115 research outputs found
Elements for a Theory of Financial Risks
Estimating and controlling large risks has become one of the main concern of
financial institutions. This requires the development of adequate statistical
models and theoretical tools (which go beyond the traditionnal theories based
on Gaussian statistics), and their practical implementation. Here we describe
three interrelated aspects of this program: we first give a brief survey of the
peculiar statistical properties of the empirical price fluctuations. We then
review how an option pricing theory consistent with these statistical features
can be constructed, and compared with real market prices for options. We
finally argue that a true `microscopic' theory of price fluctuations (rather
than a statistical model) would be most valuable for risk assessment. A simple
Langevin-like equation is proposed, as a possible step in this direction.Comment: 22 pages, to appear in `Order, Chance and Risk', Les Houches (March
1998), to be published by Springer/EDP Science
Consistently Solving the Simplicity Constraints for Spinfoam Quantum Gravity
We give an independent derivation of the Engle-Pereira-Rovelli spinfoam model
for quantum gravity which recently appeared in [arXiv:0705.2388]. Using the
coherent state techniques introduced earlier in [arXiv:0705.0674], we show that
the EPR model realizes a consistent imposition of the simplicity constraints
implementing general relativity from a topological BF theory.Comment: 6 pages, 2 figures, v2: typos correcte
Prototypes for Content-Based Image Retrieval in Clinical Practice
Content-based image retrieval (CBIR) has been proposed as key technology for computer-aided diagnostics (CAD). This paper reviews the state of the art and future challenges in CBIR for CAD applied to clinical practice
Limited genetic variation and structure in softshell clams (Mya arenaria) across their native and introduced range
Author Posting. © Springer, 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Conservation Genetics 10 (2009): 803-814, doi:10.1007/s10592-008-9641-y.To offset declines in commercial landings of the softshell clam, Mya arenaria, resource
managers are engaged in extensive stocking of seed clams throughout its range in the
northwest Atlantic. Because a mixture of native and introduced stocks can disrupt locally
adapted genotypes, we investigated genetic structure in M. arenaria populations across
its current distribution to test for patterns of regional differentiation. We sequenced
mitochondrial cytochrome oxidase I (COI) for a total of 212 individuals from 12 sites in
the northwest Atlantic (NW Atlantic), as well as two introduced sites, the northeast
Pacific (NE Pacific) and the North Sea and Europe (NS Europe). Populations exhibited
extremely low genetic variation, with one haplotype dominating (65-100%) at all sites
sampled. Despite being introduced in the last 150-400 years, both NE Pacific and NS
Europe populations had higher diversity measures than those in the NW Atlantic and both
contained private haplotypes at frequencies of 10% to 27% consistent with their
geographic isolation. While significant genetic structure (FST = 0.159, p<0.001) was
observed between NW Atlantic and NS Europe, there was no evidence for genetic
structure across the pronounced environmental clines of the NW Atlantic. Reduced
genetic diversity in mtDNA combined with previous studies reporting reduced genetic
diversity in nuclear markers strongly suggests a recent population expansion in the NW
Atlantic, a pattern that may result from the retreat of ice sheets during Pleistocene glacial
periods. Lack of genetic diversity and regional genetic differentiation suggests that
present management strategies for the commercially important softshell clam are unlikely
to have a significant impact on the regional distribution of genetic variation, although the
possibility of disrupting locally adapted stocks cannot be excluded.This work was supported by NSF grants OCE-0326734 and OCE-0215905 to L.
Mullineaux and OCE- 0349177 (Biological Oceanography) to PHB
Refining value-at-risk estimates using a Bayesian Markov-switching GJR-GARCH copula-EVT model
In this paper, we propose a model for forecasting Value-at-Risk (VaR) using a Bayesian Markov-switching GJR-GARCH(1,1) model with skewed Student’s-t innovation, copula functions and extreme value theory. A Bayesian Markov-switching GJR-GARCH(1,1) model that identifies non-constant volatility over time and allows the GARCH parameters to vary over time following a Markov process, is combined with copula functions and EVT to formulate the Bayesian Markov-switching GJR-GARCH(1,1) copula-EVT VaR model, which is then used to forecast the level of risk on financial asset returns. We further propose a new method for threshold selection in EVT analysis, which we term the hybrid method. Empirical and back-testing results show that the proposed VaR models capture VaR reasonably well in periods of calm and in periods of crisis
Entrepreneurial-intention constraint model: A comparative analysis among post-graduate management students in India, Singapore and Malaysia
YesAlthough literature on entrepreneurship has increasingly focused on intention-based models, not much emphasis has been laid on understanding the combined effect of contextual and situational factors along with support of university environment on the formation of entrepreneurial intention among students. In an effort to make up for this shortfall, by taking Theory of Planned Behavior as basic framework, the present study seeks to understand the influence of three of the most important factors, viz. (a) endogenous barriers, (b) exogenous environment, and (c) university environment and support on the entrepreneurial intention among management students. The study sample consisted of 1,097 students, wherein 526 students were from India, 252 from Singapore, and 319 were from Malaysia. The results indicates that along with positive attitude and perceived behavioral control that directly influences entrepreneurial intention, university environment and support and exogenous environment also have an indirect but significant impact on shaping of entrepreneurial intention among students. With this, it was found that exogenous environment was found to have a negative relationship with both attitude towards behavior and perceived behavioral control for all three countries.The full-text of this article will be released for public view at the end of the publisher embargo on 2 Jun 2018
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