2,681 research outputs found
Aportaciones al conocimiento de la vegetación acuática flotante, sumergida o enraizada de la provincia de Jaén (S España)
Se ha estudiado la vegetación acuática de la provincia de Jaén (sureste de España). Para ello, se han seleccionado las cuencas de los ríos Rumblar, Guadalbullón, Arroyo Salado de Cabra de Santo Cristo y Guadalentín, que comprenden toda la diversidad biogeográfica de esta provincia. Se han identificado y localizado cuatro clases de vegetación, cuatro órdenes, ocho alianzas, así como 15 fitocenosis, de las cuales, cuatro (Charetum fragilis, Ranunculetum tripartiti, Callitricho lusitanicae-Ranunculetum penicillati y Enteromorpho intestinalis-Ruppietum maritimae) no se habían citado con anterioridad en la provincia de Jaén.Contributions to the knowledge of floating or rooted submerged aquatic vegetation of the province of Jaén (S Spain). A study of the aquatic vegetation of the province of Jaén (southeastern Spain) has been carried out. Four river basins (Rumblar, Guadalbullón, Arroyo Salado de Cabra de Santo Cristo, and Guadalentín rivers) have been selected, comprising the whole biogeographical diversity of this province. Four vegetation classes, four orders, eight alliances and 15 phytocoenoses have been identified and localized. Four of these syntax (Charetum fragilis, Ranunculetum tripartiti, Callitricho lusitanicae-Ranunculetum penicillati and Enteromorpho intestinalis-Ruppietum maritimae) have not been previously cited in the province of Jaén.Confederación Hidrográfica del Guadalquivir y la Empresa de Gestión Medioambiental, S.A. (EGMASA)Universidad de Jaé
O programa nacional de fortalecimento da agricultura familiar no Brasil: uma análise sobre a distribuição regional e setorial dos recursos.
No Brasil, as políticas públicas para o espaço rural sempre tenderam a priorizar a agricultura patronal, em detrimento dos agricultores familiares. Todavia, os estudos realizados pelos órgãos FAO - INCRA deram subsídio para a criação do Programa Nacional de Fortalecimento da Agricultura Familiar (PRONAF), resultando em um novo direcionamento dos investimentos públicos, os quais passaram a contemplar o segmento dos agricultores familiares. Entende-se o PRONAF como uma política não-compensatória, que, apesar de seus problemas, tem contribuído de fato para mudanças e melhorias no espaço agrário brasileiro. Desde sua criação no final da década de 1990, o PRONAF passou por várias mudanças em sua estrutura administrativa e operacional, a fim de alcançar seus objetivos e adequar-se face a complexa realidade social agrária brasileira. Sendo assim, o presente estudo visa discutir as ações do Estado por meio desse Programa, a partir de suas linhas de atuação, bem como analisar a distribuição de suas concessões de crédito regional e setorialmente. Assim, os procedimentos metodológicos utilizados para a realização deste trabalho compreendem pesquisa bibliográfica e documental, além de pesquisa em fontes secundárias, no intuito de obter dados e informações relevantes para a análise das relações sociais estabelecidas em meio a esse processo de concretização e espacialização desse Programa. Dentre as implicações do PRONAF pode-se notar em âmbito nacional, uma diminuição da disparidade regional brasileira, bem como a preocupação que o Programa tem demonstrado com os aspectos socioculturais locais e regionais, como forma de garantir que seus investimentos perpassem a dimensão econômica, mas valorize outras dimensões, a exemplo dos elementos culturais
Suppression of Chaotic Motion of Tethered Satellite Systems Using Tether Length Control
This study focuses on attitude and control motion of two bodies (a
base-satellite and a sub-satellite) connected by an inextensible and massless
tether in a circular orbit under the influence of the Earths gravitational
force. The base-satellite is assumed to be far more heavier than the
sub-satellite. In such cases, the base-satellite is regarded as the reference
spacecraft. Because of the complexity of the problem, no thrusters on the
sub-satellite are considered, and the effect of atmospheric drag, Earths
oblateness, and electrodynamic force on the spacecraft are neglected
Structural characteristics that determine the inhibitory role of phenolic compounds on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation
In an attempt to understand the structural characteristics of phenolic compounds that favour the inhibition of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) formation, this study analyzes the role of twenty-five phenolic compounds on the PhIP produced in phenylalanine/creatinine/oxidised lipid reaction mixtures. The results showed that phenols having two hydroxy groups at meta positions of the aromatic ring were the most efficient inhibitors. The presence of alkyl or carboxylic groups as additional substituents in the aromatic ring slightly reduced the inhibitory effect. On the other hand, the introduction of additional hydroxy and amino groups mostly cancelled the inhibitory effect, which was also mostly absent in ortho and para dihydroxy derivatives. In complex phenols, the presence of several rings with opposite effects produced a reduced inhibitory effect. All these results suggest that it is possible to predict if a phenolic derivative will inhibit the formation of PhIP, or not, based on its structure. © 2013 Elsevier Ltd. All rights reserved.This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (Project AGL2012-35627). Ricardo Salazar gratefully acknowledges the financial support for his doctoral studies from the Consejo Nacional de Ciencia y Tecnología (CONACyT) of México.Peer Reviewe
The genus Tapecomys (Rodentia, Cricetidae) in Argentina: a clarification
El roedor filotino Tapecomys ha sido mencionado con 2 especies en Argentina, la típica Tapecomys primus Anderson y Yates, 2000 y Tapecomys wolffsohni (Thomas, 1902); ambas han sido reportadas como simpátricas en 1 localidad de las Yungas de Jujuy. Una revisión de estos materiales indica que la referencia a T. wolffsohni es incorrecta. En este contexto, en la selva montana solo se registra T. primus con 4 localidades en Jujuy. Otro registro para T. wolffsohni en Argentina, correspondiente a una localidad de Salta, es discutido sobre la base de una nueva aproximación morfológica. En el estado de conocimiento actual no es posible afirmar que T. wolffsohni habite el país.The 2 known species of the phyllotine rodent Tapecomys , the typical, Tapecomys primus Anderson and Yates, 2000 and Tapecomys wolffsohni (Thomas, 1902), have been cited for Argentina, and reported to be sympatric in 1 locality in the Yungas of Jujuy. A review of these materials suggest that the reference for T. wolffsohni is incorrect. In this context, only 1 species— T. primus —is present in 4 localities in the montane forests of Jujuy. A record for T. wolffsohni from 1 locality in Salta, is discussed based on a critical assessment of the morphological variation of these species. Currently it is not possible to confirm that T. wolffsohni inhabits the country.Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Salazar Bravo, Jorge. Texas Tech University; Estados Unido
Voluntary carbon neutral programs. Adoption and firms’ strategies
Voluntary Carbon Neutral (CN) programs promote the reduction of Greenhouse Gas emissions of participants. The main objective of this article is to review the literature about firms' behavior in connection to CN programs, paying particular attention to the adoption decision and the firms' strategies to meet the CN requirements. As an additional aim, we analyze the economic rationale behind the firms' decisions by connecting our literature review to a simple model based on the standard microeconomic theory of the firm. We model the firm's decision as a three-stage problem which includes, first, the adoption (or not) of a voluntary CN program, second, the selection of strategies to become CN (if the program is adopted) and third, the usual price and quantity decisions in the output market. The model helps understand some results found in the literature, such as why some activity sectors are more prone than others to adopt the CN certification. It also provides an explanation for the fact that these voluntary programs tend to be adopted by firms that are large, innovative, and more concerned about intergenerational equity and environmental preservation
The Akodon boliviensis species group (Rodentia: Cricetidae: Sigmodontinae) in Argentina: species limits and distribution, with the description of a new entity
Akodon, with about 42 living species, is the most diverse genus of the subfamily Sigmodontinae. The Akodon boliviensis species group includes small-bodied, morphologically similar forms inhabiting Altiplano grasslands and grassland/forest ecotones of the eastern slope of the Andes, from central Peru to central Argentina. Northwestern Argentina contains the largest diversity of species of the group; the taxonomic treatment of these species has been based largely on unsupported and some weakly based opinions as underscored by recurrent changes. Based on morphologic and molecular data we assessed species limits among Argentinean populations of the Akodon boliviensis species group. We conclude that four species of the A. boliviensis species group inhabit northwestern Argentina. These are: A. boliviensis; A. caenosus (under which we synonymyze A. aliquantulus); A. spegazzinii (of which the nominal forms alterus, leucolimnaeus, and tucumanensis are junior synonyms); and A. sylvanus. Additionally, we described here a new species of the A. Boliviensis species group, Akodon polopi, which inhabits central Argentina. This is the only species of the A. boliviensis species group inhabiting the Sierras Grandes range (ca. 2000 m), mountain system of medium height isolated (ca., 600 km) from the main Andean chain by low elevation arid and semiarid environments. Additionally, our phylogenetic analysis suggests that the Akodon varius species group is polyphyletic.Fil: Jayat, Jorge Pablo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Investigaciones Ecológicas de las Yungas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ortiz, Pablo Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Salazar Bravo, Jorge. Texas Tech University; Estados UnidosFil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: D’Elía, Guillermo. Universidad de Concepción; Chil
Effects of basic infrastructure on ENLACE Test of High School Technology Mexican
Bajo la teoría de capital humano, la educación se concibe como auspiciadora de capital humano y económico. La inversión en capital humano puede reflejarse a mediano plazo en el logro académico de los estudiantes. El logro académico es un indicador de la eficacia de las políticas educativas, sin embargo, en Latino América hay pocos estudios que analicen los efectos que tienen los insumos o el gasto de inversión en el desempeño de los estudiantes. En el presente estudio se analizó una muestra de 538 escuelas de educación media superior con el fin de evaluar los efectos que tiene el número de alumnos por grupo y el número de alumnos por clase sobre el logro académico. Se realizó análisis factorial confirmatorio y un modelo estandarizado con análisis de senderos por Máxima Verosimilitud para infraestructura y logro académico. Se encontró que el incremento de alumnos por grupo y el número de alumnos por clase aumenta la cantidad de alumnos que obtienen niveles de ejecución elemental tanto en habilidad lectora como en habilidad matemática. Así también, disminuye el número de alumnos con desempeño excelente en ambas habilidades. Estos resultados respaldan la evidencia que indica que la infraestructura escolar afecta el desempeño o logro educativo.Under human capital theory, education is seen as sponsor of human and economic capital. Investment in human capital in the medium term may be reflected in the students' academic achievement. Academic achievement is an indicator of the effectiveness of education policies, however, in Latin America there are few studies analyzing effects of inputs or investment spending on student performance. In this study were considered 538 high schools (vocational School) in order to assess effects of number of students per classroom and number of students per class in academic achievement. We carry out a confirmatory factorial analysis and a structural model by Maximum-likelihood Paths for infrastructure and academic achievement. Was found that increase of students per classroom and per class have negative effects because these increase on quantity of students with low levels on reading and mathematical abilities. Also, was reducing the number of students with excellent performance in both skills. These results support the evidence that scholar infrastructure has effects on academic achievement
Fragmentos urbanos de Guerra Fría en el “tercer mundo”
En 1949, en el discurso inaugural para su segundo período presidencial, Harry S. Truman
proclamó una agenda de colaboración entre los
Estados Unidos y las áreas subdesarrolladas del
mundo, con el objetivo de reducir la pobreza
a través de un desarrollo impulsado por los
conocimientos y avances tecnológicos de su
país. En 1973, Robert McNamara, presidente del Banco Mundial, instaba a erradicar la
pobreza absoluta promoviendo estrategias que
lograsen una distribución más equitativa de los
beneficios del crecimiento económico. En ambas
agendas internacionales se incluyeron políticas habitacionales para alcanzar sus objetivos.
El artículo explora el rol que cumplieron la arquitectura y el diseño urbano en estos programas, a través de la revisión de conjuntos de
vivienda construidos en ciudades y paisajes de América Latina, África y Asia, en el contexto
de la Guerra Fría.
En ambos momentos históricos se utilizó la estrategia de autoconstrucción asistida
para llegar a la población con menos recursos
económicos. Por una parte, entre las múltiples
críticas que recibieron estas operaciones, estuvo la segregación social que producirían. Por
otra, veremos cómo estos conjuntos se articularían como fragmentos urbanos que, a través de
su diseño y equipamiento comunitario, apoyarían el desarrollo social de los pobladores. El
primer momento que revisaremos corresponde
a los inicios de la promoción internacional de
políticas de autoconstrucción por parte de instituciones estadounidenses; el segundo, es el
instante en que el Banco Mundial expande esta
agenda globalmente incorporando, por primera
vez, el problema habitacional urbano entre sus
proyectos. En estos dos períodos la vivienda fue incluida para promover un crecimiento económico, así como para extender las fronteras
geopolíticas del primer mundo –liderado por Estados Unidos– hacia los países del tercer mundo.In 1949, in the inaugural speech for his second
presidential term, Harry S. Truman proclaimed an agenda of collaboration between the
United States and the underdeveloped areas of
the world, aiming to reduce poverty through
development driven by U.S. knowledge and technological advances. In 1973, Robert McNamara, president of the World Bank, called for
the eradication of absolute poverty, promoting
strategies that would achieve a more equitable
distribution of the benefits of economic growth.
Both international agendas included housing
policies to achieve their objectives. This article
explores the role of architecture and urban design in these programs by reviewing housing
developments built in cities and landscapes in
Latin America, Africa and Asia in the context
of the Cold War.
In both historical moments, assisted
self-construction was used to reach populations with low economic resources. On one
side, among the many criticisms made to these operations was the social segregation they
would generate. On the other side, we will see
how these developments would articulate urban
fragments that, through their design and community equipment, would support the social
growth of the inhabitants. The first reviewed
moment corresponds to the beginning of the
international promotion of self-construction
policies by U.S. institutions; the second is the
moment when the World Bank expanded this
program globally incorporating, for the first
time, the urban housing problem into its agenda. In these two periods, housing was included
to promote economic development, as well as
to extend the geopolitical frontiers of the first
world –led by the United States– towards third
world countries.Em 1949, no discurso inaugural do seu segundo mandato como presidente, com o objetivo de
reduzir a pobreza através do desenvolvimento
impulsionado pelo conhecimento e avanços
tecnológicos dos EUA, Harry S. Truman proclamou uma agenda de colaboração entre os
Estados Unidos e as áreas subdesenvolvidas do
mundo. Em 1973, Robert McNamara, presidente do Banco Mundial, apelou à erradicação
da pobreza absoluta, promovendo estratégias
que permitissem uma distribuição mais equitativa dos benefícios do crescimento econômico.
Ambas as agendas internacionais incluíam
políticas de habitação para alcançar os seus
objetivos. Este artigo explora o papel desempenhado pela arquitetura e pelo urban design
nestes programas, revisando conjuntos habitacionais construídos em cidades e paisagens
da América Latina, África e Ásia, no contexto
da Guerra Fria.
Em ambos os momentos históricos,
a estratégia de auto-construção assistida foi
utilizada para alcançar a população com menos recursos econômicos. Por um lado, entre
as muitas críticas a estas operações estava a
segregação social que elas produziriam; por
outro, veremos como estes conjuntos habitacionais articulariam fragmentos urbanos que,
por meio da concepção e implementação de
equipamentos comunitários, apoiariam o desenvolvimento social dos habitantes. O primeiro momento que iremos rever corresponde ao
início da promoção internacional de políticas
de auto-construção por instituições norte-americanas; o segundo, é o momento em que
o Banco Mundial expandiu esta agenda a nível global, incorporando, pela primeira vez, o
problema da habitação urbana em sua agenda.
Nestes dois períodos, a habitação foi incluída
para promover o crescimento econômico, assim como para alargar as fronteiras geopolíticas do primeiro mundo –lideradas pelos Estados
Unidos– para países do terceiro mundo
- …