Ichthyological ecoregions of Argentina

The Argentine Republic is situated in the southernmost portion of the American continent, occupying over 2,785,600 km2 not including the Antarctic territory. The country ranges from subtropical areas (21º46’S) to subantarctic regions (55º03’S), extending latitudinally over about 4,000 km. It possesses significant latitudinal and altitudinal variation (33º of latitudinal range, and heights from Bajo de San Julián in Santa Cruz province at 105 m below sea level, up to Mt. Aconcagua, 6,959 m over sea level), as well as two gradients of physical variability, extending in north-south and east-west directions. Owing to these features, the country presents a wide range of climates and soil types, being one of the countries with greatest diversity of biogeographical units (Lean et al., 1990, In: Bertonatti & Corcuera, 2000). There are four main hydrographic systems: Río de la Plata basin, the Atlantic and Pacific drainages, and several endorrheic systems. Within these basins, the ichthyofaunistic assemblage is well represented, with different magnitude in accordance with the different taxonomic groupings and regions considered. From an ichthyogeographic standpoint, and according to the works of Ringuelet (1975) and Arratia et al. (1983), Argentina is included in the Brasilic and Austral Subregions. The first of these is represented by two domains: the Andean Domain, comprising the southernmost portion of Titicaca Province, and the Paranensean Domain, including part of Alto Paraná and Paranoplatensean Provinces. The Austral Subregion is represented in Argentina by the Subandean-Cuyan and Patagonian Provinces. The present survey indicates that there are about 441 fish species in Argentina, distributed throughout the country; this number represents less than 10% of the total fish species occurring in the Neotropical Region. There is a recognizable trend of faunal impoverishment, both in North-South and East-West direction, reaching its maximum expression in the provinces of Tierra del Fuego (situated at approximately 52º30’S to 55ºS, and 65ºS to 68º50’W) and San Juan (approximately 28º50’S and 67ºW to 70º45’W), which have 4 and 5 fish species respectively. In north-south direction, one of the regional indicators of this phenomenon is the Salado river basin in Buenos Aires province, which constitutes the southern distributional boundary for the majority of the paranoplatensean ichthyofauna; 12 of the families occurring in the Paraná-Plata system are absent from this pauperized paranensean ichthyofaunal assemblage. Most of the continental fish fauna of Argentina belongs to the primary division of Myers (1949), while some elements are included in the secondary division and others in an amphibiotic or ‘marine penetration’ category. This ichthyofaunistic scope encompasses a wide range of morphological, biological, ecological and ethological types (benthic and pelagic, migrating and sedentary, haematophagous or parasites, annual species, inhabitants of plains or heights, estivation-adapted, etc.) inhabiting different regions within the national territory

State of the art of pricing policy in air transportation: network carriers vs. low-cost airlines

The modern air transport industry is highly competitive. To survive in the market, the implementation of a successful marketing strategy is fundamental. In particular, an effective pricing policy has become crucial for airlines to remain profitable. Correspondingly, the different types of airline in the market have also established very distinct pricing policies. The present study is based on a literature review and presents the state of the art of pricing policy in air transportation. The aim is to compare and discuss the pricing strategies of network carriers and low-cost airlines. Special attention is paid to Revenue Management, which is a very important management tool used by airlines to take advantage of the differences in willingness to pay of passengers. The pricing policy, however, depends on the overall business strategy of the airline. Results show many differences, resulting from the fact that these two types of airline are characterized by very different fundamental business models and, correspondingly, also target groups. Since network carriers and also low-cost airlines have adjusted their pricing strategies lately, these recent developments will be discussed as well. This paper adds to the knowledge of this topic because it presents the most up-to-date and complete study on pricing regarding network carriers vs. low-cost airlines.A moderna indústria do transporte aéreo é altamente competitiva. Para sobreviver no mercado, a implementação de uma estratégia de marketing bem-sucedida é fundamental. Em particular, uma política de preços eficaz tornou-se crucial para as companhias aéreas continuarem lucrativas. Os diferentes tipos de companhias aéreas no mercado também estabeleceram políticas de preços muito distintas. O presente estudo baseia-se numa revisão da literatura e apresenta o estado da arte da política de preços no transporte aéreo. O objetivo é comparar e discutir as estratégias de preços de companhias aéreas de linha e companhias aéreas de baixo custo. Atenção especial é dada à Gestão de Receitas (Revenue Management), que é uma ferramenta de gestão usada pelas companhias aéreas para aproveitar as diferenças na disposição de pagar dos passageiros. A política de preços, no entanto, depende da estratégia geral de negócios da companhia aérea. Os resultados mostram muitas diferenças, resultantes do facto de que esses dois tipos de companhias aéreas são caracterizados por modelos de negócios fundamentais muito diferentes e, correspondentemente, também grupos-alvo. Como as operadoras de rede e também as companhias aéreas de baixo custo ajustaram as suas estratégias de preços ultimamente, esses desenvolvimentos recentes também serão discutidos. Este documento contribui para o conhecimento deste tópico, pois apresenta o estudo mais atualizado e completo sobre preços de companhias aéreas de linha versus companhias aéreas de baixo custo.info:eu-repo/semantics/publishedVersio

Zero-temperature spin-glass freezing in self-organized arrays of Co nanoparticles

We study, by means of magnetic susceptibility and magnetic aging experiments, the nature of the glassy magnetic dynamics in arrays of Co nanoparticles, self-organized in N layers from N=1 (two-dimensional limit) up to N=20 (three-dimensional limit). We find no qualitative differences between the magnetic responses measured in these two limits, in spite of the fact that no spin-glass phase is expected above T=0 in two dimensions. More specifically, all the phenomena (critical slowing down, flattening of the field-cooled magnetization below the blocking temperature and the magnetic memory induced by aging) that are usually associated with this phase look qualitatively the same for two-dimensional and three-dimensional arrays. The activated scaling law that is typical of systems undergoing a phase transition at zero temperature accounts well for the critical slowing down of the dc and ac susceptibilities of all samples. Our data show also that dynamical magnetic correlations achieved by aging a nanoparticle array below its superparamagnetic blocking temperature extend mainly to nearest neighbors. Our experiments suggest that the glassy magnetic dynamics of these nanoparticle arrays is associated with a zero-temperature spin-glass transition.Comment: 6 pages 6 figure

EL DESARROLLO SUSTENTABLE Y LA INSTRUMENTACIÓN DE SU PARADIGMA EN MÉXICO

Since the late 1960s the discussion about the limits of growth fueled the development of sustainable development as a paradigm that has dominated strategies and policies, including the proposal in 2012 of Green Economies. Nonetheless, progress has not been achieved, among other reasons for the absence of integrated public policies. With a general perspective, the experience of Mexico’s federal public administration and recent planning instruments is revisited, including the creation of green jobs. With such analysis the conclusion about the importance of integrated public policies is duplicated

Desarrollo de la competencia lectora en secundaria

En México, los alumnos de telesecundaria obtienen los puntajes más bajos en competencia lectora. Este trabajo presenta los resultados de una investigación que tuvo como objetivo determinar la eficacia de un programa de comprensión lectora implementado en telesecundarias de una región marginada. El diseño fue experimental, con 16 grupos de octavo grado como grupo experimental y siete como control. Los resultados muestran que el grupo de control obtuvo los mismos puntajes antes y después de la intervención, mientras que el grupo experimental presentó una mejoría en la segunda evaluación, por lo que se considera que el programa fue eficaz.ITESO, A.C

Water Quality of the Beach in an Urban and not Urban Environment

Numerous studies and theories have emerged for evaluating the quality of beaches using different parameters. In recent years in the European region, one of the most important aspects when evaluating a beach is the quality of water and sand. The quality of water is represented by the amount of Intestinal Enterococcus and Escherichia coli. This parameter is essential and others to obtain the Blue Flag, indicating that the user of the beach can swim safely. The European Directive 2006/7/EC establishes the limits of E. coli and Enterococcus that may exist in bathing water. However, it should be noted that each ecosystem is unique, and therefore the characteristics a beach are not the same per example if you are in an inland sea, or an ocean, or equal if they are close to an urban or a natural area. In this paper, 1,392 beaches in Spain have been analysed, and it has been observed that in the Mediterranean, the beaches have a lower concentration of bacteria than other areas. In addition, it appears that the sandy beaches and urban beaches have a higher content of bacteria that natural and gravel beaches

EL DESARROLLO SUSTENTABLE Y LA INSTRUMENTACIÓN DEL PARADIGMA EN MÉXICO

Since the late 1960s the discussion about the limits of growth fueled the development of sustainable development as a paradigm that has dominated strategies and policies, including the proposal in 2012 of Green Economies. Nonetheless, progress has not been achieved, among other reasons for the absence of integrated public policies. With a general perspective, the experience of Mexico’s federal public administration and recent planning instruments is revisited, including the creation of green jobs. With such analysis the conclusion about the importance of integrated public policies is duplicated

Las creencias epistemológicas de alumnos y profesores de primero de secundaria

En este artículo se describen las creencias epistemológicas de alumnos y profesores de tres secundarias públicas en la zona metropolitana de Guadalajara. Se siguió el enfoque cuantitativo no experimental de tipo encuesta. El instrumento empleado fue el Inventario de Creencias Epistemológicas Sobre las Matemáticas desarrollado por Walker. La muestra incluyó 946 alumnos y diez profesores de primero de secundaria. Los resultados se analizaron desde la perspectiva cognitiva, particularmente desde los trabajos de Schommer y Perry, quienes consideran que las acciones pedagógicas y de aprendizaje de profesores y alumnos están influenciadas por su epistemología personal, entendida como un conjunto de creencias que afectan las maneras en las que las personas afrontan la tarea de aprender y enseñar. Los resultados muestran que tanto alumnos como profesores tienen creencias epistemológicas poco productivas para el aprendizaje o enseñanza de las matemáticas. Finalmente se analizan las implicaciones para el trabajo en el aula de secundaria.ITESO, A.C

El desarrollo de habilidades lectoras en la escuela telesecundaria. Algunas reflexiones sobre el papel del docente y los logros de los alumnos

Se presenta el análisis de las implicaciones que tiene la enseñanza de habilidades de comprensión lectora en telesecundaria. Se describe la intervención realizada en 16 grupos de segundo grado en escuelas telesecundarias de una zona marginada del estado de Jalisco. Se resalta especialmente el papel del docente en el éxito de la intervención y cómo este tipo de iniciativas pueden contribuir a la promoción de equidad educativa al fortalecer las habilidades de los alumnos menos avanzados.ITESO, A.C