96 research outputs found

    K+(K0)- Condensation in Highly Dense Matter with the Relativistic Mean-Field Theory

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    Properties of dense hadronic matter including strange particles are studied within the relativistic mean-field theory (RMFT). The possibility of kaon condensation is reexamined, and a simple condition is found for the parameters included in RMFT.Comment: 12pages, Latex is used, 3 Postscript figures are available by request from [email protected]

    Effects of the Λ\Lambda(1405) on the Structure of Multi-Antikaonic Nuclei

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    The effects of the Λ\Lambda(1405) (Λ\Lambda^\ast) on the structure of the multi-antikaonic nucleus (MKN), in which several KK^- mesons are embedded to form deeply bound states, are considered based on chiral symmetry combined with a relativistic mean-field theory. It is shown that additional attraction resulting from the Λ\Lambda^\ast pole has a sizable contribution to not only the density profiles for the nucleons and KK^- mesons but also the ground state energy of the KK^- mesons and binding energy of the MKN as the number of the embedded KK^- mesons increases.Comment: 4 pages, 3 figures, Talk presented at the 10th International Conference on Hypernuclear and Strange Particle Physics (Hyp-X), Tokai, Japan, Sept. 14-18, 2009. To be published in Nucl. Phys.

    Enrichment of r-process elements in dwarf spheroidal galaxies in chemo-dynamical evolution model

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    The rapid neutron-capture process (r-process) is a major process to synthesize elements heavier than iron, but the astrophysical site(s) of r-process is not identified yet. Neutron star mergers (NSMs) are suggested to be a major r-process site from nucleosynthesis studies. Previous chemical evolution studies however require unlikely short merger time of NSMs to reproduce the observed large star-to-star scatters in the abundance ratios of r-process elements relative to iron, [Eu/Fe], of extremely metal-poor stars in the Milky Way (MW) halo. This problem can be solved by considering chemical evolution in dwarf spheroidal galaxies (dSphs) which would be building blocks of the MW and have lower star formation efficiencies than the MW halo. We demonstrate that enrichment of r-process elements in dSphs by NSMs using an N-body/smoothed particle hydrodynamics code. Our high-resolution model reproduces the observed [Eu/Fe] by NSMs with a merger time of 100 Myr when the effect of metal mixing is taken into account. This is because metallicity is not correlated with time up to ~ 300 Myr from the start of the simulation due to low star formation efficiency in dSphs. We also confirm that this model is consistent with observed properties of dSphs such as radial profiles and metallicity distribution. The merger time and the Galactic rate of NSMs are suggested to be <~ 300 Myr and ~ 10410^{-4} yr1^{-1}, which are consistent with the values suggested by population synthesis and nucleosynthesis studies. This study supports that NSMs are the major astrophysical site of r-process.Comment: 16 pages, 16 figures, accepted for publication in Ap

    A case of oncocytic papillary cystadenocarcinoma of the parotid gland—Pathological and molecular features of a rare tumor

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    AbstractWe present histological, immunohistochemical and molecular features of oncocytic papillary cystadenocarcinoma, a rare neoplasm of the salivary and parotid glands, in an 82-year-old Japanese man. The resected tumor was solid nodular mass with fibrous capsule. The tumor was composed of papillary proliferation of tall columnar cells with thin vascular cores. The cytoplasm of the tumor cells was granular and eosinophilic. The tumor cells showed clear positive reaction for mitochondria and androgen receptor. GCDFP15 and HER2 were negative. Electron microscopy demonstrated numerous mitochondria in the cytoplasm of the tumor cells. Ki-67 index was 30%. Most of the tumor cells were positive for TP53, and single nucleotide polymorphism was found at codon 151. The invasion into the lymphatic spaces and capsule was noted. Although recurrence and metastasis were not noted at one and a half years after the resection, the patient needs to be followed up under careful observation

    Thermal and Quantum Fluctuations in the Kaon Condensed Phase

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    A new formulation is presented to treat thermal and quantum fluctuations around the kaon condensate on the basis of chiral symmetry; separating the zero-mode from the beginning and using the path-integral method, we can formulate the inclusion of fluctuations in a transparent way. Nucleons as well as kaons are treated in a self-consistent way to the one-loop order. The effects of the Goldstone mode, stemming from the breakdown of V- spin symmetry in the condensed phase, are figured out. A procedure is discussed to renormalize the divergent integrals properly up to the one-loop order. Consequently the thermodynamic potential is derived. It is pointed out that the zero-point fluctuation by nucleons gives a sizable effect, different from the kaonic one.Comment: 27 page

    Cancer activity and bleeding events post-PCI

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    Purpose : Limited data exist about clinically relevant bleeding events related to antiplatelet therapy after percutaneous coronary intervention (PCI) in cancer patients. We investigated the risk factors for clinically relevant bleeding events in patients with cancer after PCI with stent implantation. Patients and Methods : Patients with solid cancer subjected to first PCI were divided into active (n = 45) and non-active cancer groups (n = 44). The active group included non-operable patients on treatment or with metastasis ; the non-active included those already subjected to or for whom radical surgery was planned within 3 months after the index PCI. Results : During a median follow-up of 2.2 years, 11 bleeding events occurred, with only one occurring in the non-active cancer group. Half of them occurred during the dual-antiplatelet therapy (DAPT) period, and the rest occurred during single-antiplatelet therapy (SAPT) period. Kaplan-Meier analysis showed significantly more bleeding events in the active cancer group (p = 0.010). Multivariate Cox regression hazard analysis revealed cancer activity as a significant independent risk factor for bleeding (p = 0.023) ; but not for three-point major adverse cardiovascular events. Conclusion : Clinically relevant bleeding risk after PCI was significantly lower in non-active cancer. Active cancer group had clinically relevant bleeding during both DAPT and SAPT periods

    Kaon Condensation and Lambda-Nucleon Loop in the Relativistic Mean-Field Approach

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    The possibility of kaon condensation in high-density symmetric nuclear matter is investigated including both s- and p-wave kaon-baryon interactions within the relativistic mean-field (RMF) theory. Above a certain density, we have a collective Kˉs{\bar K}_s state carrying the same quantum numbers as the antikaon. The appearance of the Kˉs{\bar K}_s state is caused by the time component of the axial-vector interaction between kaons and baryons. It is shown that the system becomes unstable with respect to condensation of KK-Kˉs{\bar K}_s pairs. We consider how the effective baryon masses affect the kaon self-energy coming from the time component of the axial-vector interaction. Also, the role of the spatial component of the axial-vector interaction on the possible existence of the collective kaonic states is discussed in connection with Λ\Lambda-mixing effects in the ground state of high-density matter. Implications of KKˉsK{\bar K}_s condensation for high-energy heavy-ion collisions are briefly mentioned.Comment: 27 pages text, 8 figure

    Neutrino Opacities in Neutron Stars with Kaon Condensates

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    The neutrino mean free paths in hot neutron-star matter are obtained in the presence of kaon condensates. The kaon-induced neutrino absorption process, which is allowed only in the presence of kaon condensates, is considered for both nondegenerate and degenerate neutrinos. The neutrino mean free path due to this process is compared with that for the neutrino-nucleon scattering. While the mean free path for the kaon-induced neutrino absorption process is shown to be shorter than the ordinary two-nucleon absorption process by several orders of magnitude when temperature is not very high, the neutrino-nucleon scattering process has still a dominant contribution to the neutrino opacity. Thus, the kaon-induced neutrino absorption process has a minor effect on the thermal and dynamical evolution of protoneutron stars.Comment: 35 pages, 4 figure
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