6,585 research outputs found

    The three-dimensional carrier-envelope-phase map of focused few-cycle pulsed Gaussian beams

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    We derive an analytical expression that describes the complete three-dimensional carrier-envelope phase (CEP) distribution of in the focal volume of ultrashort pulsed Gaussian beams focused by spherical mirrors or lenses. The focal CEP map depends on the so-called factor gg specifying the frequency-dependence of the beam width of the source few-cycle pulse, on its chirp and on the small chromatic aberration introduced by a lens without appreciably distorting or broadening the few-cycle pulse. We show how to tailor the CEP map of mirror-focused and lens-focused few-cycle pulses in order to produce negligible transversal and axial CEP variations in specific regions of the focal volume for phase-sensitive interactions of light with matter taking place in a volume or on a surface. We propose a quasi-achromatic doublet lens that can implement in practice these tailored CEP distributions.Comment: 9 pages, 6 figure

    On the Universality of the Entropy-Area Relation

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    We present an argument that, for a large class of possible dynamics, a canonical quantization of gravity will satisfy the Bekenstein-Hawking entropy-area relation. This result holds for temperatures low compared to the Planck temperature and for boundaries with areas large compared to Planck area. We also relate our description, in terms of a grand canonical ensemble, to previous geometric entropy calculations using area ensembles.Comment: 6 page

    Mixmaster quantum cosmology in terms of physical dynamics

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    An approach to quantum cosmology, relying on strengths of both canonical and path integral formalisms, is applied to the cosmological model, Bianchi type IX. Physical quantum states are constructed on the maximal slice of the cosmological history. A path integral is derived which evolves observables off the maximal slice. This result is compared a path integral propagator derived earlier with conventional Faddeev-Poppov gauge fixing

    Facilitating a Whole-Life Approach to Career Development: The Role of Organizational Leadership

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    This article focuses on the whole-life approach to career development. A review of the ways in which career paths have been conceptualized over time demonstrates that increasing consideration has been given to nonwork factors (i.e., personal life and family life) in defining careers. The whole-life perspective on career development acknowledges that employees are striving for opportunities for professional development as well as individualized work-life balance, which changes over the life course. Although the careers literature has emphasized interorganizational mobility as the primary mechanism for achieving these goals, whole-life career development can also be achieved within a single organization when organizational leadership is willing to address employees\u27 work-family needs. This article addresses how leaders across organizational levels, including executive-level leaders and first-line supervisors, can foster whole-life career development. In addition to beneficial outcomes for employees, potential competitive advantages for organizations implementing the whole-life approach to career development are discussed

    On Modified Dispersion Relations and the Chandrasekhar Mass Limit

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    Modified dispersion relations from effective field theory are shown to alter the Chandrasekhar mass limit. At exceptionally high densities, the modifications affect the pressure of a degenerate electron gas and can increase or decrease the mass limit, depending on the sign of the modifications. These changes to the mass limit are unlikely to be relevant for the astrophysics of white dwarf or neutron stars due to well-known dynamical instabilities that occur at lower densities. Generalizations to frameworks other than effective field theory are discussed.Comment: 14 pages, 2 figures; v2: version accepted for publication, minor changes; v3: note added correcting comments on the applicability of the calculation to the DSR context, references added, results unchange

    Clinicians’ perceptions of Norwegian women’s experiences of infertility diseases

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    Background: Norway has one of the best health systems in the world. However, it has a low birth rate, which decreased by 21.2% between 2009 and 2018, and one of the highest rates of infertility prevalence. The aim of this study is to understand how Norwegian doctors perceive female infertility diseases, namely those that are more difficult to diagnose and to treat, and that are more common in their practice. Method: Descriptive qualitative study was conducted with gynecologists and general practitioners. The sample resulted from the establishment of five criteria and on the doctors’ acceptance to participate in this study. Our sample comprised thirteen highly qualified and experienced doctors. Qualitative content analysis was the method chosen to analyze the collected data. Results: Clinical diseases (polycystic ovary syndrome, endometriosis and vulvodynia) and consequences of these diseases were the pinpointed themes. These led to a set of sub-themes: the main symptoms and the treatment of the diseases, from the perspective of both women and doctors (stigmatization, disturbances in women’s daily life, diagnostic delay, and governmental support). Conclusions: The three most relevant disorders mentioned were polycystic ovary syndrome, endometriosis and vulvodynia. These diseases cause several impacts on the lives of women, because they feel stigmatized and limited in their daily life and sexuality, and the diagnosis of these diseases takes too much time. Governments should better redistribute the financing of women’s health and allocate resources to specialized centers.info:eu-repo/semantics/publishedVersio

    GINA - A Polarized Neutron Reflectometer at the Budapest Neutron Centre

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    The setup, capabilities and operation parameters of the neutron reflectometer GINA, the recently installed "Grazing Incidence Neutron Apparatus" at the Budapest Neutron Centre, are introduced. GINA, a dance-floor-type, constant-energy, angle-dispersive reflectometer is equipped with a 2D position-sensitive detector to study specular and off-specular scattering. Wavelength options between 3.2 and 5.7 {\AA} are available for unpolarized and polarized neutrons. Spin polarization and analysis are achieved by magnetized transmission supermirrors and radio-frequency adiabatic spin flippers. As a result of vertical focusing by the five-element (pyrolytic graphite) monochromator the reflected intensity from a 20x20 mm sample has doubled. GINA is dedicated to studies of magnetic films and heterostructures, but unpolarized options for non-magnetic films, membranes and other surfaces are also provided. Shortly after its startup, reflectivity values as low as 3x10-5 have been measured on the instrument. The facility is now open for the international user community, but its development is continuing mainly to establish new sample environment options, the spin analysis of off-specularly scattered radiation and further decrease of the background

    Prospecting for an HIV Vaccine

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    Human immunodeficiency virus (HIV) sets several challenges for the development of a preventative HIV vaccine. Predictable, protective natural immunity against HIV does not occur and so unlike most other diseases for which vaccines exist, there are few guideposts from natural infection. Nonetheless, six vaccine efficacy trials have occurred. One in particular, the Thai trial called RV144, showed partial protective efficacy and potential ways ahead to a better vaccine approach. This coupled with other lessons from studies of acute infections as well as an increasingly complex knowledge of HIV-related vaccine immunology bring hope that a vaccine solution might be reached for this pervasive and deadly pandemic
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