The effect of asymmetries on stock index return value-at-risk estimates

It is widely accepted that equity return volatility increases more following negative shocks rather than positive shocks. However, much of value-at-risk (VaR) analysis relies on the assumption that returns are normally distributed (a symmetric distribution). This article considers the effect of asymmetries on the evaluation and accuracy of VaR by comparing estimates based on various models

Learning Objects, Learning Objectives and Learning Design.

Educational research and development into e-learning mainly focuses on the inclusion of new technological features without taking into account psycho-pedagogical concerns that are likely to improve a learner's cognitive process in this new educational category. This paper presents an instructional model that combines objectivist and constructivist learning theories. The model is based on the concept of a learning objective which is composed of a set of learning objects. A software tool, called the Instruction Aid System (IAS), has been developed to guide instructors through the development of learning objectives and the execution of the analysis and design phases of the proposed instructional model. Additionally, a blended approach to the learning process in Web-based distance education is also presented. This approach combines various event-based activities: self-paced learning, live e-learning and the use of face-to-face contact in classrooms

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Discovery and functional prioritization of Parkinson's disease candidate genes from large-scale whole exome sequencing.

BACKGROUND: Whole-exome sequencing (WES) has been successful in identifying genes that cause familial Parkinson's disease (PD). However, until now this approach has not been deployed to study large cohorts of unrelated participants. To discover rare PD susceptibility variants, we performed WES in 1148 unrelated cases and 503 control participants. Candidate genes were subsequently validated for functions relevant to PD based on parallel RNA-interference (RNAi) screens in human cell culture and Drosophila and C. elegans models. RESULTS: Assuming autosomal recessive inheritance, we identify 27 genes that have homozygous or compound heterozygous loss-of-function variants in PD cases. Definitive replication and confirmation of these findings were hindered by potential heterogeneity and by the rarity of the implicated alleles. We therefore looked for potential genetic interactions with established PD mechanisms. Following RNAi-mediated knockdown, 15 of the genes modulated mitochondrial dynamics in human neuronal cultures and four candidates enhanced α-synuclein-induced neurodegeneration in Drosophila. Based on complementary analyses in independent human datasets, five functionally validated genes-GPATCH2L, UHRF1BP1L, PTPRH, ARSB, and VPS13C-also showed evidence consistent with genetic replication. CONCLUSIONS: By integrating human genetic and functional evidence, we identify several PD susceptibility gene candidates for further investigation. Our approach highlights a powerful experimental strategy with broad applicability for future studies of disorders with complex genetic etiologies

Characterising Scotland's marine environment to define search locations for new Marine Protected Areas. Part 2, the identification of key geodiversity areas in Scottish waters (interim report July 2011)

Legislation introduced through the Marine (Scotland) Act 2010 and the Marine and Coastal Access Act 2009 will enable Scottish Ministers to establish Nature Conservation Marine Protected Areas (MPAs) within Scottish territorial and offshore waters. Guidelines for the selection of MPAs in waters adjacent to Scotland have been drafted by Marine Scotland, Scottish Natural Heritage (SNH) and the Joint Nature Conservation Committee (JNCC). These guidelines highlight the need to identify the key biodiversity and geodiversity areas in Scottish waters through a robust scientific framework with supporting justification. This report focuses on the latter theme, namely the identification of key geodiversity areas in Scottish waters. It is the second in a series of four reports that together support the development of a wider process to define MPA search locations. Section 2 of this report outlines the development of a methodology to prioritise key geodiversity areas in Scottish waters. This methodology is closely based on the Geological Conservation Review (GCR) scientific framework for the identification and prioritisation of important aspects of Earth heritage in the terrestrial environment. However, subtle amendments to the existing GCR methodology were introduced in order to ensure consistency with the Scottish MPA selection guidelines. These guidelines prioritise areas that: (i) contain key features considered of national or international importance; (ii) contain features considered to be under threat and / or subject to rapid decline; and/or (iii) are of functional significance for the overall health and diversity of Scottish Seas. Section 3 of this report provides details of the key geodiversity areas identified in Scottish waters. The list of key geodiversity areas was compiled using the GCR-style scientific framework and is based on expert judgement and the recommendations from a workshop in February 2010 attended by a range of leading Earth scientists with expertise in the Scottish marine environment. Supporting statements and scientific justifications for the selection of the key geodiversity areas include summary literature reviews, overviews of data availability and lists of relevant publications

Multichord spectroscopy of the DIII-D divertor region

A multichannel spectrometer with high spectral resolution (0.01 nm) and high temporal resolution (0.5 msec) has been configured to collect data simultaneously from eight viewchords spanning the divertor region of DIII-D. Fiberoptically coupled to a wide-field lens with a vertical view of the vessel floor, the instrument will be capable of differentiating the behavior of impurity line emission at the inner and outer divertor strike points, on and off the Advanced Divertor Program (ADP) ring, on the face of the DIvertor Material Exposure System (DIMES) probe, and in the region of the lower centerpost. Used with a coarse grating (300 grooves/mm), spectral coverage of each spatial channel is 15 nm with 0.3 nm resolution; used in high order with a 1200 groove/nm grating, the instrument is capable of resolving Doppler profiles. Spatial variation of gas recycling and impurity influx will be studied for both single- and double-null divertor configurations in low and high density operating regimes