Showing papers by "Indiana University published in 2009"

Complex brain networks: graph theoretical analysis of structural and functional systems

Abstract: Recent developments in the quantitative analysis of complex networks, based largely on graph theory, have been rapidly translated to studies of brain network organization. The brain's structural and functional systems have features of complex networks--such as small-world topology, highly connected hubs and modularity--both at the whole-brain scale of human neuroimaging and at a cellular scale in non-human animals. In this article, we review studies investigating complex brain networks in diverse experimental modalities (including structural and functional MRI, diffusion tensor imaging, magnetoencephalography and electroencephalography in humans) and provide an accessible introduction to the basic principles of graph theory. We also highlight some of the technical challenges and key questions to be addressed by future developments in this rapidly moving field.

A General Framework for Analyzing Sustainability of Social-Ecological Systems

Abstract: A major problem worldwide is the potential loss of fisheries, forests, and water resources Understanding of the processes that lead to improvements in or deterioration of natural resources is limited, because scientific disciplines use different concepts and languages to describe and explain complex social-ecological systems (SESs) Without a common framework to organize findings, isolated knowledge does not cumulate Until recently, accepted theory has assumed that resource users will never self-organize to maintain their resources and that governments must impose solutions Research in multiple disciplines, however, has found that some government policies accelerate resource destruction, whereas some resource users have invested their time and energy to achieve sustainability A general framework is used to identify 10 subsystem variables that affect the likelihood of self-organization in efforts to achieve a sustainable SES

The diagnosis of osteoporosis

Abstract: VER THE YEARS many definitions of osteoporosis have been 0 offered to describe variously the outcome events (fragility fractures), the process giving rise to porous bones, or the resultant diminution of bone mass. More consistency has been achieved in recent years by the development of definitions that cover the spectrum of its manifestations. from the reduced amount of bone present to some of the consequences of bone loss. A consensus development conference statement defined osteoporosis as "a disease characterized by low bonc mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk."'" The definition has survived the rigors of the most recent consensus development confcrence."' There are, however, a number of problems which need to be addressed in adapting a conceptual definition for clinical use. Some of these problems were recently discussed by an expert panel of the World Health Organization."' This paper summarizes these issues and proposes diagnostic criteria for osteoporosis for practical use.

Predicting human resting-state functional connectivity from structural connectivity

Abstract: In the cerebral cortex, the activity levels of neuronal populations are continuously fluctuating. When neuronal activity, as measured using functional MRI (fMRI), is temporally coherent across 2 populations, those populations are said to be functionally connected. Functional connectivity has previously been shown to correlate with structural (anatomical) connectivity patterns at an aggregate level. In the present study we investigate, with the aid of computational modeling, whether systems-level properties of functional networks—including their spatial statistics and their persistence across time—can be accounted for by properties of the underlying anatomical network. We measured resting state functional connectivity (using fMRI) and structural connectivity (using diffusion spectrum imaging tractography) in the same individuals at high resolution. Structural connectivity then provided the couplings for a model of macroscopic cortical dynamics. In both model and data, we observed (i) that strong functional connections commonly exist between regions with no direct structural connection, rendering the inference of structural connectivity from functional connectivity impractical; (ii) that indirect connections and interregional distance accounted for some of the variance in functional connectivity that was unexplained by direct structural connectivity; and (iii) that resting-state functional connectivity exhibits variability within and across both scanning sessions and model runs. These empirical and modeling results demonstrate that although resting state functional connectivity is variable and is frequently present between regions without direct structural linkage, its strength, persistence, and spatial statistics are nevertheless constrained by the large-scale anatomical structure of the human cerebral cortex.

Individual- and organizational-level consequences of organizational citizenship behaviors: A meta-analysis.

Abstract: Although one of the main reasons for the interest in organizational citizenship behaviors (OCBs) is the potential consequences of these behaviors, no study has been reported that summarizes the research regarding the relationships between OCBs and their outcomes. Therefore, the purpose of this study is to provide a meta-analytic examination of the relationships between OCBs and a variety of individual- and organizational-level outcomes. Results, based on 168 independent samples (N 51,235 individuals), indicated that OCBs are related to a number of individual-level outcomes, including managerial ratings of employee performance, reward allocation decisions, and a variety of withdrawal-related criteria (e.g., employee turnover intentions, actual turnover, and absenteeism). In addition, OCBs were found to be related (k 38; N 3,611 units) to a number of organizational-level outcomes (e.g., productivity, efficiency, reduced costs, customer satisfaction, and unit-level turnover). Of interest, somewhat stronger relationships were observed between OCBs and unit-level performance measures in longitudinal studies than in cross-sectional studies, providing some evidence that OCBs are causally related to these criteria. The implications of these findings for both researchers and practitioners are discussed.

The Knowledge Spillover Theory of Entrepreneurship

Abstract: Contemporary theories of entrepreneurship generally focus on the recognition of opportunities and the decision to exploit them. Although the entrepreneurship literature treats opportunities as exogenous, the prevailing theory of economic growth suggests they are endogenous. This paper advances the microeconomic foundations of endogenous growth theory by developing a knowledge spillover theory of entrepreneurship. Knowledge created endogenously results in knowledge spillovers, which allow entrepreneurs to identify and exploit opportunities.

Bcl6 and Blimp-1 are reciprocal and antagonistic regulators of T follicular helper cell differentiation.

Abstract: Effective B cell–mediated immunity and antibody responses often require help from CD4+ T cells. It is thought that a distinct CD4+ effector T cell subset, called T follicular helper cells (TFH), provides this help; however, the molecular requirements for TFH differentiation are unknown. We found that expression of the transcription factor Bcl6 in CD4+ T cells is both necessary and sufficient for in vivo TFH differentiation and T cell help to B cells in mice. In contrast, the transcription factor Blimp-1, an antagonist of Bcl6, inhibits TFH differentiation and help, thereby preventing B cell germinal center and antibody responses. These findings demonstrate that TFH cells are required for proper B cell responses in vivo and that Bcl6 and Blimp-1 play central but opposing roles in TFH differentiation.

Autism genome-wide copy number variation reveals ubiquitin and neuronal genes

Abstract: Several lines of evidence point to genetic involvement in autism spectrum disorders (ASDs), neurodevelopmental and neuropsychiatric disorders characterized by impaired verbal communication and social interaction. The clinical and genetic complexities of the condition make it difficult to identify susceptibility factors, but two related studies now present robust evidence for a genetic involvement. The first, a genome-wide association study, identifies six single-nucleotide polymorphisms strongly associated with autism. These variants lie between two genes encoding neuronal cell-adhesion molecules (cadherins 9 and 10), suggesting possible involvement in ASD pathogenesis. The second study used copy number variation screens to identify genetic variants in two major gene pathways in children with ASDs. The changes are in the ubiquitin pathway, which has previously been associated with neurological disease, and in genes for neuronal cell-adhesion molecules.

miR2Disease: a manually curated database for microRNA deregulation in human disease

Abstract: 'miR2Disease', a manually curated database, aims at providing a comprehensive resource of microRNA deregulation in various human diseases. The current version of miR2Disease documents 1939 curated relationships between 299 human microRNAs and 94 human diseases by reviewing more than 600 published papers. Around one-seventh of the microRNA-disease relationships represent the pathogenic roles of deregulated microRNA in human disease. Each entry in the miR2Disease contains detailed information on a microRNA-disease relationship, including a microRNA ID, the disease name, a brief description of the microRNA-disease relationship, an expression pattern of the microRNA, the detection method for microRNA expression, experimentally verified target gene(s) of the microRNA and a literature reference. miR2Disease provides a user-friendly interface for a convenient retrieval of each entry by microRNA ID, disease name, or target gene. In addition, miR2Disease offers a submission page that allows researchers to submit established microRNA-disease relationships that are not documented. Once approved by the submission review committee, the submitted records will be included in the database. miR2Disease is freely available at http://www.miR2Disease.org.

Multiscale mobility networks and the spatial spreading of infectious diseases

Abstract: Among the realistic ingredients to be considered in the computational modeling of infectious diseases, human mobility represents a crucial challenge both on the theoretical side and in view of the limited availability of empirical data. To study the interplay between short-scale commuting flows and long-range airline traffic in shaping the spatiotemporal pattern of a global epidemic we (i) analyze mobility data from 29 countries around the world and find a gravity model able to provide a global description of commuting patterns up to 300 kms and (ii) integrate in a worldwide-structured metapopulation epidemic model a timescale-separation technique for evaluating the force of infection due to multiscale mobility processes in the disease dynamics. Commuting flows are found, on average, to be one order of magnitude larger than airline flows. However, their introduction into the worldwide model shows that the large-scale pattern of the simulated epidemic exhibits only small variations with respect to the baseline case where only airline traffic is considered. The presence of short-range mobility increases, however, the synchronization of subpopulations in close proximity and affects the epidemic behavior at the periphery of the airline transportation infrastructure. The present approach outlines the possibility for the definition of layered computational approaches where different modeling assumptions and granularities can be used consistently in a unifying multiscale framework.

Market orientation, marketing capabilities, and firm performance

Abstract: Drawing on traditional resource-based theory and its recent dynamic capabilities theory extensions, we examine both the possession of a market orientation and the marketing capabilities through which resources are deployed into the marketplace as drivers of firm performance in a cross-industry sample. Our findings indicate that market orientation and marketing capabilities are complementary assets that contribute to superior firm performance. We also find that market orientation has a direct effect on firms' return on assets (ROA), and that marketing capabilities directly impact both ROA and perceived firm performance. Copyright © 2009 John Wiley & Sons, Ltd.

Women Directors on Corporate Boards: A Review and Research Agenda

Abstract: Manuscript Type: Conceptual (Review) Research Question/Issue: This review examines how gender diversity on corporate boards influences corporate governance outcomes that in turn impact performance. We describe extant research on theoretical perspectives, characteristics and impact of women directors on corporate boards (WOCB) at micro, meso and macro levels: individual, board, firm and industry/environment. Research Finding/Insights: To the best of our knowledge, this is the first comprehensive review of WOCBs, incorporating and integrating research from over 400 publications in psychology, sociology, leadership, gender, finance, management, law, corporate governance and entrepreneurship domains. In addition, we organized our findings to provide a new lens enabling the field to be readily examined by level and by theoretical perspective. The review indicates that WOCB research is about improving corporate governance through better use of the whole talent pool’s capital, as well as about building more inclusive and fairer business institutions that better reflect their present generation stakeholders. Theoretical/Academic Implications: With only one in ten papers addressing theoretical development, the predominant perspectives are human and social capital theories and gender schema at individual level; social identity, token and social networks theories at board level; resource dependency, institution and agency theories at firm level, and institutional, critical and political theories at environmental level. We provide a short synopsis of findings at each level, and conclude with an outline of fruitful directions for future research. Practitioner/Policy Implications: There are increasing pressures for WOCBs, from diverse stakeholders such as the European Commission, national governments, politicians, employer lobby groups, shareholders, Fortune and FTSE rankings, best places for women to work lists as well as expectations from highly qualified women who are likely to leave if they see no women board members. Rationales generally draw on the business case, however the moral justice case is also used by those who seek a fairer gender balance in all aspects of society. From our review, the ‘Impact’ section charts the effect of WOCB at all four levels of analysis.

The frequency of polyploid speciation in vascular plants

Abstract: Since its discovery in 1907, polyploidy has been recognized as an important phenomenon in vascular plants, and several lines of evidence indicate that most, if not all, plant species ultimately have a polyploid ancestry. However, previous estimates of the frequency of polyploid speciation suggest that the formation and establishment of neopolyploid species is rare. By combining information from the botanical community's vast cytogenetic and phylogenetic databases, we establish that 15% of angiosperm and 31% of fern speciation events are accompanied by ploidy increase. These frequency estimates are higher by a factor of four than earlier estimates and lead to a standing incidence of polyploid species within genera of 35% (n = 1,506). Despite this high incidence, we find no direct evidence that polyploid lines, once established, enjoy greater net species diversification. Thus, the widespread occurrence of polyploid taxa appears to result from the substantial contribution of polyploidy to cladogenesis, but not from subsequent increases in diversification rates of polyploid lines.

What Student Affairs Professionals Need to Know About Student Engagement

Abstract: In a 1992 Calvin and Hobbs cartoon (Watterson), 6-year-old Calvin asks his teacher whether he is being adequately prepared for the challenges of the 21st century. He wants to know if he will have the skills and competencies that will allow him to succeed in a tough, global economy. In response, the teacher suggests he start working harder because what he will get out of school depends on how much effort he puts into it. Calvin ponders this advice for a moment and says, “Then forget it.” The exchange between Calvin and his teacher gets right to the point about what matters to student learning and personal development. Indeed, one of the few unequivocal conclusions from How College Affects Students (Pascarella & Terenzini, 2005) is that the amount of time and energy students put forth—student engagement—is positively linked with the desired outcomes of undergraduate education. Unfortunately, Calvin’s response is all too common, if not according to what students say, then by what they do or do not do. In this paper, I summarize the role and contributions of the scholarship and institutional research about student engagement and its relevance for student development professionals and others committed to enhancing the quality of the undergraduate experience. The presentation is organized into four major sections. First, I briefly describe the evolution of the student engagement concept and explain its importance to student development. Then, I summarize findings from research studies about the relationships between student engagement and selected activities including participation in high-impact practices, employment, and some other experiences of relevant a relevance to the current generation of undergraduates. Next, I discuss some topics that warrant additional investigation to better understand how to further potential and utility of student engagement research and institutional policies and practices that the findings suggest. I close with some observations about the implications of student engagement research for student affairs professionals and others on campus committed to improving the quality of undergraduate education.

Overview of the Technology Acceptance Model: Origins, Developments and Future Directions

Abstract: User acceptance of technology has been an important field of study for over two decades now. Although many models have been proposed to explain and predict the use of a system, the Technology Acceptance Model has been the only one which has captured the most attention of the Information Systems community. Thus, it is essential for anyone willing to study user acceptance of technology to have an understanding of the Technology Acceptance Model. This paper provides a historical overview of the Technology Acceptance Model (TAM) by summarizing the evolution of TAM, its key applications, extensions, limitations, and criticisms from a selective list of published articles on the model. Current observations indicate that although TAM is a highly cited model, researchers share mixed opinions regarding its theoretical assumptions, and practical effectiveness. It is concluded that research in TAM lacks sufficient rigor and relevance that would make it a well established theory for the IS community.

Acute Kidney Injury Increases Risk of ESRD among Elderly

Abstract: Risk for ESRD among elderly patients with acute kidney injury (AKI) has not been studied in a large, representative sample. This study aimed to determine incidence rates and hazard ratios for developing ESRD in elderly individuals, with and without chronic kidney disease (CKD), who had AKI. In the 2000 5% random sample of Medicare beneficiaries, clinical conditions were identified using Medicare claims; ESRD treatment information was obtained from ESRD registration during 2 yr of follow-up. Our cohort of 233,803 patients were hospitalized in 2000, were aged ≥67 yr on discharge, did not have previous ESRD or AKI, and were Medicare-entitled for ≥2 yr before discharge. In this cohort, 3.1% survived to discharge with a diagnosis of AKI, and 5.3 per 1000 developed ESRD. Among patients who received treatment for ESRD, 25.2% had a previous history of AKI. After adjustment for age, gender, race, diabetes, and hypertension, the hazard ratio for developing ESRD was 41.2 (95% confidence interval [CI] 34.6 to 49.1) for patients with AKI and CKD relative to those without kidney disease, 13.0 (95% CI 10.6 to 16.0) for patients with AKI and without previous CKD, and 8.4 (95% CI 7.4 to 9.6) for patients with CKD and without AKI. In summary, elderly individuals with AKI, particularly those with previously diagnosed CKD, are at significantly increased risk for ESRD, suggesting that episodes of AKI may accelerate progression of renal disease.

Multi-site assessment of the precision and reproducibility of multiple reaction monitoring–based measurements of proteins in plasma

Abstract: Verification of candidate biomarkers relies upon specific, quantitative assays optimized for selective detection of target proteins, and is increasingly viewed as a critical step in the discovery pipeline that bridges unbiased biomarker discovery to preclinical validation. Although individual laboratories have demonstrated that multiple reaction monitoring (MRM) coupled with isotope dilution mass spectrometry can quantify candidate protein biomarkers in plasma, reproducibility and transferability of these assays between laboratories have not been demonstrated. We describe a multilaboratory study to assess reproducibility, recovery, linear dynamic range and limits of detection and quantification of multiplexed, MRM-based assays, conducted by NCI-CPTAC. Using common materials and standardized protocols, we demonstrate that these assays can be highly reproducible within and across laboratories and instrument platforms, and are sensitive to low mug/ml protein concentrations in unfractionated plasma. We provide data and benchmarks against which individual laboratories can compare their performance and evaluate new technologies for biomarker verification in plasma.

Common genetic variants on 5p14.1 associate with autism spectrum disorders

Abstract: Several lines of evidence point to genetic involvement in autism spectrum disorders (ASDs), neurodevelopmental and neuropsychiatric disorders characterized by impaired verbal communication and social interaction. The clinical and genetic complexities of the condition make it difficult to identify susceptibility factors, but two related studies now present robust evidence for a genetic involvement. The first, a genome-wide association study, identifies six single-nucleotide polymorphisms strongly associated with autism. These variants lie between two genes encoding neuronal cell-adhesion molecules (cadherins 9 and 10), suggesting possible involvement in ASD pathogenesis. The second study used copy number variation screens to identify genetic variants in two major gene pathways in children with ASDs. The changes are in the ubiquitin pathway, which has previously been associated with neurological disease, and in genes for neuronal cell-adhesion molecules.

Progressive resistance strength training for improving physical function in older adults

Abstract: Background Muscle weakness in old age is associated with physical function decline. Progressive resistance strength training (PRT) exercises are designed to increase strength. Objectives To assess the effects of PRT on older people and identify adverse events. Search methods We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialized Register (to March 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 2), MEDLINE (1966 to May 01, 2008), EMBASE (1980 to February 06 2007), CINAHL (1982 to July 01 2007) and two other electronic databases. We also searched reference lists of articles, reviewed conference abstracts and contacted authors. Selection criteria Randomised controlled trials reporting physical outcomes of PRT for older people were included. Data collection and analysis Two review authors independently selected trials, assessed trial quality and extracted data. Data were pooled where appropriate. Main results One hundred and twenty one trials with 6700 participants were included. In most trials, PRT was performed two to three times per week and at a high intensity. PRT resulted in a small but significant improvement in physical ability (33 trials, 2172 participants; SMD 0.14, 95% CI 0.05 to 0.22). Functional limitation measures also showed improvements: e.g. there was a modest improvement in gait speed (24 trials, 1179 participants, MD 0.08 m/s, 95% CI 0.04 to 0.12); and a moderate to large effect for getting out of a chair (11 trials, 384 participants, SMD -0.94, 95% CI -1.49 to -0.38). PRT had a large positive effect on muscle strength (73 trials, 3059 participants, SMD 0.84, 95% CI 0.67 to 1.00). Participants with osteoarthritis reported a reduction in pain following PRT(6 trials, 503 participants, SMD -0.30, 95% CI -0.48 to -0.13). There was no evidence from 10 other trials (587 participants) that PRT had an effect on bodily pain. Adverse events were poorly recorded but adverse events related to musculoskeletal complaints, such as joint pain and muscle soreness, were reported in many of the studies that prospectively defined and monitored these events. Serious adverse events were rare, and no serious events were reported to be directly related to the exercise programme. Authors' conclusions This review provides evidence that PRT is an effective intervention for improving physical functioning in older people, including improving strength and the performance of some simple and complex activities. However, some caution is needed with transferring these exercises for use with clinical populations because adverse events are not adequately reported.

Rituximab, B-Lymphocyte Depletion, and Preservation of Beta-Cell Function

Abstract: BackgroundThe immunopathogenesis of type 1 diabetes mellitus is associated with T-lymphocyte autoimmunity. However, there is growing evidence that B lymphocytes play a role in many T-lymphocyte–mediated diseases. It is possible to achieve selective depletion of B lymphocytes with rituximab, an anti-CD20 monoclonal antibody. This phase 2 study evaluated the role of B-lymphocyte depletion in patients with type 1 diabetes. MethodsWe conducted a randomized, double-blind study in which 87 patients between 8 and 40 years of age who had newly diagnosed type 1 diabetes were assigned to receive infusions of rituximab or placebo on days 1, 8, 15, and 22 of the study. The primary outcome, assessed 1 year after the first infusion, was the geometric mean area under the curve (AUC) for the serum C-peptide level during the first 2 hours of a mixed-meal tolerance test. Secondary outcomes included safety and changes in the glycated hemoglobin level and insulin dose. ResultsAt 1 year, the mean AUC for the level of C peptid...

Function of Mitochondrial Stat3 in Cellular Respiration

Abstract: Cytokines such as interleukin-6 induce tyrosine and serine phosphorylation of Stat3 that results in activation of Stat3-responsive genes. We provide evidence that Stat3 is present in the mitochondria of cultured cells and primary tissues, including the liver and heart. In Stat3(-/-) cells, the activities of complexes I and II of the electron transport chain (ETC) were significantly decreased. We identified Stat3 mutants that selectively restored the protein's function as a transcription factor or its functions within the ETC. In mice that do not express Stat3 in the heart, there were also selective defects in the activities of complexes I and II of the ETC. These data indicate that Stat3 is required for optimal function of the ETC, which may allow it to orchestrate responses to cellular homeostasis.

The national survey of student engagement: Conceptual and empirical foundations

Abstract: This chapter summarizes the history of the engagement concept, the development of the National Survey of Student Engagement (NSSE), and its impact on institutional researchers.

Biological and clinical manifestations of Huntington's disease in the longitudinal TRACK-HD study: cross-sectional analysis of baseline data.

Abstract: Summary Background Huntington's disease (HD) is an autosomal dominant, fully penetrant, neurodegenerative disease that most commonly affects adults in mid-life. Our aim was to identify sensitive and reliable biomarkers in premanifest carriers of mutated HTT and in individuals with early HD that could provide essential methodology for the assessment of therapeutic interventions. Methods This multicentre study uses an extensive battery of novel assessments, including multi-site 3T MRI, clinical, cognitive, quantitative motor, oculomotor, and neuropsychiatric measures. Blinded analyses were done on the baseline cross-sectional data from 366 individuals: 123 controls, 120 premanifest (pre-HD) individuals, and 123 patients with early HD. Findings The first participant was enrolled in January, 2008, and all assessments were completed by August, 2008. Cross-sectional analyses identified significant changes in whole-brain volume, regional grey and white matter differences, impairment in a range of voluntary neurophysiological motor, and oculomotor tasks, and cognitive and neuropsychiatric dysfunction in premanifest HD gene carriers with normal motor scores through to early clinical stage 2 disease. Interpretation We show the feasibility of rapid data acquisition and the use of multi-site 3T MRI and neurophysiological motor measures in a large multicentre study. Our results provide evidence for quantifiable biological and clinical alterations in HTT expansion carriers compared with age-matched controls. Many parameters differ from age-matched controls in a graded fashion and show changes of increasing magnitude across our cohort, who range from about 16 years from predicted disease diagnosis to early HD. These findings might help to define novel quantifiable endpoints and methods for rapid and reliable data acquisition, which could aid the design of therapeutic trials. Funding CHDI/High Q Foundation.

Conceptualizing Corporate Entrepreneurship Strategy

Abstract: Our knowledge of corporate entrepreneurship (CE) continues to expand. However, this knowledge remains quite fragmented and non–cumulative. Herein, we conceptualize CE strategy as a useful focal poi...