Acoustic oscillations of rapidly rotating polytropic stars. II. Effects of the Coriolis and centrifugal accelerations

Context: With the launch of space missions devoted to asteroseismology (like COROT), the scientific community will soon have accurate measurements of pulsation frequencies in many rapidly rotating stars. Aims: The present work focuses on the effects of rotation on pulsations of rapidly rotating stars when both the Coriolis and centrifugal accelerations require a non-perturbative treatment. Method: We develop a 2-dimensional spectral numerical approach which allows us to compute acoustic modes in centrifugally distorted polytropes including the full influence of the Coriolis force. This method is validated through comparisons with previous studies, and the results are shown to be highly accurate. Results: In the frequency range considered and with COROT's accuracy, we establish a domain of validity for perturbative methods, thus showing the need for complete calculations beyond v.sin i = 50 km/s for a R = 2.3 R_\odot, M = 1.9 M_\odot polytropic star. Furthermore, it is shown that the main differences between complete and perturbative calculations come essentially from the centrifugal distortion.Comment: published in A&A, corrected minor mistakes and updated some reference

Providing health checks as incentives to retain blood donors — evidence from two field experiments

The collection of blood given by donors has proven to be a substantial societal and a managerial challenge. Consequently, blood donation services seek for incentive mechanisms to retain donors. However, economic or material rewards might entail negative side effects such as motivational crowding out or even attracting “bad blood”. In an effort to increase the retention of established blood donors, we conducted two randomized field trials (N1 = 53,257, N2 = 31,522) in cooperation with the German Red Cross Blood Donation Service and tested the effectiveness of an incentive strategy that is directly related to the blood donation itself: offering a comprehensive blood health check. Contrary to previous related research, we found substantial positive effects of a comprehensive blood health check incentive on donation behavior. In addition, unlike previous studies, we examine effects of repeated exposure to this incentive and do not find any wearout effects. Considering the positive effect of this incentive on donor retention and the relative low cost for providing this service to donors, our findings suggest that offering comprehensive blood health check incentives is a viable and cost-efficient marketing strategy to increase the retention among previous donors even if offered over the longer run.Accepted manuscrip

Control of a train of high purity distillation columns for efficient production of 13C isotopes

It is well-known that high-purity distillation columns are difficult to control due to their ill-conditioned and strongly nonlinear behaviour. The fact that these processes are operated over a wide range of feed compositions and flow rates makes the control design even more challenging. This paper proposes the most suitable control strategies applicable to a series of cascaded distillation column processes. The conditions for control and input-output relations are discusssed in view of the global control strategy. The increase in complexity with increased number of series cascaded distillation column processes is tackled. Uncertainty in the model parameters is discussed with respect to the dynamics of the global train distillation process. The main outcome of this work is insight into the possible control methodologies for this particular class of distillation processes

Visualizing probabilistic models: Intensive Principal Component Analysis

Unsupervised learning makes manifest the underlying structure of data without curated training and specific problem definitions. However, the inference of relationships between data points is frustrated by the `curse of dimensionality' in high-dimensions. Inspired by replica theory from statistical mechanics, we consider replicas of the system to tune the dimensionality and take the limit as the number of replicas goes to zero. The result is the intensive embedding, which is not only isometric (preserving local distances) but allows global structure to be more transparently visualized. We develop the Intensive Principal Component Analysis (InPCA) and demonstrate clear improvements in visualizations of the Ising model of magnetic spins, a neural network, and the dark energy cold dark matter ({\Lambda}CDM) model as applied to the Cosmic Microwave Background.Comment: 6 pages, 5 figure

Estimating economic and social welfare impacts of pension reform

This paper examines the impact of two effects of the pension reform package that the UK Government put forward in the May White Paper Security in retirement: the likely increase in the number of older people working due to a higher State Pension age and the likely rise in saving due to more people putting away money for retirement. The overall effect of changes to State Pension age and the introduction of personal accounts on UK incomes is likely to be in the range of 0.9 – 3.1 per cent. Although these numbers are relatively small proportions of the total economy, they represent significant sums. In terms of today’s economy, they would be worth around £11 – 38 billion. This paper also applies an innovative economic analysis to examine the scale of the increase in people’s wellbeing as a result of improved consumption smoothing. It finds that if people save for retirement through personal accounts, then generally their wellbeing will be enhanced.pension reform; consumption smoothing; social welfare

Trajectory-based differential expression analysis for single-cell sequencing data

Trajectory inference has radically enhanced single-cell RNA-seq research by enabling the study of dynamic changes in gene expression. Downstream of trajectory inference, it is vital to discover genes that are (i) associated with the lineages in the trajectory, or (ii) differentially expressed between lineages, to illuminate the underlying biological processes. Current data analysis procedures, however, either fail to exploit the continuous resolution provided by trajectory inference, or fail to pinpoint the exact types of differential expression. We introduce tradeSeq, a powerful generalized additive model framework based on the negative binomial distribution that allows flexible inference of both within-lineage and between-lineage differential expression. By incorporating observation-level weights, the model additionally allows to account for zero inflation. We evaluate the method on simulated datasets and on real datasets from droplet-based and full-length protocols, and show that it yields biological insights through a clear interpretation of the data. Downstream of trajectory inference for cell lineages based on scRNA-seq data, differential expression analysis yields insight into biological processes. Here, Van den Berge et al. develop tradeSeq, a framework for the inference of within and between-lineage differential expression, based on negative binomial generalized additive models

Generation of potential/surface density pairs in flat disks Power law distributions

We report a simple method to generate potential/surface density pairs in flat axially symmetric finite size disks. Potential/surface density pairs consist of a ``homogeneous'' pair (a closed form expression) corresponding to a uniform disk, and a ``residual'' pair. This residual component is converted into an infinite series of integrals over the radial extent of the disk. For a certain class of surface density distributions (like power laws of the radius), this series is fully analytical. The extraction of the homogeneous pair is equivalent to a convergence acceleration technique, in a matematical sense. In the case of power law distributions, the convergence rate of the residual series is shown to be cubic inside the source. As a consequence, very accurate potential values are obtained by low order truncation of the series. At zero order, relative errors on potential values do not exceed a few percent typically, and scale with the order N of truncation as 1/N**3. This method is superior to the classical multipole expansion whose very slow convergence is often critical for most practical applications.Comment: Accepted for publication in Astronomy & Astrophysics 7 pages, 8 figures, F90-code available at http://www.obs.u-bordeaux1.fr/radio/JMHure/intro2applawd.htm