Varying Stress Levels Research Articles

Temperature Resistance of Mo3Si: Phase Stability, Microhardness, and Creep Properties

Mo-Si-B alloys are one of the most promising candidates to substitute Ni based superalloys in gas turbines. The optimization of their composition can be achieved more effectively using multi-scale modeling of materials behavior and structural analysis of components for understanding, predicting, and screening properties of new alloys. Nevertheless, this approach is dependent on data on the properties of the single phases in these alloys. The focus of this investigation is Mo3Si, one of the phases in typical Mo-Si-B alloys. The effect of 100 h annealing at 1600 °C on phase stability and microhardness of its three near-stoichiometric compositions—Mo-23Si, Mo-24Si and Mo-25Si (at %)—is reported. While Mo-23Si specimen consist only of Mo3Si before and after annealing, Mo-24Si and Mo-25Si comprise Mo5Si3 and Mo3Si before annealing. The latter is then increased by the annealing. No significant difference in microhardness was detected between the different compositions as well as after annealing. The creep properties of Mo3Si are described at 1093 °C and 1300 °C at varying stress levels as well as at 300 MPa and temperatures between 1050 °C and 1350 °C. Three constitutive models were used for regression of experimental results—(i) power law with a constant creep exponent, (ii) stress range dependent law, and (iii) power law with a temperature-dependent creep exponent. It is confirmed that Mo3Si has a higher creep resistance than Moss and multi-phase Mo-Si-B alloys, but a lower creep strength as compared to Mo5SiB2.

The stress level and its effect on learning achievements of health students due to corona pandemic in Indonesia

(1) Background: The development of the Covid-19 (Corona Virus Disease 2019) outbreak has an impact on all sectors including education where teaching and learning processes are carried out online nationwide. Changes in these conditions can cause various levels of stress that affect students’ achievement during the online learning process. (2) Objective: The purpose of this study is to determine the effect of stress levels on students’ achievement in various health majors in Indonesia. (3) Methods: The type of research used is quantitative using a cross sectional study design. The sampling technique is simple random sampling, conducted online with a total sample of 200 respondents, in 5 departments of health education institutions in 21 provinces (61.8%) out of 34 provinces in Indonesia. Data were collected using a validated Medical Student Stressor Questionnaire (MSSQ) and the Pearson Product Moment correlation analysis method. (4) Results: From the Pearson Product Moment test results, a p-value of 0,000 was obtained, which means p-value

Does fluctuating asymmetry of wing traits capture relative environmental stress in a lepidopteran?

Fluctuating asymmetry (FA) is hypothesized to be a useful predictor of population canalization, especially for organisms at risk from environmental change.Identification of traits that meet statistical criteria as FA measures remains a challenge.Here, a laboratory experiment subjected immature butterflies (Vanessa cardui) to diet and temperature conditions of varying stress levels. Variation in dietary macronutrient ratio (protein: carbohydrate) and rearing temperature (optimal: 25°C; elevated: 32°C) was introduced as stressors. Temperature and nutrition are key variables influencing ectotherm growth and fitness and so are likely to be important stressors that influence FA.Individuals subjected to stressful conditions were predicted to show elevated FA of three wing size traits, as well as increased mortality and decreased adult body size.Trait FA did not vary across treatments. Instead, treatment levels impacted viability: The combined incidence of pupal death and expression of significant wing malformations increased in treatment levels designated as stressful. Variation in adult dry mass also reflected predicted stress levels. Results suggest that individuals predicted to display increased FA either died or displayed gross developmental aberrations.This experiment illustrates important constraints on the investigation of FA, including selection of appropriate traits and identification of appropriate levels of stressors to avoid elevated mortality. The latter concern brings into question the utility of FA as an indicator of stress in vulnerable, natural populations, where stress levels cannot be controlled, and mortality and fitness effects are often not quantifiable.

Assessment of job satisfaction and quality of life among practicising pediatric intensivists of India

Introduction: Pediatric intensive care specialty is a challenging field. This exposes the pediatric intensivist to various levels of stress at different stages of their career. The various precipitating factors for stress are prolonged working hours, decreased quality time with family, unsatisfactory remuneration, and increasing medicolegal litigations and physical, psychological stress, and property damage caused by unhappy families. Aim: The study was conducted to assess the quality of life, working patterns as well as socioeconomic wellbeing among pediatric intensivists working in Indian pediatric intensive care units (PICUs) in the private sector, public sector, and charitable institutions. Methods: A nationwide survey was performed in 2019 among the pediatric critical care fraternity across India to ascertain and enquire about several aspects of their work, careers, and personal lives with a Google form request with preformed questions and single answer options for this survey. Results: A total of 181 responses were received. About one-third (34%) chose this pediatric specialty for its challenging nature. Close to 40% of respondents were engaged in practice of other specialties of pediatrics apart from pediatric intensive care. Professionally, 86% of pediatric intensivists were satisfied with their work. More than half of the respondents (62%) felt that aggression against hospitals and health-care personnel was worrisome and these incidents affected their personal health with increased stress and subconscious fear. Conclusions: This survey revealed that most pediatric intensivists are satisfied with their chosen profession. Stress has been documented as a significant issue with violence in health-care settings being one of the most worrying aspects.

PASS: A Multimodal Database of Physical Activity and Stress for Mobile Passive Body/ Brain-Computer Interface Research

With the burgeoning of wearable devices and passive body/brain-computer interfaces (B/BCIs), automated stress monitoring in everyday settings has gained significant attention recently, with applications ranging from serious games to clinical monitoring. With mobile users, however, challenges arise due to other overlapping (and potentially confounding) physiological responses (e.g., due to physical activity) that may mask the effects of stress, as well as movement artifacts that can be introduced in the measured signals. For example, the classical increase in heart rate can no longer be attributed solely to stress and could be caused by the activity itself. This makes the development of mobile passive B/BCIs challenging. In this paper, we introduce PASS, a multimodal database of Physical Activity and StresS collected from 48 participants. Participants performed tasks of varying stress levels at three different activity levels and provided quantitative ratings of their perceived stress and fatigue levels. To manipulate stress, two video games (i.e., a calm exploration game and a survival game) were used. Peripheral physical activity (electrocardiography, electrodermal activity, breathing, skin temperature) as well as cerebral activity (electroencephalography) were measured throughout the experiment. A complete description of the experimental protocol is provided and preliminary analyses are performed to investigate the physiological reactions to stress in the presence of physical activity. The PASS database, including raw data and subjective ratings has been made available to the research community at http://musaelab.ca/pass-database/. It is hoped that this database will help advance mobile passive B/BCIs for use in everyday settings.

Fatigue behavior of GFRP-reinforced ECC link slabs under variable stress levels and number of cycles

Glass Fibre Reinforced Polymer (GFRP) bars have been used in the Province of Ontario as top layer of bridge deck reinforcement near surfaces exposed to de-icing chemicals. The intent of replacing deck reinforcements with GFRP is to mitigate negative effects of conventional steel rebar corrosion. Furthermore, the development of Engineered Cementitious Composite (ECC) with inherent crack width control and strain-hardening tensile behaviour for link slab application provides design engineers with a new effective way to construct joint-free bridge decks with improved durability. This paper presents experimental investigation of ECC-link slabs reinforced with sand-coated GFRP bars. The link slab specimens were subjected to variable mean fatigue stress levels of up to 55% load capacity and fatigue cycles of up to 1 million, followed by post-fatigue monotonic loading to failure. Link slab load–deflection, stiffness degradation, end rotation, GFRP and ECC strains, crack development, failure modes, energy absorbing capacity, and ductility were determined. Results were then compared with companion steel-reinforced ECC link slabs in the literature to quantify benefits of using GFRP bars. Experimental results showed that GFRP-reinforced link slabs failure by concrete crushing due to high rupture strength of GFRP, whereas steel-reinforced link slabs failed by rebar yielding. Besides exhibiting improved overall strength, the GFRP reinforced ECC link slabs showed greater post-fatigue residual rotational capacity, lower rate of stiffness degradation, enhanced post-fatigue retention of energy absorbing capacity.

Flexural fatigue strength prediction of self compacting concrete made with recycled concrete aggregates and blended cements

The paper presents the findings of an investigation conducted to examine the flexural fatigue strength of Self Compacting Concrete (SCC) containing 50% Coarse Recycled Concrete Aggregates (RCA) and blended cements i.e. Silica Fume (SF) and Metakaolin (MK). Fatigue life data of different SCC mixes has been obtained by performing flexure fatigue tests on 224 beams of size 100 mm × 100 mm × 500 mm under four-point loading at varying stress levels ranging from 0.95 to 0.65 depending upon the mix. Tests data thus obtained has been utilized to represent the S-N relationships for different SCC mixes and has also been employed to evaluate the experimental coefficients of different strength prediction models. Concept of failure probability has been introduced into the fatigue life data of different SCC mixes and families of S-N-Pf curves have been generated to relate stress level, fatigue life and failure probability. Theoretical fatigue life and endurance limit/two million cycle fatigue strength have also been determined for different SCC mixes and found to show a degradation with the addition of RCA. However, addition of SF and MK has been found to significantly increase the endurance limit and theoretical fatigue life for blended SCC mixes containing RCA.

Investigation on the deformation behavior of open-graded unbound granular materials for permeable pavement

Permeable pavement has many advantages on environment and has been applied in various fields. However, the performance of the base layer of permeable pavement in the field of heavy loads has not attracted enough attention. This paper explorted the deformation behavior of open-graded unbound granular materials (UGMs) for base layers of permeable pavement under repeated triaxial loading. The deformation behavior explored in this study included both resilient deformation and permanent deformation. Firstly, the resilient modulus of different gradations with different ranges of particle size was studied. The results indicated that the open-graded UGMs had enough resilient modulus ranging from 110 to 371 MPa. The different gradations at various levels of stress under dry and wet conditions were studied to simulate different work conditions of base layer for permeable pavement. The results showed that porosity, particle size, stress level and moisture had great impact on permanent deformation. In addition, stress level represented by the shear stress/strength ratio (SSR) was introduced into the permanent deformation characterization, and the results suggested that the permanent deformation under the stress level of SSR value within 0.4 belonged to the plastic creep, which was acceptable permanent deformation in the pavement design. Therefore, this study concluded that, compared with traditional UGMs, open-graded UGMs may also meet the bearing capacity requirement for base materials under wet condition.

Fatigue performance and stress range modeling of SFRC beams with high-strength steel bars

The fatigue performance of steel-fiber-reinforced concrete (SFRC) beams with tensile steel bars of 500 MPa yielding strength (HRB500) was investigated through flexural tests. One control beam was tested to determine the ultimate capacity on being subjected to static loading, and eight beams with variable stress levels and fiber contents were tested subjected to fatigue loading. Test results indicated that the fatigue life of the beams decreased with increasing stress level and increased with fiber content. For an SFRC beam with 1% fiber content, its fatigue life increased by twice compared with that of non-fiber-reinforced concrete beams, thereby, confirming the fact that adding steel fibers into concrete can enhance fatigue life significantly. With the addition of steel fibers, the cracking patterns of the beams improved and deflections decreased during fatigue loading. Furthermore, the stress range of the tensile steel bar decreased with increasing fiber content, and slippage did not occur between the tensile steel bar and concrete owing to adequate anchorage. An effective moment of inertia method that considers the effects of steel fibers was used to calculate the stresses of tensile steel bars in the first loading cycle; subsequently, an empirical expression to calculate the SFRC strain in compression zone under fatigue loading is established. Finally, a prediction model of stress range for the tensile steel bar of SFRC beams under fatigue loading is proposed and further validated through the results of tests on 19 SFRC beams.

Measuring stress in clinical and nonclinical subjects using a German adaptation of the Perceived Stress Scale

Background/Objective: Stress is perceived differently across individuals, which might be particularly true for nonclinical and clinical subjects. For this reason, we tested a German adaption of the 10-item Perceived Stress Scale (PSS-10) for model fit and measurement invariance in a big nonclinical and clinical sample. Method: We (1) conducted multiple confirmatory factor analysis (CFA) in 1,248 nonclinical subjects and 575 outpatients, (2) measurement invariance with multigroup CFA, (3) assessed correlations with relevant constructs and (4) calculated internal consistencies for overall stress and the subscales Helplessness and Self-efficacy. Results: In both samples, CFA revealed a robust two-factorial structure with an excellent model fit. Group comparisons revealed strict measurement invariance. Correlations with associated measures support validity. Internal consistencies were good to very good. Conclusions: We show highly satisfactory psychometric properties of the German PSS-10 for nonclinical and clinical individuals. Measurement invariance analyses demonstrated that varying stress levels of people with a different mental health status are due to true interindividual differences.

Dependence of fatigue limit on stress ratio and influence of cyclic stress on shear strength for an adhesive lap joint

ABSTRACT The improvement in adhesion technology for joining different types of materials has led to expectations of weight reduction in cars and commercial vehicles. Various levels of stress and stress ratios are loaded onto the joints of such transport vehicles. Therefore, the fatigue shear strength of an adhesive lap joint is important. This study is related to the fatigue properties of structural adhesive joints. Lap-joint specimens using epoxy adhesive were prepared, and fatigue tests with four different stress ratios were conducted. Subsequently, the fatigue limit diagram was plotted, and the effect of stress ratio on the fatigue limit was investigated. Moreover, the strength of the specimens subjected to various cyclic stress levels was investigated systemically. With cyclic shear stress, the influence of the shear stress amplitude on the resistance to fatigue failure was more significant than that of the number of cycles. The specimens that endured the fatigue tests maintained approximately the same shear strength as that of the as-received specimens. The findings of this study can provide important guidance for the design of a car body.

SLC1A3 C3590T but not BDNF G196A is a predisposition factor for stress as well as depression, in an adolescent eastern Indian population

BackgroundAdolescence is a distinctive stage of various changes and is noted as peak age for onset of many psychiatric disorders, especially linked to stress and depression. Several genetic variations are being increasingly known to be linked with stress and depression. The polymorphisms in two such genes, the BDNF and SLC1A3, have been reported to be linked with either depression/stress or with suicidal behaviour. These genes have not been validated in Indian population, and therefore there is a need to investigate these genes in Indian population. The present study was undertaken to test whether the known polymorphisms SLC1A3 C3590T, SLC1A3 C869G and BDNF G196A are associated or not with stress or depression in an eastern Indian population.MethodsA case-control association study was performed with 108 cases having variable levels of stress and depression and 205 matched controls. Detection of stress and depression was done by using standard instruments as PSS and CES-D, respectively and demographic profile was obtained for each individual on the basis of personal data sheet. Genotyping for the selected polymorphisms was performed by PCR followed by restriction digestion.ResultsThe SNP SLC1A3 C3590T was found to be associated with stress and depression (p = 0.0042, OR = 2.072). Therefore, the T allele increases the risk by more than two folds for stress and depression in the present population. The other allele of SLC1A3, G869C, as well as BDNF G196A were not associated with stress or depression in the population studied.ConclusionSLC1A3 C3590T is a predisposition factor for stress and depression in an eastern Indian population, whereas SLC1A3 G869C and BDNF G196A were not found to be a risk factor. Therefore, presence of T allele of SLC1A3 C3590T, may predict the development of stress and depression in an individual. This may also help in the understanding of pathophysiology of the disease. However, these findings warrant a wider study in Indian populations and would be of significance in understanding the predisposition of stress and depression in this population.

The Association of Stress with the Socio-Economic Factors of Individuals That Attended the Taxpayers’ Appreciation Week 2018, Kampala Uganda

Introduction: Work-related stress has increased in nine European Union (EU) countries in the last ten years. Eighty (80%) percent of the general population in European countries believes that work-related stress will rise in the coming five years. Objective: The purpose of this study was to determine the association between the various levels of stress with the socio-economic elements among individuals that participated in Uganda’s tax payer’s appreciation week in the year 2018 held in Kampala. Methodology: This study applied a cross-sectional study design that unified quantitative research methods and a convenience sampling method were used in this study to gather the information from the 390 respondents. Data were examined using SPSS version 20; univariate and bivariate analysis were done to measure the association between stress and the participant’s socio-economic factors. Results: Respondents who were employed recorded the majority with a percentage of 60%, while the unemployed recorded the minority with a percentage of 40%. Respondents who were employed were more likely to experience low stress as compared to those who were unemployed, under the category of moderate stress, respondents who were employed were more likely to be moderately stressed as compared to their unemployed counterparts, as for the category of high stress, unemployed respondents were more likely to be highly stressed than those that were employed and this was not statistically significant (X2 =2.374; p-value = 0.305). Conclusion: The results from this research indicated that there was no significant association between the socioeconomic factors of the respondents with stress levels. Recommendations: More community sensitization and awareness should be carried out to educate individuals about stress and its impacts on health.

The Establishment of the Proportion of Stress Levels and Its Association with the Demographic Factors among Individuals That Participated in the Taxpayers’ Appreciation Week 2018, Kampala, Uganda

Introduction: Stress can affect people of all ages, genders and circumstances and can lead to both physical and psychological health issues. Stress is the emotional and physical strain caused by our response to pressure from the outside world. Chronic stress affects your capability to concentrate, act professionally and efficiently and makes you more accident-prone. Objective: The purpose of this study was to determine the association between the various levels of stress with the demographic factors among individuals that participated in Uganda’s tax payer’s appreciation week in the year 2018 held in Kampala. Methodology: This study utilised a cross-sectional study design that incorporated quantitative research methods and convenience sampling technique was used in this study to gather the information from the 390 respondents. Data were analysed using SPSS version 20; univariate and bivariate analysis was done to measure the association between stress and the participant’s demographic characteristics. Results: This research study revealed that none of the variables (age, gender, marital status and education level) was statistically significant with stress levels, hence no association was established. Conclusion: The results from this research indicated that there was no significant association between the demographic factors of the respondents and stress levels. Furthermore, the proportion of stress levels showed that majority of the respondents recruited for this research study were moderately stressed (54.2%) and the minority had low stress (18.9%). Recommendations: Individuals should maintain a healthy lifestyle both physically, emotionally and socially to keep their stress levels low or moderate.

Brahma Kumaris Sahaj Raj-Yoga Meditation - As a Tool to Manage Various Levels of Stress

Brahma Kumaris Sahaj Raja Yoga Meditation is an ancient technique to bring the mental peace and inner harmony. The research on the practices of such techniques has shown that, they are great help in the stress management and in the prevention of many of the psychosomatic diseases. The word “Yoga” simply means “Union” and the word “Raja” means “Supreme”, “King” or “Master”. Raja Yoga is the king of all yoga because through it one can become sovereign. The regular practice results in good health, happiness and prosperity in life. This review article focuses on the beneficial effects of BarhmaKumaris Sahaj Raja Yoga Meditation through the effective stress management mechanisms. Purpose of the Research: Main aim in doing this is to build healthy, wealthy happy, and value based society. In that society, everyone will naturally enjoy their life with the greatest worth and dignity and all kinds of freedom.Result: Hectic research work on the application of the Sahaj Raja Yoga Meditation has reviled many health benefits they have been highly significant to promote the mental health and positive emotion. Conclusions: The practice enhances the cognitive capacities such as improved concentration, memory and focus. These are useful to develop the positive relationships overcoming the negative tendencies.

Nondestructive estimation of remaining fatigue life without the loading history

A new nondestructive method to estimate the remaining fatigue life of a fatigue specimen with unknown knowledge of the loading history is presented. It requires only one short-time excitation test. The method utilizes the concept of damage parameter and the temperature rise to reliably predict the remaining number of cycles before fracture. A generalized procedure and numerous experimentally verified examples are presented. It is shown that the method can be applied to both constant and variable stress levels. Extensive laboratory tests reveal that the results of the remaining fatigue life predictions are in very good agreement with measurements.

Wellbore-Stability Analysis by Integrating a Modified Hoek-Brown Failure Criterion With Dual-Porochemoelectroelastic Theory (includes associated erratum)

Summary When drilling through naturally fractured formations, the existence of natural fractures affects the fluid diffusion and stress distribution around the wellbore and induces degradation of rock strength. For chemically active formations, such as shale, the chemical–potential difference between the drilling mud and the shale–clay matrix further complicates the nonmonotonic coupled pore–pressure processes in and around the wellbore. In this work, we apply a recently formulated theory of dual–porosity/permeability porochemoelectroelasticity to predict the time evolution of mud–weight windows, while calculating stresses and pore pressure around an inclined wellbore drilled in a fractured shale formation. The effects of natural–fracture geometric and spatial distributions coupled with the chemical activity are considered in the wellbore–stability analysis. To account for the degrading effect of the fractured shale matrix on the bulk rock strength, a modified Hoek–Brown (MHB) criterion is developed to more closely describe the in–situ state of stress effects on the compressive shearing strength at great depth. Compared with the original Hoek–Brown (HB) failure criterion, the MHB criterion considers the influence of the intermediate principal stress and thus shows better agreement with true–triaxial data for various rocks at varying stress levels. The MHB criterion converges to the original HB criterion when the confining in–situ stresses are equal. Two field case studies indicate that this novel integrative methodology is capable of predicting the operational drilling–mud–weight windows used in these two cases. Another advantage of this newly developed technique is that it can be used as a back–analysis tool to estimate the fracture–matrix permeability from field operational data.

Incorporating Physiology into Creativity Research and Practice: The Effects of Bodily Stress Responses on Creativity in Organizations

In the modern workplace, employees are required to be creative under varying stress levels. In understanding the relationship between stress and creativity, organizational scholars and practitioner...

Mapping Medical Aspirants Stress Levels Based on Student Versus Parent Led Career Choice- Special Reference to Kota

This study was conducted to find varying stress levels feel by medical aspirants if they choose to prepare under parental pressure vis-à-vis under their own will considering the amount of hard work and perseverance required to put in for medical entrance in India. Suicide cases and various studies on stress levels among aspiring students, coming from different parts of India to Kota, preparing for medical and engineering entrance examinations make Kota an appropriate and obvious choice for the study. Responses were tabulated using frequency distribution tables and results were derived applying t-test, factor analysis and ANOVA using SPSS version 19. The study concluded that students chose to prepare for medical entrance out of their own will and male medical aspirants feel more stress as compared to female aspirants. Mapping overall stress with the parental pressure have some discrepancies with the previous studies performed by researchers and research institutes which might have caused due to various limitations, one would be a time of the study. This might further be analysed and verify the results as with the change in the social matrix of the social things tend to vary.

Modeling memoryless degradation under variable stress

Accelerated degradation tests can be used as the basis for predicting the performance or state of health of products and materials at use conditions over time. Measurements acquired at accelerated levels of stress are used to develop models that relate to the degradation of one or more performance measures. Frequently, products/materials of interest are subjected to variable stress levels during their lifetimes. However, testing is usually performed only at a few fixed stress levels. In such cases, cumulative degradation models are developed and assessed by using data acquired under those fixed stress conditions. The degradation rate at any stress condition within the range of the model can be estimated by the derivative of the cumulative model at that stress condition. It follows that, to predict cumulative degradation over variable use conditions, one might integrate the fluctuating degradation rate over time. Existing approaches for doing this consider degradation rates that depend only on the current stress level. Here, we propose to allow the degradation rate to also depend on the current state of health as indicated by the associated performance measure(s). The resulting modeling approach is capable of portraying a broader range of degradation behavior than existing approaches. The assertion of memoryless degradation by using this or any other approach should be assessed experimentally with data acquired under variable stress in order to increase confidence that the integrated rate model is accurate. In this article, we demonstrate the additional capability of the proposed approach by developing empirical memoryless rate-based degradation models to predict resistance increase and capacity decrease in lithium-ion cells that are being evaluated for use in electric vehicles. We then assess the plausibility of these models.