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Search Results: 1 - 10 of 481559 matches for " S. L. Lewis "
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Monk?s tonsure-like gaps in the tussock grass Spartina argentinensis (Gramineae)
Lewis,J. P.; Stofella,S. L.; Feldman,S. R.;
Revista de Biología Tropical , 2001,
Abstract: monk's tonsure-like gaps develop inside gramineans and other plants. the tonsures of spartina argentinensis originate as a result of tussock development and disturbance. as the tonsure develops the ring of tillers around it breakes down and new tussocks develop from the fragments, regenerating the grassland matrix vegetatively. the microenvironment inside the tonsure is different from the surroundings and microhabitat-specific taxa grow there.
Monk’s tonsure-like gaps in the tussock grass Spartina argentinensis (Gramineae)
J. P. Lewis,S. L. Stofella,S. R. Feldman
Revista de Biología Tropical , 2001,
Abstract: Monk's tonsure-like gaps develop inside gramineans and other plants. The tonsures of Spartina argentinensis originate as a result of tussock development and disturbance. As the tonsure develops the ring of tillers around it breakes down and new tussocks develop from the fragments, regenerating the grassland matrix vegetatively. The microenvironment inside the tonsure is different from the surroundings and microhabitat-specific taxa grow there. Los "claros tipo tonsura de monje" se desarrollan tanto en el interior de matas de gramíneas, como de especies no pertenecientes a dicha familia. Describimos las matas de Spartina argentinensis y sus tonsuras que surgen por el propio desarrollo de la mata y disturbios. A medida que la tonsura se desarrolla, el anillo de culmos que la rodea se rompe y nuevas matas se desarrollan a partir de los fragmentos, regenerando vegetativamente la matriz del pastizal. Los microambientes dentro y fuera de la tonsura son distintos, al igual que las especies que se establecen en ellos.
Stress repair mechanism activity explains inflammation and apoptosis  [PDF]
Lewis S. Coleman
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.324065
Abstract: A review of modern evidence using Internet resources has identified the Stress Repair Mechanism (SRM) postulated by Hans Selye in 1951. SRM activity regulates thrombin generation to govern tissue maintenance, tissue repair, hemodynamic physiology, inflammation, and apoptosis. Thrombin utilizes ATP to energize coagulation, capillary hemostasis, chemotaxis, immune activity, mitosis, metabolism, angiogenesis, and the release of chemokines, cytokines, bradykinins, and prostaglandins that enable cell-to-cell communications, promote perfusion, loosen cell connections, and sensitize nociceptors during tissue repair. The orchestration of these diverse activities by the SRM explains the disparate elements of the inflammation syndrome, including dolor (pain), rubor (redness), calor (heat), tumor (swelling), and Functio laesa (loss of function). Inflammation resolves as tissue repair nears completion and declining SRM activity restores thrombin to maintenance levels. As thrombin levels decline below a critical threshold, repair cells undergo apoptosis and clots disintegrate. Apoptosis shrinks granulation tissues to enable wound closure. Apoptosis also facilitates embryological development. Occult systemic SRM hyperactivity due to sepsis, surgery, trauma, chemicals, pain, fear, and emotional memories causes inflammatory effects that manifest as the fever, edema, malignancy, organ disruption, eclampsia, Multi-System Organ Failure (MS-OF), Systemic Inflammatory Response Syndrome (SI-RS), Adult Respiratory Distress Syndrome (ARDS), Disseminated Intravascular Coagulation (DIC) and other pathologies.
Analysis of the relationship between psoriasis symptom severity and quality of life, work productivity, and activity impairment among patients with moderate-to-severe psoriasis using structural equation modeling
Lewis-Beck C,Abouzaid S,Xie L,Baser O
Patient Preference and Adherence , 2013,
Abstract: Colin Lewis-Beck,1 Safiya Abouzaid,2 Lin Xie,3 Onur Baser,3,4 Edward Kim51Freddie Mac, Washington, DC, 2Eisai, Woodcliff Lake, NJ, 3STATinMED Research, 4The University of Michigan, Ann Arbor, MI, 5Novartis Pharmaceuticals Corporation, East Hanover, NJ, USABackground: Plaque psoriasis is a chronic disease characterized by scaly plaques on the skin that can itch and bleed. Psoriasis covering over 10% of the body is classified as moderate to severe, and can impact patient quality of life.Objectives: To assess the relationship between plaque psoriasis self-reported severity symptoms and health-related quality of life, work productivity, and activity impairment among patients with moderate-to-severe psoriasis.Methods: The study sample included 199 patients recruited from internet panels, of which 179 respondents had plaque psoriasis and 20 had plaque and inverse psoriasis. Itching, pain, and scaling symptoms were studied. A structural equation modeling framework was used to estimate the effect of these symptoms on patient outcomes. First, each severity variable was regressed on a set of covariates to generate a predicted severity score. These predicted values were placed in a second-stage model with patient mental and physical scores (Short-Form 12 questionnaire), work productivity, and activity impairment indicators as dependent variables.Results: Itching severity had a marginal negative effect (P < 0.06) on patients' Short-Form 12 physical and mental component scores. Pain severity also negatively affected physical and mental health scores (P < 0.02). Patients were more likely to miss work because of itching (odds ratio [OR]: 2.31, 95% confidence interval [CI]: 1.30, 4.10), pain (OR: 1.78, 95% CI: 1.25, 2.52), and scaling (OR: 2.15, 95% CI: 1.31, 3.52) symptoms. These symptoms also lowered self-reported productivity. As itching (OR: 1.74, 95% CI: 1.03, 2.95), scaling (OR: 1.84, 95% CI: 1.16, 2.90), and pain symptoms (OR: 1.53, 95% CI: 1.12, 2.09) increased, so did the odds that a patient would be less productive at work.Conclusion: Plaque psoriasis significantly affects patient quality of life. In addition to greater mental and physical pain, patients are more likely to miss work and have diminished productivity as symptom severity increases.Keywords: psoriasis, severity, activity impairment, work productivity loss, structural equation modeling
Vibrational Properties of Nanoscale Materials: From Nanoparticles to Nanocrystalline Materials
R. Meyer,L. J. Lewis,S. Prakash,P. Entel
Physics , 2003, DOI: 10.1103/PhysRevB.68.104303
Abstract: The vibrational density of states (VDOS) of nanoclusters and nanocrystalline materials are derived from molecular-dynamics simulations using empirical tight-binding potentials. The results show that the VDOS inside nanoclusters can be understood as that of the corresponding bulk system compressed by the capillary pressure. At the surface of the nanoparticles the VDOS exhibits a strong enhancement at low energies and shows structures similar to that found near flat crystalline surfaces. For the nanocrystalline materials an increased VDOS is found at high and low phonon energies, in agreement with experimental findings. The individual VDOS contributions from the grain centers, grain boundaries, and internal surfaces show that, in the nanocrystalline materials, the VDOS enhancements are mainly caused by the grain-boundary contributions and that surface atoms play only a minor role. Although capillary pressures are also present inside the grains of nanocrystalline materials, their effect on the VDOS is different than in the cluster case which is probably due to the inter-grain coupling of the modes via the grain-boundaries.
Reconstructing the primordial power spectrum
S. L. Bridle,A. M. Lewis,J. Weller,G. Efstathiou
Physics , 2003, DOI: 10.1046/j.1365-8711.2003.06807.x
Abstract: We reconstruct the shape of the primordial power spectrum from the latest cosmic microwave background data, including the new results from the Wilkinson Microwave Anisotropy Probe (WMAP), and large scale structure data from the two degree field galaxy redshift survey (2dFGRS). We tested four parameterizations taking into account the uncertainties in four cosmological parameters. First we parameterize the initial spectrum by a tilt and a running spectral index, finding marginal evidence for a running spectral index only if the first three WMAP multipoles (ell=2,3,4) are included in the analysis. Secondly, to investigate further the low CMB large scale power, we modify the conventional power-law spectrum by introducing a scale above which there is no power. We find a preferred position of the cut at k_c ~ 3e-4 /Mpc although k_c=0 (no cut) is not ruled out. Thirdly we use a model independent parameterization, with 16 bands in wavenumber, and find no obvious sign of deviation from a power law spectrum on the scales investigated. Furthermore the values of the other cosmological parameters defining the model remain relatively well constrained despite the freedom in the shape of the initial power spectrum. Finally we investigate a model motivated by double inflation, in which the power spectrum has a break between two characteristic wavenumbers. We find that if a break is required to be in the range 0.01 < k Mpc <0.1 then the ratio of amplitudes across the break is constrained to be 1.23 +/- 0.14. Our results are consistent with a power law spectrum that is featureless and close to scale invariant over the wavenumber range 0.005 ~< k Mpc ~< 0.15, with a hint of a decrease in power on the largest scales.
Point defects in models of amorphous silicon and their role in structural relaxation
Cristiano L. Dias,Laurent J. Lewis,S. Roorda
Physics , 2001,
Abstract: We have used tight-binding molecular-dynamics simulations to investigate the role of point defects (vacancies and interstitials) on structural relaxation in amorphous silicon. Our calculations give unambiguous evidence that point defects can be defined in the amorphous solid, showing up as anomalies in the valence-charge/Voronoi-volume relation. The changes in the radial distribution functions that take place during annealing are shown to be in close agreement with recent, highly-accurate x-ray diffraction measurements. Our calculations provide strong evidence that structural relaxation in a-Si proceeds by the mutual annihilation of vacancies and interstitials, i.e., local structural changes rather than an overall relaxation of the network.
Measuring non-extensitivity parameters in a turbulent Couette-Taylor flow
Christian Beck,Gregory S. Lewis,Harry L. Swinney
Physics , 2000, DOI: 10.1103/PhysRevE.63.035303
Abstract: We investigate probability density functions of velocity differences at different distances r measured in a Couette-Taylor flow for a range of Reynolds numbers Re. There is good agreement with the predictions of a theoretical model based on non-extensive statistical mechanics (where the entropies are non-additive for independent subsystems). We extract the scale-dependent non-extensitivity parameter q(r, Re) from the laboratory data.
Benchmark experiments with global climate models applicable to extra-solar gas giant planets in the shallow atmosphere approximation
V. L. Bending,S. R. Lewis,U. Kolb
Physics , 2012, DOI: 10.1093/mnras/sts357
Abstract: The growing field of exoplanetary atmospheric modelling has seen little work on standardised benchmark tests for its models, limiting understanding of the dependence of results on specific models and conditions. With spatially resolved observations as yet difficult to obtain, such a test is invaluable. Although an intercomparison test for models of tidally locked gas giant planets has previously been suggested and carried out, the data provided were limited in terms of comparability. Here, the shallow PUMA model is subjected to such a test, and detailed statistics produced to facilitate comparison, with both time means and the associated standard deviations displayed, removing the time dependence and providing a measure of the variability. Model runs have been analysed to determine the variability between resolutions, and the effect of resolution on the energy spectra studied. Superrotation is a robust and reproducible feature at all resolutions.
12.2-GHz methanol masers associated with 1.2-mm dust clumps: Quantifying high-mass star formation evolutionary schemes
S. L. Breen,S. P. Ellingsen,J. L. Caswell,B. E. Lewis
Physics , 2009, DOI: 10.1111/j.1365-2966.2009.15831.x
Abstract: We report the results of a search for 12.2-GHz methanol maser emission, targeted towards 113 known 6.7-GHz methanol masers associated with 1.2-mm dust continuum emission. Observations were carried out with the Australia Telescope National Facility (ATNF) Parkes 64-m radio telescope in the period 2008 June 20 - 25. We detect 68 12.2-GHz methanol masers with flux densities in excess of our 5-sigma detection limit of 0.55 Jy, 30 of which are new discoveries. This equates to a detection rate of 60 per cent, similar to previous searches of comparable sensitivity. We have made a statistical investigation of the properties of the 1.2-mm dust clumps with and without associated 6.7-GHz methanol maser and find that 6.7-GHz methanol masers are associated with 1.2-mm dust clumps with high flux densities, masses and radii. We additionally find that 6.7-GHz methanol masers with higher peak luminosities are associated with less dense 1.2-mm dust clumps than those 6.7-GHz methanol masers with lower luminosities. We suggest that this indicates that more luminous 6.7-GHz methanol masers are generally associated with a later evolutionary phase of massive star formation than less luminous 6.7-GHz methanol maser sources. Analysis of the 6.7-GHz associated 1.2-mm dust clumps with and without associated 12.2-GHz methanol maser emission shows that clumps associated with both class II methanol maser transitions are less dense than those with no associated 12.2-GHz methanol maser emission; suggesting that 12.2-GHz methanol masers are associated with a later evolutionary phase of massive star formation. We present an evolutionary sequence for masers in high-mass star formation regions, placing quantitative estimates on the relative lifetimes for the first time.
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