An improved method for estimating source densities using the temporal distribution of Cosmological Transients

It has been shown that the observed temporal distribution of transient events in the cosmos can be used to constrain their rate density. Here we show that the peak flux--observation time relation takes the form of a power law that is invariant to the luminosity distribution of the sources, and that the method can be greatly improved by invoking time reversal invariance and the temporal cosmological principle. We demonstrate how the method can be used to constrain distributions of transient events, by applying it to Swift gamma-ray burst data and show that the peak flux--observation time relation is in good agreement with recent estimates of source parameters. We additionally show that the intrinsic time dependence allows the method to be used as a predictive tool. Within the next year of Swift observation, we find a 50% chance of obtaining a peak flux greater than that of GRB 060017 -- the highest Swift peak flux to date -- and the same probability of detecting a burst with peak flux > 100 photons s^{-1} cm^{-2} within 6 years.Comment: Submitted to ApJ Letter

Using temporal distributions of transient events to characterize cosmological source populations

The brightest events in a time series of cosmological transients obey an observation time dependence which is often overlooked. This dependence can be exploited to probe the global properties of electromagnetic and gravitational wave transients (Howell et al. 2007a, Coward & Burman 2005). We describe a new relation based on a peak flux--observation time distribution and show that it is invariant to the luminosity distribution of the sources (Howell et al. 2007b). Applying this relation, in combination with a new data analysis filter, to \emph{Swift} gamma-ray burst data, we demonstrate that it can constrain their rate density.Comment: published in proceedings of FRONTIERS OF FUNDAMENTAL AND COMPUTATIONAL PHYSICS: 10th International Symposium, AIP,1246,203, (2010

Is there a link between treatments with exogenous corticosteroids and dog behaviour problems?

Possible side effects of exogenous corticosteroids have been described in both humans and laboratory animals, with recent studies highlighting this issue in dogs. In this paper the behaviour of 345 dogs drawn from the caseload of a behaviour clinic based in the north of Italy between February 2012 and November 2014 were analysed. Possible relationships between dogs that received treatment with corticosteroids versus dogs that received treatment with drugs other than corticosteroids and positive or negative affective states, aggression towards people, other behaviour problems apart from aggression, occurrence of severe bites, and prescription of psychoactive drugs were initially assessed using a Pearson's chi-squared test. Regression analysis was then performed in order to evaluate the best predictors of the investigated items. The goal of this retrospective survey was to investigate possible relationships between the affective states associated with the behavioural complaint of dogs and their previous history of treatment with corticosteroids. Results showed that a history of corticosteroid treatment was a significant predictor of a range of behaviour problems associated with negative affective state, but this result may be confounded by age-related effects

Edge-based nonlinear diffusion for finite element approximations of convection–diffusion equations and its relation to algebraic flux-correction schemes

The final publication is available at Springer via http://dx.doi.org/10.1007/s00211-016-0808-zFor the case of approximation of convection–diffusion equations using piecewise affine continuous finite elements a new edge-based nonlinear diffusion operator is proposed that makes the scheme satisfy a discrete maximum principle. The diffusion operator is shown to be Lipschitz continuous and linearity preserving. Using these properties we provide a full stability and error analysis, which, in the diffusion dominated regime, shows existence, uniqueness and optimal convergence. Then the algebraic flux correction method is recalled and we show that the present method can be interpreted as an algebraic flux correction method for a particular definition of the flux limiters. The performance of the method is illustrated on some numerical test cases in two space dimensions

Building Schools for the Future: Lessons Learned From Performance Evaluations of Five Secondary Schools and Academies in England

Building performance evaluations (BPE) of five secondary schools and academies constructed under the Building Schools for the Future (BSF) programme in England found that CO2 emissions associated with operational energy performance in all these buildings is higher than the median of the secondary schools. Whilst the new regulatory requirements for building fabric performance have led to some improvements in heating energy when compared against good practice and typical benchmarks, there is still significant discrepancy between heating energy use and the design expectations. Electricity use in these buildings is also 37–191% more than the median school and significantly worse than the design expectations. These results point to the importance of post-occupancy building fine-tuning and measurement and verification of performance in-use with respect to design projections to narrow the performance gap. It is also necessary to set out clear operational performance targets and protect energy efficiency measures from value engineering throughout building procurement and in operation to achieve good level of performance. Finally, it is suggested to adopt a holistic view of energy, environmental quality, and educational performance to have a better understanding of schools' performance and potential conflicts between energy efficiency measures and indoor environmental quality (IEQ)

Dislocation-mediated growth of bacterial cell walls

Recent experiments have illuminated a remarkable growth mechanism of rod-shaped bacteria: proteins associated with cell wall extension move at constant velocity in circles oriented approximately along the cell circumference (Garner et al., Science (2011), Dominguez-Escobar et al. Science (2011), van Teeffelen et al. PNAS (2011). We view these as dislocations in the partially ordered peptidoglycan structure, activated by glycan strand extension machinery, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Generation and motion of these interacting defects lead to surprising effects arising from the cylindrical geometry, with important implications for growth. We also discuss how long range elastic interactions and turgor pressure affect the dynamics of the fraction of actively moving dislocations in the bacterial cell wall.Comment: to appear in PNA

A Cut Finite Element Method for the Bernoulli Free Boundary Value Problem

We develop a cut finite element method for the Bernoulli free boundary problem. The free boundary, represented by an approximate signed distance function on a fixed background mesh, is allowed to intersect elements in an arbitrary fashion. This leads to so called cut elements in the vicinity of the boundary. To obtain a stable method, stabilization terms is added in the vicinity of the cut elements penalizing the gradient jumps across element sides. The stabilization also ensures good conditioning of the resulting discrete system. We develop a method for shape optimization based on moving the distance function along a velocity field which is computed as the $H^1$ Riesz representation of the shape derivative. We show that the velocity field is the solution to an interface problem and we prove an a priori error estimate of optimal order, given the limited regularity of the velocity field across the interface, for the the velocity field in the $H^1$ norm. Finally, we present illustrating numerical results

Play in rats: association across contexts and types, and analysis of structure

Play has been proposed as a promising indicator of positive animal welfare. We aimed to study play in rats across contexts (conspecific/heterospecific) and types (social: pinning, being pinned; solitary: scampering), and we investigated its structure using behavioral sequence analysis. Group-housed (three per cage) adolescent male Lister Hooded rats (n = 21) were subjected to a Play-In-Pairs test: after a 3 hour isolation period, a pair of cage-mates was returned to the home cage and both social and solitary play were scored for 20 min. This procedure was repeated for each pair combination across three consecutive days, and individual play scores were calculated. Heterospecific play was measured using a Tickling test: rats were individually tickled by the experimenter through bouts of gentle, rapid finger movements on their underside, and the number of positive 50 kHz frequency modulated vocalizations and experimenter-directed approach behaviors were recorded. Both of the above tests were compared with social play in the home cage. While conspecific play in both the Play-In-Pairs test and home cage were correlated, both seemed to be unrelated to heterospecific play in the Tickling test. During the Play-In-Pairs test, although both solitary and social play types occurred, they were unrelated, and solitary locomotor play of one rat did not predict the subsequent play behavior of its cage mate. Analysis of play structure revealed that social play occurred more often in bouts of repeated behaviors while solitary play sequences did not follow a specific pattern. If play is to be used as an indicator of positive welfare in rats, context, type and structure differences should be taken into account