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Background The aim of the present study was to produce the first estimation in Japan of the basic reproduction number (R(0)) and the minimum level of vaccine coverage needed to prevent measles outbreaks (P(c)). Methods A questionnaire survey was conducted during two measles outbreaks among 12-15-year-old middle school students in one prefecture in spring, from the end of February to the beginning of May 2002, and a stochastic mathematical model was constructed to calculate vaccine effectiveness (VE) and the basic reproduction number (R(0)). P(c) was calculated from R(0) and VE. Results In outbreak 1 (school A), 62 (94%) of 66 patients responded to the questionnaire. Of a total of 601 students, 534 (88.9%) responded. Of these, 82.6% (441/534) had previously received measles vaccine. In outbreak 2 (school B), 20 (99%) of 21 patients responded. Of a total of 375 students, 373 (99.5%) responded. Of these, 317 (85.0%) received measles immunization. Mathematical analysis was as follows: in outbreak 1 R(0) was 7.40 (95% confidence interval [CI]: 7.36-7.44) and VE was 76.55% (95%CI: 53.24-87.54). In outbreak 2, R(0) was 18.89 (95%CI: 18.88-18.90) and VE was 98.54% (95%CI: 94.89-99.73). Consequently, P(c) was 112.97% (95%CI: 92.29-145.52) in outbreak 1 and 96.11% (95%CI: 93.81-98.53) in outbreak 2. Conclusion Because of the lower VE in outbreak 1, measles virus transmission could not have been stopped even if all students received a single dose of vaccine. In outbreak 2, with higher VE, the outbreak could have been prevented by increasing the proportion of students who had been vaccinated.

We demonstrated high-pressure studies on two kinds of layered organics. One is a Mott insulator, β'-(BEDT-TTF) 2 ICl 2 , with an exactly half-filled band. By applying extremely high pressure to it, we observed the highest- T c superconductivity among organics. T c amounts to 14.2 K at 8.2 GPa. The other is a doped-type conductor, κ-(BEDT-TTF) 4 Hg 2.78 Cl 8 , with the band-filling shifted from the half-filled state. We uncovered that it had an anomalous pressure-temperature phase diagram. T c had a minimum structure within the superconducting phase along with pressure axis. In addition, we found that this superconducting phase was lying in between two nonmetallic phases.

We developed a useful method for the detection of rubella virus genome RNA by reverse transcription loop-mediated isothermal amplification (RT-LAMP) and compared the sensitivity of RT-LAMP with that of other virological tests: reverse transcription-PCR (RT-PCR) and virus isolation. The rubella virus genome was amplified by RT-LAMP from clinical isolates obtained between 1987 and 2004 with similar sensitivities to the Takahashi vaccine strain. The detection limit of RT-LAMP was compared with that of RT-PCR using the Takahashi vaccine strain. We detected rubella virus genome material corresponding to 30 PFU/ml in a culture fluid sample by RT-LAMP within 60 min after the extraction of RNA with equal sensitivity to RT-nested PCR. The positive result rates of RT-LAMP, RT-PCR, and virus isolation were also compared using throat swabs obtained from patients who were clinically diagnosed with acute rubella virus infection in 2004 in Tochigi, Japan. Among nine patients with clinical rubella, the positive result rates were three/nine (33.3%) for virus isolation, six/nine (66.7%) for RT-PCR, and seven/nine (77.8%) for RT-LAMP. Consequently, RT-LAMP for rubella virus would be expected to be a reliable rapid diagnostic tool in the clinical setting.

A series of molecular conductors β ′-( cation )[Pd(dmit) 2 ] 2 ( cation = Et 2 Me 2 P and Me 4 P) exhibit various complicated pressure-induced phenomena. Resistivity measurements under high pressure up to 8 GPa have been carried out using a clamp-type piston-cylinder cell and cubic anvil type high pressure apparatus. The Et 2 Me 2 P salt shows non-metallic phases at low and high pressure regions, between which a metallic phase appears. The application of pressure suppresses the low-temperature resistivity of this salt. However, the non-metallic behavior still remains at low temperature under 8 GPa. For the Me 4 P salt, the metal-to-non-metal transition temperature reaches a minimum at 0.83 GPa and turns to increase with increasing pressure up to 8 GPa, showing no metallic state stable at low temperature

We have investigated the resistivity of an organic Mott insulator, β'-(BEDT-TTF) 2 AuCl 2 , under extremely high pressures of up to 9.9 GPa, using the cubic anvil press, motivated by the fact that ...

An atomic-scale graded structure has been formed previously in a Bi70Sb30 (at. %) alloy that is miscible in all proportions, by sedimentation of substitutional solute atoms under an ultrastrong gravitational field up to 1×106 G at 220–240 °C [T. Mashimo, T. Ikeda, and I. Minato, J. Appl. Phys. 90, 741 (2001)]. In this study, additional megagravity field experiments were performed on the Bi70Sb30 alloy and pure Bi at different temperatures below their melting points, to investigate the change in crystalline state under the ultrastrong gravitational field. For the Bi70Sb30 alloy ultracentrifuged at 191–205 °C, no change in composition was observed, and the grain sizes of the crystals decreased from several millimeters to tens of micrometers, while no distinct change in grain size was observed for the pure Bi ultracentrifuged under the same experimental conditions. The Bi70Sb30 alloy ultracentrifuged at 220–240 °C consisted of two regions with different morphologies–fine-grained crystals with grain sizes in ...

The electrical resistivity ρ(T) of Y1−xUxPd3 (x = 0,0.05 and 0.2) and the lattice constants for x = 0 have been measured at high pressure. It is found that the cubic Cu3Au structure is stable up to 12 GPa at room temperature. The Kondo temperature TK was extracted from the ρ(T) curve and it was found that it increases with pressure. A logarithmic temperature dependence characteristic of the Kondo effect was found for x = 0.2 in the temperature range above about 0.5TK. Fermi liquid behaviour in ρ(T) for x = 0.05, i.e., , is observed and its stability at high pressure is discussed. The pressure dependence of the Kondo temperature TK is discussed using the Gruneisen parameters at TK, ΓK. It appears that the values of ΓK are the same for these two compounds (x = 0.05 and 0.2): ΓK = 12. The T-linear behaviour in ρ(T) for x = 0.2, which is characteristic behaviour for non-Fermi liquids, is collapsed by an application of pressure and typical Fermi liquid quadratic temperature dependence recovers at high pressure. From the result for x = 0.2, the power n of the temperature in is determined as 1.0 at ambient pressure and 1.9 at 5.8 GPa. It is pointed out that the hybridization effect due to the application of pressure gives rise to a crossover from a non-Fermi liquid state to Fermi liquid state. But the crossover temperature Tcr shows a pressure dependence different from that predicted by the two-channel Kondo model.

An organic Mott insulator, β'-(BEDT-TTF) 2 ICl 2 , is metallized by application of extremely high pressure up to 9.0GPa. When the metallic state is stabilized, superconductivity with the highest transition-temperature (T c ) among organic systems appears. The maximum T c that we observed was 14.2K(onset) at 8.2GPa. A magnetic-field effect on this superconductivity and normal-state properties are discussed in terms of comparison with other organic superconductors.

An atomic-scale graded structure had been formed in an all-proportion miscible alloy in bismuth (Bi)-antimony (Sb) (70:30 in mol%) system by the sedimentation of substitutional solute atoms under a strong gravitational field of 1 million G level in maximum acceleration at 220–240□ (Mashimo et al. 1997, Mashimo et al. 2001). The large and long crystals whose grain sizes were several mm long and several hundreds of μm wide were oriented along the direction of gravity in the high gravity region larger than about 0.7×106 G, while those of the small crystals in the low gravity region smaller than it were several 10 Pin. It was found that the large strain existed in the large crystals by back-reflection Laue method. It was found that the c axis of hexagonal structure of a large crystal was roughly parallel to the direction of gravity by Transmission Electron Microscopy (TEM) observation.

Temperature dependence of the Hall coefficient and the resistivity in Tl2Ba2CaCu2O y (TL-2212), Tl2Ba2Ca2Cu3O y (Tl-2223) and Cu0.7C0.3Ba2Ca3Cu4O y (Cu-1234) have been measured under high pressure up to 6 GPa. The values of the intrinsic T c enhancement not related to charge transfer by applied pressure were estimated to be ∼0.8K/GPa for the Tl system and ∼1.1K/GPa for Cu-1234.

An ultracentrifuge apparatus, which can generate an ultra-strong gravitational field even >1 000 000 (1 million) G (1 G=9.8 m/s2) over a wide temperature range up to >500 °C with high stability control, was developed for new materials science research. The system consists of an air turbine motor with ceramic ball bearings and dumper section, a sample rotor with an outer diameter of up to 160 mm, a vacuum chamber, and a heating system. The nonbored rotor and the double-structural dumper bushing are used to raise the maximum rotational speed and to improve the stability. The samples can be heated by radiant heat. A maximum rotational speed of 190 000 rpm using a 70 mm diam rotor was recorded despite a short time where the maximum gravitational field was >1 2000 000 G. Long and high-temperature ultracentrifuge experiments using 70 and 80 mm diam rotors made of titanium alloy with rotational speeds of up to 170 000 rpm even at temperatures of over 200 °C for 100 h with ripples of

The Ni–Cr–Al Russian alloy was prepared. Its magnetic and mechanical properties were better than those of MP35N alloy. We fabricated the a piston–cylinder-type hybrid high-pressure cell using the Ni–Cr–Al alloy. It has been found that the maximum working pressure can be repeatedly raised to 3.5 GPa at T = 2 K without any difficulties.

We measured temperature dependence of in-plane and inter-plane thermopower S ab and S c of single crystalline Ca 3 Ru 2 O 7 . The thermopower measurements were carried out by the low-frequency (33 mHz) AC heating method. Large anisotropy between S ab and S c was observed, and its ratio ( S ab / S c ) is about 15 at 300 K. The sign of S ab changes from positive to negative value at the structural transition temperature of 48 K, indicating a reconstruction of Fermi surface. The behavior of S ab can be explained by the results of the electrical resistivity and Hall coefficient. On the other hand, S c shows a rather complex behavior.

Electrical resistivity measurements of the insulating Ba 1− x K x BiO 3 ( x = 0, 0.15) under high pressure up to 8 GPa have been performed in order to search for the pressure-induced superconductivity, using a cubic-anvil pressure system. A polycrystal of BaBiO 3 has been prepared by the solid-state reaction method. A single crystal of Ba 0.85 K 0.15 BiO 3 has been synthesized by the electrochemical method from molten salts. The electrical resistivity of both compounds slightly decreases with increasing pressure. However, the temperature dependence still remains semiconductive and no superconductivity is observed.

Pressure-induced superconductivity in a spin-ladder cuprate Sr 2 Ca 12 Cu 24 O 41 was investigated on the microscopic level by using 63 Cu nuclear magnetic resonance (NMR) under pressure of 3.5 GPa. We observed both spin and superconducting gaps in separated temperature regions. We found that the superconducting state possesses a full gap and is quite stable even at high fields close to the conventional Pauli limit.

Physical properties of an organic conductor, β'-(BEDT-TTF) 2 IBrCl, were characterized under ambient and extremely high pressures. Semiconducting behavior with activation energy, E a =0.11eV, and antiferromagnetic transition with T N =19.5K were uncovered in the present work. In addition, we have found that this salt showed a sign of superconductivity at 8.0GPa in common with the case of the β'-(BEDT-TTF) 2 ICl 2 , which is the highest-T c superconductor among organics.

The title reaction smoothly proceeds at room temperature to give α-hydroxy-γ-keto esters 3 in good yields, probably via a mechanism involving samarium enolates formed in situ from α-halo ketones.

Nuclear magnetic resonance (NMR) under pressure below 3 GPa was performed by using a single crystal of Sr 2 Ca 12 Cu 24 O 41 to investigate the spin dynamics on the critical regime neighboring the superconducting phase. The temperature dependence of the relaxation rate 1/ T 1 deviates from an activated type below 50 K and exhibits power law behavior. On the other hand, 1/ T 1 increases as pressure is increased at low temperatures. These features are intrinsic to this system and reflect some fluctuations originating from holes.

Electrical resistivity measurements have been made on a good qualified single crystalline magnetite (Fe3O4) at temperatures from 300 down to 3.0 K under pressure up to 10 GPa. A steep change in resistivity at the Verwey transition temperature has been observed at pressure below 6.5 GPa, which shows a quite distinct result reported in prior work. Moreover, the Verwey transition temperature has been found to decrease nonlinearly with increasing pressure and it disappears at around 8 GPa. Above 8 GPa magnetite exhibits metallic behavior. The residual-resistivity ratio of the metallic state is observed to be more than 350. This finding of a metallic ground state in magnetite provides insight into the understanding of the Verwey transition in magnetite.

The title reaction smoothly proceeds at room temperature to give α-hydroxy-γ-keto esters 3 in good yields, probably via a mechanism involving samarium enolates formed in situ from α-halo ketones.

We investigated the effect of pressure on the magnetic properties of a single crystal of the bilayer manganese oxide (Pr0.6La0.4)1.2Sr1.8Mn2O7 by means of DC magnetization measurements under pressure. The ferromagnetic transition, which is accompanied by a metal–insulator transition, is highly sensitive to pressure. The pressure causes a structural variation, which affects the magnetic properties. We discuss the pressure dependence of the 3d electronic state of the Mn ion in this system.

We have succeeded in growing single crystals of ${\mathrm{Ca}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$ using a floating-zone method. The temperature dependence of the electrical resistivity establishes that ${\mathrm{Ca}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$ develops a quasi-two-dimensional metallic ground state below $30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, from which the observed quantum oscillation derives. The temperature dependence of specific heat reveals the electronic specific-heat coefficient $\ensuremath{\gamma}$ to be as small as $1.7\phantom{\rule{0.3em}{0ex}}\mathrm{mJ}∕\mathrm{Ru}\phantom{\rule{0.3em}{0ex}}\mathrm{mol}\phantom{\rule{0.3em}{0ex}}{\mathrm{K}}^{2}$. A qualitative difference exists between the field dependences of ${\ensuremath{\rho}}_{ab}$ and ${\ensuremath{\rho}}_{c}$. The field dependence of the resistivity at the metamagnetic transition around $6\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ can be explained from the tunneling magnetoresistance.

We present a study on magnetization in a single crystal of magnetite under uniaxial strain applied along the [1 1 0] direction using a SQUID magnetometer. An abrupt change in magnetization was observed at the metal–insulator transition temperature T V (Verwey transition temperature). We observed that T V increased with increasing uniaxial compression. The pressure coefficient d T V /d P was obtained to be 1.6 ±0.1 K/kbar. The result obtained is different from that obtained under hydrostatic pressure, which showed that T V decreases with increasing pressure.

We present the experimental results of DC magnetization measurements on the bilayer manganese oxide (Pr 0.6 La 0.4 ) 1.2 Sr 1.8 Mn 2 O 7 under pressure. The data were taken to elucidate the magnetic properties of the field-induced ferromagnetic phase and to establish the magnetic phase diagram on the fields applied along the c -axis. The results indicated that the phase is sensitive to the applied pressure. The isothermal remanent magnetization M IRM ( t ) as a function of time t in the ferromagnetic phase suggests the existence of the relaxation process and its pressure effect. It seems that the effect of pressure leads to a variation of the transition probability between the ferromagnetic metal and paramagnetic insulating state.

We have measured the thermal expansion coefficient α L ( T ) of SmS under pressure up to 21.6 kbar. In the golden phase, an excitation gap Δ inferred from α L ( T ) decreases with increasing pressure. When the system enters the metallic phase from the golden phase, Δ collapses suddenly to zero, and simultaneously, a huge sharp anomaly appears in the α L ( T ) curve, reflecting the magnetic phase transition.

The electrical resistivity of the filled skutterudite compound CeRu4Sb12 was measured in the temperature range 2– 300 K and under hydrostatic pressures up to 8 GPa . Above 6 GPa , we observed metal-semiconductor transition in CeRu4Sb12 at low temperature and a energy gap estimated from activation law was enhanced with increasing pressure at a rate of 12.2 K / GPa . Semiconductive behavior of CeRu4Sb12 under high pressure may have the same origin as other Ce-based skutterudite compounds which show semiconducting behavior.

CeRh2Si2 shows two successive antiferromagnetic phase transitions at ambient pressure (T N 1 =36 K and T N 2 =27 K ). Application of pressure suppresses TN1 to 0 K at P c ∼1 GPa . We study the magnetism of the single-crystalline sample of CeRh2Si2 by muon spin rotation/relaxation (μSR) method up to 0.45 GPa . Below TN2, we observed both the spontaneous muon spin precession and the fast muon spin relaxation under zero magnetic field. Although the transition temperature decreases with increasing the pressure, the precession frequency, which is proportional to the saturated sublattice magnetic moment, is nearly independent of the pressure.

Nuclear magnetic resonance under high pressure (3.0 GPa at room temperatures) were performed in a spin ladder system, Sr 2 Ca 12 Cu 24 O 41 where the superconductivity is realized by applying pressure above 3 GPa at low temperatures. The relaxation rate 1/ T 1 on 63 Cu nuclei shows an activated behavior at high temperatures above 50 K although the system is metallic, and the value of the excitation gap is almost the same with that at ambient pressure. The fact implies breakdown of a scenario that pressure vanishes the spin gap and then superconductivity is induced.

The magnetic susceptibility and the electrical resistivity of single crystal CeGa are measured in magnetic fields up to 9 T and at pressures up to 7.0 kbar . Antiferromagnetic transition temperature T N =5.8 K decreases and fades out above 5 T with increasing magnetic fields along the c -axis at various pressures up to 4.9 kbar . On the other hand, the T N decreases slightly with increasing magnetic fields applied along the a -axis up to 9 T and at various pressures up to 7.0 kbar . These results can be explained on the basis of magnetocrystalline anisotropy effects.

Dept. of Crystalline Materials Science, Nagoya University, Nagoya 464-8603 Dept. of Applied Physics, Nagoya University, Nagoya 464-8603 SPring-8/JASRI, 1-1-1 Koto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 Faculty of Science and Technology, Science University of Tokyo, Chiba 278-8510 ISSP, University of Tokyo, Kashiwa 277-8581 Dept. of Physics, Saitama University, Saitama 338-8570 SPring-8/JAERI, 1-1-1 Koto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198

Ternary compound Ce3PbC has a simple face-centered cubic CaTiO3-type structure. We found that Ce3PbC undergoes a transition to an antiferromagnetic state at T N =8.4 K and shows an another transition at T t =5.8 K . Magnetization process exhibits multi-step metamagnetic transitions at T=1.5 K . The observation of inelastic neutron experiments suggest that the crystalline electric field (CEF) ground state can be consider to be a doublet. This results imply that the Ce sites are influenced by tetragonal CEF interaction, even though the crystal structure is cubic. We expect that such CEF configuration plays an important role in the behavior of multi-step metamagnetic transitions.

Temperature-dependent electrical resistivity measurements have been performed on single-crystalline YbInCu4 under hydrostatic pressures to P=3.3 GPa. Its valence phase-transition temperature TV decreases linearly at a rate of −2.0 K/GPa with increasing pressure to 1.0 GPa, as found previously. Above 1.0 GPA, however, TV decreases more gradually and is depressed to below 1.5 K at 2.5 GPa. Experimental results suggest that the hybridization between 4f- and conduction-band electrons is reduced with increasing pressure and that the semi-metallic state (T>TV) is favored over the metallic state (T

The magnetic properties of Ce 2 Sc 3 Ge 4 single crystalline sample were investigated. The magnetization, magnetic susceptibility and electrical resistivity were measured. We found that Ce 2 Sc 3 Ge 4 was an antiferromagnetic Kondo compound with T N = 4.6 K.

Resistivity of the Heusler-type paramagnetic intermetallic compound PrInAg 2 is measured by the SQUID technique, down to 0.18 mK. The sample is cooled by an adiabatic Cu nuclear demagnetization refrigerator. No evidence of any phase transition is observed at any temperature. However, a ‘+’ T 1/2 dependence of resistivity is observed below 100 mK.

The P–T phase diagram and transport properties of a layered organic superconductor, � -(BEDTTTF)4Hg2:89Br8, which can be viewed as a nealy half-filled band system, are reported. Through careful resistivity measurements under pressures of up to 4.5 GPa, we uncovered anomalous pressure dependence of Tc of this superconductor, including a peak structure at approximatly 0.7 GPa and a minimum structure at higher pressure. The normal-state resistivity showed T-linear behavior at low pressures and this behavior gradually transformed into T-squared behavior with increasing pressure. The pressure, Pc � 2 GPa, at which Tc has a turning value, corresponds to the onset of the T-squared behavior.

We measured the thermal expansion and heat capacity of the mixed-valence compound SmS that shows an insulator to metal phase transition under pressure. We report a convincing evidence for the existence of not only an electronic specific heat coefficient gamma but also a Schottky like gap A in the "metal" phase, generally referred to as golden phase. As the pressure increases, gamma steeply increases while A monotonically decreases. Nevertheless, the product gamma Delta/N is kept constant, where N denotes the number of Sm3+ ion. We argue that a novel bound state is formed in golden phase.

We have measured the Moessbauer spectra of magnetite (Fe{sub 3}O{sub 4}) under a pressure of up to 18 GPa at room temperature using nonenriched high-quality samples. An analysis of the observed Moessbauer spectra confirms that Fe{sub 3}O{sub 4} does not undergo a magnetic or crystalline structural transition up to 18 GPa at room temperature. In the pressure dependences of the refined hyperfine interaction parameters, however, small but distinct anomalies are found at 7.0 GPa in the center shifts of two crystallographically nonequivalent Fe sites, which are caused by the discontinuous decrease of an oxygen internal coordinate in the cubic inverse spinel structure. We believe that the pressure-induced discontinuous change of the Fe-O bond length is related to the absence of a metal-insulator transition above 7.5 GPa.

The approximate d bands of antiferromagnetic α‐Mn are formulated, using Deegan’s prescription and the formulas of Slater and Koster, in consideration of the crystal and magnetic structures. The magnetic moments of 29 atoms are calculated by adopting reasonable coefficients of the effective exchange interaction. The obtained result is much the same as the experimental result.

Pressure effect on the spontaneous volume magnetostriction ω s of Fe-Ni and Fe-Pt Invar alloys is studied by measuring the pressure dependence of lattice constants usins X-rav diffraction technique. The pressure derivative of ω s and the magnetic contribution to the compressibility in Fe-Ni Invar alloy near 0 K are found to be largely different from those in Fe-Pt Invar alloy. The differences are interpreted phenomenologically in terms of the pressure dependence of T c and M 0 and suggested to relate with the stability of magnetic moment at low temperature.