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  • 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.
1

Relationships of Heat Stress Levels to Heat-Related Disorders and Acute Injury During Deepwater Horizon Cleanup Operations

Hiles, Michael H 01 January 2012 (has links)
Outdoor workers are often subjected to thermal conditions beyond the comfort zone, but to what degree do such conditions affect the health and safety of those workers is still a matter requiring further investigation. The purpose of this study is to examine the relationship between thermal conditions and (1) heat-related disorders and (2) acute injuries using injury and illness data collected during the BP Deepwater Horizon clean-up operations. Over an eleven month period, 5,485 cases were identified as either heat-related or an acute injury (incident type) and further divided by severity. Daily weather data were used to estimate the wet bulb globe temperature (WBGT) based on the time of day. Heat Stress Levels intervals were defined using the estimated WBGT. Labor-hours by month were estimated by the prevailing shift length in the month and the number of workers. The incidents were assigned a Heat Stress Level and the number of labor-hours by heat stress level were determined. The next step was to calculate the incident rate ratio by Heat Stress Level against the baseline of thermal comfort. The results indicated that the rate ratios for heat-related disorders and acute injury increased for thermal conditions from 24⁰C-WBGT to 30⁰C-WBGT. There was a further significant increase in rate ratio for heat-related injury above 33 °C-WBGT. It was notable that the incident rates for both heat-related disorders and acute injuries increased at thermal conditions generally considered to be below the occupational exposure limit (OEL) at 30 ⁰C-WBGT. The rate of heat-related disorders increased substantially above the occupational exposure limit.
2

Varför väljer personal att lämna stora revisionsbyråer? : Hur påverkar motivation och arbetstillfredsställelse revisorers och redovisningskonsulters beslut att lämna de stora revisionsbyråerna? / Why do staff choose to leave large audit firms? : How does motivation and job satisfaction affect accountants decision to leave the large audit firms?

Kefalas, Katerina, Broman, Elin January 2019 (has links)
Bakgrund Hög omsättning av personal har länge varit ett problem inom de stora revisionsbyråerna och det är inte ovanligt att många väljer att avsluta sin tjänst efter bara några år. Många ser sin anställning på en stor revisionsbyrå som ett förberedande steg i karriären för att sedan söka sig vidare. Syfte Syftet med den här studien är att undersöka hur revisorer och redovisningskonsulter upplevde motivation på sin tidigare arbetsplats och hur motivation och arbetstillfredsställelse påverkade deras beslut att avsluta sin anställning. Metod Den här kvalitativa studien är genomförd med en deduktiv ansats med induktiva inslag där empiri har samlats in genom semistrukturerade intervjuer med revisorer och redovisningskonsulter. Slutsats Studien visar på att det finns flera anledningar till att revisorer och redovisningskonsulter väljer att lämna sin arbetsplats och att det är många olika faktorer som påverkar motivation och arbetstillfredsställelse. Det som gav våra respondenter mest motivation var den roliga kundkontakten. Faktorer som fått våra respondenter att lämna sin arbetsplats var lön, stress kombinerat med hög arbetsbörda, att de hade för många arbetsuppgifter som inte hade med kunderna att göra, företagsledningen, erbjudande om andra jobbmöjligheter och att de ville testa på något nytt. / Introduction A high turnover of staff has been a problem in the large auditing firms for a long time. It is not unusual that many people choose to leave their firm after just a few years. Some people see their employment at a large auditing firm as a preparatory step in their careers. Purpose The purpose of this study is to investigate how accountants experienced motivation at their previous workplace and how motivation and job satisfaction affected their decision to terminate their employment. Method This qualitative study is pursued through a deductive approach with inductive elements where empirical data has been collected through semi-structured interviews with accountants. Conclusion The study indicates that there are several reasons why accountants choose to leave their workplace and that there are many different factors that affect motivation and job satisfaction. What gave our respondents the most motivation was the customer contact and to help their customers. Factors that caused our respondents to leave their workplace were salary, stress in combination with an excessively high workload, that they had too many tasks that did not have to do with their clients, the management and other job opportunities.
3

Beröringens betydelse för upplevt lugn : Känsla av upplevt lugn hos massageterapeuter / The significance of skin on skin contact for perceived calmness : The sense of perceived calm in massage therapists after giving massage

O'Keefe, Tara January 2019 (has links)
Syftet med denna studie är att undersöka hur upplevd stressnivå påverkas av hand mot hudkontakt vid och efter massage hos massageterapeuter. Studien avgränsas till att endast undersöka massage där massageterapeutens händer har kontakt mot klientens hud, av diplomerade massageterapeuter inom svensk klassisk massage. En enkät utformades specifikt för att undersöka massageterapeuternas upplevelse av stressnivå i samband med och efter massagebehandling. Enkäten besvarades av 78 diplomerade massageterapeuter inom svensk klassisk massage från hela Sverige. Resultatet visar att skattning av upplevd stressnivå var lägre i samband med massagebehandling och direkt efter massagebehandling än 12 och 24 timmar efter utförd massagebehandling. En majoritet (73 procent) angav att de upplevde stressreducering och känsla av lugn under och efter utförd massagebehandling. Ett en-vägs ANOVA test visade att desto längre tid som passerade efter massagebehandlingen, desto högre upplevelse av stressnivå rapporterade respondenterna. Skattningen direkt efter massage jämfört med 24 timmar efter massage visade på en signifikant skillnad. Medan skattning under massage och direkt efter massage visade på en mindre signifikant skillnad. Ett tvåsvansat T-test visade att det fanns en statistiskt signifikant skillnad direkt efter massage och 24 timmar efter. Alltså är det mindre än en chans på 1000 att den upplevda stressnivån (upplevt lugn) beror på slumpen. / The aim of this study is to examine how perceived levels of stress are affected by skin on skin contact during and after giving massage. The study is limited to licensed massage therapists within Swedish massage, where the therapists’ hands are in contact with the clients’ skin during the entire massage. A questionnaire was specifically designed to investigate with the objective to measure the experienced levels of stress during and after giving massage. The questionnaire was answered by 78 certified massage therapists across Sweden. The results show that the perceived level of stress was lower during and shortly after having given massage, than after 12 and 24 hours respectively. With more time passing since the massage was administered, the level of stress increased. A majority (73 percent) of the massage therapists stated that they experienced reduced levels of stress and increased level of calmness during and after giving the massage treatment. A one-way ANOVA test showed that the longer time that passed after giving the massage, the higher levels of stress was reported. The reported level of stress directly after giving massage compared to 24 hours later showed significant difference. While the reported level of stress during and directly after giving massage did not show a significant difference. An independent two-tailed T-test demonstrates that there was a statistically significant difference immediately after giving massage and 24 hours after. Meaning that there is a 0,1 percent risk that the perceived levels of stress (sense of calmness) is a result of random factors.
4

Multi-scale investigation of tensile creep of ultra-high performance concrete for bridge applications

Garas Yanni, Victor Youssef 10 November 2009 (has links)
Ultra-high performance concrete (UHPC) is relatively a new generation of concretes optimized at the nano and micro-scales to provide superior mechanical and durability properties compared to conventional and high performance concretes. Improvements in UHPC are achieved through: limiting the water-to-cementitious materials ratio (i.e., w/cm < 0.20), optimizing particle packing, eliminating coarse aggregate, using specialized materials, and implementing high temperature and high pressure curing regimes. In addition, and randomly dispersed and short fibers are typically added to enhance the material¡¦s tensile and flexural strength, ductility, and toughness. There is a specific interest in using UHPC for precast prestressed bridge girders because it has the potential to reduce maintenance costs associated with steel and conventional concrete girders, replace functionally obsolete or structurally deficient steel girders without increasing the weight or the depth of the girder, and increase bridge durability to between 75 and 100 years. UHPC girder construction differs from that of conventional reinforced concrete in that UHPC may not need transverse reinforcement due to the high tensile and shear strengths of the material. Before bridge designers specify such girders without using shear reinforcement, the long-term tensile performance of the material must be characterized. This multi-scale study provided new data and understanding of the long-term tensile performance of UHPC by assessing the effect of thermal treatment, fiber content, and stress level on the tensile creep in a large-scale study, and by characterizing the fiber-cementitious matrix interface at different curing regimes through nanoindentation and scanning electron microscopy (SEM) in a nano/micro-scale study. Tensile creep of UHPC was more sensitive to investigated parameters than tensile strength. Thermal treatment decreased tensile creep by about 60% after 1 year. Results suggested the possibility of achieving satisfactory microstructural refinement at the same temperature input despite the maximum temperature applied. For the first time, the presence of a 10 Ým (394 micro inch) wide porous fiber-cementitious matrix interface was demonstrated by nanoindentation and SEM for non-thermally treated UHPC only. Tensile creep at 90 days increased by 64% and 46% upon eliminating fibers for thermally and non-thermally treated UHPC, respectively. Increases in creep upon reducing the fiber content suggested that fibers carry part of the sustained load and thus reduce creep. Tensile creep strain was proportional to the stress applied up to 60% of the ultimate strength. No tensile creep failure occurred for a period of 1 year for pre-cracked UHPC under stress level of 40%. Also, no tensile creep failure occurred for a period of 90 days under stress level of 60%. Tensile creep failure occurred at stress levels of 70% and 80%. This study showed that fibers cannot be accounted for as shear reinforcement in lieu of stirrups unless micro-defect-free fiber-matrix interface is achieved.
5

Évaluation d'un nouveau complément à l'intervention en physiothérapie pour le torticolis postural chez les nourrissons

Goes de Castro, Priscilla 04 1900 (has links)
Le torticolis postural est une affection courante dans le milieu pédiatrique en particulier depuis que les parents ont adopté les lignes directrices de la campagne « Back to Sleep ». Habituellement, un programme d’exercices à domicile est présenté aux parents afin de promouvoir une récupération optimale toutefois, peu d’outils existent pour les accompagner dans la réalisation de ces exercices. L'objectif de cette étude était d'évaluer l'impact de l'addition du nouveau livret d’intervention pour le torticolis (LIT) sur la résolution du torticolis (restitution de l’amplitude passive du cou), le stress parental et la satisfaction à l’égard du traitement reçu et sur l'observance des parents au traitement à domicile. Cinquante-huit nourrissons référés en physiothérapie pour un torticolis postural ont été recrutés et randomisés au cours de leur première visite à l’un ou l’autre de ces 2 groupes: Physiothérapie + LIT (n = 29) ou Physiothérapie + traitement standard (n = 29). Des évaluateurs ont évalué à l’aveugle les patients 1 et 3 mois après leur visite initiale, 30 minutes avant leur consultation en physiothérapie. L’amplitude articulaire passive du cou en rotation était mesurée à l’aide d’un goniomètre arthrodial. Le niveau de stress parental a été évalué en utilisant l’Indice de Stress Parental (ISP). Les parents ont reçu l’ISP à la fin de la visite initiale et ont été invités à le compléter à la maison et le retourner à la visite suivante en physiothérapie ou à la visite de 1 mois. La satisfaction des parents à l’égard du traitement reçu a été évaluée en utilisant la Mesure du Processus de Soins (MPOC-56) à 3 mois. L'observance au traitement a été estimée en demandant aux parents de rapporter la durée quotidienne de positionnement des nourrissons sur le ventre pendant la semaine dernière à l’évaluation. L’analyse de nos données consista à d’abord décrire les performances des 2 groupes à l’aide de statistiques descriptives. Ensuite, des tests de t ont permis de comparer le changement à la rotation passive cervicale, entre la visite de 1 mois et la visite initiale ainsi qu’entre la visite de 3 mois et la visite initiale. Des tests de t ont aussi été calculés pour comparer les scores de chaque sous-échelle du ISP (stress parental) et du MPOC-56 (satisfaction des soins) entre les groupes. Le test du chi carré a été réalisé pour comparer l'adhérence entre les deux groupes à 1 et 3-mois. Les résultats ont montré une tendance à un plus grand changement de la rotation passive du cou à 1-mois dans le groupe LIT (Intervalle de Confiance à 95% = 95% IC= 1,97-8,77 ; p = 0, 17) mais pas à 3 mois. Les parents du groupe LIT ont obtenu des scores de stress plus faibles après avoir reçu l'outil d'intervention (95%IC= 49,20-57,94 ; p = 0, 01) et ont déclaré être plus satisfaits que les parents du groupe témoin pour le traitement reçu (95%IC= 6,7-6,8 ; p=0,03) e o partenariat avec les thérapeutes (95%IC= 6,3-6,9 ; p<0,001). Enfin, l'observance au traitement a été plus élevée dans le groupe LIT que dans le groupe contrôle en particulier à 3-mois (p = 0.01). Le nouveau livret d'intervention pour le torticolis accompagné d'un traitement de physiothérapie a tendance à contribuer à une restitution plus rapide de l’amplitude passive du cou en rotation, peut aider à diminuer le niveau de stress parental, contribuer à une plus grande satisfaction à l’égard du traitement et améliorer l’observance au traitement à domicile. / Postural Torticollis is a common condition in pediatric practices especially since parents have adopted “Back to Sleep” campaign’s guidelines. Parents are often instructed to carry out a home program of exercises; however there are few educational tools with comprehensive information about postural torticollis exercises. The main objective of this study was to evaluate the impact of the addition of the new Torticollis Intervention Booklet (TIB) on torticollis resolution (attainment of full passive neck range of motion), parental stress level, parental satisfaction and adherence to treatment received. Fifty-eight infants referred to physiotherapy for a postural torticollis were recruited and randomized during their initial visit to two groups: Physiotherapy + TIB (n=29) or Physiotherapy + Standard Care (n=29). Blinded evaluators assessed the patients at 1 and 3 months after their initial visit, thirty minutes before their physiotherapy consultation. Passive neck rotation range of motion (ROM) was measured by an arthrodial goniometer. Parental stress level was evaluated using the Parenting Stress Index- Short Form (PSI-SF). Parents received the PSI-SF at the end of the baseline visit and were requested to complete it at home and return it at their subsequent physical therapy appointment or at the second scheduled study assessment time. Parental satisfaction was evaluated using the Measure of Processes of Care (MPOC-56) at 3-months. Adherence to treatment was evaluated as the length of time per day parents reported having their children in the prone awake position in the week before follow-up visits. Analysis consisted of descriptive analyses for each group; t-tests to compare passive neck rotation ROM change scores between the baseline and 1-month visits and baseline and 3-month visits; and to compare subscale scores for PSI-SF (parental stress) and MPOC-56 (satisfaction with care) between the two groups. The Chi-square test was performed to compare adherence between the two groups at 1 and 3-months. The results showed a tendency to greater passive neck rotation (ROM) change at 1-month in the TIB group (95% Confidence Interval = 95%CI = 1.97- 8.77; p=0.17) but not at 3-months. Parents in the the TIB group showed lower global stress scores after receiving the intervention tool (95%CI= 49.20- 57.94; p = 0.01) and reported greater satisfaction than controls in the “coordinated and comprehensive care” (95%CI= 6.7-6.8; p=0.03) and « enabling and partnership » subscales (95%CI= 6.3-6.9; p<0.001). Finally, adherence was higher in the TIB group than controls especially at 3-months (p=0.01). The new Torticollis Intervention Booklet accompanied by physical therapy treatment has a tendency to lead to an earlier restitution of passive neck rotation ROM, may help decrease stress levels, increase satisfaction with treatment, and improve adherence.
6

Évaluation d'un nouveau complément à l'intervention en physiothérapie pour le torticolis postural chez les nourrissons

Goes de Castro, Priscilla 04 1900 (has links)
Le torticolis postural est une affection courante dans le milieu pédiatrique en particulier depuis que les parents ont adopté les lignes directrices de la campagne « Back to Sleep ». Habituellement, un programme d’exercices à domicile est présenté aux parents afin de promouvoir une récupération optimale toutefois, peu d’outils existent pour les accompagner dans la réalisation de ces exercices. L'objectif de cette étude était d'évaluer l'impact de l'addition du nouveau livret d’intervention pour le torticolis (LIT) sur la résolution du torticolis (restitution de l’amplitude passive du cou), le stress parental et la satisfaction à l’égard du traitement reçu et sur l'observance des parents au traitement à domicile. Cinquante-huit nourrissons référés en physiothérapie pour un torticolis postural ont été recrutés et randomisés au cours de leur première visite à l’un ou l’autre de ces 2 groupes: Physiothérapie + LIT (n = 29) ou Physiothérapie + traitement standard (n = 29). Des évaluateurs ont évalué à l’aveugle les patients 1 et 3 mois après leur visite initiale, 30 minutes avant leur consultation en physiothérapie. L’amplitude articulaire passive du cou en rotation était mesurée à l’aide d’un goniomètre arthrodial. Le niveau de stress parental a été évalué en utilisant l’Indice de Stress Parental (ISP). Les parents ont reçu l’ISP à la fin de la visite initiale et ont été invités à le compléter à la maison et le retourner à la visite suivante en physiothérapie ou à la visite de 1 mois. La satisfaction des parents à l’égard du traitement reçu a été évaluée en utilisant la Mesure du Processus de Soins (MPOC-56) à 3 mois. L'observance au traitement a été estimée en demandant aux parents de rapporter la durée quotidienne de positionnement des nourrissons sur le ventre pendant la semaine dernière à l’évaluation. L’analyse de nos données consista à d’abord décrire les performances des 2 groupes à l’aide de statistiques descriptives. Ensuite, des tests de t ont permis de comparer le changement à la rotation passive cervicale, entre la visite de 1 mois et la visite initiale ainsi qu’entre la visite de 3 mois et la visite initiale. Des tests de t ont aussi été calculés pour comparer les scores de chaque sous-échelle du ISP (stress parental) et du MPOC-56 (satisfaction des soins) entre les groupes. Le test du chi carré a été réalisé pour comparer l'adhérence entre les deux groupes à 1 et 3-mois. Les résultats ont montré une tendance à un plus grand changement de la rotation passive du cou à 1-mois dans le groupe LIT (Intervalle de Confiance à 95% = 95% IC= 1,97-8,77 ; p = 0, 17) mais pas à 3 mois. Les parents du groupe LIT ont obtenu des scores de stress plus faibles après avoir reçu l'outil d'intervention (95%IC= 49,20-57,94 ; p = 0, 01) et ont déclaré être plus satisfaits que les parents du groupe témoin pour le traitement reçu (95%IC= 6,7-6,8 ; p=0,03) e o partenariat avec les thérapeutes (95%IC= 6,3-6,9 ; p<0,001). Enfin, l'observance au traitement a été plus élevée dans le groupe LIT que dans le groupe contrôle en particulier à 3-mois (p = 0.01). Le nouveau livret d'intervention pour le torticolis accompagné d'un traitement de physiothérapie a tendance à contribuer à une restitution plus rapide de l’amplitude passive du cou en rotation, peut aider à diminuer le niveau de stress parental, contribuer à une plus grande satisfaction à l’égard du traitement et améliorer l’observance au traitement à domicile. / Postural Torticollis is a common condition in pediatric practices especially since parents have adopted “Back to Sleep” campaign’s guidelines. Parents are often instructed to carry out a home program of exercises; however there are few educational tools with comprehensive information about postural torticollis exercises. The main objective of this study was to evaluate the impact of the addition of the new Torticollis Intervention Booklet (TIB) on torticollis resolution (attainment of full passive neck range of motion), parental stress level, parental satisfaction and adherence to treatment received. Fifty-eight infants referred to physiotherapy for a postural torticollis were recruited and randomized during their initial visit to two groups: Physiotherapy + TIB (n=29) or Physiotherapy + Standard Care (n=29). Blinded evaluators assessed the patients at 1 and 3 months after their initial visit, thirty minutes before their physiotherapy consultation. Passive neck rotation range of motion (ROM) was measured by an arthrodial goniometer. Parental stress level was evaluated using the Parenting Stress Index- Short Form (PSI-SF). Parents received the PSI-SF at the end of the baseline visit and were requested to complete it at home and return it at their subsequent physical therapy appointment or at the second scheduled study assessment time. Parental satisfaction was evaluated using the Measure of Processes of Care (MPOC-56) at 3-months. Adherence to treatment was evaluated as the length of time per day parents reported having their children in the prone awake position in the week before follow-up visits. Analysis consisted of descriptive analyses for each group; t-tests to compare passive neck rotation ROM change scores between the baseline and 1-month visits and baseline and 3-month visits; and to compare subscale scores for PSI-SF (parental stress) and MPOC-56 (satisfaction with care) between the two groups. The Chi-square test was performed to compare adherence between the two groups at 1 and 3-months. The results showed a tendency to greater passive neck rotation (ROM) change at 1-month in the TIB group (95% Confidence Interval = 95%CI = 1.97- 8.77; p=0.17) but not at 3-months. Parents in the the TIB group showed lower global stress scores after receiving the intervention tool (95%CI= 49.20- 57.94; p = 0.01) and reported greater satisfaction than controls in the “coordinated and comprehensive care” (95%CI= 6.7-6.8; p=0.03) and « enabling and partnership » subscales (95%CI= 6.3-6.9; p<0.001). Finally, adherence was higher in the TIB group than controls especially at 3-months (p=0.01). The new Torticollis Intervention Booklet accompanied by physical therapy treatment has a tendency to lead to an earlier restitution of passive neck rotation ROM, may help decrease stress levels, increase satisfaction with treatment, and improve adherence.
7

Stochastic models for the estimation of the seismic hazard / Modèles stochastiques pour l'estimation du risque sismique

Pertsinidou, Christina Elisavet 03 March 2017 (has links)
Dans le premier chapitre, la notion d'évaluation des risques sismiques est définie et les caractéristiques sismotectoniques de la région d'étude sont brièvement présentés. Un examen rigoureux des modèles stochastiques, appliqués au domaine de la sismologie est fourni. Dans le chapitre 2, différents modèles semi-Markoviens sont développés pour étudier la sismicité des îles Ioniennes centrales ainsi que le Nord de la mer Egée (Grèce). Les quantités telles que le noyau semi-Markovien et les probabilités de destination sont évaluées, en considérant que les temps de séjour suivent les distributions géométrique, discrète Weibull et Pareto. Des résultats utiles sont obtenus pour l'estimation de la sismicité. Dans le troisième chapitre un nouvel algorithme de Viterbi pour les modèles semi-Markoviens cachés est construit, dont la complexité est une fonction linéaire du nombre d'observations et une fonction quadratique du nombre d'états cachés, la plus basse existante dans la littérature. Une extension de ce nouvel algorithme est développée pour le cas où une observation dépend de l'état caché correspondant, mais aussi de l'observation précédente (cas SM1-M1). Dans le chapitre 4 les modèles semi-Markoviens cachés sont appliquées pour étudier la sismicité du Nord et du Sud de la mer Égée. La séquence d'observation est constituée des magnitudes et des positions d’un tremblement de terre et le nouvel algorithme de Viterbi est mis en œuvre afin de décoder les niveaux des tensions cachés qui sont responsables pour la sismogenèse. Les phases précurseurs (variations des tensions cachées) ont été détectées en avertissant qu’un tremblement de terre pourrait se produire. Ce résultat est vérifié pour 70 sur 88 cas (le score optimal). Les temps de séjour du processus caché étaient supposés suivre les distributions Poisson, logarithmique ou binomiale négative, tandis que les niveaux de tensions cachés ont été classés en 2, 3 ou 4 états. Les modèles de Markov caché ont également été adaptés sans présenter des résultats intéressants concernant les phases précurseurs. Dans le chapitre 5 un algorithme de Viterbi généralisé pour les modèles semi-Markoviens cachés, est construit dans le sens que les transitions au même état caché sont autorisées et peuvent également être décodées. De plus, une extension de cet algorithme généralisé dans le contexte SM1-M1 est présentée. Dans le chapitre 6 nous modifions de manière convenable le modèle Cramér-Lundberg y compris des sinistres négatifs et positifs, afin de décrire l'évolution avec le temps des changements de contraintes de Coulomb (valeurs ΔCFF) calculées pour sept épicentres (M ≥ 6) du Nord de la mer Egée. Formules pour les probabilités de ruine sont définies sous une forme générale. Corollaires sont également formulés pour la distribution exponentielle et Pareto. L'objectif est de mettre en lumière la question suivante qui pose la problématique dans la Sismologie: Au cours d'une année pourquoi un tremblement de terre s’est produit dans une position précise et pas dans une autre position, aux régions sismotectoniquement homogènes ayant valeurs ΔCFF positives. Les résultats montrent que les nouvelles formules de probabilité peuvent contribuer à répondre au problème susmentionné. / In the first chapter the definition of the seismic hazard assessment is provided, the seismotectonic features of the study areas are briefly presented and the already existing mathematical models applied in the field of Seismology are thoroughly reviewed. In chapter 2, different semi-Markov models are developed for studying the seismicity of the areas of the central Ionian Islands and the North Aegean Sea (Greece). Quantities such as the kernel and the destination probabilities are evaluated, considering geometric, discrete-Weibull and Pareto distributed sojourn times. Useful results are obtained for forecasting purposes. In the third chapter a new Viterbi algorithm for hidden semi-Markov models is developed, whose complexity is a linear function of the number of observations and a quadratic function of the number of hidden states, the lowest existing in the literature. Furthermore, an extension of this new algorithm is introduced for the case that an observation depends on the corresponding hidden state but also on the previous observation (SM1-M1 case). In chapter 4, different hidden semi-Markov models (HSMMs) are applied for the study of the North and South Aegean Sea. The earthquake magnitudes and locations comprise the observation sequence and the new Viterbi algorithm is implemented in order to decode the hidden stress field associated with seismogenesis. Precursory phases (variations of the hidden stress field) were detected warning for an anticipated earthquake occurrence for 70 out of 88 cases (the optimal model’s score). The sojourn times of the hidden process were assumed to follow Poisson, logarithmic or negative binomial distributions, whereas the hidden stress levels were classified into 2, 3 or 4 states. HMMs were also adapted without presenting significant results as for the precursory phases. In chapter 5 a generalized Viterbi algorithm for HSMMs is constructed in the sense that now transitions to the same hidden state are allowed and can also be decoded. Furthermore, an extension of this generalized algorithm in the SM1-M1 context is given. In chapter 6 we modify adequately the Cramér-Lundberg model considering negative and positive claims, in order to describe the evolution in time of the Coulomb failure function changes (ΔCFF values) computed at the locations of seven strong (M ≥ 6) earthquakes of the North Aegean Sea. Ruin probability formulas are derived and proved in a general form. Corollaries are also formulated for the exponential and the Pareto distribution. The aim is to shed light to the following problem posed by the seismologists: During a specific year why did an earthquake occur at a specific location and not at another location in seismotectonically homogeneous areas with positive ΔCFF values (stress enhanced areas). The results demonstrate that the new probability formulas can contribute in answering the aforementioned question.
8

Kan 20 minuter massage i hemmet bidra med stressreducering hos kärlekspar?

Almqvist Berglund, Joy, J Heikkilä, Linnea January 2021 (has links)
Syftet med denna studie var att ta reda på om en kortare massage i hemmet kan bidra med stressreducering hos kärlekspar och om en instruktionsvideo för att lära ut massage kan vara en bra metod. En kvalitativ och kvantitativ ansats har använts, även kallat mixed methods. Deltagarna var 18 personer, som alla ingick i kärleksrelationer. Inledningsvis fick de titta på en inspelad kort informationsvideo om massage för att sedan med stöd av en inspelad 20 minuter lång instruktionsvideo massera varandra på rygg och nacke. Före och efter att de gett och fått massage, skulle de också svara på en webbenkät. Resultaten från enkäten visade att stressnivån sjönk hos både de som gett (p=0,0463) och de som fått (p=0,001) massage. Av de som fått massage kände alla sig avslappnade efteråt och majoriteten (83,3%) kände sig lugna. De som gett massage kände sig även de mer lugna (77,8%) efteråt. Ingen av deltagarna uppgav att de kände sig stressade efter massagen. En instruktionsvideo visade sig, genom svaren från webbenkäten, vara en bra metod för att lära ut massage till kärlekspar. / The aim of this study was to find out if a shorter massage at home can contribute to stress reduction in love couples and if an instructional video for teaching massage can be a good method. A qualitative and quantitative approach has been used, also called mixed methods. The participants were 18 people, all of whom were involved in love relationships. Initially, the participants had to watch a recorded short information video about massage and then, with the support of a recorded 20-minute instructional video, massage each other on the back and neck. Before and after giving or receiving a massage, they also had to respond to an online survey. The results from the survey showed that the stress level decreased in both those who gave (p = 0.0463) and those who received (p = 0.001) massage. Of those who received massage, all felt relaxed afterwards and the majority (83.3%) felt calm. Those who gave massages also felt calmer (77.8%) afterwards. None of the participants stated that they felt stressed after the massage. An instructional video proved, through the answers from the web survey, to be a good method for teaching massage to love couples.
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Interactions of Connected Electric Vehicles with Modern Power Grids in Smart Cities

Alghamdi, Turki 10 August 2021 (has links)
In a smart city, it is vital to provide a clean and green environment by curbing air pollution and greenhouse gas emissions (GHGs) from transportation. As a recent action from many governments aiming to minimize transportation’s pollution upon the climate, new plans have been announced to ban cars with gas engines throughout the world. Therefore, it is anticipated that the presence of electric vehicles (EVs) will grow very fast globally. Consequently, the necessity to establish electric vehicle supply equipment (EVSE) in the smart city through public charging stations is growing incrementally year by year. However, the EV charging process via EVSE which is primarily connected to the power grid will put high pressure upon the centralized power grid, especially during peak demand periods. Increasing the power production of power grid will increase the environmental impact. Therefore, it is fundamental for the smart city to be equipped with a modern power grid to cope with the traditional power grid’s drawbacks. In this thesis, we conduct an in-depth analysis of the problem of EVs’ interaction with the modern power grid in a smart city to manage and control EV charging and discharging processes. We also present various approaches and mechanisms toward identifying and investigating these challenges and requirements to manage the power demand. We propose novel solutions, namely Decentralized-EVSE (D-EVSE), for EVs’ charging and discharging processes based on Renewable Energy Sources (RESs) and an energy storage system. We present two algorithms to manage the interaction between EVs and D-EVSE while maximizing EV drivers’ satisfaction in terms of reducing the waiting time for charging or discharging services and minimizing the stress placed on D-EVSE. We propose an optimization model based on Game Theory (GT) to manage the interaction between EVs and D-EVSE. We name this the decentralized-GT (D-GT) model. This model aims to find the optimal solution for EVs and D-EVSE based on the concept of win-win. We design a decentralized profit maximization algorithm to help D-EVSE take profit from the electricity price variation during the day when selling or buying electricity respectively to EVs or from the grid or EVs as discharging processes. We implement different scenarios to these models and show through analytical and simulation results that our proposed models help to minimize the D-EVSE stress level, increase the D-EVSE sustainability, maximize the D-EVSE profit, as well as maximize EV drivers’ satisfaction and reduce EVs’ waiting time.
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Det sociala stödets inverkan på skolrelaterad stress / The effect of social support on school-related stress

Hultmark, Hanna, Kantedal, Julia January 2023 (has links)
Introduktion: Skolrelaterad stress är ett växande folkhälsoproblem som verkar som riskfaktor för unga personers psykiska ohälsa. Prestationer, relationer, krav samt tankar om framtiden beskrivs orsaka skolrelaterad stress. Socialt stöd är en resurs för hälsa och välbefinnande. Stressrelaterade sjukdomar kan leda till ökade samhällskostnader till följd av sjukskrivningar samt utebliven sysselsättning. Syfte: Syftet med studien är att studera det sociala stödets inverkan på skolrelaterad stress hos gymnasieelever i årskurs tre inom Västra Götalandsregionen samt om det skiljer sig åt mellan gymnasieprogram och kön. Metod: I en kvantitativ tvärsnittsstudie rekryterades 168 elever (&gt;18 år) genom ett bekvämlighetsurval. Data samlades in via ett webbaserad enkätformulär och analyserades genom T-test och Chi-Square test samt korstabeller och deskriptiv statistik. Resultat:Den genomsnittliga stressnivån i studiepopulationen är 1.83 på en skala 0–3. Störst andel elever upplever medel stressnivå (48.8%) och det urskiljs skillnader mellan könen ochgymnasieprogrammen. Ledande orsak till skolrelaterad stress anges vara egnaprestationskrav (58%) och det finns en korrelation mellan prestationskrav och stressnivå. Vidare uppger 23.2% vara omedvetna om stöd i skolan och det finns skillnader mellan gymnasieprogrammen. Slutsats: Studien ger indikatorer på att skolrelaterad stress är ett växande problem och framtida forskning bör undersöka bakomliggande orsaker till elevers egna höga prestationskrav, detta i syfte att förebygga stress samt främja elevers hälsa och välbefinnande. / Introduction: School-related stress is a growing public health problem that acts a risk factor for mental illness in young people. Achievements, relationships, demands and thoughts about the future have been described as causes of school-related stress. Social support is a resource for health and wellbeing. Stress-related illness can increase the social costs because of sick leave and unemployment. Aim: The aim of the study is to investigate the impact of social support on school-related stress in third-year secondary school students in Västra Götalandsregionen and whether it differs between secondary school programs and gender. Methods: In a quantitative cross-sectional study, 168 students (&gt;18 years) where recruited through a convenience sample. Data were collected through a web-based questionnaire and analyzed using T-test and Chi-Square tests as well as crosstabulations and descriptive statistics. Results: The average stress level in the study population is 1.83 on a scale 0-3. The largest percentage of students (48.8%) experience a medium level of stress and there are differences between the sexes and the secondaryschool programs. The leading cause of school-related stress is reported to be individual performance expectations (58%) and there is a correlation between performance expectations and stress level. Furthermore, 23.2% state that they are unaware of support at school and there are differences between the secondary school programs. Conclusion: The study provides indicators that school-related stress is a growing problem and future research should investigate underlaying reasons for the students’ individual highperformance expectations with the aim of preventing stress and promoting health and wellbeing.

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