913 resultados para Mean life span


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Catering to society's demand for high performance computing, billions of transistors are now integrated on IC chips to deliver unprecedented performances. With increasing transistor density, the power consumption/density is growing exponentially. The increasing power consumption directly translates to the high chip temperature, which not only raises the packaging/cooling costs, but also degrades the performance/reliability and life span of the computing systems. Moreover, high chip temperature also greatly increases the leakage power consumption, which is becoming more and more significant with the continuous scaling of the transistor size. As the semiconductor industry continues to evolve, power and thermal challenges have become the most critical challenges in the design of new generations of computing systems. ^ In this dissertation, we addressed the power/thermal issues from the system-level perspective. Specifically, we sought to employ real-time scheduling methods to optimize the power/thermal efficiency of the real-time computing systems, with leakage/ temperature dependency taken into consideration. In our research, we first explored the fundamental principles on how to employ dynamic voltage scaling (DVS) techniques to reduce the peak operating temperature when running a real-time application on a single core platform. We further proposed a novel real-time scheduling method, “M-Oscillations” to reduce the peak temperature when scheduling a hard real-time periodic task set. We also developed three checking methods to guarantee the feasibility of a periodic real-time schedule under peak temperature constraint. We further extended our research from single core platform to multi-core platform. We investigated the energy estimation problem on the multi-core platforms and developed a light weight and accurate method to calculate the energy consumption for a given voltage schedule on a multi-core platform. Finally, we concluded the dissertation with elaborated discussions of future extensions of our research. ^

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A wide range of non-destructive testing (NDT) methods for the monitoring the health of concrete structure has been studied for several years. The recent rapid evolution of wireless sensor network (WSN) technologies has resulted in the development of sensing elements that can be embedded in concrete, to monitor the health of infrastructure, collect and report valuable related data. The monitoring system can potentially decrease the high installation time and reduce maintenance cost associated with wired monitoring systems. The monitoring sensors need to operate for a long period of time, but sensors batteries have a finite life span. Hence, novel wireless powering methods must be devised. The optimization of wireless power transfer via Strongly Coupled Magnetic Resonance (SCMR) to sensors embedded in concrete is studied here. First, we analytically derive the optimal geometric parameters for transmission of power in the air. This specifically leads to the identification of the local and global optimization parameters and conditions, it was validated through electromagnetic simulations. Second, the optimum conditions were employed in the model for propagation of energy through plain and reinforced concrete at different humidity conditions, and frequencies with extended Debye's model. This analysis leads to the conclusion that SCMR can be used to efficiently power sensors in plain and reinforced concrete at different humidity levels and depth, also validated through electromagnetic simulations. The optimization of wireless power transmission via SMCR to Wearable and Implantable Medical Device (WIMD) are also explored. The optimum conditions from the analytics were used in the model for propagation of energy through different human tissues. This analysis shows that SCMR can be used to efficiently transfer power to sensors in human tissue without overheating through electromagnetic simulations, as excessive power might result in overheating of the tissue. Standard SCMR is sensitive to misalignment; both 2-loops and 3-loops SCMR with misalignment-insensitive performances are presented. The power transfer efficiencies above 50% was achieved over the complete misalignment range of 0°-90° and dramatically better than typical SCMR with efficiencies less than 10% in extreme misalignment topologies.

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It has been estimated that one in four adults have sedentary lifestyles. In addition there appears to be an increase in obesity across the life span. It is of great importance to the health of this nation to understand how to promote more active lifestyles through the identification of lifestyle behaviors of active individuals and potential predictors of physical activity (PA). Seven hundred and seventy-seven college students were surveyed to investigate the relationship between nutrition related variables (i.e., dietary restraint, nutrition knowledge, food choice and body weight concerns) and PA. In this study, over half of the students reported doing 30 minutes of moderate intensity PA daily. Vigorously active males and females chose low fat foods more often than the less active group. Exercisers and non-exercisers had similar nutrition knowledge. The results of this study suggest that students who are more active are more conscience about making healthier food choices.

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To achieve the goal of sustainable development, the building energy system was evaluated from both the first and second law of thermodynamics point of view. The relationship between exergy destruction and sustainable development were discussed at first, followed by the description of the resource abundance model, the life cycle analysis model and the economic investment effectiveness model. By combining the forgoing models, a new sustainable index was proposed. Several green building case studies in U.S. and China were presented. The influences of building function, geographic location, climate pattern, the regional energy structure, and the technology improvement potential of renewable energy in the future were discussed. The building’s envelope, HVAC system, on-site renewable energy system life cycle analysis from energy, exergy, environmental and economic perspective were compared. It was found that climate pattern had a dramatic influence on the life cycle investment effectiveness of the building envelope. The building HVAC system energy performance was much better than its exergy performance. To further increase the exergy efficiency, renewable energy rather than fossil fuel should be used as the primary energy. A building life cycle cost and exergy consumption regression model was set up. The optimal building insulation level could be affected by either cost minimization or exergy consumption minimization approach. The exergy approach would cause better insulation than cost approach. The influence of energy price on the system selection strategy was discussed. Two photovoltaics (PV) systems – stand alone and grid tied system were compared by the life cycle assessment method. The superiority of the latter one was quite obvious. The analysis also showed that during its life span PV technology was less attractive economically because the electricity price in U.S. and China did not fully reflect the environmental burden associated with it. However if future energy price surges and PV system cost reductions were considered, the technology could be very promising for sustainable buildings in the future.

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Reservoirs that present highly viscous oils require methods to aid in their recovery to the surface. The elev ated oil viscosity hinders its flow through porous media and conventional recovery methods have not obtained significant efficiency. As such, the injection of steam into the reservoir through an injection well has been the most widely used method of therma l recovery, for it allows elevated volumes of recovery due to the viscosity reduction of the oil, facilitating the oil’s mobility within the rock formation and consequently into the production well where it will be exploited. On the other hand, the injecti on of vapor not only affects the fluids found in the rock pores, but the entire structure that composes the well where it is injected due to the high temperatures used in the process. This temperature increment is conducted to the cement, found in the annu lus, responsible for the isolation of the well and the well casing. Temperatures above 110 ̊C create new fazes rich in calcium in the cement matrix, resulting in the reduction of its permeability and the consequential phenomenon of mechanical resistance ret rogression. These alterations generate faults in the cement, reducing the well’s hydraulic isolation, creating insecurity in the operations in which the well will be submitted as well as the reduction of its economic life span. As a way of reducing this re trograde effect, this study has the objective of evaluating the incorporation of rice husk ash as a mineral additive substitute of silica flour , commercially utilized as a source of silica to reduce the CaO/SiO 2 ratio in the cement pastes submitted to high temperatures in thermal recovery. Cement pastes were formulated containing 20 and 30% levels of ash, apart from the basic paste (water + cement) and a reference paste (water + cement + 40% silica flour) for comparison purposes. The tests were executed th rough compression resistance tests, X - Ray diffraction (XRD) techniques, thermogravimetry (TG), scanning electron microscopy (SEM) and chemical anal ysis BY X - ray fluorescence (EDS) on the pastes submitted to cure at low temperatures (45 ̊C) for 28 days following a cure at 280 ̊C and a pressure of 2,000 PSI for 3 days, simulating vapor injection. The results obtained show that the paste containing 30% r ice shell ash is satisfactory, obtaining mechanical resistance desired and equivalent to that of the paste containing 40% silica flour, since the products obtained were hydrated with low CaO/SiO 2 ratio, like the Tobermorita and Xonotlita fases, proving its applicability in well subject to vapor injection.

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Aimed to identify, for assessing the tillering dynamics and morphogenesis , strategy (s ) suitable ( s) defoliation management to optimize the appearance of tillers and biomass of Urochloa Brizantha syn. Brachiaria brizantha cv. Marandu ( marandugrass ) throughout the year. The experiment was conducted from January 2013 to May 2014 were studied three strategies defoliation: Marandugrass with 30 cm throughout the experimental period (constant height); Marandugrass 15 cm in winter, the spring 30 cm and 45 cm in summer (increasing height); and Marandugrass 45 cm in winter, the spring 30 cm and 15 cm in summer (descending height). The experimental design was completely randomized in a split plot in time, with four replications. In winter, in the spring and summer, the following variables were calculated: appearance rate (TApP), mortality (TMoP) and survival (TSoP) of tillers, balance (BAL) between TApP and TMoP, stability index (IE) numbers of tillers and leaf elongation rates and stem, length of leaf blade and stem, leaf senescence rate, phyllochron and duration of life of the sheet. The TAPP was higher in the early spring and summer. For TMoP, the highest values were in the late spring and summer. The balance between TApP and TMoP was negative in winter and late spring, regardless of defoliation strategy. There was no difference in IE between the heights of the canopy during winter and late spring .. The number of tillers was higher in early spring and summer and lower in winter and late spring. The defoliation strategies have not changed phyllochron, leaf elongation rate. In spring and summer, there were increases in the rates of appearance, elongation and leaf senescence and, furthermore, decreased life span and phyllochron sheet. The plant height with increasing showed a lower rate of senescence and lower culm length in the spring. To increase the number of tillers marandu, it is advantageous to handle the plant with increasing height, ie, 15 cm in autumn and winter, the spring 30 cm and 45 cm in summer.The maintaining of B. brizantha cv. Marandu with fixed height of 30 cm or with variations between 15 and 45cm from the fall/winter to summer, does not influence the appearance and the growth of leaves per tiller, which indicates great flexibility on management defoliation in this forage plant.

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This report involves a formal scoping exercise to identify lessons from a wide range of previous and current project and initiative experiences at the national, regional seas, European and global levels. An inventory of 77 projects and initiatives that are relevant with regard to the key activities proposed by the Celtic Seas Partnership has been compiled, as well as a short-list of 23 of the most pertinent projects, lessons learnt and contact names. This report has identified a number of synergies and collaborative opportunities from other project and initiatives in the Celtic Seas and beyond. It provides a strong starting point to clarify to stakeholders the uniqueness of the Celtic Seas Partnership project and delivers a sound baseline for the other preparatory actions (A2 Stakeholder Mapping and A3 Baseline Analysis for Marine Strategy Framework Directive Implementation) and the implementation actions. Furthermore, this report helps to avoid duplication of effort during the life-span of the project by highlighting what information pertaining to the Celtic Seas MSFD sub-region already exists.

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Background.  Cytomegalovirus (CMV) is a common cause of birth defects and hearing loss in infants and opportunistic infections in the immunocompromised. Previous studies have found higher CMV seroprevalence rates among minorities and among persons with lower socioeconomic status. No studies have investigated the geographic distribution of CMV and its relationship to age, race, and poverty in the community. Methods.  We identified patients from 6 North Carolina counties who were tested in the Duke University Health System for CMV immunoglobulin G. We performed spatial statistical analyses to analyze the distributions of seropositive and seronegative individuals. Results.  Of 1884 subjects, 90% were either white or African American. Cytomegalovirus seropositivity was significantly more common among African Americans (73% vs 42%; odds ratio, 3.31; 95% confidence interval, 2.7-4.1), and this disparity persisted across the life span. We identified clusters of high and low CMV odds, both of which were largely explained by race. Clusters of high CMV odds were found in communities with high proportions of African Americans. Conclusions.  Cytomegalovirus seropositivity is geographically clustered, and its distribution is strongly determined by a community's racial composition. African American communities have high prevalence rates of CMV infection, and there may be a disparate burden of CMV-associated morbidity in these communities.

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Calcitic belemnite rostra are usually employed to perform paleoenvironmental studies based on geochemical data. However, several questions, such as their original porosity and microstructure, remain open, despite they are essential to make accurate interpretations based on geochemical analyses.This paper revisits and enlightens some of these questions. Petrographic data demonstrate that calcite crystals of the rostrum solidum of belemnites grow from spherulites that successively develop along the apical line, resulting in a “regular spherulithic prismatic” microstructure. Radially arranged calcite crystals emerge and diverge from the spherulites: towards the apex, crystals grow until a new spherulite is formed; towards the external walls of the rostrum, the crystals become progressively bigger and prismatic. Adjacent crystals slightly vary in their c-axis orientation, resulting in undulose extinction. Concentric growth layering develops at different scales and is superimposed and traversed by a radial pattern, which results in the micro-fibrous texture that is observed in the calcite crystals in the rostra.Petrographic data demonstrate that single calcite crystals in the rostra have a composite nature, which strongly suggests that the belemnite rostra were originally porous. Single crystals consistently comprise two distinct zones or sectors in optical continuity: 1) the inner zone is fluorescent, has relatively low optical relief under transmitted light (TL) microscopy, a dark-grey color under backscatter electron microscopy (BSEM), a commonly triangular shape, a “patchy” appearance and relatively high Mg and Na contents; 2) the outer sector is non-fluorescent, has relatively high optical relief under TL, a light-grey color under BSEM and low Mg and Na contents. The inner and fluorescent sectors are interpreted to have formed first as a product of biologically controlled mineralization during belemnite skeletal growth and the non-fluorescent outer sectors as overgrowths of the former, filling the intra- and inter-crystalline porosity. This question has important implications for making paleoenvironmental and/or paleoclimatic interpretations based on geochemical analyses of belemnite rostra.Finally, the petrographic features of composite calcite crystals in the rostra also suggest the non-classical crystallization of belemnite rostra, as previously suggested by other authors.

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Esta investigación se propone identificar las actitudes y competencias de los estudiantes adultos en relación con el uso de las TIC, con especial atención al uso de plataformas digitales de aprendizaje y redes sociales (Web 2.0). Asimismo, evalúa la incidencia de algunas variables sociodemográficas (género y edad) en el uso estas herramientas y en la autopercepción de los estudiantes sobre sus competencias digitales. Se ha realizado un estudio tipo encuesta con una muestra de 382 estudiantes que acceden a la Universidad de Sevilla a través de las vías establecidas para mayores de 25, de 40 y 45 años. Los resultados ponen de manifiesto una actitud generalmente positiva ante las TIC que puede calificarse como de pragmática, ya que estas herramientas se valoran positivamente en función de sus potenciales beneficios en los procesos de aprendizaje. Se constata a la vez que no han recibido formación específica en el uso de las TIC. El nivel de competencia que este alumnado percibe tener en el uso de estos recursos es medio-bajo. Además, el grupo de estudiantes mayores de 45 años se considera menos competente que los mayores de 25 y de 40 años. En consecuencia, se realizan algunas propuestas para mejorar la participación de los estudiantes maduros en la enseñanza universitaria.

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Zelfbeeldvorming is een levenslang proces en vindt plaats in de sociale context. Het zelfbeeld wordt gevormd op basis van zelfreflectie en sociale vergelijking en staat onder invloed van verschillende factoren. Het zelfbeeld is belangrijk voor de zelfregulatie en heeft invloed op het psychologisch welzijn. Door een asynchrone ontwikkeling wijkt de ontwikkeling van hoogbegaafden af van de gangbare patronen. Hoewel wordt gedacht dat hierdoor een adequate en positieve zelfbeeldvorming problematisch is, is hiernaar nauwelijks onderzoek gedaan. Dit kwalitatieve onderzoek is een eerste verkenning naar levensloopontwikkelingen in het zelfbeeld van personen die op volwassen leeftijd als hoogbegaafd zijn geïdentificeerd. De ontwikkelingen worden daarnaast in verband gebracht met het psychologisch welzijn. Acht personen, die op volwassen leeftijd als hoogbegaafd zijn geïdentificeerd, werden tijdens een diepte-interview uitgenodigd hun levensverhaal te vertellen. De levensverhalen werden geanalyseerd volgens een narratieve analysemethode. Levensloopontwikkelingen van hoogbegaafden in dit onderzoek kunnen het best kunnen worden begrepen vanuit het samenspel van de aan- en afwezigheid van belemmerende en bevorderende factoren, de kwaliteit van sociale interacties, individuele persoonskenmerken en de opeenstapeling van levenservaringen. In verschillende levensfasen staan zelfbeelden centraal die betrekking hebben op sociale rollen in de betreffende levensfase en de sociale eisen die daaruit voortvloeien. Variëteit hierin is afhankelijk is van de levensomstandigheden en de opeenstapeling van levenservaringen. Persoonlijke levenservaringen beïnvloeden de manier waarop men zichzelf begrijpt en naar zijn verleden, heden en toekomst kijkt. De betekenis die men geeft aan de eigen hoogbegaafdheid is afhankelijk van de mate van inadequatheid van het zelfbeeld vóór de identificatie en de persoonlijke opvatting over hoogbegaafdheid. Voor sommigen is de identificatie cruciaal voor de vorming van een adequaat zelfbeeld en een solide identiteitsvorming. Na de identificatie als hoogbegaafd staan zelfbeelden met betrekking tot persoonlijkheidskenmerken verbonden aan de hoogbegaafde identiteit, emotionaliteit en autonomie op de voorgrond. De mate waarin deze op de voorgrond treden is afhankelijk van de betekenis die men geeft aan de eigen hoogbegaafdheid. Bij alle deelnemers zijn zelfbeelden met betrekking tot de sociale interactie, zelfsturing, persoonlijke ontwikkeling en zelfontplooiing gedurende de gehele levensloop belangrijk. Onder invloed van veranderingen in het zelfbeeld gedurende de levensloop neemt het psychologisch welzijn toe op de domeinen zelfacceptatie, autonomie, grip op de omgeving en persoonlijke groei en voor een enkeling op het domein levensdoel. In verhouding tot deze welzijnsdomeinen neemt het welzijn op het domein positieve relaties met anderen matig toe. Dit heeft te maken met de onconventionaliteit van de deelnemers, waardoor men niet in de sociale context past en te maken heeft met (zelf)stigmatisering en een negatieve benadering door anderen.

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Thesis (Ph.D.)--University of Washington, 2016-08

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Understanding the evolution of the direct and indirect pathways of allorecognition following tissue transplantation is essential in the design of tolerance-promoting protocols. On the basis that donor bone marrow-derived antigen presenting cells are eliminated within days of transplantation, it has been argued that the indirect response represents the major threat to long term transplant survival, and is consequently the key target for regulation. However, the detection of MHC transfer between cells, and particularly the capture of MHC:peptide complexes by dendritic cells, led us to propose a third, semi-direct, pathway of MHC allorecognition. Persistence of this pathway would lead to sustained activation of direct pathway T cells, arguably persisting for the life of the transplant. In this study, we focused on the contribution of acquired MHC class I, on recipient DCs, during the life span of a skin graft. We observed that MHC class I acquisition by recipient DCs occurs for at least one month following transplantation and may be the main source of alloantigen that drives CD8+ cytotoxic T cell responses. In addition, acquired MHC class I-peptide complexes stimulate T cell responses in vivo further emphasizing the need to regulate both pathways to induce indefinite survival of the graft.

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The hermit crab Paguras brevidactylus (Crustacea: Anomura: Paguridea) from the infralittoral area of Anchieta Island, Ubatuba, was characterized by population Structure (size, sex ratio, reproduction and recruitment) and growth. Animals were collected monthly during 1999 by SCUBA diving. A total of 1525 individuals was collected (633 males and 892 females), 695 of them were ovigerous females. Overall sex ratio was 0.7:1 in favour of females. The crabs showed a unimodal distribution with males significantly larger than females. Ovigerous females were collected during all months and in high percentages from 1.0 mm of shield length, demonstrating intense and Continuous reproduction. The longevity was approximately 24 months for males and 18 for females, which showed larger growth rate and reached sexual maturity earlier (two months) than males. The low number of males in this Population may be due to the longer life span. Moreover, the sexual dimorphism favours males during the intra- and interspecific fights by shell, food, reproduction and territory. Females demonstrated a short life cycle and intense reproduction.

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Dissertação de Mestrado Integrado em Medicina Veterinária