An Overview of Managed Futures' Performance: 1983 to Post-2008 Credit Crisis

The growth of the managed futures industry increased dramatically in the late 1970s after the introduction of the world's first financial futures contracts (foreign currency futures) by the Chicago Mercantile Exchange in 1972. The first published academic research on the performance of managed futures appeared in the 1980s. Researchers who adopted similar performance metrics to assess managed futures in different time periods reached similar conclusions as earlier studies about the benefits of managed futures. Some recent studies address the issues of performance persistence and market-timing ability of managed futures traders. Following the onset of the financial crisis of 2007-2008, researchers also reassessed the diversification benefits of managed futures and the low correlations of their returns with those of stocks and bonds. Evidence reaffirmed that the favorable characteristics of managed futures investments were useful for investors looking for a "crisis alpha" for their portfolios in periods with high market volatility. © 2013 John Wiley & Sons, Inc. All rights reserved

The Buckland Park air shower array

The new Buckland Park Air Shower Array has been producing analyzed shower data since July 1984. The array is described and some preliminary performance figures are presented

The specialty choices of graduates from Brighton and Sussex Medical School: a longitudinal cohort study

BACKGROUND Since 2007 junior doctors in the UK have had to make major career decisions at a point when previously many had not yet chosen a specialty. This study examined when doctors in this new system make specialty choices, which factors influence choices, and whether doctors who choose a specialty they were interested in at medical school are more confident in their choice than those doctors whose interests change post-graduation. METHODS Two cohorts of students in their penultimate year at one medical school (n = 227/239) were asked which specialty interested them as a career. Two years later, 210/227 were sent a questionnaire measuring actual specialty chosen, confidence, influence of perceptions of the specialty and experiences on choice, satisfaction with medicine, personality, self-efficacy, and demographics. Medical school and post-graduation choices in the same category were deemed 'stable'. Predictors of stability, and of not having chosen a specialty, were calculated using bootstrapped logistic regression. Differences between specialties on questionnaire factors were analysed. RESULTS 50% responded (n = 105/277; 44% of the 239 Year 4 students). 65% specialty choices were 'stable'. Factors univariately associated with stability were specialty chosen, having enjoyed the specialty at medical school or since starting work, having first considered the specialty earlier. A regression found doctors who chose psychiatry were more likely to have changed choice than those who chose general practice. Confidence in the choice was not associated with stability. Those who chose general practice valued lifestyle factors. A psychiatry choice was associated with needing a job and using one's intellect to help others. The decision to choose surgical training tended to be made early. Not having applied for specialty training was associated with being lower on agreeableness and conscientiousness. CONCLUSION Medical school experiences are important in specialty choice but experiences post-graduation remain significant, particularly in some specialties (psychiatry in our sample). Career guidance is important at medical school and should be continued post-graduation, with senior clinicians supported in advising juniors. Careers advice in the first year post-graduation may be particularly important, especially for specialties which have difficulty recruiting or are poorly represented at medical school

Incidence, Costs and Predictors of Non-Union, Delayed Union and Mal-Union Following Long Bone Fracture

Fracture healing complications are common and result in significant healthcare burden. The aim of this study was to determine the rate, costs and predictors of two-year readmission for surgical management of healing complications (delayed, mal, non-union) following fracture of the humerus, tibia or femur. Humeral, tibial and femoral (excluding proximal) fractures registered by the Victorian Orthopaedic Trauma Outcomes Registry over five years (n = 3962) were linked with population-level hospital admissions data to identify two-year readmissions for delayed, mal or non-union. Study outcomes included hospital length-of-stay (LOS) and inpatient costs. Multivariable logistic regression was used to determine demographic and injury-related factors associated with admission for fracture healing complications. Of the 3886 patients linked, 8.1% were readmitted for healing complications within two years post-fracture, with non-union the most common complication and higher rates for femoral and tibial shaft fractures. Admissions for fracture healing complications incurred total costs of $4.9 million AUD, with a median LOS of two days. After adjusting for confounders, patients had higher odds of developing complications if they were older, receiving compensation or had tibial or femoral shaft fractures. Patients who are older, with tibial and femoral shaft fractures should be targeted for future research aimed at preventing complications

Invasive species control: incorporating demographic data and seed dispersal into a management model for Rhododendron ponticum

Rhododendron ponticum is a serious invasive alien plant in the British Isles and is of significant conservation and economic concern. Here, we integrate information on both the life-history and spatial dynamics of this species within an individual-based, spatially-explicit model and investigate the effectiveness of different control strategies. Importantly, we simulate seed movement and dispersal using a mechanistic seed dispersal model. We investigate the effectiveness of initiating control at the edge versus the core of the infestation, with and without returning each year to remove seedlings. We compare these results to an age-dependent strategy whereby the oldest plants are removed each year. Age-dependent control, in which the oldest plants were removed first, was the most effective strategy investigated, both in terms of the probability of successful eradication and the number of years taken to control. We demonstrate that this is because the older (and taller) plants towards the core produce more seeds that, on average, travel further. Indeed, our results suggest that the expansion of the invading front is actually driven as much by seeds that disperse long distances from these larger plants as by the seed rain from recently matured plants located much closer to the front. Finally, we investigate the potential use of ‘quarantine lines’ - corridors of unsuitable habitat that are sufficiently wide to contain an infestation, preventing spread to vulnerable areas. This study has provided generic insights into best practice for management based on the current understanding of the biology and ecology of this pernicious, invasive plant

Effect of Smoke-Free Legislation on Adult Smoking Behaviour in England in the 18 Months following Implementation

Comprehensive smoke-free legislation covering all enclosed public places and workplaces was implemented in England on 1 July 2007. This study examines the impact of this legislation on smoking prevalence, number of cigarettes smoked and location of smoking, controlling for secular trends through the end of 2008.Repeat cross sectional survey using nationally representative data from the Health Survey for England (HSE). In total there are 54,333 respondents from 2003-2008. Logit and linear regression models were used to examine the effect of the legislation on smoking prevalence and the number of cigarettes smoked daily among continuing smokers which took the underlying trend into account. Our finding suggest that smoking prevalence (current smoker) decreased from 25% in 2003 to 21% in 2008 (AOR = 0.96 per year, 95% CI = 0.95-0.98, P<0.01) and the mean number of cigarettes consumed daily by smokers decreased from 14.1 in 2003 to 13.1 in 2008 (coefficient for time trend = -0.28±0.06 SE cig/day per year, P<0.01). After adjusting for these trends the introduction of smoke-free legislation was not associated with additional reductions in smoking prevalence (AOR = 1.02, 95% CI = 0.94-1.11, P = 0.596) or daily cigarette use in smokers (0.42±0.28 SE; P = 0.142). The percentage of respondents reporting smoking 'at work' and 'inside pubs or bars' decreased significantly from 14% to 2% (p<0.001) and from 34% to 2% (p<0.001), respectively, after the legislation. The percentage reporting smoking 'inside restaurants, cafes, or canteens' decreased significantly from 9% to 1% (p<0.001) and 'inside their home' decreased significantly from 65% to 55% (p<0.01).There is widespread compliance with the smoke-free legislation in England, which has led to large drops in indoor smoking in all venues, including at home. Declines in smoking prevalence and consumption continued along existing trends; they did not accelerate during the 18 months immediately following implementation

Decoupled diversity dynamics in green and brown webs during primary succession in a salt marsh

1.Terrestrial ecosystems are characterised by a strong functional connection between the green (plant-herbivore-based) and brown (detritus-detritivore-based) parts of the food web, which both develop over successional time. However, the interlinked changes in green and brown food web diversity patterns in relation to key ecosystem processes are rarely studied. 2.Here, we demonstrate changes in species richness, diversity and evenness over a wide range of invertebrate green and brown trophic groups during 100 years of primary succession in a salt marsh ecosystem, using a well-calibrated chronosequence. 3.We contrast two hypotheses on the relationship between green and brown food web diversity across succession: i) ‘coupled diversity hypothesis’, which predicts that all trophic groups covary similarly with the main drivers of successional ecosystem assembly versus ii) the ‘decoupled diversity hypothesis’, where green and brown trophic groups diversity respond to different drivers during succession. 4.We found that, while species richness for plants and invertebrate herbivores (green web groups) both peaked at intermediate productivity and successional age, the diversity of macro-detritivores, microarthropod microbivores and secondary consumers (brown web groups) continuously increased towards the latest successional stages. These results suggest that green web trophic groups are mainly driven by vegetation parameters, such as the amount of bare soil, vegetation biomass production, and vegetation height, while brown web trophic groups are mostly driven by the production and standing stock of dead organic material and soil development. 5.Our results show that plant diversity cannot simply be used as a proxy for the diversity of all other species groups that drive ecosystem functioning, as brown and green diversity components in our ecosystem responded differently to successional gradients

Animal Ecosystem Engineers Modulate the Diversity-Invasibility Relationship

Invasions of natural communities by non-indigenous species are currently rated as one of the most important global-scale threats to biodiversity. Biodiversity itself is known to reduce invasions and increase stability. Disturbances by ecosystem engineers affect the distribution, establishment, and abundance of species but this has been ignored in studies on diversity-invasibility relationships.We determined natural plant invasion into 46 plots varying in the number of plant species (1, 4, and 16) and plant functional groups (1, 2, 3, and 4) for three years beginning two years after the establishment of the Jena Experiment. We sampled subplots where earthworms were artificially added and others where earthworm abundance was reduced. We also performed a seed-dummy experiment to investigate the role of earthworms as secondary seed dispersers along a plant diversity gradient. Horizontal dispersal and burial of seed dummies were significantly reduced in subplots where earthworms were reduced in abundance. Seed dispersal by earthworms decreased with increasing plant species richness and presence of grasses but increased in presence of small herbs. These results suggest that dense vegetation inhibits the surface activity of earthworms. Further, there was a positive relationship between the number of earthworms and the number and diversity of invasive plants. Hence, earthworms decreased the stability of grassland communities against plant invasion.Invasibility decreased and stability increased with increasing plant diversity and, most remarkably, earthworms modulated the diversity-invasibility relationship. While the impacts of earthworms were unimportant in low diverse (low earthworm densities) and high diverse (high floral structural complexity) plant communities, earthworms decreased the stability of intermediate diverse plant communities against plant invasion. Overall, the results document that fundamental processes in plant communities like plant seed burial and invader establishment are modulated by soil fauna calling for closer cooperation between soil animal and plant ecologists

Corporate bond liquidity before and after the onset of the subprime crisis

We analyze liquidity components of corporate bond spreads during 2005–2009 using a new robust illiquidity measure. The spread contribution from illiquidity increases dramatically with the onset of the subprime crisis. The increase is slow and persistent for investment grade bonds while the effect is stronger but more short-lived for speculative grade bonds. Bonds become less liquid when financial distress hits a lead underwriter and the liquidity of bonds issued by financial firms dries up under crises. During the subprime crisis, flight-to-quality is confined to AAA-rated bonds