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Selected AbstractsArray antenna assisted doppler spread compensator for OFDMEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2002Minoru Okada This paper proposes a novel array-antenna-assisted Doppler spread compensator for orthogonal frequency division multiplexing (OFDM), which is sensitive to fast time-variation of the radio propagation channel. In the proposed compensator, a linear array antenna is installed on top of the vehicle. The compensator estimates the received signal at a certain point on the linear array antenna by using space domain interpolation. Because the relative position of the estimated receiving point with respect to the ground does not change during the effective symbol duration of an OFDM signal, the time variation due to the movement of the vehicle can be compensated for. Computer simulation shows that the compensator can compensate for the bit error rate performance degradation due to time-variation of the channel when the velocity of the vehicle is up to 180km/h and a two-element array antenna is used at the carrier frequency of 600 MHz. The bit error rate performance can be further improved by using a four-element array antenna. [source] A dynamic analysis of GP visiting in Ireland: 1995,2001HEALTH ECONOMICS, Issue 2 2007Anne Nolan Abstract This paper examines the determinants of GP visiting in Ireland, using panel data from the Living in Ireland Survey from 1995,2001. While cross-sectional studies provide important information on GP visiting patterns at a certain point in time, with panel data we can also control for unobserved individual heterogeneity, as well as identify whether it is the same individuals who consistently visit their GP year on year, or whether there is more mobility in visiting. We therefore estimate dynamic models of GP utilisation, and attempt to decompose the observed variation in GP visiting into components attributable to observed individual characteristics, unobserved individual heterogeneity and state dependence. Copyright © 2006 John Wiley & Sons, Ltd. [source] Erlang capacity analysis of hybrid FDMA/CDMA systems supporting multi-class services according to channel assignment methodsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2002Insoo Koo Abstract In this paper, we focus on the evaluation of the Erlang capacity for hybrid FDMA/CDMA systems supporting multi-class services with two channel allocation schemes: independent carrier channel assignment (ICCA) and combined carrier channel assignment (CCCA). For the performance analysis, a multi-dimensional Markov chain model is developed. The effect of the number of carriers of hybrid FDMA/CDMA system on the Erlang capacity is observed, and the optimum values of the system parameters such as the number of channel elements (CEs) and the number of carriers are selected with respect to the Erlang capacity. As a numerical example, we consider an FDMA/CDMA system supporting voice/data services. We find out that, even though the benefit of CCCA scheme over ICCA scheme is negligible for small number of CEs, the scenario changes significantly when the number of CEs increases beyond a certain point. An improvement of as much as 74% can be achieved in the Erlang capacity when 5 carriers are employed. We also find the capacity knees for different number of carriers. The results of this paper could be helpful in the traffic engineering of FDMA/CDMA systems providing multi-class services. Copyright © 2002 John Wiley & Sons, Ltd. [source] Active force closure for multiple objectsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2002Kensuke Harada This article discusses active force closure (AFC) for the manipulation of multiple objects. AFC for multiple objects is defined in such a way that the finger can generate an arbitrary acceleration onto a certain point of multiple objects. We define two kinds of AFC: in the first, an arbitrary acceleration can be generated onto each of the objects; in the second, an arbitrary acceleration can be generated onto the center of mass of multiple objects without changing the relative position of the objects. We show that the grasped object cannot always be manipulated arbitrarily even if the first kind of AFC is satisfied. We also show that the grasped objects are manipulated like a single rigid body if the second kind of AFC is satisfied. To explain these features of AFCs, numerical examples for the grasp of three objects are shown. © 2002 Wiley Periodicals, Inc. [source] Corporate Value, Managerial Stockholdings and Investments of Japanese FirmsJOURNAL OF INTERNATIONAL FINANCIAL MANAGEMENT & ACCOUNTING, Issue 1 2006Carl R. Chen We use a simultaneous equation model which treats firm value, investments and management ownership as endogenous to the firm. Our results show a feedback relation between corporate value and management ownership, i.e., corporate value is positively impacted by management ownership, which in turn is positively impacted by corporate value. Corporate value also affects investments made by the firm. We also find that the effect of the main bank on corporate value is positive but only up to a certain point; then, it turns negative. Supporting the argument that keiretsu firms have lower agency cost, we find that firms belonging to a keiretsu have higher valuations during the sample period. Finally, we find that management ownership increases as the ownership of the main bank, ownership of institutional holders and cross-holdings decreases, suggesting a substitution effect among these monitoring forces. Our results indicate that ignoring the web of these relationships leads to incorrect inferences. [source] Firm value, managerial confidence, and investments: The case of ChinaJOURNAL OF LEADERSHIP STUDIES, Issue 3 2008Bei Ye The purpose of this article is to test empirically the impact of Chinese managerial confidence on firm value through investment decisions. We use a simultaneous equation model, which treats firm value, investments, and managerial confidence as endogenous to the firm. With a sample of 329 Chinese listed firms and a confidence measure based on management shareholding, the 3SLS regression results show significant interactions among the three variables. Firm value has a positive impact on managerial confidence while the latter's impact on the former turns from positive to negative at a certain point. The results suggest a non-monotonic relationship between managerial self-confidence and firm value and imply an optimal level of managerial confidence. Therefore, while the leader selection process encourages confident talents to become decision-makers, proper measures are required to prevent the confidence transformed into overconfidence. [source] Translucency of glass-fibre-reinforced composite materialsJOURNAL OF ORAL REHABILITATION, Issue 8 2004T. Nakamura summary, The purpose of this study was to examine the translucency of glass-fibre-reinforced composite framework materials. Vectris and FibreKor, as well as an experimental material, were the glass-fibre-reinforced framework materials used. Targis, Sculpture and Estenia were the types of particulate filler composites veneered onto frameworks. Specimens were fabricated from each material, 0·5 and 1·0 mm thick. In addition, laminate specimens, 1·5 mm thick, were fabricated. The translucency of each specimen was evaluated by determining its contrast ratio. The laminate specimens were examined for colour differences. The experimental framework material was more translucent than the enamel composite when it was not coloured, and was nearly as translucent as the dentine composite when coloured. The commercial tooth-coloured framework materials were nearly as translucent as the dentine composite. It was found that it was possible to reproduce the same colour as the veneering dentine composite, when the framework thickness was 0·5 mm, except in the case of FibreKor. Within the limitations of this study, tooth-coloured, glass-fibre-reinforced framework materials are nearly as translucent as the veneering dentine composite, but these materials affect the colour of the prosthesis if the thickness of the framework material is increased beyond a certain point. [source] Longitudinal Associations Between Personality Profile Stability and Adjustment in College Students: Distinguishing Among Overall Stability, Distinctive Stability, and Within-Time NormativenessJOURNAL OF PERSONALITY, Issue 4 2010Theo A. Klimstra ABSTRACT In the present study, longitudinal associations of 3 aspects of personality profile stability (i.e., overall stability, distinctive stability, and within-time normativeness) with 3 adjustment measures (i.e., depressive symptoms, self-esteem, and delinquency) were examined, using 4 waves of longitudinal data on a Belgian college sample (N=565). Longitudinal path models revealed strong longitudinal associations between adjustment and overall stability. Subsequent analyses showed that it is not the degree to which one's personality profile consistently diverges from the average personality profile within a population (i.e., distinctive stability) that is related to adjustment but the degree to which a personality profile of an individual matches the average personality profile within the sample at a certain point in time (i.e., within-time normativeness). The current study thereby underscores the importance of distinguishing normativeness and distinctiveness when examining personality profile stability. [source] Karst Collapse Mechanism and Criterion for Its StabilityACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2001HE Keqiang Abstract Karst collapse, caused by natural or artificial abstraction of groundwater, has been a focus of environmental geological problems for its ever-increasing hazardousness. The potential erosion theory and vacuum suction erosion theory, which reveal the origin of karst collapse macroscopically, are popularly accepted. However, a mathematic prediction criterion for karst collapse cannot be established only by these two theories. From a new perspective, this paper attempts to explain the microcosmic mechanism of karst collapse on the basis of these two theories. When the shear stress surpasses the shear strength of soil, a certain point or a certain plane in the unconsolidated soil covering karst caves will fail under the mechanical effects of water and air as well as its load-pressure, and with the increase of damaged points, a breaking plane appears and the soil on karst caves is completely damaged; as a result, the karst ground collapses. On the basis of the Mohr-Coulomb failure theory and previous studies, the paper presents a prediction criterion of karst collapse. Finally, by taking, for example, nine typical cases of collapse caused by pumping tests in Guizhou, the paper gives the calculation process of the model and proves its reliability. [source] Aporias, Webs, and Passages: Doubt as an Opportunity to LearnCURRICULUM INQUIRY, Issue 2 2000Nicholas C. Burbules This article offers an exploration of the idea, and the experience, of aporia (usually translated as ,doubt') in Plato's dialogue, the Meno, and in other teaching/learning contexts. A metaphor that moves throughout the article is the experience of being lost when exploring the World Wide Web and other weblike or hypertextual environments. The article represents the experience of movement, following uncertain connections, and cycling back through certain points by way of the form in which it is written. Through a series of interlinked passages, the article explores the ideas of webs, passages, and paths of connection as models of discovery, getting lost, making unexpected connections, and learning. It explores different types of aporia and shows how aporia can be seen, not as a barrier to knowledge, or as simply ,clearing the ground' for new learning, but as an integral dimension of learning (and of teaching) itself. By design, it offers not an argument but a way of exploring complex ideas; in a different medium, it could have been produced as a hypertextual article itself (and in this way might also spark reflection on the possibilities and limits of hypertextual writing within a print medium). [source] The vasodilatory actions of insulin on resistance and terminal arterioles and their impact on muscle glucose uptakeDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 1 2004Lucy H. Clerk Abstract Whether a discrete vascular action of insulin in skeletal muscle integrally participates in insulin-mediated glucose disposal has been extensively examined but remains a contentious issue. Here, we review some of the data both supporting and questioning the role of insulin-mediated increases in limb blood flow in glucose metabolism. We advance the hypothesis that controversy has arisen, at least in part, from a failure to recognize that insulin exerts at least three separate actions on the peripheral vasculature, each with its own characteristic dose and time responsiveness. We summarize how, viewed in this manner, certain points of contention can be resolved. We also advance the hypothesis that an action on the precapillary arteriole may play the dominant role in mediating perfusion-dependent effects of insulin on glucose metabolism in muscle. Copyright © 2003 John Wiley & Sons, Ltd. [source] The origin of higher taxa: macroevolutionary processes, and the case of the mammalsACTA ZOOLOGICA, Issue 1 2007T. S. Kemp Abstract The origin of a new higher taxon is characterized by a long-term phylogenetic trend, involving evolutionary changes in a large number of characters. At this phylogenetic level, the conflict between internal integration of the phenotype and its evolvability can be resolved by the correlated progression model, in which many disparate traits evolve by a sequence of small increments in loose correlation with one another, rather than by the modularity model. The trend leading to the new higher taxon implies the existence of a long ridge in an adaptive landscape. An evolutionary lineage tracking it requires adaptive changes in broad biological characteristics, involving many traits. Species selection is a possible additional driver of the trend. These conclusions are tested against the synapsid fossil record of the origin of mammals. The reconstructed sequence of acquisition of mammalian traits supports the correlated progression model. The adaptive ridge involved is postulated to have been a sequence of overlapping niches requiring increasing ability to remain active in daily and seasonally fluctuating environments by means of increasing internal regulation. An inferred speciation bias in favour of relatively small, relatively more progressive carnivores indicates that species selection was also involved in driving the trend. Palaeoenvironmental evidence indicates that ecological opportunity probably played a role at certain points along the lineage. [source] Analytical ecological epidemiology: exposure,response relations in spatially stratified time seriesENVIRONMETRICS, Issue 6 2009Hagen Scherb Abstract An important task of environmental research is the investigation of a possible causal relationship between exposure and the frequency of a biologic trait. Major industrial accidents provide examples where the exposure status of large populations may change considerably within relatively short time intervals of days or weeks (e.g. Seveso herbicide plant explosion, Chernobyl Nuclear Power Plant catastrophe). Therefore, purely temporal change-points may be tested in time series of appropriate public health indicators (e.g. mortality, morbidity, sex ratio at birth). If, in addition, the spatial contamination is strong and variable enough and can be identified with sufficient precision at the level of regional units (e.g. districts), then a spatial-temporal approach makes sense. This essentially means that a global time trend model is adjusted for region-specific trend functions, allowing for local or global temporal jumps or broken sticks (change-points) at certain points in time. The local jump heights may be tested for associations with local exposure (exposure,response relation), and all other characteristics in the data that vary with locality and in time are automatically accounted for, thus minimizing confounding. Spatial-temporal approaches may help to strengthen the evidence of possible causal relationships. As an example, the human sex ratio at birth in several European countries before and after the Chernobyl Nuclear Power Plant accident was investigated. A long-term chronic impact of radioactive fallout on the secondary sex ratio has been found. Copyright © 2008 John Wiley & Sons, Ltd. [source] What the eyes already ,know': using eye movement measurement to tap into children's implicit numerical magnitude representationsINFANT AND CHILD DEVELOPMENT, Issue 2 2010Angela Heine Abstract To date, a number of studies have demonstrated the existence of mismatches between children's implicit and explicit knowledge at certain points in development that become manifest by their gestures and gaze orientation in different problem solving contexts. Stimulated by this research, we used eye movement measurement to investigate the development of basic knowledge about numerical magnitude in primary school children. Sixty-six children from grades one to three (i.e. 6,9 years) were presented with two parallel versions of a number line estimation task of which one was restricted to behavioural measures, whereas the other included the recording of eye movement data. The results of the eye movement experiment indicate a quantitative increase as well as a qualitative change in children's implicit knowledge about numerical magnitudes in this age group that precedes the overt, that is, behavioural, demonstration of explicit numerical knowledge. The finding that children's eye movements reveal substantially more about the presence of implicit precursors of later explicit knowledge in the numerical domain than classical approaches suggests further exploration of eye movement measurement as a potential early assessment tool of individual achievement levels in numerical processing. Copyright © 2009 John Wiley & Sons, Ltd. [source] Observations on The "Vanity of the Philosopher"AMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 3 2008Article first published online: 31 JUL 200, Charles R. McCann The purpose of this essay is to identify certain points at which the presentation in Vanity appears incomplete or in error, especially as regards the interpretations of Mill and Spencer. It is shown that, while the authors have stated their case well, certain mischaracterizations, misstatements, and omissions seem to allow an alternative overall interpretation. However, another look suggests that, despite these discrepancies, the given interpretation is quite valid. [source] A stochastic evaluation of the decision to specialize in orthodonticsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 1 2003SR Straja Structured Abstract Authors , Straja SR, Klatte KJ, Montgomery GL, Tuncay OC Objective , The objective of this paper is to identify under different scenarios, and from a financial point of view, the conditions required to successfully switch from the general dentistry practice to orthodontics. Study Design , A mail survey was used to collect the data from the practicing orthodontists. They estimated the income, at certain points, in the working life of an orthodontist. The general practitioner data were taken from the American Dental Association figures. Subsequently, a stochastic model was constructed. Results and Conclusion , Those who decide to buy an existing practice expect higher profits in the near future, and therefore the required minimum number of remaining years of practice is lower than for those deciding to start a new practice. For both scenarios, the 3-year residency will delay the profits compared with a 2-year residency. Thus, an increased number of remaining years of practice is required. There must be more than 10 working years left in the practitioner's life to make the switch profitable. [source] Representative marketing-oriented study on implants in the Austrian population.CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2003Abstract: The number of dental implants inserted annually worldwide has been estimated to come close to a million. But the level of information available to patients about realistic, evidence-based treatment options by implants is often enough more than fragmentary, and what is disseminated by the media and the industry does not always reflect evidence-based empirical data. This survey of 1000 adults presented with 18 questions was designed to shed light on several points. These were (1) level of subjective patient information, (2) sources of information and prejudices, (3) future demand for implant treatment and target groups for patient information campaigns, and (4) potential misinformation, information deficits, discrepancies of information and how these come about. Of those questioned, 20% said unprompted that implants were a possibility to replace missing teeth. When prompted, 72% said that they knew about dental implants. Most of those questioned felt poorly informed about the options for replacing missing teeth and many knew less about implants than about other alternatives. The dentist was said to be the desired source of information, but 77% of those questioned reported that their dentists did not practice implant dentistry. More than 79% of those questioned did not know whether their dentist worked with implants. Forty-four percent thought that implants should only be placed by specially trained doctors. Sixty-one percent were of the opinion that dentists who provide implant dentistry were better qualified than their nonimplanting colleagues. Half of those questioned attributed implant failures to allergies and incompatibilities, the other half to poor medical care. Only 29% incriminated poor oral hygiene as a cause of implant failure. Future strategies should be geared to more professional public relations and patient information. Internationally operating qualified implant institutions could contribute much to balance discrepant information. Résumé Le nombre d'implants dentaires insérés annuellement dans le monde se chiffrerait à environ un million. Mais le niveau d'information disponible du patient en ce qui concerne les options de traitement basées sur l'évidence est souvent fragmentaire, et l'information dispensée par les média et l'industrie ne reflète pas toujours ces options. Cette enquête réalisée sur mille adultes ayant reçu un questionnaire de 18 questions a été effectuée afin de mettre en évidence certains points. Ces derniers étaient 1) le niveau de l'information subjective du patient, 2) les sources d'information et préjudices, 3) la demande future pour le traitement implantaire et les groupes cibles pour les campagnes d'information des patients, 4) les mauvaises informations potentielles, les déficits d'information, les désaccords de l'information et les causes de ces derniers. De ces personnes questionnées, 20% ont répondu spontanément que les implants étaient un moyen de remplacer les dents manquantes. Lorsqu'ils étaient interrogés, 72% ont répondu connaître les implants dentaires. La plupart de ces personnes se sentaient cependant peu informées sur les options de remplacement des dents manquantes et beaucoup d'entre-elles possédaient très peu d'information sur les implants par rapport aux autres possibilités existantes. Le dentiste semblait être la source préférentielle d'information mais 77 % des personnes questionnées ont rapporté que leur dentiste ne plaçait pas d'implant. Plus de 79% ne savaient pas si leur dentiste pratiquait l'implantologie. Quarante-quatre pour cent étaient persuadés que les implants ne pouvaient être placés que par des spécialistes. Soixante et un pour cent pensaient que les dentistes pratiquant de la dentisterie implantaire étaient plus qualifiés que les autres collègues. La moitié attribuait les échecs implantaires aux allergies et aux incompatiblités, l'autre moitié aux mauvais soins médicaux. Seul 29% incriminaient la mauvaise hygiène buccale comme une cause d'échec implantaire. Des stratégies futures devraient être orientées vers davantage de relations publiques professionnelles et d'informations du patient. Des institutions d'implants internationales pourraient grandement contribuer à changer cette mauvaise information. Zusammenfassung Eine repräsentative marketing-orientierte Studie über Implantate in der Bevölkerung von Oesterreich. Teil I: Stand der Information, Informationsquellen und Bedürfnis bezüglich Patienteninformation Die Anzahl weltweit gesetzter Implantate pro Jahr wird auf fast eine Million geschätzt. Aber die den Patienten zur Verfügung stehende Information über realistische, auf Evidenz basierende Behandlungsmöglichkeiten mit Implantaten ist mehr als lückenhaft. Was durch die Medien und durch die Industrie verbreitet wird, wiederspiegelt nicht immer auf Evidenz basierende empirische Daten. Diese Untersuchung an 1000 Erwachsenen, welchen 18 Fragen gestellt wurden, wurde entwickelt, um Licht auf verschiedene Punkte zu werfen. Die Punkte betrafen (1) Stand der subjektiven Patienteninformation; (2) Informationsquellen und Vorurteile; (3) zukünftiger Bedarf an Implantatbehandlungen und Zielgruppen für Propaganda zur Patienteninformation; (4) potentielle Fehlinformation, Informationsdefizite, Diskrepanzen in der Information und wie diese zustande kommen. Von den gefragten Individuen sagten ohne Vorinformation 20%, dass Implantate eine Varainte für den Ersatz von fehlenden Zähnen darstellen. Mit Vorinformation sagten 72%, dass sie von dentalen Implantaten Kenntnis haben. Die meisten der Befragten fühlten sich über die Möglichkeiten bezüglich Ersatz fehlender Zähne schlecht informiert und viele wussten weniger über Implantate als über andere Behandlungsvarianten. Es wurde gesagt, der Zahnarzt sei die gewünschte Informationsquelle, aber 77% der Befragten berichteten, dass ihr Zahnarzt keine Behandlungen mit Implantaten anbietet. Mehr als 79% der Befragten wussten nicht, ob ihr Zahnarzt mit Implantaten arbeitet. Vierundvierzig Prozent dachten, dass Implantate nur durch speziell ausgebildete Aerzte gesetzt werden sollten. Einundsechzig Prozent waren der Meinung, dass Zahnärzte, welche Implantatbehandlungen anbieten, besser qualifiziert sind als ihre nicht-implantierenden Kollegen. Die Hälfte der Befragten führten Implantatmisserfolge auf Allergien und Unverträglichkeiten zurück, die andere Hälfte auf schlechte medizinische Nachsorge. Nur 29% bezeichneten eine schlechte Mundhygiene als Ursache für Implantatmisserfolge. Zukünftige Studien sollten Richtung professioneller Publikums- und Patienteninformation gesteuert werden. International tätige qualifizierte Implantatinstitutionen könnten beträchtlich zum Ausgleich von widersprüchlichen Informationen beitragen. Resumen El número de implantes dentales insertados anualmente en todo el mundo se ha estimado cercano al millón. Pero el nivel de información disponible para los pacientes acerca de opciones de tratamiento reales con implantes basados en la evidencia es frecuentemente mas bien fragmentaria y lo que se disemina por los medios y la industria no siempre refleja los datos empíricos basados en la evidencia. Esta encuesta de 1000 adultos que presentaba 18 preguntas fue diseñada para dar luz en determinados puntos. Estos fueron (1) nivel subjetivo de información de los pacientes; (2) fuentes de información y prejuicios; (3) demanda futura para tratamiento de implantes y grupos diana para campañas de información; (4) desinformación potencial, déficit de información, discrepancias de información y como se generan. De aquellos a los que se preguntó, 20% dijeron espontáneamente que los implantes eran una posibilidad para reemplazar dientes ausentes. Cuando se les preguntó, 72% dijeron que sabían acerca de los implantes dentales. La mayoría de los encuestados se sentían pobremente informados acerca de las opciones para reemplazar dientes ausentes y muchos sabían menos acerca de los implantes que sobre otras alternativas. Se dijo que el dentista era la fuente de información mas deseada, pero 77% de los encuestados manifestó que sus dentistas no practicaban implantología. Mas del 79% de los encuestados no sabían si su dentista trabajaba con implantes. El 44% pensaba que los implantes debían ponerse solamente por doctores especialmente entrenados. El 61% eran de la opinión de que los dentistas que realizaban odontología de implantes estaban mejor cualificados que sus colegas que no lo hacían. La mitad de los encuestados atribuían los fracasos de los implantes a alergias e incompatibilidades, la otra mitad a pobres cuidados médicos. Solo el 29% incriminó a la pobre higiene oral como causa de fracaso de los implantes. La futura estrategia debe ser encaminada a unas relaciones públicas más profesionales y a más información del paciente. Las instituciones de implantes cualificadas que operan internacionalmente podrían contribuir a equilibrar la información discrepante. [source] | |||||||||||||||||||