The University of Tennessee is a public sun-grant and land-grant university headquartered in Knoxville, Tennessee, United States. Founded in 1794, two years before Tennessee entered the Union as the 16th state, it is the flagship institution of the statewide University of Tennessee system with nine undergraduate colleges and eleven graduate colleges and hosts almost 28,000 students from all 50 states and more than 100 foreign countries. In its 2014 ranking of universities, U.S. News & World Report ranked UT 106th among all national universities and 46th among public institutions of higher learning. Seven alumni have been selected as Rhodes Scholars; James M. Buchanan, M.S. '41, received the 1986 Nobel Prize in Economics. UT's ties to nearby Oak Ridge National Laboratory, established under UT President Andrew Holt and continued under the UT-Battelle partnership, allow for considerable research opportunities for faculty and students.Also affiliated with the university are the Howard H. Baker, Jr. Center for Public Policy, the University of Tennessee Anthropological Research Facility, and the University of Tennessee Arboretum, which occupies 250 acres of nearby Oak Ridge and features hundreds of species of plants indigenous to the region. The University is a direct partner of the University of Tennessee Medical Center, which is one of two Level I trauma centers in East Tennessee. As a teaching hospital, it has aggressive medical research programs.The University of Tennessee is the only university in the nation to have three presidential papers editing projects and holds collections of the papers of all three U.S. presidents from Tennessee—Andrew Jackson, James K. Polk, and Andrew Johnson. UT is one of the oldest public universities in the United States and the oldest secular institution west of the Eastern Continental Divide. Wikipedia.
Hoban S.,University of Tennessee at Knoxville
Molecular Ecology | Year: 2014
Stochastic simulation software that simultaneously model genetic, population and environmental processes can inform many topics in molecular ecology. These include forecasting species and community response to environmental change, inferring dispersal ecology, revealing cryptic mating, quantifying past population dynamics, assessing in situ management options and monitoring neutral and adaptive biodiversity change. Advances in population demographic-genetic simulation software, especially with respect to individual life history, landscapes and genetic processes, are transforming and expanding the ways that molecular data can be used. The aim of this review is to explain the roles that such software can play in molecular ecology studies (whether as a principal component or a supporting function) so that researchers can decide whether, when and precisely how simulations can be incorporated into their work. First, I use seven case studies to demonstrate how simulations are employed, their specific advantage/necessity and what alternative or complementary (nonsimulation) approaches are available. I also explain how simulations can be integrated with existing spatial, environmental, historical and genetic data sets. I next describe simulation features that may be of interest to molecular ecologists, such as spatial and behavioural considerations and species' interactions, to provide guidance on how particular simulation capabilities can serve particular needs. Lastly, I discuss the prospect of simulation software in emerging challenges (climate change, biodiversity monitoring, population exploitation) and opportunities (genomics, ancient DNA), in order to emphasize that the scope of simulation-based work is expanding. I also suggest practical considerations, priorities and elements of best practice. This should accelerate the uptake of simulation approaches and firmly embed them as a versatile tool in the molecular ecologist's toolbox. © 2014 John Wiley & Sons Ltd.
Hagen G.,Oak Ridge National Laboratory |
Papenbrock T.,Oak Ridge National Laboratory |
Papenbrock T.,University of Tennessee at Knoxville |
Hjorth-Jensen M.,University of Oslo
Physical Review Letters | Year: 2010
We perform coupled-cluster calculations of the energies and lifetimes of single-particle states around the doubly magic nucleus O16 based on chiral nucleon-nucleon interactions at next-to-next-to-next-to-leading order. To incorporate effects from the scattering continuum, we employ a Gamow-Hartree-Fock basis. Our calculations for the Jπ=1/2+ proton halo state in F17 and the 1/2+ state in O17 agree well with experiment, while the calculated spin-orbit splitting between 5/2+ and 3/2+ states is too small due to the lack of three-nucleon forces. Continuum effects yield a significant amount of additional binding energy for the 1/2+ and 3/2+ states in O17 and F17. © 2010 The American Physical Society.
Brown M.,University of Tennessee at Knoxville
International Journal of Offender Therapy and Comparative Criminology | Year: 2013
In this engagement with Professor Bruce Arrigo's psychological jurisprudence model, I explore his critique of captivity and risk management. I am particularly interested in his claims that incarceration culminates in society's own captivity, that the most destructive aspect of captivity is its foreclosing of human difference and potentiality, and that a praxis that is both clinical and mindful might point a way out. By way of a case anecdote, I interrogate several of the key terms in Arrigo's formulation - citizenship, reform, revolution, and praxis - in an effort to further conjugate from the ground up such an innovative and important set of possibilities. © The Author(s) 2013.
Simberloff D.,University of Tennessee at Knoxville
PLoS Biology | Year: 2014
The earliest concept of a balance of nature in Western thought saw it as being provided by gods but requiring human aid or encouragement for its maintenance. With the rise of Greek natural philosophy, emphasis shifted to traits gods endowed species with at the outset, rather than human actions, as key to maintaining the balance. The dominance of a constantly intervening God in the Middle Ages lessened interest in the inherent features of nature that would contribute to balance, but the Reformation led to renewed focus on such features, particularly traits of species that would maintain all of them but permit none to dominate nature. Darwin conceived of nature in balance, and his emphasis on competition and frequent tales of felicitous species interactions supported the idea of a balance of nature. But Darwin radically changed its underlying basis, from God to natural selection. Wallace was perhaps the first to challenge the very notion of a balance of nature as an undefined entity whose accuracy could not be tested. His skepticism was taken up again in the 20th century, culminating in a widespread rejection of the idea of a balance of nature by academic ecologists, who focus rather on a dynamic, often chaotic nature buffeted by constant disturbances. The balance-of-nature metaphor, however, lives on in large segments of the public, representing a fragile aspect of nature and biodiversity that it is our duty to protect. © 2014 Daniel Simberloff.
Lanzas C.,University of Tennessee at Knoxville |
Dubberke E.R.,University of Washington
Infection Control and Hospital Epidemiology | Year: 2014
Objective. Both asymptomatic and symptomatic Clostridium difficile carriers contribute to new colonizations and infections within a hospital, but current control strategies focus only on preventing transmission from symptomatic carriers. Our objective was to evaluate the potential effectiveness of methods targeting asymptomatic carriers to control C. difficile colonization and infection (CDI) rates in a hospital ward: screening patients at admission to detect asymptomatic C. difficile carriers and placing positive patients into contact precautions. Methods. We developed an agent-based transmission model for C. difficile that incorporates screening and contact precautions for asymptomatic carriers in a hospital ward. We simulated scenarios that vary according to screening test characteristics, colonization prevalence, and type of strain present at admission. Results. In our baseline scenario, on average, 42% of CDI cases were community-onset cases. Within the hospital-onset (HO) cases, approximately half were patients admitted as asymptomatic carriers who became symptomatic in the ward. On average, testing for asymptomatic carriers reduced the number of new colonizations and HO-CDI cases by 40%-50% and 10%-25%, respectively, compared with the baseline scenario. Test sensitivity, turnaround time, colonization prevalence at admission, and strain type had significant effects on testing efficacy. Conclusions. Testing for asymptomatic carriers at admission may reduce both the number of new colonizations and HO-CDI cases. Additional reductions could be achieved by preventing disease in patients who are admitted as asymptomatic carriers and developed CDI during the hospital stay. © 2014 by The Society for Healthcare Epidemiology of America. All rights reserved.
Mannella N.,University of Tennessee at Knoxville
Journal of Physics Condensed Matter | Year: 2014
The determination of the most appropriate starting point for the theoretical description of Fe-based materials hosting high-temperature superconductivity remains among the most important unsolved problem in this relatively new field. Most of the work to date has focused on the pnictides, with LaFeAsO, BaFe2As2 and LiFeAs being representative parent compounds of three families known as 1111, 122 and 111, respectively. This topical review examines recent progress in this area, with particular emphasis on the implication of experimental data which have provided evidence for the presence of electron itinerancy and the detection of local spin moments. In light of the results presented, the necessity of a theoretical framework contemplating the presence and the interplay between itinerant electrons and large spin moments is discussed. It is argued that the physics at the heart of the macroscopic properties of pnictides Fe-based high-temperature superconductors appears to be far more complex and interesting than initially predicted. © 2014 IOP Publishing Ltd.
Reynolds G.D.,University of Tennessee at Knoxville
Behavioural Brain Research | Year: 2015
This paper explores the role visual attention plays in the recognition of objects in infancy. Research and theory on the development of infant attention and recognition memory are reviewed in three major sections. The first section reviews some of the major findings and theory emerging from a rich tradition of behavioral research utilizing preferential looking tasks to examine visual attention and recognition memory in infancy. The second section examines research utilizing neural measures of attention and object recognition in infancy as well as research on brain-behavior relations in the early development of attention and recognition memory. The third section addresses potential areas of the brain involved in infant object recognition and visual attention. An integrated synthesis of some of the existing models of the development of visual attention is presented which may account for the observed changes in behavioral and neural measures of visual attention and object recognition that occur across infancy. © 2015 Elsevier B.V.
Gavrilets S.,University of Tennessee at Knoxville
PLoS computational biology | Year: 2010
A crucial step in several major evolutionary transitions is the division of labor between components of the emerging higher-level evolutionary unit. Examples include the separation of germ and soma in simple multicellular organisms, appearance of multiple cell types and organs in more complex organisms, and emergence of casts in eusocial insects. How the division of labor was achieved in the face of selfishness of lower-level units is controversial. I present a simple mathematical model describing the evolutionary emergence of the division of labor via developmental plasticity starting with a colony of undifferentiated cells and ending with completely differentiated multicellular organisms. I explore how the plausibility and the dynamics of the division of labor depend on its fitness advantage, mutation rate, costs of developmental plasticity, and the colony size. The model shows that the transition to differentiated multicellularity, which has happened many times in the history of life, can be achieved relatively easily. My approach is expandable in a number of directions including the emergence of multiple cell types, complex organs, or casts of eusocial insects.
Wilkins J.F.,Santa Fe Institute |
Ubeda F.,University of Tennessee at Knoxville
Progress in Molecular Biology and Translational Science | Year: 2011
Genomic imprinting is the phenomenon where the expression of a locus differs between the maternally and paternally inherited alleles. Typically, this manifests as transcriptional silencing of one of the alleles, although many genes are imprinted in a tissue- or isoform-specific manner. Diseases associated with imprinted genes include various cancers, disorders of growth and metabolism, and disorders in neurodevelopment, cognition, and behavior, including certain major psychiatric disorders. In many cases, the disease phenotypes associated with dysfunction at particular imprinted loci can be understood in terms of the evolutionary processes responsible for the origin of imprinting. Imprinted gene expression represents the outcome of an intragenomic evolutionary conflict, where natural selection favors different expression strategies for maternally and paternally inherited alleles. This conflict is reasonably well understood in the context of the early growth effects of imprinted genes, where paternally inherited alleles are selected to place a greater demand on maternal resources than are maternally inherited alleles. Less well understood are the origins of imprinted gene expression in the brain, and their effects on cognition and behavior. This chapter reviews the genetic diseases that are associated with imprinted genes, framed in terms of the evolutionary pressures acting on gene expression at those loci. We begin by reviewing the phenomenon and evolutionary origins of genomic imprinting. We then discuss diseases that are associated with genetic or epigenetic defects at particular imprinted loci, many of which are associated with abnormalities in growth and/or feeding behaviors that can be understood in terms of the asymmetric pressures of natural selection on maternally and paternally inherited alleles. We next described the evidence for imprinted gene effects on adult cognition and behavior, and the possible role of imprinted genes in the etiology of certain major psychiatric disorders. Finally, we conclude with a discussion of how imprinting, and the evolutionarygenetic conflicts that underlie it, may enhance both the frequency and morbidity of certain types of diseases. © 2011 Elsevier Inc.
Pighetti G.M.,University of Tennessee at Knoxville |
Elliott A.A.,University of Missouri
Journal of Mammary Gland Biology and Neoplasia | Year: 2011
One of the most frequent mammary diseases impacting lactating animals is mastitis, an inflammation of the mammary gland most commonly caused by bacterial infection. The severity of mastitis is greatly influenced by the invading organism and the subsequent immune response which must recognize the foreign organism, recruit immune cells, eliminate the invading pathogen, and resolve the inflammatory response. The speed, strength, and duration of this response and subsequent disease susceptibility are critically tied to the genetic background of an animal. However, the genetic contribution has been difficult to identify due to the complex interactions that must occur for effective disease resistance. Recent studies have utilized polymorphisms to better define the genes and chromosomal regions that contribute to mastitis resistance. This review will examine these studies with primary emphasis in bovine systems, as the most work regarding mastitis has been conducted in this species. © Springer Science+Business Media, LLC 2011.
Petrie A.,University of Tennessee at Knoxville
Computational Statistics and Data Analysis | Year: 2016
Testing whether two or more independent samples arise from a common distribution is a classic problem in statistics. Several multivariate two-sample tests of equality are based on graphs such as the minimum spanning tree, nearest neighbor, and optimal nonbipartite perfect matching. Here, the samples are pooled and the test statistic is the number of edges in the graph that connect points with different sample identities. These tests are typically unbiased and perform well when estimates of underlying probability densities are poor. However, these tests have not been thoroughly studied when data is very high dimensional or in the multisample case. We introduce the use of orthogonal perfect matchings for testing equality in distribution. A suite of Monte Carlo simulations on artificial and real data shows that orthogonal perfect matchings and spanning trees typically have higher power than other graphs and are also more effective at discerning when samples have differences in their covariance structure compared to other nonparametric tests such as the energy and triangle tests. © 2015 Elsevier B.V. All rights reserved.
Barber B.K.,University of Tennessee at Knoxville
Journal of Child Psychology and Psychiatry and Allied Disciplines | Year: 2013
Aims and method Drawing on empirical studies and literature reviews, this paper aims to clarify and qualify the relevance of resilience to youth experiencing political conflict. It focuses on the discordance between expectations of widespread dysfunction among conflict-affected youth and a body of empirical evidence that does not confirm these expectations. Findings The expectation for widespread dysfunction appears exaggerated, relying as it does on low correlations and on presumptions of universal response to adversity. Such a position ignores cultural differences in understanding and responding to adversity, and in the specific case of political conflict, it does not account for the critical role of ideologies and meaning systems that underlie the political conflict and shape a young people's interpretation of the conflict, and their exposure, participation, and processing of experiences. With respect to empirical evidence, the findings must be viewed as tentative given the primitive nature of research designs: namely, concentration on violence exposure as the primary risk factor, at the expense of recognizing war's impact on the broader ecology of youth's lives, including disruptions to key economic, social, and political resources; priority given to psychopathology in the assessment of youth functioning, rather than holistic assessments that would include social and institutional functioning and fit with cultural and normative expectations and transitions; and heavy reliance on cross-sectional, rather than longitudinal, studies. Conclusions Researchers and practitioners interested in employing resilience as a guiding construct will face such questions: Is resilience predicated on evidence of competent functioning across the breadth of risks associated with political conflict, across most or all domains of functioning, and/or across time? In reality, youth resilience amidst political conflict is likely a complex package of better and poorer functioning that varies over time and in direct relationship to social, economic, and political opportunities. Addressing this complexity will complicate the definition of resilience, but it confronts the ambiguities and limitations of work in cross-cultural contexts. © 2013 The Authors. Journal of Child Psychology and Psychiatry © 2013 Association for Child and Adolescent Mental Health.
MacLennan B.J.,University of Tennessee at Knoxville
International Journal of General Systems | Year: 2014
Future computing paradigms and technologies will have to be more like the physical processes by which they are realized, and because these processes are primarily continuous, post-Moore's law computing will involve an increased use of analog computation. Traditionally analog computers have computed ordinary differential equations of time, but analog field computation permits massively parallel temporal integration of partial differential equations. In principle many different physical media - not just electronics - can be exploited to implement the basic operations of analog computing, a small number of which are sufficient to approximate a wide variety of analog computations, thus providing a basis for universal analog computation and general-purpose analog computers. The contentious issue of the computational power of analog computers is addressed best on its own terms, rather by asking it within the context of Church-Turing computation, which distorts the relevant questions and their answers. © 2014 Taylor & Francis.
Perez-Garcia M.A.,University of Salamanca |
Silk J.,University of Oxford |
Stone J.R.,University of Oxford |
Stone J.R.,University of Tennessee at Knoxville
Physical Review Letters | Year: 2010
We show that self-annihilating weakly interacting massive particle (WIMP) dark matter accreted onto neutron stars may provide a mechanism to seed compact objects with long-lived lumps of strange quark matter, or strangelets, for WIMP masses above a few GeV. This effect may trigger a conversion of most of the star into a strange star. We use an energy estimate for the long-lived strangelet based on the Fermi-gas model combined with the MIT bag model to set a new limit on the possible values of the WIMP mass that can be especially relevant for subdominant species of massive neutralinos. © 2010 The American Physical Society.
Mollenkopf D.A.,University of Tennessee at Knoxville |
Frankel R.,University of North Florida |
Russo I.,University of Verona
Journal of Operations Management | Year: 2011
Managing the return flow of product is increasingly recognized as a strategically important activity that involves decisions and actions within and across firms. We focus specifically on returns management at the marketing-operations interface, by utilizing the conceptualization of customer value and its related drivers. In order to explore the phenomenon of returns management across a multi-disciplinary, managerial spectrum, a qualitative research methodology relying on individual managers' perceptions was chosen to generate depth of understanding given the limited current understanding of the research topic under consideration. Our results suggest that functional integration at the marketing-operations interface can lead to better alignment of corporate resources and thus create higher levels of customer value. We also found the external business environment to impact how and why a firm creates customer value through the returns management process. Overall, our results suggest that when returns management is recognized as a matter of a firm's competitiveness, the joint role of operations and marketing is imperative to success. © 2010 Elsevier B.V. All rights reserved.
Giraud T.,University Paris - Sud |
Gladieux P.,University Paris - Sud |
Gavrilets S.,University of Tennessee at Knoxville
Trends in Ecology and Evolution | Year: 2010
Emerging diseases represent a growing worldwide problem accompanying global environmental changes. There is tremendous interest in identifying the factors controlling the appearance and spread of these diseases. Here, we discuss emerging fungal plant diseases, and argue that they often result from host shift speciation (a particular case of ecological speciation). We consider the factors controlling local adaptation and ecological speciation, and show that certain life-history traits of many fungal plant pathogens are conducive for rapid ecological speciation, thus favoring the emergence of novel pathogen species adapted to new hosts. We argue that placing the problem of emerging fungal diseases of plants within the context of ecological speciation can significantly improve our understanding of the biological mechanisms governing the emergence of such diseases. © 2010 Elsevier Ltd.
Zhang F.,University of Washington |
Holleman J.,University of Tennessee at Knoxville |
Otis B.P.,University of Washington
IEEE Transactions on Biomedical Circuits and Systems | Year: 2012
Rapid development in miniature implantable electronics are expediting advances in neuroscience by allowing observation and control of neural activities. The first stage of an implantable biosignal recording system, a low-noise biopotential amplifier (BPA), is critical to the overall power and noise performance of the system. In order to integrate a large number of front-end amplifiers in multichannel implantable systems, the power consumption of each amplifier must be minimized. This paper introduces a closed-loop complementary-input amplifier, which has a bandwidth of 0.05 Hz to 10.5 kHz, an input-referred noise of 2.2 μ V rms , and a power dissipation of 12 μ W. As a point of comparison, a standard telescopic-cascode closed-loop amplifier with a 0.4 Hz to 8.5 kHz bandwidth, input-referred noise of 3.2 μ V rms , and power dissipation of 12.5 μ W is presented. Also for comparison, we show results from an open-loop complementary-input amplifier that exhibits an input-referred noise of 3.6 μ V rms while consuming 800 nW of power. The two closed-loop amplifiers are fabricated in a 0.13 μ m CMOS process. The open-loop amplifier is fabricated in a 0.5 μ m SOI-BiCMOS process. All three amplifiers operate with a 1 V supply. © 2007-2012 IEEE.
Rice W.R.,University of California at Santa Barbara |
Friberg U.,Uppsala University |
Gavrilets S.,University of Tennessee at Knoxville
BioEssays | Year: 2013
We recently synthesized and reinterpreted published studies to advance an epigenetic model for the development of homosexuality (HS). The model is based on epigenetic marks laid down in response to the XX vs. XY karyotype in embryonic stem cells. These marks boost sensitivity to testosterone in XY fetuses and lower it in XX fetuses, thereby canalizing sexual development. Our model predicts that a subset of these canalizing epigenetic marks stochastically carry over across generations and lead to mosaicism for sexual development in opposite-sex offspring - the homosexual phenotype being one such outcome. Here, we begin by outlining why HS has been under-appreciated as a commonplace phenomenon in nature, and how this trend is currently being reversed in the field of neurobiology. We next briefly describe our epigenetic model of HS, develop a set of predictions, and describe how epigenetic profiles of human stem cells can provide for a strong test of the model. © 2013 The Authors. Bioessays published by WILEY Periodicals, Inc.
Kravitz J.N.,University of Tennessee at Knoxville |
Berry M.W.,Medical University of South Carolina |
Schabel S.I.,Medical University of South Carolina |
Judson M.A.,Albany Medical College
Chest | Year: 2013
Background: Pulmonary aspergillomas may cause life-threatening hemoptysis. The treatment of this condition is problematic because poor pulmonary function often precludes definitive surgical resection. Methods: We retrospectively reviewed all patients hospitalized at our institution for hemoptysis associated with an aspergilloma over an 8-year period and who underwent percutaneous intracavitary instillation of amphotericin B (ICAB). ICAB consisted of catheter placement into the aspergilloma cavity with subsequent instillation of 50 mg amphotericin B in 20 mL 5% dextrose solution daily for 10 days. Results: ICAB was attempted for 23 distinct episodes of severe hemoptysis in 20 individual patients. Catheter placement was successful in 21 of the 23 episodes (91%), and of these, ICAB instillation was successfully completed in 20 episodes (95%). In these 20 episodes, hemoptysis ceased by hospital discharge in 17 of 20 patients (85%) and in all 18 who survived until a follow-up visit 1-month after treatment. Pneumothorax occurred in six of 23 (26%) catheter placement attempts without long-term complications. Recurrence of serious hemoptysis occurred after six of 18 episodes for which follow-up was available. Potential risk factors associated with severe, recurrent hemoptysis were a size increase or reappearance of the aspergilloma on a chest CT scan (P = .001), bleeding diathesis (P = .08), and lack of bronchial artery embolization during index hospitalization (P = .07). Conclusions: Our data suggest that ICAB is an effective short-term treatment to control severe hemoptysis caused by pulmonary aspergilloma. The long-term benefit of this procedure is unknown. We identified several potential risk factors for recurrent hemoptysis after ICAB that could be examined prospectively in future trials. © 2013 American College of Chest Physicians.
Fitzpatrick B.M.,University of Tennessee at Knoxville
Ecology and Evolution | Year: 2013
Understanding factors regulating hybrid fitness and gene exchange is a major research challenge for evolutionary biology. Genomic cline analysis has been used to evaluate alternative patterns of introgression, but only two models have been used widely and the approach has generally lacked a hypothesis testing framework for distinguishing effects of selection and drift. I propose two alternative cline models, implement multivariate outlier detection to identify markers associated with hybrid fitness, and simulate hybrid zone dynamics to evaluate the signatures of different modes of selection. Analysis of simulated data shows that previous approaches are prone to false positives (multinomial regression) or relatively insensitive to outlier loci affected by selection (Barton's concordance). The new, theory-based logit-logistic cline model is generally best at detecting loci affecting hybrid fitness. Although some generalizations can be made about different modes of selection, there is no one-to-one correspondence between pattern and process. These new methods will enhance our ability to extract important information about the genetics of reproductive isolation and hybrid fitness. However, much remains to be done to relate statistical patterns to particular evolutionary processes. The methods described here are implemented in a freely available package "HIest" for the R statistical software (CRAN; http://cran.r-project.org/). © 2013 The Authors. Ecology and Evolution.
McCain C.M.,University of Colorado at Boulder |
Sanders N.J.,University of Tennessee at Knoxville
Ecology | Year: 2010
The Metabolic Theory of Ecology (MTE) posits that the temperature-dependent kinetics of metabolism shape broad-scale patterns of biodiversity. Here we test whether the MTE accounts for patterns of diversity using 102 elevational diversity gradients of reptiles and amphibians. In particular, we examined the support for the two key predictions of the MTE: that the reciprocal of absolute temperature (1/kT) and diversity are linearly related and that the slope of that relationship is -0.65. We also tested two underlying assumptions of the MTE in cases with appropriate data, namely, that abundance is invariant among samples, and that behavioral thermoregulation influences the MTE predictions. We found that few studies supported the predictions of the MTE for the relationship between environmental temperature and elevational diversity using previous methods on individual gradients and using metaanalysis. The predominant relationship was curvilinear, and the slopes were steeper than predicted. In analyses of individual gradients, only 6% followed the MTE predictions in the strictest application, and 25% in the broadest. We found violations of the assumption of invariant abundances in all five test cases. All four herpetofaunal groups, regardless of behavioral thermoregulatory abilities, demonstrated poor fits to the MTE predictions. Even when arid gradients are removed, ameliorating the potential effects of water limitation, the MTE did not account for herpetofaunal elevational diversity. We conclude that an interplay of factors shapes elevational diversity gradients rather than the simple kinetics of biochemical reactions. © 2010 by the Ecological Society of America.
Pruitt J.N.,University of Tennessee at Knoxville
Functional Ecology | Year: 2010
Many animals are adapted for a 'feast or famine' existence, and will opportunistically engage in gluttonous foraging bouts. However, how gluttonous feeding influences individual performance (e.g. running speed) and the fitness consequence of modified performance are not frequently considered. Using laboratory track trials I establish baseline locomotor performances (burst speed) for four spider species: two active foragers (Hogna helluo and Schizocosa ocreata (family: Lycosidae)), and two sit-and-wait foragers (Agelenopsis emertoni and Barronopsis texana (family: Agelenidae)). I then fed each species ad libitum, assessed what influence this meal had on individuals' burst speed relative to baseline performance, and performed a field census to assess selection on running speed for all four species. Sit-and-wait foragers fed significantly more than active foragers and slowed significantly after feeding; however, neither active forager was slowed by their meal. My field census detected no selection on speed for sit-and-wait foragers, and positive directional selection on speed for both active foragers. The negative association between the amount of food consumed and selection on burst speed suggests that selection pressures to maintain locomotor performance may set an upper limit to how much an animal can, or will, eat during a foraging bout. © 2009 The Author. Journal compilation © 2009 British Ecological Society.
Keppens V.,University of Tennessee at Knoxville
Nature Materials | Year: 2013
Ferroelectric materials exhibit an intrinsic electric polarization that can be changed or reversed by an applied electric field. While initially ferroelectrics were little more than an academic curiosity, today they can be found at the heart of many technological devices that exploit their ferro-, piezo- and pyroelectric properties, with the most advanced application perhaps being that of ferroelectric non-volatile memories. The structure of the low-temperature ferroelectric material is always non-centrosymmetric, and therefore does not display inversion symmetry, as this prevents the charge separation inherent to the electric polarization. The compound BaTiO3 is often regarded as the prototypical ferroelectric, belonging to a family of ferroelectrics known as perovskite oxides. The low-temperature ferroelectric phase is obtained from small symmetry-breaking displacements of the Li atoms, with the loss of the inversion symmetry resulting in a spontaneous polarization at 1,483 K.
Salafranca J.,University of Tennessee at Knoxville |
Salafranca J.,Oak Ridge National Laboratory |
Okamoto S.,Oak Ridge National Laboratory
Physical Review Letters | Year: 2010
The proximity effect in a model manganite-cuprate system is investigated theoretically. We consider a situation in which spin-polarized electrons in manganite layers antiferromagnetically couple with electrons in cuprate layers as observed experimentally. The effect of the interfacial magnetic coupling is found to be much stronger than the injection of spin-polarized electrons into the cuprate region. As a result, the superconducting transition temperature depends on the thickness of the cuprate layer significantly. Since the magnetic coupling creates negative polarization, an applied magnetic field and the negative polarization compete, resulting in the inverse spin-switch behavior where the superconducting transition temperature is increased by applying a magnetic field. © 2010 The American Physical Society.
Davies A.G.,Jet Propulsion Laboratory |
Ennis M.E.,University of Tennessee at Knoxville
Icarus | Year: 2011
Zamama, Culann, and Tupan Patera are three large, persistent volcanic centers on the jovian moon Io. As part of an ongoing project to quantify contributions from individual volcanic centers to Io's thermal budget, we have quantified the radiant flux from all suitable observations made by the Galileo Near Infrared Mapping Spectrometer (NIMS) of these volcanoes, in some cases filling omissions in previous analyses. At Zamama, after a long period of cooling, we see a peak in thermal emission that corresponds with new plume activity. Subsequently, toward the end of the Galileo epoch, thermal emission from Zamama drops off in a manner consistent with a greatly reduced eruption rate and the cooling of emplaced flows. Culann exhibits possible episodic activity. We present the full Tupan Patera NIMS dataset and derive new estimates of thermal output and temporal behavior. Eruption rates at these three volcanoes are on the order of 30m3s-1, consistent with a previous analysis of NIMS observations of Prometheus, and nearly an order of magnitude greater than Kilauea volcano, Hawai'i, Earth's most active volcano. We propose that future missions to the jovian system could better constrain activity at these volcanoes and others where similar styles of activity are taking place by obtaining data on a time scale of, ideally, at least one observation per day. Observations at similar or even shorter timescales are desirable during initial waxing phases of eruption episodes. These eruptions are identifiable from their characteristic spectral signatures and temporal behavior. © 2011 Elsevier Inc.
Godsoe W.,University of Tennessee at Knoxville
Oikos | Year: 2010
The niche is one of the most important concepts in ecology. However, there has been a persistent controversy on how to define, measure, and predict the ecological niche of an organism. Here I argue that these problems arise in part because the niche is defined by the set of all possible environments, many of which do not exist in nature. A complete description of the niche would require knowledge of a large number of environments that do not exist in nature. Given this, I propose that ecologists should not focus on the niche itself but instead on determining if a particular environment is a part of the niche. I then demonstrate that such an analysis has a natural interpretation as an estimate of the probability that an environment is suitable and that either experimental investigations or analyses of presence data can estimate this quantity. Depending on the way that resources interact to shape environmental requirements, the probability that an environment is a part of the niche behaves like published descriptions of causal inferences and distribution models. However, in some cases the probability that an environment is suitable can be strongly influenced by unmeasured aspects of the environment. When this is true, experimental and distribution models have complimentary strengths and weaknesses. © 2009 Oikos.
Cihak D.F.,University of Tennessee at Knoxville
Research in Autism Spectrum Disorders | Year: 2010
This study evaluated the differential effects of two different visual schedule strategies. In the context of an alternating treatments design, static-picture schedules were compared to video based activity schedules as supports for three middle school aged students with autism. Students used the visual schedules to transition between activities in their classroom. All participants began transition more independently after being exposed to the visual schedules. Two participants reached criteria faster with static-picture schedules while the third participant made slightly faster progress with the video based schedule. The positive outcomes for both interventions are discussed in the context of practitioners' need for a variety of evidenced based practices to meet the needs of a diverse student body as well and that similar interventions may have different outcomes depending on the characteristics and preferences of the learner. © 2011 Elsevier Ltd. All rights reserved.
Sun X.-G.,Oak Ridge National Laboratory |
Wang X.,Oak Ridge National Laboratory |
Mayes R.T.,Oak Ridge National Laboratory |
Dai S.,Oak Ridge National Laboratory |
Dai S.,University of Tennessee at Knoxville
ChemSusChem | Year: 2012
Nitrogen-doped mesoporous carbon (NC) and sulfur were used to prepare an NC/S composite cathode, which was evaluated in an ionic-liquid electrolyte of 0.5 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in methylpropylpyrrolidinium bis(trifluoromethane sulfonyl)imide ([MPPY][TFSI]) by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cycle testing. To facilitate the comparison, a C/S composite based on activated carbon (AC) without nitrogen doping was also fabricated under the same conditions. Compared with the AC/S composite, the NC/S composite showed enhanced activity toward sulfur reduction, as evidenced by the lower onset sulfur reduction potential, higher redox current density in the CV test, and faster charge-transfer kinetics, as indicated by EIS measurements. At room temperature under a current density of 84 mA g -1 (C/20), the battery based on the NC/S composite exhibited a higher discharge potential and an initial capacity of 1420 mAh g -1, whereas the battery based on the AC/S composite showed a lower discharge potential and an initial capacity of 1120 mAh g -1. Both batteries showed similar capacity fading with cycling due to the intrinsic polysulfide solubility and the polysulfide shuttle mechanism; capacity fading can be improved by further cathode modification. NC vs. AC: Nitrogen-doped mesoporous carbon (NC) is prepared by heat treatment of mesoporous carbon under NH 3 at 850 °C. Compared with KOH-activated mesoporous carbon (AC), NC shows catalytic activity towards sulfur reduction. Furthermore, under the same current rates, NC/S composite shows a higher discharge potential and capacity than the AC/S composite in an ionic-liquid electrolyte both at 25 °C and 50 °C. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Sanders N.J.,University of Tennessee at Knoxville
Molecular Ecology | Year: 2010
What allows some species to successfully colonize a novel environment while others fail? Numerous studies in invasion biology have sought to answer this question, but those studies have tended to focus on traits of species or individuals (e.g. body size, seed size, seed number), and these traits have largely been found to be weak predictors of invasion success. However, characteristics of colonizing populations (e.g. genetic diversity, density, age structure) might also be important for successful establishment, as the authors of a study published in this issue of Molecular Ecology show (Crawford & Whitney 2010). By experimentally manipulating the density and genetic diversity of colonizing populations of Arabidopsis thaliana, the authors found that genetic diversity, but not population density, increased colonization success. Importantly, the effects of genetic diversity on colonization success were both additive and non-additive, suggesting that traits associated with particular genotypes and complimentarity among genotypes contribute to colonization success. This research highlights the importance of considering within-species variation and characteristics of entire populations in predicting colonization success. © 2010 Blackwell Publishing Ltd.
Voy B.H.,University of Tennessee at Knoxville
Journal of Nutrition | Year: 2011
Genetic variation in a population creates an impressive spectrum of phenotypic diversity, particularly when changes in diet or the environment are imposed on the population. Genome-wide association studies have become a powerful tool for linking sequence variants with overlying systems level phenotypes, but they do not provide insight into the mechanisms through which genetic variation drives phenotypic variation. Systems genetics is an emerging discipline that provides a means to fill this knowledge gap by assembling the hierarchy of interactions among genes, proteins, and other intermediate phenotypes that manifest as phenotypic variation. When applied to nutrition, systems genetics enables the identification of pathways through which nutrients influence health and the determination of the mechanisms that cause individuals to differ in their response to diet. © 2011 American Society for Nutrition.
Stromdahl E.Y.,U.S. Army |
Hickling G.J.,University of Tennessee at Knoxville
Zoonoses and Public Health | Year: 2012
Since its emergence in the north-eastern and upper mid-western United States in the 1970s, Lyme disease, caused by Borrelia burgdorferi, has captured the public's attention as the nation's most prevalent vector-borne zoonotic disease. In contrast, recent publications on tick-pathogen systems in the eastern United States, and findings from Department of Defense investigations of ticks found biting military personnel, indicate that residents of the south-eastern United States are primarily at risk from emerging diseases caused by tick-borne pathogens other than B. burgdorferi. The risk of contracting these diseases varies greatly among states as a consequence of regional variation in the abundance of the key vector tick species. Moreover, this risk is changing, because tick distributions are in flux. To improve health outcomes, health providers need better information and awareness regarding which tick species bite humans in each state and which zoonotic pathogens are prevalent in these ticks. Effective diagnosis, treatment, control and reporting of tick-borne disease in the south-eastern United States require that health providers think 'beyond Lyme' and consider the marked regional differences in the tick species that bite humans and in the pathogens that these ticks carry. © 2012 Blackwell Verlag GmbH.
Choi S.H.,University of Tennessee at Knoxville
Journal of Aging and Health | Year: 2012
Objectives: This study tested a healthy immigrant effect (HIE) and postimmigration health status changes among late life immigrants. Methods: Using three waves of the Second Longitudinal Study of Aging (1994-2000) and the linked mortality file through 2006, this study compared (a) chronic health conditions, (b) longitudinal trajectories of self-rated health, (c) longitudinal trajectories of functional impairments, and (d) mortality between three groups (age 70+): (i) late life immigrants with less than 15 years in the United States (n = 133), (ii) longer term immigrants (n = 672), and (iii) U.S.-born individuals (n = 8,642). Logistic and Poisson regression, hierarchical generalized linear modeling, and survival analyses were conducted. Results: Late life immigrants were less likely to suffer from cancer, had lower numbers of chronic conditions at baseline, and displayed lower hazards of mortality during the 12-year follow-up. However, their self-rated health and functional status were worse than those of their counterparts over time. Conclusion: A HIE was only partially supported among older adults. © The Author(s) 2012.
Mazur P.,University of Tennessee at Knoxville
Cryobiology | Year: 2010
Thermodynamics and physical chemistry have played powerful roles the past 45 years in interpreting cryobiological problems and in predicting cryobiological outcomes. The author has been guided by a few core principles in using these concepts and tools and this paper discusses these core principles. They are (1) the importance of chemical potentials and of the difference between the chemical potentials of water and solutes inside the cell and outside in determining the direction and rate of fluxes of water and solutes. (2) The influence of the curvature of an ice crystal on its chemical potential and on the ability of ice to pass through pores in cell membranes, on the nucleation temperature of supercooled water, and on the recrystallization of ice. (3) The use of Le Chatalier's Principle in qualitatively predicting the direction of a reaction in response to variables like pressure. (4) The fact that the energy differences between State A and State B are independent of the path taken to go from A to B. (5) The importance of being aware of the assumptions underlying thermodynamic models of cryobiological events. And (6), the difficulties in obtaining experimental verification of thermodynamic and physical-chemical models. © 2009 Elsevier Inc. All rights reserved.
Vogt F.,University of Tennessee at Knoxville
Journal of Chemometrics | Year: 2014
Assessing current trends in chemometric publications reveals that most projects utilize known methodologies and fall into the category "application." There seems to be worrying little of true innovation unless one counts "fashions" assimilated from other fields. The field may have reached a crossroad: One path leads to chemometrics becoming a fully mature but stagnant tool for analytical chemists; the other path, that is, maintaining chemometrics as an active and widely recognized research field, requires opening new research areas for chemometricians. It is argued that hard modeling as opposed to the ubiquitous soft modeling may become such a new direction. Hard modeling would focus on investigating chemical mechanisms that give raise to measured data as opposed to empirically analyzing data.Furthermore, chemometricians in academia are responsible for preparing the next generation of chemometricians. Despite the need for chemometricians in the workforce, the number of young chemometricians is low and will remain low unless changes in chemistry curricula happen. This remains a challenge because there are fundamental issues that need to be overcome. © 2014 John Wiley & Sons, Ltd.
Lelu M.,University of Tennessee at Knoxville
Proceedings. Biological sciences / The Royal Society | Year: 2013
Parasites with complex life cycles are expected to manipulate the behaviour of their intermediate hosts (IHs), which increase their predation rate and facilitate the transmission to definitive hosts (DHs). This ability, however, is a double-edged sword when the parasite can also be transmitted vertically in the IH. In this situation, as the manipulation of the IH behaviour increases the IH death rate, it conflicts with vertical transmission, which requires healthy and reproducing IHs. The protozoan Toxoplasma gondii, a widespread pathogen, combines both trophic and vertical transmission strategies. Is parasite manipulation of host behaviour still adaptive in this situation? We model the evolution of the IH manipulation by T. gondii to study the conflict between these two routes of transmission under different epidemiological situations. Model outputs show that manipulation is particularly advantageous for virulent strains and in epidemic situations, and that different levels of manipulation may evolve depending on the sex of the IH and the transmission routes considered. These results may help to understand the variability of strain characteristics encountered for T. gondii and may extend to other trophically transmitted parasites.
Li H.,University of Tennessee at Knoxville |
Han Z.,University of Houston
IEEE Transactions on Wireless Communications | Year: 2011
The main challenge to cognitive radio is the emergence of primary users, which can be considered as the service interruptions in a queuing system. The service interruption can incur significant delays for secondary users' data packets which are considered as secondary customers. Therefore, a secondary customer needs to decide whether to join the queue or leave for other means of transmission. It is shown that the individually optimal strategy for joining the queue is characterized by a threshold of queue length. When the current queue length is above this threshold, the secondary customer should leave; otherwise it should join the queue. The socially optimal threshold of queue length is also obtained and is numerically shown to be smaller than the individually optimal one, which implies that the individually optimal strategy does not yield the socially optimal one. To bridge the gap between the individually and socially optimal strategies, a pricing mechanism is proposed to toll the service of each secondary customer, thus equalizing the two optimal strategies. When the channel statistics are unknown, an online learning procedure, based on the Kiefer-Wolfowitz algorithm, is proposed. The proposed algorithms are then demonstrated using numerical simulations. © 2011 IEEE.
Coble J.B.,University of Tennessee at Knoxville |
Fraga C.G.,Pacific Northwest National Laboratory
Journal of Chromatography A | Year: 2014
Preprocessing software, which converts large instrumental data sets into a manageable format for data analysis, is crucial for the discovery of chemical signatures in metabolomics, chemical forensics, and other signature-focused disciplines. Here, four freely available and published preprocessing tools known as MetAlign, MZmine, SpectConnect, and XCMS were evaluated for impurity profiling using nominal mass GC/MS data and accurate mass LC/MS data. Both data sets were previously collected from the analysis of replicate samples from multiple stocks of a nerve-agent precursor and method blanks. Parameters were optimized for each of the four tools for the untargeted detection, matching, and cataloging of chromatographic peaks from impurities present in the stock samples. The peak table generated by each preprocessing tool was analyzed to determine the number of impurity components detected in all replicate samples per stock and absent in the method blanks. A cumulative set of impurity components was then generated using all available peak tables and used as a reference to calculate the percent of component detections for each tool, in which 100% indicated the detection of every known component present in a stock. For the nominal mass GC/MS data, MetAlign had the most component detections followed by MZmine, SpectConnect, and XCMS with detection percentages of 83, 60, 47, and 41%, respectively. For the accurate mass LC/MS data, the order was MetAlign, XCMS, and MZmine with detection percentages of 80, 45, and 35%, respectively. SpectConnect did not function for the accurate mass LC/MS data. Larger detection percentages were obtained by combining the top performer with at least one of the other tools such as 96% by combining MetAlign with MZmine for the GC/MS data and 93% by combining MetAlign with XCMS for the LC/MS data. In terms of quantitative performance, the reported peak intensities from each tool had averaged absolute biases (relative to peak intensities obtained using instrument software) of 41, 4.4, 1.3 and 1.3% for SpectConnect, MetAlign, XCMS, and MZmine, respectively, for the GC/MS data. For the LC/MS data, the averaged absolute biases were 22, 4.5, and 3.1% for MetAlign, MZmine, and XCMS, respectively. In summary, MetAlign performed the best in terms of the number of component detections; however, more than one preprocessing tool should be considered to avoid missing impurities or other trace components as potential chemical signatures. © 2014 Elsevier B.V.
Zhao L.,University of Tennessee at Knoxville |
Lee J.Y.,Gwangju Institute of Science and Technology |
Hwang D.H.,University of California at Davis
Nutrition Reviews | Year: 2011
Emerging evidence reveals that pattern-recognition receptors (PRRs), Toll-like receptors (TLRs), and nucleotide-binding oligomerization domain proteins (NODs) mediate both infection-induced and sterile inflammation by recognizing pathogen-associated molecular patterns and endogenous molecules, respectively. PRR-mediated chronic inflammation is a determinant for the development and progression of chronic diseases including cancer, atherosclerosis, and insulin resistance. Recent studies demonstrated that certain phytochemicals inhibit PRR-mediated pro-inflammation. Curcumin, helenalin, and cinnamaldehyde with α, β-unsaturated carbonyl groups, or sulforaphane with an isothiocyanate group, inhibit TLR4 activation by interfering with cysteine residue-mediated receptor dimerization, while resveratrol, with no unsaturated carbonyl group, did not. Similarly, curcumin, parthenolide, and helenalin, but not resveratrol and (-)-epigallocatechin-3-gallate (EGCG), also inhibit NOD2 activation by interfering with NOD2 dimerization. In contrast, resveratrol, EGCG, luteolin, and structural analogs of luteolin specifically inhibit TLR3 and TLR4 signaling by targeting TANK binding kinase 1 (TBK1) and receptor interacting protein 1 (RIP1) in Toll/IL-1 receptor domain-containing adaptor inducing IFN-β (TRIF) complex. Together, these results suggest that PRRs and downstream signaling components are molecular targets for dietary strategies to reduce PRR-mediated chronic inflammation and consequent risks of chronic diseases. © 2011 International Life Sciences Institute.
Peacock J.C.,University of Tennessee at Chattanooga |
Sloan S.S.,University of Tennessee at Knoxville |
Cripps B.,University of Tennessee at Chattanooga
Obesity Surgery | Year: 2014
Research has shown that some bariatric patients overestimate post-surgical exercise levels, while others struggle with negative cognitions and follow-through on intentions to exercise; however, little exists on specific barriers affecting bariatric patients' post-surgical exercise behaviors. Considering that regular exercise is a predictor of weight loss maintenance, further research is warranted. Survey methodology was utilized to assess post-operative exercise barriers as well as beneficial post-surgical exercise services among a sample of bariatric patients solicited from an online support website. Qualitative assessment of responses was completed using inductive content analysis. Higher-order themes for exercise barriers included internal, external, and no barriers; generic categories determined for internal barriers included motivational and physical barriers. Of the participants, 78 % reported at least one internal motivational barrier, and the most frequently reported subcategorical barrier was time (28 %); physical barriers were reported related to surgery (9 %) or other chronic conditions (19 %). Higher-order themes for exercise services included positive descriptions such as benefits from exercise prescription as well as the importance of facilities and individuals, while negative descriptions included no services available or services that were unhelpful. Participants cited the benefit of community-based facilities, so providers might consider partnering with local professionals to deliver exercise services. Staff should be aware of physical barriers specific to bariatric populations including issues with post-surgical stamina and chronic comorbid conditions in order to provide appropriate exercise prescription. In addition, as motivational and time barriers occur frequently, providers should be well-trained on how to help patients overcome these impediments to exercise maintenance. © 2013 Springer Science+Business Media New York.
Floden A.,University of Tennessee at Knoxville
Annales Botanici Fennici | Year: 2014
Heteropolygonatum urceolatum J.M.H. Shaw (Asparagaceae), is transferred to Polygonatum based on morphological and cytological evidence. Polygonatum mengtzense F.T. Wang and T. Tang is reinstated to specific status and its description amended based on examination of ample living and herbarium material. Chromosome counts and karyotypes are presented for both species that provide evidence that the two are most closely related to the Himalayan P. punctatum. Data on their distribution and habitat are provided. A key morphological trait of Heteropolygonatum, terminal inflorescences, is discussed in relation to the generic value of this character and shown not to be diagnostic. © 2014 Finnish Zoological and Botanical Publishing Board.
Bland W.,University of Tennessee at Knoxville
Proceedings - 12th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing, CCGrid 2012 | Year: 2012
As recent research has demonstrated, it is becoming a necessity for large scale applications to have the ability to tolerate process failure during an execution. As the number of processes increases, checkpoint/restart fault tolerance approaches requiring large concurrent state check pointing become untenable and radically new methods to address fault tolerance are needed. This work addresses these challenges by proposing a novel approach to a minimalistic fault discovery and management model. Such a model allows application to run to completion despite fail-stop failures. As a proof of concept, in addition to the proposed fault tolerance model, an implementation in the context of the Open MPI library is provided, evaluated and analyzed. © 2012 IEEE.
Burghardt G.M.,University of Tennessee at Knoxville
Current Biology | Year: 2015
In this quick guide, Gordon Burghardt considers the criteria for ascribing a particular animal behavior as "play", and in particular the evidence for play in fishes, frogs and reptiles. © 2015 Elsevier Ltd. All rights reserved.
Bose B.K.,University of Tennessee at Knoxville
IEEE Transactions on Industrial Electronics | Year: 2013
Power electronics technology has gained significant maturity after several decades of dynamic evolution of power semiconductor devices, converters, pulse width modulation (PWM) techniques, electrical machines, motor drives, advanced control, and simulation techniques. According to the estimate of the Electric Power Research Institute, roughly 70% of electrical energy in the USA now flows through power electronics, which will eventually grow to 100%. In the 21st century, we expect to see the tremendous impact of power electronics not only in global industrialization and general energy systems, but also in energy saving, renewable energy systems, and electric/hybrid vehicles. The resulting impact in mitigating climate change problems is expected to be enormous. This paper, in the beginning, will discuss the global energy scenario, climate change problems, and the methods of their mitigation. Then, it will discuss the impact of power electronics in energy saving, renewable energy systems, bulk energy storage, and electric/hybrid vehicles. Finally, it will review several example applications before coming to conclusion and future prognosis. © 1982-2012 IEEE.
Gao W.,University of Tennessee at Knoxville |
Cao G.,Pennsylvania State University |
La Porta T.,Pennsylvania State University |
Han J.,University of Illinois at Urbana - Champaign
IEEE Transactions on Mobile Computing | Year: 2013
Unpredictable node mobility, low node density, and lack of global information make it challenging to achieve effective data forwarding in Delay-Tolerant Networks (DTNs). Most of the current data forwarding schemes choose the nodes with the best cumulative capability of contacting others as relays to carry and forward data, but these nodes may not be the best relay choices within a short time period due to the heterogeneity of transient node contact characteristics. In this paper, we propose a novel approach to improve the performance of data forwarding with a short time constraint in DTNs by exploiting the transient social contact patterns. These patterns represent the transient characteristics of contact distribution, network connectivity and social community structure in DTNs, and we provide analytical formulations on these patterns based on experimental studies of realistic DTN traces. We then propose appropriate forwarding metrics based on these patterns to improve the effectiveness of data forwarding. When applied to various data forwarding strategies, our proposed forwarding metrics achieve much better performance compared to existing schemes with similar forwarding cost. © 2002-2012 IEEE.
Kuo W.,City University of Hong Kong |
Zhu X.,University of Tennessee at Knoxville
IEEE Transactions on Reliability | Year: 2012
To identify the critical components or sets of components in a system, various importance measures have been proposed with different probabilistic perspectives and applications. Many of these importance measures are actually related to each other in some ways. This paper summarizes the importance measures in reliability, and presents relations and comparisons among them, focusing on their interrelations to the B-importance, the dominant relations among them, the dual relations, their performances in typical systems, and their computations. The early versions of the importance measures are for binary coherent systems, while the recent research is not limited to this type of system. This paper investigates the extensions of importance measures in noncoherent systems, multistate systems, continuum systems, and repairable systems. © 2012 IEEE.
Sheffield S.L.,University of Tennessee at Knoxville
Palaeoworld | Year: 2015
The erisocrinid Sinocrinus differs from other erisocrinid genera (Erisocrinus and Exaetocrinus) by possessing a rounded, bowl-shaped cup, bearing tumid cup plates with impressed sutures. Sinocrinus Tien, 1926 is refined using Principal Component Analysis and neighborhood cluster analysis. The genotype of Sinocrinus, S. microgranulosus Tien, 1926, is a junior subjective synonym of S. granulatus (Wanner, 1924). Sinocrinus [ Erisocrinus] stefaninii (Yakovlev, 1934) is a junior synonym of Sinocrinus lichengensis Tien, 1926 and S. asymmetricus Strimple and Watkins, 1969 is the junior synonym of S. sheareri Strimple and Watkins, 1969. Other valid species include: S. [ Erisocrinus] cernuus (Trautschold, 1867); S. [ Erisocrinus] obliquus (Wanner, 1916); S. houkouensis Tien, 1926; S. nodosus Tien, 1926; S. [ Erisocrinus] stefaninii (Yakovlev, 1934). Because of its refined inclusiveness, the temporal span of the genus now extends from the Late Carboniferous (Moscovian) through the early Permian (Sakmarion). This study also widens the current geographic range of Sinocrinus, with specimens collected across a wider span of Eurasia. © 2015 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS.
Li Y.,National Health Research Institute |
Parker L.E.,University of Tennessee at Knoxville
Information Fusion | Year: 2014
Missing data is common in Wireless Sensor Networks (WSNs), especially with multi-hop communications. There are many reasons for this phenomenon, such as unstable wireless communications, synchronization issues, and unreliable sensors. Unfortunately, missing data creates a number of problems for WSNs. First, since most sensor nodes in the network are battery-powered, it is too expensive to have the nodes re-transmit missing data across the network. Data re-transmission may also cause time delays when detecting abnormal changes in an environment. Furthermore, localized reasoning techniques on sensor nodes (such as machine learning algorithms to classify states of the environment) are generally not robust enough to handle missing data. Since sensor data collected by a WSN is generally correlated in time and space, we illustrate how replacing missing sensor values with spatially and temporally correlated sensor values can significantly improve the network's performance. However, our studies show that it is important to determine which nodes are spatially and temporally correlated with each other. Simple techniques based on Euclidean distance are not sufficient for complex environmental deployments. Thus, we have developed a novel Nearest Neighbor (NN) imputation method that estimates missing data in WSNs by learning spatial and temporal correlations between sensor nodes. To improve the search time, we utilize a kd-tree data structure, which is a non-parametric, data-driven binary search tree. Instead of using traditional mean and variance of each dimension for kd-tree construction, and Euclidean distance for kd-tree search, we use weighted variances and weighted Euclidean distances based on measured percentages of missing data. We have evaluated this approach through experiments on sensor data from a volcano dataset collected by a network of Crossbow motes, as well as experiments using sensor data from a highway traffic monitoring application. Our experimental results show that our proposed K-NN imputation method has a competitive accuracy with state-of-the-art Expectation-Maximization (EM) techniques, while using much simpler computational techniques, thus making it suitable for use in resource-constrained WSNs. © 2013 Elsevier Ltd. All rights reserved.
Black E.A.,University of Tennessee at Knoxville
The Iowa orthopaedic journal | Year: 2011
Open fractures of the pelvis remain a devastating injury with a high mortality and morbidity. Such injuries require an aggressive treatment plan and the coordination of trauma and orthopaedic surgeons to achieve the best outcomes. We report our experience at the University of Tennessee Medical Center at Knoxville with open pelvic fractures over the last ten years. After IRB and institutional approval, we reviewed patients admitted with a diagnosis of open fracture of the pelvis from 1999 to 2009. Demographic and admission data were recorded in the trauma registry (TRACS) of the Level I Trauma Center, serving the 1.2 million people living in the regions of east Tennessee, western North Carolina and southeastern Kentucky. Data on fractures were obtained from review of the medical records and radiographs within the chart. There were 3053 pelvic fractures from January 1999 to December 2009. There were 231 deaths in this group (6%) and ages ranged from 18 to 89 years old and Injury Severity Scores ranged from 4 to 75, with a mean of 18.3. Seventy five percent of patients were able to be discharged home. Fifty-two fractures were open. There were 43 men and the mean age was 39 years old. Average ISS was 23 and ranged from 5 to 50. There were 10 deaths (19%) and eight patients underwent angioembolization for control of bleeding (3 deaths). Motorcycle crashes were the most frequent cause of an open fracture, with lateral compression injuries representing 71%. A defined algorithm for fracture management has been in place and employed to assure adequate resuscitation and fracture care and is presented. Open pelvic fractures are usually the result of a high energy transfer, and convey a high morbidity and mortality. A defined resuscitation and fixation strategy improves outcome from historical reports. Injuries from penetrating mechanisms are associated with less morbidity and lower mortality.
Churilla J.R.,University of North Florida |
Fitzhugh E.C.,University of Tennessee at Knoxville
Metabolic Syndrome and Related Disorders | Year: 2012
Background: This study examined the association of total physical activity volume (TPAV) and physical activity (PA) from three domains [leisure-time physical activity (LTPA), domestic, transportation] with metabolic syndrome. We also investigated the relationship between LTPA intensity and metabolic syndrome risk. Methods: Sample included adults who participated in the 1999-2004 National Health and Nutrition Examination Survey. Physical activity measures were created for TPAV, LTPA, domestic PA, and transportational PA. For each, a six-level measure based upon no PA (level 1) and quintiles (levels 2-6) of metabolic equivalents (MET)•min•wk -1 was created. A three-level variable associated with the current Department of Health and Human Services (DHHS) PA recommendation was also created. SAS and SUDAAN were used for the statistical analysis. Results: Adults reporting the greatest volume of TPAV and LTPA were found to be 36% [odds ratio (OR) 0.64; 95% confidence interval (CI) 0.49-0.83] and 42% (OR 0.58; 95% CI 0.43-0.77), respectively, less likely to have metabolic syndrome. Domestic and transportational PA provided no specific level of protection from metabolic syndrome. Those reporting a TPAV that met the DHHS PA recommendation were found to be 33% (OR 0.67; 95%; CI 0.55-0.83) less likely to have metabolic syndrome compared to their sedentary counterparts. Adults reporting engaging in only vigorous-intensity LTPA were found to be 37% (OR 0.63; 95 CI 0.42-0.96) to 56% (OR 0.44; 95% CI 0.29-0.67) less likely to have metabolic syndrome. Conclusions: Volume, intensity, and domain of PA may all play important roles in reducing the prevalence and risk of metabolic syndrome. © 2012, Mary Ann Liebert, Inc.
Burghardt G.M.,University of Tennessee at Knoxville
Behavioral and Brain Sciences | Year: 2013
Van de Vliert proposes a comprehensive explanation for differences in freedoms in diverse human populations based on climate and monetary resources. This intriguing approach, though derived from an evolutionary view covering all species, is based exclusively on human populations. This anthropocentric lens is challenged by ways of testing Van de Vliert's thesis more generally using playfulness as a surrogate for freedom. Copyright © 2013 Cambridge University Press.
Hedberg T.,University of Tennessee at Knoxville
Environmental Values | Year: 2016
In Animal Ethics in Context, Clare Palmer tries to harmonise two competing approaches to animal ethics. One focuses on the morally relevant capacities that animals possess. The other is the Laissez-Faire Intuition (LFI): the claim that we have duties to assist domesticated animals but should (at least generally) leave wild animals alone. In this paper, I critique the arguments that Palmer offers in favour of the No-Contact LFI–the view that we have (prima facie) duties not to harm wild animals but no duties to assist them. I argue that Palmer’s endorsement of the No-Contact LFI is unwarranted. Her arguments actually provide strong reasons to endorse what I call the Gradient View–a position that posits weak presumptive duties to assist wild animals that become stronger as our relations with the animals grow stronger. © 2016 The White Horse Press.
MacLennan B.J.,University of Tennessee at Knoxville
Proceedings of the IEEE | Year: 2015
The endpoint toward which reconfigurable systems should develop is programmable matter, that is, complex systems whose physical properties and structure can be controlled in a systematic way. This can be accomplished by recognizing that computational processes can be used to assemble and reconfigure complex, hierarchically structured systems. Programmable matter may be programmatically controlled externally or internally, which includes self-assembly. The best approach to the self-assembly of complex, hierarchical systems, such as future robots with capabilities comparable to those of animals, is by artificial morphogenesis, which adapts embryological morphogenesis to artificial systems. We review the requirements of self-assembling morphogenetic components. © 2015 IEEE.
Nolt J.,University of Tennessee at Knoxville
Climatic Change | Year: 2015
Climate change will cause large numbers of casualties, perhaps extending over thousands of years. Casualties have a clear moral significance that economic and other technical measures of harm tend to mask. They are, moreover, universally understood, whereas other measures of harm are not. Therefore, the harms of climate change should regularly be expressed in terms of casualties by such agencies such as IPCC’s Working Group III, in addition to whatever other measures are used. Casualty estimates should, furthermore, be used to derive estimates of casualties per emission source up to a given date. Such estimates would have wide margins of error, but they would add substantially to humanity’s grasp of the moral costs of particular greenhouse gas emissions. © 2014, Springer Science+Business Media Dordrecht.
Dagotto E.,University of Tennessee at Knoxville |
Dagotto E.,Oak Ridge National Laboratory
Reviews of Modern Physics | Year: 2013
The iron-based superconductors that contain FeAs layers as the fundamental building block in the crystal structures have been rationalized in the past using ideas based on the Fermi surface nesting of hole and electron pockets when in the presence of weak Hubbard U interactions. This approach seemed appropriate considering the small values of the magnetic moments in the parent compounds and the clear evidence based on photoemission experiments of the required electron and hole pockets. However, recent results in the context of alkali metal iron selenides, with generic chemical composition A xFe2-ySe2 (A=alkali metal element), have challenged those previous ideas since at particular compositions y the low-temperature ground states are insulating and display antiferromagnetic order with large iron magnetic moments. Moreover, angle-resolved photoemission studies have revealed the absence of hole pockets at the Fermi level in these materials. The present status of this exciting area of research, with the potential to alter conceptually our understanding of the iron-based superconductors, is here reviewed, covering both experimental and theoretical investigations. Other recent related developments are also briefly reviewed, such as the study of selenide two-leg ladders and the discovery of superconductivity in a single layer of FeSe. The conceptual issues considered established for the alkali metal iron selenides, as well as several issues that still require further work, are discussed. © 2013 American Physical Society.
Sharma M.,University of Tennessee at Knoxville
Applied Geography | Year: 2013
This study contributes to the literature on applied urban geography by examining spatial patterns and processes of changing racial/ethnic diversity within the intra-urban context of Knoxville metropolitan statistical area. Knoxville embraces a diverse economic set up with opportunities in high-tech research and development, manufacturing, tertiary/service-sectors, construction, as well as entertainment industry. This serves well for its continued population growth, including minorities during 1990-2009. This paper explores how the neighborhood-level socioeconomic, demographic, and built-environment characteristics relate to tract-level racial/ethnic diversity, measured by multi-group diversity score and its components. Tools such as isarithmic surface density maps, correlations, principal components and regression analyses are used to examine processes of change. Results indicate that diversity in 1990 associates with negative change whereas diversity in 2000 associates with positive change. Though overall diversity sprawls and increases during 1990-2009, diversity among non-White declines during 2000-2009 and shows spatial confinement. Regressions suggest complicated mosaics of changing neighborhoods, providing evidence of invasion-succession, filtering and resurgence of ethnic-enclaves in specific neighborhoods. Concerning the six counties of the MSA, Knox is the most diverse whereas Union the least, though the share of Hispanics tops in Loudon and Asians in Knox. In terms of strategic planning, findings from this research can be used in creating equitable and sustainable urban communities that can improve the overall well-being of people by reducing racial/ethnic and socio-economic disparities that might occur as undesirable consequences of fast increasing diversity. © 2013 The Author.
Khairoutdinov M.F.,State University of New York at Stony Brook |
Yang C.-E.,University of Tennessee at Knoxville
Atmospheric Chemistry and Physics | Year: 2013
The study attempts to evaluate the aerosol indirect effects over tropical oceans in regions of deep convection applying a three-dimensional cloud-resolving model run over a doubly-periodic domain. The Tropics are modelled using a radiative-convective equilibrium idealisation when the radiation, turbulence, cloud microphysics and surface fluxes are explicitly represented while the effects of large-scale circulation are ignored. The aerosol effects are modelled by varying the number concentration of cloud condensation nuclei (CCN) at 1% supersaturation, which serves as a proxy for the aerosol amount in the environment, over a wide range, from pristine maritime (50 cm-3) to polluted (1000 cm-3) conditions. No direct effects of aerosol on radiation are included. Two sets of simulations have been run: fixed (noninteractive) sea surface temperature (SST) and interactive SST as predicted by a simple slab-ocean model responding to the surface radiative fluxes and surface enthalpy flux. Both sets of experiments agree on the tendency of increased aerosol concentrations to make the shortwave cloud forcing more negative and reduce the longwave cloud forcing in response to increasing CCN concentration. These, in turn, tend to cool the SST in interactive-SST case. It is interesting that the absolute change of the SST and most other bulk quantities depends only on relative change of CCN concentration; that is, same SST change can be the result of doubling CCN concentration regardless of clean or polluted conditions. It is found that the 10-fold increase of CCN concentration can cool the SST by as much as 1.5 K. This is quite comparable to 2.1-2.3K SST warming obtained in a simulation for clean maritime conditions, but doubled CO2 concentration. Assuming the aerosol concentration has increased from preindustrial time by 30 %, the radiative forcing due to indirect aerosol effects is estimated to be -0.3Wm-2. It is found that the indirect aerosol effect is dominated by the first (Twomey) effect. Qualitative differences between the interactive and fixed SST cases have been found in sensitivity of the hydrological cycle to the increase in CCN concentration; namely, the precipitation rate shows some tendency to increase in fixed SST case, but robust tendency to decrease in interactive SST case. © Author(s) 2013.
Gavrilets S.,University of Tennessee at Knoxville
Proceedings of the National Academy of Sciences of the United States of America | Year: 2012
A crucial step in recent theories of human origins is the emergence of strong pair-bonding between males and females accompanied by a dramatic reduction in the male-to-male conflict over mating and an increased investment in offspring. How such a transition from promiscuity to pair-bonding could be achieved is puzzling. Many species would, indeed, be much better off evolutionarily if the effort spent on male competition over mating was redirected to increasing female fertility or survivorship of offspring. Males, however, are locked in a "social dilemma," where shifting one's effort from "appropriation" to "production" would give an advantage to free-riding competitors and therefore, should not happen. Here, I first consider simple models for four prominent scenarios of the human transition to pair-bonding: communal care, mate guarding, food for mating, and mate provisioning. I show that the transition is not feasible under biologically relevant conditions in any of these models. Then, I show that the transition can happen if one accounts for male heterogeneity, assortative pair formation, and evolution of female choice and faithfulness. This process is started when low-ranked males begin using an alternative strategy of female provisioning. At the end, except for the top-ranked individuals, males invest exclusively in provisioning females who have evolved very high fidelity to their mates. My results point to the crucial importance of female choice and emphasize the need for incorporating between-individual variation in theoretical and empirical studies of social dilemmas and behaviors.
White J.B.,U.S. National Center for Atmospheric Research |
Dongarra J.J.,University of Tennessee at Knoxville
Journal of Computational Physics | Year: 2011
Current climate models have a limited ability to increase spatial resolution because numerical stability requires the time step to decrease. We describe a semi-Lagrangian method for tracer transport that is stable for arbitrary Courant numbers, and we test a parallel implementation discretized on the cubed sphere. The method includes a fixer that conserves mass and constrains tracers to a physical range of values. The method shows third-order convergence and maintains nonlinear tracer correlations to second order. It shows optimal accuracy at Courant numbers of 10-20, more than an order of magnitude higher than explicit methods. We present parallel performance in terms of strong scaling, weak scaling, and spatial scaling (where the time step stays constant while the resolution increases). For a 0.2° test with 100 tracers, the implementation scales efficiently to 10,000 MPI tasks. © 2011 Elsevier Inc.
Ballari S.A.,National University of Cordoba |
Ballari S.A.,University of British Columbia |
Barrios-Garcia M.N.,University of Tennessee at Knoxville
Mammal Review | Year: 2014
The wild boar Sus scrofa is an omnivore with one of the largest geographical ranges of all species. However, no synthesis exists on its diet, feeding behaviour and factors affecting food selection in its native and introduced ranges. A literature review and a test of effect size revealed significant differences in wild boar diet composition in native and introduced ranges. Wild boar diet is dominated by plant material (∼90%) in both ranges, but animal matter and fungi are consumed in greater proportions in the introduced range than in the native range. Food items frequently include agricultural crops (especially in the native range) and endangered animal species (especially in the introduced range). Energy requirements, food availability, and seasonal and geographical variations are major factors influencing food selection by wild boar. These factors may also interact with human activities (e.g. agricultural crops, supplementary feeding) to influence diet composition further. Dietary studies should be more rigorous and consistent across ranges to allow better comparisons. A detailed study of diet in combination with seasonal patterns of habitat use could provide key information such as target species and susceptible habitats on which management efforts should focus. © 2013 The Mammal Society and John Wiley & Sons Ltd.
Hinde R.J.,University of Tennessee at Knoxville
Computer Physics Communications | Year: 2011
We describe QSATS, a parallel code for performing variational path integral simulations of the quantum mechanical ground state of monatomic solids. QSATS is designed to treat Boltzmann quantum solids, in which individual atoms are permanently associated with distinguishable crystal lattice sites and undergo large-amplitude zero-point motions around these sites. We demonstrate the capabilities of QSATS by using it to compute the total energy and potential energy of hexagonal close packed solid 4He at the density ρ=4.61421×10-3a0-3. Program summary: Program title: QSATS Catalogue identifier: AEJE-v1-0 Program summary URL: http://cpc.cs.qub.ac.uk/ summaries/AEJE-v1-0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 7329 No. of bytes in distributed program, including test data, etc.: 61 685 Distribution format: tar.gz Programming language: Fortran 77. Computer: QSATS should execute on any distributed parallel computing system that has the Message Passing Interface (MPI)  libraries installed. Operating system: Unix or Linux. Has the code been vectorized or parallelized?: Yes, parallelized using MPI . RAM: The memory requirements of QSATS depend on both the number of atoms in the crystal and the number of replicas in the variational path integral chain. For parameter sets A and C (described in the long write-up), approximately 4.5 Mbytes and 12 Mbytes, respectively, are required for data storage by QSATS (exclusive of the executable code). Classification: 7.7, 16.13. External routines: Message Passing Interface (MPI)  Nature of problem: QSATS simulates the quantum mechanical ground state for a monatomic crystal characterized by large-amplitude zero-point motions of individual (distinguishable) atoms around their nominal lattice sites. Solution method: QSATS employs variational path integral quantum Monte Carlo techniques to project the system's ground state wave function out of a suitably-chosen trial wave function. Restrictions: QSATS neglects quantum statistical effects associated with the exchange of identical particles. As distributed, QSATS assumes that the potential energy function for the crystal is a pairwise additive sum of atom-atom interactions. Additional comments: An auxiliary program, ELOC, is provided that uses the output generated by QSATS to compute both the crystal's ground state energy and the expectation value of the crystal's potential energy. End users can modify ELOC as needed to compute the expectation value of other coordinate-space observables. Running time: QSATS requires roughly 3 hours to run a simulation using parameter set A on a cluster of 12 Xeon processors with clock speed 2.8 GHz. Roughly 15 hours are needed to run a simulation using parameter set C on the same cluster. References: For information about MPI, visit http://www.mcs.anl.gov/mpi/. © 2011 Elsevier B.V. All rights reserved.
Fleming J.T.,University of Tennessee at Knoxville
Advances in Biochemical Engineering/Biotechnology | Year: 2010
The direct interfacing of living cells with inorganic electronic materials, components or systems has led to the development of two broad categories of devices that can (1) transduce biochemical signals generated by biological components into electrical signals and (2) transduce electronically generated signals into biochemical signals. The first category of devices permits the monitoring of living cells, the second, enables control of cellular processes. This review will survey this exciting area with emphasis on the fundamental issues and obstacles faced by researchers. Devices and applications that use both prokaryotic (microbial) and eukaryotic (mammalian) cells will be covered. Individual devices described include microbial biofuel cells that produce electricity, bioelectrical reactors that enable electronic control of cellular metabolism, living cell biosensors for the detection of chemicals and devices that permit monitoring and control of mammalian physiology. © Springer-Verlag Berlin Heidelberg 2009.
Ripp S.,University of Tennessee at Knoxville
Advances in Biochemical Engineering/Biotechnology | Year: 2010
Considered the most abundant organism on Earth, at a population approaching 1031, bacteriophage, or phage for short, mediate interactions with myriad bacterial hosts that has for decades been exploited in phage typing schemes for signature identification of clinical, food-borne, and water-borne pathogens. With over 5,000 phage being morphologically characterized and grouped as to susceptible host, there exists an enormous cache of bacterial-specific sensors that has more recently been incorporated into novel bio-recognition assays with heightened sensitivity, specificity, and speed. These assays take many forms, ranging from straightforward visualization of labeled phage as they attach to their specific bacterial hosts to reporter phage that genetically deposit trackable signals within their bacterial hosts to the detection of progeny phage or other uniquely identifiable elements released from infected host cells. A comprehensive review of these and other phage-based detection assays, as directed towards the detection and monitoring of bacterial pathogens, will be provided in this chapter. © Springer-Verlag Berlin Heidelberg 2009.
Tse C.K.,Hong Kong Polytechnic University |
Li M.,University of Tennessee at Knoxville
International Journal of Bifurcation and Chaos | Year: 2011
Bifurcation analysis has been applied to many power electronics circuits. Literature abounds with results regarding the various ways in which such circuits lose stability under variation of some selected parameters, e.g. via period-doubling bifurcation, Hopf bifurcation, border collision, etc. The current status of research in the identification of bifurcation behavior in power electronics has reached a stage where the salient types of bifurcation behavior, their underlying causes and the theoretical parameters affecting them have been well understood. Currently, the emphasis of research in this field has gradually shifted toward applications that are of direct relevance to practical design of power electronics. One direction is to apply some of the available research results in bifurcation behavior to the design of practical power electronics circuits. The main difficulty is that the abstract mathematical presentations of the available results are not directly applicable to practical design problems. In this paper we will discuss how research efforts may be directed to bridge this gap. © 2011 World Scientific Publishing Company.
Woo W.,Korea Atomic Energy Research Institute |
Choo H.,University of Tennessee at Knoxville
Science and Technology of Welding and Joining | Year: 2011
The influence of friction stir welding (FSW) on changes in microstructures has been studied extensively. In particular, the microstructural softening, which is manifested as a significant reduction in the hardness, tensile strength and residual stress, is one of the most significant issues. Here, we provide a brief review of the dominant softening mechanisms in FSW aluminium and magnesium alloys available in the literature. In particular, a direct comparison between a heat treatable Al 6061-T6 alloy and an AZ31B Mg alloy is presented to highlight key differences in the underlying mechanisms responsible for the apparently similar softening behaviour. The present study shows that the softening occurs in the wide region of the FSW Al 6061-T6 alloy due to the dissolution of the strengthening precipitates, while it happens mostly within the stir zone due to the localised texture variations in the FSW Mg AZ31B alloy. These softening behaviours are clearly represented in the residual stress profiles. © 2011 Institute of Materials, Minerals and Mining.
Petridis L.,Oak Ridge National Laboratory |
Schulz R.,Oak Ridge National Laboratory |
Schulz R.,University of Tennessee at Knoxville |
Smith J.C.,Oak Ridge National Laboratory
Journal of the American Chemical Society | Year: 2011
Lignins are hydrophobic, branched polymers that regulate water conduction and provide protection against chemical and biological degradation in plant cell walls. Lignins also form a residual barrier to effective hydrolysis of plant biomass pretreated at elevated temperatures in cellulosic ethanol production. Here, the temperature-dependent structure and dynamics of individual softwood lignin polymers in aqueous solution are examined using extensive (17 μs) molecular dynamics simulations. With decreasing temperature the lignins are found to transition from mobile, extended to glassy, compact states. The polymers are composed of blobs, inside which the radius of gyration of a polymer segment is a power-law function of the number of monomers comprising it. In the low temperature states the blobs are interpermeable, the polymer does not conform to Zimm/Stockmayer theory, and branching does not lead to reduction of the polymer size, the radius of gyration being instead determined by shape anisotropy. At high temperatures the blobs become spatially separated leading to a fractal crumpled globule form. The low-temperature collapse is thermodynamically driven by the increase of the translational entropy and density fluctuations of water molecules removed from the hydration shell, thus distinguishing lignin collapse from enthalpically driven coil-globule polymer transitions and providing a thermodynamic role of hydration water density fluctuations in driving hydrophobic polymer collapse. Although hydrophobic, lignin is wetted, leading to locally enhanced chain dynamics of solvent-exposed monomers. The detailed characterization obtained here provides insight at atomic detail into processes relevant to biomass pretreatment for cellulosic ethanol production and general polymer coil-globule transition phenomena. © 2011 American Chemical Society.
Singh V.,University of Tennessee at Knoxville
GROUP'12 - Proceedings of the ACM 2012 International Conference on Support Group Work | Year: 2012
In this paper we present results of an NSF funded project on exploring and understanding cyber learning that happens in online open source software (OSS) communities for technical support. We look across multiple OSS support communities (Firefox, Java, and Koha) to understand the behavior of newcomers in these communities, the role that the community response plays in their continued participation and newcomer best practices. We found that newcomers are not a homogenous group and majority of them display "model" behavior. We also found out that community response is critical for continued participation of newcomers. In our dataset, almost all non returning newcomers can be attributed to receiving no reply or a condescending reply from the community. We found that one third of newcomers' transition into a role of help givers in the community and demonstrate evidence of learning. We also highlight best practices for newcomers to be successful in these online communities. Copyright © 2012 by the Association for Computing Machinery, Inc. (ACM).
Kovac J.,University of Tennessee at Knoxville
Science and Engineering Ethics | Year: 2013
This article considers the ethical aspects of the question: should a scientist engage in war-related research, particularly use-inspired or applied research directed at the development of the means for the better waging of war? Because scientists are simultaneously professionals, citizens of a particular country, and human beings, they are subject to conflicting moral and practical demands. There are three major philosophical views concerning the morality of war that are relevant to this discussion: realism, just war theory and pacifism. In addition, the requirements of professional codes of ethics and common morality contribute to an ethical analysis of the involvement of scientists and engineers in war-related research and technology. Because modern total warfare, which is facilitated by the work of scientists and engineers, results in the inevitable killing of innocents, it follows that most, if not all, war-related research should be considered at least as morally suspect and probably as morally prohibited. © 2012 Springer Science+Business Media B.V.
Nolt J.,University of Tennessee at Knoxville
Wiley Interdisciplinary Reviews: Climate Change | Year: 2011
Anthropogenic climate change may contribute to a mass extinction that would leave biodiversity depleted for millions of years-quite possibly longer than the duration of the human species. Such effects are arguably of ethical concern, but because established ethical theories are anthropocentric-that is, focused on the relatively short-term interests of human beings-they offer no guidance on such vast temporal scales. There has been significant work in recent decades in both longer-term intergenerational anthropocentric climate ethics and near-term nonanthropocentric ethics, but so far these novel developments have not been integrated into a long-term nonanthropocentric climate ethic. This article considers prospects for the development and justification of such an ethic, difficulties it would face, and its relevance to climate policy. © 2011 John Wiley & Sons, Ltd.
Vivekananthan C.,Queensland University of Technology |
Mishra Y.,Queensland University of Technology |
Ledwich G.,Queensland University of Technology |
Li F.,University of Tennessee at Knoxville
IEEE Transactions on Smart Grid | Year: 2014
This paper proposes a reward based demand response algorithm for residential customers to shave network peaks. Customer survey information is used to calculate various criteria indices reflecting their priority and flexibility. Criteria indices and sensitivity based house ranking is used for appropriate load selection in the feeder for demand response. Customer Rewards (CR) are paid based on load shift and voltage improvement due to load adjustment. The proposed algorithm can be deployed in residential distribution networks using a two-level hierarchical control scheme. Realistic residential load model consisting of non-controllable and controllable appliances is considered in this study. The effectiveness of the proposed demand response scheme on the annual load growth of the feeder is also investigated. Simulation results show that reduced peak demand, improved network voltage performance, and customer satisfaction can be achieved. © 2014 IEEE.
Ebadian M.A.,Florida International University |
Lin C.X.,University of Tennessee at Knoxville
Journal of Heat Transfer | Year: 2011
In recent years, high-heat-flux cooling techniques have received great attention from researchers around the world due to its importance in thermal management of both commercial and defense high-power electronic devices. Although impressive progress has been made during the last few decades, high-heat-flux removal still largely remains as a challenging subject that needs further exploration and study. In this paper, we have reviewed recent developments in several high-heat-flux heat removal techniques, including microchannels, jet impingements, sprays, wettability effects, and piezoelectrically driven droplets. High-heat-flux removal can be achieved effectively by either single-phase flow or two-phase flow boiling heat transfer. Better understandings of the underlying heat transfer mechanisms for performance improvement are discussed. © 2011 American Society of Mechanical Engineers.
Hewezi T.,University of Tennessee at Knoxville
Plant Physiology | Year: 2015
Plant-parasitic cyst and root-knot nematodes synthesize and secrete a suite of effector proteins into infected host cells and tissues. These effectors are the major virulence determinants mediating the transformation of normal root cells into specialized feeding structures. Compelling evidence indicates that these effectors directly hijack or manipulate refined host physiological processes to promote the successful parasitism of host plants. Here, we provide an update on recent progress in elucidating the molecular functions of nematode effectors. In particular, we emphasize how nematode effectors modify plant cell wall structure, mimic the activity of host proteins, alter auxin signaling, and subvert defense signaling and immune responses. In addition, we discuss the emerging evidence suggesting that nematode effectors target and recruit various components of host posttranslational machinery in order to perturb the host signaling networks required for immunity and to regulate their own activity and subcellular localization. © 2015 American Society of Plant Biologists. All rights reserved.
Scheitlin K.,University of Tennessee at Knoxville
Earth Interactions | Year: 2013
This study analyzes the influence of the Atlantic Ocean and Chesapeake Bay on the diurnal temperature range (DTR) reported by nearby weather stations. Coastal locations reported the smallest DTRs and DTR fluctuations, and DTR increased with distance from the ocean. Month of the year and airmass type also proved to be significant predictors of DTR. All locations showed a bimodal annual DTR pattern with peaks during the transitional seasons and experienced the greatest DTR during dry and/or warm air masses. Proximity to the ocean had the largest (smallest) influence on DTR during dry (moist) air masses with extreme (moderate) temperatures. Seasonally, the proximity to the ocean had the strongest impact on DTR during early-middle spring. A multiple regression model using distance from water, month, and airmass type explains over 30% of DTR variability in the area (p 0.01). Airmass type has the largest influence on DTR, and changes in both air mass and month impacted the DTR of continental locations more than coastal locations. Land use, cloud cover, and wind speed/direction are additional variables that could account for differences not explained by the model. ©2013.
Sarles S.A.,University of Tennessee at Knoxville
Smart Materials and Structures | Year: 2013
The droplet interface bilayer (DIB) is a simple technique for constructing a stable lipid bilayer at the interface of two lipid-encased water droplets submerged in oil. Networks of DIBs formed by connecting more than two droplets constitute a new form of modular biomolecular smart material, where the transduction properties of a single lipid bilayer can affect the actions performed at other interface bilayers in the network via diffusion through the aqueous environments of shared droplet connections. The passive electrical properties of a lipid bilayer and the arrangement of droplets that determine the paths for transport in the network require specific electrical control to stimulate and interrogate each bilayer. Here, we explore the use of virtual ground for electrodes inserted into specific droplets in the network and employ a multichannel patch clamp amplifier to characterize bilayer formation and ion-channel activity in a serial DIB array. Analysis of serial connections of DIBs is discussed to understand how assigning electrode connections to the measurement device can be used to measure activity across all lipid membranes within a network. Serial arrays of DIBs are assembled using the regulated attachment method within a multi-compartment flexible substrate, and wire-type electrodes inserted into each droplet compartment of the substrate enable the application of voltage and measurement of current in each droplet in the array. © 2013 IOP Publishing Ltd.
Looney B.P.,University of Tennessee at Knoxville
Mycotaxon | Year: 2014
Twenty-five historical type collections of North American Russula species described by W.A. Murrill were sequenced and analyzed for placement in a phylogenetic and taxonomic framework. Molecular data was successfully obtained from sixteen type specimens (66%), of which eight species have never before been placed in an infrageneric classification system. Classifications and synonymization of taxa proposed by Rolf Singer and others are evaluated. Russula albimarginata and R. emeticiformis are suggested as synonyms of R. vinacea, a widespread and common species in the eastern United States. Four taxa of unknown classification (R. albimarginata, R. pinophila, R. subcremeiceps, R. subrubescens) have been classified to subsection level, and an alternative classification is proposed for R. westii. A morphological comparison of a collection from British Columbia (Canada) with 99% sequence similarity to R. levyana in the Internal Transcribed Spacer 1 (ITS1) region indicates that this region alone may be inadequate for species barcoding in Russula. © 2014. Mycotaxon, Ltd.
Binder B.M.,University of Tennessee at Knoxville |
Rodriguez F.I.,University of Wisconsin - Madison |
Bleecker A.B.,University of Wisconsin - Madison
Journal of Biological Chemistry | Year: 2010
Plants utilize ethylene as a hormone to regulate multiple developmental processes and to coordinate responses to biotic and abiotic stress. In Arabidopsis thaliana, a small family of five receptor proteins typified by ETR1 mediates ethylene perception. Our previous work suggested that copper ions likely play a role in ethylene binding. An independent study indicated that the ran1 mutants, which display ethylene-like responses to the ethylene antagonist trans-cyclooctene, have mutations in the RAN1 copper-transporting P-type ATPase, once again linking copper ions to the ethylene-response pathway. The results presented herein indicate that genetically engineered Saccharomyces cerevisiae expressing ETR1 but lacking the RAN1 homolog Ccc2p (Δccc2) lacks ethylene-binding activity. Ethylene-binding activity was restored when copper ions were added to the Δccc2 mutants, showing that it is the delivery of copper that is important. Additionally, transformation of the Δccc2 mutant yeast with RAN1 rescued ethylene-binding activity. Analysis of plants carrying loss-of-function mutations in ran1 showed that they lacked ethylene-binding activity, whereas seedlings carrying weak alleles of ran1 had normal ethylene-binding activity but were hypersensitive to copper-chelating agents. Altogether, the results show an essential role for RAN1 in the biogenesis of the ethylene receptors and copper homeostasis in Arabidopsis seedlings. Furthermore, the results indicate cross-talk between the ethylene-response pathway and copper homeostasis in Arabidopsis seedling development. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Simberloff D.,University of Tennessee at Knoxville
Environmental Ethics | Year: 2012
Non-native species are implicated in many ecological and economic problems, and the field of invasion biology has burgeoned in response to this fact. However, classification, terminology, and management of non-native species generate controversies and even calls for abolition of the field. The fact that the basis for disputes is differing worldviews rather than simply interpretation of biological observations suggests that resolving arguments about non-native species will be difficult, independently of questions about the operational tractability of proposed courses of action.
Lee S.,University of Tennessee at Knoxville |
Matejkowski J.,Section on Law and Ethics Treatment Research Institute
Administration and Policy in Mental Health and Mental Health Services Research | Year: 2012
Since the Welfare Reform Act of 1996, citizenship status has become an important consideration in mental health service utilization due to the restrictions on federal healthcare benefits for noncitizens living in the U.S. Using a nationally representative sample of Latinos and Asians, we examined the extent to which U.S. citizenship status was related to rates of mental health service utilization. We also identified several predictors of mental health service utilization among noncitizens. Noncitizens were about 40% less likely than U.S.-born citizens to use any mental health services. Findings are discussed in the context of healthcare policy and recent healthcare reform. © 2011 Springer Science+Business Media, LLC.
King R.,University of Tennessee at Knoxville
Archives of Pathology and Laboratory Medicine | Year: 2011
Context.-Atypical lentiginous melanocytic lesions, particularly in older individuals, continue to pose a diagnostic challenge. Such lesions often show features intermediate between lentiginous nevus and melanoma in situ. We have recently defined within this group of lesions a histologic pattern of lentiginous melanoma, a slowly progressing variant of melanoma typically found on the trunk and proximal extremities of middle-aged and older individuals. Objective.-To review the clinical and histologic features of lentiginous melanoma and its histologic differential diagnosis. Data Sources.-Review of pertinent published literature and work in our laboratory. Conclusions.- Lentiginous melanoma defines a subset of slowly progressing melanoma occurring in middle-aged and older patients. It is histologically characterized by a broad atypical lentiginous growth pattern of moderately atypical melanocytes showing focal nesting and pagetoid spread without significant dermal fibroplasia or alteration of the rete ridges. Lentiginous melanoma shows significant overlap in clinical and histologic features with atypical lentiginous nevus (of the elderly). Relationship between these entities requires further investigations. Given the risk of progression to invasive melanoma, all lesions showing features of lentiginous melanoma should be treated with adequately wide excision.
Sharma M.,University of Tennessee at Knoxville
Applied Geography | Year: 2012
Racial/ethnic diversity in the United States has increased significantly in recent decades, with minority groups now accounting for almost one-third of the total population. At the same time, growing diversity has spread into rural and non-metropolitan areas. Research suggests that changing diversity in the 'New South' has seen growth of non-Black communities. The question, however, is the degree to which increasing diversity equates with increasing intermixing or, alternatively, whether racial/ethnic clusters retain their prominence. This paper examines the geographic manifestations of growing racial/ethnic diversity within intra-urban context, using census-tracts as scale of analysis in the metropolitan statistical area (MSA) of Knoxville in Tennessee. The statistics used for analyzing intra-urban variations include Diversity Score, Theil Entropy Index, and Location Quotient. Tract and Block-group data for White, Black, American Indian, Asian, All Others and Hispanic are used for computing these indices. This paper concludes that diversity has increased during 1990-2000, and has dispersed into suburban counties. However, segregation and clustering for certain minority groups has also increased, in particular African-Americans still remain the most segregated and most clustered community confined to specific geographic locations. This research holds significance as local economic development patterns are very much guided by the geographic variability of human and social capital. Applied research can suggest avenues for growth and can help rebuild local communities. This paper will also contribute to literature focusing on methodological challenges in measuring diversity and its geographic manifestations. © 2011 Elsevier Ltd.
Charrier R.,University of Missouri |
Li Y.,University of Tennessee at Knoxville
Applied Geography | Year: 2012
Digital elevation models (DEMs) have been widely used in automated floodplain modeling to determine floodplain boundaries. However, the effects of DEM resolution and data source on floodplain delineation are not well quantified. This paper presents a case study to assess these effects from the Camp Creek Watershed, Missouri, using two sets of DEMs. One is the Light Detection and Ranging (LiDAR) DEMs resampled from 1-m to 3, 5, 10, 15, and 30-m resolutions. The other is 5, 10, and 30-m DEMs obtained from the U.S. Geological Survey (USGS). Floodplain boundaries are delineated using a combination of hydrological, hydraulic and floodplain delineation models under the Federal Emergency Management Agency's (FEMA) guideline. Model outputs including stream network, watershed and floodplain boundaries are compared to 1-m LiDAR DEM outputs (as the reference) to assess the uncertainty. Results indicate that re-sampled 3 or 5-m LiDAR DEMs produce similar streams and floodplain boundaries within 10% difference of the reference. In contrast, coarser LiDAR DEMs (such as the 10-m resolution) are more appropriate for watershed boundary delineation because higher DEM resolutions are likely more sensitive to minor topographic changes and may introduce erroneous boundaries. For different data sources, uncertainties introduced by USGS DEMs are much higher than LiDAR DEMs with a distinct relationship between uncertainties and DEM resolutions. Uncertainties of LiDAR DEMs consistently increase with decreasing resolutions, whereas similar levels of uncertainty are observed for different USGS DEM resolutions. This difference is probably due to the inherited difference in their original data source resolutions to make these two types of DEMs. © 2011 Elsevier Ltd.
Shpak E.D.,University of Tennessee at Knoxville
Journal of Integrative Plant Biology | Year: 2013
Multiple receptor-like kinases (RLKs) enable intercellular communication that coordinates growth and development of plant tissues. ERECTA family receptors (ERfs) are an ancient family of leucine-rich repeat RLKs that in Arabidopsis consists of three genes: ERECTA, ERL1, and ERL2. ERfs sense secreted cysteine-rich peptides from the EPF/EPFL family and transmit the signal through a MAP kinase cascade. This review discusses the functions of ERfs in stomata development, in regulation of longitudinal growth of aboveground organs, during reproductive development, and in the shoot apical meristem. In addition the role of ERECTA in plant responses to biotic and abiotic factors is examined. copy; 2013 Institute of Botany, Chinese Academy of Sciences.
Chi M.,Center for Nanophase Material science |
Veith G.M.,Oak Ridge National Laboratory |
Gallego N.C.,Oak Ridge National Laboratory |
Dai S.,University of Tennessee at Knoxville
Journal of the American Chemical Society | Year: 2014
Here we describe a lab-in-a-shell strategy for the preparation of multifunctional core-shell nanospheres consisting of a core of metal clusters and an outer microporous silica shell. Various metal clusters (e.g., Pd and Pt) were encapsulated and confined in the void space mediated by the entrapped polymer dots inside hollow silica nanospheres acting first as complexing agent for metal ions and additionally as encapsulator for clusters, limiting growth and suppressing the sintering. The Pd clusters encapsulated in hybrid core-shell structures exhibit exceptional size-selective catalysis in allylic oxidations of substrates with the same reactive site but different molecular size (cyclohexene ∼0.5 nm, cholesteryl acetate ∼1.91 nm). The solvent-free aerobic oxidation of diverse hydrocarbons and alcohols was further carried out to illustrate the benefits of such an architecture in catalysis. High activity, outstanding thermal stability and good recyclability were observed over the core-shell nanocatalyst. © 2014 American Chemical Society.
Lawson C.M.,University of Tennessee at Knoxville
JPEN. Journal of parenteral and enteral nutrition | Year: 2013
Defining malnutrition and nutrition risk has been a topic of many papers and discussions throughout the modern literature. Multiple definitions have been proposed, ranging from simple body weight measurements to a more all-encompassing concept looking at disease-specific inflammatory states. Biochemical markers, elements of a history examination, physical examination findings, calculations, and technical tests have all been proposed to help further characterize and delineate those who might be at risk for malnutrition, translating to an increased risk of adverse outcomes after major surgery. The purpose of this paper is to summarize some of the most utilized and most reliable ways to determine nutrition status within the scope of the North American Surgical Nutrition Summit (2012) and discuss how to incorporate these methods into the way that patients are screened preoperatively for elective surgery.
Yen S.T.,University of Tennessee at Knoxville
Food Policy | Year: 2010
Nutritional effects of participation by young children in the Supplemental Nutrition Assistance Program (SNAP) and the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) in the United States are investigated. A system of nutrient equations with dual endogenous programs is estimated by the maximum-likelihood procedure. WIC is found to increase the intakes of three of the four important nutrients for WIC children, including iron, potassium, and fiber. SNAP only has a small and negative effect on fiber intake. The additional benefit of SNAP participation is non-existent given participation in WIC. © 2010 Elsevier Ltd.
Hatcher Jr. R.D.,University of Tennessee at Knoxville
Memoir of the Geological Society of America | Year: 2010
The Appalachians are a Paleozoic orogen that formed in a complete Wilson cycle along the eastern Laurentian margin following the breakup of super continent Rodinia and the coalescence of all of the continents to form super continent Pangea. The Appalachian Wilson cycle began by formation of a Neoproterozoic to early Paleozoic rifted margin and plat form succession on the south eastern margin of Laurentia. Three orogenies ultimately producedthe mountain chain: the Ordovician Taconic orogeny , which involved arc accretion; the Acadian-Neoacadian orogeny, which involved north-to-south, transpressional, zippered, Late Devonian-early Mississippian collision of the Carolina superterrane in the southern-central Appalachians and the Avalon-Gander superterrane in the New England Appalachians, and Silurian collision in the Maritime Appalachians and Newfoundland; and the Alleghanian orogeny, which involved late Mississippian to Permian collision of all previously formed Appalachian components with Gondwana to form super continent Pangea. The Alleghanian alsoinvolved zippered, north-to-south, transpressional, then head-on collision. All orogenieswere diachronous. Similar time-correlative orogenies affected western and central Europe (Variscan events), eastern Europe and western Siberia (Uralian events), and southern Britain and Ireland; only the Caledonide (Grampian-Finnmarkian ; Caledonian-Scandian) events affected the rest of Britain and the Scandinavian Caledonides. These different events, coupled with the irregular rifted margin of Laurentia, produced an orogen that contains numerous contrasts and nonthroughgoing elements, but it also contains elements, such as the platform margin and peri-Gondwanan elements, that are recognizable throughout the orogen.© 2010 The Geological Society of America.
Sumrall C.D.,University of Tennessee at Knoxville
Journal of Paleontology | Year: 2010
A large, edrioasteroid-bearing hardground surface from the base of the Bellevue Member of the Grant Lake Formation near Maysville, Mason County, Kentucky is described. Four species are represented including Streptaster vorticellatus (Hall), Carneyella ulrichi Bassler and Shideler, Carneyella pilea (Hall), and Curvitriordo stecki n. sp. Specimens of S. vorticellatus and C. pilea add little to the known morphologies of these species. However, prior to this study C. ulrichi was known from the unique holotype, and Curvitriordo stecki n. sp. adds greatly to out understanding of Curvitriordo which was previously known from two species comprising three poorly preserved specimens. Curvitriordo stecki shows a bimodal size frequency distribution suggesting seasonal breeding whereas Carneyella ulrichi shows a left skewed size frequency suggesting low juvenile mortality. Streptaster vorticellatus shows a tight unimodal size frequency distribution suggestive of a single spat fall accumulation. © 2010 The Paleontological Society.
Panthee D.R.,North Carolina State University |
Chen F.,University of Tennessee at Knoxville
Current Genomics | Year: 2010
Tomato (Solanum lycopersicum) is an important vegetable crop worldwide. Often times, its production is hindered by fungal diseases. Important fungal diseases limiting tomato production are late blight, caused by Phytophthora infestans, early blight, caused by Alternaria solanii, and septoria leaf spot, caused by Septoria lycopersici, fusarium wilt caused by Fusarium oxysporium fsp. oxysporium, and verticilium wilt caused by Verticilium dahlea. The Phytophthora infestans is the same fungus that caused the devastating loss of potato in Europe in 1845. A similar magnitude of crop loss in tomato has not occurred but Phytophthora infestans has caused the complete loss of tomato crops around the world on a small scale. Several attempts have been made through conventional breeding and the molecular biological approaches to understand the biology of host-pathogen interaction so that the disease can be managed and crop loss prevented. In this review, we present a comprehensive analysis of information produced by molecular genetic and genomic experiments on host-pathogen interactions of late blight, early blight, septoria leaf spot, verticilim wilt and fusarium wilt in tomato. Furthermore, approaches adopted to manage these diseases in tomato including genetic transformation are presented. Attempts made to link molecular markers with putative genes and their use in crop improvement are discussed. ©2010 Bentham Science Publishers Ltd.
Hoang K.V.,University of Tennessee at Knoxville
Frontiers in cellular and infection microbiology | Year: 2012
Antimicrobial peptides (AMPs) are critical components of host defense limiting bacterial infections at the gastrointestinal mucosal surface. Bacterial pathogens have co-evolved with host innate immunity and developed means to counteract the effect of endogenous AMPs. However, molecular mechanisms of AMP resistance in Campylobacter, an important human food-borne pathogen with poultry as a major reservoir, are still largely unknown. In this study, random transposon mutagenesis and targeted site-directed mutagenesis approaches were used to identify genetic loci contributing Campylobacter resistance to fowlicidin-1, a chicken AMP belonging to cathelicidin family. An efficient transposon mutagenesis approach (EZ::TN™
Nunez M.A.,University of Tennessee at Knoxville |
Nunez M.A.,University of Central Florida |
Medley K.A.,University of Central Florida
Diversity and Distributions | Year: 2011
Aim Explaining why some invasions fail while others succeed is a prevailing question in invasion biology. Different factors have been proposed to explain the success or failure of exotics. Evidence suggests that climate similarities may be crucial. We tested this using 12 species of the genus Pinus that have been widely planted and shown to be highly invasive. Pinus is among the best-studied group of exotic species and one that has been widely introduced world-wide, so we were able to obtain data on invasive and non-invasive introductions (i.e. unsuccessful invasions; areas where after many decades of self-sowing seeds there is no invasion). Location World-wide. Methods We developed species distribution models for native ranges using a maximum entropy algorithm and projected them across the globe. We tested whether climate-based models were able to predict both invasive and non-invasive introductions. Results Appropriate climatic conditions seem to be required for these long-lived species to invade because climates accurately predicted invasions. However, climate matching is necessary, but not sufficient to predict the fate of an introduction because most non-invasive introductions were predicted to have triggered an invasion. Main conclusions Other factors, possibly including biotic components, may be the key to explaining why some introductions do not become invasions, because many areas where Pinus is not invading were predicted to be suitable for invasion based solely on climate. © 2011 Blackwell Publishing Ltd.
Williams J.H.,University of Tennessee at Knoxville
AoB PLANTS | Year: 2012
Background and aims: The pollination to fertilization process (progamic phase) is thought to have become greatly abbreviated with the origin of flowering plants. In order to understand what developmental mechanisms enabled the speeding of fertilization, comparative data are needed from across the group, especially from early-divergent lineages. I studied the pollen germination process of Austrobaileya scandens, a perennial vine endemic to the Wet Tropics area of northeastern Queensland, Australia, and a member of the ancient angiosperm lineage, Austrobaileyales. Methodology: I used in vivo and in vitro hand pollinations and timed collections to study development from late pollen maturation to just after germination. Then I compared the contribution of pollen germination timing to progamic phase duration in 131 angiosperm species (65 families). Principal findings: Mature pollen of Austrobaileya was bicellular, starchless and moderately dehydrated-water content was 31.5 % by weight and volume increased by 57.9 % upon hydration. A callose layer in the inner intine appeared only after pollination. In vivo pollen germination followed a logarithmic curve, rising from 28 % at 1 hour after pollination (hap) to 97 % at 12 hap (R2 = 0.98). Sufficient pollen germination to fertilize all ovules was predicted to have occurred within 62 min. Across angiosperms, pollen germination ranged from 1 min to >60 h long and required 8.3±9.8 % of the total duration of the progamic phase. Significance: Pollen of Austrobaileya has many plesiomorphic features that are thought to prolong germination. Yet its germination is quite fast for species with desiccation-tolerant pollen (range: <1 to 60 h). Austrobaileya and other early-divergent angiosperms have relatively rapid pollen germination and short progamic phases, comparable to those of many insect-pollinated monocots and eudicots. These results suggest that both the pollen germination and pollen tube growth periods were marked by acceleration of developmental processes early in angiosperm history. © The Authors 2012.
Hagenauer M.H.,University of Michigan |
Lee T.M.,University of Michigan |
Lee T.M.,University of Tennessee at Knoxville
Hormones and Behavior | Year: 2013
This article is part of a Special Issue "Puberty and Adolescence".One of the defining characteristics of adolescence in humans is a large shift in the timing and structure of sleep. Some of these changes are easily observable at the behavioral level, such as a shift in sleep patterns from a relatively morning to a relatively evening chronotype. However, there are equally large changes in the underlying architecture of sleep, including a >. 60% decrease in slow brain wave activity, which may reflect cortical pruning. In this review we examine the developmental forces driving adolescent sleep patterns using a cross-species comparison. We find that behavioral and physiological sleep parameters change during adolescence in non-human mammalian species, ranging from primates to rodents, in a manner that is often hormone-dependent. However, the overt appearance of these changes is species-specific, with polyphasic sleepers, such as rodents, showing a phase-advance in sleep timing and consolidation of daily sleep/wake rhythms. Using the classic two-process model of sleep regulation, we demonstrate via a series of simulations that many of the species-specific characteristics of adolescent sleep patterns can be explained by a universal decrease in the build-up and dissipation of sleep pressure. Moreover, and counterintuitively, we find that these changes do not necessitate a large decrease in overall sleep need, fitting the adolescent sleep literature. We compare these results to our previous review detailing evidence for adolescent changes in the regulation of sleep by the circadian timekeeping system (. Hagenauer and Lee, 2012), and suggest that both processes may be responsible for adolescent sleep patterns. © 2013 .
Jiang D.,UTRC - United Technologies Research Center |
Wang F.F.,University of Tennessee at Knoxville
IEEE Transactions on Power Electronics | Year: 2013
Compared with the widely used constant switching frequency pulse-width-modulation (PWM) method, variable switching frequency PWM can benefit more because of the extra freedom. Based on the analytical expression of current ripple of three-phase converters, variable switching frequency control methods are proposed to satisfy different ripple requirements. Switching cycle Ts is updated in DSP in every interruption period based on the ripple requirement. Two methods are discussed in this paper. The first method is designed to arrange the current ripple peak value within a certain value and can reduce the equivalent switching frequency and electromagnetic interference (EMI) noise; the second method is designed to keep ripple current RMS value constant and reduce the EMI noise. Simulation and experimental results show that variable switching frequency control could improve the performance of EMI and efficiency without impairing the power quality. © 1986-2012 IEEE.
Godsoe W.,University of Tennessee at Knoxville
Systematic Biology | Year: 2010
Traditionally, the goal of systematics has been to produce classifications that are both strongly supported and biologically meaningful. In recent years several authors have advocated complementing phylogenetic analyses with measures of another form of evolutionary change, ecological divergence. These analyses frequently rely on ecological niche models to determine if species have comparable environmental requirements, but it has heretofore been difficult to test the accuracy of these inferences. To address this problem, I simulate the geographic distributions of allopatric species with identical environmental requirements. I then test whether existing analyses based on geographic distributions will correctly infer that the 2 species' requirements are identical. This work demonstrates that when taxa disperse to different environments, many analyses can erroneously infer changes in environmental requirements, but the severity of the problem depends on the method used. As this could exaggerate the number of ecologically distinct taxa in a clade, I suggest diagnostics to mitigate this problem.
Paluch M.,University of Silesia |
Paluch M.,University of Tennessee at Knoxville |
Wojnarowska Z.,University of Silesia |
Hensel-Bielowka S.,University of Silesia
Physical Review Letters | Year: 2013
In this Letter, we investigate the time evolution of the conductivity relaxation process in a prototypical ionic glass former, [Ca(NO 3)2]0.4[KNO3]0.6 (CKN), undergoing physical aging. It is demonstrated that the heterogeneous nature of molecular dynamics is manifested by an increase in the slope of the high frequency wing of the conductivity relaxation peak as the sample is annealed below the glass transition temperature. This finding is also confirmed for other ionic glass formers. Additionally, we analyze the kinetics of the change in the ionic conductivity in glassy CKN to probe its structural relaxation. © 2013 American Physical Society.
Thibert-Plante X.,McGill University |
Thibert-Plante X.,University of Tennessee at Knoxville |
Hendry A.P.,McGill University
Journal of Evolutionary Biology | Year: 2011
Many factors could influence progress towards sympatric speciation. Some of the potentially important ones include competition, mate choice and the degree to which alternative sympatric environments (resources) are discrete. What is not well understood is the relative importance of these different factors, as well as interactions among them. We use an individual-based numerical model to investigate the possibilities. Mate choice was modelled as the degree to which male foraging traits influence female mate choice. Competition was modelled as the degree to which individuals with different phenotypes compete for portions of the resource distribution. Discreteness of the environment was modelled as the degree of bimodality of the underlying resource distribution. We find that strong mate choice was necessary, but not sufficient, to cause sympatric speciation. In addition, sympatric speciation was most likely when the resource distribution was strongly bimodal and when competition among different phenotypes was intermediate. Even under these ideal conditions, however, sympatric speciation occurred only a fraction of the time. Sympatric speciation owing to competition on unimodal resource distributions was also possible, but much less common. In all cases, stochasticity played an important role in determining progress towards sympatric speciation, as evidenced by variation in outcomes among replicate simulations for a given set of parameter values. Overall, we conclude that the nature of competition is much less important for sympatric speciation than is the nature of mate choice and the underlying resource distribution. We argue that an increased understanding of the promoters and inhibitors of sympatric speciation is best achieved through models that simultaneously evaluate multiple potential factors. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.
O'Meara B.C.,University of Tennessee at Knoxville
Systematic Biology | Year: 2010
Species delimitation and species tree inference are difficult problems in cases of recent divergence, especially when different loci have different histories. This paper quantifies the difficulty of jointly finding the division of samples to species and estimating a species tree without constraining the possible assignments a priori. It introduces a parametric and a nonparametric method, including new heuristic search strategies, to do this delimitation and tree inference using individual gene trees as input. The new methods were evaluated using thousands of simulations and 4 empirical data sets. These analyses suggest that the new methods, especially the nonparametric one, may provide useful insights for systematists working at the species level with molecular data. However, they still often return incorrect results.
Nagle N.N.,University of Tennessee at Knoxville
Geographical Analysis | Year: 2010
This article summarizes area-to-point (ATP) factorial kriging that allows the smoothing of aggregate, areal data into a continuous spatial surface. Unlike some other smoothing methods, ATP factorial kriging does not suppose that all of the data within an area are located at a centroid or other arbitrary point. Also, unlike some other smoothing methods, factorial kriging allows the user to utilize an autocovariance function to control the smoothness of the output. This is beneficial because the covariance function is a physically meaningful statement of spatial relationship, which is not the case when other spatial kernel functions are used for smoothing. Given a known covariance function, factorial kriging gives the smooth surface that is best in terms of minimizing the expected mean squared prediction error. I present an application of the factorial kriging methodology for visualizing the structure of employment density in the Denver metropolitan area. © 2010 The Ohio State University.
Nakanishi M.,University of Tennessee at Knoxville |
Nozaki R.,Hokkaido University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011
A simplified model of a hydrogen-bonding network is proposed in order to clarify the microscopic structure of the cooperative rearranging region (CRR) in Adam-Gibbs theory. Our model can be solved analytically, and it successfully explains the reported systematic features of the glass transition of polyhydric alcohols. In this model, hydrogen bonding is formulated based on binding free energy. Assuming a cluster of molecules connected by double hydrogen bonds is a CRR and approximating the hydrogen-bonding network as a Bethe lattice in percolation theory, the temperature dependence of the structural relaxation time can be obtained analytically. Reported data on relaxation times are well described by the obtained equation. By taking the lower limit of the binding free energy with this equation, the Vogel-Fulcher-Tammann equation can be derived. Consequently, the fragility index and glass transition temperature can be expressed as functions of the number of OH groups in a molecule, and this relation agrees well with the reported experimental data. © 2011 American Physical Society.
Schaefferkoetter J.,University of Tennessee at Knoxville
Physics in medicine and biology | Year: 2013
Time-of-flight (TOF) and point spread function (PSF) modeling have been shown to improve PET reconstructions, but the impact on physicians in the clinical setting has not been thoroughly investigated. A lesion detection and localization study was performed using simulated lesions in real patient images. Four reconstruction schemes were considered: ordinary Poisson OSEM (OP) alone and combined with TOF, PSF, and TOF + PSF. The images were presented to physicians experienced in reading PET images, and the performance of each was quantified using localization receiver operating characteristic. Numerical observers (non-prewhitening and Hotelling) were used to identify optimal reconstruction parameters, and observer SNR was compared to the performance of the physicians. The numerical models showed good agreement with human performance, and best performance was achieved by both when using TOF + PSF. These findings suggest a large potential benefit of TOF + PSF for oncology PET studies, especially in the detection of small, low-intensity, focal disease in larger patients.
Bui H.N.,University of Tennessee at Knoxville
Journal of Immigrant and Minority Health | Year: 2013
Using data from the National Longitudinal Studies of Adolescent Health, the present study examines self-reported substance use (cigarettes, tobacco, and marijuana) among youth from different immigration generations to determine the immigrant paradox in substance use for different racial and ethnic groups as well as factors contributing to the relationship between immigration and substance use. Results of data analysis indicate the immigrant paradox in substance use among non-Hispanic Whites, Asians, and Hispanics, but not among non-Hispanic Blacks. The study also shows that factors explaining the immigrant paradox in substance use vary with racial and ethnic groups, but English use at home, friends' cigarette and marijuana use appear to be the most important mediating factors. Findings from the study suggest that effective interventions in youth substance use require an understanding of adaptation patterns in different racial and ethnic groups, so that factors associated with adaptation problems experienced by particular groups will be appropriately addressed. © 2012 Springer Science+Business Media, LLC.
Li H.,University of Tennessee at Knoxville |
Lai L.,University of Arkansas at Little Rock |
Poor H.V.,Princeton University
IEEE Journal on Selected Areas in Communications | Year: 2012
In cyber physical systems, communication is needed for conveying sensor observations to controllers; thus, the design of the communication sub-system is of key importance for the stabilization of system dynamics. In this paper, multicast routing is studied for networking of decentralized sensors and controllers. The challenges of uncertain destinations and multiple routing modes, which are significantly different from traditional data networks, are addressed by employing the theories of hybrid systems and linear matrix inequalities, thus forming a novel framework for studying the communication sub-system in cyber physical systems. Both cases of neglible delay and non-negligible delay are discussed. The proposed framework is then applied in the context of voltage control in smart grid. Numerical simulations using a 4-bus power grid model show that the proposed framework and algorithm can effectively stabilize cyber physical systems. © 2012 IEEE.
Khatabi B.,University of Tennessee at Knoxville
Plant signaling & behavior | Year: 2012
Ethylene (ET) is a gaseous phytohormone that participates in various plant physiological processes and essentially contributes to plant immunity. ET conducts its functions by regulating the expression of ET-responsive genes or in crosstalk with other hormones. Several recent studies have shown the significance of ET in the establishment and development of plant-microbe interactions. Therefore, it is not surprising that pathogens and mutualistic symbionts target ET synthesis or signaling to colonize plants. This review introduces the significance of ET metabolism in plant-microbe interactions, with an emphasis on its role in mutualistic symbioses.
Padmanabhan M.S.,University of California at Davis |
Ma S.,University of California at Davis |
Burch-Smith T.M.,University of Tennessee at Knoxville |
Czymmek K.,University of Delaware |
And 2 more authors.
PLoS Pathogens | Year: 2013
Following the recognition of pathogen-encoded effectors, plant TIR-NB-LRR immune receptors induce defense signaling by a largely unknown mechanism. We identify a novel and conserved role for the SQUAMOSA PROMOTER BINDING PROTEIN (SBP)-domain transcription factor SPL6 in enabling the activation of the defense transcriptome following its association with a nuclear-localized immune receptor. During an active immune response, the Nicotiana TIR-NB-LRR N immune receptor associates with NbSPL6 within distinct nuclear compartments. NbSPL6 is essential for the N-mediated resistance to Tobacco mosaic virus. Similarly, the presumed Arabidopsis ortholog AtSPL6 is required for the resistance mediated by the TIR-NB-LRR RPS4 against Pseudomonas syringae carrying the avrRps4 effector. Transcriptome analysis indicates that AtSPL6 positively regulates a subset of defense genes. A pathogen-activated nuclear-localized TIR-NB-LRR like N can therefore regulate defense genes through SPL6 in a mechanism analogous to the induction of MHC genes by mammalian immune receptors like CIITA and NLRC5. © 2013 Padmanabhan et al.
Gao Y.,University of Tennessee at Knoxville |
Gao Y.,Oak Ridge National Laboratory
Journal of the Mechanics and Physics of Solids | Year: 2010
Stickslip behavior observed from nanoscale asperity friction experiments are often modeled by the one-degree-of-freedom Tomlinson model, which is unable to explain the effects of lattice structure and interface defects, or by molecular simulations which suffer temporal limitations in modeling the velocity- and temperature-dependent frictional behavior. A Peierls-type model developed in this work views the atomic frictional process as the initiation and gliding passage of dislocations with diffused cores on the interface. As a consequence of loss-of-ellipticity instability, the occurrence of stickslip behavior relies on the interaction among interface slip field, contact stress fields, and existing defects. The friction stress for commensurate interface under large contact area can be approximated from the Rice model of screw-dislocation nucleation from a planar crack tip. The spatially inhomogeneous nature of rate-limiting processes and the coupling effects between contact size and interface incommensurability are successfully determined, which cannot otherwise be tackled in the Tomlinsonmodel. © 2010 Elsevier Ltd. All rights reserved.
Singh V.,University of Tennessee at Knoxville |
Holt L.,Instructional Technology
Computers and Education | Year: 2013
This research is about participants who use open-source software (OSS) discussion forums for learning. Learning in online communities of education as well as non-education-related online communities has been studied under the lens of social learning theory and situated learning for a long time. In this research, we draw parallels among these two types of communities and explore what can be learned from open-source software communities about online learning. Thematic network analysis was used to code the qualitative data from the open-ended questions in the survey and the interviews. The results indicate that learning in online open-source software communities encompasses much more than just learning about the software being discussed. 283 Open-source forum participants were surveyed, and 21 were interviewed to develop an understanding of the challenges to learning in these communities as well as to identify the practices that promote learning. Identifying these practices helps to understand online learning and enables the integration of best practices into online education. © 2012 Elsevier Ltd. All rights reserved.
Gavrilets S.,University of Tennessee at Knoxville |
Fortunato L.,University of Oxford |
Fortunato L.,Santa Fe Institute
Nature Communications | Year: 2014
Conflict with conspecifics from neighbouring groups over territory, mating opportunities and other resources is observed in many social organisms, including humans. Here we investigate the evolutionary origins of social instincts, as shaped by selection resulting from between-group conflict in the presence of a collective action problem. We focus on the effects of the differences between individuals on the evolutionary dynamics. Our theoretical models predict that high-rank individuals, who are able to usurp a disproportional share of resources in within-group interactions, will act seemingly altruistically in between-group conflict, expending more effort and often having lower reproductive success than their low-rank group-mates. Similar behaviour is expected for individuals with higher motivation, higher strengths or lower costs, or for individuals in a leadership position. Our theory also provides an evolutionary foundation for classical equity theory, and it has implications for the origin of coercive leadership and for reproductive skew theory. © 2014 Macmillan Publishers Limited.
Singh V.,University of Tennessee at Knoxville
Information Technology and Libraries | Year: 2013
Interest in migrating to open-source integrated library systems is continually growing in libraries. Along with the interest, lack of empirical research and evidence to compare the process of migration brings a lot of anxiety to the interested librarians. In this research, twenty librarians who have worked in libraries that migrated to open-source integrated library system (ILS) or are in the process of migrating were interviewed. The interviews focused on their experiences and the lessons learned in the process of migration. The results from the interviews are used to create guidelines/best practices for each stage of the adoption process of an open-source ILS. These guidelines will be helpful for librarians who want to research and adopt an open-source ILS.
Sheng H.,Google |
Wang F.F.,University of Tennessee at Knoxville |
Tipton Iv C.W.,U.S. Army
IEEE Transactions on Power Electronics | Year: 2012
Fault detection and protection is an important design aspect for any power converter, especially in high-power high-voltage applications, where cost of failure can be high. The three-level dc-dc converter and its varied derivatives are attractive topologies in high-voltage high-power converter applications. The protection method can not only prevent the system failure against unbalanced voltage stresses on the switches, but also provide a remedy for the system as faults occur and save the remaining components. The three-level converter is subject to voltage unbalance in certain abnormal conditions, which can result in switch overvoltage and system failure. The reasons for the unbalanced voltage stresses are fully investigated and categorized. The solutions to each abnormal condition are introduced. In addition to the voltage unbalance, the three-level converters can be protected against multiple faults by the proposed protection method through monitoring the flying capacitor voltage. Phenomena associated with each fault are thoroughly analyzed and summarized. The protection circuit is simple and can be easily implemented, while it can effectively protect the three-level converters and its derivatives, which has been verified by the experiment with a three-level parallel resonant converter. © 2011 IEEE.
Tran L.,University of Tennessee at Knoxville
Ecological Indicators | Year: 2016
The paper proposes a method for selecting a set of sustainable development indicators which can be used for various sustainability-related tasks, such as assessment of current condition, measure of progress toward specific goals of sustainable development, in general, and sustainable urban development, in particular. The method is based on variable clustering, selecting cluster representative, and multivariate linear regression in combination with experts and stakeholders' input in an interactive process. The small set of indicators derived from the proposed method was able to account for a significant amount of information from the initial indicator set while effectively assisting stakeholders in making informed decision based on objective quantitative information and meeting their preference simultaneously. © 2015 Elsevier Ltd.
Harden C.P.,University of Tennessee at Knoxville
Annals of the Association of American Geographers | Year: 2012
Ways in which geographers have framed research on human-environment interactions have changed over time. This review emphasizes the limitations of previous ways of framing human-environment research and indicates new opportunities to be pursued by reframing the research questions. It begins with the research and influence of W. M. Davis and follows with research framed as environmental determinism, human ecology, natural hazards, human impacts on the environment, and sustainability. Studies of interactions between people and environments are central to geography, but such studies have dominantly been one-sided as a result of the type of relationship studied or the perspectives (physical or social) brought by the investigators. Awareness of the nature of nature and the dynamic, interactive behavior of biophysical and human systems has the potential to bring new perspectives to the traditional human-environment dichotomy. Because many of the world's important problems involve interactions between people and environments, geographers are encouraged to turn their attention to this core area of the discipline. Research opportunities include studies of the effects of environmental change on human populations, including the complex web of interactions and feedbacks involved; studies of how environmental services are valued and managed; and other studies that provide knowledge to support more sustainable human-environment interactions, especially in an urbanizing world. © 2012 Copyright Taylor and Francis Group, LLC.
Miller L.E.,University of Tennessee at Knoxville
Journal of Cancer Survivorship | Year: 2012
Purpose: Previous research has demonstrated the common experience of illness-related uncertainty; however, little research has explored the specific sources of uncertainty throughout cancer survivorship. The purpose of this study is to investigate the experience of uncertainty for cancer survivors and their partners. Thus, the following research question is posed: What are the sources of uncertainty in cancer survivorship for survivors and partners?Method: One-on-one interviews were conducted with 35 cancer survivors and 25 partners. Constant comparative methodologies were used to analyze the data. Results: Participants described medical, personal, and social sources of uncertainty that persisted throughout survivorship. Medical sources of uncertainty included questions about the cancer diagnosis, treatment and prognosis. Personal sources of uncertainty included ambiguous valued identities and career-related questions. Social sources of uncertainty included unclear communicative, relational and familial consequences of illness. Conclusion: Survivors and partners in this study experienced uncertainty that persisted long after the completion of cancer treatment. The participants also described sources of uncertainty unique to this illness context. These results have important implications for health care providers and intervention developers and imply that chronic uncertainty should be managed throughout survivorship. Implications for cancer survivors: The sources of uncertainty described in the current study have important implications for cancer survivors' management of uncertainty. Cancer survivors and their family members must first know the common sources of uncertainty to adaptively adjust to an uncertain survivorship trajectory. The present investigation provides insight into the uncertainty experiences of cancer survivors and implies that continued care may improve well-being after the completion of cancer treatment. © 2012 Springer Science+Business Media, LLC.
Schilling E.E.,University of Tennessee at Knoxville |
Panero J.L.,University of Texas at Austin
Botanical Journal of the Linnean Society | Year: 2011
Sequence data for internal transcribed spacer (ITS) and partial external transcribed spacer (ETS) regions were combined in a phylogenetic analysis with previously obtained plastid DNA restriction site data to provide a comprehensive molecular phylogenetic hypothesis for derived members of subtribe Helianthinae. Analyses of the two molecular datasets provided conflicting evidence on relationships among some groups, supporting the hypothesis that hybridization has played a significant role in the divergence of the subtribe. A revised generic-level classification is presented that divides the approximately 350 species of the subtribe among 21 genera. The paraphyletic Viguiera is narrowed to embrace only the type species, V.dentata. Four newly described genera, Dendroviguiera, Gonzalezia, Heiseria and Sidneya, are composed of species formerly included in Viguiera. Aldama is expanded to include 118 species extending from southwestern North America and Mexico to South America. This requires 116 new combinations, including 58 that were recently transferred into Rhysolepis, which is a synonym of Aldama, based on molecular phylogenetic results. One species of Viguiera is transferred to Tithonia, and two combinations in Hymenostephium are validated. © 2011 The Linnean Society of London.
Graham D.E.,University of Tennessee at Knoxville
Methods in Enzymology | Year: 2011
Coenzyme M (CoM) and coenzyme B (CoB) are essential for methane production by the euryarchaea that employ this specialized anaerobic metabolism. Two pathways are known to produce CoM, 2-mercaptoethanesulfonate, and both converge on the 2-oxoacid sulfopyruvate. These cells have recruited the rich biochemistry of amino acid and 2-oxoacid metabolizing enzymes to produce a compound that resembles oxaloacetate, but with a more stable and acidic sulfonate group. 7-Mercaptoheptanoylthreonine phosphate, CoB, likewise owes its carbon backbone to a 2-oxoacid. Three enzymes recruited from leucine biosynthesis have evolved to catalyze the elongation of 2-oxoglutarate to 2-oxosuberate in CoB biosynthesis. This chapter describes the enzymology, synthesis, and analytical techniques used to study 2-oxoacid metabolism in these pathways. Protein structure and mechanistic information from enzymes provide insight into the evolution of new enzymatic activity, and the evolution of substrate specificity from promiscuous enzyme scaffolds. © 2011 Elsevier Inc. All rights reserved.
Troparevsky M.C.,Oak Ridge National Laboratory |
Morris J.R.,Oak Ridge National Laboratory |
Morris J.R.,University of Tennessee at Knoxville |
Kent P.R.C.,Oak Ridge National Laboratory |
And 2 more authors.
Physical Review X | Year: 2015
High-entropy alloys constitute a new class of materials whose very existence poses fundamental questions regarding the physical principles underlying their unusual phase stability. Originally thought to be stabilized by the large entropy of mixing associated with their large number of components (five or more), these alloys have attracted attention for their potential applications. Yet, no model capable of robustly predicting which combinations of elements will form a single phase currently exists. Here, we propose a model that, through the use of high-throughput computation of the enthalpies of formation of binary compounds, predicts specific combinations of elements most likely to form single-phase, highentropy alloys. The model correctly identifies all known single-phase alloys while rejecting similar elemental combinations that are known to form an alloy comprising multiple phases. In addition, we predict numerous potential single-phase alloy compositions and provide three tables with the ten most likely five-, six-, and seven-component single-phase alloys to guide experimental searches.
Dong S.,Nanjing Southeast University |
Liu J.-M.,Nanjing University |
Dagotto E.,University of Tennessee at Knoxville |
Dagotto E.,Oak Ridge National Laboratory
Physical Review Letters | Year: 2014
The iron selenides are important because of their superconducting properties. Here, an unexpected phenomenon is predicted to occur in an iron-selenide compound with a quasi-one-dimensional ladder geometry: BaFe2Se3 should be a magnetic ferrielectric system, driven by its magnetic block order via exchange striction. A robust performance (high TC and large polarization) is expected. Different from most multiferroics, BaFe2Se3 is ferrielectric, with a polarization that mostly cancels between ladders. However, its strong magnetostriction still produces a net polarization that is large (∼0.1μC/cm2) as compared with most magnetic multiferroics. Its fully ferroelectric state, with energy only slightly higher than the ferrielectric, has a giant improper polarization ∼2-3μC/cm2. © 2014 American Physical Society.
Freberg K.,University of Louisville |
Freberg K.,University of Tennessee at Knoxville
Public Relations Review | Year: 2012
The rapid growth of social media challenges crisis communicators to disseminate safety messages to affected audiences quickly and in a manner that promotes maximum compliance. A nationally representative consumer panel responded to food recall messages that varied in source (organizational or user-generated) and reliability (confirmed versus unconfirmed). Results indicated that intent to comply with a food recall message was stronger in response to organizational messages than to user-generated messages, but did not vary according to message reliability. Strong age cohort effects were seen in the responses to message source, with younger participants making less distinction than older cohorts between organizational and user-generated sources. Implications of the results for public relations and crisis communications theory and practice, limitations of the study, and recommendations for future research were discussed. © 2012 Elsevier Inc.
Moran E.V.,University of Tennessee at Knoxville |
Clark J.S.,Duke University
PLoS ONE | Year: 2012
Background: Nut-bearing trees, including oaks (Quercus spp.), are considered to be highly dispersal limited, leading to concerns about their ability to colonize new sites or migrate in response to climate change. However, estimating seed dispersal is challenging in species that are secondarily dispersed by animals, and differences in disperser abundance or behavior could lead to large spatio-temporal variation in dispersal ability. Parentage and dispersal analyses combining genetic and ecological data provide accurate estimates of current dispersal, while spatial genetic structure (SGS) can shed light on past patterns of dispersal and establishment. Methodology and Principal Findings: In this study, we estimate seed and pollen dispersal and parentage for two mixed-species red oak populations using a hierarchical Bayesian approach. We compare these results to those of a genetic ML parentage model. We also test whether observed patterns of SGS in three size cohorts are consistent with known site history and current dispersal patterns. We find that, while pollen dispersal is extensive at both sites, the scale of seed dispersal differs substantially. Parentage results differ between models due to additional data included in Bayesian model and differing genotyping error assumptions, but both indicate between-site dispersal differences. Patterns of SGS in large adults, small adults, and seedlings are consistent with known site history (farmed vs. selectively harvested), and with long-term differences in seed dispersal. This difference is consistent with predator/disperser satiation due to higher acorn production at the low-dispersal site. While this site-to-site variation results in substantial differences in asymptotic spread rates, dispersal for both sites is substantially lower than required to track latitudinal temperature shifts. Conclusions: Animal-dispersed trees can exhibit considerable spatial variation in seed dispersal, although patterns may be surprisingly constant over time. However, even under favorable conditions, migration in heavy-seeded species is likely to lag contemporary climate change. © 2012 Moran, Clark.
Petersen E.J.,U.S. National Institute of Standards and Technology |
Henry T.B.,University of Tennessee at Knoxville |
Henry T.B.,University of Plymouth
Environmental Toxicology and Chemistry | Year: 2012
The recent emergence of manufactured nanoparticles (NPs) that are released into the environment and lead to exposure in organisms has accelerated the need to determine NP toxicity. Techniques for measuring the toxicity of NPs (nanotoxicology) in ecological receptors (nanoecotoxicology) are in their infancy, however, and establishing standardized ecotoxicity tests for NPs are presently limited by several factors. These factors include the extent of NP characterization necessary (or possible) before, during, and after toxicity tests such that toxic effects can be related to physicochemical characteristics of NPs; determining uptake and distribution of NPs within exposed organisms (does uptake occur or are effects exerted at organism surfaces?); and determining the appropriate types of controls to incorporate into ecotoxicity tests with NPs. In this review, the authors focus on the important elements of measuring the ecotoxicity of carbon NPs (CNPs) and make recommendations for ecotoxicology testing that should enable more rigorous interpretations of collected data and interlaboratory comparisons. This review is intended to serve as a next step toward developing standardized tests that can be incorporated into a regulatory framework for CNPs. © 2011 SETAC.
Yau Y.-Y.,Northeastern State University |
Stewart C.N.,University of Tennessee at Knoxville
BMC Biotechnology | Year: 2013
Selectable marker genes (SMGs) and selection agents are useful tools in the production of transgenic plants by selecting transformed cells from a matrix consisting of mostly untransformed cells. Most SMGs express protein products that confer antibiotic- or herbicide resistance traits, and typically reside in the end product of genetically-modified (GM) plants. The presence of these genes in GM plants, and subsequently in food, feed and the environment, are of concern and subject to special government regulation in many countries. The presence of SMGs in GM plants might also, in some cases, result in a metabolic burden for the host plants. Their use also prevents the re-use of the same SMG when a second transformation scheme is needed to be performed on the transgenic host. In recent years, several strategies have been developed to remove SMGs from GM products while retaining the transgenes of interest. This review describes the existing strategies for SMG removal, including the implementation of site specific recombination systems, TALENs and ZFNs. This review discusses the advantages and disadvantages of existing SMG-removal strategies and explores possible future research directions for SMG removal including emerging technologies for increased precision for genome modification. © 2013 Yau and Stewart; licensee BioMed Central Ltd.
Wang Y.,University of Tennessee at Knoxville |
Wang X.,Ohio State University
IEEE Transactions on Parallel and Distributed Systems | Year: 2013
Many power management strategies have been proposed for enterprise servers based on dynamic voltage and frequency scaling (DVFS), but those solutions cannot further reduce the energy consumption of a server when the server processor is already at the lowest DVFS level and the server utilization is still low (e.g., 10 percent or lower). To achieve improved energy efficiency, request batching can be conducted to group received requests into batches and put the processor into sleep between the batches. However, it is challenging to perform request batching on a virtualized server because different virtual machines on the same server may have different workload intensities. Hence, putting the shared processor into sleep may severely impact the application performance of all the virtual machines. This paper proposes Virtual Batching, a novel request batching solution for virtualized servers with primarily light workloads. Our solution dynamically allocates CPU resources such that all the virtual machines can have approximately the same performance level relative to their allowed peak values. Based on this uniform level, Virtual Batching determines the time length for periodically batching incoming requests and putting the processor into sleep. When the workload intensity changes from light to moderate, request batching is automatically switched to DVFS to increase processor frequency for performance guarantees. Virtual Batching is also extended to integrate with server consolidation for maximized energy conservation with performance guarantees for virtualized data centers. Empirical results based on a hardware testbed and real trace files show that Virtual Batching can achieve the desired performance with more energy conservation than several well-designed baselines, e.g., 63 percent more, on average, than a solution based on DVFS only. © 1990-2012 IEEE.
Li H.,University of Tennessee at Knoxville |
Han Z.,University of Houston
IEEE Transactions on Wireless Communications | Year: 2010
In cognitive radio systems, primary user emulation (PUE) attack means that an attacker sends primary-user-like signals during the spectrum sensing period such that honest secondary users leave the corresponding channels, which causes a serious threat to cognitive radio systems. A passive anti-PUE approach, similar to the random frequency hopping in traditional anti-jamming schemes, is proposed and called dogfight in spectrum. In this scheme, the defenders randomly choose channels to sense and avoid the PUE attack. It is assumed that the channel statistics like availability probabilities are known; then the PUE attack and the random hopping are modeled as a zero-sum game between the attacker and defending secondary user(s). The Nash equilibrium of the game is found. The anti-jamming efficiency is also obtained. Numerical simulations demonstrated the performances of the proposed schemes for both the single defender, multiple defender and multiple round cases. © 2010 IEEE.
Jiang D.-E.,Oak Ridge National Laboratory |
Overbury S.H.,Oak Ridge National Laboratory |
Dai S.,Oak Ridge National Laboratory |
Dai S.,University of Tennessee at Knoxville
Journal of the American Chemical Society | Year: 2013
Au15(SR)13 is the smallest stable thiolated gold nanocluster experimentally identified so far, and its elusive structure may hold the key to the origin of the nucleus in the formation of thiolated gold nanoclusters. By an extensive exploration of possible isomers by density functional theory, we arrive at a novel structure for Au15(SR) 13 with high stability and whose optical absorption characteristics match those of the experiment. Different from the previous structures and the prevailing working hypothesis about the construction of thiolated gold nanoclusters, the Au15(SR)13 model features a cyclic [Au(I)-SR] pentamer interlocked with one staple trimer motif protecting the tetrahedral Au4 nucleus, together with another trimer motif. This structure suggests that Au15(SR)13 is a transitional composition from an [Au(I)-SR]x polymer such as Au 10(SR)10 to larger Aun(SR)m (n > m) clusters that have only the staple motifs and that the nucleation process starts from the Au4 core. © 2013 American Chemical Society.
Mahoney M.C.,University of Cincinnati |
Ingram A.D.,University of Tennessee at Knoxville
American Journal of Roentgenology | Year: 2014
OBJECTIVE. The objective of this article is to describe the types of breast emergencies that can be encountered in a breast imaging practice, discuss the characteristic imaging features of these emergencies, and explain the most common methods and interventions used for the treatment of breast emergencies and complications. CONCLUSION. Breast emergencies are uncommon but require prompt identification and management when they do occur. Patients with mastitis or a breast abscess may be seen for either diagnosis or treatment. Most complications are the result of interventional procedures. Pseudoaneurysms, postbiopsy hematoma, and localization wire migration are the most common situations encountered. A milk fistula resulting from a core biopsy is uncommon. Fortunately, seat-belt injuries to the breast are rare. Knowledge of these entities - of the usual presentation, management, and appropriate follow-up protocols - is essential for breast imagers. © American Roentgen Ray Society.
Maroulas V.,University of Tennessee at Knoxville |
Stinis P.,University of Minnesota
Journal of Computational Physics | Year: 2012
We present a novel approach for improving particle filters for multi-target tracking. The suggested approach is based on drift homotopy for stochastic differential equations. Drift homotopy is used to design a Markov Chain Monte Carlo step which is appended to the particle filter and aims to bring the particle filter samples closer to the observations while at the same time respecting the target dynamics. We have used the proposed approach on the problem of multi-target tracking with a nonlinear observation model. The numerical results show that the suggested approach can improve significantly the performance of a particle filter. © 2011 Elsevier Inc.
Demkowicz M.J.,Massachusetts Institute of Technology |
Bellon P.,Urbana University |
Wirth B.D.,University of Tennessee at Knoxville
MRS Bulletin | Year: 2010
Recent work Indicates that materials with nanoscale architectures, such as nanolayered Cu-Nb composites and nanoscale oxide dispersion-strengthened steels, are both thermally stable and offer improved performance under irradiation. Current understanding of the atomiclevel response of such materials to radiation yields insights into how controlling composition, morphology, and interface-defect interactions may further enable atomic-scale design of radiation-tolerant nanostructured composite materials. With greater understanding of irradiation-assisted degradation mechanisms, this bottom-up design approach may pave the way for creating the extreme environment - tolerant structural materials needed to meet the world's clean energy demand by expanding use of advanced fission and future fusion power.
Cui S.,University of Tennessee at Knoxville
Journal of Physical Chemistry B | Year: 2011
We have carried out Brownian dynamics calculations to investigate the effect of DNA-ion interaction on ion transport in a nanopore. We calculated the self-diffusion coefficient of monovalent ions in the presence of DNA in a nanopore and compared the result with that through an open pore, that is, without the presence of DNA. We find that the self-diffusion coefficient of the co-ions is essentially unaffected by the DNA. The self-diffusion coefficient of the counterions, on the other hand, is significantly reduced depending on the ion concentration. At high ion concentration, around 1 M, the effect of DNA on counterion diffusion is relatively small, causing a slight reduction in counterion diffusion coefficient. At low concentrations of a few millimolar, the effect is much larger, resulting in a reduction in counterion diffusion coefficient by a factor of about 2.5. The variation in the self-diffusion of the counterion is well described by accounting for the contributions from two components: the adsorbed counterions and the free counterions. Detailed dynamics of the DNA-counterion interaction is characterized by the varying length of the transient adsorption time of the counterions to the DNA charge sites and the exchange rate with the environment. This variation in counterion adsorption time is attributed to the ionic electric screening effect, which is in turn determined by the ion concentration. © 2011 American Chemical Society.
Schwartz F.,University of Tennessee at Knoxville
Annales Henri Poincare | Year: 2011
We consider asymptotically flat Riemannian manifolds with non-negative scalar curvature that are conformal to ℝ n\Ω, n ≥ 3, and so that their boundary is a minimal hypersurface. (Here, Ω ⊂ ℝ n is open bounded with smooth mean-convex boundary.) We prove that the ADM mass of any such manifold is bounded below by 1/2(V/β n) (n-2)/n, where V is the Euclidean volume of Ω and β n is the volume of the Euclidean unit n-ball. This gives a partial proof to a conjecture of Bray and Iga (Commun. Anal. Geom. 10:999-1016, 2002). Surprisingly, we do not require the boundary to be outermost. © 2010 Springer Basel AG.
Farmer A.T.,University of Tennessee at Knoxville
ISME Journal | Year: 2015
Corrinoid auxotrophic organohalide-respiring Dehalococcoides mccartyi (Dhc) strains are keystone bacteria for reductive dechlorination of toxic and carcinogenic chloroorganic contaminants. We demonstrate that the lower base attached to the essential corrinoid cofactor of reductive dehalogenase (RDase) enzyme systems modulates dechlorination activity and affects the vinyl chloride (VC) RDases BvcA and VcrA differently. Amendment of 5,6-dimethylbenzimidazolyl-cobamide (DMB-Cba) to Dhc strain BAV1 and strain GT cultures supported cis-1,2-dichloroethene-to-ethene reductive dechlorination at rates of 107.0 (±12.0) μM and 67.4 (±1.4) μM Cl- released per day, respectively. Strain BAV1, expressing the BvcA RDase, reductively dechlorinated VC to ethene, although at up to fivefold lower rates in cultures amended with cobamides carrying 5-methylbenzimidazole (5-MeBza), 5-methoxybenzimidazole (5-OMeBza) or benzimidazole (Bza) as the lower base. In contrast, strain GT harboring the VcrA RDase failed to grow and dechlorinate VC to ethene in medium amended with 5-OMeBza-Cba or Bza-Cba. The amendment with DMB to inactive strain GT cultures restored the VC-to-ethene-dechlorinating phenotype and intracellular DMB-Cba was produced, demonstrating cobamide uptake and remodeling. The distinct responses of Dhc strains with BvcA versus VcrA RDases to different cobamides implicate that the lower base exerts control over Dhc reductive dechlorination rates and extents (that is, detoxification), and therefore the dynamics of Dhc strains with discrete reductive dechlorination capabilities. These findings emphasize that the role of the corrinoid/lower base synthesizing community must be understood to predict strain-specific Dhc activity and achieve efficacious contaminated site cleanup.The ISME Journal advance online publication, 10 November 2015; doi:10.1038/ismej.2015.197. © 2015 International Society for Microbial Ecology
Lennox G.D.,University of Sheffield |
Armsworth P.R.,University of Tennessee at Knoxville
Conservation Biology | Year: 2013
In negotiations over land-right acquisitions, landowners have an informational advantage over conservation groups because they know more about the opportunity costs of conservation measures on their sites. This advantage creates the possibility that landowners will demand payments greater than the required minimum, where this minimum required payment is known as the landowner's willingness to accept (WTA). However, in recent studies of conservation costs, researchers have assumed landowners will accept conservation with minimum payments. We investigated the ability of landowners to demand payments above their WTA when a conservation group has identified multiple sites for protection. First, we estimated the maximum payment landowners could potentially demand, which is set when groups of landowners act as a cooperative. Next, through the simulation of conservation auctions, we explored the amount of money above landowners' WTA (i.e., surplus) that conservation groups could cede to secure conservation agreements, again investigating the influence of landowner cooperatives. The simulations showed the informational advantage landowners held could make conservation investments up to 42% more expensive than suggested by the site WTAs. Moreover, all auctions resulted in landowners obtaining payments greater than their WTA; thus, it may be unrealistic to assume landowners will accept conservation contracts with minimum payments. Of particular significance for species conservation, conservation objectives focused on overall species richness, which therefore recognize site complementarity, create an incentive for landowners to form cooperatives to capture surplus. To the contrary, objectives in which sites are substitutes, such as the maximization of species occurrences, create a disincentive for cooperative formation. © 2013 Society for Conservation Biology.
Trinh C.T.,University of Tennessee at Knoxville
Applied Microbiology and Biotechnology | Year: 2012
Elementary mode (EM) analysis based on the constraint-based metabolic network modeling was applied to elucidate and compare complex fermentative metabolisms of Escherichia coli for obligate anaerobic production of n-butanol and isobutanol. The result shows that the nbutanol fermentative metabolism was NADH-deficient, while the isobutanol fermentative metabolism was NADH redundant. E. coli could grow and produce n-butanol anaerobically as the sole fermentative product but not achieve the maximum theoretical n-butanol yield. In contrast, for the isobutanol fermentative metabolism, E. coli was required to couple with either ethanol- or succinate-producing pathway to recycle NADH. To overcome these "defective" metabolisms, EM analysis was implemented to reprogram the native fermentative metabolism of E. coli for optimized anaerobic production of n-butanol and isobutanol through multiple gene deletion (̃8-9 genes), addition (̃6-7 genes), up- and downexpression (̃6-7 genes), and cofactor engineering (e.g., NADH, NADPH). The designed strains were forced to couple both growth and anaerobic production of nbutanol and isobutanol, which is a useful characteristic to enhance biofuel production and tolerance through metabolic pathway evolution. Even though the n-butanol and isobutanol fermentative metabolisms were quite different, the designed strains could be engineered to have identical metabolic flux distribution in "core" metabolic pathways mainly supporting cell growth and maintenance. Finally, the model prediction in elucidating and reprogramming the native fermentative metabolism of E. coli for obligate anaerobic production of n-butanol and isobutanol was validated with published experimental data. © Springer-Verlag 2012.
Gavrilets S.,University of Tennessee at Knoxville
Cold Spring Harbor Perspectives in Biology | Year: 2014
At the end of the last century, sexual conflict was identified as a powerful engine of speciation, potentially even more important than ecological selection. Earlier work that followed-experimental, comparative, and mathematical—provided strong initial support for this assertion. However, as the field matures, both the power of sexual conflict and constraints on the evolution of reproductive isolation as driven by sexual conflict are becoming better understood. From theoretical studies, we now know that speciation is only one of several possible evolutionary outcomes of sexual conflict. In line with these predictions, both experimental evolution studies and comparative analyses of fertilization proteins and of species richness show that sexual conflict leads to, or is associated with, reproductive isolation and speciation in some cases but not in others. Increased genetic variation (especially in females) without reproductive isolation is an underappreciated consequence of sexually antagonistic selection. © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.
Fordyce J.A.,University of Tennessee at Knoxville
PLoS ONE | Year: 2010
Background: Phylogenetic hypotheses are increasingly being used to elucidate historical patterns of diversification rate-variation. Hypothesis testing is often conducted by comparing the observed vector of branching times to a null, pure-birth expectation. A popular method for inferring a decrease in speciation rate, which might suggest an early burst of diversification followed by a decrease in diversification rate is the γ statistic. Methodology: Using simulations under varying conditions, I examine the sensitivity of γ to the distribution of the most recent branching times. Using an exploratory data analysis tool for lineages through time plots, tree deviation, I identified trees with a significant γ statistic that do not appear to have the characteristic early accumulation of lineages consistent with an early, rapid rate of cladogenesis. I further investigated the sensitivity of the γ statistic to recent diversification by examining the consequences of failing to simulate the full time interval following the most recent cladogenic event. The power of γ to detect rate decrease at varying times was assessed for simulated trees with an initial high rate of diversification followed by a relatively low rate. Conclusions: The γ statistic is extraordinarily sensitive to recent diversification rates, and does not necessarily detect early bursts of diversification. This was true for trees of various sizes and completeness of taxon sampling. The γ statistic had greater power to detect recent diversification rate decreases compared to early bursts of diversification. Caution should be exercised when interpreting the γ statistic as an indication of early, rapid diversification. © 2010 Fordyce et al.
Sundqvist M.K.,Swedish University of Agricultural Sciences |
Sanders N.J.,University of Tennessee at Knoxville |
Sanders N.J.,Rocky Mountain Biological Laboratory |
Sanders N.J.,Copenhagen University |
Wardle D.A.,Swedish University of Agricultural Sciences
Annual Review of Ecology, Evolution, and Systematics | Year: 2013
Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There are also many exceptions, sometimes because other factors such as precipitation can also vary with elevation. Given this complexity, our capacity to predict when and why the same variable responds differently among disparate elevational gradients is often limited. Furthermore, there is utility in using elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental manipulations will provide powerful information that can improve predictions of climate change impacts within and across ecosystems. © Copyright ©2013 by Annual Reviews. All rights reserved.
Keenan J.A.,University of Tennessee at Knoxville
Annals of Pharmacotherapy | Year: 2011
Ulipristal acetate is the first selective progesterone receptor modulator approved for postcoital contraception in the US. It appears to be significantly more effective in inhibition of ovulation than other forms of emergency contraception. However, ulipristal acetate is structurally similar to mifepristone, and several lines of evidence suggest that a postfertilization mechanism of action is also operative. This mechanism of action is considered to be contragestive versus contraceptive. Ulipristal acetate administration is contraindicated in a known or suspected pregnancy; however, it could quite possibly be used as an effective abortifacient. Health-care providers should inform patients of the possibility of both mechanisms of action with use of this drug.
Guidry M.,University of Tennessee at Knoxville |
Guidry M.,Oak Ridge National Laboratory
Journal of Computational Physics | Year: 2012
In contrast to the prevailing view in the literature, it is shown that even extremely stiff sets of ordinary differential equations may be solved efficiently by explicit methods if limiting algebraic solutions are used to stabilize the numerical integration. The stabilizing algebra differs essentially for systems well-removed from equilibrium and those near equilibrium. Explicit asymptotic and quasi-steady-state methods that are appropriate when the system is only weakly equilibrated are examined first. These methods are then extended to the case of close approach to equilibrium through a new implementation of partial equilibrium approximations. Using stringent tests with astrophysical thermonuclear networks, evidence is provided that these methods can deal with the stiffest networks, even in the approach to equilibrium, with accuracy and integration timestepping comparable to that of implicit methods. Because explicit methods can execute a timestep faster and scale more favorably with network size than implicit algorithms, our results suggest that algebraically-stabilized explicit methods might enable integration of larger reaction networks coupled to fluid dynamics than has been feasible previously for a variety of disciplines. © 2012 Elsevier Inc.
Bassett D.R.,University of Tennessee at Knoxville
Physiological Measurement | Year: 2012
Measurement of physical activity is important, given the vital role of this behavior in physical and mental health. Over the past quarter of a century, the use of small, non-invasive, wearable monitors to assess physical activity has become commonplace. This review is divided into three sections. In the first section, a brief history of physical activity monitoring is provided, along with a discussion of the strengths and weaknesses of different devices. In the second section, recent applications of physical activity monitoring in physical activity and public health research are discussed. Wearable monitors are being used to conduct surveillance, and to determine the extent and distribution of physical activity and sedentary behaviors in populations around the world. They have been used to help clarify the dose-response relation between physical activity and health. Wearable monitors that provide feedback to users havealso been used in longitudinal interventions to motivate research participants and to assess their compliance with program goals. In the third section, future directions for research in physical activity monitoring are discussed. It is likely that new developments in wearable monitors will lead to greater accuracy and improved ease-of-use. © 2012 Institute of Physics and Engineering in Medicine.
Fronczak C.M.,Aurora University |
Kim E.D.,University of Tennessee at Knoxville |
Barqawi A.B.,Aurora University
Journal of Andrology | Year: 2012
One-third of infertile couples may have a male factor present. Illicit drug use can be an important cause of male factor infertility and includes use of anabolic-androgenic steroids, marijuana, opioid narcotics, cocaine, and methamphetamines. The use of these illicit drugs is common in the United States, with a yearly prevalence rate for any drug consistently higher in males compared with females. We aim to provide a review of recent literature on the prevalence and effects of illicit drug use on male fertility and to aid health professionals when counseling infertile men whose social history suggests illicit drug use. Anabolic-androgenic steroids, marijuana, cocaine, methamphetamines, and opioid narcotics all negatively impact male fertility, and adverse effects have been reported on the hypothalamic-pituitary-testicular axis, sperm function, and testicular structure. The use of illicit drugs is prevalent in our society and likely adversely impacting the fertility of men who abuse drugs. © American Society of Andrology.
Dalhaimer P.,University of Tennessee at Knoxville
Physical Biology | Year: 2013
One of the key questions in cell biology is how organelles are passed from parent to daughter cells. To help address this question, I used Brownian dynamics to simulate lipid droplets as model organelles in populations of dividing cells. Lipid droplets are dynamic bodies that can form both de novo and by fission, they can also be depleted. The quantitative interplay among these three events is unknown but would seem crucial for controlling droplet distribution in populations of dividing cells. Surprisingly, of the three main events studied: biogenesis, fission, and depletion, the third played the key role in maintaining droplet organelle number - and to a lesser extent volume - in populations of dividing cells where formation events would have seemed paramount. In the case of lipid droplets, this provides computational evidence that they must be sustained, most likely through contacts with the endoplasmic reticulum. The findings also agree with video microscopy experiments over much shorter timescales where droplet depletion in fission yeast cells was not observed. In general, this work shows that organelle maintenance is invaluable and lack thereof cannot necessarily be compensated for by organelle formation. This study provides a time-accurate, physical-based template for long-term cell division studies. © 2013 IOP Publishing Ltd.
Lane I.F.,University of Tennessee at Knoxville
Advances in Health Sciences Education | Year: 2010
Nontechnical competencies identified as essential to the health professional's success include ethical behavior, interpersonal, self-management, leadership, business, and thinking competencies. The literature regarding such diverse topics, and the literature regarding "professional success" is extensive and wide-ranging, crossing educational, psychological, business, medical and vocational fields of study. This review is designed to introduce ways of viewing nontechnical competence from the psychology of human capacity to current perspectives, initiatives and needs in practice. After an introduction to the tensions inherent in educating individuals for both biomedical competency and "bedside" or "cageside" manner, the paper presents a brief overview of the major lines of inquiry into intelligence theory and how theories of multiple intelligences can build a foundation for conceptualizing professional and life skills. The discussion then moves from broad concepts of intelligence to more specific workplace skill sets, with an emphasis on professional medical education. This section introduces the research on noncognitive variables in various disciplines, the growing emphasis on competency based education, and the SKA movement in veterinary education. The next section presents the evidence that nontechnical, noncognitive or humanistic skills influence achievement in academic settings, medical education and clinical performance, as well as the challenges faced when educational priorities must be made. © Springer Science+Business Media B.V. 2009.
Muday G.K.,Wake forest University |
Rahman A.,Iwate University |
Binder B.M.,University of Tennessee at Knoxville
Trends in Plant Science | Year: 2012
The individual roles of auxin and ethylene in controlling the growth and development of young seedlings have been well studied. In recent years, these two hormones have been shown to act synergistically to control specific growth and developmental processes, such as root elongation and root hair formation, as well as antagonistically in other processes, such as lateral root formation and hypocotyl elongation. This review examines the growth and developmental processes that are regulated by crosstalk between these two hormones and explores the mechanistic basis for the regulation of these processes. The emerging trend from these experiments is that ethylene modulates auxin synthesis, transport, and signaling with unique targets and responses in a range of tissues to fine-tune seedling growth and development. © 2012 Elsevier Ltd.
Inwood J.,University of Tennessee at Knoxville
Annals of the Association of American Geographers | Year: 2012
The Greensboro Truth and Reconciliation Commission (GTRC)-the first truth and reconciliation commission ever funded and seated in the United States-was formed in 2000 in response to a Ku Klux Klan shooting of labor activists that occurred in 1979 in Greensboro, North Carolina. Despite overwhelming video and photographic evidence of the Ku Klux Klan and American Nazi Party firing weapons into a crowd and killing five people, no one was ever held criminally liable for the deaths of the activists. In 1999 local community organizers began advocating for a truth and reconciliation process modeled after truth commissions in South Africa and Peru. In a broadly conceived qualitative approach that utilizes open-ended interviews and archival research, this project explores the truth process in Greensboro, focusing on the ways in which community members address legacies and memories of violence through reconciliation and grassroots politics. The research exposes the connections between the memory of violence and territoriality to wider academic scrutiny, examines the legacies of violence and race in North America, and contributes to larger discussions surrounding the impact that violence and race have in North American communities. © 2012 Copyright Taylor and Francis Group, LLC.
O'Bannon B.W.,University of Tennessee at Knoxville |
Thomas K.,Bellarmine University
Computers and Education | Year: 2014
This study examined the digital native-digital immigrant dichotomy based on the results of a study involving 1095 teachers from two states in the southeastern United States. The study focused on age as it relates to the relationship between the type of mobile phone they owned, their support for the use of mobile phones in the classroom, their perceptions of the benefits of specific mobile features for school-related work, and their perceptions of instructional barriers. The results indicated that the age of the teacher matters, however, not as suggested by Prensky (2001). There were no significant differences in the findings for the teachers who were less than 32 and the ones who were 33-49; however, they both significantly differed from those over 50 in mobile phone ownership and support for the use of mobile phones in the classroom as well as in their perceptions regarding the useful mobile features for school-related work and instructional barriers. In each instance, the older teachers were less likely to own smartphones, were less supportive on all items, were less enthusiastic about the features, and found the barriers to be more problematic.
Howell A.B.,Rutgers University |
D'Souza D.H.,University of Tennessee at Knoxville
Evidence-based Complementary and Alternative Medicine | Year: 2013
Pomegranates have been known for hundreds of years for their multiple health benefits, including antimicrobial activity. The recent surge in multidrug-resistant bacteria and the possibility of widespread global virus pandemics necessitate the need for additional preventative and therapeutic options to conventional drugs. Research indicates that pomegranates and their extracts may serve as natural alternatives due to their potency against a wide range of bacterial and viral pathogens. Nearly every part of the pomegranate plant has been tested for antimicrobial activities, including the fruit juice, peel, arils, flowers, and bark. Many studies have utilized pomegranate peel with success. There are various phytochemical compounds in pomegranate that have demonstrated antimicrobial activity, but most of the studies have found that ellagic acid and larger hydrolyzable tannins, such as punicalagin, have the highest activities. In some cases the combination of the pomegranate constituents offers the most benefit. The positive clinical results on pomegranate and suppression of oral bacteria are intriguing and worthy of further study. Much of the evidence for pomegranates' antibacterial and antiviral activities against foodborne pathogens and other infectious disease organisms comes from in vitro cell-based assays, necessitating further confirmation of in vivo efficacy through human clinical trials. © 2013 Amy B. Howell and Doris H. D'Souza.
Gerhold R.W.,University of Tennessee at Knoxville
Zoonoses and Public Health | Year: 2013
Free-roaming cat populations have been identified as a significant public health threat and are a source for several zoonotic diseases including rabies, toxoplasmosis, cutaneous larval migrans because of various nematode parasites, plague, tularemia and murine typhus. Several of these diseases are reported to cause mortality in humans and can cause other important health issues including abortion, blindness, pruritic skin rashes and other various symptoms. A recent case of rabies in a young girl from California that likely was transmitted by a free-roaming cat underscores that free-roaming cats can be a source of zoonotic diseases. Increased attention has been placed on trap-neuter-release (TNR) programmes as a viable tool to manage cat populations. However, some studies have shown that TNR leads to increased immigration of unneutered cats into neutered populations as well as increased kitten survival in neutered groups. These compensatory mechanisms in neutered groups leading to increased kitten survival and immigration would confound rabies vaccination campaigns and produce naïve populations of cats that can serve as source of zoonotic disease agents owing to lack of immunity. This manuscript is a review of the various diseases of free-roaming cats and the public health implications associated with the cat populations. © 2012 Blackwell Verlag GmbH.
Riechert S.E.,University of Tennessee at Knoxville
Animal Behaviour | Year: 2013
Maynard Smith & Parker (1976, Animal Behaviour, 24, 159-175) offered animal behaviourists and behavioural ecologists a theoretical framework/guide to understanding animal behaviour in competitive contexts. In this essay I trace the influence of this 'contest rule book' from the factors that led the two researchers to develop a treatise on the logic of the asymmetric game to empirical tests of the contest rules and theoretical additions made to the basic model and its underlying assumptions. Over a thousand studies cite this paper directly and thousands more cite work spurred by the original paper. The vast majority of these studies confirm the evolutionarily stable strategy (ESS) predictions made by Maynard Smith & Parker. Theoretical and empirical deviations from EES can largely be explained by the need for further structuring of the analyses into subgames and investigation of less obvious asymmetries than apparent size and resource value. To date, much progress has been made in three areas of interest to behaviourists: (1) understanding of the strategic nature of contests between conspecifics over limited resources; (2) modelling developments that deal with how information about potential asymmetries is gained; and (3) evaluation of the question of honest signalling with specific reference to threat displays. Here, I propose suggestions for future work, much of which will either require collaboration with mathematicians, or require that students interested in animal behaviour obtain a strong foundation in biomathematics. My preference is for the latter strategy. © 2013.
Wunderlich B.,University of Tennessee at Knoxville
Journal of Thermal Analysis and Calorimetry | Year: 2011
The first measurements in our laboratory of some 55 years ago dealt with adiabatic calorimetry of linear, semicrystalline polyethylene. Quickly it became obvious that time needed to be controlled to study the metastable and unstable states. Shortly thereafter, my first students were building our own DTA, capable to give quantitative, time-dependent calorimetric data. Only few years later, we could present the quantitative link between molecular motion and heat capacity in the melting and glass-transition regions. One of these students involved in this study was Prof. Michael Jaffe. His study dealt with semicrystalline polyoxymethylene, a synthetic carbohydrate. He could use the first quantitative commercial equipment and modify it to heating with rates of 100 K min -1 and more. Today, rates reaching up to 10 7 K min -1 and faster are available for the analysis of unstable and small phases. The key question of this beginning study on biopolymer-related materials is the title question of this presentation for this symposium. © 2011 Akadémiai Kiadó, Budapest, Hungary.
Jiang X.,University of Tennessee at Knoxville
Traffic injury prevention | Year: 2013
Previous studies of pavement management factors that relate to the occurrence of traffic-related crashes are rare. Traditional research has mostly employed summary statistics of bidirectional pavement quality measurements in extended longitudinal road segments over a long time period, which may cause a loss of important information and result in biased parameter estimates. The research presented in this article focuses on crash risk of roadways with overall fair to good pavement quality. Real-time and location-specific data were employed to estimate the effects of pavement management factors on the occurrence of crashes. This research is based on the crash data and corresponding pavement quality data for the Tennessee state route highways from 2004 to 2009. The potential temporal and spatial correlations among observations caused by unobserved factors were considered. Overall 6 models were built accounting for no correlation, temporal correlation only, and both the temporal and spatial correlations. These models included Poisson, negative binomial (NB), one random effect Poisson and negative binomial (OREP, ORENB), and two random effect Poisson and negative binomial (TREP, TRENB) models. The Bayesian method was employed to construct these models. The inference is based on the posterior distribution from the Markov chain Monte Carlo (MCMC) simulation. These models were compared using the deviance information criterion. Analysis of the posterior distribution of parameter coefficients indicates that the pavement management factors indexed by Present Serviceability Index (PSI) and Pavement Distress Index (PDI) had significant impacts on the occurrence of crashes, whereas the variable rutting depth was not significant. Among other factors, lane width, median width, type of terrain, and posted speed limit were significant in affecting crash frequency. The findings of this study indicate that a reduction in pavement roughness would reduce the likelihood of traffic-related crashes. Hence, maintaining a low level of pavement roughness is strongly suggested. In addition, the results suggested that the temporal correlation among observations was significant and that the ORENB model outperformed all other models.
Li H.,University of Tennessee at Knoxville
Eurasip Journal on Wireless Communications and Networking | Year: 2010
An Aloha-like spectrum access scheme without negotiation is considered for multiuser and multichannel cognitive radio systems. To avoid collisions incurred by the lack of coordination, each secondary user learns how to select channels according to its experience. Multiagent reinforcement leaning (MARL) is applied for the secondary users to learn good strategies of channel selection. Specifically, the framework of Q -learning is extended from single user case to multiagent case by considering other secondary users as a part of the environment. The dynamics of the Q -learning are illustrated using a Metrick-Polak plot, which shows the traces of Q -values in the two-user case. For both complete and partial observation cases, rigorous proofs of the convergence of multiagent Q -learning without communications, under certain conditions, are provided using the Robins-Monro algorithm and contraction mapping, respectively. The learning performance (speed and gain in utility) is evaluated by numerical simulations. Copyright © 2010 Husheng Li.
Li Y.-K.,University of Tennessee at Knoxville
Journal of Mountain Science | Year: 2013
Topographic shielding of cosmic radiation flux is a key parameter in using cosmogenic nuclides to determine surface exposure ages or erosion rates. Traditionally, this parameter is measured in the field and uncertainty and/or inconsistency may exist among different investigators. This paper provides an ArcGIS python code to determine topographic shielding factors using digital elevation models (DEMs). This code can be imported into ArcGIS as a geoprocessing tool with a user-friendly graphical interface. The DEM-derived parameters using this method were validated with field measurements in central Tian Shan. Results indicate that DEM-derived shielding factors are consistent with field-measured values. It provides a valuable tool to save fieldwork efforts and has the potential to provide consistent results for different regions in the world to facilitate the comparison of cosmogenic nuclide results. © 2013 Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg.
Zhu X.,University of Tennessee at Knoxville |
Yao Q.,Revenue Analytics Inc.
Bioresource Technology | Year: 2011
It is technologically possible for a biorefinery to use a variety of biomass as feedstock including native perennial grasses (e.g., switchgrass) and agricultural residues (e.g., corn stalk and wheat straw). Incorporating the distinct characteristics of various types of biomass feedstocks and taking into account their interaction in supplying the bioenergy production, this paper proposed a multi-commodity network flow model to design the logistics system for a multiple-feedstock biomass-to-bioenergy industry. The model was formulated as a mixed integer linear programming, determining the locations of warehouses, the size of harvesting team, the types and amounts of biomass harvested/purchased, stored, and processed in each month, the transportation of biomass in the system, and so on. This paper demonstrated the advantages of using multiple types of biomass feedstocks by comparing with the case of using a single feedstock (switchgrass) and analyzed the relationship of the supply capacity of biomass feedstocks to the output and cost of biofuel. © 2011 Elsevier Ltd.
Egami T.,University of Tennessee at Knoxville |
Egami T.,Oak Ridge National Laboratory
Journal of Alloys and Compounds | Year: 2011
The current majority view on the phenomenon of mechanical failure in metallic glasses appears to be that it is caused by the activity of some structural defects, such as free-volumes or shear transformation zones, and the concentration of such defects is small, only of the order of 1%. However, the recent results compel us to revise this view. Through molecular dynamics simulation it has been shown that mechanical failure is the stress-induced glass transition. According to our theory the concentration of the liquid-like sites (defects) is well over 20% at the glass transition. We suggest that the defect concentration in metallic glasses is actually very high, and percolation of such defects causes atomic avalanche and mechanical failure. In this article we discuss the glass transition, mechanical failure and viscosity from such a point of view. © 2010 Elsevier B.V. All rights reserved.
Simberloff D.,University of Tennessee at Knoxville
Ecological Engineering | Year: 2014
Recent critics of the effort to control biological invasions argue that the extent of the damage they cause is overblown or that, whatever the damage, the effort to control them is largely futile. The best-known invasion impacts - predation, herbivory, competition, parasitism, and hybridization - are at the population level and are joined by myriad other, more idiosyncratic impacts. Many of these impose staggering ecological, economic, and public health costs and are surely worth combating. Although major effects are not yet known for the majority of established introduced species, three facts suggest that many more impacts will ultimately be detected. First, only a small minority of introduced populations have been studied in detail. Second, some substantial impacts are subtle and have become evident only after intensive research, often at the ecosystem level. Third, an invasion debt exists, such that some introduced populations remain innocuous for an extended period before rapidly growing and spreading to become highly invasive. Many invasive populations have been eradicated or successfully managed at low levels, and technological advances have increased the range of invasions that can be attacked successfully. An effective early-warning, rapid-response system would greatly facilitate eradication of invaders and could be aided by organizing citizen volunteers and publicizing standard reporting procedures. For all these reasons, permitting new introductions should be done with great caution, and introductions detected quickly, before the species has spread widely, should be targeted for eradication if a feasible method can be identified. In the absence of eradication, maintenance of many invasive populations at low levels has proven possible by biological control, chemical control, and physical or mechanical control. New approaches from allied fields promise an even wider range of management possibilities. However, managing long-established invaders should be considered on a case-by-case basis, and in some cases ecological or social concerns may argue against management. © 2013 Elsevier B.V.
Sehrawat S.,University of Tennessee at Knoxville
PLoS pathogens | Year: 2010
In this communication, we demonstrate that galectin (Gal)-9 acts to constrain CD8(+) T cell immunity to Herpes Simplex Virus (HSV) infection. In support of this, we show that animals unable to produce Gal-9, because of gene knockout, develop acute and memory responses to HSV that are of greater magnitude and better quality than those that occur in normal infected animals. Interestingly, infusion of normal infected mice with alpha-lactose, the sugar that binds to the carbohydrate-binding domain of Gal-9 limiting its engagement of T cell immunoglobulin and mucin (TIM-3) receptors, also caused a more elevated and higher quality CD8(+) T cell response to HSV particularly in the acute phase. Such sugar treated infected mice also had expanded populations of effector as well as memory CD8(+) T cells. The increased effector T cell responses led to significantly more efficient virus control. The mechanisms responsible for the outcome of the Gal-9/TIM-3 interaction in normal infected mice involved direct inhibitory effects on TIM-3(+) CD8(+) T effector cells as well as the promotion of Foxp3(+) regulatory T cell activity. Our results indicate that manipulating galectin signals, as can be achieved using appropriate sugars, may represent a convenient and inexpensive approach to enhance acute and memory responses to a virus infection.
Truster T.J.,University of Tennessee at Knoxville
Computational Mechanics | Year: 2016
A heterogeneous interface method is developed for combining primal displacement and mixed displacement-pressure formulations across nonconforming finite element meshes to treat volume-preserving plastic flow. When the zone of inelastic response is localized within a larger domain, significant computational savings can be achieved by confining the mixed formulation solely to the localized region. The method’s distinguishing feature is that the coupling terms for joining dissimilar element types are derived from a time-discrete free energy functional, which is based on a Lagrange multiplier formulation of the interface constraints. Incorporating residual-based stabilizing terms at the interface enables the condensation of the multiplier field, leading to a symmetric Nitsche formulation in which the interface operators respect the differing character of the governing equations in each region. In a series of numerical problems, the heterogeneous interface method achieved comparable results on coarser meshes as those obtained from applying the mixed formulation throughout the domain. © 2015, Springer-Verlag Berlin Heidelberg.
Elder T.,U.S. Department of Agriculture |
Beste A.,University of Tennessee at Knoxville
Energy and Fuels | Year: 2014
Studies on the pyrolysis mechanisms of lignin model compounds have largely focused on initial homolytic cleavage reactions. It has been noted, however, that concerted mechanisms may also account for observed product formation. In the current work, the latter processes are examined and compared to the former, by the application of density functional theory calculations to fully substituted lignin models. Results show that activation energies for the concerted reactions are somewhat lower than the bond dissociation energies of the homolysis reactions. Kinetic analysis revealed that the concerted pathway is the retro-ene fragmentation mechanism. © 2014 American Chemical Society.
Smith S.A.,University of Michigan |
O'Meara B.C.,University of Tennessee at Knoxville
Bioinformatics | Year: 2012
Ever larger phylogenies are being constructed due to the explosion of genetic data and development of high-performance phylogenetic reconstruction algorithms. However, most methods for calculating divergence times are limited to datasets that are orders of magnitude smaller than recently published large phylogenies. Here, we present an algorithm and implementation of a divergence time method using penalized likelihood that can handle datasets of thousands of taxa. We implement a method that combines the standard derivative-based optimization with a stochastic simulated annealing approach to overcome optimization challenges. We compare this approach with existing software including r8s, PATHd8 and BEAST. © The Author 2012. Published by Oxford University Press. All rights reserved.
Moran E.V.,University of Tennessee at Knoxville |
Willis J.,Duke University |
Clark J.S.,Duke University
American Journal of Botany | Year: 2012
Premise of the study: Hybridization is pervasive in many plant taxa, with consequences for species taxonomy, local adaptation, and management. Oaks (Quercus spp.) are thought to hybridize readily yet retain distinct traits, drawing into question the biological species concept for such taxa, but the true extent of gene flow is controversial. Genetic data are beginning to shed new light on this issue, but red oaks (section Lobatae), an important component of North American forests, have largely been neglected. Moreover, gene flow estimates may be sensitive to the choice of life stage, marker type, or genetic structure statistic. Methods: We coupled genetic structure data with parentage analyses for two mixed-species stands in North Carolina. Genetic structure analyses of adults (including FST, RST, G'ST, and STRUCTURE) reflect long-term patterns of gene flow, while the percentage of seedlings with parents of two different species reflect current levels of gene flow. Key results: Genetic structure analyses revealed low differentiation in microsatellite allele frequencies between co-occurring species, suggesting past gene flow. However, methods differed in their sensitivity to differentiation, indicating a need for caution when drawing conclusions from a single method. Parentage analyses identifed > 20% of seedlings as potential hybrids. The species examined exhibit distinct morphologies, suggesting selection against intermediate phenotypes. Conclusions: Our results suggest that hybridization between co-occurring red oaks occurs, but that selection may limit introgression, especially at functional loci. However, by providing a source of genetic variation, hybridization could influence the response of oaks and other hybridizing taxa to environmental change. © 2012 Botanical Society of America.
Wunderlich B.,University of Tennessee at Knoxville
Journal of Thermal Analysis and Calorimetry | Year: 2010
Phases may be smaller than visible to the human eye. In order to characterize a microphase, a phase smaller than 1 μm, one must consider surface area and free energy in addition to the standard thermodynamic functions. As one approaches nanometer sizes, one also needs to know the changing thermodynamic functions within the phases. The Gibbs-Thomson equation can be used to characterize microphases, but not nanophases. For the latter, the glass transition is needed to assess the properties in the interior. In order to classify condensed phases as liquid, solid, mesophase, or crystal, one needs to consider the molecular motion in addition to the molecular structure. Most important are large-amplitude displacements in form of translation, rotation, and conformational motion. An operational definition based on experiments and an updated classification of the phases is given. The surprising result is the observation that crystals, earlier assumed prime examples of solids, can have order-disorder transitions to more mobile mesophases, as well as a glass transition without change in crystal structure, i.e., under certain condition, they cannot be identified as a solid. To these observations, one has to add the fact that large-amplitude motion may start gradually to a more mobile phase without abrupt changes in structure. These observations limit the usefulness of the 80-year-old classification of transitions as being of first or second order. Quantitative thermal analysis is shown to be an important tool to identify the possible total of 57 different condensed states in terms of their macroscopic properties as well as molecular structure and motion. © 2010 Akadémiai Kiadó, Budapest, Hungary.
Weisensee K.E.,Clemson University |
Jantz R.L.,University of Tennessee at Knoxville
American Journal of Physical Anthropology | Year: 2011
This study examines patterns of secular change in cranial morphology in the New Lisbon collection, a documented skeletal collection from Lisbon, Portugal with birth years from 1806 to 1954. This period represents a time when Lisbon was undergoing increased urbanization and population growth, as well as changes in mortality and fertility patterns. Previous studies from the U.S., Europe, and Japan have reported significant secular changes in cranial morphology over the past 200 years. In the current study, secular changes were analyzed using three-dimensional geometric morphometrics methods. The results from this study demonstrate a significant change in cranial morphology over the roughly 150-year period. Allometry was rejected as a causal factor of this change because there was no association found between temporal change and size. The pattern of temporal change is similar to that observed in other populations in the U.S., Europe, and Japan, including decreased facial breadth and a more inferiorly placed cranial base. This study, along with previous research, suggests a similar pattern of change occurs in genetically and geographically diverse populations experiencing modern environmental conditions. We argue that because the secular changes are focused in the cranial base, a region of the skull that experiences a relatively early growth curve, changes related to declines in childhood morbidity and mortality are likely important factors related to the observed changes. Copyright © 2011 Wiley-Liss, Inc.
Simberloff D.,University of Tennessee at Knoxville
American Midland Naturalist | Year: 2010
Impacts of biological invasions on recipient plant communities vary enormously, depending on both the traits of the introduced species and those of its new ecosystem. The trajectories of many introduced plant species in invaded ecosystems seem very similar to those taken by native plants as part of secondary succession. It is likely that studying them in the framework of modern succession ecology would be fruitful. Other introduced species of plants, animals and pathogens cause massive, rapid and often irreversible changes in the recipient communities, of a magnitude rarely produced by native species. Understanding such invasions, and the great range of impacts caused by introduced species, will probably require at least some approaches different from those of other sciences of vegetation change. Although invasion biology has been somewhat dissociated from other research on vegetation change, at least a partial rapprochement is underway, and, in any event, it is not evident that understanding of invasions has been retarded by the dissociation. Research on plant invasions has already contributed greatly to recent progress in understanding the determinants of community structure and function, as well as to many other areas of ecology. The rapidly increasing number of communities composed wholly or largely of introduced species would seem to be an ideal probe into questions about the nature of plant communities and the forces molding them, but they have barely been exploited in this regard. Invasion biology has not produced powerful general laws, but neither has community ecology as a whole. This fact does not indicate that they are weak sciences, only that any laws in these fields will probably be local, contingent patterns because of the complexity and idiosyncrasies of biological communities.
Gardner R.M.,Dominion |
Liu Y.,University of Tennessee at Knoxville
IEEE Transactions on Smart Grid | Year: 2012
Using data from high-resolution wide-area GPS-synchronized measurements to detect and analyze disturbances within a synchronous electrical interconnection is not trivial. Deterministic methods often fall prey to the non-stationary noisy nature of this type of data. This paper dwells on the location of noteworthy events within blue-sky ambient data taken from particularly noisy environments. The statistical processing used to detect and analyze power system events is congealed into a concise and tunable algorithm that is applicable to a multitude of data types. The data analyzed herein is drawn from FNET, a wide-area measurement system deployed worldwide at standard end-user distribution voltages. © 2011 IEEE.
Truster T.J.,University of Tennessee at Knoxville
Engineering Fracture Mechanics | Year: 2016
An algorithm is summarized for inserting zero-thickness interface elements or "couplers" into finite element meshes in two and three dimensions. Using only element connectivity, couplers are inserted according to regions within the analysis domain, a geometrically intuitive means to designate their locations. A wide class of volume elements and interface couplers are treated. A three-dimensional test case verifies that the algorithm generates meshes passing the patch test. © 2015 Elsevier Ltd.
Bilal D.,University of Tennessee at Knoxville
Journal of the American Society for Information Science and Technology | Year: 2012
This study employed benchmarking and intellectual relevance judgment in evaluating Google, Yahoo!, Bing, Yahoo! Kids, and Ask Kids on 30 queries that children formulated to find information for specific tasks. Retrieved hits on given queries were benchmarked to Google's and Yahoo! Kids' top-five ranked hits retrieved. Relevancy of hits was judged on a graded scale; precision was calculated using the precision-at-ten metric (P@10). Yahoo! and Bing produced a similar percentage in hit overlap with Google (nearly 30%), but differed in the ranking of hits. Ask Kids retrieved 11% in hit overlap with Google versus 3% by Yahoo! Kids. The engines retrieved 26 hits across query clusters that overlapped with Yahoo! Kids' top-five ranked hits. Precision (P) that the engines produced across the queries was P = 0.48 for relevant hits, and P = 0.28 for partially relevant hits. Precision by Ask Kids was P = 0.44 for relevant hits versus P = 0.21 by Yahoo! Kids. Bing produced the highest total precision (TP) of relevant hits (TP = 0.86) across the queries, and Yahoo! Kids yielded the lowest (TP = 0.47). Average precision (AP) of relevant hits was AP = 0.56 by leading engines versus AP = 0.29 by small engines. In contrast, average precision of partially relevant hits was AP = 0.83 by small engines versus AP = 0.33 by leading engines. Average precision of relevant hits across the engines was highest on two-word queries and lowest on one-word queries. Google performed best on natural language queries; Bing did the same (P = 0.69) on two-word queries. The findings have implications for search engine ranking algorithms, relevance theory, search engine design, research design, and information literacy. © 2012 ASIS&T.
Snijders P.C.,Oak Ridge National Laboratory |
Weitering H.H.,Oak Ridge National Laboratory |
Weitering H.H.,University of Tennessee at Knoxville
Reviews of Modern Physics | Year: 2010
Many quasi-one-dimensional (1D) materials are experimental approximations to the textbook models of Peierls instabilities and collective excitations in 1D electronic systems. The recently observed self-assembly of atom wires on solid surfaces has provided fascinating new insights into the nature of their structural and electronic instabilities, from both real-space and momentum-space perspectives. In this Colloquium, three of the most studied atom wire arrays are highlighted, all featuring multiple surface-state bands. One of these is made of indium atoms on a flat silicon (111) surface, while the two others consist of gold atoms on surfaces that are vicinal to Si(111). The experimental and theoretical results are discussed with a focus on the detailed mechanisms of the observed phase transitions and on the role of microscopic defects. © 2010 The American Physical Society.
Zhang H.,Tuskegee University |
Tolbert L.M.,University of Tennessee at Knoxville |
Tolbert L.M.,Oak Ridge National Laboratory
IEEE Transactions on Industrial Electronics | Year: 2011
Power electronics is an enabling technology found in most renewable energy generation systems. Because of its superior voltage blocking capabilities and fast switching speeds, silicon carbide (SiC) power electronics are considered for use in power conversion units in wind generation systems in this paper. The potential efficiency gains from the use of SiC devices in a wind generation system are explored by simulations, with the system modeling explained in detail. The performance of the SiC converter is analyzed and compared to its silicon counterpart at different wind speeds, temperatures, and switching frequencies. The quantitative results are based on SiC metaloxidesemiconductor field-effect transistor (MOSFET) prototypes from Cree and modern Si insulated-gate bipolar transistor (IGBT) products. A conclusion is drawn that the SiC converters can improve the wind system power conversion efficiency and can reduce the system's size and cost due to the low-loss, high-frequency, and high-temperature properties of SiC devices, even for one-for-one replacement for Si devices. © 2006 IEEE.
Fowlkes J.D.,Oak Ridge National Laboratory |
Rack P.D.,Oak Ridge National Laboratory |
Rack P.D.,University of Tennessee at Knoxville
ACS Nano | Year: 2010
Unknown parameters critical to understanding the electron-precursor- substrate interactions during electron-beam-induced deposition (EBID) have long limited our ability to fully control this nanoscale, directed assembly method. We report here values that describe the precursor-solid interaction, the precursor surface diffusion coefficient (D), the precursor sticking probability (δ), and the mean precursor surface residence time (τ), which are critical parameters for understanding the assembly of EBID deposits. Values of D = 6.4 μm2 s-1, δ = 0.0250, and τ = 3.20 ms were determined for a commonly used precursor molecule, tungsten hexacarbonyl W(CO)6. Space and time predictions of the adsorbed precursor coverage were solved by an explicit finite differencing numerical scheme. Evolving nanopillar surface morphology was derived from simulations considering electron-induced dissociation as the critical depletion term. This made it possible to infer the spaceand time-dependent precursor coverage both on and around nanopillar structures to better understand local precursor dynamics during mass-transport-limited (MTL) and reaction-rate-limited (RRL) EBID. © 2010 American Chemical Society.
Varga M.A.,University of West Georgia |
Paulus T.M.,University of Tennessee at Knoxville
Death Studies | Year: 2014
Research into peer conversations in online grief support groups remains scarce. The authors used discourse analysis to examine 107 initial posts to one such group to examine how newcomers constructed their initial posts to display their eligibility for membership. The authors identified three discursive features: formulating unusual stories of loss, describing uncontrollable emotional and physical states, and engaging in "troubles telling." These discursive patterns illustrate how grief is constructed in ways that may simultaneously conform to and resist norms around grief that exist offline. Implications for practitioners include the need to support individuals through validation of their "nonnormal" grief. © 2014 Copyright Taylor & Francis Group, LLC.
Bozell J.J.,University of Tennessee at Knoxville |
Petersen G.R.,U.S. Department of Energy
Green Chemistry | Year: 2010
A biorefinery that supplements its manufacture of low value biofuels with high value biobased chemicals can enable efforts to reduce nonrenewable fuel consumption while simultaneously providing the necessary financial incentive to stimulate expansion of the biorefining industry. However, the choice of appropriate products for addition to the biorefinery's portfolio is challenged by a lack of broad-based conversion technology coupled with a plethora of potential targets. In 2004, the US Department of Energy (DOE) addressed these challenges by describing a selection process for chemical products that combined identification of a small group of compounds derived from biorefinery carbohydrates with the research and technology needs required for their production. The intent of the report was to catalyze research efforts to synthesize multiple members of this group, or, ideally, structures not yet on the list. In the six years since DOE's original report, considerable progress has been made in the use of carbohydrates as starting materials for chemical production. This review presents an updated evaluation of potential target structures using similar selection methodology, and an overview of the technology developments that led to the inclusion of a given compound. The list provides a dynamic guide to technology development that could realize commercial success through the proper integration of biofuels with biobased products. © 2010 The Royal Society of Chemistry.
Bose B.K.,University of Tennessee at Knoxville
IEEE Industrial Electronics Magazine | Year: 2010
Energy and environment, particularly the global warming problem due to man-made greenhouse gases (GHGs), appear to be such a serious concern in our society that almost everybody in the world today is talking about it. The 2007 Nobel Peace Prize was awarded to the United Nations - Intergovernmental Panel of Climate Change (IPCC) along with the former U.S. Vice President Al Gore for their contributions to global warming. There is no doubt that energy has been the lifeblood in the evolution of our industrial civilization, and per capita energy consumption has been the barometer of a nation's prosperity. In the old days of the preindustrial revolution era, as indicated in Figure 1, mankind was mainly dependent on animal and manual labor. In this muscle age, our life style was very simple and unsophisticated, and the environment was clean. In 1785, James Watt of Scotland invented the steam engine that ushered in the Industrial Revolution, and we were brought into the mechanical age or age of machines. The Industrial Revolution gained momentum by the invention of internal combustion engine in the late 19th century. The wave of the Industrial Revolution gradually spread from Europe to the United States, and then to the rest of the world. The electrical revolution or electrical age started by the commercial availability of electricity in the mid-1880s, when at the same time, the commercial induction motor was invented (1888) by Nickola Tesla. The commercial dc motor was introduced at a slightly earlier date (1873), and then the synchronous motor arrived at a slightly later date (1891). The electronics revolution or the age of modern solid-state electronics was ushered in by the invention of the transistor in 1948 by Bardeen, Brattain, and Shockley of Bell Laboratories. Bell Laboratories also invented the thyristor (called the PNPN triggering transistor) in 1956, and then the thyristor (or silicon controlled rectifier) was commercially introduced by General Electric (GE) in 1958. This brought us to the modern age of solid-state power electronics. We often say that invention of the transistor brought in the first electronics revolution, whereas the invention of the thyristor brought in the second electronics revolution. Gradually, the eras of integrated circuits, computers, communication, and robotics arrived. We now live in an Internet age that shrank the world into a global village. Human society is now more interdependent than ever. During the mechanical, electrical, and electronics ages, the energy consumption in the world has grown by leaps and bounds to cater the need of growing world population and improvement of our standard of living. So far, we have hardly paid much attention to the adverse effect of energy consumption, i.e., environmental pollution. © IEEE.
Farahi R.H.,Oak Ridge National Laboratory |
Passian A.,Oak Ridge National Laboratory |
Passian A.,University of Tennessee at Knoxville |
Tetard L.,Oak Ridge National Laboratory |
Thundat T.,University of Alberta
ACS Nano | Year: 2012
Figure Persented: The stability of food and water supplies is widely recognized as a global issue of fundamental importance. Sensor development for food and water safety by nonconventional assays continues to overcome technological challenges. The delicate balance between attaining adequate limits of detection, chemical fingerprinting of the target species, dealing with the complex food matrix, and operating in difficult environments are still the focus of current efforts. While the traditional pursuit of robust recognition methods remains important, emerging engineered nanomaterials and nanotechnology promise better sensor performance but also bring about new challenges. Both advanced receptor-based sensors and emerging non-receptor-based physical sensors are evaluated for their critical challenges toward out-of-laboratory applications. © 2012 American Chemical Society.
Nolt J.,University of Tennessee at Knoxville
Environmental Values | Year: 2013
Concern with ethical anthropocentrism has largely been confined to debates in animal and environmental ethics. Philosophers generally have shown little interest in it. Ethical egoism, by contrast, though usually rejected, has sparked wide philosophical interest. This is surprising, for the two are akin; anthropocentrism is egoism writ large - the egoism of the human species. This paper explains the kinship by articulating this analogy, shows that the analogy provides for each argument for or against ethical egoism an analogous argument for or against ethical anthropocentrism, and demonstrates the analogy's fruitfulness by using it to extrapolate from an existing argument against ethical egoism a novel argument against ethical anthropocentrism. © 2013 The White Horse Press.
Spradley M.K.,Texas State University |
Jantz R.L.,University of Tennessee at Knoxville
Journal of Forensic Sciences | Year: 2011
When the pelvis is unavailable, the skull is widely considered the second best indicator of sex. The goals of this research are to provide an objective hierarchy of sexing effectiveness of cranial and postcranial elements and to test the widespread notion that the skull is superior to postcranial bones. We constructed both univariate and multivariate discriminant models using data from the Forensic Anthropology Data Bank. Discriminating effectiveness was assessed by cross-validated classification, and in the case of multivariate models, Mahalanobis D 2. The results clearly indicate that most postcranial elements outperform the skull in estimating sex. It is possible to correctly sex 88-90% of individuals with joint size, up to 94% with multivariate models of the postcranial bones. The best models for the cranium do not exceed 90%. We conclude that postcranial elements are to be preferred to the cranium for estimating sex when the pelvis is unavailable. © 2011 American Academy of Forensic Sciences.
Schoenborn W.A.,George Washington University |
Fedo C.M.,University of Tennessee at Knoxville
Chemical Geology | Year: 2011
Petrologic and geochemical data confirm that mudstones and sandstones of the Johnnie Formation were the initial siliciclastic deposits laid along the Cordilleran Laurentian margin following the Neoproterozoic break-up of Rodinia. Sedimentary rocks of the Johnnie Formation have corrected CIA values between 63 and 83 (or higher), which suggest moderate to intense weathering of crystalline source rocks or recycling. Based on modeling the fresh source rocks likely consisted of 90% granodiorite and 10% high-K granite. This conclusion is based on petrographic observations, major element geochemistry, and investigation of the REE: (LaCN/SmCN=4.19±1.26, GdCN/YbCN=1.34±0.38, Eu/Eu*=0.63±0.09 and LaCN/YbCN=9.55±2.27). Feldspars are unevenly distributed in the finer grained sedimentary rocks. Observed fluctuations in feldspar content throughout the Johnnie Formation are interpreted as a result of abrasion and hydrodynamic sorting, which concentrated feldspars in the finer grained sediment. None of the mudstone samples, including those collected just below and above the flat-pebble conglomerate in the upper Johnnie Formation, show evidence of true cold weather depositional conditions. Consequently, Johnnie Formation mudstone geochemistry does not record evidence of an extreme paleoclimatic environmental shift in the succession. Textural characteristics of Johnnie Formation sandstones are consistent with quiescent tectonic conditions characterized by low relief, and deposition of Johnnie Formation strata in a passive-margin setting. © 2011.
Raynor H.A.,University of Tennessee at Knoxville
Physiology and Behavior | Year: 2012
Due to the high prevalence of overweight and obesity, developing strategies to improve weight loss and weight loss maintenance is imperative. One dietary environmental variable that has received little attention in being targeted in an intervention to assist with obesity treatment is dietary variety. Experimental research has consistently shown that greater dietary variety increases consumption, with the effect of variety on consumption hypothesized to be a consequence of the differential experience of the more varied sensory properties of food under those conditions with greater dietary variety. As reduced energy intake is required for weight loss, limiting variety, particularly in food groups that are high in energy-density and low in nutrient-density, may assist with reducing energy intake and improving weight loss. A series of investigations, both observational and experimental, were conducted to examine if limiting variety in an energy-dense, non-nutrient-dense food group, snack foods (i.e., cookies, chips), assisted with reducing energy intake of the food group and improving weight loss. Results of the investigations suggest that a prescription for limiting variety in a food group can be implemented during obesity treatment, limiting variety is associated with the occurrence of monotony, and that reducing food group variety is related to decreased consumption of that food group. Future research is needed to ascertain the long-term effect of prescriptions targeting dietary variety on weight loss and weight loss maintenance. © 2012 Elsevier Inc.
Roseman C.C.,Urbana University |
Auerbach B.M.,University of Tennessee at Knoxville
Journal of Human Evolution | Year: 2015
Genetic resemblances among groups are non-randomly distributed in humans. This population structure may influence the correlations between traits and environmental drivers of natural selection thus complicating the interpretation of the fossil record when modern human variation is used as a referential model. In this paper, we examine the effects of population structure and natural selection on postcranial traits that reflect body size and shape with application to the more general issue of how climate - using latitude as a proxy - has influenced hominin morphological variation. We compare models that include terms reflecting population structure, ascertained from globally distributed microsatellite data, and latitude on postcranial phenotypes derived from skeletal dimensions taken from a large global sample of modern humans. We find that models with a population structure term fit better than a model of natural selection along a latitudinal cline in all cases. A model including both latitude and population structure terms is a good fit to distal limb element lengths and bi-iliac breadth, indicating that multiple evolutionary forces shaped these morphologies. In contrast, a model that included only a population structure term best explained femoral head diameter and the crural index. The results demonstrate that population structure is an important part of human postcranial variation, and that clinally distributed natural selection is not sufficient to explain among-group differentiation. The distribution of human body form is strongly influenced by the contingencies of modern human origins, which calls for new ways to approach problems in the evolution of human variation, past and present. © 2014 Elsevier Ltd.
McCall A.C.,Denison University |
Fordyce J.A.,University of Tennessee at Knoxville
Journal of Ecology | Year: 2010
1. The optimal defence theory (ODT) of chemical defence provides a predictive framework for the distribution of anti-herbivore defences in plants. One of its predictions is that chemical defences will be allocated within a plant as a function of tissue value, where value is correlated with the cost of having that tissue removed. While many studies have examined intra-plant variation in defence chemistry, these results have rarely been compiled quantitatively to assess whether defence allocation is consistent with the prediction of ODT that more valuable tissues should be more defended than less valuable tissues. 2. We performed a formal meta-analysis of published and unpublished studies to examine the predictive utility of ODT. Specifically, we examined whether defence chemicals occur at higher concentrations in flowers versus leaves and in younger leaves compared to older leaves, under the assumption that younger leaves are more valuable than older leaves. We also examined whether the expansion status of younger leaves, nodal position of the leaves, growing conditions and chemical class of defence compounds affected the mean effect sizes. 3. We found that tissues with higher assumed value had significantly higher concentrations of defence chemicals than tissues with lower value. In particular, we found that younger leaves had higher concentrations of defence chemicals than older leaves, consistent with the predictions of ODT. The magnitude of this difference was higher in the younger leaf/older leaf comparison than in the flower/leaf comparison, with no evidence that flowers were more defended than leaves. The overall results were not affected by chemical class, young leaf expansion status, growing conditions or leaf position on the plant. 4. Synthesis. We found general agreement between the predictions of ODT and the intraplant distribution of chemical defence and conclude it is a useful model. The effect size varied depending on the tissue compared. Explicit measures of tissue value, in particular as it relates to relative fitness, are required to further validate the predictive utility and general applicability of ODT. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.
Naber J.,219 Mason Hall |
Wyatt T.H.,University of Tennessee at Knoxville
Nurse Education Today | Year: 2014
Background: The importance of critical thinking is well-documented by the American Association of Colleges of Nursing and the National League for Nursing. Reflective writing is often used to increase understanding and analytical ability. The lack of empirical evidence about the effect of reflective writing interventions on critical thinking supports the examination of this concept. Objectives: Study objectives were: •To test the effectiveness of a novel reflective writing intervention, based on Paul's (1993) model of critical thinking, for improving critical thinking skills and dispositions in nursing students.•To determine the common characteristics of high-scoring participants.•To determine relationships between scores and institution, gender, age, ethnicity, or experience. Design: This study used an experimental, pretest-posttest design. Settings: The setting was two schools of nursing at universities in the southern United States. Participants: The convenience sample included 70 fourth-semester students in baccalaureate nursing programs. Methods: Randomly assigned control and experimental groups completed the California Critical Thinking Skills Test (CCTST) and the California Critical Thinking Dispositions Inventory Test (CCTDI). The experimental group completed six reflective writing assignments. Both groups completed the two tests again. Results: Results showed that the experimental group had a significant increase (p. = 0.03) on the truthseeking subscale of the CCTDI when compared to the control group. The experimental group's scores increased on four CCTST subscales and were higher than the control group's on three CCTST subscales. Conclusions: The results of this study make it imperative for nursing schools to consider including reflective writing-especially assignments based on Paul's (1993) model-in nursing courses. If future studies, testing over longer periods of time, show significant increases in critical thinking, those interventions could be incorporated into nursing curriculum and change the way nurse educators evaluate students. © 2013 Elsevier Ltd.
Fitzpatrick B.M.,University of Tennessee at Knoxville
Frontiers in Microbiology | Year: 2014
Symbiotes can be transmitted from parents to offspring or horizontally from unrelated hosts or the environment. A key question is whether symbiote transmission is similar enough to Mendelian gene transmission to generate and maintain coevolutionary associations between host and symbiote genes. Recent papers come to opposite conclusions, with some suggesting that any horizontal transmission eliminates genetic association. These studies are hard to compare owing to arbitrary differences in modeling approach, parameter values, and assumptions about selection. I show that associations between host and symbiote genes (extra-genomic associations) can be described by the same dynamic model as conventional linkage disequilibria between genes in the same genome. Thus, covariance between host and symbiote genomes depends on population history, geographic structure, selection, and co-transmission rate, just as covariance between genes within a genome. The conclusion that horizontal transmission rapidly erodes extra-genomic associations is equivalent to the conclusion that recombination rapidly erodes associations between genes within a genome. The conclusion is correct in the absence of population structure or selection. However, population structure can maintain spatial associations between host and symbiote traits, and non-additive selection (interspecific epistasis) can generate covariances between host and symbiote genotypes. These results can also be applied to cultural or other non-genetic traits. This work contributes to a growing consensus that genomic, symbiotic, and gene-culture evolution can be analyzed under a common theoretical framework. In terms of coevolutionary potential, symbiotes can be viewed as lying on a continuum between the intimacy of genes and the indifference of casually co-occurring species. © 2014 Fitzpatrick.
Alsup J.,University of Michigan-Flint |
Papantonopoulos E.,National Technical University of Athens |
Siopsis G.,University of Tennessee at Knoxville
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013
We discuss a novel mechanism to set up a gravity dual of FFLO states in strongly coupled superconductors. The gravitational theory utilizes two U(1) gauge fields and a scalar field coupled to a charged AdS black hole. The first gauge field couples with the scalar sourcing a charge condensate below a critical temperature, and the second gauge field provides a coupling to spin in the boundary theory. The scalar is neutral under the second gauge field. By turning on an interaction between the Einstein tensor and the scalar, it is shown that, in the low temperature limit, an inhomogeneous solution possesses a higher critical temperature than the homogeneous case, giving rise to FFLO states. © 2013 Elsevier B.V.
D'Souza D.H.,University of Tennessee at Knoxville
Current Opinion in Virology | Year: 2014
Plant extracts and associated polyphenols are known for their varied health benefits that include antioxidant effects and antimicrobial properties. The increasing consumer demand for cost-effective and natural alternatives to chemically-synthesized antimicrobials and therapeutics that are also sustainable makes the field of phytochemical research rather intriguing and challenging. Human enteric viruses are increasingly recognized worldwide as significant causes of human disease in adults and children, alike. In the absence of available vaccines for the human noroviruses, plant extracts are gaining popularity for the prevention and treatment of viral diseases. Research on plant extracts (particularly polyphenols derived from fruits) for human enteric virus control will be briefly summarized in this article.
Xiao D.,Oak Ridge National Laboratory |
Liu G.-B.,University of Hong Kong |
Feng W.,Oak Ridge National Laboratory |
Feng W.,University of Tennessee at Knoxville |
And 3 more authors.
Physical Review Letters | Year: 2012
We show that inversion symmetry breaking together with spin-orbit coupling leads to coupled spin and valley physics in monolayers of MoS 2 and other group-VI dichalcogenides, making possible controls of spin and valley in these 2D materials. The spin-valley coupling at the valence-band edges suppresses spin and valley relaxation, as flip of each index alone is forbidden by the valley-contrasting spin splitting. Valley Hall and spin Hall effects coexist in both electron-doped and hole-doped systems. Optical interband transitions have frequency-dependent polarization selection rules which allow selective photoexcitation of carriers with various combination of valley and spin indices. Photoinduced spin Hall and valley Hall effects can generate long lived spin and valley accumulations on sample boundaries. The physics discussed here provides a route towards the integration of valleytronics and spintronics in multivalley materials with strong spin-orbit coupling and inversion symmetry breaking. © 2012 American Physical Society.
Pan M.,University of Florida |
Sun J.,University of Tennessee at Knoxville |
Fang Y.,University of Florida
IEEE Journal on Selected Areas in Communications | Year: 2011
Microeconomics-inspired spectrum auctions can dramatically improve the spectrum utilization for wireless networks to satisfy the ever increasing service demands. However, the back-room dealing (i.e., the frauds of the insincere auctioneer and the bid-rigging between the greedy bidders and the auctioneer) poses significant security challenges, and fails all existing secure auction designs to allocate spectrum bands when considering the frequency reuse in wireless networks. In this paper, we propose THEMIS, a secure spectrum auction leveraging the Paillier cryptosystem to prevent the frauds of the insincere auctioneer as well as the bid-rigging between the bidders and the auctioneer. THEMIS incorporates cryptographic technique into spectrum auction to address the challenges of back-room dealing. It computes and reveals the results of spectrum auction while the actual bidding values of bidders are kept confidential. THEMIS also provides a novel procedure for implementing secure spectrum auction under interference constraints. It has been shown that THEMIS can effectively purge the back-room dealing with limited communication and computational complexity, and achieve similar performance compared with existing insecure spectrum auction designs in terms of spectrum utilization, revenue of the auctioneer, and bidders' satisfaction. © 2006 IEEE.
Wang X.,Laboratory of Molecular Carcinogenesis |
Baek S.J.,University of Tennessee at Knoxville |
Eling T.,Laboratory of Molecular Carcinogenesis
Cancer and Metastasis Reviews | Year: 2011
Inflammation is an important contributor to the development and progression of human cancers. Inflammatory lipid metabolites, prostaglandins, formed from arachidonic acid by prostaglandin H synthases commonly called cyclooxygenases (COXs) bind to specific receptors that activate signaling pathways driving the development and progression of tumors. Inhibitors of prostaglandin formation, COX inhibitors, or nonsteroidal anti-inflammatory drugs (NSAIDs) are well documented as agents that inhibit tumor growth and with long-term use prevent tumor development. NSAIDs also alter gene expression independent of COX inhibition and these changes in gene expression also appear to contribute to the anti-tumorigenic activity of these drugs. Many NSAIDs, as illustrated by sulindac sulfide, alter gene expressions by altering the expression or phosphorylation status of the transcription factors specificity protein 1 and early growth response-1 with the balance between these two events resulting in increases or decreases in specific target genes. In this review, we have summarized and discussed the various genes altered by this mechanism after NSAID treatment and how these changes in expression relate to the anti-tumorigenic activity. A major focus of the review is on NSAID-activated gene (NAG-1) or growth differentiation factor 15. This unique member of the TGF-β superfamily is highly induced by NSAIDs and numerous drugs and chemicals with anti-tumorigenic activities. Investigations with a transgenic mouse expressing the human NAG-1 suggest it acts to suppress tumor development in several mouse models of cancer. The biochemistry and biology of NAG-1 were discussed as potential contributor to cancer prevention by COX inhibitors. © 2011 Springer Science+Business Media, LLC (outside the USA).
Meng J.,University of Houston |
Yin W.,Rice University |
Li H.,University of Tennessee at Knoxville |
Hossain E.,University of Manitoba |
Han Z.,University of Houston
IEEE Journal on Selected Areas in Communications | Year: 2011
Spectrum sensing, which aims at detecting spectrum holes, is the precondition for the implementation of cognitive radio (CR). Collaborative spectrum sensing among the cognitive radio nodes is expected to improve the ability of checking complete spectrum usage. Due to hardware limitations, each cognitive radio node can only sense a relatively narrow band of radio spectrum. Consequently, the available channel sensing information is far from being sufficient for precisely recognizing the wide range of unoccupied channels. Aiming at breaking this bottleneck, we propose to apply matrix completion and joint sparsity recovery to reduce sensing and transmission requirements and improve sensing results. Specifically, equipped with a frequency selective filter, each cognitive radio node senses linear combinations of multiple channel information and reports them to the fusion center, where occupied channels are then decoded from the reports by using novel matrix completion and joint sparsity recovery algorithms. As a result, the number of reports sent from the CRs to the fusion center is significantly reduced. We propose two decoding approaches, one based on matrix completion and the other based on joint sparsity recovery, both of which allow exact recovery from incomplete reports. The numerical results validate the effectiveness and robustness of our approaches. In particular, in small-scale networks, the matrix completion approach achieves exact channel detection with a number of samples no more than 50% of the number of channels in the network, while joint sparsity recovery achieves similar performance in large-scale networks. © 2006 IEEE.
Xu S.,University of Tennessee at Knoxville
Journal of Product Innovation Management | Year: 2015
This study investigates the relationships between the two knowledge dimensions (knowledge breadth and knowledge depth) and two types of innovations (radical innovation and incremental innovation). While existing literature identifies knowledge in general as an important driver of innovation, the exact relationships between knowledge breadth/depth and incremental/radical innovations are not clear. Drawing from the knowledge-based view, this study advances the understanding of the relationships between knowledge dimensions and types of innovations by hypothesizing a nonlinear relationship between knowledge breadth and radical innovation as well as a nonlinear relationship between knowledge depth and incremental innovation. Furthermore, the moderating effects of the interaction between knowledge breadth and knowledge depth on the above-mentioned relationships are also examined. Due to the different natures of the two types of innovations, it is hypothesized that knowledge depth positively moderates the relationship between knowledge breadth and radical innovation while knowledge breadth negatively moderates the relationship between knowledge depth and incremental innovation. To empirically test the hypotheses, secondary data from multiple sources were collected on 64 pharmaceutical firms over 15 years. Due to the panel data structure and observed dispersion issues in the dependent variables, negative binomial random effects models were formulated to test the hypotheses. The statistical results largely support the proposed hypotheses. The results demonstrate that while knowledge breadth positively contributes to the development of radical innovations and knowledge depth positively contributes to the development of incremental innovations, both relationships are subject to diminishing returns. Furthermore, while the finding did support the negative moderating effect of the knowledge breadth on incremental innovation, the positive moderating effect of knowledge depth on radical innovation is not supported. While the effect is not explicitly hypothesized, knowledge breadth seems to have a direct impact on incremental innovation as well. © 2014 Product Development & Management Association.
Rausch M.,Cessna Aircraft Company |
Liao H.,University of Tennessee at Knoxville
IEEE Transactions on Reliability | Year: 2010
Throughput of a manufacturing process depends on the effectiveness of equipment maintenance, and the availability of spare(service) parts. This paper addresses a joint production and spare part inventory control strategy driven by condition based maintenance(CBM) for a piece of manufacturing equipment. Specifically, a critical unit is continuously monitored for performance degradation during operation. The amount of degradation is utilized to initiate replacement actions in conjunction with spare part inventory control under both production lot size, and due date constraints. A degradation limit maintenance policy is combined with a base stock spare part inventory control policy to manage the manufacturing process. The objectives are to minimize the spare part inventory, and the expected total operating cost. Constrained least squares approximation, and simulation-based optimization are utilized, in a heuristic two-step approach, to determine the optimal base-stock level of spare parts, along with the preventive maintenance threshold. The resulting joint decision ascertains the allowed stockout probability for spare parts, while incurring the minimal operating cost for the required production within a fixed production duration. A case study of an automotive engine manufacturing process is provided to demonstrate the proposed decision-making methodology in practical use. © 2006 IEEE.
Pruitt J.N.,University of Tennessee at Knoxville
Proceedings. Biological sciences / The Royal Society | Year: 2011
How task specialization, individual task performance and within-group behavioural variation affects fitness is a longstanding and unresolved problem in our understanding of animal societies. In the temperate social spider, Anelosimus studiosus, colony members exhibit a behavioural polymorphism; females either exhibit an aggressive 'asocial' or docile 'social' phenotype. We assessed individual prey-capture success for both phenotypes, and the role of phenotypic composition on group-level prey-capture success for three prey size classes. We then estimated the effect of group phenotypic composition on fitness in a common garden, as inferred from individual egg-case masses. On average, asocial females were more successful than social females at capturing large prey, and colony-level prey-capture success was positively associated with the frequency of the asocial phenotype. Asocial colony members were also more likely to engage in prey-capture behaviour in group-foraging situations. Interestingly, our fitness estimates indicate females of both phenotypes experience increased fitness when occupying colonies containing unlike individuals. These results imply a reciprocal fitness benefit of within-colony behavioural variation, and perhaps division of labour in a spider society.
Lebeis S.L.,University of Tennessee at Knoxville
Current Opinion in Plant Biology | Year: 2015
Specific subsets of microbes are capable of assembly into plant-associated communities that influence the fitness of both the host and the microbes. While there is a large spectrum of plant phenotypes cause by microbes, the microbial community members benefit from living in protected and nutrient rich plant-associated environments. Recent advances in '-omics' technologies have provided researchers with the ability to identify and assign functions to even unculturable microbes inhabiting both above-ground and below-ground plant tissues. Thus, we are beginning to unravel the molecular mechanisms of microbiome assembly and activities that contribute to overall plant health, not only for individuals, but also at the community-level. © 2015 Elsevier Ltd.
Banerjee D.,University of Tennessee at Knoxville
Local Environment | Year: 2012
Conservation discourses in the last decade have witnessed a radical shift in the conceptualisation of nature. The imagery of a pristine nature has been replaced by a growing recognition of culture and place-based attachments as emerging frontiers of conservation. Yet, the complexities of place and culture call for a greater reflection on cultural approaches to natural resource management. In this paper, I argue that the cultural discourses in conservation policies are largely global in nature and conflict with a community's understanding of a local cultural tradition. The notion of the global closely relates to a global framing of an environmental problem that glosses over cultural specificities. On the other hand, local is defined here in materially specific terms that highlight the role of history in shaping environmental traditions. I examine these contradictory framings through a narrative of conservation, displacement, and cultural loss in a US rural community known as Land Between the Rivers. © 2012 Copyright Taylor and Francis Group, LLC.
Smith C.V.,University of Mississippi |
Shaffer M.J.,University of Tennessee at Knoxville
Journal of Sex and Marital Therapy | Year: 2013
Although loss of virginity remains a salient experience throughout a person's lifetime, little is known about whether this experience has implications for later sexual functioning (e.g., sexual satisfaction). Previous research tends to ask participants about their first time and their current sexual functioning concurrently, which may lead to spillover effects. The authors investigated the relation between firsttime sexual intercourse and current sexual satisfaction using an event-sampling methodology. Participants were 331 undergraduate students who answered questions about their first-time sexual encounter and their current sexual functioning (e.g., sexual satisfaction, sexual depression). Participants then described and rated each of their sexual interactions for 2 weeks. Results show that participants who had more positive first-time sexual experiences (e.g., intimacy, respect) report greater feelings of sexual satisfaction and esteem and less sexual depression. A series of multilevel random coefficient modeling analyses revealed that positive first-time experiences were predictive of physical and emotional satisfaction in their current sexual interactions, even when controlling for global sexual satisfaction. These results suggest that one's first-time sexual experience is more than just a milestone in development. Rather, it appears to have implications for their sexual well-being years later. Copyright © 2013, Taylor & Francis Group, LLC.
Fitzpatrick B.M.,University of Tennessee at Knoxville |
Fitzpatrick B.M.,National Institute for Mathematical and Biological Synthesis
BMC Evolutionary Biology | Year: 2012
Background: Hybridization, genetic mixture of distinct populations, gives rise to myriad recombinant genotypes. Characterizing the genomic composition of hybrids is critical for studies of hybrid zone dynamics, inheritance of traits, and consequences of hybridization for evolution and conservation. Hybrid genomes are often summarized either by an estimate of the proportion of alleles coming from each ancestral population or classification into discrete categories like F1, F2, backcross, or merely "hybrid" vs. "pure". In most cases, it is not realistic to classify individuals into the restricted set of classes produced in the first two generations of admixture. However, the continuous ancestry index misses an important dimension of the genotype. Joint consideration of ancestry together with interclass heterozygosity (proportion of loci with alleles from both ancestral populations) captures all of the information in the discrete classification without the unrealistic assumption that only two generations of admixture have transpired. Methods. I describe a maximum likelihood method for joint estimation of ancestry and interclass heterozygosity. I present two worked examples illustrating the value of the approach for describing variation among hybrid populations and evaluating the validity of the assumption underlying discrete classification. Results: Naively classifying natural hybrids into the standard six line cross categories can be misleading, and false classification can be a serious problem for datasets with few molecular markers. My analysis underscores previous work showing that many (50 or more) ancestry informative markers are needed to avoid erroneous classification. Conclusion: Although classification of hybrids might often be misleading, valuable inferences can be obtained by focusing directly on distributions of ancestry and heterozygosity. Estimating and visualizing the joint distribution of ancestry and interclass heterozygosity is an effective way to compare the genetic structure of hybrid populations and these estimates can be used in classic quantitative genetic methods for assessing additive, dominant, and epistatic genetic effects on hybrid phenotypes and fitness. The methods are implemented in a freely available package "HIest" for the R statistical software. © 2012 Fitzpatrick; licensee BioMed Central Ltd.
Mundorff A.Z.,University of Tennessee at Knoxville
Forensic Science, Medicine, and Pathology | Year: 2012
This paper will provide mass fatality emergency planners, police, medical examiners, coroners and other Disaster Victim Identification (DVI) personnel ways to integrate forensic anthropologists into DVI operations and demonstrate how anthropological contributions have improved DVI projects. In mass disaster situations, anthropologists have traditionally been limited to developing biological profiles from skeletal remains. Over the past decade, however, anthropologists' involvement in DVI has extended well beyond this traditional role as they have taken on increasingly diverse tasks and responsibilities. Anthropological involvement in DVI operations is often dictated by an incident's specific characteristics, particularly events involving extensive fragmentation, commingling, or other forms of compromised remains. This paper will provide examples from recent DVI incidents to illustrate the operational utility of anthropologists in the DVI context. The points where it is most beneficial to integrate anthropologists into the DVI process include: (1) during recovery at the disaster scene; (2) at the triage station as remains are brought into the mortuary; and (3) in conducting the reconciliation process. Particular attention will be paid to quality control and quality assurance measures anthropologists have developed and implemented for DVI projects. Overall, this paper will explain how anthropological expertise can be used to increase accuracy in DVI while reducing the project's cost and duration. © 2011 Springer Science+Business Media, LLC.
May S.E.,University of Tennessee at Knoxville
Journal of Forensic Sciences | Year: 2011
Cremains have become increasingly frequent in forensic contexts, while higher body mass in the general population has simultaneously made cremation a more cost-effective mortuary practice. This study analyzed the relationship between body mass and bone mass, as reflected through cremation weight. Antemortem data were recorded for samples used in the multi-regional data set. Each was rendered through commercial crematoriums and reweighed postincineration. Pearson's correlation demonstrates clear association between body mass and cremation weight (r = 0.56; p < 0.0001). However, multiple linear regression revealed sex and age variables also have a significant relationship (t = 7.198; t = -2.5, respectively). Regressed in conjunction, body mass, sex, and age contribute approximately 67% of all variation observed in cremation weight (r = 0.668). Analysis of covariance indicates significant regional variation in body and cremation weight. Explanations include bone modification resulting from increased loading stress, as well as glucose intolerance and altered metabolic pathways related to obesity. © 2010 American Academy of Forensic Sciences.
Chang H.-H.,National Taiwan University |
Yen S.T.,University of Tennessee at Knoxville
Aging and Mental Health | Year: 2012
Objectives: Obesity has been identified as an epidemic worldwide. In Taiwan, the highest prevalence of obesity is observed in adults age ≥ 65. This article investigates the effects of body weight status on the likelihood of depression among the elderly in Taiwan. Method: A longitudinal sample of the elderly (1351 males and 1165 females) interviewed in both the 1999 and 2003 Surveys of Health and Living Status of the Elderly in Taiwan is used. A random effect logit model is estimated to examine the effects of body weight status, lifestyle, and socio-demographic characteristics on the likelihood of depression. Results: About 10.4% of the elderly men are overweight and 13.4% are obese in 2003. A higher prevalence of obesity is found among elderly women, with 19.3% being overweight and 26.4% obese. Elderly men who are underweight are more likely to be depressed (odds ratio; OR=2.36) than those from other weight categories, while overweight and obese women are less likely to be depressed (ORs=0.72 and 0.61) than elderly women of the normal weight category. Conclusions: In contrast to most findings for the Western countries, a negative association between obesity and depression of the elderly is evident in Taiwan. The different findings between Western and Asian countries may be due to the cultural differences. Unlike the Western countries that stigmata are attached to excessive overweight, being overweight is not a symbol of unhealthiness because only the wealthy can afford to eat more and put on more weight in the Chinese society. © 2012 Copyright Taylor and Francis Group, LLC.
Pruitt J.N.,University of Pittsburgh |
Oufiero C.E.,University of California at Davis |
Aviles L.,University of British Columbia |
Riechert S.E.,University of Tennessee at Knoxville
American Naturalist | Year: 2012
The evolution of group living is regarded as a major evolutionary transition and is commonly met with correlated shifts in ancillary characters. We tested for associations between social tendency and a myriad of abiotic variables (e.g., temperature and precipitation) and behavioral traits (e.g., boldness, activity level, and aggression) in a clade of spiders that exhibit highly variable social structures (genus Anelosimus). We found that, relative to their subsocial relatives, social species tended to exhibit reduced aggressiveness toward prey, increased fearfulness toward predators, and reduced activity levels, and they tended to occur in warm, wet habitats with low average wind velocities. Within-species variation in aggressiveness and boldness was also positively associated with sociality. We then assessed the functional consequences of within-species trait variation on reconstituted colonies of four test species (Anelosimus eximius, Anelosimus rupununi, Anelosimus guacamayos, and Anelosimus oritoyacu). We used colonies consisting of known ratios of docile versus aggressive individuals and group foraging success as a measure of colony performance. In all four test species, we found that groups composed of a mixture of docile and aggressive individuals outperformed monotypic groups. Mixed groups were more effective at subduing medium and large prey, and mixed groups collectively gained more mass during shared feeding events. Our results suggest that the iterative evolution of depressed aggressiveness and increased within-species behavioral variation in social spiders is advantageous and could be an adaptation to group living that is analogous to the formation of morphological castes within the social insects. © 2012 by The University of Chicago.
Akcay E.,University of Tennessee at Knoxville |
Akcay E.,Princeton University |
van Cleve J.,Santa Fe Institute
American Naturalist | Year: 2012
An unresolved controversy regarding social behaviors is exemplified when natural selection might lead to behaviors that maximize fitness at the social-group level but are costly at the individual level. Except for the special case of groups of clones, we do not have a general understanding of how and when group-optimal behaviors evolve, especially when the behaviors in question are flexible. To address this question, we develop a general model that integrates behavioral plasticity in social interactions with the action of natural selection in structured populations. We find that group-optimal behaviors can evolve, even without clonal groups, if individuals exhibit appropriate behavioral responses to each other's actions. The evolution of such behavioral responses, in turn, is predicated on the nature of the proximate behavioral mechanisms. We model a particular class of proximate mechanisms, prosocial preferences, and find that such preferences evolve to sustain maximum group benefit under certain levels of relatedness and certain ecological conditions. Thus, our model demonstrates the fundamental interplay between behavioral responses and relatedness in determining the course of social evolution. We also highlight the crucial role of proximate mechanisms such as prosocial preferences in the evolution of behavioral responses and in facilitating evolutionary transitions in individuality. © 2011 by The University of Chicago.
Haig D.,Harvard University |
Ubeda F.,University of Tennessee at Knoxville
Current Biology | Year: 2011
Excessive grooming in mice has been promoted as a model of human obsessive-compulsive disorders. A recent paper adds Grb10 to the list of genes with effects on behavioral hair loss, with the added twist that this time the gene is imprinted. © 2011 Elsevier Ltd.
Raynor H.A.,University of Tennessee at Knoxville
International Journal of Obesity | Year: 2014
As portion size has increased in the United States, greater concern has arisen regarding the positive relationship between portion size and consumption, and how this relationship may negatively impact weight management. This article is a summary of a roundtable discussion from the Forefronts in Portion Size Conference held in Philadelphia, PA, USA in May 2013. The roundtable included four discussants, five speakers who had presented research on various components of portion size at the conference, two organizers and the moderator. Topics discussed included methods to reduce portion size that can assist with reducing energy intake, societal norms about portion size, values associated with portion size and methods to promote smaller portion sizes. Areas needing additional research were also identified. © 2014 Macmillan Publishers Limited All rights reserved.
Chen F.,University of Tennessee at Knoxville |
Tholl D.,Virginia Polytechnic Institute and State University |
Bohlmann J.,University of British Columbia |
Pichersky E.,University of Michigan
Plant Journal | Year: 2011
Some plant terpenes such as sterols and carotenes are part of primary metabolism and found essentially in all plants. However, the majority of the terpenes found in plants are classified as 'secondary' compounds, those chemicals whose synthesis has evolved in plants as a result of selection for increased fitness via better adaptation to the local ecological niche of each species. Thousands of such terpenes have been found in the plant kingdom, but each species is capable of synthesizing only a small fraction of this total. In plants, a family of terpene synthases (TPSs) is responsible for the synthesis of the various terpene molecules from two isomeric 5-carbon precursor 'building blocks', leading to 5-carbon isoprene, 10-carbon monoterpenes, 15-carbon sesquiterpenes and 20-carbon diterpenes. The bryophyte Physcomitrella patens has a single TPS gene, copalyl synthase/kaurene synthase (CPS/KS), encoding a bifunctional enzyme producing ent-kaurene, which is a precursor of gibberellins. The genome of the lycophyte Selaginella moellendorffii contains 18 TPS genes, and the genomes of some model angiosperms and gymnosperms contain 40-152 TPS genes, not all of them functional and most of the functional ones having lost activity in either the CPS- or KS-type domains. TPS genes are generally divided into seven clades, with some plant lineages having a majority of their TPS genes in one or two clades, indicating lineage-specific expansion of specific types of genes. Evolutionary plasticity is evident in the TPS family, with closely related enzymes differing in their product profiles, subcellular localization, or the in planta substrates they use. © 2011 The Authors.
Brodribb T.J.,University of Tasmania |
Feild T.S.,University of Tennessee at Knoxville
Ecology Letters | Year: 2010
Angiosperm evolution transformed global ecology, and much of this impact derives from the unrivalled vegetative productivity of dominant angiosperm clades. However, the origins of high photosynthetic capacity in angiosperms remain unknown. In this study, we describe the steep trajectory of leaf vein density (Dv) evolution in angiosperms, and predict that this leaf plumbing innovation enabled a major shift in the capacity of leaves to assimilate CO2. Reconstructing leaf vein evolution from an examination of 504 angiosperm species we found a rapid three- to fourfold increase in Dv occurred during the early evolution of angiosperms. We demonstrate how this major shift in leaf vein architecture potentially allowed the maximum photosynthetic capacity in angiosperms to rise above competing groups 140-100 Ma. Our data suggest that early terrestrial angiosperms produced leaves with low photosynthetic rates, but that subsequent angiosperm success is linked to a surge in photosynthetic capacity during their early diversification. © 2009 Blackwell Publishing Ltd/CNRS.
Reassessing Trends In Black Violent Crime, 1980-2008: Sorting Out The "Hispanic Effect" In Uniform Crime Reports Arrests, National Crime Victimization Survey Offender Estimates, And U.S. Prisoner Counts
Steffensmeier D.,Pennsylvania State University |
Feldmeyer B.,University of Tennessee at Knoxville |
Harris C.T.,Pennsylvania State University |
Ulmer J.T.,Pennsylvania State University
Criminology | Year: 2011
Recent studies suggest a decline in the relative Black effect on violent crime in recent decades and interpret this decline as resulting from greater upward mobility among African Americans during the past several decades. However, other assessments of racial stratification in American society suggest at least as much durability as change in Black social mobility since the 1980s. Our goal is to assess how patterns of racial disparity in violent crime and incarceration have changed from 1980 to 2008. We argue that prior studies showing a shrinking Black share of violent crime might be in error because of reliance on White and Black national crime statistics that are confounded with Hispanic offenders, whose numbers have been increasing rapidly and whose violence rates are higher than that of Whites but lower than that of Blacks. Using 1980-2008 California and New York arrest data to adjust for this "Hispanic effect" in national Uniform Crime Reports (UCR) and National Crime Victimization Survey (NCVS) data, we assess whether the observed national decline in racial disparities in violent crime is an artifact of the growth in Hispanic populations and offenders. Results suggest that little overall change has occurred in the Black share of violent offending in both UCR and NCVS estimates during the last 30 years. In addition, racial imbalances in arrest versus incarceration levels across the index violent crimes are both small and comparably sized across the study period. We conclude by discussing the consistency of these findings with trends in economic and social integration of Blacks in American society during the past 50 years. © 2011 American Society of Criminology.
Best M.D.,University of Tennessee at Knoxville |
Zhang H.,University of Utah |
Prestwich G.D.,University of Utah
Natural Product Reports | Year: 2010
Polyphosphorylated myo-inositol compounds, including the inositol polyphosphates (InsPs), diphosphoinositol polyphosphates (PP-InsPs), and phosphatidylinositol polyphosphates (PIPns), represent key biomolecules that regulate a litany of critical biological processes. These compounds exist with myriad combinations of phosphorylation patterns, resulting in a complex network of interconverting signaling molecules that control different events. Due to the significance and intricate nature of this molecular family, the elucidation of biological roles has elicited substantial interest in both the biochemical and chemical communities. Within this broad effort, strategies employing chemical synthesis for the production of both natural products and chemically modified structures have proven advantageous for determining activities. Herein, we will discuss recent advancements in these efforts, including (i) a brief overview of structure and biological activity, (ii) current methods for the chemical synthesis of phosphorylated myo-inositols, (iii) strategies for the design of biologically active probe structures, and (iv) case studies in which synthetic probes have been applied to characterize biological properties. © 2010 The Royal Society of Chemistry.
Li H.,University of Tennessee at Knoxville |
Han Z.,University of Houston
IEEE Transactions on Wireless Communications | Year: 2011
The defense against the Primary User Emulation Attack (PUE) is studied in the scenario of unknown channel statistics (coined blind dogfight in spectrum). The algorithm of the adversarial bandit problem is adapted to the context of blind dogfight. Both cases of complete and partial information about the rewards of different channels are analyzed. Performance bounds are obtained subject to arbitrary channel statistics and attack policy. Several attack strategies, namely uniformly random, selectively random and maximal interception attacks, are discussed. The validity of the defense strategy is then demonstrated by numerical simulation results. © 2011 IEEE.
Li H.,University of Tennessee at Knoxville
IEEE Transactions on Vehicular Technology | Year: 2011
A recommendation system is proposed to enhance the efficiency of spectrum access in cognitive radio networks, in which secondary users broadcast the indices of channels that they have successfully accessed. The probabilities of different actions, i.e., taking a recommendation or probing an unrecommended channel, could be either fixed or adjustable. For the constant probability case with and without retransmission, the system is modeled as a Markov random process, and the corresponding state transition probabilities are obtained. For the adjustable probability case, the anytime multiarmed bandit technique is used to adopt the strategies to the uncertain environments, and a performance lower bound is obtained. Numerical simulation results demonstrate that the proposed recommendation system can effectively orient the channel selections and significantly improve the performance of cognitive radio networks. © 2011 IEEE.
Vilciauskas L.,Max Planck Institute for Solid State Research |
Tuckerman M.E.,Courant Institute of Mathematical Sciences |
Bester G.,Max Planck Institute for Solid State Research |
Paddison S.J.,University of Tennessee at Knoxville |
Kreuer K.-D.,Max Planck Institute for Solid State Research
Nature Chemistry | Year: 2012
Neat liquid phosphoric acid (H 3PO 4) has the highest intrinsic proton conductivity of any known substance and is a useful model for understanding proton transport in other phosphate-based systems in biology and clean energy technologies. Here, we present an ab initio molecular dynamics study that reveals, for the first time, the microscopic mechanism of this high proton conductivity. Anomalously fast proton transport in hydrogen-bonded systems involves a structural diffusion mechanism in which intramolecular proton transfer is driven by specific hydrogen bond rearrangements in the surrounding environment. Aqueous media transport excess charge defects through local hydrogen bond rearrangements that drive individual proton transfer reactions. In contrast, strong, polarizable hydrogen bonds in phosphoric acid produce coupled proton motion and a pronounced protic dielectric response of the medium, leading to the formation of extended, polarized hydrogen-bonded chains. The interplay between these chains and a frustrated hydrogen-bond network gives rise to the high proton conductivity. © 2012 Macmillan Publishers Limited. All rights reserved.
Hacquard S.,Max Planck Institute for Plant Breeding Research |
Schadt C.W.,Oak Ridge National Laboratory |
Schadt C.W.,University of Tennessee at Knoxville
New Phytologist | Year: 2015
Interactions between trees and microorganisms are tremendously complex and the multispecies networks resulting from these associations have consequences for plant growth and productivity. However, a more holistic view is needed to better understand trees as ecosystems and superorganisms, where many interacting species contribute to the overall stability of the system. While much progress has been made on microbial communities associated with individual tree niches and the molecular interactions between model symbiotic partners, there is still a lack of knowledge of the multi-component interactions necessary for holistic ecosystem-level understanding. We review recent studies in Populus to emphasize the importance of such holistic efforts across the leaf, stem and rooting zones, and discuss prospects for future research in these important ecosystems. © 2014 New Phytologist Trust.
Wise S.M.,University of Tennessee at Knoxville
Journal of Scientific Computing | Year: 2010
We present an unconditionally energy stable and solvable finite difference scheme for the Cahn-Hilliard-Hele-Shaw (CHHS) equations, which arise in models for spinodal decomposition of a binary fluid in a Hele-Shaw cell, tumor growth and cell sorting, and two phase flows in porous media. We show that the CHHS system is a specialized conserved gradient-flow with respect to the usual Cahn-Hilliard (CH) energy, and thus techniques for bistable gradient equations are applicable. In particular, the scheme is based on a convex splitting of the discrete CH energy and is semi-implicit. The equations at the implicit time level are nonlinear, but we prove that they represent the gradient of a strictly convex functional and are therefore uniquely solvable, regardless of time step-size. Owing to energy stability, we show that the scheme is stable in the L s ∞ (0, T, ; H h 2 norm, and, assuming two spatial dimensions, we show in an appendix that the scheme is also stable in the L s 2 (0, T, ; H h 2 norm. We demonstrate an efficient, practical nonlinear multigrid method for solving the equations. In particular, we provide evidence that the solver has nearly optimal complexity. We also include a convergence test that suggests that the global error is of first order in time and of second order in space. © 2010 Springer Science+Business Media, LLC.
Brandvain Y.,University of California at Davis |
Van Cleve J.,Santa Fe Institute |
Ubeda F.,University of Tennessee at Knoxville |
Wilkins J.F.,Santa Fe Institute
Trends in Genetics | Year: 2011
Genomic imprinting is the differential expression of an allele based on the parent of origin. Recent transcriptome-wide evaluations of the number of imprinted genes reveal complex patterns of imprinted expression among developmental stages and cell types. Such data demand a comprehensive evolutionary framework in which to understand the effect of natural selection on imprinted gene expression. We present such a framework for how asymmetries in demographic parameters and fitness effects can lead to the evolution of genomic imprinting and place recent theoretical advances in this framework. This represents a modern interpretation of the kinship theory, is well suited to studying populations with complex social interactions, and provides predictions which can be tested with forthcoming transcriptomic data. To understand the intricate phenotypic patterns that are emerging from the recent deluge of data, future investigations of genomic imprinting will require integrating evolutionary theory, transcriptomic data, developmental and functional genetics, and natural history. © 2011 Elsevier Ltd.
Chisholm M.F.,Oak Ridge National Laboratory |
Duscher G.,Oak Ridge National Laboratory |
Duscher G.,University of Tennessee at Knoxville |
Windl W.,Ohio State University
Nano Letters | Year: 2012
We have found that reactive elements that are normally oxidized at room temperature are present as individual atoms or clusters on and in graphene. Oxygen is present in these samples but it is only detected in the thicker amorphous carbon layers present in the graphene specimens we have examined. However, we have seen no evidence that oxygen reacts with the impurity atoms and small clusters of these normally reactive elements when they are incorporated in the graphene layers. First principles calculations suggest that the oxidation resistance is due to kinetic effects such as preferential bonding of oxygen to nonincorporated atoms and H passivation. The observed oxidation resistance of reactive atoms in graphene may allow the use of these incorporated metals in catalytic applications. It also opens the possibility of designing and producing electronic, opto-electronic, and magnetic devices based on these normally reactive atoms. © 2012 American Chemical Society.
MacLennan B.J.,University of Tennessee at Knoxville
Nano Communication Networks | Year: 2010
The creation of physical objects with a complex hierarchical structure from the nanoscale up to the macroscale presents many challenges that must be met in order to reap the full benefits of nanotechnology. To accomplish this we can learn from a natural process that already accomplishes it: embryological morphogenesis, which teaches us means by which microscopic agents can communicate and coordinate their activity by means of molecular signals in order to create complex physical structures. We call the application of these ideas artificial morphogenesis; it is a kind of embodied computation, which refers to the intimate interaction of physical and information processes. We outline the basis for artificial morphogenesis and present several simple examples in which biologically inspired models can be used to describe the assembly of useful nanostructures. © 2010 Elsevier Ltd.
Boseovski J.J.,University of North Carolina at Greensboro |
Thurman S.L.,University of Tennessee at Knoxville
Child Development | Year: 2014
This study examined 3- to 7-year-old children's reliance on informant testimony to learn about a novel animal. Sixty participants were given positive or negative information about an Australian marsupial from an informant described as a maternal figure or a zookeeper. Children were asked which informant was correct and were invited to touch the animal, which was a stuffed toy hidden in a crate. Overall, younger children endorsed the zookeeper's testimony about the animal, but touched the animal more readily when the maternal figure provided positive information. Older children endorsed the informant who provided positive information, but showed some sensitivity to zookeeper expertise. Age differences were obtained in the association between participant characteristics and informant selection and animal approach behavior. Child Development © 2014 The Society for Research in Child Development, Inc.
Barrios-Garcia M.N.,University of Tennessee at Knoxville |
Ballari S.A.,National University of Cordoba
Biological Invasions | Year: 2012
Wild boar are now present on all continents except Antarctica and can greatly affect community structure and ecosystem function. Their destructive feeding habits, primarily rooting disturbance, can reduce plant cover, diversity, and regeneration. Furthermore, predation and habitat destruction by boar can greatly affect animal communities. Effects of wild boar on fungi and aquatic communities are scarcely studied, and soil properties and processes seem more resistant to disturbance. Wild boar also affect humans' economy as they cause crop damage and transmit diseases to livestock and wildlife. In this review, we found that most of the published literature examines boar effects in their introduced range and little is available from the native distribution. Because most of the research describes direct effects of wild boar on plant communities and predation on some animal communities, less is known about indirect effects on ecosystem function. Finally, predictive research and information on ecosystem recovery after wild boar removal are scarce. We identified research gaps and urge the need to lower wild boar densities. Identifying commonalities among wild boar impacts on native ecosystems across its introduced range will help in the design of management strategies. © 2012 Springer Science+Business Media B.V.
Guiochon G.,University of Tennessee at Knoxville |
Beaver L.A.,Laboratory L.T.D
Journal of Chromatography A | Year: 2011
The impact of economic change, advances in science, therapy and production processes resulted in considerable growth in the area of biopharmaceuticals. Progress in selection of microorganisms and improvements in cell culture and bioreactors is evidenced by increased yields of the desired products in the complex fermentation mixture. At this stage the downstream process of extraction and purification of the desired biopharmaceutical requires considerable attention in the design and operation of the units used for preparative chromatography. Understanding of the process, optimization of column design and experimental conditions have become critical to the biopharmaceutical industry in order to minimize production costs while satisfying new regulatory requirements. Optimization of the purification of biopharmaceuticals by preparative liquid chromatography including an examination of column preparation and bed properties is the focus of this manuscript. © 2011 Elsevier B.V.
Shu T.,Oakland University |
Li H.,University of Tennessee at Knoxville
IEEE Journal on Selected Areas in Communications | Year: 2014
In this paper, we study the quality-of-service (QoS) support for realtime traffic in cognitive radio (CR) networks when spectrum availability and quality is not known a priori. A resource-constrained CR relies on sequential channel sensing and probing to resolve spectrum uncertainty and search for good transmission opportunities in real time. We are interested in maximizing the effective throughput the CR can achieve with a desired confidence (success probability) under a spectrum access delay constraint. This quantity can be interpreted as the QoS-compliant (e.g., min-rate and delay) capacity of the CR link under the uncertain spectrum environment. The optimization is formulated as a finite-horizon optimal stopping problem under the objective of maximizing a given percentile of the rate of return at the stopping time. This formulation cannot be directly solved by classical optimal stopping theory, because the latter only supports a mean-reward objective function. A novel transformation is developed to convert the problem into solving a series of sub problems, each of which optimizes a transformed mean-reward of the original problem and therefore can be solved using classical optimal stopping method. We prove the monotonicity of the sub problems, based on which we develop a fast algorithm to efficiently find the unique solution to the original problem. To account for different MAC mechanisms used in practice, our analysis considers both non-recall and recall channel decision strategies. Extensive simulations are performed to verify the effectiveness and significance of the optimization. We show that significant gains (e.g., over 30%) on the QoS-compliant capacity can be achieved by the proposed algorithm when compared with the counterparts. © 1983-2012 IEEE.
Lindley L.C.,University of Tennessee at Knoxville |
Lyon M.E.,Childrens National Medical Center
Journal of Palliative Medicine | Year: 2013
Background: As the United States braces for full implementation of health care reform, the eyes of the nation are on Medicaid. The large number of newly eligible Medicaid beneficiaries may challenge health care resources and ultimately impact quality of care. This is a special concern among current Medicaid beneficiaries such as children with complex chronic conditions (CCCs) who have significant health care needs, especially at end of life (EOL). Yet, a comprehensive profile of these children is lacking. Objective: To understand the demographic and health characteristics, health care utilization, and expenditures among Medicaid children with CCCs at EOL. Methods: Our study used a retrospective cohort design with data from the 2007 and 2008 California Medicaid data files. Descriptive statistics were used to profile children in the last year of life. Results: We found a diverse group of children who suffered with serious, multiple chronic conditions, and who accessed comprehensive, multidisciplinary care. Most children had neuromuscular conditions (54%), cardiovascular conditions (46%), and cancer (30%). A majority (56%) had multiple CCCs. Children with CCCs received comprehensive care including hospital inpatient (67%), primary (82%), ancillary (87%), and other acute care services (83%); however, few children utilized hospice and home health care services (26%). Significant age differences existed among the children. Conclusions: The current California Medicaid system appears to provide comprehensive care for children at EOL. The underutilization of hospice and home health services, however, represents an opportunity to improve the quality of EOL care while potentially reducing or remaining budget neutral. © Copyright 2013, Mary Ann Liebert, Inc. 2013.
Jackson H.B.,Carleton University |
Jackson H.B.,University of Tennessee at Knoxville |
Fahrig L.,Carleton University
Global Ecology and Biogeography | Year: 2015
Aim: The spatial extent (scale) at which landscape attributes are measured has a strong impact on inferred species-landscape relationships. Consequently, researchers commonly measure landscape variables at multiple scales to select one scale (the 'scale of effect') that yields the strongest species-landscape relationship. Scales of effect observed in multiscale studies may not be true scales of effect if scales are arbitrarily selected and/or are too narrow in range. Miscalculation of the scale of effect may explain why the theoretical relationship between scale of effect and species traits, e.g. dispersal distance, is not empirically well supported. Location: World-wide. Methods: Using data from 583 species in 71 studies we conducted a quantitative review of multiscale studies to evaluate whether research has been conducted at the true scale of effect. Results: Multiple lines of evidence indicated that multiscale studies are often conducted at suboptimal scales. We did not find convincing evidence of a relationship between observed scale of effect and any of 29 species traits. Instead, observed scales of effect were strongly positively predicted by the smallest and largest scales evaluated by researchers. Only 29% of studies reported biological reasons for the scales evaluated. Scales tended to be narrow in range (the mean range is 0.9 orders of magnitude) and few (the mean number of scales evaluated is four). Many species (44%) had observed scales of effect equal to the smallest or largest scale evaluated, suggesting a better scale was outside that range. Increasing the range of scales evaluated decreased the proportion of species with scales of effect equal to the smallest or largest scale evaluated. Main conclusions: To ensure that species-landscape relationships are well estimated, we recommend that the scales at which landscape variables are measured range widely, from the size of a single territory to well above the average dispersal distance. © 2014 John Wiley & Sons Ltd.
Li J.,Oak Ridge National Laboratory |
Daniel C.,Oak Ridge National Laboratory |
Daniel C.,University of Tennessee at Knoxville |
Wood D.,Oak Ridge National Laboratory
Journal of Power Sources | Year: 2011
Extensive efforts have been undertaken to develop and optimize new materials for lithium-ion batteries to address power and energy demands of mobile electronics and electric vehicles. However, the introduction of large-format lithium-ion batteries is hampered by high cost, safety concerns, and deficiencies in energy density and calendar life. Advanced materials-processing techniques can contribute solutions to such issues. From that perspective, this work summarizes the materials-processing techniques used to fabricate the cathodes, anodes, and separators used in lithium-ion batteries. © 2010 Elsevier B.V. All rights reserved.
Greene D.L.,University of Tennessee at Knoxville
Transportation Research Part D: Transport and Environment | Year: 2011
Charging highway users per mile has been proposed as a replacement for the US motor fuel tax. A miles traveled user fee, however, does not encourage energy efficiency in vehicle design, purchase and operation, as would a user fee levied on all forms of commercial energy used for transportation and indexed to the average efficiency of vehicles on the road. An indexed roadway user toll on energy would induce two to four times as much reduction in greenhouse gas emissions and petroleum use as a pure mileage fee. However, it is not a substitute for pricing greenhouse gas emissions and would make only a small but useful contribution to reducing petroleum dependence. An indexed energy user fee cannot adequately address the problems of traffic congestion and heavy vehicle cost responsibility but it could be a component of a system of financing surface transportation that would eventually also include time and place specific monitoring of miles traveled for congestion pricing, externality charges and heavy vehicle user fees. © 2011 Elsevier Ltd.
Hall H.L.,University of Tennessee at Knoxville
Integrated Environmental Assessment and Management | Year: 2011
Implications of the nuclear power plant accidents at Fukushima Daiichi are explored in this commentary. In addition to questions of nuclear reactor regulatory standards, broader implications on noncarbon-emitting energy production, nuclear nonproliferation objectives, and community resilience and emergency response against catastrophic events are explored. © 2011 SETAC.
Brown M.,University of Tennessee at Knoxville |
Rafter N.,Northeastern University
British Journal of Criminology | Year: 2013
One cannot understand or remember the genocides of the past in any direct manner. Their inaccessibility impedes us from working toward complex understandings of these events and adequate ways of responding to them. In this paper, we bring together various strands of criminological thought by examining genocide films as a form of public criminology that is engaged in the work of memory and commemoration. We identify a specific set of genocide films that, we argue, not only constitute a key (if hitherto unrecognized) branch of visual and public criminology, but also create and transmit collective memories of the 'crime of crimes', provoking public understandings of atrocity and meaningful social and political responses. These films direct us toward representational strategies and interdisciplinary perspectives that advance our theoretical and empirical understanding of genocide. Attention to such efforts not only underscores the work of images in shaping criminological discourse, but also makes for a better - because more deeply informed - criminology of genocide. © The Author 2013. Published by Oxford University Press on behalf of the Centre for Crime and Justice Studies (ISTD). All rights reserved.
Atkins D.N.,University of Tennessee at Knoxville |
Bradford W.D.,University of Georgia
Perspectives on Sexual and Reproductive Health | Year: 2014
CONTEXT: Access to effective contraceptives is critical to reducing levels of unintended childbearing in the United States. Since 1998, more than half the states have passed legislation requiring insurers that cover prescription drugs to cover prescription contraceptives approved by the Food and Drug Administration. An assessment of the impact of these laws on women's contraceptive use is needed to determine whether such policies are effective. METHODS: Information was collected on state contraceptive coverage policies, and contraceptive use data among women at risk of unintended pregnancy were drawn from Behavioral Risk Factor Surveillance System surveys conducted between 1998 and 2010. Logit regression analysis was used to calculate the marginal effects of state contraceptive coverage laws on insured and uninsured women's use of prescription methods. RESULTS: Insured women who lived in a state with a contraceptive coverage law were 5% more likely than their counterparts in states without such laws to use an effective method (i.e., a prescription method, condoms or sterilization). Among women who used such methods, those in contraceptive coverage states were 5% more likely than women in other states to use any prescription method, and 4% more likely to use the pill. No associations were found between contraceptive mandates and method use by uninsured women. Among both users and nonusers, contraceptive coverage was associated with a 5% increase in pill use. CONCLUSIONS: Contraceptive coverage mandates appear to play a role in increasing the use of prescription contraceptives among insured women, and hence may help to reduce the numbers of unintended pregnancies. © 2014 by the Guttmacher Institute.
Hettich R.L.,Oak Ridge National Laboratory |
Sharma R.,Oak Ridge National Laboratory |
Sharma R.,University of Tennessee at Knoxville |
Chourey K.,Oak Ridge National Laboratory |
Giannone R.J.,Oak Ridge National Laboratory
Current Opinion in Microbiology | Year: 2012
The availability of genome information for microbial consortia, including unculturable species, from environmental samples has enabled systems-biology interrogation by providing a means to access genomic, transcriptomic, and proteomic information. This provides a unique opportunity to characterize the molecular activities and interactions of these microbial systems at a comprehensive level never before possible. Such information not only provides details about the organizational, functional, and metabolic activities of such systems, but also the untapped reserve of molecular activities that might be invoked and exploited under certain environmental conditions. Since bacteria naturally exist in complex ecosystems, it is imperative to develop and utilize analytical approaches that can provide molecular level details on systems consisting of mixed microbial membership. This is the realm of metaproteomics- the characterization of the complement of proteins expressed by a microbial community in an environmental sample. © 2012 Elsevier Ltd.
Lu X.,University of Tennessee at Knoxville |
Sun K.,Tsinghua University |
Guerrero J.M.,University of Aalborg |
Vasquez J.C.,University of Aalborg |
Huang L.,Tsinghua University
IEEE Transactions on Industrial Electronics | Year: 2014
This paper presents the coordinated control of distributed energy storage systems in dc microgrids. In order to balance the state-of-charge (SoC) of each energy storage unit (ESU), an SoC-based adaptive droop control method is proposed. In this decentralized control method, the droop coefficient is inversely proportional to the $n$th order of SoC. By using a SoC-based droop method, the ESUs with higher SoC deliver more power, whereas the ones with lower SoC deliver less power. Therefore, the energy stored in the ESU with higher SoC decreases faster than that with lower SoC. The SoC difference between each ESU gradually becomes smaller, and finally, the load power is equally shared b