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Det avlastande bärsystemets påverkan på att bära en sjukbår : en studie baserad på prov och försök / The releiving carrying systems effect on stretcher carriageHallgren, Adam January 2021 (has links)
For a wounded soldier to have as good a chance of survival as possible, an important variable during care is the time it takes for the wounded to get to a high-quality medical facility where there is expertise in surgery. If the injured person is to be transported with a stretcher carried by other soldiers, the speed for which this can be done is limited by the strength of the bearer in the hands and forearms.This study aims to explore how the speed and perceived ergonomics of those who carry a stretcher can change for a group if it is issued a relieving carrying system that redistributes the load of the stretcher to the hips, back and legs. The study is largely based on a study by Knapik et al (2000) where similar tests were done in a controlled indoor environment but where this study was done in a field environment with groups of 2 or 4 people carrying a stretcher.The study is done in the form of tests and experiments with conscripts from Skaraborg Wing, F 7. The conscripts carried a stretcher in a field-like environment where speed, comfort and usability were in focus. The study was also done with a questionnaire belonging to the experiments to value the experience.The study resulted in a relieving carrying system integrated in the Swedish Armed Forces' combat vest 2000 having an increased average speed with the median 30.7% when carrying a stretcher loaded with 100 kg. The analysis shows that it is above all women who benefit greatly from not carrying a stretcher with their hands. Something they are statistically worse at than men. The study also shows that there are tendencies that the comfort is improved for a soldier. / För att en sårad soldat ska ha så goda chanser till överlevnad som möjligt är en viktig variabel under omhändertagandet tiden det tar för den sårade att komma till en högkvalitativ sjukvårdsinrättning, där det finns expertis inom kirurgi. Om den skadade ska transporteras med sjukbår som bärs av andra soldater, är hastigheten för vilket detta kan göras begränsad av de bärandes styrka i händer och underarmar.Denna studie syftar till att utforska hur hastigheten samt den upplevda ergonomin för de som bär en sjukbår kan förändras för en grupp om den tillförs ett avlastande bärsystem som omfördelar lasten till höfter, rygg och benen. Studien baseras till stor del på en studie av Knapik med flera (2000) där liknande tester gjordes i en kontrollerad inomhusmiljö, men där denna studie är gjord i en fältmiljö med grupper om 2 eller 4 personer som bär en sjukbår.Studien är gjord i form av prov och försök med värnpliktiga ur Skaraborgs Flygflottilj, F 7, som bär en bår i en fältliknande miljö där hastigheten, komforten och användbarheten stod i fokus. Studien är även gjord med en enkätundersökning tillhörande försöken i syfte att skatta upplevelsen.Studien resulterade i att ett avlastande bärsystem integrerat i Försvarsmaktens stridsväst 2000 medförde en ökad snitthastighet, med medianen 30,7%, vid bärande av en sjukbår 2 lastad med 100 kg. Analysen påvisar att det framför allt är kvinnor som har stor nytta av att inte bära en sjukbår med händerna, något de statistiskt sett är sämre på än män. Studien visar även att det finns tendenser för att komforten förbättras för en soldat men användbarheten är oförändrad.
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Jämförelse av motorisk och sensorisk nervledningshastighet, amplitud och handgreppsstyrka mellan dominant och icke-dominant hand / Comparison of Motor and Sensory Nerve Conduction Velocity, Amplitude and Hand strength between dominant and non-dominant handSvang, Maja January 2021 (has links)
Elektroneurografi är en undersökningsmetod som används för att undersöka nervledingskapaciteten i perifera nerver. Det är en metod som ofta används på sjukhuskliniker vid diagnostisering av perifera nervsjukdomar. Syftet med studien är att undersöka om det finns en signifikant skillnad i motorisk och sensorisk nervledningshastighet, amplitud och F-respons mellan dominant och icke-dominant hand. I studien undersöktes det även om en korrelation finns mellan handgreppsstyrka och svarsamplitud från motorisk elektroneurografi. I studien deltog 26 testpersoner från biomedicinska analytikerprogrammet i termin 6. Testpersonernas genomsnittsålder är 24 år (range 21-32 år), och testpersonernas kroppslängd är i genomsnitt 169 cm (range 155- 185). Elektroneurografi utfördes motoriskt och sensoriskt på nervus medianus bilateralt. Handgreppsstyrka undersöktes bilateralt med Jamar Hydraulic Hand dynamometer. För samtliga mätvariabler bestämdes signifikantnivån till α=0,05. Resultatet visar att det finns en signifikant skillnad i sensorisk nervledningshastighet, motorisk amplitud och sensorisk amplitud mellan dominant och icke-dominant hand. Sensorisk nervledningshastighet är högre i icke-dominant hand, medan motorisk och sensorisk amplitud är högre i dominant hand. Däremot kan inte en signifikant skillnad påvisas i motorisk nervledningshastighet, FM-latens samt antalet F-svar mellan dominant och icke-dominant hand. Resultatet visar att det inte finns någon korrelation mellan handgreppsstyrka och amplitud i motorisk elektroneurografi. I dag används samma referensvärden för dominant och icke-dominant hand. Den här studien visar att det kan finnas ett värde i att utforma referensintervall som baseras på handdominans. / Electroneurography is an examination method used for examining the nerve conduction capacity of the peripheral nerve. The method is often used in hospitals in the diagnosis of peripheral nerve injuries. The aim of this study is to examine if there is a significant difference in motor and sensory nerve conduction velocity, amplitude, and F-response between dominant and non-dominant hands. The correlation between hand grip strength and the amplitude in motor electroneurography was also examined in this study. The study involved 26 students from Biomedical Scientist Programme term 6. The average age of the participants is 24 years (range 21-32 years), and the participants body length is on average 169 cm (range 155-185 cm). Electroneurography was performed on the median nerve bilaterally. Hand grip strength was examined bilaterally with Jamar Hydraulic Hand dynamometer. For all measurement variables, the significant level was determined to α=0,05. The result shows that there is a significant difference in sensory nerve conduction velocity, motor amplitude, and sensory amplitude between dominant and non-dominant hands. Sensory nerve conduction velocity is higher in non-dominant hand, while motor and sensory amplitude is higher in dominant hand. However, a significant difference cannot be detected in motor nerve conduction velocity, FM-latency, and the number of F-responses between dominant and non-dominant hands. The result shows no correlation between hand grip strength and the amplitude in motor electroneurography. Today, the same reference values are used for dominant and non-dominant hands. This study shows that there may be a value in creating reference intervals based on hand dominance.
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Rapid Grip Strength and Muscle Activity as Predictors of Reaction TimeRodriguez, Gabriela 01 January 2021 (has links)
INTRODUCTION: Reaction time may be broadly defined as the time between stimulus presentation and a response. Analysis of reaction time in terms of rate of force development (RFD), peak force, and surface electromyography (EMG) may help bridge the gaps in knowledge pertaining to the neuromuscular system's role in reaction time. The purpose of the present study was to identify predictors of reaction time using digital hand grip dynamometry and EMG. It was hypothesized that RFD and rate of EMG rise (RER) at the onset of a contraction would correlate with reaction time.
METHODS: For grip testing, participants were instructed to squeeze a handheld dynamometer with the right hand "…as hard and fast as possible" for 5 seconds upon hearing a "beep" from the computer. A total of 5 attempts were performed, with 1-minute rest periods. Bipolar surface EMG signals were detected from the right first dorsal interosseous (FDI) and flexor carpi radialis (FCR) muscles throughout grip testing. Bivariate correlations (Pearson r) were used to examine the statistical associations. The 95% confidence interval (CI) for each Pearson r was also computed. An alpha level of p ≤ 0.05 was used to reject the null hypothesis.
RESULTS: Significant correlations were observed between reaction time and all other measures of grip force (r = -0.507 to -0.557, p= 0.016 to 0.042), except for time until peak force (r = 0.029, p = 0.915). As FDI EMG amplitude increased reaction time decreased (r = -0.664, p = .005).
CONCLUSION: Many of the grip force variables were significantly associated with reaction time. Peak force and rapid force variables showed significant correlations with reaction time. While no significant correlations for any of the FDI RER or FCR variables were found, EMG amplitude from the FDI presented the strongest bivariate correlation. As FDI EMG amplitude, peak force, and rapid force variables increased reaction time decreased. These findings give some insight into the neuromuscular system's role in hand grip tasks and help broaden the current understanding of variables that may be used to assess or improve reaction time in the clinical setting.
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Effect of Early Life Physical Inactivity Level on Muscle Health During Early Postnatal DevelopmentSmith, Austin 02 August 2022 (has links)
No description available.
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Modulation tâche-dépendante des mécanismes inhibiteurs et désinhibiteurs du cortex moteur primaire chez l’homme / Task-dependent change in inhibitory and disinhibitory mechanisms within the primary motor cortex in humansCaux-Dedeystère, Alexandre 29 September 2016 (has links)
Les mouvements sont le résultat de contractions musculaires dont l’organisation spatio-temporelle est régie par des structures cérébrales et médullaires. Etudier les circuits qui les sous-tendent est une étape indispensable pour renforcer nos connaissances des mécanismes à l’origine de la commande des mouvements volontaires et pour mieux comprendre la pathophysiologie des mouvements anormaux. Les muscles squelettiques sont innervés par les motoneurones alpha de la moelle épinière qui à leur out sont influencés par des neurones des aires corticales motrices. Cette voie descendante constitue la voie corticomotoneuronale (CM) et est responsable de l’exécution des mouvements volontaires. Le cortex moteur primaire est considéré comme une structure clé, au cœur du système, permettant l’intégration complexe de nombreuses influences multi-régions pour conduire aux comportements moteurs adéquats. Les interactions qui existent entre les différents groupes de neurones au sein de M1 influent en dernier lieu sur la sortie motrice. De la balance complexe entre ces influences inhibitrices et excitatrices, locales ou à distance va dépendre l’état d’excitabilité des cellules CM contrôlant les différents muscles. L'objectif de ce travail de thèse était d'étudier comment évoluent certains de ces mécanismes excitateurs ou inhibiteurs du cortex moteur primaire lorsque la commande motrice volontaire d’un muscle de l’index est modifiée. Nous avons étudié le rôle de ces mécanismes dans les changements d’excitabilité de la voie CM qui accompagnent la contraction tonique volontaire du muscle premier interosseus dorsalis (FDI) en comparant une tâche simple mais peu naturelle : l’abduction de l'index, une tâche naturelle plus complexe: la pince pouce-index et la condition de repos musculaire. Nous avons également étudié l’effet de la commande motrice sur l’interaction entre deux de ces mécanismes inhibiteurs l’un à longue latence, la LICI, l’autre à courte latence, la SICI. Enfin nous avons souhaité évaluer le décours temporel de ces mécanismes dans un cadre pathologique tâche-dépendant: la crampe de l’écrivain. Pour cela, nous avons utilisé la technique d’electromyographie de surface pour enregistrer les potentiels moteurs évoqués par la Stimulation Magnétique Transcrânienne. Nous avons mis en évidence une modulation tâche-dépendante de la LICI. Par rapport à la tâche d’abduction simple, la LICI s’estompait plus tôt lors de la tâche de pince pouce-index, traduisant une désinhibition plus précoce lors d’un mouvement plus complexe. Nous avons observé, et ce pour la première fois dans la littérature, une phase de facilitation nette qui suivait cette désinhibition, et qui était absente lorsque le muscle était au repos. Ces résultats sont également visibles dans un muscle voisin du FDI, non engagé dans la tâche; cela suggère que les mécanismes à l’origine de la facilitation sont impliqués dans l’activité volontaire sans spécificité topographique. L’interaction entre la LICI et la SICI n’a pas été modifiée par la tâche effectuée, laissant penser qu’elle n’est pas impliquée dans les changements d’excitabilité tâche-dépendants. Enfin, il apparaît que la désinhibition est retardée chez les sujets dystoniques quand le muscle est engagé dans un mouvement complexe de pince pouce-index mais pas dans une tâche simple d’abduction de l’index en comparaison à des sujets contrôles. Ces résultats illustrent le fait que lors d’un mouvement plus complexe, l’efficacité des circuits inhibiteurs du cortex moteur primaire est modifiée, ce qui permet de réguler l’activité des cellules CM, afin d’adapter la commande motrice au mouvement souhaité. Le fait que cette désinhibition soit retardée dans une tâche complexe (proche de la tâche affectée) mais pas dans une tâche simple chez les patients atteints d’une crampe de l’écrivain suggère que les mécanismes à l’origine de la désinhibition pourraient participer aux troubles moteurs qui caractérisent la maladie. / Movements are evoked by muscles contractions whose spatial organization is mediated by both spinal and cortical components. It is important to investigate the underlying circuitry of movements to extend our knowledge on how voluntary movement are controlled and to better understand the pathophysiology of movements disorders. The spinal alpha motoneurons innervating distal muscles are controlled at least in parts by corticomotoneuronal neurons located in the motor cortical areas. Among them, the primary motor cortex is considered as a key structure, performing a complex integration of multi-regional influences leading to appropriate motor behaviors. Axons from corticomotoneuronal (CM) cells of the primary motor cortex reach the spinal cord via descending motor pathway. CM neurons are influenced by local or distant, inhibitory and excitatory components which determine the balance of excitability. The aim of this thesis was to explore changes of some of the excitatory and inhibitory mechanisms of motor cortex as a function of the task being performed. We assessed the time course of Long-interval Intracortical Inhibition (LICI), Late Cortical Disinhibition (LCD) and Long interval Intracortical Facilitation (LICF), which are mechanisms that potentially act to modulate the output of CM controlling the first dorsal interosseus (FDI) muscle. We compared three conditions : index finger abduction (a simple but not natural task), precision grip between index and thumb ( amore natural and complex task), and rest. We also evaluated the effect of task on interaction between LICI and Short Interval Intracortical Inhibition (SICI). Finally, we assessed the time course of LICI in patients suffering from writer’s cramp. For this purpose, we used surface electromyography to record motor potentials evoked by Transcranial Magnetic Stimulation.We showed a task-dependent change in late inhibitory and disinhibitory components. Compared with abduction task, the LICI induced during precision grip was shorter, suggesting an early disinhibition in more complex task. The disinhibition was followed by a period of facilitation only during the active tasks, i.e. facilitation was not observed when all muscles were at restat rest. However, long interval intracortical facilitation can be observed in a muscle at rest not engaged in an active task if a neighboring muscle is activated. It is therefore likely that mechanisms underlying facilitation are associated with voluntary contraction albeit with lack of topographic specificity. Interaction between LICI and SICI was not modified between tasks, suggesting that it was not involved in task-dependent changes of cortical excitability. Lastly, disinhibition was shown to be delayed in dystonic patients when the FDI was actively engaged in a precision grip but not in index abduction, compared with control subjects. An explanation might be that mechanisms underlying disinhibition are impaired in thumb-index precision grip (a task similar to that inducing unwanted contractions in writer’s cramp). Task-specidic disruption of LICI and late cortical disinhibition may therefore be at least in part responsible for pathophysiology of dystonia. It is likely that during complex task, the efficacy of LICI, and more generally of motor cortex inhibitory mechanisms, is modified to allow adaptation of CM neurons activity to the functional requirements of the motor task being performed.
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Análise longitudinal multinível da morbidade por doenças cardiovasculares em idosos do município de São Paulo / Multilevel longitudinal analysis of morbidity from cardiovascular disease among elderly residents of São Paulo, BrazilMassa, Kaio Henrique Correa 07 March 2018 (has links)
A morbidade por doenças cardiovasculares (DCV) é uma preocupação crescente em Saúde Pública. Um aumento na carga das DCV tem sido recentemente observado, principalmente em países de baixa e média renda, reflexo do aumento da expectativa de vida e do maior tempo de exposição aos fatores risco para as doenças crônicas. O aumento no número de anos vividos com alguma doença crônica tem se tornado uma das principais preocupações em saúde pública, destacando-se, nesse contexto, as doenças cardiovasculares, principal responsável por anos de vida perdidos ajustados por incapacidade em idosos. Dessa forma, a avaliação da carga das doenças crônicas na população, bem como o conhecimento de seus determinantes, representa um importante campo de estudo em Saúde Pública e no planejamento da atenção em saúde. Entretanto, estudos que analisaram tanto a mudança na prevalência de DCV na última década, como os determinantes individuais e contextuais das doenças cardiovasculares em idosos ainda são escassos no Brasil. Esta tese será apresentada sob a forma de três artigos científicos. O primeiro analisou o efeito dos determinantes individuais e contextuais na morbidade por DCV em idosos residentes do município de São Paulo em 2010. Foi observada uma maior presença de DCV entre os idosos que residiam em áreas com desigualdade de renda média-baixa (OR=1,35 IC95 por cento=1,15-1,59), média-alta (OR=2,71 IC95 por cento=2,18-3,36) e alta (OR=1,43 IC95 por cento=1,14-1,79), comparada ao nível mais baixo de desigualdade. Em relação às áreas com menor área verde por habitante, viver em áreas com maior cobertura vegetal esteve significantemente associado a uma menor chance de presença de DCV, mesmo após o ajuste estatístico para os fatores individuais e contextuais. O segundo artigo analisou a mudança na prevalência de DCV entre 2000 e 2010 e sua associação com os fatores socioeconômicos e fatores de risco em idosos. A prevalência de DCV em idosos foi igual a 17,9 por cento em 2000, 22,2 por cento em 2006 e 22,9 por cento em 2010. Em relação ao ano 2000, foi observado um aumento significativo da presença de DCV em 2006 (OR=3,20 IC95 por cento=1,93-5,31) e 2010 (OR=2,98 IC95 por cento=1,51-5,89). A presença de DCV também apresentou associação com maior faixa etária, histórico de tabagismo e presença de diabetes e hipertensão arterial, sendo observada uma associação inversa entre a presença de DCV e a ingestão de álcool. O terceiro artigo analisou a associação entre a força de preensão manual e a morbidade por doença cardiovascular em idosos. Foi observado que uma maior força de preensão manual esteve significativamente associada a uma menor presença de DCV em idosos (OR=0,47 IC95 por cento = 0,24 0,91), mesmo após o controle para as características individuais. / Cardiovascular disease morbidity (CVD) is a growing concern in Public Health. An increase in the burden of CVD has been recently observed, especially in low- and middle-income countries, due to increases in life expectancy and the longer exposure period to risk factors of chronic diseases. The increase of total years lived with a chronic disease is now considered as one of the main public health concerns, especially regarding cardiovascular diseases, the highest contributor to disability-adjusted life years among the elderly. Therefore, the assessment of the total burden of chronic diseases in the population and the identification of its determinants represents an important area of concern in Public Health and healthcare policies. However, studies that have analyzed both the evolution of the CVD prevalence in the last decade and the individual and contextual determinants of cardiovascular diseases among the elderly are still scarce in Brazil. This thesis is presented in the form of three papers. The first one analyzed the effect of individual and contextual determinants of morbidity of CVD in elderly residents of Sao Paulo, Brazil, in 2010. In comparison to elderly residents in areas with the lowest level of income inequality, higher odds of CVD presence was observed among those living in areas in the mediumlow (OR=1.35, 95 per cent CI 1.15 to 1.59), mediumhigh (OR=2.71, 95 per cent CI 2.18 to 3.36) and high (OR=1.43, 95 per cent CI 1.14 to 1.79) quartiles of income inequality. Regarding green spaces, those who live in areas with highest levels of vegetation coverage had a significantly lower risk of CVD, even after controlling for individual and contextual factors. The second paper analyzed the differences in the prevalence of CVD between 2000 and 2010 and its association with socioeconomic factors and risk factors among the elderly. The prevalence of CVD in the elderly was estimated to be 17.9 per cent in 2000, 22.2 per cent in 2006 and 22.9 per cent in 2010. Regarding the prevalence observed in 2000, there was a significant increase in presence of CVD in 2006 (OR = 3.20 95 per centCI = 1.93 to 5.31) and 2010 (OR = 2.98 95 per centCI = 1.51 to 5.89). The presence of CVD was also associated with older age, smoking history, presence of diabetes and hypertension, and an inverse association was observed between CVD presence and alcohol intake. The third paper analyzed the association between grip strength and cardiovascular disease morbidity in the elderly. A significantly lower presence of CVD was observed among the elderly with higher grip strength (OR = 0.47 95 per centCI = 0.24 to 0.91), even after controlling for individual characteristics.
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L'impact d'une intervention nutritionelle chez les receveurs de cellules souches hématopoïétiques : résultats d'un essai contrôlé randomisé / The impact of counseling on nutritional status and quality of life of Hematopoietic Stem Cell recipients : results of a randomized controlled trialJabbour, Jana 29 June 2018 (has links)
Contexte :Le conditionnement précédant la greffe de cellules souches hématopoïétiques (CSH) a été associé avec des taux élevés de malnutrition meme à 100 jours après la greffe. Objectif: Cette étude évalua l'impact du conseil nutritionel fournie à la sortie de l'hôpital sur l'état nutritionnel,100 jours après la greffe de CSH (dit T4).Conception: Il s'agissait d'un essai contrôlé randomisé monocentrique. Les patients adultes étaient randomisés à un groupe témoin (GT) recevant des soins habituels et un groupe d'intervention (GI) recevant des conseils nutritionnels mensuels après la sortie de l’hôpital. Le résultat principal était le score de l'évaluation globale subjective générée par le patient (PGSGA) à T4. La malnutrition était évalué aussi par le score de la société américaine de nutrition parentérale et entérale/Académie de nutrition et diététique (AND-ASPEN).Résultats: 52 participants ont été randomisés (août 2016 jusqu'en août 2017) et 46 ont été analysés [65% d'hommes, 63% de greffes autologues, GI (n = 22), GT (n = 24)]. Les deux groupes etaient comparable au moment de randomization.A T4, le pourcentage de patients bien nourris n'était pas significativement différent entre les groupes selon le PGSGA (72% GI vs 43% GT, p = 0,063). Le pourcentage de patients bien nourris selon AND-ASPEN s'est améliorré à T4 dans le GI (50% vs 14%, p = 0,02) et non pas dans le GT par rapport aux valeurs d'admission. A T4, le GI avait un apport de protéines et de calories plus élevé que le GT(p<0.05).Conclusion:Le conseil nutritionnel après la greffe de CSH a amélioré l’apport en protéines et calories ainsi que le score AND-ASPEN mais non pas le score PGSGA. / Background: Conditioning preceding Hematopoietic Stem Cell Transplantation (HSCT) has been associated with elevated rates of malnutrition until 100 days post HSCT.Objective: This study aimed to assess the impact of nutritional counseling provided at hospital discharge on nutritional status 100 days post HSCT (defined as T4). Design: This was a single center randomized controlled trial among adult HSCT patients. Around discharge from the hospital, recruited patients were randomized to a Control Group (CG) receiving usual care and to an Intervention Group (IG) receiving nutritional counseling on a monthly basis post discharge.The primary outcome was the Patient Generated Subjective Global Assessment (PGSGA) scores at T4. Malnutrition was also assessed though the American Society for Parenteral and Enteral Nutrition/ Academy of Nutrition and Dietetics malnutrition score.Results: 52 participants were randomized (August 2016 until August 2017) and 46 were analyzed [65% males, 63% autologous HSCT, IG (n=22), CG (n=24)]. Groups were comparable at randomization. At T4, the percent of well-nourished patients was not significantly different between groups when assessed via PGSGA (72% IG vs. 43% CG, p=0.063).The percent of wellnourished patients as per AND-ASPEN criteria improved in IG at T4 (14% vs. 50%, p=0.02) and remained the same in CG (48% vs. 50%, p=1) compared to admission values. IG had higher protein and caloric intake (p<0.05). Conclusion:Nutritional counseling post HSCT improved patients’ protein and caloric intake and AND-ASPEN score but did not significantly improve PGSGA score.
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Les métaux lourds dans la glace du Groenland datant de l'époque gréco-romaine et du dernier cycle climatique : contribution anthropique et naturelleHong, Sungmin 16 October 1995 (has links) (PDF)
pas de résumé
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Tactile Sensory Control of Dexterous Manipulation in HumansBirznieks, Ingvars January 2003 (has links)
During dexterous manipulation with the fingertips, forces are applied to objects' surfaces. To achieve grasp stability, these forces must be appropriate given the properties of the objects and the skin of the fingertips, and the nature of the task. It has been demonstrated that tactile sensors in the fingertips provide crucial information about both object properties and mechanical events critical for the control of fingertip forces, while in certain tasks vision may also contribute to predictions of required fingertip actions. This thesis focuses on two specific aspects of the sensory control of manipulation: (i) how individual fingers are controlled for grasp stability when people restrain objects subjected to unpredictable forces tangential to the grasped surfaces, and (ii) how tactile sensors in the fingertips encode direction of fingertip forces and shape of surfaces contacted by the fingertips. When restraining objects with two fingers, subjects adjust the fingertip forces to the local friction at each digit-object interface for grasp stability. This is accomplished primarily by partitioning the tangential force between the digits in a way that reflects the local friction whereas the normal forces at the involved digits are scaled by the average friction and the total load. The neural control mechanisms in this task rely on tactile information pertaining to both the friction at each digit-object interface and the development of tangential load. Moreover, these mechanisms controlled the force application at individual digits while at the same time integrating sensory inputs from all digits involved in the task. Microneurographical recordings in awake humans shows that most SA-I, SA-II and FA-I sensors in the distal phalanx are excited when forces similar to those observed during actual manipulation are applied to the fingertip. Moreover, the direction of the fingertip force influences the impulse rates in most afferents and their responses are broadly tuned to a preferred direction. The preferred direction varies among the afferents and, accordingly, ensembles of afferents can encode the direction of fingertip forces. The local curvature of the object in contact with the fingertip also influenced the impulse rates in most afferents, providing a curvature contrast signals within the afferent populations. Marked interactions were observed in the afferents' responses to object curvature and force direction. Similar findings were obtained for the onset latency in individual afferents. Accordingly, for ensembles of afferents, the order by which individual afferents initially discharge to fingertip events effectively represents parameters of fingertip stimulation. This neural code probably represents the fastest possible code for transmission of parameters of fingertip stimuli to the CNS.
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Längdmätning i engreppsskördareHjerpe, Stefan January 2007 (has links)
Detta examensarbete har gjorts på uppdrag av SP Maskiner AB och berör längdmätningsenheten på skördaraggregatet SP451LF. Pulsgivaren i den befintliga längdmätningen anses inte nå en acceptabel livslängd och därför skall ett sensorlager prövas som ersättare. Uppdraget består i att söka ett lämpligt sensorlager, dimensionera en komplett mäthjulslagring samt att ta fram ett konstruktionsförslag till prototyp på längdmätning. Arbetet begränsas av att den omkonstruerade längdmätningen skall passa på SP451LF aggregatet. Det betyder att längdmätningens infästning mot aggregatet inte får förändras och dess yttermått måste hållas inom de gränser som aggregatets chassi tillåter. / This diploma work has been done on commission by SP Maskiner AB and affects the length meter unit on the single-grip harvester SP451LF. The pulse encoder in the present length meter has too short duration why a sensor-bearing will be tested as replacement. The tasks are to find a suitable sensor-bearing unit, to dimension a complete measuring wheel bearing and create a construction proposal for a prototype of a length meter. The diploma work is limited by the fact that the reworked length meter has to fit into the SP451LF harvester. That means that the length meter’s contact points on the harvester’s frame are not to be altered.
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