3,850 research outputs found
Droplets of trapped quantum dipolar bosons
Strongly interacting systems of dipolar bosons in three dimensions confined by harmonic traps are analyzed using the exact path integral ground-state Monte Carlo method. By adding a repulsive two-body potential, we find a narrow window of interaction parameters leading to stable ground-state configurations of droplets in a crystalline arrangement. We find that this effect is entirely due to the interaction present in the Hamiltonian without resorting to additional stabilizing mechanisms or specific three-body forces. We analyze the number of droplets formed in terms of the Hamiltonian parameters, relate them to the corresponding s-wave scattering length, and discuss a simple scaling model for the density profiles. Our results are in qualitative agreement with recent experiments showing a quantum Rosensweig instability in trapped Dy atoms.Peer ReviewedPostprint (published version
Determinant factors of pull up performance in trainedathletes
Aim: to investigate the relationship among pull up and lat pull exercises and differentanthropometric dimensions in trained athletes. Methods: twenty-five males were evaluated for maximum number of pull ups, one-repetitionmaximum lat pull (1RM Lat Pull), lat pull repetitions at 80% 1RM (Lat Pull at 80% 1RM), latpull repetitions at a load equivalent to body mass (Lat Pull at BM-load), and differentanthropometric variables. Furthermore, the subjects were divided in higher (HPG, n = 12) andlower pull up performance (LPG, n = 13) to compare the differences in the variables analyzedbetween both levels. Results: pull ups were significantly correlated with Lat Pull at BM-load (r = .62, P < .01) butneither with 1RM Lat Pull (r = .09) nor with Lat Pull at 80% 1RM (r = -.15). Pull ups showed asignificant (P < .05) negative relationship with body mass (BM, r = -.55), lean body mass(LBM, r = -.51), and fat mass (FM, r = -.52), while BM and LBM were significantly correlatedwith 1RM Lat Pull (r = .55, P < .05). HPG showed significantly (P < .05) lower BM (0/3/97%),FM (1/3/97%) and LBM (1/4/95%) than LPG. Furthermore, HPG attained significantly (P < .05– .001) greater performance in Lat Pull at BM-load (100/0/0%) and 1RM Lat Pull•BM-1(96/3/2%) than LPG. Conclusion: these findings suggest that pull up and lat pull exercises have common elements.Moreover, the anthropometric dimensions seem to influence differently on both exercises,depending on the strength indicator evaluated
Can output explain the predictability and volatility of stock returns?.
This paper examines whether a general equilibrium asset pricing model can explain two important empirical regularities of asset returns, extensively documented in the literature: (i) returns can be predicted by a set of macro variables, and (ii) returns are very volatile. We derive a closed-form solution for the equilibrium asset pricing model that relates asset returns to output by using an approximate method proposed by Campbell (Am. Econ. Rev. 83 (1993) 487) and Restoy and Weil (W.P. NBER, No. 6611 (1998)). We obtain evidence on eight OECD economies using both quarterly and annual observations. Equilibrium models seem to fin fewer difficultie in explaining the volatility of returns than their predictability for general output processes. In the case of the US, the observed predictability and volatility of asset returns, for annual frequencies, are broadly compatible with the predictions of equilibrium models for a reasonableGeneralized isoelastic preferences; Asset returns; Real activity; Volatility;
Análisis de las alternativas terapéuticas del trastorno de pánico en atención primaria mediante un árbol de decisión
ResumenObjetivoAnalizar las diferentes estrategias terapéuticas para el trastorno de pánico, de forma que se facilite la toma de decisiones conjunta entre el profesional sanitario de atención primaria y el paciente.DiseñoAnálisis cuantitativo por árbol de decisión.Fuentes de datosRevisión del período de 1990 a 2008 en Medline, Embase, librería Cochrane Plus y Tripdatabase. Términos utilizados: “panic disorder”, “psychotherapy” y “drug therapy”.Selección de estudiosSumarios de pruebas, revisiones sistemáticas, metaanálisis y guías de práctica clínica.Extracción de datosa) Elaboración de un árbol de decisión con una única opción terapéutica; b) idéntico procedimiento con 2 opciones terapéuticas secuenciales, y c) análisis de sensibilidad para valorar la consistencia del modelo.ResultadosLa terapia cognitivo-conductual (TCC) obtiene la utilidad media esperada (UME) más elevada (UME = 0,58), seguida de los antidepresivos, inhibidores selectivos de la recaptación de serotonina (ISRS) (UME = 0,53) y de los antidepresivos tricíclicos (UME = 0,44). La secuencia TCC seguida de ISRS es la que obtiene una UME más alta (0,62). EL análisis de sensibilidad indica que el modelo no es suficientemente consistente.ConclusionesLa TCC en monoterapia o seguida de ISRS como estrategia secuencial serían las opciones terapéuticas con una mayor utilidad. Los resultados no son suficientemente consistentes, puesto que pueden variar claramente con la modificación de las variables más importantes dentro de unos rangos razonables.AbstractAimsTo analyse the different therapeutic alternatives for Panic Disorders to make it easier to make collaborative treatment decisions between patients and doctors in a Primary Care setting.DesignQuantitative analysis by a decision tree.Data SourcesTime period reviewed; 1990–2008 in Med-line, Embase, Cochrane-plus Library and Tripdatabase. Terms used “panic disorder”, “psychotherapy” and “drug therapy”.MethodsI) A decision tree was prepared with only one therapeutic option in each arm; II) The same procedure with two sequential therapeutic options; III) Sensitivity analysis to test the robustness of the model.Study selectionEvidence summary, systematic reviews, meta-analysis and clinical guidelines.ResultsCognitive-Behavioural Therapy (CBT) obtains the highest usefulness (UME=0.58), followed by the Selective serotonin reuptake inhibitors (SSRI) (UME=0.53) and by the tricyclic antidepressants (UME=0.44). CBT followed by SSRI is the therapeutic sequence with the highest usefulness (0.62). The sensitivity analysis suggests the model is not robust enough.ConclusionsThe CBT in monotherapy or followed by SSRI in a sequential strategy would be the options with the highest usefulness. The results are not robust enough because they can clearly vary with changes in the most important variables in a reasonable range
A geometrical view of scalar modulation instability in optical fibers
Full models of scalar modulation instability (MI) in optical fibers available in the literature usually involve complex formulations. In this paper, we present a novel approach to the analysis of MI in optical fibers by means of a simple geometrical description in the power vs. frequency plane. This formulation allows to relate the shape of the MI gain to any arbitrary dispersion profile of the medium, thus providing a simple insight. As a result, we derive a straightforward explanation of the non-trivial dependence of the cutoff power on high-order dispersion and derive explicitly the power that maximizes the gain. Our approach puts forth a tool to synthesize a desired MI gain with the potential application to a number of parametric-amplification and supercontinuum-generation devices whose initial-stage dynamics rely upon modulation instability.Fil: Hernandez, Santiago Martin. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Fierens, Pablo Ignacio. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Bonetti, Juan Ignacio. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Sánchez, Alfredo Daniel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Grosz, Diego Fernando. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Instituto Tecnológico de Buenos Aires; Argentin
Onyx: describing emotions on the web of data
There are several different standardised and widespread formats to represent emotions. However, there is no standard semantic model yet. This paper presents a new ontology, called Onyx, that aims to become such a standard while adding concepts from the latest Semantic Web models. In particular, the ontology focuses on the representation of Emotion Analysis results. But the model is abstract and inherits from previous standards and formats. It can thus be used as a reference representation of emotions in any future application or ontology. To prove this, we have translated resources from EmotionML representation to Onyx. We also present several ways in which developers could benefit from using this ontology instead of an ad-hoc presentation. Our ultimate goal is to foster the use of semantic technologies for emotion Analysis while following the Linked Data ideals
Valoración de la empresa de telecomunicaciones de Bogotá S.A. E.S.P.
El objetivo de la investigación es estimar un valor razonable para la Empresa de Telecomunicaciones de Bogotá S.A. E.S.P. Para alcanzar este objetivo, se realizó una revisión al entorno sectorial de la compañía y se analizó su información contable y financiera correspondiente al periodo 2006 a 2011. Con la información recolectada, se procedió a la elaboración de los supuestos de valoración. El valor de la empresa se estimó por el método del flujo de caja libre descontado. Se concluye que, a la fecha de elaboración de la investigación, se presenta una desviación entre el valor fundamental de la empresa y su precio de mercado. Se presume que, los agentes del mercado han descontado significativamente la incertidumbre sobre el futuro de la empresa.118 p.The research's primary objective is to estimate a reasonable value for Empresa de Telecomunicaciones de Bogotá S.A. E.S.P. In order to reach this objective, a revision of the company's sector environment and it's financial statements from 2005 to 2011 has been done. With the collected information, we proceeded to elaborate the valuation's premises. The company's value has been estimated by the discounted cash flow method. In conclusion, as to the date of the research, it shows a deviation between the company's fundamental value and it's market price.Contenido parcial: Valoración de empresas -- Métodos de valoración de empresas -- Valoración de empresas por descuento de flujos de fondos -- Análisis sectorial -- Diagnóstico financiero -- Valoración de la empresa -- Supuestos generales de valoración -- Modelación del valor de continuidad -- Estructura de capital y cuadre del balance proyectado
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