87 research outputs found
Neutrino self-interaction and MSW effects on the supernova neutrino-process
We calculate the abundances of Li, B, Nb, Tc,
La, and Ta produced by neutrino induced reactions in a
core-collapse supernova explosion. We consider the modification by
self-interaction (-SI) near the neutrinosphere and the
Mikheyev-Smirnov-Wolfenstein effect in outer layers for time-dependent neutrino
energy spectra. Abundances of Li and heavy isotopes Nb, Tc
and La are reduced by a factor of 1.5-2.0 by the -SI. In contrast,
B is relatively insensitive to the -SI. We find that the abundance
ratio of heavy to light nucleus, La/B, is sensitive to the
neutrino mass hierarchy, and the normal mass hierarchy is more likely to be
consistent with the solar abundances
Minimal upstream open reading frame of Per2 mediates phase fitness of the circadian clock to day/night physiological body temperature rhythm
全身の体内リズムを調和させるRNA配列の発見 --体温の日内変化に合わせてしなやかに調和させる--. 京都大学プレスリリース. 2023-03-07.Body temperature in homeothermic animals does not remain constant but displays a regular circadian fluctuation within a physiological range (e.g., 35°C–38.5°C in mice), constituting a fundamental systemic signal to harmonize circadian clock-regulated physiology. Here, we find the minimal upstream open reading frame (uORF) encoded by the 5′ UTR of the mammalian core clock gene Per2 and reveal its role as a regulatory module for temperature-dependent circadian clock entrainment. A temperature shift within the physiological range does not affect transcription but instead increases translation of Per2 through its minimal uORF. Genetic ablation of the Per2 minimal uORF and inhibition of phosphoinositide-3-kinase, lying upstream of temperature-dependent Per2 protein synthesis, perturb the entrainment of cells to simulated body temperature cycles. At the organismal level, Per2 minimal uORF mutant skin shows delayed wound healing, indicating that uORF-mediated Per2 modulation is crucial for optimal tissue homeostasis. Combined with transcriptional regulation, Per2 minimal uORF-mediated translation may enhance the fitness of circadian physiology
Comprehensive Analyses of the Neutrino-Process in the Core-collapsing Supernova
We investigate the neutrino flavor change effects due to neutrino
self-interaction, shock wave propagation as well as matter effect on the
neutrino process of the core-collapsing supernova. For the hydrodynamics, we
use two models: a simple thermal bomb model and a specified hydrodynamic model
for SN1987A. As a pre-supernova model, we take an updated model adjusted to
explain the SN1987A employing recent development of the reaction
rates for nuclei near the stability line . As for the neutrino
luminosity, we adopt two different models: equivalent neutrino luminosity and
non-equivalent luminosity models. The latter is taken from the synthetic
analyses of the CCSN simulation data which involved quantitatively the results
obtained by various neutrino transport models. Relevant neutrino-induced
reaction rates are calculated by a shell model for light nuclei and a
quasi-particle random phase approximation model for heavy nuclei. For each
model, we present abundances of the light nuclei (Li, Be, B and
C) and heavy nuclei (Nb, Tc, La and Ta)
produced by the neutrino-process. The light nuclei abundances turn out to be
sensitive to the Mikheyev-Smirnov-Wolfenstein region around ONeMg region while
the heavy nuclei are mainly produced prior to the MSW region. Through the
detailed analyses of the numerical abundances, we find that neutrino
self-interaction becomes a key ingredient in addition to the MSW effect for
understanding the neutrino process and the relevant nuclear abundances.
However, the whole results are shown to depend on the adopted neutrino
luminosity scheme. Detailed evaluations of the nuclear abundances for the two
possible neutrino mass hierarchies are performed with the comparison to the
available meteorite analyses data. The normal mass hierarchy is shown to be
more compatible with the meteoritic data
In Vitro Assessment of Factors Affecting the Apparent Diffusion Coefficient of Jurkat Cells Using Bio-phantoms
It is well known that many tumor tissues show lower apparent diffusion coefficient (ADC) values, and that several factors are involved in the reduction of ADC values. The aim of this study was to clarify how much each factor contributes to decreases in ADC values. We investigate the roles of cell density, extracellular space, intracellular factors, apoptosis and necrosis in ADC values using bio-phantoms. The ADC values of bio-phantoms, in which Jurkat cells were encapsulated by gellan gum, were measured
by a 1.5-Tesla magnetic resonance imaging device with constant diffusion time of 30sec. Heating at 42℃ was used to induce apoptosis while heating at 48℃ was used to induce necrosis. Cell death after heating was evaluated by flow cytometric analysis and electron microscopy. The ADC values of bio-phantoms including non-heated cells decreased linearly with increases in cell density, and showed a steep decline when the distance between cells became less than 3μm. The analysis of ADC values of cells after destruction of cellular structures by sonication suggested that approximately two-thirds of the ADC values of cells originate from their cellular structures. The ADC values of bio-phantoms including necrotic cells increased while those including apoptotic cells decreased. This study quantitatively
clarified the role of the cellular factors and the extracellular space in determining the ADC values
produced by tumor cells. The intermediate diffusion time of 30msec might be optimal to distinguish
between apoptosis and necrosis
General characterization of Antarctic micrometeorites collected by the 39th Japanese Antarctic Research Expedition: Consortium studies of JARE AMMs (III)
From November 1998 to January 1999,the 39th Japanese Antarctic Research Expedition (JARE-39) undertook Japanese first large-scale collection of Antarctic micrometeorites (AMMs), with sizes larger than 10μm, at the Meteorite Ice Field around the Yamato Mountains in Antarctica (at three different locations, for a total of 24 collection sites). The number of collected AMMs larger than 40μm is estimated to be about 5000. Here we present the general characterization (i.e., micro-morphology and surface chemical composition using SEM/EDS) of ∿810 AMMs chosen from 5 of the 24 sites. Additionally, the mineral composition of 61 out of 810 AMMs was determined by Synchrotron X-ray radiation. Preliminary results on mineralogical and chemical compositions show similarities with that of previous studies, even though a pronounced alteration of some AMMs is noticed. A correlation is found between the Mg/Si ratio at the sample\u27s surfaces of unmelted AMMs and the age of snow/ice in which the AMMs are embedded
Plastid signalling under multiple conditions is accompanied by a common defect in RNA editing in plastids
Retrograde signalling from the plastid to the nucleus, also known as plastid signalling, plays a key role in coordinating nuclear gene expression with the functional state of plastids. Inhibitors that cause plastid dysfunction have been suggested to generate specific plastid signals related to their modes of action. However, the molecules involved in plastid signalling remain to be identified. Genetic studies indicate that the plastid-localized pentatricopeptide repeat protein GUN1 mediates signalling under several plastid signalling-related conditions. To elucidate further the nature of plastid signals, investigations were carried out to determine whether different plastid signal-inducing treatments had similar effects on plastids and on nuclear gene expression. It is demonstrated that norflurazon and lincomycin treatments and the plastid protein import2-2 (ppi2-2) mutation, which causes a defect in plastid protein import, all resulted in similar changes at the gene expression level. Furthermore, it was observed that these three treatments resulted in defective RNA editing in plastids. This defect in RNA editing was not a secondary effect of down-regulation of pentatricopeptide repeat protein gene expression in the nucleus. The results indicate that these three treatments, which are known to induce plastid signals, affect RNA editing in plastids, suggesting an unprecedented link between plastid signalling and RNA editing
A rare case of concomitant huge exophytic gastrointestinal stromal tumor of the stomach and Kasabach-Merritt phenomenon
<p>Abstract</p> <p>Background</p> <p>We report an extremely rare case of concomitant huge exophytic GIST of the stomach and Kasabach-Merritt phenomenon (KMP).</p> <p>Case presentation</p> <p>The patient was a 67-year-old man experiencing abdominal distension since September 2006. A physical examination revealed a 25 × 30 cm hard mass that was palpable in the middle and lower left abdomen minimal intrinsic mobility and massive ascites. Since the admitted patient was diagnosed with DIC, surgery could not be performed. The patient received a platelet transfusion and the DIC was treated. Due to this treatment, the platelet count recovered to 7.0 × 10<sup>4</sup>; tumor resection was performed at 16 days after admission. Laparotomy revealed a huge extraluminal tumor arising from the greater curvature of the stomach that measured 25 × 30 cm and had not ruptured into the peritoneal cavity or infiltrated other organs. Partial gastric resection was performed. The resected mass measured 25 × 25 × 20 cm. In cross section, the tumor appeared hard and homogenous with a small polycystic area. Histopathology of the resected specimen showed large spindle cell GIST with >5/50 HPF (high-power field) mitotic activity. The postoperative course was uneventful, and the coagulopathy improved rapidly.</p> <p>Conclusion</p> <p>Since the characteristic of tumor in this case was hypervascularity with bleeding and necrotic lesions, coagulopathy was thought to be caused by the trapping of platelets within a large vasculized tumor mass.</p
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