Tohoku University

About: Tohoku University is a education organization based out in Sendai, Japan. It is known for research contribution in the topics: Magnetization & Population. The organization has 72116 authors who have published 170791 publications receiving 3941714 citations. The organization is also known as: Tōhoku daigaku.

Chemosensitivity and Perception of Dyspnea in Patients with a History of Near-Fatal Asthma

Abstract: Background Many deaths from attacks of asthma may be preventable. However, the difficulty in preventing fatal attacks is that not all the pathophysiologic risk factors have been identified. Methods To examine whether dyspnea and chemosensitivity to hypoxia and hypercapnia are factors in fatal asthma attacks, we studied 11 patients with asthma who had had near-fatal attacks, 11 patients with asthma who had not had near-fatal attacks, and 16 normal subjects. Their respiratory responses to hypoxia and hypercapnia, determined by the standard rebreathing technique while the patients were in remission, were assessed in terms of the slopes of ventilation and airway occlusion pressure as a function of the percentage of arterial oxygen saturation and end-tidal carbon dioxide tension, respectively. The perception of dyspnea was scored on the Borg scale during breathing through inspiratory resistances ranging from 0 to 30.9 cm of water per liter per second. Results The mean (±SD) hypoxic ventilatory response (0.14 ±...

Direct measurement of stiffness of single actin filaments with and without tropomyosin by in vitro nanomanipulation.

Abstract: In order to explain the molecular mechanism of muscle contraction, it is crucial to know the distribution of the sarcomere compliance of active muscle. Here, we directly measure the stiffness of single actin filaments with and without tropomyosin, using a recently developed technique for nanomanipulation of single actin filaments with microneedles. The results show that the stiffness for 1-micron-long actin filaments with and without tropomyosin is 65.3 +/- 6.3 and 43.7 +/- 4.6 pN/nm, respectively. When the distribution of crossbridge forces along the actin filament is taken into account, the elongation of a 1-micron-long thin filament during development of isometric contraction is calculated to be approximately 0.23%. The time constant of force in response to a sudden length change is < 0.2 ms, indicating that the viscoelasticity is negligible in the millisecond time range. These results suggest that approximately 50% of the sarcomere compliance of active muscle is due to extensibility of the thin filaments.

Itokawa Dust Particles: A Direct Link Between S-Type Asteroids and Ordinary Chondrites

Abstract: The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.

Observation of two charged bottomoniumlike resonances in Υ(5S) decays.

Abstract: We report the observation of two narrow structures in the mass spectra of the pi(+/-) Y(nS) (n = 1, 2, 3) and pi(+/-) h(b)(mP) (m = 1, 2) pairs that are produced in association with a single charged pion in Y(5S) decays The measured masses and widths of the two structures averaged over the five final states are M-1 = (10 6072 +/- 20) MeV/c(2), Gamma(1) =(184 +/- 24) MeV, and M-2 = (10 6522 +/- 15) MeV/c(2), Gamma(2) = (115 +/- 22) MeV The results are obtained with a 1214 fb(-1) data sample collected with the Belle detector in the vicinity of the Y(5S) resonance at the KEKB asymmetric-energy e(+)e(-) collider

Toward the standard population synthesis model of the x-ray background: evolution of x-ray luminosity and absorption functions of active galactic nuclei including compton-thick populations

Abstract: We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5--2 keV) and/or hard ($>2$ keV) band. We utilize a maximum likelihood method to reproduce the count-rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broad band spectra of AGNs including reflection components from tori based on the luminosity and redshift dependent unified scheme. We find that the shape of the XLF at $z \sim 1-3$ is significantly different from that in the local universe, for which the luminosity dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-Ray Background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be $\approx$0.5--1.6 to produce the 20--50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.