242 research outputs found
Antiferromagnetism and d-wave superconductivity in cuprates: a uster DMFT study
We present a new approach to investigate the coexistence of
antiferromagnetism and d-wave superconductivity in the two dimensional extended
Hubbard model within a numerically exact cluster dynamical mean-field
approximation. Self-consistent solutions with two non-zero order parameters
exists in the wide range of doping level and temperatures. A linearized
equation for energy spectrum near the Fermi level have been solved. The
resulting d-wave gap has the correct magnitude and k-dependence but some
distortion compare to the pure d_{x^2-y^2} superconducting order parameter due
to the presence of underlying antiferromagnetic ordering.Comment: 4 pages, 3 figure
The Electrical-Thermal Switching in Carbon Black-Polymer Composites as a Local Effect
Following the lack of microscopic information about the intriguing well-known
electrical-thermal switching mechanism in Carbon Black-Polymer composites, we
applied atomic force microscopy in order to reveal the local nature of the
process and correlated it with the characteristics of the widely used
commercial switches. We conclude that the switching events take place in
critical interparticle tunneling junctions that carry most of the current. The
macroscopic switched state is then a result of a dynamic-stationary state of
fast switching and slow reconnection of the corresponding junctions.Comment: 14 pages, 5 figures,Typographic correctio
Anomalous Thermal Stability of Nd-Fe-Co-Al Bulk Metallic Glass
The thermal stability of Nd60Fe20Co10Al10 bulk metallic glass (BMG) has been studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), isochronal dilatation and compression tests. The results show that the glass transition of the BMG takes place quite gradually between about 460 and 650 K at a heating rate of 0.17 K/s. Several transformation processes are observed during continuous heating with the first crystallization process beginning at about 460 K, while massive crystallization takes place near the solidus temperature of the alloy. The positive heat of mixing between the two major constituents, Nd and Fe, and, consequently, a highly inhomogeneous composition of the attained amorphous phase are responsible for the anomalous thermal stability in this system. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved
Fecal pancreatic elastase-1 levels in older individuals without known gastrointestinal diseases or diabetes mellitus
Background - Structural changes occur in the pancreas as a part of the natural aging process. With aging, also the incidence of maldigestive symptoms and malnutrition increases, raising the possibility that these might be caused at least in part by inadequate pancreatic enzyme secretion due to degenerative processes and damage of the gland. Fecal elastase-1 is a good marker of pancreatic exocrine secretion. The aim of this study was to investigate the fecal elastase-1 levels among over 60 years old Finnish and Polish healthy individuals without any special diet, known gastrointestinal disease, surgery or diabetes mellitus.
Methods - A total of 159 patients participated in this cross-sectional study. 106 older individuals (aged 60-92 years) were recruited from outpatient clinics and elderly homes. They were divided to three age groups: 60-69 years old (n = 31); 70-79 years old (n = 38) and over 80 years old (n = 37). 53 young subjects (20-28 years old) were investigated as controls. Inclusion criteria were age over 60 years, normal status and competence. Exclusion criteria were any special diet, diabetes mellitus, any known gastrointestinal disease or prior gastrointestinal surgery. Fecal elastase-1 concentration was measured from stool samples with an ELISA that uses two monoclonal antibodies against different epitopes of human elastase-1.
Results - Fecal elastase-1 concentrations correlated negatively with age (Pearson r = -0,3531, P < 0.001) and were significantly lower among subjects over 70 years old compared to controls (controls vs. 70-79 years old and controls vs. over 80 years old, both P < 0.001). Among the over 60 years old subjects, the fecal elastase-1 concentrations were below the cut off level of 200 μg/g in 23 of 106 (21.7%) individuals [mean 112 (86-138) μg/g] indicating pancreatic exocrine insufficiency. Of those, 9 subjects had fecal elastase-1 level below 100 μg/g as a marker of severe pancreatic insufficiency.
Conclusion - In our study one fifth of healthy older individuals without any gastrointestinal disorder, surgery or diabetes mellitus suffer from pancreatic exocrine insufficiency and might benefit from enzyme supplementation therapy.peerReviewe
Gut mucosal DAMPs in IBD: From mechanisms to therapeutic implications
Endogenous damage-associated molecular patterns (DAMPs) are released during tissue damage and have increasingly recognized roles in the etiology of many human diseases. The inflammatory bowel diseases (IBD), ulcerative colitis (UC) and Crohn’s disease (CD), are immune-mediated conditions where high levels of DAMPs are observed. DAMPs such as calprotectin (S100A8/9) have an established clinical role as a biomarker in IBD. In this review, we use IBD as an archetypal common chronic inflammatory disease to focus on the conceptual and evidential importance of DAMPs in pathogenesis and why DAMPs represent an entirely new class of targets for clinical translation. </p
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