Harvesting technology and catch-to-biomass dependence: The case of small pelagic fish

This note deals with a harvesting model for a single stock fishery. In the case of small pelagic fish it seems reasonable to consider harvest functions depending nonlinearly on fishing effort and on fish stock. Empirical evidence about these fish species suggests that marginal catch does not necessarily react in a linear way to changes in fishing effort and fish stock levels. This is in contradiction with traditional fishery models where catch-to-input marginal productivities are normally assumed to be constant. While allowing for non linearities in both catch-to-effort and catch-to-stock parameters, this note extends the traditional analysis by focusing on the dependence of the stationary solutions upon the nonlinear catch-to-biomass parameter. Given the emphasis on the case of small pelagic fish, the analysis considers positive but small values for the catch-to-stock parameter.small pelagic fisheries, harvesting functions, Cobb-Douglas production function, optimal control, maximum principle.

A multi-method proposal to study the public space in the scale of neighborhood from a transactional approach

La perspectiva transaccional resulta muy atractiva para analizar y actuar sobre el espacio público en la escala de barrio. Sin embargo, las diferencias metodológicas y de lenguaje entre las distintas disciplinas implicadas lo hacen bastante complejo. En este artículo se presenta una estrategia cualitativa de análisis multimétodo, como una propuesta que integra los diferentes lenguajes gráficos y textuales que dominan en los análisis unidisciplinares del espacio público, a través de un trabajo de espacialización gráfica de resultados. Se triangularon diversas técnicas y se sometieron a un mismo proceso analítico (Grounded Theory), lo que apoyado por los programas de procesamiento Atlas/ti y Arcgis hicieron posible ligar aspectos gráficos (mapas e imágenes) con observaciones de los investigadores y narraciones biográficas de los participantes, asociando de esta manera, espacios físicos concretos con la evolución y construcción de significados y usos espaciales.The transactional perspective is very attractive in order to analyze and intervene in public space on neighborhood scale. However, language and methodological differences between the various disciplines involved make it quite complex. In this article we present a multi-method qualitative strategy of analysis, integrating various results graphically, in an attempt to bring together the graphic and textual languages that dominate single-discipline approaches of public space. Diverse techniques were triangulated and underwent the same analytical process (Grounded Theory), supported by Atlas / ti and Arcgis software. Using this techniques it was possible to link graphic aspects (maps and images) with comments from researchers and biographical accounts of the participants. So, specific physical spaces were associated with the development and construction of spatial meanings and uses

Parametric Instability in Mathieu Equation for Interaction P-S Waves

We propose an experimental study of parametric resonance between P-waves and S-waves, which can be used to describe various nonlinear phenomena qualitatively and to obtain bifurcation diagrams quantitatively. It is based on an electronic circuit and is easy to design. We show that it is a good simulation of parametric phenomena, and our results are in good agreement with theoretical predictions. In particular, it may be used to study the influence of pump P waves on the instability's threshold and amplitude of S waves

A Seismic Channel Model: The San Ramon Fault

Although seismic waves have been studied for many years, their soliton structure has only recently studied. Deformation solitons propagate along earthquake faults and can induce large earthquakes. Rotation solitons are generated in earthquake sources and propagate throughout the Earth. The conclusion to be reached from our paper is that the research on seismic solitons is essential for investigating the propagation of seismic waves and helps understand mechanisms triggering earthquakes. This paper discusses the development of elastodynamics equations similar to Maxwell's equations in a chiral -mode which is applied to a seismic channel, which is dispersive and nonlinear. The chirality is described in terms of the formalism proposed by Born-Fedorov. The nonlinearity is Kerr-type, and dispersion of the medium is taken into account explicitly through the Taylor series expansion. Through numerical calculations these theoretical results allow us analyze the soliton propagation of S-seismic pulses which can induce strong earthquakes. The numerical calculation is applied to the San Ramon Fault localized in Santiago City, Chile which is a seismically active fault that is a main element to be considered in any study on seismic hazard assessment for this city

Metodología para aplicar el Bechmarking financiero a las empresas del sector Metalmecánico en Risaralda. Un caso de estudio

La propuesta de investigación "METODOLOGIA PARA APLICAR EL BECHMARKING FINANCIERO A LAS EMPRESAS DEL SECTOR METALMECANICO EN RISARALDA - UN CASO DE ESTUDIO", pretende determinar las características de la gestión de las empresas dedicadas a la actividad metalmecánica con un enfoque financiero. Los empresarios del departamento de Risaralda y el soporte de información estadística del Dane, dejan entrever el futuro promisorio de este sub sector de la economía para el departamento. Además, de conocer los elementos claves en la gestión de las empresas dedicadas a la metalmecánica, se propone un procedimiento de gestión empresarial que oriente y facilite la toma de la dirección no solo a este tipo de empresas sino, en general a cualquier institución. Entre los elementos a considerar para la caracterización se tiene la estructura de la empresa, el estilo gerencial, métodos para la toma de decisiones, el direccionamiento estratégico, el plan de acciones, el análisis de la competitividad y acciones orientadas al benchmarking que aseguren una permanencia exitosa de estas empresas. Para desarrollar la metodología a proponer y que se expondrá a lo largo del documento se tomará una empresa del sector metalmecánico de Risaralda como estudio de caso, con las siguientes etapas: Analizar la visión y la misión de la organización, realizar un análisis estratégico, medir el nivel de competitividad, Aplicar un análisis envolvente de datos (DEA), para establecer el benchmarking a realizar por parte de la empresa. Por ultimo llegar a unas conclusiones y recomendaciones del trabajo de investigación desarrollado.The research proposal "BECHMARKING METHODOLOGY TO IMPLEMENT THE FINANCIAL SECTOR TO BUSINESSES IN METALMECHANICAL RISARALDA - A CASE STUDY", aimed at determining the characteristics of the management of enterprises involved in the metalworking activity with a financial approach. Entrepreneurs of the department of Risaralda and statistical information medium of Dane, show the promising future of this sub sector of the economy for the department. In addition, to know the key elements in the management of companies involved in metalworking, a business management procedure to guide and facilitate the taking of the leadership not only to such companies but, in general to any institution. Among the items to consider for the characterization is: the structure of the company, the management style, methods for decision making, addressing strategic plan of action, the analysis of competitiveness and actions aimed at ensuring a benchmarking permanence of these successful companies. To develop the methodology to propose and which will be shown throughout the document will take a metal company in the sector of Risaralda as a case study, with the following steps: Analyze the vision and mission of the organization, to conduct strategic analysis, measure the level of competitiveness, implement a data envelopment analysis (DEA) to establish benchmarking to conduct on the part of the company. Finally arriving at conclusions and recommendations of the research developed

Resolving the clumpy circumstellar environment of the B[e] supergiant LHA 120-S 35

Context. B[e] supergiants are massive post-main-sequence stars, surrounded by a complex circumstellar environment where moleculesand dust can survive. The shape in which the material is distributed around these objects and its dynamics as well as the mechanismsthat give rise to these structures are not well understood.Aims. The aim of this work is to deepen our knowledge of the structure and kinematics of the circumstellar disc of the B[e] supergiantLHA 120-S 35.Methods. High-resolution optical spectra were obtained in three different years. Forbidden emission lines, that contribute to trace thedisc at different distances from the star, are modelled in order to determine the kinematical properties of their line-forming regions,assuming Keplerian rotation. In addition, we used low-resolution near-infrared spectra to explore the variability of molecular emission.Results. LHA 120-S 35 displays an evident spectral variability in both optical and infrared regions. The P-Cygni line profiles of H i,as well as those of Fe ii and O i, suggest the presence of a strong bipolar clumped wind. We distinguish density enhancements in theP-Cygni absorption component of the first Balmer lines, which show variations in both velocity and strength. The P-Cygni profileemission component is double-peaked, indicating the presence of a rotating circumstellar disc surrounding the star. We also observeline-profile variations in the permitted and forbidden features of Fe ii and O i. In the infrared, we detect variations in the intensity ofthe H i emission lines as well as in the emission of the CO band-heads. Moreover, we find that the profiles of each [Ca ii] and [O i]emission lines contain contributions from spatially different (complete or partial) rings. Globally, we find evidence of detached multi-ring structures, revealing density variations along the disc. We identify an inner ring, with sharp edge, where [Ca ii] and [O i] linesshare their forming region with the CO molecular bands. The outermost regions show a complex structure, outlined by fragmentedclumps or partial-ring features of Ca ii and O i. Additionally, we observe variations in the profiles of the only visible absorptionfeatures, the He i lines.Conclusions. We suggest that LHA 120-S 35 has passed through the red-supergiant (RSG) phase and evolves back bluewards in theHertzsprung-Russell diagram. In this scenario, the formation of the complex circumstellar structure could be the result of the wind-wind interactions of the post-RSG wind with the previously ejected material from the RSG. The accumulation of material in thecircumstellar environment could be attributed to enhanced mass-loss, probably triggered by stellar pulsations. However, the presenceof a binary companion can not be excluded. Finally, we find that LHA 120-S 35 is the third B[e] supergiant belonging to a youngstellar cluster.Fil: Torres, Andrea Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Cidale, Lydia Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Kraus, M.. Tartu Observatory, Estonia; Estonia. Astronomický Ústav, Akademie Ved Ceské Republiky; República ChecaFil: Arias, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Barba, Rodolfo Hector. Universidad de La Serena; ChileFil: Maravelias, G.. Universidad de Valparaiso; Chile. Astronomický Ústav, Akademie Ved Ceské Republiky; República ChecaFil: Borges Fernandes, M.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; Brasi

Análisis de eficiencia técnica en las Entidades Federativas de México 1988-2013

El principal interés en desarrollar este trabajo es estudiar la eficiencia técnica para identificar si existe potencial para incrementar la producción, sin necesidad de incrementar la cantidad de factores de la producción en las entidades federativas de

Una propuesta multimétodo para un abordaje transaccional del espacio público en la escala de barrio

La perspectiva transaccional resulta muy atractiva para analizar y actuar sobre el espacio público en la escala de barrio. Sin embargo, las diferencias metodológicas y de lenguaje entre las distintas disciplinas implicadas lo hacen bastante complejo. En este artículo se presenta una estrategia cualitativa de análisis multimétodo, como una propuesta que integra los diferentes lenguajes gráficos y textuales que dominan en los análisis unidisciplinares del espacio público, a través de un trabajo de espacialización gráfica de resultados. Se triangularon diversas técnicas y se sometieron a un mismo proceso analítico (Grounded Theory), lo que apoyado por los programas de procesamiento Atlas/ti y Arcgis hicieron posible ligar aspectos gráficos (mapas e imágenes) con observaciones de los investigadores y narraciones biográficas de los participantes, asociando de esta manera, espacios físicos concretos con la evolución y construcción de significados y usos espaciales.The transactional perspective is very attractive in order to analyze and intervene in public space on neighborhood scale. However, language and methodological differences between the various disciplines involved make it quite complex. In this article we present a multi-method qualitative strategy of analysis, integrating various results graphically, in an attempt to bring together the graphic and textual languages that dominate single-discipline approaches of public space. Diverse techniques were triangulated and underwent the same analytical process (Grounded Theory), supported by Atlas / ti and Arcgis software. Using this techniques it was possible to link graphic aspects (maps and images) with comments from researchers and biographical accounts of the participants. So, specific physical spaces were associated with the development and construction of spatial meanings and uses

Seguridad alimentaria: seguridad nacional

Seguridad alimentaria: seguridad nacional es un libro que trata sobre el deterioro del abasto alimentario en nuestro país, y advierte sobre los posibles riesgos a que puede llevar la profundización de las asimetrías sociales y regionales, aunado al incremento de la pobreza. En esta obra se plantea el riesgo que implica para la seguridad nacional la carencia de alimentos porque se pueden generar situaciones de tensión y conflicto, sobre todo, si no se atiende esta situación con medidas políticas y económicas que corrijan los problemas estructurales de la agricultura mexicana