具有随机加速度的随机运动的存在性

讨论了随机加速度为位移的给定函数的随机运动的存在性(即R上的随机微分方程弱解的存在性),给出并证明了具有随机加速度的随机运动存在的几个充分性条件.     

For complex orientations preserving power operations, p-typicality is atypical

We show, for primes p?13, that a number of well-known MU(p)-rings do not admit the structure of commutative MU(p)-algebras. These spectra have complex orientations that factor through the Brown-Peterson spectrum and correspond to p-typical formal group laws. We provide computations showing that such a factorization is incompatible with the power operations on complex cobordism. This implies, for example, that if E is a Landweber exact MU(p)-ring whose associated formal group law is p-typical of positive height, then the canonical map MU(p)→E is not a map of H_∞ ring spectra. It immediately follows that the standard p-typical orientations on BP,E(n), and En do not rigidify to maps of E_∞ ring spectra. We conjecture that similar results hold for all primes.     

Brown measures of sets of commuting operators in a type II1 factor

Using the spectral subspaces obtained in [U. Haagerup, H. Schultz, Invariant subspaces of operators in a general II₁-factor, preprint, 2005], Brown's results (cf. [L.G. Brown, Lidskii's theorem in the type II case, in: H. Araki, E. Effros (Eds.), Geometric Methods in Operator Algebras, Kyoto, 1983, in: Pitman Res. Notes Math. Ser., vol. 123, Longman Sci. Tech., 1986, pp. 1-35]) on the Brown measure of an operator in a type II₁ factor (M,τ) are generalized to finite sets of commuting operators in M. It is shown that whenever T₁,…,Tn∈M are mutually commuting operators, there exists one and only one compactly supported Borel probability measure μT₁,…,Tn on B(Cn) such that for all α₁,…,αn∈C,

     

The promoted hydrolysis effect of cellulase with ultrasound treatment is reflected on the sonicated rather than native brown rice

Brown rice is nutritionally superior to polished white rice, as it maintains a large content of external bran that involves a series of bioactive compounds. However, the presence of bran also restricts water diffusion and results in adverse quality of brown rice. In this work, ultrasound conditions were optimized for cellulase to improve its hydrolysis effect on rice bran, and combinations of enzymatic and ultrasound treatment in different manners were conducted on brown rice, to improve the textural attributes. The results showed significant improvements in the catalytic activity and efficiency of cellulase after ultrasonication at the optimal intensity of 1.67 W cm⁻³ and duration of 30 min, with the conformational variation of cellulase observed from the fluorescence spectra and circular dichroism (CD). Despite the enhanced activity of ultrasonicated cellulase, it leaded to a similar rice surface morphology and a comparable amount of released glucose, and equivalent textural parameters of brown rice treated by native cellulase. However, for the pre-sonicated brown rice, the ultrasonicated cellulase showed a significantly higher hydrolysis capacity than the untreated enzyme, suggesting the important influence of ruptured bran surface on amplifying the hydrolysis effect of cellulase. Compared to the successive ultrasound stimulation on both cellulase and brown rice, ultrasound-assisted cellulase treatment on brown rice produced less glucose from rice bran, but induced similar textural properties of brown rice, possibly resulting from the simultaneously promoting effect of ultrasonication on cellulase and water diffusion. Ultimately, this study highlighted that the mild rice surface rupture is a crucial factor to display the promoted hydrolysis effect of ultrasonicated cellulase on brown rice. Ultrasound-assisted cellulase treatment potentially provides an effective strategy to improve the edible quality of brown rice.     

带干扰风险的破产模型的研究

本文对古典风险模型中保险公司按单位时间常数率收到保险费的假设做了改进,将每次收到的保险费的次数看作是复合泊松过程,将每次收到的保费和每次的理陪额均看作是服从指数分布的随机变量,并引入带干扰风险的扰动项,从而对古典风险模型进行推广,且给出了相应的破产概率上界,分析了破产概率的上界与准备金,索赔额,净保费和扰动方差之间的关系。     

Enhancement of AC-losses of magnetic nanoparticles for heating applications

Aqueous ferrofluids of maghemite nanoparticles coated with carboxydextran were investigated with respect to their specific loss power (SLP) in dependence on frequency and field amplitude of magnetic AC-fields. In order to elucidate the effect of the size distribution on SLP fluid fractions with different mean particle core size were prepared by a magnetic separation procedure from the original ferrofluid. Structural characterisation by means of TEM and XRD as well as reconstruction of core size distributions from magnetisation curves reveals that the narrow size distributions of the fractions cover a range of mean core sizes from about 8 up to 20 nm. Spectra of the complex susceptibility were measured for a frequency range of 20 Hz to 1 MHz. From the imaginary part of the susceptibility the specific loss power is calculated in dependence on frequency. The results are compared with calorimetrical measurements performed in dependence on field amplitude up to 11 kA/m at 410 kHz. A very high specific loss power in the order of 400 W per gram maghemite was found at 410 kHz and 11 kA/m for the fluid fraction having the largest mean core diameter. A deviation from linear response behaviour is found for this sample showing a power law field dependence of the specific loss power SLPH^2.5. In addition to liquid suspensions measurements were performed with particles immobilised in mannitol or gel in order to elucidate the role of Brownian relaxation. The experimentally found dependence of SLP on the mean particle core diameter may be understood in the frame of the Debye dispersion model. Results are discussed with respect to applications of ferrofluids in RF-magnetic hyperthermia.     

双电极对脉冲放电时间间隔τ=0s时的能量增强效应

In this paper we it is presented a self-similar image model based on Fractional Brown Motion (FBM), in which the various structure functions and scale dependent Hurst parameters can be choosed to simulate the scale-dependent textures. The method is quite efficient for generation of realistic nature textures and synthesis of digital holograms. The synthesized digital holograms can be used in laser anti-counterfeiting field.     

Joint remote preparation of an arbitrary five-qubit Brown state via non-maximally entangled channels

We firstly present a novel scheme for deterministic joint remote state preparation of an arbitrary five-qubit Brown state using four Greenberg–Horme–Zeilinger(GHZ)entangled states as the quantum channel.The success probability of this scheme is up to 1,which is superior to the existing ones.Moreover,the scheme is extended to the generalized case where three-qubit and four-qubit non-maximally entangled states are taken as the quantum channel.We simultaneously employ two common methods to reconstruct the desired state.By comparing these two methods,we draw a conclusion that the first is superior to the second-optimal positive operator-valued measure only taking into account the number of auxiliary particles and the success probability.     

标的资产服从一类混合过程的欧式未定权益定价

文中假设标的资产价格服从受分数布朗运动和泊松过程共同驱动的一类混合模型，并给出了基于这一模型的欧式未定权益定价的基本公式，以及欧式看涨、看跌期权和上限型欧式期权的定价公式。     

A linear algebra approach to Koethe's problem and related questions

We discuss several problems on the structure of nil rings from the linear algebra point of view. Among others, a number of questions and results are presented concerning algebras of infinite matrices over nil algebras, and nil algebras of infinite matrices over fields, which are related to the famous Koethe's problem. Some questions on radicals of tensor products of algebras related to Koethe's problem are also discussed.