A new discriminative kernel from probabilistic models

Recently, Jaakkola and Haussler (1999) proposed a method for constructing kernel functions from probabilistic models. Their so-called Fisher kernel has been combined with discriminative classifiers such as support vector machines and applied successfully in, for example, DNA and protein analysis. Whereas the Fisher kernel is calculated from the marginal log-likelihood, we propose the TOP kernel derived; from tangent vectors of posterior log-odds. Furthermore, we develop a theoretical framework on feature extractors from probabilistic models and use it for analyzing the TOP kernel. In experiments, our new discriminative TOP kernel compares favorably to the Fisher kernel.     

Effect of Cd Substitution for Bi on Superconductivity of the Bi-2201 Phase in the Bi—La—Ca—Cu—O System

A series of the Bi-2201 samples with the nominal composition of (Bi_2–x Cd _x )La_0.7Ca_1.3CuO _z has been synthesized and effect of Cd substitution for Bi on the superconductivity has been investigated. As a result, it is found that almost single phase samples are obtained for a considerable wide composition of 0.0 x 0.8, their crystal structures have a tetragonal or a pseudotetragonal symmetry in the whole composition range, and the sample unexpectedly changes from superconductor to semiconductor by little Cd-substitution of about 0.1. The semiconducting samples show a temperature dependence of the resistivity suggesting that the transport process is followed by a three-dimensional variable range hopping conduction.     

Polarization-maintaining optical fibers used for a laser diode redundancy system in a submarine optical repeater

Polarization-maintaining optical fibers are developed for installation in a submarine optical repeater. These fibers preserve the polarization of light emitted from laser diodes (LD's) to a single-mode fiber through a light-switching coupler. Crosstalk of less than -30 dB in a 1-m length of these optical fibers, called PANDA optical fibers, is achieved with a bending radius greater than 10 mm, twists of less than 60 turns, and tension of less than 3 kg, and ambient temperatures of-20-80degC. The mechanical strength of these fibers is the same as that of single-mode fibers.     

Properties of variable-thickness NbN microbridges

Variable-thickness NbN microbridges have been fabricated by ion etching, using photoresist mask and obliquely evaporated Al films. A tungsten needle ≈3 µm in diameter is placed across the slit produced in the photoresist to define the bridge width. The NbN microbridges show many well-defined constant-voltage steps under microwave irradiation.     

Development of a wrist-worn calorie monitoring system using bluetooth

Methods and tools for monitoring real-time human body information in daily life are required for advanced healthcare. In this study, a method for estimating energy expenditure during health exercises was evaluated and a wrist-worn sensing system based on the method was developed. Pulse monitoring was used to calculate energy expenditure by estimating oxygen uptake from a correlation between heart rate and oxygen uptake. Bluetooth technology was utilized for sending data by wireless communication. By the newly developed system, energy expenditure during exercise can be estimated considering individual difference and distinguishing changes in grade or load. Our goal is to construct a miniaturized wearable system that monitors vital signs and has many applications for healthcare. The study suggests that a wearable pulse sensing system proposed could provide useful information for healthcare.     

Low-loss single polarisation fibres with asymmetrical strain birefringence

Low-loss and highly birefringent single polarisation fibres have been fabricated. The minimum transmission loss and the modal birefringence of the fibre with refractive-index difference ?=0.61% was 0.62 dB/km at ?=1.52 ?m and 8.5×10?5 at ?=1.15 ?m, respectively. The state of linear polarisation was stable against the handling conditions such as bending, twists, concentrated force, and temperature variations.     

Low crosstalk polarisation-maintaining optical fibre with an 11 km length

An 11 km-long polarisation-maintaining optical fibre with crosstalk up to ?25.2 dB and ?22.5 dB at 1.30 ?m and 1.56 ?m, respectively, is presented. Transmission loss is 1.2 dB/km at 1.3 ?m and has a minimum value of 0.79 dB/km at 1.56 ?m.     

Design and fabrication of low-loss and low-crosstalk polarization-maintaining optical fibers

Low-loss and low-crosstalk polarization-maintaining optical fibers (called PANDA fibers), which are potentially useful for coherent optical communication systems, have been fabricated based on the optimum design. Transmission loss of 0.22 dB/km, comparable to that of commercially available single-mode fibers, and crosstalk of -27 dB in a 5-km length, corresponding to the polarization-mode-coupling coefficient of4.0 times 10^{-7}m^-1, have been demonstrated in the 1.56-μm wavelength.     

A hierarchical algorithm for MR brain image parcellation

We introduce an algorithm for segmenting brain magnetic resonance (MR) images into anatomical compartments such as the major tissue classes and neuro-anatomical structures of the gray matter. The algorithm is guided by prior information represented within a tree structure. The tree mirrors the hierarchy of anatomical structures and the subtrees correspond to limited segmentation problems. The solution to each problem is estimated via a conventional classifier. Our algorithm can be adapted to a wide range of segmentation problems by modifying the tree structure or replacing the classifier. We evaluate the performance of our new segmentation approach by revisiting a previously published statistical group comparison between first-episode schizophrenia patients, first-episode affective psychosis patients, and comparison subjects. The original study is based on 50 MR volumes in which an expert identified the brain tissue classes as well as the superior temporal gyrus, amygdala, and hippocampus. We generate analogous segmentations using our new method and repeat the statistical group comparison. The results of our analysis are similar to the original findings, except for one structure (the left superior temporal gyrus) in which a trend-level statistical significance (p = 0.07) was observed instead of statistical significance.