Optimal trading strategies - a time series approach

Motivated by recent advances in the spectral theory of auto-covariance matrices, we are led to revisit a reformulation of Markowitz' mean-variance portfolio optimization approach in the time domain. In its simplest incarnation it applies to a single traded asset and allows to find an optimal trading strategy which - for a given return - is minimally exposed to market price fluctuations. The model is initially investigated for a range of synthetic price processes, taken to be either second order stationary, or to exhibit second order stationary increments. Attention is paid to consequences of estimating auto-covariance matrices from small finite samples, and auto-covariance matrix cleaning strategies to mitigate against these are investigated. Finally we apply our framework to real world data

Inequalities in Health and Service Use among People with Borderline Intellectual Impairment

This report, produced in collaboration with Professor Angela Hassiotis and others, sets out the extent to which people with borderline intellectual impairment face inequalities in health and use of services compared with the rest of the population, and seeks to improve awareness of these inequalities. Findings - Borderline intellectual impairment is common, affecting at least one adult in ten in England. The term is used here to refer to people with good verbal skills and living in private households, but who may experience cognitive impairments. - The findings in this report are consistent with previous research: people with borderline intellectual impairment are a disadvantaged group and their needs are not well understood. - Such adults face high levels of poor mental health, poorer general health, and many limitations in their daily lives. - Their level of use of mental health treatment and services does not appear to be commensurate with their higher level of need. This indicates that they are underserved compared with the rest of the population. - This may be due to a lack of professional awareness of their needs, to services not adapting enough to meet those needs, or to difficulties the individual faces in seeking treatment and support. - Adults with borderline intellectual impairment constitute key users of primary and secondary health care, and employment, education and welfare support. Improving awareness of the needs of this group should form part of wider plans to reduce inequalities in health and service use in England. Methods Secondary analysis of data from the Adult Psychiatric Morbidity Survey (APMS) was conducted to profile the circumstances of people with borderline intellectual impairment. APMS is one of the most authoritative and comprehensive national household surveys to assess both intellectual functioning and mental health in adults in England

Explaining Spatial Diversity in Latin American Rural Development: Structures, Institutions, and Coalitions

SummaryThis article summarizes the results of a research program conducted in 11 Latin America countries, addressing two questions: (1) what factors determine territorial development dynamics that lead to economic growth, poverty reduction, and improved income distribution? (2) What can be done to stimulate this kind of territorial dynamics? We highlight five “bundles of factors” that we found in 19 case studies of territorial development1,1In fact, 20 case studies were started, but the final report of one of them was not accepted during the program’s quality control process, and thus we never considered this case study in our analyses. as well as the role of social territorial coalitions that appear to be necessary for territorial dynamics that lead to economic growth with social inclusion. The article calls for territorial development policies to complement sectoral policies

Prevalence of psychosis in black ethnic minorities in Britain: analysis based on three national surveys

Purpose A considerable excess of psychosis in black ethnic minorities is apparent from clinical studies, in Britain, as in other developed economies with white majority populations. This excess is not so marked in population surveys. Equitable health service provision should be informed by the best estimates of the excess. We used national survey data to establish the difference in the prevalence of psychosis between black ethnic groups and the white majority in the British general population. Methods Analysis of the combined datasets (N = 26,091) from the British national mental health surveys of 1993, 2000 and 2007. Cases of psychosis were determined either by the use of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), or from a combination of screening items. We controlled for sex, age, social class, unemployment, design features and other putative confounders, using a Disease Risk Score. Results People from black ethnic minorities had an excess prevalence rate of psychosis compared with the white majority population. The OR, weighted for study design and response rate, was 2.72 (95 % CI 1.3–5.6, p = 0.002). This was marginally increased after controlling for potential confounders (OR = 2.90, 95 % CI 1.4–6.2, p = 0.006). Conclusions The excess of psychosis in black ethnic minority groups was similar to that in two previous British community surveys, and less than that based on clinical studies. Even so it confirms a considerable need for increased mental health service resources in areas with high proportions of black ethnic minority inhabitants

Rare Earth Doped Silica for Integrated Optical Waveguide Lasers and Amplifiers

The aim of the project was to realise rare earth doped planar silica waveguide lasers. Research centred on two rare earth ions: neodymium taking advantage of the four level laser system near 1.05 mum and erbium with emission at 1.54 mum, in the important third telecommunication window. Research concentrated on SiO2-P2O5 glass films fabricated by the flame hydrolysis of SiCl4 and PCI3. The resultant low density glass soot was deposited onto silica or oxidised silicon substrates, which was then sintered at temperatures up to 135

Resource extraction and infrastructure threaten forest cover and community rights

Mineral and hydrocarbon extraction and infrastructure are increasingly significant drivers of forest loss, greenhouse gas emissions, and threats to the rights of forest communities in forested areas of Amazonia, Indonesia, and Mesoamerica. Projected investments in these sectors suggest that future threats to forests and rights are substantial, particularly because resource extraction and infrastructure reinforce each other and enable population movements and agricultural expansion further into the forest. In each region, governments have made framework policy commitments to national and cross-border infrastructure integration, increased energy production, and growth strategies based on further exploitation of natural resources. This reflects political settlements among national elites that endorse resource extraction as a pathway toward development. Regulations that protect forests, indigenous and rural peoples’ lands, and conservation areas are being rolled back or are under threat. Small-scale gold mining has intensified in specific locations and also has become a driver of deforestation and degradation. Forest dwellers’ perceptions of insecurity have increased, as have documented homicides of environmental activists. To explain the relationships among extraction, infrastructure, and forests, this paper combines a geospatial analysis of forest loss overlapped with areas of potential resource extraction, interviews with key informants, and feedback from stakeholder workshops. The increasing significance of resource extraction and associated infrastructure as drivers of forest loss and rights violations merits greater attention in the empirical analyses and conceptual frameworks of Sustainability Science

Psychological mechanisms mediating effects between trauma and psychotic symptoms: the role of affect regulation, intrusive trauma memory, beliefs, and depression

Evidence suggests a causal role for trauma in psychosis, particularly for childhood victimization. However, the establishment of underlying trauma-related mechanisms would strengthen the causal argument. In a sample of peo-ple with relapsing psychosis (n = 228), we tested hypoth-esized mechanisms specifically related to impaired affect regulation, intrusive trauma memory, beliefs, and depres-sion. The majority of participants (74.1%) reported vic-timization trauma, and a fifth (21.5%) met symptomatic criteria for Posttraumatic Stress Disorder. We found a specific link between childhood sexual abuse and auditory hallucinations (adjusted OR = 2.21, SE = 0.74, P = .018). This relationship was mediated by posttraumatic avoid-ance and numbing (OR = 1.48, SE = 0.19, P = .038) and hyperarousal (OR = 1.44, SE = 0.18, P = .045), but not intrusive trauma memory, negative beliefs or depression. In contrast, childhood emotional abuse was specifically associated with delusions, both persecutory (adjusted OR = 2.21, SE = 0.68, P = .009) and referential (adjusted OR = 2.43, SE = 0.74, P = .004). The link with persecutory delusions was mediated by negative-other beliefs (OR = 1.36, SE = 0.14, P = .024), but not posttraumatic stress symptoms, negative-self beliefs, or depression. There was no evidence of mediation for referential delusions. No rela-tionships were identified between childhood physical abuse and psychosis. The findings underline the role of cognitive-affective processes in the relationship between trauma and symptoms, and the importance of assessing and treating victimization and its psychological consequences in people with psychosis

The evolution of delayed dispersal and different routes to breeding in social birds

Many animals live in stable groups, where sexually mature individuals delay dispersal and stay as nonbreeding subordinates, seemingly counter to their own evolutionary interests. Revealing what circumstances drive the evolution of delayed dispersal is central to understanding sociality, family living and cooperative breeding across the animal kingdom, but there is as yet no general consensus about the relative importance of the various ecological and social conditions and the reproductive benefits proposed to drive delayed dispersal. We argue that two components may facilitate further progress in this respect: firstly, full consideration of the various routes that individuals can follow to obtain an independent breeding position. Here, we provide a comprehensive review of these routes: inheritance of a natal territory, budding off part of the natal territory, shifting to a neighboring vacancy, making temporary prospecting trips throughout the population; or permanently leaving to float in search of a breeding position or to stage as subordinate in a non-natal territory. Second, we illustrate that in order to understand delayed dispersal, we need to consider that the fitness consequences of these different routes apply across the lifetime: as subordinate (e.g., benefits of philopatry and indirect fitness); while waiting or searching for a position; and after obtaining a breeding position. Overall, we conclude that by which route and under what circumstances individuals can obtain a breeding position must be considered in order to make more comprehensive inferences about the evolution of delayed dispersal, cooperative breeding and animal sociality as a whole.</p

Delayed dispersal and the cost and benefits of different routes to independent breeding in a cooperative breeding bird

Why sexually mature individuals stay in groups as non-reproductive subordinates is central to the evolution of sociality and cooperative breeding. To understand such delayed dispersal, its costs and benefits need to be compared with those of permanently leaving to float through the population. However, comprehensive comparisons, especially regarding differences in future breeding opportunities, are rare. Moreover, extra-territorial prospecting by philopatric individuals has generally been ignored, even though the factors underlying this route to independent breeding may differ from those of strict philopatry or floating. We use a comprehensive predictive framework to explore how various costs, benefits and intrinsic, environmental and social factors explain philopatry, prospecting and floating in Seychelles warblers (Acrocephalus sechellensis). Floaters more likely obtained an independent breeding position before the next season than strictly philopatric individuals, but also suffered higher mortality. Prospecting yielded similar benefits to floating but lower mortality costs, suggesting that it is overall more beneficial than floating and strict philopatry. Whereas prospecting is probably individual-driven, though limited by resource availability, floating likely results from eviction by unrelated breeders. Such differences in proximate and ultimate factors underlying each route to independent breeding highlight the need for simultaneous consideration when studying the evolution of delayed dispersal