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General Conclusions (general + conclusion)
Selected AbstractsExamining understanding, acceptance, and support for the biorefinery concept among EU policy-makersBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 3 2009Philip Peck Abstract This paper outlines how an understanding of the processes of building cognitive and sociopolitical legitimacy is relevant to the formation of a biorefining sector. First we describe a number of theoretical insights into challenges faced by emerging industries and how these can relate to the formation of a biorefining sector. Second, we present the conduct and results of an initial exploration of understanding, acceptance, and support for the biorefinery concept among a sample of actors in the EU policy community. General conclusions of this study are then provided in these two areas. Addressing theory versus evidence from the fi eld, it is found that many phenomena predicted by theory indeed appear in the empirical results and seem immediately relevant to the formative biorefining industry. Analysis of the perceptions of members of the policy community toward biorefinery-related environmental, social, policy, reputational and policy issues reveals that there are a number of areas where prompt action from the political and scientifi c communities could yield signifi cant benefi ts. We conclude that theories enfolding the concepts of cognitive and sociopolitical legitimacy are relevant to discussions of biofuels, bioproducts and biorefining. Importantly, proponents of the biorefinery concept can draw upon a broad body of knowledge generated in both related and non-related industries, to support their work reducing barriers to the emergence of commercial biorefineries. A key area in this regard will be improved communication of biorefinery contributions to sustainable development. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source] ECONOMIC DEPRIVATION AND CHANGES IN HOMICIDE ARREST RATES FOR WHITE AND BLACK YOUTHS, 1967,1998: A NATIONAL TIME-SERIES ANALYSIS,CRIMINOLOGY, Issue 3 2001STEVEN F. MESSNER Using time-series techniques with national data for 1967,98, we model the effects on changes in age-race-specific arrest rates of changes in indicators of economic deprivation. A measure of child poverty is positively related to juvenile arrest rates for both races, whereas changing unemployment (lagged) yields a surprising negative effect on youth offending. Measures of intraracial income inequality are also associated with changes in juvenile arrest rates, but the effects differ by race. Between-race inequality is unrelated to changes in arrest rates for both races. Our general conclusion is that fluctuations in juvenile homicide offending over recent decades can be understood, at least in part, with reference to the macro-economic environment confronting young people and their families. [source] PHYLOGENETIC COMPARATIVE ANALYSIS OF LIFE-HISTORY VARIATION AMONG POPULATIONS OF THE LIZARD SCELOPORUS UNDULATUS:AN EXAMPLE AND PROGNOSISEVOLUTION, Issue 3 2004Peter H. Niewiarowski Abstract Over the past 15 years, phylogenetic comparative methods (PCMs) have become standard in the study of life-history evolution. To date, most studies have focused on variation among species or higher taxonomic levels, generally revealing the presence of significant phylogenetic effects as well as residual variation potentially attributable to adaptive evolution. Recently, population-level phylogenetic hypotheses have become available for many species, making it possible to apply PCMs directly to the level at which experiments are typically used to test adaptive hypotheses. In this study, we present the results of PCMs applied to life-history variation among populations of the widespread and well-studied lizard Sceloporus undulatus. Using S. undulatus (which may represent four closely related species) as an example, we explore the benefits of using PCMs at the population level, as well as consider the importance of several thorny methodological problems including but not limited to nonindependence of populations, lack of sufficient variation in traits, and the typically small sample sizes dictated by the difficulty of collecting detailed demographic data. We show that phylogenetic effects on life-history variation among populations of S. undulatus appear to be unimportant, and that several classic trade-offs expected by theory and revealed by many interspecific comparisons are absent. Our results suggest that PCMs applied to variation in life-history traits below the species level may be of limited value, but more studies like ours are needed to draw a general conclusion. Finally, we discuss several outstanding problems that face studies seeking to apply PCMs below the species level. [source] WITHIN-HOST POPULATION DYNAMICS AND THE EVOLUTION OF MICROPARASITES IN A HETEROGENEOUS HOST POPULATIONEVOLUTION, Issue 2 2002Vitaly V. Ganusov Abstract Why do parasites harm their hosts? The general understanding is that if the transmission rate and virulence of a parasite are linked, then the parasite must harm its host to maximize its transmission. The exact nature of such trade-offs remains largely unclear, but for vertebrate hosts it probably involves interactions between a microparasite and the host immune system. Previous results have suggested that in a homogeneous host population in the absence of super- or coinfection, within-host dynamics lead to selection of the parasite with an intermediate growth rate that is just being controlled by the immune system before it kills the host (Antia et al. 1994). In this paper, we examine how this result changes when heterogeneity is introduced to the host population. We incorporate the simplest form of heterogeneity,random heterogeneity in the parameters describing the size of the initial parasite inoculum, the immune response of the host, and the lethal density at which the parasite kills the host. We find that the general conclusion of the previous model holds: parasites evolve some intermediate growth rate. However, in contrast with the generally accepted view, we find that virulence (measured by the case mortality or the rate of parasite-induced host mortality) increases with heterogeneity. Finally, we link the within-host and between-host dynamics of parasites. We show how the parameters for epidemiological spread of the disease can be estimated from the within-host dynamics, and in doing so examine the way in which trade-offs between these epidemiological parameters arise as a consequence of the interaction of the parasite and the immune response of the host. [source] Self-image and burnout in psychiatric staffJOURNAL OF PSYCHIATRIC & MENTAL HEALTH NURSING, Issue 5 2000M. Jeanneau phd Burnout was tested for in 754 mental health workers and related to self-image as assessed with Structural Analysis of Social Behavior (SASB, Benjamin 1974). A positive relation was found between burnout and negative self-image, and between the experience of personal accomplishment and positive self-image. Compared to self-image, gender, age and work setting did not explain any variance in burnout. Highly burned-out persons had a significantly more negative self-image than staff who had rated themselves as low burnout. Finally, the relation between self-image and burnout was studied in 210 subjects who had completed their self-image ratings one year before burnout was measured, with the same results: a negative self-image was related to higher burnout one year later. One general conclusion is that a tendency in staff to treat themselves in negative ways may function as a negative filter for coping with difficulties at work and thus be a risk factor for burnout. [source] An Analysis of the Integration of Strategic Sourcing and Negotiation PlanningJOURNAL OF SUPPLY CHAIN MANAGEMENT, Issue 4 2003Larry R. Smeltzer SUMMARY Initially, strategic sourcing is defined as an integrated, seven-step process that includes the negotiation plan. Research questions are then proposed to determine the extent to which negotiation is part of the integrated sourcing process. To answer the research questions, the strategic sourcing process and negotiation plan are evaluated in 29 cases. In 14 of the 29 cases, strategic sourcing was completed and integrated into the negotiation plan. This is just under half of the cases, which led to the general conclusion that negotiation is not well integrated with the other strategic sourcing processes. Additional findings indicated the appropriate negotiation style was used in only 64 percent of the cases, with most mismatches occurring when an integrative style was used instead of the more appropriate distributive style. Managerial and research implications of the findings are presented and discussed. [source] Perspectives on the Past: A Study of the Spatial Perspectival Characteristics of Recollective MemoriesMIND & LANGUAGE, Issue 2 2007DOROTHEA DEBUS I begin by considering the ,Past-Dependency-Claim', which states that every recollective memory (or ,R-memory') has its spatial perspectival characteristics in virtue of the subject's present awareness of the spatial perspectival characteristics of a relevant past perceptual experience. Although the Past-Dependency-Claim might for various reasons seem particularly attractive, I show that it is false. I then proceed to develop and defend the ,Present-Dependency-Claim', namely the claim that the spatial perspectival characteristics of an R-memory depend on the spatial perspectival characteristics of perceptual experiences that the subject has at the time at which the R-memory occurs. Lastly, I discuss the phenomenon of so-called ,observer-memories', which presents a special challenge for any attempt to account for the spatial perspectival characteristics of R-memories. I argue that we have no good reason to deny that the relevant experiences should count as memories, and I show that we can account for the spatial perspectival characteristics of observer-memories with the help of the ,Present-Dependency-Claim'. More generally, the paper shows that certain events that occur in a subject's mental life (namely, a subject's R-memories) are necessarily dependent on other events that occur in the relevant subject's mental life (namely, on certain perceptual experiences). This more general conclusion in turn should be relevant for any attempt to develop an appropriate account of a subject's mental life as a whole. [source] The nature of high-redshift galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001Rachel S. Somerville Using semi-analytic models of galaxy formation set within the cold dark matter (CDM) merging hierarchy, we investigate several scenarios for the nature of the high-redshift ) Lyman-break galaxies (LBGs). We consider a ,collisional starburst' model in which bursts of star formation are triggered by galaxy,galaxy mergers, and find that a significant fraction of LBGs are predicted to be starbursts. This model reproduces the observed comoving number density of bright LBGs as a function of redshift and the observed luminosity function at and with a reasonable amount of dust extinction. Model galaxies at have star formation rates, half-light radii, colours and internal velocity dispersions that are in good agreement with the data. Global quantities such as the star formation rate density and cold gas and metal content of the Universe as a function of redshift also agree well. Two ,quiescent' models without starbursts are also investigated. In one, the star formation efficiency in galaxies remains constant with redshift, while in the other, it scales inversely with disc dynamical time, and thus increases rapidly with redshift. The first quiescent model is strongly ruled out, as it does not produce enough high-redshift galaxies once realistic dust extinction is accounted for. The second quiescent model fits marginally, but underproduces cold gas and very bright galaxies at high redshift. A general conclusion is that star formation at high redshift must be more efficient than locally. The collisional starburst model appears to accomplish this naturally without violating other observational constraints. [source] Novel and recurrent germline LEMD3 mutations causing Buschke,Ollendorff syndrome and osteopoikilosis but not isolated melorheostosisCLINICAL GENETICS, Issue 6 2009Y Zhang Mutations in the LEMD3 gene were recently incriminated in Buschke,Ollendorff syndrome (BOS) and osteopoikilosis, with or without melorheostosis. The relationship of this gene with isolated sporadic melorheostosis is less clear. We investigated LEMD3 in a two-generation BOS family showing an extremely variable expression of the disease, in a sporadic patient with skin features of BOS, and in an additional subject with isolated melorheostosis. We identified two different mutations, both resulting in a premature stop codon, in the two cases of BOS. The mutation (c.2564G>A) reported in the familial case is novel, while that observed in the sporadic case (c.1963C>T) has been previously reported in an American woman with osteopoikilosis and melorheostosis who had a family history of isolated osteopoikilosis. The search for mutations in DNA extracted from the peripheral blood, as well as skin and bone biopsies of the patient with melorheostosis failed to identify any pathogenic change. Our results further expand the LEMD3 mutation repertoire, corroborate the extreme interfamilial and intrafamilial clinical variability of LEMD3 mutations, and underline the lack of a clear phenotype,genotype correlation in BOS. The present study supports the general conclusion that LEMD3 mutations do not contribute to isolated sporadic melorheostosis. The genetic or epigenetic influences that are responsible for the development of melorheostosis require further investigation. [source] The effect of texture on the pass/fail colour tolerances of injection-molded plasticsCOLOR RESEARCH & APPLICATION, Issue 1 2007Ingrid Ariño Abstract The effect of surface texture on the pass/fail colour tolerance region was estimated using acrylonitrile,butadiene,styrene injection-molded plaques in three different colours and with different surface textures. Variations in the measured colour coordinates due to differences in texture for three selected colours were observed using the specular component excluded mode (SCE) of the spectrophotometer. Such variations could not, however, be clearly distinguished in the specular component included mode. The colour tolerance regions were assessed through a combination of colour measurement and a psychometric study involving 35 observers. The limits of acceptance of colour differences varied substantially with the surface texture. In some cases, the observers accepted a larger colour difference for the textured than for the smooth surface, whereas in other cases, the reverse situation was noted. Thus, no general conclusion regarding the influence of texture on the tolerance region can be drawn, since the acceptable differences were colour- and/or surface texture-dependent. In the case of textured surfaces, measurements made in the SCE mode of the spectrophotometer appear to be more meaningful for assessing perceived colour differences and tolerance regions. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 47,54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20284 [source] The management of incipient or suspicious occlusal caries: a decision-tree analysisCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 5 2008Ben Balevi Abstract,,, Objective:, To perform a comprehensive decision-tree analysis for the management of the suspicious/incipient occlusal lesion on a molar tooth. Methods:, A quantitative decision tree was constructed to assess the expected utility value of three global strategies to dentally manage the incipient or suspicious occlusal carious lesion. Result:, A preventive strategy offered an optimal expected utility value (0.98 utile) compared with the other two strategies of visual inspection (0.84 utile) or referring to one of four diagnostic tests (0.74,0.82 utile). Conclusion:, Although the general conclusion of this analysis agrees with current recommendations, this analysis offers a more complete mathematical model that provides a unified value for each strategy (i.e. expected utility value) thus allowing for complex quantitative comparison between strategies. This paper provides a specific example of how decision-tree analysis can be a powerful tool in guiding dental practice. [source] Gene,environment interactions and alcohol use and dependence: current status and future challengesADDICTION, Issue 6 2009Carmen S. Van Der Zwaluw ABSTRACT Aim To discuss the current status of gene,environment interaction research with regard to alcohol use and dependence. Further, we highlight the difficulties concerning gene,environment studies. Methods Overview of the current evidence for gene,environment interactions in alcohol outcomes, and of the associated challenges in gene,environment studies. Results Attention to the causative roles of gene,environment interactions in alcohol use and dependence is increasing. Studies with twin designs are beginning to examine gene-shared environment effects, and animal studies have investigated gene,environment interaction effects on alcohol intake in primates. Thirteen studies incorporated gene,environment interactions in examining alcohol use or dependence in humans. These studies held a variety of candidate genes and environmental risk factors and their heterogeneity made it impossible to draw firm general conclusions. Conclusions Challenges for future gene,environment studies are abundant, and consist of, for example, the development of clear theoretical assumptions about neurobiological mechanisms and the recruitment of large longitudinal samples that already start in childhood. Replication is essential to prevent an overload of false-positive results. Despite the difficulties, it is crucial to include gene,environment interactions in future studies in order to unravel the aetiological factors of human alcohol outcomes. [source] Comprehensive proteome analysis by chromatographic protein prefractionationELECTROPHORESIS, Issue 7-8 2004Pierre Lescuyer Abstract Protein copy number is distributed from 7 to 8 orders of magnitude in cells and probably up to 12 orders of magnitude in plasma. Classical silver-stained two-dimensional electrophoresis (2-DE) can only display up to four orders of magnitude. This is a major drawback since it is assumed that most of the regulatory proteins are low-abundance gene products. It is thus clear that the separation of low copy number proteins in amounts sufficient for postseparation analysis is an important issue in proteome studies to complete the comprehensive description of the proteome of any given cell type. The visualization of a polypeptide on a 2-DE gel will depend on the copy number, on the quantity loaded onto the gel and on the method of detection. As the amount of protein that can be loaded onto a gel is limited, one efficient solution is to fractionate the sample prior to 2-DE analysis. Several approaches exist including subcellular fractionation, affinity purification and chromatographic and electrophoretic protein prefractionation. The chromatographic step adds a new dimension in the protein separation using specific protein properties. It allows proteins to be adsorbed to a surface and eluted differentially under certain conditions. This review article presents studies combining chromatography-based methods to 2-DE analysis and draws general conclusions on this strategy. [source] Visiting America: notes from an alcohol-focused study tour made in 1961ADDICTION, Issue 12 2008Griffith Edwards ABSTRACT Aims This paper has as its focus a study tour made by the author in 1961. Diary notes are used to capture a historical moment in the evolution of alcohol studies. The paper will argue for the continuing value today of such experiences in support of career development and the building of ,the field'. Data sources Diary notes and personal recollection. Findings The United States was at the time more active than the United Kingdom in its response to alcohol problems. There was, however, a disjunction between the elite American research world and the world of action, which was not informed greatly by research. For the most part, treatment services and prevention strategies seemed driven by opinion rather than by evidence. But at the level of serious scientific endeavour there was opportunity to meet influential figures including Seldon Bacon, Morris Chafetz, Milton Gross, Ebbe Curtis Hoff, Harris Isbell, E. M. Jellinek, Mark Keller, Benjamin Kissen, Robert Strauss, Wolf Schmidt and Abraham Wikler, who generously made their time available. Conclusions These diary notes provide a snapshot of a field of endeavour at a critical stage of transition from uninformed assumptions towards establishment of a research base which can inform public action. The visit was of tangible value to the visitor in several different identified ways. Such an experience is inevitably time-bound and personal, but there are general conclusions to be drawn as to the benefits which will be derived from early travel opportunities in a field such as alcohol studies, which is all too easily culture-bound in its horizons and assumptions. Alcohol science needs to be more reflective on its history and the mechanisms that help to make it happen. [source] Assessment of multiple implicit self-concept dimensions using the Extrinsic Affective Simon Task (EAST)EUROPEAN JOURNAL OF PERSONALITY, Issue 6 2004Sarah Teige This study explored the psychometric properties of the Extrinsic Affective Simon Task (EAST; De Houwer, 2003a) as adapted for the measurement of the implicit self-concept of personality. The EAST was adapted to allow the simultaneous assessment of the three traits shyness, anxiousness, and angriness. In order to test the EAST's psychometric properties, 100 participants completed a trait EAST, Implicit Association Tests (IATs), and direct self-ratings. The EAST showed low internal consistencies and correlated neither with the IATs nor with the direct measures. The main problem of the EAST, namely its low reliability, is discussed, and general conclusions regarding the indirect assessment of the personality self-concept by EASTs are derived. Copyright © 2004 John Wiley & Sons, Ltd. [source] Listening Comprehension Strategies: A Review of the LiteratureFOREIGN LANGUAGE ANNALS, Issue 4 2004Jane E. Berne The present study seeks to build upon two previous reviews of listening comprehension strategies research. Of particular interest in this review are studies dealing with the types of cues used by listeners, the sequence of listening, differences between more- and less-proficient listeners, listening strategy instruction, strategies versus tactics, and identifying listening problems. This review first summarizes the findings of a number of studies in each of these areas. Based on these summaries, the review then posits some general conclusions and suggests directions for future research. The review demonstrates that listening comprehension strategies have been and continue to be a very fruitful area for researchers to explore. [source] Design and comparison of turbo codes under frame-length and code-rate constraintsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2006Franco Chiaraluce Abstract When the performances of error-correcting codes for space communications are investigated, with the aim to translate them into practical recommendations, comparison among different schemes is usually a very difficult task. As a matter of fact, these comparisons rarely yield general conclusions. On the other hand, most practical space applications impose strong constraints on the code parameters, which have important effects on code selection. In this paper, we show a methodology and several examples of design and comparison, derived under fixed constraints imposed by the system application on the frame-length and the code-rate. CCSDS Earth observation missions requiring both large coding gains and high spectral efficiency are considered as a case study. Though referred to this specific space mission framework, the presented study is quite general and applies to many other digital communication systems; e.g. for wireless or wired applications where similar constraints exist but are often not taken in due consideration by the designer of the error-correcting schemes. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Role of Charge Localization in Current-Driven DynamicsISRAEL JOURNAL OF CHEMISTRY, Issue 1 2007Ryan Jorn We explore the role of charge localization in current-triggered, resonance-mediated, dynamical events in molecular junctions. To that end we use a simple model for a molecular rattle, a Li+C9H,9 zwitterion attached between two metal clusters. By varying the size of the metal clusters we systematically vary the degree of delocalization of the electronic orbitals underlying the resonant current, and thus can draw general conclusions regarding the effect of delocalization on dynamical processes induced by resonance inelastic current in molecular electronics. In the small cluster limit, we find interesting quantum dynamics in the nuclear subspace, corresponding to coherent tunneling of the wave packet through the barrier of an asymmetric double-well potential. These dynamics are rapidly damped with increasing charge delocalization in extended systems. [source] The Plausibility of Defensive Projection: A Cognitive AnalysisJOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 3 2003Maria Miceli This paper provides an analysis of the cognitive processes implied in the ego defense known as projection. Projection is first placed in the context of the general cognitive processes of attribution and ascription. Then we address defensive projection, and identify its distinctive features. In particular, whereas general projection consists in the ascription of one's own mental attitudes to others, defensive projection implies one's rejection (via denial or repression) of the ascribed mental states, and ascription is a means for supporting this rejection. We try to understand how and why ascription is functional to rejection. Then, we examine a few types of defensive projection, and identify the main components and steps in the projective process. Finally, we draw some general conclusions. [source] Scheduling considerations for a branching transit routeJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2004Aichong Sun This paper addresses the impacts of different scheduling alternatives for a branching transit route. It examines different schedule alternatives that might be used to optimize the route performance in terms of the passenger traveling time distributed among branch passengers and trunk-line passengers. The schedule alternatives considered include transit vehicle allocation to different branches, offset shifting across vehicles on different branches, and vehicle holding (slack time) in the transit vehicle schedule. With these variables, several vehicle schedules are devised and examined based on a wide variety of possible passenger boarding scenarios using deterministic service models. Test outcomes provide general conclusions about the performance of the strategies. Vehicle assignment leading to even headways among branches is generally preferred for the case of low passenger demand. However, when passenger demand is high, or the differences between the passenger demands on branches are significant, unequal vehicle assignment will be helpful to improve the overall route performance. Holding, as a proactive strategy in scheduling, has the potential to be embedded into the schedule as a type of slack time, but needs further evidence and study to determine the full set of conditions where it may be beneficial. Offset shifting does not show sufficient evidence to be an efficient strategy to improve route performance in the case of low or high passenger demand. [source] Anthropogenic impacts on lake and stream ecosystems, and approaches to restorationJOURNAL OF APPLIED ECOLOGY, Issue 6 2007MARTIN SØNDERGAARD Summary 1Freshwater ecosystems have long been affected by numerous types of human interventions that have a negative impact on their water quality and ecological state. Fortunately, in most western countries the input of sewage to freshwater systems has been reduced, but hydromorphological alterations, eutrophication-related turbidity and loss of biodiversity remain major problems in many parts of the world. Such impacts prevent the achievement of a high or good ecological state, as defined by the European Water Framework Directive (WFD) or other standards. 2This paper synthesizes and links the findings presented in the seven papers of this special profile, focusing on the effects of anthropogenic stressors on freshwater ecosystems and on how to maintain and restore ecological quality. The papers cover a broad range of research areas and methods, but are all centred on the relationship between dispersal barriers, the connectivity of waterways and the restoration of rivers and lakes. 3The construction of dams and reservoirs disturbs the natural functioning of many streams and rivers and shore-line development around lakes may reduce habitat complexity. New methods demonstrate how reservoirs may have a severe impact on the distribution and connectivity of fish populations, and new techniques illustrate the potential of using graph theory and connectivity models to illustrate the ecological implications. Hydromorphologically degraded rivers and streams can be restored by addition of wood debris, but ,passive' restoration via natural wood recruitment may be preferable. The most cost-effective way to restore streams may also include information campaigns to farmers on best management practices. Removal of zooplanktivorous fish often has marked positive effects on trophic structure in lakes, but there is a tendency to return to turbid conditions after 8,10 years or less unless fish removal is repeated. 4Synthesis and applications. Development of new methods, as well as derivation of more general conclusions from reviewing the effects of previous restoration efforts, are crucial to achieve progress in applied freshwater research. The papers contained in this Special Profile contribute on both counts, as well as illustrating the importance of well-designed research projects and monitoring programmes to record the effects of the interventions. Such efforts are vital if we are to improve our knowledge of freshwater systems and to elaborate the best and most cost-effective recommendations. They may also help in achieving a good ecological state or potential in water bodies by 2015, as demanded by the European WFD. [source] Photocatalytic degradation for environmental applications , a reviewJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2002Dhananjay S Bhatkhande Abstract Photocatalysis is a rapidly expanding technology for wastewater treatment. In this review the chemical effects of various variables on the rate of degradation of different pollutants are discussed in detail. The effects of adsorption, temperature, intensity of light, pH, and the presence of anions, cations, etc have been specifically covered. A critical analysis of the available literature data has been made and some general conclusions have been drawn concerning the above mentioned effects. The need for more work on specific points has been brought out. © 2001 Society of Chemical Industry [source] How the choice of a computational model could rule the chemical interpretation: The Ni(II) catalyzed ethylene dimerization as a case studyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 5 2010Vincent Tognetti Abstract In this article, we present a critical study of the theoretical protocol used for the determination of the nickel(II) catalyzed ethylene dimerization mechanism, considered as a representative example of the various problems related to the modeling a catalytic cycle. The choice of an appropriate computational procedure is indeed crucial for the validity of the conclusions that will be drawn from the computational process. The influence of the exchange-correlation functional on energetic profiles and geometries, the role of the basis set describing the metal atom, as well as the importance of the chosen molecular model, have been thus examined in details. From the obtained results, some general conclusions and guidelines are presented, which could constitute useful warnings in modeling homogenous catalysis. Besides, the database constituted by our high-level calculations can be used within benchmarking procedures to assess the performances of new computational methods based on density functional theory. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [source] MHC studies in nonmodel vertebrates: what have we learned about natural selection in 15 years?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2003L. Bernatchez Abstract Elucidating how natural selection promotes local adaptation in interaction with migration, genetic drift and mutation is a central aim of evolutionary biology. While several conceptual and practical limitations are still restraining our ability to study these processes at the DNA level, genes of the major histocompatibility complex (MHC) offer several assets that make them unique candidates for this purpose. Yet, it is unclear what general conclusions can be drawn after 15 years of empirical research that documented MHC diversity in the wild. The general objective of this review is to complement earlier literature syntheses on this topic by focusing on MHC studies other than humans and mice. This review first revealed a strong taxonomic bias, whereby many more studies of MHC diversity in natural populations have dealt with mammals than all other vertebrate classes combined. Secondly, it confirmed that positive selection has a determinant role in shaping patterns of nucleotide diversity in MHC genes in all vertebrates studied. Yet, future tests of positive selection would greatly benefit from making better use of the increasing number of models potentially offering more statistical rigour and higher resolution in detecting the effect and form of selection. Thirdly, studies that compared patterns of MHC diversity within and among natural populations with neutral expectations have reported higher population differentiation at MHC than expected either under neutrality or simple models of balancing selection. Fourthly, several studies showed that MHC-dependent mate preference and kin recognition may provide selective factors maintaining polymorphism in wild outbred populations. However, they also showed that such reproductive mechanisms are complex and context-based. Fifthly, several studies provided evidence that MHC may significantly influence fitness, either by affecting reproductive success or progeny survival to pathogens infections. Overall, the evidence is compelling that the MHC currently represents the best system available in vertebrates to investigate how natural selection can promote local adaptation at the gene level despite the counteracting actions of migration and genetic drift. We conclude this review by proposing several directions where future research is needed. [source] In Vivo Gene Transfer Studies on the Regulation and Function of the Vasopressin and Oxytocin GenesJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2003D. Murphy Abstract Novel genes can be introduced into the germline of rats and mice by microinjecting fertilized one-cell eggs with fragments of cloned DNA. A gene sequence can thus be studied within the physiological integrity of the resulting transgenic animals, without any prior knowledge of its regulation and function. These technologies have been used to elucidate the mechanisms by which the expression of the two genes in the locus that codes for the neuropeptides vasopressin and oxytocin is confined to, and regulated physiologically within, specific groups of neurones in the hypothalamus. A number of groups have described transgenes, derived from racine, murine and bovine sources, in both rat and mouse hosts, that mimic the appropriate expression of the endogenous vasopressin and genes in magnocellular neurones (MCNs) of the supraoptic and paraventricular nuclei. However, despite considerable effort, a full description of the cis -acting sequences mediating the regulation of the vasopressin-oxytocin locus remains elusive. Two general conclusions have nonetheless been reached. First, that the proximal promoters of both genes are unable to confer any cell-specific regulatory controls. Second, that sequences downstream of the promoter, within the structural gene and/or the intergenic region that separates the two genes, are crucial for appropriate expression. Despite these limitations, sufficient knowledge has been garnered to specifically direct the expression of reporter genes to vasopressin and oxytocin MCNs. Further, it has been shown that reporter proteins can be directed to the regulated secretory pathway, from where they are subject to appropriate physiological release. The use of MCN expression vectors will thus enable the study of the physiology of these neurones through the targeted expression of biologically active molecules. However, the germline transgenic approach has a number of limitations involving the interpretation of phenotypes, as well as the large cost, labour and time demands. High-throughput somatic gene transfer techniques, principally involving the stereotaxic injection of hypothalamic neuronal groups with replication-deficient adenoviral vectors, are now being developed that obviate these difficulties, and which enable the robust, long-lasting expression of biologically active proteins in vasopressin and oxytocin MCNs. [source] The views of an advocatus dei: political marketing and its criticsJOURNAL OF PUBLIC AFFAIRS, Issue 3 2004Stephan C. Henneberg Abstract This paper addresses 11 statements of criticism of political marketing. These statements represent the most commonly voiced issues and were collected from marketers and political scientists. While marketing theorists are more concerned with the state of political marketing theory, political scientists concentrate much of their criticism on aspects of political marketing management as it is experienced in practice. Each statement is discussed and general conclusions are identified. While presenting the personal opinion of the author (advocatus dei), these conclusions and statements concerning political marketing should foster critical discourse on issues such as political marketing management, concepts and ethics. Copyright © 2004 Henry Stewart Publications [source] The use of topography-based parameters for the assessment and prediction of surface wearLUBRICATION SCIENCE, Issue 1 2000I. Sherrington Abstract This paper examines the use of surface parameters as ,tools' for assessing and predicting surface wear. It begins by briefly reviewing other work published on wear assessment based on entirely topography-based parameters, and concludes that other elements of surface condition are needed, in addition to topography, to assess and characterise the contact if topography-based parameters are to be employed to predict wear. This paper discusses why areal measurements of bearing area and plasticity index are suitable candidates as a basis for assessing and predicting surface wear, and outlines the potential value of using these parameters in conjunction with a wear equation. The validity of this suggestion is illustrated by some preliminary data from a series of pin-on-disc wear experiments involving areal assessments of the bearing area and plasticity index of the rough tip of a brass pin. Predictions of the first stage of a wear simulation are compared to experimental data, and the paper concludes by presenting some general conclusions and suggestions about how the work could be developed. [source] PRODUCTIVITY ACCOUNTING BASED ON PRODUCTION PRICESMETROECONOMICA, Issue 2 2010Matteo Degasperi ABSTRACT In this paper we propose a method of productivity accounting based on production prices. By using input,output tables from four major OECD countries between 1970 and 2000, we compute the associated wage,profit frontiers and the net national products, and from these we derive two measures of productivity growth based on production prices and a chosen numéraire. Our findings support the general conclusions in the existing literature on the productivity slowdown and later rebound, and supply new important insights to the extent and timing of these events. [source] Using phylochronology to reveal cryptic population histories: review and synthesis of 29 ancient DNA studiesMOLECULAR ECOLOGY, Issue 7 2009UMA RAMAKRISHNAN Abstract The evolutionary history of a population involves changes in size, movements and selection pressures through time. Reconstruction of population history based on modern genetic data tends to be averaged over time or to be biased by generally reflecting only recent or extreme events, leaving many population historic processes undetected. Temporal genetic data present opportunities to reveal more complex population histories and provide important insights into what processes have influenced modern genetic diversity. Here we provide a synopsis of methods available for the analysis of ancient genetic data. We review 29 ancient DNA studies, summarizing the analytical methods and general conclusions for each study. Using the serial coalescent and a model-testing approach, we then re-analyse data from two species represented by these data sets in a common interpretive framework. Our analyses show that phylochronologic data can reveal more about population history than modern data alone, thus revealing ,cryptic' population processes, and enable us to determine whether simple or complex models best explain the data. Our re-analyses point to the need for novel methods that consider gene flow, multiple populations and population size in reconstruction of population history. We conclude that population genetic samples over large temporal and geographical scales, when analysed using more complex models and the serial coalescent, are critical to understand past population dynamics and provide important tools for reconstructing the evolutionary process. [source] Primary productivity can affect mammalian body size frequency distributionsOIKOS, Issue 2 2001Birgitta Aava Frequency distributions of mammal body sizes in large-scale assemblages have often been found to show a positive skew. In an attempt to explain this pattern, a model has been put forward which incorporates energetic constraints on fitness and thereby predicts optimal body sizes corresponding to the mode of the distribution. A key assumption of the model is that energy is unlimited. However, if energy is limited, the input of energy into a herbivorous mammal community should influence the shape of the frequency distribution. Thus, I propose that increases in primary productivity will decrease the variation of body size and increase the mean body size in a distribution. So, in low-productivity environments we should see a predominance of small-sized species, but with a great variation of body sizes due to limitations of resources (energy). I tested this hypothesis using the herbivorous mammal fauna (rodents, bats and marsupials) in seven biomes of Australia. Because herbivorous marsupials generally are fairly large-bodied while rodents and bats are small-sized and because marsupials also have a different mode of reproduction from placental mammals, the hypothesis was also tested on placental mammals and marsupials separately. There was no clear mode for the entire assemblage in any biome, but as primary productivity increased, the variation of body masses decreased and the mean body mass of the distribution increased. Body mass distributions of both placental mammals and marsupials displayed clear modes. Placental mammals also showed an increase in mean body mass. The variation in body mass of marsupials was highest for the intermediately productive biomes. Primary productivity does seem to have some effect on mammalian body mass in this case, but the results here need to be complemented with studies of other assemblages before any general conclusions can be drawn. It is also important to distinguish which taxa are affected in a heterogeneous assemblage like the Australian herbivorous mammal fauna. [source] | |||||||||||||||||||||||||||||||