in micro fluidics in chemistry and biology and in optical devices and displays in physics and engineering. Many of these rely on the use of a liquid droplet immersed in a second liquid due to the need either for neutral buoyancy to overcome gravity and shield against impact shocks or to encapsulate the droplet for other reasons, such as in microfluidic-based DNA analyses. Recently, it has been shown that nonwetting oleophobic surfaces can be forcibly wetted by nonconducting oils using nonuniform electric fields and an interface-localized form of liquid dielectrophoresis (dielectrowetting). Here we show that this effect can be used to create films of oil immersed in a second immiscible fluid of lower permittivity. We predict that the square of the thickness of the film should obey a simple law dependent on the square of the applied voltage and with strength dependent on the ratio of difference in permittivity to the liquid-fluid interfacial tension, Δε/γLF. This relationship is experimentally confirmed for 11 liquid−air and liquid−liquid combinations with Δε/γLF having a span of more than two orders of magnitude. We therefore provide fundamental understanding of dielectrowetting for liquid-in-liquid systems and also open up a new method to determine liquid−liquid interfacial tensions

Political devolution and employment relations in Great Britain: the case of the Living Wage

This article examines the role of the devolved governments of Scotland and Wales in promoting the voluntary Living Wage. It shows that active promotion of the Living Wage standard has emerged in both countries from a broader commitment to an economic policy of ‘inclusive growth’. Employment law is not a devolved matter, and the article identifies a broad range of economic incentives and soft forms of regulation that have been used by the devolved governments to promote the Living Wage in the absence of hard power to legislate. Non‐legislative forms of state intervention are often regarded sceptically, but the article shows that the attempts of devolved governments to spread the Living Wage have been impactful, particularly in Scotland

Metabolic Syndrome and Early-Onset Coronary Artery Disease Is the Whole Greater Than Its Parts?

ObjectivesWe sought to examine the association between the metabolic syndrome (MetS) (defined both by the 2001 National Cholesterol Educational Program Adult Treatment Panel III [ATP-III] definition and the American Heart Association/National Heart, Lung and Blood Institute [AHA/NHLBI] revision incorporating the lower threshold for impaired fasting glucose [IFG]) and early-onset coronary artery disease (CAD).BackgroundThe impact of MetS on premature CAD has not been studied extensively. Lowering the threshold to define the IFG component (from 110 to 100 mg/dl) and the value of the syndrome as a whole versus its individual components are subjects of intense debate.MethodsWe performed a case-control study with 393 early-onset CAD subjects (acute myocardial infarction, angina with ≥50% stenosis, or coronary revascularization) in men under age 46 years or women under age 56 years and 393 control subjects individually matched for gender, age, and race/ethnicity.ResultsBy conditional logistic regression, presence of ATP-III MetS without diabetes (adjusted odds ratio [adj-OR] 4.9; 95% confidence interval [CI] 3.4 to 8.0) and with diabetes (adj-OR 8.0, 95% CI 4.39 to 14.6) was a strong independent determinant of early-onset CAD. Using the AHA/NHLBI revision, these ORs became slightly stronger. However, neither definition of MetS remained significantly associated with early-onset CAD in multivariate models adjusting for individual components.ConclusionsThe presence of MetS imparts a high risk of early-onset clinical CAD, but the prognostic information associated with the syndrome is not greater than the sum of its parts