448 research outputs found

    Holonomy of the Ising model form factors

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    We study the Ising model two-point diagonal correlation function C(N,N) C(N,N) by presenting an exponential and form factor expansion in an integral representation which differs from the known expansion of Wu, McCoy, Tracy and Barouch. We extend this expansion, weighting, by powers of a variable λ\lambda, the jj-particle contributions, fN,N(j) f^{(j)}_{N,N}. The corresponding λ \lambda extension of the two-point diagonal correlation function, C(N,N;λ) C(N,N; \lambda), is shown, for arbitrary λ\lambda, to be a solution of the sigma form of the Painlev{\'e} VI equation introduced by Jimbo and Miwa. Linear differential equations for the form factors fN,N(j) f^{(j)}_{N,N} are obtained and shown to have both a ``Russian doll'' nesting, and a decomposition of the differential operators as a direct sum of operators equivalent to symmetric powers of the differential operator of the elliptic integral E E. Each fN,N(j) f^{(j)}_{N,N} is expressed polynomially in terms of the elliptic integrals E E and K K. The scaling limit of these differential operators breaks the direct sum structure but not the ``Russian doll'' structure. The previous λ \lambda-extensions, C(N,N;λ) C(N,N; \lambda) are, for singled-out values λ=cos(πm/n) \lambda= \cos(\pi m/n) (m,nm, n integers), also solutions of linear differential equations. These solutions of Painlev\'e VI are actually algebraic functions, being associated with modular curves.Comment: 39 page

    Nonintegrability of the two-body problem in constant curvature spaces

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    We consider the reduced two-body problem with the Newton and the oscillator potentials on the sphere S2{\bf S}^{2} and the hyperbolic plane H2{\bf H}^{2}. For both types of interaction we prove the nonexistence of an additional meromorphic integral for the complexified dynamic systems.Comment: 20 pages, typos correcte

    No Association Between MTHFR A1298C and MTRR A66G Polymorphisms, and MS in an Australian Cohort

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    Multiple sclerosis (MS) is a complex neurological disease that affects the central nervous system (CNS) resulting in debilitating neuropathology. Pathogenesis is primarily defined by CNS inflammation and demyelination of nerve axons. Methionine synthase reductase (MTRR) is an enzyme that catalyzes the remethylation of homocysteine (Hcy) to methionine via cobalamin and folate dependant reactions. Cobalamin acts as an intermediate methyl carrier between methylenetetrahydrofolate reductase (MTHFR) and Hcy. MTRR plays a critical role in maintaining cobalamin in an active form and is consequently an important determinant of total plasma Hcy (pHcy) concentrations. Elevated intracellular pHcy levels have been suggested to play a role in CNS dysfunction, neurodegenerative, and cerebrovascular diseases. Our investigation entailed the genotyping of a cohort of 140 cases and matched controls for MTRR and MTHFR, by restriction length polymorphism (RFLP) techniques. Two polymorphisms: MTRR A66G and MTHFR A1298C were investigated in an Australian age and gender matched case-control study. No significant allelic frequency difference was observed between cases and controls at the α = 0.05 level (MTRR χ^2 = 0.005, P = 0.95, MTHFR χ^2 = 1.15, P = 0.28). Our preliminary findings suggest no association between the MTRR A66G and MTHFR A1298C polymorphisms and MS

    Genetics of human neural tube defects

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    Neural tube defects (NTDs) are common, severe congenital malformations whose causation involves multiple genes and environmental factors. Although more than 200 genes are known to cause NTDs in mice, there has been rather limited progress in delineating the molecular basis underlying most human NTDs. Numerous genetic studies have been carried out to investigate candidate genes in cohorts of patients, with particular reference to those that participate in folate one-carbon metabolism. Although the homocysteine remethylation gene MTHFR has emerged as a risk factor in some human populations, few other consistent findings have resulted from this approach. Similarly, attention focused on the human homologues of mouse NTD genes has contributed only limited positive findings to date, although an emerging association between genes of the non-canonical Wnt (planar cell polarity) pathway and NTDs provides candidates for future studies. Priorities for the next phase of this research include: (i) larger studies that are sufficiently powered to detect significant associations with relatively minor risk factors; (ii) analysis of multiple candidate genes in groups of well-genotyped individuals to detect possible gene–gene interactions; (iii) use of high throughput genomic technology to evaluate the role of copy number variants and to detect ‘private’ and regulatory mutations, neither of which have been studied to date; (iv) detailed analysis of patient samples stratified by phenotype to enable, for example, hypothesis-driven testing of candidates genes in groups of NTDs with specific defects of folate metabolism, or in groups of fetuses with well-defined phenotypes such as craniorachischisis

    Fuchs versus Painlev\'e

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    We briefly recall the Fuchs-Painlev\'e elliptic representation of Painlev\'e VI. We then show that the polynomiality of the expressions of the correlation functions (and form factors) in terms of the complete elliptic integral of the first and second kind, K K and E E, is a straight consequence of the fact that the differential operators corresponding to the entries of Toeplitz-like determinants, are equivalent to the second order operator LE L_E which has E E as solution (or, for off-diagonal correlations to the direct sum of LE L_E and d/dt d/dt). We show that this can be generalized, mutatis mutandis, to the anisotropic Ising model. The singled-out second order linear differential operator LE L_E being replaced by an isomonodromic system of two third-order linear partial differential operators associated with Π1 \Pi_1, the Jacobi's form of the complete elliptic integral of the third kind (or equivalently two second order linear partial differential operators associated with Appell functions, where one of these operators can be seen as a deformation of LE L_E). We finally explore the generalizations, to the anisotropic Ising models, of the links we made, in two previous papers, between Painlev\'e non-linear ODE's, Fuchsian linear ODE's and elliptic curves. In particular the elliptic representation of Painlev\'e VI has to be generalized to an ``Appellian'' representation of Garnier systems.Comment: Dedicated to the : Special issue on Symmetries and Integrability of Difference Equations, SIDE VII meeting held in Melbourne during July 200

    Psycho-educational interventions for adults with severe or difficult asthma: a systematic review.

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    types: Journal Article; Research Support, Non-U.S. Gov't; ReviewThis is the author's version of the work that was accepted for publication in the Journal of Asthma. The final version can be accessed via the DOI in this record.Research highlights psychosocial factors associated with adverse asthma events. This systematic review therefore examined whether psycho-educational interventions improve health and self-management outcomes in adults with severe or difficult asthma. Seventeen controlled studies were included. Characteristics and content of interventions varied even within broad types. Study quality was generally poor and several studies were small. Any positive effects observed from qualitative and quantitative syntheses were mainly short term and, in planned subgroup analyses (involving < 5 trials), effects on hospitalizations, quality of life, and psychological morbidity in patients with severe asthma did not extend to those in whom multiple factors complicate management.UK NHS Health Technology Assessment Programm

    Plasma-assisted ALD of LiPO(N) for solid state batteries

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    All solid state 3D batteries are pursued for their increased safety and high power capabilities. At present conformai coating of the solid electrolyte remains one of the key hurdles for the implementation of such devices. In the present work we investigate atomic layer deposition (ALD) as means of conformai deposition of lithium phosphate (Li3PO4) and nitrogen doped lithium phosphates (LiPON). These processes are characterized here to obtain the highest possible Li-ion conductivity. Li3PO4 is shown to yield a conductivity of 10-10 S/cm. On the other hand, an optimized LiPON process gave rise to a Li-ion conductivity of 510-7 S/cm. In addition, good conformality of the LiPON process was shown on high aspect ratio pillars. Furthermore, a solid state battery device was fabricated comprising a Li4Ti5O12 cathode, a 70 nm thick ALD LiPON solid electrolyte and a metallic lithium anode. The fabricated device is based on the thinnest solid electrolyte used so far as well as on the first ALD deposited solid electrolyte.</p
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