970 resultados para frequency analysis problem


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US Geological Survey (USGS) based elevation data are the most commonly used data source for highway hydraulic analysis; however, due to the vertical accuracy of USGS-based elevation data, USGS data may be too “coarse” to adequately describe surface profiles of watershed areas or drainage patterns. Additionally hydraulic design requires delineation of much smaller drainage areas (watersheds) than other hydrologic applications, such as environmental, ecological, and water resource management. This research study investigated whether higher resolution LIDAR based surface models would provide better delineation of watersheds and drainage patterns as compared to surface models created from standard USGS-based elevation data. Differences in runoff values were the metric used to compare the data sets. The two data sets were compared for a pilot study area along the Iowa 1 corridor between Iowa City and Mount Vernon. Given the limited breadth of the analysis corridor, areas of particular emphasis were the location of drainage area boundaries and flow patterns parallel to and intersecting the road cross section. Traditional highway hydrology does not appear to be significantly impacted, or benefited, by the increased terrain detail that LIDAR provided for the study area. In fact, hydrologic outputs, such as streams and watersheds, may be too sensitive to the increased horizontal resolution and/or errors in the data set. However, a true comparison of LIDAR and USGS-based data sets of equal size and encompassing entire drainage areas could not be performed in this study. Differences may also result in areas with much steeper slopes or significant changes in terrain. LIDAR may provide possibly valuable detail in areas of modified terrain, such as roads. Better representations of channel and terrain detail in the vicinity of the roadway may be useful in modeling problem drainage areas and evaluating structural surety during and after significant storm events. Furthermore, LIDAR may be used to verify the intended/expected drainage patterns at newly constructed highways. LIDAR will likely provide the greatest benefit for highway projects in flood plains and areas with relatively flat terrain where slight changes in terrain may have a significant impact on drainage patterns.

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Iowa features an extensive surface transportation system, with more than 110,000 miles of roadway, most of which is under the jurisdiction of local agencies. Given that Iowa is a lower-population state, most of this mileage is located in rural areas that exhibit low traffic volumes of less than 400 vehicles per day. However, these low-volume rural roads also account for about half of all recorded traffic crashes in Iowa, including a high percentage of fatal and major injury crashes. This study was undertaken to examine these crashes, identify major contributing causes, and develop low-cost strategies for reducing the incidence of these crashes. Iowa’s extensive crash and roadway system databases were utilized to obtain needed data. Using descriptive statistics, a test of proportions, and crash modeling, various classes of rural secondary roads were compared to similar state of Iowa controlled roads in crash frequency, severity, density, and rate for numerous selected factors that could contribute to crashes. The results of this study allowed the drawing of conclusions as to common contributing factors for crashes on low-volume rural roads, both paved and unpaved. Due to identified higher crash statistics, particular interest was drawn to unpaved rural roads with traffic volumes greater than 100 vehicles per day. Recommendations for addressing these crashes with low-cost mitigation are also included. Because of the isolated nature of traffic crashes on low-volume roads, a systemic or mass action approach to safety mitigation was recommended for an identified subset of the entire system. In addition, future development of a reliable crash prediction model is described.

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The Center for Transportation Research and Education (CTRE) issued a report in July 2003, based on a sample study of the application of remote sensed image land use change detection to the methodology of traffic monitoring in Blackhawk County, Iowa. In summary, the results indicated a strong correlation and a statistically significant regression coefficient between the identification of built-up land use change areas from remote sensed data and corresponding changes in traffic patterns, expressed as vehicle miles traveled (VMT). Based on these results, the Iowa Department of Transportation (Iowa DOT) requested that CTRE expand the study area to five counties in the southwest quadrant of the state. These counties are scheduled for traffic counts in 2004, and the Iowa DOT desired the data to 1) evaluate the current methodology used to place the devices; 2) potentially influence the placement of traffic counting devices in areas of high built-up land use change; and 3) determine if opportunities exist to reduce the frequency and/or density of monitoring activity in lower trafficked rural areas of the state. This project is focused on the practical application of built-up land use change data for placement of traffic count data recording devices in five southwest Iowa counties.

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The authors pooled data from 15 case-control studies of head and neck cancer (9,107 cases, 14,219 controls) to investigate the independent associations with consumption of beer, wine, and liquor. In particular, they calculated associations with different measures of beverage consumption separately for subjects who drank beer only (858 cases, 986 controls), for liquor-only drinkers (499 cases, 527 controls), and for wine-only drinkers (1,021 cases, 2,460 controls), with alcohol never drinkers (1,124 cases, 3,487 controls) used as a common reference group. The authors observed similar associations with ethanol-standardized consumption frequency for beer-only drinkers (odds ratios (ORs) = 1.6, 1.9, 2.2, and 5.4 for < or =5, 6-15, 16-30, and >30 drinks per week, respectively; P(trend) < 0.0001) and liquor-only drinkers (ORs = 1.6, 1.5, 2.3, and 3.6; P < 0.0001). Among wine-only drinkers, the odds ratios for moderate levels of consumption frequency approached the null, whereas those for higher consumption levels were comparable to those of drinkers of other beverage types (ORs = 1.1, 1.2, 1.9, and 6.3; P < 0.0001). Study findings suggest that the relative risks of head and neck cancer for beer and liquor are comparable. The authors observed weaker associations with moderate wine consumption, although they cannot rule out confounding from diet and other lifestyle factors as an explanation for this finding. Given the presence of heterogeneity in study-specific results, their findings should be interpreted with caution.

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Background The association between dietary patterns and head and neck cancer has rarely been addressed. Patients and methods We used individual-level pooled data from five case-control studies (2452 cases and 5013 controls) participating in the International Head and Neck Cancer Epidemiology consortium. A posteriori dietary patterns were identified through a principal component factor analysis carried out on 24 nutrients derived from study-specific food-frequency questionnaires. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated using unconditional logistic regression models on quintiles of factor scores. Results We identified three major dietary patterns named 'animal products and cereals', 'antioxidant vitamins and fiber', and 'fats'. The 'antioxidant vitamins and fiber' pattern was inversely related to oral and pharyngeal cancer (OR = 0.57, 95% CI 0.43-0.76 for the highest versus the lowest score quintile). The 'animal products and cereals' pattern was positively associated with laryngeal cancer (OR = 1.54, 95% CI 1.12-2.11), whereas the 'fats' pattern was inversely associated with oral and pharyngeal cancer (OR = 0.78, 95% CI 0.63-0.97) and positively associated with laryngeal cancer (OR = 1.69, 95% CI 1.22-2.34). Conclusions These findings suggest that diets rich in animal products, cereals, and fats are positively related to laryngeal cancer, and those rich in fruit and vegetables inversely related to oral and pharyngeal cancer.

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ABSTRACT Adult neuronal plasticity is a term that corresponds to a set of biological mechanisms allowing a neuronal circuit to respond and adapt to modifications of the received inputs. Mystacial whiskers of the mouse are the starting point of a major sensory pathway that provides the animal with information from its immediate environment. Through whisking, information is gathered that allows the animal to orientate itself and to recognize objects. This sensory system is crucial for nocturnal behaviour during which vision is not of much use. Sensory information of the whiskers are sent via brainstem and thalamus to the primary somatosensory area (S1) of the cerebral cortex in a strictly topological manner. Cell bodies in the layer N of S 1 are arranged in ring forming structures called barrels. As such, each barrel corresponds to the cortical representation in layer IV of a single whisker follicle. This histological feature allows to identify with uttermost precision the part of the cortex devoted to a given whisker and to study modifications induced by different experimental conditions. The condition used in the studies of my thesis is the passive stimulation of one whisker in the adult mouse for a period of 24 hours. It is performed by glueing a piece of metal on one whisker and placing the awake animal in a cage surrounded by an electromagnetic coil that generates magnetic field burst inducing whisker movement at a given frequency during 24 hours. I analysed the ultrastructure of the barrel corresponding the stimulated whisker using serial sections electron microscopy and computer-based three-dimensional reconstructions; analysis of neighbouring, unstimulated barrels as well as those from unstimulated mice served as control. The following elements were structurally analyzed: the spiny dendrites, the axons of excitatory as well as inhibitory cells, their connections via synapses and the astrocytic processes. The density of synapses and spines is upregulated in a barrel corresponding to a stimulated whisker. This upregulation is absent in the BDNF heterozygote mice, indicating that a certain level of activity-dependent released BDNF is required for synaptogenesis in the adult cerebral cortex. Synpaptogenesis is correlated with a modification of the astrocytes that place themselves in closer vicinity of the excitatory synapses on spines. Biochemical analysis revealed that the astrocytes upregulate the expression of transporters by which they internalise glutamate, the neurotransmitter responsible for the excitatory response of cortical neurons. In the final part of my thesis, I show that synaptogenesis in the stimulated barrel is due to the increase in the size of excitatory axonal boutons that become more frequently multisynaptic, whereas the inhibitory axons do not change their morphology but form more synapses with spines apposed to them. Taken together, my thesis demonstrates that all the cellular elements present in the neuronal tissue of the adult brain contribute to activity-dependent cortical plasticity and form part of a mechanism by which the animal responds to a modified sensory experience. Throughout life, the neuronal circuit keeps the faculty to adapt its function. These adaptations are partially transitory but some aspects remain and could be the structural basis of a memory trace in the cortical circuit. RESUME La plasticité neuronale chez l'adulte désigne un ensemble de mécanismes biologiques qui permettent aux circuits neuronaux de répondre et de s'adapter aux modifications des stimulations reçues. Les vibrisses des souris sont un système crucial fournissant des informations sensorielles au sujet de l'environnement de l'animal. L'information sensorielle collectée par les vibrisses est envoyée via le tronc cérébral et le thalamus à l'aire sensorielle primaire (S 1) du cortex cérébral en respectant strictement la somatotopie. Les corps cellulaires dans la couche IV de S 1 sont organisés en anneaux délimitant des structures nommées tonneaux. Chaque tonneau reçoit l'information d'une seule vibrisse et l'arrangement des tonneaux dans le cortex correspond à l'arrangement des vibrisses sur le museau de la souris. Cette particularité histologique permet de sélectionner avec certitude la partie du cortex dévolue à une vibrisse et de l'étudier dans diverses conditions. Le paradigme expérimental utilisé dans cette thèse est la stimulation passive d'une seule vibrisse durant 24 heures. Pour ce faire, un petit morceau de métal est collé sur une vibrisse et la souris est placée dans une cage entourée d'une bobine électromagnétique générant un champ qui fait vibrer le morceau de métal durant 24 heures. Nous analysons l'ultrastructure du cortex cérébral à l'aide de la microscopie électronique et des coupes sériées permettant la reconstruction tridimensionnelle à l'aide de logiciels informatiques. Nous observons les modifications des structures présentes : les dendrites épineuses, les axones des cellules excitatrices et inhibitrices, leurs connections par des synapses et les astrocytes. Le nombre de synapses et d'épines est augmenté dans un tonneau correspondant à une vibrisse stimulée 24 heures. Basé sur cela, nous montrons dans ces travaux que cette réponse n'est pas observée dans des souris hétérozygotes BDNF+/-. Cette neurotrophine sécrétée en fonction de l'activité neuronale est donc nécessaire pour la synaptogenèse. La synaptogenèse est accompagnée d'une modification des astrocytes qui se rapprochent des synapses excitatrices au niveau des épines dendritiques. Ils expriment également plus de transporteurs chargés d'internaliser le glutamate, le neurotransmetteur responsable de la réponse excitatrice des neurones. Nous montrons aussi que les axones excitateurs deviennent plus larges et forment plus de boutons multi-synaptiques à la suite de la stimulation tandis que les axones inhibiteurs ne changent pas de morphologie mais forment plus de synapses avec des épines apposées à leur membrane. Tous les éléments analysés dans le cerveau adulte ont maintenu la capacité de réagir aux modifications de l'activité neuronale et répondent aux modifications de l'activité permettant une constante adaptation à de nouveaux environnements durant la vie. Les circuits neuronaux gardent la capacité de créer de nouvelles synapses. Ces adaptations peuvent être des réponses transitoires aux stimuli mais peuvent aussi laisser une trace mnésique dans les circuits.

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Introduction The population of elderly persons is increasing andnegative outcomes due to polymedication are frequent. Discrepanciesin information about medication are frequent when older persons aretransitioning from hospital to home, increasing the risk of hospitalreadmission. The aims of this study were a) to determine discrepanciesin medical regimen indicated in two official discharge documents(DS = discharge summary, DP=discharge prescription); b) to characterizethe pharmacotherapy prescribed in older patients dischargedfrom a geriatric service.Materials & Methods Elderly patients (N=230) discharged from thegeriatric service (CHUV, Lausanne) over a 6-month period (January toJune 2009) were selected. Community pharmacists compared DS andDP to identify discrepancies including (a) drugs' name; (b) schedule ofadministration, dosage, frequency, prn prescription, treatment durationand galenic formulation. Beers' criteria were applied to identifypotentially inappropriate drugs and a descriptive analysis of drug costs,prescription profiles and generics were also performed.Results On average, patients were 82 ± 7 years old and stayed23.0 ± 11.6 days in the geriatric service. The delay between the datesof patient's discharge with the DP and the sending of the DS to hisgeneral physician averaged 14.0 ± 7.5 days (range 1-55). The DPhad an average of 10.0 ± 3.3 drugs (range 2-19). 77% of patients hadat least one discrepancy. A drug was missing on the DS in 57.8% ofpatients and 19.6% had a missing prn prescription. Among the 2312drugs prescribed, 3% belonged to Beers' list. They were prescribed to61 patients (26.5%), with 6 patients cumulating two Beers' potentiallyinappropriate drugs in their treatment. Analgesics (85% of thepatients), anticoagulants (80%), mineral supplements (77%), laxatives(52%) and antihypertensives (46%) were the drug classes most frequentlyprescribed. Mean costs of treatment as per DP was160.4 ± 179.4 Euros. Generic prescription represented more than 5%of the costs for 3 therapeutic classes (cholesterol-lowering agents(64%), antihypertensives (50%) and antidepressants (47%)).Discussion & Conclusion The high discrepancy rate between medicationlisted in the DP and the DS highlights a need for safetyimprovement. Potential benefits are expected from reinforced pharmacist-physician collaboration in transition from hospital to primarycare. In addition, even though Beers' criteria are questionable, thedrugs prescribed in this already fragile population, and the potentialopportunities of economical optimizations, are advocating thedevelopment and the scientific evaluation of a structured advancedcollaborative pharmacy practice service. This foresees improvedeffectiveness, safety and efficiency in the medication management ofelderly persons.

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Decisions taken in modern organizations are often multi-dimensional, involving multiple decision makers and several criteria measured on different scales. Multiple Criteria Decision Making (MCDM) methods are designed to analyze and to give recommendations in this kind of situations. Among the numerous MCDM methods, two large families of methods are the multi-attribute utility theory based methods and the outranking methods. Traditionally both method families require exact values for technical parameters and criteria measurements, as well as for preferences expressed as weights. Often it is hard, if not impossible, to obtain exact values. Stochastic Multicriteria Acceptability Analysis (SMAA) is a family of methods designed to help in this type of situations where exact values are not available. Different variants of SMAA allow handling all types of MCDM problems. They support defining the model through uncertain, imprecise, or completely missing values. The methods are based on simulation that is applied to obtain descriptive indices characterizing the problem. In this thesis we present new advances in the SMAA methodology. We present and analyze algorithms for the SMAA-2 method and its extension to handle ordinal preferences. We then present an application of SMAA-2 to an area where MCDM models have not been applied before: planning elevator groups for high-rise buildings. Following this, we introduce two new methods to the family: SMAA-TRI that extends ELECTRE TRI for sorting problems with uncertain parameter values, and SMAA-III that extends ELECTRE III in a similar way. An efficient software implementing these two methods has been developed in conjunction with this work, and is briefly presented in this thesis. The thesis is closed with a comprehensive survey of SMAA methodology including a definition of a unified framework.

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The continuous wavelet transform is obtained as a maximumentropy solution of the corresponding inverse problem. It is well knownthat although a signal can be reconstructed from its wavelet transform,the expansion is not unique due to the redundancy of continuous wavelets.Hence, the inverse problem has no unique solution. If we want to recognizeone solution as "optimal", then an appropriate decision criterion hasto be adopted. We show here that the continuous wavelet transform is an"optimal" solution in a maximum entropy sense.

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Granular flow phenomena are frequently encountered in the design of process and industrial plants in the traditional fields of the chemical, nuclear and oil industries as well as in other activities such as food and materials handling. Multi-phase flow is one important branch of the granular flow. Granular materials have unusual kinds of behavior compared to normal materials, either solids or fluids. Although some of the characteristics are still not well-known yet, one thing is confirmed: the particle-particle interaction plays a key role in the dynamics of granular materials, especially for dense granular materials. At the beginning of this thesis, detailed illustration of developing two models for describing the interaction based on the results of finite-element simulation, dimension analysis and numerical simulation is presented. The first model is used to describing the normal collision of viscoelastic particles. Based on some existent models, more parameters are added to this model, which make the model predict the experimental results more accurately. The second model is used for oblique collision, which include the effects from tangential velocity, angular velocity and surface friction based on Coulomb's law. The theoretical predictions of this model are in agreement with those by finite-element simulation. I n the latter chapters of this thesis, the models are used to predict industrial granular flow and the agreement between the simulations and experiments also shows the validation of the new model. The first case presents the simulation of granular flow passing over a circular obstacle. The simulations successfully predict the existence of a parabolic steady layer and show how the characteristics of the particles, such as coefficients of restitution and surface friction affect the separation results. The second case is a spinning container filled with granular material. Employing the previous models, the simulation could also reproduce experimentally observed phenomena, such as a depression in the center of a high frequency rotation. The third application is about gas-solid mixed flow in a vertically vibrated device. Gas phase motion is added to coherence with the particle motion. The governing equations of the gas phase are solved by using the Large eddy simulation (LES) and particle motion is predicted by using the Lagrangian method. The simulation predicted some pattern formation reported by experiment.

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Centrifugal compressors are widely used for example in process industry, oil and gas industry, in small gas turbines and turbochargers. In order to achieve lower consumption of energy and operation costs the efficiency of the compressor needs to be improve. In the present work different pinches and low solidity vaned diffusers were utilized in order to improve the efficiency of a medium size centrifugal compressor. In this study, pinch means the decrement of the diffuser flow passage height. First different geometries were analyzed using computational fluid dynamics. The flow solver Finflo was used to solve the flow field. Finflo is a Navier-Stokes solver. The solver is capable to solve compressible, incompressible, steady and unsteady flow fields. Chien's k-e turbulence model was used. One of the numerically investigated pinched diffuser and one low solidity vaned diffuser were studied experimentally. The overall performance of the compressor and the static pressure distribution before and after the diffuser were measured. The flow entering and leaving the diffuser was measured using a three-hole Cobra-probe and Kiel-probes. The pinch and the low solidity vaned diffuser increased the efficiency of the compressor. Highest isentropic efficiency increment obtained was 3\% of the design isentropic efficiency of the original geometry. It was noticed in the numerical results that the pinch made to the hub and the shroud wall was most beneficial to the operation of the compressor. Also the pinch made to the hub was better than the pinchmade to the shroud. The pinch did not affect the operation range of the compressor, but the low solidity vaned diffuser slightly decreased the operation range.The unsteady phenomena in the vaneless diffuser were studied experimentally andnumerically. The unsteady static pressure was measured at the diffuser inlet and outlet, and time-accurate numerical simulation was conducted. The unsteady static pressure showed that most of the pressure variations lay at the passing frequency of every second blade. The pressure variations did not vanish in the diffuser and were visible at the diffuser outlet. However, the amplitude of the pressure variations decreased in the diffuser. The time-accurate calculations showed quite a good agreement with the measured data. Agreement was very good at the design operation point, even though the computational grid was not dense enough inthe volute and in the exit cone. The time-accurate calculation over-predicted the amplitude of the pressure variations at high flow.

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A maximum entropy statistical treatment of an inverse problem concerning frame theory is presented. The problem arises from the fact that a frame is an overcomplete set of vectors that defines a mapping with no unique inverse. Although any vector in the concomitant space can be expressed as a linear combination of frame elements, the coefficients of the expansion are not unique. Frame theory guarantees the existence of a set of coefficients which is “optimal” in a minimum norm sense. We show here that these coefficients are also “optimal” from a maximum entropy viewpoint.

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This work is devoted to the problem of reconstructing the basis weight structure at paper web with black{box techniques. The data that is analyzed comes from a real paper machine and is collected by an o®-line scanner. The principal mathematical tool used in this work is Autoregressive Moving Average (ARMA) modelling. When coupled with the Discrete Fourier Transform (DFT), it gives a very flexible and interesting tool for analyzing properties of the paper web. Both ARMA and DFT are independently used to represent the given signal in a simplified version of our algorithm, but the final goal is to combine the two together. Ljung-Box Q-statistic lack-of-fit test combined with the Root Mean Squared Error coefficient gives a tool to separate significant signals from noise.

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A wide variety of whole cell bioreporter and biosensor assays for arsenic detection has been developed over the past decade. The assays permit flexible detection instrumentation while maintaining excellent method of detection limits in the environmentally relevant range of 10-50 μg arsenite per L and below. New emerging trends focus on genetic rewiring of reporter cells and/or integration into microdevices for more optimal detection. A number of case studies have shown realistic field applicability of bioreporter assays.

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Cigar and pipe smoking are considered risk factors for head and neck cancers, but the magnitude of effect estimates for these products has been imprecisely estimated. By using pooled data from the International Head and Neck Cancer Epidemiology (INHANCE) Consortium (comprising 13,935 cases and 18,691 controls in 19 studies from 1981 to 2007), we applied hierarchical logistic regression to more precisely estimate odds ratios and 95% confidence intervals for cigarette, cigar, and pipe smoking separately, compared with reference groups of those who had never smoked each single product. Odds ratios for cigar and pipe smoking were stratified by ever cigarette smoking. We also considered effect estimates of smoking a single product exclusively versus never having smoked any product (reference group). Among never cigarette smokers, the odds ratio for ever cigar smoking was 2.54 (95% confidence interval (CI): 1.93, 3.34), and the odds ratio for ever pipe smoking was 2.08 (95% CI: 1.55, 2.81). These odds ratios increased with increasing frequency and duration of smoking (Ptrend ≤ 0.0001). Odds ratios for cigar and pipe smoking were not elevated among ever cigarette smokers. Head and neck cancer risk was elevated for those who reported exclusive cigar smoking (odds ratio = 3.49, 95% CI: 2.58, 4.73) or exclusive pipe smoking (odds ratio = 3.71, 95% CI: 2.59, 5.33). These results suggest that cigar and pipe smoking are independently associated with increased risk of head and neck cancers.