Spatial variation in soil inorganic nitrogen across an arid urban ecosystem

We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO₃-N and NH₄-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO₃-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH₄-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO₃-N and NH₄-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO₃-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.     

Differences in preferred level of arousal in two sub-groups of problem gamblers: A preliminary report

Twelve problem poker machine players and thirteen horse race gamblers (20 males and 5 females; age range 28–69) completed a series of questionnaires which assessed levels of anxiety, their preferred state of arousal and their motivations to gamble. As predicted, problem poker machine gamblers were found to be more anxious and reported avoiding arousal more frequently than the horse race gamblers. Alternately, problem horse race gamblers were found to prefer heightened levels of arousal and appeared to gamble to achieve these optimal levels of arousal. However, there was no difference between the groups on proneness to boredom. The present results provide evidence which is consistent with the Reversal theory and its application to the field of problem gambling.     

Cognitive and behavioral therapies for pathological gambling

The purpose of this paper is to provide an overview of behavioral and cognitive treatment approaches in the management of pathological gambling disorders. Disappointingly, the literature to date contains only one controlled outcome study in which two differing behavioral techniques were compared. Although research in general has focussed on identifying the nature of cognitive distortions in gambling, findings from these studies have not been systematically translated into treatment programs. It is concluded that methodological limitations including small sample size, absence of control groups, multiple concurrent interventions and poorly defined outcome criteria preclude conclusive statements to be drawn regarding the active ingredient of either behavioral or cognitive strategies. The program offered within the Impulse Disorders Research Centre is outlined.The authors wish to gratefully acknowledge the assistance and contribution of Zachary Steel, Research Assistant, in the preparation of this paper.     

Statistical methods for the analysis of high-throughput data based on functional profiles derived from the Gene Ontology

The increasing availability of high-throughput data, that is, massive quantities of molecular biology data arising from different types of experiments such as gene expression or protein microarrays, leads to the necessity of methods for summarizing the available information. As annotation quality improves it is becoming common to rely on biological annotation databases, such as the Gene Ontology (GO), to build functional profiles which characterize a set of genes or proteins using the distribution of their annotations in the database. In this work we describe a statistical model for such profiles, provide methods to compare profiles and develop inferential procedures to assess this comparison. An R-package implementing the methods will be available at publication time.     

Predicting infectious disease outbreak risk via migratory waterfowl vectors

The spread of an emerging infectious disease is a major public health threat. Given the uncertainties associated with vector-borne diseases, in terms of vector dynamics and disease transmission, it is critical to develop statistical models that address how and when such an infectious disease could spread throughout a region such as the USA. This paper considers a spatio-temporal statistical model for how an infectious disease could be carried into the USA by migratory waterfowl vectors during their seasonal migration and, ultimately, the risk of transmission of such a disease to domestic fowl. Modeling spatio-temporal data of this type is inherently difficult given the uncertainty associated with observations, complexity of the dynamics, high dimensionality of the underlying process, and the presence of excessive zeros. In particular, the spatio-temporal dynamics of the waterfowl migration are developed by way of a two-tiered functional temporal and spatial dimension reduction procedure that captures spatial and seasonal trends, as well as regional dynamics. Furthermore, the model relates the migration to a population of poultry farms that are known to be susceptible to such diseases, and is one of the possible avenues toward transmission to domestic poultry and humans. The result is a predictive distribution of those counties containing poultry farms that are at the greatest risk of having the infectious disease infiltrate their flocks assuming that the migratory population was infected. The model naturally fits into the hierarchical Bayesian framework.     

The poisson-inverse gaussian disiribuiion as a model for species abundance

An inverse Gaussian mixture of Poisson distributions(the P-IG distribution) is considered as a model for species abundance data,, Minimum chi-square and maximum likelihood methods of estimation for the zero-truncated P-IG distribution are developed, Ihe performance of the P-IG distribution is illustrated and discussed for several well-known sets of insect abundance data.     

Advances in the surgical management of prolapse

Prolapse is an extremely common condition, for which 11% of women will have a surgical procedure at some point in their lives. The recurrence rate after most of the traditional surgical procedures is high and upto 29% of women who have had surgery for prolapse will require a further operation. In order to improve the surgical outcome, there is currently much interest in the use of grafts to augment traditional repairs and new procedures have been developed using specifically developed grafts. These have been combined with minimally invasive surgical techniques in an attempt to reduce surgical morbidity. These procedures may improve the outcome of surgery for prolapse. However, there is currently a lack of long-term data from randomized trials to demonstrate their effectiveness and safety.     

Who will change the “baby?” Examining the power of gender in an experimental setting

We conduct an experiment designed to test the impact of a gender-loaded frame on the distribution of labor between care and market work. In an unframed tre