127 research outputs found
New Approach for Measuring at Future -Factories
It is suggested that the measurements of hadronic invariant mass ()
distributons in the inclusive decays can be
useful in extracting the CKM matrix element . We investigated
hadronic invariant mass distributions within the various theoretical models of
HQET, FAC and chiral lagrangian as well as ACCMM model. It is also emphasized
that the distribution even at the region in the inclusive
are effetive in selecting the events, experimentally viable at
the future asymmetric factories, with better theoretical understandings.Comment: 11 pages not including 1 figur
Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic Quark Model
We investigate the and mesons in the relativistic quark model by
applying the variational method with the Gaussian wave function. We calculate
the Fermi momentum parameter , and obtain
GeV, which is almost independent of the input parameters, , ,
and . We then calculate the ratio /, and obtain the
result which is larger, by the factor of about 1.3, than
given by the naive nonrelativistic analogy. This result is in a good agreement
with the recent Lattice calculations. We also calculate the ratio
/. In these calculations the wave function at
origin is essential. We also determine by comparing the
theoretical prediction of the ACCMM model with the lepton energy spectrum of from the recent ARGUS analysis, and find that
GeV, when we use GeV. However, this
experimentally determined value of is strongly dependent on the value
of input parameter .Comment: 15 pages (Latex) (uses epsfig.sty, 1 figure appended as a uuencoded
compressed ps-file
Dependence of on Fermi momentum in ACCMM model
The Gaussian width of Fermi momentum, , is the most important
parameter of the ACCMM model, and its value is essential in the determination
of because the experimental analysis is allowed only at the
end-point region of inclusive semileptonic -decay spectrum. We extract the
value of as a function of . We also calculate the
parameter in the relativistic quark model using the variational
method, and obtain GeV which is much larger than the commonly
used value, GeV, in experimental analyses. When we use GeV instead of 0.3 GeV, the value of from ACCMM model is
increased by a factor 1.81, and can give a good agreement with Isgur {\it et
al.} model.Comment: 1. Section 2 has been revised by considering the fact that in the
real experimental situation the only measured quantity is the number of
events in the high region compared to the total semi- leptonic event
number. 2. The article by C. Greub and D. Wyler (Phys. Lett. B295 (1992) 293)
has been included in references, which reports a similar conclusion for the
value of (=566 MeV), even though they used the different
approach. 3. This article will be published in Z. Phys. C (1995
Wide Contact Structures for Low-Noise Nanochannel Devices Based on a Carbon Nanotube Network
We have developed a wide contact structure for low-noise nanochannel devices based on a carbon nanotube (CNT) network. This low-noise CNT network-based device has a dumbbell-shaped channel, which has wide CNT/electrode contact regions and, in effect, reduces the contact noise. We also performed a systematic analysis of structured CNT networks and established an empirical formula that can explain the noise behavior of arbitrary-shaped CNT network-based devices including the effect of contact regions and CNT alignment. Interestingly, our analysis revealed that the noise amplitude of aligned CNT networks behaves quite differently compared with that of randomly oriented CNT networks. Our results should be an important guideline in designing low-noise nanoscale devices based on a CNT network for various applications such as a highly sensitive low-noise sensor
Epigenetic regulation of fetal bone development and placental transfer of nutrients: progress for osteoporosis
Osteoporosis is a common age-related disorder and causes acute and long-term disability and economic cost. Many factors influence the accumulation of bone minerals, including heredity, diet, physical activity, gender, endocrine functions, and risk factors such as alcohol, drug abuse, some pharmacological drugs or cigarette smoking. The pathology of bone development during intrauterine life is a factor for osteoporosis. Moreover, the placental transfer of nutrients plays an important role in the building of bones of fetuses. The importance of maternal calcium intake and vitamin D status are highlighted in this review. Various environmental factors including nutrition state or maternal stress may affect the epigenetic state of a number of genes during fetal development of bones. Histone modifications as histone hypomethylation, histone hypermethylation, hypoacetylation, etc. are involved in chromatin remodeling, known to contribute to the epigenetic landscape of chromosomes, and play roles in both fetal bone development and osteoporosis. This review will give an overview of epigenetic modulation of bone development and placental transfer of nutrients. In addition, the data from animal and human studies support the role of epigenetic modulation of calcium and vitamin D in the pathogenesis of osteoporosis. We review the evidence suggesting that various genes are involved in regulation of osteoclast formation and differentiation by osteoblasts and stem cells. Epigenetic changes in growth factors as well as cytokines play a rol in fetal bone development. On balance, the data suggest that there is a link between epigenetic changes in placental transfer of nutrients, including calcium and vitamin D, abnormal intrauterine bone development and pathogenesis of osteoporosis
Average Kinetic Energy of Heavy Quark in Semileptonic B Decay
Within the ACCMM model the average kinetic energy of heavy quark in a
heavy-light meson is calculated as , solely from the fact that the Gaussian momentum probability
distribution has been taken in the ACCMM model. Therefore, the Fermi momentum
parameter of the ACCMM model is not a truly free parameter, but is
closely related to the average kinetic energy of heavy quark, which is
theoretically calculable in principle. In this context, we determine
by comparing the theoretical prediction of the ACCMM model with the model
independent lepton energy spectrum of from the recent
CLEO analysis, and find that GeV. We also
calculate in the relativistic quark model by applying the quantum
mechanical variational method, and obtained GeV. We show
the correspondences between the relativistic quark model and the heavy quark
effective theory. We then clarify the importance of the value of in
the determination of .Comment: 23 pages(LaTeX), 2 Postscript figures, uses aps.st
Recommended from our members
Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF
M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
Effects of Once-Weekly Exenatide on Cardiovascular Outcomes in Type 2 Diabetes.
Abstract
BACKGROUND:
The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown.
METHODS:
We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy.
RESULTS:
In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups.
CONCLUSIONS:
Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo. (Funded by Amylin Pharmaceuticals; EXSCEL ClinicalTrials.gov number, NCT01144338 .)
An automated method for cell-free layer width determination in small arterioles
10.1088/0967-3334/32/3/N01Physiological Measurement323N1-N12PMEA
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