Osaka Institute of Technology

About: Osaka Institute of Technology is a education organization based out in Osaka, Japan. It is known for research contribution in the topics: Thin film & Laser. The organization has 2457 authors who have published 4247 publications receiving 49872 citations. The organization is also known as: Ōsaka kōgyō daigaku.

PWM technique for power MOSFET inverter

Abstract: A sinusoidal PWM (pulsewidth-modulated) inverter suitable for use with power MOSFETs is described. The output waveforms in the proposed PWM inverter are investigated both theoretically and experimentally. A modulating signal for the three-phase PWM inverter is obtained by adding the harmonic components of integer multiples of three to the three-phase sine waves. By using the proposed modulating signal, the amplitude of the fundamental component is increased about 15% more than that of a conventional sine-wave inverter and the commutation number of the inverter is decreased to two-thirds of a conventional one. >

Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo’s third observing run

Abstract: We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO’s and Advanced Virgo’s third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density Ω GW ≤ 5.8 × 10 − 9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity coming from the band 20–76.6 Hz; Ω GW ( f ) ≤ 3.4 × 10 − 9 at 25 Hz for a power-law GWB with a spectral index of 2 / 3 (consistent with expectations for compact binary coalescences), in the band 20–90.6 Hz; and Ω GW ( f ) ≤ 3.9 × 10 − 10 at 25 Hz for a spectral index of 3, in the band 20–291.6 Hz. These upper limits improve over our previous results by a factor of 6.0 for a flat GWB, 8.8 for a spectral index of 2 / 3 , and 13.1 for a spectral index of 3. We also search for a GWB arising from scalar and vector modes, which are predicted by alternative theories of gravity; we do not find evidence of these, and place upper limits on the strength of GWBs with these polarizations. We demonstrate that there is no evidence of correlated noise of magnetic origin by performing a Bayesian analysis that allows for the presence of both a GWB and an effective magnetic background arising from geophysical Schumann resonances. We compare our upper limits to a fiducial model for the GWB from the merger of compact binaries, updating the model to use the most recent data-driven population inference from the systems detected during O3a. Finally, we combine our results with observations of individual mergers and show that, at design sensitivity, this joint approach may yield stronger constraints on the merger rate of binary black holes at z ≳ 2 than can be achieved with individually resolved mergers alone.

Mosaic organization and heterogeneity in frequency of allelic recombination of the Plasmodium vivax merozoite surface protein-1 locus

Abstract: The organization and allelic recombination of the merozoite surface protein-1 gene of Plasmodium vivax (PvMsp-1), the most widely prevalent human malaria parasite, were evaluated in complete nucleotide sequences of 40 isolates from various geographic areas. Alignment of 31 distinct alleles revealed the mosaic organization of PvMsp-1, consisting of seven interallele conserved blocks flanked by six variable blocks. The variable blocks showed extensive variation in repeats and nonrepeat unique sequences. Numerous recombination sites were distributed throughout PvMsp-1, in both conserved blocks and variable block unique sequences, and the distribution was not uniform. Heterozygosity of PvMsp-1 alleles was higher in Asia (0.953 +/- 0.009) than in Brazil (0.813 +/- 0.047). No identical alleles were shared between Asia and Brazil, whereas all but one variable block nonrepeat sequence found in Brazil occurred in Asia. These observations suggest that P. vivax populations in Asia are ancestral to Brazilian populations, and that PvMsp-1 has heterogeneity in frequency of allelic recombination events. Recurrent origins of new PvMsp-1 alleles by repeated recombination events were supported by a rapid decline in linkage disequilibrium between pairs of synonymous sites with increasing nucleotide distance, with little linkage disequilibrium at a distance of over 3 kb in a P. vivax population from Thailand, evidence for an effectively high recombination rate of the parasite. Meanwhile, highly reduced nucleotide diversity was noted in a region encoding the 19-kDa C-terminal epidermal growth factor-like domain of merozoite surface protein-1, a vaccine candidate.

Hydrogen-mediated epitaxy of Ag on Si(111) as studied by low-energy ion scattering.

Abstract: We have investigated the effect of the saturation of surface dangling bonds of Si(111) surfaces with atomic hydrogen upon Ag thin-film growth. By using time-of-flight-type low-energy ion scattering-recoil analysis techniques, we find that the growth mode of Ag thin films is drastically changed by the hydrogen termination of Si(111)-7\ifmmode\times\else\texttimes\fi{}7 surfaces and that the epitaxial growth of A-type Ag(111) films is promoted by the hydrogen atoms residing at the film/substrate interface.