895 resultados para System failures (Engineering) -- Location
Resumo:
Among numerous magnetic resonance imaging (MRI) techniques, perfusion MRI provides insight into the passage of blood through the brain's vascular network non-invasively. Studying disease models and transgenic mice would intrinsically help understanding the underlying brain functions, cerebrovascular disease and brain disorders. This study evaluates the feasibility of performing continuous arterial spin labeling (CASL) on all cranial arteries for mapping murine cerebral blood flow at 9.4 T. We showed that with an active-detuned two-coil system, a labeling efficiency of 0.82 ± 0.03 was achieved with minimal magnetization transfer residuals in brain. The resulting cerebral blood flow of healthy mouse was 99 ± 26 mL/100g/min, in excellent agreement with other techniques. In conclusion, high magnetic fields deliver high sensitivity and allowing not only CASL but also other MR techniques, i.e. (1)H MRS and diffusion MRI etc, in studying murine brains.
Resumo:
Analysis of variance is commonly used in morphometry in order to ascertain differences in parameters between several populations. Failure to detect significant differences between populations (type II error) may be due to suboptimal sampling and lead to erroneous conclusions; the concept of statistical power allows one to avoid such failures by means of an adequate sampling. Several examples are given in the morphometry of the nervous system, showing the use of the power of a hierarchical analysis of variance test for the choice of appropriate sample and subsample sizes. In the first case chosen, neuronal densities in the human visual cortex, we find the number of observations to be of little effect. For dendritic spine densities in the visual cortex of mice and humans, the effect is somewhat larger. A substantial effect is shown in our last example, dendritic segmental lengths in monkey lateral geniculate nucleus. It is in the nature of the hierarchical model that sample size is always more important than subsample size. The relative weight to be attributed to subsample size thus depends on the relative magnitude of the between observations variance compared to the between individuals variance.
Resumo:
This manual captures the experience of practitioners in the Iowa Department of Transportation’s (Iowa DOT’s) Office of Location and Environment (OLE). It also documents the need for coordinated project development efforts during the highway project planning, or location study phase and engineering design. The location study phase establishes: * The definition of, and need for, the highway improvement project * The range of alternatives and many key attributes of the project’s design * The recommended alternative, its impacts, and the agreed-to conditions for project approval The location study process involves developing engineering alternatives, collecting engineering and environmental data, and completing design refinements to accomplish functional designs. The items above also embody the basic content required for projects compliant with the National Environmental Policy Act (NEPA) of 19691, which directs federal agencies to use a systematic, interdisciplinary approach during the planning process whenever proposed actions (or “projects”) have the potential for environmental impacts. In doing so, NEPA requires coordination with stakeholders, review, comment, and public disclosure. Are location studies and environmental studies more about the process or the documents? If properly conducted, they concern both—unbiased and reasonable processes with quality and timely documents. In essence, every project is a story that needs to be told. Engineering and environmental regulations and guidance, as documented in this manual, will help project staff and managers become better storytellers.
Resumo:
The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing to improve the interstate system around Council Bluffs with improvements extending across the Missouri River on I-80 to east of the I-480 interchange in Omaha, Nebraska, see Figure 1-1. The study considers long-term, broad-based transportation improvements along I-80, I-29, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs
Resumo:
The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 (I-80) to east of the Interstate 480 (I-480) interchange in Omaha, Nebraska (see Figure 1-1). The study considers long-term, broad-based transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs.
Resumo:
Because an individual's investment into the immune system may modify its dispersal rate, immune function may evolve rapidly in an invader. We collected cane toads (Rhinella marina) from sites spanning their 75-year invasion history in Australia, bred them, and raised their progeny in standard conditions. Evolved shifts in immune function should manifest as differences in immune responses among the progeny of parents collected in different locations. Parental location did not affect the offspring's cell-mediated immune response or stress response, but blood from the offspring of invasion-front toads had more neutrophils, and was more effective at phagocytosis and killing bacteria. These latter measures of immune function are negatively correlated with rate of dispersal in free-ranging toads. Our results suggest that the invasion of tropical Australia by cane toads has resulted in rapid genetically based compensatory shifts in the aspects of immune responses that are most compromised by the rigours of long-distance dispersal.
Resumo:
The protective effect of cations, especially Ca and Mg, against aluminum (Al) rhizotoxicity has been extensively investigated in the last decades. The mechanisms by which the process occurs are however only beginning to be elucidated. Six experiments were carried out here to characterize the protective effect of Mg application in relation to timing, location and crop specificity: Experiment 1 - Protective effect of Mg compared to Ca; Experiment 2 - Protective effect of Mg on distinct root classes of 15 soybean genotypes; Experiment 3 - Effect of timing of Mg supply on the response of soybean cvs. to Al; Experiment 4 - Investigating whether the Mg protective effect is apoplastic or simplastic using a split-root system; Experiment 5 - Protective effect of Mg supplied in solution or foliar spraying, and Experiment 6 - Protective effect of Mg on Al rhizotoxicity in other crops. It was found that the addition of 50 mmol L-1 Mg to solutions containing toxic Al increased Al tolerance in 15 soybean cultivars. This caused soybean cultivars known as Al-sensitive to behave as if they were tolerant. The protective action of Mg seems to require constant Mg supply in the external medium. Supplying Mg up to 6 h after root exposition to Al was sufficient to maintain normal soybean root growth, but root growth was not recovered by Mg addition 12 h after Al treatments. Mg application to half of the root system not exposed to Al was not sufficient to prevent Al toxicity on the other half exposed to Al without Mg in rooting medium, indicating the existence of an external protection mechanism of Mg. Foliar spraying with Mg also failed to decrease Al toxicity, indicating a possible apoplastic role of Mg. The protective effect of Mg appeared to be soybean-specific since Mg supply did not substantially improve root elongation in sorghum, wheat, corn, cotton, rice, or snap bean when grown in the presence of toxic Al concentrations.
Resumo:
A t the request of the Iowa State Highway Commission, the Engineering Research Institute observed the traffic operations at the Interstate 29 (1-29) and Interstate 80 (1-80) interchange in the southwest part of Council Bluffs. The general location of the site is shown in Figure 1. Before limiting the analysis to the diverging area the project staff drove the entire Council Bluffs freeway system and consulted with M r . Philip Hassenstab (Iowa State Highway Commission, District 4, Resident Maintenance Engineer at Council Bluffs). The final study scope was delineated as encompassing only the operational characteristics of the diverge area where 1-29 South and 1-80 East divide and the ramp to merge area where 1-80 West joins 1-29 North (both areas being contained within the aforementioned interchange). Supplementing the traffic operations scope, was an effort to delineate and document the applicability of video-tape techniques to traffic engineering studies and analyses. Documentation was primarily in the form of a demonstration video-tape.
Resumo:
A mobile ad hoc network (MANET) is a decentralized and infrastructure-less network. This thesis aims to provide support at the system-level for developers of applications or protocols in such networks. To do this, we propose contributions in both the algorithmic realm and in the practical realm. In the algorithmic realm, we contribute to the field by proposing different context-aware broadcast and multicast algorithms in MANETs, namely six-shot broadcast, six-shot multicast, PLAN-B and ageneric algorithmic approach to optimize the power consumption of existing algorithms. For each algorithm we propose, we compare it to existing algorithms that are either probabilistic or context-aware, and then we evaluate their performance based on simulations. We demonstrate that in some cases, context-aware information, such as location or signal-strength, can improve the effciency. In the practical realm, we propose a testbed framework, namely ManetLab, to implement and to deploy MANET-specific protocols, and to evaluate their performance. This testbed framework aims to increase the accuracy of performance evaluation compared to simulations, while keeping the ease of use offered by the simulators to reproduce a performance evaluation. By evaluating the performance of different probabilistic algorithms with ManetLab, we observe that both simulations and testbeds should be used in a complementary way. In addition to the above original contributions, we also provide two surveys about system-level support for ad hoc communications in order to establish a state of the art. The first is about existing broadcast algorithms and the second is about existing middleware solutions and the way they deal with privacy and especially with location privacy. - Un réseau mobile ad hoc (MANET) est un réseau avec une architecture décentralisée et sans infrastructure. Cette thèse vise à fournir un support adéquat, au niveau système, aux développeurs d'applications ou de protocoles dans de tels réseaux. Dans ce but, nous proposons des contributions à la fois dans le domaine de l'algorithmique et dans celui de la pratique. Nous contribuons au domaine algorithmique en proposant différents algorithmes de diffusion dans les MANETs, algorithmes qui sont sensibles au contexte, à savoir six-shot broadcast,six-shot multicast, PLAN-B ainsi qu'une approche générique permettant d'optimiser la consommation d'énergie de ces algorithmes. Pour chaque algorithme que nous proposons, nous le comparons à des algorithmes existants qui sont soit probabilistes, soit sensibles au contexte, puis nous évaluons leurs performances sur la base de simulations. Nous montrons que, dans certains cas, des informations liées au contexte, telles que la localisation ou l'intensité du signal, peuvent améliorer l'efficience de ces algorithmes. Sur le plan pratique, nous proposons une plateforme logicielle pour la création de bancs d'essai, intitulé ManetLab, permettant d'implémenter, et de déployer des protocoles spécifiques aux MANETs, de sorte à évaluer leur performance. Cet outil logiciel vise à accroître la précision desévaluations de performance comparativement à celles fournies par des simulations, tout en conservant la facilité d'utilisation offerte par les simulateurs pour reproduire uneévaluation de performance. En évaluant les performances de différents algorithmes probabilistes avec ManetLab, nous observons que simulateurs et bancs d'essai doivent être utilisés de manière complémentaire. En plus de ces contributions principales, nous fournissons également deux états de l'art au sujet du support nécessaire pour les communications ad hoc. Le premier porte sur les algorithmes de diffusion existants et le second sur les solutions de type middleware existantes et la façon dont elles traitent de la confidentialité, en particulier celle de la localisation.
Resumo:
The role of rural demand-responsive transit is changing, and with that change is coming an increasing need for technology. As long as rural transit was limited to a type of social service transportation for a specific set of clients who primarily traveled in groups to common meal sites, work centers for the disabled, or clinics in larger communities, a preset calendar augmented by notes on a yellow legal pad was sufficient to develop schedules. Any individual trips were arranged at least 24 to 48 hours ahead of time and were carefully scheduled the night before in half-hour or twenty-minute windows by a dispatcher who knew every lane in the service area. Since it took hours to build the schedule, any last-minute changes could wreak havoc with the plans and raise the stress level in the dispatch office. Nevertheless, given these parameters, a manual scheduling system worked for a small demand-responsive operation.
Resumo:
New Global Positioning System (GPS) receivers allow now to measure a location on earth at high frequency (5Hz) with a centimetric precision using phase differential positioning method. We studied whether such technique was accurate enough to retrieve basic parameters of human locomotion. Eight subjects walked on an athletics track at four different imposed step frequencies (70-130steps/min) plus a run at free pace. Differential carrier phase localization between a fixed base station and the mobile antenna mounted on the walking person was calculated. In parallel, a triaxial accelerometer, attached to the low back, recorded body accelerations. The different parameters were averaged for 150 consecutive steps of each run for each subject (total of 6000 steps analyzed). We observed a perfect correlation between average step duration measured by accelerometer and by GPS (r=0.9998, N=40). Two important parameters for the calculation of the external work of walking were also analyzed, namely the vertical lift of the trunk and the velocity variation per step. For an average walking speed of 4.0km/h, average vertical lift and velocity variation were, respectively, 4.8cm and 0.60km/h. The average intra-individual step-to-step variability at a constant speed, which includes GPS errors and the biological gait style variation, were found to be 24. 5% (coefficient of variation) for vertical lift and 44.5% for velocity variation. It is concluded that GPS technique can provide useful biomechanical parameters for the analysis of an unlimited number of strides in an unconstrained free-living environment.
Resumo:
The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing to improve the interstate system around Council Bluffs with improvements extending across the Missouri River on I-80 to east of the I-480 interchange in Omaha, Nebraska, see Figure 1-1. The study considers long-term, broad-based transportation improvements along I-80, I-29, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs. In 2001, Iowa DOT and FHWA initiated the Council Bluffs Interstate System (CBIS) Improvements Project. The agencies concluded that the environmental study process would be conducted in two stages; that is, a tiered approach would be applied. The project is being conducted pursuant to the National Environmental Policy Act (NEPA) regulations issued by the Council on Environmental Quality (CEQ), 40 Code of Federal Regulations (CFR) Part 1502.20, and FHWA 23 CFR Part 771.111, that permit tiering for large, complex NEPA studies. Tier 1 is an examination of the overall interstate system improvement needs, including a clear explanation of the area’s transportation needs, a study of alternatives to satisfy them, and broad consideration of potential environmental and social impacts. The Tier 1 evaluation is at a sufficient level of engineering and environmental detail to assist decision makers in selecting a preferred transportation strategy. Tier 1 includes preparation of a draft and final Environmental Impact Statement (EIS) that would disclose the potential environmental and social effects (evaluated at a planning level that considers a variety of conceptual designs) of the proposed improvements. The final EIS will conclude with a Record of Decision (ROD) that states the preferred plan for improvements to be implemented. Essentially, the Tier 1 document will establish the planning framework for the needed improvements. Because the scope of the overall system improvements is large, the interstate improvements would be implemented as a series of individual projects that fit into the overall planning framework. The Tier 1 Area of Potential Impact, which is discussed in detail in Section 4 is an alternative that considers a combination of the most reasonable concepts that have been developed, buffered by approximately 100 or more feet to ensure that any Tier 2 design modifications would remain inside the outer boundary.
Resumo:
The Federal Highway Administration (FHWA) approves the selection of the Reconstruction of All or Part of the Interstate (Construction Alternative) as the Preferred Alternative to provide improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 to east of the Interstate 480 interchange in Omaha, Nebraska. The study considered long-term, broad-based transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. FHWA also approves the decisions to provide full access between West Broadway and I-29, design the I-80/I-29 overlap section as a dual-divided freeway, and locating the new I-80 Missouri River Bridge north of the existing bridge. Improvements to the interstate system, once implemented, would bring the segments of I-80 and I-29 (see Figure 1) up to current engineering standards and accommodate future traffic needs. This Record of Decision (ROD) concludes Tier 1 of the Council Bluffs Interstate System (CBIS) Improvements Project. Tier 1 included an examination of the area’s transportation needs, a study of alternatives to satisfy them, and broad consideration of potential environmental and social impacts. The Tier 1 evaluation consisted of a sufficient level of engineering and environmental detail to assist decision makers in selecting a preferred transportation strategy. During Tier 1 a Draft EIS (FHWA-IA- EIS-04-01D) was developed which was approved by FHWA, Iowa DOT, and Nebraska Department of Roads (NDOR) in November 2004 with comments accepted through March 15, 2005. The Draft EIS summarized the alternatives that were considered to address the transportation needs around Council Bluffs; identified reconstruction of all or part of the interstate, the “Construction Alternative,” as the Preferred Alternative; identified three system-level decisions that needed to be made at the Tier 1 level; and invited comment on the issues. The Final EIS (FHWA-IA- EIS-04-01F) further documented the Construction Alternative as the Preferred Alternative and identified the recommended decisions for the three system level decisions that needed to be made in Tier 1. This ROD defines the Selected Alternative determined in the Tier 1 studies.
Resumo:
The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 (I-80) to east of the Interstate 480 (I-480) interchange in Omaha, Nebraska (see Figure 1-1). The study considers long-term, broad-base transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs.
Resumo:
The Iowa Department of Transportation (Iowa DOT), Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA) are proposing improvements to the interstate system in the Omaha/Council Bluffs metropolitan area, extending across the Missouri River on Interstate 80 (I-80) to east of the Interstate 480 (I-480) interchange in Omaha, Nebraska (see Figure 1-1). The study considers long-term, broad-base transportation improvements along Interstate I-29 (I-29), I-80, and I-480, including approximately 18 mainline miles of interstate and 14 interchanges (3 system1, 11 service), that would add capacity and correct functional issues along the mainline and interchanges and upgrade the I-80 Missouri River Crossing. These improvements, once implemented, would bring the segments of I-80 and I-29 up to current engineering standards and modernize the roadway to accommodate future traffic needs.