1,484 research outputs found
Formal institutions and opportunity entrepreneurship. The contingent role of informal institutions
This paper analyzes opportunity entrepreneurship through the interplay between formal and informal institutions. It seems evident that not all entrepreneurial initiatives have the same quality, thus the goal of a society should be to encourage the activities that best contribute to innovation and value generation. We theorize that informal institutions are contingent to the formal institutional environment where the new ventures operate. Our empirical results, using GEM data, confirm that, in countries with a more individualistic orientation, the relationship between formal institutions and opportunity entrepreneurship is more intense, as happens in societies with lower levels of uncertainty avoidance
Trans-equatorial migration and mixing in the wintering areas of a pelagic seabird
Despite increasing interest in long-distance migration, the wintering areas, migration corridors, and population mix in winter quarters of most pelagic marine predators are unknown. Here, we present the first study tracking migration movements of shearwaters through the non-breeding period. We used geolocators (global location sensing [GLS] units based on ambient light levels) to track 22 Cory's shearwaters (Calonectris diomedea) breeding in three different areas. Most birds wintered in one or more of three relatively small areas, all clearly associated with major coastal upwelling systems of the tropical and south Atlantic. Trans-equatorial movements were dominated by prevailing trade winds and westerlies, while calm, oligotrophic areas were avoided. Breeding populations clearly differed in their preference amongst the three major wintering areas, but showed substantial mixing. This illustrates the exceptional value of GLS, not only for determining and describing the influence of oceanographic features on migration patterns, but also for assessing population mix in winter quarters. This knowledge is essential to understanding the impacts of population-level threats, such as longlining, offshore windfarms, and oil spills on multiple breeding sites, and will be critical in devising conservation policies that guarantee the sustainable exploitation of the oceans
A methodological approach for assessing flexibility and capacity value in renewable-dominated power systems: A Spanish case study in 2030
Maintaining the security of supply is one of the challenges that system operators face. Variability and uncertainty increase due to the penetration of variable renewable energy sources such as solar and wind, while flexible technologies such as traditional thermal units are phased out to reduce emissions. The current methods for assessing power system adequacy are based on historical operations and are generally intended to be applied to thermal-dominated electricity systems. Therefore, it is necessary to improve current adequacy assessment methods since they usually neglect the flexibility of power systems. This paper presents a methodological approach for jointly assessing the adequacy and flexibility of power systems. The methodology's usefulness is demonstrated through its application to the Spanish power system. For the case study, results show that new closed-looped pumped storage hydro technology provides 25% flexibility while contributing to adequacy due to higher installed capacity and round-trip efficiency. Due to shorter storage duration, batteries only contribute to flexibility, supplying 16% of the total operating reserves. Therefore, this study shows that metrics of flexibility and individual contribution to the power system adequacy complement each other and simultaneously enable the scarcities of power systems to be observed.This research has been carried out thanks to the Spanish Ministry of Economy and Competitiveness MINECO through BC3 María de Maeztu excellence accreditation MDM-2017-0714 Maria de Maeztu Grant
Anthropometric Characteristics, Body Composition and Somatotype in Elite Junior ITF Tennis Players from South America
Indexación: Scopus; Scielo.El objetivo de este estudio fue determinar las características antropométricas, composición corporal y somatotipo en tenistas varones elite juniors sudamericanos de la Federación Internacional de Tenis. Participaron 25 jugadores de 17,04 ± 1,05 años. La composición corporal se evaluó con el perfil restringido de 25 variables propuesto por Kerr en base al método pentacompartimental, el cual fracciona el cuerpo en 5 componentes (tejidos: muscular, adiposo, óseo, residual, y piel). El somatotipo se identificó con el método de Heath y Carter. Para la evaluación se utilizaron las normas propuestas por La Sociedad Internacional para el Avance de la Cineantropometría (ISAK) y el Grupo Español de Cineantropometría (GREC). El porcentaje de tejido muscular fue de 47,65 ± 2,83 %, tejido adiposo de 23,23 ± 3,56 %, y tejido óseo de 11,79 ± 1,56 % con un índice músculoóseo(IMO) de 4,09 ± 0,50. En cuanto al somatotipo se apreció una clasificación de tipo mesomorfo balanceado con valores de 2,5 ± 0,81 de endomorfia, 4,9 ± 0,66 de mesomorfia, y 2,7 ± 0,96 de ectomorfia. El grupo de tenistas presentó un predominio del componente mesomorfia con un equilibrio entre los componentes endomorfia y ectomorfia con características de composición corporal similares a las encontradas en la literatura. El presente estudio entrega datos referenciales sobre las características antropométricas en tenistas sudamericanos nivel elite categoría junior.The objective of the study was to determine the anthropometric characteristics, body composition and somatotype in male elite junior tennis players from the International Tennis Federation (ITF). Twenty five players of 17.04 ± 1.05 years participated. The body composition was evaluated with the restricted profile of 25 variables proposed by Kerr based on the pent compartmental method, which divided the body into 5 components (tissues: muscle, adipose, bone, residual, and skin). The somatotype was identified with the Heath and Carter method. For the evaluation, the norms proposed by the International Society for the Advancement of Cineanthropometry (ISAK) and the Spanish Group of Cineanthropometry (GREC) were used. The percentage of muscle tissue was 47.65 ± 2.83 %, adipose tissue of 23.23 ± 3.56 %, and bone tissue of 11.79 ± 1.56 % with a muscle-osseous index (IMO) of 4.09 ± 0.50. Regarding somatotype, a balanced mesomorphic classification was observed with values of 2.5 ± 0.81 of endomorphy, 4.9 ± 0.66 of mesomorphy, and 2.7 ± 0.96 of ectomorphy. The group of tennis players presented a predominance of the mesomorphy component with a balance between the components endomorphy and ectomorphy with characteristics of body composition similar to those found in the literature. The present study provides referential data on the anthropometric characteristics in South American tennis players elite junior category.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-95022018000301095&lng=en&nrm=iso&tlng=e
La ideología de género: una respuesta de la Antropología y la Teología
El trabajo analiza la historia y desarrollo de los movimientos feministas, así como las repercusiones de la IV Conferencia Mundial de la Mujer (Pekín, 1995) que, según muchos estudiosos, ha sido utilizada como una importante plataforma para el desarrollo del feminismo radical, cuyo objetivo es eliminar o no dar relieve particular a la bipolaridad sexual del ser humano. Primero se ponen de manifiesto las consecuencias que estas corrientes comportan para el ser humano, el matrimonio, la familia, etc., y después se considera la respuesta al feminismo radical desde la antropología y la teología.
El estudio pone de relieve cómo la realidad diferenciada de ser varón y ser mujer pertenece a la persona humana como tal y, por eso mismo, respetar esa diferenciación es irrenunciable en la valoración adecuada de la verdadera dignidad del varón y de la mujer. La consideración de la sexualidad como dimensión constitutiva de la persona, su ordenación al don y a la complementariedad, y el respeto de su estructura, son algunos de estos significados.
Además de responder a los argumentos de carácter antropológico en los que se intenta apoyar el feminismo radical, la investigación busca recuperar las nociones antropológicas claves que son necesarias para desmontar los postulados principales de estas corrientes.This work analyzes the history and development of feminist movements, as well as the repercussions of the IV World Conference on Women (Beijing, 1995). According to many scholars, this Conference has been used as an important platform for the development of radical feminism, whose objective is to eliminate or make irrelevant the sexual bipolarity of human beings. First the consequences of these ideologies for individuals, married couples, and families are analyzed. Then the response to radical feminism from anthropology and theology is considered.
The study highlights how the differentiated reality of being male and being female belongs to the human person as such. For this reason, respecting this differentiation is essential in the correct assessment of the true dignity of men and women. The consideration of sexuality as a constitutive dimension of the person, its orientation towards self-giving and complementarity, and the respect for its structure are some of these meanings.
Apart from responding to the anthropological arguments on which radical feminism bases its ideas, the research seeks to recover the key anthropological notions which are necessary to rebut the main postulates of these movements
Magnetotunneling Between Two-dimensional Electron Gases in InAs-AlSb-GaSb Heterostructures
We have observed that the tunneling magnetoconductance between
two-dimensional (2D) electron gases formed at nominally identical InAs-AlSb
interfaces most often exhibits two sets of Shubnikov-de Haas oscillations with
almost the same frequency. This result is explained quantitatively with a model
of the conductance in which the 2D gases have different densities and can
tunnel between Landau levels with different quantum indices. When the epitaxial
growth conditions of the interfaces are optimized, the zero-bias
magnetoconductance shows a single set of oscillations, thus proving that the
asymmetry between the two electron gases can be eliminated.Comment: RevTeX format including 4 figures; submit for publicatio
Autonomic adaptation after traditional and reverse swimming training periodizations
The objective of the present study was to analyze the autonomic response of trained swimmers to traditional and reverse training periodization models. Seventeen swimmers were divided in two groups, performing a traditional periodization (TPG) or a reverse periodization (RPG) during a period of 10 weeks. Heart rate variability and 50 m swimming performance were analyzed before and after the training programs. After training, the TPG decreased the values of the high frequency band (HF), the number of differences between adjacent normal R-R intervals longer than 50 ms (NN50) and the percentage of differences between adjacent normal R-R intervals more than 50 ms (pNN50), and the RPG increased the values of HF and square root of the mean of the sum of the squared differences between adjacent normal R-R intervals (RMSSD). None of the groups improved significantly their performance in the 50-m test. The autonomic response of swimmers was different depending on the periodization performed, with the reverse periodization model leading to higher autonomic adaption. Complementary, the data suggests that autonomic adaptations were not critical for the 50-m swimming performance
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