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Search Results: 1 - 10 of 472806 matches for " A William Sheel "
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Clinical review: Guyton - the role of mean circulatory filling pressure and right atrial pressure in controlling cardiac output
William R Henderson, Donald EG Griesdale, Keith R Walley, A William Sheel
Critical Care , 2010, DOI: 10.1186/cc9247
Abstract: The support of blood flow is one of the central goals of clinical medicine, and the understanding of the regulation of blood flow is the sine qua non of cardiac physiology. Building on the foundational work of Frank and Starling, Arthur Guyton proposed that characteristics of the venous circulation were of fundamental importance in the regulation of cardiac output and thus blood flow. However, several authors have raised strong objections to Guyton's model, and more than 50 years after the publication of his model, there is still debate about whether Guyton's ideas present a viable model of cardiac control or whether several fundamental misjudgments lie at the core of Guyton's conclusions [1-4].Traditionally, the heart's accepted role has been that it not only provides the driving force for blood flow but also determines the total blood flow [5-7]. Simply stated, cardiac output is the product of stroke volume and heart rate. In this view, all pressures in the heart and circulatory system (for example, those measured in the large veins, in the cardiac chambers, and in the arteries) are derivatives of the force generated by the heart rather than independent variables that might have an influence on the heart's function and thus cardiac output.At the end of the 19th century, Frank [8] found that ventricular contractility was increased if the ventricle was stretched prior to contraction. Building on this observation, Starling and colleagues [9,10] found that increasing venous return increased stroke volume. We therefore term the ability of the heart to change its force of contraction (and stroke volume) in response to changes in venous return the Frank-Starling mechanism.The ventricle does not operate on a single Frank-Starling curve. Any heart may operate on a family of curves, each of which is defined by the afterload, inotropic state, and diastolic compliance of the heart. Changes in venous return cause the ventricle to move along a single Frank-Starling curve that i
Photoactive Thin Silver Films by Atmospheric Pressure CVD
Heather M. Yates,Lucy A. Brook,David W. Sheel
International Journal of Photoenergy , 2008, DOI: 10.1155/2008/870392
Abstract: We report the visible and UV activity of thin silver films. The films are grown using a CVD process employing aqueous-based silver precursors, flame-assisted chemical vapour deposition. This approach overcomes many of the previously encountered limitations to silver deposition by employing an atmospheric pressure process, low-cost and low-toxicity precursors. The resultant films are assessed for activity using stearic acid destruction as a model compound. We also report on the addition of titania to these silver films to increase the potential functionality. This activity is also demonstrated, where the films appear largely transparent to the eye, further widening the potential application of this work. It is speculated that the nanoparticulate nature, of the CVD silver, is crucial in determining photoactivity.
Urena lobata Flowers: A Green Route to Volumetric Analysis  [PDF]
Dixa Singh, Vimal Sheel Singh
Green and Sustainable Chemistry (GSC) , 2015, DOI: 10.4236/gsc.2015.51001
Abstract: The aqueous and alcoholic extract of Urena lobata flowers has been used in acid/alkali titrations over a wide range of concentration. The results obtained with the flower extracts have been compared with those obtained by using traditional chemical indicators like phenolphthalein and methyl orange. It has been established experimentally that the flower extract can be successfully used in place of phenolphthalein and methyl orange for acid/alkali titrations. The presence of anthocyanins is supposed to impart pH sensitive colour dependence to the natural indicator.
Symplectic cohomology and duality for the wrapped Fukaya category
Sheel Ganatra
Mathematics , 2013,
Abstract: Consider the wrapped Fukaya category W of a collection of exact Lagrangians in a Liouville manifold. Under a non-degeneracy condition implying the existence of enough Lagrangians, we show that natural geometric maps from the Hochschild homology of W to symplectic cohomology and from symplectic cohomology to the Hochschild cohomology of W are isomorphisms, in a manner compatible with ring and module structures. This is a consequence of a more general duality for the wrapped Fukaya category, which should be thought of as a non-compact version of a Calabi-Yau structure. The new ingredients are: (1) Fourier-Mukai theory for W via a wrapped version of holomorphic quilts, (2) new geometric operations, coming from discs with two negative punctures and arbitrary many positive punctures, (3) a generalization of the Cardy condition, and (4) the use of homotopy units and A-infinity shuffle products to relate non-degeneracy to a resolution of the diagonal.
Vacuum Structure in QCD with Quark and Gluon Condensates
A. Mishra,H. Mishra,Varun Sheel,S. P. Misra,P. K. Panda
Physics , 1994, DOI: 10.1142/S0218301396000037
Abstract: We consider here the vacuum structure in QCD with both quark and gluon condensates and a variational ansatz for the ground state. The method is nonperturbative using only equal time algebra for the field operators. We then find that a constrained energy minimisation of the Hamiltonian leads to a QCD vacuum with both quark and gluon condensates for $\alpha_s > \alpha_c=0.62$. Pion decay constant and the charge radius of the pion seem to fix the QCD coupling constant $\alpha_s$ as 1.28. The approach opens up possibilities of relating the mysterious vacuum structure with common place hadronic properties.
Acceleration of Vortex Methods Calculation Using Fmm and Mdgrape-3
Tarun Kumar Sheel
PIER B , 2011, DOI: 10.2528/PIERB10091804
Abstract: The present study discusses some numerical techniques on the simultaneous use of the Fast Multipole Method (FMM) and specialpurpose computer (MDGRAPE-3) to make the impractically expensive calculation feasible without the loss of numerical accuracy. In the present calculations, the impingement of two identical inclined vortex rings has been studied, and the computation time has been reduced by a factor of 1000 at =1.18 × 10 where is the number of vortex elements. The direct and MDGRAPE-3 calculations both have a scaling of , and the use of the FMM brings them both down to . The global kinetic energy, enstrophy and energy spectra have been investigated to address the numerical accuracy and have good agreement with other similar works.
Non-microsurgical breast reconstruction
Sharma Sheel,Kaplan Gordon
Indian Journal of Plastic Surgery , 2007,
Abstract: Breast reconstruction after mastectomy should aim at resulting in an aesthetic outcome that matches the patient′s expectations and without interfering in the oncologic treatment. Whether the reconstruction is performed immediately or in a delayed fashion depends on various factors, which needs detailed attention. Autologous tissue, implants or both are used in the reconstruction. This article reviews the current concepts in these, with emphasis on non-microsurgical methods of using the autologous tissue for reconstruction. Breast conservation has become an accepted practice of treatment. Reconstruction in these situations as well as in an occasion when the surgery is done for failed breast conservation is discussed in detail. The article also reviews the various methods for nipple reconstruction available.
Biocidal Silver and Silver/Titania Composite Films Grown by Chemical Vapour Deposition
D. W. Sheel,L. A. Brook,I. B. Ditta,P. Evans,H. A. Foster,A. Steele,H. M. Yates
International Journal of Photoenergy , 2008, DOI: 10.1155/2008/168185
Abstract: This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grown by thermal CVD, functionally and structurally modified by deposition of nanostructured silver via a novel flame assisted combination CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bioactivity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films are active to a range of organisms, including Gram-negative and Gram-positive bacteria, and viruses. The very high-biocidal activity is above that expected from the concentrations of silver present, and this is discussed in terms of nanostructure of the titania/silver surface. These properties are especially significant when combined with the well-known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where biocidal surface functionality is sought.
Intergenic subset organization within a set of geographically-defined viral sequences from the 2009 H1N1 influenza A pandemic  [PDF]
William A. Thompson, Joel K. Weltman
American Journal of Molecular Biology (AJMB) , 2012, DOI: 10.4236/ajmb.2012.21004
Abstract: We report a bioinformatic analysis of the datasets of sequences of all ten genes from the 2009 H1N1 influenza A pandemic in the state of Wisconsin. The gene with the greatest summed information entropy was found to be the hemagglutinin (HA) gene. Based upon the viral ID identifier of the HA gene sequence, the sequences of all of the genes were sorted into two subsets, depending upon whether the nucleotide occupying the position of maximum entropy, position 658 of the HA sequence, was either A or U. It was found that the information entropy (H) distributions of subsets differed significantly from each other, from H distributions of randomly generated subsets and from the H distributions of the complete datasets of each gene. Mutual information (MI) values facilitated identification of nine nucleotide positions, distributed over seven of the influenza genes, at which the nucleotide subsets were disjoint, or almost disjoint. Nucleotide frequencies at these nine positions were used to compute mutual information values that subsequently served as weighting factors for edges in a graph net-work. Seven of the nucleotide positions in the graph network are sites of synonymous mutations. Three of these sites of synonymous mutation are within a single gene, the M1 gene, which occupied the position of greatest graph centrality. It is proposed that these bioinformatic and network graph results may reflect alterations in M1-mediated viral packaging and exteriorization, known to be susceptible to synonymous mutations.
Speed kills: Highly relativistic spaceflight would be fatal for passengers and instruments  [PDF]
William A. Edelstein, Arthur D. Edelstein
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.410099
Abstract: Highly relativistic speeds are desirable for interstellar travel. Relativistic time dilation would reduce the subjective duration of the trip for the travelers, so that they can cover galaxy-scale distances in a reasonable amount of personal time. Unfortunately, as spaceship velocities approach the speed of light, interstellar hydrogen H, although only present at a density of approximately 1.8 atoms/cm3, turns into intense radiation that would quickly kill passengers and destroy electronic instrumentation. In addition, the energy loss of ionizing radiation passing through the ship’s hull represents an increasing heat load that necessitates large expenditures of energy to cool the ship. Stopping or diverting this flux, either with material or electromagnetic shields, is a daunting problem. Going slow to avoid severe H irradiation sets an upper speed limit of v ~ 0.5 c. This velocity only gives a time dilation factor of about 15%, which would not substantially assist galaxy-scale voyages. Diffuse interstellar H atoms are the ultimate cosmic space mines and represent a formidable obstacle to interstellar travel.
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