Major Issues and Challenges of Influenza Pandemic Preparedness in Developing Countries

Summary line: A pandemic is a global issue, and pandemic preparedness should be considered from a global perspective

アルベール・カミュの「客」について : 教師と生徒の関係を中心として

伊地智均教授退職記念

『追放と王国』について : 「不貞の女」と「生い出ずる石」を中心として

加藤美雄教授退職記念

Electronic Phase Transition of Cesium Metal under High Pressure

The isostructural phase transition of cesium metal, CsII←→CsIII, under pressure is discussed in terms of the crystalline energy as a function of volume. Using the augmented plane wave (APW) method and the quantum defect method, the energy bands are calculated at symmetry points in the Brillouin zone for the ran e of relative volume V/V_0 (V_0 : the volume at normal pressure) from 1.30 to 0.24. As the volume decreases, there appears a pronounced tendency of d-states to fall lower relative to s-states, which rise significantly at V/V_0≤0.6. Besides overall rise of the band energy with decreasing volume, a small humped portion is found at 0.4≤V/V_0≤0.5, this being attributed to the shift of electrons into the vicinity of X. The transition beyond this portion is accompanied by a significant volume change. Thus the CsII←→CsIII transition is interpreted as an electronic one. A calculation using the Green\u27s function method is also carried out and the results are compared with those by the APW method

Ultrasonic Attenuation in Steel and Cast Iron

Ultrasonic attenuation in steel and cast iron with various kinds of texture were measured in the frequency range from 0.5 to 25 megacycles per second making use of pulsed longitudinal ultrasonic waves. For this purpose, several processes of heat treatments were applied successively to the same specimens and at every stage of such treatments the attenuation measurements were carried out. The chromium-molybdenum steel and carbon steel specimens were normalized, hardened by quenching, and tempered to make the structure of troostite and sorbite, and the differences among attenuations at each stage were determined. For determining the effect of austenite grain size on the ultrasonic attenuation, the measurements were made for the carbon steel specimens heat-treated above transformation point. The white cast iron was prepared, then tempered successively till the spheroid graphite structures were reached, and the attenuations were studied at every stage of tempering. The attenuation measurements were also made both for flake graphite cast iron with various sizes of flake graphite distributing in wide range and for spheroid graphite cast iron, and the effects of the shape and size of crystallized graphite on the attenuation were studied. The results of measurements are summarized as follows : (1) In the case of steel ultrasonic attenuation varies remarkably with the change of the texture. In the specimens with pearlite structure, a large attenuation value was observed and the value rose steeply with frequency, so that the sound wave hardly penetrated through this medium at frequencies higher than about 10 Mc/sec. The predominant factor causing such a high attenuation is the grain size of austenite phase. In quenched specimens of martensite structure the ultrasonic attenuation was fairly low at high frequencies as 20 Mc/sec. In tempered specimens of troostite or sorbite structure, the lower attenuation values were observed. And these low attenuations are considered to be caused by the elastically anisotropic character of each grain. (2) In cast iron the ultrasonic attenuation shows complicated dependence upon the texture. The form and size of crystallized graphite in cast iron have remarkable effect on the attenuation. White cast iron without crystallized graphite has low attenuation value. In flake graphite cast iron, very high attenuation was observed and the value increased steeply with frequency. These characters are determined directly by the size of flake graphite. The cast iron of intermediate structure, including spheroid graphite cast iron, has medium value. (3) The most predominant factor determining the magnitude of ultrasonic attenuation is the Rayleigh scattering of ultrasound by grains. The rate of energy loss by scattering depends upon the size and elastically anisotropic character of the crystal grains

High Pressure Apparatus for Angle Dispersive Neutron Diffraction

A piston-cylinder type high pressure apparatus was designed for the angle dispersive neutron diffraction. A Ti-53wt% Zr alloy was used for the cylinder. The performance was tested by observing the structural transformation under pressure in RbBr from an NaCl-type to a CsCl-type

Evolution of the M gene of the influenza A virus in different host species: large-scale sequence analysis

<p>Abstract</p> <p>Background</p> <p>Influenza A virus infects not only humans, but also other species including avian and swine. If a novel influenza A subtype acquires the ability to spread between humans efficiently, it could cause the next pandemic. Therefore it is necessary to understand the evolutionary processes of influenza A viruses in various hosts in order to gain better knowledge about the emergence of pandemic virus. The virus has segmented RNA genome and 7th segment, M gene, encodes 2 proteins. M1 is a matrix protein and M2 is a membrane protein. The M gene may be involved in determining host tropism. Besides, novel vaccines targeting M1 or M2 protein to confer cross subtype protection have been under development. We conducted the present study to investigate the evolution of the M gene by analyzing its sequence in different species.</p> <p>Results</p> <p>Phylogenetic tree revealed host-specific lineages and evolution rates were different among species. Selective pressure on M2 was stronger than that on M1. Selective pressure on M1 for human influenza was stronger than that for avian influenza, as well as M2. Site-by-site analyses identified one site (amino acid position 219) in M1 as positively selected in human. Positions 115 and 121 in M1, at which consensus amino acids were different between human and avian, were under negative selection in both hosts. As to M2, 10 sites were under positive selection in human. Seven sites locate in extracellular domain. That might be due to host's immune pressure. One site (position 27) positively selected in transmembrane domain is known to be associated with drug resistance. And, two sites (positions 57 and 89) locate in cytoplasmic domain. The sites are involved in several functions.</p> <p>Conclusion</p> <p>The M gene of influenza A virus has evolved independently, under different selective pressure on M1 and M2 among different hosts. We found potentially important sites that may be related to host tropism and immune responses. These sites may be important for evolutional process in different hosts and host adaptation.</p