8,521 research outputs found

    The Solar pp and hep Processes in Effective Field Theory

    Full text link
    The strategy of modern effective field theory is exploited to pin down accurately the flux SS factors for the pppp and hephep processes in the Sun. The technique used is to combine the high accuracy established in few-nucleon systems of the "standard nuclear physics approach" (SNPA) and the systematic power counting of chiral perturbation theory (ChPT) into a consistent effective field theory framework. Using highly accurate wave functions obtained in the SNPA and working to \nlo3 in the chiral counting for the current, we make totally parameter-free and error-controlled predictions for the pppp and hephep processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3, 200

    The Solar Proton Burning Process Revisited In Chiral Perturbation Theory

    Get PDF
    The proton burning process p + p -> d + e(+) + \nu(e), important for the stellar evolution of main-sequence stars of mass equal to or less than that of the Sun, is computed in effective field theory using chiral perturbation expansion to the next-to-next-to leading chiral order. This represents a model-independent calculation consistent with low-energy effective theory of QCD comparable in accuracy to the radiative np capture at thermal energy previously calculated by first using very accurate two-nucleon wavefunctions backed up by an effective field theory technique with a finite cut-off. The result obtained thereby is found to support within theoretical uncertainties the previous calculation of the same process by Bahcall and his co-workers.Comment: 30 pages, 2 eps files, aaspp4.sty needed, slightly modified, to be published in Ap.

    Quantum Key Distribution with Blind Polarization Bases

    Full text link
    We propose a new quantum key distribution scheme that uses the blind polarization basis. In our scheme the sender and the receiver share key information by exchanging qubits with arbitrary polarization angles without basis reconciliation. As only random polarizations are transmitted, our protocol is secure even when a key is embedded in a not-so-weak coherent-state pulse. We show its security against the photon number splitting attack and the impersonation attack.Comment: Security has been improved upon referee's comment. 4 pages and 2 figure

    Unintended Pregnancy Prevention and Active Duty Women

    Get PDF
    Studies have shown that a structured education program for women decreases risky sexual behavior identified as vulnerable for AIDS. However, the outcomes from a structured, repeated, educational intervention in reducing the rates of unintended pregnancies have not been studied in military females who are considered as a high risk. The purpose of this quasi-experimental longitudinal study was to implement and evaluate the effects of a reproductive health educational program regarding knowledge, attitudes, decisional balance, self-efficacy, stages of change, and contraceptive use, and to identify independent variables most likely to predict behavior change in the use of contraceptives among single, active duty women during the 4-month study period. The theoretical framework for this study was based on the proposed Contraceptive Behavior Change Model. Descriptive statistics, t-tests, contingency tables using chi square, two-way repeated measures ANOVA, regression, and correlation were used to analyze data from the sample of 104 Navy enlisted females recruited from the ships in San Diego, CA. In this study, the program was effective in increasing knowledge and repetitive intervention proved a better long-term effect in knowledge retention. A significant difference in a positive attitude change over time was seen in the experimental group, making subjects more accepting about contraception and family planning. Study variables of knowledge and stages of change correlated positively with contraceptive use, while knowledge, decisional balance measure, cons, and self-efficacy correlated with attitude. Regression analyses indicated that knowledge and stages of change over 4 months of the program explained 90% (experimental group) and 64% (control group) of the variance in contraceptive use at the end of the program. There was a decrease in sexual activity and greater use of contraceptive methods over time among sexually active individuals in the experimental group, leading to decreased unintended pregnancies. The reduced rate has the potential benefit of a significant cost-savings to the society, as well as improved mobilization readiness and quality of life for sailors and their families. In addition to implementing effective interventions to reduce unintended pregnancy, future research is needed to examine issues surrounding contraceptive non-use and/or to investigate the motivational components of adolescent pregnancy

    Chiral Dynamics and Heavy-Fermion Formalism in Nuclei: Exchange Axial Currents

    Get PDF
    URL: http://www-spht.cea.fr/articles/T93/013 http://fr.arxiv.org/abs/hep-ph/9301295International audienceChiral perturbation theory in heavy-fermion formalism is developed for meson-exchange currents in nuclei and applied to nuclear axial-charge transitions. Calculation is performed to the next-to-leading order in chiral expansion which involves graphs up to one loop. The result turns out to be very simple. The previously conjectured notion of \lq\lq chiral filter mechanism\rq\rq\ in the time component of the nuclear axial current on the space component of the nuclear electromagnetic current is verified to that order. As a consequence, the phenomenologically observed soft-pion dominance in the nuclear process is given a simple interpretation in terms of chiral symmetry in nuclei. In this paper we focus on the axial current, relegating the electromagnetic current which can be treated in a similar way to a separate paper. We discuss the implication of our result on the enhanced axial-charge transitions observed in heavy nuclei and clarify the relationship between the phenomenological meson-exchange description and the chiral Lagrangian description.Lorqu'on cherche à appliquer la théorie des perturbations chirales à des processus où entrent en jeu les nucléons et les mésons, on se heurte à une difficulté liée à la masse du nucléon qui est grande par rapport aux petits paramètres de la théorie (impulsions externes, masse du pion, constante de désintégration du pion). Dans ce travail les auteurs appliquent le formalisme des baryons lourds pour lever cette difficulté. Grossièrement parlant ce formalisme travaille avec des champs des nucléons redéfinis de manière à éliminer les effets de la masse du nucléon. Cela permet aux auteurs d'identifier l'ordre en nombre de boucles à l'ordre de la perturbation chirale. Les calculs deviennent plus rigoureux et en sont grandement simplifiés. Les auteurs appliquent leur méthode au calcul, jusqu'au deuxième ordre, de l'interaction du courant électrofaible avec les noyaux

    Pharmacological activation of FOXO3 suppresses triple-negative breast cancer in vitro and in vivo

    Get PDF
    Triple-negative breast cancer (TNBC) is the most lethal form of breast cancer. Lacking effective therapeutic options hinders treatment of TNBC. Here, we show that bepridil (BPD) and trifluoperazine (TFP), which are FDA-approved drugs for treatment of schizophrenia and angina respectively, inhibit Akt-pS473 phosphorylation and promote FOXO3 nuclear localization and activation in TNBC cells. BPD and TFP inhibit survival and proliferation in TNBC cells and suppress the growth of TNBC tumors, whereas silencing FOXO3 reduces the BPD- and TFP-mediated suppression of survival in TNBC cells. While BPD and TFP decrease the expression of oncogenic c-Myc, KLF5, and dopamine receptor DRD2 in TNBC cells, silencing FOXO3 diminishes BPD- and TFP-mediated repression of the expression of these proteins in TNBC cells. Since c-Myc, KLF5, and DRD2 have been suggested to increase cancer stem cell-like populations in various tumors, reducing these proteins in response to BPD and TFP suggests a novel FOXO3-dependent mechanism underlying BPD- and TFP-induced apoptosis in TNBC cells

    The Solar hep Process in Effective Field Theory

    Full text link
    Using effective field theory, we calculate the S-factor for the hep process in a totally parameter-free formulation. The transition operators are organized according to chiral counting, and their matrix elements are evaluated using the realistic nuclear wave functions obtained in the correlated-hyperspherical-harmonics method. Terms of up to next-to-next-to-next-to-leading order in heavy-baryon chiral perturbation theory are considered. Fixing the only parameter in the theory by fitting the tritium \beta-decay rate, we predict the hep S-factor with accuracy better than \sim 20 %.Comment: 4 pages, Revtex. Minor revision has been mad
    corecore