Ruin Probability in a Semi-Markov Risk Model with Constant Interest Force and Heavy-Tailed Claims

In the present paper, we consider a kind of semi-Markov risk model (SMRM) with constant interest force and heavy-tailed claims, in which the claim rates and sizes are conditionally independent, both fluctuating according to the state of the risk business. First, we derive a matrix integro-differential equation satisfied by the survival probabilities. Second, we analyze the asymptotic behaviors of ruin probabilities in a two-state SMRM with special claim amounts. It is shown that the asymptotic behaviors of ruin probabilities depend only on the state 2 with heavy-tailed claim amounts, not on the state 1 with exponential claim sizes.     

Coquasitriangular Hopf Group Algebras and Drinfel'd Co-Doubles

A ring R is called “semicommutative” if any right annihilator over R is an ideal of R. We show that special subrings of upper triangular matrix rings over a reduced ring are maximal semicommutative. Consequently, new families of semicommutative rings are presented.     

Growth and characterization of nano‐crystalline hydroxyapatite at physiological conditions

Pure, stable stoichimetric nano crystalline hydroxyapatite material was crystallized by double diffusion technique at physiological conditions, temperature at 37°C and pH at 7.4. The sample was sintered at 400°C, 750°C and 1200°C with equal interval of time. They were characterized by X‐ray diffraction studies, Fourier Transformation Infra‐Red analysis, Thermogravimetric analysis, Scanning Electron Microscopic studies and Atomic Force Microscopic studies. The X‐ray analysis confirmed that the grown crystals are to be the pure form of hydroxyapatite. Infra‐red studies confirmed CO free hydroxyapatite. Thermogravimetric studies showed the thermal stability of the hydroxyapatite crystals even at 1200°C. The presence of pores in the sintered sample was traced by scanning electron microscopy. Atomic force microscopy revealed the presence of nano crystalline HAP of size 0.958 nanometer in the samples grown using this technique. At higher temperature the deagglomeration of bulk phases and agglomeration of nano phases leads to the nano crystalline HAP were observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

用于瞬态力学量测试的光学传感器设计及应用

基于光纤耦合反射式光束偏转法,提出了一种可用于瞬态力学量测试的光学传感器,并详细给出了该测试机理.采用该传感器,在靶材对心处实时检测到由于空泡在固体靶材附近溃灭时射流冲击力引起的靶材瞬态微小变形.通过对该传感器定标可以进一步得到作用冲击力大小.这种传感器的应用将有助于了解激光诱导产生空泡射流运动特性及其对靶材的损伤机制.     

The absence of physical-aging effects on the surface relaxations of rubbed polystyrene

Extensive experimental results are presented to reveal the relaxations of polystyrene surface deformed by rubbing with a velvet cloth. We found that surface topographic features, such as ditches and ridges created by rubbing, relax at temperatures at about 20^° C below the bulk glass transition temperature of the polystyrene for a molecular weight of 442 kg/mol, even though we estimate the Laplace Pressure driving the relaxation to be 1/500 of the yield limit. The relaxation is independent of the thermal history before the rubbing process, and post rubbing thermal history below 55^° C . In other words, physical-aging processes at 23^° C for up to 7 days and at 50^° C for 2 days, which would have drastic effects on the relaxations of bulk polymers, have little effects on the relaxations of rubbed surfaces. This is consistent with the mobility enhancement in the surface layer previously reported in the literature.     

Investigation of Ti/CuO interface by X-ray photoelectron spectroscopy and atomic force microscopy

The Ti/CuO interface has been studied by the techniques of X-ray photoelectron spectroscopy and atomic force microscopy. Thin films of titanium were deposited on a CuO substrate at room temperature by the e-beam technique. The photoelectron spectra of titanium and copper were found to exhibit significant chemical interaction at the interface. The titanium overlayer was observed to get oxidized to TiO₂, while the CuO was observed to get reduced to elemental copper. This chemical interaction was observed to occur until a thickness of 7 nm of the titanium overlayer. For thicknesses greater than this value, the presence of unreacted titanium in the sample was detected. Barrier characteristics at the Ti/CuO interface were also carried out for substrate temperatures of 300°C, 400°C, 500°C, and 600°C as a function of the titanium overlayer thickness. A linear trend in the barrier thickness of the overlayer was observed between 400°C and 600°C substrate temperatures. The atomic force microscopy micrographs of the unannealed samples depicted layer-by-layer growth of elemental titanium on copper. At the Ti/CuO interface in such samples, the micrographs exhibited island formation of TiO₂ corresponding to the Volmer-Weber growth model. This formation has been interpreted as the relaxation in the strain energy. The percentage coverage of the underlying substrate by the TiO₂ islands showed a linear trend for the thicknesses of the titanium overlayer investigated. The average size of these islands also showed a linear trend as a function of the thickness of the overlayer.     

Delineating Protein–Protein Curvilinear Dissociation Pathways and Energetics with Naïve Multiple-Walker Umbrella Sampling Simulations

The protein–protein interaction energetics can be obtained by calculating the potential of mean force (PMF) from umbrella sampling (US) simulations, in which samplings are often enhanced along a predefined vector as the reaction coordinate. However, any slight change in the vector may significantly vary the calculated PMF, and therefore the energetics using a random choice of vector may mislead. A non-predefined curve path-based sampling enhancement approach is a natural alternative, but was relatively less explored for protein–protein systems. In this work, dissociation of the barnase–barstar complex is simulated by implementing non-predefined curvilinear pathways in US simulations. A simple variational principle is applied to determine the lower bound PMF, which could be used to derive the standard free energy of binding. Two major dissociation pathways, which include interactions with the RNA-binding loop and the Val 36 to Gly 40 loop, are observed. Further, the proposed approach was used to discriminate the decoys from protein–protein docking studies. © 2019 Wiley Periodicals, Inc.