1,314 research outputs found

    The Interaction of Organizational Culture and Change

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    Organizational culture and organizational change are two terms that are often studied and researched separately, however they are not often studied together. This paper discusses both organizational culture and organizational change apart from one another and also how they impact one another inside organizations. A case study organization was used to gather information on culture and change from senior leaders and also staff level employees. This data is compared and contrasted between the employee levels and also to relevant current research on culture and change. Based on this research and the interviews and focus groups used in the case study analysis, implications and recommendations are made to the case study organization on how to better implement changes by understanding the corporate culture, and vice versa

    Reactivity of Zinc Finger Cysteines: Chemical Modifications Within Labile Zinc Fingers in Estrogen Receptor

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    Estrogen receptor (ER, alpha isoform) is a 67 kDa zinc finger transcription factor that plays a fundamental role in both normal reproductive gland development and breast carcinogenesis, and also represents a critical molecular target for breast cancer therapy. We are investigating the structural consequences of chemical exposures thought to modify essential zinc finger cysteine residues in human ER. The current study employs mass spectrometry to probe ER zinc finger structural changes induced by a redox-reactive vitamin K3 analog, menadione; a commonly used cysteine alkylator, iodoacetic acid; and a thiol alkylating fluorophore, monobromobimane. Although they are slower to react, the sterically bulkier reagents, monobromobimane and menadione, effectively alkylate the most susceptible ER zinc finger cysteine sulfhydryl groups. Menadione arylation results first in Michael addition of the hydroquinone followed by rapid oxidation to the corresponding quinone, evidenced by a 2 Da mass loss per cysteine residue. Mass spectrometric analysis performed under MALDI conditions reveals both hydroquinone and quinone forms of arylated menadione, whereas only the quinone product is detectable under ESI conditions. Tandem mass spectrometry of a synthetic peptide encompassing the C-terminal half of the structurally more labile second zinc finger of ER (ZnF2B) demonstrates that the two nucleophilic thiols in ZnF2B (Cys-237, Cys-240) are not chemically equivalent in their reactivity to bromobimane or menadione, consistent with their unequal positioning near basic amino acids that affect thiol pKa, thereby rendering Cys-240 more reactive than Cys-237. These findings demonstrate important differential susceptibility of ER zinc finger cysteine residues to thiol reactions

    The elusive search for an effective repellent against voles: an assessment of anthraquinone for citrus crops

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    Vole (Cricetidae) girdling of tree trunks is a common form of damage experienced by tree and vine growers throughout much of the Northern Hemisphere. Management programs that effectively incorporate chemical repellents and vegetation management would be of substantial assistance to growers that experience such damage. Anthraquinone has proven effective as a repellent against voles in lab trials, yet controlled field tests of combined anthraquinone and vegetation management programs are lacking. Therefore, we established a mesocosm-based study in central California, USA, to test the efficacy of anthraquinone and vegetation management for reducing girdling damage caused by California voles Microtus californicus to Clementine citrus trees Citrus clementine under semi-field conditions. We observed a 90–100% reduction in girdling damage for trees following a single application of anthraquinone during two trials in summer and spring, respectively. Removal of vegetation around the base of trees further reduced damage during the summer sampling period, with no girdling observed on anthraquinone-treated trees that were surrounded by bare soil. We did not observe this same relationship during spring, and we observed no relationship between vegetation management in the absence of anthraquinone treatments in either seasonal trial, suggesting that vegetation management had a lesser impact on vole girdling than anthraquinone applications. We observed no decrease in efficacy of anthraquinone across the duration of both sampling periods (5–6 weeks), indicating substantial longevity for anthraquinone. Anthraquinone appears to have substantial utility for minimizing vole girdling damage. Field testing is warranted for additional mammalian species to determine potential uses for other taxa

    Repellent application strategy for wild rodents and cottontail rabbits

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    Effective chemical repellents and repellent application strategies are needed to manage damages caused by wild rodents and rabbits to agricultural resources. For the purpose of comparatively investigating the behavioral response of wild rodents and rabbits to a chemical repellent, we experimentally evaluated the concentration-response relationship of an anthraquinone-based repellent in California voles (Microtus californicus Peale), Richardson’s ground squirrels (Urocitellus richardsonii Sabine), deer mice (Peromyscus maniculatus Wagner) and cottontail rabbits (Sylvilagus audubonii Baird) in captivity. We observed 52–56% feeding repellency for whole oats treated with 10,800ppm anthraquinone or 18,500ppmanthraquinone in mice and squirrels, and 84–85% repellency for oats treated with 18,300ppm anthraquinone or 19,600ppm anthraquinone in voles and rabbits, respectively. In addition to providing the negative postingestive consequences necessary for conditioned food avoidance, the anthraquinonebased repellent also absorbs ultraviolet (UV) wavelengths that are visible to most wild birds. For the purpose of developing a repellent application strategy to modify the behavior of vertebrate pests, we therefore conducted a conditioned avoidance experiment by offering repellent- and UV-treated food to California voles in a subsequent behavioral assay. Relative to unconditioned test subjects (P = 0.3161), voles conditioned with the UV, postingestive repellent subsequently avoided whole oats treated only with an UV cue (P = 0.0109). These behavioral responses to anthraquinone-based repellents and UV feeding cues can be exploited as a repellent application strategy for wild mammals. We discuss potential applications of preplant seed treatments and surface treatments that include postingestive repellents and related visual cues for the protection of agricultural resources associated with mammalian depredation

    Repellent application strategy for wild rodents and cottontail rabbits

    Get PDF
    Effective chemical repellents and repellent application strategies are needed to manage damages caused by wild rodents and rabbits to agricultural resources. For the purpose of comparatively investigating the behavioral response of wild rodents and rabbits to a chemical repellent, we experimentally evaluated the concentration-response relationship of an anthraquinone-based repellent in California voles (Microtus californicus Peale), Richardson’s ground squirrels (Urocitellus richardsonii Sabine), deer mice (Peromyscus maniculatus Wagner) and cottontail rabbits (Sylvilagus audubonii Baird) in captivity. We observed 52–56% feeding repellency for whole oats treated with 10,800ppm anthraquinone or 18,500ppmanthraquinone in mice and squirrels, and 84–85% repellency for oats treated with 18,300ppm anthraquinone or 19,600ppm anthraquinone in voles and rabbits, respectively. In addition to providing the negative postingestive consequences necessary for conditioned food avoidance, the anthraquinonebased repellent also absorbs ultraviolet (UV) wavelengths that are visible to most wild birds. For the purpose of developing a repellent application strategy to modify the behavior of vertebrate pests, we therefore conducted a conditioned avoidance experiment by offering repellent- and UV-treated food to California voles in a subsequent behavioral assay. Relative to unconditioned test subjects (P = 0.3161), voles conditioned with the UV, postingestive repellent subsequently avoided whole oats treated only with an UV cue (P = 0.0109). These behavioral responses to anthraquinone-based repellents and UV feeding cues can be exploited as a repellent application strategy for wild mammals. We discuss potential applications of preplant seed treatments and surface treatments that include postingestive repellents and related visual cues for the protection of agricultural resources associated with mammalian depredation

    A framework for incorporating the toxicity of pesticide mixtures into ecological risk assessments

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    Pesticides are widely used throughout the Puget Sound region and are frequently detected as complex mixtures in aquatic habitats. As a result, pesticide mixture toxicity is an important component of risk assessments performed within the Salish Sea region. Here we describe a process for assessing toxicity of three categories of pesticide mixtures; formulated products (one product containing multiple active ingredients), tank mixes (multiple pesticides applied simultaneously), and environmental mixtures (resulting from unrelated pesticide use over the landscape). Mixtures were assumed to be either dose-additive or response-additive, depending on the modes of action of the individual pesticide components. Toxicity estimates utilized two main pieces of information - exposure concentrations and taxa-specific toxicity values. Exposure concentrations were either generated using EPA’s Pesticide Water Calculator (PWC), which incorporates chemical and application-specific parameters to calculate anticipated water concentrations over different durations, or utilized directly from routine monitoring studies. Standard measures of toxicity (typically the LC50, or the concentration that is lethal to 50% of the test organisms) were used to represent the sensitivity of different taxa groups to a given pesticide. We predicted toxicity for formulated products containing multiple pesticides, tank mixtures based on co-applications reported in California’s Pesticide Use Reporting System, and environmental mixtures identified in ambient water quality monitoring data from Washington State. Results show that estimating mixture toxicity is possible with currently available information, and these predictions can be used effectively in ecological risk assessments. Importantly, failing to consider mixtures may underestimate pesticide risk, leading to erroneous risk conclusions and ineffective protections for aquatic species and habitats

    An Optical Study of BG Geminorum: An Ellipsoidal Binary with an Unseen Primar Star

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    We describe optical photometric and spectroscopic observations of the bright variable BG Geminorum. Optical photometry shows a pronounced ellipsoidal variation of the K0 I secondary, with amplitudes of ~0.5 mag at VRI and a period of 91.645 days. A deep primary eclipse is visible for wavelengths < 4400A; a shallower secondary eclipse is present at longer wavelengths. Eclipse timings and the radial velocity curve of the K0 secondary star indicate an interacting binary where a lobe-filling secondary, M_2 ~ 0.5 Msun, transfers material into a extended disk around a massive primary, M_1 ~ 4.5 Msun. The primary star is either an early B-type star or a black hole. If it did contain a black hole, BG Gem would be the longest period black hole binary known by a factor of 10, as well as the only eclipsing black hole binary system.Comment: 27 pages, includes 8 figures and 5 tables, accepted to A

    Modeling Change in the Presence of Nonrandomly Missing Data: Evaluating a Shared Parameter Mixture Model

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    In longitudinal research, interest often centers on individual trajectories of change over time. When there is missing data, a concern is whether data are systematically missing as a function of the individual trajectories. Such a missing data process, termed random coefficient-dependent missingness, is statistically non-ignorable and can bias parameter estimates obtained from conventional growth models that assume missing data are missing at random. This paper describes a shared-parameter mixture model (SPMM) for testing the sensitivity of growth model parameter estimates to a random coefficient-dependent missingness mechanism. Simulations show that the SPMM recovers trajectory estimates as well as or better than a standard growth model across a range of missing data conditions. The paper concludes with practical advice for longitudinal data analysts

    Evaluating models for partially clustered designs.

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    Partially clustered designs, where clustering occurs in some conditions and not others, are common in psychology, particularly in prevention and intervention trials. This paper reports results from a simulation comparing five approaches for analyzing partially clustered data, including Type I errors, parameter bias, efficiency, and power. Results indicate that multilevel models adapted for partially clustered data are relatively unbiased and efficient and consistently maintain the nominal Type I error rate when using appropriate degrees of freedom. To attain sufficient power in partially clustered designs, researchers should attend primarily to the number of clusters in the study. An illustration is provided using data from a partially clustered eating disorder prevention trial
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