Closed formula for Wilson loops for SU(N)SU(N) Quantum Yang-Mills Theory in two dimensions

A closed expression of the Euclidean Wilson-loop functionals is derived for pure Yang-Mills continuum theories with gauge groups $SU(N)$ and $U(1)$ and space-time topologies \Rl^1\times\Rl^1 and \Rl^1\times S^1. (For the $U(1)$ theory, we also consider the $S^1\times S^1$ topology.) The treatment is rigorous, manifestly gauge invariant, manifestly invariant under area preserving diffeomorphisms and handles all (piecewise analytic) loops in one stroke. Equivalence between the resulting Euclidean theory and and the Hamiltonian framework is then established. Finally, an extension of the Osterwalder-Schrader axioms for gauge theories is proposed. These axioms are satisfied for the present model.Comment: 31 pages, Latex, no figure

Administrative Censoring in Ecological Analyses of Autism and a Bayesian Solution

Widely cited ecological analyses of autism have reported associations with mercury emissions, with precipitation, and race at the level of counties or school districts. However, state educational agencies often suppress any low numerical autism counts before releasing data—a phenomenon known as “administrative censoring.” Previous analyses did not describe appropriate methods for censored data analysis; common substitution or exclusion methods are known to introduce bias and produce artificially narrow confidence intervals. We apply a Bayesian censored random effects Poisson model to reanalyze associations between 2001 Toxic Release Inventory reported mercury emissions and 2000-2001 autism counts in Texas. Relative risk estimates for autism decreased from 4.44 (95% CI: 4.16, 4.74) per thousand lbs. of air mercury emissions using a naive zero-substitution approach to 1.42 (95% CI: 1.09, 1.78) using the Bayesian approach. Inadequate attention to censoring poses a serious threat to the validity of ecological analyses of autism and other health outcomes

Biobased value chains for a growing bioeconomy

This special issue covers three important fields of the bioeconomy: sustainable biogas value chains, bio‐based products from lignocellulose, and the use of microalgae as a biomass resource and for the production of food and feed. In order to develop sustainable products and processes, an interdisciplinary systemic approach to the analysis of entire value chains is necessary. For this reason, the contributions cover aspects of the complete biobased value chain from biomass production, pretreatment, and conversion, through to the manufacture and marketing of biobased products, and in addition, include socio‐economic and ecological assessments

SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical radioisotope power system (RPS) launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources were designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments

Uniqueness of diffeomorphism invariant states on holonomy-flux algebras

Loop quantum gravity is an approach to quantum gravity that starts from the Hamiltonian formulation in terms of a connection and its canonical conjugate. Quantization proceeds in the spirit of Dirac: First one defines an algebra of basic kinematical observables and represents it through operators on a suitable Hilbert space. In a second step, one implements the constraints. The main result of the paper concerns the representation theory of the kinematical algebra: We show that there is only one cyclic representation invariant under spatial diffeomorphisms. While this result is particularly important for loop quantum gravity, we are rather general: The precise definition of the abstract *-algebra of the basic kinematical observables we give could be used for any theory in which the configuration variable is a connection with a compact structure group. The variables are constructed from the holonomy map and from the fluxes of the momentum conjugate to the connection. The uniqueness result is relevant for any such theory invariant under spatial diffeomorphisms or being a part of a diffeomorphism invariant theory.Comment: 38 pages, one figure. v2: Minor changes, final version, as published in CM

Abnormalities of the corpus callosum in nonpsychotic children with chromosome 22q11 deletion syndrome

Chromosome 22q11 deletion syndrome (22q11DS) is associated with elevated rates of schizophrenia and other psychoses in adulthood. Childhood morphologic brain abnormalities are frequently reported, but the significance of these and their relationship to the development of schizophrenia are unclear. We sought to delineate midline neuroanatomical abnormalities in nonpsychotic children with 22q11DS and their age- and sex-matched controls and compare these to those reported in individuals with schizophrenia. On qualitative analysis, we found a high incidence of midline developmental abnormalities (cavum septum pellucidum, or CSP). On quantitative analysis, the total corpus callosum (CC) area was significantly increased in the patient group and among the subregions, the patients had a significantly larger isthmus. These findings of an increased area of the corpus callosum, specifically the isthmus, have not been reported before in individuals with 22q11DS. We also found a relative lack of the age-related increase in the size of the corpus callosum in the children with 22q11DS. There were no differences in cerebellar vermis measurements between the patient and control groups. Our findings are indicative of frequent midline brain anomalies, including dysgenesis of the corpus callosum, in nonpsychotic children with 22q11DS. Although the increased size of the corpus callosum in our 22q11DS patients is in direct contrast to the decrease seen in schizophrenia, the high frequency of structural midline abnormalities in these nonpsychotic children with 22q11DS is similar to that seen in schizophrenia. Further longitudinal studies on these children will help determine which of these structural abnormalities is/are pertinent to the development of psychosis

Schizophrenic-like neurocognitive deficits in children and adolescents with 22q11 deletion syndrome

22q11.2 Deletion Syndrome (22q11DS) is the most common genetic microdeletion syndrome affecting humans. The syndrome is associated with general cognitive impairments and specific deficits in visual-spatial ability, non-verbal reasoning, and planning skills. 22q11DS is also associated with behavioral and psychiatric abnormalities, including a markedly elevated risk for schizophrenia. Research findings indicate that people with schizophrenia, as well as those identified as schizoptypic, show specific cognitive deficits in the areas of sustained attention, executive functioning, and verbal working memory. The present study examined such schizophrenic-like cognitive deficits in children and adolescents with 22q11DS (n?=?26) and controls (n?=?25) using a cross-sectional design. As hypothesized, 22q11DS participants exhibited deficits in intelligence, achievement, sustained attention, executive functioning, and verbal working memory compared to controls. Furthermore, deficits in attention and executive functioning were more pronounced in the 22q11DS sample relative to general cognitive impairment. These findings suggest that the same pattern of neuropsychological impairment seen in patients with schizophrenia is present in non-psychotic children identified as at-risk for the development of schizophrenia based on a known genetic risk marker. © 2006 Wiley-Liss, Inc