835 research outputs found

    A Business Model Assessment and Evaluation Framework for City Logistics Collaborative Strategic Decision Support

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    Several City Logistics (CL) initiatives have emerged in the last two decades with the aim to reduce the negative externalities of freight distribution in urban areas. Such initiatives can be public and/or private but need to not break or impeach current operations efficiency so to not hinder their profitability. In order to provide business value to CL initiatives and thus fostering their long-term success, it is necessary to understand the decision-making of private companies operating in the urban freight ecosystem. This paper proposes an ex-ante assessment and evaluation framework built around the concept of an ecosystem business modelling that includes the decision-making by CL stakeholders. A theoretical framework previously developed is extended to evaluate a collaborative business model of an Urban Consolidation Centre (UCC). Cost-Benefit analysis (CBA is used estimate the impact of the business model configuration. Finally, research and practice implications are also addressed

    Compuestos polímero-metal con aplicaciones biomédicas

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    Este artículo describe la síntesis por plasma y la caracterización de compuestos polímero-metal con posibles aplicaciones como biomateriales. Se tomó particular atención en el tamaño de los agregados metálicos, en la rugosidad y en su hidrofilicidad. Se obtuvieron compuestos con conductividades eléctricas que van desde el intervalo correspondiente al de los semiconductores, hasta compuestos con conductividad metálica

    The Broad-Line and Narrow-Line Regions of the LINER NGC 4579

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    We report the discovery of an extremely broad H-alpha emission line in the LINER nucleus of NGC 4579. From ground-based observations, the galaxy was previously known to contain a Type 1 nucleus with a broad H-alpha line of FWHM = 2300 km/s and FWZI ~ 5000 km/s. New spectra obtained with the Hubble Space Telescope and a 0.2 arcsec-wide slit reveal an H-alpha component with FWZI ~ 18,000 km/s. The line is not obviously double-peaked, but it does possess shoulders on the red and blue sides which resemble the H-alpha profiles of double-peaked emitters such as NGC 4203 and NGC 4450. This similarity suggests that the very broad H-alpha profile in NGC 4579 may represent emission from an accretion disk. Three such objects have been found recently in two HST programs which have targeted a total of 30 galaxies, demonstrating that double-peaked or extremely broad-line emission in LINERs must be much more common than would be inferred from ground-based surveys. The ratio of the narrow [S II] 6716, 6731 lines shows a pronounced gradient indicating a steep rise in density toward the nucleus. The direct detection of a density gradient within the inner arcsecond of the narrow-line region confirms expectations from previous observations of linewidth-critical density correlations in several LINERs.Comment: 8 pages, includes 3 figures. To appear in The Astrophysical Journa

    La reforma de la formación inicial del profesorado de ciencias de secundaria: propuesta de un diseño del currículo basado en competencias

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    El principal objetivo de este trabajo es proponer un mecanismo de selección de competencias específicas para la formación inicial del profesorado de ciencias experimentales, contando para ello con distintas fuentes relevantes para dicha formación. Con tal fin hemos hecho uso de un procedimiento consistente en ir incorporando de forma crítica las competencias procedentes de las siguientes fuentes curriculares: los modelos de formación inicial del profesorado vigentes en la literatura educativa, el currículo actual de ciencias en la educación secundaria obligatoria en España, el Programa internacional de evaluación PISA, la opinión del profesorado en activo mediante una encuesta cuyos resultados más relevantes son mostrados, las concepciones epistemológicas del profesorado, la profesionalización docente y las demandas que genera y, finalmente, la dimensión social de la ciencia.The primary objective of this paper is to propose a mechanism for selecting specific competences for preservice science teacher training, referring to relevant sources for such training. To this end we have used an trans-disciplinary procedure consistent with incorporating critical competences from the following curricular sources: Models of current preservice teacher training in educational literature, the current curriculum of Science in Compulsory Secondary Education in Spain, the Program for International Student Assessment (PISA), the views of in-service secondary school teachers (through a survey whose most relevant results are given), teachers' epistemological conceptions, the professionalization of teaching and the demands it generates and, finally the social dimension of science

    OPserver: interactive online-computations of opacities and radiative accelerations

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    Codes to compute mean opacities and radiative accelerations for arbitrary chemical mixtures using the Opacity Project recently revised data have been restructured in a client--server architecture and transcribed as a subroutine library. This implementation increases efficiency in stellar modelling where element stratification due to diffusion processes is depth dependent, and thus requires repeated fast opacity reestimates. Three user modes are provided to fit different computing environments, namely a web browser, a local workstation and a distributed grid.Comment: 5 pages, 1 figur

    Monte Carlo simulation with time step quantification in terms of Langevin dynamics

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    For the description of thermally activated dynamics in systems of classical magnetic moments numerical methods are desirable. We consider a simple model for isolated magnetic particles in a uniform field with an oblique angle to the easy axis of the particles. For this model, a comparison of the Monte Carlo method with Langevin dynamics yields new insight in the interpretation of the Monte Carlo process, leading to the implementation of a new algorithm where the Monte Carlo step is time-quantified. The numeric results for the characteristic time of the magnetisation reversal are in excellent agreement with asymptotic solutions which itself are in agreement with the exact numerical results obtained from the Fokker-Planck equation for the Neel-Brown model.Comment: 5 pages, Revtex, 4 Figures include

    Laser-Beam-Patterned Topological Insulating States on Thin Semiconducting MoS2

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    Identifying the two-dimensional (2D) topological insulating (TI) state in new materials and its control are crucial aspects towards the development of voltage-controlled spintronic devices with low-power dissipation. Members of the 2D transition metal dichalcogenides have been recently predicted and experimentally reported as a new class of 2D TI materials, but in most cases edge conduction seems fragile and limited to the monolayer phase fabricated on specified substrates. Here, we realize the controlled patterning of the 1T′ phase embedded into the 2H phase of thin semiconducting molybdenum-disulfide by laser beam irradiation. Integer fractions of the quantum of resistance, the dependence on laser-irradiation conditions, magnetic field, and temperature, as well as the bulk gap observation by scanning tunneling spectroscopy and theoretical calculations indicate the presence of the quantum spin Hall phase in our patterned 1T′ phasesThe work carried out at Aoyama Gakuin University was partly supported by a grant for private universities and a Grant-in-Aid for Scientific Research (JP15K13277) awarded by MEXT. The work at the University of Tokyo was partly supported by Grantin-Aid for Scientific Research (JP17K05492, JP18H04218 and JP19H00652). J. J. P. and S. P. acknowledge Spanish MINECO through Grant No. FIS2016-80434-P, the Fundación Ramón Areces, the María de Maeztu Program for Units of Excellence in R&D (MDM-2014- 0377), the Comunidad Autónoma de Madrid through NANOMAGCOST Program, and the European Union Seventh Framework Programme under Grant Agreement No. 604391 Graphene Flagship. S. P. acknowledges the computer resources and assistance provided by the Centro de Computación Científica of the Universidad Autónoma de Madrid. S. P. was also supported by the VILLUM FONDEN via the Center of Excellence for Dirac Materials (Grant No. 11744). D. M. and E. G.-M. gratefully acknowledge support from the Graphene Flagship Graphene Core2 Contract No. 785219. E. G.-M also acknowledges IJCI-2017-32297 from Spanish MINECO/AE
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