3,062 research outputs found
Is the Urban Coyote a Misanthropic Synanthrope? The Case from Chicago
Coyotes appear to be one of the few mammalian carnivores that occur in urban areas, although their true relationship with urbanization remains poorly understood. We summarize results from a long-term study of the urban ecology of coyotes in the Chicago metropolitan area to determine the degree of synanthropy for this species and discuss the subsequent management implications for human-coyote conflicts. Local population densities were slightly higher, and survival rates for pups were five times higher compared to rural populations. In contrast to demographic patterns, behavioral responses to urbanization, including home range size, avoidance of developed land cover, activity budget, and diet, were not consistent with synanthropy, even for coyotes located in the urban matrix. We discuss the management implications of the paradoxical relationship coyotes have with people and cities
Investigating the accuracy of parallel analysis in underextraction conditions: A monte carlo study
One of the most important decisions to make when performing an exploratory factor analysis regards the number of factors to retain. Parallel analysis is considered to be the best course of action in these circumstances as it consistently outperforms other factor extraction methods (Zwick & Velicer, 1986). Even so, parallel analysis requires further research and refinement to improve its accuracy. Characteristics such as factor loadings, correlations between factors, and number of variables per factor all have been shown to adversely impact the effectiveness of parallel analysis as a means of identifying the number of factors. Critically, even the choice of criteria on which to evaluate factors such as the eigenvalue at the 50th or 95th percentile can have deleterious effects on the number of factors extracted. One area of parallel analysis yet to be researched is the magnitude of the difference between the actual eigenvalue and the random data-based eigenvalue. Currently, even if the margin between the actual eigenvalue and the random data-based eigenvalue is nominal, the factor is considered to be meaningful. As such, it may behoove researchers to enforce a higher standard, such as a greater margin between the two eigenvalues than just an absolute difference. Accordingly, the purpose of this study will be to evaluate the efficacy of a 10 percent margin criterion as compared to an absolute margin. These margins will specifically be evaluated in conjunction with the 50th, 90th, 95th, and 99th percentile eigenvalue criteria on a population correlation matrix which engenders underextraction. Previous research (Matsumoto & Brown, 2017) explored the same conditions on a population correlation matrix designed to cause overextraction. They found that the most stringent standard (99th percentile eigenvalue plus 10 percent margin) was the most accurate. For the present study however, we hypothesize that the most accurate results will be obtained from a standard less stringent than the 99th percentile eigenvalue plus 10 percent margin. This research has important implications for the scientific and practical application of psychometrics
Quantification of Lansoprazole in Oral Suspension by Ultra-High-Performance Liquid Chromatography Hybrid Ion-Trap Time-of-Flight Mass Spectrometry
An LC-MS/MS method was developed and validated to be used as a stability indicating assay for the study of a 3 mg/mL lansoprazole oral suspension. The method utilizes a UPLC (ultra-performance liquid chromatography) column and unique mass spectrometric detection (ion-trap time-of-flight (IT-TOF)) to achieve a sensitive (LOD 2 ng/mL), accurate, and reproducible quantification of lansoprazole. This method reports an intraday and interday coefficient of variation of 2.98 ± 2.17% (n = 5 for each concentration for each day) and 3.07 ± 0.89% (n = 20 for each concentration), respectively. Calibration curves (5–25 μg/mL) were found to be linear with an R2 value ranging from 0.9972 to 0.9991 on 4 different days. Accuracy of the assay, expressed as % error, ranged from 0.30 to 5.22%. This method is useful for monitoring the stability of lansoprazole in oral suspension
Dissecting a wildlife disease hotspot: the impact of multiple host species, environmental transmission and seasonality in migration, breeding and mortality
Avian influenza viruses (AIVs) have been implicated in all human influenza pandemics in recent history. Despite this, surprisingly little is known about the mechanisms underlying the maintenance and spread of these viruses in their natural bird reservoirs. Surveillance has identified an AIV ‘hotspot’ in shorebirds at Delaware Bay, in which prevalence is estimated to exceed other monitored sites by an order of magnitude. To better understand the factors that create an AIV hotspot, we developed and parametrized a mechanistic transmission model to study the simultaneous epizootiological impacts of multi-species transmission, seasonal breeding, host migration and mixed transmission routes. We scrutinized our model to examine the potential for an AIV hotspot to serve as a ‘gateway’ for the spread of novel viruses into North America. Our findings identify the conditions under which a novel influenza virus, if introduced into the system, could successfully invade and proliferate
Dissecting a wildlife disease hotspot: the impact of multiple host species, environmental transmission and seasonality in migration, breeding and mortality
Avian influenza viruses (AIVs) have been implicated in all human influenza pandemics in recent history. Despite this, surprisingly little is known about the mechanisms underlying the maintenance and spread of these viruses in their natural bird reservoirs. Surveillance has identified an AIV ‘hotspot’ in shorebirds at Delaware Bay, in which prevalence is estimated to exceed other monitored sites by an order of magnitude. To better understand the factors that create an AIV hotspot, we developed and parametrized a mechanistic transmission model to study the simultaneous epizootiological impacts of multi-species transmission, seasonal breeding, host migration and mixed transmission routes. We scrutinized our model to examine the potential for an AIV hotspot to serve as a ‘gateway’ for the spread of novel viruses into North America. Our findings identify the conditions under which a novel influenza virus, if introduced into the system, could successfully invade and proliferate
Ecology of an Isolated Muskrat Population During Regional Population Declines
Evidence indicating a decline in Ondatra zibethicus (Muskrat) populations in the United States during the past 40 years has led to speculation regarding factors influencing Muskrat survival. In order to understand population dynamics and survival, it is important to first define the ecology of local populations. We investigated the dwelling structure use, movements, home range, and survival of radio-tagged Muskrats (n = 14) in an urban wetland complex in central Pennsylvania. We used locations collected from intensive radio-telemetry monitoring to determine number of lodging structures used, hourly movement, and size and percent area overlap of home ranges. Muskrats shared an average of 9 lodging structures, and on average, 68% of a Muskrat’s home range overlapped home ranges of other Muskrats. We used 4 home-range estimators (kernel density estimator [KDE]href, KDEad hoc, KDEplug-in, and local convex hull estimator) to assess the ability of each estimator to represent Muskrat home ranges. The KDEplug-in that constrained the estimate of home range to habitat boundaries provided the most appropriate home-range size for Muskrats in a linear–non-linear habitat matrix. We also calculated overwinter survival estimates using known-fate models. Our top model indicated a positive effect of the average weekly precipitation on survival, with an overwinter survival estimate of 0.59 (SE = 0.16). The main cause of Muskrat mortality was predation by Neovison vison (American Mink; n = 6). The small sample size and uncertainty surrounding our model selection led to weak estimates of survival; however, our model suggests that snowfall may be an important factor in Muskrat survival. Our study provides novel data on Muskrat ecology in Pennsylvania as well as preliminary evidence for future investigations of factors affecting Muskrat survival during the winter months
Reconciling Epidemiology and Social Justice in the Public Health Discourse Around the Sexual Networks of Black Men Who Have Sex With Men
Several studies have implicated the sexual networks of Black men who have sex with men (MSM) as facilitating disproportionally high rates of new HIV infections within this community. Although structural disparities place these networks at heightened risk for infection, HIV prevention science continues to describe networks as the cause for HIV disparities, rather than an effect of structures that pattern infection. We explore the historical relationship between public health and Black MSM, arguing that the current articulation of Black MSM networks is too often incomplete and counterproductive. Public health can offer a counternarrative that reconciles epidemiology with the social justice that informs our discipline, and that is required for an effective response to the epidemic among Black MSM
Subtype diversity and reassortment potential for co‐circulating avian influenza viruses at a diversity hot spot
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106946/1/jane12167.pd
A statistical method to optimize the chemical etching process of zinc oxide thin films
Zinc oxide (ZnO) is an attractive material for microscale and nanoscale devices. Its desirable semiconductor, piezoelectric and optical properties make it useful in applications ranging from microphones to missile warning systems to biometric sensors. This work introduces a demonstration of blending statistics and chemical etching of thin films to identify the dominant factors and interaction between factors, and develop statistically enhanced models on etch rate and selectivity of c-axis-oriented nanocrystalline ZnO thin films. Over other mineral acids, ammonium chloride (NH4Cl) solutions have commonly been used to wet etch microscale ZnO devices because of their controllable etch rate and near-linear behaviour. Etchant concentration and temperature were found to have a significant effect on etch rate. Moreover, this is the first demonstration that has identified multi-factor interactions between temperature and concentration, and between temperature and agitation. A linear model was developed relating etch rate and its variance against these significant factors and multi-factor interactions. An average selectivity of 73 : 1 was measured with none of the experimental factors having a significant effect on the selectivity. This statistical study captures the significant variance observed by other researchers. Furthermore, it enables statistically enhanced microfabrication processes for other materials
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