• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 172
  • 84
  • 39
  • 25
  • 15
  • 9
  • 7
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 443
  • 46
  • 41
  • 37
  • 36
  • 36
  • 36
  • 33
  • 31
  • 30
  • 28
  • 27
  • 26
  • 26
  • 26
  • 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.
81

Reflexarmband : Ett koncept för att få fler fotgängare att vilja synas i mörkertrafiken

Hägg, Elaine January 2019 (has links)
Det här examensarbetet behandlar synlighet i mörkertrafiken hos fotgängare. Syftet har varit att få fler fotgängare att synas i mörkertrafiken och målet har varit att hitta ett alternativ till det som finns på marknaden idag, som gör att man som fotgängare vill syns i trafiken när det är mörkt. Eftersom reflexer eller ljusreflekterande material i olika former avser en stor del av marknaden har mitt arbete utgått från denna befintliga reflexlösning och sen utvecklats till en ny form med ett hållbart affärstänk.   Research har gjorts för att få en förståelse för hur reflexer fungerar och hur ett alternativ kan utvecklas som gör att användaren kommer ihåg vikten av att använda reflex samtidigt som man också vill ha det på sig. Researcharbetet har delats in i två faser där den ena fasen har behandlat vad en reflex är och hur den fungerar medan den andra har handlat om att förstå användaren och användarupplevelsen. Det är ett arbete som har genomförts i en designprocess där användarperspektivet har fått ett stort utrymme i processen i form av både kvantitativa användarundersökningar och kvalitativa intervjuer och samtal i en fokusgrupp. Fokus har legat på attityden till reflexer, om man använder det, hur man tänker och vilken sorts reflex man använder samt hur man i övrigt tänker när man klär sig på vinterhalvåret när man är ute och går.   För att hitta ett alternativ till dagens reflexer har skapandet av idéer tagit upp en stor del av designprocessen. En omfattande idégenerering har gjorts i form av både skisser på papper och fysiska modeller för att få en uppfattning om funktion och volym. Dessa skisser har sedan utvecklats till flera koncept som till slut har blivit ett slutgiltigt koncept.   I detta examensarbete har jag alltså utvecklat ett koncept som skapar ett hållbart värde där reflexen kan bytas ut varje år med en återanvändningsbar grund, i form av en armbandskedja. Detta reflexarmband har presenterats i form av illustrationer, rendering och i en skalmodell för att visualisera konceptet.
82

Estudo do desenvolvimento somático e sensório-motor de Rattus norvegicus machos e fêmeas oriundos de mães tratadas na prenhez com sertralina: análise da distribuição dos neurônios serotoninérgicos nos núcleos da rafe. / Study of development and somatic sensorimotor of Rattus norvegicus males and females from mothers treated with sertraline in pregnancy: analysis of the distribution of serotonergic neurons in the raphe nuclei.

Vasconcelos, Renata Gonçalves de 29 August 2008 (has links)
Analisamos o efeito do sistema serotoninérgico no desenvolvimento somático e na ontogênese de reflexos dos filhotes, cujas mães foram submetidas a tratamento farmacológico durante a prenhez. Ratas wistar prenhas foram divididas em dois grupos (N=11): Grupo AD, tratadas com água destilada, Grupo Sert, tratadas com sertralina 30mg/kg, 0,5mL/100g, s.c. Um dia após o parto 8 neonatos (4 machos e 4 fêmeas) foram mantidos com suas mães do 1º ao 21º dia pós-natal. O investigador cego avaliou o crescimento somático, características físicas e maturação de reflexos. Aos 22 e 60 dias de idade os encéfalos foram processados com técnicas de imunoistoquímica contra 5-HT. O grupo Sert, macho ou fêmea, apresentou atraso no crescimento somático e na maturação de alguns reflexos. A quantidade de neurônios 5-HT-IR foi alterada nos núcleos da rafe nos ratos aos 22 dias de idade, mas não aos 60 dias. A análise da morfometria dos neurônios 5-HT-IR, em ambas as idades estudadas, revelou alterações em sua forma. Os resultados deste estudo demonstram a ação inibitória da serotonina sobre o crescimento somático e desenvolvimento sensório-motor bem como alterações na quantidade e na forma dos neurônios 5-HT em ratos. / The aim of the present study was to investigate the effects of prenatal sertraline exposure on offspring in growth and somatic development and even in the maturation of reflex in rats. Female wistar rats were treated with sertraline (Sert, 30 mg/kg, 0,5 mL/100 g, s.c., N=11) or distilled water (Control, N=11) during the whole pregnancy. After the birth, 8 pups (4 males and 4 females) were kept in each litter during lactation. The blind investigator evaluated indicators of general body growth parameters, somatic maturation and ontogeny of reflex during the period of lactation. The central nervous system alterations were approached by 5-HT-IR using the ABC-DAB-Peroxidase techniques in animals at the 22st and 60st postnatal day. The Sert group, showed reduction on the somatic growth and on the maturation of reflexes. There was reduction in the amount of the 5-HT-IR neurons in the raphe nuclei at the 22st postnatal day, but did not change at the 60st. The morphometric analysis revealed alterations in the shape of these cells at the 22st and 60st postnatal day. An inhibitory action of the 5-HT on the somatic and sensory-motor growth in these rats was also observed. After the lactation period, the amount and shape of the 5-HT neurons were altered.
83

High frequency acoustic reflexes in cochlea-impaired and normal ears

Jones, Karen Elizabeth 01 January 1990 (has links)
The acoustic reflex refers to the contraction of a middle ear muscle in response to sound. The contraction causes a stiffening of the middle ear system and, consequently, the flow of acoustic energy to the cochlea is impeded. By measuring the change in admittance in the auditory system during sound stimulation it is possible to indirectly monitor the middle ear muscle contractions. Such measurements provide useful information regarding the integrity of the auditory system and the location of the auditory pathology.
84

Establishing a Kinetic Assessment of Reactive Strength

Louder, Talin 01 May 2017 (has links)
The reactive strength index (RSI) is the current “gold standard” assessment of reactive strength. Traditional measures of reactive strength, including the RSI, are not strength-based and are founded using untested theoretical assumptions. The purpose of this study was to develop two versions of a kinetic-based paradigm of reactive strength (New and AdjNew) and compare them against the Coefficient of Reactivity (CoR) and the RSI. Twenty one NCAA Division I basketball players and 59 young adults from the general population performed two reactive strength protocols: Progressive drop jumping and repetitive countermovement jumping. For every jump, the CoR, RSI, New, and AdjNew were computed. Measure agreeability was assessed using the Bland-Altman approach and linear regressions. Analyses of variance (ANOVA) assessed the effect of sport participation, age, and sex on the four measures of reactive strength. Lastly, effects of self-reported physical activity levels were assessed using stepwise linear regressions. The strongest association was observed between AdjNew and the RSI (R2= 0.636). All NCAA > young adults). The RSI, New, and AdjNew were sensitive to effects of sex and sport participation in repetitive countermovement jumping (males > females; NCAA > young adults). There are theoretical issues with the computation and implementation of the CoR and RSI. For example, the CoR and RSI are non-strength based measures that attempt to measure a strength construct. Further, the CoR, RSI, and New make the theoretical assumption that no biological variability exists in human movement. The AdjNew paradigm addresses and solves the theoretical issues with the CoR, RSI, and New. Therefore it may be argued that the AdjNew paradigm improves the theoretical validity of reactive strength assessment and is preferred over the RSI. The AdjNew is kinetic based, comprised of only measured component variables, and is not founded in assumptions of theory. This dissertation provides objective theoretical evidence to suggest that the AdjNew paradigm is an improvement over the RSI as a model of reactive strength.
85

Effect of eye position on the three-dimensional kinematics of saccadic and vestibular-evoked eye movements

Thurtell, Matthew James January 2007 (has links)
Master of Science in Medicine / Saccadic and vestibular-evoked eye movements are similar in that their three-dimensional kinematic properties show eye position-dependence. When the line of sight is directed towards an eccentric target, the eye velocity axis tilts in a manner that depends on the instantaneous position of the eye in the head, with the magnitude of tilt also depending on whether the eye movement is saccadic or vestibular-evoked. The mechanism responsible for producing eye velocity axis tilting phenomena is not well understood. Some authorities have suggested that muscle pulleys in the orbit are critical for implementing eye velocity axis tilting, while others have suggested that the cerebellum plays an important role. In the current study, three-dimensional eye and head rotation data were acquired, using the magnetic search coil technique, to confirm the presence of eye position-dependent eye velocity axis tilting during saccadic eye movements. Both normal humans and humans with cerebellar atrophy were studied. While the humans with cerebellar atrophy were noted to have abnormalities in the two-dimensional metrics and consistency of their saccadic eye movements, the eye position-dependent eye velocity axis tilts were similar to those observed in the normal subjects. A mathematical model of the human saccadic and vestibular systems was utilized to investigate the means by which these eye position-dependent properties may arise for both types of eye movement. The predictions of the saccadic model were compared with the saccadic data obtained in the current study, while the predictions of the vestibular model were compared with vestibular-evoked eye movement data obtained in a previous study. The results from the model simulations suggest that the muscle pulleys are responsible for bringing about eye position-dependent eye velocity axis tilting for both saccadic and vestibular-evoked eye movements, and that these phenomena are not centrally programmed.
86

Understanding the Mechanisms of Motor Learning in the Vestibulo-ocular Reflex

Titley, Heather 11 January 2012 (has links)
The vestibulo-ocular reflex (VOR) is a simple reflex that stabilizes gaze by moving the eyes in the opposite direction to the head. The gain of the VOR (ratio of head to eye velocity) can be increased or decreased during motor learning. It is thought that the memory for learned changes in the VOR gain is initially encoded within the cerebellar flocculus. Furthermore, these learned gain changes can be disrupted or consolidated into a long-term memory. In this thesis we describe novel results that show that consolidation of the VOR can take place rapidly, within 1 hour after learning has stopped. Furthermore, we demonstrated that unlike learning, which has been shown to have frequency selectivity, disruption and rapid consolidation generalize across the range of frequencies. We suggest that disruption and rapid consolidation in the VOR are local mechanisms within the cerebellar cortex, and do not require new learning. This thesis also provides additional evidence for the idea that learned gain increases and decreases are the result of separate mechanisms, most likely long-term depression and potentiation respectively, at the parallel fibre-Purkinje cell synapses. We demonstrate that learned gain increases, but not decreases, require the activation of type 1 metabotropic glutamate receptors (mGluR1) and B type γ-aminobutyric acid (GABAB) receptors. Blocking one or both of these receptors with an antagonist inverts gain-up learning, while the agonist augments gain-up learning. Furthermore, we provide novel evidence that these receptors are co-activated during gain-up learning.
87

Understanding the Mechanisms of Motor Learning in the Vestibulo-ocular Reflex

Titley, Heather 11 January 2012 (has links)
The vestibulo-ocular reflex (VOR) is a simple reflex that stabilizes gaze by moving the eyes in the opposite direction to the head. The gain of the VOR (ratio of head to eye velocity) can be increased or decreased during motor learning. It is thought that the memory for learned changes in the VOR gain is initially encoded within the cerebellar flocculus. Furthermore, these learned gain changes can be disrupted or consolidated into a long-term memory. In this thesis we describe novel results that show that consolidation of the VOR can take place rapidly, within 1 hour after learning has stopped. Furthermore, we demonstrated that unlike learning, which has been shown to have frequency selectivity, disruption and rapid consolidation generalize across the range of frequencies. We suggest that disruption and rapid consolidation in the VOR are local mechanisms within the cerebellar cortex, and do not require new learning. This thesis also provides additional evidence for the idea that learned gain increases and decreases are the result of separate mechanisms, most likely long-term depression and potentiation respectively, at the parallel fibre-Purkinje cell synapses. We demonstrate that learned gain increases, but not decreases, require the activation of type 1 metabotropic glutamate receptors (mGluR1) and B type γ-aminobutyric acid (GABAB) receptors. Blocking one or both of these receptors with an antagonist inverts gain-up learning, while the agonist augments gain-up learning. Furthermore, we provide novel evidence that these receptors are co-activated during gain-up learning.
88

Multi-Mode Charging Circuit

Wu, Chih-Kang 15 June 2004 (has links)
Charging technology is becoming more and more important since rechargeable batteries are commonly used in many applications than ever before. To facilitate various charging profiles, a battery charger with multi-mode is proposed. The charger is composed of an innovative reflex charging circuit and a controllable half-bridge converter with pulse-width-modulation. This multi-mode charger provides not only four basic functions of constant voltage (CV), constant current (CC), pulsed current (PS) and reflex charging (RX), but also the multi-stage charging with hybrid charging modes. The desired charging profile can easily be accomplished by adjusting the controllable parameters of the charger. In order to simplify the control circuit, a digital signal processor (DSP) with the associated sensors and interface circuits are used as the control kernel. By continuously monitoring the charging current and battery voltage, the charging modes can be adapted to the charging strategy. An experimental charging circuit is built and tested. The experiments in this dissertation are carried out on lead-acid batteries, Experimental results show that the charger is able to execute the charging functions of various tentative charging strategies with hybrid charging modes.
89

A Pilot Study of Change in Laryngeal Cough Threshold Sensitivity and PAS(Penetration Aspiration Scale) Score Within the Acute Stage

McFarlane, Mary January 2013 (has links)
Background: Cough Reflex Testing (CRT) has been shown to be useful in the challenging task of identifying silent aspiration (aspiration without a cough response). With the emergence of the routine clinical use of CRT in the acute stroke population, the following clinical conundrum often arises: Does passing a previously failed CRT mean the risk of silent aspiration has resolved? The purpose of this study was to evaluate the association between change in laryngeal cough threshold sensitivity and change in PAS (Penetration Aspiration Scale) score within the acute stage post-stroke. Methods: This was a prospective longitudinal pilot study of 20 acute stroke patients utilizing a Cough Reflex Threshold Test (CRTT) at 0.4M, 0.6M and 0.8M citric acid concentrations and Fiberoptic Endoscopic Evaluation of Swallowing (FEES). A cough response threshold was obtained from the CRTT and a PAS (penetration aspiration scale) score from FEES. Inclusion criteria required a PAS score of 4 or above on preliminary FEES or impaired CRT threshold as defined by weak or failed cough test result at 0.8M citric acid concentration. Both test methods were repeated every four days for 20 days or until the participant no longer aspirated/penetrated and had a normal result on CRTT on two consecutive assessment sessions. Agreement between changes in the two tests was evaluated using the Cohen’s Kappa statistic. Results: Eighteen of the twenty participants in this study aspirated on initial assessment, ten of which were silent. One participant continued to aspirate at study completion. On initial assessment eleven participants had a C2 response threshold at 0.4M citric acid concentration and three participants failed to reach threshold at 0.8M citric acid concentration. At study completion, 18 participants had a C2 response threshold at 0.4M citric acid concentration and one participant failed to reach threshold at 0.8M citric acid concentration. During the study, sixty-six re-assessments took place; there were fifteen incidences of improved cough response threshold on re-assessment and thirty-one incidences of improved PAS score. There was no significant agreement between improved laryngeal cough reflex threshold and improved PAS score during the acute stage Kappa = 0.0598 (p <.0.574), 95% CI (- 0.1496- 0.2692). Conclusion: Significant limitations of this study included small data set and potential flooring effect of the CRT. Due to the limitations of this study, no conclusions can be made as to the appropriateness of reinstating oral intake based on passing a previously failed CRT.
90

An Investigation of Self-Report and Psychophysiologic Empathic Responses In Non-Psychopathic and Psychopathic Individuals

Kirsch, Laura G. January 2009 (has links)
A lack of empathy is considered to be a hallmark feature of psychopathy. However, remarkably little research has specifically examined the relationship between psychopathy and empathy, and what does exist relies solely on self-report measures, which is problematic given psychopaths' propensity for dishonesty. This research signifies an attempt to develop an objective measure of empathy, using psychophysiological indices of emotional experience as indicators of an empathic response. Specifically, corrugator and zygomatic facial muscle activity, event-related heart rate, and acoustic startle reflex responses were measured while participants viewed brief films of individuals experiencing happy and sad emotional events.Pilot investigations of the films suggest they are appropriate for eliciting happy and sad empathic emotion, and the pattern of responses by undergraduates with high and low trait levels of empathy indicates the validity of the approach, and the promise of utilizing psychophysiological indices of emotional responding to measure situational empathy in an objective manner. In particular, participants demonstrated patterns of psychophysiological responses to the empathy-inducing films which both matched their self-reported emotional experiences as well as the emotional valence of the stimuli. Moreover, several of the psychophysiological indices were able to discriminate high and low empathy individuals, whereby low empathy participants exhibited less facial expressiveness and less modulation of the acoustic startle reflex to the empathy-inducing stimuli than their high empathy counterparts.The paradigm was then extended to a sample of male undergraduates with high and low levels of psychopathic traits, as assessed by the Psychopathic Personality Inventory-Revised. Results suggest a significant negative relationship between self-reported psychopathy and self-reported dispositional empathy, with high levels of psychopathy associated with low levels of dispositional empathy, particularly with respect to affective empathy. However, despite differences in dispositional empathy, psychopathic and non-psychopathic undergraduates were not easily discriminated on subjective or objective measures of situational empathy, with the exception of an anomalous pattern of zygomatic EMG activity exhibited by the psychopathic participants. The implications of these findings are discussed with respect to the nature of the empathic capabilities of psychopaths, as well as considerations of the methodological limitations of the current study and directions for future research.

Page generated in 0.0292 seconds