Isolation and structure determination of a new thiopeptide globimycin from Streptomyces globisporus subsp. globisporus based on genome mining

Based on genome-mining, a new thiopeptide globimycin was discovered from the extract of Streptomyces globisporus subsp. globisporus, along with known one radamycin. The structure of globimycin was established by a combination of 2D NMR and ESI-MS experiments, and globimycin was identified to be a structural isomer of a known thiopeptide methylsulfomycin. The proposed biosynthetic gene cluster for globimycin and radamycin was found in the genome of S. globisporus subsp. globisporus.     

Shrinkage minimax estimation and positive-part rule for a mean matrix in an elliptically contoured distribution

This paper addresses the problem of estimating the mean matrix of an elliptically contoured distribution with an unknown scale matrix. The unbiased estimator of the mean matrix is shown to be minimax relative to a quadratic loss. This fact yields minimaxity of a matricial shrinkage estimator improving on the unbiased estimator. A positive-part rule for eigenvalues of matricial shrinkage factor provides a better estimator than the shrinkage minimax one.     

Stein's phenomenon in estimation of means restricted to a polyhedral convex cone

This paper treats the problem of estimating the restricted means of normal distributions with a known variance, where the means are restricted to a polyhedral convex cone which includes various restrictions such as positive orthant, simple order, tree order and umbrella order restrictions. In the context of the simultaneous estimation of the restricted means, it is of great interest to investigate decision-theoretic properties of the generalized Bayes estimator against the uniform prior distribution over the polyhedral convex cone. In this paper, the generalized Bayes estimator is shown to be minimax. It is also proved that it is admissible in the one- or two-dimensional case, but is improved on by a shrinkage estimator in the three- or more-dimensional case. This means that the so-called Stein phenomenon on the minimax generalized Bayes estimator can be extended to the case where the means are restricted to the polyhedral convex cone. The risk behaviors of the estimators are investigated through Monte Carlo simulation, and it is revealed that the shrinkage estimator has a substantial risk reduction.     

Full-parallax three-dimensional display based on light field reproduction

Optical Review - Light field displays can display three-dimensional (3D) images with smooth motion parallax without the use of special glasses, by reproducing light ray information from objects....     

Fraunhofer Diffraction Pattern by a Slit Aperture between a Knife Edge and a Metal Cylinder

The Fraunhofer diffraction pattern of an aperture formed between a knife edge and a smooth surface of a turned metal cylinder or half cylinder is different from the diffraction pattern of an ideal slit aperture. The diffraction pattern is simulated by adding the light reflected by the cylinder surface to the pattern formed by a slit, and is measured using a cylinder that has been partly cut away so that it can represent either a full or half cylinder. The theoretical and measured patterns agree well with each other.     

Disk Noise Measurement System for Optical Disks

We developed a system to measure disk noise as a function of both radial and angular position. In order to obtain an accurate disk noise measurement, crosstalk and intersymbol interference were avoided by recording regularly repeating pit patterns and the influence of electronic and laser noise was removed by averaging techniques. We found the system’s mapping ability and its high sensitivity to be very useful in investigating disk noise phenomena in the mastering process. We used the system to assess the accuracy and reproducibility of the photopolymerization replication and Al vapor deposition processes. Also, we investigated the choice of photoresist and found that photoresists with the combination of the narrowest molecular weight distribution and the highest photo-active compound content resulted in the lowest disk noise levels. Our system can, in principle, be adapted to evaluate magneto-optical and phase change disks.     

Conditions for swappability of records in a microdata set when some marginals are fixed

We consider swapping of two records in a microdata set for the purpose of disclosure control. We give some necessary and sufficient conditions that some observations can be swapped between two records under the restriction that a given set of marginals are fixed. We also give an algorithm to find another record for swapping if one wants to swap out some observations from a particular record.     

In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry

We propose detecting a fragment ion (Ph₂As⁺) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH⁺) of DA, DC, DPAH, and BDPAO could produce Ph₂As⁺ through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph₂As⁺ signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH⁺ signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph₂As⁺.

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X-ray photoelectron spectroscopy characterization of oxidated Si particles formed by pulsed ion-beam ablation

X-ray photoelectron spectroscopy (XPS) is used to probe oxidation states of Si species in particles deposited using a pulsed ion-beam evaporation method. The effects of He ambient gas, ion beam intensity and post-treatments on the oxides composition and oxygen content have been studied. It is found that presence of He ambient gas led to a profound oxidation of Si species as compared to that prepared in vacuum at the same ion-beam ablation energy, i.e. both increase of SiO₂ component and oxygen concentration in the oxides coverage. The deposition in He also resulted in an increase of oxygen concentration even under lower ablation intensity, but a higher Si suboxides concentration. It is revealed that the reaction between Si and O was controlled by the ion beam intensity (temperature of Si plasma) and the gas ambient (collision probability of Si and O species). The difference in structure of oxide layers for samples obtained under various conditions is discussed based on the results of XPS analyses.