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Simpler
Terms modified by Simpler Selected AbstractsPerformance analysis of IDEAL algorithm for three-dimensional incompressible fluid flow and heat transfer problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2009Dong-Liang Sun Abstract Recently, an efficient segregated algorithm for incompressible fluid flow and heat transfer problems, called inner doubly iterative efficient algorithm for linked equations (IDEAL), has been proposed by the present authors. In the algorithm there exist inner doubly iterative processes for pressure equation at each iteration level, which almost completely overcome two approximations in SIMPLE algorithm. Thus, the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate and stability of solution process. However, validations have only been conducted for two-dimensional cases. In the present paper the performance of the IDEAL algorithm for three-dimensional incompressible fluid flow and heat transfer problems is analyzed and a systemic comparison is made between the algorithm and three other most widely used algorithms (SIMPLER, SIMPLEC and PISO). By the comparison of five application examples, it is found that the IDEAL algorithm is the most robust and the most efficient one among the four algorithms compared. For the five three-dimensional cases studied, when each algorithm works at its own optimal under-relaxation factor, the IDEAL algorithm can reduce the computation time by 12.9,52.7% over SIMPLER algorithm, by 45.3,73.4% over SIMPLEC algorithm and by 10.7,53.1% over PISO algorithm. Copyright © 2009 John Wiley & Sons, Ltd. [source] Scalable, Versatile and Simple Constrained Graph LayoutCOMPUTER GRAPHICS FORUM, Issue 3 2009Tim Dwyer Abstract We describe a new technique for graph layout subject to constraints. Compared to previous techniques the proposed method is much faster and scalable to much larger graphs. For a graph with n nodes, m edges and c constraints it computes incremental layout in time O(n log n+m+c) per iteration. Also, it supports a much more powerful class of constraint: inequalities or equalities over the Euclidean distance between nodes. We demonstrate the power of this technique by application to a number of diagramming conventions which previous constrained graph layout methods could not support. Further, the constraint-satisfaction method,inspired by recent work in position-based dynamics,is far simpler to implement than previous methods. [source] Implicit Surface Modelling with a Globally Regularised Basis of Compact SupportCOMPUTER GRAPHICS FORUM, Issue 3 2006C. Walder We consider the problem of constructing a globally smooth analytic function that represents a surface implicitly by way of its zero set, given sample points with surface normal vectors. The contributions of the paper include a novel means of regularising multi-scale compactly supported basis functions that leads to the desirable interpolation properties previously only associated with fully supported bases. We also provide a regularisation framework for simpler and more direct treatment of surface normals, along with a corresponding generalisation of the representer theorem lying at the core of kernel-based machine learning methods. We demonstrate the techniques on 3D problems of up to 14 million data points, as well as 4D time series data and four-dimensional interpolation between three-dimensional shapes. Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Curve, surface, solid, and object representations [source] Progressive Hulls for Intersection ApplicationsCOMPUTER GRAPHICS FORUM, Issue 2 2003Nikos Platis Abstract Progressive meshes are an established tool for triangle mesh simplification. By suitably adapting the simplification process, progressive hulls can be generated which enclose the original mesh in gradually simpler, nested meshes. We couple progressive hulls with a selective refinement framework and use them in applications involving intersection queries on the mesh. We demonstrate that selectively refinable progressive hulls considerably speed up intersection queries by efficiently locating intersection points on the mesh. Concerning the progressive hull construction, we propose a new formula for assigning edge collapse priorities that significantly accelerates the simplification process, and enhance the existing algorithm with several conditions aimed at producing higher quality hulls. Using progressive hulls has the added advantage that they can be used instead of the enclosed object when a lower resolution of display can be tolerated, thus speeding up the rendering process. ACM CSS: I.3.3 Computer Graphics,Picture/Image Generation, I.3.5 Computer Graphics,Computational Geometry and Object Modeling, I.3.7 Computer Graphics,Three-Dimensional Graphics and Realism [source] Multiple states based temporal consistency for dynamic verification of fixed-time constraints in Grid workflow systemsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 7 2007Jinjun Chen Abstract To verify fixed-time constraints in Grid workflow systems, consistency and inconsistency conditions have been defined in conventional verification work. However, with a view of the run-time uncertainty of activity completion duration, we argue that, although the conventional consistency condition is feasible, the conventional inconsistency condition is too restrictive and covers several different states. These states, which are handled conventionally by the same exception handling, should be handled differently for the purpose of cost saving. Therefore, in this paper, we divide conventional inconsistency into weak consistency, weak inconsistency and strong inconsistency and treat conventional consistency as strong consistency. Correspondingly, we develop some algorithms on how to verify them. Based on this, for weak consistency we present a method on how to adjust it to strong consistency by using mean activity time redundancy and temporal dependency between fixed-time constraints. For weak inconsistency, we analyse briefly why it can be handled by simpler and more cost-saving exception handling while for strong inconsistency, the conventional exception handling remains deployed. The final quantitative evaluation demonstrates that our research can achieve better cost-effectiveness than the conventional work. Copyright © 2006 John Wiley & Sons, Ltd. [source] OpenMP-oriented applications for distributed shared memory architecturesCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2004Ami Marowka Abstract The rapid rise of OpenMP as the preferred parallel programming paradigm for small-to-medium scale parallelism could slow unless OpenMP can show capabilities for becoming the model-of-choice for large scale high-performance parallel computing in the coming decade. The main stumbling block for the adaptation of OpenMP to distributed shared memory (DSM) machines, which are based on architectures like cc-NUMA, stems from the lack of capabilities for data placement among processors and threads for achieving data locality. The absence of such a mechanism causes remote memory accesses and inefficient cache memory use, both of which lead to poor performance. This paper presents a simple software programming approach called copy-inside,copy-back (CC) that exploits the data privatization mechanism of OpenMP for data placement and replacement. This technique enables one to distribute data manually without taking away control and flexibility from the programmer and is thus an alternative to the automat and implicit approaches. Moreover, the CC approach improves on the OpenMP-SPMD style of programming that makes the development process of an OpenMP application more structured and simpler. The CC technique was tested and analyzed using the NAS Parallel Benchmarks on SGI Origin 2000 multiprocessor machines. This study shows that OpenMP improves performance of coarse-grained parallelism, although a fast copy mechanism is essential. Copyright © 2004 John Wiley & Sons, Ltd. [source] Multicenter clinical experience with flow cytometric method for fetomaternal hemorrhage detectionCYTOMETRY, Issue 6 2002Jenn C. Chen Abstract BACKGROUND Enumeration of fetal red blood cells (RBCs) is important in the management of fetomaternal hemorrhage (FMH), particularly in situations of Rh incompatibility. METHODS We evaluated results from three institutions using the flow cytometric method (FCM) to detect fetal RBCs based on the anti-hemoglobin F (HbF) monoclonal antibody method. RESULTS During 1997,2001, 69 of 1,248 patients (5.5%) had measurable fetal erythrocytes (RBCs) in maternal blood. Only 21 patients (1.7%) had more than 30 mL of fetal blood detected in maternal blood. Of the 11 patients with large FMH and clinical follow-up, 7 had fetal demise (64%). In positive samples, significant differences were found in the fluorescence intensity (FI) of anti-HbF antibody staining between HbF-negative erythrocytes (HbF-) and adult HbF containing erythrocytes (F cells; 4 ± 0 versus 57 ± 9 linear mean channels [LMC]; P < 0.001) and between HbF-cells and fetal RBCs (4 ± 0 versus 433 ± 136 LMC; P < 0.001). In addition, significant differences were observed in forward light scatter intensity between HbF-cells and fetal RBCs (298 ± 15 versus 355 ± 68 LMC, P = 0.03). The transportability of the test is also addressed by comparing results from two other laboratories. The experience of our three laboratories, as well as the results from the recently reinitiated College of American Pathologists survey, which compares FCM and manual methods, clearly documents the superiority of the FCM test over the manual Kleihauer-Betke (KB) test. CONCLUSIONS The FCM is a simpler, more objective, and more precise alternative to the KB method in clinical testing. The high mortality rate associated with large FMH and therapeutic implications of these results should give laboratories motivation to abandon the KB method with more robust FCM to detect FMH. Cytometry (Clin. Cytometry) 50:285,290, 2002. © 2002 Wiley-Liss, Inc. [source] Behavioral discrimination of sexually dimorphic calls by male zebra finches requires an intact vocal motor pathwayDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2001David S. Vicario Abstract Vocal communication between zebra finches includes the exchange of long calls (LCs) as well as song. By using this natural call behavior and quantifying the LCs emitted in response to playbacks of LCs of other birds, we have previously shown that adult male zebra finches have a categorical preference for the LCs of females over those of males. Female LCs are acoustically simpler than male LCs, which include complex acoustic features that are learned during development. Production of these male-typical features requires an intact nucleus RA, the sexually dimorphic source of the main telencephalic projection to brainstem vocal effectors. We have now made bilateral lesions of RA in 17 adult males and tested their discrimination behavior in the call response situation. Lesioned birds continue to call, but lose the male-typical preference for female LCs. The degree of loss is correlated with the extent of RA damage. Further, the simplified LCs of males with RA lesions have a variable duration that is correlated with stimulus features. In effect, the call response behavior of lesioned males becomes like that of females. Apparently, in the absence of RA, the remaining intact structures receive different call information than RA normally does, and/or process it differently. This suggests that the vocal motor nucleus RA could play a role in the transformation of a signal encoding the salience of stimulus parameters into a control signal that modulates the probability and strength of responding. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 109,120, 2001 [source] Accelerated nervous system development contributes to behavioral efficiency in the laboratory mouse: A behavioral review and theoretical proposalDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2001Ian Q. Whishaw Abstract The emergence of the laboratory mouse as a favored species for genetic research has posed a number of problems for scientists interested in the reflection of genetic influences in mouse behavior. It is commonly thought that rat behavior, which has been studied more extensively than mouse behavior, could be easily generalized to mice. In this article, a number of categories of behavior displayed by the mouse (motor, spatial, defensive, social) are reviewed and contrasted with the same categories of behavior displayed by the rat. The comparison suggests that mouse behavior is simpler and more dependent upon elementary actions than the behavior of the rat. We suggest that the behavioral simplification in the mouse adapts it for a different ecological niche than that occupied by the rat. We propose that this simplification may be mediated by accelerated brain maturation during development. We further propose that this developmental acceleration in the mouse renders it less dependent upon complex social behavior and plastic nervous system changes associated with learning than the rat. This difference poses problems for the development of relevant methods of behavioral analysis and interpretation. Since the mouse's biological adaptations will be reflected in laboratory behavior, suggestions are made for behavioral approaches to the study and interpretation of mouse behavior. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 151,170, 2001 [source] GENERAL RULES FOR RECORDING ENDOSCOPIC FINDINGS OF ESOPHAGOGASTRIC VARICES (2ND EDITION)DIGESTIVE ENDOSCOPY, Issue 1 2010Takashi Tajiri General rules for recording endoscopic findings of esophageal varices were initially proposed in 1980 and revised in 1991. These rules have widely been used in Japan and other countries. Recently, portal hypertensive gastropathy has been recognized as a distinct histological and functional entity. Endoscopic ultrasonography can clearly depict vascular structures around the esophageal wall in patients with portal hypertension. Owing to progress in medicine, we have updated and slightly modified the former rules. The revised rules are simpler and more straightforward than the former rules and include newly recognized findings of portal hypertensive gastropathy and a new classification for endoscopic ultrasonographic findings. [source] The biology and functional morphology of Arca noae (Bivalvia: Arcidae) from the Adriatic Sea, Croatia, with a discussion on the evolution of the bivalve mantle marginACTA ZOOLOGICA, Issue 1 2008Brian Morton Abstract In the Croatian Adriatic, Arca noae occurs from the low intertidal to a depth of 60 m; it can live for > 15 years and is either solitary or forms byssally attached clumps with Modiolus barbatus. The shell is anteriorly foreshortened and posteriorly elongate. The major inhalant flow is from the posterior although a remnant anterior stream is retained. There are no anterior but huge posterior byssal retractor muscles and both anterior and posterior pedal retractors. The ctenidia are of Type B(1a) and the ctenidial,labial palp junction is Category 3. The ctenidia collect, filter and undertake the primary sorting of potential food in the inhalant water. The labial palps are small with simple re-sorting tracks on the ridges of their inner surfaces. The ciliary currents of the mantle cavity appear largely concerned with the rejection of particulate material. The mantle margin comprises an outer and an (either) inner or middle fold. The outer fold is divided into outer and inner components that secrete the shell and are photo-sensory, respectively. The latter bears a large number of pallial eyes, especially posteriorly. The inner/middle mantle fold of A. noae, possibly representative of simpler, more primitive conditions, may have differentiated into distinct folds in other recent representatives of the Bivalvia. [source] A general framework for neutral models of community dynamicsECOLOGY LETTERS, Issue 12 2009Omri Allouche Abstract Neutral models of community dynamics are a powerful tool for ecological research, but their applications are currently limited to unrealistically simple types of dynamics and ignore much of the complexity that characterize natural ecosystems. Here, we present a new analytical framework for neutral models that unifies existing models of neutral communities and extends the applicability of existing models to a much wider spectrum of ecological phenomena. The new framework extends the concept of neutrality to fitness equivalence and in spite of its simplicity explains a wide spectrum of empirical patterns of species diversity including positive, negative and unimodal productivity,diversity relationships; gradual and highly delayed declines in species diversity with habitat loss; and positive and negative responses of species diversity to habitat heterogeneity. Surprisingly, the abundance distribution in all of these cases is given by the dispersal limited multinomial (DLM), the abundance distribution in Hubbell's zero-sum model, showing DLM's robustness and demonstrating that it cannot be used to infer the underlying community dynamics. These results support the hypothesis that ecological communities are regulated by a limited set of fundamental mechanisms much simpler than could be expected from their immense complexity. Ecology Letters (2009) 12: 1287,1297 [source] A simple persistence condition for structured populationsECOLOGY LETTERS, Issue 7 2006Alan Hastings Abstract The fundamental question in both basic and applied population biology of whether a species will increase in numbers is often investigated by finding the population growth rate as the largest eigenvalue of a deterministic matrix model. For a population classified only by age, and not stage or size, a simpler biologically interpretable condition can be used, namely whether R0, the mean number of offspring per newborn, is greater than one. However, for the many populations not easily described using only age classes, stage-structured models must be used for which there is currently no quantity like R0. We determine analogous quantities that must be greater than one for persistence of a general structured population model that have a similar useful biological interpretation. Our approach can be used immediately to determine the magnitude of changes and interactions that would either allow population persistence or would ensure control of an undesirable species. [source] Amperometric Determination of Glucose at Conventional vs.ELECTROANALYSIS, Issue 12 2010Nanostructured Gold Electrodes in Neutral Solutions Abstract The conventional gold electrodes were compared with recently published electrodes based on gold nanoparticles and gold nanostructured films as amperometric sensors for glucose in pH,7.40 phosphate buffer solutions. The conventional electrodes provided similar electroanalytical benefits while required much simpler and shorter preparation. It is recommended that the future reports on the development of electrochemical sensors based on metal nanoparticles/nanostructures include also the analytical figures of merit obtained at relevant conventional metal electrodes. The voltammetric studies indicated that, in contrast to phosphate buffers, the Tris buffers were not suitable for activation of gold surface toward the direct oxidation of glucose. [source] Alkanethiols Modified Gold Electrodes for Selective Detection of Molecules with Different Polarity and Molecular Size.ELECTROANALYSIS, Issue 3-5 2009Application to Vitamin B2 Analysis Abstract The cyclic voltammetry behavior of several molecules with different polarity and molecular size on gold electrodes modified with nonfunctionalized alkanethiols of different chain length, usually employed as chromatographic stationary phases, are studied. The redox systems hexacyanoferrate(II/III), ferrocene/ferrocine and hydroquinone/quinone are chosen as template molecules. As modifiers, ethanethiol, 1-octanethiol and di- n -octadecyldisulfide are selected. We can conclude that polar molecules can reach the electrode surface through channels created by the modifiers. However, when nonpolar compounds are analyzed, the nonpolar interactions between the analyte and the terminal group of the modifier lead to retention of the compound, retarding its arrival to the electrode surface. A molecule with polar and nonpolar part was used for the application of this conclusion. If the gold electrode is modified with di- n -octadecyldisulfide, the electrochemical behavior of vitamin B2 becomes simpler than that observed on a bare one. This result allows a sensitive and selective procedure to be developed for direct determination of vitamin B2 in pharmaceutical formulations. [source] Fast Mapping of Gunshot Residues by Batch Injection Analysis with Anodic Stripping Voltammetry of Lead at the Hanging Mercury Drop ElectrodeELECTROANALYSIS, Issue 2 2005Adriana De, Donato Abstract The forensic analysis of lead in gunshot residues (GSR) sampled on the hands of potential shooters is rendered faster, simpler and less expensive by a new batch injection analysis (BIA) method, based on differential pulse anodic stripping voltammetry (DPASV). A simple "J" shaped adaptor was designed to direct the flux of the analyte injected with a micropipettor onto the hanging mercury drop electrode of any commercial electrode stand. Sampling methods for GSR were compared and lifting with adhesive tape was elected for field use. The tapes are glued on polyethylene screens and stored in capped vials. Sampling with multiple strips provides coarse mapping of the distribution of lead on the shooter's hands. After a dissolution/extraction step with chloroform/aqueous 0.10,mol,L,1 HCl, 100,,L of the aqueous phase are injected during 25,s for accumulation of lead on the HMDE at ,0.60,V (vs. Ag/AgCl). A detection limit of 20,ng/mL of Pb(II), outreaching for GSR analysis, is reached without oxygen removal, at a frequency of 20 injections per hour. Results for sequences of shootings with a revolver and a pistol are presented. [source] Targeting Chemical and Biological Warfare Agents at the Molecular LevelELECTROANALYSIS, Issue 14 2003Omowunmi Abstract After the September,11 tragedies of 2001, scientists and law-enforcement agencies have shown increasing concern that terrorist organizations and their "rogue" foreign government-backers may resort to the use of chemical and/or biological agents against U.S. military or civilian targets. In addition to the right mix of policies, including security measures, intelligence gathering and training for medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism lies in how best to respond to an attack using reliable analytical sensors. The public and regulatory agencies expect sensing methodologies and devices for homeland security to be very reliable. Quality data can only be generated by using analytical sensors that are validated and proven to be under strict design criteria, development and manufacturing controls. Electrochemical devices are ideally suited for obtaining the desired analytical information in a faster, simpler, and cheaper manner compared to traditional (lab-based) assays and hence for meeting the requirements of decentralized biodefense applications. This articler presents a review of the major trends in monitoring technologies for chemical and biological warfare (CBW) agents. It focuses on research and development of sensors (particularly electrochemical ones), discusses how advances in molecular recognition might be used to design new multimission networked sensors (MULNETS) for homeland security. Decision flow-charts for choosing particular analytical techniques for CBW agents are presented. Finally, the paths to designing sensors to meet the needs of today's measurement criteria are analyzed. [source] Manganese speciation in human cerebrospinal fluid using CZE coupled to inductively coupled plasma MSELECTROPHORESIS, Issue 9 2007Bernhard Michalke Dr. Abstract The neurotoxic effects of manganese (Mn) at elevated concentrations are well known. This raises the question, which of the Mn species can cross neural barriers and appear in cerebrospinal fluid (CSF). CSF is the last matrix in a living human organism available for analysis before a compound reaches the brain cells and therefore it is assumed to reflect best the internal exposure of brain tissue to Mn species. A previously developed CE method was modified for separation of albumin, histidine, tyrosine, cystine, fumarate, malate, inorganic Mn, oxalacetate, ,-keto-glutarate, nicotinamide-dinucleotide (NAD), citrate, adenosine, glutathione, and glutamine. These compounds are supposed in the literature to act as potential Mn carriers. In a first attempt, these compounds were analyzed by CZE-UV to check whether they are present in CSF. The CZE-UV method was simpler than the coupled CZE-inductively coupled plasma (ICP)-dynamic reaction cell (DRC)-MS method and it was therefore chosen to obtain a first overview information. In a second step, the coupled method (CZE-ICP-DRC-MS) was used to analyze, in detail, which of the compounds found in CSF by CZE-UV were actually bound to Mn. Finally, 13 Mn species were monitored in CSF samples, most of them being identified: Mn-histidine, Mn-fumarate, Mn-malate, inorganic Mn, Mn-oxalacetate, Mn-,-keto glutarate, Mn-carrying NAD, Mn-citrate and Mn-adenosine. By far the most abundant Mn species was Mn-citrate showing a concentration of 0.7,±,0.13,µg,Mn/L. Interestingly, several other Mn species can be related to the citric acid cycle. [source] Microstructure of the silk spigots of the green crab spider Oxytate striatipes (Araneae: Thomisidae)ENTOMOLOGICAL RESEARCH, Issue 3 2006Myung-Jin MOON Abstract The genus Oxytate L. Koch, 1878 comprises a homogeneous group of nocturnal crab spiders that have silk apparatuses even though they do not spin webs to trap prey. We examined the microstructure of the silk spinning apparatus of the green crab spider Oxytate striatipes, using field emission scanning electron microscopy. The silk glands of the spider were classified into three types: ampullate, pyriform and aciniform. The spigots of these three types of silk gland occur in both sexes. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pairs of minor ampullate glands supply the median spinnerets. In addition, the pyriform glands send ductules to the anterior spinnerets (45 pairs in females and 40 pairs in males), and the aciniform glands feed silk into the median (9,12 pairs in females and 7,10 pairs in males) and the posterior (30 pairs in both sexes) spinnerets. The spigot system of O. striatipes is simpler and more primitive than other wandering spiders: even the female spiders possess neither tubuliform glands for cocoon production nor triad spigots for web-building. [source] CLINICAL STUDY: The P300 event-related potential and its possible role as an endophenotype for studying substance use disorders: a reviewADDICTION BIOLOGY, Issue 3 2009Shubh M. Singh ABSTRACT The concept of endophenotypes has gained popularity in recent years. This is because of the potential that endophenotypes provide of measuring objective trait markers that are simpler to access and assess than complex behavioral disease phenotypes themselves. The simplicity, ease of measurement and the putative links to the etiology of the disease in the study of an endophenotype has the potential promise of unraveling the genetic basis of the disease in question. Of the various proposed endophenotypes, the P300 component of the event-related potential has been used in studies on alcoholism, schizophrenia and externalizing disorders. The current state of knowledge regarding the concept of endophenotypes, P300 and the validity of P300 as an endophenotype with special reference to substance use disorders is discussed in this review. The implications of the above are discussed. [source] The Reductive Elimination of Methane from ansa -Hydrido(methyl)metallocenes of Molybdenum and Tungsten: Application of Hammond's Postulate to Two-State ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2005José-Luis Carreón-Macedo Abstract The energetic profile of the methane reductive elimination from a selected number of hydrido(methyl)molybdenocene and -tungstenocene derivatives has been calculated by DFT methods. The calculations were carried out for the CH2(C5H4)2M (a -M), SiH2(C5H4)2M (a -H2Si,M), and SiMe2(C5Me4)2M (a -Me2Si,M*) ansa -metallocene systems for M = Mo, W. They include the full optimization of minima [the hydrido(methyl) starting complexes, M(H)(CH3), the intermediate methane complexes, M(CH4), and the metallocene products in the singlet and triplet configurations, (3M and 1M)], transition states (for the methyl hydride reductive elimination, M,TSins, and for the hydrogen exchange, M,TSexch), and the minimum energy crossing point (M,MECP) leading from the singlet methane complexes to the corresponding triplet metallocenes. The results are compared with those previously obtained for the simpler (C5H5)2M (Cp2M) systems (J. C. Green, J. N. Harvey, and R. Poli, J. Chem. Soc., Dalton Trans.2002, 1861). The calculated energy profiles, notably the relative energies of M,TSins and M,MECP, are in agreement with available experimental observations for the a -Me2Si,M* systems. The comparison of the energies and geometries of the rate-determining M,TSins and M,MECP structures with those of the thermodynamically relevant minima for the various systems show the applicability of Hammond's postulate to two-state reactions. However, one notable exception serves to show that the principle is only quantitatively reliable when all the potential energy surfaces for the set of analogous reactions have similar shapes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Effect of organic matter applications on 13C-NMR spectra of humic acids of soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2008S. Dou Summary Much attention has been paid to improving soil fertility with organic matter (OM) application, which not only deals with organic wastes and protects the environment, but also maintains soil fertility and increases crop yields. Much research has also been on the effects of OM applications on the soil's physical, chemical and biological properties, but relatively less attention has been spent on humic substance (HS). In order to clarify the mechanism of improving soil fertility by applying OM, we analysed the changes of structural characteristics of humic acid (HA) from OM applications to soils by 13C-NMR, chemical analysis, thermal analysis, optical properties, IR and fluorescence spectroscopy. Samples of a brown soil (Paleudalf) and a paddy soil (an anthropogenic soil originating from Udifluvents) were collected from the plough layer of the long-term field experiment at Shenyang Agricultural University and Liaoning Provincial Alkali-Saline Soil Institute, respectively. Both field experiments included three treatments each: (i) brown soil, zero-treatment (CKbr) and two pig manure (PM) applications (O1 and O2) at annual rates of 0.9 t ha,1 and 1.8 t ha,1 of organic carbon, respectively; and (ii) paddy soil, zero-treatment (CKpad), pig manure (Op) and rice straw (Or) at annual rates of 2.62 t ha,1 and 1.43 t ha,1 of organic carbon, respectively. An incubation experiment was also carried out to test the field experiment on the brown soil, namely four treatments: zero-treatment (CKc), and three pig manure applications at rates of 30 g kg,1 (C1), 50 g kg,1 (C2) and 70 g kg,1 (C3), respectively. The total incubation was 180 days. The results indicated that number-average molecular weights (Mn), total acidity, aromaticity, excitation maximum wavelength (,Exmax), and the heat ratio of the high to moderate temperature exothermic regions (H3/H2) of the HA all decreased after OM application. The degree of activation (AD), the absorption intensity ratio of 2920 cm,1 to 1720 cm,1 in infrared spectra (IR2920/1720), alkyl C and O-alkyl C of the HA increased. The HA structure tended to become simpler and more aliphatic. [source] Recognition of resonance in long radial transmission lines with static VAR compensation using travelling wavesEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2005Ljubivoje M. Popovi Abstract This paper presents an analytical procedure for estimation of resonance frequencies in long-distance radial transmission lines with static VAR compensation. The development of the procedure is based on a new approach in solving this problem. It employs the fact that the phenomenon is characterized by an algebraic sum of travelling current waves at the beginning of the line. Relatively simple analytical expressions are obtained by considering the phase angles of only one direct and only one corresponding reflected wave. Besides enabling a simpler and faster solution of the problem under various realistic conditions, the obtained analytical expressions also offer more direct analytical insight into the interplay of basic parameters. Copyright © 2005 John Wiley & Sons, Ltd. [source] Analysis of the NADH-dependent retinaldehyde reductase activity of amphioxus retinol dehydrogenase enzymes enhances our understanding of the evolution of the retinol dehydrogenase familyFEBS JOURNAL, Issue 14 2007Diana Dalfó In vertebrates, multiple microsomal retinol dehydrogenases are involved in reversible retinol/retinal interconversion, thereby controlling retinoid metabolism and retinoic acid availability. The physiologic functions of these enzymes are not, however, fully understood, as each vertebrate form has several, usually overlapping, biochemical roles. Within this context, amphioxus, a group of chordates that are simpler, at both the functional and genomic levels, than vertebrates, provides a suitable evolutionary model for comparative studies of retinol dehydrogenase enzymes. In a previous study, we identified two amphioxus enzymes, Branchiostoma floridae retinol dehydrogenase 1 and retinol dehydrogenase 2, both candidates to be the cephalochordate orthologs of the vertebrate retinol dehydrogenase enzymes. We have now proceeded to characterize these amphioxus enzymes. Kinetic studies have revealed that retinol dehydrogenase 1 and retinol dehydrogenase 2 are microsomal proteins that catalyze the reduction of all- trans -retinaldehyde using NADH as cofactor, a remarkable combination of substrate and cofactor preferences. Moreover, evolutionary analysis, including the amphioxus sequences, indicates that Rdh genes were extensively duplicated after cephalochordate divergence, leading to the gene cluster organization found in several mammalian species. Overall, our data provide an evolutionary reference with which to better understand the origin, activity and evolution of retinol dehydrogenase enzymes. [source] Peptides corresponding to helices 5 and 6 of Bax can independently form large lipid poresFEBS JOURNAL, Issue 5 2006Ana J. García-Sáez Proteins of the B-cell lymphoma protein 2 (Bcl2) family are key regulators of the apoptotic cascade, controlling the release of apoptotic factors from the mitochondrial intermembrane space. A helical hairpin found in the core of water-soluble folds of these proteins has been reported to be the pore-forming domain. Here we show that peptides including any of the two ,-helix fragments of the hairpin of Bcl2 associated protein X (Bax) can independently induce release of large labelled dextrans from synthetic lipid vesicles. The permeability promoted by these peptides is influenced by intrinsic monolayer curvature and accompanied by fast transbilayer redistribution of lipids, supporting a toroidal pore mechanism as in the case of the full-length protein. However, compared with the pores made by complete Bax, the pores made by the Bax peptides are smaller and do not need the concerted action of tBid. These data indicate that the sequences of both fragments of the hairpin contain the principal physicochemical requirements for pore formation, showing a parallel between the permeabilization mechanism of a complex regulated protein system, such as Bax, and the much simpler pore-forming antibiotic peptides. [source] Examples of fire engineering design for steel members, using a standard curve versus a new parametric curveFIRE AND MATERIALS, Issue 2-4 2004C. R. Barnett Abstract This paper presents examples of the differences that can occur when a standard time-temperature curve and a parametric time-temperature curve are used to determine temperatures likely to be reached by uninsulated and insulated steel members during a fire. For low and moderate structural fire severity situations, determination of the adequacy of a steel member by comparing the temperature reached in a ,design fire' with the limiting temperature based on the member heat sink characteristics, extent of insulation and utilization factor is becoming increasingly common fire engineering design practice. For this it is important to have an accurate and widely applicable parametric fire model as is practicable. The standard time-temperature curve used in the examples is the ISO 834 curve. The two parametric time-temperature curves used in the paper are the Eurocode parametric curve and a recently developed one termed the ,BFD curve'. The latter has been found to fit the results of a wide range of actual fire tests more closely than do existing parametric curves and is mathematically simpler in form. The shape of the BFD curve and the parameters used to define it bear a strong relationship to both the pyrolysis coefficient (R/Avhv0.5) and the opening factor, F02. The curve also models the development of fire without the need for time shifts. It uses a single and relatively simple equation to generate the temperature of both the growth and decay phases of a fire in a building and only three factors are required to derive the curve. These factors are (i) the maximum gas temperature, (ii) the time at which this maximum temperature occurs, and (iii) a shape constant for the curve. If desired, the shape constant can be different on the growth and the decay sides to model a very wide range of natural fire conditions and test results. This paper presents an overview of the background to the BFD curve. It then illustrates its use in a simple fire engineering design application, where the adequacy of a steel beam is checked using the Eurocode parametric curve and the BFD curve to represent the fire. Copyright © 2004 John Wiley & Sons, Ltd. [source] Experimental quantum secret sharingFORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 8-10 2006Ch. Schmid Abstract We consider two simple and practical protocols for multiparty communication and show their experimental realization. These protocols deal with the task of secret sharing in which a secret message is split among several parties in a way that its reconstruction requires their mutual collaboration. In the presented schemes the parties solve the problem by two different approaches: The first uses as a resource the multiqubit entangled state |,4 - ,. As no interferometric setups are required here, contrary to known schemes, involving Greenberger-Horne-Zeilinger states, its implementation is simpler and more stable. In the second scheme only sequential transformations on a single qubit are used. This further tremendously simplifies the method, makes it scalable with regard to the number of participating partners and above all, technologically comparable to quantum key distribution. [source] Simplified algorithms for calculating double-couple rotationGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2007Yan Y. Kagan SUMMARY We derive new, simplified formulae for evaluating the 3-D angle of earthquake double-couple (DC) rotation. The complexity of the derived equations depends on both accuracy requirements for angle evaluation and the completeness of desired solutions. The solutions are simpler than my previously proposed algorithm based on the quaternion representation designed in 1991. We discuss advantages and disadvantages of both approaches. These new expressions can be written in a few lines of computer code and used to compare both DC solutions obtained by different methods and variations of earthquake focal mechanisms in space and time. [source] Unification of single-configuration seismic imaging processesGEOPHYSICAL PROSPECTING, Issue 2 2008H. Jaramillo ABSTRACT In this paper we derive an integral formula that encompasses all linear processes on seismic data. These include migration, demigration and residual migration, as well as data mapping procedures such as transformation to zero offset, inverse transformation to zero offset, residual transformation to zero offset and offset continuation. The derivation of the equation is different from all previous approaches to unification. Here we do not use a cascaded operation between two operators, but rather the superposition principle. In this regard, the derivation is not only more fundamental, but also simpler and more general. We study the kinematics and the dynamics of these processes and show that the signals can be reconstructed asymptotically either by finding the envelope of particular surfaces or by stacking energy along "adjoint" surfaces. For example, in the case of migration, the first set of surfaces are isochrons, while the "adjoint" surfaces are diffraction responses. In practice, the distinction between these two types of surfaces is equivalent to choosing the order of the computational loops with regard to the input and output seismic traces. [source] Hydrogeologic unit flow characterization using transition probability geostatisticsGROUND WATER, Issue 2 2005Norman L. Jones This paper describes a technique for applying the transition probability geostatistics method for stochastic simulation to a MODFLOW model. Transition probability geostatistics has some advantages over traditional indicator kriging methods including a simpler and more intuitive framework for interpreting geologic relationships and the ability to simulate juxtapositional tendencies such as fining upward sequences. The indicator arrays generated by the transition probability simulation are converted to layer elevation and thickness arrays for use with the new Hydrogeologic Unit Flow package in MODFLOW 2000. This makes it possible to preserve complex heterogeneity while using reasonably sized grids and/or grids with nonuniform cell thicknesses. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||