Home About us Contact
|
Home About us Contact | ||
|
|
||
Essential Aspect (essential + aspect)
Selected AbstractsProtein tyrosine phosphatases in Chaetopterus egg activationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5-6 2003Shantá D. Hinton Changes in protein tyrosine phosphorylation are an essential aspect of egg activation after fertilization. Such changes result from the net contributions of both tyrosine kinases and phosphatases (PTP). This study was conducted to determine what role(s) PTP may have in egg activation. We identified four novel PTP in Chaetopterus pergamentaceus oocytes, cpPTPNT6, cpPTPNT7, cpPTPR2B, and cpPTPR2A, that have significant homology to, respectively, human PTP,, -,, -D2 and -BAS. The first two are cytosolic and the latter two are transmembrane. Several PTP inhibitors were tested to see if they would affect Chaetopterus pergamentaceus fertilization. Eggs treated with ,-bromo-4-hydroxyacetophenone (PTP inhibitor 1) exhibited microvillar elongation, which is a sign of cortical changes resulting from activation. Those treated with Na3VO4 underwent full parthenogenetic activation, including polar body formation and pseudocleavage and did so independently of extracellular Ca2+, which is required for the Ca2+ oscillations that initiate development after fertilization. Fluorescence microscopy identified phosphotyrosine-containing proteins in the cortex and around the nucleus of vanadate-activated eggs, whereas in fertilized eggs they were concentrated only in the cortex. Immunoblots of vanadate-activated and fertilized eggs showed tyrosine hyperphosphorylation of approximately140 kDa protein. These results suggest that PTP most likely maintain the egg in an inactive state by dephosphorylation of proteins independent of the Ca2+ oscillations in the activation process. [source] Cascading effects of variation in plant vigour on the relative performance of insect herbivores and their parasitoidsECOLOGICAL ENTOMOLOGY, Issue 1 2002Tiit Teder Abstract 1. Consequences of variation in food plant quality were estimated for a system consisting of two monophagous noctuid herbivores and three ichneumonid parasitoids. 2. In a natural population, pupal weights of the herbivores in this system, Nonagria typhae and Archanara sparganii, were found to be highly variable. Pupal weights increased strongly and consistently with the increase in the vigour of the host plant, Typha latifolia, providing support for the plant vigour hypothesis. Correspondingly, as the moths do not feed as adults, a strong, positive correlation between host vigour and fecundity of the herbivores would be expected. 3. There were strong and positive relationships between adult body sizes of the parasitoids and the sizes of their lepidopteran hosts. Moreover, a direct, positive link between plant quality and parasitoid size was documented. 4. For all three parasitoids, cascading effects of plant quality on body size were weaker than for the herbivores. Differences in the importance of adult feeding and oviposition behaviour suggest that dependence of fitness on body size is also weaker in the parasitoids than in the moths. It is therefore concluded that the numerical response of the herbivore population to a change in plant quality should exceed the corresponding response in the parasitoids. 5. The results of this work imply that variation in plant variables may affect performance of different trophic levels to a different extent. It is suggested that the importance of adult feeding for the reproductive success (capital vs. income breeding strategies) in both herbivores and parasitoids is an essential aspect to consider when predicting responses of such a system to changes in plant quality. [source] Determinants and effects of foreign direct investment: evidence from German firm-level data*ECONOMIC POLICY, Issue 41 2005Claudia M. Buch SUMMARY FDI Firm-level evidence Foreign direct investment is an essential aspect of ,globalization' yet its empirical determinants are not well understood. What we do know is based either on poor data for a wide range of nations, or good data for the US and Swedish cases. In this paper, we provide evidence on the determinants of the activities of German multinational firms by using a newly available firm-level data set from the Deutsche Bundesbank. The specific goal of this paper is to demonstrate the relative role of country-level and firm-level determinants of foreign direct investment. We focus on three main questions: First, what are the main driving forces of German firms' multinational activities? Second, is there evidence that sector-level and firm-level factors shape internationalization patterns? Third, is there evidence of agglomeration effects in the foreign activities of German firms? We find that the market access motive for internationalization dominates. Firms move abroad mainly to gain better access to large foreign markets. Cost-saving motives, however, are important for some manufacturing sectors. Our results strongly suggest that firm-level heterogeneity has an important influence on internationalization patterns , as stressed by recent models of international trade. We also find positive agglomeration effects for the activities of German firms that stem from the number of other German firms that are active on a given foreign market. In terms of lessons for economic policy, our results show that lowering barriers to the integration of markets and encouraging the formation of human capital can promote the activities of multinational firms. However, our results related to the heterogeneity of firms and agglomeration tendencies show that it might be difficult to fine-tune policies directed at the exploitation of synergies and at the creation of clusters of foreign firms. , Claudia M. Buch, Jörn Kleinert, Alexander Lipponer and Farid Toubal [source] Viral encephalitis: a review of diagnostic methods and guidelines for managementEUROPEAN JOURNAL OF NEUROLOGY, Issue 5 2005I. Steiner Viral encephalitis is a medical emergency. The spectrum of brain involvement and the prognosis are dependent mainly on the specific pathogen and the immunological state of the host. Although specific therapy is limited to only several viral agents, correct immediate diagnosis and introduction of symptomatic and specific therapy has a dramatic influence upon survival and reduces the extent of permanent brain injury in survivors. We searched MEDLINE (National Library of Medicine) for relevant literature from 1966 to May 2004. Review articles and book chapters were also included. Recommendations are based on this literature based on our judgment of the relevance of the references to the subject. Recommendations were reached by consensus. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. Diagnosis should be based on medical history, examination followed by analysis of cerebrospinal fluid for protein and glucose contents, cellular analysis and identification of the pathogen by polymerase chain reaction (PCR) amplification (recommendation level A) and serology (recommendation level B). Neuroimaging, preferably by magnetic resonance imaging, is an essential aspect of evaluation (recommendation level B). Lumbar puncture can follow neuroimaging when immediately available, but if this cannot be obtained at the shortest span of time it should be delayed only in the presence of strict contraindications. Brain biopsy should be reserved only for unusual and diagnostically difficult cases. All encephalitis cases must be hospitalized with an access to intensive care units. Supportive therapy is an important basis of management. Specific, evidence-based, anti-viral therapy, acyclovir, is available for herpes encephalitis (recommendation level A). Acyclovir might also be effective for varicella-zoster virus encephalitis, gancyclovir and foscarnet for cytomegalovirus encephalitis and pleconaril for enterovirus encephalitis (IV class of evidence). Corticosteroids as an adjunct treatment for acute viral encephalitis are not generally considered to be effective and their use is controversial. Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management. [source] Living up to high standards and psychological distressEUROPEAN JOURNAL OF PERSONALITY, Issue 4 2008Nico W. Van Yperen Abstract We argue and demonstrate that setting high standards, an essential aspect of perfectionism, is not associated with maladaptive responses in and of itself. Rather, our findings suggest that people's responses to their perceptions that they consistently fail to meet their own standards are maladaptive. More importantly, in the present survey study (n,=,293), we extend previous research by showing that low personal standards and the perception that others are imposing high standards on the self operate in concert to strengthen the link between perceived discrepancy and psychological distress. Furthermore, in support of our moderation-mediation model, regression analyses provided evidence for the mediating role of generalised self-efficacy beliefs. Copyright © 2008 John Wiley & Sons, Ltd. [source] Growing decision trees in an ordinal settingINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 7 2003Kim Cao-Van Although ranking (ordinal classification/regression) based on criteria is related closely to classification based on attributes, the development of methods for learning a ranking on the basis of data is lagging far behind that for learning a classification. Most of the work being done focuses on maintaining monotonicity (sometimes even only on the training set). We argue that in doing so, an essential aspect is mostly disregarded, namely, the importance of the role of the decision maker who decides about the acceptability of the generated rule base. Certainly, in ranking problems, there are more factors besides accuracy that play an important role. In this article, we turn to the field of multicriteria decision aid (MCDA) in order to cope with the aforementioned problems. We show that by a proper definition of the notion of partial dominance, it is possible to avoid the counter-intuitive outcomes of classification algorithms when applied to ranking problems. We focus on tree-based approaches and explain how the tree expansion can be guided by the principle of partial dominance preservation, and how the resulting rule base can be graphically represented and further refined. © 2003 Wiley Periodicals, Inc. [source] Rethinking Social Security in Latin AmericaINTERNATIONAL SOCIAL SECURITY REVIEW, Issue 2-3 2005Indermit Gill In the past decade, many Latin American governments have radically restructured their old age income security systems, following the lead of Chile, which undertook its major pension reform in 1981. The defining characteristic of the reforms has been a shift in the basis of public pensions from social to individual responsibility: instead of the widely used system that "collectivized" or pooled the risk of being without the capacity to earn while aged, numerous countries in the region have adopted a system that relies on individual savings accounts. The reforms have maintained a role for a modified version of public pooling; this combination of individual and social savings to finance pensions is known as the "multipillar" approach. This article is based on a report prepared for the Office of the Chief Economist of the Latin America and Caribbean Region of the World Bank (Gill, Packard and Yermo, 2004).1 The report recognizes that the system of individual accounts, the essential aspect of the reform, has been a necessary and positive development, and one that is consistent with the economics of insurance and social welfare objectives. Beyond this recognition, however, the results of reform are much more complex. Each country has implemented its own version of the multipillar system. The article therefore draws on country evidence in order to determine: How has the new approach to public pensions in Latin America fared? In particular, have the changes left workers and their families in reform countries better off? The first section provides a brief description of the reforms. The second discusses the main macroeconomic concerns and effects. The third describes the impact on coverage levels, and other social welfare implications. The fourth evaluates the stagnation of coverage levels and presents various possible explanations. The fifth makes specific proposals to improve the multipillar pension system in Latin America. The last section concludes. [source] A systematic review of studies assessing and facilitating attitudes towards professionalism in medicineMEDICAL EDUCATION, Issue 8 2007Vikram Jha Objectives, An essential aspect of medical education is to facilitate the development and assessment of appropriate attitudes towards professionalism in medicine. This systematic review provides a summary of evidence for measures that have been used to assess these attitudes and their psychometric rigour. It also describes interventions that have been found to be effective in changing such attitudes. Methods, MEDLINE, EMBASE, ERIC, PsychINFO, Sociological Abstracts and CINAHL were searched from the respective start date of each database to May 2006. Three key journals and reference lists of existing reviews were also searched. Articles that were published in English and reported primary empirical research measuring medical students' attitudes towards medical professionalism were included. The findings are integrated in narrative structured in such a way as to address the research questions. Results, A total of 97 articles were included in the review. Most measures of attitudes assessed attitudes towards attributes of professionalism such as ethical issues, the patient,doctor relationship and cultural issues. Fourteen studies measured attitudes towards professionalism as a whole and 44 studies reported both the reliability and validity of measures. No interventions reported a change in attitudes over time. Conclusions, There is little evidence of reported measures that are effective in assessing attitudes towards professionalism in medicine as a whole. Likewise, there is scant evidence of interventions that influence attitude change over a period of time. Future studies should take into account the need to measure more global attitudes rather than attitudes towards specific issues in professionalism and the need to track attitudes throughout the curriculum. [source] Is Kaldor's Theory of Money Supply Endogeneity Still Relevant?METROECONOMICA, Issue 1 2001Giancarlo Bertocco Contemporary monetary theory is characterized by the predominance of the monetarist thesis. Paradoxically, the widespread acceptance of the monetarists' conclusions has coincided with the disappearance of the stable relation between money stock and nominal income from the 1980s onwards. These results did not call the monetarist theory into question, but instead stimulated the elaboration of various proposals for the modification of the monetary authorities' operative schemes. Each of these proposals gives rise to some perplexity. These anomalies provide the justification for this paper, which sets out to analyse the characteristics of the money supply endogeneity theory, a theoretical approach initiated in the 1970s thanks to Kaldor's seminal contribution, with the objective of demonstrating the inconsistencies in the monetarists' conclusions. It is intended to show that the debate on the endogeneity theory developed by the post-Keynesians has overlooked an essential aspect of Kaldor's theory, the examination of which permits: (a) the elaboration of an important criticism of monetarism; and (b) the development of a theory of credit and of financial intermediaries that highlights elements of Keynes's theory that have been neglected by the traditional interpretation. [source] Fluid-Borne entities in the impeller stream of a rushton turbineTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2000Larry A. Glasgow Abstract The breakage or disintegration of suspended entities by energetic fluid motions in stirred tanks is an essential aspect of many operations in the chemical process industries. However, the hydrodynamic inhomogeneity of such tanks makes it extremely difficult to characterize the stresses experienced in any simple manner. This work provides a determination of both the location and the frequency of interaction of spherical fluid-borne entities with the discharge of a Rushton turbine. These data show how both particle size and impeller speed affect the severity of the exposure, setting the groundwork for improved descriptions of the dynamic behaviour of the particle size distribution in a wide variety of dispersed-phase processes. La rupture ou la désintégration de particules suspendues par des déplacements de fluides énergé-tiques dans des réservoirs agités est un aspect essentiel de nombreuses opérations des industries de procédés chimiques. Toutefois, la non-homogénéité hydrody-namique de ces réservoirs rend extrçmement difficile la caractérisation des forces en jeu par une méthode simple. On détermine dans ce travail la position et la fréquence d'interaction de particules sphériques transpottées par le fluide dans la zone de refoulement d'une turbine Rushton. Ces données montrent comment la taille des particules et la vitesse de la turbine influent toutes deux sur la sévérité de l'exposi-tion, jetant ainsi les bases pour améliorer la description du comportement dynamique de la distribution de taille des particules dans un large éventail de procédés en phase dispersée. [source] AMPA-sst2 somatostatin receptor interaction in rat hypothalamus requires activation of nmda and/or metabotropic glutamate receptors and depends on intracellular calciumTHE JOURNAL OF PHYSIOLOGY, Issue 1 2003Stéphane Peineau Modulation of glutamatergic transmission by neuropeptides is an essential aspect of neuronal network activity. Activation of the hypothalamic somatostatin sst2 receptor subtype by octreotide decreases AMPA glutamate responses, indicating a central link between a neurohormonal and neuromodulatory peptide and the main hypothalamic fast excitatory neurotransmitter. In mediobasal hypothalamic slices, sst2 activation inhibits the AMPA component of glutamatergic synaptic responses but is ineffective when AMPA currents are pharmacologically isolated. In mediobasal hypothalamic cultures, the decrease of AMPA currents induced by octreotide requires a concomitant activation of sst2 receptors with either NMDA and/or metabotropic glutamate receptors. This modulation depends on changes in intracellular calcium concentration induced by calcium flux through NMDA receptors or calcium release from intracellular stores following metabotropic glutamate receptor activation. These results highlight an unusual regulatory mechanism in which the simultaneous activation of at least three different types of receptor is necessary to allow somatostatin-induced modulation of fast synaptic glutamatergic transmission in the hypothalamus. [source] The Z/I Imaging Digital Camera SystemTHE PHOTOGRAMMETRIC RECORD, Issue 96 2000A. Hinz Market needs for airborne and spaceborne imagery used in photogrammetry and GIS applications are changing. Fundamental changes in sensors, platforms and applications are currently taking place. Most recently, new high resolution spaceborne sensors have become available. Besides classical photogrammetry, new thematic applications will drive the future image market. Savings in cost and time, together with the need for higher and reproducible radiometric resolution or spectral information will push forward the change from analogue to digital imagery. High resolution satellites will compete with airborne film-based photography and digital camera systems. With the availability of a digital airborne camera, it is possible to completely close the digital chain from image acquisition to exploitation and data distribution. The key decision regarding the camera design in this case is whether a linear or area array sensor should be used. In view of the high geometric accuracy requirements in photogrammetry, Z/I Imaging has focused development on a digital camera based on an area sensor. An essential aspect of this decision was not only the aerial camera system, but also the entire photogrammetric process to the finished photographic or mapping product. If this point of view is adopted, it becomes clear that the development of a digital camera involves more than simply exchanging film for silicon. Aspects such as data transfer rates, in-flight data processing and storage, image archiving, georeferencing, colour fusion, calibration and preprocessing have the same influence on the economic assessment of a digital camera system. This paper describes current development activities and application aspects of a digital modular airborne camera system. [source] Development of Mechanical Circulatory Support Devices in ChinaARTIFICIAL ORGANS, Issue 11 2009Wei Wang Abstract Myocardial dysfunction leading to low cardiac output syndrome is a common clinical pathophysiological state. Currently, the use of mechanical circulatory support (MCS) is an essential aspect of the treatment of patients with cardiac failure. Several groups in China are engaged in the design and development of MCS devices. These devices can be classified as pulsatile, rotary, and total artificial heart (TAH). There are two types of pulsatile pump, which are driven by air (pneumatic). One of these pumps, the Luo-Ye pump, has been used clinically for short-term support since 1998. The other is a push-plate left ventricular device, which has a variable rate mode. Various rotary devices are classified into axial and centrifugal pumps, depending on the impeller geometry. Most rotary pumps are based on the maglev principle, and some types have been used clinically. Others are still being studied in the laboratory or in animal experiments. Furthermore, certain types of total implantable pump, such as the UJS-III axial pump and the UJS-IV aortic valvo-pump, have been developed. Only one type of TAH has been developed in China. The main constituents of this artificial heart are two axial pumps, two reservoir tanks mimicking the right and left atria, flow meters, two pressure gauges, and a resistance adaptor. Although the development of mechanical assist devices in China is still in a nascent stage, a number of different types of MCS devices are currently being studied. [source] Modeling the competition between aggregation and self-assembly during virus-like particle processing,BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Yong Ding Abstract Understanding and controlling aggregation is an essential aspect in the development of pharmaceutical proteins to improve product yield, potency and quality consistency. Even a minute quantity of aggregates may be reactogenic and can render the final product unusable. Self-assembly processing of virus-like particles (VLPs) is an efficient method to quicken the delivery of safe and efficacious vaccines to the market at low cost. VLP production, as with the manufacture of many biotherapeutics, is susceptible to aggregation, which may be minimized through the use of accurate and practical mathematical models. However, existing models for virus assembly are idealized, and do not predict the non-native aggregation behavior of self-assembling viral subunits in a tractable nor useful way. Here we present a mechanistic mathematical model describing VLP self-assembly that accounts for partitioning of reactive subunits between the correct and aggregation pathways. Our results show that unproductive aggregation causes up to 38% product loss by competing favorably with the productive nucleation of self-assembling subunits, therefore limiting the availability of nuclei for subsequent capsid growth. The protein subunit aggregation reaction exhibits an apparent second-order concentration dependence, suggesting a dimerization-controlled agglomeration pathway. Despite the plethora of possible assembly intermediates and aggregation pathways, protein aggregation behavior may be predicted by a relatively simple yet realistic model. More importantly, we have shown that our bioengineering model is amenable to different reactor formats, thus opening the way to rational scale-up strategies for products that comprise biomolecular assemblies. Biotechnol. Bioeng. 2010;107: 550,560. © 2010 Wiley Periodicals, Inc. [source] Using the rate of respiration to monitor events in the infection of Escherichia coli cultures by bacteriophage T4BIOTECHNOLOGY PROGRESS, Issue 3 2010Dominic Sauvageau Abstract The growing interest in applications of bacteriophages creates a need for improvements in the production processes. Continuous monitoring of the phage production is an essential aspect of any control strategy and, at present, there is no completely satisfactory option. The approach presented here uses IR-spectrometry to continuously measure the rate of respiration (CO2 released) of Escherichia coli infected by phage T4 at various multiplicities of infection (MOI). Within the trends in these data, or in other aspects of the rate of respiration, it was possible to reliably and reproducibly identify five features that reflected specific events in the infection process. These included two events in the host cell apparent growth rate and events in the magnitude of the host cell density, in the measurement of OD600 or in the specific rate of respiration. All of these correlations were within 95% confidence showing that they are suitable for the monitoring and control of E. coli populations infected by phage T4. This method is reliable, cheap, and can be operated in-line and in real time. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Recording previous adverse drug reactions,a gap in the systemBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 6 2001Gillian M. Shenfield Aims, To measure the accuracy of recording of previous adverse drug reaction (ADR) history in patients admitted to a teaching hospital before and after an education programme. Methods, One month survey of patients on one medical and one surgical ward, repeated after a 1 month education programme. Patients answered a questionnaire about previous ADRs and this information was compared with that in all relevant sections of their medical records and medication charts. Results, Of 117 patients at baseline, 50 had a total of 81 previous ADRs. Only 75% were recorded on medication charts and 57% and 64%, respectively, in medical and nursing notes. In the post education survey of 124 patients, 56 had 105 previous ADRs, 85% were recorded on medication charts and 64% and 70% in medical and nursing records. These differences were not significant. Serious ADRs were also poorly recorded at baseline but, due to intervention by ward pharmacists, their recording on medication charts improved significantly after education. Pharmacists also significantly improved the quality of description of previous ADRs in both parts of the study. Conclusions, Previous ADR history obtainable from hospital patients is poorly recorded in medical records and an intensive education programme only produced a significant change in recording by ward pharmacists. Better strategies are needed to improve this essential aspect of history taking. [source] Aggression and Moral Development: Integrating Social Information Processing and Moral Domain ModelsCHILD DEVELOPMENT, Issue 4 2004William F. Arsenio Social information processing and moral domain theories have developed in relative isolation from each other despite their common focus on intentional harm and victimization, and mutual emphasis on social cognitive processes in explaining aggressive, morally relevant behaviors. This article presents a selective summary of these literatures with the goal of showing how they can be integrated into a single, coherent model. An essential aspect of this integration is Crick and Dodge's (1994) distinction between latent mental structures and online processing. It is argued that moral domain theory is relevant for describing underlying mental structures regarding the nature and boundaries of what is moral, whereas the social information processing model describes the online information processing that affects application of moral structures during peer interactions. [source] Interactive low-dimensional human motion synthesis by combining motion models and PIKCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 4-5 2007Schubert R. Carvalho Abstract This paper explores the issue of interactive low-dimensional human motion synthesis. We compare the performances of two motion models, i.e. Principal Components Analysis (PCA) or Probabilistic PCA (PPCA), for solving a constrained optimization problem within a low-dimensional latent space. We use PCA or PPCA as a first step of preprocessing to reduce the dimensionality of the database to make it tractable, and to encapsulate only the essential aspects of a specific motion pattern. Interactive user control is provided by formulating a low-dimensional optimization framework that uses a Prioritized Inverse Kinematics (PIK) strategy. The key insight of PIK is that the user can adjust a motion by adding constraints with different priorities. We demonstrate the robustness of our approach by synthesizing various styles of golf swing. This movement is challenging in the sense that it is highly coordinated and requires a great precision while moving with high speeds. Hence, any artifact is clearly noticeable in the solution movement. We simultaneously show results comparing local and global motion models regarding synthesis realism and performance. Finally, the quality of the synthesized animations is assessed by comparing our results against a per-frame PIK technique. Copyright © 2007 John Wiley & Sons, Ltd. [source] Episodic memory,From brain to mindHIPPOCAMPUS, Issue 9 2006Janina Ferbinteanu Abstract Neuronal mechanisms of episodic memory, the conscious recollection of autobiographical events, are largely unknown because electrophysiological studies in humans are conducted only in exceptional circumstances. Unit recording studies in animals are thus crucial for understanding the neurophysiological substrate that enables people to remember their individual past. Two features of episodic memory,autonoetic consciousness, the self-aware ability to "travel through time", and one-trial learning, the acquisition of information in one occurrence of the event,raise important questions about the validity of animal models and the ability of unit recording studies to capture essential aspects of memory for episodes. We argue that autonoetic experience is a feature of human consciousness rather than an obligatory aspect of memory for episodes, and that episodic memory is reconstructive and thus its key features can be modeled in animal behavioral tasks that do not involve either autonoetic consciousness or one-trial learning. We propose that the most powerful strategy for investigating neurophysiological mechanisms of episodic memory entails recording unit activity in brain areas homologous to those required for episodic memory in humans (e.g., hippocampus and prefrontal cortex) as animals perform tasks with explicitly defined episodic-like aspects. Within this framework, empirical data suggest that the basic structure of episodic memory is a temporally extended representation that distinguishes the beginning from the end of an event. Future research is needed to fully understand how neural encodings of context, sequences of items/events, and goals are integrated within mnemonic representations of autobiographical events. © 2006 Wiley-Liss, Inc. [source] Silicon Nanowires: A Review on Aspects of their Growth and their Electrical PropertiesADVANCED MATERIALS, Issue 25-26 2009Volker Schmidt Abstract This paper summarizes some of the essential aspects of silicon-nanowire growth and of their electrical properties. In the first part, a brief description of the different growth techniques is given, though the general focus of this work is on chemical vapor deposition of silicon nanowires. The advantages and disadvantages of the different catalyst materials for silicon-wire growth are discussed at length. Thereafter, in the second part, three thermodynamic aspects of silicon-wire growth via the vapor,liquid,solid mechanism are presented and discussed. These are the expansion of the base of epitaxially grown Si wires, a stability criterion regarding the surface tension of the catalyst droplet, and the consequences of the Gibbs,Thomson effect for the silicon wire growth velocity. The third part is dedicated to the electrical properties of silicon nanowires. First, different silicon nanowire doping techniques are discussed. Attention is then focused on the diameter dependence of dopant ionization and the influence of interface trap states on the charge carrier density in silicon nanowires. It is concluded by a section on charge carrier mobility and mobility measurements. [source] Bifurcation and instability modelling by a multimechanism elasto-plastic modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2008Kamel Hamadi Abstract The bifurcation and instability conditions in geomechanics are closely related to the elasto-plastic behaviour. In this paper the potential of a multimechanism elasto-plastic model to predict various modes of failure is examined. First, a brief overview for the essential aspects of the constitutive model and the development of the elasto-plastic constitutive matrix for this model are presented. Then, numerical simulations of different drained and undrained paths in the axisymmetric and plane-strain conditions for the Hostun sand are illustrated. These examples confirm the capacity of the model to reproduce instability and strain localization phenomena. The obtained response is in agreement with experimental observations, theoretical developments and numerical analyses existing in the literature. Copyright © 2007 John Wiley & Sons, Ltd. [source] Elasto-plasticity revisited: numerical analysis via reproducing kernel particle method and parametric quadratic programmingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2002K. M. Liew Abstract Aiming to simplify the solution process of elasto-plastic problems, this paper proposes a reproducing kernel particle algorithm based on principles of parametric quadratic programming for elasto-plasticity. The parametric quadratic programming theory is useful and effective for the assessment of certain features of structural elasto-plastic behaviour and can also be exploited for numerical iteration. Examples are presented to illustrate the essential aspects of the behaviour of the model proposed and the flexibility of the coupled parametric quadratic programming formulations with the reproducing kernel particle method. Copyright © 2002 John Wiley & Sons, Ltd. [source] Performance measurement: a critical analysis of the literature with respect to total quality managementINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 2 2000David Sinclair This paper represents a comprehensive review of the literature on performance measurement. The roadmap used for this analysis is from the evolution of performance measurement, to the way it is currently defined and how it is applied from a corporate-wide perspective. One useful contribution of this review is a special focus on performance measurement in a non-financial, non-traditional sense. This discussion was further amplified by referring to newly developed tools and techniques and by highlighting critical factors of success in the application of performance measurement. The key factors from this literature review reveal that, although interest in the area of measurement is growing significantly, this is not reflected by the tangible and credible experiences in the organizations concerned. There is a concurrent view amongst various writers that there are both hard and soft issues reflecting, for instance, the lack of strategic thinking and goal clarity, putting measurement systems in the driving seat and therefore trusting unreliable designs and not focusing on the true ethos of modern measurement towards continuous improvement and thereby not engaging employees and neglecting the culture change aspects. The paper concludes by highlighting the dearth in research in the important field of performance measurement and, in particular, the design and implementation of performance measurement systems that cover all the essential aspects through an integrated perspective. [source] Efficient packet scheduling for heterogeneous multimedia provisioning over broadband satellite networks: An adaptive multidimensional QoS-based designINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2009Hongfei Du Abstract With their inherent broadcast capabilities and reliable extensive geographical coverage, the broadband satellite networks are emerging as a promising approach for the delivery of multimedia services in 3G and beyond systems. Given the limited capacity of the satellite component, to meet the diverse quality of service (QoS) demands of multimedia applications, it is highly desired that the available resources can be adaptively utilized in an optimized way. In this paper, we draw our attention on the development and evaluation of an efficient packet scheduling scheme in a representative broadband satellite system, namely satellite digital multimedia broadcasting (SDMB), which is positioned as one of the most attractive solutions in the convergence of a closer integration with the terrestrial mobile networks for a cost-effective delivery of point-to-multipoint services. By taking into account essential aspects of a successful QoS provisioning while preserving the system power/resource constraints, the proposed adaptive multidimensional QoS-based (AMQ) packet scheduling scheme in this paper aims to effectively satisfy diverse QoS requirements and adaptively optimize the resource utilization for the satellite multimedia broadcasting. The proposed scheme is formulated via an adaptive service prioritization algorithm and an adaptive resource allocation algorithm. By taking into account essential performance criteria, the former is capable of prioritizing contending flows based on the QoS preferences and performance dynamics, while the latter allocates the resources, in an adaptive manner, according to the current QoS satisfaction degree of each session. Simulation results show that the AMQ scheme achieves significantly better performance than those of existing schemes on multiple performance metrics, e.g. delay, throughput, channel utilization and fairness. Copyright © 2008 John Wiley & Sons, Ltd. [source] Foucault in Africa: the microphysics of a contemporary monarchyINTERNATIONAL SOCIAL SCIENCE JOURNAL, Issue 191 2008Jean-Pierre Warnier The Mankon kingdom is located in the mountains of western Cameroon (the Grassfields). Although like many other African kingdoms it has since the 1980s been experiencing a revitalisation, the king is fully aware of all of the practices that have structured life in the kingdom for at least the past three centuries. His body contains substances that have been transformed into ancestral substances of life during offerings to his deceased ancestors, which he distributes to the entire kingdom. He thus embodies a pot-king, a receptacle of the kingdom's life substances. The sensorimotor conduct and the material culture implemented by the monarch and his subjects lend themselves to a Foucauldian analysis in terms of subjectivising governmentality. The work of Foucault, formulated in the west, proves to be extremely relevant in shedding light on the microphysics of power in this kingdom. It also suggests the possibility of new comparative studies of such practices, which are hardly verbalised, and which constitute the essential aspects of devices of subjection and subjectivisation. [source] Forest change and stream fish habitat: lessons from ,Olde' and New EnglandJOURNAL OF FISH BIOLOGY, Issue 2005K. H. Nislow The North Atlantic region has a long history of land use change that has influenced and will continue to influence stream ecosystems and fisheries production. This paper explores and compares the potential consequences of changes in forest cover for fish production in upland, coldwater stream environments in New England, U.S.A. and the British Isles, two regions which share important similarities with respect to overall physical, biotic and socio-economic setting. Both regions were extensively deforested and essentially no extensive old-growth forest stands remain. In New England, recovering forests, consisting almost entirely of naturally-regenerated native species, now cover >60% of the landscape. Associated with this large-scale reforestation, open landscapes, common in the 19th and first half the 20th century, are currently rare and declining in this region. In the British Isles, forests still cover <20% of the landscape, and existing forests largely consist of exotic conifer plantations stocked at high stand densities and harvested at frequent rotations. While forest restoration and conservation is frequently recommended as a fisheries habitat conservation and restoration tool, consideration of the way in which forests affect essential aspects of fish habitat suggests that response of upland stream fish to landscape change is inherently complex. Under certain environmental settings and reforestation practices, conversion of open landscapes to young-mature forests can negatively impact fish production. Further, the effects of re-establishing old-growth forests are difficult to predict for the two regions (due to the current absence of such landscapes), and are likely to depend strongly on the extent to which critical ecosystem attributes (large-scale disturbances, fish migrations, keystone species, large woody debris recruitment) are allowed to be re-established. Understanding these context-dependencies is critical for predicting fish responses, and should help managers set realistic conservation, management and restoration goals. Management may best be served by promoting a diversity of land cover types in a way that emulates natural landscape and disturbance dynamics. This goal presents very different challenges in New England and the British Isles due to differences in current and predicted land use trajectories, along with differences in ecological context and public perception. [source] The impact of case specificity and generalisable skills on clinical performance: a correlated traits,correlated methods approachMEDICAL EDUCATION, Issue 6 2008Paul F Wimmers Context, The finding of case or content specificity in medical problem solving moved the focus of research away from generalisable skills towards the importance of content knowledge. However, controversy about the content dependency of clinical performance and the generalisability of skills remains. Objectives, This study aimed to explore the relative impact of both perspectives (case specificity and generalisable skills) on different components (history taking, physical examination, communication) of clinical performance within and across cases. Methods, Data from a clinical performance examination (CPX) taken by 350 Year 3 students were used in a correlated traits,correlated methods (CTCM) approach using confirmatory factor analysis, whereby ,traits' refers to generalisable skills and ,methods' to individual cases. The baseline CTCM model was analysed and compared with four nested models using structural equation modelling techniques. The CPX consisted of three skills components and five cases. Results, Comparison of the four different models with the least-restricted baseline CTCM model revealed that a model with uncorrelated generalisable skills factors and correlated case-specific knowledge factors represented the data best. The generalisable processes found in history taking, physical examination and communication were responsible for half the explained variance, in comparison with the variance related to case specificity. Conclusions, Pure knowledge-based and pure skill-based perspectives on clinical performance both seem too one-dimensional and new evidence supports the idea that a substantial amount of variance contributes to both aspects of performance. It could be concluded that generalisable skills and specialised knowledge go hand in hand: both are essential aspects of clinical performance. [source] UNESCO and Languages: A Commitment to Culture and DevelopmentMUSEUM INTERNATIONAL, Issue 3 2008Mauro Rosi For more than sixty years languages and multilingualism have constituted essential aspects of UNESCO's programme and this remains true today. This is due, on the one hand, to the fact that we are witnessing an unprecedented valorisation of intangible cultural heritage in all its forms, and on the other, to the fear that globalization will cause an acceleration in the disappearance of a large number of languages. In this context, UNESCO has opted in favour of languages and multilingualism, by creating a normative tool and specialized and multidisciplinary programmes. [source] Bestimmung der Tunnelinnenschalendicke mit zerstörungsfreien PrüfverfahrenBETON- UND STAHLBETONBAU, Issue 8 2006Dietmar Mähner Prof. Dr.-Ing. Der vorliegende Beitrag befaßt sich mit dem Einfluß von zerstörungsfreien Prüfmethoden zur Bestimmung der Tunnelinnenschalendicke und der Auswertung eines auf einer Baustelle durchgeführten Untersuchungsprogramms. Die Bandbreite der Untersuchungen bilden dabei an drei Tunnelblöcken unterschiedlich eingesetzte Meßverfahren und ihre jeweilige spezifische Eignung, verschiedene Meßteams sowie unterschiedliche Meßraster, die jeweils vor und nach der Firstspaltverpressung zum Einsatz kamen und analysiert wurden. Als wichtiger Parameter zum Einfluß der Meßqualität ist hierbei die durchzuführende Kalibrierung der Meßgeräte am Einsatzort zu nennen, die die Grundlage der Meßgenauigkeit bildet. Weiterhin konnte die Qualität bzw. der Erfolg der durchgeführten Firstspaltverpressung mittels eines Injektionsgutes in den Messungen nicht zweifelsfrei bestätigt werden und wurde daher zusätzlich durch Kernbohrungen und endoskopische Aufnahmen überprüft. Mit den daraus gewonnen Erkenntnissen werden wesentliche Aspekte und Empfehlungen aufgeführt, die im Umgang mit den zerstörungsfreien Prüfmethoden zur Dickenbestimmung einer Tunnelschale zu beachten sind und in zukünftige Projekte einfließen sollten. Determining the thickness of tunnel internal shell with non-destructive testing methods This report deals with the influence of non-destructive testing methods for determining the thickness of internal tunnel shells and evaluates the results of examinations performed on a construction site. The investigations cover different measurement techniques performed on three tunnel blocks; also analyzed were the specific advantages of these techniques, the employment measurement personnel and different measurement grids used before and after ridge-gap grouting. An essential parameter influencing the measurement accuracy is the calibration needed by the measurement devices at the site of deployment. Because the measurements were not able to unmistakably confirm the quality or success of ridge-gap grouting through injection, these results had to be examined additionally using drill cores and endoscopy. Permitting a crystallization of essential aspects and recommendations as regards the conduction of non-destructive tests for determining the thickness of tunnel shells, the obtained findings are to be incorporated into future projects. [source] Brain, mind and limitations of a scientific theory of human consciousnessBIOESSAYS, Issue 5 2008Alfred Gierer In biological terms, human consciousness appears as a feature associated with the functioning of the human brain. The corresponding activities of the neural network occur strictly in accord with physical laws; however, this fact does not necessarily imply that there can be a comprehensive scientific theory of consciousness, despite all the progress in neurobiology, neuropsychology and neurocomputation. Predictions of the extent to which such a theory may become possible vary widely in the scientific community. There are basic reasons,not only practical but also epistemological,why the brain,mind relation may never be fully "decodable" by general finite procedures. In particular self-referential features of consciousness, such as self-representations involved in strategic thought and dispositions, may not be resolvable in all their essential aspects by brain analysis. Assuming that such limitations exist, objective analysis by the methods of natural science cannot, in principle, fully encompass subjective, mental experience. BioEssays 30:499,505, 2008. © 2008 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||||||||