Critical Number of Fermion Flavors at Finite Chemical Potential in QED3

We propose a new method for calculating the dressed fermion propagator at finite chemical potential in QED3 under the rainbow approximation of Dyson-Schwinger equation. In the above approximation, we show that the dressed fermion propagator at finite chemical potential # has the form S（p） = iγ.p^-A（p^-2） ＋ B（ p^-2） with p^-μ= （p^-1p3 ＋ iμ）. Using this form of fermion propagator at nonzero chemical potential, we investigate the Dyson-Schwinger equation for the dressed fermion propagator at finite chemical potential and study the effects of the chemical potential on the critical number of the fermion flavors.     

形式三角矩阵环的特殊性质

We consider the sufficient and necessary conditions for the formal triangular matrix ring being right minsymmetric,right DS,semicommutative,respectively.     

Development of variance‐filtered instrumental transfer methods for high‐resolution NMR spectroscopy

The introduction of a variance‐filter to both direct standardization (DS) and piece‐wise direct standardization (PDS) instrumental transfer methods for the analysis of NMR spectral data is described. The variance‐filter modification allows for the identification of regions in the NMR spectra that are not adequately represented by the limited number of transfer calibration samples used during the calculation of the instrument‐to‐instrument transfer matrix. For these spectral frequencies, the corresponding portion of the transfer matrix is replaced by identity (or scaled identity) prior to the secondary instrumental data sets being transferred to the target instrument response. The spectral matching performance of the variance‐filtered instrumental transfer method as applied to high‐resolution ¹H NMR spectra is presented along with possible uses and limitations. Copyright © 2010 John Wiley & Sons, Ltd.     

Statistical approach to the code acquisition problem in direct-sequence spread-spectrum communication systems

^** Email: eshima{at}med.oita-u.ac.jp In direct-sequence spread-spectrum (DS/SS) communication, users'original signals are modulated into higher frequencies withthe users' codes. DS/SS communication has the attractive propertythat multiple users' signals can be simultaneously transmitted;however, communication cannot be performed without synchronizationof users' spread-spectrum (SS) signal. Synchronization is typicallyperformed in two steps, i.e. code acquisition and tracking.This paper gives a statistical solution to the question as tohow code acquisition can be performed effectively and precisely.First, properties of matched-filter outputs of SS signal arediscussed. Second, a theoretical method of code acquisitionis proposed according to statistical decision theory. The methoduses all matched-filter outputs for code acquisition. Third,matched-filter outputs are dichotomized with a threshold valueand the dichotomous outputs are used for code acquisition. Asimple and effective method for code acquisition is proposed.Numerical simulations are also given to illustrate the effectivenessof the proposed method. Finally, a further discussion and conclusionto this study are provided.     

用微机和CAN总线改进热学实验

用片上自带CAN的微控制器P8XC5 91、数字温度传感器DS1 8B2 0和微机组成温度测试网络系统 ,改进了热学实验 .本文详细叙述了该系统的硬件电路、软件及通信设计     

LOW ENERGY TRIPLE DIFFERENTIAL CROSS SECTIONS FOR ELECTRON IMPACT IONIZATION OF HYDROGEN

ＬＯＷＥＮＥＲＧＹＴＲＩＰＬＥＤＩＦＦＥＲＥＮＴＩＡＬＣＲＯＳＳＳＥＣＴＩＯＮＳＦＯＲＥＬＥＣＴＲＯＮＩＭＰＡＣＴＩＯＮＩＺＡＴＩＯＮＯＦＨＹＤＲＯＧＥＮＣｈｅｎＺｈａｎｇｊｉｎａ，ｂＸｕＫｅｚｕｎｂＸｕＦｕｘｉｎａａＤｅｐａｒｔｍｅｎｔｏｆＰｈｙ...     

Quantitation of low concentrations of polysorbates in high protein concentration formulations by solid phase extraction and cobalt-thiocyanate derivatization

A spectrophotometric method was developed to quantify low polysorbate (PS) levels in biopharmaceutical formulations containing high protein concentrations. In the method, Oasis HLB solid phase extraction (SPE) cartridge was used to extract PS from high protein concentration formulations. After loading a sample, the cartridge was washed with 4 M guanidine HCl and 10% (v/v) methanol, and the retained PS was eluted by acetonitrile. Following the evaporation of acetonitrile, aqueous cobalt-thiocyanate reagent was added to react with the polyoxyethylene oxide chain of polysorbates to form a blue colored PS–cobaltothiocyante complex. This colored complex was then extracted into methylene chloride and measured spectrophotometrically at 620 nm. The method performance was evaluated on three products containing 30–40 mg L⁻¹ PS-20 and PS-80 in ≤70 g L⁻¹ protein formulations. The method was specific (no matrix interference identified in three types of protein formulations), sensitive (quantitation limit of 10 mg L⁻¹ PS) and robust with good precision (relative standard deviation ≤6.4%) and accuracy (spike recoveries from 95% to 101%). The linear range of the method for both PS-20 and PS-80 was 10 to 80 mg L⁻¹ PS. By diluting samples with 6 M guanidine HCl and/or using different methylene chloride volumes to extract the colored complexes of standards and samples, the method could accurately and precisely quantify 40 mg L⁻¹ PS in up to 300 g L⁻¹ protein formulations.     

Capillary electrophoresis-based assessment of nanobody affinity and purity

Drug purity and affinity are essential attributes during development and production of therapeutic proteins. In this work, capillary electrophoresis (CE) was used to determine both the affinity and composition of the biotechnologically produced “nanobody” EGa1, the binding fragment of a heavy-chain-only antibody. EGa1 is an antagonist of the epidermal growth factor receptor (EGFR), which is overexpressed on the surface of tumor cells. Using a background electrolyte (BGE) of 50 mM sodium phosphate (pH 8.0) in combination with a polybrene-poly(vinylsulfonic acid) capillary coating, CE analysis of EGa1 showed the presence of at least three components. Affinity of the EGa1 components towards the extracellular domain of EGFR was assessed by adding different concentrations (0–12 nM) of the receptor to the BGE while measuring the effective electrophoretic mobility of the respective EGa1 components. Binding curves obtained by plotting electrophoretic mobility shifts as a function of receptor concentration, yielded dissociation constants (K_d) of 1.65, 1.67, and 1.75 nM for the three components, respectively; these values were comparable to the K_d of 2.1 nM obtained for the bulk EGa1 product using a cellular assay. CE with mass spectrometry (MS) detection using a BGE of 25 mM ammonium acetate (pH 8.0) revealed that the EGa1 sample comprised of significant amounts of deamidated, bisdeamidated and N-terminal pyroglutamic acid products. CE–MS using a BGE of 100 mM acetic acid (pH 2.8) in combination with a polybrene–dextran sulfate–polybrene capillary coating demonstrated the additional presence of minor products related to incomplete removal of the signal peptide from the produced nanobody. Combining the results obtained from affinity CE and CE–MS, it is concluded that the EGa1 nanobody product is heterogeneous, comprising highly-related proteins that exhibit very similar affinity towards EGFR.     

基于Virtools的平抛运动仿真实验的设计与实现

三维仿真实验能够模拟逼真的实验场景和现象帮助学生理解复杂的物理原理,并激发学生的学习兴趣.但是,专业的研究团队制作的商业仿真实验软件售价太高,无法在课堂推广.本研究小组将以Virtools仿真软件为开发平台制作出一系列的虚拟仿真实验.本论文以平抛运动实验为例,介绍了平抛运动仿真实验的制作过程,主要包括分析与设计、模型的构建、交互功能设计和作品发布四个步骤.在论文的最后部分,介绍了仿真实验在课堂实践的成效并对物理仿真实验的发展前景进行了展望.     

基于能量换测法的热电偶与DS18B20测温系统

VC9808A+数字万用表所附的测温热电偶制造简单,价格便宜,是一般测试温度的必要器件,广泛应用于人们日常生活领域。当传输距离较远且采集到的温度信号还用于控制时,这种测温系统已不能很好适应现代测温的要求。设计了以单片机为核心的DS18B20测温系统,与数字万用表所附的热电偶测温系统进行比对,基于单片机的DS18B20测温系统精度高,抗干扰能力强,使用灵活方便,但成本较高。