Showing papers by "University of Connecticut published in 2009"

Genetics in geographically structured populations: defining, estimating and interpreting FST

Abstract: FST describes the processes that lead to genetic differentiation among and within populations and is widely used in population and evolutionary genetics. This article describes the meaning of FST and how it should be estimated and interpreted.

Unpacking Organizational Ambidexterity: Dimensions, Contingencies, and Synergistic Effects

Abstract: Significant ambiguity remains in the literature regarding the conceptualization of organizational ambidexterity. We unpack this construct into one with two dimensions we term the balance dimension of ambidexterity (BD) and the combined dimension of ambidexterity (CD). BD corresponds to a firm's orientation to maintain a close relative balance between exploratory and exploitative activities, whereas CD corresponds to their combined magnitude. We reason that these dimensions are conceptually distinct, and rely on different causal mechanisms to enhance firm performance. We find that over and above their independent effects, concurrent high levels of BD and CD yield synergistic benefits. We also find that BD is more beneficial to resource-constrained firms, whereas CD is more beneficial to firms having greater access to internal and/or external resources. These results indicate that managers in resource-constrained contexts may benefit from a focus on managing trade-offs between exploration and exploitation demands, but for firms that have access to sufficient resources, the simultaneous pursuit of exploration and exploitation is both possible and desirable.

Guidelines for the nomenclature of the human heat shock proteins

Abstract: The expanding number of members in the various human heat shock protein (HSP) families and the inconsistencies in their nomenclature have often led to confusion. Here, we propose new guidelines for the nomenclature of the human HSP families, HSPH (HSP110), HSPC (HSP90), HSPA (HSP70), DNAJ (HSP40), and HSPB (small HSP) as well as for the human chaperonin families HSPD/E (HSP60/HSP10) and CCT (TRiC). The nomenclature is based largely on the more consistent nomenclature assigned by the HUGO Gene Nomenclature Committee and used in the National Center of Biotechnology Information Entrez Gene database for the heat shock genes. In addition to this nomenclature, we provide a list of the human Entrez Gene IDs and the corresponding Entrez Gene IDs for the mouse orthologs.

From Conceptualizing to Measuring HIV Stigma: A Review of HIV Stigma Mechanism Measures

Abstract: Recent analyses suggest that lack of clarity in the conceptualization and measurement of HIV stigma at an individual level is a significant barrier to HIV prevention and treatment efforts. In order to address this concern, we articulate a new framework designed to aid in clarifying the conceptualization and measurement of HIV stigma among individuals. The HIV Stigma Framework explores how the stigma of HIV elicits a series of stigma mechanisms, which in turn lead to deleterious outcomes for HIV uninfected and infected people. We then apply this framework to review measures developed to gauge the effect of HIV stigma since the beginning of the epidemic. Finally, we emphasize the utility of using three questions to guide future HIV stigma research: who is affected by, how are they affected by, and what are the outcomes of HIV stigma?

Prospects for tropical forest biodiversity in a human-modified world.

Abstract: The future of tropical forest biodiversity depends more than ever on the effective management of human-modified landscapes, presenting a daunting challenge to conservation practitioners and land use managers. We provide a critical synthesis of the scientific insights that guide our understanding of patterns and processes underpinning forest biodiversity in the human-modified tropics, and present a conceptual framework that integrates a broad range of social and ecological factors that define and contextualize the possible future of tropical forest species. A growing body of research demonstrates that spatial and temporal patterns of biodiversity are the dynamic product of interacting historical and contemporary human and ecological processes. These processes vary radically in their relative importance within and among regions, and have effects that may take years to become fully manifest. Interpreting biodiversity research findings is frequently made difficult by constrained study designs, low congruence in species responses to disturbance, shifting baselines and an over-dependence on comparative inferences from a small number of well studied localities. Spatial and temporal heterogeneity in the potential prospects for biodiversity conservation can be explained by regional differences in biotic vulnerability and anthropogenic legacies, an ever-tighter coupling of human-ecological systems and the influence of global environmental change. These differences provide both challenges and opportunities for biodiversity conservation. Building upon our synthesis we outline a simple adaptive-landscape planning framework that can help guide a new research agenda to enhance biodiversity conservation prospects in the human-modified tropics.

Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance.

Abstract: It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance. This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of sports dietitians. Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins, as well as contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged. Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise, maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia. Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density, may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution, and only after careful product evaluation for safety, efficacy, potency, and legality. A qualified sports dietitian and in particular in the United States, a Board Certified Specialist in Sports Dietetics, should provide individualized nutrition direction and advice subsequent to a comprehensive nutrition assessment.

Targeted killing of cancer cells in vivo and in vitro with EGF-directed carbon nanotube-based drug delivery.

Abstract: Carbon nanotube-based drug delivery holds great promise for cancer therapy. Herein we report the first targeted, in vivo killing of cancer cells using a drug-single wall carbon nanotube (SWNT) bioconjugate, and demonstrate efficacy superior to nontargeted bioconjugates. First line anticancer agent cisplatin and epidermal growth factor (EGF) were attached to SWNTs to specifically target squamous cancer, and the nontargeted control was SWNT-cisplatin without EGF. Initial in vitro imaging studies with head and neck squamous carcinoma cells (HNSCC) overexpressing EGF receptors (EGFR) using Qdot luminescence and confocal microscopy showed that SWNT-Qdot-EGF bioconjugates internalized rapidly into the cancer cells. Limited uptake occurred for control cells without EGF, and uptake was blocked by siRNA knockdown of EGFR in cancer cells, revealing the importance of EGF-EGFR binding. Three color, two-photon intravital video imaging in vivo showed that SWNT-Qdot-EGF injected into live mice was selectively taken up b...

Polydendrocytes (NG2 cells): multifunctional cells with lineage plasticity

Abstract: NG2 cells (also known as polydendrocytes) are a population of CNS cells that are distinct from neurons, mature oligodendrocytes, astrocytes and microglia. They can be identified by the expression of the proteoglycan NG2, have a highly branched morphology and are distributed throughout the grey and white matter. They differentiate into oligodendrocytes in vitro and have often been equated with oligodendrocyte precursor cells. However, whether polydendrocytes are multipotential cells that can give rise to neurons and astrocytes as well as oligodendrocytes is now highly debated. Furthermore, electrophysiological studies indicate that polydendrocytes receive synaptic input from neurons, suggesting that they are integrated in the neural network. This Review highlights recent findings and unresolved questions related to the lineage and function of polydendrocytes in the CNS.

A Randomized, Wait-List Controlled Effectiveness Trial Assessing School-Wide Positive Behavior Support in Elementary Schools.

Abstract: We report a randomized, wait-list controlled trial assessing the effects of school-wide positive behavior support (SWPBS). An effectiveness analysis was conducted with elementary schools in Hawaii ...

Organizational Ambidexterity: Towards a Multilevel Understanding

Abstract: Although interest in the concept of organizational ambidexterity has increased during recent years, this line of inquiry remains unfocused and limited due to a lack of more encompassing conceptual efforts. As a first step, we begin by critically reviewing previous research on the conceptualization, antecedents, and consequences of ambidexterity. We then offer a model that specifies a more encompassing, multilevel explanation of ambidexterity. Finally, we trace research and managerial implications and suggest some potential research avenues.

Sparse channel estimation for multicarrier underwater acoustic communication: From subspace methods to compressed sensing

Abstract: In this paper, we investigate various channel estimators that exploit channel sparsity in the time and/or Doppler domain for a multicarrier underwater acoustic system. We use a path-based channel model, where the channel is described by a limited number of paths, each characterized by a delay, Doppler scale, and attenuation factor, and derive the exact inter-carrier-interference (ICI) pattern. For channels that have limited Doppler spread we show that subspace algorithms from the array processing literature, namely Root-MUSIC and ESPRIT, can be applied for channel estimation. For channels with Doppler spread, we adopt a compressed sensing approach, in form of Orthogonal Matching Pursuit (OMP) and Basis Pursuit (BP) algorithms, and utilize overcomplete dictionaries with an increased path delay resolution. Numerical simulation and experimental data of an OFDM block-by-block receiver are used to evaluate the proposed algorithms in comparison to the conventional least-squares (LS) channel estimator. We observe that subspace methods can tolerate small to moderate Doppler effects, and outperform the LS approach when the channel is indeed sparse. On the other hand, compressed sensing algorithms uniformly outperform the LS and subspace methods. Coupled with a channel equalizer mitigating ICI, the compressed sensing algorithms can effectively handle channels with significant Doppler spread.

The Transmission Electron Microscope

Abstract: A typical commercial transmission electron microscope (TEM) costs about $5 for each electron volt (eV) of energy in the beam and, if you add on all available options, it can easily cost up to $10 per eV. As you’ll see, we use beam energies in the range from 100,000 to 400,000 eV, so a TEMis an extremely expensive piece of equipment. Consequently, there have to be very sound scientific reasons for investing such a large amount of money in onemicroscope. In this chapter (which is just a brief overview of many of the concepts that we’ll talk about in detail throughout the book) we start by introducing you to some of the historical development of the TEM because the history is intertwined with some of the reasons why you need to use a TEM to characterize materials. Other reasons for using a TEM have appeared as the instrument continues to develop, to the point where it can seriously be claimed that no other scientific instrument exists which can offer such a broad range of characterization techniques with such high spatial and analytical resolution, coupled with a completely quantitative understanding of the various techniques.

Living with a concealable stigmatized identity: the impact of anticipated stigma, centrality, salience, and cultural stigma on psychological distress and health.

Abstract: The current research provides a framework for understanding how concealable stigmatized identities impact people's psychological well-being and health. The authors hypothesize that increased anticipated stigma, greater centrality of the stigmatized identity to the self, increased salience of the identity, and possession of a stigma that is more strongly culturally devalued all predict heightened psychological distress. In Study 1, the hypotheses were supported with a sample of 300 participants who possessed 13 different concealable stigmatized identities. Analyses comparing people with an associative stigma to those with a personal stigma showed that people with an associative stigma report less distress and that this difference is fully mediated by decreased anticipated stigma, centrality, and salience. Study 2 sought to replicate the findings of Study 1 with a sample of 235 participants possessing concealable stigmatized identities and to extend the model to predicting health outcomes. Structural equation modeling showed that anticipated stigma and cultural stigma were directly related to self-reported health outcomes. Discussion centers on understanding the implications of intraindividual processes (anticipated stigma, identity centrality, and identity salience) and an external process (cultural devaluation of stigmatized identities) for mental and physical health among people living with a concealable stigmatized identity.

Interactive effects of growth need strength, work context, and job complexity on self-reported creative performance

Abstract: We propose that “growth need strength” is an important individual factor for employees' creative performance. Using an interactionist perspective, we examine the relationship between growth need st...

Diagnosis of asymptomatic primary hyperparathyroidism: proceedings of the third international workshop.

Abstract: Background: At the Third International Workshop on Asymptomatic Primary Hyperparathyroidism (PHPT) in May 2008, recent data on the disease were reviewed. We present the results of a literature review on issues arising from the clinical presentation and natural history of PHPT. Methods: Questions were developed by the International Task Force on PHPT. A comprehensive literature search for relevant studies was reviewed, and the questions of the International Task Force were addressed by the Consensus Panel. Conclusions: 1) Data on the extent and nature of cardiovascular involvement in those with mild disease are too limited to provide a complete picture. 2) Patients with mild PHPT have neuropsychological complaints. Although some symptoms may improve with surgery, available data remain inconsistent on their precise nature and reversibility. 3) Surgery leads to long-term gains in spine, hip, and radius bone mineral density (BMD). Because some patients have early disease progression and others lose BMD after ...

Corporate Tax Avoidance and Firm Value

Abstract: Do corporate tax avoidance activities advance shareholder interests? This paper tests alternative theories of corporate tax avoidance using unexplained differences between income reported to capital markets and to tax authorities. OLS estimates indicate that the effect of tax avoidance on firm value is a function of firm governance, as predicted by an agency perspective on corporate tax avoidance. Instrumental variables estimates based on exogenous changes in tax regulations yield larger overall effects and reinforce the basic result, as do several robustness checks. The results suggest that the simple view of corporate tax avoidance as a transfer of resources from the state to shareholders is incomplete given the agency problems characterizing shareholder-manager relations.

A Typology for Aligning Organizational Ambidexterity's Conceptualizations, Antecedents, and Outcomes

Abstract: We take stock of the current body of knowledge and understanding on organizational ambidexterity to further specify the construct and develop a typology to focus this line of research. To that end, we first synthesize the various insights on ambidexterity's conceptualization in extant research. We then develop a parsimonious, yet coherent typology that delineates four archetypes of ambidexterity using two primary dimensions underlying previous conceptualizations of this construct. To help focus and align extant research, we next map these types onto the most salient theories, antecedents, and outcomes that are uniquely germane to each. Finally, we offer several recommendations and promising avenues for future inquiries that follow from our typology and associated discussion.

The Potential for Species Conservation in Tropical Secondary Forests

Abstract: In the wake of widespread loss of old-growth forests throughout the tropics, secondary forests will likely play a growing role in the conservation of forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary forests. Beyond the characteristics of local forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary forests. Prospects for conservation of old-growth species in secondary forests are maximized in regions where the ratio of secondary to old-growth forest area is relatively low, older secondary forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed-dispersing fauna are present, and old-growth forests are close to abandoned sites. The conservation value of a secondary forest is expected to increase over time, as species arriving from remaining old-growth forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of old-growth species present in secondary forests. Older secondary forests are not often studied and few long-term studies are conducted in secondary forests. Available data indicate that both old-growth and second-growth forests are important to the persistence of forest species in tropical, human-modified landscapes.

Hutchinson's duality: The once and future niche

Abstract: The duality between "niche" and "biotope" proposed by G. Evelyn Hutchinson provides a powerful way to conceptualize and analyze biogeographical distributions in relation to spatial environmental patterns. Both Joseph Grinnell and Charles Elton had attributed niches to environments. Attributing niches, instead, to species, allowed Hutchinson's key innovation: the formal severing of physical place from environment that is expressed by the duality. In biogeography, the physical world (a spatial extension of what Hutchinson called the biotope) is conceived as a map, each point (or cell) of which is characterized by its geographical coordinates and the local values of n environmental attributes at a given time. Exactly the same n environmental attributes define the corresponding niche space, as niche axes, allowing reciprocal projections between the geographic distribution of a species, actual or potential, past or future, and its niche. In biogeographical terms, the realized niche has come to express not only the effects of species interactions (as Hutchinson intended), but also constraints of dispersal limitation and the lack of contemporary environments corresponding to parts of the fundamental niche. Hutchinson's duality has been used to classify and map environments; model potential species distributions under past, present, and future climates; study the distributions of invasive species; discover new species; and simulate increasingly more realistic worlds, leading to spatially explicit, stochastic models that encompass speciation, extinction, range expansion, and evolutionary adaptation to changing environments.

Beyond Reserves: A Research Agenda for Conserving Biodiversity in Human‐modified Tropical Landscapes

Abstract: To truly understand the current status of tropical diversity and to forecast future trends, we need to increase emphasis on the study of biodiversity in rural landscapes that are actively managed or modified by people. We present an integrated landscape approach to promote research in human-modified landscapes that includes the effects of landscape structure and dynamics on conservation of biodiversity, provision of ecosystem services, and sustainability of rural livelihoods. We propose research priorities encompassing three major areas: biodiversity, human–environment interactions, and restoration ecology. We highlight key areas where we lack knowledge and where additional understanding is most urgent for promoting conservation and sustaining rural livelihoods. Finally, we recommend participatory and multidisciplinary approaches in research and management. Lasting conservation efforts demand new alliances among conservation biologists, agroecologists, agronomists, farmers, indigenous peoples, rural social movements, foresters, social scientists, and land managers to collaborate in research, co-design conservation programs and policies, and manage human-modified landscapes in ways that enhance biodiversity conservation and promote sustainable livelihoods.

Ultrasensitive Immunosensor for Cancer Biomarker Proteins using Gold Nanoparticle Film Electrodes and Multienzyme-Particle Amplification

Abstract: A densely packed gold nanoparticle platform combined with a multiple-enzyme labeled detection antibody-magnetic bead bioconjugate was used as the basis for an ultrasensitive electrochemical immunosensor to detect cancer biomarkers in serum. Sensitivity was greatly amplified by synthesizing magnetic bioconjugates particles containing 7500 horseradish peroxidase (HRP) labels along with detection antibodies (Ab2) attached to activated carboxyl groups on 1 μm diameter magnetic beads. These sensors had sensitivity of 31.5 μA mL ng−1 and detection limit (DL) of 0.5 pg mL−1 for prostate specific antigen (PSA) in 10 μL of undiluted serum. This represents an ultralow mass DL of 5 fg PSA, 8-fold better than a previously reported carbon nanotube (CNT) forest immunosensor featuring multiple labels on carbon nanotubes, and near or below the normal serum levels of most cancer biomarkers. Measurements of PSA in cell lysates and human serum of cancer patients gave excellent correlations with standard ELISA assays. These ...

Social Connection Through Joint Action and Interpersonal Coordination

Abstract: The pull to coordinate with other individuals is fundamental, serving as the basis for our social connectedness to others. Discussed is a dynamical and ecological perspective to joint action, an approach that embeds the individual’s mind in a body and the body in a niche, a physical and social environment. Research on uninstructed coordination of simple incidental rhythmic movement, along with research on goal-directed, embodied cooperation, is reviewed. Finally, recent research is discussed that extends the coordination and cooperation studies, examining how synchronizing with another, and how emergent social units of perceiving and acting are reflected in people’s feelings of connection to others.

The Impact of Financial Literacy Education on Subsequent Financial Behavior

Abstract: This study examined the differential impact on 79 high school students of a personal financial management course completed 1 to 4 years earlier. This study used a matched sample design based on a school system’s records to identify students who had and had not taken a course in personal financial management. The findings indicated that those who took the course were no more financially literate than those who had not. In addition, those who took the course did not evaluate themselves to be more savings-oriented and did not appear to have better financial behavior than those who had not taken the course. The study raises serious questions about the longer-term effectiveness of high school financial literacy courses.

Information, affordances, and the control of action in sport.

Abstract: The theory of affordances, a conceptual pillar of the ecological approach to perception and action, has the potential to become a guiding principle for research on perception and action in sport. Affordances are opportunities for action. They describe the environment in terms of behaviors that are possible at a given moment under a given set of conditions. Affordances capture the tight coupling between perception and action, and allow for the prospective and moment-to-moment control of activity that is characteristic of fluent, fast-paced behavior on the playing field. We begin with an overview of the ecological approach and the principle of direct perception, using past research on interceptive action to illustrate how this principle has been put to work to capture information-movement relations in perceptualmotor skill. We then review theory and research on body-scaled, action-scaled, and social affordances, highlighting outstanding questions that provide opportunities for new research on affordances in the context of sport. We conclude with consideration of affordances as providing a functional semantics for sports.

Responsiveness-to-Intervention and School-Wide Positive Behavior Supports: Integration of Multi-Tiered System Approaches

Abstract: The Individuals with Disabilities Education Act and No Child Left Behind emphasize the use of scientifically based research to improve outcomes for students. From this emphasis, response-to-intervention has evolved. We present one perspective on the defining features of response-to-intervention and application of those features to school-wide positive behavior supports (SWPBS). We suggest that the initial purpose of response-to-intervention has expanded from a focus on screening and improved outcomes for students with learning disabilities to a general approach for improving instructional and intervention decision making for all students. We describe a similar evolution of SWPBS, only with a focus on the (a) social culture within the whole school and (b) behavior supports for those students with problem behavior. We conclude by suggesting that the response-to-intervention approach offers an excellent umbrella of guiding principles for improved assessment and intervention decision making, and that SWPBS is...

Sufficient sampling for asymptotic minimum species richness estimators

Abstract: Biodiversity sampling is labor intensive, and a substantial fraction of a biota is often represented by species of very low abundance, which typically remain undetected by biodiversity surveys. Statistical methods are widely used to estimate the asymptotic number of species present, including species not yet detected. Additional sampling is required to detect and identify these species, but richness estimators do not indicate how much sampling effort (additional individuals or samples) would be necessary to reach the asymptote of the species accumulation curve. Here we develop the first statistically rigorous nonparametric method for estimating the minimum number of additional individuals, samples, or sampling area required to detect any arbitrary proportion (including 100%) of the estimated asymptotic species richness. The method uses the Chao1 and Chao2 nonparametric estimators of asymptotic richness, which are based on the frequencies of rare species in the original sampling data. To evaluate the performance of the proposed method, we randomly subsampled individuals or quadrats from two large biodiversity inventories (light trap captures of Lepidoptera in Great Britain and censuses of woody plants on Barro Colorado Island [BCI], Panama). The simulation results suggest that the method performs well but is slightly conservative for small sample sizes. Analyses of the BCI results suggest that the method is robust to nonindependence arising from small-scale spatial aggregation of species occurrences. When the method was applied to seven published biodiversity data sets, the additional sampling effort necessary to capture all the estimated species ranged from 1.05 to 10.67 times the original sample (median approximately equal to 2.23). Substantially less effort is needed to detect 90% of the species (0.33-1.10 times the original effort; median approximately equal to 0.80). An Excel spreadsheet tool is provided for calculating necessary sampling effort for either abundance data or replicated incidence data.

Cyclic GMP from the surrounding somatic cells regulates cyclic AMP and meiosis in the mouse oocyte.

Abstract: Mammalian oocytes are arrested in meiotic prophase by an inhibitory signal from the surrounding somatic cells in the ovarian follicle. In response to luteinizing hormone (LH), which binds to receptors on the somatic cells, the oocyte proceeds to second metaphase, where it can be fertilized. Here we investigate how the somatic cells regulate the prophase-to-metaphase transition in the oocyte, and show that the inhibitory signal from the somatic cells is cGMP. Using FRET-based cyclic nucleotide sensors in follicle-enclosed mouse oocytes, we find that cGMP passes through gap junctions into the oocyte, where it inhibits the hydrolysis of cAMP by the phosphodiesterase PDE3A. This inhibition maintains a high concentration of cAMP and thus blocks meiotic progression. LH reverses the inhibitory signal by lowering cGMP levels in the somatic cells (from ∼2 μM to ∼80 nM at 1 hour after LH stimulation) and by closing gap junctions between the somatic cells. The resulting decrease in oocyte cGMP (from ∼1 μM to ∼40 nM) relieves the inhibition of PDE3A, increasing its activity by ∼5-fold. This causes a decrease in oocyte cAMP (from ∼700 nM to ∼140 nM), leading to the resumption of meiosis.