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Simple Modifications (simple + modifications)
Selected AbstractsSimple modifications for stabilization of the finite point methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2005B. Boroomand Abstract A stabilized version of the finite point method (FPM) is presented. A source of instability due to the evaluation of the base function using a least square procedure is discussed. A suitable mapping is proposed and employed to eliminate the ill-conditioning effect due to directional arrangement of the points. A step by step algorithm is given for finding the local rotated axes and the dimensions of the cloud using local average spacing and inertia moments of the points distribution. It is shown that the conventional version of FPM may lead to wrong results when the proposed mapping algorithm is not used. It is shown that another source for instability and non-monotonic convergence rate in collocation methods lies in the treatment of Neumann boundary conditions. Unlike the conventional FPM, in this work the Neumann boundary conditions and the equilibrium equations appear simultaneously in a weight equation similar to that of weighted residual methods. The stabilization procedure may be considered as an interpretation of the finite calculus (FIC) method. The main difference between the two stabilization procedures lies in choosing the characteristic length in FIC and the weight of the boundary residual in the proposed method. The new approach also provides a unique definition for the sign of the stabilization terms. The reasons for using stabilization terms only at the boundaries is discussed and the two methods are compared. Several numerical examples are presented to demonstrate the performance and convergence of the proposed methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] In Vitro synthesis and activity of reporter proteins in an Escherichia coli S30 extract system: An undergraduate experiment,BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 6 2005Pamela J. Higgins Abstract This undergraduate laboratory experiment integrates multiple techniques (in vitro synthesis, enzyme assays, Western blotting) to determine the production and detection sensitivity of two common reporter proteins (,-galactosidase and luciferase) within an Escherichia coli S30 transcription/translation extract. Comparison of the data suggests that luciferase is the more suitable reporter for this specific in vitro extract system. Simple modifications in the experimental design allow for flexibility in the use of materials and the time required to perform the study. Furthermore, extension into additional experiments and alternative techniques are also discussed. [source] Dichloro-Bis(aminophosphine) Complexes of Palladium: Highly Convenient, Reliable and Extremely Active Suzuki,Miyaura Catalysts with Excellent Functional Group ToleranceCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010Jeanne Abstract Dichloro-bis(aminophosphine) complexes are stable depot forms of palladium nanoparticles and have proved to be excellent Suzuki,Miyaura catalysts. Simple modifications of the ligand (and/or the addition of water to the reaction mixture) have allowed their formation to be controlled. Dichlorobis[1-(dicyclohexylphosphanyl)piperidine]palladium (3), the most active catalyst of the investigated systems, is a highly convenient, reliable, and extremely active Suzuki catalyst with excellent functional group tolerance that enables the quantitative coupling of a wide variety of activated, nonactivated, and deactivated and/or sterically hindered functionalized and heterocyclic aryl and benzyl bromides with only a slight excess (1.1,1.2,equiv) of arylboronic acid at 80,°C in the presence of 0.2,mol,% of the catalyst in technical grade toluene in flasks open to the air. Conversions of >95,% were generally achieved within only a few minutes. The reaction protocol presented herein is universally applicable. Side-products have only rarely been detected. The catalytic activities of the aminophosphine-based systems were found to be dramatically improved compared with their phosphine analogue as a result of significantly faster palladium nanoparticle formation. The decomposition products of the catalysts are dicyclohexylphosphinate, cyclohexylphosphonate, and phosphate, which can easily be separated from the coupling products, a great advantage when compared with non-water-soluble phosphine-based systems. [source] Seeking a second opinion: uncertainty in disease ecologyECOLOGY LETTERS, Issue 6 2010Brett T. McClintock Ecology Letters (2010) 13: 659,674 Abstract Analytical methods accounting for imperfect detection are often used to facilitate reliable inference in population and community ecology. We contend that similar approaches are needed in disease ecology because these complicated systems are inherently difficult to observe without error. For example, wildlife disease studies often designate individuals, populations, or spatial units to states (e.g., susceptible, infected, post-infected), but the uncertainty associated with these state assignments remains largely ignored or unaccounted for. We demonstrate how recent developments incorporating observation error through repeated sampling extend quite naturally to hierarchical spatial models of disease effects, prevalence, and dynamics in natural systems. A highly pathogenic strain of avian influenza virus in migratory waterfowl and a pathogenic fungus recently implicated in the global loss of amphibian biodiversity are used as motivating examples. Both show that relatively simple modifications to study designs can greatly improve our understanding of complex spatio-temporal disease dynamics by rigorously accounting for uncertainty at each level of the hierarchy. [source] Mixed biodiversity benefits of agri-environment schemes in five European countriesECOLOGY LETTERS, Issue 3 2006D. Kleijn Abstract Agri-environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non-ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri-environment schemes and use it to evaluate the biodiversity effects of agri-environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri-environment scheme, the other conventionally managed. In all countries, agri-environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri-environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures. [source] Synthesis and Modulation of Bis(triazine) Hydrogen-Bonding ReceptorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Pamela V. Mason Abstract The synthesis of bis(triazine) molecules capable of acting as synthetic receptors for barbiturate guest molecules is described. The binding properties are also reported illustrating the modulation of the binding properties of these species by the modification of the hydrogen-bonding patterns of the receptor molecule, namely 1,3- N,N, -bis[4-(dibenzylamino)-6-(butylamino)-1,3,5-triazin-2-yl]xylylenediamine (1). Thus 1,3- O,O, -bis[4-(dibenzylamino)-6-(butylamino)-1,3,5-triazin-2-yl]benzenedimethanol (3) and 1,3- O,O, -bis[4-(dibenzylamino)-6-(diethylamino)-1,3,5-triazin-2-yl]benzenedimethanol (5) have been prepared, and their binding constants compared to those observed for 1. In the case of compounds 3 and 5 the hydrogen-bonding secondary amines at the apex of the receptor 1 are substituted by non-hydrogen-bonding ether links. The hydrogen-bonding ability is further modified in the case of 5 by the removal of all hydrogen-bond donors from the receptor site, replacing secondary amines by tertiary amines. NMR binding studies illustrate how these simple modifications of the hydrogen-bonding patterns of these receptors influences the overall strength of binding demonstrating a simple mechanism for controlling host-guest complex formation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Serological response to hepatitis E virus genotype 3 infection: IgG quantitation, avidity, and IgM responseJOURNAL OF MEDICAL VIROLOGY, Issue 1 2008R. Bendall Abstract Sequential sera were collected from 18 acute cases of UK-acquired hepatitis E. The virus strains in all cases were of genotype 3. The IgM and IgG response to acute infection were documented over time using EIA kits based on a peptide antigen, pE2, which is derived from a genotype 1 strain of hepatitis E virus (HEV). Ninety-five percentage of acute sera were IgM positive; after 6 months or more only 12% remained positive. The kit was adapted to quantify the IgG response (in WHO U/ml) and to determine antibody avidity. Following acute infection, anti-HEV IgG concentrations rose between 6.9- and 90-fold. IgG avidity was low (<25%) in most acute sera. After 6 months IgG avidity was greater than 50% in all cases. One patient with a poor IgM response and high avidity antibody in acute sera may have had a second HEV infection. Taken together, these results confirm that the pE2-based EIA kits are suitable for diagnosing acute HEV genotype 3 infection. With simple modifications the IgG kit can measure anti-HEV concentration and avidity, which can be used to confirm acute infection. J. Med. Virol. 80:95,101, 2008. © 2007 Wiley-Liss, Inc. [source] A POST-KEYNESIAN AMENDMENT TO THE NEW CONSENSUS ON MONETARY POLICYMETROECONOMICA, Issue 2 2006Article first published online: 24 APR 200, Marc Lavoie ABSTRACT A common view is now pervasive in policy research at universities and central banks, which one could call the New Keynesian consensus, based on an endogenous money supply. This new consensus reproduces received wisdom: in the long run, expansionary fiscal policy leads to higher inflation rates and real interest rates, while more restrictive monetary policy only leads to lower inflation rates. The paper provides a simple four-quadrant apparatus to represent the above, and it shows that simple modifications to the new consensus model are enough to radically modify received doctrine as to the likely effects of fiscal and monetary policies. [source] Structural,functional Aspects in the Evolution of Operculate Corals (Rugosa)PALAEONTOLOGY, Issue 4 2002Michael Gudo Among the Rugosa operculae were developed by only a few genera. One is the slipper,shaped Calceola and another is the pyramidal shaped Goniophyllum. On the basis of biological and morphological knowledge of recent corals, the two different bauplans of the soft bodies of Calceola and Goniophyllum have been reconstructed. The soft body (i.e. the polyp) of a rugose coral is thought to have all the basic structures of anthozoan polyps: a barrel,like body shape, a flat oral disc with tentacles, and a mouth from which a pharynx reaches inside the gastric cavity. Furthermore, as in all Anthozoa, Rugosa had internal mesenteries that act as tensile cords; during growth in the diameter further mesenteries were inserted. In contrast to all other Anthozoa, in the Rugosa new single mesenteries were added in four insertion sectors. The bauplans of Calceola and Goniophyllum differ in the pattern of mesentery insertion into these four sectors. Calceola had a serial insertion pattern and Goniophyllum had a symmetrical insertion pattern. They are representatives of the two different bauplans within the Rugosa. The lid corals are examples of convergent evolved genera; Calceola as well as Goniophyllum originated by quite simple modifications of the ancestral type. The peculiar shapes, the operculae and especially the straight hinges between the calyx and the lid(s) result only from mechanical necessity. Under special conditions (such as high sedimentation rates) these modifications of the corallites represent suitable tactics for survival. [source] Stabilization of glucose oxidase in alginate microspheres with photoreactive diazoresin nanofilm coatingsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2005Rohit Srivastava Abstract The nanoassembly and photo-crosslinking of diazo-resin (DAR) coatings on small alginate microspheres for stable enzyme entrapment is described. Multilayer nanofilms of DAR with poly(styrene sulfonate) (PSS) were used in an effort to stabilize the encapsulation of glucose oxidase enzyme for biosensor applications. The activity and physical encapsulation of the trapped enzyme were measured over 24 weeks to compare the effectiveness of nanofilm coatings and crosslinking for stabilization. Uncoated spheres exhibited rapid loss of activity, retaining only 20% of initial activity after one week, and a dramatic reduction in effective activity over 24 weeks, whereas the uncrosslinked and crosslinked {DAR/PSS}-coated spheres retained more than 50% of their initial activity after 4 weeks, which remained stable even after 24 weeks for the two and three bilayer films. Nanofilms comprising more polyelectrolyte layers maintained higher overall activity compared to films of the same composition but fewer layers, and crosslinking the films increased retention of activity over uncrosslinked films after 24 weeks. These findings demonstrate that enzyme immobilization and stabilization can be achieved by using simple modifications to the layer-by-layer self-assembly technique. © 2005 Wiley Periodicals, Inc. [source] | |||||||||||||