Showing papers by "University of Nevada, Reno published in 2005"

Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis.

Abstract: Reactive oxygen species (ROS), such as O2 � and H2O2, play a key role in plant metabolism, cellular signaling, and defense. In leaf cells, the chloroplast is considered to be a focal point of ROS metabolism. It is a major producer of O2 � and H2O2 during photosynthesis, and it contains a large array of ROS-scavenging mechanisms that have been extensively studied. By contrast, the function of the cytosolic ROS-scavenging mechanisms of leaf cells is largely unknown. In this study, we demonstrate that in the absence of the cytosolic H2O2-scavenging enzyme ascorbate peroxidase 1 (APX1), the entire chloroplastic H2O2-scavenging system of Arabidopsis thaliana collapses, H2O2 levels increase, and protein oxidation occurs. We further identify specific proteins oxidized in APX1-deficient plants and characterize the signaling events that ensue in knockout-Apx1 plants in response to a moderate level of light stress. Using a dominant-negative approach, we demonstrate that heat shock transcription factors play a central role in the early sensing of H2O2 stress in plants. Using knockout plants for the NADPH oxidase D protein (knockout-RbohD), we demonstrate that RbohD might be required for ROS signal amplification during light stress. Our study points to a key role for the cytosol in protecting the chloroplast during light stress and provides evidence for cross-compartment protection of thylakoid and stromal/mitochondrial APXs by cytosolic APX1.

Ionic polymer–metal composites: IV. Industrial and medical applications

Abstract: This paper, the last in a series of four review papers to appear in this journal, presents some critical applications using ionic polymer?metal composites?(IPMCs). Industrial and biomedical applications of IPMCs are identified and presented along with brief illustration.

Operator Algebras: Theory of C*-Algebras and von Neumann Algebras

Abstract: Operators on Hilbert Space.- C*-Algebras.- Von Neumann Algebras.- Further Structure.- K-Theory and Finiteness.

Apatite Fission-Track Analysis

Abstract: Apatite fission-track (AFT) analysis has been widely used during the past 30+ years to constrain the low-temperature thermal histories of many igneous, metamorphic and sedimentary rocks in a wide range of geological settings. Applicable geological settings include orogenic belts, rifted margins, faults, sedimentary basins, cratons, and mineral deposits. The types of geologic problems that can be addressed include the timing and rates of tectonic events, sedimentary basin evolution, the timing of hydrocarbon generation and ore mineralization, the absolute age of volcanic deposits, the effects of major climatic changes on the near-surface geothermal gradient, and long-term landscape evolution. Early work by Naeser (1967) and Wagner (1968, 1969) first established the basic procedures that enabled the fission-track dating method to be applied routinely to these geologic problems. Fleischer et al. (1975) summarized the early studies of the broader discipline of nuclear-track detection in different solid-state materials. More recent comprehensive overviews of fission-track applications have been provided by Naeser and McCulloh (1989), Wagner and Van den haute (1992), Gallagher et al. (1998), Van den haute and De Corte (1998), Dumitru (2000), and Gleadow et al. (2002). Etched, natural fission tracks in several apatite grains are shown in Figure 1⇓. Successful AFT analysis is limited by the following: 1) the availability of apatite from which useful AFT data can be obtained, often due to a lack of apatite of sufficient grain size and quality within available rock types, or, alternatively, the lack of available rock samples due to minimal outcrop exposure or other reasons, 2) economic considerations in terms of the time and money required to obtain sufficient AFT data, 3) the inherent limitations of AFT data to resolve geological thermal history information, often related to limited numbers of accumulated spontaneous fission tracks due to …

The Zinc-Finger Protein Zat12 Plays a Central Role in Reactive Oxygen and Abiotic Stress Signaling in Arabidopsis

Abstract: Plant acclimation to environmental stress is controlled by a complex network of regulatory genes that compose distinct stress-response regulons. In contrast to many signaling and regulatory genes that are stress specific, the zinc-finger protein Zat12 responds to a large number of biotic and abiotic stresses. Zat12 is thought to be involved in cold and oxidative stress signaling in Arabidopsis (Arabidopsis thaliana); however, its mode of action and regulation are largely unknown. Using a fusion between the Zat12 promoter and the reporter gene luciferase, we demonstrate that Zat12 expression is activated at the transcriptional level during different abiotic stresses and in response to a wound-induced systemic signal. Using Zat12 gain- and loss-of-function lines, we assign a function for Zat12 during oxidative, osmotic, salinity, high light, and heat stresses. Transcriptional profiling of Zat12-overexpressing plants and wild-type plants subjected to H2O2 stress revealed that constitutive expression of Zat12 in Arabidopsis results in the enhanced expression of oxidative- and light stress-response transcripts. Under specific growth conditions, Zat12 may therefore regulate a collection of transcripts involved in the response of Arabidopsis to high light and oxidative stress. Our results suggest that Zat12 plays a central role in reactive oxygen and abiotic stress signaling in Arabidopsis.

Balancing Ethical Responsibility among Multiple Organizational Stakeholders: The Islamic Perspective

Abstract: In spite of a renewed interest in the relationship between spirituality and managerial thinking, the literature covering the link between Islam and management has been sparse - especially in the area of ethics. One potential reason may be the cultural diversity of nearly 1.3 billion Muslims globally. Yet, one common element binding Muslim individuals and countries is normative Islam. Using all four sources of this religion's teachings, we outline the parameters of an Islamic model of normative business ethics. We explain how this ethics model seeks to balance the needs of multiple stakeholders, and discuss its enforcement mechanisms. This Islamic approach to business ethics is centered around criteria that are in common with stakeholder theory such as justice and balance, and includes unique additional criteria such as trust and benevolence.

Tandem Au-catalyzed 3,3-rearrangement-[2 + 2] cycloadditions of propargylic esters : Expeditious access to highly functionalized 2,3-indoline-fused cyclobutanes

Abstract: The treatment of readily available propargylic indole-3-acetates with a catalytic amount of AuCl(PPh3)/AgSbF6 leads to tandem activations of the propargylic esters and the in situ generated allenylic esters, resulting in expeditious access to highly functionalized cyclobutanes with fused 2,3-indoline and γ-lactone rings and an exocyclic E-double bond through sequential 3,3-rearrangement and [2 + 2] cyclization.

The Gambler’s Fallacy and the Hot Hand: Empirical Data from Casinos

Abstract: Research on decision making under uncertainty demonstrates that intuitive ideas of randomness depart systematically from the laws of chance. Two such departures involving random sequences of events have been documented in the laboratory, the gambler’s fallacy and the hot hand. This study presents results from the field, using videotapes of patrons gambling in a casino, to examine the existence and extent of these biases in naturalistic settings. We find small but significant biases in our population, consistent with those observed in the lab.

Plants, symbiosis and parasites: a calcium signalling connection

Abstract: A unique family of protein kinases has evolved with regulatory domains containing sequences that are related to Ca(2+)-binding EF-hands. In this family, the archetypal Ca(2+)-dependent protein kinases (CDPKs) have been found in plants and some protists, including the malarial parasite, Plasmodium falciparum. Recent genetic evidence has revealed isoform-specific functions for a CDPK that is essential for Plasmodium berghei gametogenesis, and for a related chimeric Ca(2+) and calmodulin-dependent protein kinase (CCaMK) that is essential to the formation of symbiotic nitrogen-fixing nodules in plants. In Arabidopsis thaliana, the analysis of 42 isoforms of CDPK and related kinases is expected to delineate Ca(2+) signalling pathways in all aspects of plant biology.

Seed removal, seed predation, and secondary dispersal

Abstract: Many studies of postdispersal seed fate use seed removal as an index of seed predation. However, following primary seed dispersal, some seeds are transported intact by ants, dung beetles, scatter-hoarding animals, or abiotic processes to new microsites (secondary dispersal) where germination is possible. Despite a growing realization that secondary seed dispersal can play an important role in plant recruitment, many researchers continue to use seed removal as a proxy for seed predation and are focused too intently on only the initial step of seed fate. We describe, using examples from the recent literature, how the results of some seed removal studies may have been misinterpreted, present plausible, alternative explanations for the fate of seeds in those studies, and discuss the importance of detailed studies of seed fates. Following the fates of seeds can be difficult, but such studies contribute much more to our understanding of seed dynamics and plant fitness.

Neural correlates of genetically abnormal social cognition in Williams syndrome

Abstract: Williams-Beuren syndrome (WBS), caused by a microdeletion of approximately 21 genes on chromosome 7q11.23, is characterized by unique hypersociability combined with increased non-social anxiety. Using functional neuroimaging, we found reduced amygdala activation in individuals with WBS for threatening faces but increased activation for threatening scenes, relative to matched normal controls. Activation and interactions of prefrontal regions linked to amygdala, especially orbitofrontal cortex, were abnormal, suggesting a genetically controlled neural circuitry for regulating human social behavior.

Control of Tamarix in the Western United States: implications for water salvage, wildlife use, and riparian restoration.

Abstract: Non-native shrub species in the genus Tamarix (saltcedar, tamarisk) have colonized hundreds of thousands of hectares of floodplains, reservoir margins, and other wetlands in western North America. Many resource managers seek to reduce saltcedar abundance and control its spread to increase the flow of water in streams that might otherwise be lost to evapotranspiration, to restore native riparian (streamside) vegetation, and to improve wildlife habitat. However, increased water yield might not always occur and has been substantially lower than expected in water salvage experiments, the potential for successful revegetation is variable, and not all wildlife taxa clearly prefer native plant habitats over saltcedar. As a result, there is considerable debate surrounding saltcedar control efforts. We review the literature on saltcedar control, water use, wildlife use, and riparian restoration to provide resource managers, researchers, and policy-makers with a balanced summary of the state of the science. To best ensure that the desired outcomes of removal programs are met, scientists and resource managers should use existing information and methodologies to carefully select and prioritize sites for removal, apply the most appropriate and cost-effective control methods, and then rigorously monitor control efficacy, revegetation success, water yield changes, and wildlife use.

First job experiences of recent RN graduates: improving the work environment.

Abstract: ObjectiveTo determine registered nurses' (RNs) perceptions of their first nursing position experience, and if they left the position, why.BackgroundLittle information is available regarding job perceptions of RNs in practice for 5 years or less. Nurses with negative perceptions of first job experien

On a Leray-α model of turbulence

Abstract: In this paper we introduce and study a new model for three–dimensional turbulence, the Leray– α model. This model is inspired by the Lagrangian averaged Navier–Stokes– α model of turbulence (also known Navier–Stokes– α model or the viscous Camassa–Holm equations). As in the case of the Lagrangian averaged Navier–Stokes– α model, the Leray– α model compares successfully with empirical data from turbulent channel and pipe flows, for a wide range of Reynolds numbers. We establish here an upper bound for the dimension of the global attractor (the number of degrees of freedom) of the Leray– α model of the order of ( L / l d ) 12/7 , where L is the size of the domain and l d is the dissipation length–scale. This upper bound is much smaller than what one would expect for three–dimensional models, i.e. ( L / l d ) 3 . This remarkable result suggests that the Leray– α model has a great potential to become a good sub–grid–scale large–eddy simulation model of turbulence. We support this observation by studying, analytically and computationally, the energy spectrum and show that in addition to the usual k −5/3 Kolmogorov power law the inertial range has a steeper power–law spectrum for wavenumbers larger than 1/ α . Finally, we propose a Prandtl–like boundary–layer model, induced by the Leray– α model, and show a very good agreement of this model with empirical data for turbulent boundary layers.

Relational frame theory, acceptance and commitment therapy, and a functional analytic definition of mindfulness

Abstract: The present article interprets mindfulness from the point of view of the effects of language and cognition on human action. Relational Frame Theory is described to show how human suffering is created by entanglement with the cognitive networks made possible by language. Mindfulness can be understood as a collection of related processes that function to undermine the dominance of verbal networks, especially involving temporal and evaluative relations. These processes include acceptance, defusion, contact with the present moment, and the transcendent sense of self. Each of these components of mindfulness are targeted in Acceptance and Commitment Therapy, and there is some evidence that they underlie the therapeutic changes induced by this approach. The relation between the present approach to mindfulness and other approaches is discussed.

Measuring Determinants of Student Return vs. Dropout/Stopout vs. Transfer: A First-to-Second Year Analysis of New Freshmen.

Abstract: To reflect academic challenges and enrollment patterns of today’s freshmen, this study measures the impact of high school preparation, first-year academic performance, multi-institution enrollment, and financial aid support on secondyear persistence. Using multi-year cohorts at a public research university, results confirm the importance of including first-year math experience, math intensity of the declared major, simultaneous enrollment at another college/university, and secondyear financial aid offers when measuring freshmen retention. The positive impact of a large-scale, state-funded scholarship program in widening access to college must be balanced against findings that show academic performance and readiness to take on and pass first-year math to be more important than aid in explaining freshmen dropout and transfer-out during both first and second semesters. Middleincome students with greater levels of unmet need face an elevated departure risk, while academically well-prepared freshmen with unmet need are more likely to transfer to other institutions.

The Goldman Consensus statement on depression in multiple sclerosis

Abstract: Background. In January 2002 the New York City Chapter of the National Multiple Sclerosis Society convened a panel of experts to review the issue of depressive affective disorders associated with multiple sclerosis (MS). This Consensus Conference was supported by a grant from the Goldman family of New York City. Results. The panel reviewed summaries of current epidemiologic, neurobiologic, and therapeutic studies having to do with depressive disorders among MS patient populations. Depressive disorders occur at high rates among patients with MS, and there is reason to believe that the immunopathology of the disease is involved in the clinical expression of affective disorders. The depressive syndromes of MS have a major, negative impact on quality of life for MS sufferers, but are treatable. At the present time, most MS patients with depression do not receive adequate recognition and treatment. Conclusions. The Goldman Consensus Conference Study Group provides recommendations for improved screening, diagnosis, and clinical management for depressive affective disorders among patients suffering from MS.

Enhanced Tolerance to Environmental Stress in Transgenic Plants Expressing the Transcriptional Coactivator Multiprotein Bridging Factor 1c

Abstract: Abiotic stresses cause extensive losses to agricultural production worldwide. Acclimation of plants to abiotic conditions such as drought, salinity, or heat is mediated by a complex network of transcription factors and other regulatory genes that control multiple defense enzymes, proteins, and pathways. Associated with the activity of different transcription factors are transcriptional coactivators that enhance their binding to the basal transcription machinery. Although the importance of stressresponse transcription factors was demonstrated in transgenic plants, little is known about the function of transcriptional coactivators associated with abiotic stresses. Here, we report that constitutive expression of the stress-response transcriptional coactivator multiprotein bridging factor 1c (MBF1c) in Arabidopsis (Arabidopsis thaliana) enhances the tolerance of transgenic plants to bacterial infection, heat, and osmotic stress. Moreover, the enhanced tolerance of transgenic plants to osmotic and heat stress was maintained even when these two stresses were combined. The expression of MBF1c in transgenic plants augmented the accumulation of a number of defense transcripts in response to heat stress. Transcriptome profiling and inhibitor studies suggest that MBF1c expression enhances the tolerance of transgenic plants to heat and osmotic stress by partially activating, or perturbing, the ethylene-response signal transduction pathway. Present findings suggest that MBF1 proteins could be used to enhance the tolerance of plants to different abiotic stresses.

Family interaction and the development of borderline personality disorder: a transactional model.

Abstract: Although no prospective epidemiological studies have evaluated the relationship between family interactions and the development of borderline personality disorder (BPD), there is considerable evidence for the central role of family interactions in the development of BPD. This paper describes the role of family interactions or processes, especially those that might be regarded as invalidating or conflictual, negative or critical, and the absence of more validating, positive, supportive, empathic interactions, in the development of BPD. Perhaps more importantly, the proposed model considers how these parental and family behaviors transact with the child's own behaviors and emotional vulnerabilities, resulting in a developmental model of BPD that is neither blaming of the family member with BPD nor of her or his parents and caregivers, and has important and specific implications for both prevention and intervention.

Estrogen-Plus-Progestin Use and Mammographic Density in Postmenopausal Women: Women's Health Initiative Randomized Trial

Abstract: BACKGROUND Increased mammographic density reduces the sensitivity of screening mammography, is associated with increased breast cancer risk, and may be hormone related. We assessed the effect of estrogen-plus-progestin therapy on mammographic density. METHODS In a racially and ethnically diverse ancillary study of the Women's Health Initiative, we examined data from 413 postmenopausal women who had been randomly assigned to receive daily combined conjugated equine estrogens (0.625 mg) plus medroxyprogesterone acetate (i.e., progestin; 2.5 mg) (n = 202) or daily placebo (n = 211). We assessed the effect of estrogen plus progestin on measured mammographic percent density and abnormal findings over a 1-year and 2-year period. All tests of statistical significance were two-sided and were based on F tests or t tests from mixed-effects models. RESULTS Mean mammographic percent density increased by 6.0% at year 1, compared with baseline, in the estrogen-plus-progestin group but decreased by 0.9% in the placebo group (difference = 6.9%, 95% confidence interval [CI] = 5.3% to 8.5%; P < .001). The mean changes in mammographic density persisted but were attenuated slightly after 2 years, with an absolute increase of 4.9% in the estrogen-plus-progestin group and a decrease of 0.8% in the placebo group (difference = 5.7%, 95% CI = 4.3% to 7.3%; P < .001). These effects were consistent across racial/ethnic groups but were higher among women aged 70-79 years in the estrogen-plus-progestin group (mean increase at year 1 = 11.6%) than in the placebo group (mean decrease at year 1 = 0.1%) (difference of the means = 11.7%, 95% CI = 8.2% to 15.4%; P < .001, comparing across age groups). At year 1, women who were adherent to treatment in the estrogen-plus-progestin group had a mean increase in density of 7.7% (95% CI = 5.9% to 9.5%), and women in the placebo group had a mean decrease in density of 1.1% (95% CI = 0.3% to 1.9%). Use of estrogen plus progestin was associated with an increased risk of having an abnormal mammogram at year 1 (relative risk = 3.9, 95% CI = 1.5 to 10.2; P = .003), compared with placebo, that was not explained by an increase in density. CONCLUSIONS Use of up to 2 years of estrogen plus progestin was associated with increases in mammographic density.

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.

Dynamics of electric fields driving the laser acceleration of multi-MeV protons.

Abstract: The acceleration of multi-MeV protons from the rear surface of thin solid foils irradiated by an intense ($\ensuremath{\sim}{10}^{18}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) and short ($\ensuremath{\sim}1.5\text{ }\text{ }\mathrm{ps}$) laser pulse has been investigated using transverse proton probing. The structure of the electric field driving the expansion of the proton beam has been resolved with high spatial and temporal resolution. The main features of the experimental observations, namely, an initial intense sheath field and a late time field peaking at the beam front, are consistent with the results from particle-in-cell and fluid simulations of thin plasma expansion into a vacuum.

Particle size and energetics of gouge from earthquake rupture zones

Abstract: Grain size reduction and gouge formation are found to be ubiquitous in brittle faults at all scales, and most slip along mature faults is observed to have been localized within gouge zones. This fine-grain gouge is thought to control earthquake instability, and thus understanding its properties is central to an understanding of the earthquake process. Here we show that gouge from the San Andreas fault, California, with approximately 160 km slip, and the rupture zone of a recent earthquake in a South African mine with only approximately 0.4 m slip, display similar characteristics, in that ultrafine grains approach the nanometre scale, gouge surface areas approach 80 m2 g(-1), and grain size distribution is non-fractal. These observations challenge the common perception that gouge texture is fractal and that gouge surface energy is a negligible contributor to the earthquake energy budget. We propose that the observed fine-grain gouge is not related to quasi-static cumulative slip, but is instead formed by dynamic rock pulverization during the propagation of a single earthquake.

Aeolian processes at the Mars Exploration Rover Meridiani Planum landing site.

Abstract: The cover shows part of the Larry's Lookout panorama, seen from the Mars Exploration Rover (MER) Spirit during its drive up Husband Hill: the summit is about 200 metres from the rover. Six papers this week report in detail on the MER mission. An Analysis compares predictions used to select a landing site with the conditions actually encountered. This ‘ground truth’ will be invaluable for interpreting future remote-sensing data. Surface chemistry suggests that the upper layer of soil may contain 1% meteoritic material. MER provides a unique glimpse of solar transits of the moons Phobos and Deimos. Rover Opportunity examined wind-related processes, and spectroscopy indicates a dry origin for atmospheric dust. Features from within the Gusev crater give more information on the role of liquid water in Mars's past. An accompanying News and Views puts the MER data in context. The martian surface is a natural laboratory for testing our understanding of the physics of aeolian (wind-related) processes in an environment different from that of Earth. Martian surface markings and atmospheric opacity are time-variable, indicating that fine particles at the surface are mobilized regularly by wind1,2,3. Regolith (unconsolidated surface material) at the Mars Exploration Rover Opportunity's landing site has been affected greatly by wind, which has created and reoriented bedforms, sorted grains, and eroded bedrock. Aeolian features here preserve a unique record of changing wind direction and wind strength. Here we present an in situ examination of a martian bright wind streak, which provides evidence consistent with a previously proposed formational model4,5 for such features. We also show that a widely used criterion for distinguishing between aeolian saltation- and suspension-dominated grain behaviour is different on Mars, and that estimated wind friction speeds between 2 and 3 m s-1, most recently from the northwest, are associated with recent global dust storms, providing ground truth for climate model predictions.