5,438 research outputs found
Factor V Leiden and thrombosis in patients with systemic lupus erythematosus: a meta-analysis.
The aim of this study was to perform a meta-analysis of the association between the factor V Leiden polymorphism (FVL) and thrombosis among patients with systemic lupus erythematosus (SLE) and/or antiphospholipid antibody (aPL) positivity. Included studies recruited patients based on SLE or aPL-positive status, confirmed subjects' SLE diagnosis as defined by the American College of Rheumatology, and documented thrombotic events. Excluded studies were non-English or considered only arterial thrombosis. Individual patient data, available from 5 studies, together with unpublished data from 1210 European-American SLE patients from the UCSF Lupus Genetics Collection genotyped for FVL, were further analyzed. Seventeen studies (n=2090 subjects) were included in the initial meta-analysis. Unadjusted odds ratios (OR) were calculated to assess association of FVL with thrombosis. The OR for association of thrombosis with FVL was 2.88 (95% confidence interval (CI) 1.98-4.20). In the secondary analysis with our individual patient dataset (n=1447 European-derived individuals), SLE subjects with the FVL polymorphism still had more than two times the odds of thrombosis compared to subjects without this polymorphism, even when adjusting for covariates such as gender, age and aPL status. SLE and/or aPL-positive patients with the FVL variant have more than two times the odds of thrombosis compared to those without this polymorphism
Landscape Socioecology in the Serpis Valley (10,000–4000 BP)
En este trabajo se discute nuestro enfoque de la modelización del paisaje para la cuenca del Serpis medio (costa mediterránea central de la Península Ibérica) durante el Holoceno. La secuencia arqueológica de estos valles está marcada por la aparición inicial del paquete neolítico alrededor del año 5700 a.C. Examinamos cómo los paisajes responden al modo de vida agrícola, tanto a corto como a largo plazo. Conceptos como el cambio, la adaptación y también la resiliencia proporcionan marcos conceptuales para comprender mejor la forma en que los seres humanos interactúan con su entorno. También ayudan a explicar cómo fenómenos como la introducción inicial de la horticultura simple de cereales o la posterior introducción del cultivo del arado (Bernabeu Aubán 1995) pueden desencadenar procesos con consecuencias a veces impredecibles en los ecosistemas mediterráneos. Estas consecuencias no son inherentemente desastrosas, pero las interacciones entre los ecosistemas y los seres humanos que usan recursos son complejas y a menudo muestran resultados no lineales en sus respuestas a las actuaciones antrópicas. Utilizamos el concepto de socioecología para caracterizar estos sistemas humanos y naturales vinculados estrechamente, ya que estos deben ser un importante foco de interés para la arqueología.In this paper we discuss our approach to landscape modeling for the Holocene middle Serpis drainage system (central Mediterranean Coast of the Iberian Peninsula). The archaeological sequence of these valleys is marked by the initial appearance of the Neolithic package around 5700 BC. We examine how landscapes respond to the agricultural way of life, in both the short and the long term. Concepts like change, adaptation and also resilience provide conceptual frameworks to better understand the way in which humans interact with their surroundings. They also help to explain how phenomena like the initial introduction of simple cereal horticulture, or subsequent introduction of plow cultivation (Bernabeu Aubán 1995) can trigger processes with sometimes unpredictable consequences in Mediterranean ecosystems. These consequences are not inherently disastrous, but the interactions between ecosystems and humans using resources are complex and often display non-linear outcomes of human decisions. We use the concept of socioecology to characterize these closely coupled human and natural systems as these should be an important focus of interest for archaeology
A unified hyperbolic formulation for viscous fluids and elastoplastic solids
We discuss a unified flow theory which in a single system of hyperbolic
partial differential equations (PDEs) can describe the two main branches of
continuum mechanics, fluid dynamics, and solid dynamics. The fundamental
difference from the classical continuum models, such as the Navier-Stokes for
example, is that the finite length scale of the continuum particles is not
ignored but kept in the model in order to semi-explicitly describe the essence
of any flows, that is the process of continuum particles rearrangements. To
allow the continuum particle rearrangements, we admit the deformability of
particle which is described by the distortion field. The ability of media to
flow is characterized by the strain dissipation time which is a characteristic
time necessary for a continuum particle to rearrange with one of its
neighboring particles. It is shown that the continuum particle length scale is
intimately connected with the dissipation time. The governing equations are
represented by a system of first order hyperbolic PDEs with source terms
modeling the dissipation due to particle rearrangements. Numerical examples
justifying the reliability of the proposed approach are demonstrated.Comment: 6 figure
The Dilaton Theorem and Closed String Backgrounds
The zero-momentum ghost-dilaton is a non-primary BRST physical state present
in every bosonic closed string background. It is given by the action of the
BRST operator on another state \x, but remains nontrivial in the semirelative
BRST cohomology. When local coordinates arise from metrics we show that dilaton
and \x insertions compute Riemannian curvature and geodesic curvature
respectively. A proper definition of a CFT deformation induced by the dilaton
requires surface integrals of the dilaton and line integrals of \x.
Surprisingly, the ghost number anomaly makes this a trivial deformation. While
dilatons cannot deform conformal theories, they actually deform conformal
string backgrounds, showing in a simple context that a string background is not
necessarily the same as a CFT. We generalize the earlier proof of quantum
background independence of string theory to show that a dilaton shift amounts
to a shift of the string coupling in the field-dependent part of the quantum
string action. Thus the ``dilaton theorem'', familiar for on-shell string
amplitudes, holds off-shell as a consequence of an exact symmetry of the string
action.Comment: 51 pages, plain tex with phyzzx, two uuencoded figure
Off-shell Closed String Amplitudes: Towards a Computation of the Tachyon Potential
We derive an explicit formula for the evaluation of the classical closed
string action for any off-shell string field, and for the calculation of
arbitrary off-shell amplitudes. The formulae require a parametrization, in
terms of some moduli space coordinates, of the family of local coordinates
needed to insert the off-shell states on Riemann surfaces. We discuss in detail
the evaluation of the tachyon potential as a power series in the tachyon field.
The expansion coefficients in this series are shown to be geometrical
invariants of Strebel quadratic differentials whose variational properties
imply that closed string polyhedra, among all possible choices of string
vertices, yield a tachyon potential which is as small as possible order by
order in the string coupling constant. Our discussion emphasizes the
geometrical meaning of off-shell amplitudes.Comment: 42 pages, phyzzx macropackage. A correction made that implies that
the tachyon potential is unbounded below and unlikely to have a local
minimum. An extra reference adde
Informe preliminar sobre la prospección de la Vall del Barxell -Polop (Alcoi-Alcant)
Dins del projecte d'estudi del procés de neolitització a les comarques centromeridionals del País Valencià. es presenten els resultats preliminars obringuts en la prospecció sistemàtica deI la capçalera del riu Serpis, la Vall de Barxell-Polop (Alcoi-Alacant).Within the survey project of neolithization in the central and southern regions of the Valencian Country, we present herein the preliminary results achieved so far in the systematic prospecting at the source of the Serpis River, located in the Barxell-Polop Valley, within the municipal boundary of Alcoi, in the Alicante area.Dentro del proyecto de estudio del proceso de Neolitización en las comarcas centromeridionales del País Valenciano. se presentan los resultados preliminares obtenidos en la prospección sistemática de la cabecera del río Serpis, valle del Barxell-Polop (Alcoi. Alacant)
Photon Propagation in Space-Time with a Compactified Spatial Dimension
The one-loop effects of vacuum polarization induced by untwisted fermions in
QED in a nonsimply connected space-time with topology are
investigated. It is found that photon propagation in this system is
anisotropic, appearing several massive photon modes and a superluminal
transverse mode. For small compactification radius , the superluminal
velocity increases logarithmically with . At low energies the photon masses
lead to an effective confinement of the gauge fields into a (2+1)-dimensional
manifold transverse to the compactified direction. The system shows a
topologically induced directional superconductivity.Comment: 5 pages, to appear in PL
HLA-A and -B alleles and haplotypes in 240 index patients with common variable immunodeficiency and selective IgG subclass deficiency in central Alabama
BACKGROUND: We wanted to quantify HLA-A and -B phenotype and haplotype frequencies in Alabama index patients with common variable immunodeficiency (CVID) and selective IgG subclass deficiency (IgGSD), and in control subjects. METHODS: Phenotypes were detected using DNA-based typing (index cases) and microlymphocytotoxicity typing (controls). RESULTS: A and B phenotypes were determined in 240 index cases (114 CVID, 126 IgGSD) and 1,321 controls and haplotypes in 195 index cases and 751 controls. Phenotyping revealed that the "uncorrected" frequencies of A*24, B*14, B*15, B*35, B*40, B*49, and B*50 were significantly greater in index cases, and frequencies of B*35, B*58, B*62 were significantly lower in index cases. After Bonferroni corrections, the frequencies of phenotypes A*24, B*14, and B*40 were significantly greater in index cases, and the frequency of B*62 was significantly lower in index cases. The most common haplotypes in index cases were A*02-B*44 (frequency 0.1385), A*01-B*08 (frequency 0.1308), and A*03-B*07 (frequency 0.1000), and the frequency of each was significantly greater in index cases than in control subjects ("uncorrected" values of p < 0.0001, 0.0252, and 0.0011, respectively). After performing Bonferroni corrections, however, the frequency of A*02-B*44 alone was significantly increased in probands (p < 0.0085). Three other haplotypes were also significantly more frequent in index cases (A*03-B*14, A*31-B*40, and A*32-B*14). The combined frequencies of three latter haplotypes in index patients and control subjects were 0.0411 and 0.0126, respectively ("uncorrected" value of p < 0.0002; "corrected" value of p = 0.0166). Most phenotype and haplotype frequencies in CVID and IgGSD were similar. 26.7% of index patients were HLA-haploidentical with one or more other index patients. We diagnosed CVID or IgGSD in first-degree or other relatives of 26 of 195 index patients for whom HLA-A and -B haplotypes had been ascertained; A*01-B*08, A*02-B*44, and A*29-B*44 were most frequently associated with CVID or IgGSD in these families. We conservatively estimated the combined population frequency of CVID and IgGSD to be 0.0092 in adults, based on the occurrence of CVID and IgGSD in spouses of the index cases. CONCLUSIONS: CVID and IgGSD in adults are significantly associated with several HLA haplotypes, many of which are also common in the Alabama Caucasian population. Immunoglobulin phenotype variability demonstrated in index cases and family studies herein suggests that there are multiple gene(s) on Ch6p or other chromosomes that modify immunoglobulin phenotypes of CVID and IgGSD. The estimated prevalence of CVID and IgGSD in central Alabama could be reasonably attributed to the fact that many HLA haplotypes significantly associated with these disorders are also common in the general population
Algebraic Structures and Differential Geometry in 2D String Theory
A careful treatment of closed string BRST cohomology shows that there are
more discrete states and associated symmetries in string theory than has
been recognized hitherto. The full structure, at the radius, has a
natural description in terms of abelian gauge theory on a certain three
dimensional cone . We describe precisely how symmetry currents are
constructed from the discrete states, explaining the role of the ``descent
equations.'' In the uncompactified theory, we compute the action of the
symmetries on the tachyon field, and isolate the features that lead to
nonlinear terms in this action. The resulting symmetry structure is interpreted
in terms of a homotopy Lie algebra.Comment: 65pp. (Two figures, not included.
On the Picture Dependence of Ramond-Ramond Cohomology
Closed string physical states are BRST cohomology classes computed on the
space of states annihilated by . Since does not commute with the
operations of picture changing, BRST cohomologies at different pictures need
not agree. We show explicitly that Ramond-Ramond (RR) zero-momentum physical
states are inequivalent at different pictures, and prove that non-zero momentum
physical states are equivalent in all pictures. We find that D-brane states
represent BRST classes that are nonpolynomial on the superghost zero modes,
while RR gauge fields appear as polynomial BRST classes. We also prove that in
-cohomology, the cohomology where the zero mode of the spatial coordinates
is included, there is a unique ghost-number one BRST class responsible for the
Green-Schwarz anomaly, and a unique ghost number minus one BRST class
associated with RR charge.Comment: Added one footnote and five reference
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