• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 425
  • 363
  • 89
  • 44
  • 21
  • 15
  • 15
  • 11
  • 9
  • 9
  • 8
  • 6
  • 5
  • 5
  • 4
  • Tagged with
  • 1225
  • 1225
  • 488
  • 315
  • 236
  • 208
  • 189
  • 187
  • 184
  • 168
  • 146
  • 143
  • 119
  • 98
  • 97
  • 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.
311

Can internal and external load measures via Polar Vantage V predict training status in trained individuals? : - A prospective study during a normal and a heavy load training week.

Offerman, Jens January 2019 (has links)
Purpose To evaluate the information provided by Polar Vantage V, a new generation of heart rate monitor/watch (HRM-watch) to the user, regarding the acute:chronic load ratio (ACLR), based onthe external and internal load measures and examine the measures against psychological and physiological measures before and during a threshold test with VO2max testing. Method A five-week prospective study with results and data collected during and after four normal training weeks and during a fifth week with a very high training load. The results from HRM-watchwere then evaluated against the results from physiological and psychological tests. Eight endurance runners were recruited. Results Differences in ACLR against the differences in HRR show a R2 value of 0.77 (p<0.05). ACLR signicantly increased with an average of 0.33 from 0.93 to 1.26 (p=0.003, 95 % CI= 0.17 {0.49). Differences in ACLR against dierences in total mood disturbance (TMD) from POMS showin regression analyses a R2value of 0.67 (p=0.05). No significant difference was noted in neither resting HRV (p=0.3, 95% CI= -22.2 { 8.5) or standing HRV (p=0.15, 95% CI= - 4.15 { 20.8). Conclusion Based on the result of the present study it can be concluded that training status, well-being and present mood state can be predicted fairly good with the information from the internal and external load measurements from the Polar Vantage V. However, the power of present exploratory study was low due to a low number of included participants. Future research with greater number of participants and an improved study design is needed to verify these interesting findings.
312

The relationship between training load and incidence of injury and illness over a pre-season at an Australian Football League Club

PIGGOTT, Benjamin, ben_piggott@yahoo.com January 2008 (has links)
In any competitive sporting environment, it is crucial to a team's success to have the maximum number of their players free from injury and illness and available for selection in as many games as possible throughout the season. The training programme of the club, and therefore training load, can have an impact on the incidence of injury and illness amongst the players. The purpose of this study was to investigate the relationship between the training load and the incidence of injury and illness over an entire pre-season at an Australian Football League (AFL) club. Sixteen players were subjects; all full time professional male AFL players (mean + or - standard deviation; age 23.8 + or - 5.1 years; height 188.9 + or - 7.4 m; weight 90.9 + or - 9.2 kg). A longitudinal research design was employed, where training load, injury and illness were monitored over a 15 week pre-season and Pearson Correlation Coefficients were used to examine relationships.
313

The Effect of Plants on Individuals' Stress Level in an Indoor Work Environment

Larsson, Marie-France January 2010 (has links)
<p>Many instances of sick leave can be linked to diseases caused by stress. An efficient way to counter the negative effects of stress is coping. However, trying to fit coping activities into an already busy schedule can be stressful in itself. Therefore it is interesting to study passive stress-reducing methods, for instance interaction with nature. This paper studied the effect of the presence of plants in a work-like environment on the stress level of 30 participants divided equally in a control group and a test group by measuring their heart rate. A factorial analysis of variance and a multivariate analysis of variance were used to analyze the data. Despite the heart rate of the control group being on an average 5 beats per minute higher than the test group, the difference was found not to be statistically significant. An explanation for this could be the poor reliability of heart rate as a measure of stress.</p><p>Keywords: coping, heart rate, indoors, nature, plants, stress, work</p>
314

Methodological aspects and usefulness of Quantitative Sensory Testing in early small fiber polyneuropathy : a clinical study in Swedish hereditary transthyretin amyloidosis patients

Heldestad, Victoria January 2011 (has links)
Generalised polyneuropathy (PNP) is a common cause to neurological impairment, and may be an early symptom of a severe systemic disease. One such illness is hereditary transthyretin (TTR) amyloidosis (ATTR), a progressive fatal disorder caused by a mutation on the TTR gene. More than 100 such mutations have been found worldwide, of which Val30Met is the most common neuropathic variant with initial clinical manifestations indicating small fiber impairment. Differences in onset age, penetrance and phenotypes are present between endemic areas. Liver transplantation generally slows the progress of the symptom development, especially in patients with short disease duration. Ongoing research has also shown promising results with drug interventions. In any event, early diagnosis of PNP onset in ATTR patients is crucial to ensure early therapeutic interventions. Nerve conduction studies (NCS) and electromyography (EMG) provide the basis for evaluation of the functional state of the thick myelinated nerve fibres in patients with symptoms of PNP, but no such quantitative methods are available for the thin myelinated or unmyelinated fibers. Instead, a psychophysical method with thermal quantitative sensory testing (QST) can provide indirect information about the overall function in the afferent small fiber systems. The purpose of thesis was to evaluate the applicability of QST by the Method-of-limits (MLI) for early detection of PNP in Swedish ATTR patients with the Val30Met mutation. In healthy subjects the repeatability of the MLI was assessed, and reference values for thermal perception thresholds (TPT) in several body regions were determined. No significant differences in TPT or pain thresholds were found at repeated testing with MLI, indicating that the MLI is a reliable method. However, the results show that the arrangement of the testing order is of importance, as cold (CT) and warm (WT) perception thresholds were significantly elevated when tested after thermal pain assessments, instead of before. I general, the TPT was more elevated at lower parts of the body compared to the upper part, and with higher WT than CT, fully in accordance with the underlying anatomical and physiological prerequisites for QST. In biopsy verified ATTR patients lacking EMG and NCS abnormalities, significantly elevated TPT were found compared to controls. Furthermore, significantly more increased TPT were observed in patients with an early onset of the disease, compared those with a late onset. Finally, a combined detailed evaluation of QST and heart rate variability (HRV) analyses demonstrated correlations between QST and HRV abnormalities in patients with late onset, but not in those with early onset. The present thesis emphasizes the importance of incorporating QST early in the clinical evaluation of ATTR patients with a Val30Met mutation and with symptoms of thin fiber PNP. This is particularly indicated when patients report symptoms, or show signs, of neuropathic small fiber affection, but simultaneously exhibit normal EMG and NCS findings. The results furthermore underline the importance of performing both QST and HRV for a complete evaluation of both the thin somatic and autonomic nerve fibers, as both types of nerves may be affected early in the ATTR disease.
315

Idiopathic environmental intolerance attributed to electromagnetic fields : physiological and psychological aspects

Johansson, Amanda January 2008 (has links)
This thesis aims to increase the knowledge on people with symptoms attributed to electromagnetic fields (EMF) by investigating the effects of EMF exposure and by additional description of the heterogeneous group of people reporting EMF-related symptoms. The effect of mobile phone (MP)-like radio frequency (RF) fields on symptoms, autonomic nervous system (ANS) parameters, short-term memory, and reaction time in persons with MP-related symptoms (MP participants) was investigated in a provocation study. A second provocation study investigated the effect of similar exposure on serum concentration of biomarkers in persons with atopic dermatitis. No effect of exposure was detected in either study. MP participants displayed changes in heart rate variability (HRV) during cognitive tests, but not during rest. This contrasts with earlier findings, participants with symptoms attributed to EMF sources in general (EHS participants) displayed an elevated sympathetic nervous system activity both during cognitive tests and during rest. Proposed differences between subgroups of persons with EMF-related symptoms with respect to symptoms, personality traits and stress were investigated in a questionnaire study. MP participants reported primarily symptoms from the head; EHS participants reported symptoms from many organ systems. Furthermore, EHS participants reported higher levels of anxiety, depression, stress, and exhaustion when compared with a reference group. MP participants reported higher levels of anxiety and exhaustion only. In a pilot study, 24-hour and short-term HRV were investigated in EHS participants, to examine whether the previously observed sympathovagal imbalance would still be present. There was a tendency toward increased parasympathetic activity compared with earlier recordings, and a reduction of symptoms. Twenty-four hour and short-term recordings were fairly similar for each participant; however, there were large between-subject differences. The results do not support the hypothesis of effects of MP-like RF exposure on symptoms, ANS activity, CFFT, cognitive function, or biomarkers. However, they do support the hypothesis that persons with different symptom attribution (MP and EHS) may differ also in ANS activity and psychological aspects.
316

The Effect of Plants on Individuals' Stress Level in an Indoor Work Environment

Larsson, Marie-France January 2010 (has links)
Many instances of sick leave can be linked to diseases caused by stress. An efficient way to counter the negative effects of stress is coping. However, trying to fit coping activities into an already busy schedule can be stressful in itself. Therefore it is interesting to study passive stress-reducing methods, for instance interaction with nature. This paper studied the effect of the presence of plants in a work-like environment on the stress level of 30 participants divided equally in a control group and a test group by measuring their heart rate. A factorial analysis of variance and a multivariate analysis of variance were used to analyze the data. Despite the heart rate of the control group being on an average 5 beats per minute higher than the test group, the difference was found not to be statistically significant. An explanation for this could be the poor reliability of heart rate as a measure of stress. Keywords: coping, heart rate, indoors, nature, plants, stress, work
317

Zur Beziehung zwischen der akzelerometrisch erfassten Körperbeschleunigung und der Herzfrequenz beim Pferd

Kubus, Katrin 14 June 2013 (has links) (PDF)
Zur Ermittlung des Energieverbrauches bei Mensch und Tier stehen verschiedene Methoden zur Verfügung. Im Jahre 1780 nutzte Lavoisier die Schmelzwassermenge, um den Energieverlust eines Meerschweinchens zu berechnen. Das Tier saß in einem von Eis umgebenen Kalorimeter, die von ihm abgegebene Wärme brachte das Eis zum Schmelzen. Derzeit sind die indirekte Kalorimetrie, die den Energieumsatz über den im Respirationsversuch gemessenen Gaswechsel von O2 und CO2 sowie die im Harn ausgeschiedene Stickstoffmenge bestimmt, und die Isotopendilutionsmethode, die mit der unterschiedlichen Ausscheidungsrate von markierten Wasserstoff- (2H) und Sauerstoff- (18O) Atomen im Urin arbeitet, der „Goldstandard“ für die Bestimmung des Energieverbrauchs. Seit einigen Jahren bis heute steht die Herzfrequenzmethode in der Diskussion. Sie nutzt die Beziehung zwischen Herzfrequenz und Sauerstoffverbrauch zur Ermittlung des Energieumsatzes. Alle genannten Methoden haben Vor- und Nachteile, insbesondere für den einfachen und schnellen täglichen Einsatz sowie bei Langzeitstudien. Deshalb werden Alternativen gesucht. Diese Dissertation untersucht die Beziehung zwischen der akzelerometrisch erfassten dreidimensionalen Körperbeschleunigung und der Herzfrequenz beim Pferd in verschiedenen Gangarten. Dabei wird die Herzfrequenz als Vergleichs- und Bezugsgröße verwendet. Sie stellt das direkte Bindeglied zum Sauerstoffverbrauch und damit Energieaufwand dar. Es wurden drei Versuchsvarianten durchgeführt. Die Pferde gingen an der Hand, „geführt“, liefen frei in einem umzäunten Oval, „freilaufend“, oder wurden „geritten“. Bei den beiden Varianten „geführt“ und „freilaufend“ kamen jeweils dieselben vier Pferde zum Einsatz, die Variante „geritten“ absolvierten fünf andere Tiere. Die Versuche folgten verschiedenen Schemata mit den Gangarten Schritt, Trab und, zum Teil, Galopp. Bei allen Versuchen wurden parallel die dreidimensionale Körperbeschleunigung mit einer Frequenz von 32 Hz sowie die Herzfrequenz gemessen. Die Pulsuhr speicherte im kleinstmöglichen Intervall von fünf Sekunden. Nach Aufbereitung der Beschleunigungsrohdaten wurde letztendlich der dynamische Anteil der dreidimensionalen Beschleunigung in Form von „fünf-Sekunden-Mittelwerten“ berechnet. Anschließend wurden diese Beschleunigungswerte über die Regressionsanalyse mit den Originalwerten der Herzfrequenz in Beziehung gesetzt. Dabei wurden die Übergangsphasen zwischen den Gangarten ausgenommen, da die beiden Parameter hier ein sehr unterschiedliches und zeitversetztes Verhalten zeigen. Bei der Analyse der Gangarten Schritt und Trab konnte gut mit dem Modell der einfachen linearen Regression (y = a + bx) gearbeitet werden, mit Hinzukommen der dritten Gangart, Galopp, erwies sich das Modell der polynomialen Regression (y = a + bx + cx²) von Vorteil. Die Stärke des Zusammenhanges der beiden Größen wurde durch den Korrelationskoeffizienten r angezeigt. Bei differenzierter Betrachtung der Versuchsvarianten und der einzelnen Pferde erreichte r Werte von 0,86 bis 0,94, bei zusammenfassender Betrachtung aller Pferde einer Versuchsvariante Werte zwischen 0,82 und 0,87, stets bei signifikanter Korrelation (p < 0,05). Somit kann für die Parameter Herzfrequenz und Beschleunigung ein signifikanter und starker Zusammenhang beschrieben werden. Sie verhalten sich dabei nicht proportional zueinander. Schlussfolgernd lässt sich sagen, dass die Akzelerometrie für bestimmte Zielstellungen und unter bestimmten Voraussetzungen eine geeignete Methode ist, um den Energieaufwand von Pferden zu bestimmen. Sie ist schnell und meist störungsfrei durchzuführen und im Gegensatz zur Herzfrequenz nahezu unabhängig von emotionalen Einflüssen. Des Weiteren bietet die Akzelerometrie die Möglichkeit, die Ermittlung des Energieumsatzes mit einer Verhaltensanalyse zu kombinieren. Bedingungen für ihren Einsatz sind eine situationsspezifische und möglichst individuelle Kalibrierung, denn die Beschleunigungsmessung weist insofern Nachteile auf, als dass sie die Auswirkungen von zum Beispiel Bodenbeschaffenheit, Umwelteinflüssen oder das Tragen einer Last auf den Energieumsatz nicht berücksichtigt. Die parallele Erfassung von Herzfrequenz und Beschleunigung kann zum Beispiel zur Analyse und Kontrolle von Trainingserfolgen genutzt werden. Somit bringt die Kombination von Herzfrequenz- und Beschleunigungsmessung klare Vorteile. / There are different opportunities to determine the consumption of energy in humans and animals. In 1780 Lavoisier used the quantity of melt water to calculate the energy loss of a guinea pig. The guinea pig was located inside a calorimeter which was surrounded by ice. The emitted heat induced the melting of the ice. At present both, indirect calorimetry that estimates energy expenditure from respiratory measurements of oxygen consumption and carbon dioxide production plus the excretion of nitrogen with the urine and the DLW-method that uses the different urinary elimination rates of the isotopes 2H and 18O are the so called “golden standard” for the calculation of energy consumption. For several years until now there has been a discussion about the heart rate-method. This method uses the correlation between heart rate and oxygen consumption for the calculation of energy expenditure. All above mentioned methods have pros and cons, especially for simple and quick every day application and for long-term studies. Therefore alternatives are searched. This dissertation examines the relation between the accelerometricly measured three-dimensional body acceleration and the heart rate in horses at different gaits. The heart rate has been used for comparison and as a reference item. It directly relates the acceleration with the oxygen consumption and thus with the energy expenditure. There have been three variants of trials. Horses were led by the hand (HD), moved freely (MF) in an enclosed oval or were ridden (R). In the HD- and MF-trials the same four horses were used, for the R-trials five other horses came into action. The trials followed different schemes with the gaits of walk, trot and gallop. At every trial three-dimensional body-acceleration with a logging frequency of 32 Hz and heart rate were measured simultaneously. The heart rate meter stored the heart rate in the smallest possible intervals of five seconds. After processing the crude data the dynamic part of the three-dimensional acceleration was calculated in form of “five-second-means”. After that the regression analysis was used to relate these acceleration data to the original heart rate data. In this process the transitional phases between the gaits were excluded because there both parameters have a highly varying and time-shifted relation. The model of simple linear regression (y = a + bx) suited well for analysing walking and trotting. With adding the third gait gallop the model of polynomial regression (y = a + bx + cx²) became more favourable. The correlation coefficient r showed the strength of the correlation between both parameters. By the separate inspection of the variants of trials and the individual horses r reached values from 0,86 to 0,94; pooling all horses of each variant of trials yields r-values from 0,82 to 0,87, always with a significant correlation (p < 0,05). Hence a significant and strong correlation can be attributed to the parameters heart rate and acceleration. They are not proportional to each other. In conclusion one can say: for specific aims and under certain conditions the accelerometry is an appropriate method to assess energy expenditure in horses. You can implement it quickly and mostly disturbance-free and in contrast to the heart rate it is nearly independent of emotional influence. Furthermore accelerometry gives the opportunity to combine the determination of the energy expenditure with the analysis of behaviour. A possibly individual and situation-specific calibration are the preconditions for its application. A setback of the accelerometry is that the effects of such factors like the condition of the ground, environmental influences or carrying weights are not taken into consideration. Simultaneous measurement of heart rate and body-acceleration can for example be used for analysing and controlling the success of training. Consequently there are clear advantages of combining the measurement of heart rate and acceleration.
318

College Men's Psychological and Physiological Responses Associated with Violent Video Game Play

Powell, Cecil Lamonte 22 April 2008 (has links)
Research suggests that playing violent video games increases the likelihood of aggression. However, less clear is how individual characteristics influence the mechanisms that lead to aggression. Using Anderson and Bushman’s (2002) General Aggression Model as a framework, the present study examined the independent and joint effects of individual differences and situational factors on affective and physiological reactivity to playing a violent video game. One hundred thirty-three participants completed self-report measures of trait aggression and violent video game exposure. They were randomly assigned to groups instructed to play a video game using either violent or nonviolent strategies while facial electromyography, heart rate, and electrodermal activity were measured. Positive and negative affect was assessed via self-report prior to and following video game play. It was hypothesized that trait aggression and level of past exposure to violent video games would be positively related to increases in physiological arousal and negative affect among participants in a violent, relative to a nonviolent, condition. Hierarchical regression analyses failed to detect a significant relationship between trait aggression and changes in heart rate, facial electromyography, or self-reported affect as a function of game condition. However, significant positive relationships were found between trait aggression and skin conductance, but only in the nonviolent condition. Analyses revealed that past exposure to violent video games was positively related to increased skin conductance among participants in the non-violent, but not the violent video game condition. Past exposure to violent video games was also positively related to increased heart rate, but this was among participants in the violent, but not the non-violent condition. Significant relationships between past exposure to violent video games and changes in facial electromyography and self-reported affect as a function of video game condition were not found. Findings are discussed in terms of how trait aggression and past exposure to violent video games influence arousal, and potentially, the likelihood of aggressive behavior.
319

Reagera och agera: Styrka och snabbhet i den manuella responsen för emotionella stimuli

Bärgh, Isabelle January 2012 (has links)
In this study I investigated whether the strength in the manual response for emotional and neutral stimulus search arrays can explain some of the difference in reaction times (RT:s) for emotional stimuli, or not. Earlier, perceptual, cognitive and attentional processes has mostly been used to explain the variance in RT:s. Thirtythree individuals were asked to, as fast as possible, detect a target picture among distractor pictures in 3 rows x 4 columns arranged search arrays. The pictures were categorized in fear relevant animals (snake, spider) and neutral animals (cat). The results showed, more correct responses for cat target. No correlation between strength and fear relevant target picture was found. This can partly be explained by that RT:s and force (Newton) was measured at different time sets with different buttons. The results show that the use of different response buttons results in a difference in the heartbeat frequency.
320

Effects of Stress and Balance of Options on Decision-Making and Associated Physiological Responses in Laying Hens

Persson, Mia January 2012 (has links)
Animal preferences in choice tests have frequently been used within animal welfare research to make recommendations about animal handling and husbandry. It is therefore important that these results are obtained in a way that, as far as possible, respects the behavioural capabilities of the animal. Stress has been shown to affect cognitive processes in animals and could therefore affect the decision making process. To examine the effects of stress on decision making, 16 laying hens were trained to distinguish between two different quantities of a food reward. A decision balance point was found, by increasing the cost of reaching the large reward, in lines with the theory of demand curves. Hens were then tested in a t-maze choice test with both balanced and unbalanced sets of options, with and without prior stress treatment. Choice, latency to choose, heart rate and temperatures were recorded. Hens that received stress treatment prior to their first test session were affected by this even in subsequent sessions where they did not receive stress treatment. This effect was not found in hens that first received stress treatment prior to their second test session. This shows the influence of previous experiences on animal decision making. Also, a decrease in heart rate during the decision making period was found, when making a choice between balanced options, indicating anticipation of difficulty. Additionally, this shows that physiological measurements such as heart rate could be of importance for future studies and greater understanding of underlying processes of animal decision making.

Page generated in 0.1081 seconds