1,521 research outputs found

    Quasi-Exact Solvability and the direct approach to invariant subspaces

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    We propose a more direct approach to constructing differential operators that preserve polynomial subspaces than the one based on considering elements of the enveloping algebra of sl(2). This approach is used here to construct new exactly solvable and quasi-exactly solvable quantum Hamiltonians on the line which are not Lie-algebraic. It is also applied to generate potentials with multiple algebraic sectors. We discuss two illustrative examples of these two applications: an interesting generalization of the Lam\'e potential which posses four algebraic sectors, and a quasi-exactly solvable deformation of the Morse potential which is not Lie-algebraic.Comment: 17 pages, 3 figure

    Hospital general con unidad cardiovascular en la ciudad de Ibagu?

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    60 p. Recurso Electr?nicoEl hospital general con unidad cardiovascular localizado en la zona de expansi?n dispuesta por el plan de ordenamiento territorial (POT), es un proyecto que minimiza la crisis de salud por medio de infraestructura y cuerpo m?dico en la ciudad o departamento. Es producto al d?ficit de equipamientos de salud en Ibagu? y su prioridad o enfoque en las afecciones cardiovasculares, ya que es la principal causa de muerte en el Tolima. Est? compuesto por un juego de cinco vol?menes articulados, que concentran siete niveles; cada volumen adopta una funci?n espec?fica, lo mismo para cada nivel, donde se organizan las unidades puntuales del hospital; dando como resultado espacial, 15 consultorios m?dicos, una unidad de imagenologia general y otra cardiaca, la unidad de laboratorios y terapia, estos ubicados en el segundo nivel; en el tercer piso opera la unidad de quir?fanos y salas de recuperaci?n, el cuarto nivel la unidad de cuidados intensivos y del quinto al s?ptimo, la unidad de hospitalizaci?n. Continuo al volumen principal se ubica el volumen de servicios complementarios, dirigido a la pedagog?a m?dica, ?reas de comercio y zonas de estar. La propuesta ampliar?a la cobertura de salud de la ciudad y departamental, mejorando la calidad de vida para una falencia vigente; adem?s genera grandes oportunidades de orden f?sico, social, econ?mico y ambiental para un sector de futuro desarrollo de Ibagu?.The general hospital with a cardiovascular unit located in the expansion zone provided by the Territorial Order Plan (TOP) is a project that minimizes the health crisis through the infrastructure and the medical staff in the city or department. The project is a product of the deficit of health facilities in Ibagu?, Tolima and its priority are cardiovascular diseases, since it is the main cause of death in the region. It is composed of a set of five articulated volumes, which concentrate seven levels; each volume adopts a specific function, each level as well, where the specific units of the hospital are organized. As a result, in the second floor there are 15 medical clinics, a general imaging unit, a cardiac unit, laboratory and therapy unit. While in the third, there are the surgeon and recovery rooms. In the fourth there is the intensive care unit, and from the fifth to seventh, the hospitalization unit. The unit of complementary services is located next to the main unit; it is focused on medical pedagogy, areas of commerce, and living areas. The proposal will enhance the health coverage in the city and the department, improving the life quality. In addition, it generates great opportunities of physical, social, economic, and environmental order for a sector of future development in Ibagu?. Key words: health, hospital, unit, cardiology

    Errors and Artefacts in Agent-Based Modelling

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    The objectives of this paper are to define and classify different types of errors and artefacts that can appear in the process of developing an agent-based model, and to propose activities aimed at avoiding them during the model construction and testing phases. To do this in a structured way, we review the main concepts of the process of developing such a model – establishing a general framework that summarises the process of designing, implementing, and using agent-based models. Within this framework we identify the various stages where different types of errors and artefacts may appear. Finally we propose activities that could be used to detect (and hence eliminate) each type of error or artefact.Verification, Replication, Artefact, Error, Agent-Based Modelling, Modelling Roles

    Biologically active Phytophthora mating hormone prepared by catalytic asymmetric total synthesis

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    A Phytophthora mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained two of the 16 possible stereoisomers of Phytophthora hormone α1. These synthetic stereoisomers induced the formation of sexual spores (oospores) in A2 mating type strains of three heterothallic Phytophthora species, P. infestans, P. capsici, and P. nicotianae but not in A1 mating type strains. The response was concentration-dependent, and the oospores were viable. These results demonstrate that the biological activity of the synthetic hormone resembles that of the natural hormone α1. Mating hormones are essential components in the sexual life cycle of a variety of organisms. For plant pathogens like Phytophthora, sexual reproduction is important as a source of genetic variation. Moreover, the thick-walled oospores are the most durable propagules that can survive harsh environmental conditions. Sexual reproduction can thus greatly affect disease epidemics. The availability of synthetic compounds mimicking the activity of Phytophthora mating hormone will be instrumental for further unravelling sexual reproduction in this important group of plant pathogens.

    Oscillatons revisited

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    In this paper, we study some interesting properties of a spherically symmetric oscillating soliton star made of a real time-dependent scalar field which is called an oscillaton. The known final configuration of an oscillaton consists of a stationary stage in which the scalar field and the metric coefficients oscillate in time if the scalar potential is quadratic. The differential equations that arise in the simplest approximation, that of coherent scalar oscillations, are presented for a quadratic scalar potential. This allows us to take a closer look at the interesting properties of these oscillating objects. The leading terms of the solutions considering a quartic and a cosh scalar potentials are worked in the so called stationary limit procedure. This procedure reveals the form in which oscillatons and boson stars may be related and useful information about oscillatons is obtained from the known results of boson stars. Oscillatons could compete with boson stars as interesting astrophysical objects, since they would be predicted by scalar field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version published in Classical and Quantum Gravit

    Galactic Collapse of Scalar Field Dark Matter

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    We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations and phenomenological studies in galaxies.Comment: 4 pages, 3 figue

    Improving small area estimation by combining surveys : new perspectives in regional statistics

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    A national survey designed for estimating a specific population quantity is sometimes used for estimation of this quantity also for a small area, such as a province. Budget constraints do not allow a greater sample size for the small area, and so other means of improving estimation have to be devised. We investigate such methods and assess them by a Monte Carlo study. We explore how a complementary survey can be exploited in small area estimation. We use the context of the Spanish Labour Force Survey (EPA) and the Barometer in Spain for our study

    Perturbative evolution of particle orbits around Kerr black holes: time domain calculation

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    Treating the Teukolsky perturbation equation numerically as a 2+1 PDE and smearing the singularities in the particle source term by the use of narrow Gaussian distributions, we have been able to reproduce earlier results for equatorial circular orbits that were computed using the frequency domain formalism. A time domain prescription for a more general evolution of nearly geodesic orbits under the effects of radiation reaction is presented. This approach can be useful when tackling the more realistic problem of a stellar-mass black hole moving on a generic orbit around a supermassive black hole under the influence of radiation reaction forces.Comment: 8 pages, 5 figures, problems with references and double-printing fixe

    FKF1 conveys timing information for CONSTANS stabilization in photoperiodic flowering

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    Plants use day-length information to coordinate flowering time with the appropriate season to maximize reproduction. In Arabidopsis, the long-day specific expression of CONSTANS (CO) protein is crucial for flowering induction. Although light signaling regulates CO protein stability, the mechanism by which CO is stabilized in the long-day afternoon has remained elusive. Here we demonstrate that FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) protein stabilizes CO protein in the afternoon in long days. FKF1 interacts with CO through its LOV domain, and blue light enhances this interaction. In addition, FKF1 simultaneously removes CYCLING DOF FACTOR 1 (CDF1) that represses CO and FLOWERING LOCUS T (FT) transcription. Together with CO transcriptional regulation, FKF1 protein controls robust FT mRNA induction through multiple feedforward mechanisms that accurately control flowering timing

    Interferon β-1a in relapsing multiple sclerosis: four-year extension of the European IFNβ-1a Dose-C omparison Study

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    Background: Multiple sclerosis (MS) is a chronic disease requiring long-term monitoring of treatment. Objective: To assess the four-year clinical efficacy of intramuscular (IM) IFNb-1a in patients with relapsing MS from the European IFNb-1a Dose-C omparison Study. Methods: Patients who completed 36 months of treatment (Part 1) of the European IFNb-1a Dose-C omparison Study were given the option to continue double-blind treatment with IFNb-1a 30 mcg or 60 mcg IM once weekly (Part 2). Analyses of 48-month data were performed on sustained disability progression, relapses, and neutralizing antibody (NA b) formation. Results: O f 608/802 subjects who completed 36 months of treatment, 493 subjects continued treatment and 446 completed 48 months of treatment and follow-up. IFNb-1a 30 mcg and 60 mcg IM once weekly were equally effective for up to 48 months. There were no significant differences between doses over 48 months on any of the clinical endpoints, including rate of disability progression, cumulative percentage of patients who progressed (48 and 43, respectively), and annual relapse rates; relapses tended to decrease over 48 months. The incidence of patients who were positive for NAbs at any time during the study was low in both treatment groups. Conclusion: C ompared with 60-mcg IM IFNb-1a once weekly, a dose of 30 mcg IM IFNb-1a once weekly maintains the same clinical efficacy over four years
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