628 research outputs found
Avoiding the uncertainty from correlation between |Delta m_{31}^2| and CP phase delta in nu_mu --> nu_mu long baseline experiments
We introduce a new index I_{Delta m_{31}^2} to find where is the better setup
of the baseline length and energy to avoid as well as possible the uncertainty
from the correlation between Delta m_{31}^2 and cos(delta) in nu_mu --> nu_mu
long baseline experiments.Comment: 6 pages, 9 figure
Resonant Spin-Flavor Conversion of Supernova Neutrinos: Dependence on Electron Mole Fraction
Detailed dependence of resonant spin-flavor (RSF) conversion of supernova
neutrinos on electron mole fraction Ye is investigated. Supernova explosion
forms a hot-bubble and neutrino-driven wind region of which electron mole
fraction exceeds 0.5 in several seconds after the core collapse. When a higher
resonance of the RSF conversion is located in the innermost region, flavor
change of the neutrinos strongly depends on the sign of 1-2Ye. At an adiabatic
high RSF resonance the flavor conversion of bar{nu}_e -> nu_{mu,tau} occurs in
Ye 0.5 and inverted mass hierarchy.
In other cases of Ye values and mass hierarchies, the conversion of nu_e ->
bar{nu}_{mu,tau} occurs. The final bar{nu}_e spectrum is evaluated in the cases
of Ye 0.5 taking account of the RSF conversion. Based on the
obtained result, time variation of the event number ratios of low bar{nu}_e
energy to high bar{nu}_e energy is discussed. In normal mass hierarchy, an
enhancement of the event ratio should be seen in the period when the electron
fraction in the innermost region exceeds 0.5. In inverted mass hierarchy, on
the other hand, a dip of the event ratio should be observed. Therefore, the
time variation of the event number ratio is useful to investigate the effect of
the RSF conversion.Comment: 16 pages, 33 figures, accepted for publication in Physical Review
Measuring the Leptonic CP Phase in Oscillations
In oscillations, we find that the effect of the CP
phase becomes large in the region km. In this
region, the change of the probability in this channel reaches about 0.4 due to
the CP phase effect beyond our expectation in the case of large 1-3 mixing
angle. Furthermore, the CP phase effect have almost same sign over the region
GeV so that one may find the signal of CP violation by measuring the
total rate only. As an example, we use an experimental setup and demonstrate
that the allowed region is limited to one by combined analysis of and
events although there remain three allowed regions by the analysis
of events alone.Comment: 7 pages, 8 figures, version to appear in PL
A New Insight into Electron Acceleration Properties from Theoretical Modeling of Double-Peaked Radio Light Curves in Core-Collapse Supernovae
It is recognized that some core-collapse supernovae (SNe) show a
double-peaked radio light curve within a few years since the explosion. A shell
of circumstellar medium (CSM) detached from the SN progenitor has been
considered to play a viable role in characterizing such a re-brightening of
radio emission. Here, we propose another mechanism that can give rise to the
double-peaked radio light curve in core-collapse SNe. The key ingredient in the
present work is to expand the model for the evolution of the synchrotron
spectral energy distribution (SED) to a generic form, including fast and slow
cooling regimes, as guided by the widely-accepted modeling scheme of gamma-ray
burst afterglows. We show that even without introducing an additional CSM
shell, the radio light curve would show a double-peaked morphology when the
system becomes optically thin to synchrotron self-absorption at the
observational frequency during the fast cooling regime. We can observe this
double-peaked feature if the transition from fast cooling to slow cooling
regime occurs during the typical observational timescale of SNe. This situation
is realized when the minimum Lorentz factor of injected electrons is initially
large enough for the non-thermal electrons' SED to be discrete from the thermal
distribution. We propose SN 2007bg as a special case of double-peaked radio SNe
that can be explained by the presented scenario. Our model can serve as a
potential diagnostic for electron acceleration properties in SNe.Comment: 16 pages, 8 figures, submitted to Ap
Risk factor analysis of thoracic endovascular repair using the Matsui-Kitamura stent graft for acute aortic emergencies in the descending thoracic aorta
ObjectiveIn recent years, thoracic endovascular aneurysm repair (TEVAR) has been attempted for acute aortic emergencies (AAEs). However, the risk factors for achieving good results have not been identified. Besides focusing on Acute Physiology and Chronic Health Evaluation (APACHE) II score as a general indicator of patient condition, we analyzed both preoperative factors and intraoperative/postoperative factors. The purpose of this study was to identify those factors affecting the results of TEVAR using our Matsui-Kitamura stent graft (MKSG) for AAEs involving descending thoracic aortic aneurysm.MethodsBetween July 2000 and June 2008, a total of 32 patients (23 men, 9 women) with AAEs underwent endovascular repair. AAE was a result of aortic aneurysm rupture in 16 cases, rupture of penetrating atherosclerotic ulcer in 2 cases, traumatic aortic injury in 9 cases, complicated type B dissection in 4 cases, and aortic infiltration of sarcoma in 1 case. Low blood pressure in 6 patients, acute renal failure in 7 patients, anemia due to bleeding in 12 patients were found at the time of operation. Urgent TEVAR using the MKSG was performed. Perioperative and long-term results for these patients were investigated.ResultsThe delivery and technical success rate for TEVAR using the MKSG, was 100%. Perioperative mortality was 12.5%, and 5-year survival rate was 71%. In both univariate and multivariate analysis, the APACHE II score clarified a risk factor. Among the various elements of an APACHE II score, age, hematocrit, and total score were identified as significant factors. The mean of an APACHE II score was 9.5. Patients with an APACHE II score ≥10 showed significantly lower 5-year survival rates than patients with an APACHE II score ≤9.ConclusionsGood results were obtained using TEVAR to treat AAEs with MKSGs, both perioperatively and during medium-term follow-up. Evaluation of risk factors for TEVAR of AAEs showed the utility of APACHE II score (particularly age, hematocrit, and total score) with a score ≥10 indicating high risk
非小細胞肺がんにおけるS100A4とE-カドヘリン依存性細胞接着関連因子の発現と予後との関連性
取得学位 : 博士(医学), 学位授与番号 : 医博甲第1423号,学位授与年月日:平成12年3月31日,学位授与年:200
Supernova Neutrino Nucleosynthesis of Light Elements with Neutrino Oscillations
Light element synthesis in supernovae through neutrino-nucleus interactions, i.e., the ν-process, is affected by neutrino oscillations in the supernova environment. There is a resonance of 13-mixing in the O/C layer, which increases the rates of charged-current ν-process reactions in the outer He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and 1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing resonance, compared to those without neutrino oscillations. In the case of an inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the increase in the 7Li and 11B yields is much smaller. Observations of the 7Li/11B ratio in stars showing signs of supernova enrichment could thus provide a unique test of neutrino oscillations and constrain their parameters and the mass hierarchy
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