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Individual User (individual + user)
Selected AbstractsA standards-based Grid resource brokering service supporting advance reservations, coallocation, and cross-Grid interoperabilityCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 18 2009Erik Elmroth Abstract The problem of Grid-middleware interoperability is addressed by the design and analysis of a feature-rich, standards-based framework for all-to-all cross-middleware job submission. The architecture is designed with focus on generality and flexibility and builds on extensive use, internally and externally, of (proposed) Web and Grid services standards such as WSRF, JSDL, GLUE, and WS-Agreement. The external use provides the foundation for easy integration into specific middlewares, which is performed by the design of a small set of plugins for each middleware. Currently, plugins are provided for integration into Globus Toolkit 4 and NorduGrid/ARC. The internal use of standard formats facilitates customization of the job submission service by replacement of custom components for performing specific well-defined tasks. Most importantly, this enables the easy replacement of resource selection algorithms by algorithms that address the specific needs of a particular Grid environment and job submission scenario. By default, the service implements a decentralized brokering policy, striving to optimize the performance for the individual user by minimizing the response time for each job submitted. The algorithms in our implementation perform resource selection based on performance predictions, and provide support for advance reservations as well as coallocation of multiple resources for coordinated use. The performance of the system is analyzed with focus on overall service throughput (up to over 250 jobs per min) and individual job submission response time (down to under 1,s). Copyright © 2009 John Wiley & Sons, Ltd. [source] User-Centred Time Geography for Location-Based ServicesGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 4 2004Martin Raubal Abstract Location-based services assist people in their decision-making during the performance of tasks in space. They do not consider the user's individual preferences, time constraints and possible subtasks to be performed. In order to account for these important aspects, a user-centred spatio-temporal theory of location-based services is required. We propose such a theory by combining classical time geography with an extended theory of affordances. It assumes that affordances belong to three realms: physical, social-institutional, and mental. In addition to covering the capability, coupling and authority constraints from time geography, this allows for a user-centred perspective because affordances describe action possibilities with regard to a specific person. Furthermore, the integration of mental affordances offers the possibility to account for cognitive time constraints due to the duration of decision-making processes. This new theory for location-based services is closer to the individual user and more plausible with respect to their daily lives. A business traveller scenario is used as a case study to demonstrate this. [source] A utility-based capacity optimization framework for achieving cooperative diversity in the hierarchical converged heterogeneous wireless networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 12 2008Mugen Peng Abstract A hierarchical convergence mechanism for the heterogeneous wireless communication system via the heterogeneous cooperative relay node is presented in this paper, in which the techniques of cooperative communication and wireless relay are utilized to improve performances of the individual user and the overall converged networks. In order to evaluate the benefits of the proposal, a utility-based capacity optimization framework for achieving the heterogeneous cooperative diversity gain is proposed. The heterogeneous cooperative capacity, relay selection and power allocation theoretical models are derived individually. The joint optimization model for relay selection and power allocation is presented as well. Owing to the computation complexity, the sub-optimal cooperative relay selection algorithm, the sub-optimal power allocation algorithm and the sub-optimal joint algorithm are determined to approach the maximum overall networks' spectrum efficiency. These proposed algorithms are designed in conformance to guarantee the equivalent transmission rates of the different wireless access networks. The simulation results demonstrate that the utility-based capacity model is available for the heterogeneous cooperative wireless communication system, and the proposed algorithms can improve performances by achieving the cooperative gain and taking full advantage of the cross-layer design. Copyright © 2008 John Wiley & Sons, Ltd. [source] DVB-S2, the second generation standard for satellite broadcasting and unicastingINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2004Alberto Morello Abstract DVB-S2 is the second-generation specification for satellite broadcasting developed by the DVB Project in 2003 and needs to be seen in conjunction with the world-famous DVB-S specification which was finalized in 1993. It benefits from more recent developments in channel coding (LDPC codes) combined with a variety of modulation formats (QPSK, 8PSK, 16APSK and 32APSK). When used for interactive point-to-point applications like IP-based service navigation, it may implement adaptive coding and modulation (ACM), thus allowing the transmission parameters to be optimized for each individual user, dependent on path conditions. Backwards compatible modes are available, allowing existing DVB-S services and Set Top Boxes (STBs) to continue working during any transitional period. Copyright © 2004 John Wiley & Sons, Ltd. [source] Conceptualizing sources in online newsJOURNAL OF COMMUNICATION, Issue 1 2001S S Sundar This study attempts a new conceptualization of communication ,sources' by proposing a typology of sources that would apply not only to traditional media but also to new online media. Ontological rationale for the distinctions in the typology is supplemented by psychological evidence via an experiment that investigated the effects of different types of source attributions upon receivers' perception of online news content. Participants (N=48) in a 4-condition, between-participants experiment read 6 identical news stories each through an online service. Participants were told that the stories were selected by 1 of 4 sources: news editors, the computer terminal on which they were accessing the stories, other audience members (or users) of the online news service, or (using a pseudo-selection task) the individual user (self). After reading each online news story, all participants filled out a paper-and-pencil questionnaire indicating their perceptions of the story they had just read. In confirmation of the distinctions made in the typology, attribution of identical content to 4 different types of online sources was associated with significant variation in news story perception. Theoretical implications of the results as well as the typology are discussed. [source] 10 A Rapid, Simple and Inexpensive Method for Construction of Peripheral Vascular Ultrasound PhantomsACADEMIC EMERGENCY MEDICINE, Issue 2008Hal Minnigan Background and Introduction:, Emergency department bedside ultrasound has grown to include ultrasound guidance of vascular access, most recently, peripheral IV access has been described with ultrasound guidance. Simulation of procedures that are crucial to clinical practice is an efficient and reliable way to train and assess competency prior to performance on an actual patient. Ultrasound phantoms that simulate patient anatomy allow the development of hand-eye coordination, orientation and manipulation of the instruments in a controlled setting. In an effort to obviate the cost of commercial products I have developed a very simple and rapid method for building vascular ultrasound phantoms for teaching ultrasound guided peripheral IV placement. Materials and Methods:, Using easily obtainable and inexpensive materials, a simple method is described which allows construction of the phantom in less than 1 hour. This method requires no special tools or construction skills. The total cost for 1 phantom is about $30.00. Most of the components can be reused when the phantom needs to be repoured , the cost to repour a phantom is less than 2. Results:, These phantoms are realistic in terms of visualization of deep upper extremity veins, and include fluid filled vessels which are gravity fed by colored saline. The system is versatile and can be customized to fit the needs of the individual user. Attendees will be provided with a CD comprising a complete materials list with sources of supply, a PowerPoint presentation to guide construction with each step detailed using digital photographs, and videos of use of the phantom. [source] Paper Versus Electronic Medical Records: The Effects of Access on Physicians' Decisions to Use Complex Information Technologies,DECISION SCIENCES, Issue 2 2009Virginia Ilie ABSTRACT This study examines physicians' responses to complex information technologies (IT) in the health care supply chain. We extend individual-level IT adoption models by incorporating a new construct: system accessibility. The main premise of the study is, when faced with a decision between alternate IT systems, individual users tend to select and make use of the technology or system that is most readily accessible. We discuss both physical and logical dimensions of accessibility as they relate to adoption of electronic medical records (EMR). Physical accessibility refers to the availability of computers that can be used to access EMR, while logical accessibility refers to the ease or difficulty of logging into the system. Using data from a survey of 199 physicians practicing in a large U.S. hospital, we show that, when deciding between the paper chart and EMR, accessibility is an important consideration in a physician's decision to use the system. Both dimensions of accessibility act as barriers to EMR use intentions through their indirect effect on physicians' perceptions of EMR usefulness and ease of use. Logical access also has a direct effect on EMR use intentions. We conclude that accessibility is an important factor that limits acceptance of complex IT such as EMR. [source] An Investigation of Localization as an Element of Cognitive Fit in Accounting Model RepresentationsDECISION SCIENCES, Issue 1 2001Cheryl Dunn Abstract Cognitive fit, a correspondence between task and data representation format, has been demonstrated to lead to superior task performance by individual users and has been posited as an explanation for performance differences among users of various problem representations such as tables, graphs, maps, and schematic faces. The current study extends cognitive fit to accounting models and integrates cognitive fit theory with the concept of localization to provide additional evidence for how cognitive fit works. Two accounting model representations are compared in this study, the traditional DCA (Debit-Credit-Account) accounting model and the REA (Resources-Events-Agents) accounting model. Results indicate that the localization of relevant objects or linkages is important in establishing cognitive fit. [source] Adaptive directional-aware location update strategyINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2004Tracy Tung Abstract In this paper, a new tracking strategy, the directivity-aware location updating scheme was developed to better utilize the distinct characteristics of individual users on travelling directions. In this new adaptive scheme, an optimal distance-based update threshold is selected according to the call-to-mobility ratio and a transitional directivity index, introduced to give indications of the mobile's travelling patterns. It is found that as far as mobility characteristics are concerned, the actual transitional direction of roaming mobiles plays a significant role in selecting the optimal threshold in addition to the usual perception about mobility rate. Its advantage becomes even more visible when an optimal threshold is not theoretically obtainable due to certain restrictions imposed by the network during times of high system loadings. Simulation results show that the additional information made available about roaming mobile's transitional directivity is critical to ensure that the best available sub-optimal threshold is realizable. Other advances in this paper include the simplification of existing Markovian movement model. With the improved model presentation, the number of states necessary to simulate such memoryless movements is reduced. Consequently, the computational complexity involved is also lessened. Copyright © 2004 John Wiley & Sons, Ltd. [source] NATURAL RESOURCE EXPLOITATION UNDER COMMON PROPERTY RIGHTSNATURAL RESOURCE MODELING, Issue 1 2003MICHAEL R. CAPUTO ABSTRACT. Renewable natural resources such as ground-water, pastures and fisheries are often governed bycommon propertyrights in which members of a group jointlyown the exclusive use of the resource. We develop a formal model of a common propertycontract based on differential game theory and then use the model to examine (i) the incentives of individual users of the common resource; (ii) the resulting harvest and stock time paths; (iii) the local stabilityof the steady state; and (iv) the steadystate comparative statics. Moreover, we compare the qualitative properties of the common propertyregime to those generated under perfectlydefined private rights and open access. We show how common prop-ertyownership of natural resources can generate rent and be a second-best solution when private propertyrights are costly to establish. [source] Measures of skill and value of ensemble prediction systems, their interrelationship and the effect of ensemble sizeTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 577 2001David S. Richardson Abstract Ensemble forecasts provide probabilistic predictions for the future state of the atmosphere. Usually the probability of a given event E is determined from the fraction of ensemble members which predict the event. Hence there is a degree of sampling error inherent in the predictions. In this paper a theoretical study is made of the effect of ensemble size on forecast performance as measured by a reliability diagram and Brier (skill) score, and on users by using a simple cost-loss decision model. The relationship between skill and value, and a generalized skill score, dependent on the distribution of users, are discussed. The Brier skill score is reduced from its potential level for all finite-sized ensembles. The impact is most significant for small ensembles, especially when the variance of forecast probabilities is also small. The Brier score for a set of deterministic forecasts is a measure of potential predictability, assuming the forecasts are representative selections from a reliable ensemble prediction system (EPS). There is a consistent effect of finite ensemble size on the reliability diagram. Even if the underlying distribution is perfectly reliable, sampling this using only a small number of ensemble members introduces considerable unreliability. There is a consistent over-forecasting which appears as a clockwise tilt of the reliability diagram. It is important to be aware of the expected effect of ensemble size to avoid misinterpreting results. An ensemble of ten or so members should not be expected to provide reliable probability forecasts. Equally, when comparing the performance of different ensemble systems, any difference in ensemble size should be considered before attributing performance differences to other differences between the systems. The usefulness of an EPS to individual users cannot be deduced from the Brier skill score (nor even directly from the reliability diagram). An EPS with minimal Brier skill may nevertheless be of substantial value to some users, while small differences in skill may hide substantial variation in value. Using a simple cost-loss decision model, the sensitivity of users to differences in ensemble size is shown to depend on the predictability and frequency of the event and on the cost-loss ratio of the user. For an extreme event with low predictability, users with low cost-loss ratio will gain significant benefits from increasing ensemble size from 50 to 100 members, with potential for substantial additional value from further increases in number of members. This sensitivity to large ensemble size is not evident in the Brier skill score. A generalized skill score, dependent on the distribution of users, allows a summary performance measure to be tuned to a particular aspect of EPS performance. [source] | |||||||||||||