855 resultados para wireless ad hoc networks


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As part of the Sentinel-3 mission and in order to ensure the highest quality of products, ESA in cooperation with EUMETSAT has set up the Sentinel-3 Mission Performance Centre (S-3 MPC). This facility is part of the Payload Data Ground Segment (PDGS) and aims at controlling the quality of all generated products, from L0 to L2. The S-3 MPC is composed of a Coordinating Centre (CC), where the core infrastructure is hosted, which is in charge of the main routine activities (especially the quality control of data) and the overall service management. Expert Support Laboratories (ESLs) are involved in calibration and validation activities and provide specific assessment of the products (e.g., analysis of trends, ad hoc analysis of anomalies, etc.). The S-3 MPC interacts with the Processing Archiving Centres (PACs) and the Marine centre at EUMETSAT.

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Three different worlds, sometimes concentric and often intersecting —society, theatre and the art of performance— and social work. Diverse worlds that live, reflect and self-reflect and interact, and can also afford an opportunity for meeting, misunderstanding and confrontation, and above all offer the possibility of profound change.This article considers the experience of a theatre company that has spent more than three years moving at the limits of these three universes. To these three worlds can be added an infinite number of words that fill them with meaning and significance: territory, meeting, diversity and search. An artistic experience that has chosen to focus on creating scenarios for debate and to examine the difficulties, the human contradictions and the constant and inexhaustible confrontation with human experience. At the heart of this theatrical activity is all of this, seeking the balance between narration, meeting, investigation and the artistic dimension. This meeting between society, theatre and social work also contains the search for sustainability of this cultural business, in an Italy that has been destroyed by a crisis that is not merely economic, but also of values and, above all, of role models. The guiding theme, though not always made explicit, is always present and essential: the search for beauty.

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Wireless enabled portable devices must operate with the highest possible energy efficiency while still maintaining a minimum level and quality of service to meet the user's expectations. The authors analyse the performance of a new pointer-based medium access control protocol that was designed to significantly improve the energy efficiency of user terminals in wireless local area networks. The new protocol, pointer controlled slot allocation and resynchronisation protocol (PCSAR), is based on the existing IEEE 802.11 point coordination function (PCF) standard. PCSAR reduces energy consumption by removing the need for power saving stations to remain awake and listen to the channel. Using OPNET, simulations were performed under symmetric channel loading conditions to compare the performance of PCSAR with the infrastructure power saving mode of IEEE 802.11, PCF-PS. The simulation results demonstrate a significant improvement in energy efficiency without significant reduction in performance when using PCSAR. For a wireless network consisting of an access point and 8 stations in power saving mode, the energy saving was up to 31% while using PCSAR instead of PCF-PS, depending upon frame error rate and load. The results also show that PCSAR offers significantly reduced uplink access delay over PCF-PS while modestly improving uplink throughput.

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Transparency in nonprofit sector and foundations, as an element to enhance the confidence of stakeholders in the organization, is a fact shown by several studies in recent decades. Transparency can be considered in various fields and through different channels. In our study we focused on the analysis of the organizational and economic transparency of foundations, shown through the voluntary information on their Website. We review the theoretical previous studies published to put to the foundations within the framework of the social economy. This theoretical framework has focused on accountability that make foundations in relation to its social function and its management, especially since the most recent focus of information transparency across the Website.In this theoretical framework was made an index to quantify the voluntary information which is shown on its website. This index has been developed ad hoc for this study and applied to a group of large corporate foundations.With the application of these data are obtained two kind of results, to a descriptive level and to a inferential level.We analyzed the statistical correlation between economic transparency and organizational transparency offered in the Website through quantified variables by a multiple linear regression. This empirical analysis allows us to draw conclusions about the level of transparency offered by these organizations in relation to their organizational and financial information, as well as explain the relation between them.

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This work aims to analyze the perceptions of students enrolled in the Master's Degree in Secondary Education Teaching, Training and Language Teaching at the University of Jaen, about the initial training received on attention to diversity. A descriptive methodology has been followed using an ad hoc questionnaire as data collection instrument. The results show favorable attitudes of future secondary teachers for diversity, having received an adequate training in curricular and organizational aspects, making it able to fully achieve inclusion of students with special educational needs in the classroom.

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La Educación para la Salud (EpS) es un tema transversal del currículo que adolece de propuestas didácticas novedosas para la intervención pedagógica. El objetivo del trabajo que se presenta es poner en marcha un plan de mejora para la prevención de drogadicciones en adolescentes. Para ello, se ha trabajado con un total de 142 estudiantes de 3º de Educación Secundaria Obligatoria (ESO) con edades comprendidas entre los 14 y los 16 años que cursan estudios en el Instituto “Francisco Salzillo” de la localidad de Alcantarilla (Murcia). Concretamente, este artículo da luz al Proyecto ¡Abre los ojos!, que forma parte del Plan de Acción Tutorial (PAT) y del Plan de Mejora para la Prevención de Drogas (PMPD) propuesto desde el Departamento de Orientación. Se exponen ad hoc las actividades implementadas durante las 3 sesiones trabajadas con cada uno de los 6 grupos-clase escolarizados en este nivel. Haciendo uso de la reflexión-acción, el alumnado ha desarrollado una conciencia crítica acerca de los riesgos que entraña para la salud el consumo de drogas. Asimismo, mediante la técnica de grupos de discusión los discentes han realizado un interesante debate cuyas ideas han sido organizadas en torno a tres aspectos clave: causas por las que se empieza a consumir, cómo evitar caer en las drogas, y alternativas de ocio y tiempo libre para una vida saludable. Finalmente, se especifica la necesidad de abordar tareas de prevención en los centros educativos así como de facilitar información y de resolver las inquietudes de los jóvenes acerca de esta temática.

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Students' learning process can be negatively affected when their reading and comprehension control is not appropriated. This research focuses on the analysis of how a group of students from high school evaluate their reading comprehension in manipulated scientific texts. An analysis tool was designed to determine the students' degree of comprehension control when reading a scientific short text with an added contradiction. The results have revealed that the students from 1st and 3rd ESO do not properly self-evaluated their reading comprehension. A different behavior has been observed in 1st Bachillerato, where appropriate evaluation and regulation seem to be more frequent. Moreover, no significant differences have been found regarding the type of text, year or gender. Finally, as identified by previous research, the correlations between the students' comprehension control and their school marks have shown to have a weak relationship and inversely proportional to the students' age.

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Background: Infection remains a severe complication following a total hip replacement. If infection is suspected when revision surgery is being performed, additional gentamicin is often added to the cement on an ad hoc basis in an attempt to reduce the risk of recurrent infection.

Methods and results: In this in vitro study, we determined the effect of incorporating additional gentamicin on the mechanical properties of cement. We also determined the degree of gentamicin release from cement, and also the extent to which biofilms of clinical Staphylococcus spp. isolates form on cement in vitro. When gentamicin was added to unloaded cement (1–4 g), there was a significant reduction in the mechanical performance of the loaded cements compared to unloaded cement. A significant increase in gentamicin release from the cement over 72 h was apparent, with the amount of gentamicin released increasing significantly with each additional 1 g of gentamicin added. When overt infection was modeled, the incorporation of additional gentamicin did result in an initial reduction in bacterial colonization, but this beneficial effect was no longer apparent by 72 h, with the clinical strains forming biofilms on the cements despite the release of high levels of gentamicin.

Interpretation: Our findings indicate that the addition of large amounts of gentamicin to cement is unlikely to eradicate bacteria present as a result of an overt infection of an existing implant, and could result in failure of the prosthetic joint because of a reduction in mechanical performance of the bone cement.

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This study highlights how heuristic evaluation as a usability evaluation method can feed into current building design practice to conform to universal design principles. It provides a definition of universal usability that is applicable to an architectural design context. It takes the seven universal design principles as a set of heuristics and applies an iterative sequence of heuristic evaluation in a shopping mall, aiming to achieve a cost-effective evaluation process. The evaluation was composed of three consecutive sessions. First, five evaluators from different professions were interviewed regarding the construction drawings in terms of universal design principles. Then, each evaluator was asked to perform the predefined task scenarios. In subsequent interviews, the evaluators were asked to re-analyze the construction drawings. The results showed that heuristic evaluation could successfully integrate universal usability into current building design practice in two ways: (i) it promoted an iterative evaluation process combined with multi-sessions rather than relying on one evaluator and on one evaluation session to find the maximum number of usability problems, and (ii) it highlighted the necessity of an interdisciplinary ad hoc committee regarding the heuristic abilities of each profession. A multi-session and interdisciplinary heuristic evaluation method can save both the project budget and the required time, while ensuring a reduced error rate for the universal usage of the built environments.

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The government of Greece has gained notoriety for its failure to implement EU environmental directives in general, and is criticised specifically for its lack of an effective plan for the safe disposal of waste. Local mobilisations against a series of planned 'Sanitary Waste Disposal Sites' (HETAs) in three municipalities of Attica are examined. Should such protests be classified as NIMBY (not in my backyard)? Or do they present broader claims of justice and equity? Qualitative analysis of the protesters' on-line campaign material reveals that while these mobilisations do demonstrate some NIMBY characteristics, such campaigns should rather be perceived as ad hoc mobilisations reflective of tensions of late modernity. The public's mistrust of science and concerns about democratic deficit and accountability, as well as different perceptions of risk, are prominent.

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The role of dispersion or van de Waals (VDW) interactions in imidazolium-based room-temperature ionic liquids is studied within the framework of density functional theory, using a recently developed non-empirical functional [M. Dion, H. Rydberg, E. Schroder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)], as efficiently implemented in the SIESTA code [G. Roman-Perez and J. M. Soler, Phys. Rev. Lett. 103, 096102 (2009)]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to both the local density (LDA) and the generalized gradient approximations (GGA). Similar to other systems characterized by VDW bonding, such as rare gas and benzene dimers as well as solid argon, equilibrium distances and volumes are consistently overestimated by approximate to 7%, compared to -11% within LDA and 11% within GGA. The intramolecular geometries are retained, while the intermolecular distances and orientations are significantly improved relative to LDA and GGA. The quality is superior to that achieved with tailor-made empirical VDW corrections ad hoc [M. G. Del Popolo, C. Pinilla, and P. Ballone, J. Chem. Phys. 126, 144705 (2007)]. We also analyse the performance of an optimized version of this non-empirical functional, where the screening properties of the exchange have been tuned to reproduce high-level quantum chemical calculations [J. Klimes, D. Bowler, and A. Michaelides, J. Phys.: Condens. Matter 22, 074203 (2010)]. The results for solids are even better with volumes and geometries reproduced within 2% of experimental data. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and we present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] neutral and charged clusters, which validate the use of empirical force fields. (C) 2011 American Institute of Physics. [doi:10.1063/1.3652897]

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The use of dataflow digital signal processing system modelling
and synthesis techniques has been a fruitful research theme for many years and has yielded many powerful rapid system synthesis and optimisation capabilities. However, recent years have seen the spectrum of languages and techniques splinter in an application specific manner, resulting in an ad-hoc design process which is increasingly dependent on the particular application under development. This poses a major problem for automated toolflows attempting to provide rapid system synthesis for a wide ranges of applications. By analysing a number of dataflow FPGA implementation case studies, this paper shows that despit ethis common traits may be found in current techniques, which fall largely into three classes. Further, it exposes limitations pertaining to their ability to adapt algorith models to implementations for different operating environments and target platforms.

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Organizations are becoming relentless in managing and developing their key talent. This is a view, however, largely based on anecdote rather than reliable empirical evidence. Utilizing data from 260 multinational enterprises (MNEs), this paper helps redress this deficit. Specifically, this paper explores the extent to which MNEs engage in global talent management (GTM) and deciphers some of the factors which may explain the use and non-use of GTM practices. In so doing, we find that although a significant number of MNEs have systems and mechanisms in place to strategically identify and develop their talent many more seemingly adopt an ad hoc or haphazard approach. For instance, less than half of all MNEs have both global succession planning and formal management development programs for their high-potentials. Consequently it seems that there is a considerable distance yet to be travelled to arrive at a universal appreciation of the need to strategically manage one's key employees. We find the size of the MNE has a significant effect on GTM system usage-larger MNEs are more likely to undertake GTM. Other significant, positive influences include whether products or services are standardized regionally or globally, and if the MNE has a global human resources policy formation body. Of considerable interest is the finding that MNEs operating in the low-tech/low-cost sectors are significantly more likely to have formal global systems to identify and develop high-potentials. © 2009 Elsevier Inc. All rights reserved.

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The adequacy of provisions for young people leaving care and in aftercare in the Republic of Ireland have been the subject of recent policy attention. A landmark report, the Ryan Report (2009), into historic abuse in state institutions recommended strengthening provisions in this area. However, the legislative basis for aftercare remains relatively weak and services for young people leaving care remain ad hoc and regionally variable. This article outlines the current context of leaving and aftercare provision in the Republic of Ireland and traces some of the recent policy debates and recommendations in this area. A genealogical analysis of leaving care and aftercare provision highlights that this issue has historically only emerged as a concern in the context in which young people leaving the care system are perceived as a ‘threat’ to social order. It is argued that the failure to adequately reform leaving and aftercare provision is reflective of wider social inequality and of a context in which young people in care are largely invisible from view.

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As awareness of the limitations of relying solely on income to measure poverty has become more widespread, attention has been increasingly focused on multi-dimensional approaches, to the point where the EU has adopted a multidimensional poverty and social exclusion target for 2020. The rationale advanced is that the computation of a multidimensional poverty index is an effective way of communicating in a political environment, and a necessary tool in order to monitor 27 different national situations. By contrast with the rather ad hoc way in which the EU 2020 poverty target has been framed and rationalised, the adjusted head count ratio applied here has a number of desirable axiomatic properties. It constitutes a significant improvement on union and intersection approaches and allows for the decomposition of multidimensional poverty in terms of dimensions of deprivation and socio-economic attributes. Since understanding poverty as multidimensional does not necessarily require constructing a multidimensional poverty index, on the basis of our analysis we provide a more general consideration of the value of developing a multidimensional index of poverty for the European Union.