3,055 research outputs found
Ab initio calculations of response properties including electron-hole interaction
We discuss the current status of a computational approach which allows to
evaluate the dielectric matrix, and hence electronic excitations like optical
properties, including local field and excitonic effects. We introduce a recent
numerical development which greatly reduces the use of memory in such type of
calculations, and hence eliminates one of the bottlenecks for the application
to complex systems. We present recent applications of the method, focusing our
interest on insulating oxides.Comment: 11 pages, 5 figures, 1999 MRS Proceedin
Ab initio calculation of excitonic effects in the optical spectra of semiconductors
An ab initio approach to the calculation of excitonic effects in the optical
absorption spectra of semiconductors and insulators is formulated. It starts
from a quasiparticle bandstructure calculation and is based on the relevant
Bethe--Salpeter equation.
An application to bulk silicon shows a substantial improvement with respect
to previous calculations in the description of the experimental spectrum, for
both peak positions and lineshape.Comment: 4 pages, 1 figur
Serum microRNA-122 predicts survival in patients with liver cirrhosis
Background: Liver cirrhosis is associated with high morbidity and mortality. MicroRNAs (miRs) circulating in the blood are an emerging new class of biomarkers. In particular, the serum level of the liver-specific miR-122 might be a clinically useful new parameter in patients with acute or chronic liver disease.
Aim: Here we investigated if the serum level of miR-122 might be a prognostic parameter in patients with liver cirrhosis.
Methods: 107 patients with liver cirrhosis in the test cohort and 143 patients in the validation cohort were prospectively enrolled into the present study. RNA was extracted from the sera obtained at the time of study enrollment and the level of miR-122 was assessed. Serum miR-122 levels were assessed by quantitative reverse-transcription PCR (RT-PCR) and were compared to overall survival time and to different complications of liver cirrhosis.
Results: Serum miR-122 levels were reduced in patients with hepatic decompensation in comparison to patients with compensated liver disease. Patients with ascites, spontaneous bacterial peritonitis and hepatorenal syndrome had significantly lower miR-122 levels than patients without these complications. Multivariate Cox regression analysis revealed that the miR-122 serum levels were associated with survival independently from the MELD score, sex and age.
Conclusions: Serum miR-122 is a new independent marker for prediction of survival of patients with liver cirrhosis
Evidence for a Ru Kondo Lattice in LaCuRuO
Rare -electron derived heavy-fermion properties of the solid-solution
series LaCuRuTiO were studied for by
resistivity, susceptibility, specific-heat measurements, and magnetic-resonance
techniques. The pure ruthenate () is a heavy-fermion metal characterized
by a resistivity proportional to at low temperatures . The coherent
Kondo lattice formed by the localized Ru 4 electrons is screened by the
conduction electrons leading to strongly enhanced effective electron masses. By
increasing titanium substitution the Kondo lattice becomes diluted resulting in
single-ion Kondo properties like in the paradigm -based heavy-fermion
compound CeLaCuSi [M. Ocko {\em et al.}, Phys. Rev. B
\textbf{64}, 195106 (2001)]. In LaCuRuTiO the
heavy-fermion behavior finally breaks down on crossing the metal-to-insulator
transition close to .Comment: 9 pages, 8 figure
Pricing of Cyber Insurance Contracts in a Network Model
We develop a novel approach for pricing cyber insurance contracts. The considered cyber threats, such as viruses and worms, diffuse in a structured data network. The spread of the cyber infection is modeled by an interacting Markov chain. Conditional on the underlying infection, the occurrence and size of claims are described by a marked point process. We introduce and analyze a new polynomial approximation of claims together with a mean-field approach that allows to compute aggregate expected losses and prices of cyber insurance. Numerical case studies demonstrate the impact of the network topology and indicate that higher order approximations are indispensable for the analysis of non-linear claims. © 2018 by Astin Bulletin. All rights reserved
Atrial Natriuretic Peptide, a Regulator of Nuclear Factor-κB Activation in Vivo
Natriuretic peptides (NPs) comprise a family of vasoactive hormones that play important roles in the regulation of cardiovascular and renal homeostasis. Along this line, atrial NP (ANP) (international non-proprietary name: carperitide, HANP) is an approved drug for the treatment of acute heart failure. In recent years, evidence has been given that the NP system possesses a far broader biological spectrum than the regulation of blood pressure and volume homeostasis. In fact, a substantial amount of in vitro work indicates that ANP affects important inflammatory processes and signaling pathways. Quite surprisingly, however, no information exists on the in vivo antiinflammatory potential and signaling of ANP. We show here that pretreatment of lipopolysaccharide (Salmonella abortus equi, 2.5 mg/kg)-challenged mice with ANP (5μg/kg iv, 15 min) rapidly inhibits nuclear factor-κB activation via inhibition of phosphorylation and degradation of the IκB-α protein. ANP also reduces Akt activation upon lipopolysaccharide injection. In ANP-pretreated mice, the increase of TNF-α serum concentration is markedly prevented; most importantly, the survival of these animals improved. These findings demonstrate both in vitro and in vivo an antiinflammatory profile of ANP that deserves to be further investigated in a therapeutic perspective
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