University of Nevada, Reno

About: University of Nevada, Reno is a education organization based out in Reno, Nevada, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 13561 authors who have published 28217 publications receiving 882002 citations. The organization is also known as: University of Nevada & Nevada State University.

Morphometric indices of body condition in birds: a review

Abstract: Morphometric estimates of body condition are widely used by ornithologists, but which estimates work best is a matter of debate. We review morphometric approaches (body mass, ratio and residual condition indices, predictive regression models, fat scoring, and abdominal profiles) for estimating body condition (defined as fat mass) in birds. We describe the strengths and weaknesses of each approach. Across diverse indices and species (~200 estimates total), the mean r 2 relating condition indices to mass of body fat was 0.55, and 64% of the r 2 values were greater than 0.50. But despite their generally good performance, condition indices sometimes perform poorly (i.e., r 2 is low). The data indicate that: (1) no single index was clearly best, (2) on average body mass alone, fat scores, and predictive multiple regression equations explained slightly more than 50% of the variation in fat content, (3) on average, ratio and residual indices explained slightly less than 50% of the variation in fat content, and (4) body mass alone, a variable that can be easily and reliably measured, is as good or nearly as good an indicator of fat content as any other condition index. We recommend that: (1) morphometric indicators of condition be empirically validated, (2) researchers publish their body composition data in sufficient detail that they can be used in future analyses exploring the relative merits of different condition indices, and (3) multiple regression directly on measured traits be used instead of condition indices whenever the condition index is not empirically validated.

A mammalian predator-prey imbalance: grizzly bear and wolf extinction affect avian neotropical migrants

Abstract: Because most large, terrestrial mammalian predators have already been lost from more than 95-99% of the contiguous United States and Mexico, many ecological communities are either missing dominant selective forces or have new ones dependent upon humans. Such large-scale manipulations of a key element of most ecosystems offer unique opportunities to investigate how the loss of large carnivores affects communities, including the extent, if any, of interactions at different trophic levels. Here, we demonstrate a cascade of ecological events that were triggered by the local extinction of grizzly bears (Ursus arctos) and wolves (Canis lupus) from the southern Greater Yellowstone Ecosystem. These include (1) the demographic eruption of a large, semi-obligate, riparian-dependent herbi- vore, the moose (Alces alces), during the past 150 yr; (2) the subsequent alteration of riparian vegetation structure and density by ungulate herbivory; and (3) the coincident reduction of avian neotropical migrants in the impacted willow communities. We contrasted three sites matched hydrologically and ecologically in Grand Teton National Park, Wyo- ming, USA, where grizzly bears and wolves had been eliminated 60-75 yr ago and moose densities were about five times higher, with those on national forest lands outside the park, where predation by the two large carnivores has been replaced by human hunting and moose densities were lower. Avian species richness and nesting density varied inversely with moose abundance, and two riparian specialists, Gray Catbirds (Dumetella carolinensis) and MacGillivray's Warblers (Oporornis tolmiei), were absent from Park riparian systems where moose densities were high. Our findings not only offer empirical support for the top-down effect of large carnivores in terrestrial communities, but also provide a scientific rationale for restoration options to conserve biological diversity. To predict future impacts, whether overt or subtle, of past management, and to restore biodiversity, more must be known about ecological interactions, including the role of large carnivores. Restoration options with respect to the system that we studied in the southern Greater Yellowstone Ecosystem are simple: (1) do nothing and accept the erosion of biological diversity, (2) replace natural carnivores with human predation, or (3) allow continued dispersal of grizzly bears and wolves into previously occupied, but now vacant, habitat. Although additional science is required to further our understanding of this and other terrestrial systems, a larger con- servation challenge remains: to develop public support for ecologically rational conser- vation options.

Cognition and the visual arts

Abstract: An experienced and prolific writer, Robert Solso has a gift for simplifying sometimes difficult concepts in science. Here he brings a refreshing new approach to the psychology of art, synthesizing research from a vast collection of data on how humans perceive, process, and store information and applying it to the viewing and interpretation of art. In this first systematic study of the connection between the new cognitive psychology and its importance to art, Solso reflects on the long relationship between humankind and art, observing that "mind and art are one." A major theme of this book, in fact, is that the clearest view of the mind comes when we create or experience art, a reverse of the usual view of art and cognition. The illustrations cover a wide range of examples, including African, Asian, and prehistoric art, but focusing primarily on Western art. The treatment of cognition applies a blend of the standard information-processing model, brain function, and neural networks.Cognitive Psychology series

Soil water exploitation after fire: competition between Bromus tectorum (cheatgrass) and two native species.

Abstract: Causes for the widespread abundance of the alien grass Bromus tectorum (cheatgrass) after fire in semiarid areas of western North America may include: (1) utilization of resources freed by the removal of fireintolerant plants; and (2) successful competition between B. tectorum and individual plants that survive fire. On a site in northwestern Nevada (USA), measurements of soil water content, plant water potential, aboveground biomass production, water use efficiency, and B. tectorum tiller density were used to determine if B. tectorum competes with either of two native species (Stipa comata and Chrysothamnus viscidiflorus) or simply uses unclaimed resources. Soil water content around native species occurring with B. tectorum was significantly lower (P<0.05) than around individuals without B. tectorum nearby. Native species had significantly more negative plant water potential when they occurred with B. tectorum. Aboveground biomass was significantly higher for native species without B. tectorum. However, the carbon isotope ratio of leaves for native species with B. tectorum was not significantly different from individuals without B. tectorum. Thus, B. tectorum competes with native species for soil water and negatively affects their wate status and productivity, but the competition for water does not affect water use efficiency of the native species. These adverse effects of B. tectorum competition on the productivity and water status of native species are also evident at 12 years after a fire. This competitive ability of B. tectorum greatly enhances its capability to exploit soil resources after fire and to enhance its status in the community.

Frequency Response Analysis of Current Controllers for Selective Harmonic Compensation in Active Power Filters

Abstract: This paper compares four current control structures for selective harmonic compensation in active power filters. All controllers under scrutiny perform the harmonic compensation by using arrays of resonant controllers, one for the fundamental and one for each harmonic of interest, in order to achieve zero phase shift and unity gain in the closed-loop transfer function for selected harmonics. The complete current controller is the superposition of all individual harmonic controllers and may be implemented in various reference frames. The analysis is focused on the comparison of harmonic and total closed-loop transfer functions for each controller. Analytical similarities and differences between schemes in terms of frequency response characteristics are emphasized. It is concluded that three of them have identical harmonic behavior despite the fact that their implementation is significantly different. It emerges that the fourth one has superior behavior and robustness and can stably work at higher frequencies than the others. Theoretical findings and analysis are supported by comparative experimental results on a 7-kVA laboratory setup. The highest harmonic frequency that can be stably compensated with each control method has been determined, indicating significant differences in the control performance.