Louisiana State University and Agricultural and Mechanical College is a public coeducational university located in Baton Rouge, Louisiana. The University was founded in 1853 in what is now known as Pineville, Louisiana, under the name Louisiana State Seminary of Learning & Military Academy. The current LSU main campus was dedicated in 1926, and consists of more than 250 buildings constructed in the style of Italian Renaissance architect Andrea Palladio, and occupies a 650-acre plateau on the banks of the Mississippi River.LSU is the flagship institution of the Louisiana State University System, and the largest institution of higher education in Louisiana in terms of student enrollment. In 2011, the University enrolled nearly 24,000 undergraduate and over 5,000 graduate students in 14 schools and colleges. Several of LSU's graduate schools, such as the E.J. Ourso College of Business and the Paul M. Hebert Law Center, have received national recognition in their respective fields of study. Designated as a land-grant, sea-grant and space-grant institution, LSU is also noted for its extensive research facilities, operating some 800 sponsored research projects funded by agencies such as the National Institutes of Health, the National Science Foundation, the National Endowment for the Humanities, and the National Aeronautics and Space Administration.LSU's athletics department fields teams in 21 varsity sports , and is a member of the NCAA and the SEC . The University is represented by its mascot, Mike the Tiger. Wikipedia.
Matthews R.A.,Louisiana State University |
Barnes-Farrell J.L.,University of Connecticut
Journal of Occupational Health Psychology | Year: 2010
This manuscript reports the development of a measure of work and family domain boundary flexibility. Building on previous research, we propose an expanded definition of boundary flexibility that includes two components-flexibility-ability and flexibility-willingness-and we develop a measure designed to capture this more comprehensive definition of boundary flexibility. Flexibility-ability is conceptualized as an individual's perception of personal and situational constraints that affect boundary management, and flexibility-willingness is conceptualized as an individual difference variable that captures the motivation to engage in boundary flexing. An additional feature of domain boundaries, permeability, is also examined. Data are presented from two studies. Study 1 (N = 244) describes the development of a multiscale measure that extends current conceptual definitions of boundary flexibility. Study 2 (N = 225) describes the refinement and evaluation of this measure. Confirmatory factor analysis, reliability evidence, interscale correlations, and correlations with important work-family constructs (e.g., domain centrality, work-family conflict) provide initial construct validity evidence for the measure. © 2010 American Psychological Association.
Shikhaliev P.M.,Louisiana State University
Physics in Medicine and Biology | Year: 2012
As x-ray imaging technology moves from conventional radiography and computed tomography (CT) to spectral radiography and CT, dedicated phantom materials are needed for spectral imaging. The spectral phantom materials should accurately represent the energy-dependent mass-attenuation coefficients of different types of tissues. Although tissue-equivalent phantom materials were previously developed for CT and radiation therapy applications, these materials are suboptimal for spectral radiography and CT; they are not compatible with contrast agents, do not represent many of the tissue types and do not provide accurate values of attenuation characteristics of tissue. This work provides theoretical framework and a practical method for developing tissue-equivalent spectral phantom materials with a required set of parameters. The samples of the tissue-equivalent spectral phantom materials were developed, tested and characterized. The spectral phantom materials were mixed with iodine, gold and calcium contrast agents and evaluated. The materials were characterized by CT imaging and x-ray transmission experiments. The fabricated materials had nearly identical densities, mass attenuation coefficients, effective atomic numbers and electron densities as compared to corresponding tissue materials presented in the ICRU-44 report. The experimental results have shown good volume uniformity and inter-sample uniformity (repeatability of sample fabrication) of the fabricated materials. The spectral phantom materials were fabricated under laboratory conditions from readily available and inexpensive components. It was concluded that the presented theoretical framework and fabrication method of dedicated spectral phantom materials could be useful for researchers and developers working in the new area of spectral radiography and CT. Independently, the results could also be useful for other applications, such as radiation therapy. © 2012 Institute of Physics and Engineering in Medicine.
Obrosova I.G.,Louisiana State University |
Kador P.F.,University of Nebraska Medical Center
Current Pharmaceutical Biotechnology | Year: 2011
Diabetic retinopathy is the most common microvascular complication of diabetes and the most severe of diabetic ocular complications. This review describes retinal changes at different stages of diabetic retinopathy and risk factors associated with this devastating disease. Special attention is focused on aldose reductase, the first enzyme of the sor-bitol pathway of glucose metabolism. The current knowledge on the enzyme localization in the retina, and the role for increased aldose reductase activity in retinal capillary cell loss and formation of acellular capillaries, capillary basement membrane thickening, increased vascular permeability and disruption of blood-retinal barrier, and increased leukocyte adhesion to endothelial cells associated with early diabetic retinopathy, as well as neovascularization associated with advanced (proliferative) diabetic retinopathy, gained through the experimental studies in animal models of diabetes and ga-lactose feeding, is described in detail. The review also analyzes the potential mechanisms underlying aldose reductase involvement in pathogenesis of diabetic retinopathy, and discusses interactions between aldose reductase and other patho-genetic factors such as formation of advanced glycation end-products, oxidative-nitrosative stress, protein kinase C, mito-gen-activated protein kinase, and poly(ADP-ribose) polymerase activations, inflammation, and growth factor imbalances. A detailed analysis of clinical diabetic retinopathy trials of aldose reductase inhibitors is also provided. © 2011 Bentham Science Publishers Ltd.
Dixit V.D.,Louisiana State University
Current Opinion in Immunology | Year: 2010
With advancing age, the thymus undergoes striking fibrotic and fatty changes that culminate in its transformation into adipose tissue. As the thymus involutes, reduction in thymocytes and thymic epithelial cells precede the emergence of mature lipid-laden adipocytes. Dogma dictates that adipocytes are 'passive' cells that occupy non-epithelial thymic space or 'infiltrate' the non-cellular thymic niches. The provenance and purpose of ectopic thymic adipocytes during aging in an organ that is required for establishment and maintenance of T cell repertoire remains an unsolved puzzle. Nonetheless, tantalizing clues about elaborate reciprocal relationship between thymic fatness and thymopoietic fitness are emerging. Blocking or bypassing the route toward thymic adiposity may complement the approaches to rejuvenate thymopoiesis and immunity in elderly. © 2010 Elsevier Ltd.
Williamson G.B.,Louisiana State University |
Wiemann M.C.,U.S. Department of Agriculture
American Journal of Botany | Year: 2010
The specific gravity (SG) of wood is a measure of the amount of structural material a tree species allocates to support and strength. In recent years, wood specific gravity, traditionally a forester' s variable, has become the domain of ecologists exploring the universality of plant functional traits and conservationists estimating global carbon stocks. While these developments have expanded our knowledge and sample of woods, the methodologies employed to measure wood SG have not received as much scrutiny as SG' s ecological importance. Here, we reiterate some of the basic principles and methods for measuring the SG of wood to clarify past practices of foresters and ecologists and to identify some of the prominent errors in recent studies and their consequences. In particular, we identify errors in (1) extracting wood samples that are not representative of tree wood, (2) differentiating wood specific gravity from wood density, (3) drying wood samples at temperatures below 100 ° C and the resulting moisture content complications, and (4) improperly measuring wood volumes. In addition, we introduce a new experimental technique, using applied calculus, for estimating SG when the form of radial variation is known, a method that significantly reduces the effort required to sample a tree' s wood. © 2010 Botanical Society of America.
Kaufman H.E.,Louisiana State University
Cornea | Year: 2013
PURPOSE:: To evaluate the importance and practicality of testing for matrix metalloproteinase 9 (MMP-9) in dry eye and ocular surface disease. This enzyme, which can cause tissue damage, seems also to be the most reliable diagnostic indicator of ocular surface disease. METHODS:: Enzyme-linked immunosorbent assay, polymerase chain reaction, diffusion, and InflammaDry, a new rapid immunoassay by RPS (Rapid Pathogen Screening Inc). RESULTS:: MMP-9 measurement is sensitive and accurate for diagnosing dry eye and ocular surface disease and compares favorably in both sensitivity and specificity against the existing methods of dry eye diagnosis. Abnormal elevations of MMP-9 may predict post-laser in situ keratomileusis complications and refractive complications such as epithelial ingrowth and corneal ulceration. The presence of elevated MMP-9 on the ocular surface will identify those patients who should receive antiinflammatory therapy, such as cyclosporine, and may predict those patients who will respond to this therapy. CONCLUSIONS:: A rapid in-office test that is sensitive for identifying inflammatory dry eye and ocular surface disease may facilitate better preoperative management of the ocular surface. Optimization of the ocular surface perioperatively would be expected to reduce complications from laser in situ keratomileusis and other surgeries that often make the underlying disease worse. This test may also indicate the need for antiinflammatory therapies, such as cyclosporine or steroids, and also may predict those patients who are more likely to respond. Copyright © 2012 by Lippincott Williams & Wilkins.
Schoegl I.,Louisiana State University
Combustion and Flame | Year: 2012
This study investigates the impact of radiative heat transfer on the behavior of flat flame burners within the framework of a simplified one-dimensional model. Flat flame burners stabilize planar premixed flames downstream of a porous plug. Within this study, the porous plug is modeled as a thermally conducting, optically thick medium, allowing for both conductive and radiative heat transfer. Based on the simplified model, the impact of radiative heat exchange between the porous plug exit and the downstream environment is investigated. In " surface" combustion, flame stabilization occurs due to heat transfer between gas phase and porous solid. Results demonstrate that radiative heat transfer from a hot downstream environment to the porous plug significantly increases maximum attainable mass fluxes. For a cold downstream environment, plug properties do not affect the maximum supportable mass flux, although plug porosity and heat transfer between gas and solid have a significant impact on the " stand-off" distance between flame and plug exit. In addition, the model provides insight to a second " submerged" combustion mode, where the flame is stabilized within the porous plug of the burner. Here, increased flame temperatures lead to a dramatic increase of the maximum supportable mass flux. Overall, results show that radiative heat losses play a critical role in both combustion modes: in surface combustion, they are an important mode of heat dissipation, where they can prevent " flash-back" conditions with the flame moving into the porous matrix; in submerged combustion, they prevent flame stabilization close to inlet and exit faces and enable a " slow" solution branch that does not exist without radiative losses. © 2012.
Nelms B.E.,Louisiana State University
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2010
Electronic portal imaging devices (EPIDs) could potentially be useful for intensity-modulated radiation therapy (IMRT) QA. The data density, high resolution, large active area, and efficiency of the MV EPID make it an attractive option. However, EPIDs were designed as imaging devices, not dosimeters, and as a result they do not inherently measure dose in tissue equivalent media. EPIDose (Sun Nuclear, Melbourne, FL) is a tool designed for the use of EPIDs in IMRT QA that uses raw MV EPID images (no additional build-up and independent of gantry angle, but with dark and flood field corrections applied) to estimate absolute dose planes normal to the beam axis in a homogeneous media (i.e. similar to conventional IMRT QA methods). However, because of the inherent challenges of the EPID-based dosimetry, validating and commissioning such a system must be done very carefully, by exploring the range of use cases and using well-proven "standards" for comparison. In this work, a multi-institutional study was performed to verify accurate EPID image to dose plane conversion over a variety of conditions. Converted EPID images were compared to 2D diode array absolute dose measurements for 188 fields from 28 clinical IMRT treatment plans. These plans were generated using a number of commercially available treatment planning systems (TPS) covering various treatment sites including prostate, head and neck, brain, and lung. The data included three beam energies (6, 10, and 15 MV) and both step-and-shoot and dynamic MLC fields. Out of 26,207 points of comparison over 188 fields analyzed, the average overall field pass rate was 99.7% when 3 mm/3% DTA criteria were used (range 94.0-100 per field). The pass rates for more stringent criteria were 97.8% for 2mm/2% DTA (range 82.0-100 per field), and 84.6% for 1 mm/1% DTA (range 54.7-100 per field). Individual patient-specific sites as well, as different beam energies, followed similar trends to the overall pass rates.
Wright R.A.,Louisiana State University |
McCurdy B.L.,Devereux Center for Effective Schools
Journal of Positive Behavior Interventions | Year: 2012
The Good Behavior Game (GBG) is a powerful group contingency with a history of documented empirical support. The purpose of this study was to compare two interdependent group contingencies, the GBG and a positive variation, the Caught Being Good Game (CBGG), in a school implementing school-wide positive behavior support. A kindergarten and fourth-grade classroom teacher with 17 and 20 students, respectively, implemented both versions of the game in a counterbalanced fashion. Using a withdrawal design, results showed similar effects on disruptive and on-task behaviors. The CBGG is discussed as an effective variation of the GBG that is acceptable to both teachers and students. © 2011 Hammill Institute on Disabilities.
Carstens B.C.,Louisiana State University |
Dewey T.A.,University of Michigan
Systematic Biology | Year: 2010
Coalescent model-based methods for phylogeny estimation force systematists to confront issues related to the identification of species boundaries. Unlike conventional phylogenetic analysis, where species membership can be assessed qualitatively after the phylogeny is estimated, the phylogenies that are estimated under a coalescent model treat aggregates of individuals as the operational taxonomic units and thus require a priori definition of these sets because the models assume that the alleles in a given lineage are sampled from a single panmictic population. Fortunately, the use of coalescent model-based approaches allows systematists to conduct probabilistic tests of species limits by calculating the probability of competing models of lineage composition. Here, we conduct the first exploration of the issues related to applying such tests to a complex empirical system. Sequence data from multiple loci were used to assess species limits and phylogeny in a clade of North American Myotis bats. After estimating gene trees at each locus, the likelihood of models representing all hierarchical permutations of lineage composition was calculated and Akaike information criterion scores were computed. Metrics borrowed from information theory suggest that there is strong support for several models that include multiple evolutionary lineages within the currently described species Myotis lucifugus and M. evotis. Although these results are preliminary, they illustrate the practical importance of coupled species delimitation and phylogeny estimation. © The Author(s) 2010.
Proctor S.L.,Louisiana State University
Mental Health and Substance Use: Dual Diagnosis | Year: 2012
The co-occurrence of substance use disorders (SUDs) and posttraumatic stress disorder (PTSD) is prevalent among inmates and is associated with numerous adverse outcomes. The present study sought to estimate the prevalence and patterns of co-occurring PTSD among substance-dependent inmates. Structured diagnostic assessment interview data from 176 adult male inmates incarcerated in a local jail facility were analyzed to assess study aims. Alcohol dependence was the most prevalent SUD with 81.3% of the total sample meeting current Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria. The remaining substance dependence diagnoses that predominated were as follows: cocaine, 35.2%; marijuana, 21.0%; heroin, 15.5%; and stimulant, 6.8%. Over half (54.6%) met diagnostic criteria for PTSD. A bimodal distribution was found for the PTSD cases as inmates tended to report either no symptoms or sub-diagnostic indications (45.4%), or acknowledge sufficient information to substantiate a severe diagnostic grouping (41.5%). Bivariate correlations between the symptom count for PTSD and the seven dependence criteria for the various substance dependence categories revealed several significant findings. Of particular interest were the negative correlations of alcohol dependence symptoms with those of cocaine (r=.230, p<.01) and heroin (r=.176, p<.05). PTSD severity was associated with higher symptom counts for marijuana (r=.244, p<.01) and cocaine (r=.233, p<.01) dependence. The design and implementation of SUD treatment programs for inmates must consider other co-occurring mental health issues as well and incorporate treatment techniques that address the symptoms associated with PTSD. © 2012 Copyright Taylor and Francis Group, LLC.
Brumfield R.T.,Louisiana State University
Molecular Ecology | Year: 2010
The negative effects of human-induced habitat disturbance and modification on multiple dimensions of biological diversity are well chronicled (Turner 1996; Harding 1998; Lawton 1998; Sakai 2001). Among the more insidious consequences is secondary contact between formerly allopatric taxa (Anderson & Hubricht 1938; Perry 2002; Seehausen 2006). How the secondary contact will play out is unpredictable (Ellstrand 2010), but if the taxa are not fully reproductively isolated, hybridization is likely, and if the resulting progeny are fertile, the eventual outcome is often devastating from a conservation perspective (Rhymer & Simberloff 1996; Wolf 2001; McDonald 2008). In this issue of Molecular Ecology, Steeves (2010) present an analysis of hybridization between two avian species, one of which is critically endangered and the other of which is invasive. Their discovery that the endangered species has not yet been hybridized to extinction is promising and not what one would necessarily expect from theory. © 2010 Blackwell Publishing Ltd.
Green P.T.,La Trobe University |
Green P.T.,A+ Network |
Harms K.E.,Louisiana State University |
Connell J.H.,University of California at Santa Barbara
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014
A variety of ecological processes influence diversity and species composition in natural communities. Most of these processes, whether abiotic or biotic, differentially filter individuals from birth to death, thereby altering species' relative abundances. Nonrandom outcomes could accrue throughout ontogeny, or the processes that generate them could be particularly influential at certain stages. One long-standing paradigm in tropical forest ecology holds that patterns of relative abundance among mature trees are largely set by processes operating at the earliest life cycle stages. Several studies confirm filtering processes at some stages, but the longevity of large trees makes a rigorous comparison across size classes impossible without long-term demographic data. Here, we use one of the world's longest-running, plot-based forest dynamics projects to compare nonrandom outcomes across stage classes. We considered a cohort of 7,977 individuals in 186 species that were alive in 1971 and monitored in 13 mortality censuses over 42 y to 2013. Nonrandom mortality with respect to species identity occurred more often in the smaller rather than the larger size classes. Furthermore, observed nonrandom mortality in the smaller size classes had a diversifying influence; species richness of the survivors was up to 30% greater than expected in the two smallest size classes, but not greater than expected in the larger size classes. These results highlight the importance of early life cycle stages in tropical forest community dynamics. More generally, they add to an accumulating body of evidence for the importance of early-stage nonrandom outcomes to community structure in marine and terrestrial environments. © 2014, National Academy of Sciences. All rights reserved.
Klasser G.D.,Louisiana State University
Journal (Canadian Dental Association) | Year: 2011
Burning mouth syndrome is an enigmatic condition that can be difficult to recognize and diagnose. Dental practitioners must be able to distinguish between primary (essential or idiopathic) and secondary burning mouth syndrome. The primary form is characterized by a burning sensation in the oral mucosa and perioral areas, typically with bilateral, symmetric distribution and an absence of relevant clinical and laboratory findings. In the secondary form, the burning sensation is due to clinical abnormalities or a systemic or psychological condition. To date, primary burning mouth syndrome has been considered a diagnosis of exclusion. A case description of a woman with oral burning sensations and the results of a retrospective case analysis are presented to aid practitioners in the understanding, recognition and diagnosis of primary burning mouth syndrome.
Reeve J.D.,Southern Illinois University Carbondale |
Cronin J.T.,Louisiana State University
Journal of Animal Ecology | Year: 2010
1. Changes in the density of an organismnear a boundary elements (edge effects) are often thought to be generated by changes in movement behaviour, but in most cases the mechanism underlying these effects is unknown. 2. We quantified the movement behaviour of a minute parasitic wasp, Anagrus columbi, in relation to edges in its habitat. This wasp attacks eggs of the planthopper Prokelisia crocea, which inhabits a wet prairie ecosystem composed of patches of its host plant prairie cordgrass (Spartina pectinata) interspersed within a matrix of mudflat, smooth brome (Bromus inermis) and native grasses. Two edge types are common in this system, cordgrass-mudflat and cordgrass-brome. 3. We conducted mark-recapture experiments in which wasps were released at the cordgrassmatrix edge and 50 cm within cordgrass or matrix, for both edge types. The marked wasps were recaptured using a grid of sticky traps. We fitted an advection-diffusion model to these data, yielding estimates of the diffusion rate and advection coefficient for cordgrass and matrix, for each release position and edge type. 4. The spatial distribution of wasps was well-described by the advection-diffusion model. The pattern suggests that marked wasps strongly biased their movements towards the edge when released in matrix, and to a lesser extent when released in cordgrass, while edge releases showed little bias. The advection coefficients were similar for the two edge types, as were the diffusion rates for the three substrates (cordgrass, brome, mudflat). The diffusive and advective components of movement were of comparable magnitude for matrix and cordgrass releases, suggesting equal amounts of directed and random movement. 5. Our results suggest the wasps are attracted to cordgrass patches across short distances, and that bias in their movements may concentrate them at the patch edge. Their edge behaviour is qualitatively different fromthat of the host insect. 6. The methodology described here could be readily adapted to other systems, where direct observations of movement are difficult but mark-recapture studies are feasible. ©2009 The Authors. Journal compilation ©2009 British Ecological Society.
Berthoud H.-R.,Louisiana State University
Proceedings of the Nutrition Society | Year: 2012
The objective of this non-systematic review of the literature is to highlight some of the neural systems and pathways that are affected by the various intake-promoting aspects of the modern food environment and explore potential modes of interaction between core systems such as hypothalamus and brainstem primarily receptive to internal signals of fuel availability and forebrain areas such as the cortex, amygdala and meso-corticolimbic dopamine system, primarily processing external signals. The modern lifestyle with its drastic changes in the way we eat and move puts pressure on the homoeostatic system responsible for the regulation of body weight, which has led to an increase in overweight and obesity. The power of food cues targeting susceptible emotions and cognitive brain functions, particularly of children and adolescents, is increasingly exploited by modern neuromarketing tools. Increased intake of energy-dense foods high in fat and sugar is not only adding more energy, but may also corrupt neural functions of brain systems involved in nutrient sensing as well as in hedonic, motivational and cognitive processing. It is concluded that only long-term prospective studies in human subjects and animal models with the capacity to demonstrate sustained over-eating and development of obesity are necessary to identify the critical environmental factors as well as the underlying neural systems involved. Insights from these studies and from modern neuromarketing research should be increasingly used to promote consumption of healthy foods. © The Author 2012.
Pagnotta A.,American Museum of Natural History |
Schaefer B.E.,Louisiana State University
Astrophysical Journal | Year: 2014
Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called CNe are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our Galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a Galactic, time-limited sample of 237 CNe and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (1) outburst amplitude smaller than 14.5-4.5 × log (t 3), (2) orbital period >0.6 days, (3) infrared colors of J-H > 0.7 mag and H-K > 0.1 mag, (4) FWHM of Hα > 2000 km s-1, (5) high excitation lines, such as Fe X or He II near peak, (6) eruption light curves with a plateau, and (7) white dwarf mass greater than 1.2 M Ȯ. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction among the known CNe using three methods to get 24% ± 4%, 12% ± 3%, and 35% ± 3%. With roughly a quarter of the 394 known Galactic novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe. © 2014. The American Astronomical Society. All rights reserved..
Bray G.A.,Louisiana State University
Advances in Nutrition | Year: 2013
Sugar intake in the United States has increased by >40 fold since the American Revolution. The health concerns that have been raised about the amounts of sugar that are in the current diet, primarily as beverages, are the subject of this review. Just less than 50% of the added sugars (sugar and high-fructose corn syrup) are found in soft drinks and fruit drinks. The intake of soft drinks has increased 5-fold between 1950 and 2000. Most meta-analyses have shown that the risk of obesity, diabetes, cardiovascular disease, and metabolic syndrome are related to consumption of beverages sweetened with sugar or high-fructose corn syrup. Calorically sweetened beverage intake has also been related to the risk of nonalcoholic fatty liver disease, and, in men, gout. Calorically sweetened beverages contribute to obesity through their caloric load, and the intake of beverages does not produce a corresponding reduction in the intake of other food, suggesting that beverage calories are "add-on" calories. The increase in plasma triglyceride concentrations by sugar-sweetened beverages can be attributed to fructose rather than glucose in sugar. Several randomized trials of sugar-containing soft drinks versus low-calorie or calorie-free beverages show that either sugar, 50% of which is fructose, or fructose alone increases triglycerides, body weight, visceral adipose tissue, muscle fat, and liver fat. Fructose is metabolized primarily in the liver. When it is taken up by the liver, ATP decreases rapidly as the phosphate is transferred to fructose in a form that makes it easy to convert to lipid precursors. Fructose intake enhances lipogenesis and the production of uric acid. By worsening blood lipids, contributing to obesity, diabetes, fatty liver, and gout, fructose in the amounts currently consumed is hazardous to the health of some people. © 2013 American Society for Nutrition.
Shikhaliev P.M.,Louisiana State University
Physics in Medicine and Biology | Year: 2010
The aim of the study is to determine the upper limits of the signal-tonoise ratio (SNR) in radiography and computed tomography (CT) with polyenergetic x-ray sources. In x-ray imaging, monoenergetic x-rays provide a higher SNR compared to polyenergetic x-rays. However, the SNR in polyenergetic x-ray imaging can be increased when a photon-counting detector is used and x-rays are optimally weighted according to their energies. For a particular contrast/background combination and at a fixed x-ray entrance skin exposure, the SNR in energy-weighting x-ray imaging depends on tube voltage and can be maximized by selecting the optimal tube voltage. The SNR in energy-weighted x-ray images acquired at this optimal tube voltage is the highest SNR that can be achieved with polyenergetic x-ray sources. The optimal tube voltages and the highest SNR were calculated and compared to the SNR of monoenergetic x-ray imaging. Monoenergetic, energy-weighting polyenergetic and energy-integrating polyenergetic x-ray imagings were simulated at a fixed entrance skin exposure of 20 mR. The tube voltages varied in the range of 30-140 kVp with 10 kV steps. Contrast elements of CaCO3, iodine, adipose and tumor with thicknesses of 280 mg cm-2, 15 mg cm-2, 1 g cm -2 and 1 g cm-2, respectively, inserted in a soft tissue background with 10 cm and 20 cm thicknesses, were used. The energy weighting also improves the contrast-to-noise ratio (CNR) in CT when monoenergetic CT projections are optimally weighted prior to CT reconstruction (projection-based weighting). Alternatively, monoenergetic CT images are reconstructed, optimally weighted and composed to yield a final CT image (image-based weighting). Both projection-based and image-based weighting methods improve the CNR in CT. An analytical approach was used to determine which of these two weighting methods provides the upper limit of the CNR in CT. The energy-weighting method was generalized and expanded as a weighting method applicable in areas other than x-ray and CT. An optimal xray tube voltage providing the highest SNR in energy-weighting x-ray imaging © 2010 Institute of Physics and Engineering in Medicine.
Kaiser M.J.,Louisiana State University |
Liu M.,China University of Petroleum - Beijing
Marine Structures | Year: 2014
Decommissioning is the final stage in the life cycle of an offshore structure, where all wells are plugged and abandoned, the platform and associated facilities are removed, and the seafloor cleared of all obstructions created by the operations. From 1989 to 2012, 15 structures in water depth greater than 400ft were decommissioned in the U.S. Gulf of Mexico, but none of the project cost have been publicly released. The purpose of this paper is to apply work decomposition algorithms developed by ProServ Offshore to estimate cost for well plugging and abandonment, conductor severance and removal, pipeline abandonment, umbilical and flowline removal, and platform removal for the 53 deepwater fixed platforms and compliant towers in the Gulf of Mexico circa January 2013. Decommissioning cost estimates are presented by stage and operator. Bullwinkle and Pompano are expected to be the most expensive fixed platform decommissioning projects in the Gulf of Mexico estimated at $265 million and $203 million, respectively. Total undiscounted decommissioning liability for the asset class is estimated to be $2.4 billion. © 2014 Elsevier Ltd.
Schaefer B.E.,Louisiana State University
Astrophysical Journal | Year: 2011
I report on the cumulative results from a program started 24 years ago designed to measure the orbital period change of recurrent novae (RNe) across an eruption. The goal is to use the orbital period change to measure the mass ejected during each eruption as the key part of trying to measure whether the RNe white dwarfs are gaining or losing mass over an entire eruption cycle, and hence whether they can be progenitors for Type Ia supernovae. This program has now been completed for two eclipsing RNe: CI Aquilae (CIAql) across its eruption in 2000 and UScorpii (USco) across its eruption in 1999. For CIAql, I present 78 eclipse times from 1991 to 2009 (including four during the tail of the 2000 eruption) plus two eclipses from 1926 and 1935. For USco, I present 67 eclipse times, including 46 times during quiescence from 1989 to 2009, plus 21 eclipse times in the tails of the 1945, 1999, and 2010 eruptions. The eclipse times during the tails of eruptions are systematically and substantially shifted with respect to the ephemerides from the eclipses in quiescence, with this being caused by shifts of the center of light during the eruption. These eclipse times are plotted on an O - C diagram and fitted to models with a steady period change () between eruptions (caused by, for example, conservative mass transfer) plus an abrupt period change (ΔP) at the time of eruption. The primary uncertainty arises from the correlation between ΔP with , such that a more negative makes for a more positive ΔP. For CIAql, the best fit is ΔP = -3.7+9.2 -7.3 × 10-7. For USco, the best fit is ΔP = (+43 ± 69) × 10-7days. These period changes can directly give a dynamical measure of the mass ejected (Mejecta) during each eruption with negligible sensitivity to the stellar masses and no uncertainty from distances. For CIAql, the 1σ upper limit is Mejecta < 10 × 10-7 M⊙. For USco, I derive Mejecta = (43 ± 67) × 10-7 M⊙. © 2011. The American Astronomical Society. All rights reserved.
Yang M.-Y.,Louisiana State University
Child Abuse and Neglect | Year: 2015
This study employs four waves of survey data on 1,135 families from the Illinois Families Study, a longitudinal panel study of Temporary Assistance for Needy Families in Illinois. This study explores the following issues within this low-income population: (1) whether material hardships are associated with child protective services (CPS) investigations, (2) whether the effect of material hardship on CPS differs by the type of child maltreatment investigated, and (3) whether psychological distress mediates the association between material hardship and CPS involvement. Results from pooled and fixed effects logistic regressions suggest that caregivers who experience material hardship are more likely to become involved in CPS. In general, investigated neglect reports are responsive to particular types of hardship such as housing and food, while investigated physical abuse reports are responsive to levels of hardship regardless of specific types. The association between material hardship and CPS involvement is not fully explained by depressive symptoms or parenting stress. The study results suggest that in order to prevent child maltreatment, it may be necessary to address a family's unmet material needs through economic support interventions. © 2014 Elsevier Ltd.
Singh P.,Louisiana State University
Classical and Quantum Gravity | Year: 2012
A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations provided insights into the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed. © 2012 IOP Publishing Ltd.
Wan X.,Louisiana State University
Journal of Computational Physics | Year: 2013
In this work, we develop a parallel minimum action method for small random perturbations of Navier-Stokes equations to solve the optimization problem given by the large deviation theory. The Freidlin-Wentzell action functional is discretized by hp finite elements in time direction and spectral methods in physical space. A simple diagonal preconditioner is constructed for the nonlinear conjugate gradient solver of the optimization problem. A hybrid parallel strategy based on MPI and OpenMP is developed to improve numerical efficiency. Both h- and p-convergence are obtained when the discretization error from physical space can be neglected. We also present preliminary results for the transition in two-dimensional Poiseuille flow from the base flow to a non-attenuated traveling wave. © 2012 Elsevier Inc.
Schaefer B.E.,Louisiana State University
Astrophysical Journal, Supplement Series | Year: 2010
I collect virtually all photometry of the 10 known galactic recurrent novae (RNe) and their 37 known eruptions. This consists of my modern measures of nearly all archival plates (providing the only data for half of 37 known eruptions), my own 10,000 CCD magnitudes from 1987 to present (providing virtually all of the magnitudes in quiescence for seven RNe), over 140,000 visual magnitude estimates recorded by amateur astronomers (who discovered half the known eruptions), and the small scattering of magnitudes from all the literature. From this, I produce various uniform products: (1) BVRIJHK comparison star magnitudes and BV comparison star sequences to cover the entire range of eruption; (2) complete light curves for all eruptions; (3) best-fit B and V light curve templates; (4) orbital periods for all but one RN; (5) exhaustive searches for all missed eruptions; (6) measured discovery efficiencies since 1890; (7) true recurrence time scales; (8) predicted next eruption dates; (9) variations on time scales of minutes, hours, days, months, years, decades, and century; (10) uniform distances and extinctions to all RNe; (11) BV colors at peak and UBVRIJHK colors at minimum, all with extinction corrections; and (12) the spectral energy distributions over UBVRIJHK. Highlights of this work include the discoveries of one new RN, six previously unknown eruptions, and the orbital periods for half the RNe. The goal of this work is to provide uniform demographics for answering questions like the "What is the death rate of RNe in our Galaxy?" and "Are the white dwarfs gaining or losing mass over each eruption cycle?." An important use of this work is for the question of whether RNe can be the progenitors of Type Ia supernovae. © 2010. The American Astronomical Society. All rights reserved.
Kim J.,Louisiana State University
ILAR journal / National Research Council, Institute of Laboratory Animal Resources | Year: 2012
Two histone marks, H3K27me3 and H3K9me3, are well known for their repressive roles in the genic and nongenic regions of metazoan genomes. Several protein complexes are known to be responsible for generating these marks, including polycomb repression complex 2 and several H3K9 methylases. Recent studies have shown that the targeting of these histone-modifying complexes within mammalian genomes may be mediated through several DNA-binding proteins, including AEBP2, JARID2, and YY1. In this review, we discuss the potential targeting mechanisms in light of the recent results that have been derived from genome-wide chromatin immunoprecipitation sequencing data and the in vivo functions of these two histone marks in light of the results derived from mouse and human genetic studies.
Malisoff M.,Louisiana State University |
Zhang F.,Georgia Institute of Technology
Automatica | Year: 2013
Curve tracking is a challenging and central problem in robotics. In this note, we study adaptive control and parameter estimation for two dimensional robotic curve tracking with unknown control gains. We build adaptive controllers that stabilize equilibria corresponding to a fixed constant distance to the curve and zero bearing. The significance of our work is in (a) our ability to identify the unknown control gain, (b) our proof of input-to-state stability with respect to actuator errors, and (c) the optimality of our disturbance bounds for maintaining robust forward invariance of a nested class of hexagons that fill the state space, under actuator disturbances and the unknown control gain. We demonstrate our work in simulations. © 2013 Elsevier Ltd. All rights reserved.
Smolinsky L.,Louisiana State University
Journal of Informetrics | Year: 2016
The mean normalized citation score or crown indicator is a much studied bibliometric indicator that normalizes citation counts across fields. We examine the theoretical basis of the normalization method and, in particular, the determination of the expected number of citations. We observe a theoretical bias that raises the expected number of citations for low citation fields and lowers the expected number of citations for high citation fields when interdisciplinary publications are included. © 2015 Elsevier Ltd.
Schaefer B.E.,Louisiana State University
Astrophysical Journal Letters | Year: 2016
KIC 8462852 is a completely ordinary F3 main-sequence star, except that the light curve from Kepler shows episodes of unique and inexplicable day-long dips with up to 20% dimming. Here, I provide a light curve of 1338 Johnson B-band magnitudes from 1890 to 1989 taken from archival photographic plates at Harvard. KIC 8462852 displays a secular dimming at an average rate of 0.164 ± 0.013 mag per century. From the early-1890s to the late-1980s, KIC 8462852 faded by 0.193 ± 0.030 mag. The decline is not an artifact because nearby check stars have closely flat light curves. This century-long dimming is unprecedented for any F-type main-sequence star. Thus, the Harvard light curve provides the first confirmation (past the several dips seen in the Kepler light curve alone) that KIC 8462852 has anything unusual. The century-long dimming and the day-long dips are both just extreme ends of a spectrum of timescales for unique dimming events. By Ockham's Razor, two such unique and similar effects are very likely produced by one physical mechanism. This one mechanism does not appear as any isolated catastrophic event in the last century, but rather must be some ongoing process with continuous effects. Within the context of dust-occultation models, the century-long dimming trend requires 104-107 times as much dust as for the deepest Kepler dip. Within the context of the comet-family idea, the century-long dimming trend requires an estimated 648,000 giant comets (each with 200 km diameter) all orchestrated to pass in front of the star within the last century. © 2016. The American Astronomical Society. All rights reserved.
Li S.,Louisiana State University
DNA Repair | Year: 2015
Transcription coupled nucleotide excision repair (TC-NER) is believed to be triggered by an RNA polymerase stalled at a lesion in the transcribed strand of actively transcribed genes. Rad26, a DNA-dependent ATPase in the family of SWI2/SNF2 chromatin remodeling proteins, plays an important role in TC-NER in Saccharomyces cerevisiae. However, Rad26 is not solely responsible for TC-NER and Rpb9, a nonessential subunit of RNA polymerase II (RNAP II), is largely responsible for Rad26-independent TC-NER. The Rad26-dependent and Rpb9-dependent TC-NER have different efficiencies in genes with different transcription levels and in different regions of a gene. Rad26 becomes entirely or partially dispensable for TC-NER in the absence of Rpb4, another nonessential subunit of RNAP II, or a number of transcription elongation factors (Spt4, Spt5 and the RNAP II associated factor complex). Rad26 may not be a true transcription-repair coupling factor that recruits the repair machinery to the damaged sites where RNAP II stalls. Rather, Rad26 may facilitate TC-NER indirectly, by antagonizing the action of TC-NER repressors that normally promote transcription elongation. The underlying mechanism of how Rad26 functions in TC-NER remains to be elucidated. © 2015 Elsevier B.V.
Qiu L.,Hong Kong University of Science and Technology |
Gu G.,Louisiana State University |
Chen W.,Hong Kong University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2013
In this paper, we study the problem of state feedback stabilization of a linear time-invariant (LTI) discrete-time multi-input system with imperfect input channels. Each input channel is modeled in three different ways. First it is modeled as an ideal transmission system together with an additive norm bounded uncertainty, introducing a multiplicative uncertainty to the plant. Then it is modeled as an ideal transmission system together with a feedback norm bounded uncertainty, introducing a relative uncertainty to the plant. Finally it is modeled as an additive white Gaussian noise channel. For each of these models, we properly define the capacity of each channel whose sum yields the total capacity of all input channels. We aim at finding the least total channel capacity for stabilization. Different from the single-input case that is available in the literature and boils down to a typical H∞ or H 2 optimal control problem, the multi-input case involves allocation of the total capacity among the input channels in addition to the design of the feedback controller. The overall process of channel resource allocation and the controller design can be considered as a case of channel-controller co-design which gives rise to modified nonconvex optimization problems. Surprisingly, the modified nonconvex optimization problems, though appear more complicated, can be solved analytically. The main results of this paper can be summarized into a universal theorem: The state feedback stabilization can be accomplished by the channel-controller co-design, if and only if the total input channel capacity is greater than the topological entropy of the open-loop system. © 1963-2012 IEEE.
Ye J.,Louisiana State University
Frontiers of Medicine in China | Year: 2013
Obesity increases the risk for type 2 diabetes through induction of insulin resistance. Treatment of type 2 diabetes has been limited by little translational knowledge of insulin resistance although there have been several well-documented hypotheses for insulin resistance. In those hypotheses, inflammation, mitochondrial dysfunction, hyperinsulinemia and lipotoxicity have been the major concepts and have received a lot of attention. Oxidative stress, endoplasmic reticulum (ER) stress, genetic background, aging, fatty liver, hypoxia and lipodystrophy are active subjects in the study of these concepts. However, none of those concepts or views has led to an effective therapy for type 2 diabetes. The reason is that there has been no consensus for a unifying mechanism of insulin resistance. In this review article, literature is critically analyzed and reinterpreted for a new energy-based concept of insulin resistance, in which insulin resistance is a result of energy surplus in cells. The energy surplus signal is mediated by ATP and sensed by adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. Decreasing ATP level by suppression of production or stimulation of utilization is a promising approach in the treatment of insulin resistance. In support, many of existing insulin sensitizing medicines inhibit ATP production in mitochondria. The effective therapies such as weight loss, exercise, and caloric restriction all reduce ATP in insulin sensitive cells. This new concept provides a unifying cellular and molecular mechanism of insulin resistance in obesity, which may apply to insulin resistance in aging and lipodystrophy. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg.
Vorontsov A.B.,Montana State University |
Vekhter I.,Louisiana State University
Physical Review Letters | Year: 2010
We develop the formalism for computing the oscillations of the specific heat and thermal transport under rotated magnetic field in multiband superconductors with anisotropic gap and apply it to iron-based materials. We show that these oscillations change sign at low temperatures and fields, which strongly influences the experimental conclusions about the gap structure. We find that recent measurements of the specific heat oscillations indicate that the iron-based superconductors possess an anisotropic gap with deep minima or nodes close to the line connecting electron and hole pockets. We predict the behavior of the thermal conductivity that will help distinguish between these cases. © 2010 The American Physical Society.
Jia P.,Louisiana State University |
Joyner A.,East Tennessee State University
BMC Infectious Diseases | Year: 2015
Background: Brucellosis is a common zoonotic disease and remains a major burden in both human and domesticated animal populations worldwide. Few geographic studies of human Brucellosis have been conducted, especially in China. Inner Mongolia of China is considered an appropriate area for the study of human Brucellosis due to its provision of a suitable environment for animals most responsible for human Brucellosis outbreaks. Methods: The aggregated numbers of human Brucellosis cases from 1951 to 2005 at the municipality level, and the yearly numbers and incidence rates of human Brucellosis cases from 2006 to 2010 at the county level were collected. Geographic Information Systems (GIS), remote sensing (RS) and ecological niche modeling (ENM) were integrated to study the distribution of human Brucellosis cases over 1951-2010. Results: Results indicate that areas of central and eastern Inner Mongolia provide a long-term suitable environment where human Brucellosis outbreaks have occurred and can be expected to persist. Other areas of northeast China and central Mongolia also contain similar environments. Conclusions: This study is the first to combine advanced spatial statistical analysis with environmental modeling techniques when examining human Brucellosis outbreaks and will help to inform decision-making in the field of public health. © 2015 Jia and Joyner; licensee BioMed Central.
Baumeister A.A.,Louisiana State University
Journal of the History of the Neurosciences | Year: 2013
Two revolutionary drugs were introduced into psychiatry in the early 1950s for the treatment of agitated mental patients - reserpine and chlorpromazine. These drugs initiated the modern era of drug treatment for schizophrenia and other psychoses. Early research revealed that, although the pharmacological profiles of the two drugs overlapped considerably, they had different mechanisms of action. The mechanism of action of reserpine was determined first: it depletes monoamines from the brain and other tissues. By contrast, chlorpromazine has little or no effect on brain monoamine concentrations. The mystery created by two drugs that have similar pharmacological profiles but different mechanisms of action is the chlorpromazine enigma. For about eight years after the mechanism of action of reserpine was determined, researchers followed several false leads about the mechanism of action of chlorpromazine. Then, in 1963, Arvid Carlsson and Margit Lindqvist proposed that chlorpromazine (and haloperidol) work by blocking "monoaminergic" receptors. It was quickly determined that dopamine receptor blockade was the most important action. Although the idea of chemical communication between central neurons had yet to gain wide acceptance, this idea was central to resolving the chlorpromazine enigma. © 2013 Copyright Taylor & Francis Group, LLC.
Kam S.I.,Louisiana State University
Journal of Petroleum Science and Engineering | Year: 2010
A leak from subsea pipelines has been a serious problem in deepwater operations because of its potential threat to surrounding marine environments, significant monetary loss from the delay of hydrocarbon production, and difficulty in detection and remedial processes. For the first time, this study shows how a leak in long horizontal subsea pipelines can be modeled mechanistically using pressure traverse calculations, and presents the results in a form of contour plots, with "a change in inlet pressure (ΔP in)" or "a change in outlet flowrate (Δq tout)" induced by a leak in z axis as a function of leak opening size and longitudinal pipe location in the x and y axes. Beggs and Brill's correlations provided a means of deciphering complicated gas-oil two-phase flow mechanisms in pipelines. The calculated steady-state response of the system before and after the leak was investigated in terms of pressure gradient, flow rate, holdup, and flowing fraction, which were validated and well agreed with results from a quasi-dynamic numerical simulation. The results showed that the outlet flowrate monitored at the receiving facilities (q tout) could be a good indicator to detect a leak, while the pressure monitored at the inlet (P in) was less reliable. The use of inlet pressure became more trustworthy with decreasing backpressure downstream (or increasing gas compressibility equivalently). The results also demonstrated that a leak is more easily detected if located further upstream with a larger opening size, and the presence of a compressible phase in pipelines makes leak detection more favorable leading to larger Δq tout. The effects of gas-oil ratio of leaking fluids, gas compressibility, leak size, and leak coefficient were investigated, and the nature of transient behavior between the two steady states, before and after the leak, was also examined. © 2009 Elsevier B.V. All rights reserved.
Wan X.,Louisiana State University
Journal of Computational Physics | Year: 2011
In this work, we present an adaptive high-order minimum action method for dynamical systems perturbed by small noise. We use the hp finite element method to approximate the minimal action path and nonlinear conjugate gradient method to solve the optimization problem given by the Freidlin-Wentzell least action principle. The gradient of the discrete action functional is obtained through the functional derivative and the moving mesh technique is employed to enhance the approximation accuracy. Numerical examples are given to demonstrate the efficiency and accuracy of the proposed numerical method. © 2011 Elsevier Inc.
Aly A.M.,Louisiana State University
Building and Environment | Year: 2014
This paper summarizes the state-of-the-art techniques used to simulate hurricane winds in atmospheric boundary-layer (ABL) for wind engineering testing. The wind tunnel simulation concept is presented along with its potential applications, advantages and challenges. ABL simulation at open-jet simulators is presented along with an application example followed by a discussion on the advantages and challenges of testing at these facilities. Some of the challenges and advantages of using computational fluid dynamics (CFD) are presented with an application example. The paper show that the way the wind can be simulated is complex and matching one parameter at full-scale may lead to a mismatch of other parameters. For instance, while large-scale testing is expected to improve Reynolds number and hence approach the full-scale scenario, it is challenging to generate large-scale turbulence in an artificially created wind. New testing protocols for low-rise structures and small-size architectural features are presented as an answer to challenging questions associated with both wind tunnel and open-jet testing. Results show that it is the testing protocol that can be adapted to enhance the prediction of full-scale physics in nature. Thinking out of the box and accepting non-traditional ABL is necessary to compensate for Reynolds effects and to allow for convenient experimentation. New research directions with focus on wind, rain and waves as well as other types of non-synoptic winds are needed, in addition to a more focus on the flow physics in the lower part of the ABL, where the major part of the infrastructure exists. © 2014 Elsevier Ltd.
Yu W.,Xiamen University |
Li X.,Louisiana State University
Computer Graphics Forum | Year: 2014
This paper proposes an effective framework to compute the visibility guarding and star decomposition of 3D solid shapes. We propose a progressive integer linear programming algorithm to solve the guarding points that can visibility cover the entire shape; we also develop a constrained region growing scheme seeded on these guarding points to get the star decomposition. We demonstrate this guarding/decomposition framework can benefit graphics tasks such as shape interpolation and shape matching/retrieval. © 2011 The Author(s).
Cohen A.S.,Louisiana State University |
Lee Hong S.,Indiana University
Journal of Personality Disorders | Year: 2011
Constricted affect (CA) is a cardinal negative symptom of schizophrenia- spectrum disorders. It is unclear whether behaviorally-defined CA occurs in individuals with schizotypy-those with the personality organization reflective of schizophrenia liability. Moreover, it is unclear whether CA contributes to real world dysfunction in this population. The present study employed computerized prosodic analysis of natural speech procured during a laboratory procedure. Subjects were 89 individuals with psychometrically-defined schizotypy and 26 controls. Groups did not differ in any of the prosody measures examined here. Within the schizotypy group, increased prosodic expression was associated with positive schizotypy traits while decreased prosodic expression was associated with negative schizotypy traits. Prosodic deficits were significantly associated with reduced prosocial behaviors (e.g., talking with friends) but were not associated with subjective social satisfaction. Prosodic deficits characterize a subset of individuals with schizotypy who show a schizoid-like reduction in social behaviors without a concomitant reduction in social satisfaction. © 2011 The Guilford Press.
Shu Y.,South China Normal University |
Lam Nina S.N. N.S.N.,Louisiana State University
Atmospheric Environment | Year: 2011
Detailed estimates of carbon dioxide emissions at fine spatial scales are critical to both modelers and decision makers dealing with global warming and climate change. Globally, traffic-related emissions of carbon dioxide are growing rapidly. This paper presents a new method based on a multiple linear regression model to disaggregate traffic-related CO 2 emission estimates from the parish-level scale to a 1×1km grid scale. Considering the allocation factors (population density, urban area, income, road density) together, we used a correlation and regression analysis to determine the relationship between these factors and traffic-related CO 2 emissions, and developed the best-fit model. The method was applied to downscale the traffic-related CO 2 emission values by parish (i.e. county) for the State of Louisiana into 1-km 2 grid cells. In the four highest parishes in traffic-related CO 2 emissions, the biggest area that has above average CO 2 emissions is found in East Baton Rouge, and the smallest area with no CO 2 emissions is also in East Baton Rouge, but Orleans has the most CO 2 emissions per unit area. The result reveals that high CO 2 emissions are concentrated in dense road network of urban areas with high population density and low CO 2 emissions are distributed in rural areas with low population density, sparse road network. The proposed method can be used to identify the emission " hot spots" at fine scale and is considered more accurate and less time-consuming than the previous methods. © 2010 Elsevier Ltd.
Bray G.A.,Louisiana State University
Mount Sinai Journal of Medicine | Year: 2010
Obesity results from a prolonged small positive energy imbalance, and treatment needs to reverse this imbalance. Many different diets have been tried to treat obesity, and weight loss occurs with all of them. There is currently no evidence that supports the superiority of one macronutrient composition for diets over any other. The principal effect seems to be the degree of adherence to the prescribed calorie reduction. Obesity drugs have been developed that tap brain mechanisms for controlling feeding and the gastrointestinal tract and its peptides. Orlistat blocks intestinal lipase and produces modest weight loss. Sibutramine is a serotonin-norepinephrine reuptake inhibitor that has a warning on its label from the US Food and Drug Administration because of cardiovascular risk. Its marketing has been suspended in Europe. Several drug combinations are on the horizon for treatment of obesity. © 2010 Mount Sinai School of Medicine.
Listi G.A.,Louisiana State University
American Journal of Physical Anthropology | Year: 2011
The timing of the dietary shift from foraging to maize agriculture, and the speed at which such practices were adopted, are important considerations in the cultural evolution of the New World. In the southern Lower Mississippi Valley, maize agriculture traditionally was believed to have been practiced during the Coles Creek period (A.D. 700-1200); however, direct evidence for maize is lacking in the archaeological record prior to A.D. 1000. The present study examines Coles Creek diet from a bioarchaeological perspective. Oral-health indicators, including abscesses, antemortem tooth loss, calculus, carious lesions, periodontal disease, and tooth wear, were evaluated in a regional, temporal context. Data were collected from 288 dentitions from eight sites in the southern Lower Mississippi Valley that range in date from 800 B.C. to A.D. 1200. The sample then was separated into Pre-Coles Creek and Coles Creek categories and statistical analyses were used to assess temporal variation in pathology load. Results indicate that pathology load in the Coles Creek sample is slightly heavier than the Pre-Coles Creek sample; however, the differences are not substantial. Furthermore, data suggest that regional differences in resource exploitation existed between the Lower Mississippi Valley and populations elsewhere in the eastern United States. Specifically, the presence of starchy native plants other than maize in the diet likely contributed to a high pathology load for early hunter-gatherers. Ultimately, data from this study complement the archaeological, botanical, and zooarchaeological records and indicate that Coles Creek subsistence was not based on maize agriculture. © 2010 Wiley-Liss, Inc.
Wang T.,Yale University |
Kartika R.,Louisiana State University |
Spiegel D.A.,Yale University
Journal of the American Chemical Society | Year: 2012
The methylglyoxal-derived hydroimidazolones (MG-Hs) comprise the most prevalent class of non-enzymatic, post-translational modifications of protein arginine residues found in nature. These adducts form spontaneously in the human body, and are also present at high levels in the human diet. Despite numerous lines of evidence suggesting that MG-H-arginine adducts play critical roles in both healthy and disease physiology in humans, detailed studies of these molecules have been hindered by a lack of general synthetic strategies for their preparation in chemically homogeneous form, and on scales sufficient to enable detailed biochemical and cellular investigations. To address this limitation, we have developed efficient, multigram-scale syntheses of all MG-H-amino acid building blocks, suitably protected for solid-phase peptide synthesis, in 2-3 steps starting from inexpensive, readily available starting materials. Thus, MG-H derivatives were readily incorporated into oligopeptides site-specifically using standard solid-phase peptide synthesis. Access to synthetic MG-H-peptide adducts has enabled detailed investigations, which have revealed a series of novel and unexpected findings. First, one of the three MG-H isomers, MG-H3, was found to possess potent, pH-dependent antioxidant properties in biochemical and cellular assays intended to replicate redox processes that occur in vivo. Computational and mechanistic studies suggest that MG-H3-containing constructs are capable of participating in mechanistically distinct H-atom-transfer and single-electron-transfer oxidation processes. Notably, the product of MG-H3 oxidation was unexpectedly observed to disassemble into the fully unmodified arginine residue and pyruvate in aqueous solution. We believe these observations provide insight into the role(s) of MG-H-protein adducts in human physiology, and expect the synthetic reagents reported herein to enable investigations into non-enzymatic protein regulation at an unprecedented level of detail. © 2012 American Chemical Society.
Ram Y.M.,Louisiana State University |
Mottershead J.E.,University of Liverpool
Mechanical Systems and Signal Processing | Year: 2013
The paper addresses the problem of suppressing vibrations by active control. Conventional methods use a mathematical model, e.g. finite elements, as the foundations for the computations of the control gains. Such a model is known to contain inaccuracies and assumptions that may hinder the calculations. An alternative approach, advocated previously by the authors, is to design a controller using vibration measurements, in the form of receptances, typically available from a modal test. The methodology as originally formulated was limited to single-input control. In this paper new theory is described that is applicable to both single-input and multiple-input-multiple-output vibration control of practical engineering structures. The theory is supplemented by a series of illustrative numerical examples. © 2013 Elsevier Ltd.
Blackwell M.,Louisiana State University
BioControl | Year: 2010
Fungi and insects are closely associated in many terrestrial and some aquatic habitats. In addition to the pathogenic associations, many more interactions involve fungal spore dispersal. Recent advances in the study of insect-associated fungi have come from phylogenic analyses with increased taxon sampling and additional DNA loci. In addition to providing stable phylogenies, some molecular studies have begun to unravel problems of dating of evolutionary events, convergent evolution and host switching. These studies also enlighten our understanding of fungal ecology and the development of organismal interactions. Mycologists continue to rely heavily, however, on identified specimens based on morphology to incorporate more of the estimated 1.5 million species of fungi in phylogenetic studies. © International Organization for Biological Control (IOBC) 2009.
Reid N.,Louisiana State University |
Reid N.,University of Idaho |
Demboski J.R.,Denver Museum of Nature and Science |
Sullivan J.,University of Idaho
Systematic Biology | Year: 2012
The causes and consequences of rapid radiations are major unresolved issues in evolutionary biology. This is in part because phylogeny estimation is confounded by processes such as stochastic lineage sorting and hybridization. Because these processes are expected to be heterogeneous across the genome, comparison among marker classes may provide a means of disentangling these elements. Here we use introns from nuclear-encoded reproductive protein genes expected to be resistant to introgression to estimate the phylogeny of the western chipmunks (Tamias: subgenus: Neotamias), a rapid radiation that has experienced introgressive hybridization of mitochondrial DNA (mtDNA). We analyze the nuclear loci using coalescent-based species-tree estimation methods and concatenation to estimate a species tree and we use parametric bootstraps and coalescent simulations to differentiate between phylogenetic error, coalescent stochasticity and introgressive hybridization. Results indicate that the mtDNA gene tree reflects several introgression events that have occurred between taxa of varying levels of divergence and at different time points in the tree. T. panamintinus and T. speciosus appear to be fixed for ancient mitochondrial introgressions from T. minimus. A southern Rocky Mountains clade appears well sorted (i.e., species are largely monophyletic) at multiple nuclear loci, while five of six taxa are nonmonophyletic based on cytochrome b. Our simulations reject phylogenetic error and coalescent stochasticity as causes. The results represent an advance in our understanding of the processes at work during the radiation of Tamias and suggest that sampling reproductive-protein genes may be a viable strategy for phylogeny estimation of rapid radiations in which reproductive isolation is incomplete. However, a genome-scale survey that can statistically compare heterogeneity of genealogical process at many more loci will be necessary to test this conclusion. © 2011 The Author(s).
Williamson G.B.,Louisiana State University |
Wiemann M.C.,U.S. Department of Agriculture
Biotropica | Year: 2010
Wood specific gravity is the single best descriptor of wood functional properties and tree life-history traits, and it is the most important variable in estimating carbon stocks in forests. Tropical pioneer trees produce wood of increasing specific gravity across the trunk radius as they grow in stature. Here, we tested whether radial increases in wood specific gravity were dependent on a tree's diameter or its age by comparing trees of different diameters within cohorts. We cored trunks of four pioneer species in naturally regenerating, even-aged stands in the lowland, wet forests of Costa Rica. For each core, specific gravity was determined for 1-cm radial wood segments, pith to bark. Increases across the radius were evident in all four species studied, and in four different stands for one species. For any given species in a given stand, the rate of radial increase in specific gravity as a function of radial distance from the pith was greater in smaller diameter trees. As the trees in a stand represent a colonizing cohort, these results strongly suggest that the radial increases in specific gravity in lowland pioneers are associated with tree age, not with tree diameter. Furthermore, the specific gravity of the outermost wood was not associated with tree radius, further negating size dependence. One consequence of these results is that species-specific biomass estimates for trees in secondary forests are likely to be confounded by age, as diameter alone may be a poor indicator of specific gravity in individual trees for pioneers of tropical wet forests.Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp. © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.
Rejeski W.J.,Wake forest University |
Ip E.H.,Wake forest University |
Bertoni A.G.,Wake forest University |
Bray G.A.,Louisiana State University |
And 3 more authors.
New England Journal of Medicine | Year: 2012
BACKGROUND:Adults with type 2 diabetes mellitus often have limitations in mobility that increase with age. An intensive lifestyle intervention that produces weight loss and improves fitness could slow the loss of mobility in such patients. METHODS:We randomly assigned 5145 overweight or obese adults between the ages of 45 and 74 years with type 2 diabetes to either an intensive lifestyle intervention or a diabetes support-and-education program; 5016 participants contributed data. We used hidden Markov models to characterize disability states and mixed-effects ordinal logistic regression to estimate the probability of functional decline. The primary outcome was self-reported limitation in mobility, with annual assessments for 4 years. RESULTS:At year 4, among 2514 adults in the lifestyle-intervention group, 517 (20.6%) had severe disability and 969 (38.5%) had good mobility; the numbers among 2502 participants in the support group were 656 (26.2%) and 798 (31.9%), respectively. The lifestyle-intervention group had a relative reduction of 48% in the risk of loss of mobility, as compared with the support group (odds ratio, 0.52; 95% confidence interval, 0.44 to 0.63; P<0.001). Both weight loss and improved fitness (as assessed on treadmill testing) were significant mediators of this effect (P<0.001 for both variables). Adverse events that were related to the lifestyle intervention included a slightly higher frequency of musculoskeletal symptoms at year 1. CONCLUSIONS:Weight loss and improved fitness slowed the decline in mobility in overweight adults with type 2 diabetes. (Funded by the Department of Health and Human Services and others; ClinicalTrials.gov number, NCT00017953.) Copyright © 2012 Massachusetts Medical Society.
Buford T.W.,University of Florida |
Roberts M.D.,University of Missouri |
Church T.S.,Louisiana State University
Sports Medicine | Year: 2013
The early 21st century has witnessed a steady push by scientists, industry leaders, and government officials to make medicine more personalized. To date, the concept of personalized medicine has referred largely to the field of pharmacogenomics. In contrast, relatively few data exist regarding the application of preventive strategies such as physical exercise in the context of personalized medicine. Within this review, we highlight the extant literature and propose five strategies for scientists that may propel the exercise and sports science fields toward this global goal. Notably, these approaches are in addition to methods to maintain adherence to training - a well-known factor in determining exercise responsiveness. Briefly, these strategies include (1) evaluating participant responses to training at the individual as well as group level; (2) identifying sources of variability in responsiveness to training; (3) optimizing exercise dosing strategies to maximize benefits while minimizing barriers to participation; (4) evaluating the efficacy of multimodal interventions for relevant population subgroups; and (5) increasing the clinical relevance of study populations and outcomes in exercise trials. We look forward to seeing these strategies considered in trials of preventive health interventions such as exercise. Extensive future research in this area is needed for the vision of exercise as a personalized form of medicine to become a reality. © 2013 Springer International Publishing Switzerland.
Brown J.M.,Louisiana State University
Systematic Biology | Year: 2014
Systematic phylogenetic error caused by the simplifying assumptions made in models of molecular evolution may be impossible to avoid entirely when attempting to model evolution across massive, diverse data sets. However, not all deficiencies of inference models result in unreliable phylogenetic estimates. The field of phylogenetics lacks a direct method to identify cases where model specification adversely affects inferences. Posterior predictive simulation is a flexible and intuitive approach for assessing goodness-of-fit of the assumed model and priors in a Bayesian phylogenetic analysis. Here, I propose new test statistics for use in posterior predictive assessment of model fit. These test statistics compare phylogenetic inferences from posterior predictive data sets to inferences from the original data. A simulation study demonstrates the utility of these new statistics. The new tests reject the plausibility of inferred tree lengths or topologies more often when data/model combinations produce biased inferences. I also apply this approach to exemplar empirical data sets, highlighting the value of the novel assessments. [Bayesian; Markov chain Monte Carlo; model fit; phylogenetic; posterior predictive distribution; sequence evolution; simulation. © The Author(s) 2014.
Starns J.J.,University of Massachusetts Amherst |
Hicks J.L.,Louisiana State University
Memory and Cognition | Year: 2013
Reinstating source details at test often has no impact on source memory. We tested the proposition that participants internally reinstate source cues when such cues are not provided by the experimenter, thus making the external cues redundant. Participants studied words paired with either a male or a female face and were later asked to specify the gender of the face studied with each word. To disrupt the ability to internally reinstate sources, some participants saw eight male faces and eight female faces throughout the study list (multiple-face condition), making it difficult to determine which face should be internally reinstated for uncued test trials. Other participants saw only a single face for each gender (single-face condition), which should facilitate internal reinstatement. Across three experiments, participants in the multiple-face condition showed improved source discrimination when the studied faces were reinstated at test, as compared to uncued trials. In contrast, participants in the single-face condition showed no effect of the face cues. Moreover, the cuing effect for the multiple-face condition disappeared when the test structure facilitated internal reinstatement. Overall, the experiments support the contention that internal reinstatement is a natural part of source retrieval that can mask the effects of external cues. © 2013 Psychonomic Society, Inc.
Miot da Silva G.,Nicholls State University |
Hesp P.,Louisiana State University
Geomorphology | Year: 2010
This paper examines the role of coastline orientation on foredune and dunefield development at Moçambique Beach, Southern Brazil. The beach displays significant alongshore variations in exposure to the prevailing winds and waves, grain size, beach/surfzone morphodynamic type, foredune volume, and type and dimensions of the Holocene dune systems. Two wind analyses and calculation of aeolian drift potentials were carried out, one based on 1. year of wind record and another based on a record of 34. years. Monthly topographic surveys of beach and foredunes on 5 profiles along Moçambique beach were conducted over one year to obtain data on beach mobility and width, aeolian sediment transport and foredune development. Southerly winds dominate, and aeolian sediment supply is minimal in the south, moderate in the central portion and high in the northern portion of the embayment. The relationship between actual sediment supply, foredune building and potential sediment supply is relatively poor over one year due to factors such as beach type and mobility, beach moisture levels, rainfall, storm surge and wave scarping. The intermediate term (34. year) record indicates a strong relationship between foredune size and volume, winds and shoreline orientation: foredune volume is minimum in the southern part of the beach and greatest in the northern part of the beach. The Holocene barrier and dunefield development also reflects the long term control of shoreline orientation and increasing longshore gradient in exposure to southerly winds: for the last 6000-7000. years a small foredune developed in the southern portion, parabolics and small transgressive dunes in the central portion, and a large-scale transgressive dunefield in the northern portion. © 2010 Elsevier B.V.
Karki B.B.,Louisiana State University
Reviews in Mineralogy and Geochemistry | Year: 2010
The study of silicate melts from first principles is computationally intensive due to the need of relatively large atomic systems and long simulation runs. Recent advances in hardware and software have made it possible to accurately simulate the liquid phase at pressures and temperatures that are geophysically relevant. This paper reports the details of the methodology used in the context of simulations and subsequent analysis of the output data. The simulations are performed using the parallel first-principles molecular dynamics (FPMD) technique within the framework of density functional theory. Various physical properties including the equation of state, thermodynamics, atomic and electronic structures, self-diffusion and viscosity are obtained from simulations. The position time series are visualized to gain insight into underlying physical mechanisms. We review the recent first-principles studies of three liquids along the MgO-SiO2 join including MgSiO3 melt to show that the structural and dynamical properties of these liquids are highly sensitive to pressure and temperature. Copyright © Mineralogical Society of America.
Ingram D.K.,Louisiana State University |
Roth G.S.,GeroScience Inc.
Ageing Research Reviews | Year: 2015
Strong consensus exists regarding the most robust environmental intervention for attenuating aging processes and increasing healthspan and lifespan: calorie restriction (CR). Over several decades, this paradigm has been replicated in numerous nonhuman models, and has been expanded over the last decade to formal, controlled human studies of CR. Given that long-term CR can create heavy challenges to compliance in human diets, the concept of a calorie restriction mimetic (CRM) has emerged as an active research area within gerontology. In past presentations on this subject, we have proposed that a CRM is a compound that mimics metabolic, hormonal, and physiological effects of CR, activates stress response pathways observed in CR and enhances stress protection, produces CR-like effects on longevity, reduces age-related disease, and maintains more youthful function, all without significantly reducing food intake, at least initially. Over 16 years ago, we proposed that glycolytic inhibition could be an effective strategy for developing CRM. The main argument here is that inhibiting energy utilization as far upstream as possible provides the highest chance of generating a broad spectrum of CR-like effects when compared to targeting a singular molecular target downstream. As an initial candidate CRM, 2-deoxyglucose, a known anti-glycolytic, was shown to produce a remarkable phenotype of CR, but further investigation found that this compound produced cardiotoxicity in rats at the doses we had been using. There remains interest in 2DG as a CRM but at lower doses. Beyond the proposal of 2DG as a candidate CRM, the field has grown steadily with many investigators proposing other strategies, including novel anti-glycolytics. Within the realm of upstream targeting at the level of the digestive system, research has included bariatric surgery, inhibitors of fat digestion/absorption, and inhibitors of carbohydrate digestion. Research focused on downstream sites has included insulin receptors, IGF-1 receptors, sirtuin activators, inhibitors of mTOR, and polyamines. In the current review we discuss progress made involving these various strategies and comment on the status and future for each within this exciting research field. © 2014 Elsevier B.V.
King G.M.,Louisiana State University |
Kostka J.E.,Georgia Institute of Technology |
Hazen T.C.,University of Tennessee at Knoxville |
Sobecky P.A.,University of Alabama
Annual Review of Marine Science | Year: 2015
The Deepwater Horizon oil spill in the northern Gulf of Mexico represents the largest marine accidental oil spill in history. It is distinguished from past spills in that it occurred at the greatest depth (1,500 m), the amount of hydrocarbon gas (mostly methane) lost was equivalent to the mass of crude oil released, and dispersants were used for the first time in the deep sea in an attempt to remediate the spill. The spill is also unique in that it has been characterized with an unprecedented level of resolution using next-generation sequencing technologies, especially for the ubiquitous hydrocarbon-degrading microbial communities that appeared largely to consume the gases and to degrade a significant fraction of the petroleum. Results have shown an unexpectedly rapid response of deep-sea Gammaproteobacteria to oil and gas and documented a distinct succession correlated with the control of the oil flow and well shut-in. Similar successional events, also involving Gammaproteobacteria, have been observed in nearshore systems as well. Copyright © 2015 by Annual Reviews. All rights reserved.
Clift P.D.,Louisiana State University |
Clift P.D.,CAS South China Sea Institute of Oceanology |
Wan S.,CAS Qingdao Institute of Oceanology |
Blusztajn J.,Woods Hole Oceanographic Institution
Earth-Science Reviews | Year: 2014
Reconstructing the changing strength of the East Asian summer monsoon has been controversial because different proxies, many being indirect measures of rainfall, tell contrasting stories about how this has varied over long periods of geologic time. Here we present new Sr isotope, grain-size and clastic flux data and synthesize existing proxies to reconstruct changing chemical erosion in the northern South China Sea since the Oligocene, using the links between weathering rates and monsoon strength established in younger sediments as a way to infer intensity. Chemical proxies such as K/Rb, K/Al and the Chemical Index of Alteration (CIA), together with clay proxies like kaolinite/(illite+chlorite) show a steady decline in alteration after a sharp fall following a maximum at the Mid Miocene Climatic Optimum (MMCO; 15.5-17.2Ma), probably as a result of cooling global temperatures. In contrast, physical erosion proxies, including bulk Ti/Ca and clastic mass accumulation rates (MAR), show peaks at 21-23Ma, ~19Ma and 15.5-17.2Ma, implying faster run-off in the absence of drainage capture. Rates increase again, likely driven by slightly increased run-off after 13Ma, but decrease after 8Ma, which is identified as a period of summer monsoon weakening. Sr isotope composition correlates with hematite/goethite and the spectral proxy CRAT to show stronger weathering linked to more monsoonal seasonality. These proxies argue for a strengthening of the East Asian Monsoon after 22-23Ma, followed by an extended period of monsoon maximum between 18 and 10Ma, then weakening. There is some suggestion that the summer monsoon may have strengthened since 3-4Ma after reaching a minimum in the Pliocene. © 2014 Elsevier B.V.
Maccio E.M.,Louisiana State University
Journal of Homosexuality | Year: 2010
This study examined the likelihood of participating in sexual reorientation therapy (SRT) based on actual or expected family reactions to the disclosure of one's same-sex sexuality, religious fundamentalism, social conformity, and several demographic variables. A sample of 52 SRT participants and 211 SRT nonparticipants who had ever identified as gay, lesbian, or bisexual completed a survey either online or in hardcopy format. Actual or expected negative family reactions, high religious fundamentalism, and identifying as spiritual significantly increased one's odds of participating in SRT. The findings are essential for preparing practitioners in any clinical practice setting to work with clients struggling with their sexuality. © Taylor & Francis Group, LLC.
Ram Y.M.,Louisiana State University
Mechanical Systems and Signal Processing | Year: 2016
A simple and intuitive matrix iteration method for solving nonlinear eigenvalue problems is described and demonstrated in detail by two problems: (i) the boundary value problem associated with large deflection of a flexible rod, and (ii) the initial value problem associated with normal mode motion of a double pendulum. The two problems are solved by two approaches, the finite difference approach and a continuous realization approach which is similar in spirit to the Rayleigh-Ritz method. © 2016.
Warren Liao T.,Louisiana State University
Expert Systems with Applications | Year: 2011
This paper proposes feature selection as an approach to deal with a bladder cancer data set with small sample size. Three feature selection methods and four classifiers were used to determine the best feature subsets that produce perfect classification accuracy. The smallest best feature subsets are used to build neural models with the small data set to achieve 100% training and testing accuracies. Therefore, the mega-trend-diffusion technique proposed by Li et al. to produce artificial samples is actually unnecessary. The similarity classifier proposed by Luukka was also applied to the small data set with the smallest best feature subsets to achieve 100% accuracy using only 4 samples (two with bladder cancer and two normal) for two selected p and m values. Given the same accuracy, using the best feature subsets selected is better than using all 13 features as done by Luukka. Furthermore, several indexes/methods commonly used in filtering feature selection methods were tested for their ability to find the best feature subsets for this particular small bladder cancer data set. © 2010 Elsevier Ltd. All rights reserved.
Warren Liao T.,Louisiana State University
Engineering Applications of Artificial Intelligence | Year: 2010
Feature extraction and feature selection are two important issues in sensor-based condition monitoring of any engineering systems. In this study, acoustic emission signals were first collected during grinding operations, next processed by autoregressive modeling or discrete wavelet decomposition for feature extraction, and then the best feature subsets are found by three different feature selection methods, including two proposed ant colony optimization (ACO)-based method and the famous sequential forward floating selection method. Posing monitoring as a classification problem, the evaluation is carried out by the wrapper approach with four different algorithms serving as the classifier. Empirical test results were shown to illustrate the effectiveness of feature extraction and feature selection methods. © 2009 Elsevier Ltd. All rights reserved.
Bray G.A.,Louisiana State University
Current Opinion in Lipidology | Year: 2010
Purpose of review: The purpose of the review is to suggest that fructose, a component of both sucrose (common sugar) and high fructose corn syrup, should be of concern to both healthcare providers and the public. Recent findings: Consumption of sugar-sweetened beverages has increased steadily over the past century and with this increase has come more and more reports associating their use with the risk of overweight, diabetes and cardiometabolic disease. In a meta-analysis of the relationship between soft drink consumption and cardiometabolic risk, there was a 24% overall increased risk comparing the top and bottom quantiles of consumption. Several factors might account for this increased risk, including increased carbohydrate load and increased amounts of dietary fructose. Fructose acutely increases thermogenesis, triglycerides and lipogenesis as well as blood pressure, but has a smaller effect on leptin and insulin release than comparable amounts of glucose. In controlled feeding studies, changes in body weight, fat storage and triglycerides are observed as well as an increase in inflammatory markers. Summary: The present review concludes on the basis of the data assembled here that in the amounts currently consumed, fructose is hazardous to the cardiometabolic health of many children, adolescents and adults. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.
Blackwell M.,Louisiana State University
American Journal of Botany | Year: 2011
Premise of the study: Fungi are major decomposers in certain ecosystems and essential associates of many organisms. They provide enzymes and drugs and serve as experimental organisms. In 1991, a landmark paper estimated that there are 1.5 million fungi on the Earth. Because only 70 000 fungi had been described at that time, the estimate has been the impetus to search for previously unknown fungi. Fungal habitats include soil, water, and organisms that may harbor large numbers of understudied fungi, estimated to outnumber plants by at least 6 to 1. More recent estimates based on high-throughput sequencing methods suggest that as many as 5.1 million fungal species exist. Methods: Technological advances make it possible to apply molecular methods to develop a stable classification and to discover and identify fungal taxa. Key results: Molecular methods have dramatically increased our knowledge of Fungi in less than 20 years, revealing a monophyletic kingdom and increased diversity among early-diverging lineages. Mycologists are making significant advances in species discovery, but many fungi remain to be discovered. Conclusions: Fungi are essential to the survival of many groups of organisms with which they form associations. They also attract attention as predators of invertebrate animals, pathogens of potatoes and rice and humans and bats, killers of frogs and crayfish, producers of secondary metabolites to lower cholesterol, and subjects of prize-winning research. Molecular tools in use and under development can be used to discover the world ' s unknown fungi in less than 1000 years predicted at current new species acquisition rates. © 2011 Botanical Society of America.
O'Neil C.E.,Louisiana State University
American journal of health promotion : AJHP | Year: 2010
PURPOSE: This study investigated the associations among 100% juice consumption, nutrient intake, and measures of weight in adolescents. DESIGN: A cross-sectional secondary analysis of data from adolescents aged 12 to 18 years (n = 3939) participating in the National Health and Nutrition Examination Survey 1999-2002 was conducted to assess nutrient and weight in categories of 100% juice consumption. METHODS: Least square means and logistic regression analyses were generated, and were adjusted for gender, age, ethnicity, and energy intake. Analyses were Bonferroni corrected with an effective p value of .0125. RESULTS: Twenty-eight percent of adolescents (51% male, 42% Hispanic, 25% non-Hispanic white, 29% non-Hispanic black) consumed 100% juice the day of the recall. The mean amount of 100% juice consumed was 3.7 ounces (2.2% of energy intake). Compared with non-juice consumers, carbohydrate, fiber, vitamins C and B6, folate, potassium, copper, magnesium, and iron intakes of juice consumers were higher, and intakes of fat and saturated fatty acids were lower. Those consuming greater than 6 ounces of juice consumed more servings of fruit and less discretionary fat and added sugar than nonconsumers. No differences were found in weight by juice consumption group. CONCLUSION: In conclusion, when compared with non-juice consumers, adolescents consuming 100% juice did not show mean increased weight measures. Juice provided valuable nutrients, and consumption was associated with lower intakes of total fat, saturated fatty acids, discretionary fat, and added sugars and with higher intakes of whole fruit; however, consumption was not associated with decreased intake of milk, meat, or grains.
Bray G.A.,Louisiana State University
Annual Review of Nutrition | Year: 2015
As Erwin Chargaff observed, "Scientific autobiography belongs to a most awkward literary genre," and mine is no exception. In reviewing my scientific life, I contrast the nutritional influences that would have existed had I been born 100 or 200 years earlier than I actually was. With this background, I trace the influences on my formative years in science beginning in high school and ending as a postdoctoral fellow in Professor E.B. Astwood's laboratory, when my directional sails were set and obesity was the compass heading. With this heading, the need for organized national and international meetings on obesity and the need for a scientific journal dealing with obesity as its subject matter became evident and occupied considerable energy over the next 30 years. The next section of this memoir traces the wanderings of an itinerant academic who moved from Boston to Los Angeles and finally to Baton Rouge. The influence of Sir William Osler's idea that there is a time for education, a time for scholarship, a time for teaching, and time to retire has always been a guide to allocating time ever since I was an intern at Johns Hopkins Hospital. It was in Baton Rouge that the final phase began: I agreed to become the first full-time executive director of the Pennington Biomedical Research Center, a decision that changed my life. The article ends with a quotation from Tennessee Williams that reflects the theater, which has given me so much pleasure over the years: "There is a time for departure even when there's no certain place to go." Copyright ©2015 by Annual Reviews. All rights reserved.
Ozhan K.,Louisiana State University
Environmental monitoring and assessment | Year: 2014
We conducted controlled laboratory exposure experiments to assess the toxic effects of water-accommodated fractions (WAFs) of South Louisiana sweet crude oil on five phytoplankton species isolated from the Gulf of Mexico. Experiments were conducted with individual and combinations of the five phytoplankton species to determine growth inhibitions to eight total petroleum hydrocarbon (TPH) equivalent concentrations ranging from 461 to 7,205 ppb. The composition and concentration of crude oil were altered by physical and chemical processes and used to help evaluate crude oil toxicity. The impact of crude oil exposure on phytoplankton growth varied with the concentration of crude oil, species of microalgae, and their community composition. At a concentration of TPH < 1,200 ppb, dinoflagellate species showed significantly better tolerance, while diatom species showed a higher tolerance to crude oil at higher concentrations of TPH. For both groups, the larger species were more tolerant to crude oil than smaller ones. The toxicity potential of crude oil seems to be strongly influenced by the concentration of polycyclic aromatic hydrocarbons (PAHs). The addition of the dispersant, Corexit® EC9500A, increased the amount of crude oil up to 50-fold in the water column, while the physical enhancement (vigorous mixing of water column) did not significantly increase the amount of TPH concentration in the water column. The species response to crude oil was also examined in the five-species community. Each phytoplankton species showed considerably less tolerance to crude oil in the five-species community compared to their individual responses. This study provides baseline information about individual phytoplankton responses to crude oil and dispersed crude oil for subsequent research efforts seeking to understand the impacts of oil on the phytoplankton in the bigger picture.
McKnight M.,Louisiana State University
Journal of the Medical Library Association | Year: 2014
Objectives: Recently, government agencies in several countries have promoted information prescription programs to increase patients’ understanding of their conditions. The practice has a long history and many publications, but no comprehensive literature reviews such as this.Methods: Using a variety of high-precision and highrecall strategies, the researcher searched two dozen online bibliographic databases, citation databases, and repositories, as well as many print sources, to identify and retrieve documents for review. Of these documents, ninety relevant English-language case reports, research reports, and reviews published from 1930-2013 met the study criteria.Results: Early to mid-twentieth century reports covered long-standing practices and used no rigorous research methods. The literature since the mid-1990s reports on short-term trial projects, especially of government-sponsored programs in the United States and United Kingdom. Although the concept of information prescription has been in the literature and practiced for decades, no long-term research studies were found.Conclusions: Most of the literature is anecdotal concerning small pilot projects. The reports investigate physician, patient, and librarian satisfaction but not changes in patient knowledge or behavior. Many twenty-first century projects emphasize materials and projects from specific government agencies and commercial enterprises.Implications: While the practice is commonly believed to be a good idea and there are many publications on the subject, few studies provide any evidence of the efficacy of information prescriptions for increased patient knowledge. Well-designed and executed large or long-term studies might produce needed evidence for professional practice. © 2014 Medical Library Association. All rights reserved.
Lu L.,LSI Corporation |
Wu H.-C.,Louisiana State University
IEEE Transactions on Wireless Communications | Year: 2012
Source localization for wideband signals using acoustic sensor networks has drawn much research interest recently. The maximum-likelihood is the predominant objective for a wide variety of source localization approaches, and we have previously proposed an expectation-maximization (EM) algorithm to solve the source localization problem. In this paper, we tackle the source localization problem based on the realistic assumption that the sources are corrupted by spatially-non-white noise. We explore the respective limitations of our recently proposed algorithm, namely EM source localization algorithm, and design a new direction-of-arrival (DOA) estimation based (DEB) source localization algorithm. We also derive the Cramer-Rao lower bound (CRLB) analysis and the computational complexity study for the aforementioned source localization schemes. Through Monte Carlo simulations and our derived CRLB analysis, it is demonstrated that our proposed DEB algorithm significantly outperforms the previous EM method in terms of both source localization accuracy and computational complexity. © 2012 IEEE.
Bray G.A.,Louisiana State University |
Popkin B.M.,University of North Carolina at Chapel Hill
Diabetes Care | Year: 2014
Sugar-sweetened drinks have been associated with several health problems. In the point narrative as presented below, we provide our opinion and review of the data to date that we need to reconsider consumption of dietary sugar based on the growing concern of obesity and type 2 diabetes. In the counterpoint narrative following our contribution, Drs. Kahn and Sievenpiper provide a defense and suggest that dietary sugar is not the culprit. Data from the National Health and Nutrition Examination Survey and U.S. Department of Agriculture dietary surveys along with commercial Homescan data on household purchases were used to understand changes in sugar and fructose consumption. Meta-analyses and randomized clinical trials were used to evaluate outcomes of beverage and fructose intake. About 75% of all foods and beverages contain added sugar in a large array of forms. Consumption of soft drinks has increased fivefold since 1950. Meta-analyses suggest that consumption of sugar-sweetened beverages (SSBs) is related to the risk of diabetes, the metabolic syndrome, and cardiovascular disease. Drinking two 16-ounce SSBs per day for 6 months induced features of the metabolic syndrome and fatty liver. Randomized controlled trials in children and adults lasting 6 months to 2 years have shown that lowering the intake of soft drinks reduced weight gain. Recent studies suggest a gene-SSB potential relationship. Consumption of calorie-sweetened beverages has continued to increase and plays a role in the epidemic of obesity, the metabolic syndrome, and fatty liver disease. Reducing intake of soft drinks is associated with less weight gain. © 2014 by the American Diabetes Association.
Antipov Y.A.,Louisiana State University
Quarterly Journal of Mechanics and Applied Mathematics | Year: 2014
Scattering of a plane electromagnetic wave by an anisotropic impedance right-angled concave wedge at skew incidence is analysed. A closed-form solution is derived by reducing the problem to a symmetric order-2 vector Riemann-Hilbert problem (RHP) on the real axis. The problem of matrix factorization leads to a scalar RHP on a genus-3 Riemann surface. Its solution is derived by the Weierstrass integrals. Due to a special symmetry of the problem the associated Jacobi inversion problem is solved in terms of elliptic integrals, not a genus-3 Riemann θ-function. The electric and magnetic field components are expressed through the Sommerfeld integrals, and the incident and reflected waves are recovered. © The Author, 2013.
Adams C.E.,Louisiana State University
Nicotine & tobacco research : official journal of the Society for Research on Nicotine and Tobacco | Year: 2011
Many smokers believe that smoking helps them to control their weight, and concerns about weight gain can interfere with smoking cessation. As researchers typically assess general weight concerns, a measure specific to smoking-related weight concerns is needed. The Smoking-related Weight and Eating Episodes Test (SWEET) was created by generating items from 4 content domains: Hunger, Craving, Overeating, and Body Image. Female undergraduate smokers (N = 280) rated their postcessation weight gain concern and completed the SWEET, Fagerström Test for Nicotine Dependence, Brief Smoking Consequences Questionnaire-Adult, Eating Attitudes Test (EAT)-26, Bulimia Test-Revised (BULIT-R), and Body Shape Questionnaire. Factor analysis of the initial items suggested a 4-factor solution, suggesting 4 subscales: Smoking to suppress appetite, smoking to prevent overeating, smoking to cope with body dissatisfaction, and withdrawal-related appetite increases. Based on these results, the SWEET subscales were revised and shortened. The resulting 10-item SWEET showed excellent internal consistency (total α = .94; mean α = .86) and evidence of validity by predicting smoking frequency, eating pathology, and body image concerns (ps < .05). Smoking frequency, eating pathology, and body image concerns were significantly predicted by the SWEET while controlling for existing measures of postcessation weight gain concern. The SWEET appears to be a reliable and valid measure of tendencies to smoke in response to body image concern and nicotine withdrawal and as a way to control appetite and overeating.
Knorowski C.,Iowa State University |
Burleigh S.,Louisiana State University |
Travesset A.,Iowa State University
Physical Review Letters | Year: 2011
DNA linker mediated self-assembly is emerging as a very general strategy for designing new materials. In this Letter, we characterize both the dynamics and thermodynamics of nanoparticle-DNA self-assembly by molecular dynamics simulations from a new coarse-grained model. We establish the general phase diagram and discuss the stability of a previously overlooked crystalline phase (D-bcc). We also characterize universal properties about the dynamics of crystallization. We point out the connection to f-star polymer systems and discuss the implications for ongoing experiments as well as for the general field of DNA mediated self-assembly. © 2011 American Physical Society.
Hynes R.I.,Louisiana State University |
Robinson E.L.,University of Texas at Austin
Astrophysical Journal | Year: 2012
We present Hubble Space Telescope/Advanced Camera for Surveys ultraviolet photometry of three quiescent black hole X-ray transients, X-ray Nova Muscae 1991 (GU Mus), GRO J0422+32 (V518 Per), and X-ray Nova Vel 1993 (MM Vel), and one neutron star system, Aql X-1. These are the first quiescent UV detections of these objects. All are detected at a much higher level than expected from their companion stars alone and are significant detections of the accretion flow. Three of the four UV excesses can be characterized by a blackbody of temperature 5000-13, 000K, hotter than expected for the quiescent outer disk. A good fit could not be found for MM Vel. The source of the blackbody-like emission is most likely a heated region of the inner disk. Contrary to initial indications from spectroscopy, there does not appear to be a systematic difference in the UV luminosity or spectral shape between black holes and neutron star systems. However, combining our new data with earlier spectroscopy and published X-ray luminosities, there is a significant difference in the X-ray to UV flux ratios, with the neutron stars exhibiting L X/L UV about 10 times higher than the black hole systems. This is consistent with earlier comparisons based on estimating non-stellar optical light, but since both bandpasses we use are expected to be dominated by accretion light, we present a cleaner comparison. This suggests that the difference in X-ray luminosities cannot simply reflect differences in quiescent accretion rates and so the UV/X-ray ratio is a more robust discriminator between the black hole and neutron star populations than the comparison of X-ray luminosities alone. © 2012 The American Astronomical Society. All rights reserved.
Laws E.A.,Louisiana State University
Annual Review of Marine Science | Year: 2013
The use of clean sampling and incubation methods and the development of biomass-independent techniques for estimating the rates of growth and grazing mortality of phytoplankton in the ocean have resulted in estimates of phytoplankton growth rates that are approximately twice those reported prior to roughly 1980. Light-saturated growth rates in tropical and subtropical latitudes correspond to a doubling time of roughly 1 day. The results of mesoscale nutrient-enrichment experiments and comparison of growth rates with estimates of strictly temperature-limited rates indicate that light-saturated growth rates are no more than 50% of nutrient-saturated values, a conclusion consistent with the resiliency of food webs to perturbations. Phytoplankton growth rates in the euphotic zone of the ocean appear to be controlled largely by the grazing activities of micro-and mesozooplankton and the recycling of nutrients associated with the catabolism of consumed prey. © 2013 by Annual Reviews. All rights reserved.
Barbato M.,Louisiana State University |
Tubaldi E.,University of Camerino
Earthquake Engineering and Structural Dynamics | Year: 2013
Existing design procedures for determining the separation distance between adjacent buildings subjected to seismic pounding risk are based on approximations of the buildings' peak relative displacement. These procedures are characterized by unknown safety levels and thus are not suitable for use within a performance-based earthquake engineering framework. This paper introduces an innovative reliability-based methodology for the design of the separation distance between adjacent buildings. The proposed methodology, which is naturally integrated into modern performance-based design procedures, provides the value of the separation distance corresponding to a target probability of pounding during the design life of the buildings. It recasts the inverse reliability problem of the determination of the design separation distance as a zero-finding problem and involves the use of analytical techniques in order to evaluate the statistics of the dynamic response of the buildings. Both uncertainty in the seismic intensity and record-to-record variability are taken into account. The proposed methodology is applied to several different buildings modeled as linear elastic single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems, as well as SDOF nonlinear hysteretic systems. The design separation distances obtained are compared with the corresponding estimates that are based on several response combination rules suggested in the seismic design codes and in the literature. In contrast to current seismic code design procedures, the newly proposed methodology provides consistent safety levels for different building properties and different seismic hazard conditions.© 2012 John Wiley & Sons, Ltd..
Webb A.A.G.,Louisiana State University |
Yin A.,University of California at Los Angeles |
Dubey C.S.,University of Delhi
Bulletin of the Geological Society of America | Year: 2013
Models for the origin and deformation of Himalayan rocks are dependent upon geometric and age relationships between major units. We present field mapping and U-Pb dating of igneous and detrital zircons that establish the lithostratigraphic architecture of the eastern Himalaya, revealing that: (1) the South Tibet detachment along the Bhutan-China border is a top-to-the-north ductile shear zone; (2) Late Triassic and Early Cretaceous sedimentary samples from the northern Indian margin show a similar age range of detrital zircons from ca. 3500 Ma to ca. 200 Ma, but the Late Triassic rocks are distinguished by a significant age cluster between ca. 280 and ca. 220 Ma and a well-defined age peak at ca. 570 Ma, (3) an augen gneiss in the South Tibet detachment shear zone in southeast Tibet has a Cambrian-Ordovician crystallization age, (4) Main Central thrust hanging-wall paragneiss and footwall quartzites from the far western Arunachal Himalaya share similar provenance and Late Proterozoic maximum depositional ages, and (5) Main Central thrust footwall metagraywacke from the central western Arunachal Himalaya has a Paleoproterozoic maximum depositional age, indicated by a single prominent age peak of ca. 1780 Ma. Recent work in the eastern Himalaya demonstrates that in the early-middle Miocene, the Himalayan crystalline core here was emplaced southward between two subhorizontal shear zones that merge to the south. A proposed subsequent (middle Miocene) brittle low-angle normal fault accomplishing exhumation of these rocks along the range crest can be precluded because new and existing mapping demonstrates only a ductile shear zone here. The ca. 280-220 Ma detrital zircons of the Late Triassic strata are derived from an arc developed along the northern margin of the Lhasa terrane. Detritus from this arc was deposited on the northern margin of India during India-Lhasa rifting. Along-strike heterogeneity in Main Central thrust footwall chronostratigraphy is indicated by detrital zircon age spectrum differences from central western to far western Arunachal. Nonetheless, the Late Proterozoic rocks in the Main Central thrust hanging wall and footwall in far western Arunachal can be correlated to each other, and to previously analyzed rocks in the South Tibet detachment hanging wall to the west and in the Indian craton to the south. These findings are synthesized in a reconstruction showing Late Triassic India-Lhasa rifting and Cenozoic eastern Himalayan construction via in situ thrusting of basement and cover sequences along the north Indian margin. © 2013 Geological Society of America.
Kato Y.,Los Alamos National Laboratory |
Batista C.D.,Los Alamos National Laboratory |
Vekhter I.,Louisiana State University
Physical Review Letters | Year: 2011
We develop a theory of the coexistence of superconductivity (SC) and antiferromagnetism (AFM) in CeCoIn5. We show that in Pauli-limited nodal superconductors the nesting of the quasiparticle pockets induced by Zeeman pair breaking leads to incommensurate AFM with the magnetic moment normal to the field. We compute the phase diagram and find a first order transition to the normal state at low temperatures, the absence of normal state AFM, and the coexistence of SC and AFM at high fields, in agreement with experiments. We also predict the existence of a new double-Q magnetic phase. © 2011 American Physical Society.
Li C.,Louisiana State University
Journal of Geophysical Research: Oceans | Year: 2013
This paper examines the net transport through a multiple-inlet bay under a combined force of strong wind and tide, with observations and a model experiment. The observations were made in central Georgia in Sapelo and Altamaha Sounds between 13 and 17 September 2000. Wind was weak in the beginning of the survey. An air pressure trough (as a weak cold front) passed the area on 16 September, when the wind changed to the northeast and increased in magnitude. This front was associated with a midlatitude cyclone in the New England area. This weather event with an episode of strong northeasterly winds prompted a numerical model experiment on an idealized three-inlet bay, with a set of nonlinear 2-D shallow water equations on an f plane, which provides some insight to the wind-driven circulation under the presence of tidal forcing. It is found that tidally induced currents are small compared to wind-induced flows. When the wind direction is not perpendicular to the alignment of the three inlets, the net outward flow tends to occur at the inlet farther away in the downwind direction. This is associated with a net inward transport in the inlet opposite of the downwind direction. As a result, the middle inlet has the minimum of the net flow. When the wind is perpendicular to the barrier islands, and if the three inlets have different maximum depth values, the deeper inlet tends to have a net flow against the wind, while the shallower inlet tends to have a net flow in the direction of the wind. Offshore (onshore) currents may develop outside of the inlet with outward (inward) flow, as an effect of fluxes through the inlets on the coastal ocean. © 2013. American Geophysical Union. All Rights Reserved.
Yu G.,Louisiana State University
Methods in molecular biology (Clifton, N.J.) | Year: 2011
Murine models of obesity or reduced adiposity are a valuable resource for understanding the role of adipocyte dysfunction in metabolic disorders. Primary adipocytes grown in culture and derived from murine adipose tissue are essential for studying the mechanisms underlying adipocyte development and function. Herein, we describe methods for the isolation, expansion, and long-term storage of murine adipose-derived stem cells along with a protocol for inducing adipogenesis in this cell population.
Yu G.,Louisiana State University
Methods in molecular biology (Clifton, N.J.) | Year: 2011
The primary physiological function of adipose-derived stem cells (ASCs) is to differentiate into adipose tissue. It is now possible to isolate, expand, and cryopreserve ASC from adipose depots of many animal species. These ASC can be induced to undergo adipogenic differentiation in vitro by exposure to a cocktail of chemical agents or inductive growth factors. The current chapter describes methods to induce adipogenesis and to quantify this differentiation process in vitro.
Khan T.T.,Louisiana State University
Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.] | Year: 2013
The effect of perceived facial blanching with neurotoxin therapy has been described in the literature and has been used to treat the undesirable facial flushing of Frey's syndrome. Patients rarely report it as a complication after cosmetic injection, but it can be distressing. To elucidate the proposed mechanism(s) of this unusual vasculocutaneous phenomenon, we reviewed normal physiologic responses to heat stress and the role of cholinergic neurotransmission in modulating cutaneous vascular tone in the context of the literature. We report a case of a 32-year-old woman who complained of white patches on her forehead at sites of abobotulinumtoxinA injections administered 2 weeks before presentation. Acetylcholine is a primary mediator of cutaneous vasodilatation; certain co-transmitters modulate its effect. Chemical denervation by botulinum toxin (BoNT) appears to interfere with these normal signaling pathways and can provide symptomatic relief to patients with undesirable facial flushing. Conversely, it may create an unwanted cosmetic effect in patients who desire isolated muscle paresis. Skin sites injected with BoNT type A may not experience the expected decrease in cutaneous vessel tone associated with higher body temperature. The exact mechanism remains unclear. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.
Podrabsky J.E.,Portland State University |
Hand S.C.,Louisiana State University
Journal of Experimental Biology | Year: 2015
Diapause is a programmed state of developmental arrest that typically occurs as part of the natural developmental progression of organisms that inhabit seasonal environments. The brine shrimp Artemia franciscana and annual killifish Austrofundulus limnaeus share strikingly similar life histories that include embryonic diapause as a means to synchronize the growth and reproduction phases of their life history to favorable environmental conditions. In both species, respiration rate is severely depressed during diapause and thus alterations in mitochondrial physiology are a key component of the suite of characters associated with cessation of development. Here, we use these two species to illustrate the basic principles of metabolic depression at the physiological and biochemical levels. It is clear that these two species use divergent molecularmechanisms to achieve the same physiological and ecological outcomes. This pattern of convergent physiological strategies supports the importance of biochemical and physiological adaptations to cope with extreme environmental stress and suggests that inferring mechanism from transcriptomics or proteomics or metabolomics alone, without rigorous follow-up at the biochemical and physiological levels, could lead to erroneous conclusions. © 2015. Published by The Company of Biologists Ltd.
Scherp P.,Louisiana State University
Methods in molecular biology (Clifton, N.J.) | Year: 2011
Proteomics refers to the analysis of expression, localization, functions, posttranslational modifications, and interactions of proteins expressed by a genome at a specific condition and at a specific time. Mass spectrometry (MS)-based proteomic methods have emerged as a key technology for unbiased systematic and high-throughput identification and quantification of complex protein mixtures. These methods have the potential to reveal unknown and novel changes in protein interactions and assemblies that regulate cellular and physiological processes. Both gel-based (one-dimensional [1D] gel electrophoresis, two-dimensional [2D] polyacrylamide gel electrophoresis, 2D difference in-gel electrophoresis [DIGE]) and gel-free (liquid chromatography [LC], capillary electrophoresis) approaches have been developed and utilized in a variety of combinations to separate proteins prior to mass spectrometric analysis. Detailed protocols for global proteomic analysis from adipose-derived stem cells (ASCs) using two central strategies, 2D-DIGE-MS and 2D-LC-MS, are presented here.
Chaney J.,Louisiana State University
Southeastern Geographer | Year: 2010
In the past two decades, Nashville, Tennessee has emerged as a new destination for Hispanic immigrants moving into the American South. Many of these newcomers have chosen to reside in the southeast section of the city in neighborhoods adjacent to two main thoroughfares - Nolensville and Murfreesboro Pikes. Residential clustering has fostered the development of various Hispanic- oriented businesses and services throughout southeast Nashville. In this article, I assert that the concentration of Hispanic residents and businesses in southeast Nashville has formed an ethnic enclave. Based on findings collected through an intensive qualitative approach, I argue that the creation of this enclave, complete with Hispanic businesses, organizations, and churches, interferes with the integration of Hispanics into the local community. The results of this study indicate that many Hispanics immigrants (both authorized and unauthorized) choose to operate almost entirely within this enclave which in turn reduces their involvement with members of the host society and slows down the acquisition of the English language. In many cases, this choice is based on language and perceived differences in culture between Hispanics and Anglos; however, interviews and conversations with younger Hispanic immigrants reveal that discriminatory public policies may lead Hispanic immigrants to adopt a strategy of self-segregation as a means of avoiding police harassment.
Grove A.,Louisiana State University
Molecular BioSystems | Year: 2010
The genus Burkholderia includes a large number of species, some of which are serious human pathogens. A genomic locus is conserved that consists of a gene encoding a member of the multiple antibiotic resistance regulator (MarR) family of transcriptional regulators and a divergently oriented gene encoding a major facilitator transport protein (MFTP), a predicted membrane efflux pump. Homology modeling shows that the MarR homolog conserves the location of four conserved amino acid residues previously shown to bind the ligand urate in the Deinococcus radiodurans-encoded MarR homolog HucR. Analysis of the B. thailandensis-encoded homolog shows that its specific DNA binding to two adjacent sites in the intergenic region between the genes encoding the transcription factor and the MFTP is attenuated by urate and to a lesser extent by xanthine and hypoxanthine, but not by adenine or the product of urate degradation, allantoin. These data suggest the existence of a four amino acid urate-binding signature in a subset of MarR homologs, and that homologs bearing this signature will respond to the ligand urate by attenuated DNA binding. The location of binding sites predicts regulation of the MFTP and prompts a proposal to name the cognate transcription factor MftR (major facilitator transport regulator). © 2010 The Royal Society of Chemistry.
Mehraeen S.,Louisiana State University |
Jagannathan S.,Missouri University of Science and Technology
IEEE Transactions on Neural Networks | Year: 2011
In this paper, the direct neural dynamic programming technique is utilized to solve the Hamilton-Jacobi-Bellman equation forward-in-time for the decentralized near optimal regulation of a class of nonlinear interconnected discrete-time systems with unknown internal subsystem and interconnection dynamics, while the input gain matrix is considered known. Even though the unknown interconnection terms are considered weak and functions of the entire state vector, the decentralized control is attempted under the assumption that only the local state vector is measurable. The decentralized nearly optimal controller design for each subsystem consists of two neural networks (NNs), an action NN that is aimed to provide a nearly optimal control signal, and a critic NN which evaluates the performance of the overall system. All NN parameters are tuned online for both the NNs. By using Lyapunov techniques it is shown that all subsystems signals are uniformly ultimately bounded and that the synthesized subsystems inputs approach their corresponding nearly optimal control inputs with bounded error. Simulation results are included to show the effectiveness of the approach. © 2011 IEEE.
Schoegl I.,Louisiana State University
Combustion and Flame | Year: 2014
In reduced-order modeling of premixed combustion, a major concern is whether chemistry submodels capture flame characteristics over a broad range of mixture stoichiometries and reactant temperatures. In order to adapt to local temperature level and stoichiometry, models require a suitable parameterization. Post-processing of a large database of adiabatic laminar flame simulations reveals that characteristic temperatures within premixed flames can be collapsed to self-similar structures throughout the lean and ultra-lean premixed regime. The collapse depends on the parameterization, where adiabatic flame temperatures Tad and stoichiometry Φ are identified as natural primary and secondary parameters, respectively. Furthermore, parameterizations of chemical source terms are superior to parameterizations of species profiles, as they allow for a differentiation of chemical processes from transport processes. A comparison of flame characteristics at low and high Tad illustrates that reaction pathways and resulting contributions to the heat release by individual reactions shift according to the temperature level, whereas flames with comparable Tad have similar flame structures that are almost independent of initial temperatures and stoichiometries. © 2013 The Combustion Institute.
Nagarajan V.K.,University of Delaware |
Smith A.P.,Louisiana State University
Plant and Cell Physiology | Year: 2012
Phosphate (Pi) is a common limiter of plant growth due to its low availability in most soils. Plants have evolved elaborate mechanisms for sensing Pi deficiency and for initiating adaptive responses to low Pi conditions. Pi signaling pathways are modulated by both local and long-distance, or systemic, sensing mechanisms. Local sensing of low Pi initiates major root developmental changes aimed at enhancing Pi acquisition, whereas systemic sensing governs pathways that modulate expression of numerous genes encoding factors involved in Pi transport and distribution. The gaseous phytohormone ethylene has been shown to play an integral role in regulating local, root developmental responses to Pi deficiency. Comparatively, a role for ethylene in systemic Pi signaling has been more circumstantial. However, recent studies have revealed that ethylene acts to modulate a number of systemically controlled Pi starvation responses. Herein we highlight the findings from these studies and offer a model for how ethylene biosynthesis and responsiveness are integrated into both local and systemic Pi signaling pathways. © 2011 The Author.
Gleason E.,Louisiana State University
Visual Neuroscience | Year: 2012
Amacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed. © Copyright Cambridge University Press 2011.
Mazenc F.,French National Institute for Agricultural Research |
Malisoff M.,Louisiana State University
IEEE Transactions on Automatic Control | Year: 2010
We provide new techniques for building explicit global strict Lyapunov functions for broad classes of periodic time varying nonlinear systems satisfying LaSalle conditions. We illustrate our work using the Lotka-Volterra model, which plays a fundamental role in bioengineering. We use our strict Lyapunov constructions to prove robustness of the Lotka-Volterra tracking dynamics to uncertainty in the death rates. © 2006 IEEE.
Gambini R.,Institute Fisica |
Pullin J.,Louisiana State University
Physical Review Letters | Year: 2013
We quantize spherically symmetric vacuum gravity without gauge fixing the diffeomorphism constraint. Through a rescaling, we make the algebra of Hamiltonian constraints Abelian, and therefore the constraint algebra is a true Lie algebra. This allows the completion of the Dirac quantization procedure using loop quantum gravity techniques. We can construct explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. New observables living in the bulk appear at the quantum level (analogous to spin in quantum mechanics) that are not present at the classical level and are associated with the discrete nature of the spin network states of loop quantum gravity. The resulting quantum space-times resolve the singularity present in the classical theory inside black holes. © 2013 American Physical Society.
Kappen C.,Louisiana State University
PLoS ONE | Year: 2016
The process of patterning along the anterior-posterior axis in vertebrates is highly conserved. The function of Hox genes in the axis patterning process is particularly well documented for bone development in the vertebral column and the limbs. We here show that Hoxb6, in skeletal elements at the cervico-Thoracic junction, controls multiple independent aspects of skeletal pattern, implicating discrete developmental pathways as substrates for this transcription factor. In addition, we demonstrate that Hoxb6 function is subject to modulation by genetic factors. These results establish Hox-controlled skeletal pattern as a quantitative trait modulated by gene-gene interactions, and provide evidence that distinct modifiers influence the function of conserved developmental genes in fundamental patterning processes. © 2016 Claudia Kappen. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Pence C.H.,Louisiana State University
PLoS ONE | Year: 2016
While textual analysis of the journal literature is a burgeoning field, there is still a profound lack of user-friendly software for accomplishing this task. RLetters is a free, open-source web application which provides researchers with an environment in which they can select sets of journal articles and analyze them with cutting-edge textual analysis tools. RLetters allows users without prior expertise in textual analysis to analyze word frequency, collocations, cooccurrences, term networks, and more. It is implemented in Ruby and scripts are provided to automate deployment. © 2016 Charles H. Pence. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Martin M.J.,Louisiana State University
Journal of Applied Mechanics, Transactions ASME | Year: 2011
The frequency response of a flat plate in a viscous fluid is a problem with applications in microsystems, including gyroscopes, accelerometers, viscometers, and biological sensing. To find the frequency response away from the resonant frequency, the equations of motion are combined with the solution to Stokes' second problem to produce an analytic solution for the motion of the plate in response to a sinusoidal driving force. These results are used to determine the gain, phase lag, and dynamic stability of the system. The behavior of the system depends on an effective damping ratio ζ eff, which depends on the resonator dimensions, and is proportional to the square root of the viscosity times the fluid density. © 2011 American Society of Mechanical Engineers.
Gaschen L.,Louisiana State University
Veterinary Clinics of North America - Small Animal Practice | Year: 2011
Ultrasonography, which has become a mainstay of diagnosing intestinal diseases in dogs and cats, is often one of the first diagnostic tools used to differentiate inflammatory from neoplastic infiltration of the small intestine. Although overlap in the sonographic appearances of inflammatory and neoplastic infiltration make a definitive diagnosis difficult, awareness of features of both diseases is important for the accurate interpretation of the sonographic findings. Full-thickness intestinal biopsy remains the gold standard for differentiating inflammatory from neoplastic disease of the small intestine. © 2011.
Mehraeen S.,Louisiana State University |
Jagannathan S.,Missouri University of Science and Technology |
Crow M.L.,Missouri University of Science and Technology
IEEE Transactions on Neural Networks | Year: 2011
A novel neural network (NN)-based nonlinear decentralized adaptive controller is proposed for a class of large-scale, uncertain, interconnected nonlinear systems in strict-feedback form by using the dynamic surface control (DSC) principle, thus, the explosion of complexity problem which is observed in the conventional backstepping approach is relaxed in both state and output feedback control designs. The matching condition is not assumed when considering the interconnection terms. Then, NNs are utilized to approximate the uncertainties in both subsystem and interconnected terms. By using novel NN weight update laws with quadratic error terms as well as proposed control inputs, it is demonstrated using Lyapunov stability that the system states errors converge to zero asymptotically with both state and output feedback controllers, even in the presence of NN approximation errors in contrast with the uniform ultimate boundedness result, which is common in the literature with NN-based DSC and backstepping schemes. Simulation results show the effectiveness of the approach. © 2011 IEEE.
Sarker B.R.,Louisiana State University
International Journal of Production Economics | Year: 2014
This paper studies the consignment stocking policy models for supply chain systems and categorizes different models from the view point of structural configuration of the systems, operational policies, component analyses, cost and profit measurements, and several other standard measures used in inventory management. A comprehensive survey of the models and their critical analyses are pursued here to understand the operational mechanics of different consignment policies that vary from product to product and system to system. The isolation mechanisms used for modeling are different types of supply systems, consignment types, operational mechanism, physical and/or geographical locations, and operational constraints, to name a few. The exercise performed here systematically identifies the appropriateness, and different advantages and disadvantages of the models. This study also examines different consignment models for determining manufacturing batch sizes, order quantity deliverable to the retailers, advertisement and price of the products, profits, independent and centralized operational policies for vendor and buyers, and optimizes many other system parameters and controllable operational variables. The review of the literature sheds different comparative perspectives of the models from practical point of applications and revelation of their theoretical underpinnings. The models have been examined from the managerial insights and several hints on applications of them have been indicated as appropriate in different locations. Several avenues for future research have also been pin-pointed to enrich this area of research on consignment policy. © 2014 Elsevier B.V. All rights reserved.
Li S.,Louisiana State University
International Journal of Molecular Sciences | Year: 2012
Histones are highly alkaline proteins that package and order the DNA into chromatin in eukaryotic cells. Nucleotide excision repair (NER) is a conserved multistep reaction that removes a wide range of generally bulky and/or helix-distorting DNA lesions. Although the core biochemical mechanism of NER is relatively well known, how cells detect and repair lesions in diverse chromatin environments is still under intensive research. As with all DNA-related processes, the NER machinery must deal with the presence of organized chromatin and the physical obstacles it presents. A huge catalogue of posttranslational histone modifications has been documented. Although a comprehensive understanding of most of these modifications is still lacking, they are believed to be important regulatory elements for many biological processes, including DNA replication and repair, transcription and cell cycle control. Some of these modifications, including acetylation, methylation, phosphorylation and ubiquitination on the four core histones (H2A, H2B, H3 and H4) or the histone H2A variant H2AX, have been found to be implicated in different stages of the NER process. This review will summarize our recent understanding in this area. © 2012 by the authors; licensee MDPI, Basel, Switzerland.
Tsai F.T.-C.,Louisiana State University
Stochastic Environmental Research and Risk Assessment | Year: 2010
This study introduces Bayesian model averaging (BMA) to deal with model structure uncertainty in groundwater management decisions. A robust optimized policy should take into account model parameter uncertainty as well as uncertainty in imprecise model structure. Due to a limited amount of groundwater head data and hydraulic conductivity data, multiple simulation models are developed based on different head boundary condition values and semivariogram models of hydraulic conductivity. Instead of selecting the best simulation model, a variance-window-based BMA method is introduced to the management model to utilize all simulation models to predict chloride concentration. Given different semivariogram models, the spatially correlated hydraulic conductivity distributions are estimated by the generalized parameterization (GP) method that combines the Voronoi zones and the ordinary kriging (OK) estimates. The model weights of BMA are estimated by the Bayesian information criterion (BIC) and the variance window in the maximum likelihood estimation. The simulation models are then weighted to predict chloride concentrations within the constraints of the management model. The methodology is implemented to manage saltwater intrusion in the 1,500-foot sand aquifer in the Baton Rouge area, Louisiana. The management model aims to obtain optimal joint operations of the hydraulic barrier system and the saltwater extraction system to mitigate saltwater intrusion. A genetic algorithm (GA) is used to obtain the optimal injection and extraction policies. Using the BMA predictions, higher injection rates and pumping rates are needed to cover more constraint violations, which do not occur if a single best model is used. © 2010 Springer-Verlag.
Pagnotta A.,American Museum of Natural History |
Schaefer B.E.,Louisiana State University
Astrophysical Journal | Year: 2015
Although Type Ia supernovae have been heavily scrutinized due to their use in making cosmological distance estimates, we are still unable to definitively identify the progenitors for the entire population. While answers have been presented for certain specific systems, a complete solution remains elusive. We present observations of two supernova remnants (SNRs) in the Large Magellanic Cloud, SNR 0505-67.9 and SNR 0509-68.7, for which we have identified the center of the remnant and the 99.73% containment central region in which any companion star left over after the supernova must be located. Both remnants have a number of potential ex-companion stars near their centers; all possible single and double degenerate progenitor models remain viable for these two supernovae. Future observations may be able to identify the true ex-companions for both remnants. © 2015. The American Astronomical Society. All rights reserved..
Solmon M.A.,Louisiana State University
Advances in Child Development and Behavior | Year: 2014
The benefits associated with engaging in regular physical activity are well documented, but a large segment of the population is not sufficiently active. School physical education and sport programs are identified as important components in efforts to promote physical activity. Girls are less active than boys, and there is evidence that physical education programs are not effectively meeting their needs. The focus of this chapter is to examine gender as a construct in the domains of physical education and sport, clarifying the reasons girls tend to be less active and less involved in physical education. Following an historical overview, curricular issues and motivational aspects are considered. Implications are focused on ways that educators can provide positive experiences for all students in physical education and sport that will encourage them to adopt and maintain healthy active lifestyles and enhance their quality of life across the life span. © 2014 Elsevier Inc.
Motes K.R.,Macquarie University |
Gilchrist A.,Macquarie University |
Dowling J.P.,Louisiana State University |
Rohde P.P.,Macquarie University
Physical Review Letters | Year: 2014
We present an architecture for arbitrarily scalable boson sampling using two nested fiber loops. The architecture has fixed experimental complexity, irrespective of the size of the desired interferometer, whose scale is limited only by fiber and switch loss rates. The architecture employs time-bin encoding, whereby the incident photons form a pulse train, which enters the loops. Dynamically controlled loop coupling ratios allow the construction of the arbitrary linear optics interferometers required for boson sampling. The architecture employs only a single point of interference and may thus be easier to stabilize than other approaches. The scheme has polynomial complexity and could be realized using demonstrated present-day technologies. © 2014 American Physical Society.
Webb A.A.G.,Louisiana State University
Geosphere | Year: 2013
A line-length balanced palinspastic reconstruction across the Himachal Himalaya is presented, highlighting different phases of Himalayan tectonic development: Eocene shortening of the north Indian margin, Early-Middle Miocene emplacement of the crystalline core, and subsequent growth of the range by underplating. The total preserved shortening is 518 km (72%). The reconstruction demonstrates geometric feasibility of crystalline core emplacement via tectonic wedging, i.e., between a southdirected thrust (the Main Central thrust) and a north-directed backthrust (the South Tibet detachment). Crystalline core exposure between these faults occurs ca. 5Ma in the reconstruction; initial exposure of these crystalline rocks ca. 11 Ma probably occurred in the hinterland within core complexes accommodating east-west extension. After Early-Middle Miocene crystalline core emplacement, ongoing orogenic growth is dominated by underplating processes. Outof-sequence faulting accomplishes <5% of this shortening; frontal accretion of foreland rocks occurs, but the resulting imbricate fan is largely eroded away. Over the past 3-5 m.y., an antiformal stack of mid-crustal horses and a hinterland-dipping duplex of upper crustal horses develop simultaneously. Minimum total shortening across the western Himalaya (fromundeformed foreland to the India-Asia suture) is estimated by adding the new results and results from prior work to the north; an estimate of ~703-773 km of assessed shortening is calculated. However, because large portions of the regional deformation remain unassessed, estimates of ~900-1100 km may more accurately refl ect the minimum preserved shortening here. This range is comparable to the~1350 km of shortening estimated by plate circuit reconstructions for this region. Apparent mismatch between geologic and plate circuit shortening estimates has recently instigated the new Greater India Basin hypothesis for two Cenozoic collisions along Asia's southern margin, but the new results suggest that this mismatch may not exist. © 2013 Geological Society of America.
Worley J.A.,Louisiana State University
Developmental neurorehabilitation | Year: 2011
The diagnostic stability of Autism Spectrum Disorders (ASD) at very young ages continues to be debated, despite empirical evidence that ASDs can be reliably diagnosed in children under the age of 3 years. This topic is of the upmost importance given that early intervention increases long-term outcomes in this population. The goal of the current study was to examine the stability of symptoms of ASD between two assessment times for 114 toddlers. The following was compared from the first to second assessment: diagnostic classification stability, correlations between scores and the impact of time between the first and second assessment. Significant correlations were found for toddlers as young as 18 months of age. In addition, even with up to a year between assessment intervals, symptoms of ASD were relatively stable prior to 3 years of age. Implications of the current findings are discussed.
Carney R.S.,Louisiana State University
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2010
Hydrocarbon-seep communities in the Gulf of Mexico have a high biomass that is exploited as a food source to varying degrees by the photosynthesis-dependent fauna inhabiting the surrounding mud bottom. A decline concurrent with ocean depth in detritus influx to that background habitat results in a much lower background biomass. The biomass contrast between population-rich seeps and depauperate mud bottom leads to the prediction that seep utilization by the background fauna should be extensive at all depths and should increase with depth. Species depth zonation makes like-species comparisons over the full depth of the Gulf of Mexico impossible. Seeps and normal bottom above 1000m have different fauna from those below 1000m. Lower slope seeps are surrounded by a fauna rich in echinoderm species, especially asteroids, ophiuroids, and holothuroids. All three taxa have species that are abundant within seeps and are probably endemic to them. They also contain species found only in mud background or within mud and seeps backgrounds. Tissue analyses of δ 13C and δ 15N of echinoderms collected by ROV within seeps and trawling away from seeps indicate a pattern of utilization similar to that found in upper slope seeps exploited by different taxa. Seastar and ophiuroid species abundant in or endemic to seeps have tissue isotope values reflecting seep chemosynthetic input via a free-living microbial detritus or predation. A single seep-endemic deposit-feeding holothuroid showed distinct seep tissue values. Background deposit-feeding holothuroids collected within seeps showed either no or only minor incorporation of seep carbon, indicating either a lack of access to seep detritus or short feeding times within the seep. A predicted extensive utilization of seep productivity at the deeper seeps was not found. Seeps may be relatively closed systems that require special adaptations of species in order for them to enter, exploit, and survive. Alternately, the surrounding deep benthos may not be as food-poor as assumed from biomass measurements and flux estimates. © 2010.
Baksi A.K.,Louisiana State University
Quaternary Geochronology | Year: 2012
The guidelines set out by Renne et al. (2009) offer a start to potentially removing numerous problems often associated with the reporting of 40Ar 39Ar ages in the literature. Herein, some recommendations are made concerning aspects of how, in what form, and with what " corrections" , supporting argon isotopic data should be published. © 2012 Elsevier B.V.
Zhang S.,Louisiana State University |
Li L.,Georgia Southern University
Gait and Posture | Year: 2013
Foot sole tactile sensation provides valuable feedback to the central nervous system. Acutely reduced foot sensation changes plantar pressure distribution in standing and gait; however, the effect of chronic foot sole sensory impairment on plantar pressure distribution is unclear. Purpose: This study aims to examine the effects of peripheral neuropathy (PN) induced chronic sensory loss on plantar pressure distribution in walking and standing. Methods: Foot sole sensitivity was tested at the five sites: big toe (BT), 1st metatarsal (M1), 5th metatarsal (M5), mid-foot (MF) and heel (HL). Relative peak pressures (RPP) of the five sites were collected during a 20-s walking on a treadmill at .45. m/s and a 30-s quiet standing with eyes open. Five-way MANOVA was used to examine the influence of sensitivity of each site on overall plantar pressure distribution for standing and walking separately. Tukey's test was used to examine the significant associations. Results: In standing, the sensitivity of BT affected average RPP at BT significantly (. P<. .05), where RPP associated with insensitive BT (8.1. ±. 5.7%) was greater than with sensitive BT (4.5. ±. 4.9%). Furthermore, the RPP at HL was greater for insensitive MF (36.1. ±. 17.9%) compared with sensitive MF (23.6. ±. 7.4%) (. P<. .05). No pressure distribution changes were observed in walking. Conclusions: Feedback from foot sole tactile sensation in gait is not as significant as in standing, showing standing balance control relies more on feedback control mechanism while gait control relies more on feed forward control mechanism. © 2012.
Alvarez N.,Institute Fisica |
Gambini R.,Institute Fisica |
Pullin J.,Louisiana State University
Physical Review Letters | Year: 2012
We present a gauge fixing of gravity coupled to a scalar field in spherical symmetry such that the Hamiltonian is an integral over space of a local density. Such a formulation had proved elusive over the years. As in any gauge fixing, it works for a restricted set of initial data. We argue that the set could be large enough to attempt a quantization the could include the important case of an evaporating black hole. Published by the American Physical Society under the terms of the < uri xlink:href="http://creativecommons.org/ licenses/by/3.0/"> Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. © 2012 American Physical Society.
Chang S.J.,Louisiana State University
Forest Policy and Economics | Year: 2013
More than just an environmental challenge, the problem of carbon dioxide emissions is a basic human rights issue. This paper proposes a solution to the problem based on the proposition of Green Human Right that all men are created equal and thus entitled to equal carbon dioxide emissions per person. Countries with per capita carbon dioxide emissions above that of the global average must pay for the privilege to pollute. Conversely, countries with that below the global average are entitled to compensations.To determine the excess or slack carbon dioxide emissions of individual countries, the total carbon dioxide emissions of every country are adjusted for international trade to account for carbon dioxide out-sourcing and carbon sequestration by forests and forest products to arrive at their net carbon dioxide emissions. Countries with above the global average in net per capita carbon dioxide emissions have excess emissions. Those with below the global average have slack emissions. Total excess or slack carbon dioxide emissions are determined by multiplying the per capita excess or slack per capita emissions by its population. They then pay into or get compensated from the Green Climate Fund based on their respective excess or slack carbon dioxide emissions.Based on the total excess carbon dioxide emission figures from 2009 and $10 per ton of carbon dioxide emissions, major excess emission countries and the amount of money they would pay into the Green Climate Fund are the U.S. $40.8. billion, Japan $7.8. billion, U.K. $5.1. billion, Canada $4.7. billion, Germany $4.6. billion, and Russia $4.2. billion. China, for the first time, also would become an excess emission country and would pay $446. million, thus obliterating the artificial separation between developed and developing countries and removing a major stumbling block in climate change negotiations. Major slack emission countries and the amount of money they would earn from the Green Climate Fund are India $3.7. billion, Pakistan $645. million, Bangladesh $626. million, Nigeria $433. million, Ethiopia $358. million, the Philippines $351. million and Vietnam $333. million.The incentives created by the proposed solution would propel all countries to focus on controlling or lowering their total global carbon dioxide emissions. Excess emission countries have incentives to reduce their carbon dioxide emissions to lower their payments. Slack countries also have incentives to lower or limit their emissions, if they want to keep earning money over time. When the price of carbon dioxide emissions is high enough, its impact on the global carbon dioxide emissions would be significant. Furthermore, as a dynamic system, every year the price set for carbon dioxide emissions would depend on how quickly the total global carbon dioxide emissions are being reduced through conservation efforts and technical innovations. Once the price is set, there is total transparency. Every country will know exactly how much it would either pay into or earn from the Green Climate Fund, sparing rich countries from haggling over how much each will pay and poor countries over how much each will earn.© 2013 Elsevier B.V.
Stout M.J.,Louisiana State University
Insect Science | Year: 2013
Applied research on host-plant resistance to arthropod pests has been guided over the past 60 years by a framework originally developed by Reginald Painter in his 1951 book, Insect Resistance in Crop Plants. Painter divided the "phenomena" of resistance into three "mechanisms," nonpreference (later renamed antixenosis), antibiosis, and tolerance. The weaknesses of this framework are discussed. In particular, this trichotomous framework does not encompass all known mechanisms of resistance, and the antixenosis and antibiosis categories are ambiguous and inseparable in practice. These features have perhaps led to a simplistic approach to understanding arthropod resistance in crop plants. A dichotomous scheme is proposed as a replacement, with a major division between resistance (plant traits that limit injury to the plant) and tolerance (plant traits that reduce amount of yield loss per unit injury), and the resistance category subdivided into constitutive/inducible and direct/indirect subcategories. The most important benefits of adopting this dichotomous scheme are to more closely align the basic and applied literatures on plant resistance and to encourage a more mechanistic approach to studying plant resistance in crop plants. A more mechanistic approach will be needed to develop novel approaches for integrating plant resistance into pest management programs. © 2012 Institute of Zoology, Chinese Academy of Sciences.
Giovannoni S.J.,Oregon State University |
Cameron Thrash J.,Oregon State University |
Cameron Thrash J.,Louisiana State University |
Temperton B.,Oregon State University |
Temperton B.,Plymouth Marine Laboratory
ISME Journal | Year: 2014
Whether a small cell, a small genome or a minimal set of chemical reactions with self-replicating properties, simplicity is beguiling. As Leonardo da Vinci reportedly said, 'simplicity is the ultimate sophistication'. Two diverging views of simplicity have emerged in accounts of symbiotic and commensal bacteria and cosmopolitan free-living bacteria with small genomes. The small genomes of obligate insect endosymbionts have been attributed to genetic drift caused by small effective population sizes (N e). In contrast, streamlining theory attributes small cells and genomes to selection for efficient use of nutrients in populations where N e is large and nutrients limit growth. Regardless of the cause of genome reduction, lost coding potential eventually dictates loss of function. Consequences of reductive evolution in streamlined organisms include atypical patterns of prototrophy and the absence of common regulatory systems, which have been linked to difficulty in culturing these cells. Recent evidence from metagenomics suggests that streamlining is commonplace, may broadly explain the phenomenon of the uncultured microbial majority, and might also explain the highly interdependent (connected) behavior of many microbial ecosystems. Streamlining theory is belied by the observation that many successful bacteria are large cells with complex genomes. To fully appreciate streamlining, we must look to the life histories and adaptive strategies of cells, which impose minimum requirements for complexity that vary with niche. © 2014 International Society for Microbial Ecology All rights reserved.
Buscemi F.,Nagoya University |
Hall M.J.W.,Griffith University |
Ozawa M.,Nagoya University |
Wilde M.M.,Louisiana State University
Physical Review Letters | Year: 2014
We introduce information-theoretic definitions for noise and disturbance in quantum measurements and prove a state-independent noise-disturbance tradeoff relation that these quantities have to satisfy in any conceivable setup. Contrary to previous approaches, the information-theoretic quantities we define are invariant under the relabelling of outcomes and allow for the possibility of using quantum or classical operations to "correct" for the disturbance. We also show how our bound implies strong tradeoff relations for mean square deviations. © 2014 American Physical Society.
Finley J.W.,Louisiana State University |
Seiber J.N.,University of California at Davis
Journal of Agricultural and Food Chemistry | Year: 2014
The Earth's population is expected to exceed 9 billion by 2050, posing significant challenges in meeting human needs while minimally affecting the environment. To support this population, we will need secure and safe sources of food, energy, and water. The nexus of food, energy, and water is one of the most complex, yet critical, issues that face society. There is no more land to exploit, and the supply of fresh water in some areas of the world limits the use of land for food. All solutions must also deal with the overlay of global climate change. Meeting current and future populations needs will require security in food, energy, and water supplies. A nexus approach is needed to improve food, energy, and water security integrating the management of the limited resources while transitioning to a more "green" economy, which provides adequate food, energy, and water for the expanding human population. © 2014 American Chemical Society.
Rovelli C.,Aix - Marseille University |
Rovelli C.,University of Toulon |
Wilson-Ewing E.,Louisiana State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014
We point out that the relative Heisenberg uncertainty relations vanish for noncompact spaces in homogeneous loop quantum cosmology. As a consequence, for sharply peaked states quantum fluctuations in the scale factor never become important, even near the bounce point. This shows why quantum backreaction effects remain negligible and explains the surprising accuracy of the effective equations in describing the dynamics of sharply peaked wave packets. This also underlines the fact that minisuperspace models - where it is global variables that are quantized - do not capture the local quantum fluctuations of the geometry. © 2014 American Physical Society.
Cenfetelli R.T.,University of British Columbia |
Schwarz A.,Louisiana State University
Information Systems Research | Year: 2011
An important area of information systems (IS) research has been the identification of the individual-level Abeliefs that enable technology acceptance such as the usefulness, reliability, and flexibility of a system. This study posits the existence of additional beliefs that inhibit usage intentions and thus foster technology rejection rather than acceptance. We theorize that these inhibitors are more than just the antipoles of enablers (e.g., the opposite of usefulness or reliability) and so are distinct constructs worthy of their own investigation. Inhibitors are proposed to have effects on usage intentions beyond that of enablers as well as effects on enablers themselves. We report on a series of empirical studies designed to test the existence and effects of inhibitors. A candidate set of six inhibitors is shown to be distinct from enablers. These inhibitors are subsequently tested in a field study of 387 individuals nested within 32 different websites. Effects at both individual and website unit levels of analysis are tested using multilevel modeling. We find that inhibitors have negative effects on usage intentions, as well as on enablers, and these effects vary contingent upon individual or website unit levels of analysis. The overall results support the existence and importance of inhibitors in explaining individual intent to use-or not use-technology. © 2011 INFORMS.
Hafermann H.,Ecole Polytechnique - Palaiseau |
Patton K.R.,Louisiana State University |
Werner P.,ETH Zurich
Physical Review B - Condensed Matter and Materials Physics | Year: 2012
We propose efficient measurement procedures for the self-energy and vertex function of the Anderson impurity model within the hybridization expansion continuous-time quantum Monte Carlo algorithm. The method is based on the measurement of higher-order correlation functions related to the quantities being sought through the equation of motion, a technique previously introduced in the numerical renormalization-group context. For the case of interactions of density-density type, the additional correlators can be obtained at essentially no additional computational cost. In combination with a recently introduced method for filtering the Monte Carlo noise using a representation in terms of orthogonal polynomials, we obtain data with unprecedented accuracy. This leads to an enhanced stability in analytical continuations of the self-energy or in two-particle-based theories such as the dual fermion approach. As an illustration of the method we reexamine the previously reported spin-freezing and high-spin to low-spin transitions in a two-orbital model with density-density interactions. In both cases, the vertex function undergoes significant changes, which suggests significant corrections to the dynamical mean-field solutions in dual fermion calculations. © 2012 American Physical Society.
de Veylder L.,Vlaams Institute for Biotechnology |
de Veylder L.,Ghent University |
Larkin J.C.,University of Strasbourg |
Larkin J.C.,Louisiana State University |
Schnittger A.,University of Strasbourg
Trends in Plant Science | Year: 2011
Endoreplication, also called endoreduplication, is a cell cycle variant of multicellular eukaryotes in which mitosis is skipped and cells repeatedly replicate their DNA, resulting in cellular polyploidy. In recent years, research results have shed light on the molecular mechanism of endoreplication control, but the function of this cell-cycle variant has remained elusive. However, new evidence is at last providing insight into the biological relevance of cellular polyploidy, demonstrating that endoreplication is essential for developmental processes, such as cell fate maintenance, and is a prominent response to physiological conditions, such as pathogen attack or DNA damage. Thus, endoreplication is being revealed as an important module in plant growth that contributes to the robustness of plant life. © 2011 Elsevier Ltd.
Greenway F.L.,Louisiana State University
International Journal of Obesity | Year: 2015
Obesity is a major global health problem and predisposes individuals to several comorbidities that can affect life expectancy. Interventions based on lifestyle modification (for example, improved diet and exercise) are integral components in the management of obesity. However, although weight loss can be achieved through dietary restriction and/or increased physical activity, over the long term many individuals regain weight. The aim of this article is to review the research into the processes and mechanisms that underpin weight regain after weight loss and comment on future strategies to address them. Maintenance of body weight is regulated by the interaction of a number of processes, encompassing homoeostatic, environmental and behavioural factors. In homoeostatic regulation, the hypothalamus has a central role in integrating signals regarding food intake, energy balance and body weight, while an 'obesogenic' environment and behavioural patterns exert effects on the amount and type of food intake and physical activity. The roles of other environmental factors are also now being considered, including sleep debt and iatrogenic effects of medications, many of which warrant further investigation. Unfortunately, physiological adaptations to weight loss favour weight regain. These changes include perturbations in the levels of circulating appetite-related hormones and energy homoeostasis, in addition to alterations in nutrient metabolism and subjective appetite. To maintain weight loss, individuals must adhere to behaviours that counteract physiological adaptations and other factors favouring weight regain. It is difficult to overcome physiology with behaviour. Weight loss medications and surgery change the physiology of body weight regulation and are the best chance for long-term success. An increased understanding of the physiology of weight loss and regain will underpin the development of future strategies to support overweight and obese individuals in their efforts to achieve and maintain weight loss. © 2015 Macmillan Publishers Limited. All rights reserved.
Balasubramanian S.,Louisiana State University |
Panigrahi S.,Purdue University
Food and Bioprocess Technology | Year: 2011
Solid-phase microextraction (SPME) is a relatively new sampling technique wherein sample extraction and pre-concentration could be achieved in a single step. The handling of an SPME device is simple, and the analysis of volatiles could be easy. However, the process becomes complex while analyzing sample matrices of heterogeneous nature. The complexity also increases depending upon the nature of compounds to be extracted. Careful selection and optimization of extraction parameters like fiber coating selection, extraction time, agitation, addition of salt, and extraction temperature have to be undertaken to improve the sensitivity and the reproducibility of this method. This paper reviews the principles associated with SPME technique from a general application viewpoint. Also, a comprehensive review of prior research related to characterization of food quality has been reported. SPME-related solutions for environmental applications have also been analyzed to be applied for new food-related applications. © 2010 Springer Science + Business Media, LLC.
McVay J.D.,Louisiana State University |
Carstens B.,Ohio State University
Molecular Phylogenetics and Evolution | Year: 2013
Ideally, existing taxonomy would be consistent with phylogenetic estimates derived from rigorously analyzed data using appropriate methods. We present a multi-locus molecular analysis of the relationships among nine genera in the North American snake tribe Thamnophiini in order to test the monophyly of the crayfish snakes (genus Regina) and the earth snakes (genus Virginia). Sequence data from seven genes were analyzed to assess relationships among representatives of the nine genera by performing multi-locus phylogeny and species tree estimations, and we performed constraint-based tests of monophyly of classic taxonomic designations on a gene-by-gene basis. Estimates of concatenated phylogenies demonstrate that neither genera are monophyletic, and this inference is supported by a species tree estimate, though the latter is less robust. These taxonomic findings were supported using gene tree constraint tests and Bayes Factors, where we rejected the monophyly of both the crayfish snakes (genus Regina) and the earth snakes (genus Virginia); this method represents a potentially useful tool for taxonomists and phylogeneticists when available data is less than ideal. © 2013 Elsevier Inc.
Cryptic patterns of diversification of a widespread Amazonian Woodcreeper species complex (Aves: Dendrocolaptidae) inferred from multilocus phylogenetic analysis: Implications for historical biogeography and taxonomy
Sousa-Neves T.,University of Porto |
Aleixo A.,Louisiana State University |
Sequeira F.,University of Porto
Molecular Phylogenetics and Evolution | Year: 2013
Inferring evolutionary relationships between recently diverged taxa is still challenging, especially taking into account the likely occurrence of incomplete lineage sorting and/or introgression. The Xiphorhynchus pardalotus/ocellatus species complex includes between two to three polytypic species and eight to nine subspecies distributed throughout most of lowland Amazonia and the foothills of the eastern Andes. To understand its historical diversification and address the main unsettled issues of phylogenetic relationships and taxonomy, we apply several approaches using data from two mitochondrial (Cyt b and ND2) and three nuclear genes (β-fibint7, CPZint3 and CRYAAint1) for all described species and most subspecies of this complex. We compared single gene trees with a multilocus concatenated tree and Bayesian species tree inferred under a coalescent framework (*BEAST). Our results showed a general pattern of incongruence among gene trees and multilocus trees. Despite of this, the coalescent-based species tree analysis supports the sister-taxa relationship of X. ocellatus and X. chunchotambo, while X. pardalotus comes out as the basal taxon. With exception of the last, our results revealed within both X. ocellatus and X. chunchotambo high levels of genetic differentiation (p-distances 0.5-5.5%) with well-supported lineages. Our phylogenetic analyses showed several incongruences with current subspecies taxonomy, revealing that X. o. ocellatus is paraphyletic relative to X. o. perplexus, and the currently recognized subspecies X. c. napensis corresponds to two distinct evolutionary lineages, which are not supported as sister-lineages. In addition, the deep level of genetic divergence between X. o. beauperthuysii and the extant subspecies of X. ocellatus is more consistent with species-level differences found in this complex. Divergence time estimates were consistent with a historical scenario of intense population subdivision and speciation during the Early-mid Pleistocene. The spatial pattern and timing of diversification overlap broadly with that reported for other Amazonian vertebrate lineages. © 2013 Elsevier Inc.
Caminita C.M.,Louisiana State University
Journal of Agricultural and Food Information | Year: 2015
In fall 2012, the agriculture librarian at Louisiana State University Libraries began to embed library instruction, resources, and services within the University's Agricultural Residential College. The purpose of the collaboration was to incorporate information literacy into the agriculture curriculum and to introduce 1st-year students to library services and resources. The collaboration resulted in a number of benefits for the agriculture librarian and the agriculture college. Sustaining the collaboration is a challenge with changes in leadership and program focus. This article will describe the agriculture librarian's embedding efforts, identify issues in sustaining such a high level of embedding, and discuss strategies for moving the collaboration forward. © 2015, Published with license by Taylor & Francis.
Bastian F.O.,Louisiana State University
Journal of Neuropathology and Experimental Neurology | Year: 2014
Spiroplasma biofilm formation explains the role of these wall-less bacteria in the pathogenesis of transmissible spongiform encephalopathies (TSEs). Spiroplasma embedded in the biofilm polysaccharide matrix are markedly resistant to physical and chemical treatment, simulating the biologic properties of the TSE agent. Microcolonies of spiroplasma embedded in biofilm bound to clay are the likely mechanism of lateral transmission of scrapie in sheep and chronic wasting disease in deer via soil ingestion. Spiroplasma in biofilm bound to the stainless steel of surgical instruments may also cause iatrogenic transmission of Creutzfeldt-Jakob disease. Sessile spiroplasma in biofilm attach to the surface by curli-like fibrils, a functional amyloid that is important for spiroplasma entering cells. Curli fibers have been shown to interact with host proteins and initiate formation of a potentially toxic amyloid that multiplies by self-assembly. In TSE, this mechanism may explain how spiroplasma trigger the formation of prion amyloid. This possibility is supported by experiments that show spiroplasma produce α-synuclein in mammalian tissue cultures. The data linking spiroplasma to neurodegenerative diseases provide a rationale for developing diagnostic tests for TSE based on the presence of spiroplasma-specific proteins or nucleic acid. Research efforts should focus on this bacterium for development of therapeutic regimens for Creutzfeldt-Jakob disease. © 2014 by the American Association of Neuropathologists, Inc.
Deegan L.A.,Ecosystems Center |
Johnson D.S.,Ecosystems Center |
Johnson D.S.,Sewanee: The University of the South |
Warren R.S.,Connecticut College |
And 4 more authors.
Nature | Year: 2012
Salt marshes are highly productive coastal wetlands that provide important ecosystem services such as storm protection for coastal cities, nutrient removal and carbon sequestration. Despite protective measures, however, worldwide losses of these ecosystems have accelerated in recent decades. Here we present data from a nine-year whole-ecosystem nutrient-enrichment experiment. Our study demonstrates that nutrient enrichment, a global problem for coastal ecosystems, can be a driver of salt marsh loss. We show that nutrient levels commonly associated with coastal eutrophication increased above-ground leaf biomass, decreased the dense, below-ground biomass of bank-stabilizing roots, and increased microbial decomposition of organic matter. Alterations in these key ecosystem properties reduced geomorphic stability, resulting in creek-bank collapse with significant areas of creek-bank marsh converted to unvegetated mud. This pattern of marsh loss parallels observations for anthropogenically nutrient-enriched marshes worldwide, with creek-edge and bay-edge marsh evolving into mudflats and wider creeks. Our work suggests that current nutrient loading rates to many coastal ecosystems have overwhelmed the capacity of marshes to remove nitrogen without deleterious effects. Projected increases in nitrogen flux to the coast, related to increased fertilizer use required to feed an expanding human population, may rapidly result in a coastal landscape with less marsh, which would reduce the capacity of coastal regions to provide important ecological and economic services. © 2012 Macmillan Publishers Limited. All rights reserved.
Janz D.R.,Louisiana State University
Critical Care Medicine | Year: 2016
OBJECTIVE:: To evaluate the effect of video laryngoscopy on the rate of endotracheal intubation on first laryngoscopy attempt among critically ill adults. DESIGN:: A randomized, parallel-group, pragmatic trial of video compared with direct laryngoscopy for 150 adults undergoing endotracheal intubation by Pulmonary and Critical Care Medicine fellows. SETTING:: Medical ICU in a tertiary, academic medical center. PATIENTS:: Critically ill patients 18 years old or older. INTERVENTIONS:: Patients were randomized 1:1 to video or direct laryngoscopy for the first attempt at endotracheal intubation. MEASUREMENTS AND MAIN RESULTS:: Patients assigned to video (n = 74) and direct (n = 76) laryngoscopy were similar at baseline. Despite better glottic visualization with video laryngoscopy, there was no difference in the primary outcome of intubation on the first laryngoscopy attempt (video 68.9% vs direct 65.8%; p = 0.68) in unadjusted analyses or after adjustment for the operator’s previous experience with the assigned device (odds ratio for video laryngoscopy on intubation on first attempt 2.02; 95% CI, 0.82–5.02, p = 0.12). Secondary outcomes of time to intubation, lowest arterial oxygen saturation, complications, and in-hospital mortality were not different between video and direct laryngoscopy. CONCLUSIONS:: In critically ill adults undergoing endotracheal intubation, video laryngoscopy improves glottic visualization but does not appear to increase procedural success or decrease complications. Copyright © by 2016 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.
Kaiser M.J.,Louisiana State University
Applied Energy | Year: 2010
Experts may disagree on when world oil production will peak, but there is general agreement that marginal fields will contribute a greater percentage of world supply in the future. As fields mature and operations transition into the later stages of their production cycle, decreasing revenue streams, higher operating costs, and fewer upside opportunities lead to declining profitability. Eventually, all properties are abandoned when cost exceeds the revenue of production. In this two-part paper on marginal production in the Gulf of Mexico, the number of marginal structures in the gulf and their expected contribution to future production is forecast using established economic models. In Part 1, a historical perspective on producing assets is provided and the inventory of committed assets is modeled and categorized. We operationalize the definition of marginal production based on a structure's economic limit. The model framework to identify marginal assets in the Gulf of Mexico is discussed and a step-by-step description of the methodology is provided. In Part 2, the results of the model are described. © 2010 Elsevier Ltd. All rights reserved.
Tsai Y.-H.E.,Duke University |
Tsai Y.-H.E.,Louisiana State University
Molecular Ecology Resources | Year: 2011
The first step of many population genetic studies is the simple visualization of allele frequencies on a landscape. This basic data exploration can be challenging without proprietary software, and the manual plotting of data is cumbersome and unfeasible at large sample sizes. I present an open source, web-based program that plots any kind of frequency or count data as pie charts in Google Maps (Google Inc., Mountain View, CA). Pie polygons are then exportable to Google Earth (Google Inc.), a free Geographic Information Systems platform. Import of genetic data into Google Earth allows phylogeographers access to a wealth of spatial information layers integral to forming hypotheses and understanding patterns in the data. © 2010 Blackwell Publishing Ltd.
Amariucai G.T.,Iowa State University |
Wei S.,Louisiana State University
IEEE Transactions on Information Theory | Year: 2012
In this paper, we study the problem of half-duplex active eavesdropping in fast-fading channels. The active eavesdropper is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping the transmission between the legitimate parties (Ex mode), and jamming it (Jx mode)-the active eavesdropper cannot function in full duplex mode. We consider a conservative scenario, when the active eavesdropper can choose its strategy based on the legitimate transmitter-receiver pair's strategy, and thus, the transmitter and legitimate receiver have to plan for the worst. We show that conventional physical-layer secrecy approaches perform poorly (if at all), and we introduce a novel encoding scheme, based on very limited and unsecured feedback-the Block-Markov Wyner encoding scheme-which outperforms any schemes currently available. © 2012 IEEE.
Bensman S.J.,Louisiana State University
Scientometrics | Year: 2012
This paper is a response to that of Vanclay, who proposes, that since the impact factor (IF) is so seriously flawed, Thomson Reuters should either correct the measure or-preferably-no longer publish it and restrict itself to journal certification. It is argued here that Vanclay's analysis is itself seriously flawed, because he appears totally ignorant of the thought structure of Eugene Garfield, IF's creator. As a result, Vanclay appears unaware of the importance of total cites and the close connection of IF with review journals, where the paradigms of science are defined. This paper's author agrees that IF is a defective measure, analyzing its defects from the perspective of the frequency theory of probability, on which modern inferential statistics is based. However, he asserts that abandoning it would be counterproductive because of its demonstrated ability-even with its defects-to identify small important journals like review journals, giving it an important role in science evaluation and library collection management. © 2011 Akadémiai Kiadó, Budapest, Hungary.
Landolt A.U.,Louisiana State University
Astronomical Journal | Year: 2013
U BV RI photoelectric observations have been made of 335 stars around the sky, and centered approximately at +50 deg declination. The majority of the stars fall in the magnitude range 9 < V < 16, and in the color range -0.3 < (B-V) < +1.8. Those 243 stars best suited as new broadband photometric standard stars average 12.5 measures each from data taken on 98 different nights over a period of 17 years at the Kitt Peak National and Lowell Observatories. © 2013. The American Astronomical Society. All rights reserved.
Kaiser M.J.,Louisiana State University
Energy | Year: 2010
When the operating cost of a well is equal to its income from production, the well is no longer considered an asset and is said to have reached its economic limit. The purpose of this paper is to quantify the economic limit of hydrocarbon field production in Louisiana. We classify 690 fields that terminated production between 1977 and 2007 by product type, location, and year of termination and compute production and adjusted gross revenue near the end of their life cycle. During the last year of production, average oil field revenues varied from $35,000 in North Louisiana to $101,000 in South Louisiana to $227,000 in state waters; gas field revenue thresholds ranged from $57,000 (North Louisiana) to $402,000 (South Louisiana) to $936,000 (offshore). Economic limit statistics are summarized and correlations with price and field size are reviewed. The limitations of the analysis and constraints on interpretation are discussed. © 2010 Elsevier Ltd.
Kaiser M.J.,Louisiana State University
Energy | Year: 2010
Throughout the world wherever oil and gas is discovered, a support industry will develop and evolve with the needs of industry and government regulation. In the Gulf of Mexico, a large variety of marine vessels transport goods and provide services to exploration, development and production activity, and play an important role in the economic and ecological impacts across communities. The spatial and temporal dynamics of the logistics network is complex and dynamic and closely related to the magnitude, duration, type, and sequence of offshore workflows and activities. The purpose of this paper is to develop a methodological framework to quantify the number of offshore supply vessel and crew boat departures by activity across the Gulf's coastal regions in support of the oil and gas industry. The logistics network is modeled as a linear time-invariant deterministic system and implemented using an input-output model. We provide a methodological framework to quantify the magnitude and distribution of service vessel trips to forecast port activity. This is the first integrated modeling study on service vessel trips in the Gulf of Mexico and special attention is paid to the analytic framework, model assumptions, and limitations of the analysis. Generic examples illustrate the model implementation. © 2010 Elsevier Ltd.
Newcomer M.E.,Louisiana State University |
Brash A.R.,Vanderbilt University
Protein Science | Year: 2015
Many intriguing facets of lipoxygenase (LOX) catalysis are open to a detailed structural analysis. Polyunsaturated fatty acids with two to six double bonds are oxygenated precisely on a particular carbon, typically forming a single chiral fatty acid hydroperoxide product. Molecular oxygen is not bound or liganded during catalysis, yet it is directed precisely to one position and one stereo configuration on the reacting fatty acid. The transformations proceed upon exposure of substrate to enzyme in the presence of O2 (RH + O2 → ROOH), so it has proved challenging to capture the precise mode of substrate binding in the LOX active site. Beginning with crystal structures with bound inhibitors or surrogate substrates, and most recently arachidonic acid bound under anaerobic conditions, a picture is consolidating of catalysis in a U-shaped fatty acid binding channel in which individual LOX enzymes use distinct amino acids to control the head-to-tail orientation of the fatty acid and register of the selected pentadiene opposite the non-heme iron, suitably positioned for the initial stereoselective hydrogen abstraction and subsequent reaction with O2. Drawing on the crystal structures available currently, this review features the roles of the N-terminal β-barrel (C2-like, or PLAT domain) in substrate acquisition and sensitivity to cellular calcium, and the α-helical catalytic domain in fatty acid binding and reactions with O2 that produce hydroperoxide products with regio and stereospecificity. LOX structures combine to explain how similar enzymes with conserved catalytic machinery differ in product, but not substrate, specificities. Interactive Figure 2; Interactive Figure 3; Interactive Figure 8. © 2014 The Protein Society.
Kosma M.,Louisiana State University
Research on Aging | Year: 2014
Falling is a major health-related risk among older adults due to injuries, disability, and even death. Although physical activity (PA) can prevent falls, most older adults are inactive due to limited motivation. The purpose was to examine a motivational framework whereby the stages of change (SOC) and PA mediated the relations between the theory of planned behavior constructs and falls risks among 172 diverse older adults (M age = 72.36). The participants were assessed using standardized scales. Based on the path analysis, the hypothesized framework fit the sample data. The SOC and perceived control had significant path coefficients for PA (.48 and.43, respectively), and PA was linked to falls risks (-.54). Subjective norm was mostly associated with the SOC followed by attitude and perceived control. The variance explained in the SOC, PA, and falls risks were 28%, 59%, and 29%, respectively. Health promoters can use the proposed framework to promote PA and decrease falls risk. © The Author(s) 2012.
Caprio J.,Louisiana State University |
Shimohara M.,Kagoshima University |
Marui T.,409 Koyocho |
Harada S.,Kagoshima University |
Kiyohara S.,Kagoshima University
Science | Year: 2014
We report that the Japanese sea catfish Plotosus japonicus senses local pH-associated increases in H+/CO2 equating to a decrease of ≤0.1 pH unit in ambient seawater. We demonstrated that these sensors, located on the external body of the fish, detect undamaged cryptic respiring prey, such as polychaete worms. Sensitivity is maximal at the natural pH of seawater (pH 8.1 to 8.2) and decreases dramatically in seawater with a pH <8.0.
Frieben J.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Louisiana State University
Monthly Notices of the Royal Astronomical Society | Year: 2012
We have computed models of rotating relativistic stars with a toroidal magnetic field and investigated the combined effects of magnetic field and rotation on the apparent shape (i.e. the surface deformation), which could be relevant for the electromagnetic emission, and on the internal matter distribution (i.e. the quadrupole distortion), which could be relevant for the emission of gravitational waves. Using a sample of eight different cold nuclear physics equations of state, we have computed models of maximum field strength, as well as the distortion coefficients for the surface and the quadrupolar deformations. Surprisingly, we find that non-rotating models admit arbitrary levels of magnetization, accompanied by a growth of size and quadrupole distortion to which we could not find a limit. Rotating models, on the other hand, are subject to a mass-shedding limit at frequencies well below the corresponding ones for unmagnetized stars. Overall, the space of solutions can be split into three distinct classes for which the surface deformation and the quadrupole distortion are either prolate and prolate, oblate and prolate, or oblate and oblate, respectively. We also derive a simple formula expressing the relativistic distortion coefficients, which allows one to compute the surface deformation and the quadrupole distortion up to significant levels of rotation and magnetization, essentially covering all known magnetars. Such a formula replaces Newtonian equivalent expressions that overestimate the magnetic quadrupole distortion by about a factor of 6 and are inadequate for strongly relativistic objects like neutron stars. © 2012 The Authors.
Ciolfi R.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Max Planck Institute For Gravitationsphysik |
Rezzolla L.,Louisiana State University
Astrophysical Journal | Year: 2012
We investigate the instability of purely poloidal magnetic fields in nonrotating neutron stars (NSs) by means of three-dimensional general-relativistic magnetohydrodynamics simulations, extending the work presented by Ciolfi et al. in 2011. Our aim is to draw a clear picture of the dynamics associated with the instability and to study the final configuration reached by the system, thus obtaining indications on possible equilibria in a magnetized NS. Furthermore, since the internal rearrangement of magnetic fields is a highly dynamical process and has been suggested to be behind magnetar giant flares, our simulations can provide a realistic estimate of the electromagnetic and gravitational-wave (GW) emission that should accompany the flare event. Our main findings are the following: (1) the initial development of the instability meets all the expectations of perturbative studies in terms of the location of the seed of the instability, the timescale for its growth, and the generation of a toroidal component; (2) in the subsequent nonlinear reorganization of the system, ∼90% of magnetic energy is lost in few Alfvén timescales mainly through electromagnetic emission, and further decreases on a much longer timescale; (3) all stellar models tend to achieve a significant amount of magnetic helicity and the equipartition of energy between poloidal and toroidal magnetic fields and evolve to a new configuration that does not show a subsequent instability on dynamical or Alfvén timescales; (4) the electromagnetic emission matches the duration of the initial burst in luminosity observed in giant flares, giving support to the internal rearrangement scenario; and (5) only a small fraction of the energy released during the process is converted into f-mode oscillations and in the consequent GW emission, thus resulting in very low chances of detecting this signal with present and near-future ground-based detectors. © 2012. The American Astronomical Society. All rights reserved.
Cai Y.-F.,McGill University |
Wilson-Ewing E.,Louisiana State University
Journal of Cosmology and Astroparticle Physics | Year: 2014
A non-singular bouncing cosmology is generically obtained in loop quantum cosmology due to non-perturbative quantum gravity effects. A similar picture can be achieved in standard general relativity in the presence of a scalar field with a non-standard kinetic term such that at high energy densities the field evolves into a ghost condensate and causes a non-singular bounce. During the bouncing phase, the perturbations can be stabilized by introducing a Horndeski operator. Taking the matter content to be a dust field and an ekpyrotic scalar field, we compare the dynamics in loop quantum cosmology and in a non-singular bouncing effective field model with a non-standard kinetic term at both the background and perturbative levels. We find that these two settings share many important properties, including the result that they both generate scale-invariant scalar perturbations. This shows that some quantum gravity effects of the very early universe may be mimicked by effective field models. © 2014 IOP Publishing Ltd and Sissa Medialab srl.
Boudreaux B.,Louisiana State University
Veterinary Clinics of North America - Small Animal Practice | Year: 2014
This article discusses the clinically relevant uses of antimicrobials in small animal cancer patients. The article focuses on general considerations of antimicrobial use, antimicrobials in the neutropenic patient, prophylactic antimicrobial usage, antimicrobials in radiation therapy, and antimicrobials in metronomic chemotherapy protocols. © 2014 Elsevier Inc.
Czarnecki L.S.,Louisiana State University
IET Power Electronics | Year: 2010
Results of a study on how the supply voltage asymmetry affects the reference signal for switching compensator control, in a situation when this signal is generated using the instantaneous reactive power (IRP) p-q theory are presented. According to the IRP p-q approach, the compensator should compensate IRP and the alternating component of the instantaneous active power of the load. However, that in the presence of the supply voltage asymmetry, even an ideal, unity power factor load has an instantaneous active power with a non-zero alternating component is demonstrated. According to IRP p-q theory-based approach, it should be compensated and this requires that a distorted current be injected into the distribution system. It means that in the presence of the supply voltage asymmetry, the algorithms based on the IRP p-q theory generate a non-sinusoidal reference signal for the compensator control, even when voltages and currents in the system are sinusoidal. © 2009 The Institution of Engineering and Technology.
Inderfurth K.,Otto Von Guericke University of Magdeburg |
Kelle P.,Louisiana State University
International Journal of Production Economics | Year: 2011
Capacity reservation contracts and spot markets are two alternative purchasing practices. We focus on the cost-effective management of the combined use of these two procurement sources. Due to the variability of the spot market prices and demand uncertainty, the flexibility of combined sourcing can be advantageous. Spot market purchasing is a benefit in case of low spot market prices or insufficient reserved capacity, and the capacity reservation contract is an operational risk hedging for high spot market price incidents. The structure of the optimal combined purchasing policy is complex. In this paper we consider a simple and easy-to-implement capacity reservation - base stock policy and compare it to single sourcing options. We examine the joint effect of demand and spot market price uncertainty. Our analysis shows that in the case of large spot market price variability the combined sourcing is superior over spot market sourcing even in the case of low average spot price. The combined sourcing is also superior over long-term sourcing even in the case of high average spot price if there is large spot market price variability. Analytical and simulation results are presented to show the effect of the different price, cost, and uncertainty parameters on the optimal capacity reservation - base stock policy and on the expected percentage gain over single sourcing. © 2010 Elsevier B.V. All rights reserved.
Ho Y.-C.,Johns Hopkins University |
Shan L.,Johns Hopkins University |
Shan L.,Yale University |
Hosmane N.N.,Johns Hopkins University |
And 8 more authors.
Cell | Year: 2013
Antiretroviral therapy fails to cure HIV-1 infection because latent proviruses persist in resting CD4+ T cells. T cell activation reverses latency, but <1% of proviruses are induced to release infectious virus after maximum in vitro activation. The noninduced proviruses are generally considered defective but have not been characterized. Analysis of 213 noninduced proviral clones from treated patients showed 88.3% with identifiable defects but 11.7% with intact genomes and normal long terminal repeat (LTR) function. Using direct sequencing and genome synthesis, we reconstructed full-length intact noninduced proviral clones and demonstrated growth kinetics comparable to reconstructed induced proviruses from the same patients. Noninduced proviruses have unmethylated promoters and are integrated into active transcription units. Thus, it cannot be excluded that they may become activated in vivo. The identification of replication-competent noninduced proviruses indicates that the size of the latent reservoir - and, hence, the barrier to cure - may be up to 60-fold greater than previously estimated. PaperFlick © 2013 Elsevier Inc.
Hassan M.M.,Louisiana State University
Journal of Infrastructure Systems | Year: 2010
The use of titanium dioxide (TiO 2) ultrafine particulates as coating for concrete pavement have received considerable attention in recent years as these coatings can trap and absorb organic and inorganic air pollutants by a photocatalytic process. Despite these promising benefits, the promotion of TiO 2 coatings based on a single factor such as air quality does not provide a complete evaluation of this technology and may omit critical environmental factors that should be considered in the selection of sustainable materials. The objective of this study was to determine the life-cycle assessment of TiO 2 coating technology based on a hybrid life-cycle methodology. To achieve this objective, a life-cycle inventory that quantifies the energy, abiotic raw material inputs, and emission of TiO 2 coatings from cradle to grave were developed. Based on this inventory, life-cycle impact assessment of TiO 2 coatings for concrete pavement was conducted using the BEES impact assessment model. The use of titanium dioxide coating reduces the concentration of harmful pollutants by a photocatalytic process, and therefore, reduces the environmental impacts in four main categories: acidification, eutrophication, criteria air pollutants, and smog formation. However, during the production phases and due to the consumption of fossil energy, titanium dioxide will cause an increase in global warming, fossil fuel depletion, water intake, ozone depletion, and impacts on human health. Based on the overall environmental performance of this product, life-cycle assessment shows that titanium dioxide coating has an overall beneficial effect on the environment. © 2010 ASCE.
Soysal O.M.,Louisiana State University
Expert Systems with Applications | Year: 2015
In this paper, we address the problem of mining structured data to find potentially useful patterns by association rule mining. Different than the traditional find-all-then-prune approach, a heuristic method is proposed to extract mostly associated patterns (MASPs). This approach utilizes a maximally-association constraint to generate patterns without searching the entire lattice of item combinations. This approach does not require a pruning process. The proposed approach requires less computational resources in terms of time and memory requirements while generating a long sequence of patterns that have the highest co-occurrence. Furthermore, k-item patterns can be obtained thanks to the sub-lattice property of the MASPs. In addition, the algorithm produces a tree of the detected patterns; this tree can assist decision makers for visual analysis of data. The outcome of the algorithm implemented is illustrated using traffic accident data. The proposed approach has a potential to be utilized in big data analytics. © 2014 Elsevier Ltd.
Sarjeant K.,Louisiana State University
Cold Spring Harbor perspectives in biology | Year: 2012
Adipose tissue is an important site for lipid storage, energy homeostasis, and whole-body insulin sensitivity. It is important to understand the mechanisms involved in adipose tissue development and function, which can be regulated by the endocrine actions of various peptide and steroid hormones. Recent studies have revealed that white and brown adipocytes can be derived from distinct precursor cells. This review will focus on transcriptional control of adipogenesis and its regulation by several endocrine hormones. The general functions and cellular origins of adipose tissue and how the modulation of adipocyte development pertains to metabolic disease states will also be considered.
Gu G.,Louisiana State University
IEEE Transactions on Signal Processing | Year: 2011
The problem of target motion analysis (TMA) has been extensively investigated using bearing-only (BO), Doppler-bearing (DB), and other measurement data. For radio frequency (RF) emitters, signal powers follow the well-known path loss law that can be utilized to aid localization and target tracking in BO-TMA, leading to the novel power-bearing (PB) approach as proposed in this paper. Our main contribution lies in the proof of the asymptotic optimality of the total least-squares (TLS) algorithm for PB-TMA under some mild condition. The Cramér-Rao lower bound (CRLB) is employed to demonstrate the performance improvements of the PB-TMA over the BO-TMA. Our work shows the promise of the PB-TMA approach for RF signals. © 2010 IEEE.
Bray G.A.,Louisiana State University |
Popkin B.M.,University of North Carolina at Chapel Hill
Pediatric Obesity | Year: 2013
Background: Sugar-sweetened drinks and the fructose they provide are associated with several health problems. Methods: Data from the Nielsen Homescan and product content were analysed for sweetener type using the Gladson Nutrition Database. Meta-analyses and randomized clinical trials were used to evaluate outcomes of beverage and fructose intake. Results: Over 70% of all foods contain some amounts of added sugar, and consumption of soft drinks has increased fivefold since 1950. Meta-analyses suggest that consumption of sugar-sweetened beverages is related to the risk of diabetes, the metabolic syndrome and cardiovascular disease in adults and in children. Drinking two sugar-sweetened beverages per day for 6 months induced features of the metabolic syndrome and fatty liver. Randomized, controlled trials in children and adults lasting from 6 months to 2 years have shown that lowering the intake of soft drinks reduced weight gain. Genetic factors influence the weight gain when drinking soft drinks. Conclusion: Consumption of calorie-sweetened beverages and the fructose they contain has continued to increase and may play a role in the epidemic of obesity, the metabolic syndrome and fatty liver disease. Reducing intake of soft drinks is associated with less weight gain and metabolic improvement as well. © 2013 The Authors.
Llerena K.,University of Maryland University College |
Strauss G.P.,University of Maryland Baltimore County |
Cohen A.S.,Louisiana State University
Schizophrenia Research | Year: 2012
Abnormalities in emotional experience have long been viewed as core features of schizophrenia. Numerous studies indicate that people with schizophrenia report less pleasure than controls when reporting non-current feelings using trait, hypothetical, prospective, and retrospective emotional self-report formats; however, current research has demonstrated that schizophrenia patients and controls do not differ in their subjective reactions to emotional stimuli in most laboratory studies. Although substantial attention has been paid to studies examining self-reported valence in schizophrenia, subjective reports of arousal in response to affective stimuli have been neglected. Understanding the role of arousal in schizophrenia is imperative given that valence and arousal are differentially associated with physiological and behavioral responses. To understand the role of self-reported arousal, a meta-analysis of 26 published studies employing laboratory emotion induction paradigms in patients with schizophrenia and healthy controls was conducted. Medline, PsycINFO, Web of Science, and PubMed electronic databases and reference lists from identified articles were used as data sources. Using a random effects model, analyses demonstrated that controls and people with schizophrenia reported similar levels of subjective arousal in response to pleasant and unpleasant stimuli; however, people with schizophrenia reported experiencing greater arousal than controls in response to neutral stimuli. Furthermore, moderator analyses suggested that gender and methodological factors, such as rating scale and stimulus type, may affect these patterns of results and play a key role in determining whether patients and controls differ in self-reported arousal. © 2012 Elsevier B.V.
D'Sa E.J.,Louisiana State University
GIScience and Remote Sensing | Year: 2014
Variability in surface chlorophyll (Chl) concentrations derived from the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) were examined in conjunction with river discharge, QuikSCAT satellite-derived winds, and sea surface height (SSH) anomaly data along the Louisiana coast, USA. Surface Chl distributions exhibited rapid response to strong northerly winds following a frontal passage. A comparison of time series (1998-2010) river discharge and monthly Chl data indicated Chl variability to be well correlated to seasonal river discharge only for locations near the two river deltas, while offshore, enhancements in Chl during fall-winter was likely due to cross-shelf transport or mixing associated with strong northerly wind stress. Variance in Chl examined using wavelet analysis applied to nearly 10 years (1998-2007) of SeaWiFS data indicated patterns of significant Chl variability due to combined enhanced wind and river discharge, offshore flows associated with Ekman transport and coastal wind convergence, and the effect of Hurricane Rita in 2005. Instances of significant Chl variance were also observed to occur during years of large hypoxic zone size suggesting potential linkages to hypoxia. SSH anomaly imagery indicated the presence of warm-core eddies that were responsible for the offshore dispersal of elevated Chl observed in the monthly SeaWiFS imagery. Overall, the use of multi-satellite data better described the forcing and patterns of Chl distributions along the river-dominated Louisiana coast and shelf. © 2014 © 2014 Taylor & Francis.
McMahan C.D.,Louisiana State University
PloS one | Year: 2013
The contrasting distribution of species diversity across the major lineages of cichlids makes them an ideal group for investigating macroevolutionary processes. In this study, we investigate whether different rates of diversification may explain the disparity in species richness across cichlid lineages globally. We present the most taxonomically robust time-calibrated hypothesis of cichlid evolutionary relationships to date. We then utilize this temporal framework to investigate whether both species-rich and depauperate lineages are associated with rapid shifts in diversification rates and if exceptional species richness can be explained by clade age alone. A single significant rapid rate shift increase is detected within the evolutionary history of the African subfamily Pseudocrenilabrinae, which includes the haplochromins of the East African Great Lakes. Several lineages from the subfamilies Pseudocrenilabrinae (Australotilapiini, Oreochromini) and Cichlinae (Heroini) exhibit exceptional species richness given their clade age, a net rate of diversification, and relative rates of extinction, indicating that clade age alone is not a sufficient explanation for their increased diversity. Our results indicate that the Neotropical Cichlinae includes lineages that have not experienced a significant rapid burst in diversification when compared to certain African lineages (rift lake). Neotropical cichlids have remained comparatively understudied with regard to macroevolutionary patterns relative to African lineages, and our results indicate that of Neotropical lineages, the tribe Heroini may have an elevated rate of diversification in contrast to other Neotropical cichlids. These findings provide insight into our understanding of the diversification patterns across taxonomically disparate lineages in this diverse clade of freshwater fishes and one of the most species-rich families of vertebrates.
Spivey J.J.,Louisiana State University |
Hutchings G.,University of Cardiff
Chemical Society Reviews | Year: 2014
Recent developments in natural gas production technology have led to lower prices for methane and renewed interest in converting methane to higher value products. Processes such as those based on syngas from methane reforming are being investigated. Another option is methane aromatization, which produces benzene and hydrogen: 6CH4(g) → C6H6(g) + 9H2(g) ΔGor = +433 kJ mol-1 ΔHor = +531 kJ mol-1. Thermodynamic calculations for this reaction show that benzene formation is insignificant below ∼600 °C, and that the formation of solid carbon [C(s)] is thermodynamically favored at temperatures above ∼300 °C. Benzene formation is insignificant at all temperatures up to 1000 °C when C(s) is included in the calculation of equilibrium composition. Interestingly, the thermodynamic limitation on benzene formation can be minimized by the addition of alkanes/alkenes to the methane feed. By far the most widely studied catalysts for this reaction are Mo/HZSM-5 and Mo/MCM-22. Benzene selectivities are generally between 60 and 80% at methane conversions of ∼10%, corresponding to net benzene yields of less than 10%. Major byproducts include lower molecular weight hydrocarbons and higher molecular weight substituted aromatics. However, carbon formation is inevitable, but the experimental findings show this can be kinetically limited by the use of H 2 or oxidants in the feed, including CO2 or steam. A number of reactor configurations involving regeneration of the carbon-containing catalyst have been developed with the goal of minimizing the cost of regeneration of the catalyst once deactivated by carbon deposition. In this tutorial review we discuss the thermodynamics of this process, the catalysts used and the potential reactor configurations that can be applied. © The Royal Society of Chemistry.
Gambini R.,Institute Fisica |
Pullin J.,Louisiana State University
Classical and Quantum Gravity | Year: 2015
We study the quantum motion of null shells in the quantum space-time of a black hole in loop quantum gravity. We treat the shells as test fields and use an effective dynamics for the propagation equations. The shells propagate through the region where the singularity was present in the classical black hole space-time, but is absent in the quantum space-time, eventually emerging through a white hole to a new asymptotic region of the quantum space-time. The profiles of the shells get distorted due to the quantum fluctuations in the Planckian region that replaces the singularity. The evolution of the shells is unitary throughout the whole process. © 2015 IOP Publishing Ltd.
Karki B.B.,Louisiana State University
Physics of the Earth and Planetary Interiors | Year: 2015
First-principles methods based on density functional theory are used extensively in the investigation of the behavior and properties of mantle materials over broad ranges of pressure, temperature, and composition that are relevant. A review of computational results reported during the last couple of decades shows that essentially all properties including structure, phase transition, equation of state, thermodynamics, elasticity, alloying, conductivity, defects, interfaces, diffusivity, viscosity, and melting have been calculated from first principles. Using MgO, the second most abundant oxide of Earth's mantle, as a primary example and considering many other mantle materials in their crystalline and amorphous phases, we have found that most properties are strongly pressure dependent, sometimes varying non-monotonically and anomalously, with the effects of temperature being systematically suppressed with compression. The overall agreement with the available experimental data is excellent; it is remarkable that the early-calculated results such as shear wave velocities of two key phases, MgO and MgSiO3 perovskite, were subsequently reproduced by experimentation covering almost the entire mantle pressure regime. As covered in some detail, the defect formation and migration enthalpies of key mantle materials increase with pressure. The predicted trend is that partial MgO Schottky defects are energetically most favorable in Mg-silicates but their formation enthalpies are high. So, the diffusion in the mantle is likely to be in the extrinsic regime. Preliminary results on MgO and forsterite hint that the grain boundaries can accommodate point defects (including impurities) and enhance diffusion rates at all pressures. The structures are highly distorted in the close vicinity of the defects and at the interface with excess space. Recent simulations of MgO-SiO2 binary and other silicate melts have found that the melt self-diffusion and viscosity vary by several orders of magnitudes with pressure, temperature, and composition. The predicted high compressibility and complex dynamical behavior can be associated with structural changes (involving non-bridging oxygen, oxygen tri-clusters, Si-O pentahedra, etc.) occurring on compression. We envision future prospect for massively parallel/distributed computing of unprecedented magnitude and scope in the study of relevant materials for Earth, super-Earth, and other planets. A renewed computational theme perhaps should be the first-principles simulations of large systems (with long runs) that are necessary to explore realistic (natural) compositions, polycrystalline phases, multi-component melts, crystal/melt interfaces, trace element partitioning, etc. © 2014 Elsevier B.V.
Bao H.,Louisiana State University
Chemical Geology | Year: 2015
The stable isotope composition of O2, O3, and H2O in the geological past conveys rich information on history of the Earth system. However, few compounds are known to record O2 or O3 isotope signals directly and reliably. Sulfate (SO4 2-), a non-labile oxyanion capable of forming weakly soluble minerals, plays important roles in global sulfur, carbon, and oxygen cycles. Here I review publications on the triple oxygen isotope composition of sulfate which has been recently expanded, demonstrating that in addition to H2O isotope signals, sulfate can carry isotope signatures from O2 and O3. I argue that sulfate, to this point, is the only compound from which direct atmospheric O2 and O3 signals from the distant past can be retrieved. If the current understanding of the Earth's surface oxygenation history holds, we expect to observe little to no measurable deviation from a "normal" triple oxygen isotope composition for sulfate throughout the Archean, but both positive and negative deviations since the early Proterozoic. The full potential of this unique proxy can be achieved by further study on isotope kinetics of sulfur redox cycling and by filling gaps in geological records. © 2014 Elsevier B.V.
Bray G.A.,Louisiana State University
Journal of Diabetes Science and Technology | Year: 2010
The worldwide consumption of sucrose, and thus fructose, has risen logarithmically since 1800. Many concerns about the health hazards of calorie-sweetened beverages, including soft drinks and fruit drinks and the fructose they provide, have been voiced over the past 10 years. These concerns are related to higher energy intake, risk of obesity, risk of diabetes, risk of cardiovascular disease, risk of gout in men, and risk of metabolic syndrome. Fructose appears to be responsible for most of the metabolic risks, including high production of lipids, increased thermogenesis, and higher blood pressure associated with sugar or high fructose corn syrup. Some claim that sugar is natural, but natural does not assure safety. © Diabetes Technology Society.
Bray G.A.,Louisiana State University
Current Atherosclerosis Reports | Year: 2012
Fructose and glucose in soft drinks and fruit drinks account for just under 50 % of added sugars. Soft drinks intake has risen five-fold between 1950 and 2000, and this increase in intake of simple sugars has raised health concerns. The risks of cardiovascular disease, obesity and the metabolic syndrome have all been related to consumption of sugar-sweetened beverages in several, but not all meta-analyses. Fructose and sugar-sweetened beverages have also been related to the risk of gout in men, and to non-alcoholic fatty liver disease. Studies show that the calories in sugar-sweetened beverages do not produce an adequate reduction in the intake of other foods, leading to increased caloric intake. Plasma triglycerides are increased by sugar-sweetened beverages, and this increase appears to be due to fructose, rather than to glucose in sugar. Several 10-week to 26-week randomized trials of sugar-containing soft drinks show increases in triglycerides, body weight, and visceral adipose tissue; there were also increases in muscle fat and liver fat, which might lead to non-alcoholic-fatty liver disease. © Springer Science+Business Media, LLC 2012.
de Koning A.P.J.,Aurora University |
Gu W.,Aurora University |
Gu W.,Nanjing Southeast University |
Castoe T.A.,Aurora University |
And 2 more authors.
PLoS Genetics | Year: 2011
Transposable elements (TEs) are conventionally identified in eukaryotic genomes by alignment to consensus element sequences. Using this approach, about half of the human genome has been previously identified as TEs and low-complexity repeats. We recently developed a highly sensitive alternative de novo strategy, P-clouds, that instead searches for clusters of high-abundance oligonucleotides that are related in sequence space (oligo "clouds"). We show here that P-clouds predicts >840 Mbp of additional repetitive sequences in the human genome, thus suggesting that 66%-69% of the human genome is repetitive or repeat-derived. To investigate this remarkable difference, we conducted detailed analyses of the ability of both P-clouds and a commonly used conventional approach, RepeatMasker (RM), to detect different sized fragments of the highly abundant human Alu and MIR SINEs. RM can have surprisingly low sensitivity for even moderately long fragments, in contrast to P-clouds, which has good sensitivity down to small fragment sizes (~25 bp). Although short fragments have a high intrinsic probability of being false positives, we performed a probabilistic annotation that reflects this fact. We further developed "element-specific" P-clouds (ESPs) to identify novel Alu and MIR SINE elements, and using it we identified ~100 Mb of previously unannotated human elements. ESP estimates of new MIR sequences are in good agreement with RM-based predictions of the amount that RM missed. These results highlight the need for combined, probabilistic genome annotation approaches and suggest that the human genome consists of substantially more repetitive sequence than previously believed. © 2011 de Koning et al.
Pecchioni L.L.,Louisiana State University
Research on Aging | Year: 2012
Age serves as a basis for assigning status and regulating social interaction across all societies. Members of the cultural group socialize new members into the rules and roles that are associated with different chronological ages and age categories. These socially constructed age norms result in cultural life scripts. The events expected to occur reflect a positive bias, resulting in an idealized life script. Serious illnesses serve as an interruption to the idealized life script creating a tension between this ideal and the real of the lived experience. This study explores the nature of interrupted life narratives by analyzing comments related to aging made by people diagnosed with cancer and their spousal caregivers. Their comments reveal the ways in which aging expectations, chronological age, and health are intertwined. Because a serious illness is typically expected in very old age, when it occurs at a younger age both the individual with cancer and his or her caregiver struggle to make sense of this interruption to their anticipated life narratives. Poor health status leads to age relativism; that is, perceptions that the individual is not acting his or her chronological age. For married couples, adapting to illness as a couple operates in similar ways as it does for the individual. Their identity as a couple is challenged by the illness, and they struggle to redefine their relationship to each other and to their social world. © The Author(s) 2012.
Wang F.,Louisiana State University
Annals of the Association of American Geographers | Year: 2012
Despite spending more than any other nation on medical care per person, the United States ranks behind other industrialized nations in key health performance measures. A main cause is the deep disparities in access to care and health outcomes. Federal programs such as the designations of Medically Underserved Areas/Populations and Health Professional Shortage Areas are designed to boost the number of health professionals serving these areas and to help alleviate the access problem. Their effectiveness relies first and foremost on an accurate measure of accessibility so that resources can be allocated to truly needy areas. Various measures of accessibility need to be integrated into one framework for comparison and evaluation. Optimization methods can be used to improve the distribution and supply of health care providers to maximize service coverage, minimize travel needs of patients, limit the number of facilities, and maximize health or access equality. Inequality in health care access comes at a personal and societal price, evidenced in disparities in health outcomes, including late-stage cancer diagnosis. This review surveys recent literature on the three named issues with emphasis on methodological advancements and implications for public policy. © 2012 Copyright Taylor and Francis Group, LLC.
Claramunt S.,Louisiana State University
Evolution | Year: 2010
The study of continental adaptive radiations has lagged behind research on their island counterparts in part because the mere identification of adaptive radiations is more challenging at continental scales. Here, I demonstrate a new method based on simulations for discovering clades that show exceptionally high phenotypic diversity. Themethod does not require a phylogeny but accounts for differences in age and species richness among clades and incorporates effects of the phylogenetic structure of data. In addition, I developed a new multivariate measure of phenotypic diversity, which has the advantage over other measures of disparity in that it takes covariation into account. I applied these methods to a clade of endemic Neotropical suboscine passerines, within which the family Furnariidae has been considered an adaptive radiation. I found that the families Thamnophilidae, Furnariidae, and Dendrocolaptidae have experienced a higher rate of cladogenesis than have other clades. Although Thamnophilidae is exceptionally diverse in body size, only Furnariidae and Dendrocolaptidae are exceptionally diverse in shape. The combination of high rates of cladogenesis and high morphometric diversity in traits related to feeding and locomotion suggest that the clade Furnariidae-Dendrocolaptidae represent an authentic continental adaptive radiation. © 2010 The Author(s). Journal compilation. © 2010 The Society for the Study of Evolution.
Selim H.M.,Louisiana State University |
Zhang H.,CAS Yantai Institute of Coastal Zone Research
Journal of Environmental Quality | Year: 2013
Competition among various heavy metal species for available adsorption sites on soil matrix surfaces can enhance the mobility of contaminants in the soil environment. Accurate predictions of the fate and behavior of heavy metals in soils and geologic media requires the understanding of the underlying competitive-sorption and transport processes. In this review, we present equilibrium and kinetic models for competitive heavy metal sorption and transport in soils. Several examples are summarized to illustrate the impact of competing ions on the reactivities and mobility of heavy metals in the soil-water environment. We demonstrate that equilibrium Freundlich approaches can be extended to account for competitive sorption of cations and anions with the incorporation of competition coeffi cients associated with each reaction. Furthermore, retention models of the multiple-reaction type including the two-site nonlinear equilibrium-kinetic models and the concurrent- and consecutive-multireaction models were modifi ed to describe commonly observed time-dependent behaviors of heavy metals in soils. We also show that equilibrium Langmuir and kinetic second-order models can be extended to simulate the competitive sorption and transport in soils, although the use of such models is limited due to their simplifying assumptions. A major drawback of the empirically based Freundlich and Langmuir approaches is that their associated parameters are specifi c for each soil. Alternatively, geochemical models that are based on ion-exchange and surfacecomplexation concepts are capable of quantifying the competitive behavior of several chemical species under a wide range of environmental conditions. Such geochemical models, however, are incapable of describing the time-dependent sorption behavior of heavy metal ions in competitive systems. Further research is needed to develop a general-purpose model based on physical and chemical mechanisms governing competitive sorption in soils. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Zabaleta J.,Louisiana State University
Methods in Molecular Biology | Year: 2012
The prevalence of gastric cancer is associated with several factors including geographical location, diet, and genetic background of the host. However, it is evident that infection with Helicobacter pylori (H. pylori) is crucial for the development of the disease. Virulence of the bacteria is also important in modulating the risk of the disease. After infection, H. pylori gains access to the gastric mucosa and triggers the production of cytokines that promote recruitment of inflammatory cells, probably involved in tissue damage. Once the infection is established, a cascade of inflammatory steps associated with changes in the gastric epithelia that may lead to cancer is triggered. H. pylori-induced gastritis and H. pylori-associated gastric cancer have been the focus of extensive research aiming to discover the underlying mechanisms of gastric tissue damage. This research has led to the association of host genetic components with the risk of the disease. Among these is the presence of single nucleotide polymorphisms (SNPs) in several genes, including cytokine genes, which are able to differentially modulate the production of inflammatory cytokines and then modulate the risk of gastric cancer. Interestingly, the frequency of some of these SNPs is different among populations and may serve as a predictive factor for gastric cancer risk within that specific population. However, the role played by other genetic modifications should not be minimized. Methylation of gene promoters has been recognized as a major mechanism of gene expression regulation without changing the primary structure of the DNA. Most DNA methylation occurs in cytosine residues in CpG dinucleotide, but it can also be found in other DNA bases. DNA methyltransferases add methyl groups to the CpG dinucleotide, and when this methylation level is too high, the gene expression is turned off. In H. pylori infection as well as in gastric cancer, hypermethylation of promoters of genes involved in cell cycle control, metabolism of essential nutrients, and production of inflammatory mediators, among others, has been described. Interestingly, DNA changes like SNPs or mutations can create CpG sites in sequences where transcription factors normally sit, affecting transcription. In this chapter, we review the literature about the role of SNPs and methylation on H. pylori infection and gastric cancer, with big emphasis to the H. pylori role in the development of the disease due to the strong association between both. © 2012 Springer Science+Business Media, LLC.
Donze D.,Louisiana State University
Gene | Year: 2012
RNA polymerase III (Pol III) is one of three eukaryotic transcription complexes, and was identified as the complex responsible for production of transfer RNA and a limited number of other small RNAs. Pol III transcription at tRNA genes (tDNAs) requires the binding of two transcription factor complexes, TFIIIC and TFIIIB. Recent evidence points to a larger role for the Pol III transcription system in various other nuclear processes, including effects on nucleosome positioning, global genome and sub-nuclear organization, and direct effects on RNA polymerase II (Pol II) transcription. These effects are perhaps mediated by recruitment of a host of other chromatin proteins, including Pol II transcription factors and chromatin enzymes. Extra-TFIIIC sites (ETC sites) are chromosomal locations bound by TFIIIC without the rest of the Pol III complex, and bound TFIIIC alone is also able to mediate additional functions. These so called "extra-transcriptional effects" of the Pol III system are reviewed here, and a model is put forth suggesting that the TFIIIC transcription factor may act as a stably bound, global "bookmark" within chromatin to establish, maintain, or demarcate chromatin states as cells divide or change gene expression patterns. © 2011 Elsevier B.V.
Wan X.,Louisiana State University
Communications in Computational Physics | Year: 2015
In this work, we develop a minimum action method (MAM) with optimal linear time scaling, called tMAM for short. The main idea is to relax the integration time as a functional of the transition path through optimal linear time scaling such that a direct optimization of the integration time is not required. The Feidlin-Wentzell action functional is discretized by finite elements, based on which h-type adaptivity is introduced to tMAM. The adaptive tMAM does not require reparametrization for the transition path. It can be applied to deal with quasi-potential: 1) When the minimal action path is subject to an infinite integration time due to critical points, tMAM with a uniform mesh converges algebraically at a lower rate than the optimal one. However, the adaptive tMAM can recover the optimal convergence rate. 2) When the minimal action path is subject to a finite integration time, tMAM with a uniform mesh converges at the optimal rate since the problem is not singular, and the optimal integration time can be obtained directly from the minimal action path. Numerical experiments have been implemented for both SODE and SPDE examples. © 2015 Global-Science Press.
Fry B.,Louisiana State University
Fishery Bulletin | Year: 2011
Brown shrimp (Farfan-tepenaeus aztecus) are abundant along the Louisiana coast, a coastline that is heavily influenced by one of the world's largest rivers, the Mississippi River. Stable carbon, nitrogen, and sulfur (CNS) isotopes of shrimp and their proventriculus (stomach) contents were assayed to trace riverine support of estuarine-dependent brown shrimp. Extensive inshore and offshore collections were made in the Louisiana coastal zone during 1999-2006 to document shrimp movement patterns across the bay and shelf region. Results showed an unexpectedly strong role for nursery areas in the river delta in supporting the offshore fishery, with about 46% of immigrants to offshore regions arriving from riverine marshes. Strong river influences also were evident offshore, where cluster analysis of combined CNS isotope data showed three regional station groups related to river inputs. Two nearer-river mid-shelf station groups showed isotope values indicating river fertilization and productivity responses in the benthic shrimp food web, and a deeper offshore station group to the south and west showed much less river influence. At several mid-shelf stations where hypoxia is common, shrimp were anomalously 15N depleted versus their diets, and this δ15N difference or mismatch may be useful in monitoring shrimp movement responses to hypoxia.
Cheviron Z.A.,University of Nebraska - Lincoln |
Brumfield R.T.,Louisiana State University
Heredity | Year: 2012
Elucidating the molecular genetic basis of adaptive traits is a central goal of evolutionary genetics. The cold, hypoxic conditions of high-altitude habitats impose severe metabolic demands on endothermic vertebrates, and understanding how high-altitude endotherms cope with the combined effects of hypoxia and cold can provide important insights into the process of adaptive evolution. The physiological responses to high-altitude stress have been the subject of over a century of research, and recent advances in genomic technologies have opened up exciting opportunities to explore the molecular genetic basis of adaptive physiological traits. Here, we review recent literature on the use of genomic approaches to study adaptation to high-altitude hypoxia in terrestrial vertebrates, and explore opportunities provided by newly developed technologies to address unanswered questions in high-altitude adaptation at a genomic scale. © 2012 Macmillan Publishers Limited All rights reserved.
Warren Liao T.,Louisiana State University |
Chang P.C.,Yuan Ze University
International Journal of Production Economics | Year: 2010
This paper first proposes the use of metaheuristic, to combine with exponential smoothing methods, in forecasting future demands and in determining the optimal inventory policy values for each node in a supply chain network based on historical demand or order streams without the need of any prior knowledge about the demand distribution or distribution fitting. The effects of five demand forecasting methods, two inventory policies, and three lead times on the total inventory cost of a 3-echelon serial supply chain system are then investigated. The effect of sharing the demand information for planning the inventories is also compared with that of no sharing. For testing, 15 quarterly and 15 monthly time series were taken from the M3 Competition and are considered as the multi-item demand streams to be fulfilled in the supply chain. The results indicate that: (1) the damped Pegel forecasting method is the best in terms of prediction errors because it outperforms others in three of five measures, followed by the simple exponential smoothing that wins one of the remaining two and ties the damped Pegel in one; (2) the supply chain inventory cost increases with increasing lead time and echelon level of the supply chain when the (s, S) policy is used, but not the (r, Q) policy; (3) the (r, Q) inventory policy generally incurs lower supply chain inventory cost than the (s, S) policy; (4) sharing demand information reduces inventory cost and the reduction is higher for (s, S) than for (r, Q); (5) the best demand forecasting method for minimizing inventory cost varies with the inventory policy used and lead time; and (6) the correlation between forecasting errors and inventory costs is either negligible or minimal. © 2010 Elsevier B.V. All rights reserved.
Park H.,Louisiana State University |
Rodgers S.,University of Missouri |
Stemmle J.,University of Missouri
Journal of Health Communication | Year: 2013
This study explored health-related organizations' use of Twitter in delivering health literacy messages. A content analysis of 571 tweets from health-related organizations revealed that the organizations' tweets were often quoted or retweeted by other Twitter users. Nonprofit organizations and community groups had more tweets about health literacy than did other types of health-related organizations examined, including health business corporations, educational institutions, and government agencies. Tweets on health literacy topics focused predominantly on using simple language rather than complicated language. The results suggest that health organizations need a more strategic approach to managing positive organizational self-presentations in order to create an optimal level of exposure on social networking sites. © 2013 Copyright Taylor and Francis Group, LLC.
Hakes A.S.,Florida State University |
Cronin J.T.,Louisiana State University
Ecology | Year: 2012
Despite considerable research on plant defenses, we know very little about how temporal changes in the environment may influence resistance and tolerance levels, or the costs and benefits of these defense strategies for long-lived plant species. We hypothesized that, in successional habitats, predictable environmental changes should favor strong plasticity in defense phenotypes and that the costs, benefits, and levels of tolerance and resistance will change with environmental context. Using a widely distributed, old-field perennial, late goldenrod (Solidago altissima), we conducted a field experiment to test these predictions. We planted goldenrod genets exhibiting varying levels of resistance and tolerance into three earlysuccessional and three late-successional fields (approximately three and 15 years in age, respectively) and experimentally measured resistance and tolerance levels and their associated costs and selection coefficients. We found a significant effect of successional stage but no effect of genotype or stage-genotype interaction on defense levels. Genets planted in earlysuccessional fields appeared to be more resistant and less tolerant to herbivory than those same genets planted in late-successional fields. There were significant trade-offs between resistance and tolerance in early-successional fields but not in late-successional fields. Each late-successional field exhibited a significant cost or selection gradient for resistance, but there was no general pattern of resistance costs or selection gradients specific to a successional stage class. In contrast, there was evidence of stage-specific costs of tolerance; late-successional fields exhibited significant costs of tolerance whereas early-successional fields did not. There was no evidence of direct selection for or against tolerance in either stage. Our results suggest that defense phenotypes might change in qualitative ways during succession. High resistance in early stages may be attributed to associational effects of the early-successional community, reducing the probability of damage, and despite a cost of tolerance in late stages, tolerance may be beneficial in mitigating the effects of both herbivory and environmental stresses (i.e., low light availability) that limit fitness in these fields. This study provides experimental evidence that succession can strongly influence defense phenotypes and promote temporal variability in relative resistance and tolerance levels. © 2012 by the Ecological Society of America.
Fuller E.,University of Chicago |
Elderd B.D.,Louisiana State University |
Dwyer G.,University of Chicago
American Naturalist | Year: 2012
Classical epidemic theory focuses on directly transmitted pathogens, but many pathogens are instead transmitted when hosts encounter infectious particles. Theory has shown that for such diseases pathogen persistence time in the environment can strongly affect disease dynamics, but estimates of persistence time, and consequently tests of the theory, are extremely rare. We consider the consequences of persistence time for the dynamics of the gypsy moth baculovirus, a pathogen transmitted when larvae consume foliage contaminated with particles released from infectious cadavers. Using field-transmission experiments, we are able to estimate persistence time under natural conditions, and inserting our estimates into a standard epidemic model suggests that epidemics are often terminated by a combination of pupation and burnout rather than by burnout alone, as predicted by theory. Extending our models to allow for multiple generations, and including environmental transmission over the winter, suggests that the virus may survive over the long term even in the absence of complex persistence mechanisms, such as environmental reservoirs or covert infections. Our work suggests that estimates of persistence times can lead to a deeper understanding of environmentally transmitted pathogens and illustrates the usefulness of experiments that are closely tied to mathematical models. © 2012 by The University of Chicago.
Hanna E.B.,Louisiana State University
Journal of Invasive Cardiology | Year: 2012
Peripheral arterial disease (PAD) is common and is associated with a high cardiovascular mortality. While dual antiplatelet therapy (DAT) does not appear superior to antiplatelet monotherapy in preventing myocardial infarction, stroke, and death in the general PAD population, a subgroup of patients with peripheral percutaneous revascularization, particularly superficial femoral artery (SFA) stenting, may benefit from prolonged DAT (>3 months). One to 3 months of DAT appears reasonable after percutaneous revascularization of SFA in low-risk settings, and 1 month of DAT appears reasonable after iliac stenting or carotid stenting, but definite randomized trial data are lacking. Individualized therapy, taking into account the diffuseness of the disease, the quality of the inflow and the outflow, the presence of critical limb ischemia, the extent of stenting, the use of covered stents, and the stent fracture risk is reasonable.
Martin M.J.,Louisiana State University
Physics of Fluids | Year: 2012
Gas flow through arrays of nanotube or nanowire structures is modeled by combining the one-dimensional equations for conservation of mass, momentum, and energy with the linearized free-molecular drag and heat transfer for a cylinder. The results show that the pressure gradient, temperature, and local velocity of the gas are governed by coupled ordinary differential equations. Three cases are considered: an isothermal system, a constant wall temperature, and a constant wall heat flux. While the coupled momentum, heat transfer, and continuity equations are nonlinear, the relatively low velocities encountered in these systems cause the nonlinear portions of pressure drops and thermal phenomena to be relatively small. © 2012 American Institute of Physics.
Kearney M.S.,University of Maryland University College |
Riter J.C.A.,University of Maryland University College |
Turner R.E.,Louisiana State University
Geophysical Research Letters | Year: 2011
The restoration of Louisiana's coastal wetlands will be one of the largest, most costly and longest environmental remediation projects undertaken. We use Landsat data to show that freshwater diversions, a major restoration strategy, have not increased vegetation and marsh coverage in three freshwater diversions operating for ∼19 years. Two analytic methods indicate no significant changes in either relative vegetation or overall marsh area from 1984 to 2005 in zones closest to diversion inlets. After Hurricanes Katrina and Rita, these zones sustained dramatic and enduring losses in vegetation and overall marsh area, whereas the changes in similar marshes of the adjacent reference sites were relatively moderate and short-lived. We suggest that this vulnerability to storm damage reflects the introduction of nutrients in the freshwater diversions (that add insignificant amounts of additional sediments), which promotes poor rhizome and root growth in marshes where below-ground biomass historically played the dominant role in vertical accretion. Copyright 2011 by the American Geophysical Union.
Berthoud H.-R.,Louisiana State University
Current Opinion in Neurobiology | Year: 2011
Obesity is on the rise in all developed countries, and a large part of this epidemic has been attributed to excess caloric intake, induced by ever present food cues and the easy availability of energy dense foods in an environment of plenty. Clearly, there are strong homeostatic regulatory mechanisms keeping body weight of many individuals exposed to this environment remarkably stable over their adult life. Other individuals, however, seem to eat not only because of metabolic need, but also because of excessive hedonic drive to make them feel better and relieve stress. In the extreme, some individuals exhibit addiction-like behavior toward food, and parallels have been drawn to drug and alcohol addiction. However, there is an important distinction in that, unlike drugs and alcohol, food is a daily necessity. Considerable advances have been made recently in the identification of neural circuits that represent the interface between the metabolic and hedonic drives of eating. We will cover these new findings by focusing first on the capacity of metabolic signals to modulate processing of cognitive and reward functions in cortico-limbic systems (bottom-up) and then on pathways by which the cognitive and emotional brain may override homeostatic regulation (top-down). © 2011 Elsevier Ltd.
Agullo I.,Louisiana State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015
We argue that the anomalous power asymmetry observed in the cosmic microwave background (CMB) may have originated in a cosmic bounce preceding inflation. In loop quantum cosmology (LQC), the big bang singularity is generically replaced by a bounce due to quantum gravitational effects. We compute the spectrum of inflationary non-Gaussianity and show that strong correlation between observable scales and modes with longer (superhorizon) wavelength arise as a consequence of the evolution of perturbations across the LQC bounce. These correlations are strongly scale dependent and induce a dipole-dominated modulation on large angular scales in the CMB, in agreement with observations. © 2015 American Physical Society.
Wilson-Ewing E.,Louisiana State University
Journal of Cosmology and Astroparticle Physics | Year: 2013
We consider the ekpyrotic paradigm in the context of loop quantum cosmology. In loop quantum cosmology the classical big-bang singularity is resolved due to quantum gravity effects, and so the contracting ekpyrotic branch of the universe and its later expanding phase are connected by a smooth bounce. Thus, it is possible to explicitly determine the evolution of scalar perturbations, from the contracting ekpyrotic phase through the bounce and to the post-bounce expanding epoch. The possibilities of having either one or two scalar fields have been suggested for the ekpyrotic universe, and both cases will be considered here. In the case of a single scalar field, the constant mode of the curvature perturbations after the bounce is found to have a blue spectrum. On the other hand, for the two scalar field ekpyrotic model where scale-invariant entropy perturbations source additional terms in the curvature perturbations, the power spectrum in the post-bounce expanding cosmology is shown to be nearly scale-invariant and so agrees with observations. © 2013 IOP Publishing Ltd and Sissa Medialab srl.
Berthoud H.-R.,Louisiana State University |
Zheng H.,University of Pittsburgh
Physiology and Behavior | Year: 2012
Palatable foods lead to overeating, and it is almost a forgone conclusion that it is also an important contributor to the current obesity epidemic - there is even talk about food addiction. However, the cause-effect relationship between taste and obesity is far from clear. As discussed here, there is substantial evidence for altered taste sensitivity, taste-guided liking and wanting, and neural reward processing in the obese, but it is not clear whether such traits cause obesity or whether obesity secondarily alters these functions. Studies with calorie restriction-induced weight loss and bariatric surgery in humans and animal models suggest that at least some of the obesity-induced alterations are reversible and consequently represent secondary effects of the obese state. Thus, both genetic and non-genetic predisposition and acquired alterations in taste and reward functions appear to work in concert to aggravate palatability-induced hyperphagia. In addition, palatability is typically associated with high energy content, further challenging energy balance regulation. The mechanisms responsible for these alterations induced by the obese state, weight loss, and bariatric surgery, remain largely unexplored. Better understanding would be helpful in designing strategies to promote healthier eating and prevention of obesity and the accompanying chronic disease risks. © 2012 Elsevier Inc.
Radzihovsky L.,University of Colorado at Boulder |
Sheehy D.E.,Louisiana State University
Reports on Progress in Physics | Year: 2010
We present an overview of recent developments in species-imbalanced ('polarized') Feshbach-resonant Fermi gases. We summarize the current status of thermodynamics of these systems in terms of a phase diagram as a function of the Feshbach resonance detuning, polarization and temperature. We review instabilities of the s-wave superfluidity across the Bose-Einstein condensation-to-Bardeen-Cooper-Schrieffer crossover to phase separation, Fulde-Ferrell-Larkin-Ovchinnikov states, polarized molecular superfluidity and the normal state, driven by the species imbalance. We discuss different models and approximations of this system and compare their predictions with current experiments. © 2010 IOP Publishing Ltd.
Dokka R.K.,Louisiana State University
Journal of Geophysical Research: Solid Earth | Year: 2011
Geodetic leveling observations from Biloxi, MS, to New Orleans, LA, and water level gauge measurements in the New Orleans-Lake Pontchartrain area were analyzed to infer late 20th century vertical motions. These data were used to test the validity of previous subsidence rate measurements and the models that predict the location and causes of subsidence. Water gauges attached to bridge foundations and benchmarks affixed to deep rods that penetrate Holocene strata subsided as much as 0.8 m locally between 1955 and 1995. The observed deep-seated subsidence far exceeds model predictions and demonstrates that shallow processes such as compaction and consolidation of Holocene sediments are inadequate by themselves to explain late 20th century subsidence. Deep-seated subsidence occurring east and north of the normal faults marking the Gulf of Mexico basin margin can be explained by local groundwater withdrawal, and regional tectonic loading of the lithosphere by the modern Mississippi River delta (MRD). Sharp changes in subsidence coincide with strands of the basin margin normal faults. Displacements are consistent with activity and show motions consonant with fault creep. Deep subsidence of the region to the south, including New Orleans, can be explained by a combination of groundwater withdrawal from shallow upper Pleistocene aquifers, the aforementioned lithospheric loading, and perhaps, nongroundwater-related faulting. Subsidence due to groundwater extraction from aquifers ∼160 to 200 m deep dominated urbanized areas and is likely responsible for helping to lower local flood protection structures and bridges by as much as ∼0.8 m. Copyright © 2011 by the American Geophysical Union.
Katzmarzyk P.T.,Louisiana State University |
Lear S.A.,Simon Fraser University
Obesity Reviews | Year: 2012
Summary: The purpose of this review was to determine the effectiveness of physical activity in improving chronic disease risk factors in obese individuals. A systematic review was conducted to identify randomized physical activity intervention studies reporting changes in risk factors among obese individuals published prior to March 2010. Studies included in the review were randomized trials of at least 10 weeks in duration, with a sample mean body mass index ≥30kg/m 2 at baseline, and reporting a relevant risk factor (blood pressure, blood lipids, glucose/insulin or C-reactive protein). Forty-four studies met the inclusion criteria for this review. Overall, physical activity had no more than a modest effect on chronic disease risk factors in obese individuals. There was great heterogeneity in responses of risk factors across studies. In many studies it was difficult to determine the effect of physical activity, independent of changes in body mass consequent to the intervention. Obese individuals should be encouraged to undertake physical activity following general recommendations for weight loss and health. The degree to which physical activity is effective at lowering risk factor levels among high-risk obese individuals is not known. © 2011 The Authors. obesity reviews © 2011 International Association for the Study of Obesity.
Li S.,Louisiana State University
DNA Repair | Year: 2011
Base excision repair (BER) of dimethyl sulfate induced N-methylpurines (NMPs) was measured at nucleotide resolution in the mitochondrial DNA (mtDNA) of cultured human and yeast (Saccharomyces cerevisiae) cells. NMPs were repaired with heterogeneous rates in the human mtDNA. The nearest-neighbor nucleotides significantly affected the repair rates: NMPs between pyrimidines were repaired much faster than those between purines, and those between a purine and a pyrimidine were repaired at intermediate rates. Repair intermediates of NMPs can also be detected at certain sites of the human mtDNA, indicating an ineffectiveness of processing the intermediates at these sites by the human mitochondrial BER machinery. In contrast to the human mtDNA, the yeast mtDNA did not show detectable repair of NMPs at any sites. Furthermore, a high level of spontaneous strand breaks exists exclusively at purine sites in the yeast mtDNA. Spontaneous NMPs or oxidative lesions were unlikely to be the major causes for the spontaneous strand breaks. Rather, spontaneous depurination combined with inefficient processing of DNA nicks or single-nucleotide gaps by the yeast mitochondrial BER machinery may result in the spontaneous strand breaks. Our results unveil a striking difference in BER between human and the yeast mitochondria. © 2010 Elsevier B.V.
Gimble J.M.,Louisiana State University |
Bunnell B.A.,Tulane University Medical Center |
Chiu E.S.,Tulane University Medical Center |
Guilak F.,Duke University
Stem Cells | Year: 2011
Subcutaneous fat has emerged as an alternative tissue source for stromal/stem cells in regenerative medicine. Over the past decade, international research efforts have established a wealth of basic science and preclinical evidence regarding the differentiation potential and regenerative properties of both freshly processed, heterogeneous stromal vascular fraction cells and culture expanded, relatively homogeneous adipose-derived stromal/stem cells. the stage has been set for clinicians to translate adipose-derived cells from the bench to the bedside; however, this process will involve "development" steps that fall outside of traditional "hypothesis-driven, mechanism-based'' paradigm. This concise review examines the next stages of the development process for therapeutic applications of adipose-derived cells and highlights the current state of the art regarding clinical trials. It is recommended that the experiments addressing these issues be reported comprehensively in the peer-review literature. This transparency will accelerate the standardization and reproducibility of adipose-derived cell therapies with respect to their efficacy and safety. © AlphaMed Press.
Lee M.R.,Louisiana State University
Homicide Studies | Year: 2011
This article fleshes out a perspective on culture and lethal violence using examples from two contexts where they are believed to be strongly linked: among rural southern Whites and urban Blacks. Concepts from the cultural paradigm which focuses on understanding how people use cultural resources instead of discerning the content of cultures are employed. Through the lenses of this alternative cultural paradigm, violence in these two settings is partly attributable to an abundance of strategies of action condoning the use of violence. Strategies of action pertinent to defensive or honor-based violence emerge where the law is unavailable and may be amplified by moderate or high levels of poverty. However, when socioeconomic disadvantage is so severe that there is widespread institutional breakdown, strategies of action promoting more predatory and instrumental forms of violence may also evolve. This is because mainstream institutions are a primary source of socialization where cultural tool kits containing strategies of action are expanded and diversified. When they are weak, socialization through street peer groups or illegal markets may be more pronounced, facilitating the contextual transference of violent scripts for action to situations other than those involving honor or character contests. Actors immersed in violent communities are not subsequently mired down in circumstances beyond their control. Through participation in violent activities, they can actively create and reinforce their own violent social environment. © 2011 SAGE Publications.
Maccio E.M.,Louisiana State University
Journal of Gay and Lesbian Mental Health | Year: 2011
Researchers disagree on whether sexual reorientation (i.e., conversion or reparative) therapy (SRT) can change sexual orientation. Much of the recent research relies on participants from a particular religious denomination or from SRT organizations. This study recruited participants from SRT organizations and from gay-affirming ones. In this cross-sectional study, 37 former SRT participants reported no statistically significant differences in sexual orientation and sexual identity from before SRT participation to the time of their participation in this study. Practitioners with clients struggling with their sexual orientation or identity must be informed of SRT alternatives, including person-centered and gayaffirmative approaches. © Taylor & Francis Group, LLC.
Stevens R.D.,Louisiana State University
Biotropica | Year: 2013
Temperature seasonality has been proposed to be an important determinant of bat community structure in Atlantic Forest of South America and elsewhere. I characterized spatial and environmental patterns of species richness of phyllostomid bats in Atlantic Forest of South America and examined the degree to which temperature seasonality relative to other important environmental gradients was related to patterns of diversity across 60 heterogeneously sampled assemblages. I compared efficacy of different methods of accounting for inventory completeness (rarefaction, species estimation, minimum number of individuals and raw data) in characterizing gradients of bat diversity. I also compared levels of spatial autocorrelation generated by these methods and the degree to which such autocorrelation influenced results of regression analyses. Temperature seasonality was consistently the most important predictor of species richness across all methods of accounting for inventory completeness as well as between spatial and non-spatial regression methods. Spatial autocorrelation of both species richness and regression residuals was lowest for species richness estimators and highest for data rarefied to the highest sample sizes. Strong and characteristic environmental gradients typifying Atlantic Forest of South America translate into coincident gradients of richness of bat assemblages. Although data were characterized by heterogeneous sampling efforts, relationships of species richness with seasonality of temperature were strong and easily detectable. Methods of accounting for inventory completeness improve assessment with species richness estimators performing better than rarefaction methods. © 2013 The Association for Tropical Biology and Conservation.
Selim H.M.,Louisiana State University
Advances in Agronomy | Year: 2013
Appreciable amounts of various heavy metals (e.g. As, Cu, Ni, and Zn) are found in surface soils of lands as a result of accidental spills or industrial waste and sewage sludge applications. Such conditions often create environmental risks and potential contamination of soil, surface and groundwater resources. Competitive adsorption and desorption processes of heavy metals by the soil matrix have significant importance on their fate and mobility in soils. In this contribution, equilibrium and kinetic models governing competitive heavy-metal sorption and transport in soils were presented. Several examples were discussed to illustrate the impact of competing ions on the reactivities and mobility of heavy metals in the soil-water environment. The examples exhibited that competition among various heavy-metal species for available adsorption sites on soil matrix surfaces often results in the enhancement of the mobility of contaminants in the soil environment. Competitive sorption based on equilibrium Freundlich and Langmuir models were derived in order to account for competitive sorption of cations and anions in soils. Competitive models of the multiple reaction type including the two-site nonlinear equilibrium-kinetic models, the concurrent- and consecutive multireaction models were modified to describe kinetic adsorption-desorption of heavy metals behavior in soil. It was shown that equilibrium Langmuir and kinetic second-order models can be extended to simulate the competitive sorption and transport in soils. A drawback of Freundlich and Langmuir approaches is that their associated parameters are specific for each soil. Moreover, since predictions of the transport of heavy metals were sometime inadequate, improved competitive modeling approaches are needed. On the other hand, geochemical models, which are based on ion exchange and surface complexation concepts, are frequently utilized to quantify competitive behavior of several chemical species under a wide range of environmental conditions. However, further research is also needed since geochemical models are incapable of describing kinetic sorption-desorption of heavy metal ions in competitive systems. © 2013 Elsevier Inc.
Pi-Sunyer X.,Columbia University |
Astrup A.,Copenhagen University |
Fujioka K.,Scripps Research Institute |
Greenway F.,Louisiana State University |
And 6 more authors.
New England Journal of Medicine | Year: 2015
BACKGROUND Obesity is a chronic disease with serious health consequences, but weight loss is difficult to maintain through lifestyle intervention alone. Liraglutide, a glucagonlike peptide-1 analogue, has been shown to have potential benefit for weight management at a once-daily dose of 3.0 mg, injected subcutaneously. METHODS We conducted a 56-week, double-blind trial involving 3731 patients who did not have type 2 diabetes and who had a body-mass index (BMI; the weight in kilograms divided by the square of the height in meters) of at least 30 or a BMI of at least 27 if they had treated or untreated dyslipidemia or hypertension. We randomly assigned patients in a 2:1 ratio to receive once-daily subcutaneous injections of liraglutide at a dose of 3.0 mg (2487 patients) or placebo (1244 patients); both groups received counseling on lifestyle modification. The coprimary end points were the change in body weight and the proportions of patients losing at least 5% and more than 10% of their initial body weight. RESULTS At baseline, the mean (±SD) age of the patients was 45.1±12.0 years, the mean weight was 106.2±21.4 kg, and the mean BMI was 38.3±6.4; a total of 78.5% of the patients were women and 61.2% had prediabetes. At week 56, patients in the liraglutide group had lost a mean of 8.4±7.3 kg of body weight, and those in the placebo group had lost a mean of 2.8±6.5 kg (a difference of -5.6 kg; 95% confidence interval, -6.0 to -5.1; P<0.001, with last-observation-carried-forward imputation). A total of 63.2% of the patients in the liraglutide group as compared with 27.1% in the placebo group lost at least 5% of their body weight (P<0.001), and 33.1% and 10.6%, respectively, lost more than 10% of their body weight (P<0.001). The most frequently reported adverse events with liraglutide were mild or moderate nausea and diarrhea. Serious events occurred in 6.2% of the patients in the liraglutide group and in 5.0% of the patients in the placebo group. CONCLUSIONS In this study, 3.0 mg of liraglutide, as an adjunct to diet and exercise, was associated with reduced body weight and improved metabolic control. (Funded by Novo Nordisk; SCALE Obesity and Prediabetes NN8022-1839 ClinicalTrials.gov number, NCT01272219.). Copyright © 2015 Massachusetts Medical Society.
Sheehy D.E.,Louisiana State University
New Journal of Physics | Year: 2011
We study two species of attractively interacting fermion confined to a quasi-one-dimensional geometry, in the presence of a strong scattering potential that can couple, selectively, to one or both species. We show that the fermion density distribution in the presence of such a spin-selective scattering potential reflects the pairing spin gap of the fermions. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Mah C.,Smithsonian Institution |
Foltz D.,Louisiana State University
Zoological Journal of the Linnean Society | Year: 2011
The Valvatacea is one the most ecologically important, taxonomically diverse, and widespread groups of post-Palaeozoic (i.e. modern) Asteroidea. Classification within the group has been historically problematic. We present a comprehensively sampled, three-gene (12S, 16S, early-stage histone H3) molecular phylogenetic analysis of the Valvatacea. We include five of the six families within the Paxillosida, the monotypic Notomyotida, and 13 of the 16 families of the living Valvatida. The Solasteridae is removed from the Velatida (Spinulosacea) and joins the Ganeriidae and the Leilasteridae as members of the clade containing the Asterinidae. The Poraniidae is supported as the sister group to the large cluster of Valvatacea. Asteropseids and poraniids are phylogenetically distant, contrary to morphological evidence. Several goniasterid-like ophidiasterids, such as Fromia and Neoferdina are supported as derived goniasterids rather than as Ophidiasteridae. The Benthopectinidae (Notomyotida) are supported as members of the Paxillosida as are two members of the Pseudarchasterinae that have traditionally been considered members of the Goniasteridae. Our data suggest that Antarctic valvataceans may be derived from sister taxa in adjacent regions. © 2011 The Linnean Society of London.
Davis M.P.,Louisiana State University |
Fielitz C.,Emory & Henry College
Molecular Phylogenetics and Evolution | Year: 2010
The divergence times of lizardfishes (Euteleostei: Aulopiformes) are estimated utilizing a Bayesian approach in combination with knowledge of the fossil record of teleosts and a taxonomic review of fossil aulopiform taxa. These results are integrated with a study of character evolution regarding deep-sea evolutionary adaptations in the clade, including simultaneous hermaphroditism and tubular eyes. Divergence time estimations recover that the stem species of the lizardfishes arose during the Early Cretaceous/Late Jurassic in a marine environment with separate sexes, and laterally directed, round eyes. Tubular eyes have arisen independently at different times in three deep-sea pelagic predatory aulopiform lineages. Simultaneous hermaphroditism evolved a single time in the stem species of the suborder Alepisauroidei, the clade of deep-sea aulopiforms during the Early Cretaceous. This result indicates the oldest known evolutionary event of simultaneous hermaphroditism in vertebrates, with the Alepisauroidei being the largest vertebrate clade with this reproductive strategy. © 2010 Elsevier Inc.
Herrera G.A.,Louisiana State University
Archives of Pathology and Laboratory Medicine | Year: 2014
Context. - Lesions associated with monoclonal light and heavy chains display a variety of glomerular, tubular interstitial, and vascular manifestations. While some of the entities are well recognized, including light and heavy chain deposition diseases, AL (light chain) and AH (heavy chain) amyloidosis, and light chain ("myeloma") cast nephropathy, other lesions centered on proximal tubules are much less accurately identified, properly diagnosed, and adequately understood in terms of pathogenesis and molecular mechanisms involved. These proximal tubule-centered lesions are typically associated with monoclonal light chains and have not been reported in patients with circulating monoclonal heavy chains. Objective. - To determine the incidence of proximal tubulopathies in a series of patients with monoclonal light chain-related renal lesions and characterize them with an emphasis on clinical correlations and elucidation of molecular mechanisms involved in their pathogenesis. Design. - A study of 5410 renal biopsies with careful evaluation of light microscopic, immunofluorescence, and electron microscopic findings was conducted to identify these monoclonal light/heavy chain-related lesions. In selected cases, ultrastructural immunolabeling was performed to better illustrate and understand molecular mechanisms involved or to resolve specific diagnostic difficulties. Results. - In all, 2.5% of the biopsies were diagnosed as demonstrating renal pathology associated with monoclonal light or heavy chains. Of these, approximately 46% were classified as proximal tubule-centered lesions, also referred to as monoclonal light chain-associated proximal tubulopathies. These proximal tubulopathies were divided into 4 groups defined by characteristic immunomorphologic manifestations associated with specific clinical settings. Conclusions. - These are important lesions whose recognition in the different clinical settings is extremely important for patients' clinical management, therapeutic purposes, and prognosis. These entities have been segregated into 4 distinct variants, conceptualized morphologically and clinically. Specific mechanisms involved in their pathogenesis are proposed. © 2014, College of American Pathologists. All rights reserved.
Ruiz M.,Louisiana State University
Journal of the International Association of Physicians in AIDS Care | Year: 2010
Background: Lung cancer is one of the most common non-AIDS-defining malignancies among HIV-infected patients. Recent studies suggest that lung cancer risk is 3 to 4 times higher in HIV-infected patients than in uninfected persons after adjusting for other factors such as smoking intensity and duration. Methods: A retrospective chart review (2002-2009) was conducted in our institution. An abstraction form was used to compile data that included demographics, T-cell count, and viral loads before and at the time of diagnosis, comordibities, smoking, and use of alcohol and drugs. Results: A total of 16 patients were found. Of these, 11 (69%) patients were male and 5 (31%) female. The average age at diagnosis was 49 years (range 36-54). The Majority of patients were African American (90%). Their average CD4 counts before and at the time of diagnoses were 241 and 211 cells/mm3, respectively. Their viral loads before and at the time of diagnosis ranged from <48 to 437 000 and <48 to 590 760 copies/mL, respectively. Adenocarcinoma was found in 67% of cases. The majority of cases (85%) were detected at advanced stages (IIIB or IV). Smoking was found in 100% of cases (average of 15-20 pack/year history), alcohol use in 70% of cases, and drug abuse in 50%. Conclusions: Lung cancer is very common in HIV-infected populations. It tends to occur at a young age, and it is usually diagnosed at very advanced stages (IIIB or IV). The main risk factors found in our study were extensive smoking history, young age, male sex, and potentially prolonged immunosuppression. Based on these results, an attempt to construct a high-risk group index might not be appropriate due to the limited number of cases studied and the need for further evaluation of the length of immunosuppression and the real impact of HIV RNA viral load in the development of lung cancer. © The Author(s) 2010.
Depew B.,Louisiana State University |
Bailey J.,Creighton University
Journal of Health Economics | Year: 2015
We investigate the impact of the Affordable Care Act's dependent coverage mandate on insurance premiums. The expansion of dependent coverage under the ACA allows young adults to remain on their parent's private health insurance plans until the age of 26. We find that the mandate has led to a 2.5-2.8 percent increase in premiums for health insurance plans that cover children, relative to single-coverage plans. We are able to conclude that employers did not pass on the entire premium increase to employees through higher required plan contributions. © 2015 Elsevier B.V.
Murray-Tuite P.,Virginia Polytechnic Institute and State University |
Wolshon B.,Louisiana State University
Transportation Research Part C: Emerging Technologies | Year: 2013
This paper presents a review of highway-based evacuation modeling and simulation and its evolution over the past decade. The review includes the major components of roadway transportation planning and operations, including the current state of modeling in the forecasting of evacuation travel demand, distribution and assignment of evacuation demand to regional road networks to reach destinations, assignment of evacuees to various modes of transportation, and evaluation and testing of alternative management strategies to increase capacity of evacuation networks or manage demand. Although this discussion does not cover recent work in other modes used in evacuation such as air, rail, and pedestrian, this paper does highlight recent interdisciplinary modeling work in evacuation to help bridge the gap between the behavioral sciences and engineering and the application of emerging techniques for the verification, validation, and calibration of models. The manuscript also calls attention to special considerations and logistical difficulties, which have received limited attention to date. In addition to these concerns, the following future directions are discussed: further interdisciplinary efforts, including incorporating the medical community; using new technologies for communication of warnings and traffic condition information, data collection, and increased modeling resolution and confidence; using real-time information; and further model refinements and validation. © 2012 Elsevier Ltd.
Oard S.V.,Louisiana State University
Biochimica et Biophysica Acta - Biomembranes | Year: 2011
α-Hordothionin (αHTH) belongs to thionins, the plant antimicrobial peptides with membrane-permeabilizing activity which is associated with broad-range antimicrobial activity. Experimental data have revealed a phospholipid-binding site and indicated formation of ion channels as well as membrane disruption activity of thionin. However, the mechanism of membrane permeabilization by thionin remained unknown. Here it is shown that thionin is a small water-selective channel. Unbiased high-precision molecular modeling revealed formation of a water-selective pore running through the αHTH double α-helix core when the peptide interacted with anions. Anion-induced unfolding of the C-end of the α2-helix opened a pore mouth. The pore started at the α2 C-end between the hydrophilic and the hydrophobic regions of the peptide surface and ended in the middle of the unique hydrophobic region at the C-end of the α1-helix. Highly conserved residues including cysteines and tyrosine lined the pore walls. A large positive electrostatic potential accumulated inside the pore. The narrow pore was, nonetheless, sufficient to accommodate at least one water molecule along the channel except for two constriction sites. Both constriction sites were formed by residues participating in the phospholipid-binding site. The channel properties resembled that of aquaporins with two selectivity filters, one at the entrance, inside the α2 C-end cavity, and a second in the middle of the channel. It is proposed that the αHTH water channel delivers water molecules to the bilayer center that leads to local membrane disruption. The proposed mechanism of membrane permeabilization by thionins explains seemingly controversial experimental data.
Marks B.D.,Louisiana State University
Molecular Phylogenetics and Evolution | Year: 2010
A recent trend in the literature highlights the special role that tropical montane regions and habitat transitions peripheral to large blocks of lowland rainforest play in the diversification process. The emerging view is one of lowland rainforests as evolutionary 'museums'; where biotic diversity is maintained over evolutionary time, and additional diversity is accrued from peripheral areas, but where there has been little recent diversification. This leads to the prediction of genetic diversity without geographic structure in widespread taxa. Here, I assess the notion of the lowland rainforest 'museum' with a phylogeographic study of the green hylia (Aves: Sylviidae: Hylia prasina) using 1132 bp of mtDNA sequence data. The distribution of genetic diversity within the mainland subspecies of Hylia reveals five highly divergent haplotype groups distributed in accordance with broad-scale areas of endemism in the Afrotropics. This pattern of genetic diversity within a currently described subspecies refutes the characterization of lowland forests as evolutionary museums. If the pattern of geographic variation in Hylia occurs broadly in widespread rainforest species, conservation policy makers may need to rethink their priorities for conservation in the Afrotropics. © 2009 Elsevier Inc. All rights reserved.
Malisoff M.,Louisiana State University |
Mazenc F.,Supelec |
Zhang F.,Georgia Institute of Technology
IEEE Transactions on Automatic Control | Year: 2012
We study an important class of feedback controllers that arise in curve tracking problems for robotics. Previous experimental results suggested the robust performance of the control laws under perturbations. Here we use input-to-state stability to prove predictable tolerance and safety bounds that ensure robust performance under perturbations and time delays. Our proofs are based on an invariant polygon argument and a new strict Lyapunov function design. © 2012 IEEE.
Singh P.,Louisiana State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
We investigate the effects of the underlying quantum geometry in loop quantum cosmology on spacetime curvature invariants and the extendibility of geodesics in the Bianchi-I model for matter with a vanishing anisotropic stress. Using the effective Hamiltonian approach, we find that even though quantum geometric effects bound the energy density and expansion and shear scalars, divergences of curvature invariants are potentially possible under special conditions. However, as in the isotropic models in LQC, these do not necessarily imply a physical singularity. Analysis of geodesics and strength of such singular events, point towards a general resolution of all known types of strong singularities. We illustrate these results for the case of a perfect fluid with an arbitrary finite equation of state w>-1, and show that curvature invariants turn out to be bounded, leading to the absence of strong singularities. Unlike classical theory, geodesic evolution does not break down. We also discuss possible generalizations of sudden singularities which may arise at a nonvanishing volume, causing a divergence in curvature invariants. Such finite volume singularities are shown to be weak and harmless. © 2012 American Physical Society.
Husseneder C.,Louisiana State University
Environmental Entomology | Year: 2010
The symbiotic relationship of termites and their eukaryotic and prokaryotic gut microbiota is a focal point of research because of the important roles symbionts play in termite nutrition. The use of molecular methods has recently provided valuable insights into the species diversity and the roles of microorganisms in the guts of termites. This paper provides a review of the current knowledge of symbiont species inventories, genome analysis, and gene expression in the guts of subterranean termites. Particular emphasis is given to the termite genera Reticulitermes and Coptotermes (Isoptera: Rhinotermitidae), because they contain pest species of global impact in their native and invasive range. © 2010 Entomological Society of America.
McCarley R.L.,Louisiana State University
Annual Review of Analytical Chemistry | Year: 2012
Stimuli-responsive systems for the transport and delivery of materials to a given location at a specific time are highly valuable in numerous applications. The characteristics of the delivery system are dictated by the requirements of a particular application, which include the nature of the stimulus for actuation of the delivery process. Electron transfer has moved to the forefront as a stimulus for responsive delivery systems, particularly for those used in drug and reagent delivery, and for analyte transportseparation avenues. Interest in redox-activated delivery of materials arises from the abundance of redox-active stimuli that can be used to make delivery occur, the often simple chemical nature of the activation process, and the ease of constructing delivery vehicles with an integrated redox-responsive trigger group. This review is focused on vesicle- and micelle-based vehicles whose contents can be delivered by a redox stimulus due to their potential to meet the needs of key applications. Copyright © 2012 by Annual Reviews. All rights reserved.
Murray K.K.,Louisiana State University
Journal of Chromatography A | Year: 2010
This document is a glossary of terms for separations coupled to mass spectrometry. It covers gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry, and supercritical fluid chromatography/mass spectrometry and the sample introduction, ionization, and data analysis methods used with these combined techniques. © 2010 Elsevier B.V.
Ali M.,TU Darmstadt |
Ali M.,COMSATS Institute of Information Technology |
Rau A.R.P.,Louisiana State University |
Alber G.,TU Darmstadt
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010
Quantum discord, a kind of quantum correlation, is defined as the difference between quantum mutual information and classical correlation in a bipartite system. In general, this correlation is different from entanglement, and quantum discord may be nonzero even for certain separable states. Even in the simple case of bipartite quantum systems, this different kind of quantum correlation has interesting and significant applications in quantum information processing. So far, quantum discord has been calculated explicitly only for a rather limited set of two-qubit quantum states and expressions for more general quantum states are not known. In this article, we derive explicit expressions for quantum discord for a larger class of two-qubit states, namely, a seven-parameter family of so called X states that have been of interest in a variety of contexts in the field. We also study the relation between quantum discord, classical correlation, and entanglement for a number of two-qubit states to demonstrate that they are independent measures of correlation with no simple relative ordering between them. © 2010 The American Physical Society.
Bezemer T.M.,Netherlands Institute of Ecology |
Harvey J.A.,Netherlands Institute of Ecology |
Cronin J.T.,Louisiana State University
Annual Review of Entomology | Year: 2014
Invasive plants can disrupt a range of trophic interactions in native communities. As a novel resource they can affect the performance of native insect herbivores and their natural enemies such as parasitoids and predators, and this can lead to host shifts of these herbivores and natural enemies. Through the release of volatile compounds, and by changing the chemical complexity of the habitat, invasive plants can also affect the behavior of native insects such as herbivores, parasitoids, and pollinators. Studies that compare insects on related native and invasive plants in invaded habitats show that the abundance of insect herbivores is often lower on invasive plants, but that damage levels are similar. The impact of invasive plants on the population dynamics of resident insect species has been rarely examined, but invasive plants can influence the spatial and temporal dynamics of native insect (meta)populations and communities, ultimately leading to changes at the landscape level. © Copyright ©2014 by Annual Reviews. All rights reserved.
Keast D.R.,Food and Nutrition Database Research Inc |
Nicklas T.A.,Baylor College of Medicine |
O'Neil C.E.,Louisiana State University
American Journal of Clinical Nutrition | Year: 2010
Background: Snacking is common in adolescents; however, it is unclear if there is an association between snacking and overweight or obesity within the context of the overall diet. Objective: This study examined the associations of snacking with weight status and abdominal obesity in adolescents 12-18 y of age (n = 5811). Design: We conducted secondary analyses of 24-h diet recalls and anthropometric data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004. We classified adolescents by frequency of snack consumption (0, 1, 2, 3, and ≥4 snacks/d) and by the percentage of energy intake from snacks (0%, <10%, 10-19%, 20-29%, 30-39%, and ≥40%). We classified adolescents who had a body mass index (BMI) ≥85th percentile of BMI-for-age as overweight or obese. We defined abdominal obesity as a waist circumference ≥90th percentile. We determined covariate-adjusted prevalences of overweight or obesity and abdominal obesity and odds ratios with SUDAAN software (release 9.0.1; Research Triangle Institute, Research Triangle Park, NC). Results: Mean values of all obesity indicators studied were inversely associated with snacking frequency and percentage of energy from snacks. The prevalence of overweight or obesity and of abdominal obesity decreased with increased snacking frequency and with increased percentage of energy from snacks. Odds ratios (95% CIs) for overweight or obesity and for abdominal obesity ranged from 0.63 (0.48, 0.85) to 0.40 (0.29, 0.57) and from 0.61 (0.43, 0.86) to 0.36 (0.21, 0.63) for 2 to ≥4 snacks/d, respectively. Reduced risks of overweight or obesity and abdominal obesity were associated with snacking. Conclusion: Snackers, compared with nonsnackers, were less likely to be overweight or obese and less likely to have abdominal obesity. © 2010 American Society for Nutrition.
Rousseau V.G.,Louisiana State University
Physical Review B - Condensed Matter and Materials Physics | Year: 2014
We review the concept of superfluidity and, based on real and thought experiments, we use the formalism of second quantization to derive expressions that allow the calculation of the superfluid density for general Hamiltonians with path-integral methods. It is well known that the superfluid density can be related to the response of the free energy to a boundary phase twist, or to the fluctuations of the winding number. However, we show that this is true only for a particular class of Hamiltonians. In order to treat other classes, we derive general expressions of the superfluid density that are valid for various Hamiltonians. While the winding number is undefined when the number of particles is not conserved, our general expressions allow us to calculate the superfluid density in all cases. We also provide expressions of the superfluid densities associated to the individual components of multispecies Hamiltonians, which remain valid when interspecies conversions occur. The cases of continuous and discrete spaces are discussed, and we emphasize common mistakes that occur when considering lattices with nonorthonormal primitive vectors. © 2014 American Physical Society.
Nyman J.A.,Louisiana State University
Estuaries and Coasts | Year: 2014
Inactive deltas are more extensive than active deltas in most deltaic landscapes; thus, the subsurface generally is dominated by mineral sediments that rapidly accreted at different times, whereas the landscape at any one time generally is dominated by ephemeral emergent wetlands that are slowly accreting via vegetative growth. Subsidence is slow enough in most deltas that emergent wetlands, although ephemeral, can persist for millennia but accelerating global sea level rise probably will slow wetland creation in active deltas and accelerate the loss of existing wetlands in inactive deltas this century worldwide. A recent publication created confusion regarding the effects of river management on coastal Louisiana, where spatially variable subsidence is great enough in some areas to mimic extremely rapid sea level rise. I show how integrating Successional Ecology with the Delta Lobe Cycle, and correcting some omissions and errors in recent publications, clarifies the effects of river management in coastal Louisiana and provides a framework for predicting deltaic landscape dynamics worldwide. Successional Ecology provides a framework for understanding changes in natural and managed environments worldwide, whereas the Delta Lobe Cycle provides a framework for understanding river-dominated deltas worldwide. Sediment diversions are a form of river management that removes artificial barriers to river flow and are designed to mimic hydrologic conditions during the active delta stage of the Delta Lobe Cycle by focusing rapid mineral sedimentation in open water and thus creating new emergent wetlands. Freshwater diversions are another form of river management that also removes artificial barriers to river flow but are designed to mimic hydrologic conditions during the inactive stages of the Delta Lobe Cycle by reducing salinity stress over large areas of emergent wetlands and thus promoting marsh vertical accretion via vegetative growth. The Delta Lobe Cycle and both types of river diversions also create salinity gradients that simultaneously increase the sensitivity of emergent wetlands to disturbance while increasing the ability of emergent wetlands to recover from disturbance. Freshwater diversions only slow the loss of existing wetlands because the natural Delta Lobe Cycle, artificial channels that increase salinity stress, artificial ridges that increase flooding stress, and repeated disturbances eventually will cause vertical accretion via vegetative growth to become inadequate. Formally integrating these concepts might advance research and restoration in deltaic landscapes worldwide especially in the majority of deltas where inactive deltas are more extensive than active deltas. © 2014, Coastal and Estuarine Research Federation.
Wang F.,Louisiana State University
Annals of GIS | Year: 2012
This article provides an overview of major application areas of geographic information systems (GISs) in police departments and policing practices, mainly in the United States. It begins with a quick review of historical evolution of GIS applications in law enforcement from prototype computerized crime mapping to sophisticated spatial analysis and its integration in policing practices. Six major areas of GIS applications in police and policing are discussed with case studies to illustrate the value of GIS as (1) a partner for field officers, (2) a crime investigation and prevention tool, (3) a policy implementation and evaluation tool, (4) a police force planning tool, (5) a tool for testing crime theories, and (6) a communication tool. The article is concluded with an outlook for some emerging trends. © 2012 Copyright Taylor and Francis Group, LLC.
Rizzuto T.E.,Louisiana State University
Computers in Human Behavior | Year: 2011
Two workplace trends will become increasingly important in years to come: reliance on information technology (IT) and workforce aging. This study explores the influence of workplace context on employee reactions to the implementation of a new IT initiative to better understand innovation enhancers and inhibitors. Employees from multiple workplace departments completed a questionnaire that assessed their reactions to the implementation. Age-based differences and contextual influences were estimated to predict satisfaction with the implementation process. Hierarchical linear models indicate that younger workers reported less satisfaction than older workers - an effect that was more pronounced in relatively young departments. These findings challenge ageist notions and emphasize the role of context on attitudes formation. Multi-institutional and multilevel field-setting data are rare making this a unique research contribution. © 2011 Elsevier Ltd. All rights reserved.
Chen Y.,University of Kentucky |
Lipton R.,Louisiana State University
Archive for Rational Mechanics and Analysis | Year: 2013
A generic class of metamaterials is introduced and is shown to exhibit frequency dependent double negative effective properties. We develop a rigorous method for calculating the frequency intervals where either double negative or double positive effective properties appear and show how these intervals imply the existence of propagating Bloch waves inside sub-wavelength structures. The branches of the dispersion relation associated with Bloch modes are shown to be explicitly determined by the Dirichlet spectrum of the high dielectric phase and the generalized electrostatic spectra of the complement. © 2013 Springer-Verlag Berlin Heidelberg.
Aly A.M.,Louisiana State University
Wind and Structures, An International Journal | Year: 2013
In wind load calculations based on pressure measurements, the concept of 'tributary area' is usually used. The literature has less guidance for a systematic computational methodology for calculating tributary areas, in general, and for scattered pressure taps, in particular. To the best of the author's knowledge, there is no generic mathematical equation that helps calculate the tributary areas for irregular pressure taps. Traditionally, the drawing of tributary boundaries for scattered and intensively distributed taps may not be feasible (a time and resource consuming task). To alleviate this problem, this paper presents a proposed numerical approach for tributary area calculations on rectangular surfaces. The approach makes use of the available coordinates of the pressure taps and the dimensions of the surface. The proposed technique is illustrated by two application examples: first, quasi-regularly distributed pressure taps, and second, taps that have scattered distribution on a rectangular surface. The accuracy and the efficacy of the approach are assessed, and a comparison with a traditional method is presented. © 2013 Techno-Press, Ltd.
Kaufman H.E.,Louisiana State University |
Haw W.H.,Shiley Eye Center
Current Eye Research | Year: 2012
Background: Until the availability of ganciclovir ophthalmic gel in 2009, the only option for treating herpes simplex (HSV) keratitis in the USA has been trifluridine (TFT), a compound with tolerability issues related to its nonselective inhibition of DNA replication in both normal cells and virus-infected cells. Ganciclovir has selective pharmacologic activity on viral thymidine kinase and a lower potential for toxicity to healthy human cells. Our objective was to evaluate safety and efficacy findings reported with the use of ganciclovir ophthalmic gel, both for HSV keratitis and other potential clinical indications. Methods: Clinical and preclinical data with ganciclovir were identified through a comprehensive electronic search of PubMed and Medline, using the search terms ganciclovir, ganciclovir 0.15% ophthalmic gel, acyclovir, acyclovir ointment 3%, herpes simplex keratitis, treatment of herpes simplex keratitis, and adenoviral keratoconjunctivitis. The authors were also granted access to previously unpublished ganciclovir surveillance safety data from Bausch & Lomb, Inc. Results: No clinical data comparing ganciclovir ophthalmic gel to 1% trifluorothymidine (TFT) for HSV keratitis could be identified. Four international, randomized, multicenter clinical trials have demonstrated that ganciclovir gel is at least as effective as acyclovir ointment for the treatment of HSV keratitis. Ganciclovir gel was better tolerated, with lower rates of blurred vision, eye irritation, and punctate keratitis. Recent data also indicate it may hold promise as a treatment for adenoviral keratoconjunctivitis. Worldwide safety surveillance data collected over the past 10-15 years in over 30 countries suggests an extremely low rate of spontaneously reported adverse events with ganciclovir ophthalmic gel. Conclusions: Current data suggest that ganciclovir ophthalmic gel has similar efficacy as acyclovir ointment for the treatment of HSV keratitis and is better tolerated. Clinical head-to-head studies comparing ganciclovir and TFT would be of great interest, especially for US physicians. © 2012 Informa Healthcare USA, Inc.
Katzmarzyk P.T.,Louisiana State University |
Lee I.-M.,Harvard University
BMJ Open | Year: 2012
Objectives: To determine the impact of sitting and television viewing on life expectancy in the USA. Design: Prevalence-based cause-deleted life table analysis. Setting: Summary RRs of all-cause mortality associated with sitting and television viewing were obtained from a meta-analysis of available prospective cohort studies. Prevalences of sitting and television viewing were obtained from the US National Health and Nutrition Examination Survey. Primary outcome measure: Life expectancy at birth. Results: The estimated gains in life expectancy in the US population were 2.00 years for reducing excessive sitting to <3 h/day and a gain of 1.38 years from reducing excessive television viewing to <2 h/day. The lower and upper limits from a sensitivity analysis that involved simultaneously varying the estimates of RR (using the upper and lower bounds of the 95% CI) and the prevalence of television viewing (±20%) were 1.39 and 2.69 years for sitting and 0.48 and 2.51 years for television viewing, respectively. Conclusion: Reducing sedentary behaviours such as sitting and television viewing may have the potential to increase life expectancy in the USA.
Almog Y.,Louisiana State University
Archive for Rational Mechanics and Analysis | Year: 2013
We consider a large number of randomly dispersed spherical, identical, inclusions in a bounded domain, with conductivity different than that of the host medium. In the dilute limit, with some mild assumptions on the first few marginal probability densities (no periodicity or stationarity is assumed), we prove convergence in the H1 norm of the expectation of the solution of the steady state heat equation to the solution of an effective medium problem, where the conductivity is given by the Clausius-Mossotti formula. Error estimates are provided as well. © 2012 Springer-Verlag Berlin Heidelberg.
Hesp P.A.,Louisiana State University |
Walker I.J.,University of Victoria
Aeolian Research | Year: 2012
This paper examines the æolian dynamics of a deep bowl blowout within the foredune of the Greenwich Dunes, on the northeastern shore or Prince Edward Island, Canada. Masts of cup anemometers and sonic anemometers were utilized to measure flow velocities and directions during a strong regional ESE (offshore) wind event. The flow across the blowout immediately separated at the upwind rim crest, and within the blowout was strongly reversed. High, negative vertical flows occurred down the downwind (but seaward) vertical scarp which projected into the separation envelope and topographically forced flow back into the blowout. A pronounced, accelerated jet flow existed near the surface across the blowout basin, and the flow exhibited a complex, anti-clockwise structure with the near-surface flow following the contours around the blowout basin and lower slopes. Significant æolian sediment transport occurred across the whole bowl basin and sediment was delivered by saltation and suspension out the blowout to the east. This study demonstrates that strong offshore winds produce pronounced topographically forced flow steering, separation, reversal, and more complex three-dimensional motions within a bowl blowout, and that such winds within a bowl blowout play a notable role in transporting sediment within and beyond deep topographic hollows in the foredune. © 2011 Elsevier B.V.
Esquenazi S.,Louisiana State University
Journal of glaucoma | Year: 2010
To report 4 cases of Descemet stripping automated endothelial keratoplasty (DSAEK) in the presence of previous glaucoma filtering surgery. Observational case series. Review of clinical data of 4 patients who underwent DSAEK successfully performed in the presence of previous glaucoma filtering surgery with endothelial survival rates comparable with larger series published previously and good postoperative intraocular pressure (IOP) control. The endothelial cell loss was 36% and 39% mean cell loss at 6 months and 1 year postoperatively. The IOP remained well controlled within target levels in all patients. No complications were reported in any of the 4 cases. Corneal endothelial failure can be successfully managed with DSAEK in glaucoma patients with previous filtering surgery with good endothelial survival rates and IOP control.
Li T.,Louisiana State University
Journal of Physical Chemistry B | Year: 2014
We report a theoretical study on the relaxation dynamics of Staphylococcus nuclease following photon excitation. Molecular dynamics simulations were implemented for both ground state and excited state surface of Trp140. Over the course of 40 ns ground state simulation, a structural transition was observed from one isomeric protein configuration to another. No obvious isomerization process was exhibited in the excited state simulations. Using linear response theory and direct nonequilibrium approach, time-dependent Stokes shift, as well as its time-infinity value, was evaluated for both ground state isomers. Comparison between these methods exhibits severe disagreement. The nonequilibrium simulations show the similar relaxation dynamics as the excited state linear response approach, whereas they severely differ from the ground state linear response evaluation. Further examination reveals that the isomerization process breaks the characteristics of the energy gap histogram from Gaussian statistics. We also made the comparison between the experimental and simulation results. The significant inertial decay, in theory, is absent in the experiment. The ground state linear response evaluation provides a better agreement with the experimental results among all three approaches. (Graph Presented). © 2014 American Chemical Society.
Dixit V.D.,Louisiana State University
Seminars in Immunology | Year: 2012
Emerging evidence indicates that the immune and metabolic interactions control several aspects of the aging process and associated chronic diseases. Among several sites of immune-metabolic interactions, thymic demise represents a particularly puzzling phenomenon because even in metabolically healthy middle-aged individuals the majority of thymic space is replaced with ectopic lipids. The new T cell specificities can only be generated in a functional thymus and, peripheral proliferation of pre-existing T cell clones provides limited immune-vigilance in the elderly. Therefore, it is hypothesized that the strategies that enhance thymic-lymphopoiesis may extend healthspan. Recent data suggest that byproducts of thymic fatty acids and lipids result in accumulation of 'lipotoxic DAMPs' (damage associated molecular patterns), which triggers the innate immune-sensing mechanism like inflammasome activation which links aging to thymic demise. The immune-metabolic interaction within the aging thymus produces a local pro-inflammatory state that directly compromises the thymic stromal microenvironment, thymic-lymphopoiesis and serves a precursor of systemic immune-dysregulation in the elderly. New evidence also suggests that ectopic thymic adipocytes may develop from specific intrathymic stromal cell precursors instead of a passive process that is simply a consequence of thymic lymphopenia. Thus the complex bidirectional interactions between metabolic and immune systems may link aging to health, T cell senescence, and associated diseases. This review discusses the immune-metabolic mechanisms during aging - with implications for developing future therapeutic strategies for living well beyond the expected. © 2012 Elsevier Ltd.
Aboul-Ela F.,Louisiana State University
Future Medicinal Chemistry | Year: 2010
Bacterial ribosomal RNA is the target of clinically important antibiotics, while biologically important RNAs in viral and eukaryotic genomes present a range of potential drug targets. The physicochemical properties of RNA present difficulties for medicinal chemistry, particularly when oral availability is needed. Peptidic ligands and analysis of their RNA-binding properties are providing insight into RNA recognition. RNA-binding ligands include far more chemical classes than just aminoglycosides. Chemical functionalities from known RNA-binding small molecules are being exploited in fragment- and ligand-based projects. While targeting of RNA for drug design is very challenging, continuing advances in our understanding of the principles of RNA-ligand interaction will be necessary to realize the full potential of this class of targets. © 2010 Future Science Ltd.
Grove A.,Louisiana State University
Current Issues in Molecular Biology | Year: 2011
Bacterial histone-like HU proteins are critical to maintenance of the nucleoid structure. In addition, they participate in all DNA-dependent functions, including replication, repair, recombination and gene regulation. In these capacities, their function is typically architectural, inducing a specific DNA topology that promotes assembly of higher-order nucleo-protein structures. Although HU proteins are highly conserved, individual homologs have been shown to exhibit a wide range of different DNA binding specificities and affinities. The existence of such distinct specificities indicates functional evolution and predicts distinct in vivo roles. Emerging evidence suggests that HU proteins discriminate between DNA target sites based on intrinsic flexure, and that two primary features of protein binding contribute to target site selection: The extent to which protein-mediated DNA kinks are stabilized and a network of surface salt-bridges that modulate interaction between DNA flanking the kinks and the body of the protein. These features confer target site selection for a specific HU homolog, they suggest the ability of HU to induce different DNA structural deformations depending on substrate, and they explain the distinct binding properties characteristic of HU homologs. Further divergence is evidenced by the existence of HU homologs with an additional lysine-rich domain also found in eukaryotic histone H1.
Barker S.A.,Louisiana State University
Drug testing and analysis | Year: 2012
Three indole alkaloids that possess differing degrees of psychotropic/psychedelic activity have been reported as endogenous substances in humans; N,N-dimethyltryptamine (DMT), 5-hydroxy-DMT (bufotenine, HDMT), and 5-methoxy-DMT (MDMT). We have undertaken a critical review of 69 published studies reporting the detection or detection and quantitation of these compounds in human body fluids. In reviewing this literature, we address the methods applied and the criteria used in the determination of the presence of DMT, MDMT, and HDMT. The review provides a historical perspective of the research conducted from 1955 to 2010, summarizing the findings for the individual compounds in blood, urine, and/or cerebrospinal fluid. A critique of the data is offered that addresses the strengths and weaknesses of the methods and approaches to date. The review also discusses the shortcomings of the existing data in light of more recent findings and how these may be overcome. Suggestions for the future directions of endogenous psychedelics research are offered. Copyright © 2012 John Wiley & Sons, Ltd.
Kaiser M.J.,Louisiana State University
Marine Policy | Year: 2015
The offshore oil and gas industry is susceptible to natural and man-made disasters. From 2004 to 2008, five major hurricanes-destroyed 181 structures and 1673 wells in the Gulf of Mexico. State and federal regulatory agencies were forced to deal with an unprecedented number of applications to Rigs-to-Reef Programs because operators wanted to permit their toppled structures as reefs. In 2009, the Minerals Management Service issued a moratorium on reef proposals outside of established planning areas in response to public criticism and NGO assertions that Rigs-to-Reef was becoming a de facto "Ocean Dumping Program". In 2013, the moratorium was lifted, and in a recently released Rigs-to-Reef Interim Policy Document 2013-07, the Bureau of Safety and Environmental Enforcement specified that no departures from regulatory requirements will be granted for toppled structures. The purpose of this article is to describe the status of hurricane clean-up activity in the Gulf of Mexico, and to identify the challenges associated with unconventional decommissioning operations. Through 2013, 141 hurricane-destroyed structures and 1537 wells have been decommissioned. Remaining structures that await regulatory approval are likely to be more expensive and difficult to decommission relative to previous activity. Federal regulatory responses in the aftermath of the hurricane destruction are described. © 2014 Elsevier Ltd.
Nicklas T.A.,Baylor College of Medicine |
O'Neil C.E.,Louisiana State University |
Fulgoni III V.L.,Nutrition Impact LLC
Journal of Nutrition | Year: 2012
The goal of the study was to determine if there was an association between diet quality and cardiovascular risk factors (CVRF) in adults. NHANES 2001-2008 data were used to compare diet quality, as determined by using 2005 Healthy Eating Index (HEI-2005) scores, and CVRF in adults aged $19 y (n = 18,988; 51% men, 50% white, 21% African American, 25% Hispanic American, 4% other). HEI-2005 scores were calculated by using one 24-h dietary recall collected from the participants. Weight and adiposity, blood pressure, and CVRF were measured. Regression analyses were conducted to assess the linear relationship of CVRF and HEI-2005 scores by using appropriate covariates accounting for sample weights and the complex sample design of NHANES. OR were calculated for HEI quartiles and CVRF. BMI (P < 0.0001), waist circumference (WC) (P < 0.0001), diastolic blood pressure (P = 0.0002), C-reactive protein (P = 0.0016), total cholesterol (P = 0.0006), LDL cholesterol (P = 0.0039), and metabolic syndrome (P = 0.0035) were inversely associated with HEI-2005. HDL cholesterol significantly (P = 0.0048) increased across HEI-2005 quartiles. Compared with the lowest HEI-2005 quartile, individuals with the highest diet quality (HEI-2005 quartile 4) were less likely to be overweight or obese (34%) or have elevated WC (35%), elevated blood pressure (26%), metabolic syndrome (35%), and decreased HDL-cholesterol concentrations (21%).Data suggest that diet quality is inversely associated with several CVRF. © 2012 American Society for Nutrition.
Aly A.M.,Louisiana State University
Smart Structures and Systems | Year: 2014
Tuned mass dampers (TMDs) have been installed in many high-rise buildings, to improve their resiliency under dynamic loads. However, high-rise buildings may experience natural frequency changes under ambient temperature fluctuations, extreme wind loads and relative humidity variations. This makes the design of a TMD challenging and may lead to a detuned scenario, which can reduce significantly the performance. To alleviate this problem, the current paper presents a proposed approach for the design of a robust and efficient TMD. The approach accounts for the uncertain natural frequency, the optimization objective and the input excitation. The study shows that robust design parameters can be different from the optimal parameters. Nevertheless, predetermined optimal parameters are useful to attain design robustness. A case study of a high-rise building is executed. The TMD designed with the proposed approach showed its robustness and effectiveness in reducing the responses of high-rise buildings under multidirectional wind. The case study represents an engineered design that is instructive. The results show that shear buildings may be controlled with less effort than cantilever buildings. Structural control performance in high-rise buildings may depend on the shape of the building, hence the flow patterns, as well as the wind direction angle. To further increase the performance of the robust TMD in one lateral direction, active control using LQG and fuzzy logic controllers was carried out. The performance of the controllers is remarkable in enhancing the response reduction. In addition, the fuzzy logic controller may be more robust than the LQG controller. Copyright © 2014 Techno-Press, Ltd.
White J.E.,Audubon Sugar Institute |
White J.E.,U.S. Department of Agriculture |
Catallo W.J.,Louisiana State University |
Legendre B.L.,Audubon Sugar Institute
Journal of Analytical and Applied Pyrolysis | Year: 2011
Biomass pyrolysis is a fundamental thermochemical conversion process that is of both industrial and ecological importance. From designing and operating industrial biomass conversion systems to modeling the spread of wildfires, an understanding of solid state pyrolysis kinetics is imperative. A critical review of kinetic models and mathematical approximations currently employed in solid state thermal analysis is provided. Isoconversional and model-fitting methods for estimating kinetic parameters are comparatively evaluated. The thermal decomposition of biomass proceeds via a very complex set of competitive and concurrent reactions and thus the exact mechanism for biomass pyrolysis remains a mystery. The pernicious persistence of substantial variations in kinetic rate data for solids irrespective of the kinetic model employed has exposed serious divisions within the thermal analysis community and also caused the broader scientific and industrial community to question the relevancy and applicability of all kinetic data obtained from heterogeneous reactions. Many factors can influence the kinetic parameters, including process conditions, heat and mass transfer limitations, physical and chemical heterogeneity of the sample, and systematic errors. An analysis of thermal decomposition data obtained from two agricultural residues, nutshells and sugarcane bagasse, reveals the inherent difficulty and risks involved in modeling heterogeneous reaction systems. © 2011 Published by Elsevier B.V.
Ptitsyn A.A.,Colorado State University |
Gimble J.M.,Louisiana State University
Annals of Medicine | Year: 2011
Multiple microarray studies have documented the importance of circadian regulation of gene expression in different species under many experimental conditions. However, these reports often differ with respect to the identity and total number of oscillating genes. This review explores the interrelated questions of: How many genes are oscillating within individual tissues or systems? What are the forces that drive these oscillations? What are the methodological sources contributing to the discrepancy between estimates of gene oscillation? And finally, what are the physiological and systemic implications of oscillatory gene expression with respect to circadian molecular biology? Since this remains an evolving area of investigation, this hypothetical and speculative review also highlights the potential limitations faced by the current data in the literature relating to the novel paradigm(s) proposed. © 2011 Informa UK, Ltd.
Conrad E.J.,Louisiana State University
Southern medical journal | Year: 2013
Little is known about patient populations that remain during or after the mandatory evacuation of a city and use hospital services. This study sought to characterize the population that presented to an emergency department during Hurricane Gustav in 2008. This was a retrospective chart review of patients who presented to the Interim Louisiana State University Hospital emergency department in New Orleans during the 72-hour activation phase of Hurricane Gustav. Of the 104 patients, 51 (49%) had a psychiatric diagnosis. Among the psychiatric patients, 34 (67%) had a substance use disorder diagnosis, 16 (31%) had a mood disorder, 13 (25%) had a psychotic disorder, and 4 (8%) had an anxiety disorder. The psychiatry service was the most used consultation service. To our knowledge, this is the first report to characterize the patient population presenting to an emergency department during a hurricane evacuation. Data suggest that disaster preparedness should include psychiatric consultation services. The consultation psychiatrist may anticipate patients with high levels of substance use disorders and the need for ongoing psychiatric management until the event ends.
Singh P.,Louisiana State University
Bulletin of the Astronomical Society of India | Year: 2014
Singularities in general relativity such as the big bang and big crunch, and exotic singularities such as the big rip are the boundaries of the classical space-times. These events are marked by a divergence in the curvature invariants and the breakdown of the geodesic evolution. Recent progress on implementing techniques of loop quantum gravity to cosmological models reveals that such singularities may be generically resolved because of the quantum gravitational effects. Due to the quantum geometry, which replaces the classical differential geometry at the Planck scale, the big bang is replaced by a big bounce without any assumptions on the matter content or any fine tuning. In this manuscript, we discuss some of the main features of this approach and the results on the generic resolution of singularities for the isotropic as well as anisotropic models. Using effective spacetime description of the quantum theory, we show the way quantum gravitational effects lead to the universal bounds on the energy density, the Hubble rate and the anisotropic shear. We discuss the geodesic completeness in the effective spacetime and the resolution of all of the strong singularities. It turns out that despite the bounds on energy density and the Hubble rate, there can be divergences in the curvature invariants. However such events are geodesically extendible, with tidal forces not strong enough to cause inevitable destruction of the in-falling objects. © 2014 Astronomical Society of India, Indian Institute of Astrophysics. All rights reserved.
Chakrabarty P.,Louisiana State University |
Davis M.P.,The Field Museum |
Sparks J.S.,American Museum of Natural History
PLoS ONE | Year: 2012
We show using the most complete phylogeny of one of the most species-rich orders of vertebrates (Gobiiformes), and calibrations from the rich fossil record of teleost fishes, that the genus Typhleotris, endemic to subterranean karst habitats in southwestern Madagascar, is the sister group to Milyeringa, endemic to similar subterranean systems in northwestern Australia. Both groups are eyeless, and our phylogenetic and biogeographic results show that these obligate cave fishes now found on opposite ends of the Indian Ocean (separated by nearly 7,000 km) are each others closest relatives and owe their origins to the break up of the southern supercontinent, Gondwana, at the end of the Cretaceous period. Trans-oceanic sister-group relationships are otherwise unknown between blind, cave-adapted vertebrates and our results provide an extraordinary case of Gondwanan vicariance. © 2012 Chakrabarty et al.
Mazenc F.,Supelec |
Malisoff M.,Louisiana State University
Automatica | Year: 2013
A problem of state feedback stabilization of time-varying feedforward systems with a pointwise delay in the input is solved. The approach relies on a time-varying change of coordinates and Lyapunov-Krasovskii functionals. The result applies for any given constant delay, and provides uniformly globally asymptotically stabilizing controllers of arbitrarily small amplitude. Although exact model knowledge and periodicity of the dynamics are required, the closed-loop systems enjoy input-to-state stability properties with respect to additive uncertainty on the controllers. The work is illustrated through a tracking problem for a model for high level formation flight of unmanned air vehicles. © 2012 Elsevier Ltd. All rights reserved.
Stevens R.D.,Louisiana State University