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1
Blyžienė, Alevtina. « Mokytojų stresas ir jo valdymo metodų reikšmė ugdymo procesui ». Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080904_110456-98414.
Texte intégralRésumé :
Tyrimo aktualumas. Ne tik Lietuvoje, bet ir kitose šalyse mokytojo profesija netenka prestižo dėl didelės įpareigojančios etinės atsakomybės, informacinio ir fizinio krūvio, socialinių vaidmenų konfliktų, kurie sukelia išsekimą ir profesinį „perdegimą“. Anksčiau atliktuose tyrimuose mokytojų streso valdymo metodai nebuvo nagrinėjami.
Tyrimo problema. Mokytojai dėl savo darbo specifikos nuolat patiria psichinį, fizinį, emocinį stresą, kuris daro įtaką ugdymo proceso kokybei.
Tyrimo objektas. Mokytojų streso valdymo metodai.
DARBO TIKSLAS. Atlikti mokytojų streso ir jo valdymo metodų analizę.
UŽDAVINIAI
1. Apibūdinti streso sąvoką pedagogikoje .
2. Įvardinti mokytojų streso įtaka ugdymo procesui
3. Numatyti mokytojų streso valdymo galimybes.
4. Empiriškai ištirti mokytojų stresą ir jo valdymo metodus.
Tyrimo klausimas. Ar mokytojai naudoja streso valdymo metodus savo darbe.
Teorinis darbo pagrindimas. Teorinėje darbo dalyje aptariami mokytojo profesijos ypatumai, mokytojo streso įtaka ugdymo kokybei, mokyklos baimių fenomenas, streso šaltiniai mokytojo darbe, pateikiami mokslinėje literatūroje rekomenduojami mokytojų streso valdymo metodai ir pabrėžiamas mokyklos streso valdymo kompleksinio sprendimo būtinumas.
Tyrimo radiniai. Empirinio kiekybinio tyrimo rezultatai parodė, kad mokytojai savo veikloje dažniausiai naudoja veiklos planavimo metodus. Tyrimo metu nustatyta streso požymių dažnumo ir streso valdymo metodų koreliacija. Kokybinio stebėjimo metodo metu gauti duomenys... [toliau žr. visą tekstą]Topicality of the study. Not only in Lithuania, but in other countries as well, the teachers job is losing it's prestige because of extremely coercive ethical responsibility, informational and physical load, conflicts in social roles, which result in exhaustion and professional „burn out“. The control methods of the stress of the teachers have not been studied previously. The problem of the study. Because of the specifics of their job, teachers are constantly under mental, physical and emotional stress, which is affecting not only their health and social life, but also their students and the general quality of the process of education. The object of the study. Control methods of teacher's stress. PURPOSE OF THE STUDY. Make an analysis of the teachers' stress and its control methods. GOALS 1. Define “stress” in pedagogy 2. Define the effects of teachers' stress on the process of education 3. Present the options for teachers' stress control 4. Empirically study the teachers' stress and its control methods The question of the study. Are teachers using stress control methods in their work? Theoretical background. Theoretical part of this work discusses the specifics of the teacher's profession, the effects of their stress on the quality of the education process, the phenomenon of school fears, the sources of stress in teacher's job, the methods of stress control for teachers, recommended in scientific literature and emphasises the need for the complex control of stress in the... [to full text]
2
BERTAGNOLI, STEFANO. « Improving robustness and metabolic profile of saccharomyces cerevisiae for industrial bioprocesses ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28926.
Texte intégralRésumé :
The fossil energy resources decrease and climate changes, caused by carbon dioxide (CO2) emissions, have led most industrialized countries to undertake policies aimed at the development and use of renewable energy sources. Among the renewable energies, vegetal biomasses play a key role because widely available and potentially able to cover up to 200% of the global energy demand. Vegetal biomasses can be used mainly as raw materials for the production of chemicals, biofuels and energy, in the increasingly important green economy concept based on biorefineries creation. Although the vegetal biomasses result widely available, rising costs of food raw material such as wheat, corn and sugar beet have raised a serious ethical problem using these resources. To avoid the use of such raw materials, the exploitation of lignocellulosic biomasses plays a fundamental role in the industry. However, for an efficient utilization of lignocellulosic biomasses, new technologies are required in order to transform the starting biomass into simple molecules, such as pentoses and hexoses sugars, more easily to use by the microrganism, which will have the task of producing both fine chemicals and bulk chemicals in an economically and environmentally sustainable processes. In this regard, industrial biotechnologies should be able to develop new microrganisms capable to face the harsh environmental conditions that occur during an industrial production process. For many of these productions the yeast Saccharomyces cerevisiae is largely used, not only because of its naturally ability to produce large ethanol amount, but also is widely known both at genetic and metabolic level, outlining a good starting point for the development of producers strains with high tolerance against different stresses occur during an industrial process. This is the view adopted by NEMO project (Novel high performance Enzymes and Microrganisms for conversion of lignocellulosic biomass to ethanol), belonging to the European Union seventh framework program, where it become of primary importance the development of microrganisms, especially S.cerevisiae, for the second generation ethanol production. Microrganisms must be, on the one hand able to efficiently utilize all the sugars released from lignocellulosic biomass pre-treatment, on the other hand should be more tolerant against process conditons, such as inhibitory compounds and environmental stresses.
A point of relevant importance is the ability to utilize pentose sugars, like D-xylose, released in large amount after lignocellulose pre-treatment. Currently, worldwide researches are focused on the development of yeast strains engineered with xylose degradation pathways involving the pentose phosphate pathway. In fact the fungal pathway exploits xylose reductase and the xylitol dehydrogenase while the bacterial pathway exploits xylose isomerase; both pathways degrade D-xylose into D-xylulose, which will enter into pentose phosphate pathway.
In addition to these two pathways studied since the ‘80s of the last century, there also two other poorly known metabolisms, described for the first time in the ‘70s, which produce alpha-ketoglutarate or pyruvate and glycolaldehyde through an oxidative xylose degradation. These pathways are composed of 5 enzymatic reactions by the Weimberg’s pathway and of 4 enzymatic reactions by the Dahms’ pathway, however they share the first 3 enzymatic reactions. After bioinformatics we were identified the presence of Weimberg’s pathway into Burkholderia xenovorans, while the reaction that characterizes the Dahms’ pathway has been identified in Escherichia coli. The encoding genes for these enzymatic activities were expressed in S.cerevisiae, and the capacity to grow on D-xylose as carbon source are evaluated. The reconstruction of these two pathways showed a poorly growth capacity on xylose. Such growth limitation seems to be related to several factors: the presence of bottlenecks associated to enzymes functionality, like D-xylonate dehydratase activity; the yeast ability to internalize xylose efficiently; the involved genes optimization.
Another important aspect is the yeast ability to face and overcome environmental stresses encountered during an industrial process. The cytoplasmic membrane plays a key role in cellular homeostasis, being at the interface between the cell and the external environment, and reacting at environmental changes. The plant membrane protein TIL gives particular strength to the yeast cells when these are subjected to environmental stresses of industrial relevance, such as the presence of oxidative agents or during temperature changes. However, when TIL is expressed in an industrial and/or in an engineered laboratory strains, for industrial use, the protective effect against prolonged stress exposure and process conditions disappear.
Finally, a further important aspect during an industrial process is the S.cerevisiae ability to tolerate the growth inhibitory compounds presence into pre-treated lignocellulose. In fact has been largely described how chemical compounds like aldehydes, organic acids and phenolic compounds, released during lignocellulose pre-treatment process, are toxic at certain concentration, inhibiting S.cerevisiae growth or causing yeast death. The growth performance of different wild type or engineered yeast strains are evaluated on spruce and giant cane lignocellulose pre-treated: in addition the same strains were tested on minimal formulated medium according to the spruce pre-treated composition. The results showed that the combination of low pH and the presence of organic acids, especially acetic acid and formic acid, are dramatically harmful for growth of both industrial strain, naturally more tolerant, and engineered strain, for the production and recycle of L-ascorbic acid. However, the behavior of engineered strain for production and recycle of L-ascorbic acid is interesting at low pH, because showed higher tolerance than other strains in terms of growth rate and ethanol production and productivity.
Despite the positive results obtained by engineering microrganisms, especially S.cerevisiae, in laboratory, their industrial uses still remain limited. Therefore, appears extremely important the construction of more robustness strains, able to withstand different environmental conditions along an entire industrial process, with consequent influence on yields, production and productivity. For these reasons, the research is aimed to combine these aspects to provide the best microrganism possible to industry productions.
3
Wang, Gongbing 1944. « Size effect on damage in progressive softening process for simulated rock ». Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276886.
Texte intégralRésumé :
In the hierarchical approach of constitutive modelling, the damage accumulation and resulting strain-softening behavior of geologic materials can be modelled by introducing a concept of damage evaluation. The damage accumulation and softening behavior are affected by the size of specimens. A series of uniaxial tests on cylindrical specimens of a simulated rock were performed. The effect of specimen size on the parameters of the damage model were investigated by using the test results. The empirical results show that the damage parameters can be related to a characteristic dimension, which was expressed in terms of length and diameter of the specimen.
4
Ana, Genc. « Relacije između stres-procesa i ispitne anksioznosti – distorzije u sećanjima na emocije iz prošlih stresnih transakcija ». Phd thesis, Univerzitet u Novom Sadu, Filozofski fakultet u Novom Sadu, 2014. http://www.cris.uns.ac.rs/record.jsf?recordId=90694&source=NDLTD&language=en.
Texte intégralRésumé :
Disertacija je usmerena na dva glavna istraživačka pitanja: na ispitivanjesloženih međuodnosa varijabli relevantnih za fenomen stres-procesa u kontekstuispitne anksioznosti i na istraživanje grešaka u sećanjima na emocije, misli iponašanja iz konkretne prošle stresne transakcije. Teorijsku bazu rada predstavlja uovoj studiji revidirana verzija modela Tejlora i Aspinvala (The Taylor and AspinwallModel, 1996), koji podrazumeva sveobuhvatan i savremen konceptualni okvir zarazumevanje komponenti generičkog pojma stresa i njihovih međusobnih relacija.Ovde validirani model obuhvata četiri grupe promenljivih: a) stresor (ispitnaanksioznost), b) suočavanje sa stresom (tri kategorije mehanizama prevladavanja:suočavanje usmereno na zadatak, suočavanje usmereno na emocije i izbegavanje), c)karakteristike ličnosti (optimizam i generalna samoefikasnost kao internalni resursi zasuočavanje sa stresom, i dve stabilne osobine ličnosti, relevantne za domenakademskog života: perfekcionizam i neuroticizam), i d) izlazne varijable stresprocesa(uspeh postignut na kolokvijumu i emocionalno stanje studenata neposrednonakon ispitne situacije).Istraživanje je sprovedeno na prigodnom uzorku od ukupno 263 studenata,koji pohađaju studije psihologije i germanistike na Filozofskom fakultetu u NovomSadu. Nacrt istraživanja koncipiran je na način, koji je omogućio prikupljanjepodataka u dva distinktivna vremena merenja: neposredno pre i odmah nakonpolaganja kolokvijuma, te mesec dana posle ove ispitne situacije. Ispitivanje prostoravarijabli stres-procesa obavljeno je primenom sledećih mernih instrumenata: upitnikza procenu ispitne anksioznosti (TAI), inventar za registrovanje načina suočavanja sakognitivnim zadacima (CITS), upitnik za merenje perfekcionizma (APS-R), skaladispozicionog optimizma (LOT-R), skala generalne samoefikasnosti (GSE), subskalaneuroticizma iz „Big Five” inventara ličnosti i upitnik za procenu pozitivnog inegativnog afektiviteta (SIAB-PANAS).Dobijeni rezultati, koji su proizišli iz razmatranja prve grupe istraživačkihpitanja, sugerišu da mehanizmi suočavanja usmereni na emocije predstavljajustatistički značajne medijatore relacija, koje postoje između visine izraženosti ispitneanksioznosti, s jedne strane, i uspeha na kolokvijumu i emocionalnog stanja ispitanikaneposredno nakon ispitne situacije, s druge strane. Nadalje, u radu su detaljnoprikazani i prodiskutovani specifični uslovi, pod kojima određeni nivo razvijenosti ispitivanih moderator varijabli (optimizam, generalna samoefikasnost, neuroticizam itri podvrste perfekcionizma) značajno menja sledeće relacije: a) ispitna anksioznost –izbor strategija za suočavanje, b) primenjeni mehanizmi prevladavanja – ishodiispitivane stresne transakcije i c) direktna veza između stresora i izlaznih varijabli.Prilikom ispitivanja memorijskih distorzija, ustanovljeno je da su studentigeneralno skloni naknadnom potcenjivanju jačine sopstvene ispitne anksioznosti, kojaje postojala u realnoj situaciji polaganja kolokvijuma, kao i precenjivanju pozitivnihishodnih emocija. Nalazi takođe sugerišu da osobina neuroticizma i uspeh postignutna testu znanja nisu u značajnoj meri delovali na greške u sećanju na osećanja izprošle stresne transakcije. Na posletku, utvrđeno je da su ispitanici relativno tačnoevocirali sećanja na primenjene strategije suočavanja, koje spadaju u kategorijeprevladavanja usmerenog na zadatak i izbegavanje, dok su potcenili jačinu i učestalostkorišćenja mehanizama suočavanja usmerenih na emocije.The thesis is focused on two main research issues, as follows: examination ofcomplex interrelationships among variables relevant to the phenomenon of the stressprocessin the context of test anxiety and study of distortions in the memory foremotions, thoughts and behavior in a particular previous stressful transaction. Thetheoretical basis of the thesis presented in this study is a revised version of the Taylorand Aspinwall model (The Taylor and Aspinwall Model, 1996), which includes acomprehensive and contemporary conceptual framework for understanding thecomponents of a generic phenomenon of the stress concept and their mutual relations.The validated model includes four sets of variables: a) stressor (test anxiety), b)coping (three categories of coping mechanisms: task-focused coping, emotion-focusedcoping, and avoidance), c) personality traits (optimism and general self-efficacy asinternal resources for coping, and two stable personality traits relevant to the domainof academic life: perfectionism and neuroticism), and d) the output variables of thestress-process (success achieved at the colloquium and the emotional state of studentsimmediately after the test situation).The research was carried out on a sample of 263 students of Psychologystudies and German Language and Literature studies at the University of Novi Sad.The research design enabled data collection within two distinct times of measurement:immediately before and immediately after passing the colloquium (test), and a monthafter the test situation. Examination of the stress-process variable space was carriedout by application of the following measuring instruments: Test Anxiety Inventory(TAI), Coping Inventory for Task Stress (CITS), The Almost Perfect Scale-Revised(APS-R), Life Orientation Test-Revised (LOT-R), General Self-Efficacy Scale (GSE),the neuroticism subscale from the "Big Five" personality inventory, and the Serbianadaptation of the Positive and Negative Affect Schedule (SIAB-PANAS).The obtained results, which have emerged after reviewing the first set of theresearch questions, suggest that emotion-focused coping mechanisms are significantmediators of relations, which exist between the intensity of the test anxiety on onehand, and success achieved at the colloquium and the emotional state of subjectsimmediately after the test situation, on the other hand. Furthermore, the thesis presentsin details and discusses specific conditions under which a certain level of theexamined moderator variables (optimism, general self-efficacy, neuroticism, and three subtypes of perfectionism) significantly change the following relations: a) test anxiety– a choice of coping strategies, b) applied coping mechanisms - outcomes of theexamined stressful transaction and c) a direct relationship between stressors andoutput variables.When examining memory distortions, it was found that students generallytended to subsequently underestimate the strength of their own test anxiety, whichexisted in the real situation of taking the test, as well as to overestimate positiveoutcome emotions. The findings also suggested that the neuroticism trait and thesuccess achieved on the test were statistically not significant for distortions inmemory, and feelings from the previous stressful transaction. Finally, it was foundthat the subjects relatively accurately evoked memories of the applied copingstrategies, which fell into the category of the task-focused coping and avoidance, andunderestimated the strength and frequency of application of emotion-focused copingmechanisms.
5
Zelenka, Stefan. « Stress-related problems in process simulation / ». Zürich, 2001. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14220.
Texte intégral
6
Hanna, Carl Robert. « Engineering Residual Stress into the Workpiece through the Design of Machining Process Parameters ». Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19813.
Texte intégralRésumé :
The surface integrity of a machined component that meets the demands of a specific application requirement is defined by several characteristics. The residual stress profile into the component is often considered as the critical characteristics as it carries a direct effect on the fatigue life of a machined component.
A significant amount of effort has been dedicated by researchers to predict post process stress in a workpiece using analytical, experimental, and numerical modeling methods. Nonetheless, no methodology is available that can express the cutting process parameters and tool geometry parameters as functions of machined residual stress profile to allow process planning in achieving desired residual stress profile.
This research seeks to fill that void by developing a novel approach to enable the extraction of cutting process and tool geometry parameters from a desired or required residual stress profile. More specifically, the model consists in determining the depth of cut, the tool edge radius and the cutting forces needed to obtain a prescribed residual stress profile for an orthogonal machining operation. The model is based on the inverse solution of a physics-based modeling approach of the orthogonal machining operation and the inverse solution of the residual stress prediction from Hertzian stresses. Experimental and modeling data are used to validate the developed model. The work constitutes a novel approach in engineering residual stress in a machined component.
7
Wani, Nitin Yashwant. « Simulation of thermal stresses in vacuum arc remelting process ». Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178820121.
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8
Proudian, Joanne. « Simulating Residual Stress in Machining ; from Post Process Measurement to Pre-Process Predictions ». Thesis, KTH, Industriell produktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103003.
Texte intégralRésumé :
Metal cutting is a widely used manufacturing technique in the industry and has been the focus of many research and studies in both academic and industrial fields. Prediction of induced residual stresses in a machined component is essential in a component’s fatigue life and surface integrity approximation. Furthermore, it plays a significant role in optimizing cutting process conditions as well as cutting tool geometries. Research has found that using experimental techniques in measuring residual stresses in a machined component is both time consuming and expensive as a method. In the attempt of eliminating the post process measuring drawbacks, the finite element modeling and simulation has proven its efficiency, as a tool, in predicting mechanical and thermal variables, hence, providing a pre-process prediction of variables which may prevent future component failures. This thesis uses the finite element method to study, model and simulate orthogonal metal cutting using the commercial software DEFORM. Orthogonal cutting simulations of 20NiCrMo5 steel are performed and simulation results are validated against experimental data. The influence of the feed rate, cutting speed and rake angle variations on the induced residual stress are investigated and analyzed. Simulation results offer an insight into cutting parameters and tool geometry influence on the induced residual stresses. Based on the simulation results, cutting speed and rake angle showed a trend when varying the parameters on the induced residual stress; however more investigation is needed in determining a trend for the feed rate influence.
9
Donovan, Christie. « Exploring the stress process in the university context ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0006/MQ34883.pdf.
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10
Serido, Joyce. « Appraisal and interpersonal stressors : Untangling the stress process ». Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280448.
Texte intégralRésumé :
To understand variations in the stress response, two separate research traditions have developed: one that focuses on appraisal and the other on stressors. Research on stressors informs our understanding of the social conditions that expose individuals to potentially stressful situations, whereas research on appraisal informs our understanding of why different people respond to stressors in different ways. The present study seeks to integrate findings from these two research traditions and extend our understanding of the stress process by investigating the possibility those variations in sources of stress trigger different appraisals. In addition, this study also attempts to untangle the separate effects of appraisal and stressor by examining each construct at a more granular level than has previously been undertaken. Finally, this study examines the relationships between stressors and appraisal to understand how they may, in combination, influence distress. The data for these analyses are merged from the National Survey of Midlife Development in the United States (MIDUS) and the National Study of Daily Experiences (NSDE). The MIDUS participants are a representative sample of 3032 adults aged 25 to 74 obtained through a random-digit dialing process. The NSDE participants are a subsample of 1031 participants from the MIDUS. The participants for the present study are the 534 men and women who participated in the NSDE who experienced at least one interpersonal tension during the 8-day telephone diary. Results from multilevel modeling analyses indicated that there was more within-person variability in appraisal of interpersonal tensions than between-person variability. Findings from this study also provide empirical support that stressors and appraisal are separate constructs with independent effects on distress. Further, there are multiple pathways through which dimensions of appraisal and attributes of the stressor in combination influence distress.
11
黃浪詞 et Long-chi Rinna Wong. « Using process research to identify stress-alleviating helpful events in stress inoculation training ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31976797.
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Irwin, Jay A. « Stress and support among Southern lesbians an application of the stress process model / ». Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2009p/irwin.pdf.
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Moyle, Penelope Jane. « The stress process in occupational settings : the role of psychosocial factors ». Thesis, University of Oxford, 1995. http://ora.ox.ac.uk/objects/uuid:fab0dbb4-7012-42ba-92b4-c63d72d6b078.
Texte intégralRésumé :
This thesis is concerned with the direct and indirect mechanisms through which psychosocial stressors affect well-being, within the framework of the Michigan Model (House, 1981). An additional aim is to examine the stress process during workplace transitions. Empirical studies were conducted in three occupational settings: a cross-sectional pilot study with a sample of white-collar employees of several companies (N=144), and two longitudinal studies with samples drawn from a single retail chain, the "manager study" (N=261) and the "relocation study" (N=175). Although statistical control for individual differences (including response style) attenuated associations between work characteristics and strain outcomes, in all three samples work characteristics jointly contributed to the explanation of job satisfaction and psychological distress. More specifically, perceptions of control and social support were associated with job satisfaction, while work demands played a significant role in explaining symptom report. Furthermore, symptom levels predicted work absence in a combined sample of retail employees (N=221). In addition to direct effects, mediation and moderation patterns were examined. Results suggested that work perceptions partially mediated relations between personality (specifically locus of control beliefs and neuroticism) and strain. A similar pattern of mediation was apparent for social support. However, evidence for moderation of the stress process by individual and work characteristics was equivocal. Cross-sectional analyses using the manager sample data revealed significant interactions of control and Type A behaviour with work characteristics, but these interactions were not consistent in form with theory and past research. In contrast, in the longitudinal relocation study interactions were consistent with expectations: the negative impact of change was buffered by social support from senior colleagues and perceptions of control. Longitudinal analyses also demonstrated negative effects of workplace change; decreasing job satisfaction was observed during organisational restructuring, and transfer to a new branch was associated with increased psychological distress. Furthermore latent variable models revealed that changes in support, role ambiguity, and control over time were predictive of changes in job satisfaction. Overall, the present studies emphasise the need to examine simultaneously the joint influences of individual and work characteristics in occupational stress research. In this way the direct and indirect mechanisms through which psychosocial factors influence strain may be more fully understood, and strain-reducing interventions devised.
14
Myers, Matthew. « Investigating process stresses on Saccharomyces cerevisiae using isothermal microcalorimetry ». Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25435.
Texte intégralRésumé :
Maximising performance of microbial processes, including yeast-based processes, in an industrial setting requires understanding of the impact of process stresses. These may be the result of process configuration, dilution, temperature changes, hydrodynamic conditions or process perturbations. Methods to determine the microbial metabolic response to such stresses have long been sought, but are typically limited, often requiring the use of a suite of methods to assess the physiological status and state. The recent technical advances in microcalorimetry suggest potential for the use of isothermal microcalorimetry (IMC) to determine yeast viability and vitality and is investigated here. IMC is a laboratory method whereby the real-time heat produced by a chemical, biological or physical process is measured in the micro to nano watt range. It is proposed that this heat production may be correlated to the physiological state of the microbial catalyst and can be used to measure the impact of different stresses. In this study, the potential of IMC as a method for exploring process stress is investigated using Saccharomyces cerevisiae and its application in the beer brewing industry as a case study. Here, it is well known that yeast viability and vitality have commercial significance. IMC is sufficiently sensitive to detect the heat given off by 1000 yeast cells. However, IMC cannot distinguish between different heat flows within a system i.e. it is non-specific. The literature demonstrates how IMC has been used in the study of numerous microbiological fields, including the growth and metabolism of yeast. Previous studies have successfully derived the specific growth rate and cell numbers of a growing yeast population from analysing power and heat curves. The specific growth activity and specific growth retardation of yeast and how these parameters relate to bactericidal and bacteriostatic effects has also been examined by a number of authors. The key objectives of this study were to determine the viability and vitality of Saccharomyces cerevisiae using IMC and to assess the impact of stresses on yeast viability and vitality. This was achieved by measuring the thermal power produced by a growing yeast suspension as a function of its overall growth and metabolism. Two industrially relevant stresses were examined: cold shock and ethanol shock. The effect of these stresses has yet to be studied using microcalorimetry. The growth of Saccharomyces cerevisiae under ethanol stress was used as an inhibition study to isolate its effects on the growth thermogram. Following the generation of thermograms under control and stress conditions using IMC, a method for their quantitative analysis was developed. Curves were fitted to the heat data using an exponential growth equation and the time for the heat flow curve to peak was determined. From the exponential curve, the specific growth rate of the yeast was determined with a high degree of repeatability. The coefficient of the exponential term in the growth equation gave highly reproducible and distinguishable results relating to the viability and vitality of the initial yeast population. The time of peak heat flow was also affected by the initial viability and vitality of the yeast and was used to estimate the initial active cell population size.
15
Dasgupta, Mitul. « Design Against Stress : Design's methodological approach of dealing with the issue of stress ». University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282317515.
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Dogu, Doruk. « Finite Element Modeling Of Stress Evolution In Quenching Process ». Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12606917/index.pdf.
Texte intégralRésumé :
In this thesis the finite element computer code QUEANA simulating the quenching of axisymetric parts and determining the residual stress state was improved by adding pre- and post-processors. The code was further verified by additional numerical experiments and comparison of the results with commercial software &ldquoMARC&rdquo
. The possible applications of this code are optimization of industrial quenching processes by controlling the evolution of internal stresses and dimensional changes.
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Butters, Jennifer Ellen. « Understanding adolescent cannabis use, a stress process model application ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ59074.pdf.
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Dykstra, Richelle. « Emotion Management and Well-Being : A Stress Process Approach ». University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1321307618.
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Gary, Katharine Marie Gary. « Sexual Stigma and Mental Health : A Stress Process Approach ». Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1528550901560843.
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Fabbro, Lucian Del. « Avaliação do efeito do flavonoide crisina na toxicidade induzida pela zearalenona em camundongos ». Universidade Federal do Pampa, 2014. http://dspace.unipampa.edu.br:8080/xmlui/handle/riu/283.
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As micotoxicoses ocorrem através do consumo de alimentos contaminados, sendo uma questão de saúde pública em todo o mundo. A contaminação dos alimentos depende de crescimento fúngico, além de condições climáticas ideais para o desenvolvimento das micotoxinas. A ingestão de micotoxinas por seres humanos ocorre principalmente pela ingestão de produtos vegetais contaminados, bem como pelo consumo de produtos derivados destes alimentos. A Zearalenona (ZEA) é uma lactona do ácido fenólico resorcílico e pode ser produzida por várias espécies de Fusarium, sendo que Fusarium graminearum, proliferatum e culmorum são os principais produtores. A ZEA é um composto estrogênico, cujo os efeitos tóxicos e seus metabólitos têm sido atribuídos principalmente à sua estrutura química semelhante a dos estrógenos naturais. O sistema reprodutivo é um dos principais alvos de toxicidade da ZEA, sendo os órgãos reprodutores, como útero, ovários e testículos os principais órgãos afetados. Frente a esta problemática, o estudo de substâncias naturais capazes de prevenir tal micotoxicose se faz necessária. A crisina é um flavonoide da classe das flavonas. Possui hidroxila livre nos carbonos 5 e 7 do anel, está presente em níveis elevados no maracujá do mato, mel e no própolis. Possui conhecidos efeitos benéficos como atividades antioxidante e anti-inflamatória, além de aumentar níveis de testosterona. Este estudo teve por objetivo avaliar o efeito protetor da crisina frente aos efeitos tóxicos da micotoxina ZEA nos testículos de camundongos Swiss. Para isto, os camundongos foram tratados durante 10 dias consecutivos com crisina (5 e 20 mg/Kg, via gavagem), no 11° dia os animais receberam uma dose de ZEA (40 mg/Kg, via gavagem). Após 48 horas, os animais receberam uma dose de pentobarbital (180 mg/Kg, intraperitoneal, i.p.) e o sangue foi coletado por punção cardíaca e os testículos removidos, pesados e homogeneizados em tampão para as determinações dos níveis de testosterona, contagem e avaliação da motilidade dos espermatozoides, determinação de indicadores de estresse oxidativo por métodos colorimétricos: catalase (CAT), superóxido dismutase (SOD), glutationa peroxidase (GPx), glutationa redutase (GR), glutationa-S-transferase (GST) e não enzimáticos glutationa reduzida, TRAP (capacidade de reatividade antioxidante total) e TAR (capacidade antioxidante total) e 4-Hydroxynonenal (4-HNE). Foram determinados interleucinas (IL-1β, IL6 e IL10), o fator de necrose tumoral alfa (TNF-α) e a enzima mieloperocidase (MPO). Foram determinados parâmetros apoptóticos, as atividades das Caspases 3 e 6 além de dos níveis de 8-hydroxy-2'-deoxyguanosina (8-OHdG). O tratamento com crisina reverteu a redução dos níveis de testorenona, da contagem e da motilidade dos espermatozoides. O tratamento com crisina reverteu a inibição das enzimas antioxidantes GPx, GR, e GST, além de normalizar os níveis de GSH e 4-HNE. A alteração nos parâmetros inflamatórios causados pela administração de ZEA foi prevenida pela administração da crisina restaurando os níveis xi de IL-1β e IL-6 e TNF-α e reduzindo os níveis de IL-10 e a atividade da MPO. O tratamento com crisina atenuou os danos apoptóticos causados pela ZEA, inibindo a atividade das caspases 3 e 6 e reduzindo os níveis de 8-OHdG. Desta forma o tratamento com crisina preveniu os danos causados pela micotoxina ZEA em camundongos swiss através da modulação do estresse oxidativo, acarretando em uma redução do processo inflamatório e consequentemente apoptótico. Desta forma espera-se que a crisina possa vir a ser um possível tratamento auxiliar no combate a micotoxicoses seja em humanos ou animais.
Ace mycotoxicoses occur through the consumption of contaminated food being a public health issue worldwide. Contamination of food depends on fungal growth beyond the ideal climatic conditions for the development of mycotoxins. The ingestion of mycotoxins by humans occurs primarily by ingestion of contaminated plant products, as well as the consumption of food products derived therefrom. Zearalenone (ZEA) is a phenolic resorcylic acid lactones and can be produced by various Fusarium species, and Fusarium graminearum, culmorum and proliferatum are the main producers. ZEA is an estrogenic compound, whose the toxic effects and its metabolites have been mainly attributed to their similar chemical structure of natural estrogens. The reproductive system is one of the main targets of toxicity of ZEA and the reproductive organs such as the uterus, ovaries and testes those most affected organs. Faced with this problem, the study of natural substances capable of preventing such mycotoxicosis is required. Chrysin is a flavonoid of the flavones class. It has free hydroxyl at carbons 5 and 7 ring, is present at high levels in passion fruit bush honey and propolis. Chrysin has known beneficial effects as an antioxidant activities and anti-inflammatory and it has increased testosterone levels. This study aimed to evaluate the protective effect of chrysin forward to the toxic effects of the mycotoxin ZEA in the testes of Swiss mice. For this, the mice were treated for 10 consecutive days with chrysin (5 and 20 mg / kg by gavage) on day 11, the animals received ZEA, a dose (40 mg / kg by gavage). After 48 hours, the animals received an overdose of pentobarbital (180 mg / kg, intraperitoneal, i.p.) and blood was collected by heart puncture and removed, weighed and homogenized testis for determination of testosterone, count and assessment of sperm motility, determination of oxidative stress indicators by colorimetric methods: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and non-enzymatic reduced glutathione, TRAP (reactivity total antioxidant capacity) and TAR (total antioxidant capacity) and 4-hydroxynonenal (4-HNE). Were determined, interleukins (IL-1β, IL-6 and IL-10), tumor necrosis factor (TNF-α) and mieloperoxidase enzyme (MPO). Apoptotic parameters were determined, Caspases 3 and 6 beyond the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG). The treatment with chrysin reversed the reduction of testorenone levels, count and motility of sperm. Treatment with chrysin reversed the inhibition of antioxidant enzymes GPx, GR, and GST, as well as normalizing levels of GSH and 4-HNE. The alteration in inflammatory parameters caused by the administration of ZEA was xiii prevented by administration of chrysin, restoring IL-1β and IL-6 and reducing IL-10 levels, and reduce TNF-α levels and MPO activity. Treatment with chrysin attenuated apoptotic damage ZEA, inhibiting the activity of caspases3 and 6, reducing levels and 8-OHdG. Thus, the treatment with chrysin prevented the damage caused by mycotoxins ZEA in Swiss mice probably through modulation of the oxidative stress, resulting in a reduction of the inflammatory process and hence apoptosis. Thus it is expected that chrysin may be a possible treatment support combat in mycotoxicosis both in humans and animals.
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Palaniappan, Prema. « In-process stress analysis of flip chip assemblies during underfill cure and environmental stress testing ». Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19138.
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Engström, Frida. « Stress, kreativitet och problemlösning : En kvalitativ studie i hur vi löser problem under stress och vad detta kan innebära för designprocessen ». Thesis, Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-18121.
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Problem solving is a big part of design, however a lot of emphasis is put on creativity in research related to the effects of stress. Research has shown that the amount of stress we feel affects idea generation. Stress may also affect the ability to solve problems, however the researchers don’t seem to agree about what the effect of stress actually does. The study was made through experimental sessions where the respondents were asked to solve 4 matchstick puzzles of similar difficulty. Depending on their outcome they experienced more or less stress. They all experienced greater amounts of stress in the puzzles that took them longer times to figure out. Along with the experimental sessions, I also interviewed the respondents about their personal relationship with problem solving in their daily and professional life. I found that problem solving is intertwined and compounded with creativity through both problem solving being a part of the creative process, and problem solving needing the creative elements to generate ideas for solutions. But more than anything the study showed that problem solving in fact could be a stress trigger.
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Karasan, Mustafa Murat. « Residual Stress Analysis Of Riveting Process Using Finite Element Method ». Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608997/index.pdf.
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Rivets are widely used as a means of fastening in airframe construction industry. There are various types of riveted joints on an aircraft fuselage or on a helicopter body. Among the other types of fasteners riveted joints are preferred in such applications due totheir permanence after installation and their economical advantages. In a riveted joint, it is known that residual stresses are present as a result of the installation process. Furthermore, during the flight of an aircraft, the fuselage is loaded in one cycle and such cycles are repeated throughout the service life. As a result, the panels and the rivets are subjected to fatigue type loading. The integrity of the joint must be maintained against this combination of service loads and the residual stresses. Hence, the riveting process parameters which influence the residual stresses are utmost critical in terms of fatigue life of the hole body. In this study it is aimed to obtain an accurate numerical model of a single-lap riveted joint which is widely used in airframes. 2-D axisymmetrical and 3-D numerical models are generated using commercial finite element code ABAQUS/CAE and subsequent parametric studies are carried out on these models. The Results of both models are compared with those found in the literature. Clearance between hole and rivet shank is selected as the primary parameter to be inspected. The effects of hole clearance on the final residual stress field are examined on 2-D and 3D models. Furthermore, a through the thickness, crack on the inner panel which is initiated after installation is modeled. The crack is perpendicular to the direction of loading. It is placed to the residual tensile stress zone that surrounds the rivet hole. Hence, the effects of residual stresses are also taken into account. For a riveted joint subjected to fatigue loading, such a macroscopic crack could eventually form. In this thesis, stress intensity factors (SIF&rsquo
s) for this crack are calculated for various parameters such as clearance and crack length. These can be utilized in a subsequent fatigue crack growth analysis as the initial values or they can be used in a fracture analysis, to predict unstable crack growth due to overload (i.e. crack linking).
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Kan, Chui-Chui Flora. « Modelling the behaviour of a process control operator under stress ». Thesis, City University London, 1992. http://openaccess.city.ac.uk/14854/.
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In this study, a framework to model the effects of stress on a process control operator is proposed. There exists many cognitive models, each of which attempts to model a specific class of human behaviour. One major effect of stress is the cause of errors, both physical and cognitive. In order to model the effects of stress, two cognitive models, a cognitive model of human errors and a cognitive model of process control operators are examined in detail. In this thesis, the basic functions of the human cognitive system, its organization and a cognitive model of error commission are first examined. The behaviour of a process control operator and a cognitive model of the behaviour of the operator are then discussed. The known effects of stress on the process control operator's behaviour are described and a framework for modelling the behaviour of process control operators under stress is proposed. The inadequacies associated with existing cognitive models for process control operators are explained and a modified cognitive model is proposed, which takes into account the cognitive model of error. Finally, an architecture design for the implementation of the cognitive model is provided and suggestions for the next step forward are proposed.
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Ehe, Kerstin Anna von der. « Detection of stress during the drying process of polymer dispersions ». Clausthal-Zellerfeld Papierflieger, 2008. http://d-nb.info/993813410/04.
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Banks, Sean R. Almeida David M. « Event-specific control, salivary cortisol, and the daily stress process ». [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4635/index.html.
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Bazel, Teresa L. (Teresa Lorraine) 1965. « Process optimization of plastic injection molding for minimal residual stress ». Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9762.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (p. 67-68).
This thesis summarizes the progress made in developing a procedure to optimize a plastic injection molding process by minimizing the dimensional instability of a critical feature. It documents the steps taken by a development team at the Visteon facility in Belfast, Northern Ireland to apply Design of Experiments (DOE) in process research for the production of a plastic throttle body. The team demonstrated the feasibility of using designed experiments to understand the effects of five main process parameters; melt temperature, injection speed, hold pressure, mold temperature, and cooling time, on the deformation caused by thermal cycle exposure. The experiment results and analysis were successful in establishing a prediction model for the critical dimensions of the component before and after thermal exposure. The prediction model and additional testing indicated that adjustments to the process would reduce the dimensional shift of the bore radius by over fifty percent. The thesis stresses the use of a team approach and the application of analytical methods to better understand the process. The report also includes a brief discussion of the use of Computer Aided Engineering (CAE) techniques to improve the product development process.
by Teresa L. Bazel.
S.M.
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Schillings, Angela Izabel. « Processo de estresse em mestrandos ». Florianópolis, SC, 2005. http://repositorio.ufsc.br/handle/123456789/102851.
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Dissertação(mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em PsicologiaMade available in DSpace on 2013-07-16T02:05:54Z (GMT). No. of bitstreams: 1 221398.pdf: 1595689 bytes, checksum: 5725250443747c8fb825f0ebf99999ec (MD5)
Esta pesquisa buscou identificar fatores estressores entre mestrandos que efetuavam um programa de mestrado na área de Filosofia e Ciências Humanas de uma Instituição de Ensino Superior pública, no sul do país. 54,8% dos mestrandos do Centro de Filosofia e Ciências Humanas responderam ao Inventário de Stress para Adultos de Lipp, de Marilda Novaes Lipp e a um questionário sobre estressores externos, confeccionado para essa finalidade, de acordo com variáveis retiradas da literatura sobre estresse. Os resultados demonstraram a presença de processo de estresse em 62,4% da amostra. A amostra foi composta por quase duas vezes mais mulheres do que homens, sendo uma população eminentemente de adultos jovens, e os índices mais elevados de estresse situaram-se na faixa etária de 26 a 30 anos. A incidência de estresse no sexo feminino foi superior à do sexo masculino. Constatou-se ocorrência de estresse nos mestrandos dos seis programas de mestrado pesquisados, sendo que os índices mais altos ocorreram entre os sujeitos do mestrado em Antropologia Social (73,3%) e os mais baixos entre os mestrandos de Filosofia (46,4%). Os resultados mostram que os relacionamentos estabelecidos pelos mestrandos com seus colegas e professores foram geradores de estresse, pois os índices mais elevados estão entre os alunos que consideraram insatisfatórias essas relações. O tempo para efetuar as leituras do mestrado foi considerado insuficiente pela maioria dos sujeitos e foi maior a incidência de estresse quanto mais insuficiente esse tempo. Foi verificada relação entre processo de estresse e grau de satisfação com as atividades acadêmicas. Conclui-se que nas relações estabelecidas com a família de origem e com as relações de amizade, quanto maior o grau de insatisfação maior a incidência de processo de estresse. Com relação à freqüência das atividades físicas e de lazer o índice de insatisfação também foi elevado e os sujeitos que apresentaram maior nível de insatisfação nesse aspecto apresentaram maior percentual de estresse. Quase metade dos mestrandos possui outra atividade profissional, paralela ao mestrado, e a renda mensal recebida por grande parte dos mestrandos é de até R$1.500,00, sendo que 57,4% ganham até R$1.000,00. Quanto mais insuficiente a renda em relação às necessidades dos mestrandos, maiores os percentuais de processo de estresse. Quanto às fases do processo de estresse constatou-se a predominância da fase de resistência com prevalência de sintomas psicológicos. A pesquisa conclui que existem índices bastante elevados de processo de estresse, podendo gerar reflexos negativos na qualidade de vida da população pesquisada.
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Li, Chun. « Simulation of process induced residual stresses in thick filament wound tubes ». Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272044.
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Niu, Xiaokai. « Process induced residual stresses and dimensional distortions in advanced laminated composites ». [Florida] : State University System of Florida, 1999. http://etd.fcla.edu/etd/uf/1999/amj9744/niu.pdf.
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Thesis (Ph. D.)--University of Florida, 1999.Title from first page of PDF file. Document formatted into pages; contains xi, 149 p.; also contains graphics. Vita. Includes bibliographical references (p. 144-148).
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Jarvis, Ashley Yoder Kevin Allan. « Children of incarcerated parents an application of the stress process model / ». [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3660.
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Trainor, Sarah. « Stress, coping and the illusion of control : a two-process model / ». Title page, table of contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09ARPS/09arpst768.pdf.
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Herbert, Martin. « Evaluating pipeline thermal stress induced by the process of ice pigging ». Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529881.
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Savvas, Michael. « Individual and organisational coping strategies as buffers in the stress process ». Thesis, University of Plymouth, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289572.
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McKay, Jane. « Individual differences and the stress process : the experiences of U.K. athletes ». Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416191.
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Carson, Jerome Francis John. « The stress process in mental health workers : assessment and intervention studies ». Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420885.
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Jarvis, Ashley. « Children of Incarcerated Parents : An Application of the Stress Process Model ». Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3660/.
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The purpose of this qualitative interview study is to examine the lives and experiences children of incarcerated parents from a theoretical perspective through an application of the social stress process. Previous research on children of incarcerated parents has neglected to add a theoretical component to their research, which is the intention of this research. The results will be organized around the theoretical domains of the stress process applied to findings from the analysis of eleven qualitative interviews of mothers and/or caregivers of youth(s) of an incarcerated parent. Guided by analytic induction, the themes that emerged from the transcripts were applied to the theoretical propositions of the social stress process: stressors, mediators, and manifestations. Stressors experienced by children of incarcerated parents include: the incarceration of a parent, financial difficulties, and residential instability. Stress mediators include: coping mechanisms and the importance of maintaining familial ties during parental incarceration. The manifestations or outcomes include: internalizing and externalizing behaviors.
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Burke, Jessica L. « A STRESS PROCESS APPROACH TO EXAMINING INTERRACIAL RELATIONSHIPS AND WELL-BEING ». Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1375039188.
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Biron, Caroline. « Researching process and contextual issues influencing organizational-level work stress interventions ». Thesis, Lancaster University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547959.
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SRINIVASAN, MADHAV. « Finite element simulation of laser shock peening process ». University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204910079.
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Harman, Wendy S. « Interruptions in the goal striving process / ». Thesis, Connect to this title online ; UW restricted, 2006. http://hdl.handle.net/1773/8817.
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Yee, Kuo-chung. « Process-induced residual stresses in a continuously-cured, hoop-wound thermoset composite cylinder : theory and experiments / ». Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Beers, Jeffry Childs. « Teacher Stress and Coping : Does the Process Differ According to Years of Teaching Experience ? » PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/809.
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Teaching is stressful. The demands placed on teachers can result in emotional exhaustion and burnout, causing many to leave the profession. Teachers early in their careers seem to be at special risk, with desistence rates estimated as high as 40% in the first five years. This study was based on the notion that constructive coping can be a resource for teachers, and that teachers later in their professional lives may provide a model for adaptive ways of dealing with professional demands. The goal of the study was to examine whether the coping process utilized by teachers (including reported demands, appraisals, ways of coping, resolutions, and post-coping assessment) differed at different stages of their career. Participants (n = 57) were teachers (90% female) ranging in age from 28-63, teaching in grades 4 to 12. The current study utilized a portion of the baseline open-ended interview of a randomized waitlist control study conducted to explore the effects of a mindfulness-based program. After coding the interview data for each step of the coping process, frequency analyses revealed that: (1) as in previous studies, the most frequently reported demands were problems with students (40%), followed by workload (18%) and parents (15%); (2) the most frequently reported appraisal was extreme negative emotion (44%); (3) the most frequently reported ways of coping were adaptive, including problem-solving (65%), support seeking (35%), and self regulation (22%); (4) the most frequently reported resolution of the stressful episode was successful (51%); and (5) with regards to post coping assessment, teachers most frequently reported that they would do something differently in future episodes if they could (54%). A series of Chi-square analyses to explore whether there is an association between how the teachers responded to questions corresponding to each step revealed that (1) teachers who reported parents as a demand in teaching were more likely to report extreme negative emotion and the use of self-regulation, which was associated with a successful resolution; (2) teachers who reported the administration as a demand were also more likely to use support seeking as a way of coping; and (3) teachers who reported using more maladaptive ways of coping were also more likely to report an unsuccessful resolution. Finally, pairwise comparisons to determine which groups of teachers differed from each other showed that, in keeping with expectations, early career teachers reported "no negative emotion" less and "extreme negative emotion" more than other groups, while late career teachers mentioned "no negative emotion" more. In terms of demands, early career teachers mentioned the environment less whereas late career teachers mentioned parents less and students more often. In terms of coping, late career teachers reported using self-regulation less and cognitive accommodation more than the other groups. Finally, early career teachers were more likely to say that they would try different effective strategies in future coping episodes while late career teachers were less likely to report that they would do so. Applications of these findings are discussed for process-oriented theories of teacher stress and coping, for future studies examining how coping develops over the course of a professional career, and for preservice training and school-based interventions designed to promote adaptive coping for teachers at every phase of their profession.
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Chan, David Tai-Wai. « Analysis of molecular orientation and internal stresses in plastic sheet extrusion process / ». The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487596307358216.
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Keller, Stephanie M. « HOMEWORK ADHERENCE IN PROLONGED EXPOSURE FOR CHRONICPOSTTRAUMATIC STRESS DISORDER ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1413366984.
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Miller, Lynn. « Social-cognitive process in posttraumatic stress disorder in motor vehicle accident survivors ». Thesis, University of Ottawa (Canada), 2000. http://hdl.handle.net/10393/9334.
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Posttraumatic stress disorder (PTSD) is a common sequela in those individuals who survive or witness an event such as a motor vehicle accident (MVA) that may threaten personal and interpersonal integrity. Yet, not all individuals who experience MVAs develop PTSD. It was hypothesized that MVA survivors who developed PTSD would evidence dysfunctional thinking characterized by maladaptive rules, assumptions, and interpretations, or schema specific to road traffic situations. Such dysfunctional thinking patterns were thought to be associated with individuals' perceptions of increased threat in road traffic situations and with PTSD in survivors of MVAs. The study also sought to explore the possible modifying effect that social interactional influences may have on maladaptive schema. In Study 1, a Motor Vehicle-Related Schema (MVRS) questionnaire was developed as A tool to tap the content of a potential dysfunctional thought process germane to road traffic situations. In Study 2, MVA survivors who developed PTSD were compared to MVA survivors who did not develop PTSD. A group of injured workers and a community sample were used as control groups. The control groups allowed the researcher to address the question of specificity of maladaptive schema related to road traffic situations in the MVA PTSD group. Multiple measures were used to assess the presence or absence of PTSD. Participants in the MVA PTSD group endorsed significantly higher levels of dysfunctional and maladaptive cognitions specific to road traffic situations than did all other participant groups. Given that other factors might influence this type of thought process, a number of other variables were examined. The findings remained robust even after adjustment for: (a) persistent dysfunctional schemas tapping general personal and interpersonal vulnerability, (b) subjective pain, and (c) self-reported depression. In addition, MVA survivors who developed PTSD, compared to MVA survivors who did not develop PTSD, reported significantly lower levels of perceived beneficial social interactions. However, these findings became non-significant after adjustment for subjective pain and self-reported depression. Overall, the findings suggest that MVA survivors who developed PTSD organized and interpreted stimuli relevant to road traffic situations in ways that were fundamentally different from MVA survivors who did not develop PTSD, injured workers and a community sample. More specifically, participants in the MVA PTSD group tended to interpret road traffic situations as more threatening than did participants in the other groups in this study. The perception of lower levels of beneficial social interactions appear to be associated more with heightened levels of distress, pain, and depression than with PTSD. This investigation demonstrates that it is possible to tap into maladaptive schemas using a self-report measure. Consistent with cognitive-behavioral clinical protocols for MVA survivors with PTSD, these results support the notion that specific dysfunctional or maladaptive cognitions appear to characterize MVA survivors with PTSD. A better understanding of dysfunctional schemas specific to road traffic situations, gleaned through further research, may be of some benefit in attenuating or managing symptoms of PTSD in WA survivors. Although the injured workers were not the focus of this research, many of the participants in this group met the classification for PTSD or posttraumatic stress symptoms (PTSS). This finding suggests that clinical screening and further research for PTSD in injured workers might also be warranted.
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Haghshenas, Seyed Mehdi. « Integrating resin flow and stress development in process modeling of thermoset composites ». Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43758.
Texte intégralRésumé :
The usual approach to the process modeling of thermoset matrix composites is to divide the analysis into two distinct and sequential steps, first of flow-deformation behaviour and then of stress-deformation. In the current processing models, each of these two aspects is dealt with in a separate sub-model, typically called the flow module and stress module respectively. The flow module is relevant to the pre-gelation behaviour of resin, while the stress module is valid for the post-gelation composite material.
In this thesis, the framework to integrate the flow and the stress modules into a unified module in finite element processing models is presented. The work is based on a two-phase model for analysis of resin flow and its resulting deformations in the composite material. Special measures are introduced to provide for additional capability of this model to account for the development of stresses in the curing composite material. These modifications are needed to ensure the accuracy of the model in both of resin flow and stress development regimes, and include the introduction of consistent compressibility in the mass conservation equation of the two-phase system, and a special decomposition of stresses of the system.
The formulation is implemented for a pseudo-viscoelastic stress model in a 2D plane strain FE code in MATLAB. The approach may readily be extended to fully viscoelastic models. Various examples from single-element problems dealing with the development of residual stresses throughout a single-hold cure cycle to more geometrically complex composite laminates undergoing standard cure cycles are modeled by the integrated model and comparisons are made in one extreme to the flow-compaction behaviour by the standard flow models, and in the other extreme to the results obtained by the pseudo-viscoelastic approach.
The model developed here is a promising tool for simulating processing of large-scale composite structures continuously from the very early stages of the process when the resin behaves in a fluid-like manner all the way to the final stage when it behaves as a 3D solid.
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Linga, Gaute. « The Breaking Process of an Idealized Polymeric Bundle under Applied Tensile Stress ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26873.
Texte intégralRésumé :
We introduce a particle-based model of an idealized polymeric bundle, whose properties are investigated by means of molecular dynamics simulations. We analyse in particular the effect of applying a tensile stress, stretching and eventually breaking the bundle.The simulation results show that, despite its simplicity, the model captures characteristic features of polymeric materials, e.g. a multistage creep and creep ringing. The results indicate that the system evolves in a near-equilibrium state during almost the entire creep process, reflected in the data collapse of the \emph{effective stress--strain} curve.Two distinct variants of the basic model are studied, the first one allowing and the second one disallowing recombination of broken bonds. The former model is observed to undergo a phase transition, taking place at a critical tensile force $F_c$. Below this threshold, the bundle is observed to stabilize, and above the threshold, the bundle breaks down. In both model assumptions, the bundle lifetime $t_f$ seems to exhibit Basquin-like power-law dependence upon the applied force $F$; for the former this is estimated to be $t_f \sim F^{-\gamma}$, with $\gamma = 4 \pm 0.1$. Simulation results follow the same power law over the accessible range in $F$, spanning about half a decade.The elongation difference as a function of normalized time also shows a remarkable data collapse for a range in $F$, hinting to universality in the creep process. Moreover, at imminent failure, the strain rate is shown to grow as $\dot{L} \sim \tau_{\rm ttf}^{-1}$, where $\tau_{\rm ttf}$ is the normalized time-to-failure. This is in excellent agreement with recent experimental findings for a protein gel \cite{leocmach2014creep}.New theoretical approaches are also made to understand the breaking process of a bundle of polymers. In particular, a simple one-step fiber bundle model is proposed. The model may serve to explain the phase transition that was observed for the simulation model that allowed for recombination.
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Choi, Dongwon 1973. « Silicon carbide process development for microengine applications : residual stress control and microfabrication ». Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28348.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references.
The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high speed at elevated temperatures (1300 to 1700 K). However, the thermal softening of silicon (Si) at temperatures above 900 K limits the highest achievable operating temperatures, which in turn significantly compromises the engine efficiency. Silicon carbide (SiC) offers great potential for improved microengine efficiency due to its high stiffness, strength, and resistance to oxidation at elevated temperatures. However, techniques for microfabricating SiC to the high level of precision needed for the microengine are not currently available. Given the limitations imposed by the SiC microfabrication difficulties, this thesis proposed Si-SiC hybrid turbine structures, explores key process steps, identified, and resolved critical problems in each of the processes along with a thorough characterization of the microstructures, mechanical properties, and composition of CVD SiC. Three key process steps for the Si-SiC hybrid structures are CVD SiC deposition on silicon wafers, wafer-level SiC planarization, and Si-to-SiC wafer bonding. Residual stress control in SiC coatings is of the most critical importance to the CVD process itself as well as to the subsequent wafer planarization, and bonding processes since residual stress-induced wafer bow increases the likelihood of wafer cracking significantly. Based on CVD parametric studies performed to determine the relationship between residual stresses in SiC and H2/MTS ratio, deposition temperature, and HCl/MTS ratio, very low residual stress (less than several tens of MPa) in thick CVD SiC coatings (up to -50 pm) was achieved.
(cont.) In the course of the residual stress study, a general method for stress quantification was developed to isolate the intrinsic stress from the thermal stress. In addition, qualitative explanations for the residual stress generation are also offered, which are in good agreement with experimental results. In the post-CVD processes, the feasibility of SiC wafer planarization and Si-to-SiC wafer bonding processes have successfully been demonstrated, where CVD oxide was used as an interlayer bonding material to overcome the roughness of SiC surface. Finally, the bonding interface of the Si-SiC hybrid structures with oxide interlayer was verified to retain its integrity at high temperatures through four-point flexural tests.
by Dongwon Choi.
Ph.D.
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Didymus, Faye F. « Exploring the organizational stress process in sport performers : from theory to practice ». Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10959.
Texte intégralRésumé :
The increasing evidence of the organizational demands encountered by sports performers provides a fertile ground for research. There is now a requirement to move beyond describing the organizational stressors that performers encounter in order to understand the complex appraisal and coping processes that athletes engage in when experiencing organizational stress. This thesis aimed to conduct a detailed examination of these processes in high-level sport performers. Chapter 2 describes a narrative review of the extant appraisal literature that has examined the roles of situational and personal influences on appraising. In order to generate a detailed understanding of this literature, the review includes findings from the general, occupational, organizational, and sport psychology literatures. This review was instrumental in determining the direction of the research described in later chapters. Chapter 3 aimed to narrow the focus of the thesis to organizational stress transactions in sport performers and therefore, describes a diary study that explored swimmers appraisals of organizational stressors. The findings of this study provided insight into the complex process of appraisal and suggested that appraisals are related to the situational property of the stressor encountered. In addition, the results pointed to the importance of exploring the coping strategies that athletes use to manage organizational stressors in future research. Chapter 4 describes a narrative review of the literature that has examined athletes ways of coping with organizational stressors. Due to the limited sport psychology research in this area and in order to extend current knowledge in sport, prominent findings from the organizational and occupational psychology domains were considered. Chapter 5 was designed to extend the findings of Chapter 3 and the existing literature by examining the coping strategies that swimmers use in response to organizational stressors. This chapter highlighted the complexity of coping and suggested that appraisal mechanisms are linked to the coping family employed. Chapter 6 aimed to take a more complete approach to examining organizational stress transactions by exploring various components of stress transactions. The study presented in this chapter suggested that the appraisal an athlete makes is influential in determining the performance outcome that they will experience. Collectively, the chapters described above highlighted appraising as the pivotal element in stress transactions and established a rationale for the cognitive-behavioral based intervention that is described in Chapter 7. The study presented in Chapter 7 aimed to alleviate some of the negative outcomes of organizational stress by optimizing sport performers appraisals. The findings suggested that cognitive restructuring was a useful technique for achieving this aim. The program of research presented in this thesis suggests that appraising is the pivotal element of organizational stress transactions in sport and that appraising can be optimized in order to alleviate the negative emotional and performance outcomes of maladaptive appraisals. In addition, the research highlights the importance of considering the situational properties of stressors, the complexity of coping, and the relationships between components of stress transactions in future research. Further, the findings presented within this thesis suggest that future research should aim to make methodological and measurement advances and examine, in detail, performers appraisal and coping processes.