234 research outputs found

    An apprach to generate large and small leptonic mixing angles

    Full text link
    We take up the point of view that Yukawa couplings can be either 0 or 1, and the mass patterns of fermions are generated purely from the structure of the Yukawa matrices. We utilize such neutrino as well as charged leptonic textures which lead to (maximal) mixing angles of π/4\pi/4 in each sector for relevant transitions. The combined leptonic CKM mixing angles are π/4±π/4\pi/4 \pm \pi/4 which lead to very small sin22Θ\sin^2 2 \Theta relevant to solar neutrino and LSND experiments. We propose that on the other hand the absence of the charged leptonic partner of the sterile neutrino maintains the angle π/4\pi/4 from the neutrino sector for the transition νμνs\nu_\mu \leftrightarrow \nu_s and hence atmospheric neutrino anomaly is explained through maximal mixing

    Exactly Solvable Hydrogen-like Potentials and Factorization Method

    Get PDF
    A set of factorization energies is introduced, giving rise to a generalization of the Schr\"{o}dinger (or Infeld and Hull) factorization for the radial hydrogen-like Hamiltonian. An algebraic intertwining technique involving such factorization energies leads to derive nn-parametric families of potentials in general almost-isospectral to the hydrogen-like radial Hamiltonians. The construction of SUSY partner Hamiltonians with ground state energies greater than the corresponding ground state energy of the initial Hamiltonian is also explicitly performed.Comment: LaTex file, 21 pages, 2 PostScript figures and some references added. To be published in J. Phys. A: Math. Gen. (1998

    Generalized stochastic Schroedinger equations for state vector collapse

    Get PDF
    A number of authors have proposed stochastic versions of the Schr\"odinger equation, either as effective evolution equations for open quantum systems or as alternative theories with an intrinsic collapse mechanism. We discuss here two directions for generalization of these equations. First, we study a general class of norm preserving stochastic evolution equations, and show that even after making several specializations, there is an infinity of possible stochastic Schr\"odinger equations for which state vector collapse is provable. Second, we explore the problem of formulating a relativistic stochastic Schr\"odinger equation, using a manifestly covariant equation for a quantum field system based on the interaction picture of Tomonaga and Schwinger. The stochastic noise term in this equation can couple to any local scalar density that commutes with the interaction energy density, and leads to collapse onto spatially localized eigenstates. However, as found in a similar model by Pearle, the equation predicts an infinite rate of energy nonconservation proportional to δ3(0)\delta^3(\vec 0), arising from the local double commutator in the drift term.Comment: 24 pages Plain TeX. Minor changes, some new references. To appear in Journal of Physics

    Linear Collider Capabilities for Supersymmetry in Dark Matter Allowed Regions of the mSUGRA Model

    Full text link
    Recent comparisons of minimal supergravity (mSUGRA) model predictions with WMAP measurements of the neutralino relic density point to preferred regions of model parameter space. We investigate the reach of linear colliders (LC) with s=0.5\sqrt{s}=0.5 and 1 TeV for SUSY in the framework of the mSUGRA model. We find that LCs can cover the entire stau co-annihilation region provided \tan\beta \alt 30. In the hyperbolic branch/focus point (HB/FP) region of parameter space, specialized cuts are suggested to increase the reach in this important ``dark matter allowed'' area. In the case of the HB/FP region, the reach of a LC extends well past the reach of the CERN LHC. We examine a case study in the HB/FP region, and show that the MSSM parameters μ\mu and M2M_2 can be sufficiently well-measured to demonstrate that one would indeed be in the HB/FP region, where the lightest chargino and neutralino have a substantial higgsino component.Comment: 29 pages, 15 EPS figures; updated version slightly modified to conform with published versio

    Design and Evaluation of Path Planning Decision Support for Planetary Surface Exploration

    Get PDF
    Human intent is an integral part of real-time path planning and re-planning, thus any decision aiding system must support human-automation interaction. The appropriate balance between humans and automation for this task has previously not been adequately studied. In order to better understand task allocation and collaboration between humans and automation for geospatial path problem solving, a prototype path planning aid was developed and tested. The focus was human planetary surface exploration, a high risk, time-critical domain, but the scenario is representative of any domain where humans path plan across uncertain terrain. Three visualizations, including elevation contour maps, a novel visualization called levels of equal costs, and a combination of the two were tested along with two levels of automation. When participants received the lower level of automation assistance, their path costs errors were less than 35% of the optimal, and they integrated manual sensitivity analysis strategies. When participants used the higher level of automation assistance, path costs errors were reduced to a few percentages, and they saved on average 1.5 minutes in the task. However, this increased performance came at the price of decreased situation awareness and automation bias.We would like to acknowledge the NASA Harriett G. Jenkins Predoctoral Fellowship and the Office of Naval Research for sponsoring this research

    Behavioral determinants as predictors of return to work after long-term sickness absence: an application of the theory of planned behavior

    Get PDF
    Background The aim of this prospective, longitudinal cohort study was to analyze the association between the three behavioral determinants of the theory of planned behavior (TPB) model-attitude, subjective norm and self-efficacy-and the time to return-to-work (RTW) in employees on long-term sick leave. Methods The study was based on a sample of 926 employees on sickness absence (maximum duration of 12 weeks). The employees filled out a baseline questionnaire and were subsequently followed until the tenth month after listing sick. The TPB-determinants were measured at baseline. Work attitude was measured with a Dutch language version of the Work Involvement Scale. Subjective norm was measured with a self-structured scale reflecting a person's perception of social support and social pressure. Self-efficacy was measured with the three subscales of a standardised Dutch version of the general self-efficacy scale (ALCOS): willingness to expend effort in completing the behavior, persistence in the face of adversity, and willingness to initiate behavior. Cox proportional hazards regression analyses were used to identify behavioral determinants of the time to RTW. Results Median time to RTW was 160 days. In the univariate analysis, all potential prognostic factors were significantly associated (P < 0.15) with time to RTW: work attitude, social support, and the three subscales of self-efficacy. The final multivariate model with time to RTW as the predicted outcome included work attitude, social support and willingness to expend effort in completing the behavior as significant predictive factors. Conclusions This prospective, longitudinal cohort-study showed that work attitude, social support and willingness to expend effort in completing the behavior are significantly associated with a shorter time to RTW in employees on long-term sickness absence. This provides suggestive evidence for the relevance of behavioral characteristics in the prediction of duration of sickness absence. It may be a promising approach to address the behavioral determinants in the development of interventions focusing on RTW in employees on long-term sick leave

    Hauora Māori - Māori health: a right to equal outcomes in primary care.

    Get PDF
    Background For more than a century, Māori have experienced poorer health than non-Māori. In 2019 an independent Tribunal found the Government had breached Te Tiriti o Waitangi by “failing to design and administer the current primary health care system to actively address persistent Māori health inequities”. Many Māori (44%) have unmet needs for primary care. Seven models of primary care were identified by the funders and the research team, including Māori-owned practices. We hypothesised patient health outcomes for Māori would differ between models of care. Methods Cross-sectional primary care data were analysed at 30 September 2018. National datasets were linked to general practices at patient level, to measure associations between practice characteristics and patient health outcomes. Primary outcomes: polypharmacy (≥ 55 years), HbA1c testing, child immunisations, ambulatory sensitive hospitalisations (0–14, 45–64 years) and emergency department attendances. Regressions include only Māori patients, across all models of care. Results A total of 660,752 Māori patients were enrolled in 924 practices with 124,854 in 65 Māori-owned practices. Māori practices had: no significant association with HbA1c testing, ambulatory sensitive hospitalisations or ED attendances, and a significant association with lower polypharmacy (3.7% points) and lower childhood immunisations (13.4% points). Māori practices had higher rates of cervical smear and cardiovascular risk assessment, lower rates of HbA1c tests, and more nurse (46%) and doctor (8%) time (FTE) with patients. The average Māori practice had 52% Māori patients compared to 12% across all practices. Māori practices enrolled a higher percentage of children and young people, five times more patients in high deprivation areas, and patients with more multimorbidity. More Māori patients lived rurally (21.5% vs 15%), with a greater distance to the nearest ED. Māori patients were more likely to be dispensed antibiotics or tramadol. Conclusions Māori practices are an expression of autonomy in the face of enduring health system failure. Apart from lower immunisation rates, health outcomes were not different from other models of care, despite patients having higher health risk profiles. Across all models, primary care need was unmet for many Māori, despite increased clinical input. Funding must support under-resourced Māori practices and ensure accountability for the health outcomes of Māori patients in all models of general practice.fals

    La prensa del Mahyar en Chile: la revista Laiazul (1945)

    Get PDF
    El presente artículo analiza la importancia de la prensa árabe en el proceso de modernización del Próximo Oriente (ss.XIX y XX), centrando su interés en la prensa de la emigración (Mahyar) de Latinoamérica. Las revistas chilenas El Triunfo (Surilandia, 1930) y Laiazul (Chile, 1945) del intelectual y poeta sirobrasileño Assis Féres, sirven de pretexto para aproximarnos al "arabismo iberoamericano" que ambas revistas propugnan, abriendo nuevas perspectivas de análisis en el discurso literario del Mahyar yanubi.This article analyzes the importance of the Arabic press in the modernization of the Middle East during the 19th and 20th centuries, with special emphasis on the emigrant (Mahyar) press in Latin America. The Chilean journals El Triunfo (Surilandia, 1930) and Laiazul (Chile, 1945) founded by the Sirio-Brazilian poet and intellectual Assis Féres, are examined for the “Ibero-American Arabism” that they defend, leading to new approaches to the analysis of the literary discourse of Mahyar yanûbî

    Exact boundary S-matrices of the supersymmetric sine-Gordon theory on a half line

    Get PDF
    Using the boundary Yang-Baxter equations and exact results on the bulk SS-matrices, we compute exact boundary scattering amplitudes of the supersymmetric sine-Gordon model with integrable boundary potentials.Comment: 15 pages, requires phyzzx.tex. Serious typo-errors are correcte
    corecore