540 research outputs found

    Mirror model for sterile neutrinos

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    Sterile neutrinos are studied as subdominant contribution to solar neutrino physics. The mirror-matter neutrinos are considered as sterile neutrinos. We use the symmetric mirror model with gravitational communication between mirror and visible sectors. This communication term provides mixing between visible and mirror neutrinos with the basic scale mu=v^2/M_Pl=5*10^-6 eV, where v=174 GeV is the vacuum expectation value of the standard electroweak group and M_Pl is the Planckian mass. It is demonstrated that each mass eigenstate of active neutrinos splits into two states separated by small Delta m^2. Unsuppressed oscillations between active and sterile neutrinos nu_a --> nu_s occur only in transitions between each of these close pairs (``windows''). These oscillations are characterized by very small Delta m^2 and can suppress the flux and distort spectrum of pp-neutrinos in detectable way. The other observable effect is anomalous seasonal variation of neutrino flux, which appears in LMA solution. The considered subdominant neutrino oscillations nu_a nu_s can reveal itself as big effects in observations of supernova neutrinos and high energy (HE) neutrinos. In the case of HE neutrinos they can provide a very large diffuse flux of active neutrinos unconstrained by the e-m cascade upper limit.Comment: 30 pags, 5 figs. V2: Refs added, minor editing. Accepted in NP

    A phenomenological equation of state for isospin asymmetric nuclear matter

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    A phenomenological momentum-independent (MID) model is constructed to describe the equation of state (EOS) for isospin asymmetric nuclear matter, especially the density dependence of the nuclear symmetry energy Esym(ρ)E_{\text{\textrm{sym}}}(\rho). This model can reasonably describe the general properties of the EOS for symmetric nuclear matter and the symmetry energy predicted by both the sophisticated isospin and momentum dependent MDI model and the Skyrme-Hartree-Fock approach. We find that there exists a nicely linear correlation between KsymK_{\mathrm{sym}} and LL as well as between J0/K0J_{0}/K_{0} and K0K_{0}, where LL and KsymK_{\mathrm{sym}} represent, respectively, the slope and curvature parameters of the symmetry energy at the normal nuclear density ρ0\rho_{0} while K0K_{0} and J0J_{0} are, respectively, the incompressibility and the third-order derivative parameter of symmetric nuclear matter at ρ0\rho_{0}. These correlations together with the empirical constraints on K0K_{0}, LL and Esym(ρ0)E_{\text{\textrm{sym}}}(\rho_{0}) lead to an estimation of -477 MeV Ksat,2241\leq K_{\mathrm{sat,2}}\leq -241 MeV for the second-order isospin asymmetry expansion coefficient for the incompressibility of asymmetric nuclear matter at the saturation point.Comment: 9 pages, 4 figures, contribution to Special Topic on Large-Scale Scientific Facilities (LSSF) in Science in China Series G: Physics, Mechanics & Astronom

    Application of the density dependent hadron field theory to neutron star matter

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    The density dependent hadron field (DDRH) theory, previously applied to isospin nuclei and hypernuclei is used to describe β\beta-stable matter and neutron stars under consideration of the complete baryon octet. The meson-hyperon vertices are derived from Dirac-Brueckner calculations of nuclear matter and extended to hyperons. We examine properties of density dependent interactions derived from the Bonn A and from the Groningen NN potential as well as phenomenological interactions. The consistent treatment of the density dependence introduces rearrangement terms in the expression for the baryon chemical potential. This leads to a more complex condition for the β\beta-equilibrium compared to standard relativistic mean field (RMF) approaches. We find a strong dependence of the equation of state and the particle distribution on the choice of the vertex density dependence. Results for neutron star masses and radii are presented. We find a good agreement with other models for the maximum mass. Radii are smaller compared to RMF models and indicate a closer agreement with results of non-relativistic Brueckner calculations.Comment: 28 pages, 11 figure

    Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei

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    The Relativistic Continuum Hartree-Bogoliubov (RCHB) theory, which properly takes into account the pairing correlation and the coupling to (discretized) continuum via Bogoliubov transformation in a microscopic and self-consistent way, has been reviewed together with its new interpretation of the halo phenomena observed in light nuclei as the scattering of particle pairs into the continuum, the prediction of the exotic phenomena -- giant halos in nuclei near neutron drip line, the reproduction of interaction cross sections and charge-changing cross sections in light exotic nuclei in combination with the Glauber theory, better restoration of pseudospin symmetry in exotic nuclei, predictions of exotic phenomena in hyper nuclei, and new magic numbers in superheavy nuclei, etc. Recent investigations on new effective interactions, the density dependence of the interaction strengthes, the RMF theory on the Woods-Saxon basis, the single particle resonant states, and the resonant BCS (rBCS) method for the pairing correlation, etc. are also presented in some details.Comment: 79 pages. Prog. Part. Nucl. Phys. (2005) in pres

    PENGAWASAN PASAR TERTIB UKUR OLEH DINAS KOPERASI USAHA KECIL DAN MENENGAH, PERINDUSTRIAN DAN PERDAGANGAN (KOPERINDAG) DI PASAR BATUSANGKAR

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    Pasar tertib Ukur, Takaran, Timbangan dan Perlengkapannya (UTTP) adalah pasar yang patuh menyangkut pemakaian alat ukur, timbangan dan perlengkapannya (UTTP) oleh pedagang yang mengacu kepada Undang-Undang Nomor 2 Tahun 1981 terkait Metrologi Legal. Salah satu indikator penting dalam pasar tertib ukur tersebut adalah kepastian kebenaran dalam penggunaan alat ukur, khususnya pada saat transaksi perdagangan. Pasar tertib ukur merupakan pasar yang pedagangnya menggunakan UTTP mengikuti peraturan perundang-undangan yang berlaku. Rumusan masalah yang akan dibahas yaitu: 1) Bagaimana pengawasan pasar tertib ukur oleh Dinas Koperasi Usaha Kecil dan Menengah, perindustrian dan perdagangan (KOPERINDAG) di Pasar Batusangkar? 2) Kendala apa saja yang dihadapi dalam pengelolaan pasar tertib ukur di Pasar Batusangkar ?. Penelitian ini dilakukan di Dinas Koperasi, UKM, Perindustrian dan Perdagangan (KOPERINDAG) Kabupaten Tanah Datar, Sumatera Barat. Jenis data yang digunakan adalah data primer dan data sekunder. Adapun metode penelitian yang diimplementasikan dalam penelitian ini yaitu metode penelitian hukum empiris. Teknik pengumpulan data diperoleh dari wawancara dan Studi dokumen. Jenis data yang diperoleh dianalisis secara kualitatif dan disajikan secara deskriptif. Berdasarkan hasil penelitian dapat disimpulkan: 1) Dalam pengawasan pasar tertib ukur terdapat 3 tahap yaitu : Tahap perencanaan, tahap pengawasan dan tahap penertiban; 2) Pengelolaan Pasar Tertib Ukur di Pasar Batusangkar masih belum terlaksana sesuai dengan perencanaan dan aturan yang berlaku karena terkendala oleh hal-hal terkait masalah penertiban alat ukur dan lemahnya regulasi pasar tertib ukur, sehingga diperlukan koordinasi beupa diskusi antar Dinas Koperindag sebagai pengelola pasar tertib ukur dengan pedagang di pasar. Selain itu juga dibutuhkan penyuluhan yang lebih intens kepada para pedagang mengenai pasar tertib ukur sehingga dapat membantu terlaksananya pengelolaan pasar tertib ukur dengan baik. Kata Kunci: Pasar Tertib Ukur, Pengawasan, UTTP

    Regression model for the study of sole and cumulative effect of temperature and solar radiation on wheat yield

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    The effect of variability in temperature, solar radiation and photothermal quotient were studied under varying planting windows in three wheat genotypes to cope environmental vulnerability. Regression models are regarded as valuable tools for the evaluation of temperature, solar radiation and photothermal quotient effects on wheat yield to bring its resilience to climatic vulnerability. The objective of this study was to evaluate sole and cumulative impact of temperature and solar radiation on spring wheat (Triticum aestivum L.) yield using regression modeling approach. The data collected at maturity for grain number, grain weight and grain yield were regressed against mean temperature, solar radiation and photothermal quotient (PTQ) (temperature plus solar radiation) from emergence to anthesis and maturity, using STATISTICA9 software. Scatter-plot regression model was developed at 95% confidence interval with crop data and climate variables. Results indicate direct relationship of yield with solar radiation, cumulative effect of temperature and solar radiation, whereas yield had an inverse relationship with temperature alone. Direct relationship between PTQ and yield parameters confirmed PTQ as crop-yield determinant, thus, its management needs to be done by choosing a more appropriate sowing time and best suited genotypes as an adapted management strategy for farmers under increased climatic vulnerability.Key words: Photothermal quotient, planting windows, solar radiation, temperature, wheat

    Reaction rates and transport in neutron stars

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    Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions.Comment: 74 pages; commissioned for the book "Physics and Astrophysics of Neutron Stars", NewCompStar COST Action MP1304; version 3: minor changes, references updated, overview graphic added in the introduction, improvements in Sec IV.A.

    Logistic Organ Dysfunction Score (LODS): A reliable postoperative risk management score also in cardiac surgical patients?

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    <p>Abstract</p> <p>Background</p> <p>The original Logistic Organ Dysfunction Sore (LODS) excluded cardiac surgery<ul/>patients from its target population, and the suitability of this score in cardiac surgery patients has never been tested. We evaluated the accuracy of the LODS and the usefulness of its daily measurement in cardiac surgery patients. The LODS is not a true logistic scoring system, since it does not use β-coefficients.</p> <p>Methods</p> <p>This prospective study included all consecutive adult patients who were admitted to<ul/>the intensive care unit (ICU) after cardiac surgery between January 2007 and December 2008. The LODS was calculated daily from the first until the seventh postoperative day. Performance was assessed with Hosmer-Lemeshow (HL) goodness-of-fit test (calibration) and receiver operating characteristic (ROC) curves (discrimination) from ICU admission day until day 7. The outcome measure was ICU mortality.</p> <p>Results</p> <p>A total of 2801 patients (29.6% female) with a mean age of 66.4 ± 10.7 years were<ul/>included. The ICU mortality rate was 5.2% (n = 147). The mean stay on the ICU was 4.3 ± 6.8 days. Calibration of the LODS was good with no significant difference between expected and observed mortality rates on any day (p ≥ 0.05). The initial LODS had an area under the ROC curve (AUC) of 0.81. The AUC was best on ICU day 3 with a value of 0.93, and declined to 0.85 on ICU day 7.</p> <p>Conclusions</p> <p>Although the LODS has not previously been validated for cardiac surgery<ul/>patients it showed reasonable accuracy in prediction of ICU mortality in patients after cardiac surgery.</p

    Pairing in nuclear systems: from neutron stars to finite nuclei

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    We discuss several pairing-related phenomena in nuclear systems, ranging from superfluidity in neutron stars to the gradual breaking of pairs in finite nuclei. We focus on the links between many-body pairing as it evolves from the underlying nucleon-nucleon interaction and the eventual experimental and theoretical manifestations of superfluidity in infinite nuclear matter and of pairing in finite nuclei. We analyse the nature of pair correlations in nuclei and their potential impact on nuclear structure experiments. We also describe recent experimental evidence that points to a relation between pairing and phase transitions (or transformations) in finite nuclear systems. Finally, we discuss recent investigations of ground-state properties of random two-body interactions where pairing plays little role although the interactions yield interesting nuclear properties such as 0+ ground states in even-even nuclei.Comment: 74 pages, 33 figs, uses revtex4. Submitted to Reviews of Modern Physic
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