• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 15
  • 15
  • 9
  • 9
  • 9
  • 9
  • 6
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Trabalho mecânico e custo de transporte da caminhada de pacientes com acidente vascular encefálico isquêmico

Schuch, Clarissa Cristini Pedrini January 2011 (has links)
O acidente vascular encefálico (AVE) do tipo isquêmico representa 80% dos casos de AVE no Brasil; este é resultante da interrupção do suprimento sanguíneo ao tecido cerebral. Uma sequela decorrente da lesão do neurônio motor superior é a hemiparesia, estado caracterizado pela perda parcial da força muscular de um lado do corpo. Por sua vez, a locomoção hemiparética é característica comum após o episódio de AVE. Clinicamente os pacientes apresentam alterações no controle motor, excessiva co-ativação muscular e espasticidade, assim como mudanças nas propriedades passivas dos músculos. Além disso, os padrões cinemáticos alterados acarretam em diminuição da amplitude de movimento e consequentemente redução na velocidade de caminhada e maior dispêndio energético. Dessa maneira, um melhor entendimento de como os acometimentos segmentares afetam o trabalho mecânico total (Wtot) e o custo de transporte (C) da caminhada de indivíduos com AVE pode auxiliar na avaliação da eficácia das intervenções terapêuticas. Assim, este estudo tem como objetivo mensurar e comparar o Wtot e o C em cinco diferentes velocidades de caminhada entre sujeitos hemiparéticos crônicos decorrente do AVE e sujeitos saudáveis. A amostra foi composta por 6 pacientes com diagnóstico clínico de AVE do tipo isquêmico e 10 sujeitos saudáveis (grupo controle). Foi utilizada a cinemetria tridimensional e um sistema de análise metabólica para aquisição dos dados. Os resultados indicaram que os pacientes com AVE apresentaram Wtot e C significativamente maior em relação aos sujeitos do grupo controle. O aumento no Wtot se deve principalmente ao maior trabalho mecânico vertical (Wv) e trabalho mecânico interno (Wint), e.g., Wint rotacional do membro não acometido teve contribuição de até 50% para o resultado de Wint. Os pacientes AVE apresentaram C significativamente maior nas baixas velocidades de caminhada; enquanto nas demais velocidades os grupos foram similares. Pode-se concluir que em reposta ao prejuízo para o sistema de movimento em decorrência ao AVE, os pacientes adaptam a marcha e realizam compensações com o objetivo de minimizar os déficits funcionais. / Ischemic stroke represents 80% of stroke cases in Brazil, and it is result of a blood flow interruption into brain tissue. This upper motor neuron injury leads to hemiparesis, state characterized by partial loss of muscle strength at one side of the body. Hemiparetic gait is a common feature after stroke episode. Clinically, patients present alterations in motor control, excessive co-activation and muscle spasticity, as well as changes in passive properties of muscles. Moreover, kinematic deviations lead to a decreased range of motion and consequently a reduction in walking speed and a higher energy expenditure. Thus, a better understanding of how segmentar impairments affect total mechanical work (Wtot) and cost of transport (C) in stroke patients allows verifying the efficacy of therapeutic interventions. Therefore, this study aims to measure and compare Wtot and C at five different walking speeds between hemiparetic post-stroke patients and healthy subjects. Six patients with clinical diagnostic of ischemic stroke and ten healthy subjects (control group) participated in the present study. Three-dimensional motion analysis system and metabolic analysis system were employed for data acquisition. Results indicated that stroke group showed significantly higher Wtot and C than control group. The increased Wtot is mainly due to higher vertical mechanical work (Wv) and internal mechanical work (Wint), i.e., higher Wint rotational of uninvolved limb; accounted for a 50% contribution to Wint results. The stroke group had significantly higher C at lower speeds, while for other speeds both groups were similar. In conclusion the stroke group showed a compensatory response in the neuromuscular system, on which stroke patients adapted their gait mechanics in order to minimize functional deficits.
12

Efeitos da velocidade nos paramêtros mecânicos e energéticos da locomoção de amputados transfemurais / Effects of speed on mechanics and energetics of transfemoral amputee walking

Bona, Renata Luisa January 2011 (has links)
A caminhada humana é um movimento importante utilizado pelo homem, porém extremamente complexo em relação aos mecanismos energéticos e mecânicos que geram este movimento. O custo energético é maior na caminhada de amputados quando comparada a caminhada de indivíduos sem restrições físicas. Variáveis mecânicas e energéticas de amputados não foram extensivamente estudadas. Nosso objetivo foi avaliar a influência de diferentes velocidades, no recovery, no custo de transporte (C), na eficiência mecânica (Eff), na transdução pendular (Rint), trabalho mecânico, na estabilidade dinâmica, bem como verificar a associação entre a estabilidade dinâmica com recovery, custo de transporte e eficiência mecânica. Participaram do estudo 10 indivíduos amputados transfemurais (com joelho hidráulico e pé em fibra de carbono). Foi realizada cinemetria 3D (quatro câmeras de vídeo) e simultaneamente a análise do consumo de oxigênio. Foram determinadas cinco velocidades de caminhada, após definir a velocidade auto selecionada. Além da velocidade auto selecionada foram definidas duas velocidades acima e abaixo das VAS. Para os dados de Recovery, custo de transporte, eficiência mecânica, transdução pendular, trabalho total, trabalho externo, travalho vertical, trabalho horizontal, trabalho interno e estabilidade dinâmica foram utilizadas rotinas desenvolvidas em Matlab®. A velocidade influencia nos parâmetros mecânicos e energéticos da caminhada de amputados transfemurais. Os maiores valores para: economia de caminhada, Recovery, transdução pendular, eficiência mecânica, trabalho mecânico interno e vertical, e estabilidade dinâmica foram obtidos na máxima velocidade de caminhada dos sujeitos. As correlações entre o coeficiente de variação do comprimento da passada e Recovery, custo de transporte e potência metabólica foram moderadas. Esses resultados são de grande relevância para a área clínica e ponderados durante o processo de reabilitação desses indivíduos. / The human walking is an important movement used by man, but extremely complex in relation to the energetic and mechanical mechanisms that generate this movement. The energy cost of gait is greater in amputees than in normal subjects. Mechanical and energetics variables in amputees have not been extensively studied. Our objective was to assess the influence of speed in recovery, cost of transport (C), mechanical efficiency (Eff), pendular transduction (Rint), mechanic parameters, dynamical stability, well as to verify agreement between dynamical stability with recovery, C, Eff and metabolic power. Materials and Methods: ten transfemoral amputees (with hydraulic knee and carbon fiber foot) were selected in the study. Simultaneously three-dimensional (3D) kinematics data (four cameras) and oxygen consumption were collected at five speeds, two above and two below self-select one. The Recovery, C, Eff, Rint, dynamical stability, were processed using Matlab software. Mechanics and energetics of amputee walking were influenced by speed. In maximal speed of amputee walking were reported greatest values, like: recovery, cost of transport (C), mechanical efficiency (Eff), pendular transduction (Rint), internal and vertical mechanical work and dynamical stability. Pearson correlation between dynamical stability and Recovery, C, Eff and metabolic power were moderate. These results are clinical relevance and should be considered during the rehabilitation of these individuals.
13

Trabalho mecânico e custo de transporte da caminhada de pacientes com acidente vascular encefálico isquêmico

Schuch, Clarissa Cristini Pedrini January 2011 (has links)
O acidente vascular encefálico (AVE) do tipo isquêmico representa 80% dos casos de AVE no Brasil; este é resultante da interrupção do suprimento sanguíneo ao tecido cerebral. Uma sequela decorrente da lesão do neurônio motor superior é a hemiparesia, estado caracterizado pela perda parcial da força muscular de um lado do corpo. Por sua vez, a locomoção hemiparética é característica comum após o episódio de AVE. Clinicamente os pacientes apresentam alterações no controle motor, excessiva co-ativação muscular e espasticidade, assim como mudanças nas propriedades passivas dos músculos. Além disso, os padrões cinemáticos alterados acarretam em diminuição da amplitude de movimento e consequentemente redução na velocidade de caminhada e maior dispêndio energético. Dessa maneira, um melhor entendimento de como os acometimentos segmentares afetam o trabalho mecânico total (Wtot) e o custo de transporte (C) da caminhada de indivíduos com AVE pode auxiliar na avaliação da eficácia das intervenções terapêuticas. Assim, este estudo tem como objetivo mensurar e comparar o Wtot e o C em cinco diferentes velocidades de caminhada entre sujeitos hemiparéticos crônicos decorrente do AVE e sujeitos saudáveis. A amostra foi composta por 6 pacientes com diagnóstico clínico de AVE do tipo isquêmico e 10 sujeitos saudáveis (grupo controle). Foi utilizada a cinemetria tridimensional e um sistema de análise metabólica para aquisição dos dados. Os resultados indicaram que os pacientes com AVE apresentaram Wtot e C significativamente maior em relação aos sujeitos do grupo controle. O aumento no Wtot se deve principalmente ao maior trabalho mecânico vertical (Wv) e trabalho mecânico interno (Wint), e.g., Wint rotacional do membro não acometido teve contribuição de até 50% para o resultado de Wint. Os pacientes AVE apresentaram C significativamente maior nas baixas velocidades de caminhada; enquanto nas demais velocidades os grupos foram similares. Pode-se concluir que em reposta ao prejuízo para o sistema de movimento em decorrência ao AVE, os pacientes adaptam a marcha e realizam compensações com o objetivo de minimizar os déficits funcionais. / Ischemic stroke represents 80% of stroke cases in Brazil, and it is result of a blood flow interruption into brain tissue. This upper motor neuron injury leads to hemiparesis, state characterized by partial loss of muscle strength at one side of the body. Hemiparetic gait is a common feature after stroke episode. Clinically, patients present alterations in motor control, excessive co-activation and muscle spasticity, as well as changes in passive properties of muscles. Moreover, kinematic deviations lead to a decreased range of motion and consequently a reduction in walking speed and a higher energy expenditure. Thus, a better understanding of how segmentar impairments affect total mechanical work (Wtot) and cost of transport (C) in stroke patients allows verifying the efficacy of therapeutic interventions. Therefore, this study aims to measure and compare Wtot and C at five different walking speeds between hemiparetic post-stroke patients and healthy subjects. Six patients with clinical diagnostic of ischemic stroke and ten healthy subjects (control group) participated in the present study. Three-dimensional motion analysis system and metabolic analysis system were employed for data acquisition. Results indicated that stroke group showed significantly higher Wtot and C than control group. The increased Wtot is mainly due to higher vertical mechanical work (Wv) and internal mechanical work (Wint), i.e., higher Wint rotational of uninvolved limb; accounted for a 50% contribution to Wint results. The stroke group had significantly higher C at lower speeds, while for other speeds both groups were similar. In conclusion the stroke group showed a compensatory response in the neuromuscular system, on which stroke patients adapted their gait mechanics in order to minimize functional deficits.
14

Swimming in four goldfish (Carassius auratus) morphotypes: understanding functional design and performance through artificial selection

Li, Jason 05 1900 (has links)
Although artificially selected goldfish exhibit swimming performance decrements, with the most derived morphotypes more affected, they can be utilized to explore functional design and movement pattern principles in aquatic vertebrates. Drag, steady swimming kinematics (tailbeat frequency, amplitude, stride length), energetics (standard and active metabolic rate), fast-start performance (average and maximum velocity and acceleration), stability in yaw and roll and propulsive muscle ultrastructural characteristics (mitochondrial volume density and spacing, myofibril diameter and capillary to fibre ratio in red and white muscle) were measured for four morphotypes: common, comet, fantail and eggfish, of comparable length (≈ 5 cm). A performance “pairing” (common and comet; fantail and eggfish) was a recurrent theme for most performance parameters. Vertebral numbers (30), segment lengths (≈ 0.85 mm) and standard metabolic rates (≈ 140 mg O2 kg-1 hr-1) are exceptions where values are the same. Fantail and eggfish drag and drag coefficients (referenced to frontally projected area ≈ 0.6 - 0.9) were higher (requiring more thrust at any given velocity) than those for the more streamlined common and comet (≈ 0.3 - 0.6; P < 0.05). This is reflected in kinematics; tailbeat frequency and stride length at any given velocity for the common and comet are lower and higher respectively than that of the fantail and eggfish (P < 0.05). Common and comet fatigue times are not significantly different from that of their ancestor, Crucian carp (P > 0.05), and are lower than those of the fantail and eggfish (P < 0.05). The cost of transport of the common and comet (≈ 0.6 mg O2 kg-1 m-1) is accurately predicted from the mass scaling relationship for fish (P > 0.05), but values for the fantail and eggfish (≈ 1.3 mg O2 kg-1 m-1) are not (P < 0.05). Eggfish steady swimming (dorsal fin absent) was characterized by rolling and yawing motions associated with significant energy losses. Common and comet fast-start performance (average velocity ≈ 0.45 m s-1, maximum velocity ≈ 1.2 m s-1, average acceleration ≈ 7.5 m s-2, maximum acceleration ≈ 35 m s-2) was similar to that of other locomotor generalists (e.g. trout). Eggfish maximum acceleration (≈ 5 m s-2) is poor due to the absence of inertial and lifting contributions to thrust from the dorsal fin and energy wasting rolling motions. Artificially selected fish can bear upon fitness related adaptations associated with form and movement, providing insights into the “performance envelope” of natural systems subject to ecological speciation. / Science, Faculty of / Zoology, Department of / Graduate
15

Tids- och kostnadseffektivitet vid intermodala transporter / Time and cost efficiency within intermodal transportation

Ahlnäs, Simon, Börjesson, Tobias January 2017 (has links)
This study aims to explore effectiveness within intermodal transportation of semi-trailers based on the variables cost and time. Intermodal transport can be explained as a transportation of a carrier, from the origin to the final destination, using two or more modes of transport (Crainic &amp; Kim, 2007 p.467). This study focuses on the two modes of transport rail and road. The rail transportation has big advantages towards other modes of transport since it has less impact on the environment, given that the energy is produced in Sweden (Trafikverket 2017) but there are more benefits to be utilized. The rail transportation is generally more profitable on distances greater than 500 km, thus it can transport high volumes of goods over long distances for a low cost. The fixed costs that´s added in the terminals and the rail transports low degree of flexibility compared to the road transport is the primary reasons why rail transportation isn´t profitable on shorter distances. This study has made a market research to see where the final destinations for the imported semi-trailers are located in Sweden and Norway. This, to see where there are potential to develop and create new rail shuttles from Port of Gothenburg to dry ports across the Swedish and Norwegian inland for transportation of semi-trailers. Interviews have been conducted with carriers to create a more correct view of the current situation. Study results show that the greatest volumes of the transported semi-trailers ends up in the areas around Helsingborg and Stockholm, with the region around Gothenburg excluded. Dry ports positioned in this area show the best potential for development of new rail shuttles. The results from conducted interviews with carriers express that time is the most important aspect for their operation and their clients, that is also the reason why they don´t use the railway for transportation of semi-trailers. Carriers also consider the trains to be unreliable and the railway operation in Port of Gothenburg has so far not been operating well enough for them. The result show that 38 percent of the imported semi-trailers have their final destination in the area around Gothenburg and naturally it´s not possible for the railway to compete with the road transport at such a short distance. In order for the railway to compete with the road transport, rail shuttles to regions with high flows of semi-trailers must be developed to not loose in time and flexibility. Thus, the railway transportation has other opportunities than just transportation. In dry ports there are opportunities for storage of goods, which is generally cheaper than in the port and simultaneously create time gains in the final transportation, thus the goods are closer to the customer. Port of Gothenburg can compete with other ports, which are geographically closer to a certain customer, through more rail shuttles with more frequent departures and then take more market shares within Nordic transportation. / Studien syftar till att undersöka transporteffektiviteten för intermodala transporter av semitrailrar med utgångspunkt från variablerna kostnad och tid. Intermodala transporter kan förklaras som en transport av en lastbärare från dess ursprung till dess slutdestination med hjälp av två eller flera olika transportsätt (Crainic &amp; Kim, 2007 s.467) och denna studie fokuserar på de två transportsätten järnväg och väg. Just järnvägstransporten har en stor fördel gentemot andra transportsätt då det är ett mer miljövänligt alternativ, förutsatt att det är eldrivna tåg samt att elen är producerad i Sverige (Trafikverket 2017) men det finns även fler fördelar som kan utnyttjas. Järnvägstransporten är generellt lönsammare på avstånd längre än 500 km, då det kan transportera stora volymer över långa avstånd till en låg kostnad. Varför det inte är lönsamt på kortare sträckor beror framför allt på de fasta avgifter som tillkommer vid terminalerna och järnvägens relativt låga flexibilitet gentemot vägtransporten. Studien har gjort en marknadsundersökning för att se var de importerade semitrailrarna har sin slutdestination inom Sverige och Norge. Det för att se var det finns potential för att utveckla och skapa nya järnvägspendlar från Göteborgs Hamn till torrhamnar för transport av semitrailrar via järnväg. Intervjuer har utförts med speditörer i anslutning till hamnen för att skapa en så bra bild som möjligt av nuläget. Resultatet visar att de största volymerna i flödet av semitrailrar går till Helsingborg och Stockholm med omnejd, med Göteborg exkluderat. Det är de två områdena som visar potential för att eventuellt skapa järnvägspendlar till torrhamnar. Vid intervjuerna som utförts uttrycker speditörerna att tid är den viktigaste aspekten för deras verksamhet och kunder. Det är även anledningen till att de inte använder sig av järnvägstransport för semitrailrar, då tågen är för opålitliga och verksamheten för järnvägstransport kring Göteborgs Hamn inte har fungerat för dem hitintills. Resultatet visar även att drygt 38 procent av de importerade semitrailrarna har sin slutdestination i Göteborgsområdet och där kan naturligtvis inte järnvägstransporten konkurrera med vägtransporten på grund av det korta avståndet. För att järnvägstransporten ska kunna konkurrera med vägtransporten måste det skapas pendlar till de regionerna med större flöden för att inte förlora tid och flexibilitet gentemot vägtransporten. Dock så ger järnvägstransporten andra möjligheter än bara transport av gods. I torrhamnarna finns möjligheter för lagring av gods, som generellt är billigare än lagring i hamnen och ger samtidigt tidsvinster när den slutliga transporten till kund ska utföras, då godset är närmare kunden. Göteborgs Hamn kan konkurrera med andra hamnar som geografisk ligger närmare en viss kund, genom att fler järnvägspendlar med frekventare avgångar kan skapas och på så sätt ta marknadsandelar inom nordisk transport.

Page generated in 0.0709 seconds