Showing papers by "University of Connecticut published in 2001"

Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness

Abstract: Species richness is a fundamental measurement of community and regional diversity, and it underlies many ecological models and conservation strategies. In spite of its importance, ecologists have not always appreciated the effects of abundance and sampling effort on richness measures and comparisons. We survey a series of common pitfalls in quantifying and comparing taxon richness. These pitfalls can be largely avoided by using accumulation and rarefaction curves, which may be based on either individuals or samples. These taxon sampling curves contain the basic information for valid richness comparisons, including category‐subcategory ratios (species-to-genus and species-toindividual ratios). Rarefaction methods ‐ both sample-based and individual-based ‐ allow for meaningful standardization and comparison of datasets. Standardizing data sets by area or sampling effort may produce very different results compared to standardizing by number of individuals collected, and it is not always clear which measure of diversity is more appropriate. Asymptotic richness estimators provide lower-bound estimates for taxon-rich groups such as tropical arthropods, in which observed richness rarely reaches an asymptote, despite intensive sampling. Recent examples of diversity studies of tropical trees, stream invertebrates, and herbaceous plants emphasize the importance of carefully quantifying species richness using taxon sampling curves.

A Temporally Based Framework and Taxonomy of Team Processes

Abstract: In this article we examine the meaning of team process. We first define team process in the context of a multiphase episodic framework related to goal accomplishment, arguing that teams are multitasking units that perform multiple processes simultaneously and sequentially to orchestrate goal-directed taskwork. We then advance a taxonomy of team process dimensions synthesized from previous research and theorizing. a taxonomy that reflects our time-based conceptual framework. We conclude with implications for future research and application.

A Likelihood Approach to Estimating Phylogeny from Discrete Morphological Character Data

Abstract: Evolutionary biologists have adopted simplelikelihood models for purposes of estimating ancestral states and evaluating character independence on specieed phylogenies; however, for pur- poses of estimating phylogenies byusing discrete morphological data, maximum parsimony remains the only option. This paper explores the possibility of using standard, well-behaved Markov models for estimating morphological phylogenies (including branch lengths) under the likelihood criterion. AnimportantmodiecationofstandardMarkovmodelsinvolvesmakingthelikelihoodconditionalon characters being variable, because constant characters are absent in morphological data sets. Without this modiecation, branch lengths are often overestimated, resulting in potentially serious biases in tree topology selection. Several new avenues of research are opened by an explicitly model-based approach to phylogenetic analysis of discrete morphological data, including combined-data likeli- hood analyses (morphologyCsequence data), likelihood ratio tests, and Bayesian analyses. (Discrete morphological character; Markov model; maximum likelihood; phylogeny.) The increased availability of nucleotide and protein sequences from a diversity of both organisms and genes has stimu- lated the development of stochastic models describing evolutionary change in molecu- lar sequences over time. Such models are not only useful for estimating molecular evolutionary parameters of interest but also important as the basis for phylogenetic inference using the method of maximum likelihood (ML) and Bayesian inference. ML provides a very general framework for esti- mation and has been extensively applied in diverse eelds of science (Casella and Berger, 1990); however, the popularity of ML in phylogenetic inference has lagged behind thatofotheroptimality criteria(suchas max- imum parsimony), primarily because of its much greater computational cost for evalu- ating any givencandidate tree.Recent devel- opments on the algorithmic aspects of ML inference as applied to phylogeny recon- struction (Olsen et al., 1994; Lewis, 1998; Salter and Pearl, 2001; Swofford, 2001) have succeeded in reducing this computational cost substantially, and ML phylogeny esti- mates involving hundreds of terminal taxa are now entering the realm of feasibility. Bayesian methods (based on a likelihood foundation) offer the prospect of obtaining meaningful nodal support measures with- out the unreasonable computational burden imposed by existing methods such as boot- strapping (Rannala and Yang, 1996; Yang and Rannala, 1997; Larget and Simon, 1999;

Predictors of postpartum depression: an update.

Abstract: Background Approximately 13% of women experience postpartum depression. Early recognition is one of the most difficult challenges with this mood disorder because of how covertly it is suffered. Objectives The purpose of this meta-analysis was to update the findings of an earlier meta-analysis of postpartum depression predictors that had synthesized the results of studies conducted mostly in the 1980s. Method A meta-analysis of 84 studies published in the decade of the 1990s was conducted to determine the magnitude of the relationships between postpartum depression and various risk factors. Using the software system Advanced Basic Meta-Analysis, effect sizes were calculated three ways: unweighted, weighted by sample size, and weighted by quality index score. Results Thirteen significant predictors of postpartum depression were revealed. Ten of the 13 risk factors had moderate effect sizes while three predictors had small effect sizes. The mean effect size indicator ranges for each risk factor were as follows: prenatal depression (.44 to .46), self esteem (.45 to. 47), childcare stress (.45 to .46), prenatal anxiety (.41 to .45), life stress (.38 to .40), social support (.36 to .41), marital relationship (.38 to .39), history of previous depression (.38 to .39), infant temperament (.33 to .34), maternity blues (.25 to .31), marital status (.21 to .35), socioeconomic status (.19 to .22), and unplanned/unwanted pregnancy (.14 to .17). Conclusions Results confirmed findings of an earlier meta-analysis and in addition revealed four new predictors of postpartum depression: self-esteem, marital status, socioeconomic status, and unplanned/unwanted pregnancy.

The Modified Checklist for Autism in Toddlers: an initial study investigating the early detection of autism and pervasive developmental disorders.

Abstract: Autism, a severe disorder of development, is difficult to detect in very young children. However, children who receive early intervention have improved long-term prognoses. The Modified Checklist for Autism in Toddlers (M-CHAT), consisting of 23 yes/no items, was used to screen 1,293 children. Of the 58 children given a diagnostic/developmental evaluation, 39 were diagnosed with a disorder on the autism spectrum. Six items pertaining to social relatedness and communication were found to have the best discriminability between children diagnosed with and without autism/PDD. Cutoff scores were created for the best items and the total checklist. Results indicate that the M-CHAT is a promising instrument for the early detection of autism.

Dipole blockade and quantum information processing in mesoscopic atomic ensembles.

Abstract: We describe a technique for manipulating quantum information stored in collective states of mesoscopic ensembles. Quantum processing is accomplished by optical excitation into states with strong dipole-dipole interactions. The resulting "dipole blockade" can be used to inhibit transitions into all but singly excited collective states. This can be employed for a controlled generation of collective atomic spin states as well as nonclassical photonic states and for scalable quantum logic gates. An example involving a cold Rydberg gas is analyzed.

Night Shift Work, Light at Night, and Risk of Breast Cancer

Abstract: Background Exposure to light at night may increase the risk of breast cancer by suppressing the normal nocturnal production of melatonin by the pineal gland, which, in turn, could increase the release of estrogen by the ovaries. This study investigated whether such exposure is associated with an increased risk of breast cancer in women. Methods Case patients (n = 813), aged 20-74 years, were diagnosed from November 1992 through March 1995; control subjects (n = 793) were identified by random-digit dialing and were frequency matched according to 5-year age groups. An in-person interview was used to gather information on sleep habits and bedroom lighting environment in the 10 years before diagnosis and lifetime occupational history. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by use of conditional logistic regression, with adjustment for other potential risk factors. Results Breast cancer risk was increased among subjects who frequently did not sleep during the period of the night when melatonin levels are typically at their highest (OR = 1.14 for each night per week; 95% CI = 1.01 to 1.28). Risk did not increase with interrupted sleep accompanied by turning on a light. There was an indication of increased risk among subjects with the brightest bedrooms. Graveyard shiftwork was associated with increased breast cancer risk (OR = 1.6; 95% CI = 1.0 to 2.5), with a trend of increased risk with increasing years and with more hours per week of graveyard shiftwork (P =.02, Wald chi-squared test). Conclusion The results of this study provide evidence that indicators of exposure to light at night may be associated with the risk of developing breast cancer.

Drought- and salt-tolerant plants result from overexpression of the AVP1 H+-pump

Abstract: Transgenic plants overexpressing the vacuolar H+-pyrophosphatase are much more resistant to high concentrations of NaCl and to water deprivation than the isogenic wild-type strains. These transgenic plants accumulate more Na+ and K+ in their leaf tissue than the wild type. Moreover, direct measurements on isolated vacuolar membrane vesicles derived from the AVP1 transgenic plants and from wild type demonstrate that the vesicles from the transgenic plants have enhanced cation uptake. The phenotypes of the AVP1 transgenic plants suggest that increasing the vacuolar proton gradient results in increased solute accumulation and water retention. Presumably, sequestration of cations in the vacuole reduces their toxic effects. Genetically engineered drought- and salt-tolerant plants could provide an avenue to the reclamation of farmlands lost to agriculture because of salinity and a lack of rainfall.

Mammalian Photoperiodic System: Formal Properties and Neuroendocrine Mechanisms of Photoperiodic Time Measurement

Abstract: Photoperiodism is a process whereby organisms are able to use both absolute measures of day length and the direction of day length change as a basis for regulating seasonal changes in physiology an...

Prospective time periodic geographical disease surveillance using a scan statistic

Abstract: Most disease registries are updated at least yearly. If a geographically localized health hazard suddenly occurs, we would like to have a surveillance system in place that can pick up a new geographical disease cluster as quickly as possible, irrespective of its location and size. At the same time, we want to minimize the number of false alarms By using a space-time scan statistic, we propose and illustrate a system for regular time periodic disease surveillance to detect any currently active' geographical clusters of disease and which tests the statistical significance of such clusters adjusting for the multitude of possible geographical locations and sizes, time intervals and time periodic analyses. The method is illustrated on thyroid cancer among men in New Mexico 1973-1992.

Thermal conductivity of dense and porous yttria-stabilized zirconia

Abstract: The thermal conductivity of dense and porous yttria-stabilized zirconia (YSZ) ceramics has been measured as a function of temperature in the range 25 to 1000 °C The dense specimens were either single crystal (8 mol% YSZ) or sintered polycrystalline (3 mol% and 8 mol% YSZ) The porous specimens (3 mol% YSZ) were prepared using the “fugitive” polymer method, where different amounts of polymer spheres (of two different average sizes) were included in the starting powders before sintering This method yielded materials with uniformly distributed porosities with a tight pore-size distributions A theory has been developed to describe the thermal conductivity of dense YSZ as a function of temperature This theory considers the reduction in the intrinsic thermal conductivity due scattering of phonons by point defects (oxygen vacancies and solute) and by the “hopping” of oxygen vacancies It also considers an increase in the effective thermal conductivity at high temperatures due to radiation This theory captures the essential features of the observed thermal conductivity The Maxwell theory has been used to analyze the thermal conductivity of the porous materials An adequate agreement was found between the theory and experiment

African Americans and High Blood Pressure: The Role of Stereotype Threat:

Abstract: We examined the effect of stereotype threat on blood pressure reactivity. Compared with European Americans, and African Americans under little or no stereotype threat, African Americans under stereotype threat exhibited larger increases in mean arterial blood pressure during an academic test, and performed more poorly on difficult test items. We discuss the significance of these findings for understanding the incidence of hypertension among African Americans.

Integrating seaweeds into marine aquaculture systems: a key toward sustainability

Abstract: The rapid development of intensive fed aquaculture (e.g. finfish and shrimp) throughout the world is associated with concerns about the environmental impacts of such often monospecific practices, especially where activities are highly geographically concentrated or located in suboptimal sites whose assimilative capacity is poorly understood and, consequently, prone to being exceeded. One of the main environmental issues is the direct discharge of significant nutrient loads into coastal waters from open-water systems and with the effluents from land-based systems. In its search for best management practices, the aquaculture industry should develop innovative and responsible practices that optimize its efficiency and create diversification, while ensuring the remediation of the consequences of its activities to maintain the health of coastal waters. To avoid pronounced shifts in coastal processes, conversion, not dilution, is a common-sense solution, used for centuries in Asian countries. By integrating fed aquaculture (finfish, shrimp) with inorganic and organic extractive aquaculture (seaweed and shellfish), the wastes of one resource user become a resource (fertilizer or food) for the others. Such a balanced ecosystem approach provides nutrient bioremediation capability, mutual benefits to the cocultured organisms, economic diversification by producing other value-added marine crops, and increased profitability per cultivation unit for the aquaculture industry. Moreover, as guidelines and regulations on aquaculture effluents are forthcoming in several countries, using appropriately selected seaweeds as renewable biological nutrient scrubbers represents a cost-effective means for reaching compliance by reducing the internalization of the total environmental costs. By adopting integrated polytrophic practices, the aquaculture industry should find increasing environmental, economic, and social acceptability and become a full and sustainable partner within the development of integrated coastal management frameworks.

Development and validation of a prognostic index for 1-year mortality in older adults after hospitalization.

Abstract: ContextFor many elderly patients, an acute medical illness requiring hospitalization is followed by a progressive decline, resulting in high rates of mortality in this population during the year following discharge. However, few prognostic indices have focused on predicting posthospital mortality in older adults.ObjectiveTo develop and validate a prognostic index for 1 year mortality of older adults after hospital discharge using information readily available at discharge.DesignData analyses derived from 2 prospective studies with 1-year of follow-up, conducted in 1993 through 1997.Setting and PatientsWe developed the prognostic index in 1495 patients aged at least 70 years who were discharged from a general medical service at a tertiary care hospital (mean age, 81 years; 67% female) and validated it in 1427 patients discharged from a separate community teaching hospital (mean age, 79 years; 61% female).Main Outcome MeasurePrediction of 1-year mortality using risk factors such as demographic characteristics, activities of daily living (ADL) dependency, comorbid conditions, length of hospital stay, and laboratory measurements.ResultsIn the derivation cohort, 6 independent risk factors for mortality were identified and weighted using logistic regression: male sex (1 point); number of dependent ADLs at discharge (1-4 ADLs, 2 points; all 5 ADLs, 5 points); congestive heart failure (2 points); cancer (solitary, 3 points; metastatic, 8 points); creatinine level higher than 3.0 mg/dL (265 µmol/L) (2 points); and low albumin level (3.0-3.4 g/dL, 1 point; <3.0 g/dL, 2 points). Several variables associated with 1-year mortality in bivariable analyses, such as age and dementia, were not independently associated with mortality after adjustment for functional status. We calculated risk scores for patients by adding the points of each independent risk factor present. In the derivation cohort, 1-year mortality was 13% in the lowest-risk group (0-1 point), 20% in the group with 2 or 3 points, 37% in the group with 4 to 6 points, and 68% in the highest-risk group (>6 points). In the validation cohort, 1-year mortality was 4% in the lowest-risk group, 19% in the group with 2 or 3 points, 34% in the group with 4 to 6 points, and 64% in the highest-risk group. The area under the receiver operating characteristic curve for the point system was 0.75 in the derivation cohort and 0.79 in the validation cohort.ConclusionsOur prognostic index, which used 6 risk factors known at discharge and a simple additive point system to stratify medical patients 70 years or older according to 1-year mortality after hospitalization, had good discrimination and calibration and generalized well in an independent sample of patients at a different site. These characteristics suggest that our index may be useful for clinical care and risk adjustment.

Cultural Trauma: Slavery and the Formation of African American Identity

Abstract: In this book, Ron Eyerman explores the formation of the African-American identity through the theory of cultural trauma. The trauma in question is slavery, not as an institution or as personal experience, but as collective memory: a pervasive remembrance that grounded a people's sense of itself. Combining a broad narrative sweep with more detailed studies of important events and individuals, Eyerman reaches from Emancipation through the Harlem Renaissance, the Depression, the New Deal and the Second World War to the Civil Rights movement and beyond. He offers insights into the intellectual and generational conflicts of identity-formation which have a truly universal significance, as well as providing a compelling account of the birth of African-American identity. Anyone interested in questions of assimilation, multiculturalism and postcolonialism will find this book indispensable.

The microbiology of primary dental caries in humans.

Abstract: A systematic literature review from 1966 to 2000 revealed 2,730 English-language publications on the role of bacteria in human primary dental caries in vivo. The most pertinent 313 papers were analyzed in evidence tables accessible online (http://www.nidcr.nih.gov). The search targeted all bacterial types implicated previously in caries and asked two questions. First, what is the association of specific bacteria with tooth decay and can causation be attributed to any of those bacteria? Retrieved studies were categorized as randomized-blinded-interventional, longitudinal, case-control, and cross-sectional and were weighted in descending order in terms of significance. Although many studies, due to ethical requirements, had confounding variables, they still indicate strongly: 1) the central role of the mutans streptococci in initiation of caries of smooth surfaces and fissures of crowns of teeth and suggests their potent role in induction of root surface caries; and 2) that lactobacilli are implicated as important contributory bacteria in tooth decay, but their role in induction of lesions is not well supported. Second, what is the source of infection by cariogenic bacteria? Molecular/genetic studies of implicated bacteria isolated from humans, randomized-blinded-interventional, and longitudinal studies indicate that mutans streptococci are spread vertically among humans, mostly from mothers to their children. Implications of these conclusions are briefly discussed. The most significant problems of literature interpretation include the benefits/shortcomings of salivary and plaque monitoring of the flora, the role of sugar(s) in decay as it influences the flora, and modeling strategies to predict lesion score increments as distinct from determination of the etiological role of specific bacteria. Future directions for microbiological clinical caries research are suggested, and the use of the term "caries" to describe the disease, not its lesions, is urged.

Evidence from Auditors about Managers' and Auditors' Earnings-Management Decisions

Abstract: We report survey evidence about 515 experiences that auditors have had with clients who they identified as attempting to manage earnings. This approach enables us to analyze separately managers' decisions about how to attempt earnings management ("EM") and auditors' decisions about whether or not to waive adjustment of managers' earnings-management attempts ("EMAs"). We provide evidence that the likelihood that managers make EMAs (and auditors waive adjustment of EMAs) that involve transaction structuring varies with the precision of the related accounting standards. Managers tend to make EMAs that increase current-year income, but auditors are less likely to waive EMAs that increase current-year income. Managers are more likely to make EMAs that decrease current-year income with unstructured transactions and/or when standards are imprecise (presumably because the resulting "cookie jar reserves" are easier to harvest in future years if structuring is not necessary or the relevant standards are flexible). Auditors are more likely to waive EMAs that they identify as immaterial or that are attempted by large clients. These variables combine to affect the areas in which EMAs are attempted and waived to become EM in the audited financial statements.

The impact of 'bursting' thalamic impulses at a neocortical synapse

Abstract: Considerable effort has gone into understanding the mechanisms underlying high-frequency 'bursting' of thalamocortical impulses, their sensory information content and their involvement in perception. However, little is known about the influence of such impulses on their cortical targets. Here we follow bursting thalamic impulses to their terminus at the thalamocortical synapse of the awake rabbit, and examine their influence on a class of somatosensory cortical neurons. We show that thalamic bursts potently activate cortical circuits. Initial impulses of each burst have a greatly enhanced ability to elicit cortical action potentials, and later impulses in the burst further raise the probability of eliciting spikes. In some cases, multiple cortical spikes result from a single burst. Moreover, we show that the interval preceding each burst is crucial for generating the enhanced cortical response. The powerful activation of neocortex by thalamocortical bursts is fully consistent with an involvement of these impulses in perceptual/attentional processes.

Small‐rodent dynamics and predation

Abstract: The hypothesis that the regular multiannual population oscillations of boreal and arctic small rodents (voles and lemmings) are driven by predation is as old as the scientific study of rodent cycles itself Subsequently, for several decades, the predation hypothesis fell into disrepute, possibly because the views about predation and rodent dy- namics were too simplistic Here we review the work that has been done on the predation hypothesis primarily in Fennoscandia over the past decade Models of predator-prey interaction have been constructed for the least weasel (Mustela nivalis) and the field vole (Microtus agrestis), which are considered to be the key specialist predator and the key prey species in the multispecies communities in the boreal forest region in Fennoscandia The basic model has been parameterized with independent field data, and it predicts well the main features of the observed dynamics An extension of the model also including generalist and nomadic avian predators predicts correctly the well- documented and striking geographic gradient in rodent oscillations in Fennoscandia, with the amplitude and cycle period decreasing from north to south These geographic changes are attributed to the observed latitudinal change in the density of generalist and nomadic predators, which are expected to have a stabilizing effect on rodent dynamics We review the other observational, modeling, and experimental results bearing on the predation hypothesis and conclude that it accounts well for the broad patterns in rodent oscillations in Fennoscandia We discuss the application of the predation hypothesis to other regions in the northern hemisphere The predation hypothesis does not make predictions about multiannual and latitudinal changes in body size, behavior, and demography of ro- dents, which may have some population-dynamic consequences With the current evidence, however, we consider it unlikely that the phenotypic and genotypic composition of pop- ulations would be instrumental for generating the broad patterns in rodent oscillations

Racial and Ethnic Differences in Advanced-Stage Prostate Cancer: the Prostate Cancer Outcomes Study

Abstract: Background African-Americans have twice the risk of non-Hispanic whites for presenting with advanced-stage prostate cancer. To investigate the reasons for this difference, we evaluated the association between race/ethnicity and advanced-stage prostate cancer, adjusting for demographic, socioeconomic, clinical, and pathologic factors. Methods A population-based cohort of 3173 men diagnosed with prostate cancer between October 1, 1994, and October 31, 1995, was analyzed. Medical record abstracts and self-administered survey questionnaires were used to obtain information regarding race/ethnicity, age, marital status, insurance status, educational level, household income, employment status, comorbidity, urinary function, prostate-specific antigen level, tumor grade, and clinical stage. The odds ratio (OR) for advanced-stage prostate cancer was estimated with weighted logistic regression analysis. All P: values were two-sided. Results Clinically advanced-stage prostate cancers were detected more frequently in African-Americans (12.3%) and Hispanics (10.5%) than in non-Hispanic whites (6.3%). Socioeconomic, clinical, and pathologic factors each accounted for about 15% of the increased relative risk. After adjusting for all covariates, the risk remained statistically significantly increased for African-Americans (OR = 2.26; 95% confidence interval [CI] = 1.43 to 3.58) but not for Hispanics (OR = 1.23; 95% CI = 0.73 to 2.08). Conclusion Traditional socioeconomic, clinical, and pathologic factors accounted for the increased relative risk for presenting with advanced-stage prostate cancer in Hispanic but not in African-American men.

CB2 cannabinoid receptor-mediated peripheral antinociception.

Abstract: Cannabinoid receptor agonists diminish responses to painful stimuli. Extensive evidence implicates the CB(1) receptor in the production of antinociception. However, the capacity of CB(2) receptors, which are located outside the central nervous system (CNS), to produce antinociception is not known. Using AM1241, a CB(2) receptor-selective agonist, we demonstrate that CB(2) receptors produce antinociception to thermal stimuli. Injection of AM1241 in the hindpaw produced antinociception to a stimulus applied to the same paw. Injection of an equivalent dose of AM1241 into the paw contralateral to the side of testing did not. The antinociceptive actions of AM1241 were blocked by the CB(2) receptor-selective antagonist AM630, but not by the CB(1) receptor-selective antagonist AM251. AM1241 also produced antinociception when injected systemically (intraperitoneally). The antinociceptive actions of systemic AM1241 were blocked by injection of AM630 into the paw where the thermal stimulus was applied, but not the contralateral paw. These findings demonstrate the local, peripheral nature of CB(2) cannabinoid antinociception. AM1241 did not produce the CNS cannabinoid effects of hypothermia, catalepsy, inhibition of activity or impaired ambulation, while this tetrad of effects was produced by the mixed CB(1)/CB(2) receptor agonist WIN55,212-2. Peripheral antinociception without CNS effects is consistent with the peripheral distribution of CB(2) receptors. CB(2) receptor agonists may have promise clinically for the treatment of pain without CNS cannabinoid side effects.

Approaches to the study of territory size and shape

Abstract: ▪ Abstract Intraspecific variation in territory size and shape can have strong effects on population structure and dynamics. The traditional theoretical approach to the study of territory size is based on optimality models that analyze decisions of focal residents as responses to the costs and benefits of defense. These models have stimulated numerous empirical studies showing that territory holders adjust their behavior according to rates of intrusion and availability of food. However, models of optimal territory size are applicable only in limited circumstances because they focus on unilateral decisions rather than on interactions. Furthermore, observational and experimental studies often find that territory sizes are insensitive to food supply. Recently, greater emphasis has been placed on two alternative approaches. The first concerns interactions among contiguous neighbors and how these affect use of space. In these models territory size and shape are determined by the balance of pressure exerted at ...