Development of a fast neutron radiography converter using wavelength-shifting fibers

A fluorescent converter for fast neutron radiography (FNR) comprising a scintillator and hydrogen-rich resin has been developed and applied to electronic imaging. The rate of the reaction between fast neutrons and the converter is increased by thickening the converter, but its opaqueness attenuates emitted light photons before they reach its surface. To improve the luminosity of a fluorescent converter for FNR, a novel type of converter was designed in which wavelength-shifting fibers were adopted to transport radiated light to the observation end face. The performance of the converter was compared with that of a polypropylene-based fluorescent converter in an experiment conducted at the fast-neutron-source reactor YAYOI in the University of Tokyo.     

Analysis of ink flow in a mimeograph printer based on the mechanics of fluid-filled poroelastic solids

Summary To understand some main ink flow mechanisms in a mimeograph printer, the continuum mechanics theory of fluid-saturated porous solids is applied to analyze the ink flow through screens and a printing master, which are modeled by a fluid-filled poroelastic single layer. The layer is assumed to be pressed by a press roller from below and to be subjected from above to the hydrodynamic lubrication pressure induced between a printing drum and an ink roller. Nonlinear elasticity of the layer and dependence of the permeability on its deformation are taken into account. The numerical results show some important results: e.g., squeezing-out of the ink from the layer by the layer compaction by the press roller plays an important role, especially for the case where the compression duration is small in comparison with the characteristic time of the ink-filled poroelastic layer.     

MiR-10a in Pancreatic Juice as a Biomarker for Invasive Intraductal Papillary Mucinous Neoplasm by miRNA Sequencing

New biomarkers are needed to further stratify the risk of malignancy in intraductal papillary mucinous neoplasm (IPMN). Although microRNAs (miRNAs) are expected to be stable biomarkers, they can vary owing to a lack of definite internal controls. To identify universal biomarkers for invasive IPMN, we performed miRNA sequencing using tumor-normal paired samples. A total of 19 resected tissues and 13 pancreatic juice samples from 32 IPMN patients were analyzed for miRNA expression by next-generation sequencing with a two-step normalization of miRNA sequence data. The miRNAs involved in IPMN associated with invasive carcinoma were identified from this tissue analysis and further verified with the pancreatic juice samples. From the tumor-normal paired tissue analysis of the expression levels of 2792 miRNAs, 20 upregulated and 17 downregulated miRNAs were identified. In IPMN associated with invasive carcinoma (INV), miR-10a-5p and miR-221-3p were upregulated and miR-148a-3p was downregulated when compared with noninvasive IPMN. When these findings were further validated with pancreatic juice samples, miR-10a-5p was found to be elevated in INV (p = 0.002). Therefore, three differentially expressed miRNAs were identified in tissues with INV, and the expression of miR-10a-5p was also elevated in pancreatic juice samples with INV. MiR-10a-5p is a promising additional biomarker for invasive IPMN.     

Environmentally benign precipitation copolymerization of methacrylate ester and styrene to make polymeric microspheres in supercritical carbon dioxide

The polymeric microspheres were synthesized by the precipitation copolymerization of glycidyl methacrylate (GMA) with methacrylic acid(MAA) or 2‐hydoxyethyl methacrylate (2‐HEMA) containing styrene (ST) in SC‐CO₂. Scanning electron microscopy (SEM) showed that the products were spherical microparticles, with the addition of MAA and/or 2‐HEMA as the monomer, with diameter of 0.2–2 μm. The effects of copolymerization pressure, temperature, and ratios of GMA/MAA, ST, and/or GMA/2‐HEMA, on the particle size and morphology were investigated in detail. A new experiment setup is proposed for the large amount of production, based on the rule of lower monomer concentration, more stable system, and better use of the present polymerization apparatus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2425–2431, 2007     

Optical absorption in the two-dimensional two-band model

The optical properties are studied within the two-dimensional two-band model with the antiferromagnetic exchange interaction between nearest-neighbord andp spins in the Cu-O sheet. The optical-absorption spectra are computed within the mean-field theory with the periodic boundary condition. An insulating gap of about 1.7 eV appears for nondoping. A Drude peak appears for a singlep hole. The Drude peak and the in-gap state appear for twop holes. The intensity of the charge-transfer band decreases, while those of the Drude peak and the in-gap state increase with doping. It turns out that the strong Coulomb repulsion and the orbital are important such as thep _x orp _y orbital in the electronic properties of high-T _c copper oxides.     

MHz-driven snubberless zero-current soft-switching high step-up DC-DC converter with a multi-resonant tank

A novel high step-up DC-DC converter suitable for the power interface of fuel cells (FC) is presented in this paper. The proposed converter features a multi-resonant tank for achieving high-step up ratio under zero current soft switching (ZCS) without any snubber circuits. The simple and minimized-component topology is beneficial for megahertz driving of gallium nitride (GaN) power transistors with effective reductions of switching loss, electromagnetic emission interference (EMI) noise, and ripple-free DC input current. Mode-transitional power stages are described in detail, following that the high step-up principle is revealed by means of frequency-domain analysis. The essential performances of the proposed circuit topology are demonstrated by simulation and experiment of 1.8 MHz-120W prototype whereby effectiveness of the snubberless and multi-resonant topology are verified from the practical point of view.     

Multi-contact vertical ladder climbing with an HRP-2 humanoid

We describe the research and the integration methods we developed to make the HRP-2 humanoid robot climb vertical industrial-norm ladders. We use our multi-contact planner and multi-objective closed-loop control formulated as a QP (quadratic program). First, a set of contacts to climb the ladder is planned off-line (automatically or by the user). These contacts are provided as an input for a finite state machine. The latter builds supplementary tasks that account for geometric uncertainties and specific grasps procedures to be added to the QP controller. The latter provides instant desired states in terms of joint accelerations and contact forces to be tracked by the embedded low-level motor controllers. Our trials revealed that hardware changes are necessary, and parts of software must be made more robust. Yet, we confirmed that HRP-2 has the kinematic and power capabilities to climb real industrial ladders, such as those found in nuclear power plants and large scale manufacturing factories (e.g. aircraft, shipyard) and construction sites.     

Effective indices to characterize short sequences of human random generations

Brain impediments such as dementia are a serious problem today. It would be very useful if software for private diagnosis were available. In this paper, we show the effectiveness of the human random generation test (HRG) for such software, and propose a set of four indices to be used for classifying the HRG data. Human-generated random numbers have strong characteristics compared to computer-generated random numbers, and these are known to be correlated to the individual characters of the subjects. However, analysis using the correlation dimension or HMM requires a long data sequence, and thus is not suitable for diagnoses. We therefore focus on short sequences of HRG and search for effective indices to detect signs of brain disability hidden in the HRG data. We studied data from subjects of different age groups, and successfully differentiated the data from the different groups. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Prospective study of "early" gastric cancer

In order to elucidate the natural history of early gastric cancer, we followed up non-concurrently certain patients who had been diagnosed endoscopically as having "early' gastric cancer and who had histological evidence of cancer by biopsy, but on whom surgical resection had been delayed or had not been conducted. At the Center for Adult Diseases, Osaka, 56 cases were eligible for this study. Out of these, 27 cases progressed to advanced cancer and 16 remained at the early stage during the follow-up period (6-88 months, mean: 29 months). The remaining 13 cases had had neither surgical resection nor examinations. The survivorship function for the duration of "early" gastric cancer was estimated by the life-table method of Kaplan and Meier. The median of the duration was estimated as 37 months. The 5-year survival rate of the 34 cases on whom surgical resection had not been conducted was estimated as 64.5%. These results suggest that early diagnosis and early treatment may lead to a reduction of mortality from stomach cancer.