959 resultados para Packet Inter-arrival Time


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Mode of access: Internet.

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Reprinted from the Edinburgh review.

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Since the arrival of the first African slaves to Cuba in 1524, the issue of race has had a long-lived presence in the Cuban national discourse. However, despite Cuba’s colonial history, it has often been maintained by some historians that race relations in Cuba were congenial with racism and racial discrimination never existing as deep or widespread in Cuba as in the United States (Cannon, 1983, p. 113). In fact, it has been argued that institutionalized racism was introduced into Cuban society with the first U.S. occupation, during 1898–1902 (Cannon, 1983, p. 113). This study of Cuba investigates the influence of the United States on the development of race relations and racial perceptions in post-independent Cuba, specifically from 1898-1902. These years comprise the time period immediately following the final fight for Cuban Independence, culminating with the Cuban-Spanish-American War and the first U.S. occupation of Cuba. By this time, the Cuban population comprised Africans as well as descendants of Africans, White Spanish people, indigenous Cubans, and offspring of the intermixing of the groups. This research studies whether the United States’ own race relations and racial perceptions influenced the initial conflicting race relations and racial perceptions in early and post-U.S. occupation Cuba. This study uses a collective interpretative framework that incorporates a national level of analysis with a race relations and racial perceptions focus. This framework reaches beyond the traditionally utilized perspectives when interpreting the impact of the United States during and following its intervention in Cuba. Attention is given to the role of the existing social, political climate within the United States as a driving influence of the United States’ involvement with Cuba. This study reveals that emphasis on the role of the United States as critical to the development of Cuba’s race relations and racial perceptions is credible given the extensive involvement of the U.S. in the building of the early Cuban Republic and U.S. structures serving as models for reconstruction. U.S. government formation in Cuba aligned with a governing system reflecting the existing governing codes of the U.S. during that time period.

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The ability to use Software Defined Radio (SDR) in the civilian mobile applications will make it possible for the next generation of mobile devices to handle multi-standard personal wireless devices and ubiquitous wireless devices. The original military standard created many beneficial characteristics for SDR, but resulted in a number of disadvantages as well. Many challenges in commercializing SDR are still the subject of interest in the software radio research community. Four main issues that have been already addressed are performance, size, weight, and power. ^ This investigation presents an in-depth study of SDR inter-components communications in terms of total link delay related to the number of components and packet sizes in systems based on Software Communication Architecture (SCA). The study is based on the investigation of the controlled environment platform. Results suggest that the total link delay does not linearly increase with the number of components and the packet sizes. The closed form expression of the delay was modeled using a logistic function in terms of the number of components and packet sizes. The model performed well when the number of components was large. ^ Based upon the mobility applications, energy consumption has become one of the most crucial limitations. SDR will not only provide flexibility of multi-protocol support, but this desirable feature will also bring a choice of mobile protocols. Having such a variety of choices available creates a problem in the selection of the most appropriate protocol to transmit. An investigation in a real-time algorithm to optimize energy efficiency was also performed. Communication energy models were used including switching estimation to develop a waveform selection algorithm. Simulations were performed to validate the concept.^

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The ability to use Software Defined Radio (SDR) in the civilian mobile applications will make it possible for the next generation of mobile devices to handle multi-standard personal wireless devices and ubiquitous wireless devices. The original military standard created many beneficial characteristics for SDR, but resulted in a number of disadvantages as well. Many challenges in commercializing SDR are still the subject of interest in the software radio research community. Four main issues that have been already addressed are performance, size, weight, and power. This investigation presents an in-depth study of SDR inter-components communications in terms of total link delay related to the number of components and packet sizes in systems based on Software Communication Architecture (SCA). The study is based on the investigation of the controlled environment platform. Results suggest that the total link delay does not linearly increase with the number of components and the packet sizes. The closed form expression of the delay was modeled using a logistic function in terms of the number of components and packet sizes. The model performed well when the number of components was large. Based upon the mobility applications, energy consumption has become one of the most crucial limitations. SDR will not only provide flexibility of multi-protocol support, but this desirable feature will also bring a choice of mobile protocols. Having such a variety of choices available creates a problem in the selection of the most appropriate protocol to transmit. An investigation in a real-time algorithm to optimize energy efficiency was also performed. Communication energy models were used including switching estimation to develop a waveform selection algorithm. Simulations were performed to validate the concept.

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Advances in the diagnosis of Mycobacterium bovis infection in wildlife hosts may benefit the development of sustainable approaches to the management of bovine tuberculosis in cattle. In the present study, three laboratories from two different countries participated in a validation trial to evaluate the reliability and reproducibility of a real time PCR assay in the detection and quantification of M. bovis from environmental samples. The sample panels consisted of negative badger faeces spiked with a dilution series of M. bovis BCG Pasteur and of field samples of faeces from badgers of unknown infection status taken from badger latrines in areas with high and low incidence of bovine TB (bTB) in cattle. Samples were tested with a previously optimised methodology. The experimental design involved rigorous testing which highlighted a number of potential pitfalls in the analysis of environmental samples using real time PCR. Despite minor variation between operators and laboratories, the validation study demonstrated good concordance between the three laboratories: on the spiked panels, the test showed high levels of agreement in terms of positive/negative detection, with high specificity (100%) and high sensitivity (97%) at levels of 10(5) cells g(-1) and above. Quantitative analysis of the data revealed low variability in recovery of BCG cells between laboratories and operators. On the field samples, the test showed high reproducibility both in terms of positive/negative detection and in the number of cells detected, despite low numbers of samples identified as positive by any laboratory. Use of a parallel PCR inhibition control assay revealed negligible PCR-interfering chemicals co-extracted with the DNA. This is the first example of a multi-laboratory validation of a real time PCR assay for the detection of mycobacteria in environmental samples. Field studies are now required to determine how best to apply the assay for population-level bTB surveillance in wildlife.

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OBJETIVO: este estudo teve como objetivo avaliar a influência da largura do septo inter-radicular no local de inserção de mini-implantes autoperfurantes sobre o grau de estabilidade desses dispositivos de ancoragem. MÉTODOS: a amostra consistiu de 40 mini-implantes inseridos entre as raízes do primeiro molar e segundo pré-molar superiores de 21 pacientes, com o intuito de fornecer ancoragem para retração anterior. A largura do septo no local de inserção (LSI) foi mensurada nas radiografias pós-cirúrgicas e, sob esse aspecto, os mini-implantes foram divididos em dois grupos: grupo 1 (áreas críticas, LSI<3mm) e grupo 2 (áreas não críticas, LSI>3mm). A estabilidade dos mini-implantes foi avaliada mensalmente pela quantificação do grau de mobilidade e a partir dessa variável foi calculada a proporção de sucesso. Avaliou-se também: a quantidade de placa, altura de inserção, grau de sensibilidade e período de observação. RESULTADOS: os resultados obtidos demonstraram que não houve diferença estatisticamente significativa para o grau de mobilidade e proporção de sucesso entre os mini-implantes inseridos em septos de largura mesiodistal crítica e não crítica. A proporção de sucesso total encontrada foi de 90% e nenhuma variável demonstrou estar relacionada ao insucesso dos mini-implantes. No entanto, observou-se maior sensibilidade nos pacientes cujos mini-implantes apresentavam mobilidade, e que a falha desses dispositivos de ancoragem ocorria logo após sua inserção. CONCLUSÃO: a largura do septo inter-radicular no local de inserção não interferiu na estabilidade dos mini-implantes autoperfurantes avaliados neste estudo.

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Due to the several kinds of services that use the Internet and data networks infra-structures, the present networks are characterized by the diversity of types of traffic that have statistical properties as complex temporal correlation and non-gaussian distribution. The networks complex temporal correlation may be characterized by the Short Range Dependence (SRD) and the Long Range Dependence - (LRD). Models as the fGN (Fractional Gaussian Noise) may capture the LRD but not the SRD. This work presents two methods for traffic generation that synthesize approximate realizations of the self-similar fGN with SRD random process. The first one employs the IDWT (Inverse Discrete Wavelet Transform) and the second the IDWPT (Inverse Discrete Wavelet Packet Transform). It has been developed the variance map concept that allows to associate the LRD and SRD behaviors directly to the wavelet transform coefficients. The developed methods are extremely flexible and allow the generation of Gaussian time series with complex statistical behaviors.

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Since their discovery 150 years ago, Neanderthals have been considered incapable of behavioural change and innovation. Traditional synchronic approaches to the study of Neanderthal behaviour have perpetuated this view and shaped our understanding of their lifeways and eventual extinction. In this thesis I implement an innovative diachronic approach to the analysis of Neanderthal faunal extraction, technology and symbolic behaviour as contained in the archaeological record of the critical period between 80,000 and 30,000 years BP. The thesis demonstrates patterns of change in Neanderthal behaviour which are at odds with traditional perspectives and which are consistent with an interpretation of increasing behavioural complexity over time, an idea that has been suggested but never thoroughly explored in Neanderthal archaeology. Demonstrating an increase in behavioural complexity in Neanderthals provides much needed new data with which to fuel the debate over the behavioural capacities of Neanderthals and the first appearance of Modern Human Behaviour in Europe. It supports the notion that Neanderthal populations were active agents of behavioural innovation prior to the arrival of Anatomically Modern Humans in Europe and, ultimately, that they produced an early Upper Palaeolithic cultural assemblage (the Châtelperronian) independent of modern humans. Overall, this thesis provides an initial step towards the development of a quantitative approach to measuring behavioural complexity which provides fresh insights into the cognitive and behavioural capabilities of Neanderthals.

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In his study of the 'time of arrival' problem in the nonrelativistic quantum mechanics of a single particle, Allcock [1] noted that the direction of the probability flux vector is not necessarily the same as that of the mean momentum of a wave packet, even when the packet is composed entirely of plane waves with a common direction of momentum. Packets can be constructed, for example for a particle moving under a constant force, in which probability flows for a finite time in the opposite direction to the momentum. A similar phenomenon occurs for the Dirac electron. The maximum amount of probabilitiy backflow which can occur over a given time interval can be calculated in each case.

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It is recognized that vascular dispersion in the liver is a determinant of high first-pass extraction of solutes by that organ. Such dispersion is also required for translation of in-vitro microsomal activity into in-vivo predictions of hepatic extraction for any solute. We therefore investigated the relative dispersion of albumin transit times (CV2) in the livers of adult and weanling rats and in elasmobranch livers. The mean and normalized variance of the hepatic transit time distribution of albumin was estimated using parametric non-linear regression (with a correction for catheter influence) after an impulse (bolus) input of labelled albumin into a single-pass liver perfusion. The mean +/- s.e. of CV2 for albumin determined in each of the liver groups were 0.85 +/- 0.20 (n = 12), 1.48 +/- 0.33 (n = 7) and 0.90 +/- 0.18 (n = 4) for the livers of adult and weanling rats and elasmobranch livers, respectively. These CV2 are comparable with that reported previously for the dog and suggest that the CV2 Of the liver is of a similar order of magnitude irrespective of the age and morphological development of the species. It might, therefore, be justified, in the absence of other information, to predict the hepatic clearances and availabilities of highly extracted solutes by scaling within and between species livers using hepatic elimination models such as the dispersion model with a CV2 of approximately unity.

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Engineering This investigation examined the rheological (viscosity and yield stress) and material property (density) characteristics of the thickened meal-time and videofluorscopy fluids provided by 10 major metropolitan hospitals. Differences in the thickness of thickened fluids were considered as a source of variability and potential hazard for inter-hospital transfers of dysphagic patients. The results indicated considerable differences in the viscosity, density, and yield stress of both meal-time and videofluoroscopy fluids. In theory, the results suggest that dysphagic patients transferred between hospitals could be placed on inappropriate levels of fluid thickness because of inherent differences in the rheology and material property characteristics of the fluids provided by different hospitals. Slowed improvement or medical complications are potential worst-case scenarios for dysphagic patients if the difference between the thick fluids offered by 2 hospitals are extreme. The investigation outlines the most appropriate way to assess the rheological and material property characteristics of thickened fluids. In addition, it suggests a plan of quality improvement to reduce the variability of the thickness of fluids offered at different hospitals.

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High performance video codec is mandatory for multimedia applications such as video-on-demand and video conferencing. Recent research has proposed numerous video coding techniques to meet the requirement in bandwidth, delay, loss and Quality-of-Service (QoS). In this paper, we present our investigations on inter-subband self-similarity within the wavelet-decomposed video frames using neural networks, and study the performance of applying the spatial network model to all video frames over time. The goal of our proposed method is to restore the highest perceptual quality for video transmitted over a highly congested network. Our contributions in this paper are: (1) A new coding model with neural network based, inter-subband redundancy (ISR) prediction for video coding using wavelet (2) The performance of 1D and 2D ISR prediction, including multiple levels of wavelet decompositions. Our result shows a short-term quality enhancement may be obtained using both 1D and 2D ISR prediction.