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Secondary Peak (secondary + peak)
Selected AbstractsFlow reversal over a natural pool,riffle sequence: a computational studyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2003Zhixian Cao Abstract A computational study is presented on the hydraulics of a natural pool,rif,e sequence composed of mixed cobbles, pebbles and sand in the River Lune, northern England. A depth-averaged two-dimensional numerical model is employed, calibrated with observed data at the ,eld site. From the computational outputs, the occurrence of longitudinally double peak zones of bed shear stress and velocity is found. In particular, at low discharge there exists a primary peak zone of bed shear stress and velocity at the rif,e tail in line with the local maximum energy slope, in addition to a secondary peak at the pool head. As discharge increases, the primary peak at the rif,e tail at low ,ow moves toward the upstream side of the rif,e along with the maximum energy slope, showing progressive equalization to the surrounding hydraulic pro,les. Concurrently, the secondary peak, due to channel constriction, appears to stand at the pool head, with its value increasing with discharge and approaching or exceeding the primary peak over the rif,e. The existence of ,ow reversal is demonstrated for this speci,c case, which is attributable to channel constriction at the pool head. A dynamic equilibrium model is presented to reconstruct the pool,rif,e morphology. A series of numerical modelling exercises demonstrates that the pool,rif,e morphology is more likely produced by shallow ,ows concentrated with coarse sediments than deep ,ows laden with low concentrations of ,ne sediments. It is concluded that channel constriction can, but may not necessarily, lead to competence reversal, depending on channel geometry, ,ow discharge and sediment properties. Copyright © 2003 John Wiley & Sons, Ltd. [source] First-order reversal curve diagrams and thermal relaxation effects in magnetic particlesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2001Christopher R. Pike Summary We have recently developed a technique for characterizing the magnetic components within natural particle assemblages. This technique is based on the transformation of magnetization data from first-order reversal curves (FORCs) into contour plots of a 2-D distribution function (FORC diagrams). FORC diagrams are useful for obtaining information about switching fields and interactions in magnetic particle systems. Here, we examine experimental data and a theoretical model in order to provide a rigorous framework for interpreting FORC diagrams for samples that contain superparamagnetic particles. We have found four distinct manifestations of thermal relaxation on FORC diagrams. First, thermal relaxation will shift the FORC distribution to lower coercivities. Second, at intermediate temperatures, thermal relaxation can generate a secondary peak about the origin of a FORC diagram. This secondary peak indicates that part of a single-domain particle assemblage has become superparamagnetic. At high enough temperatures, the primary peak of the FORC distribution will be located about the origin of a FORC diagram. Third, thermal relaxation can produce a small, but systematic, upward shift of a FORC distribution. Fourth, thermal relaxation will produce contours that lie near and parallel to the vertical axis in the lower quadrant of a FORC diagram. These manifestations make FORC diagrams a powerful tool for studying the effects of thermal relaxation (superparamagnetism) in bulk natural samples, particularly when the samples contain mixed magnetic particle assemblages. [source] Clenbuterol in the horse: urinary concentrations determined by ELISA and GC/MS after clinical dosesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2001J. D. Harkins Clenbuterol is a ,2 agonist/antagonist bronchodilator marketed as Ventipulmin® and is the only member of this group of drugs approved by the US Food and Drug Administration (FDA) for use in horses. Clenbuterol is a class 3 drug in the Association of Racing Commissioners International (ARCI) classification system; therefore, its identification in postrace samples may lead to sanctions. Recently, the sensitivity of postrace testing for clenbuterol has been substantially increased. The objective of this study was to determine the ,detection times' for clenbuterol after administration of an oral clinical dose (0.8 g/kg, b.i.d.) of Ventipulmin syrup. Five horses received oral clenbuterol (0.8 g/kg, b.i.d.) for 10 days, and urine concentrations of clenbuterol were determined by an enhanced enzyme-linked immunoabsorbent assay (ELISA) test and gas chromatography/mass spectrometric (GC/MS) analysis by two different methods for 30 days after administration. Twenty-four hours after the last administration, urine concentrations of apparent clenbuterol, as measured by ELISA, averaged about 500 ng/mL, dropping to about 1 ng/mL by day 5 posttreatment. However, there was a later transient increase in the mean concentrations of apparent clenbuterol in urine, peaking at 7 ng/mL on day 10 postadministration. The urine samples were also analysed using mass spectral quantification of both the trimethylsilyl (TMS) and methane boronic acid (MBA) derivatives of clenbuterol. Analysis using the TMS method showed that, at 24 h after the last administration, the mean concentration of recovered clenbuterol was about 22 ng/mL. Thereafter, clenbuterol concentrations fell below the limit of detection of the TMS-method by day 5 after administration but became transiently detectable again at day 10, with a mean concentration of about 1 ng/mL. Derivatization with MBA offers significant advantages over TMS for the mass spectral detection of clenbuterol, primarily because MBA derivatization yields a high molecular weight base peak of 243 m/z, which is ideal for quantitative purposes. Therefore, mass spectral analyses of selected urine samples, including the transient peak on day 10, were repeated using MBA derivatization, and comparable results were obtained. The results show that clenbuterol was undetectable in horse urine by day 5 after administration. However, an unexpected secondary peak of clenbuterol was observed at day 10 after administration that averaged ,1 ng/mL. Because of this secondary peak, the detection time for clenbuterol (0.8 g/kg, b.i.d. × 10 days) is at least 11 days if the threshold for detection is set at 1 ng/mL. [source] Unified description of collective modes in superconductors and semiconductors with an exciton condensed phasePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2010Z. G. Koinov Abstract It is shown that the Bethe,Salpeter approach, the Bardeen, Cooper, and Schrieffer (BCS) based vertex method, and a generalized random-phase approximation (GRPA) to the many-electron problem in the presence of a condensed quantum phase yield the same theoretical excitation spectrum to collective modes. This spectrum reveals a secondary peak in optical absorption in semiconductors that can be understood as signaling the existence of an excitonic Bose,Einstein condensate (BEC). The analysis shows as well that there is an additional, non-trivial linearly-dispersive " moving" Cooper-pair solution for superconductors in both weak and strong coupling. [source] Striated muscle and nerve fascicle distribution in the female raturethral sphincterTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2007Ronald J. Kim Abstract The anatomical basis for urinary continence depends on a thorough understanding of the tissues in the urethra. The objective of this study was to evaluate the morphology and neuroanatomy of urethral striated muscle, called the rhabdosphincter or external urethral sphincter, in normal female rats. Urethras from 12 female rats were dissected from the bladder, fixed, embedded in paraffin or epon, and sectioned every 1 mm. Striated muscle content was taken as the ratio of the striated muscle area to net urethral area. Nerve fascicles containing myelinated axons near the rhabdosphincter were counted and mapped. Both striated muscle content and number of nerve fascicles peak in the proximal third of the urethra, with a secondary peak at the distal end of the urethra. This secondary peak may correspond to an analog of the combined compressor urethrae/urethrovaginal sphincter located in the distal urethra in human. The rhabdosphincter has a variable distribution along the length of the urethra. In the middle and distal thirds of the urethra, the dorsal striated muscle fibers between the urethra and vagina become more sparse. The majority of nerve fascicles are contained in the lateral quadrants of the urethra, similar to the lateral distribution of somatic nerves in humans. In conclusion, this study demonstrates the normal distribution of the striated musculature and neuroanatomy in the urethra, with similarities to the human. It thus supports and extends the usefulness of the rat as an experimental model for studying urinary incontinence. Anat Rec 290:145,154, 2007. © 2007 Wiley-Liss, Inc. [source] Compressed sensing for next generation instrumentsASTRONOMISCHE NACHRICHTEN, Issue 6 2010A. Asensio Ramos Abstract This document discusses the possibility of using compressed sensing techniques for measuring 2D spectro-polarimetric information using only one etalon and a broad prefilter. Instead of using an etalon and an extremely narrow prefilter (with all the subsequent problems of alignment), the idea is to use multiplexing techniques to include in the observations all the secondary peaks of the etalon. The reconstruction of the signal is done under the assumption that it can be efficiently reproduced in an orthogonal basis set (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A simple pharmacokinetics subroutine for modeling double peak phenomenonBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2006Ahmad Mirfazaelian Abstract Double peak absorption has been described with several orally administered drugs. Numerous reasons have been implicated in causing the double peak. DRUG-KNT,a pharmacokinetic software developed previously for fitting one and two compartment kinetics using the iterative curve stripping method,was modified and a revised subroutine was incorporated to solve double-peak models. This subroutine considers the double peak as two hypothetical doses administered with a time gap. The fitting capability of the presented model was verified using four sets of data showing double peak profiles extracted from the literature (piroxicam, ranitidine, phenazopyridine and talinolol). Visual inspection and statistical diagnostics showed that the present algorithm provided adequate curve fit disregarding the mechanism involved in the emergence of the secondary peaks. Statistical diagnostic parameters (RSS, AIC and R2) generally showed good fitness in the plasma profile prediction by this model. It was concluded that the algorithm presented herein provides adequate predicted curves in cases of the double peak phenomenon. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||||||||