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Appropriate Conditions (appropriate + condition)
Selected AbstractsWHO'S AFRAID OF THE MARSHALL-LERNER CONDITION?ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 4 2005Gordon D. Menzies The Marshall-Lerner condition,that the sum of the elasticities of import and export demand exceeds unity,has been put forward as a condition that is required for a depreciation to make the trade balance more positive. Based on recently estimated trade equations, the more appropriate condition for Australia is that the sum of the import elasticity of demand and the elasticity of the export price with respect to the exchange rate exceeds unity. I call this the Small Economy Marshall,Lerner (SEML) condition. In recent history, this condition was fulfilled in 1999,2001, when the (unstable) relationship between the terms of trade and the exchange rate broke down. [source] Sampling methods for phlebotomine sandfliesMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2000B. Alexander Summary A review is presented of methods for sampling phlebotomine sandflies (Diptera: Psychodidae). Among ,500 species of Phlebotominae so far described, mostly in the New World genus Lutzomyia and the Old World genus Phlebotomus, about 10% are known vectors of Leishmania parasites or other pathogens. Despite being small and fragile, sandflies have a wide geographical range with species occupying a considerable diversity of ecotopes and habitats, from deserts to humid forests, so that suitable methods for collecting them are influenced by environmental conditions where they are sought. Because immature phlebotomines occupy obscure terrestrial habitats, it is difficult to find their breeding sites. Therefore, most trapping methods and sampling procedures focus on sandfly adults, whether resting or active. The diurnal resting sites of adult sandflies include tree holes, buttress roots, rock crevices, houses, animal shelters and burrows, from which they may be aspirated directly or trapped after being disturbed. Sandflies can be collected during their periods of activity by interception traps, or by using attractants such as bait animals, CO2 or light. The method of trapping used should: (a) be suited to the habitat and area to be surveyed, (b) take into account the segment of the sandfly population to be sampled (species, sex and reproduction condition) and (c) yield specimens of appropriate condition for the study objectives (e.g. identification of species present, population genetics or vector implication). Methods for preservation and transportation of sandflies to the laboratory also depend on the objectives of a particular study and are described accordingly. [source] AUTONOMY AND AUTHENTICITY OF ENHANCED PERSONALITY TRAITSBIOETHICS, Issue 6 2009JAN CHRISTOPH BUBLITZ ABSTRACT There is concern that the use of neuroenhancements to alter character traits undermines consumer's authenticity. But the meaning, scope and value of authenticity remain vague. However, the majority of contemporary autonomy accounts ground individual autonomy on a notion of authenticity. So if neuroenhancements diminish an agent's authenticity, they may undermine his autonomy. This paper clarifies the relation between autonomy, authenticity and possible threats by neuroenhancements. We present six neuroenhancement scenarios and analyse how autonomy accounts evaluate them. Some cases are considered differently by criminal courts; we demonstrate where academic autonomy theories and legal reasoning diverge and ascertain whether courts should reconsider their concept of autonomy. We argue that authenticity is not an appropriate condition for autonomy and that new enhancement technologies pose no unique threats to personal autonomy. [source] Sheath Physics and Boundary Conditions for Edge PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004R. H. Cohen Abstract The boundary conditions of mass, momentum, energy, and charge appropriate for fluid formulations of edge plasmas are surveyed. We re-visit the classic problem of 1-dimensional flow, and note that the "Bohm sheath criterion" is requirement of connectivity of the interior plasma with the external world, not the result of termination of the plasma by a wall. We show that the nature of the interior plasma solution is intrinsically different for ion sources that inject above and below the electron sound speed. We survey the appropriate conditions to apply, and resultant fluxes, for a magnetic field obliquely incident on a wall, including the presence of drifts and radial transport. We discuss the consequences of toroidal asymmetries in wall properties, as well as experimental tests of such effects. Finally, we discuss boundary-condition modifications in the case of rapidly varying plasma conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed ReactorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006M. Ergezinger Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source] Thresholds of Response in Nest Thermoregulation by Worker Bumble Bees, Bombus bifarius nearcticus (Hymenoptera: Apidae)ETHOLOGY, Issue 5 2001Sean O'Donnell Regulation of nest temperature is important to the fitness of eusocial insect colonies. To maintain appropriate conditions for the developing brood, workers must exhibit thermoregulatory responses to ambient temperature. Because nest-mate workers differ in task performance, thermoregulatory behavior provides an opportunity to test threshold of response models for the regulation of division of labor. We found that worker bumble bees (Bombus bifarius nearcticus) responded to changes in ambient temperature by altering their rates of performing two tasks , wing fanning and brood cell incubation. At the colony level, the rate of incubating decreased, and the rate of fanning increased, with increasing temperature. Changes in the number of workers performing these tasks were more important to the colony response than changes in workers' task performance rates. At the individual level, workers' lifetime rates of incubation and fanning were positively correlated, and most individuals did not specialize exclusively on either of these temperature-sensitive tasks. However, workers differed in the maximum temperature at which they incubated and in the minimum temperature at which they fanned. More individuals fanned at high and incubated at low temperatures. Most of the workers that began incubating at higher temperatures continued performing this task at lower temperatures, when additional nest-mates became active. The converse was true for fanning behavior. These data are consistent with a threshold of response model for thermoregulatory behavior of B. bifarius workers. [source] Breakpoints in immunoregulation required for Th1 cells to induce diabetesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2006Margaret Neighbors Abstract We describe a novel TCR-transgenic mouse line, TCR7, where MHC class,II-restricted, CD4+ T cells are specific for the subdominant H-2b epitope (HEL74,88) of hen egg lysozyme (HEL), and displayed an increased frequency in the thymus and in peripheral lymphoid compartments over that seen in non-transgenic littermate controls. CD4+ T cells responded vigorously to HEL or HEL74,88 epitope presented on APC and could develop into Th1 or Th2 cells under appropriate conditions. Adoptive transfer of TCR7 Ly5.1 T cells into Ly5.2 rat insulin promoter (RIP)-HEL transgenic recipient hosts did not lead to expansion of these cells or result in islet infiltration, although these TCR7 cells could expand upon transfer into mice expressing high levels of HEL in the serum. Islet cell infiltration only occurred when the TCR7 cells had been polarized to either a Th1 or Th2 phenotype prior to transfer, which led to insulitis. Progression from insulitis to autoimmune diabetes only occurred in these recipients when Th1 but not Th2 TCR7 cells were transferred and CTLA-4 signaling was simultaneously blocked. These findings show that regulatory pathways such as CTLA-4 can hold in check already differentiated autoreactive effector Th1 cells, to inhibit the transition from tolerance to autoimmune diabetes. See accompanying commentary at http://dx.doi.org/10.1002/eji.200636591 [source] Synthesis of 2-phosphinoxidomethyl- and 2-phosphonomethyl glutaric acid derivatives,HETEROATOM CHEMISTRY, Issue 7 2005Kálmán Harsányi Michael addition of the corresponding anions derived from diphenylphosphine oxide, dialkylphosphites, and a cyclic phosphite to ,-methylene-glutaric esters (1) afforded the title compounds (2,6). Double debenzylation of 2-phosphono glutaric esters 4b and 5a by catalytic hydrogenation under the appropriate conditions gave the correspon- ding diacides 8 and 9, respectively. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:562,565, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20142 [source] Composition and Longitudinal Patterns of Aquatic Insect Emergence in Small Rivers of Palawan Island, the PhilippinesINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2004Hendrik Freitag Abstract This study presents the first emergence trap samples from streams in the Philippines and Greater Sunda. Aquatic insect emergence from two small rivers and longitudinal patterns including estuaries are compared. A decline of total emergence towards estuaries was observed, affecting all major orders. Diptera, namely Chironomidae, dominated all sites. High abundances in Ceratopogonidae, Odonata, and Coleoptera were found, compared to other emergence studies from tropical and temperate latitudes. Ephemeroptera displayed a highly variable contribution to the emergence from Palawan as well as in other comparative studies either supported by the appropriate conditions for certain functional groups or limited by environmental variables such as pH. Trichoptera are likely to tolerate a wider range of environmental conditions and they are consequently able to fill further niches where Ephemeroptera are under-represented. Except for scarce abundances of Plecoptera observed in this and other studies from the tropics, no substantial differences in emergence composition at order level existed between temperate and tropical rivers, however, with a remarkable local variation. Components of riparian and non-aquatic insects and non-emergent fauna contributing to the collections are discussed based on trap features. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Putative Mechanism for Anticancer and Apoptosis-Inducing Properties of Plant-Derived Polyphenolic CompoundsIUBMB LIFE, Issue 3 2000S. M. Hadi Abstract Several plant-derived polyphenolic compounds are considered to possess anticancer and apoptosis-inducing properties in cancer cells. Such compounds are recognized as naturally occurring antioxidants but also exhibit prooxidant properties under appropriate conditions. Evidence in the literature suggests that the antioxidant properties of polyphenolics such as gallotannins, curcumin, and resveratrol may not fully account for their chemopreventive effects. We propose a mechanism for the cytotoxic action of these compounds against cancer cells that involves mobilization of endogenous copper and the consequent prooxidant action. [source] If We Value Individual Responsibility, Which Policies Should We Favour?JOURNAL OF APPLIED PHILOSOPHY, Issue 1 2005ALEXANDER BROWN ABSTRACT Individual responsibility is now very much on the political agenda. Even those who believe that its importance has been exaggerated by the political right , either because the appropriate conditions for assigning responsibility to individuals are rarely satisfied or because not enough is done to protect individuals from the more harmful consequences of their past choices and gambles , accept that individual responsibility is at least one of the values against which a society and its institutions ought to be evaluated. One might be forgiven for assuming, then, that we know exactly why individual responsibility is important. The truth is otherwise. Surprisingly little philosophical work has been undertaken to analyse and separate out the different rationales that might be in play. Several possible reasons are examined here including: utility, the social bases of self-respect, autonomy, human flourishing and fairness. However, once we adopt a pluralistic view of the value of individual responsibility we open up the possibility of value conflict, which conflict can make it harder to arrive at definitive prescriptions about which social policies best advance our concerns for individual responsibility. It is nevertheless possible to draw at least some conclusions about which policies we should favour. One important conclusion is that sometimes it is better not to hold individuals responsible for their past choices by denying them aid now, so that they might be better able to assume individual responsibility at a later date. [source] Preparation of a heterogeneous hollow-fiber affinity membrane having a mercapto chelating resin and its recovery of Hg2+ cationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Bing Wang Abstract A kind of heterogeneous hollow-fiber affinity filter membrane with a high chelating capacity for Hg2+ was prepared by phase separation with blends of a mercapto chelating resin and polysulfone as the membrane materials, N,N -dimethylacetamide as the solvent, and water as the extraction solvent. The adsorption isotherms of the hollow-fiber affinity filter membrane for Hg2+ were determined. The heterogeneous hollow-fiber affinity filter membrane was used for the adsorption of Hg2+ cations through the coordination of the mercapto group and Hg2+ cations, and the effects of the morphology and structure of the affinity membrane on the chelating properties were investigated. The chelating conditions, including the chelating resin grain size, pH value, concentration of the metallic ion solution, mobile phase conditions, and operating parameters, had significant effects on the chelating capacity of the hollow-fiber affinity filter membrane. The results revealed that the greatest chelating capacity of the hollow-fiber affinity filter membrane for Hg2+ was 1090 ,g/cm2 of membrane under appropriate conditions, and the adsorption isotherms of Hg2+ could be described by the Langmuir isotherm. The dynamic chelating experiments indicated that the hollow-fiber affinity membrane could be operated at a high feed flow rate and that large-scale removal of Hg2+ could be realized. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Mechanical strength of laser-welded cobalt,chromium alloyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2004N. Baba Abstract The purpose of this study was to investigate the effect of the output energy of laserwelding and welding methods on the joint strength of cobalt-chromium (Co-Cr) alloy. Twotypes of cast Co-Cr plates were prepared, and transverse sections were made at the center ofthe plate. The cut surfaces were butted against one another, and the joints welded with alaser-welding machine at several levels of output energy with the use of two methods. Thefracture force required to break specimens was determined by means of tensile testing. For the0.5-mm-thick specimens, the force required to break the 0.5-mm laser-welded specimens atcurrents of 270 and 300 A was not statistically different (p > 0.05) from the results for thenonwelded control specimens. The force required to break the 1.0-mm specimens double-weldedat a current of 270 A was the highest value among the 1.0-mm laser-welded specimens. The results suggested that laser welding under the appropriate conditions improved the jointstrength of cobalt- chromium alloy. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 121,124, 2004 [source] Model Selection for Broadband Semiparametric Estimation of Long Memory in Time SeriesJOURNAL OF TIME SERIES ANALYSIS, Issue 6 2001Clifford M. Hurvich We study the properties of Mallows' CL criterion for selecting a fractional exponential (FEXP) model for a Gaussian long-memory time series. The aim is to minimize the mean squared error of a corresponding regression estimator dFEXP of the memory parameter, d. Under conditions which do not require that the data were actually generated by a FEXP model, it is known that the mean squared error MSE=E[dFEXP,d]2 can converge to zero as fast as (log n)/n, where n is the sample size, assuming that the number of parameters grows slowly with n in a deterministic fashion. Here, we suppose that the number of parameters in the FEXP model is chosen so as to minimize a local version of CL, restricted to frequencies in a neighborhood of zero. We show that, under appropriate conditions, the expected value of the local CL is asymptotically equivalent to MSE. A combination of theoretical and simulation results give guidance as to the choice of the degree of locality in CL. [source] Expression of extracellular matrix genes in cultured hepatic oval cells: an origin of hepatic stellate cells through transforming growth factor beta?LIVER INTERNATIONAL, Issue 4 2009Ping Wang Abstract Background: Hepatic oval cells, progenitor cells in the liver, can differentiate into hepatocytes and bile duct cells both in vitro and in vivo. Although hepatic stellate cells are another important cell component in the liver, less attention has been focused on the relationship between hepatic oval cells and hepatic stellate cells. Methods: Hepatic oval cells were isolated from rats fed a choline-deficient diet supplemented with 0.1% ethionine for 6 weeks and characterized by electron microscopy, flow cytometry, reverse transcription polymerase chain reaction, Western blot and bi-direction differentiation. After treatment with transforming growth factor-,1 (TGF-,1), changes in cell viability, morphology, extracellular matrix (ECM) expression and immune phenotype were analysed in these cultured and adherent hepatic oval cells. Results: The primary cultured hepatic oval cells were positive for the oval cell-specific markers OV-6, BD-1/BD-2 and M2PK as well as the hepatocyte markers albumin and ,-foetoprotein. These hepatic oval cells differentiated bipotentially into hepatocytes or bile duct-like cells under appropriate conditions. It is noteworthy that these bipotential hepatic oval cells expressed ECM genes stably, including collagens, matrix metalloproteinases and tissue inhibitor of mellatoproteinase. Furthermore, except for growth inhibition and morphological changes in the hepatic oval cells after exposure to TGF-,1, there was an increased expression of ECM genes, the onset expression of snail and loss expression of E-cadherin. During this process, TGF-,1 treatment induced an upregulation of marker genes for hepatic stellate cells in hepatic oval cells, such as desmin and GFAP. Conclusion: Except for the expression of ECM, the cultured hepatic oval cells could induce an increased expression of hepatic stellate cell markers by TGF-,1 through an epithelial,mesenchymal transition process, which might indicate the contribution of hepatic oval cells to liver fibrosis. [source] SEPARABLE TERM STRUCTURES AND THE MAXIMAL DEGREE PROBLEMMATHEMATICAL FINANCE, Issue 4 2002Damir Filipovi This paper discusses separablc term structure diffusion models in an arbitrage-free environment. Using general consistency results we exploit the interplay between the diffusion coefficients and the functions determining the forward curve. We introduce the particular class of polynomial term structure models. We formulate the appropriate conditions under which the diffusion for a quadratic term structure model is necessarily an Ornstein-Uhlenbeck type process. Finally, we explore the maximal degree problem and show that basically any consistent polynomial term structure model is of degree two or less. [source] Sufficient conditions of non-uniqueness for the Coulomb friction problemMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 1 2004Riad Hassani Abstract We consider the Signorini problem with Coulomb friction in elasticity. Sufficient conditions of non-uniqueness are obtained for the continuous model. These conditions are linked to the existence of real eigenvalues of an operator in a Hilbert space. We prove that, under appropriate conditions, real eigenvalues exist for a non-local Coulomb friction model. Finite element approximation of the eigenvalue problem is considered and numerical experiments are performed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Blowup of solutions for a class of non-linear evolution equations with non-linear damping and source termsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 10 2002Yang Zhijian We consider the blowup of solutions of the initial boundary value problem for a class of non-linear evolution equations with non-linear damping and source terms. By using the energy compensation method, we prove that when p>max{m, ,}, where m, , and p are non-negative real numbers and m+1, ,+1, p+1 are, respectively, the growth orders of the non-linear strain terms, damping term and source term, under the appropriate conditions, any weak solution of the above-mentioned problem blows up in finite time. Comparison of the results with the previous ones shows that there exist some clear condition boundaries similar to thresholds among the growth orders of the non-linear terms, the states of the initial energy and the existence and non-existence of global weak solutions. Copyright © 2002 John Wiley & Sons, Ltd. [source] Inverse scattering for the non-linear Schrödinger equation: Reconstruction of the potential and the non-linearityMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 4 2001Ricardo Weder In this paper we consider the inverse scattering problem for the non-linear Schrödinger equation on the line \def\dr{{\rm d}}$$i{\partial\over\partial t}u(t,x)=-{\dr^2\over\dr x^2}u(t,x)+V_0(x)u(t,x)+\sum_{j=1}^{\infty}V_j(x)|u|^{2(j_0+j)}u(t,x)$$\nopagenumbers\end We prove, under appropriate conditions, that the small-amplitude limit of the scattering operator determines uniquely Vj, j=0,1,, . Our proof gives also a method for the reconstruction of the Vj, j=0,1,, . Copyright © 2001 John Wiley & Sons, Ltd. [source] Global continuation for first order systems over the half-line involving parametersMATHEMATISCHE NACHRICHTEN, Issue 8 2009Gilles EvéquozArticle first published online: 21 JUL 200 Abstract Let X be one of the functional spaces W1,p ((0, ,), ,N) or C01 ([0, ,), ,N), we study the global continuation in , for solutions (,, u, ,) , , × X × ,k of the following system of ordinary differential equations: where ,N = X1 , X2 is a given decomposition, with associated projection P: ,N , X1. Under appropriate conditions upon the given functions F and ,, this problem gives rise to a nonlinear Fredholm operator which is proper on the closed bounded subsets of , × X × ,k and whose zeros correspond to the solutions of the original problem. Using a new abstract continuation result, based on a recent degree theory for proper Fredholm mappings of index zero, we reduce the continuation problem to that of finding a priori estimates for the possible solutions (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photochemistry of Oxazolidinone Antibacterial Drugs,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2009Elisa Fasani The photochemistry of six N3-(3-fluoro-4-dialkylaminophenyl)-oxazolidinones known for their antimicrobial activity has been examined. All of these compounds are defluorinated in water (,dec , 0.25) and in methanol (,dec , 0.03), reasonably via the triplet. The chemical processes observed are reductive defluorination and solvolysis, depending on the structural variation introduced (thus, tethering the dialkylamino group to the aromatic ring and introducing a highly polar group in the oxazolidinone moiety have an effect). A likely mechanism involves the fragmentation of the C,F bond yielding the corresponding triplet phenyl cation. This intermediate either is reduced or, under appropriate conditions, intersystem crosses to the singlet state that adds the solvent. These data demonstrate a sizeable photodecomposition of these drugs that causes a decrease in the therapeutic activity. Furthermore, the likely formation of phenyl cations may cause a photogenotoxic effect. [source] Amyloid,a state in many guises: Survival of the fittest fibril foldPROTEIN SCIENCE, Issue 1 2008Jesper S. Pedersen Abstract Under appropriate conditions, essentially all proteins are able to aggregate to form long, well-ordered and ,-sheet-rich arrays known as amyloid-like fibrils. These fibrils consist of varying numbers of intertwined protofibrils and can for any given protein exhibit a wealth of different forms at the ultrastructural level. Traditionally, this structural variability or polymorphism has been attributed to differences in the assembly of a common protofibril structure. However, recent work on glucagon, insulin, and the A, peptide suggests that this polymorphism can occur at the level of secondary structure. Simple variations in either solvent conditions such as temperature, protein concentration, and ionic strength or external mechanical influences such as agitation can lead to formation of fibrils with markedly different characteristics. In some cases, these characteristics can be passed on to new fibrils in a strain-specific manner, similar to what is known for prions. The preferred structure of fibrils formed can be explained in terms of selective pressure and survival of the fittest; the most populated types of fibrils we observe at the end of an experiment are those that had the fastest overall growth rate under the given conditions. Fibrillar polymorphism is probably a consequence of the lack of structural restraints on a nonfunctional conformational state. [source] Reduction of the amyloidogenicity of a protein by specific binding of ligands to the native conformationPROTEIN SCIENCE, Issue 4 2001Fabrizio Chiti AcP, acylphosphatase; CD, circular dichroism; TFE, 2,2,2-trifluoroethanol; TTR, transthyretin Abstract It is known that human muscle acylphosphatase (AcP) is able, under appropriate conditions in vitro, to aggregate and form amyloid fibrils of the type associated with human diseases. A number of compounds were tested for their ability to bind specifically to the native conformation of AcP under conditions favoring denaturation and subsequent aggregation and fibril formation. Compounds displaying different binding affinities for AcP were selected and their ability to inhibit protein fibrillization in vitro was evaluated. We found that compounds displaying a relatively high affinity for AcP are able to significantly delay protein fibrillization, mimicking the effect of stabilizing mutations; in addition, the effectiveness of such outcome correlates positively to both ligand concentration and affinity to the native state of AcP. By contrast, the inhibitory effect of ligands on AcP aggregation disappears in a mutant protein in which such binding affinity is lost. These results indicate that the stabilization of the native conformation of amyloidogenic proteins by specific ligand binding can be a strategy of general interest to inhibit amyloid formation in vivo. [source] Structure, phase transitions and ionic conductivity of K3NdSi6O15·xH2O.ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2000Hydrothermally grown crystals of ,-K3NdSi6O15, potassium neodymium silicate, have been studied by single-crystal X-ray methods. Under appropriate conditions, the compound crystallizes in space group Bb21m and has lattice constants a = 14.370,(2), b = 15.518,(2) and c = 14.265,(2),Ĺ. There are 30 atom sites in the asymmetric unit of the basic structure. With eight formula units per unit cell, the calculated density is 2.798,Mg,m,3. Refinement was carried out to a residual, wR(F2), of 0.1177 [R(F) = 0.0416] using anisotropic temperature factors for all atoms. The structure is based on (Si2O52,), layers, connected by Nd polyhedra to form a three-dimensional framework. Potassium ion sites, some of which are only partially occupied, are located within channels that run between the silicate layers. The silica,neodymia framework of ,-K3NdSi6O15, in particular the linkages formed between the silicate layers and Nd polyhedra, bears some similarities to that of the essentially isocompositional phase ,-K3NdSi6O15·2H2O. In both, the silicate layers are corrugated so as to accommodate a simple cubic array of NdO6 octahedra with lattice constant , 7.5,Ĺ. Furthermore, the Si2O5 layers in ,-K3NdSi6O15 are topologically identical to those of the mineral sazhinite, Na2HCeSi6O15. Although ,-K3NdSi6O15 and sazhinite are not isostructural, the structures of each can be described as slight distortions of a high-symmetry parent structure with space group Pbmm. [source] Cooperation and cheating in microbial exoenzyme production , Theoretical analysis for biotechnological applicationsBIOTECHNOLOGY JOURNAL, Issue 7 2010Stefan Schuster Abstract The engineering of microorganisms to produce a variety of extracellular enzymes (exoenzymes), for example for producing renewable fuels and in biodegradation of xenobiotics, has recently attracted increasing interest. Productivity is often reduced by "cheater" mutants, which are deficient in exoenzyme production and benefit from the product provided by the "cooperating" cells. We present a game-theoretical model to analyze population structure and exoenzyme productivity in terms of biotechnologically relevant parameters. For any given population density, three distinct regimes are predicted: when the metabolic effort for exoenzyme production and secretion is low, all cells cooperate; at intermediate metabolic costs, cooperators and cheaters coexist; while at high costs, all cells use the cheating strategy. These regimes correspond to the harmony game, snowdrift game, and Prisoner's Dilemma, respectively. Thus, our results indicate that microbial strains engineered for exoenzyme production will not, under appropriate conditions, be outcompeted by cheater mutants. We also analyze the dependence of the population structure on cell density. At low costs, the fraction of cooperating cells increases with decreasing cell density and reaches unity at a critical threshold. Our model provides an estimate of the cell density maximizing exoenzyme production. [source] A Stereodivergent Synthesis of All Stereoisomers of Centrolobine: Control of Selectivity by a Protecting-Group ManipulationCHEMISTRY - A EUROPEAN JOURNAL, Issue 44 2009Bernd Schmidt Prof. Abstract All stereoisomers of the natural product centrolobine are selectively synthesized, by starting from a common precursor. Key steps are an enantioselective allylation with enantiomerically pure allylsilanes, a tandem ring-closing metathesis,isomerization reaction, and a Heck reaction by using an arene diazonium salt. By choosing appropriate conditions for the final deprotection step, either the cis -configured centrolobines or their epimers are selectively obtained. [source] Controlling the Association of Adamantyl-Substituted Poly{N -[tris(hydroxymethyl)methyl]acrylamide} and a , -Cyclodextrin/Epichlorohydrin Polymer by a Small Drug Molecule , NaproxenCHEMISTRY & BIODIVERSITY, Issue 1 2007Danica Mislovi Abstract Two polymeric substances, a poly{N -[tris(hydroxymethyl)methyl]acrylamide} (THMMA) substituted with adamantyl moieties and a , -cyclodextrin/epichlorohydrin polycondensate, formed a host,guest type complex, which resulted in the gel formation upon mixing of these two compounds at appropriate conditions. Introduction of a drug molecule, i.e., naproxen, that was able to fill the , -cyclodextrin cavities, thus expulsing adamantyl moieties, led to disruption of such association and inhibition of gel formation. The conditions required for the association of the two polymeric components and formation of the gel, as well as the dynamics of its inhibition by addition of naproxen was established. The procedure of using solutions of two associating polymers and an appropriate drug competitor can be used at targeted viscosupplementation. [source] T cell-mediated immune responses in human newborns: ready to learn?CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2005A. Marchant Summary Infections with intracellular pathogens are often more severe or more prolonged in young infants suggesting that T cell-mediated immune responses are different in early life. Whereas neonatal immune responses have been quite extensively studied in murine models, studies of T cell-mediated immunity in human newborns and infants are scarce. Qualitative and quantitative differences when compared with adult immune responses have been observed but on the other hand mature responses to certain vaccines and infectious pathogens were demonstrated during the postnatal period and even during foetal life. Herein, we review the evidence suggesting that under appropriate conditions of stimulation, protective T cell-mediated immune responses could be induced by vaccines in early life. [source] Dirichlet duality and the nonlinear Dirichlet problemCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 3 2009F. Reese Harvey We study the Dirichlet problem for fully nonlinear, degenerate elliptic equations of the form F(Hess u) = 0 on a smoothly bounded domain , , ,n. In our approach the equation is replaced by a subset F , Sym2(,n) of the symmetric n × n matrices with ,F , {F = 0}. We establish the existence and uniqueness of continuous solutions under an explicit geometric "F -convexity" assumption on the boundary ,,. We also study the topological structure of F -convex domains and prove a theorem of Andreotti-Frankel type. Two key ingredients in the analysis are the use of "subaffine functions" and "Dirichlet duality." Associated to F is a Dirichlet dual set F, that gives a dual Dirichlet problem. This pairing is a true duality in that the dual of F, is F, and in the analysis the roles of F and F, are interchangeable. The duality also clarifies many features of the problem including the appropriate conditions on the boundary. Many interesting examples are covered by these results including: all branches of the homogeneous Monge-Ampčre equation over ,, ,, and ,; equations appearing naturally in calibrated geometry, Lagrangian geometry, and p -convex Riemannian geometry; and all branches of the special Lagrangian potential equation. © 2008 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||||||||||||||