226 research outputs found

    Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u

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    We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of 50∼40050 \sim 400 MeV/u. The GOP is derived from the microscopic folding model with the complex GG-matrix interaction CEG07 and the global density presented by S{\~ a}o Paulo group. The folding model well accounts for realistic complex optical potentials of nucleus-nucleus systems and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, 8βˆ’22^{8-22}C, 12βˆ’24^{12-24}O, 16βˆ’38^{16-38}Ne, 20βˆ’40^{20-40}Mg, 22βˆ’48^{22-48}Si, 26βˆ’52^{26-52}S, 30βˆ’62^{30-62}Ar, and 34βˆ’70^{34-70}Ca, scattered by stable target nuclei of 12^{12}C, 16^{16}O, 28^{28}Si, 40^{40}Ca 58^{58}Ni, 90^{90}Zr, 120^{120}Sn, and 208^{208}Pb at the incident energy of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers and the projectile atomic number, while the range parameters are taken to depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a Fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.Comment: 25 pages, 13 figure

    Slow Slip Events and Time-Dependent Variations in Locking Beneath Lower Cook Inlet of the Alaska-Aleutian Subduction Zone

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    We identify a series of abrupt changes in GPS site velocities in Lower Cook Inlet, Alaska, in late 2004, early 2010, and late 2011. The site motions during each time period are nearly linear. The surface deformations inferred from GPS for pre-2004 and 2010–2011 are similar to each other, as are 2004–2010 and post-2011. We estimate the slip distribution on the Alaska-Aleutian subduction plate interface accounting for upper plate block rotations and interpret this toggling between two deformation patterns as caused by transient slip. We find that by allowing negative slip deficit rates (i.e., creep rates in excess of relative plate motion), the data in Lower Cook Inlet are fit significantly better during pre-2004 and 2010–2011, suggesting the occurrence of slow slip events (SSEs) there during those time periods. The earlier SSE lasted at least 9 years (observations in that area began in 1995) with Mw ~7.8. The latter SSE had almost the same area as the earlier one and a duration of ~2 years with Mw ~7.2. During 2004–2010 and post-2011, the inversions result in only positive slip deficit rates (i.e., locking) in Lower Cook Inlet. Slip rates are nearly constant during the Lower Cook Inlet SSEs, and the events start and stop abruptly. Both of these properties contrast with observations of SSEs in Upper Cook Inlet and elsewhere. The Lower Cook Inlet SSEs are consistent with previously proposed duration-magnitude scaling laws and demonstrate that slow slip events can last as long as a decade

    Negative Regulation of Immunoglobulin E–dependent Allergic Responses by Lyn Kinase

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    A role for Lyn kinase as a positive regulator of immunoglobulin (Ig)E-dependent allergy has long been accepted. Contrary to this belief, Lyn kinase was found to have an important role as a negative regulator of the allergic response. This became apparent from the hyperresponsive degranulation of lynβˆ’/βˆ’ bone marrow–derived mast cells, which is driven by hyperactivation of Fyn kinase that occurs, in part, through the loss of negative regulation by COOH-terminal Src kinase (Csk) and the adaptor, Csk-binding protein. This phenotype is recapitulated in vivo as young lynβˆ’/βˆ’ mice showed an enhanced anaphylactic response. In vivo studies also demonstrated that as lynβˆ’/βˆ’ mice aged, their serum IgE increased as well as occupancy of the high affinity IgE receptor (FcΞ΅RI). This was mirrored by increased circulating histamine, increased mast cell numbers, increased cell surface expression of the high affinity IgE receptor (FcΞ΅RI), and eosinophilia. The increased IgE production was not a consequence of increased Fyn kinase activity in lynβˆ’/βˆ’ mice because both lynβˆ’/βˆ’ and lynβˆ’/βˆ’ fynβˆ’/βˆ’ mice showed high IgE levels. Thus, lynβˆ’/βˆ’ mice and mast cells thereof show multiple allergy-associated traits, causing reconsideration of the possible efficacy in therapeutic targeting of Lyn in allergic disease

    Hawaii Geothermal Project : quarterly progress report no. 3 (December 1, 1973 through February 28, 1974)

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    Discussion of early exploration research conducted under the Hawaii Geothermal Project.Support for project provided by National Science Foundation, State of Hawaii, County of Hawai

    Anaphylatoxin C3a receptors in asthma

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    The complement system forms the central core of innate immunity but also mediates a variety of inflammatory responses. Anaphylatoxin C3a, which is generated as a byproduct of complement activation, has long been known to activate mast cells, basophils and eosinophils and to cause smooth muscle contraction. However, the role of C3a in the pathogenesis of allergic asthma remains unclear. In this review, we examine the role of C3a in promoting asthma. Following allergen challenge, C3a is generated in the lung of subjects with asthma but not healthy subjects. Furthermore, deficiency in C3a generation or in G protein coupled receptor for C3a abrogates allergen-induced responses in murine models of pulmonary inflammation and airway hyperresponsiveness. In addition, inhibition of complement activation or administration of small molecule inhibitors of C3a receptor after sensitization but before allergen challenge inhibits airway responses. At a cellular level, C3a stimulates robust mast cell degranulation that is greatly enhanced following cell-cell contact with airway smooth muscle (ASM) cells. Therefore, C3a likely plays an important role in asthma primarily by regulating mast cell-ASM cell interaction

    Exploring the Switchgrass Transcriptome Using Second-Generation Sequencing Technology

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    Background: Switchgrass (Panicum virgatum L.) is a C4 perennial grass and widely popular as an important bioenergy crop. To accelerate the pace of developing high yielding switchgrass cultivars adapted to diverse environmental niches, the generation of genomic resources for this plant is necessary. The large genome size and polyploid nature of switchgrass makes whole genome sequencing a daunting task even with current technologies. Exploring the transcriptional landscape using next generation sequencing technologies provides a viable alternative to whole genome sequencing in switchgrass. Principal Findings: Switchgrass cDNA libraries from germinating seedlings, emerging tillers, flowers, and dormant seeds were sequenced using Roche 454 GS-FLX Titanium technology, generating 980,000 reads with an average read length of 367 bp. De novo assembly generated 243,600 contigs with an average length of 535 bp. Using the foxtail millet genome as a reference greatly improved the assembly and annotation of switchgrass ESTs. Comparative analysis of the 454-derived switchgrass EST reads with other sequenced monocots including Brachypodium, sorghum, rice and maize indicated a 70– 80 % overlap. RPKM analysis demonstrated unique transcriptional signatures of the four tissues analyzed in this study. More than 24,000 ESTs were identified in the dormant seed library. In silico analysis indicated that there are more than 2000 EST-SSRs in this collection. Expression of several orphan ESTs was confirmed by RT-PCR. Significance: We estimate that about 90 % of the switchgrass gene space has been covered in this analysis. This study nearl
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