Fourier synthesis image reconstruction by use of one-dimensional position-sensitive detectors

An improvement of Fourier synthesis optics for hard x-ray imaging is described, and the basic performance of the new optics is confirmed through numerical simulations. The original concept of the Fourier synthesis imager utilizes nonposition-sensitive hard x-ray detectors coupled to individual bigrid modulation collimators. The improved concept employs a one-dimensional position-sensitive detector (such as a CdTe strip detector) instead of the second grid layer of each bigrid modulation collimator. This improves the imaging performance in several respects over the original design. One performance improvement is a two-fold increase in the average transmission, from 1/4 to 1/2. The second merit is that both the sine and cosine components can be derived from a single grid-detector module, and hence the number of imaging modules can be halved. Furthermore, it provides information along the depth direction simultaneously. This in turn enables a three-dimensional imaging hard x-ray microscope for medical diagnostics, incorporating radioactive tracers. A conceptual design of such a microscope is presented, designed to provide a field of view of 4 mm and a spatial resolution of 400 microm.     

EELFS as a new tool of local structural characterization of solid surfaces

A new apparatus to obtain information on local structures and chemical states of solid surfaces has been constructed, with which we measure electron energy-loss fine structures (EELFS), excited by electrons of a few keV incident at a grazing angle. We describe results about O/Ni(100) and O/W(100) systems, where we extensively take advantage of anisotropy in regard to momentum transfer of the probe electron and high surface sensitivity of this technique.     

Analysis of field distributions in a GaAs m.e.s.f.e.t. at large drain voltages

Electric-field distributions and carrier-density distributions in a GaAs m.e.s.f.e.t. at large drain voltages are investigated with a new analytical model, which takes account of the electron-drift-velocity saturation with negative differential mobility and the extension of a depletion layer towards the drain electrode.     

Preparation and characterization of biaxially oriented polypropylene film with high molecular orientation in the machine direction by sequential biaxial stretching

Novel approach of applying the ternary polymer blend of long‐chain branched polypropylene (LCB‐PP), conventional polypropylene (PP), and hydrogenated polydicyclopentadiene (hDCPD) has been employed to tensilize biaxially oriented polypropylene (BOPP) film in the machine direction (MD) by successive sequential biaxial stretching method. It is found that the addition of LCB‐PP improves the MD stretchability of the BOPP film of PP/hDCPD blend. Depending on the content of LCB‐PP, LCB‐PP/PP/hDCPD ternary blend could be biaxially stretched up to the MD stretching ratio (MDX) of 12 without film breakage whereas that of PP (conventional BOPP film) resulted in the MDX up to 6. This excellent MD stretchability enabled to tensilize the BOPP film in the MD, where Young's modulus in the MD could be increased up to 4.9 GPa, twice higher than that of conventional BOPP film. The orientation of total molecular chains and that of crystalline molecular chains were evaluated by in‐plane distribution of refractive indices and wide‐angle X‐ray diffraction, respectively. The results are discussed from the viewpoint of deformation behavior during stretching process. Moreover, the resultant film had a dimensional stability substantially equivalent to that of conventional one, in spite of the higher stretching ratio, and an improved moisture barrier property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Similarity graphing and enzyme-reaction database: methods to detect sequence regions of importance for recognition of chemical structures

We developed a new method which searches sequence segments responsiblefor the recognition of a given chemical structure. These segmentsare detected as those locally conserved among a sequence tobe analyzed (target sequence) and a set of sequences (referencesequences). Reference sequences are the sequences of functionallyrelated proteins, ligands of which contain a common chemicalsubstructure in their molecular structures. ‘Similaritygraphing’ cuts target sequences into segments, alignsthem with reference sequence pairwise, calculates the degreeof similarity for each alignment, and shows graphically cumulativesimilarity values on target sequence. Any locally conservedregions, short or long in length and weak or strong in similarity,are detected at their optimal conditions by adjusting threeparameters. The ‘enzyme-reaction database’ containschemical structures and their related enzymes. When a chemicalsubstructure is input into the database, sequences of the enzymesrelated to the input substructure are systematically searchedfrom the NBRF sequence database and output as reference sequences.Examples of analysis using similarity graphing in combinationwith the enzyme-reaction database showed a great potentialityin the systematic analysis of the relationships between sequencesand molecular recognitions for protein engineering.     

A cognitive load application in tutoring

Research on intelligent tutoring systems has mainly concentrated on how to reduce a cognitive load which a student will bear in learning a domain. This load reduction approach contributes to facilitating his/her learning. However the approach often fails to reinforce the student's comprehension and retention. Another approach to tutoring is to apply a load to him/her purposefully. In this paper, we present a framework for cognitive load application and describe a demonstration system. The framework imposes a load on a student who tries to understand an explanation. The important point toward the load application is to provide the student with an optimal load that does not go beyond his/her capacity for understanding. This requires controlling the student's load by means of explanations. In order to implement such load control, it is necessary to estimate how much load the explanation imposes on his/her understanding process. The load estimate depends on his/her understanding capability since the same explanation imposes a different load according to the capability. Therefore a student model representing his/her capability is required. This paper shows how our system accomplishes a proper load application by generating explanations with the load estimate.     

Palladium(II)‐Catalyzed Aerobic Intermolecular Cyclization of Acrylic Acid with Alkenes to α‐Methylene‐γ‐butyrolactones

The methodology in this article is a palladium(II)/copper(II)‐ or palladium(II)‐catalyzed intermolecular cyclization of acrylic acid with alkenes to produce α‐methylene‐γ‐butyrolactone derivatives using molecular oxygen as an environmentally benign oxidant. In this system, the carboxylato, especially trifluoroacetato, or trimethylacetato ligand, plays a quite important role to afford a high catalytic activity by suppressing the deposition of palladium(0) black.     

Searching for common sequence patterns among distantly related proteins

We have developed a program Gap Allowing Pattern Explorer (GAPE)to extract amino acid sequence motifs conserved among distantlyrelated proteins. The GAPE program is designed to allow gapsin the sequences. First, this program generates all possibleamino acid patterns comprising up to five amino acids. Sequencescontaining the amino acid residues in the same order as a generatedpattern are selected as subsequences, where the differencesin the distances between two consecutive amino acids are ignored.Next, the motifs are extracted from the subsequences under conditionsin which all four distances between the five amino acids arefixed. At this stage, motifs with gaps in their subsequenceare also found by relaxing one of the four fixed distances.The statistical significance for a motif obtained is calculatedbased on the amino acid composition of the sequences under consideration.When the GAPE program was applied to 59 pyridoxal-phosphaterelatedsequences and 64 ATP (AMP-forming)-related sequences, motifsextracted with a low expectation of occurrence contained someof the amino acid residues chemically proved to be involvedin the ligand recognition.     

Economical operation of ( x,s ) control chart indexed by Taguchi's loss function

Assume that lot quality characteristics obey a normal distribution. Kanagawa et al. have proposed the ( x, s ) control chart which enable the user to monitor both changes of the mean and variance simultaneously. Further, the results of Watakabe and Arizono enable the user to evaluate the performance for out-of-control state in the case of using the ( x, s ) control chart. On the other hand, Taguchi has presented an approach to quality improvement in which reduction of deviation from the target value is the guiding principle. In this approach, the loss is expressed as a quadratic form with respect to the difference between the measured value x of a product characteristic X and the target value T of a product quality characteristic. Then, we can evaluate the process quality based on the Taguchi's loss criterion. We consider here the economical operation of the ( x, s ) control chart in conformity with the expected total operation cost function based on the sampling cost and the loss due to derivation in the process quality. First, we consider the economical operation of the ( x, s ) control chart in the situation that the loss to be considered is known. Further, the economical operation of the ( x, s ) control chart is also discussed under any loss instead of a known loss. Then, the relationship between the two economical operations proposed here corresponds to the relationship between the lot tolerance per cent defective plans under the fixed fraction defective and the average outgoing quality limit plans under any fraction defective in rectifying inspection plans.