851 resultados para Time and space
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Background: Previous attempts at costing infection control programmes have tended to focus on accounting costs rather than economic costs. For studies using economic costs, estimates tend to be quite crude and probably underestimate the true cost. One of the largest costs of any intervention is staff time, but this cost is difficult to quantify and has been largely ignored in previous attempts. Aim: To design and evaluate the costs of hospital-based infection control interventions or programmes. This article also discusses several issues to consider when costing interventions, and suggests strategies for overcoming these issues. Methods: Previous literature and techniques in both health economics and psychology are reviewed and synthesized. Findings: This article provides a set of generic, transferable costing guidelines. Key principles such as definition of study scope and focus on large costs, as well as pitfalls (e.g. overconfidence and uncertainty), are discussed. Conclusion: These new guidelines can be used by hospital staff and other researchers to cost their infection control programmes and interventions more accurately.
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Processes in complex chemical systems, such as macromolecules, electrolytes, interfaces, micelles and enzymes, can span several orders of magnitude in length and time scales. The length and time scales of processes occurring over this broad time and space window are frequently coupled to give rise to the control necessary to ensure specificity and the uniqueness of the chemical phenomena. A combination of experimental, theoretical and computational techniques that can address a multiplicity of length and time scales is required in order to understand and predict structure and dynamics in such complex systems. This review highlights recent experimental developments that allow one to probe structure and dynamics at increasingly smaller length and time scales. The key theoretical approaches and computational strategies for integrating information across time-scales are discussed. The application of these ideas to understand phenomena in various areas, ranging from materials science to biology, is illustrated in the context of current developments in the areas of liquids and solvation, protein folding and aggregation and phase transitions, nucleation and self-assembly.
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In this thesis the current status and some open problems of noncommutative quantum field theory are reviewed. The introduction aims to put these theories in their proper context as a part of the larger program to model the properties of quantized space-time. Throughout the thesis, special focus is put on the role of noncommutative time and how its nonlocal nature presents us with problems. Applications in scalar field theories as well as in gauge field theories are presented. The infinite nonlocality of space-time introduced by the noncommutative coordinate operators leads to interesting structure and new physics. High energy and low energy scales are mixed, causality and unitarity are threatened and in gauge theory the tools for model building are drastically reduced. As a case study in noncommutative gauge theory, the Dirac quantization condition of magnetic monopoles is examined with the conclusion that, at least in perturbation theory, it cannot be fulfilled in noncommutative space.
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A case study of an aircraft engine manufacturer is used to analyze the effects of management levers on the lead time and design errors generated in an iteration-intensive concurrent engineering process. The levers considered are amount of design-space exploration iteration, degree of process concurrency, and timing of design reviews. Simulation is used to show how the ideal combination of these levers can vary with changes in design problem complexity, which can increase, for instance, when novel technology is incorporated in a design. Results confirm that it is important to consider multiple iteration-influencing factors and their interdependencies to understand concurrent processes, because the factors can interact with confounding effects. The article also demonstrates a new approach to derive a system dynamics model from a process task network. The new approach could be applied to analyze other concurrent engineering scenarios. © The Author(s) 2012.
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The dynamics of high energetic electrons (>= 11.7 eV) in a modified industrial confined dual-frequency capacitively coupled RF discharge (Exelan, Lam Research Inc.), operated at 1.937 MHz and 27.118 MHz, is investigated by means of phase resolved optical emission spectroscopy. Operating in a He-O-2. plasma with small rare gas admixtures the emission is measured, with one-dimensional spatial resolution along the discharge axis. Both the low and high frequency RF cycle are resolved. The diagnostic is based on time dependent measurements of the population densities of specifically chosen excited rare gas states. A time dependent model, based on rate equations, describes the dynamics of the population densities of these levels. Based on this model and the comparison of the excitation of various rare gas states, with different excitation thresholds, time and space resolved electron temperature, propagation velocity and qualitative electron density as well as electron energy distribution functions are determined. This information leads to a better understanding of the dual-frequency sheath dynamics and shows, that separate control of ion energy and electron density is limited.
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Abundant evidence for the occurrence of modulated envelope plasma wave packets is provided by recent satellite missions. These excitations are characterized by a slowly varying localized envelope structure, embedding the fast carrier wave, which appears to be the result of strong modulation of the wave amplitude. This modulation may be due to parametric interactions between different modes or, simply, to the nonlinear (self-)interaction of the carrier wave. A generic exact theory is presented in this study, for the nonlinear self-modulation of known electrostatic plasma modes, by employing a collisionless fluid model. Both cold (zero-temperature) and warm fluid descriptions are discussed and the results are compared. The (moderately) nonlinear oscillation regime is investigated by applying a multiple scale technique. The calculation leads to a Nonlinear Schrodinger-type Equation (NLSE), which describes the evolution of the slowly varying wave amplitude in time and space. The NLSE admits localized envelope (solitary wave) solutions of bright(pulses) or dark- (holes, voids) type, whose characteristics (maximum amplitude, width) depend on intrinsic plasma parameters. Effects like amplitude perturbation obliqueness (with respect to the propagation direction), finite temperature and defect (dust) concentration are explicitly considered. Relevance with similar highly localized modulated wave structures observed during recent satellite missions is discussed.
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Darwin's On the Origin of Species has led to a theory of evolution with a mass of empirical detail on population genetics below species level, together with heated debate on the details of macroevolutionary patterns above species level. Most of the main principles are clear and generally accepted, notably that life originated once and has evolved over time by descent with modification. Here, I review the fossil and molecular phylogenetic records of the response of life on Earth to Quaternary climatic changes. I suggest that the record can be best understood in terms of the nonlinear dynamics of the relationship between genotype and phenotype, and between climate and environments. 'The origin of species' is essentially unpredictable, but is nevertheless an inevitable consequence of the way that organisms reproduce through time. The process is 'chaotic', but not 'random'. I suggest that biodiversity is best considered as continuously branching systems of lineages, where 'species' are the branch tips. The Earth's biodiversity should thus (1) be in a state of continuous increase and (2) show continuous discrepancies between genetic and morphological data in time and space. © The Palaeontological Association.
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As a leading facility in laser-driven nuclear physics, ELI-NP will develop innovative research in the fields of materials behavior in extreme environments and radiobiology, with applications in the development of accelerator components, new materials for next generation fusion and fission reactors, shielding solutions for equipment and human crew in long term space missions and new biomedical technologies. The specific properties of the laser-driven radiation produced with two lasers of 1 PW at a pulse repetition rate of 1 Hz each are an ultra-short time scale, a relatively broadband spectrum and the possibility to provide simultaneously several types of radiation. Complex, cosmic-like radiation will be produced in a ground-based laboratory allowing comprehensive investigations of their effects on materials and biological systems. The expected maximum energy and intensity of the radiation beams are 19 MeV with 10^9 photon/pulse for photon radiation, 2 GeV with 108 electron/pulse for electron beams, 60 MeV with 10^12 proton/pulse for proton and ion beams and 60 MeV with 107 neutron/pulse for a neutron source. Research efforts will be directed also towards measurements for radioprotection of the prompt and activated dose, as a function of laser and target characteristics and to the development and testing of various dosimetric methods and equipment.
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In this paper I explore connections between women, art education and spatial relations drawing on the Deleuzo-Guattarian concept of machinic assemblage as a useful analytical tool for making sense of the heterogeneity and meshwork of life narratives and their social milieus. In focusing on Mary Bradish Titcomb, a fin-de-sie`cle Bostonian woman who lived and worked in the interface of education and art, moving in between differentiated series of social, cultural and geographical spaces, I challenge an image of narratives as unified and coherent representations of lives and subjects; at the same time I am pointing to their importance in opening up microsociological analyses of deterritorializations and lines of flight. What I argue is that an attention to space opens up paths for an analytics of becomings, and enables the theorization of open processes, multiplicities and nomadic subjectivities in the field of gender and education.
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Real-time systems demand guaranteed and predictable run-time behaviour in order to ensure that no task has missed its deadline. Over the years we are witnessing an ever increasing demand for functionality enhancements in the embedded real-time systems. Along with the functionalities, the design itself grows more complex. Posed constraints, such as energy consumption, time, and space bounds, also require attention and proper handling. Additionally, efficient scheduling algorithms, as proven through analyses and simulations, often impose requirements that have significant run-time cost, specially in the context of multi-core systems. In order to further investigate the behaviour of such systems to quantify and compare these overheads involved, we have developed the SPARTS, a simulator of a generic embedded real- time device. The tasks in the simulator are described by externally visible parameters (e.g. minimum inter-arrival, sporadicity, WCET, BCET, etc.), rather than the code of the tasks. While our current implementation is primarily focused on our immediate needs in the area of power-aware scheduling, it is designed to be extensible to accommodate different task properties, scheduling algorithms and/or hardware models for the application in wide variety of simulations. The source code of the SPARTS is available for download at [1].
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Abstract: This dissertation generally concentrates on the relationships between “gender” and “space” in the present time of urban life in capital city of Tehran. “Gender” as a changing social construct, differentiated within societies and through time, studied this time by investigation on “gender attitude” or “gender identity” means attitudes towards “gender” issues regarding Tehran residences. “Space” as a concept integrated from physical and social constituents investigated through focus on “spatial attitude” means attitudes towards using “living spaces” including private space of “house”, semi private semi public space of neighborhood and finally public spaces of the city. “Activities and practices” in space concentrated instead of “physical” space; this perspective to “space” discussed as the most justified implication of “space” in this debate regarding current situations in city of Tehran. Under a systematic approach, the interactions and interconnections between “gender” and “space” as two constituent variables of social organization investigated by focus on the different associations presented between different “gender identities” and their different “spatial identities”; in fact, “spatial identity” manifests “gender identity” and in opposite direction, “spatial identity” influences to construction of “gender identity”. The hypotheses of case study in Tehran defined as followed: • “Gender identity” is reflected on “spatial identity”. Various “gender identities” in Tehran present different perspectives of “space” or they identify “space” by different values. • As “gender identity” internalizes patriarchal oppression, it internalizes associated “spatial” oppression too. • Within the same social class, different “gender identities” related to men and women, present interconnected qualities, compared with “gender identities” related to men or women of different social classes. This situation could be found in the “spatial” perspectives of different groups of men and women too. • Following the upper hypotheses, “spatial” oppression differs among social classes of Tehran living in different parts of this city. This research undertook a qualitative study in Tehran by interviewing with different parents of both young daughter and son regarding their attitudes towards gender issues from one side and activities and behaviors of their children in different spaces from the other side. Results of case study indicated the parallel changes of parents’ attitudes towards “gender” and “spatial” issues; it means strong connection between “gender” and “space”. It revealed association of “equal” spatial attitudes with “open, neutral” gender attitudes, and also the association of “biased, unequal” spatial identities with “conservative patriarchal” gender identities. It was cleared too that this variable concept – gender space - changes by “sex”; mothers comparing fathers presented more equitable notions towards “gender spatial” issues. It changes too by “social class” and “educational level”, that means “gender spatial” identity getting more open equitable among more educated people of middle and upper classes. “Breadwinning status in the family” also presents its effect on the changes of “gender spatial” identity so participant breadwinners in the family expressed relatively more equitable notions comparing householders and housekeepers. And finally, “gender spatial” identity changes through “place” in the city and regarding South – North line of the city. The illustration of changes of “gender spatial” identity from “open” to “conservative” among society indicated not only vertical variation across social classes, furthermore the horizontal changing among each social class. These results also confirmed hypotheses while made precision on the third one regarding variable of sex. More investigations pointed to some inclusive spatial attitudes throughout society penetrated to different groups of “gender identities”, to “opens” as to “conservatives”, also to groups between them, by two opposite features; first kind, conservative biased spatial practices in favor of patriarchal gender relations and the second, progressive neutral actions in favor of equal gender relations. While the major reason for the inclusive conservative practices was referred to the social insecurity for women, the second neutral ones associated to more formal & safer spaces of the city. In conclusion, while both trends are associated deeply with the important issues of “sex” & “body” in patriarchal thoughts, still strong, they are the consequences of the transitional period of social change in macro level, and the challenges involved regarding interactions between social orders, between old system of patriarchy, the traditional biased “gender spatial” relations and the new one of equal relations. The case study drew an inhomogeneous illustration regarding gender spatial aspects of life in Tehran, the opposite groups of “open” and “conservative”, and the large group of “semi open semi conservative” between them. In macro perspective it presents contradicted social groups according their general life styles; they are the manifestations of challenging trends towards tradition and modernity in Iranian society. This illustration while presents unstable social situations, necessitates probing solutions for social integration; exploring the directions could make heterogeneous social groups close in the way they think and the form they live in spaces. Democratic approaches like participatory development planning might be helpful for the city in its way to more solidarity and sustainability regarding its social spatial – gender as well – development, in macro levels of social spatial planning and in micro levels of physical planning, in private space of house and in public spaces of the city.
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We introduce and describe the Multiple Gravity Assist problem, a global optimisation problem that is of great interest in the design of spacecraft and their trajectories. We discuss its formalization and we show, in one particular problem instance, the performance of selected state of the art heuristic global optimisation algorithms. A deterministic search space pruning algorithm is then developed and its polynomial time and space complexity derived. The algorithm is shown to achieve search space reductions of greater than six orders of magnitude, thus reducing significantly the complexity of the subsequent optimisation.
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Changes in the cultures and spaces of death during the Victorian era reveal the shifting conceptualisations and mobilisations of class in this period. Using the example of Brookwood Necropolis, established 1852 in response to the contemporary burial reform debate, the paper explores tensions within the sanitary reform movement, 1853–1903. Whilst reformist ideology grounded the cemetery's practices in a discourse of inclusion, one of the consequences of reform was to reinforce class distinctions. Combined with commercial imperatives and the modern impulse towards separation of living and dead, this aspect of reform enacted a counter-discourse of alienation. The presence of these conflicting strands in the spaces and practices of the Necropolis and their changes during the time period reflect wider urban trends.
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The thesis work concerns X-ray spectrometry for both medical and space applications and is divided into two sections. The first section addresses an X-ray spectrometric system designed to study radiological beams and is devoted to the optimization of diagnostic procedures in medicine. A parametric semi-empirical model capable of efficiently reconstructing diagnostic X-ray spectra in 'middle power' computers was developed and tested. In addition, different silicon diode detectors were tested as real-time detectors in order to provide a real-time evaluation of the spectrum during diagnostic procedures. This project contributes to the field by presenting an improved simulation of a realistic X-ray beam emerging from a common X-ray tube with a complete and detailed spectrum that lends itself to further studies of added filtration, thus providing an optimized beam for different diagnostic applications in medicine. The second section describes the preliminary tests that have been carried out on the first version of an Application Specific Integrated Circuit (ASIC), integrated with large area position-sensitive Silicon Drift Detector (SDD) to be used on board future space missions. This technology has been developed for the ESA project: LOFT (Large Observatory for X-ray Timing), a new medium-class space mission that the European Space Agency has been assessing since February of 2011. The LOFT project was proposed as part of the Cosmic Vision Program (2015-2025).
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The purpose of this study was to evaluate summer and fall residency and habitat selection by gray whales, Eschrichtius robustus, together with the biomass of benthic amphipod prey on the coastal feeding grounds along the Chukotka Peninsula. Thirteen gray whales were instrumented with satellite transmitters in September 2006 near the Chukotka Peninsula, Russia. Nine transmitters provided positions from whales for up to 81 days. The whales travelled within 5 km of the Chukotka coast for most of the period they were tracked with only occasional movements offshore. The average daily travel speeds were 23 km/day (range 9-53 km/day). Four of the whales had daily average travel speeds <1 km/day suggesting strong fidelity to the study area. The area containing 95% of the locations for individual whales during biweekly periods was on average 13,027 km**2 (range 7,097-15,896 km**2). More than 65% of all locations were in water <30 m, and between 45 and 70% of biweekly kernel home ranges were located in depths between 31 and 50 m. Benthic density of amphipods within the Bering Strait at depths <50 m was on average ~54 g wet wt/m**2 in 2006. It is likely that the abundant benthic biomass is more than sufficient forage to support the current gray whale population. The use of satellite telemetry in this study quantifies space use and movement patterns of gray whales along the Chukotka coast and identifies key feeding areas.