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Search Results: 1 - 10 of 300409 matches for " Victoria J. Dreitz "
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Mortality of Parental Mountain Plovers (Charadrius montanus) during the Post-hatching Stage.
Victoria J. Dreitz
Avian Conservation and Ecology , 2010,
Abstract: Monitoring, management, and conservation of grassland birds are topics of importance because of widespread population declines. Annual estimates of survival are available for many species, however knowledge of how survival varies on a seasonal basis remains poor. Information on the relative effects of breeding, overwintering, and migratory periods on population dynamics is necessary for effective management. Mortality risks often vary with the stage of the breeding cycle. In precocial species, mortality risks of adult birds are often higher during post-hatching care than prehatching. Using a multistate modeling approach, I investigated the influence of both environmental characteristics, measured by habitat, and individual characteristics, measured by sex and body mass, on post-hatching parental mortality of a declining grassland species, the Mountain Plover (Charadrius montanus). I found minimal evidence to support the effect of habitat, sex, or body mass on post-hatching parental mortality. Daily parental mortality was 0.0037 (SE = 0.0007, CI = 0.0026, 0.0053) and survival during the 30-day post-hatching period was 0.8943 (SE = 0.0187, CI = 0.8512, 0.9255). The findings from this study provide an understanding of the associations with today's grassland habitats and the dynamics of Mountain Plovers during the breeding season. Prior to assessing if alterations in habitats are acting more on post-hatching than the other stages of the annual cycle for the Mountain Plover, information on survival during other breeding stages and during migration is needed to assist in developing effective conservation and management plans.
Drought and Cooler Temperatures Are Associated with Higher Nest Survival in Mountain Plovers
Victoria J Dreitz,Reesa Yale Conrey,Susan K Skagen
Avian Conservation and Ecology , 2012,
Abstract: Native grasslands have been altered to a greater extent than any other biome in North America. The habitats and resources needed to support breeding performance of grassland birds endemic to prairie ecosystems are currently threatened by land management practices and impending climate change. Climate models for the Great Plains prairie region predict a future of hotter and drier summers with strong multiyear droughts and more frequent and severe precipitation events. We examined how fluctuations in weather conditions in eastern Colorado influenced nest survival of an avian species that has experienced recent population declines, the Mountain Plover (Charadrius montanus). Nest survival averaged 27.2% over a 7-yr period (n = 936 nests) and declined as the breeding season progressed. Nest survival was favored by dry conditions and cooler temperatures. Projected changes in regional precipitation patterns will likely influence nest survival, with positive influences of predicted declines in summer rainfall yet negative effects of more intense rain events. The interplay of climate change and land use practices within prairie ecosystems may result in Mountain Plovers shifting their distribution, changing local abundance, and adjusting fecundity to adapt to their changing environment.
An Assessment of Factors Affecting Population Growth of the Mountain Plover
Stephen J. Dinsmore,Michael B. Wunder,Victoria J. Dreitz,Fritz L. Knopf
Avian Conservation and Ecology , 2010,
Abstract: Effective conservation measures should target the most sensitive life history attributes of a species, assuming they are responsive to potential management actions. The Mountain Plover (Charadrius montanus) is a species of conservation concern with a patchy breeding distribution in western North America. Plovers prefer areas with short vegetation, bare ground, and disturbance for nesting. Current management tools, including grazing and burning, have been used to attract plovers and enhance nesting success. We used a stage-specific matrix model to study the influence of vital rates, e.g., juvenile and adult annual survival, on population growth rate in the Mountain Plover at two breeding sites in Colorado, South Park and Eastern Colorado, and one breeding site in Montana, USA. Our analysis was motivated by a need to 1) better understand the relationship between demographic rates and population growth rate, 2) assess current management tools for the plover by exploring their effect on population growth rate, and 3) identify areas of the plover's population biology where additional demographic work is needed. Stochastic population growth rate was most influenced by adult survival, especially in Montana and South Park, Colorado (elasticities > 0.60), and was least influenced by first-year reproduction (all elasticities < 0.20). The modeled relationships between lambda and each demographic rate were generally weak (r2 < 0.30) with the exception of number of eggs hatched per nest in Eastern Colorado (r2 = 0.63), chick survival in South Park (r2 = 0.40) and Montana (r2 = 0.38), and adult survival in Montana (r2 = 0.36). We examined the predicted increase in lambda that would result from increasing each demographic rate from its mean to the maximum value observed in our simulations. Chick and adult survival showed the greatest increase in lambda while eggs hatched per nest produced the smallest increase. Our results suggest that future conservation efforts should favor ways to increase adult or chick survival over efforts to increase nest success. In particular, adult survival rates during the stationary periods, i.e., summer and winter, are relatively high, implying that efforts to increase adult survival rates may need to focus on the migratory periods. Increasing chick survival should be a priority for efforts that are restricted to the breeding grounds because this life history stage is relatively short (< 3 mo) and it offers opportunities for targeted short-term management activities in breeding areas.
Monitoring programs to assess reintroduction efforts: a critical component in recovery
E. Muths,V. Dreitz
Animal Biodiversity and Conservation , 2008,
Abstract: Reintroduction is a powerful tool in our conservation toolbox. However, the necessary follow-up, i.e. long-term monitoring, is not commonplace and if instituted may lack rigor. We contend that valid monitoring is possible, even with sparse data. We present a means to monitor based on demographic data and a projection model using the Wyoming toad (Bufo baxteri) as an example. Using an iterative process, existing data is built upon gradually such that demographic estimates and subsequent inferences increase in reliability. Reintroduction and defensible monitoring may become increasingly relevant as the outlook for amphibians, especially in tropical regions, continues to deteriorate and emergency collection, captive breeding, and reintroduction become necessary. Rigorous use of appropriate modeling and an adaptive approach can validate the use of reintroduction and substantially increase its value to recovery programs.
MBDS Solvent: An Improved Method for Assessment of Biofilms  [PDF]
Greg Tram, Victoria Korolik, Christopher J. Day
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.32030

Biofilms are recognised as an important contributor to bacterial resistance towards traditional antimicrobial treatments. Assessment of biofilm formation currently relies on a 96 well microtitre plate assay, which usually involves the colourimetric detection of stain (typically crystal violet) removed from previously stained biofilm. The amount of crystal violet released is then used as a quantitative indicator of the amount of biofilm formed. Currently, this is achieved by solubilisation of the stain by ethanol which results in partial decolourisation of the crystal violet stained biofilm which impacts the accuracy and reproducibility of this method. Herein, we describe a modified biofilm dissolving solution (MBDS) which produces a more uniform and reproducible colour release from stained biofilm through solubilisation of the biofilm architecture itself. Here we use crystal violet stained biofilms of P. aeruginosa strain PA0-1, to demonstrate an approximate two fold increase in crystal violet release by MBDS, as compared to ethanol treatment. In addition, when ethanol decolourised biofilms were treated again with MBDS, an almost equal amount of remnant crystal violet was recovered by dissolving the biofilm and the stain trapped within it. These results were reflected in microscopic analysis of ethanol treated and MBDS treated biofilm. Similar results were obtained when MBDS was used to decolourise and dissolve the biofilms of a number of other bacterial species highlighting the advantages of MDBS as a universal solvent for the colour detection of biofilm.

Examination of Complementarity in Speech and Emotional Vocalization Perception  [PDF]
Victoria L. Harms, Lorin J. Elias
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.58098

Lateralization of cognitive functioning is a well-established principle of cerebral organization. The left and right hemispheres are known to play distinct and complementary roles in the processing of information. What is still unclear is whether these asymmetrically lateralized functions have a common or distinct developmental origin; are left and right processes lateralized through causal influences, or is the laterality of each function independently influenced? Left- and right-lateralized functions are commonly assessed in isolation, with little attention to the relationship in the degree and direction of lateralization within individuals. This relationship between left-hemisphere processing of speech sounds and right-hemisphere processing of emotional vocalizations was examined using dichotic listening tasks. An overall complementary pattern of lateralization was observed across participants, but no significant relationship was found for degree of lateralization of speech and emotional vocalization processing within individuals. These results support the view that functions in the left and right hemispheres are independently lateralized.

Mycoplasma hominis Variable Adherence-Associated Antigen: A Major Adhesin and Highly Variable Surface Membrane Protein  [PDF]
Rebecca J. Brown, Victoria J. Chalker, Owen B. Spiller
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.411080
Abstract: Mycoplasma hominis is a member of the genus mycoplasma and has only been isolated from humans. It is most frequently isolated from the urogenital tract in the absence of symptoms, but has been isolated from wounds, brain abscess, inflamed joints, blood and placenta from pregnancy with adverse outcomes (especially preterm birth and occasionally term stillbirth). Controversy surrounds whether this organism is a commensal or a pathogen; however, Mycoplasma hominis has been shown to induce preterm birth and foetal lung injury in an experimental primate model as a sole pathogen. These bacteria are known to exist as a parasitic infection, due to a number of missing synthetic and metabolism pathway enzymes from their minimal genome; therefore, the ability to adhere to host cells is important. Here we provide a review that clarifies the different nomenclature (variable adherence-associated antigen and P50) that has been used to investigate the major surface adhesin for this organism, as well as reported mechanisms responsible for turning off its expression. Variation in the structure of this protein can be used to separate strains into six categories, a method that we were able to use to distinguish and characterise 12 UK strains isolated from between 1983 and 2012. We propose that the Vaa should be used in further investigations to determine if commensal populations and those that are associated with disease utilise different forms of this adhesin, as this is under-studied and identification of pathogenic determinants is overdue for this organism.
Review Essay: Getting with the Act of Action Research Ensayo: Logrando el acto de la investigación acción Review Essay: Action Research und/als Handlung
Victoria J. Palmer
Forum : Qualitative Social Research , 2009,
Abstract: Action research (AR) prides itself on being a field of both theoretical and practical inquiry. Its scholarly identity rests heavily on framing participants as engaged, subjective, and participatory beings who learn and change through research processes. Yet, action research struggles to be considered a rigorous methodological field of inquiry and certainly there have been those who have raised questions about its validity as a research method. Where action research is used, qualifications and justifications abound as people struggle to have their research heard over other disciplines and techniques that claim more validity or appropriateness of methods. As a community development practitioner, I have employed AR approaches in the design and application of projects. As an academic, I have had the opportunity to design and facilitate meetings using participatory action research methods for data collection and to develop ground-up interventions with primary health care professionals. Therefore, I was eager to read about AR theoretical developments and to examine this text for its core purpose: as a "handbook" to guide research and practice. The handbook boasts 32 chapters covering theory, practices, exemplars, and skills which I reviewed with particular attention to where, how, and why I would use the content and whether it offered what a research handbook should—practical assistance in design, application, analysis, and synthesis for AR. Overall, the handbook does provide extensive examples about research projects and process. In future editions though, I would like to see more attention to complementary methods that can be employed in AR and attention to methods for the analysis of data generated via action research approaches. URN: urn:nbn:de:0114-fqs0903268 La investigación acción (IA) se enorgullece de ser un campo de investigación tanto teórico como práctico. Su identidad académica recae en gran medida en pensar a los participantes como seres participativos, subjetivos y comprometidos que aprenden y cambian a través de los procesos de la investigación. Sin embargo, la investigación acción lucha por ser considerado un campo riguroso de investigación metodológica y, desde luego, ha habido quienes han puesto en duda su validez como método de investigación. Allí donde se utiliza la investigación acción, las calificaciones y las justificaciones abundan en tanto que la gente lucha para que su investigación sea escuchada entre otras disciplinas y técnicas que proponen mejorar la validez y la idoneidad de los métodos. Como un profesional del desarrollo comuni
Elders in the shadow of the Big-Man
Victoria J. Baker
Bijdragen tot de Taal-, Land- en Volkenkunde , 1983,
Pitching a tent in the native village; Malinowski and participant observation
Victoria J. Baker
Bijdragen tot de Taal-, Land- en Volkenkunde , 1987,
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