Interference effects among \u3cem\u3eJ\u3c/em\u3e = 3/2\u3csup\u3e+\u3c/sup\u3e resonances in \u3csup\u3e19\u3c/sup\u3eNe system & Searching for resonances in the unbound \u3csup\u3e6\u3c/sup\u3eBe nucleus

The 18F(p,α)15O reaction plays a crucial role in understanding γ-ray emission from novae. Because of the importance of understanding the 18F + p reactions, a number of studies of the A=19 isobars have been made using stable and exotic beams. The interference effects among J π = 3/2+ resonances in the 18F + p system, however, have never been measured, but they can change the S-factor by a factor of 20 at nova energies. R-matrix calculations indicate that the cross sections above the Ec.m. = 665 keV resonance are sensitive to the interference between the Ec.m. = 8, 38, and 665 keV resonances. In order to study the interference effects, an excitation function for the 1H(18F,α)15O reaction has been measured in the energy range of Ec.m. = 663-877 keV using radioactive 18F beams at the Holifield Radioactive Ion Beam Facility (HRIBF). By measuring the 18F(p,α)15O cross section off resonance and comparing the cross section with theoretical calculations, we provide the first experimental constraints on the interference of 3/2+ resonances. The 3He(3He,2p)4He reaction is responsible for destruction of 3He in stars, and strongly affects the calculated neutrino luminosity from the sun. Previous measure- ments demonstrated a rise in the 3He(3He,2p)4He S-factor at low energies, which could be due to a low energy resonance in the 3He + 3He (6Be) system, or be due to an electron screening effect. In the 6Be nucleus, however, no excited states have been observed above the first 2+ state at Ex = 1.67 MeV up to 23 MeV. But there is considerable evidence to support the presence of unknown excited states in 6Be. First of all, in the mirror nucleus 6He two excited states have been established below the t + t threshold at Ex = 12.3 MeV. Secondly, a recent measurement at Notre Dame University found tentative evidence for a 6Be level at 9.6 MeV. A search for the missing 6Be levels was performed by studying the d(7Be,t)6Be reaction with the radioactive 7Be beam at Oak Ridge National Laboratory HRIBF. No excited states in 6Be were found; however, we could set the upper limits on the reaction cross section

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X-ray bursts (XRBs) have been thought to occur via thermonuclear runaway reactions on the surface of a neutron star. The runaway reactions are affected by both the properties of the accreted material, such as the accretion rate and the composition, and the reaction rates of participating nuclei. We investigate how the shape of the XRB light curve changes with specific reaction rates. As a case study, we choose three reaction rates, triple alpha, 18Ne(??; ??)21Na, and 15O(??; ??)19Ne. We find that the shape of the light curve does change with different reaction rates for the same reaction, but the predicted light curves with 54 isotopes do not match the observed ones even when the variations within the different reaction rates are considered. We confirm that the shape of the light curve is more sensitive to the number of isotopes that participate in the runaway reactionsclos

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The energy levels of the 23Mg radionuclide are very important for astrophysical reactions such as the 22Na(??,??)23Mg and the 19Ne(??,??)23Mg reactions, depending on their excitation energies. In the present manuscript, two independent 24Mg(??,d)23Mg transfer reaction measurements, which were performed by using 31- and 41-MeV proton beams from the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory in the United States and 24Mg solid targets, are summarized. Recoiling deuterons from the (p,d) reactions were detected by using a silicon strip detector array. By comparing the experimental angular distributions with the results of calculations using theoretical distorted-wave Born approximation, we were able, for the first time, to constrain the spins and the parities of seven energy levels in 23Mgclos

Hot CH_4 in the polar regions of Jupiter

We have obtained 3.3–3.4-μm spectro-images of Jupiter including CH_4 and H_3^+ emission lines from both polar regions at the Gemini North telescope. We find that the peak of the 3-μm CH_4 northern bright spot is located at ∼200° (SysIII) longitude, ∼20° west of the center of the 8-μm north-polar bright spot, and does not coincide with the 3-μm H_3^+ bright spot. We derive high temperatures (500–850 K) from CH_4 rotational lines on the bright spots of both polar regions, above the 1-μbar pressure level, while we find cooler temperatures (<350 K) over the 8-μm spot. The intensity ratios of the various 3-μm vibrational bands of CH4 are roughly constant, indicating that the upper states of these bands are mostly populated by non-thermal excitation mechanisms, such as auroral particle precipitation and/or Joule heating, in contrast with the 8-μm thermal emission

टेक्निकल बुल्लेटिन नं: 29 / 2012

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Beta-catenin overexpression reduces myocardial infarct size through differential effects on cardiomyocytes and cardiac fibroblasts

Beta-catenin is a transcriptional regulator of several genes involved in survival and proliferation. Although previous studies suggest that beta-catenin may be involved in the process of preconditioning and healing after myocardial infarction (MI), little is known regarding the role of beta-catenin in cardiomyocytes and cardiac fibroblasts. We investigated the role of beta-catenin in cardiomyocytes and cardiac fibroblasts and whether beta-catenin overexpression could reduce MI size. Adenovirus-mediated gene transfer of nonphosphorylatable constitutively active beta-catenin (Ad-catenin) decreased apoptosis in cardiomyocytes and cardiac fibroblasts with increased expression of survivin and Bcl-2. Although Ad-catenin increased the percentage of cells in the S phase with enhanced expression of cyclin D1 and E2 in both cell types, the increase in cell number was only evident in cardiac fibroblasts, whereas hypertrophy and binuclear cells were more prominent in cardiomyocytes. All of these effects of beta-catenin gene transfer were blocked by inhibition of its nuclear translocation. Furthermore, Ad-catenin enhanced the expression of vascular endothelial growth factor in both cells and induced differentiation of cardiac fibroblasts into myofibroblasts. In a rat MI model, injection of Ad-catenin into the infarct border zone resulted in a significantly decreased MI size with anti-apoptotic effect and cell cycle activation in both cardiomyocytes and myofibroblasts. beta-Catenin may play an important role in the healing process after MI by promoting survival and cell cycle not only in cardiomyocytes but also in cardiac fibroblasts with its differentiation into myofibroblasts

X-ray Burst Studies with the JENSA Gas Jet Target

When a neutron star accretes hydrogen and helium from the outer layers of its companion star, thermonuclear burning enables the αp-process as a break out mechanism from the hot CNO cycle. Model calculations predict (α, p) reaction rates significantly affect both the light curves and elemental abundances in the burst ashes. The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target enables the direct measurement of previously inaccessible (α,p) reactions with radioactive beams provided by the rare isotope re-accelerator ReA3 at the National Superconducting Cyclotron Laboratory (NSCL), USA. JENSA is going to be the main target for the Recoil Separator for Capture Reactions (SECAR) at the Facility for Rare Isotope Beams (FRIB). Commissioning of JENSA and first experiments at Oak Ridge National Laboratory (ORNL) showed a highly localized, pure gas target with a density of ∼1019 atoms per square centimeter. Preliminary results are presented from the first direct cross section measurement of the 34Ar(α, p)37 K reaction at NSCL