43,101 research outputs found

    Room temperature ferromagnetic-like behavior in Mn-implanted and post-annealed InAs layers deposited by Molecular Beam Epitaxy

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    We report on the magnetic and structural properties of Ar and Mn implanted InAs epitaxial films grown on GaAs (100) by Molecular Beam Epitaxy (MBE) and the effect of Rapid Thermal Annealing (RTA) for 30 seconds at 750C. Channeling Particle Induced X- ray Emission (PIXE) experiments reveal that after Mn implantation almost all Mn atoms are subsbtitutional in the In-site of the InAs lattice, like in a diluted magnetic semiconductor (DMS). All of these samples show diamagnetic behavior. But, after RTA treatment the Mn-InAs films exhibit room-temperature magnetism. According to PIXE measurements the Mn atoms are no longer substitutional. When the same set of experiments were performed with As as implantation ion all of the layers present diamagnetism without exception. This indicates that the appearance of room-temperature ferromagnetic-like behavior in the Mn-InAs-RTA layer is not related to lattice disorder produce during implantation, but to a Mn reaction produced after a short thermal treatment. X-ray diffraction patterns (XRD) and Rutherford Back Scattering (RBS) measurements evidence the segregation of an oxygen deficient-MnO2 phase (nominally MnO1.94) in the Mn-InAs-RTA epitaxial layers which might be on the origin of room temperature ferromagnetic-like response observed.Comment: 16 pages, 5 figures. Acepted in J. Appl. Phy

    THE METHOD OF SIMULATED MAXIMUM LIKELIHOOD FOR THE ESTIMATON OF DYNAMIC ORDERED PROBIT: AN APPLICATION TO COUNTRY-RISK FOR NON-DEVELOPED COUNTRIES

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    This paper aims to give a detailed explanation of the econometric methodology necessary to estimate dynamic probit models with ordinal dependent variables. A typology of cases are established which appear when considering different choices of individual heterogeneity along with time correlation. To be able to estimate by maximum likelihood the models which come out of the different alternatives proposed, simulation techniques are used and put into practice by the GHK simulator and, in this way, estimators by simulated maximum likelihood are obtained. Finally, all the models described are used to measure and determine the macroeconomic factors which explain the ratings of country-risk in non-developed countries.Country risk, panel data, external debt, dynamic ordered probit

    ODESWS, A Semantic Web Service Development

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    ODE SWS is a development environment to design Semantic Web Services (SWS) at the knowledge level. ODE SWS describe the service following a problem-solving approach in which the SWS are modeled using tasks, to represent the SWS functional features, and methods, to describe the SWS internal structure. In this paper, we describe the ODE SWS architecture and the capabilities of its graphical interface, which enables users to design SWS independently of the semantic markup language used to represent them

    SWSDesigner: The Graphical Interface of ODESWS

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    ODESWS is a development environment to design Semantic Web Services (SWS) at the knowledge level. ODESWS describe the service following a problem-solving approach in which the SWS are modelled using tasks, to represent the SWS functional features, and methods, to describe the SWS internal structure. In this paper, we describe the ODESWS graphical interface (called SWSDesinger). This interface enables users to design SWS independently of the semantic markup language in which the service will be implemented, and once the design has been export the service to an SWS implementation languag

    A Framework for Design and Composition of Semantic Web Services

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    Semantic Web Services (SWS) are Web Services (WS) whose description is semantically enhanced with markup languages (e.g., OWL-S). This semantic description will enable external agents and programs to discover, compose and invoke SWSs. However, as a previous step to the specification of SWSs in a language, it must be designed at a conceptual level to guarantee its correctness and avoid inconsistencies among its internal components. In this paper, we present a framework for design and (semi) automatic composition of SWSs at a language-independent and knowledge level. This framework is based on a stack of ontologies that (1) describe the different parts of a SWS; and (2) contain a set of axioms that are really design rules to be verified by the ontology instances. Based on these ontologies, design and composition of SWSs can be viewed as the correct instantiation of the ontologies themselves. Once these instances have been created they will be exported to SWS languages such as OWL-S

    Combined analysis of the decays τKSπντ\tau^-\to K_S\pi^-\nu_\tau and τKηντ\tau^-\to K^-\eta\nu_\tau

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    In a combined study of the decay spectra of τKSπντ\tau^-\to K_S\pi^-\nu_\tau and τKηντ\tau^-\to K^-\eta\nu_\tau decays within a dispersive representation of the required form factors, we illustrate how the K(1410)K^*(1410) resonance parameters, defined through the pole position in the complex plane, can be extracted with improved precision as compared to previous studies. While we obtain a substantial improvement in the mass, the uncertainty in the width is only slightly reduced, with the findings MK=1304±17M_{K^{*\prime}}=1304 \pm 17\,MeV and ΓK=171±62\Gamma_{K^{*\prime}} = 171 \pm 62\,MeV. Further constraints on the width could result from updated analyses of the KπK\pi and/or KηK\eta spectra using the full Belle-I data sample. Prospects for Belle-II are also discussed. As the Kπ0K^-\pi^0 vector form factor enters the description of the decay τKηντ\tau^-\to K^-\eta\nu_\tau, we are in a position to investigate isospin violations in its parameters like the form factor slopes. In this respect also making available the spectrum of the transition τKπ0ντ\tau^-\to K^-\pi^0\nu_\tau would be extremely useful, as it would allow to study those isospin violations with much higher precision.Comment: 20 pages, 1figur
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