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Search Results: 1 - 10 of 332348 matches for " L. H. Lewis "
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Antioxidant and Anti-Inflammatory Effects of Peanut Skin Extracts  [PDF]
Wanida E. Lewis, Gabriel K. Harris, Timothy H. Sanders, Brittany L. White, Lisa L. Dean
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.48A003
Abstract: Peanut skins are regarded as a low economic value by-product of the peanut industry; however, they contain high levels of bioactive compounds including catechins and procyanidins, which are known for their health-promoting properties. The in vitro antioxidant activity of peanut skin extracts (PSE) has been reported but the associated anti-inflammatory properties have not been widely examined. This study investigated the anti-inflammatory effects of PSE on the pro-inflammatory enzyme, Cyclooxygenase-2 (COX-2) protein expression, on its downstream product, prostaglandin E2 (PGE2), and on nitrous oxide (NO) levels. Defatted peanut skins were extracted using two aqueous solvent mixtures (50% acetone and 90% ethanol), in order to compare the effects of the two solvent systems on antioxidant and anti-inflammatory properties. PSE antioxidant activity was determined by the hydrophilic oxygen radical absorbance capacity (H-ORAC) assay, while total phenolics were determined by the Folin-Ciocalteu assay and flavan-3-ols and procyanidins were quantified by HPLC. Acetone extracted PSE (A-PSE) exhibited numerically, but not statistically higher H-ORAC and total phenolic values than the ethanol extracted PSE (E-PSE) (1836 μmol Trolox/100 g and 67.9 mg GAE/g, and 1830 μmol Trolox/100 g and 51.8 GAE/g respectively). A-PSE also had higher levels of flavan-3-ols and procyanidins than E-PSE. RAW 264.7 cells were pretreated with 1.0%, 2.5% and 5.0% (v/v) of A-PSE or E-PSE and induced with the inflammatory marker, lipopolysaccharide (LPS) for 12 hours. COX-2 protein expression, measured by Western blotting was significantly (p < 0.05) inhibited by A-PSE and E-PSE at 2.5% and 5.0% concentrations. PGE2 and NO levels measured by ELISA, were significantly (p < 0.05) decreased with increasing added levels of A-PSE and E-PSE suggesting that A-PSE and E-PSE not also possess similar antioxidant properties, but also exhibit similar anti-inflammatory effects.
Learned Non-Rigid Object Motion is a View-Invariant Cue to Recognizing Novel Objects
Lewis L. Chuang,Heinrich H. Bülthoff
Frontiers in Computational Neuroscience , 2012, DOI: 10.3389/fncom.2012.00026
Abstract: There is evidence that observers use learned object motion to recognize objects. For instance, studies have shown that reversing the learned direction in which a rigid object rotated in depth impaired recognition accuracy. This motion reversal can be achieved by playing animation sequences of moving objects in reverse frame order. In the current study, we used this sequence-reversal manipulation to investigate whether observers encode the motion of dynamic objects in visual memory, and whether such dynamic representations are encoded in a way that is dependent on the viewing conditions. Participants first learned dynamic novel objects, presented as animation sequences. Following learning, they were then tested on their ability to recognize these learned objects when their animation sequence was shown in the same sequence order as during learning or in the reverse sequence order. In Experiment 1, we found that non-rigid motion contributed to recognition performance; that is, sequence-reversal decreased sensitivity across different tasks. In subsequent experiments, we tested the recognition of non-rigidly deforming (Experiment 2) and rigidly rotating (Experiment 3) objects across novel viewpoints. Recognition performance was affected by viewpoint changes for both experiments. Learned non-rigid motion continued to contribute to recognition performance and this benefit was the same across all viewpoint changes. By comparison, learned rigid motion did not contribute to recognition performance. These results suggest that non-rigid motion provides a source of information for recognizing dynamic objects, which is not affected by changes to viewpoint.
On the interaction of massive spinor particles with external electromagnetic and torsion fields
Lewis H. Ryder,Ilya L. Shapiro
Physics , 1998, DOI: 10.1016/S0375-9601(98)00503-9
Abstract: We explore the Dirac equation in external electromagnetic and torsion fields. Motivated by the previous study of quantum field theory in an external torsion field, we include a nonminimal interaction of the spinor field with torsion. As a consequence, the torsion axial vector and the electromagnetic potential enter the action in a similar form. The existence of an extra local symmetry is emphasized and the Foldy-Wouthuysen transformation is performed to an accuracy of next to the leading order. We also discuss the motion of a classical test particle in a constant torsion field.
Universal Properties of Linear Magnetoresistance in Strongly Disordered Semiconductors
H. G. Johnson,S. P. Bennett,R. Barua,L. H Lewis,D. Heiman
Physics , 2010, DOI: 10.1103/PhysRevB.82.085202
Abstract: Linear magnetoresistance occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the linear magnetoresistance (LMR) is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of classical LMR that can be applied to other material systems.
Soil Does Not Explain Monodominance in a Central African Tropical Forest
Kelvin S. -H. Peh,Bonaventure Sonké,Jon Lloyd,Carlos A. Quesada,Simon L. Lewis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016996
Abstract: Soil characteristics have been hypothesised as one of the possible mechanisms leading to monodominance of Gilbertiodendron dewerei in some areas of Central Africa where higher-diversity forest would be expected. However, the differences in soil characteristics between the G. dewevrei-dominated forest and its adjacent mixed forest are still poorly understood. Here we present the soil characteristics of the G. dewevrei forest and quantify whether soil physical and chemical properties in this monodominant forest are significantly different from the adjacent mixed forest.
Looking for Discriminating Is Different from Looking for Looking’s Sake
Hans-Joachim Bieg, Jean-Pierre Bresciani, Heinrich H. Bülthoff, Lewis L. Chuang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045445
Abstract: Recent studies provide evidence for task-specific influences on saccadic eye movements. For instance, saccades exhibit higher peak velocity when the task requires coordinating eye and hand movements. The current study shows that the need to process task-relevant visual information at the saccade endpoint can be, in itself, sufficient to cause such effects. In this study, participants performed a visual discrimination task which required a saccade for successful completion. We compared the characteristics of these task-related saccades to those of classical target-elicited saccades, which required participants to fixate a visual target without performing a discrimination task. The results show that task-related saccades are faster and initiated earlier than target-elicited saccades. Differences between both saccade types are also noted in their saccade reaction time distributions and their main sequences, i.e., the relationship between saccade velocity, duration, and amplitude.
Recent and Projected Increases in Atmospheric CO2 Concentration Can Enhance Gene Flow between Wild and Genetically Altered Rice (Oryza sativa)
Lewis H. Ziska, David R. Gealy, Martha B. Tomecek, Aaron K. Jackson, Howard L. Black
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037522
Abstract: Although recent and projected increases in atmospheric carbon dioxide can alter plant phenological development, these changes have not been quantified in terms of floral outcrossing rates or gene transfer. Could differential phenological development in response to rising CO2 between genetically modified crops and wild, weedy relatives increase the spread of novel genes, potentially altering evolutionary fitness? Here we show that increasing CO2 from an early 20th century concentration (300 μmol mol?1) to current (400 μmol mol?1) and projected, mid-21st century (600 μmol mol?1) values, enhanced the flow of genes from wild, weedy rice to the genetically altered, herbicide resistant, cultivated population, with outcrossing increasing from 0.22% to 0.71% from 300 to 600 μmol mol?1. The increase in outcrossing and gene transfer was associated with differential increases in plant height, as well as greater tiller and panicle production in the wild, relative to the cultivated population. In addition, increasing CO2 also resulted in a greater synchronicity in flowering times between the two populations. The observed changes reported here resulted in a subsequent increase in rice dedomestication and a greater number of weedy, herbicide-resistant hybrid progeny. Overall, these data suggest that differential phenological responses to rising atmospheric CO2 could result in enhanced flow of novel genes and greater success of feral plant species in agroecosystems.
QUAGMIRE v1.3: a quasi-geostrophic model for investigating rotating fluids experiments
P. D. Williams, T. W. N. Haine, P. L. Read, S. R. Lewis,Y. H. Yamazaki
Geoscientific Model Development (GMD) & Discussions (GMDD) , 2009, DOI: 10.5194/gmd-2-13-2009
Abstract: QUAGMIRE is a quasi-geostrophic numerical model for performing fast, high-resolution simulations of multi-layer rotating annulus laboratory experiments on a desktop personal computer. The model uses a hybrid finite-difference/spectral approach to numerically integrate the coupled nonlinear partial differential equations of motion in cylindrical geometry in each layer. Version 1.3 implements the special case of two fluid layers of equal resting depths. The flow is forced either by a differentially rotating lid, or by relaxation to specified streamfunction or potential vorticity fields, or both. Dissipation is achieved through Ekman layer pumping and suction at the horizontal boundaries, including the internal interface. The effects of weak interfacial tension are included, as well as the linear topographic beta-effect and the quadratic centripetal beta-effect. Stochastic forcing may optionally be activated, to represent approximately the effects of random unresolved features. A leapfrog time stepping scheme is used, with a Robert filter. Flows simulated by the model agree well with those observed in the corresponding laboratory experiments.
Brown carbon in tar balls from smoldering biomass combustion
R. K. Chakrabarty,H. Moosmüller,L.-W. A. Chen,K. Lewis
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010, DOI: 10.5194/acp-10-6363-2010
Abstract: We report the direct observation of laboratory production of spherical, carbonaceous particles – "tar balls" – from smoldering combustion of two commonly occurring dry mid-latitude fuels. Real-time measurements of spectrally varying absorption ngstr m coefficients (AAC) indicate that a class of light absorbing organic carbon (OC) with wavelength dependent imaginary part of its refractive index – optically defined as "brown carbon" – is an important component of tar balls. The spectrum of the imaginary parts of their complex refractive indices can be described with a Lorentzian-like model with an effective resonance wavelength in the ultraviolet (UV) spectral region. Sensitivity calculations for aerosols containing traditional OC (no absorption at visible and UV wavelengths) and brown carbon suggest that accounting for near-UV absorption by brown carbon leads to an increase in aerosol radiative forcing efficiency and increased light absorption. Since particles from smoldering combustion account for nearly three-fourths of the total carbonaceous aerosol mass emitted globally, inclusion of the optical properties of tar balls into radiative forcing models has significance for the Earth's radiation budget, optical remote sensing, and understanding of anomalous UV absorption in the troposphere.
Could treatment of pregnant mares prevent abortions due to equine piroplasmosis? : research communication
B.D. Lewis,B.L. Penzhorn,D.H. Volkmann
Journal of the South African Veterinary Association , 2012, DOI: 10.4102/jsava.v70i2.760
Abstract: Treatment of pregnant mares to prevent abortions due to equine piroplasmosis is a novel idea practised empirically at some Thoroughbred studs in South Africa. This paper presents the results of an investigation to ascertain whether imidocarb dipropionate crosses the equine placenta. Three pregnant mares were injected intramuscularly with imidocarb and their foetuses were mechanically aborted at varying time intervals thereafter. Imidocarb was found in foetal blood at a level similar to that in the dam's blood, suggesting that imidocarb administered to the dam would be available for anti-parasitic activity in the foetal circulation. Uncertainty concerning the time of treatment to achieve the desired effect currently makes this a questionable exercise.
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