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Interchange
Terms modified by Interchange Selected AbstractsTHE IMPACT OF ELECTRONIC DATA INTERCHANGE ON DELIVERY PERFORMANCEPRODUCTION AND OPERATIONS MANAGEMENT, Issue 1 2001SOHEL AHMAD After several years of use of electronic data interchange (EDI) in various industries, the literature is still inconclusive regarding the benefits gained from its usage. We investigated contextual factors of two types: non-managerial (product diversity, product customization, production instability, and organizational size) and managerial (just-in-time and quality management), that might have confounded past results. Our results indicate that the extent of EDI use is significantly related to delivery performance after controlling for the above-mentioned factors. Furthermore, the data set supported the moderating effect of production instability on the relationship between the extent of EDI use and delivery performance achieved, but failed to support the moderating effect of organizational size. [source] Cenozoic environmental change in South America as indicated by mammalian body size distributions (cenograms)DIVERSITY AND DISTRIBUTIONS, Issue 6 2001Darin A. Croft Abstract. A cenogram is a rank-ordered body size distribution of non-predatory terrestrial mammal species within a community. Studies of cenograms for modern faunas have shown that certain quantifiable attributes of cenograms are correlated with environmental variables such as rainfall and vegetation structure. Based on these correlations, cenograms of fossil communities have been used to infer palaeoenvironments and palaeoenvironmental variables. The present study uses cenogram statistics to interpret palaeoenvironmental conditions for eight Cenozoic South American mammal faunas, ranging from Eocene to Pleistocene in age. Body sizes for fossil taxa were taken either from the literature or were estimated using regressions of body size on molar length (or femoral bicondylar width) for modern mammals. Cenogram statistics are calculated for the eight fossil faunas and compared to similar statistics calculated for 16 modern South American mammal faunas, allowing palaeoenvironmental interpretations to be made. The palaeoenvironmental interpretations based on cenogram analyses sometimes support and sometimes contradict interpretations based on herbivore craniodental morphology (e.g. levels of hypsodonty). Simulations of expected errors in body size estimates for fossil taxa suggest that the discrepancies do not result primarily from erroneous body size estimates. It is possible that some of the incongruity in interpretations results from certain non-analogue attributes of South American faunas during much of the Cenozoic (e.g. the relatively depauperate mammalian predator diversity prior to the Great American Biotic Interchange). [source] Highly Efficient and Chemoselective Interchange of 1,3-Oxathioacetals and Dithioacetals to Acetals Promoted by N-Halosuccinimide.CHEMINFORM, Issue 42 2002Babak Karimi Abstract For Abstract see ChemInform Abstract in Full Text. [source] Feminism Spoken Here: Epistemologies for Interdisciplinary Development ResearchDEVELOPMENT AND CHANGE, Issue 3 2006Cecile Jackson Development studies is a field characterized by an unusual degree of interdisciplinary and multidisciplinary research, and therefore is constantly subject both to pressures for the reproduction of disciplines as autonomous and self-sufficient, and to an increasing steer from public funders of research for interdisciplinary work which is valued for its problem-solving character and more apparent relevance, in an era greatly exercised by accountability. At a moment when the need to renew disciplinary interchange has intensified it is therefore instructive to consider the social relations which facilitate interdisciplinarity. This article does this through an argument that feminist cross-disciplinary research shows how important shared values are to motivate and sustain these kinds of learning, and that an explicit focus on social justice as the core of development research can be the basis of such a renewal. If feminist interactions and solidarity provide the motivation, feminist epistemologies provide arguments for why socially engaged research is not ,biased', but stronger than research with narrower ideas of objectivity; why reflexivities and subjectivities are crucial to the conduct of research; and how these, and the convergence of concepts of individuals and persons favoured within different disciplines, might build the common ground required for greater disciplinary interchange. [source] Biological and environmental initial conditions shape the trajectories of cognitive and social-emotional development across the first years of lifeDEVELOPMENTAL SCIENCE, Issue 1 2009Ruth Feldman Human development is thought to evolve from the dynamic interchange of biological dispositions and environmental provisions; yet the effects of specific biological and environmental birth conditions on the trajectories of cognitive and social-emotional growth have rarely been studied. We observed 126 children at six time-points from birth to 5 years. Intelligence, maternal sensitivity, and child social engagement were repeatedly tested. Effects of neonatal vagal tone (VT) and maternal postpartum depressive symptoms on growth-rates were assessed. Cognitive development showed a substantial growth-spurt between 2 and 5 years and social engagement increased rapidly across the first year and more gradually thereafter. VT improved cognitive and social-emotional growth-rates across the first year, whereas maternal depressive symptoms interfered with growth from 2 to 5 years. Differences between infants with none, one, or two non-optimal birth conditions increased with age. Findings shed light on the dynamics of early development as it is shaped by biological and environmental initial conditions. [source] The profound influence of the Late Pliocene Panamanian uplift on the exchange, diversification, and distribution of New World birdsECOGRAPHY, Issue 2 2010Brian Tilston Smith Separated throughout most of the Cenozoic era, North and South America were joined during the mid-Pliocene when the uplift of Panama formed a land bridge between these two continents. The fossil record indicates that this connection allowed an unprecedented degree of inter-continental exchange to occur between unique, previously isolated biotic assemblages, a phenomenon now recognized as the "Great American Biotic Interchange". However, a relatively poor avian fossil record has prevented our understanding the role of the land bridge in shaping New World avian communities. To address the question of avian participation in the GABI, we compiled 64 avian phylogenetic studies and applied a relaxed molecular clock to estimate the timing of trans-isthmus diversification events. Here, we show that a significant pulse of avian interchange occurred in concert with the isthmus uplift. The avian exchange was temporally consistent with the well understood mammalian interchange, despite the presumed greater vagility of birds. Birds inhabiting a variety of habitats and elevational zones responded to the newly available corridor. Within the tropics, exchange was equal in both directions although between extratropical and tropical regions it was not. Avian lineages with Nearctic origins have repeatedly invaded the tropics and radiated throughout South America; whereas, lineages with South American tropical origins remain largely restricted to the confines of the Neotropical region. This previously unrecognized pattern of asymmetric niche conservatism may represent an important and underappreciated contributor to the latitude diversity gradient. [source] Geographic and Temporal Variation of the Male Zebra Finch Distance CallETHOLOGY, Issue 4 2005David Runciman Temporal and geographic variation of acoustic signals can provide insights into dispersal patterns, population history and speciation. Vocalizations that are transmitted from one generation to the next are of particular value in this respect because they can reveal patterns of gene flow, effectively behaving as population markers. The male zebra finch Taeniopygia guttata distance call is one such vocalization; sons learn their father's distance call in the first 40 d of life and it is individually stereotyped thereafter. We investigated geographic variation in the zebra finch by comparing the structure of distance calls recorded from 61 males from six populations across the continent-wide range of the Australian subspecies T. g. castanotis. Intra-population variation was high, in many cases greater than the variation among all males recorded, possibly because of population interchange. However, three of six call variables measured, including the newly discovered modulated element, varied geographically although the pattern of distance call variation did not agree with that of geographic proximity of populations. The proportion of calls with a modulated element increased dramatically over 7 yr in central Australia but there was no change over a similar period of time in south-eastern Australia where no calls contained the element. The findings suggest that interchange among widely separated populations may be commonplace in Australian zebra finches, with the possible exception of those from south-eastern Australia. [source] The application of NN technique to automatic generation control for the power system with three areas including smes unitsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2003A. Demirören The study includes an application of layered neural network controller to study automatic generation control (AGC) problem of the power system, which contains superconducting magnetic energy storage (SMES) units. The effectiveness of SMES unit over frequency oscillations improvement against load perturbations in power system is well known. In addition, the proposed control scheme provides the steady state error of frequency and inadvertent interchange of tie-lines to be maintained in steady state values. The power system considered has three areas two of which including steam turbines while the other containing a hydro turbine, and all of them contain SMES units, in addition. In the power system each area with a steam turbine contains the non-linearity due to reheat effect of the steam turbine and all of the areas contain upper and lower constraints for generation rate. Only one neural network (NN) controller, which controls all the inputs of each area in the power system, is considered. In the NN controller, back propagation-through-time algorithm is used as neural network learning rule. The performance of the power system is simulated by using conventional integral controller and NN controller for the cases with or without SMES units in all areas, separately. By comparing the results for both cases, it can be seen that the performance of NN controller is better than conventional controllers. [source] First principles study of small palladium cluster growth and isomerizationINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2007Chen Luo Abstract Structures and physical properties of small palladium clusters Pdn up to n = 15 and several selected larger clusters were studied using density functional theory under the generalized gradient approximation. It was found that small Pdn clusters begin to grow 3-dimensionally at n = 4 and evolve into symmetric geometric configurations, such as icosahedral and fcc -like, near n = 15. Several isomers with nearly degenerate average binding energies were found to coexist and the physical properties of these clusters were calculated. For several selected isomers, relatively moderate energy barriers for structural interchange for a given cluster size were found, implying that isomerization could readily occur under ambient conditions. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] BSSE-free hardness profiles of hydrogen bond exchange in the hydrogen fluoride dimerINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 14 2006David Asturiol Abstract Hardness profiles are calculated for the hydrogen bond interchange in the hydrogen fluoride dimer; the study is carried out at the Hartree,Fock and second-order Mřller,Plesset (MP2) levels of theory with three different basis sets. The basis set superposition error (BSSE) is corrected by means of the chemical Hamiltonian approach (CHA). Uncorrected and BSSE-corrected energy and hardness profiles are compared. Their analysis shows that hardness profiles do not lead to spurious minima as energy profiles do in various cases. The CHA methodology is shown to be valuable in the analysis of intermolecular interactions, with BSSE observed to carry smaller modifications on hardness profiles than on energy curves. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] The "externalization" of labour lawINTERNATIONAL LABOUR REVIEW, Issue 1-2 2009Antonio OJEDA AVILÉS Abstract. The powerful process of labour law adjustment which, for some three decades, experts have looked upon as one of fragmentation , not to say disintegration , into evermore disconnected subfields is turning into a general trend that looks set to take on a structural dimension. An expansionary drive is indeed taking labour law into alien territories, seemingly jeopardizing its identity and traditional boundaries, albeit with a symbiotic interchange of reciprocal influences. This article analyses six avenues of expansion which have been observed in Europe and in some American and Asian countries. [source] Anglo-Italian Cultural Relations before and during the Long Eighteenth CenturyJOURNAL FOR EIGHTEENTH-CENTURY STUDIES, Issue 2 2010JOHN GASH Abstract This introduction sketches some of the key factors and moments in Anglo-Italian contact from the Roman occupation of Britain to the emergence of the Grand Tour in the seventeenth century as a channel for cultural interchange. It then indicates some of the changes that occurred in the nature of that interchange during the eighteenth century. These are explored in the ensuing essays, whose subjects range from the impact in Italy of the writings of Hobbes, through the motivations and prejudices of British travellers to the peninsula, to the reciprocal journeys to England of Italian painters and art dealers. [source] Spatial and temporal variation in the relative contribution of density dependence, climate variation and migration to fluctuations in the size of great tit populationsJOURNAL OF ANIMAL ECOLOGY, Issue 2 2009Vidar Grřtan Summary 1The aim of the present study is to model the stochastic variation in the size of five populations of great tit Parus major in the Netherlands, using a combination of individual-based demographic data and time series of population fluctuations. We will examine relative contribution of density-dependent effects, and variation in climate and winter food on local dynamics as well as on number of immigrants. 2Annual changes in population size were strongly affected by temporal variation in number of recruits produced locally as well as by the number of immigrants. The number of individuals recruited from one breeding season to the next was mainly determined by the population size in year t, the beech crop index (BCI) in year t and the temperature during March,April in year t. The number of immigrating females in year t + 1 was also explained by the number of females present in the population in year t, the BCI in autumn year t and the temperature during April,May in year t. 3By comparing predictions of the population model with the recorded number of females, the simultaneous modelling of local recruitment and immigration explained a large proportion of the annual variation in recorded population growth rates. 4Environmental stochasticity especially caused by spring temperature and BCI did in general contribute more to annual fluctuations in population size than density-dependent effects. Similar effects of climate on local recruitment and immigration also caused covariation in temporal fluctuations of immigration and local production of recruits. 5The effects of various variables in explaining fluctuations in population size were not independent, and the combined effect of the variables were generally non-additive. Thus, the effects of variables causing fluctuations in population size should not be considered separately because the total effect will be influenced by covariances among the explanatory variables. 6Our results show that fluctuations in the environment affect local recruitment as well as annual fluctuations in the number of immigrants. This effect of environment on the interchange of individuals among populations is important for predicting effects of global climate change on the pattern of population fluctuations. [source] Does infectious disease influence the efficacy of marine protected areas?JOURNAL OF APPLIED ECOLOGY, Issue 4 2005A theoretical framework Summary 1Marine protected areas are increasingly being recommended as an essential component of the management of exploited marine species, but virtually no attention has been given to the influence of parasites. This may be substantial, as a primary effect of marine reserves is to increase the density of an exploited population within the reserve relative to outside the reserve, which may facilitate parasite transmission. 2We used a simple deterministic model of microparasitic infection in a fishery with a reserve to investigate equilibrium yield and parasite prevalence inside and outside the reserve as a function of three control variables: the proportion of habitat inside the reserve, fishing mortality and the rate of interchange between the stock and the reserve. 3While our model is generic, we parameterized it with values that may be appropriate to the interaction between abalone and Rickettsia. 4The presence of a pathogen does not necessarily decrease yield when a reserve is present, particularly if the rate of movement of adult hosts between stock and reserve is low. 5Synthesis and applications. Pathogens have important implications for the design of marine reserves. Our modelling identifies two key considerations. First, ,fishing out' a pathogen by reducing the host population density to a level below the threshold for disease maintenance is a potential management strategy that is made more difficult by establishing a reserve. Secondly, the effect of a highly transmissible pathogen without a reserve is to cause a rapid decline in equilibrium yield for efforts beyond those that produce maximum sustainable yield, making the fishery prone to collapse. Introducing a reserve decreases yield in this case, but makes the fishery much more resistant to collapse. [source] Fish assemblages of the Casiquiare River, a corridor and zoogeographical filter for dispersal between the Orinoco and Amazon basinsJOURNAL OF BIOGEOGRAPHY, Issue 9 2008Kirk O. Winemiller Abstract Aim, The aim of this study was to determine whether the Casiquiare River functions as a free dispersal corridor or as a partial barrier (i.e. filter) for the interchange of fish species of the Orinoco and Negro/Amazon basins using species assemblage patterns according to geographical location and environmental features. Location, The Casiquiare, Upper Orinoco and Upper Negro rivers in southern Venezuela, South America. Methods, Our study was based on an analysis of species presence/absence data and environmental information (11 habitat characteristics) collected by the authors and colleagues between the years 1984 and 1999. The data set consisted of 269 sampled sites and 452 fish species (> 50,000 specimens). A wide range of habitat types was included in the samples, and the collection sites were located at various points along the entire length of the Casiquiare main channel, at multiple sites on its tributary streams, as well as at various nearby sites outside the Casiquiare drainage, within the Upper Orinoco and Upper Rio Negro river systems. Most specimens and field data used in this analysis are archived in the Museo de Ciencias Naturales in Guanare, Venezuela. We performed canonical correspondence analysis (CCA) based on species presence/absence using two versions of the data set: one that eliminated sites having < 5 species and species occurring at < 5 sites; and another that eliminated sites having < 10 species and species occurring at < 10 sites. Cluster analysis was performed on sites based on species assemblage similarity, and a separate analysis was performed on species based on CCA loadings. Results, The CCA results for the two versions of the data set were qualitatively the same. The dominant environmental axis contrasted assemblages and sites associated with blackwater vs. clearwater conditions. Longitudinal position on the Casiquiare River was correlated (r2 = 0.33) with CCA axis-1 scores, reflecting clearwater conditions nearer to its origin (bifurcation of the Orinoco) and blackwater conditions nearer to its mouth (junction with the Rio Negro). The second CCA axis was most strongly associated with habitat size and structural complexity. Species associations derived from the unweighted pair-group average clustering method and pair-wise squared Euclidean distances calculated from species loadings on CCA axes 1 and 2 showed seven ecological groupings. Cluster analysis of species assemblages according to watershed revealed a stronger influence of local environmental conditions than of geographical proximity. Main conclusions, Fish assemblage composition is more consistently associated with local environmental conditions than with geographical position within the river drainages. Nonetheless, the results support the hypothesis that the mainstem Casiquiare represents a hydrochemical gradient between clearwaters at its origin and blackwaters at its mouth, and as such appears to function as a semi-permeable barrier (environmental filter) to dispersal and faunal exchanges between the partially vicariant fish faunas of the Upper Orinoco and Upper Negro rivers. [source] Historical biogeography of scarabaeine dung beetlesJOURNAL OF BIOGEOGRAPHY, Issue 9 2002Adrian L. V. Davis Abstract Aim, (1) To review briefly global biogeographical patterns in dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), a group whose evolutionary history has been dominated by ecological specialization to vertebrate dung in warmer climates. (2) To develop hypotheses accounting for the evolution of these patterns. Location, Six principal biogeographical regions: Palaearctic, Oriental, Afrotropical, Australasia, Neotropical, Nearctic and five outlying islands or island groups harbouring endemic genera: Caribbean, Madagascar, Mauritius, New Caledonia, New Zealand. Methods, Major patterns of tribal, generic and species distribution are investigated using cluster analysis, ordination, parsimony analysis of endemism and track analysis. Attempts are made to resolve biogeographical patterns with findings in the fields of plate tectonics, fossil and evolutionary history, plus phylogeny of both mammals and dung beetles. Results, Because of conflict between published findings, it is uncertain at what point in time density of dinosaur dung, mammal dung or both became sufficiently great to select for specialized habits in dung beetles. However, biogeographical evidence would suggest a Mesozoic origin followed by further taxonomic radiation during the Cenozoic, possibly in response to the increasing size and diversity of mammalian dung types in South America and Afro-Eurasia. Proportional generic distribution in fourteen tribes and subtribes showed four principal biogeographical patterns: (1) southerly biased Gondwanaland distribution, (2) Americas or (3) Madagascar endemism, and (4) northerly biased, Afro-Eurasian-centred distribution with limited numbers of genera also widespread in other regions. Proportional composition of faunas in eleven geographical regions indicated three principal distributional centres, East Gondwanaland fragments, Afro-Eurasia and the Americas. These patterns probably result from three principal long-term range expansion and vicariance events (Mesozoic: Gondwanaland interchange and fragmentation, Cenozoic: Afro-Eurasian/Nearctic interchange and the Great American interchange). It is suggested that old vicariance caused by the Mesozoic fragmentation of Gondwanaland leads to a high degree of regional endemism at generic or tribal level across one or more Gondwanaland tracks. In contrast, it is suggested that the more recent Cenozoic range expansions occurred primarily towards northern regions leading to endemism primarily at species level. These Cenozoic radiations were facilitated by the re-linking of continents, either because of tectonic plate movements (Africa to Eurasia in Miocene), climatically induced sea-level change (Afro-Eurasia to Nearctic in Miocene and Pleistocene), or similar coupled with orogenics (Nearctic to Neotropical in Pliocene). Speciation has followed vicariance either because of climatic change or physical barrier development. These recent range expansions probably occurred principally along an Afro-Eurasian land track to the Nearctic and Neotropical and an Americas land track northwards from the Neotropics to the Nearctic, with limited dispersal from Eurasia to Australia, probably across a sea barrier. This accounts for the overall, spatially constrained, biogeographical pattern comprising large numbers of species-poor genera endemic to a single biogeographical region and fewer more species-rich genera, many of which show wider biogeographical distributions. In most southerly regions (Australasia, Madagascar, Neotropical), faunal composition and generic endemism is primarily dominated by elements with Gondwanaland ancestry, which is consistent with the Gondwanaland origin claimed for Scarabaeinae. In Afro-Eurasia (Palaearctic, Oriental, Afrotropical), generic endemism of monophyletically derived Afro-Eurasian and widespread lineages is centred in the Afrotropical region and faunal composition is numerically dominated by Afro-Eurasian and widespread elements. In the Nearctic region, the fauna is jointly dominated by widespread elements, derived from Afro-Eurasia, and Gondwanaland and Americas elements derived from the Neotropical region. Main conclusions, Global biogeographical patterns in scarabaeine dung beetles primarily result from Mesozoic and Cenozoic range expansion events followed by vicariance, although recent dispersal to Australia may have occurred across sea barriers. Detailed phylogenetics research is required to provide data to support dispersal/vicariance hypotheses. [source] Toward a community-oriented action research framework for spirituality: Community psychological and theological perspectivesJOURNAL OF COMMUNITY PSYCHOLOGY, Issue 5 2001Paul R. Dokecki Spirituality, once an old and honorable religious term for the "exploration into what is involved in becoming human" (McFague, 1997, p. 10), is ubiquitous in contemporary culture, albeit highly diverse and ambiguous in its usage. In our active interchange involving two community psychologists and a theologian,carried on in the spirit of Lewinian action research and pastoral theology's method of congregational studies, we have returned to that earlier tradition. We are developing a framework for spirituality encompassing human development and community development as two sides of the same coin. The framework provides a community-oriented theoretical account of the dynamics of spirituality and a foundation for action research on the interrelationship of spirituality and community. We begin by describing the context for the development of the framework,the St. Robert project, a participant,observer action research and consultation project ongoing for more than ten years in a Roman Catholic parish. We then present the framework's elements and conclude by outlining an ongoing empirical inquiry at St. Robert into the nature of spirituality, which has implications for the field's address to the spiritual dimensions of personal and community experience, especially psychological sense of community. © 2001 John Wiley & Sons, Inc. [source] Establishing a perimeter position: speciation around the Indian Ocean BasinJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2008G. VOELKER Abstract Historical biological interactions among peripheral landmasses on the periphery of the Indian Ocean Basin (IOB) are generally poorly understood. While interactions based on early Gondwanan vicariance have been used to explain present day lineage distributions, several recent studies have instead inferred dispersal across the IOB. This inference is often advanced because lineages under study have species inhabiting IOB islands. Here we examine the roles of continental vicariance vs. trans-IOB dispersal in the distribution of an avian genus found around the perimeter of the IOB. A molecular phylogeny does reveal evidence of a relationship that would require the inference of trans-IOB dispersal between eastern Africa and Sri Lanka. However, molecular clock data, ancestral area analyses and paleoclimatic reconstructions suggest that vicariance related to tropical forest expansion and retraction is more likely to have facilitated African,Asian interchange, with an initial colonization of Africa from Asia quickly followed by a recolonization of Asia. Subsequent dispersal from Asia to Sri Lanka and islands east of the Sunda Shelf are inferred; these latter islands were colonized in a stepping-stone fashion that culminated in colonization of the Sunda Shelf, and a recolonization of mainland Asia. We propose that circum-IOB distributions, which post-date early Gondwanan breakup, are most likely the result of continent-based vicariant events, particularly those events related to large-scale habitat alterations, and not trans-IOB dispersals. [source] Photochemistry of 4- and 5- phenyl substituted isoxazolesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2005James W. Pavlik 5-Phenylisoxazole (4) and 4-phenylisoxazole (22) underwent phototransposition to 5-phenyloxazole (5) and 4-phenyloxazole (24) respectively. Labeling with deuterium or methyl confirmed that these phototranspositions occurred via the P4 pathway which involves only interchange of the N2 and C3 ring position. Thus, 4-deuterio-5-phenylisoxazole (4-4d), 4-methyl-5-phenylisoxazole (10), and 5-methyl-4-phenylisoxazole (23) phototransposed to 4-deuterio-5-phenyloxazole (5-4d), 4-methyl-5-phenyloxazole (11), and 5-methyl-4-phenyloxazole (25) respectively. In addition to phototransposition, isoxazoles 4, 10, and 23 also underwent photo-ring cleavage to yield benzoylacetonitrile (9), ,-benzoylpropionitrile (15), and aceto-,-phenylacetonitrile (26) respectively. Irradiation of 5-phenyl-3-(trifluoromethyl)isoxazole (16) in acetonitrile led to 5-phenyl-2-(trifluoromethyl)oxazole (17), the P4 phototransposition product. Irradiation of 16 in methanol led to a substantial decrease in the yield of 17 and to the formation of a mixture of (E) and (Z)-2-methoxy-2-(trifluoromethyl)-3-benzoylaziridines 18a and 18b. [source] Characterization of ,- and ,-glutamyl dipeptides by negative ion collision-induced dissociationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2004Alex G. Harrison Abstract The low-energy CID mass spectra of the [M , H], ions of a variety of dipeptides containing glutamic acid have been obtained using cone-voltage collisional activation. Dipeptides with the ,-linkage, H-Glu(Xxx-OH)-OH, are readily distinguished from those with the ,-linkage, H-Glu-Xxx-OH, by the much more prominent elimination of H-Xxx-OH from the [M , H], ions of the former isomers, resulting in formation of m/z 128, presumably deprotonated pyroglutamic acid. Dipeptides with the reverse linkage, H-Xxx-Glu-OH, show distinctive fragmentation reactions of the [M , H], ions including enhanced elimination of CO2 and formation of deprotonated glutamic acid. Exchange of the labile hydrogens for deuterium has shown that there is considerable interchange of C-bonded hydrogens with labile (N- and O-bonded) hydrogens prior to most fragmentation reactions. All dipeptides show loss of H2O from [M , H],. MS3 studies show that the [M , H , H2O], ion derived from H-Glu-Gly-OH has the structure of deprotonated pyroglutamylglycine while the [M , H , H2O], ions derived from H-Glu(Gly-OH)-OH and H-Gly-Glu-OH show a different fragmentation behaviour indicating distinct structures for the fragment ions. Copyright © 2004 John Wiley & Sons, Ltd. [source] Macromolecular design via reversible addition,fragmentation chain transfer (RAFT)/xanthates (MADIX) polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Sébastien Perrier Abstract Among the living radical polymerization techniques, reversible addition,fragmentation chain transfer (RAFT) and macromolecular design via the interchange of xanthates (MADIX) polymerizations appear to be the most versatile processes in terms of the reaction conditions, the variety of monomers for which polymerization can be controlled, tolerance to functionalities, and the range of polymeric architectures that can be produced. This review highlights the progress made in RAFT/MADIX polymerization since the first report in 1998. It addresses, in turn, the mechanism and kinetics of the process, examines the various components of the system, including the synthesis paths of the thiocarbonyl-thio compounds used as chain-transfer agents, and the conditions of polymerization, and gives an account of the wide range of monomers that have been successfully polymerized to date, as well as the various polymeric architectures that have been produced. In the last section, this review describes the future challenges that the process will face and shows its opening to a wider scientific community as a synthetic tool for the production of functional macromolecules and materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43:5347,5393, 2005 [source] Social and population structure of a gleaning bat, Plecotus auritusJOURNAL OF ZOOLOGY, Issue 1 2000A. C. Entwistle Abstract Brown long-eared bats Plecotus auritus occupying 30 summer roosts in north-east Scotland were studied over 15 years. During this time 1365 bats were ringed, and a further 720 recaptures were made. Individual bats showed a high degree of roost fidelity, returning to one main roost site; < 1% of recaptured bats had moved among roost sites, and all recorded movements (n= 5) were < 300 m. Adults of both sexes were loyal to the roost sites at which they were first captured, indicating long-term use of roosts. At least some juveniles (n= 32) of both sexes returned to the natal roost. Mark,recapture estimates indicated that colonies of this species were substantially larger (c. 30,50 individuals) than assumed in previous studies. Plecotus auritus differs from most other temperate zone, vespertilionid species in that there was no evidence of sexual segregation during summer, with males present in all colonies throughout the period of occupancy. Population structure in summer seems to be consistent with a metapopulation model, with discrete sub-populations showing minimal interchange. The group size, colony composition and population structure described in this species may be associated with the wing shape (particularly aspect ratio) and foraging behaviour of P. auritus. It is postulated that relative motility, linked to wing structure, may affect the distribution of individuals, and may have implications for the genetic structure of this species. Correlations between aspect ratio and both colony size and migratory behaviour, across British bat species, indicate that wing shape could be an important factor contributing to patterns of social behaviour and genetic structuring in bats. [source] Paired donor interchange to avoid ABO-incompatible living donor liver transplantation,LIVER TRANSPLANTATION, Issue 4 2010See Ching Chan We report an emergency paired donor interchange living donor liver transplant performed on January 13, 2009. The 4 operations (2 liver transplants) were performed simultaneously. The aim was to avoid 2 ABO-incompatible liver transplants. One recipient in acute liver failure underwent transplantation in a high-urgency situation. The abdomen of the other recipient had severe adhesions from previous spontaneous bacterial peritonitis that rendered the recipient operation almost impossible. The ethical and logistical issues are discussed. Approaches adopted in anticipation of potential adverse outcomes are explained in view of the higher donor and recipient mortality and morbidity rates in comparison with kidney transplantation. Liver Transpl , 2010. © 2010 AASLD. [source] Characterization of New Amphiphilic Block Copolymers of N -Vinyl Pyrrolidone and Vinyl Acetate, 1 , Analysis of Copolymer Composition, End Groups, Molar Masses and Molar Mass Distributions,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2010Nick Fandrich Abstract New amphiphilic block copolymers consisting of N -vinyl pyrrolidone and vinyl acetate were synthesized via controlled radical polymerization using a reversible addition/fragmentation chain transfer (RAFT)/macromolecular design via the interchange of xanthates (MADIX) system. The synthesis was carried out in 1,4-dioxane as process solvent. In order to get conclusions on the mechanism of the polymerization the molecular structure of formed copolymers was analysed by means of different analytical techniques. 13C NMR spectroscopy was used for the determination of the monomer ratios. End groups were analysed by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This technique was also used to determine possible fragmentations of the RAFT end groups. By means of a combination of size exclusion chromatography, 13C NMR and static light scattering molar mass distributions and absolute molar masses could be analysed. The results clearly show a non-ideal RAFT mechanism. [source] Living Polymerization of N,N -Diphenylacrylamide with Triisobutylaluminum,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 18 2005Yeon Cu Kim Abstract Summary:N,N -Diphenylacrylamide was polymerized in a living fashion with triisobutylaluminum in THF at 0,°C. The polymerization results showed an increase of molecular weight proportional to the amount of monomer consumed and a first-order kinetics at ,78,°C. The intermediates obtained with excess initiator at ,78,°C revealed that the polymerization was initiated through 1,4-addition of hydride from a triisobutyl group in the triisobutylaluminum and then proceeded through aluminum-oxygen bond interchange. N,N -Diphenylacrylamide was polymerized in a living fashion with triisobutylaluminum in THF at 0,°C. [source] Zirconocene-catalysed propene polymerisation: kinetics, mechanism, and the role of the anionMACROMOLECULAR SYMPOSIA, Issue 1 2004Fuquan Song Abstract The olefin polymerisation activity of metallocene catalysts strongly depends on the counteranion provided by the activator system. The relative activities of a number of new diborate anions [Z(BAr3)2], have been quantified (Z = CN, NH2, N(CN)2; Ar = C6F5 or o -C6F4C6F5). The kinetic parameters for the initiation, propagation and termination steps of propene polymerisations catalysed by (SBI)ZrCl2 have been determined using quenched-flow kinetic and batch techniques [SBI = rac -Me2Si(1-Ind)2]. Comparison of two activator systems, (i) CPh3[B(C6F5)4] / triisobutylaluminium (TIBA) and (ii) methylaluminoxane (MAO) shows, surprisingly, that the concentration of species actively involved in chain growth at any one time is comparable for both systems, although the MAO-activated catalyst is about 20 times less active than the borate system. It is concluded that the counteranion remains sufficiently strongly bound to the metal centre throughout the chain growth sequence to modulate the energetics of monomer insertion. A model suggesting that the monomer binding follows an associative interchange (Ia) mechanism is proposed. [source] Detection of platinum dihydride bisphosphine complexes and studies of their reactivity through para -hydrogen-enhanced NMR methodsMAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2008Cyril Godard Abstract In-situ NMR studies on the reactions of Pt{CH2 = CHSi(Me)2}2O)(PCy3) with phosphines, HSiEt3 and - hydrogen or Pt(L)(L,)(Me)2 alone enable the detection of cis -Pt(L)(L,)(H)2 [L = PCy3 and L, = PCy2H, PPh3 or PCy3] which then undergo hydride site interchange and H2 reductive elimination on the NMR timescale. Copyright © 2008 John Wiley & Sons, Ltd. [source] Low-temperature 1H and 13C NMR spectra of N -substituted 1,2,3,4-tetrahydropyrazino[1,2- a]indolesMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2005Alan R. Katritzky Abstract The temperature-dependent 1H and 13C NMR spectra of 2-(2-butynyl)-10-methyl-1,2,3,4-tetrahydropyrazino[1,2- a]indole (4) (as a representative example of 1,9) in CFCl3 + CD2Cl2 solution are described and discussed. Below 183 K, the hexahydropyrazine ring inversions become slow on the NMR time-scale and 4 exists in principle as two conformational diastereomers. In fact, only one was observed with the N-2 substituent in an equatorial position as shown by a low-temperature NOESY experiment. The energy barrier for conformational interchange was calculated from NMR data to be 8.3 kcal mol,1 (1 kcal = 4.184 kJ), in agreement with quantum chemical calculations. Unambiguous assignments for all proton and carbon resonances of 1,9 were made using 1D (APT, DEPT, NOE difference) and 2D (COSY, NOESY, gHMQC, gHMBC) NMR techniques. Copyright © 2005 John Wiley & Sons, Ltd. [source] Use of the wavelet method for analyzing electrochemical noise dataMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2007O. Duran This research paper shows the application of the mathematical tool "wavelet's" to be used in the interpretation and analysis of electrochemical noise signals. The Fast Fourier Transformation (FFT) is one of the most commonly used techniques for analyzing electrochemical noise. But the application of this methodology to the analysis of stochastic signals does not allow their interpretation in a suitable way. The wavelet's methodology carries out the analysis by means of the construction of finite base functions. In several studies, it has been found out that the function that is closest to the electrochemical oscillations is the one called "coiflets," which presents a similar geometry to what it is observed when an ionic,electronic interchange occurs during an electrochemical interphase. The analysis that appears here was implemented using the toolbox "LabViewÔ." [source] From bacterial avirulence genes to effector functions via the hrp delivery system: an overview of 25 years of progress in our understanding of plant innate immunityMOLECULAR PLANT PATHOLOGY, Issue 6 2009JOHN W. MANSFIELD SUMMARY Cloning the first avirulence (avr) gene has led not only to a deeper understanding of gene-for-gene interactions in plant disease, but also to fundamental insights into the suppression of basal defences against microbial attack. This article (focusing on Pseudomonas syringae) charts the development of ideas and research progress over the 25 years following the breakthrough achieved by Staskawicz and coworkers. Advances in gene cloning technology underpinned the identification of both avr and hrp genes, the latter being required for the activation of the defensive hypersensitive reaction (HR) and pathogenicity. The delivery of Avr proteins through the type III secretion machinery encoded by hrp gene clusters was demonstrated, and the activity of the proteins inside plant cells as elicitors of the HR was confirmed. Key roles for avr genes in pathogenic fitness have now been established. The rebranding of Avr proteins as effectors, proteins that suppress the HR and cell wall-based defences, has led to the ongoing search for their targets, and is generating new insights into the co-ordination of plant resistance against diverse microbes. Bioinformatics-led analysis of effector gene distribution in genomes has provided a remarkable view of the interchange of effectors and also their functional domains, as the arms race of attack and defence drives the evolution of microbial pathogenicity. The application of our accrued knowledge for the development of disease control strategies is considered. [source] | |||||||||||||||||||||||||||||||