Habitability of known exoplanetary systems based on measured stellar properties

At present, because of observational selection effects, we know of no exoplanetary systems with any planetary masses close to that of the Earth. We have therefore used computer models to see whether such planets could be dynamically stable in the presence of the more massive planets known to be present, and in particular whether planets with roughly an Earth mass could remain confined to the classical habitable zone (HZ) for long enough for life to have emerged. Measured stellar properties have been used to determine for each system the present location of the HZ. We have also determined the critical distances from the orbit of each giant planet within which an Earth-mass planet would suffer large orbital changes. We then evaluated the present habitability of each and every exoplanetary system by examining the penetration of these critical distances into the HZ. The critical distances can be obtained by extensive computer modelling of an exoplanetary system. This is far too time consuming to apply to all of the 150 or so systems already known, and to keep up with the latest discoveries. Therefore, in earlier work we studied a few systems in great detail, and developed a speedier means of obtaining the critical distances. We summarize this comparatively quick method here. We can then evaluate comparatively quickly the present habitability of each exoplanetary system by examining the penetration of the critical distance(s) into the HZ. The results are encouraging for astrobiology.Comment: Accepted for publication by The Astrophysical Journal. A few revisions have been made following suggestions by the refere

Shade as enrichment : testing preferences for shelter in two model fish species

N.A.R.J. was supported by an Fisheries Society of the British Isles studentship, F.M.J. by the St Andrews School of Biology and H.C.S.-J. by the John Templeton Foundation.We compared preferences shown by zebrafish Danio rerio and three‐spined stickleback Gasterosteus aculeatus for shelter provided by above‐tank shade and artificial plants. Zebrafish showed no preference for either shelter, whereas sticklebacks showed a preference for both shelter types over open areas and for shade over plants. Our results suggest shade may be used as enrichment for captive fish and re‐emphasise the importance of species‐specific welfare considerations.PostprintPeer reviewe

Dynamic communities in multichannel data: An application to the foreign exchange market during the 2007--2008 credit crisis

We study the cluster dynamics of multichannel (multivariate) time series by representing their correlations as time-dependent networks and investigating the evolution of network communities. We employ a node-centric approach that allows us to track the effects of the community evolution on the functional roles of individual nodes without having to track entire communities. As an example, we consider a foreign exchange market network in which each node represents an exchange rate and each edge represents a time-dependent correlation between the rates. We study the period 2005-2008, which includes the recent credit and liquidity crisis. Using dynamical community detection, we find that exchange rates that are strongly attached to their community are persistently grouped with the same set of rates, whereas exchange rates that are important for the transfer of information tend to be positioned on the edges of communities. Our analysis successfully uncovers major trading changes that occurred in the market during the credit crisis.Comment: 8 pages, 6 figures, accepted for publication in Chao

The Evolution of Private Equity: Corporate Restructuring in the UK, c.1945-2010

The paper analyses the role of private equity in restructuring the UK corporate economy. It develops a theoretical synthesis to show that the evolution of the PE industry and firms in which it invested were governed by the relations of corporate governance between investor and investee companies. Effective governance relations were a necessary condition for success and complement firm specific resources to create competitive advantage. Four case studies are used to show the contrasting effects of these determining factors, ICFC and Slater Walker, and the two waves of buy-out centred restructuring that developed with the maturity of the PE industry after 1980. In contrast to the evolutionary approach, the periodisations utilised in this study show that structural breaks associated with points of institutional reform are also necessary to make firm specific resource and governance determinants of competitive advantage operable

No experimental evidence of stress-induced hyperthermia in zebrafish (Danio rerio)

NJ was supported by a studentship from The Fisheries Society of The British Isles.Stress-induced hyperthermia (SIH) is characterised by a rise in body temperature in response to a stressor. In endotherms SIH is mediated by the autonomic nervous system, whereas ectotherms must raise their body temperature via behavioural means by moving to warmer areas within their environment (behavioural thermoregulation). A recent study suggested that zebrafish (Danio rerio), an important model species, may move to warmer water in response to handling and confinement and thus exhibit SIH, which, if accepted, may have important practical and welfare implications. However an alternative hypothesis proposed that the observed movements may been produced by avoidance behaviour rather than behavioural thermoregulation. Investigating the claims for SIH in zebrafish further we conducted two experiments that extend the earlier study. The first experiment incorporated new conditions that considered fish behaviour in the absence of thermal variation, i.e. their null distribution, an important condition that was not performed in the original study. The second was a refined version of the experiment to reduce the numbers of fish and aid movement between areas for the fish. In contrast to the previous study, we saw no effect of handling or confinement on preference for warmer areas, and no evidence for SIH in either experiment. Instead we observed a short-lived reduction in preference for warmer areas immediately post stress. Our work suggests that zebrafish may not experience SIH and claims regarding fish consciousness based on SIH may need to be revised.PostprintPeer reviewe

Detection of Infectious Disease Outbreaks From Laboratory Data With Reporting Delays

Many statistical surveillance systems for the timely detection of outbreaks of infectious disease operate on laboratory data. Such data typically incur reporting delays between the time at which a specimen is collected for diagnostic purposes, and the time at which the results of the laboratory analysis become available. Statistical surveillance systems currently in use usually make some ad hoc adjustment for such delays, or use counts by time of report. We propose a new statistical approach that takes account of the delays explicitly, by monitoring the number of specimens identified in the current and past m time units, where m is a tuning parameter. Values expected in the absence of an outbreak are estimated from counts observed in recent years (typically 5 years). We study the method in the context of an outbreak detection system used in the United Kingdom and several other European countries. We propose a suitable test statistic for the null hypothesis that no outbreak is currently occurring. We derive its null variance, incorporating uncertainty about the estimated delay distribution. Simulations and applications to some test datasets suggest the method works well, and can improve performance over ad hoc methods in current use. Supplementary materials for this article are available online

A revised edition of the readiness to change questionnaire (treatment version)

The UK Alcohol Treatment Trial provided an opportunity to examine the factor structure of the Readiness to Change Questionnaire-Treatment Version (RCQ[TV]) in a large sample (N = 742) of individuals in treatment for alcohol problems who were given the RCQ[TV] at baseline, 3-months and 12-months follow-up. Confirmatory factor analysis of the previously reported factor structure (5 items for each of Precontemplation, Contemplation and Action scales) resulted in a relatively poor fit to the data. Removal of one item from each of the scales resulted in a 12-item instrument for which goodness-of-fit indices were improved, without loss of internal consistency of the three scales, on all three measurement occasions. Inspection of relationships between stage allocation by the new instrument and negative alcohol outcome expectancies provided evidence of improved construct validity for the revised edition of the RCQ[TV]. There was also a strong relationship between stage allocation at 3-months follow-up and outcome of treatment at 12 months. The revised edition of the RCQ[TV] offers researchers and clinicians a shorter and improved measurement of stage of change in the alcohol treatment population

Presence of an audience and consistent interindividual differences affect archerfish shooting behaviour

This study was funded by the Fisheries Society of the British Isles (studentship to N.A.R.J.).The social environment can play an important role in shaping the foraging behaviour of animals. In this study we investigated whether archerfish, Toxotes jaculatrix, display any behavioural changes in response to the presence of an audience while using their specialized foraging tactic of shooting, spitting precisely aimed jets of water, at prey targets. As any prey items shot down are potentially available to competitors, we hypothesized that shooting fish would be sensitive to the presence of potential competitors, especially given the suggestion that, in the wild, this species shows intraspecific kleptoparasitism and faces interspecific competition. We found that in the presence of another fish, archerfish took longer to shoot, made more orientations (aiming events) per shot, and tended to be closer to the target at the time of shooting. Additionally, archerfish showed high interindividual differences in latency to shoot, and these differences were consistent across contexts, with and without an audience. Our results show that archerfish are sensitive to, and adjust their shooting behaviour in response to, the presence of an audience and highlight the importance of social context in this fish species. We also suggest that interindividual differences may play an important role in archerfish shooting behaviour. This study highlights the importance of social effects and competition on foraging behaviour and decision making. Further work in this species could explore whether differences in competitive foraging ability are linked to sensitivity to the presence of an audience.PostprintPeer reviewe

The effect of high dose antibiotic impregnated cement on rate of surgical site infection after hip hemiarthroplasty for fractured neck of femur : a protocol for a double-blind quasi randomised controlled trial

Background: Mortality following hip hemiarthroplasty is in the range of 10-40% in the first year, with much attributed to post-operative complications. One such complication is surgical site infection (SSI), which at the start of this trial affected 4.68% of patients in the UK having this operation. Compared to SSI rates of elective hip surgery, at less than 1%, this figure is elevated. The aim of this quasi randomised controlled trial (RCT) is to determine if high dose antibiotic impregnated cement can reduce the SSI in patients at 12-months after hemiarthroplasty for intracapsular fractured neck of femur. Methods: 848 patients with an intracapsular fractured neck of femur requiring a hip hemiarthroplasty are been recruited into this two-centre double-blind quasi RCT. Participants were recruited before surgery and quasi randomised to standard care or intervention group. Participants, statistician and outcome assessors were blind to treatment allocation throughout the study. The intervention consisted of high dose antibiotic impregnated cement consisting of 1 gram Clindamycin and 1 gram of Gentamicin. The primary outcome is Health Protection Agency (HPA) defined deep surgical site infection at 12 months. Secondary outcomes include HPA defined superficial surgical site infection at 30 days, 30 and 90-day mortality, length of hospital stay, critical care stay, and complications. Discussion: Large randomised controlled trials assessing the effectiveness of a surgical intervention are uncommon, particularly in the speciality of orthopaedics. The results from this trial will inform evidence-based recommendations for antibiotic impregnated cement in the management of patients with a fractured neck of femur undergoing a hip hemiarthroplasty. If high dose antibiotic impregnated cement is found to be an effective intervention, implementation into clinical practice could improve long-term outcomes for patients undergoing hip hemiarthroplasty