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.

Real-time eye detection and tracking under various light conditions

Abstract: Non-intrusive methods based on active remote IR illumination for eye tracking are important for many applications of vision-based man-machine interaction. One problem that has plagued those methods is their sensitivity to lighting condition change. This tends to significantly limit their scope of application. In this paper, we present a new real-time eye detection and tracking methodology that works under variable and realistic lighting conditions. Based on combining the bright-pupil effect resulted from IR light and the conventional appearance-based object recognition technique, our method can robustly track eyes when the pupils are not very bright due to significant external illumination interferences. The appearance model is incorporated in both eyes detection and tracking via the use of support vector machine and the mean shift tracking. Additional improvement is achieved from modifying the image acquisition apparatus including the illuminator and the camera.

A self-sensing dielectric elastomer actuator

Abstract: A novel self-sensing method based on the dielectric elastomer (DE) actuator/sensor, was successfully developed and evaluated in order to extract accurate displacement information during the actuation process without using any additional sensing device. The proposed self-sensing method is based on a capacitance characteristic of a DE actuator. The DE actuator with a serial external resistor can serve as an electrical high-pass filter. The voltage gained using the high-pass filter, which is virtually built by the DE, varies due to the change of overall capacitance when the DE actuator is expanded electro-mechanically. To realize actuating and sensing simultaneously with a DE actuator, we used a modulation technique to mix signals, which have a low frequency signal for actuating and a high frequency with small amplitude for sensing. Several experiments were performed to verify the usability of the proposed self-sensing method. The results showed a fine resolution and an excellent correlation with the displacements measured by a laser displacement sensor.

Linking patterns and processes in alpine plant communities: a global study

Abstract: Predictable relationships among patterns, processes, and properties of plant communities are crucial for developing meaningful conceptual models in community ecology. We studied such relationships in 18 plant communities spread throughout nine Northern Hemisphere high-mountain subalpine and alpine meadow systems and found linear and curvilinear correlative links among temperature, precipitation, productivity, plant interactions, spatial pattern, and richness. We found that sites with comparatively mild climates have greater plant biomass, and at these sites strong competition corresponds with overdispersed distribution of plants, reducing intraspecific patchiness and in turn increasing local richness. Sites with cold climates have little biomass, and at these sites a high proportion of species benefit from strong facilitative effects of neighbors, leading to an aggregated distribution of plants. Sites with intermediate, or relatively moderate climates are intermediate in biomass, and at these sites interactions are weak (or competition may be counterbalanced by facilitation), corresponding with a nearly random distribution of plants. At these sites species richness is lower than average. We propose that the relationship between interspecific spatial pattern and community richness reflects niche differentiation and/or construction, which allows for the coexistence of more species than would be possible with random, unstructured spatial distributions. Discovering the mechanisms that drive the relationships described here would further link functional and structural components of plant communities and enhance the predictive capability of community ecology.

Invited Review: Mechanisms of calcium handling in smooth muscles

Abstract: The concentration of cytoplasmic Ca2+ regulates the contractile state of smooth muscle cells and tissues. Elevations in global cytoplasmic Ca2+ resulting in contraction are accomplished by Ca2+ entry and release from intracellular stores. Pathways for Ca2+ entry include dihydropyridine-sensitive and -insensitive Ca2+ channels and receptor and store-operated nonselective channels permeable to Ca2+. Intracellular release from the sarcoplasmic reticulum (SR) is accomplished by ryanodine and inositol trisphosphate receptors. The impact of Ca2+ entry and release on cytoplasmic concentration is modulated by Ca2+ reuptake into the SR, uptake into mitochondria, and extrusion into the extracellular solution. Highly localized Ca2+ transients (i.e., sparks and puffs) regulate ionic conductances in the plasma membrane, which can provide feedback to cell excitability and affect Ca2+entry. This short review describes the major transport mechanisms and compartments that are utilized for Ca2+ handling in smooth muscles.