Showing papers by "University of Connecticut published in 2004"

A new statistical approach for assessing similarity of species composition with incidence and abundance data

Abstract: The classic Jaccard and Sorensen indices of compositional similarity (and other indices that depend upon the same variables) are notoriously sensitive to sample size, especially for assemblages with numerous rare species. Further, because these indices are based solely on presence–absence data, accurate estimators for them are unattainable. We provide a probabilistic derivation for the classic, incidence-based forms of these indices and extend this approach to formulate new Jaccard-type or Sorensen-type indices based on species abundance data. We then propose estimators for these indices that include the effect of unseen shared species, based on either (replicated) incidence- or abundancebased sample data. In sampling simulations, these new estimators prove to be considerably less biased than classic indices when a substantial proportion of species are missing from samples. Based on species-rich empirical datasets, we show how incorporating the effect of unseen shared species not only increases accuracy but also can change the interpretation of results.

Interpolating, extrapolating, and comparing incidence-based species accumulation curves

Abstract: A general binomial mixture model is proposed for the species accumulation function based on presence-absence (incidence) of species in a sample of quadrats or other sampling units. The model covers interpolation between zero and the observed number of samples, as well as extrapolation beyond the observed sample set. For interpolation (sample- based rarefaction), easily calculated, closed-form expressions for both expected richness and its confidence limits are developed (using the method of moments) that completely eliminate the need for resampling methods and permit direct statistical comparison of richness between sample sets. An incidence-based form of the Coleman (random-placement) model is developed and compared with the moment-based interpolation method. For ex- trapolation beyond the empirical sample set (and simultaneously, as an alternative method of interpolation), a likelihood-based estimator with a bootstrap confidence interval is de- scribed that relies on a sequential, AIC-guided algorithm to fit the mixture model parameters. Both the moment-based and likelihood-based estimators are illustrated with data sets for temperate birds and tropical seeds, ants, and trees. The moment-based estimator is confi- dently recommended for interpolation (sample-based rarefaction). For extrapolation, the likelihood-based estimator performs well for doubling or tripling the number of empirical samples, but it is not reliable for estimating the richness asymptote. The sensitivity of individual-based and sample-based rarefaction to spatial (or temporal) patchiness is dis- cussed.

What leaders need to know: a review of social and contextual factors that can foster or hinder creativity

Abstract: This article provides a current review of research examining contextual factors that can either foster or hinder employee creativity at the individual, job, group, and organizational level. Specifically, we examine the role of leadership and the use of different human resource practices for developing a work context that is supportive of creativity. Finally, based on our review, we discuss practical implications for managers, propose areas that need further research attention, and highlight possible new directions for future research.

The rights of others : aliens, residents, and citizens

Abstract: Introduction 1. On hospitality: rereading Kant's cosmopolitan doctrine 2. 'The right to have rights': Hannah Arendt and the contradictions of the nation-state 3. The law of peoples, distributive justice and migrations 4. Transformations of citizenship: the case of the European Union 5. Democratic iterations: the local, the national and the global Conclusion References Index.

Fundamentals of resistance training: progression and exercise prescription.

Abstract: KRAEMER, W. J., and N. A. RATAMESS. Fundamentals of Resistance Training: Progression and Exercise Prescription. Med. Sci. Sports Exerc., Vol. 36, No. 4, pp. 674–688, 2004. Progression in resistance training is a dynamic process that requires an exercise prescription process, evaluation of tr

Measuring Marketing Productivity: Current Knowledge and Future Directions:

Abstract: For too long, marketers have not been held accountable for showing how marketing expenditures add to shareholder value. As time has gone by, this lack of accountability has undermined marketers’ credibility, threatened the standing of the marketing function within the firm, and even threatened marketing’s existence as a distinct capability within the firm. This article proposes a broad framework for assessing marketing productivity, cataloging what is already known, and suggesting areas for further research. The authors conclude that it is possible to show how marketing expenditures add to shareholder value. The effective dissemination of new methods of assessing marketing productivity to the business community will be a major step toward raising marketing’s vitality in the firm and, more important, toward raising the performance of the firm itself. The authors also suggest many areas in which further research is essential to making methods of evaluating marketing productivity increasingly valid,...

From Censure to Reinforcement: Developmental Changes in the Association Between Aggression and Social Status

Abstract: Developmental changes were examined in the associations among physical and relational aggression, and sociometric and perceived popularity based on peer nominations. Participating in the longitudinal study were 905 children (440 girls, 465 boys) from ages 10 to 14. Associations between the forms of status and between the forms of aggression decreased over time. Relational aggression increasingly predicted high social prominence but low social preference; physical aggression was increasingly less disliked but decreasingly predictive of prominence. The effect of relational aggression on perceived popularity was strong for girls. Perceived popularity preceded physical and relational aggression for both genders. Implications for the attainment of high status, processes of peer influence on antisocial behavior, and gender differences in the meaning of status are discussed.

Cross-Layer combining of adaptive Modulation and coding with truncated ARQ over wireless links

Abstract: We developed a cross-layer design which combines adaptive modulation and coding at the physical layer with a truncated automatic repeat request protocol at the data link layer, in order to maximize spectral efficiency under prescribed delay and error performance constraints. We derive the achieved spectral efficiency in closed-form for transmissions over Nakagami-m block fading channels. Numerical results reveal that retransmissions at the data link layer relieve stringent error control requirements at the physical layer, and thereby enable considerable spectral efficiency gain. This gain is comparable with that offered by diversity, provided that the maximum number of transmissions per packet equals the diversity order. Diminishing returns on spectral efficiency, that result when increasing the maximum number of retransmissions, suggest that a small number of retransmissions offers a desirable delay-throughput tradeoff, in practice.

Design of freeze-drying processes for pharmaceuticals: practical advice.

Abstract: Design of freeze-drying processes is often approached with a "trial and error" experimental plan or, worse yet, the protocol used in the first laboratory run is adopted without further attempts at optimization. Consequently, commercial freeze-drying processes are often neither robust nor efficient. It is our thesis that design of an "optimized" freeze-drying process is not particularly difficult for most products, as long as some simple rules based on well-accepted scientific principles are followed. It is the purpose of this review to discuss the scientific foundations of the freeze-drying process design and then to consolidate these principles into a set of guidelines for rational process design and optimization. General advice is given concerning common stability issues with proteins, but unusual and difficult stability issues are beyond the scope of this review. Control of ice nucleation and crystallization during the freezing step is discussed, and the impact of freezing on the rest of the process and final product quality is reviewed. Representative freezing protocols are presented. The significance of the collapse temperature and the thermal transition, denoted Tg', are discussed, and procedures for the selection of the "target product temperature" for primary drying are presented. Furthermore, guidelines are given for selection of the optimal shelf temperature and chamber pressure settings required to achieve the target product temperature without thermal and/or mass transfer overload of the freeze dryer. Finally, guidelines and "rules" for optimization of secondary drying and representative secondary drying protocols are presented.

Bayesian Survival Analysis

Abstract: Great strides in the analysis of survival data using Bayesian methods have been made in the past ten years due to advances in Bayesian computation and the feasibility of such methods. In this chapter, we review Bayesian advances in survival analysis and discuss the various semiparametric modeling techniques that are now commonly used. We review parametric and semiparametric approaches to Bayesian survival analysis, with a focus on proportional hazards models. Reference to other types of models are also given. Keywords: beta process; Cox model; Dirichlet process; gamma process; Gibbs sampling; piecewise exponential model; Weibull model

A customer lifetime value framework for customer selection and resource allocation strategy

Abstract: The authors evaluate the usefulness of customer lifetime value (CLV) as a metric for customer selection and marketing resource allocation by developing a dynamic framework that enables managers to maintain or improve customer relationships proactively through marketing contacts across various channels and to maximize CLV simultaneously. The authors show that marketing contacts across various channels influence CLV nonlinearly. Customers who are selected on the basis of their lifetime value provide higher profits in future periods than do customers selected on the basis of several other customer-based metrics. The analyses suggest that there is potential for improved profits when managers design resource allocation rules that maximize CLV. Managers can use the authors’ framework to allocate marketing resources efficiently across customers and channels of communication.

Infection and Invasion of Roots by Symbiotic, Nitrogen-Fixing Rhizobia during Nodulation of Temperate Legumes

Abstract: Bacteria belonging to the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. The interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. Temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that arise from root inner and middle cortical cells and grow out from the root via a persistent meristem. During the formation of functional indeterminate nodules, symbiotic bacteria must gain access to the interior of the host root. To get from the outside to the inside, rhizobia grow and divide in tubules called infection threads, which are composite structures derived from the two symbiotic partners. This review focuses on symbiotic infection and invasion during the formation of indeterminate nodules. It summarizes root hair growth, how root hair growth is influenced by rhizobial signaling molecules, infection of root hairs, infection thread extension down root hairs, infection thread growth into root tissue, and the plant and bacterial contributions necessary for infection thread formation and growth. The review also summarizes recent advances concerning the growth dynamics of rhizobial populations in infection threads.

An empirical investigation of net-enabled business value

Abstract: Many traditional organizations have undertaken major initiatives to leverage the Internet to transform how they coordinate value activities with customers, suppliers, and other business partners with the objective of improving firm performance. This paper addresses processes through which business value is created through such Internet-enabled value chain activities. Relying on the resource-based view of the firm, we propose a model positing that a firm's abilities to coordinate and exploit firm resources (processes, information technology, and readiness of customers and suppliers) create online informational capabilities (a higher order resource) which then leads to improved operational and financial performance. The outcome of a firm's online informational capabilities is reflected in superior operational performance through customer and supplier-side digitization efforts, which reflect the extent to which transactions and external interactions occur electronically. We also hypothesize that increased customer and supplier-side digitization leads to better financial performance. The model is tested with data from over 1,000 firms in the manufacturing, retail, and wholesale sectors. The analysis suggests that while most firms are lagging in their supplier-side initiatives relative to the customer-side, supplier-side digitization has a strong positive impact on customer-side digitization, which, in turn, leads to better financial performance. Further, both customer and supplier readiness to engage in digital interactions are shown to be as important as a firm's internal digitization initiatives, implying that a firm's transformation-related decisions should include its customers' and suppliers' resources and incentives.

Extracting more out of relocation data: building movement models as mixtures of random walks

Abstract: We present a framework for fitting multiple random walks to animal move- ment paths consisting of ordered sets of step lengths and turning angles. Each step and turn is assigned to one of a number of random walks, each characteristic of a different behavioral state. Behavioral state assignments may be inferred purely from movement data or may include the habitat type in which the animals are located. Switching between different behavioral states may be modeled explicitly using a state transition matrix estimated directly from data, or switching probabilities may take into account the proximity of animals to landscape features. Model fitting is undertaken within a Bayesian framework using the WinBUGS software. These methods allow for identification of different movement states using several properties of observed paths and lead naturally to the formulation of movement models. Analysis of relocation data from elk released in east-central Ontario, Canada, suggests a biphasic movement behavior: elk are either in an ''encamped'' state in which step lengths are small and turning angles are high, or in an ''exploratory'' state, in which daily step lengths are several kilometers and turning angles are small. Animals encamp in open habitat (agricultural fields and opened forest), but the exploratory state is not associated with any particular habitat type.

Preoperative PSA Velocity and the Risk of Death from Prostate Cancer after Radical Prostatectomy

Abstract: Background We evaluated whether men at risk for death from prostate cancer after radical prostatectomy can be identified using information available at diagnosis. Methods We studied 1095 men with localized prostate cancer to assess whether the rate of rise in the prostate-specific antigen (PSA) level — the PSA velocity — during the year before diagnosis, the PSA level at diagnosis, the Gleason score, and the clinical tumor stage could predict the time to death from prostate cancer and death from any cause after radical prostatectomy. Results As compared with an annual PSA velocity of 2.0 ng per milliliter or less, an annual PSA velocity of more than 2.0 ng per milliliter was associated with a significantly shorter time to death from prostate cancer (P<0.001) and death from any cause (P=0.01). An increasing PSA level at diagnosis (P=0.01), a Gleason score of 8, 9, or 10 (P=0.02), and a clinical tumor stage of T2 (P<0.001) also predicted the time to death from prostate cancer. For men with an annual PSA vel...

Political Partisanship and Welfare State Reform in Advanced Industrial Societies

Abstract: In this article we evaluate two claims made in recent studies of the welfare states of advanced industrial societies: first, that welfare states have remained quite resilient in the face of demands for retrenchment; and second, that partisan politics have ceased to play a decisive role in their evolution. Addressing the first claim, we present analysis from a new data set on unemployment insurance and sickness benefit replacement rates for 18 countries for the years 1975‐99. We find considerably more evidence of welfare retrenchment during the last two decades than do recent cross-national studies. Second, we examine the “end of partisanship” claim by estimating the effects of government partisanship on changes in income replacement rates in sickness and unemployment programs. Our results suggest that, contrary to claims that partisanship has little impact on welfare state commitments, traditional partisanship continues to have a considerable effect on welfare state entitlements in the era of retrenchment.

Green algae and the origin of land plants

Abstract: Over the past two decades, molecular phylogenetic data have allowed evaluations of hypotheses on the evolution of green algae based on vegetative morphological and ultrastructural characters. Higher taxa are now generally recognized on the basis of ultrastructural characters. Molecular analyses have mostly employed primarily nuclear small subunit rDNA (18S) and plastid rbcL data, as well as data on intron gain, complete genome sequencing, and mitochondrial sequences. Molecular-based revisions of classification at nearly all levels have occurred, from dismemberment of long-established genera and families into multiple classes, to the circumscription of two major lineages within the green algae. One lineage, the chlorophyte algae or Chlorophyta sensu stricto, comprises most of what are commonly called green algae and includes most members of the grade of putatively ancestral scaly flagellates in Prasinophyceae plus members of Ulvophyceae, Trebouxiophyceae, and Chlorophyceae. The other lineage (charophyte algae and embryophyte land plants), comprises at least five monophyletic groups of green algae, plus embryophytes. A recent multigene analysis corroborates a close relationship between Mesostigma (formerly in the Prasinophyceae) and the charophyte algae, although sequence data of the Mesostigma mitochondrial genome analysis places the genus as sister to charophyte and chlorophyte algae. These studies also support Charales as sister to land plants. The reorganization of taxa stimulated by molecular analyses is expected to continue as more data accumulate and new taxa and habitats are sampled. Twenty years ago, a relatively slim volume with chapters by leading chlorophycologists celebrated the systematics of green algae (Irvine and John, 1984), a field that was undergoing rapid and fascinating changes, both in content and theory. ‘‘The present period may be termed the ‘Age of Ultrastructure’ in green algal systematics,’’ wrote Frank Round (1984, p. 7) in the introductory chapter, which summarized the history and state of the art. Round (1984) argued that light microscopy had laid the foundation in the preceding two centuries, but that the foundation was largely descriptive—alpha taxonomy in the most restricted sense. Ultrastructure, he asserted, had enlarged and presumably would continue to expand our horizons to unify systematics of green algae and overcome the fragmented alpha taxonomy that had dominated the field. Little did Round know that this golden age of green algal systematics was about to go platinum. Molecular systematics, in concert with a rigorous theoretical approach to data analysis and hypothesis testing (Theriot, 1992; Swofford et al., 1996), would at first complement and then transform the age of ultrastructure and usher in the ‘‘Age of Molecules.’’ In this article, we review the major advances in green algal systematics in the past 20 years, with a focus on well-supported, monophyletic taxa and the larger picture of phylogeny and evolution of green algae. We will review the types of data that have fueled these advances. As will become obvious, this perspective entails discussion of some embryophytes as well as their closest green algal relatives. In addition, we will point

Data Envelopment Analysis: Theory and Techniques for Economics and Operations Research

Abstract: 1. Introduction and overview 2. Productivity, efficiency, and data envelopment analysis 3. Variable returns to scale: separating technical and scale efficiencies 4. Extensions to the basic DEA models 5. Non-radial models and Pareto-Koopmans measures of technical efficiency 6. Efficiency measurement without convexity assumption: free disposal hull analysis 7. Dealing with slacks: assurance region/cone ratio analysis, weak disposability, and congestion 8. Efficiency of merger and break up of firms 9. Efficiency analysis with market prices 10. Nonparametric approaches to production analysis 11. Measuring total factor productivity change over time 12. Stochastic approaches to data envelopment analysis 13. Looking ahead.

Variations in GABRA2, Encoding the α2 Subunit of the GABAA Receptor, Are Associated with Alcohol Dependence and with Brain Oscillations

Abstract: Alcoholism is a complex disease with both genetic and environmental risk factors. To identify genes that affect the risk for alcoholism, we systematically ascertained and carefully assessed individuals in families with multiple alcoholics. Linkage and association analyses suggested that a region of chromosome 4p contained genes affecting a quantitative endophenotype, brain oscillations in the beta frequency range (13–28 Hz), and the risk for alcoholism. To identify the individual genes that affect these phenotypes, we performed linkage disequilibrium analyses of 69 single-nucleotide polymorphism (SNPs) within a cluster of four GABAA receptor genes, GABRG1, GABRA2, GABRA4, and GABRB1, at the center of the linked region. GABAA receptors mediate important effects of alcohol and also modulate beta frequencies. Thirty-one SNPs in GABRA2, but only 1 of the 20 SNPs in the flanking genes, showed significant association with alcoholism. Twenty-five of the GABRA2 SNPs, but only one of the SNPs in the flanking genes, were associated with the brain oscillations in the beta frequency. The region of strongest association with alcohol dependence extended from intron 3 past the 3′ end of GABRA2; all 43 of the consecutive three-SNP haplotypes in this region of GABRA2 were highly significant. A three-SNP haplotype was associated with alcoholism, with P=.000000022. No coding differences were found between the high-risk and low-risk haplotypes, suggesting that the effect is mediated through gene regulation. The very strong association of GABRA2 with both alcohol dependence and the beta frequency of the electroencephalogram, combined with biological evidence for a role of this gene in both phenotypes, suggest that GABRA2 might influence susceptibility to alcohol dependence by modulating the level of neural excitation.

Low‐Thermal‐Conductivity Rare‐Earth Zirconates for Potential Thermal‐Barrier‐Coating Applications

Abstract: Rare-earth zirconates have been identified as a class of low-thermal-conductivity ceramics for possible use in thermal barrier coatings (TBCs) for gas-turbine engine applications. To document and compare the thermal conductivities of important rare-earth zirconates, we have measured the thermal conductivities of the following hot-pressed ceramics: (i) Gd 2 Zr 2 O 7 (pyrochlore phase), (ii) Gd 2 Zr 2 O 7 (fluorite phase), (iii) Gd 2.58 Zr 1.57 O 7 (fluorite phase), (iv) Nd 2 Zr 2 O 7 (pyrochlore phase), and (v) Sm 2 Zr 2 O 7 (pyrochlore phase). We have also measured the thermal conductivity of pressureless-sintered 7 wt% yttria-stabilized zirconia (7YSZ)--the commonly used composition in current TBCs. All rare-earth zirconates investigated here showed nearly identical thermal conductivities, all of which were ∼30% lower than the thermal conductivity of 7YSZ in the temperature range 25°-700°C. This finding is discussed qualitatively with reference to thermal-conductivity theory.

Votes and Violence: Electoral Competition and Ethnic Riots in India

Abstract: List of figures List of tables Acknowledgments 1. The electoral incentives for ethnic violence 2. Explaining town-level variation in Hindu-Muslim violence 3. State capacity explanations for Hindu-Muslim violence 4. The consociational explanation for Hindu-Muslim violence 5. The electoral incentives for Hindu-Muslim violence 6. Party competition and Hindu-Muslim violence 7. The electoral incentives for ethnic violence in comparative perspective 8. Democracy and ethnic violence Appendices References Index.

The mid-domain effect and species richness patterns:what have we learned so far?

Abstract: If species' ranges are randomly shuffled within a bounded geographical domain free of environmental gradients, ranges overlap increasingly toward the center of the domain, creating a “mid‐domain” peak of species richness. This “mid‐domain effect” (MDE) has been controversial both in concept and in application. Empirical studies assess the degree to which the evolutionary, ecological, and historical processes that undeniably act on individual species and clades produce geographical patterns that resemble those produced by MDE models. MDE models that resample empirical range size frequency distributions (RSFDs) balance the risk of underestimating and overestimating the role of MDE, whereas theoretical RSFDs are generally biased toward underestimating MDE. We discuss the inclusion of nonendemic species in MDE models, rationales for setting domain limits, and the validity of one‐ and two‐dimensional MDE models. MDE models, though null models, are not null hypotheses to be simplistically rejected or ...

Utilization of early invasive management strategies for high-risk patients with non-ST-segment elevation acute coronary syndromes: results from the CRUSADE Quality Improvement Initiative

Abstract: ContextThe American College of Cardiology/American Heart Association (ACC/AHA) guidelines for the management of non–ST-segment elevation acute coronary syndromes (NSTE ACS) recommend early invasive management for high-risk patients, given the benefits with this approach demonstrated in randomized clinical trials.ObjectivesTo determine the use and predictors of early invasive management strategies (cardiac catheterization <48 hours following presentation) in high-risk patients with NSTE ACS and to examine the association of early invasive management with mortality.Design, Setting, and PatientsThe CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines) Quality Improvement Initiative evaluated care patterns and outcomes for 17 926 high-risk NSTE ACS patients (positive cardiac markers and/or ischemic electrocardiographic changes) based on ACC/AHA guidelines recommendations at 248 US hospitals with catheterization and revascularization facilities between March 2000 and September 2002.Main Outcome MeasuresUse of early invasive management within 48 hours of presentation, predictors of early invasive management, and in-hospital mortality.ResultsOf the 17 926 patients analyzed, 8037 (44.8%) underwent early cardiac catheterization less than 48 hours following presentation. Predictors of early invasive management included cardiology care, younger age, lack of prior or current congestive heart failure, lack of renal insufficiency, ischemic electrocardiographic changes, positive cardiac markers, white race, and male sex. Patients treated with early invasive management were more likely to be treated with medications and interventions recommended by the ACC/AHA guidelines and had a lower risk of in-hospital mortality after adjusting for differences in clinical characteristics and after comparing propensity-matched pairs (2.5% vs 3.7%, P<.001).ConclusionsAn early invasive management strategy is not utilized in the majority of high-risk patients with NSTE ACS. This strategy appears to be reserved for patients without significant comorbidities and those cared for by cardiologists and is associated with a lower risk of in-hospital mortality.

Modeling Tetracycline Antibiotic Sorption to Clays

Abstract: Sorption interactions of three high-use tetracycline antibiotics (oxytetracycline, chlortetracycline, tetracycline) with montmorillonite and kaolinite clays were investigated undervaried pH and ionic strength conditions. Sorption edges were best described with a model that included cation exchange plus surface complexation of zwitterion forms of these compounds. Zwitterion sorption was accompanied by proton uptake, was more favorable on acidic clay, and was relatively insensitive to ionic strength effects. Calcium salts promoted oxytetracycline sorption at alkaline pHs likely by a surface-bridging mechanism. Substituent effects among the compounds in the tetracycline class had only minor effects on sorption edges and isotherms under the same solution pH and ionic strength conditions. At low ionic strength, greater sorption to montmorillonite than kaolinite was observed at all pHs tested, even after normalizing for cation exchange capacity. These results indicate that soil and sediment sorption models for tetracyclines, and other pharmaceuticals with similar chemistry, must account for solution speciation and the presence of other competitor ions in soil or sediment pore waters.

The Search for American Political Development

Abstract: In recent years, American political development has claimed the attention of a growing band of political scientists, and scholars have begun to speak of 'APD' as a subfield within the discipline. This book provides a justification for studying politics historically, not only for what it reveals about the roots of political affairs at the present time but what it teaches about politics as an ongoing activity in time, anytime. Placing the character of political institutions at the center of analysis, Orren and Skowronek survey past and current scholarship and attempt to outline a course of study for the future.