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Recently, the need for high power, high frequency devices continues to grow with the increase in wireless communication, radar systems, HDTV, digital communication, and other military application of the RF spectrum. Traditionally when higher power is needed, one needs to either combine the output power of multiple devices or use vacuum tubes, which are still uncontested at very high power levels, capable of up to a few hundred kilowatts at 5 GHz [11]. But wide band gap semiconductor devices capable of competing in this application. Moreover, the static induction transistor (SIT) in silicon carbide can provide very high total power at microwave frequency. This is due to the vertical structure of the SIT which consists of a vertical channel that is defined by a mesa with gate electrodes of the Schottky type to control the current between a top side source contact and a drain contact on the backside of the wafer. This thesis demonstrates that through careful modeling by means of simulations and inclusion of all significant device physics, good agreement is reached between theoretical prediction and simulation results. It is shown in particular that by careful choice of the device critical parameters, such as mesa width, gate length, and contact resistance, SIT should be able to obtain cut-off frequency up to 42 GHz and shown temperature simulation results of SIT.

ABSTRACT The purpose of this thesis is to examine the Sit-in movement in Chattanooga, Tennessee during the early 1960s in the context of a perpetuating tradition of protest in the African American community spanning more than a century. The study will also illustrate how it was a unique episode in the annals of the Civil Rights Movement in that it was strictly orchestrated by high school students without the input or support of adults, yet it has largely been neglected by historians. The research conducted includes oral histories, newspaper clippings, private manuscript collections, books, videos, and periodicals which provide great insight into the minds, motives, and methods of those involved. The study also depicts the galvanizing spirit, ignited by the students, which compelled the community to act and resulted in monumental social changes.

The Sit-to-Stand (STS) transition is a voluntary daily activity that consists of rising from a sitting position to a standing position, an activity that is typically performed by a person several times a day. To undertake the activity successfully requires the coordination of the body limbs in order to transfer the body weight between the sitting and standing positions, maintaining the balance, in order to avoid a fall. A biomechanical analysis of the STS transition provides useful information about the motor ability and control strategy of a person and as such, it is commonly employed to assess functional performance, and as an indicator of lower limb strength in the elderly and in people with disabling diseases. The aim of the work described in this thesis was to investigate and analyse the STS transition in two groups of healthy subjects, a cohort (n=10) of younger adult participants (age range 28±2 years) and a cohort (n=10) of older adult participants (age range 56±8 years), in order to identify the differences in the performances within and between the two groups when the STS transition was undertaken at different speeds. The two groups of participants performed STS transition trials at three, different, self-selected speeds (normal, slow and fast) during which data was recorded from a caption systems, consisting of a set of six infrared-cameras and two force plates. The in-vivo data obtained was applied to a link segment biomechanical model enabling the kinematic contribution of the major body segments to the STS activity to be determined for each participant. A principal component analysis (PCA) was undertaken to identify any aggregate and segmental differences in the STS transition performance between speeds. In addition, a kinetic analysis was performed to determine the torque and power contributions of the lower limb joints during the STS transition. The results from the analysis showed that younger and older participants performed the STS transition with a similar pattern, but they used different strategies to ascend according to the speed at which the activity was being performed. The younger participants used the same strategy at slow speed than the older participants used at slow and normal speeds. Likewise, the younger participants used the same strategy at normal and fast speeds as the older participants used at fast speed. From the segmental analysis it was found that the upper-body and pelvis segments presented the larger variability than the other segments. From the joint analysis, the knee and hip joints were identified as the joints that provide the greatest contribution to the STS transition as they generated most of the power and torque required for the activity. The results obtained and the methodology developed could help clinicians with the diagnosis, planning and selection of treatment for patients with a lack of mobility. This type of analysis may also find application in fields such as robotics, ergonomics and sports training.

The sit-to-stand (STS) is a multi-articular movement of daily living that requires significantly higher knee extensor (KE) efforts compared to ankle and hip musculature, which approach near maximal levels in older adults populations. As well, fatigue may develop more readily with repetitive actions. Consequently, it is understandable how KE strength reserves have been previously correlated with both functional independence and STS strategy characteristics in older persons, and why STS capacity is a significant predictor of disability. However, it is still unclear why compensatory movement strategies manifest when rising from a seated position, and how this may be influenced by aging. The purpose of this thesis compilation was to evaluate alterations in muscular contributions at the ankle, knee, and hip, in relation to STS performance strategies in young and older adults either: a) with repetitive multi-joint STS exercise or b) before and after isolated fatigue of KE musculature. Results showed that aging caused a redistribution of joint torques when ascending from a seated position, and was associated with significantly higher quadriceps muscular efforts in older persons in comparison to their younger counterparts. In contrast, young and older adults exhibited similar compensatory movement and loading strategies during repetitive STS exercise, which appeared to be limited by the ability to sustain KE force output. In turn, lower KE strength reserves of older persons were responsible for their disproportionately higher quadriceps efforts and reduced STS capacities. Young and older persons also appeared to employ motor strategies to compensate for reduced KE force output via increased contribution of the biarticular rectus femoris within the quadriceps KE synergy, as well as through increases in the initially less active ankle plantar flexor and hip extensor musculature. Older adults may benefit from strengthening of thigh extensor musculature to maintain or improve their strength reserves to promote independent living.

Att utöva fysiska aktiviteter ska vara möjligt för alla.Genom parasporten, som är sporter anpassade förpersoner med olika funktionsnedsättningar, görs dettamöjligt för alla, oavsett vilka fysiska förutsättningar manhar. Cross-country sitskiing är en gren inom parasportensom växer mer och mer i antalet utövare. Vid utövandetav Cross-country sitskiing sitter åkaren i en typ av kälkesom kallas sitski. Denna är anpassad efter individen ochkan därför se mycket olika ut. Vid tävling är det viktigtatt utrustningen passar bra och håller en låg vikt.Med syftet att förbättra prestationen för en åkare, samtgöra det enklare för andra att göra detsamma, gav SportsTech Research Centre rapportförfattarna i uppdrag attutvärdera och utveckla en sitskiåkares nuvarande sitski.Målet med arbetet är att ta fram ett produktionsunderlagför en ny sitski utifrån åkarens önskemål.Arbetet har skett genom de fyra faserna förstudie,konceptgenerering, konceptval och detaljkonstruktion. Iförstudien undersöktes marknaden i stort och enförståelse för sporten och sitskin skapades. Vidare ikonceptgenereringen undersöktes mer detaljer av desitskis som redan finns på marknaden och möjligalösningar började tas fram, dessa kombinerades till olikakoncept. I konceptvalet kontrollerades koncepten ochjämfördes mot satta krav samt mot varandra. De tvåkoncepten som togs vidare förädlades för att kunna väljaett slutgiltigt koncept. Detta koncept togs vidare till densista fasen, detaljkonstruktion, där det bearbetadesytterligare för att sedan kontrolleras med FEM-analyser.Resultatet gav en ny sitski med väldigt likvärdig viktmot den tidigare. Dock har den nya en öppnare vinkel ihöften, då detta var önskat för att försöka ökaåkeffektiviteten. Den nya sitskin är även merergonomisk än den tidigare, har bättre passform och ärmer personanpassad. / Performing physical activities should be possible foreveryone. Through parasport, i.e. sports adapted forpeople with disabilities, this becomes possible foreveryone - despite differences in physical conditions.Cross country sit-skiing is a competitive sport in theparasport community which has been growing a lot interms of number of athletes. Performing Cross countrysit-skiing, the skier sits in a type of sledge, which is calleda sit-ski. The sit-ski is usually fitted after each individualand can therefore have big differences in appearance andfunctionality. In competitive sports, it is important tohave well-adjusted equipment that also holds a lowweight.With the purpose to improve one skiers performancewhilst also making it possible for others to do the same,the task given by Sports Tech Research Centre was toevaluate and develop a sit-ski used by an athlete incompetition. The aim being to produce a documentationof production for a new sit-ski, adjusted to the skierspreferences.The work has gone through the four phases: prestudy,concept generation, concept selection and detail design.The prestudy analyzed the market in general and anunderstanding for the sport and sit-skis generally wasestablished. The concept generation consisted ofexamining details in sit-skis already on the market, andbeginning to produce possible solutions, which werecombined into different concepts. In the conceptselection, the concepts were checked and compared tothe requirements and to each other. The two conceptswere further refined, to finally be able choose a final one.The final concept was developed further in the detaildesign phase and checked with further FEM-analysis.The result being an improved sit-ski, although with aweight comparable to the old one, a wider angle at thehip to hopefully improve skiing efficiency. The new sit-ski is more ergonomic than the original one, better fittedand more personalized. / <p>Betyg 2020-07-08/2020-08-13</p>

Background: Sit-to-stand is a challenging task as it requires the transition from a large 3-point base of support to a small 2-point base of support while simultaneously controlling anteroposterior and vertical body acceleration. Age-related morphological changes in both the visual and vestibular system could impair the ability to extract and interpret sensory information necessary for motor control in older adults, which can increase instability and the risk of falls. The purpose of this study is to understand the effects of aging on visual-vestibular interaction for maintaining stability during sit-to-stand. Methods: Fifteen younger (age=22.5±1.1) and fifteen older (age=73.9±5.3) healthy adults were asked to stand from a sitting position as quickly as possible. Vestibular input was manipulated using percutaneous bipolar galvanic vestibular stimulation where threshold intensity was individually calculated for each participant during quiet stance with eyes closed. Galvanic vestibular stimulation was applied at both threshold (1xGVS) and 2-times the participant’s threshold intensity (2xGVS). Visual conditions included eyes opened, wearing custom-made vision blurring goggles, or eyes closed. Outcome measures included a global measure of performance (transition phase duration), mediolateral stability (peak-to-peak trunk roll angle, mediolateral center of mass displacement, mediolateral center of pressure displacement) and anteroposterior stability (peak braking force, peak-to-peak trunk pitch angle, and peak anteroposterior center of mass velocity). Results: When vision was suboptimal (blurring goggles), older adults had significantly longer transition phase duration than younger adults (p<0.05). Older adults demonstrated greater mediolateral instability than younger adults. When vision was absent, trunk roll angle was significantly greater with 1xGVS than 2xGVS (p<0.05). Mediolateral center of mass displacement was greater when vision was absent than when vision was available, irrespective of age (p<0.05). No effects of age, vision or galvanic vestibular stimulation were seen in peak braking force, trunk pitch angle, and peak anteroposterior center of mass velocity (p>0.05). Conclusion: Regardless of age, visual inputs were more critical to maintain stability during sit-to-stand than vestibular inputs. Differences between younger adults and older adults were only seen in the mediolateral direction. Despite having greater mediolateral instability, older adults utilized similar strategies as younger adults to overcome sensory perturbations during sit-to-stand. / Thesis (Master, Rehabilitation Science) -- Queen's University, 2013-09-20 23:22:16.695

Hållbarhetsämnet är mer aktuellt än någonsin i dagens samhälle och diskuteras i allt fler sammanhang och kontexter, men ur en jobbsökarkontext är området relativt outforskat. Den tidigare forskning som finns inom ämnet görs ur olika perspektiv och kommer till olika slutsatser, varför ett behov av en mer djupgående analys finns. För att uppnå denna djupare förståelse av ämnet valde vi att genomföra en kvalitativ undersökning för att identifiera huruvida det bland jobbsökare finns ett samband mellan önskan att kunna identifiera sig med en potentiell framtida arbetsgivare och intresset för dennes hållbarhetsengagemang.Genom litteraturgenomgång tas en teoretisk referensram för studien fram, där olika för studien relevanta ämnesområden tas fram och sammanställs. Den teoretiska referensramen innefattar olika teorier kring identifiering, såsom social identifieringsteori och organisationsidentifiering, men även teori kring arbetsgivarattraktivitet, greenwashing och företags hållbarhetsengagemang i termer av corporate social responsibility – CSR. Den teoretiska referensramen leder fram till en föreslagen modell, vilken sammankopplar de olika utvalda teorierna och har för avsikt att fungera som ett verktyg för kategorisering av jobbsökare baserat på hur dessa ställer sig till de olika ämnesområden som den föreslagna modellen berör.Den teoretiska referensramen och dess modell utgör basen för de semistrukturerade intervjuer som genomförs med tio respondenter, de samtliga olika ämnesområdena ur den föreslagna modellen diskuteras för att utgöra basen för studiens analys. Efter kodning av intervjuerna identifieras stora likheter bland många respondenter, varför den föreslagna modellens applicerbarhet blir låg. Istället tas en fyrfältsmodell fram, vilken tydliggör tre olika kluster bland respondenterna baserat på deras svar och attityder. Klustren baseras på till vilken grad man som jobbsökare önskar identifiera sig med potentiell framtida arbetsgivare samt till vilken grad företags CSR-engagemang beaktas vid jobbsökandet. Majoriteten av respondenterna placeras i det såkallade medelklustret, där identifieringen med potentiell arbetsgivare anses viktig men beaktandet av CSR-engagemanget är lågt. Ytterligheterna utgörs av ett lägre respektive högre kluster, där det lägre klustret visar ett ointresse för båda faktorerna, medans det högre klustret visar på ett förhållandevis högt intresse för båda. Potentiell framtida arbetsgivares CSR-engagemang tycks alltså inte vara något som är av högre betydelse för jobbsökande, men att kunna identifiera sig med denne är för majoriteten viktigt. Ingen är dock perfekt och även de respondenter som kategoriserades enligt det högre klustret gav, liksom de flesta övriga respondenter, uttryck för att man i en desperat situation sannolikt skulle kunna tänka sig att ta ett jobb vid ett företag man egentligen inte hade velat vara anställd i. Intresset för potentiell arbetsgivares CSR-engagemang tycks alltså vara en effekt av en stark identifiering med denne. Vad vi kunde se var också att flera av jobbsökarna inte anser sig befinna i en situation där det är rättfärdigat att ha förväntningar eller krav på arbetsgivares hållbarhetsengagemang, utan ger uttryck för att det eventuell är något som kan komma att beaktas till högre grad längre fram i karriären. Om man får jobb vid ett företag med ett bra CSR-engagemang ses det snarare som en bonus än något man förväntar sig.Studien bidrar med en djupare insikt kring identifiering med potentiell arbetsgivare och synen på dennes CSR-engagemang i en jobbsökarsituation. Den fyrfältsmodell som tas fram i analysen fungerar som ett verktyg för kategorisering av jobbsökare baserat på dennes attityder i ämnet och kan appliceras även i andra kontexter än studiens urval bestående av civilekonomstudenter på väg ut i arbetslivet.

During pregnancy the female body must accommodate the enlarging gravid uterus and increased mass. Therefore the maternal musculoskeletal system is required to adapt in both morphology and functional workload. After childbirth there is a rapid change in both mass and dimensions, requiring further adaptations. The objectives of the study were to investigate seated and standing upper body posture, the kinematics of seated and standing trunk motion, and the three dimensional kinematics and kinetics during rising to stand from a chair, as pregnancy progressed and in the early post-birth period. Nine maternal subjects (aged 28 to 40 years) were tested at less than 16 weeks, 24 weeks, 30 weeks, 38 weeks gestation and at 8 weeks postbirth. The subjects, fitted with 37 retroreflective markers, were filmed during upright sitting, quiet standing, and four trials each of maximum seated and standing trunk forward flexion, side to side flexion and during maximum seated axial rotation. Three trials each of constrained and free rising to stand from a height adjustable stool and with each foot placed on a forceplate were also recorded. An eight-camera motion analysis system was used to record movements of the body segments and synchronised force plate variables in three dimensions. Motion of the ankle, knee and hip joints, pelvic, thoracic and head segments and the thoracolumbar and cervicothoracic spines and shoulder joints were investigated. Twelve nulliparous subjects (aged 21 to 35 years) were used as controls to provide standard descriptive data and to investigate the consistency of the selected biomechanical variables with repeated testing. A repeated measures ANOVA was used to investigate the possibility of linear and quadratic trends showing systematic changes within the maternal group, over the four test sessions during pregnancy for each variable. Two tailed Student t-tests were used to compare the maternal postbirth variable results with the control group. There was no significant effect of pregnancy on the upper body posture during upright sitting and quiet standing. Postbirth, the pelvic segment had a smaller anterior orientation and the thoracolumbar spine was less extended, indicating a flatter spinal curve. The maternal subjects were similar to the control subjects in early pregnancy and postbirth for trunk segment motions during seated and standing forward flexion and side to side flexion and seated axial rotation. Strategies, such as increasing the width of the base of support and reducing obstruction to movements from other body parts, were used in late pregnancy in attempts to minimise the effects of increased trunk mass and circumference. For seated and standing side to side flexion, the strategies were successful and no significant decreases in range of motion were seen. For seated and standing forward flexion and seated axial rotation, motion of the thoracic segment and the thoracolumbar spine were significantly reduced, although movement of the pelvis was less affected. In early pregnancy and postbirth the kinematics and kinetics of the lower limbs and upper body segment kinematics during constrained and free rising were generally similar to the control subjects. As pregnancy progressed there were increases in mass and dimensions of body segments. The effect of increased mass was seen in increased ground reaction forces and sagittal plane lower limb joint external moments. An increased base of support width was found in association with an increased lateral ground reaction force and ankle inversion moment from each foot, which would move the body centre of mass medially. There was little change in the three dimensional kinematics of the thoracolumbar and cervicothoracic spine, although the contribution of the upper body segments differed for each rise condition. There were also few significant changes in the displacement of the ankle, knee and hip, and the angular velocity of ankle and knee joints. The maternal subjects were thus able to flex the upper body forward, raise the body and maintain stability as pregnancy progressed, regardless of whether the rise to stand was performed in a natural manner or under constrained conditions. The overall results show that, contrary to expectations as pregnancy progressed, maternal subjects minimised propulsion rather than increasing it to overcome the increased mass and possibly limited trunk flexion. A fear of postural instability may have made the subjects more cautious and as they were able to adequately flex the trunk forward, propulsion was minimised in favour of maintaining upright terminal balance.

<p>Tillfälliga anställningar har de senaste 20 åren blivit allt vanligare på</p><p>arbetsmarknaden till följd av större konkurrens och arbetsgivarens</p><p>krav på flexibilitet. Tidigare studier visar att tillfälligt anställda känner</p><p>ett visst utanförskap och missnöje. Huvudsyftet med studien är därför</p><p>att, med stöd av Social Identity Theory och Parkers modell (2003) om</p><p>psykologiskt klimat, testa om tillfälligt anställda upplever sämre</p><p>arbetsgruppssammanhållning och arbetsattityder än fast anställda.</p><p>Enkäter skickades ut till 796 sjuksköterskor och sedan gjordes</p><p>beräkningar med t-tester för oberoende stickprov. Resultatet</p><p>bekräftade tidigare teori om sambandet mellan psykologiskt klimat och</p><p>arbetsattityder dvs. ju bättre arbetsgruppssammanhållning desto bättre</p><p>arbetsattityder. Däremot fanns ingen signifikant skillnad mellan</p><p>grupperna i upplevelse av arbetsgruppssammanhållning och i</p><p>uppvisande av arbetsattityder. Framtida forskning bör ta hänsyn till</p><p>heterogeniteten i gruppen tillfälligt anställda.</p>