Wake states and frequency selection of a streamwise oscillating cylinder

This paper presents the results of an in-depth study of the flow past a streamwise oscillating cylinder, examining the impact of varying the amplitude and frequency of the oscillation, and the Reynolds number of the incoming flow. These findings are presented in a framework that shows that the relationship between the frequency of vortex shedding fs and the amplitude of oscillation A* is governed by two primary factors: the first is a reduction of fs proportional to a series in A*2 over a wide range of driving frequencies and Reynolds numbers; the second is nonlinear synchronization when this adjusted fs is in the vicinity of N = (1 - fs/fd)-1, where N is an integer. Typically, the influence of higher-order terms is small, and truncation to the first term of the series (A*2) well represents the overall trend of vortex shedding frequency as a function of amplitude. However, discontinuous steps are overlaid on this trend due to the nonlinear synchronization. When fs is normalized by the Strouhal frequency fSt (the frequency of vortex shedding from an unperturbed cylinder), the rate at which fs/fSt decreases with amplitude, at least for fd/fSt = 1, shows a linear dependence on the Reynolds number. For a fixed Re = 175, the truncated series shows that the rate of decrease of fs/fSt with amplitude varies as (2 - fd/fSt)-1/2 for 1 < or egal fd/fSt < or egal 2, but is essentially independent of fd/fSt for fd/fSt < 1. These trends of the rate of decrease of fs with respect to amplitude are also used to predict the amplitudes of oscillation around which synchronization occurs. These predicted amplitudes are shown to fall in regions of the parameter space where synchronized modes occur. Further, for the case of varying fd/fSt, a very reasonable prediction of the amplitude of oscillation required for the onset of synchronization to the mode where fs = 0.5fd is given. In a similar manner, amplitudes at which fs = 0 are calculated, predicting where the natural vortex shedding is completely supplanted by the forcing. These amplitudes are found to coincide approximately with those at which the onset of a symmetric vortex shedding mode is observed. This result is interpreted as meaning that the symmetric shedding mode occurs when the dynamics crosses over from being dominated by the vortex shedding to being dominated by the forcing

The Deficit-Reducing Potential of a Financial Speculation Tax

While a number of commissions and organizations around Washington have produced plans for reducing the projected deficit in the decades ahead, most have not included a financial speculation tax (FST) in the mix. This seems peculiar since an FST has several features that could make it attractive as a revenue source

How to Use Fewer Markers in Admixture Studies

Swiss Fleckvieh has been established from 1970 as a composite of Simmental and Red Holstein Friesian cattle. Breed composition is currently reported based on pedigree information. Information on ancestry informative molecular markers potentially provides more accurate information. For the analysis Illumina Bovine SNP50 Beadchip data for 495 bulls were used. Markers were selected based on difference in allele frequencies in the pure populations, using FST as an indicator. Performance of sets with decreasing number of markers was compared. The scope of the study was to see how much we can reduce the number of markers based on FST to get a reliability that is close to that with the full set of markers. On these sets of markers hidden Markov models (HMM) and methods used in genomic selection (BayesB, partial least squares regression, LASSO variable selection) were applied. Correlations of admixture levels were estimated and compared with admixture levels based on pedigree information. FST chosen SNP gave very high correlations with pedigree based admixture. Only when using 96 and 48 SNP with the highest FST, correlations dropped to 0.92 and 0.90, respectively

Estimators for QST and coalescence times.

Comparisons of QST to FST can provide insights into the evolutionary processes that lead to differentiation, or lack thereof, among the phenotypes of different groups (e.g., populations, species), and these comparisons have been performed on a variety of taxa, including humans. Here, I show that for neutrally evolving (i.e., by genetic drift, mutation, and gene flow alone) quantitative characters, the two commonly used QST estimators have somewhat different interpretations in terms of coalescence times, particularly when the number of groups that have been sampled is small. A similar situation occurs for FST estimators. Consequently, when observations come from only a small number of groups, which is not an unusual situation, it is important to match estimators appropriately when comparing QST to FST

Feasibility of a randomized controlled trial of functional strength training for people between six months and five years after stroke: FeSTivaLS trial

Background: Functional Strength Training (FST) could enhance recovery late after stroke. The aim of this study was to evaluate the feasibility of a subsequent fully powered, randomized controlled trial. Methods: The study was designed as a randomized, observer-blind trial. Both interventions were provided for up to one hour a day, four days a week, for six weeks. Evaluation points were before randomization (baseline), after six weeks intervention (outcome), and six weeks thereafter (follow-up). The study took place in participants’ own homes. Participants (n = 52) were a mean of 24.4 months after stroke with a mean age of 68.3 years with 67.3% male. All had difficulty using their paretic upper (UL) and lower limb (LL). Participants were allocated to FST-UL or FST-LL by an independent randomization service. The outcome measures were recruitment rate, attrition rate, practicality of recruitment strategies, occurrence of adverse reactions, acceptability of FST, and estimation of sample size for a subsequent trial. Primary clinical efficacy outcomes were the Action Research Arm Test (ARAT) and the Functional Ambulation Categories (FAC). Analysis was conducted using descriptive statistics and thematic analysis of participants’ views of FST. A power calculation used estimates of clinical efficacy variance to estimate sample size for a subsequent trial. Results: The screening process identified 1,127 stroke survivors of whom 52 (4.6%) were recruited. The recruitment rate was higher for referral from community therapists than for systematic identification of people discharged from an acute stroke unit. The attrition rate was 15.5% at the outcome and follow-up time-points. None of the participants experienced an adverse reaction. The participants who remained in the study at outcome had received 68% of the total possible amount of therapy. Participants reported that their experience of FST provided a sense of purpose and involvement and increased their confidence in performing activities. The power calculation provides estimation that 150 participants in each group will be required for a subsequent clinical trial. Conclusions: This study found that a subsequent clinical trial was feasible with modifications to the recruitment strategy to be used

GAL(1-15) induces a depression and anxiogenic effect trough GALR1/GALR2 heteroreceptor: siRNA GALR1/GALR2 knockdown rats

The Galanin N-terminal fragment (1-15) [GAL(1-15)] induces depressant- and anxiogenic- like actions. In this work, we have studied the role of GALR2 and GALR1 on the effects of GAL(1-15) in the Forced Swimming Test (FST) and Open Field Test (OFT) using siRNA GALR2 and GALR1 knockdown rats. Rats (n=6-14) were injected with GAL(1-15) 3nmol, GALR2 antagonist M871 3nmol in combination or alone 15 before the FST or OFT. The time of immobility, climbing and swimming were recorded during 5 min FST and Time and entries in the central square during 5min were scored in the OFT. In other experiment, rats (n=6-14) were injected Intracerebroventricular (icv) with siRNA-GALR2 or siRNA-GALR1 to generate the GALR knockdown rats. These knockdown rats were used in the OFT and in the FST after receiving icv GAL(1-15) 3nmol 15 min before the test. Vehicle was used as control. In the FST, M871 significantly blocked the increased immobility (p<0.001) and decreased climbing (p<0.01) induced by GAL(1-15). In the OFT M871 also significantly decreased the number of entries (p<0.001) and time spent in the center (p<0.05) mediated by GAL(1-15). Down-regulation of GALR2 or GALR1 by siRNA was sufficient to block the effect of GAL(1-15) in behavioural tests. Thus, GAL(1-15) 3nmol lacked effect on the immobility, climbing and swimming time in the FST. The same effect was observed in the number of entries and time spent in the central square in the OFT. These results indicated that GALR1 and GALR2 are involved in the GAL(1-15) depression- and anxiogenic-like effects suggesting that GAL(1-15) could act through GALR1/GALR2 heteroreceptor complex. These findings may give the basis for the development of novel therapeutic drugs targeting GAL(1-15) system for treatment of depression and anxiety disorders. This study was supported by Junta de Andalucía CVI6476.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech