Showing papers by "University of Tennessee published in 2008"

The CMS experiment at the CERN LHC

Abstract: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead-lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosities up to 10(34)cm(-2)s(-1) (10(27)cm(-2)s(-1)). At the core of the CMS detector sits a high-magnetic-field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4 pi solid angle. Forward sampling calorimeters extend the pseudo-rapidity coverage to high values (vertical bar eta vertical bar <= 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t.

Solid‐Solution Phase Formation Rules for Multi‐component Alloys

Abstract: The factors of the atomic size difference Delta and the enthalpy of mixing ΔH mιx of the multi-component alloys were summarized from the literatures. The formation zones of solid-solution phases, intermediate phases, and bulk metallic glasses were determined and the validity was verified by experimental results. For forming the solid solution, the alloys should have high entropy of mixing, lower Delta, and not too negative and positive enthalpy of mixing.

Effects of urbanization on species richness: A review of plants and animals

Abstract: Many studies have described the effects of urbanization on species richness. These studies indicate that urbanization can increase or decrease species richness, depending on several variables. Some of these variables include: taxonomic group, spatial scale of analysis, and intensity of urbanization. Recent reviews of birds (the most-studied group) indicate that species richness decreases with increasing urbanization in most cases but produces no change or even increases richness in some studies. Here I expand beyond the bird studies by reviewing 105 studies on the effects of urbanization on the species richness of non-avian species: mammals, reptiles, amphibians, invertebrates and plants. For all groups, species richness tends to be reduced in areas with extreme urbanization (i.e., central urban core areas). However, the effects of moderate levels of urbanization (i.e., suburban areas) vary significantly among groups. Most of the plant studies (about 65%) indicate increasing species richness with moderate urbanization whereas only a minority of invertebrate studies (about 30%) and a very small minority of non-avian vertebrate studies (about 12%) show increasing species richness. Possible explanations for these results are discussed, including the importance of nonnative species importation, spatial heterogeneity, intermediate disturbance and scale as major factors influencing species richness.

Magnetic order close to superconductivity in the iron-based layered LaO1-xFxFeAs systems

Abstract: Following the discovery of long-range antiferromagnetic order in the parent compounds of high-transition-temperature (high-T(c)) copper oxides, there have been efforts to understand the role of magnetism in the superconductivity that occurs when mobile 'electrons' or 'holes' are doped into the antiferromagnetic parent compounds. Superconductivity in the newly discovered rare-earth iron-based oxide systems ROFeAs (R, rare-earth metal) also arises from either electron or hole doping of their non-superconducting parent compounds. The parent material LaOFeAs is metallic but shows anomalies near 150 K in both resistivity and d.c. magnetic susceptibility. Although optical conductivity and theoretical calculations suggest that LaOFeAs exhibits a spin-density-wave (SDW) instability that is suppressed by doping with electrons to induce superconductivity, there has been no direct evidence of SDW order. Here we report neutron-scattering experiments that demonstrate that LaOFeAs undergoes an abrupt structural distortion below 155 K, changing the symmetry from tetragonal (space group P4/nmm) to monoclinic (space group P112/n) at low temperatures, and then, at approximately 137 K, develops long-range SDW-type antiferromagnetic order with a small moment but simple magnetic structure. Doping the system with fluorine suppresses both the magnetic order and the structural distortion in favour of superconductivity. Therefore, like high-T(c) copper oxides, the superconducting regime in these iron-based materials occurs in close proximity to a long-range-ordered antiferromagnetic ground state.

Media, tasks, and communication processes: a theory of media synchronicity

Abstract: This paper expands, refines, and explicates media synchronicity theory, originally proposed in a conference proceeding in 1999 (Dennis and Valacich 1999). Media synchronicity theory (MST) focuses on the ability of media to support synchronicity, a shared pattern of coordinated behavior among individuals as they work together. We expand on the original propositions of MST to argue that communication is composed of two primary processes: conveyance and convergence. The familiarity of individuals with the tasks they are performing and with their coworkers will also affect the relative amounts of these two processes. Media synchronicity theory proposes that for conveyance processes, use of media supporting lower synchronicity should result in better communication performance. For convergence processes, use of media supporting higher synchronicity should result in better communication performance. We identify five capabilities of media (symbol sets, parallelism, transmission velocity, rehearsability, and reprocessability) that influence the development of synchronicity and thus the successful performance of conveyance and convergence communication processes. The successful completion of most tasks involving more than one individual requires both conveyance and convergence processes, thus communication performance will be improved when individuals use a variety of media to perform a task, rather than just one medium.

The ALICE experiment at the CERN LHC

Abstract: ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries. Its overall dimensions are 161626 m3 with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.

Stream denitrification across biomes and its response to anthropogenic nitrate loading

Abstract: About a quarter of the nitrogen added to the biosphere is exported from rivers to the ocean or inland basins, indicating substantial sinks for nitrogen must exist in the landscape. Data from nitrogen stable isotope tracer experiments across 72 streams suggests that the total uptake of nitrate is related to ecosystem photosynthesis, and that denitrification is related to ecosystem respiration. A stream network model demonstrates that excess nitrate in streams elicits a disproportionate increase in the fraction of nitrate that is exported to receiving waters and reduces the relative role of small versus large streams as nitrate sinks. Anthropogenic addition of bioavailable nitrogen to the biosphere is increasing1,2 and terrestrial ecosystems are becoming increasingly nitrogen-saturated3, causing more bioavailable nitrogen to enter groundwater and surface waters4,5,6. Large-scale nitrogen budgets show that an average of about 20–25 per cent of the nitrogen added to the biosphere is exported from rivers to the ocean or inland basins7,8, indicating that substantial sinks for nitrogen must exist in the landscape9. Streams and rivers may themselves be important sinks for bioavailable nitrogen owing to their hydrological connections with terrestrial systems, high rates of biological activity, and streambed sediment environments that favour microbial denitrification6,10,11. Here we present data from nitrogen stable isotope tracer experiments across 72 streams and 8 regions representing several biomes. We show that total biotic uptake and denitrification of nitrate increase with stream nitrate concentration, but that the efficiency of biotic uptake and denitrification declines as concentration increases, reducing the proportion of in-stream nitrate that is removed from transport. Our data suggest that the total uptake of nitrate is related to ecosystem photosynthesis and that denitrification is related to ecosystem respiration. In addition, we use a stream network model to demonstrate that excess nitrate in streams elicits a disproportionate increase in the fraction of nitrate that is exported to receiving waters and reduces the relative role of small versus large streams as nitrate sinks.

Global supply chain risk management strategies

Abstract: – Global supply chains are more risky than domestic supply chains due to numerous links interconnecting a wide network of firms. These links are prone to disruptions, bankruptcies, breakdowns, macroeconomic and political changes, and disasters leading to higher risks and making risk management difficult. The purpose of this paper is to explore the phenomenon of risk management and risk management strategies in global supply chains., – This paper is based on an extensive literature review and a qualitative study comprising 14 in‐depth interviews and a focus group meeting with senior supply chain executives., – The study provides insights into the applicability of six risk management strategies with respect to environmental conditions and the role of three moderators., – The model is developed in a global manufacturing supply chain context. It should be tested in other contexts and with other methods to provide generalizability. The study takes a much needed step toward building a theory of risk management in global supply chains, which opens important future research directions., – This research provides direction to managers for choosing risk management strategies based on the global supply chain environment. Moderators have practical implications for global supply chain managers., – The paper addresses an identified gap in the literature for selecting risk management strategies in global supply chains. It employs grounded theory, a methodology appropriate for theory‐building, to explore a phenomenon with an inadequate theoretical base.

Consequences of More Extreme Precipitation Regimes for Terrestrial Ecosystems

Abstract: Amplification of the hydrological cycle as a consequence of global warming is forecast to lead to more extreme intra-annual precipitation regimes characterized by larger rainfall events and longer intervals between events. We present a conceptual framework, based on past investigations and ecological theory, for predicting the consequences of this underappreciated aspect of climate change. We consider a broad range of terrestrial ecosystems that vary in their overall water balance. More extreme rainfall regimes are expected to increase the duration and severity of soil water stress in mesic ecosystems as intervals between rainfall events increase. In contrast, xeric ecosystems may exhibit the opposite response to extreme events. Larger but less frequent rainfall events may result in proportional reductions in evaporative losses in xeric systems, and thus may lead to greater soil water availability. Hydric (wetland) ecosystems are predicted to experience reduced periods of anoxia in response to pr...

Global supply chain risk management

Abstract: Highly coordinated flows within and across national boundaries are required for goods, services, information, and cash in global supply chains. The vulnerabilities of, and risks in, complex supply chains are widely acknowleged in literature. The authors attempt to bring together, in order to propose a comprehensive global supply chain risk management and mitigation model, concepts, frameworks, and insights of several disciplines, primarily international business management, strategy, operations management, supply chain management, and logistics. Global supply chain challenges, definitions, risk assessment paradigms, global supply chain uncertainty and risk identification, global supply chain risk assessment, risk management strategies and mitigation plans (and a related model), and managerial and research implications are discussed.

Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity

Abstract: We report density functional calculations of the electronic structure, Fermi surface, phonon spectrum, magnetism, and electron-phonon coupling for the superconducting phase FeSe, as well as the related compounds FeS and FeTe. We find that the Fermi-surface structure of these compounds is very similar to that of the Fe-As based superconductors, with cylindrical electron sections at the zone corner, cylindrical hole surface sections, and depending on the compound, other small hole sections at the zone center. As in the Fe-As based materials, these surfaces are separated by a two-dimensional nesting vector at $(\ensuremath{\pi},\ensuremath{\pi})$. The density of states, nesting, and Fermi-surface size increase, going from FeSe to FeTe. Both FeSe and FeTe show spin-density wave (SDW) ground states, while FeS is close to instability. In a scenario where superconductivity is mediated by spin fluctuations at the SDW nesting vector, the strongest superconductor in this series would be doped FeTe.

Walking, Cycling, and Obesity Rates in Europe, North America, and Australia

Abstract: Purpose: This study was designed to examine the relationship between active transportation (defined as the percentage of trips taken by walking, bicycling, and public transit) and obesity rates (BMI ≥ 30 kg · m−2) in different countries. Methods: National surveys of travel behavior and health indicators in Europe, North America, and Australia were used in this study; the surveys were conducted in 1994 to 2006. In some cases raw data were obtained from national or federal agencies and then analyzed, and in other cases summary data were obtained from published reports. Results: Countries with the highest levels of active transportation generally had the lowest obesity rates. Europeans walked more than United States residents (382 versus 140 km per person per year) and bicycled more (188 versus 40 km per person per year) in 2000. Discussion: Walking and bicycling are far more common in European countries than in the United States, Australia, and Canada. Active transportation is inversely related to obesity in these countries. Although the results do not prove causality, they suggest that active transportation could be one of the factors that explain international differences in obesity rates.

Structural and magnetic phase diagram of CeFeAsO 1− x F x and its relation to high-temperature superconductivity

Abstract: According to a neutron-scattering study of the structural and magnetic properties of the pnictide CeFeAsO1−xFx, the phase diagram of this material shows considerable similarities with the high-Tc cuprate superconductors. These results are an important addition to the effort to find out where superconductivity in these iron–arsenic alloys arises.

Insights from the complete genome sequence of Mycobacterium marinum on the evolution of Mycobacterium tuberculosis

Abstract: Mycobacterium marinum, a ubiquitous pathogen of fish and amphibia, is a near relative of Mycobacterium tuberculosis, the etiologic agent of tuberculosis in humans. The genome of the M strain of M. marinum comprises a 6,636,827-bp circular chromosome with 5424 CDS, 10 prophages, and a 23-kb mercury-resistance plasmid. Prominent features are the very large number of genes (57) encoding polyketide synthases (PKSs) and nonribosomal peptide synthases (NRPSs) and the most extensive repertoire yet reported of the mycobacteria-restricted PE and PPE proteins, and related-ESX secretion systems. Some of the NRPS genes comprise a novel family and seem to have been acquired horizontally. M. marinum is used widely as a model organism to study M. tuberculosis pathogenesis, and genome comparisons confirmed the close genetic relationship between these two species, as they share 3000 orthologs with an average amino acid identity of 85%. Comparisons with the more distantly related Mycobacterium avium subspecies paratuberculosis and Mycobacterium smegmatis reveal how an ancestral generalist mycobacterium evolved into M. tuberculosis and M. marinum. M. tuberculosis has undergone genome downsizing and extensive lateral gene transfer to become a specialized pathogen of humans and other primates without retaining an environmental niche. M. marinum has maintained a large genome so as to retain the capacity for environmental survival while becoming a broad host range pathogen that produces disease strikingly similar to M. tuberculosis. The work described herein provides a foundation for using M. marinum to better understand the determinants of pathogenesis of tuberculosis.

Assessing the organizational social context (OSC) of mental health services: Implications for research and practice.

Abstract: The organizational social context in which mental health services are provided is believed to affect the adoption and implementation of evidence-based practices (EBPs) as well as the quality and outcomes of the services. A fully developed science of implementation effectiveness requires conceptual models that include organizational social context and tools for assessing social context that have been tested in a broad cross-section of mental health systems. This paper describes the role of organizational social context in services and implementation research and evaluates a comprehensive contextual measure, labeled Organizational Social Context (OSC), designed to assess the key latent constructs of culture, climate and work attitudes. The psychometric properties of the OSC measure were assessed in a nationwide study of 1,154 clinicians in 100 mental health clinics with a second-order confirmatory factor analysis of clinician responses, estimates of scale reliabilities, and indices of within-clinic agreement and between-clinic differences among clinicians. Finally, the paper illustrates the use of nationwide norms in describing the OSC profiles of individual mental health clinics and examines the cross-level association of organizational-level culture and climate with clinician-level work attitudes.

The Google generation: the information behaviour of the researcher of the future

Abstract: Purpose – This article is an edited version of a report commissioned by the British Library and JISC to identify how the specialist researchers of the future (those born after 1993) are likely to access and interact with digital resources in five to ten years' time. The purpose is to investigate the impact of digital transition on the information behaviour of the Google Generation and to guide library and information services to anticipate and react to any new or emerging behaviours in the most effective way.Design/methodology/approach – The study was virtually longitudinal and is based on a number of extensive reviews of related literature, survey data mining and a deep log analysis of a British Library and a JISC web site intended for younger people.Findings – The study shows that much of the impact of ICTs on the young has been overestimated. The study claims that although young people demonstrate an apparent ease and familiarity with computers, they rely heavily on search engines, view rather than rea...

Simultaneous MR/PET Imaging of the Human Brain : Feasibility Study

Abstract: The purpose of this study was to apply a magnetic resonance (MR) imaging‐compatible positron emission tomographic (PET) detector technology for simultaneous MR/ PET imaging of the human brain and skull base. The PET detector ring consists of lutetium oxyorthosilicate (LSO) scintillation crystals in combination with avalanche photodiodes (APDs) mounted in a clinical 3-T MR imager with use of the birdcage transmit/receive head coil. Following phantom studies, two patients were simultaneously examined by using fluorine 18 fluorodeoxyglucose (FDG) PET and MR imaging and spectroscopy. MR/PET data enabled accurate coregistration of morphologic and multifunctional information. Simultaneous MR/PET imaging is feasible in humans, opening up new possibilities for the emerging field of molecular imaging. RSNA, 2008

Photoconductivity in BiFeO3 thin films

Abstract: The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17eV, a direct gap (2.667±0.005eV at 300K), and charge transfer excitations at higher energy. Additionally, we report photoconductivity in BiFeO3 films under illumination from a 100mW∕cm2 white light source. A direct correlation is observed between the magnitude of the photoconductivity and postgrowth cooling pressure. Dark conductivities increased by an order of magnitude when comparing films cooled in 760 and 0.1Torr. Large increases in photoconductivity are observed in light.

Agrochemicals increase trematode infections in a declining amphibian species

Abstract: Declining amphibian populations have been reported in the past twenty years from locations all over the world. These events have been attributed variously — often without much evidence — to habitat loss, climate change and disease. Now a case study of the northern leopard frog, Rana pipiens, in wetlands across Minnesota points to the use of agrochemicals — combined with parasitic infestation — as a contributor to population decline. The study sought factors associated with the abundance of larval trematodes in the frogs. An abundance of these parasites can be debilitating, causing limb malformation, kidney damage and death. Of more than 240 plausible predictors of trematode infection — ranging from the presence of various plant and animal species to agrochemicals and habitat geography — two stood out: the herbicide atrazine and the fertilizer, phosphate. Atrazine and phosphate are principal agrochemicals for corn and sorghum production, and together they accounted for 74% of the variation in trematode abundance. Global amphibian declines have often been attributed to disease1,2, but ignorance of the relative importance and mode of action of potential drivers of infection has made it difficult to develop effective remediation. In a field study, here we show that the widely used herbicide, atrazine, was the best predictor (out of more than 240 plausible candidates) of the abundance of larval trematodes (parasitic flatworms) in the declining northern leopard frog Rana pipiens. The effects of atrazine were consistent across trematode taxa. The combination of atrazine and phosphate—principal agrochemicals in global corn and sorghum production—accounted for 74% of the variation in the abundance of these often debilitating larval trematodes (atrazine alone accounted for 51%). Analysis of field data supported a causal mechanism whereby both agrochemicals increase exposure and susceptibility to larval trematodes by augmenting snail intermediate hosts and suppressing amphibian immunity. A mesocosm experiment demonstrated that, relative to control tanks, atrazine tanks had immunosuppressed tadpoles, had significantly more attached algae and snails, and had tadpoles with elevated trematode loads, further supporting a causal relationship between atrazine and elevated trematode infections in amphibians. These results raise concerns about the role of atrazine and phosphate in amphibian declines, and illustrate the value of quantifying the relative importance of several possible drivers of disease risk while determining the mechanisms by which they facilitate disease emergence.

Audit Quality and Properties of Analyst Earnings Forecasts

Abstract: Under the assumption that audit quality relates positively to unobservable financial reporting quality, we investigate whether audit quality is associated with the predictability of accounting earnings by focusing on analyst earnings forecast properties. The evidence shows that analysts' earnings forecast accuracy is higher and the forecast dispersion is smaller for firms audited by a Big 5 auditor. We further find that auditor industry specialization is associated with higher forecast accuracy and less forecast dispersion in the non‐Big 5 auditor sample but not in the Big 5 auditor sample. Overall, our results suggest that high‐quality audit provided by Big 5 auditors and industry specialist non‐Big 5 auditors is associated with better forecasting performance by analysts.

Calcium as the superior coating metal in functionalization of carbon fullerenes for high-capacity hydrogen storage.

Abstract: We explore theoretically the feasibility of functionalizing carbon nanostructures for hydrogen storage, focusing on the coating of C60 fullerenes with light alkaline-earth metals. Our first-principles density functional theory studies show that both Ca and Sr can bind strongly to the C60 surface, and highly prefer monolayer coating, thereby explaining existing experimental observations. The strong binding is attributed to an intriguing charge transfer mechanism involving the empty d levels of the metal elements. The charge redistribution, in turn, gives rise to electric fields surrounding the coated fullerenes, which can now function as ideal molecular hydrogen attractors. With a hydrogen uptake of >8.4 wt % on Ca32C60, Ca is superior to all the recently suggested metal coating elements.

Clinical practice as natural laboratory for psychotherapy research: a guide to case-based time-series analysis.

Abstract: Both researchers and practitioners need to know more about how laboratory treatment protocols translate to real-world practice settings and how clinical innovations can be systematically tested and communicated to a skeptical scientific community. The single-case time-series study is well suited to opening a productive discourse between practice and laboratory. The appeal of case-based time-series studies, with multiple observations both before and after treatment, is that they enrich our design palette by providing the discipline another way to expand its empirical reach to practice settings and its subject matter to the contingencies of individual change. This article is a user's guide to conducting empirically respectable case-based time-series studies in a clinical practice or laboratory setting.

Initial review of methods for cascading failure analysis in electric power transmission systems IEEE PES CAMS task force on understanding, prediction, mitigation and restoration of cascading failures

Abstract: Large blackouts are typically caused by cascading failure propagating through a power system by means of a variety of processes. Because of the wide range of time scales, multiple interacting processes, and the huge number of possible interactions, the simulation and analysis of cascading blackouts is extremely complicated. This paper defines cascading failure for blackouts and gives an initial review of the current understanding, industrial tools, and the challenges and emerging methods of analysis and simulation.

Surface-enhanced Raman spectroscopy substrates created via electron beam lithography and nanotransfer printing.

Abstract: The development of quantitative, highly sensitive surface-enhanced Raman spectroscopy (SERS) substrates requires control over size, shape, and position of metal nanoparticles. Despite the fact that SERS has gained the reputation as an information-rich spectroscopy for detection of many classes of analytes, in some isolated instances down to the single molecule detection limit, its future development depends critically on techniques for nanofabrication. Herein, an unconventional nanofabrication approach is used to produce efficient SERS substrates. Metallic nanopatterns of silver disks are transferred from a stamp onto poly(dimethysiloxane) (PDMS) to create nanocomposite substrates with regular periodic morphologies. The stamp with periodic arrays of square, triangular, and elliptical pillars is created via electron beam lithography (EBL) of ma-N 2403 resist. A modified cyclodextrin is thermally evaporated onto the stamp to overcome the adhesive nature of the EBL resist and to function as a releasing layer...