The National University of Comahue is an Argentine national university with branches in the provinces of Neuquén, Río Negro and Chubut, with a center in the city of Neuquén and units in Viedma, Bariloche, San Martín de los Andes, Cipolletti, Zapala, Allen, General Roca, Choele Choel, San Antonio Este, Villa Regina, Esquel, Puerto Madryn, Trelew. Wikipedia.
Harder L.D.,University of Calgary |
Aizen M.A.,National University of Comahue
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2010
Pollen limitation (PL) of seed production creates unique conditions for reproductive adaptation by angiosperms, in part because, unlike under ovule or resource limitation, floral interactions with pollen vectors can contribute to variation in female success. Although the ecological and conservation consequences of PL have received considerable attention in recent times, its evolutionary implications are poorly appreciated. To identify general influences of PL on reproductive adaptation compared with those under other seed-production limits and their implications for evolution in altered environments, we derive a model that incorporates pollination and postpollination aspects of PL. Because PL always favours increased ovule fertilization, even when population dynamics are not seed limited, it should pervasively influence selection on reproductive traits. Significantly, under PL the intensity of inbreeding does not determine whether outcrossing or autonomous selfing can evolve, although it can affect which response is most likely. Because the causes of PL are multifaceted in both natural and anthropogenically altered environments, the possible outcrossing solutions are diverse and context dependent, which may contribute to the extensive variety of angiosperm reproductive characteristics. Finally, the increased adaptive options available under PL may be responsible for positive global associations between it and angiosperm diversity. © 2010 The Royal Society.
Lambertucci S.A.,National University of Comahue
ORYX | Year: 2010
Estimations of the population sizes of threatened species are fundamental for conservation. The current estimate of the population of the Andean condor Vultur gryphus is based on limited local counts. Simultaneous censuses of 10 condor communal roosts were therefore conducted during 2006-2008 in north-west Patagonia, Argentina, to obtain a minimum population number, to estimate the size of the local population, and to describe use of the roosts by season and age classes. I fitted the data to two asymptotic models to calculate the population of condors as a function of the number of communal roosts surveyed. In an area of c. 6,300 km2 I obtained a minimum population size of 246 individuals by direct observation, and a population estimate of 296 condors (range 260-332) by applying the models. This population, the largest known of this species, comprises 68.5% adults and 31.5% immatures. Condors had large aggregations in some communal roosts and used the area seasonally, increasing in numbers from autumn to spring and decreasing in summer. Long-term monitoring of communal roosts across the Andean condors range is essential for the monitoring of this rare and vulnerable species. © 2010 Fauna & Flora International.
Aprea J.L.,National University of Comahue
International Journal of Hydrogen Energy | Year: 2014
For decades, the issue of hydrogen quality specification has been a source of complexity and confusion in particular for end users, especially because of the jargon spoken by different providers and clients in varied and diverse areas of application. Virtually every requirement was established within the customer-supplier relationship. The rise of new hydrogen technologies, the emergence of new devices like fuel cells and the spread of knowledge, together with the growing need for uniformity has pushed the specialists to solve this problem. As a result, standardization seems to be the key to accomplish with quality goals at the lowest cost possible. This article discusses the traditional concepts used in the past, the current situation, the standards used today and future developments in hydrogen quality requirements to simplify and facilitate the use and the applications of hydrogen and blends with a careful respect for the quality of the product and safety. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Aprea J.L.,National University of Comahue
International Journal of Hydrogen Energy | Year: 2012
Antarctica is a land of research, peace and one of the last refuges of pristine landscapes and pure environments of the planet. Therefore, the installation of a clean energy module at the Esperanza (HopeBay) Scientific Station of Argentina is one of the signs that opens new perspectives for the respect of the environment through the use of renewable energy sources with the aim of replacing fossil fuels currently used in the continent. This article briefly discusses the preparation, installation, commissioning and two years operation of an electrolytic hydrogen generator powered by wind and various devices designed for safe and reliable use of hydrogen for the benefit of the population of the station and visitors. We analyze the acceptance of the new technologies, the possibility of feeding the module independently from local renewable resources and the difficulties encountered due to the extreme conditions at the location. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Zenni R.D.,University of Tennessee at Knoxville |
Nunez M.A.,University of Tennessee at Knoxville |
Nunez M.A.,National University of Comahue
Oikos | Year: 2013
Most species introductions are not expected to result in invasion, and species that are invasive in one area are frequently not invasive in others. However, cases of introduced organisms that failed to invade are reported in many instances as anecdotes or are simply ignored. In this analysis, we aimed to find common characteristics between non-invasive populations of known invasive species and evaluated how the study of failed invasions can contribute to research on biological invasions. We found intraspecific variation in invasion success and several recurring explanations for why non-native species fail to invade; these included low propagule pressure, abiotic resistance, biotic resistance, genetic constraints and mutualist release. Furthermore, we identified key research topics where ignoring failed invasions could produce misleading results; these include studies on historical factors associated with invasions, distribution models of invasive species, the effect of species traits on invasiveness, genetic effects, biotic resistance and habitat invasibility. In conclusion, we found failed invasions can provide fundamental information on the relative importance of factors determining invasions and might be a key component of several research topics. Therefore, our analysis suggests that more specific and detailed studies on invasion failures are necessary. © 2012 The Authors. Oikos © 2012 Nordic Society Oikos.