The averaged characteristic polynomial for the Gaussian and chiral Gaussian ensembles with a source

In classical random matrix theory the Gaussian and chiral Gaussian random matrix models with a source are realized as shifted mean Gaussian, and chiral Gaussian, random matrices with real $(\beta = 1)$, complex ($\beta = 2)$ and real quaternion $(\beta = 4$) elements. We use the Dyson Brownian motion model to give a meaning for general $\beta > 0$. In the Gaussian case a further construction valid for $\beta > 0$ is given, as the eigenvalue PDF of a recursively defined random matrix ensemble. In the case of real or complex elements, a combinatorial argument is used to compute the averaged characteristic polynomial. The resulting functional forms are shown to be a special cases of duality formulas due to Desrosiers. New derivations of the general case of Desrosiers' dualities are given. A soft edge scaling limit of the averaged characteristic polynomial is identified, and an explicit evaluation in terms of so-called incomplete Airy functions is obtained.Comment: 21 page

Body size, first year breeding, and extra-pair paternity in an island endemic, the Island Scrub-Jay

2014 Spring.Includes bibliographical references.Body size is a fundamental characteristic that shapes all aspects of an organism's biology. The advantages of large body size may include increased probability of territory acquisition, a critical component of fitness for species that require a territory to breed. Large body size, an indicator of quality, may also be advantageous to males in acquiring mates, including matings outside of a pair bond. Such advantages could be especially important in island systems because habitat saturation may result in strong intra-specific competition for territories, and females may be especially motivated to seek large extra-pair mates to increase the body size of their offspring. We tested the role of body size in determining the ability of an island-endemic bird, the Island Scrub-Jay, Aphelocoma insularis, to acquire a territory and breed in their first spring, as well as to sire extra-pair offspring. We compared the body size of individuals that obtained a territory and bred to those that did not, as well as the body size of social fathers to the extra-pair sires to whom they lost paternity. We found that large body size was important in the siring of extra-pair young. However, body size did not predict the ability of male or female Island Scrub-Jays to acquire a territory and breed in their first year. We suggest that year-to-year variation in environmental conditions and chance may be more important than a large body size or weapon performance in early territory acquisition. Our study provides evidence for a mechanism, specifically female preference for a large body size in males, that supports the observed rates of extra-pair paternity, and demonstrates the general difficulty, even for individuals with a relatively large body size, of acquiring a territory as a yearling in an island system with saturated habitat

Efficient algorithms for finding critical subgraphs

AbstractThis paper presents algorithms to find vertex-critical and edge-critical subgraphs in a given graph G, and demonstrates how these critical subgraphs can be used to determine the chromatic number of G. Computational experiments are reported on random and DIMACS benchmark graphs to compare the proposed algorithms, as well as to find lower bounds on the chromatic number of these graphs. We improve the best known lower bound for some of these graphs, and we are even able to determine the chromatic number of some graphs for which only bounds were known

Maternal occupational exposure to organic solvents during early pregnancy and selected congenital anomalies

Background: As more women enter the labor force, there is increased epidemiologic interest in the possible effects of employment and occupational exposures on adverse pregnancy outcomes. Using data from the National Birth Defects Prevention Study, we examined the prevalence and patterns of maternal employment before and during pregnancy, and examined the relation between maternal occupational exposure to organic solvents during the periconceptional period (first trimester and month before conception) and neural tube defects (NTDs) and orofacial clefts (OFCs), which toxicological data suggest may be susceptible to oxidative stressors like solvents. Methods: Cases of NTDs (anencephaly; spina bifida; encephalocele) and OFCs (cleft lip [plus or minus] cleft palate; cleft palate) delivered between 1997 and 2002 were identified by birth defect surveillance registries in 8 states; non-malformed control infants were selected using birth certificates or hospital records. Exposure to aromatic, chlorinated and Stoddard solvents were estimated by industrial hygienist review of self-reported occupational histories in combination with a literature-derived exposure database. We used employment dates to examine variability in employment status and estimated exposure prevalence to any solvent across different time periods before and during pregnancy among controls. Odds ratios (OR) and 95% confidence intervals (CI) for the association between solvent class and each birth defect group and component phenotype were estimated using logistic regression, adjusting for maternal age, race/ethnicity, education, pre-pregnancy body mass index, folic acid supplement use and smoking. Results: Over 70% of mothers worked at some point 3 months before and during pregnancy; employment status was not constant throughout pregnancy for 25% of these women. The prevalence of estimated exposure to any solvent during the periconceptional period among mothers of NTD cases (n=511), OFC cases (n=1163) and controls (n=2997) was 13.1%, 9.6% and 8.2%, respectively. No solvent class was associated with OFCs in these data. Exposure to chlorinated solvents was associated with increased odds of NTDs (OR=1.96; CI=1.34, 2.87), particularly spina bifida (OR=2.26; CI=1.44, 3.53). Conclusions: Future studies of maternal employment should focus on the biologically relevant critical exposure window to reduce misclassification. Maternal occupational exposure to chlorinated solvents during early pregnancy may be associated with NTDs and merits further research

Time Series Forecasting by Recommendation: An Empirical Analysis on Amazon Marketplace

This study proposes a forecasting methodology for univari ate time series (TS) using a Recommender System (RS). The RS is built from a given TS as only input data and following an item-based Collabo rative Filtering approach. A set of top-N values is recommended for this TS which represent the forecasts. The idea is to emulate RS elements (the users, items and ratings triple) from the TS. Two TS obtained from Italy’s Amazon webpage were used to evaluate this methodology and very promising performance results were obtained, even the difficult environ ment chosen to conduct forecasting (short length and unevenly spaced TS). This performance is dependent on the similarity measure used and suffers from the same problems that other RSs (e.g., cold-start). However, this approach does not require high computational power to perform and its intuitive conception allows for being deployed with any programming language

Supersymmetric Many-particle Quantum Systems with Inverse-square Interactions

The development in the study of supersymmetric many-particle quantum systems with inverse-square interactions is reviewed. The main emphasis is on quantum systems with dynamical OSp(2|2) supersymmetry. Several results related to exactly solved supersymmetric rational Calogero model, including shape invariance, equivalence to a system of free superoscillators and non-uniqueness in the construction of the Hamiltonian, are presented in some detail. This review also includes a formulation of pseudo-hermitian supersymmetric quantum systems with a special emphasis on rational Calogero model. There are quite a few number of many-particle quantum systems with inverse-square interactions which are not exactly solved for a complete set of states in spite of the construction of infinitely many exact eigen functions and eigenvalues. The Calogero-Marchioro model with dynamical SU(1,1|2) supersymmetry and a quantum system related to short-range Dyson model belong to this class and certain aspects of these models are reviewed. Several other related and important developments are briefly summarized.Comment: LateX, 65 pages, Added Acknowledgment, Discussions and References, Version to appear in Jouranl of Physics A: Mathematical and Theoretical (Commissioned Topical Review Article

Some properties of angular integrals

We find new representations for Itzykson-Zuber like angular integrals for arbitrary beta, in particular for the orthogonal group O(n), the unitary group U(n) and the symplectic group Sp(2n). We rewrite the Haar measure integral, as a flat Lebesge measure integral, and we deduce some recursion formula on n. The same methods gives also the Shatashvili's type moments. Finally we prove that, in agreement with Brezin and Hikami's observation, the angular integrals are linear combinations of exponentials whose coefficients are polynomials in the reduced variables (x_i-x_j)(y_i-y_j).Comment: 43 pages, Late

Assessing the Multiple Dimensions of the Self-Concept of Young Children: A Focus on Latinos

This study was designed to provide psychometric and developmental information for a caregiver report and observational measure of young children\u27s self-concept. The Caregiver Inventory of Self-Concept (elsC) and the Tasks for Observation of Self-Concept (lOSe) assess six domains: self-recognition, self-representation, selfdescription, self-assertion, self-evaluation, self-regulation. Mothers of 290 children aged 6 to 66 months reported on the presence of self-concept behaviors, and 75 of these children, aged 15 to 48 months, were observed. Coefficient alpha, an index of item-objective congruence, and factor analysis provided evidence for the reliability and validity of both measures. Between- and within-domain analyses found that the development of self-concept in young children followed the hypothesized progression (self-recognition, self-representation, self-description, self-assertion, selfevaluation, and self-regulation) on the ClSC but not on the TOSC

Treatment and Management of Depression Symptoms in Pregnant Veterans: Varying Experiences of Mental Health Care in the Prenatal Period

Depression screening is recommended for all pregnant veterans; however, little is known on how often symptomatic women receive care, how depression treatment presents in practice, and whether women veterans are utilizing treatment during the appreciable perinatal period. Our sample included 142 pregnant veterans from 15 Veterans Health Administration (VA) medical facilities with Edinburgh Postnatal Depression Scale (EPDS) scores \u3e/=10. Sociodemographic characteristics, military service, health utilization, and pregnancy related factors were collected as part of a telephone survey. A majority of our sample (70%) had 1 or more mental health visits or antidepressant prescriptions during pregnancy. Women with a history of depression had more mental health visits and a higher percentage of antidepressant use before and during pregnancy than women without a history of depression. Pregnant women veterans without a history of depression may be less likely to receive care for depression during pregnancy. However, the majority of our veterans showing depression symptoms prenatally had at least one mental health visit or an antidepressant medication fill during their pregnancy window, suggesting that mental health care is readily available for women veterans