Asymptotic formulae for likelihood-based tests of new physics

We describe likelihood-based statistical tests for use in high energy physics for the discovery of new phenomena and for construction of confidence intervals on model parameters. We focus on the properties of the test procedures that allow one to account for systematic uncertainties. Explicit formulae for the asymptotic distributions of test statistics are derived using results of Wilks and Wald. We motivate and justify the use of a representative data set, called the “Asimov data set”, which provides a simple method to obtain the median experimental sensitivity of a search or measurement as well as fluctuations about this expectation.     

Sparse asymptotic minimum variance based bearing estimation algorithm for a single vector hydrophone

For underwater target detection using a single vector hydrophone, sparse asymptotic minimum variance(SAMV) method is used to estimate the target bearing. The SAMV discretizes the entire scanning space and the target bearing is located at the position of the discrete direction. The SAMV algorithm utilizes the sparsity of the spatial signal to improve the estimation performance of the target bearing. Background noise level(BNL) of the bearing estimation of SAMV algorithm is lower than those of the conventional beam forming(CBF)method and minimum variance distortionless response(MVDR) method for different signal noise ratios(SNRs). When the SNR is higher than 0 d B, the direction-finding error of this algorithm is less than 2°. Moreover, the SAMV algorithm has a better dimensional orientation resolution capability. The experimental results show that the SAMV algorithm gives a bearing and time recording map with a lower BNL, which effectively verifies the effectiveness of SAMV algorithm in terms of underwater target detection.     

离子交换色谱法分离测定磷霉素的研究

分别采用全多孔型硅胶基键合强阴离子交换柱与氨丙基键合硅胶柱,在低波长 ２００ ｎｍ 处检测,分离测定了磷霉素 探讨了流动相条件,如ｐ Ｈ 值、离子强度等对磷霉素保留及分离选择性的影响,优化分离条件,建立了一种测定磷霉素的高效液相色谱新方法方法简便、快速     

交通流非参数回归模型

交通流宏观参数流量、速度和占有率在交通工程和管理中具有非常重要的作用 ,对这三者关系的刻划反映了道路本身特性和交通流的规律。到目前为止 ,基本上采用线性或非线性的参数模型来描述 ,此类模型在应用中具有一定的局限性 ,并交通变量时间序列进行预测 ,数据拟合表明 ,选择适当的核函数或邻近数以及窗宽 ,可以达到比较满意的效果     

The photoelectron spectrum of thiazyl fluoride (NSF)

The photoelectron spectrum of thiazyl fluoride has been recorded. An assignment of the first five bands has been attempted, using semi-empirical calculations.     

A bivariate exponential distribution arising in random geometry

Summary In this paper a new bivariate exponential distribution, arising naturally in the theory of Poisson line processes, is studied. The distribution has some interesting and useful properties which renders it suitable for use in statistical modelling work. It is presented in the spirit of adding to the repertoire of bivariate exponential forms. It joins other models, such as those of Downton (1970,J. R. Statist. Soc., B,32, 408–417), Marshall and Olkin (1967,J. Appl. Prob.,4, 291–302) and Nagao and Kadoya (1971,Bulletin of the Disaster Prevention Research Institute,20, 3, 183–215), which have their origins in the theory of stochastic processes.     

Oxygen deficient α-Fe2O3 photoelectrodes: a balance between enhanced electrical properties and trap-mediated losses

Intrinsic doping of hematite through the inclusion of oxygen vacancies (V_O) is being increasingly explored as a simple, low temperature route to preparing active water splitting α-Fe₂O_3–x photoelectrodes. Whilst it is widely accepted that the introduction of V_O leads to improved conductivities, little else is verified regarding the actual mechanism of enhancement. Here we employ transient absorption (TA) spectroscopy to build a comprehensive kinetic model for water oxidation on α-Fe₂O_3–x. In contrast to previous suggestions, the primary effect of introducing V_O is to block very slow (ms) surface hole – bulk electron recombination pathways. In light of our mechanistic research we are also able to identify and address a cause of the high photocurrent onset potential, a common issue with this class of electrodes. Atomic layer deposition (ALD) of Al₂O₃ is found to be particularly effective with α-Fe₂O_3–x, leading to the photocurrent onset potential shifting by ca. 200 mV. Significantly TA measurements on these ALD passivated electrodes also provide important insights into the role of passivating layers, that are relevant to the wider development of α-Fe₂O₃ photoelectrodes.     

Constraints on the fundamental topological parameters of spatial tessellations

Tessellations of that use convex polyhedral cells to fill the space can be extremely complicated, especially if they are not “facet‐to‐facet”, that is, if the facets of a cell do not necessarily coincide with the facets of that cell's neighbours. In a recent paper 15 , we have developed a theory which covers these complicated cases, at least with respect to their combinatorial topology. The theory required seven parameters, three of which suffice for facet‐to‐facet cases; the remaining four parameters are needed for the awkward adjacency concepts that arise in the general case. This current paper establishes constraints that apply to these seven parameters and so defines a permissible region within their seven‐dimensional space, a region which we discover is not bounded. Our constraints in the relatively simple facet‐to‐facet case are also new.     

Factors influencing the DNA nuclease activity of iron, cobalt, nickel, and copper chelates

A library of complexes that included iron, cobalt, nickel, and copper chelates of cyclam, cyclen, DOTA, DTPA, EDTA, tripeptide GGH, tetrapeptide KGHK, NTA, and TACN was evaluated for DNA nuclease activity, ascorbate consumption, superoxide and hydroxyl radical generation, and reduction potential under physiologically relevant conditions. Plasmid DNA cleavage rates demonstrated by combinations of each complex and biological co-reactants were quantified by gel electrophoresis, yielding second-order rate constants for DNA(supercoiled) to DNA(nicked) conversion up to 2.5 × 10(6) M(-1) min(-1), and for DNA(nicked) to DNA(linear) up to 7 × 10(5) M(-1) min(-1). Relative rates of radical generation and characterization of radical species were determined by reaction with the fluorescent radical probes TEMPO-9-AC and rhodamine B. Ascorbate turnover rate constants ranging from 3 × 10(-4) to 0.13 min(-1) were determined, although many complexes demonstrated no measurable activity. Inhibition and Freifelder-Trumbo analysis of DNA cleavage supported concerted cleavage of dsDNA by a metal-associated reactive oxygen species (ROS) in the case of Cu(2+)(aq), Cu-KGHK, Co-KGHK, and Cu-NTA and stepwise cleavage for Fe(2+)(aq), Cu-cyclam, Cu-cyclen, Co-cyclen, Cu-EDTA, Ni-EDTA, Co-EDTA, Cu-GGH, and Co-NTA. Reduction potentials varied over the range from -362 to +1111 mV versus NHE, and complexes demonstrated optimal catalytic activity in the range of the physiological redox co-reactants ascorbate and peroxide (-66 to +380 mV).     

Influence of charge and structure on the coordination chemistry of copper aminoglycosides

Aminoglycosides are a family of molecules based on a 2-deoxystreptamine ring that is functionalized with a variety of sugar units that contain vicinal amine and hydroxyl functionality. These positively-charged amines promote selective high affinity binding to bacterial 16 s rRNA with resultant antibacterial activity. Aminoglycosides have also been shown to selectively target a variety of therapeutically relevant RNA motifs, and in combination with copper to promote irreversible degradation of the RNA target. The presence of multiple hydroxyl and amine groups on multiple rings creates many potential copper coordination sites. However, only a small subset of these sites actually bind copper, which have not been clearly defined experimentally, Herein we describe a more extensive structural characterization of the complexes of six aminoglycosides (kanamycin A, kanamycin B, neomycin B, neamine, tobramycin and paromomycin) that provide insights on the factors contributing to the coordination selectivity of aminoglycosides toward divalent copper. The presence of vicinal ligand donors capable of chelating the copper ion appears to be a prerequisite for stable metal binding, with charge density providing further tuning of the K(D). A possible role for metal coordination in antibacterial activity is also considered.