117 research outputs found
Crossovers induced by discrete-time quantum walks
We consider crossovers with respect to the weak convergence theorems from a
discrete-time quantum walk (DTQW). We show that a continuous-time quantum walk
(CTQW) and discrete- and continuous-time random walks can be expressed as DTQWs
in some limit. At first we generalize our previous study [Phys. Rev. A
\textbf{81}, 062129 (2010)] on the DTQW with position measurements. We show
that the position measurements per each step with probability can be evaluated, where is the final time and . We
also give a corresponding continuous-time case. As a consequence, crossovers
from the diffusive spreading (random walk) to the ballistic spreading (quantum
walk) can be seen as the parameter shifts from 0 to 1 in both discrete-
and continuous-time cases of the weak convergence theorems. Secondly, we
introduce a new class of the DTQW, in which the absolute value of the diagonal
parts of the quantum coin is proportional to a power of the inverse of the
final time . This is called a final-time-dependent DTQW (FTD-DTQW). The CTQW
is obtained in a limit of the FTD-DTQW. We also obtain the weak convergence
theorem for the FTD-DTQW which shows a variety of spreading properties.
Finally, we consider the FTD-DTQW with periodic position measurements. This
weak convergence theorem gives a phase diagram which maps sufficiently
long-time behaviors of the discrete- and continuous-time quantum and random
walks.Comment: 14 pages, 1 figur
Emergence of Randomness and Arrow of Time in Quantum Walks
Quantum walks are powerful tools not only to construct the quantum speedup
algorithms but also to describe specific models in physical processes.
Furthermore, the discrete time quantum walk has been experimentally realized in
various setups. We apply the concept of the quantum walk to the problems in
quantum foundations. We show that randomness and the arrow of time in the
quantum walk gradually emerge by periodic projective measurements from the
mathematically obtained limit distribution under the time scale transformation.Comment: 6 pages, 3 figure
Secretory Phospholipases A2 Induce Neurite Outgrowth in PC12 Cells through Lysophosphatidylcholine Generation and Activation of G2A Receptor
We previously demonstrated that secretory phospholipase A2 (sPLA2) and lysophosphatidylcholine (LPC) exhibit neurotrophin-like neuritogenic activity in the rat pheochromocytoma cell line PC12. In this study, we further analyzed the mechanism whereby sPLA2 displays neurite-inducing activity. Exogenously added mammalian group X sPLA2 (sPLA2-X), but not group IB and IIA sPLA2s, induced neuritogenesis, which correlated with the ability of sPLA2-X to liberate LPC into the culture media. In accordance, blocking the effect of LPC by supplementation of bovine serum albumin or phospholipase B attenuated neuritogenesis by sPLA2 or LPC. Overproduction or suppression of G2A, a G-protein-coupled receptor involved in LPC signaling, resulted in the enhancement or reduction of neuritogenesis induced by sPLA2 treatment. These results indicate that the neuritogenic effect of sPLA2 is mediated by generation of LPC and subsequent activation of G2A
Rapid changes in plaque composition and morphology after intensive lipid lowering therapy: study with serial coronary CT angiography.
Although intensive lipid lowering by statins can enhance plaque stability, few data exist regarding how early statins change plaque composition and morphology in clinical setting. Therefore, to examine early changes in plaque composition and morphology by intensive lipid lowering with statins, we evaluate coronary plaques from acute coronary syndrome (ACS) before and 3 weeks after lipid lowering by coronary CT angiography. We enrolled 110 patients with suspected ACS and underwent coronary CT. We defined plaque as unstable when CT number of plaque1.10. Rosuvastatin (5 mg/day) or atorvastatin (20 mg/day) were introduced to reduce low density lipoprotein cholesterol (LDL-C). Then, CT was again performed by the same condition 3 weeks after lipid lowering therapy. Total 10 patients (8 men, mean age 72.0 years), in whom informed consent regarding serial CT examination was obtained, were analyzed. Among them, 4 patients who denied to have intensive lipid lowering were served as controls. In remaining 6 patients, LDL-C reduced from 129.5±26.9 mg/dl to 68.5±11.1 mg/dl after statin treatment. Under these conditions, CT number of the targeted plaque significantly increased from 16.0±15.9 to 50.8±35.0 HU (p<0.05) and remodeling index decreased from 1.22±0.11 to 1.11±0.06 (p<0.05), although these values substantially unchanged in controls. These results demonstrate that MDCT-determined plaque composition as well as volume could be changed within 3 weeks after intensive lipid lowering. This may explain acute effects of statins in treatment of acute coronary syndrome
CIPRO 2.5: Ciona intestinalis Protein integrated database with large-scale omics data, bioinformatic analyses and curated annotation, with ability for user rating and comments
CIPRO database is an integrated protein database for a tunicate species Ciona intestinalis that belongs to the Urochordata. Although the CIPRO database deals with proteomic and transcriptomic data of a single species, the animal is considered unique in the evolutionary tree, representing a possible origin of the vertebrates and is a good model for understanding chordate evolution, including that of humans. Furthermore, C. intestinalis has been one of the favorites of developmental biologists; there exists a huge amount of accumulated knowledge on its development and morphology, in addition to the recent genome sequence and gene expression data. The CIPRO database is aimed at not only collecting published data, but also presenting unique information, including the unpublished transcriptomic and proteomic data and human curated annotation, for the use by researchers in broad research fields of biology and bioinformatics
SILVERRUSH. VII. Subaru/HSC Identifications of 42 Protocluster Candidates at z~6-7 with the Spectroscopic Redshifts up to z=6.574: Implications for Cosmic Reionization
We report fourteen and twenty-eight protocluster candidates at z=5.7 and 6.6
over 14 and 19 deg^2 areas, respectively, selected from 2,230 (259) Lya
emitters (LAEs) photometrically (spectroscopically) identified with
Subaru/Hyper Suprime-Cam (HSC) deep images (Keck, Subaru, and Magellan spectra
and the literature data). Six out of the 42 protocluster candidates include
1-12 spectroscopically confirmed LAEs at redshifts up to z=6.574. By the
comparisons with the cosmological Lya radiative transfer (RT) model reproducing
LAEs with the reionization effects, we find that more than a half of these
protocluster candidates are progenitors of the present-day clusters with a mass
of > 10^14 M_sun. We then investigate the correlation between LAE overdensity
delta and Lya rest-frame equivalent width EW_Lya^rest, because the cosmological
Lya RT model suggests that a slope of EW_Lya^rest-delta relation is steepened
towards the epoch of cosmic reionization (EoR), due to the existence of the
ionized bubbles around galaxy overdensities easing the escape of Lya emission
from the partly neutral intergalactic medium (IGM). The available HSC data
suggest that the slope of the EW_Lya^rest-delta correlation does not evolve
from the post-reionization epoch z=5.7 to the EoR z=6.6 beyond the moderately
large statistical errors. There is a possibility that we would detect the
evolution of the EW_Lya^rest - delta relation from z=5.7 to 7.3 by the upcoming
HSC observations providing large samples of LAEs at z=6.6-7.3
CIPRO 2.5: Ciona intestinalis Protein Database - a unique integrated repository of large-scale omics data, bioinformatic analyses, and curated annotation, with ability for user rating and comments
- …