Search results for: aperture change due to stress

Authors: Deena Moustafa

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The purpose of this paper is to describe the sources of parenting stress in mothers of Dual Diagnosis children (n =60) and examine the relationship between parenting stress and maternal psychological status (depression and well-being), also examine if there is any difference between the previous variables in different disabilities associated with Autism. A descriptive correlational design was used. Data were collected via online questionnaires. The study finds that there was no significant relationship between Autism Parenting Stress Index (APSI) scores and types of disability which associated with Autism, although Mothers with deaf autistic reported more parenting stress, Similar findings were found regarding Depressive Symptoms, as there was no significant relationship between (CESD-R) scores and types of disability which associated with Autism, also study finds that there was a significant correlation of the (APSI) with the (CESD-R) Mothers with higher overall parenting stress reported more depressive symptoms. Likewise, there was also a significant correlation between the (APSI) and the (RPWB) Mothers reporting more parenting stress also reported lower levels of well-being.

Keywords: parenting stress, maternal psychological statues, mothers of dual diagnosis, autism

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Authors: Kashif Jaeel, Bingru Huang

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Stress-induced accumulation of ethylene exacerbates drought damages in plants, and suppressing stress induction of ethylene may promote plant tolerance to heat stress. The objective of this study was to investigate the effects of endophytic bacteria (Paraburkholderia aspalathi) with 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase enzymes in suppressing ethylene production on plant tolerance to heat stress and underlying physiological mechanisms of P. aspalathi-regulation in creeping bentgrass (Agrostis stolonifera). A novel strain of P. aspalathi, ‘WSF23’, with ACC deaminase activity was used to inoculate the roots of plants (cv. ‘Penncross’) subjected to heat stress in controlled-environment chambers. Inoculation with WSF23 bacteria resulted in improved shoot and root growth during heat stress. The differential changes in metabolite regulation due to the bacterial inoculation could contribute to ACC deamination bacteria-improved heat tolerance in cool-season grass species.

Keywords: rhizobacteria, grass, heat, plant metabolism, soil bacteria

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Authors: Rhea Mathews

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The purpose of the study is to investigate the effects of perceived social support and cultural self-efficacy on the acculturative stress of international postgraduate students in the United Kingdom. The study adopted Berry, Kim, Minde & Mok’s (1987) acculturative framework on acculturative stress and examined the relationship between the variables. The study hypothesized that perceived social support and cultural self-efficacy would predict lower levels of acculturative stress among students. Postgraduate students in the United Kingdom (N = 76) completed three surveys measuring the variables; Acculturative Stress Scale for International Students, Multidimensional Scale of Perceived Social Support, and Cultural Self-efficacy for Adolescents. To evaluate the role of the perceived social support and cultural self-efficacy in determining the acculturative stress level of international students, multiple linear regression was employed. Both independent variables exhibited a significant, negative relationship with acculturative stress (p < 0.001; p < 0.01). Results described that cultural self-efficacy and perceived social support significantly predicted acculturative stress (p < 0.01). Together, the variables accounted for 22% of the variance in acculturative stress scores (adjusted R² = 0.22), with cultural self-efficacy playing a larger role in predicting the dependent variable. Limitations and implications of the study are noted. The findings of the study are discussed in relation to enhancing international students’ acculturative experience when relocating to a new environment.

Keywords: acculturative stress, coping, cultural adjustment, cultural self-efficacy, international education, international students, migration, perceived social support

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Authors: Horaya Mostafa Ahmed

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All cultures are inherently predisposed to change and, at the same time, to resisting change. There are dynamic processes operating that encourage the acceptance of new ideas and things, while there are others that encourage changeless stability. Despite the dramatic changes that have taken place in all human cultures, there are cultures still steadfast and resist change. These cultures resist through some culture mechanisms like, cultural boundaries, ethnocentrism, religion, and cultural relativity. So this paper is an attempt to discover these mechanisms of cultural change resistance and to ask is cultural change always required.

Keywords: cultural change, cultural boundaries, cultural relativity, ethnocentrism, religion, resistance

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Authors: M. Jalali Azizpour, H. Mohammadi Majd, A.R. Aboudi Asl, D. Sajedipour, V. Tawaf

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Sandblasting is a generally used surface treatment technique to improve the residual stress and adhesion of coatings to substrate. The goal of this work is to study the effect of temperature on the residual stress in sandblasting AISI1045 substrate. For this purpose a two dimensional axisymmetric model of shot impacting on an AISI 1045 disc was generated using ABAQUS version 6.10. The result shows for sandblasting temperature there is an optimum condition. In addition there are other effective factors that influence the fatigue life of parts.

Keywords: modeling, shot peen, residual stress, temperature

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Authors: Hossein Kheirollahi, Yunhua Luo

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Studying stress and strain trends in the femur and recognizing femur failure mechanism is very important for preventing hip fracture in the elderly. The aim of this study was to identify high stress and strain regions in the femur during normal walking and falling to find the mechanical behavior and failure mechanism of the femur. We developed a finite element model of the femur from the subject’s quantitative computed tomography (QCT) image and used it to identify potentially high stress and strain regions during the single-leg stance and the sideways fall. It was found that fracture may initiate from the superior region of femoral neck and propagate to the inferior region during a high impact force such as sideways fall. The results of this study showed that the femur bone is more sensitive to strain than stress which indicates the effect of strain, in addition to effect of stress, should be considered for failure analysis.

Keywords: finite element analysis, hip fracture, strain, stress

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Authors: Mahyar Maali, Merve Sagiroglu, Mahmut Kilic, Abdulkadir Cuneyt Aydin

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In order to evaluate the residual strength of S235 (St37) steel structures after the fire, an experimental program was undertaken to investigate the post-fire mechanical properties. Tensile coupons taken from S235 sheets were exposed to varying temperatures as 200°C, 400°C, 600°C, and 800 °C. The samples were then allowed to cool down to ambient temperature before they were tested to failure. To obtain the mechanical properties of steels; tensile tests are performed, and the post-fire stress-strain curves are evaluated. The microstructures of the heat-treated specimens were examined by Scanning Electron Microscope (SEM). It is seen that morphology and size of the precipitates in the specimens change, as the heat increases. The modulus of elasticity decreases, and deformation increases with temperature. Energy dissipation decreases due to lower stress according to the stress-strain curves of the specimens. Especially, the mechanical properties were decreased compared with the pre-fire ones. As a result of the post-fire and pre-fire behavior of S235, a set of equations is evaluated to predict the mechanical properties after the fire. These types of equations may allow the structural and/or fire engineers to predict accurately the post-fire behavior of the buildings constructed with S235 type steel.

Keywords: post-fire behavior, stress-strain curves, experimental study, S235 steel

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Authors: Siqi Lin, Yangang Zhao

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Concrete-filled steel tube column achieves the excellent performance of high strength, stiffness, and ductility due to the confinement from the steel tube. Well understanding the stress of the steel tube is important to make clear the confinement effect. In this paper, the ultimate stress of the steel tube in circular concrete-filled steel tube columns subjected to axial compression was studied. Experimental tests were conducted to investigate the effects of the parameters, including concrete strength, steel strength, and D/t ratio, on the ultimate stress of the steel tube. The stress of the steel tube was determined by employing the Prandtl-Reuss flow rule associated with isotropic strain hardening. Results indicate that the stress of steel tube was influenced by the parameters. Specimen with higher strength ratio fy/fc and smaller D/t ratio generally leads to a higher utilization efficiency of the steel tube.

Keywords: concrete-filled steel tube, axial compression, ultimate stress, utilization efficiency

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Authors: Amritha Nair, Fleur Visser, Ian Maddock, Jonas Schoelynck

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Inland waters such as streams sustain a rich variety of species and are essentially hotspots for biodiversity. Submerged aquatic vegetation, also known as SAV, forms an important part of ecologically healthy river systems. Direct and indirect human influences, such as climate change are putting stress on aquatic plant communities, ranging from the invasion of non-native species and grazing, to changes in the river flow conditions and temperature. There is a need to monitor SAV, because they are in a state of deterioration and their disappearance will greatly impact river ecosystems. Like terrestrial plants, SAV can show visible signs of stress. However, the techniques used to map terrestrial vegetation from its spectral reflectance, are not easily transferable to a submerged environment. Optical remote sensing techniques are employed to detect the stress from remotely sensed images through multispectral imagery and Structure from Motion photogrammetry. The effect of the overlying water column in the form of refraction, attenuation of visible and near infrared bands in water, as well as highly moving targets, are NIR) key challenges that arise when remotely mapping SAV. This study looks into the possibility of mapping the changes in spectral signatures from SAV and their response to certain stresses.

Keywords: submerged aquatic vegetation, structure from motion, photogrammetry, multispectral, spectroscopy

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Authors: Khalid Omari, Rene Chenier, Enrique Blondel, Ryan Ahola

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Northern Canadian coasts have vulnerable and very dynamic intertidal zones with very high tides occurring in several areas. The impact of climate change presents challenges not only for maintaining this biodiversity but also for navigation safety adaptation due to the high sediment mobility in these coastal areas. Thus, frequent mapping of shorelines and intertidal changes is of high importance. To help in quantifying the changes in these fragile ecosystems, remote sensing provides practical monitoring tools at local and regional scales. Traditional methods based on high-resolution optical sensors are often used to map intertidal areas by benefiting of the spectral response contrast of intertidal classes in visible, near and mid-infrared bands. Tidal areas are highly reflective in visible bands mainly because of the presence of fine sand deposits. However, getting a cloud-free optical data that coincide with low tides in intertidal zones in northern regions is very difficult. Alternatively, the all-weather capability and daylight-independence of the microwave remote sensing using synthetic aperture radar (SAR) can offer valuable geophysical parameters with a high frequency revisit over intertidal zones. Multi-polarization SAR parameters have been used successfully in mapping intertidal zones using incoherence target decomposition. Moreover, the crustal displacements caused by ocean tide loading may reach several centimeters that can be detected and quantified across differential interferometric synthetic aperture radar (DInSAR). Soil moisture change has a significant impact on both the coherence and the backscatter. For instance, increases in the backscatter intensity associated with low coherence is an indicator for abrupt surface changes. In this research, we present primary results obtained following our investigation of the potential of the fully polarimetric Radarsat-2 data for mapping an inter-tidal zone located on Tasiujaq on the south-west shore of Ungava Bay, Quebec. Using the repeat pass cycle of Radarsat-2, multiple seasonal fine quad (FQ14W) images are acquired over the site between 2016 and 2018. Only 8 images corresponding to low tide conditions are selected and used to build an interferometric stack of data. The observed displacements along the line of sight generated using HH and VV polarization are compared with the changes noticed using the Freeman Durden polarimetric decomposition and Touzi degree of polarization extrema. Results show the consistency of both approaches in their ability to monitor the changes in intertidal zones.

Keywords: SAR, degree of polarization, DInSAR, Freeman-Durden, polarimetry, Radarsat-2

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Authors: Abdelouahab Errida, Bouchra Lotfi, Elalami Semma

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In this paper, we try to address the topic of multiple change management by adopting an engineered research methodology, conducted within a Moroccan company during its implementation of several change projects that aim at improving its supply chain management performance. Firstly, we present the key concepts related to our research, namely change management, multiproject management and supply chain management. Then, we try to assess how the change management and multi-project management are applied in this company. Finally, we try to propose an approach that will help managers in dealing with multiple change projects. This approach proposes to integrate change management, project management and multi-project management for managing change projects according to three organizational levels: executive level, project portfolio level and change project level.

Keywords: change management, multi-project management, project management, change portfolio, supply chain management,

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Authors: Mehrab Karimian

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The present study was designed to find the relationship between Iranian teachers' motivation, their creativity and their job stress. To achieve such goals, 101 EFL teachers, through convenient sampling from different institutes of Shiraz and Fasa, took part in this study. The researcher utilized three instruments, including the Motivation to Teach Questionnaire (MTQ), the Teacher Creativity Questionnaire, and the Job Stress Questionnaire. By running the Pearson correlation coefficient, the findings emphasized that there was a statistically significant positive relationship between Iranian EFL teachers' motivation and their creativity. Moreover, the finding of this study revealed that there was a statistically significant positive relationship between Iranian EFL teachers' motivation and their job stress. Also, according to the results of this study, there was no statistically significant relationship between Iranian EFL teachers' creativity and their job stress. Besides, by utilizing multiple regression analyses, the finding highlighted that just teachers' creativity was able to strongly predict the variance in teachers' motivation. Each of the other variables, namely gender, teachers' job stress, and years of teaching experience individually and collectively, did not predict teachers' motivation. The pedagogical implications of the findings are thoroughly presented.

Keywords: creativity, job stress, gender, years of teaching experience

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Authors: Mahdi Aghaei, Saeid Jamshidi, Mastaneh Hajipour

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Effective factors on the mechanical wellbore stability are divided in to two categories: 1) Controllable factors, 2) Uncontrollable factors. The purpose of geo-mechanical modeling of wells is to determine the limit of controlled parameters change based on the stress regime at each point and by solving the governing equations the pore-elastic environment around the well. In this research, the mechanical analysis of wellbore stability was carried out for Soroush oilfield. For this purpose, the geo-mechanical model of the field is made using available data. This model provides the necessary parameters for obtaining the distribution of stress around the wellbore. Initially, a basic model was designed to perform various analysis, based on obtained data, using Abaqus software. All of the subsequent sensitivity analysis such as sensitivity analysis on porosity, permeability, etc. was done on the same basic model. The results obtained from these analysis gives various result such as: with the constant geomechanical parameters, and sensitivity analysis on porosity permeability is ineffective. After the most important parameters affecting the wellbore stability and instability are geo-mechanical parameters.

Keywords: wellbore stability, movement, stress, instability

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Authors: Cindy de Frias, Erum Whyne

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Objectives: The current study examined whether the link between stress and health-related quality of life was buffered by protective factors, namely mindfulness, in a sample of middle-aged and older adults. Method: In this cross-sectional study, 134 healthy, community-dwelling adults (aged 50–85 years) were recruited from Dallas, Texas. The participants were screened for depressive symptoms and severity (using the Patient Health Questionnaire [PHQ-9]). All participants completed measures of self-reported health status (i.e., SF-36v2: mental and physical health composites), life stress (using the Elder’s Life Stress Inventory [ELSI]), and trait mindfulness (i.e., Mindful Attention Awareness Scale). Results: Hierarchical regressions (covarying for age, gender, and education) showed that life stress was inversely related to physical and mental health. Mindfulness was positively related to mental health. The negative effect of life stress on mental health was weakened for those individuals with greater trait mindfulness. Discussion: The results suggest that mindfulness is a powerful, adaptive strategy that may protect middle-aged and older adults from the well-known harmful effects of stress on healthy aging.

Keywords: health, stress, mindfulness, aging

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Authors: Mohamed Barbary, Mohamed H. Abd El-Azeem

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Maneuvering extended object tracking (M-EOT) using high-resolution inverse synthetic aperture radar (ISAR) observations has been gaining momentum recently. This work presents a new robust implementation of the multiple models (MM) multi-Bernoulli (MB) filter for M-EOT, where the M-EOT’s ISAR observations are characterized using a skewed (SK) non-symmetrically normal distribution. To cope with the possible abrupt change of kinematic state, extension, and observation distribution over an extended object when a target maneuvers, a multiple model technique is represented based on MB-track-before-detect (TBD) filter supported by SK-sub-random matrix model (RMM) or sub-ellipses framework. Simulation results demonstrate this remarkable impact.

Keywords: maneuvering extended objects, ISAR, skewed normal distribution, sub-RMM, MM-MB-TBD filter

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Authors: H. Hosseini, B. V. Berdyshev, I. Iskopintsev

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This paper presents a rheological model for producing shape-memory thermoplastic polymers. Shape-memory occurs as a result of internal rearrangement of the structural elements of a polymer. A non-linear viscoelastic model was developed that allows qualitative and quantitative prediction of the stress-strain behavior of shape-memory polymers during heating. This research was done to develop a technique to determine the maximum possible change in size of heat-shrinkable products during heating. The rheological model used in this work was particularly suitable for defining process parameters and constructive parameters of the processing equipment.

Keywords: elastic deformation, heating, shape-memory polymers, stress-strain behavior, viscoelastic model

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Authors: Kenneth Nhundu, Leocadia Zhou, Farhad Aghdasi, Voster Muchenje

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Climate change poses increased risks to rural communities that rely on natural resources, such as forests, cropland and rangeland, waterways, and open spaces Because of their connection to the land and the potential for climate change to impact natural resources and disrupt ecosystems and seasons, rural livelihoods and well-being are disproportionately vulnerable to climate change. Climate change has the potential to affect the environment in a number of ways that place increased stress on everyone, but disproportionately on the most vulnerable populations, including the young, the old, those with chronic illness, and the poor. The communities in the study area are predominantly rural, resource-based and are generally surrounded by public or private lands that are dominated by natural resources, including forests, rangelands, and agriculture. The livelihoods of these communities are tied to natural resources. Therefore, targeted strategies to cope will be required. This paper assessed the household socio-economic characteristics and their implications to household vulnerability to climate change impacts in the rural Eastern Cape Province, South Africa. The results indicate that the rural communities are climate-vulnerable populations as they have a large proportion of people who are less economically or physically capable of adapting to climate change. The study therefore recommends that at each level, the needs, knowledge, and voices of vulnerable populations, including indigenous peoples and resource-based communities, deserve consideration and incorporation so that climate change policy (1) ensures that all people are supported and able to act, (2) provides as robust a strategy as possible to address a rapidly changing environment, and (3) enhances equity and justice.

Keywords: climate change, vulnerable, socio-economic, livelihoods

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Authors: Farhat Nigar

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Social stress is stress which arises from one's relationships with others and from the social environment. When a person finds that they are not capable of coping with a situation, stress arises. Sanitation workers faces a lot of discrimination from the society which leads to stress and have severe impact on their mental health. Sanitation workers face lot of work pressure which sometimes leads to mental health problems, but there is lack of proper data of sanitation workers dealing with mental health problems which is a big obstacle before evolving policies for the welfare of sewage and septic tank workers which needs attention. The objective of the study is to find out the effect of social stress on the mental health of sanitation workers and to explore the scope of social work in coping with mental health problems of workers. This descriptive and analytical study was conducted on 100 sanitation workers of Aligarh city through convenience sampling. Data were collected from respondents by schedule and interview method. Most of the respondents said that they don’t enjoy equal status in society and at the workplace as well which leads to stress. Many of them said that social stress leads to poor performance in the workplace. Some of the workers feel depressed when their work is not appreciated and recognized in society. Majority of respondents has stress in financial and employment-related difficulties. Thus it can be said that social stress has several impacts on mental health which leads to poor performance, lack of confidence, and motivation which sometimes leads to depression. Social work can play a very important and challenging role in overcoming these difficulties by providing education, motivation and guiding them and by making them aware of their rights and duties.

Keywords: discrimination, health, stress, sanitation workers

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Authors: Jun Su Park, Byung Kwan Oh, Jin Woo Hwang, Yousok Kim, Hyo Seon Park

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For the structural safety, the maximum stress calculated from the stress distribution of a structure is widely used. The stress distribution can be estimated by deformed shape of the structure obtained from measurement. Although the estimation of stress is strongly affected by the location and number of sensing points, most studies have conducted the stress estimation without reasonable basis on sensing plan such as the location and number of sensors. In this paper, an optimal sensing technique for estimating the stress distribution is proposed. This technique proposes the optimal location and number of sensing points for a 2-D frame structure while minimizing the error of stress distribution between analytical model and estimation by cubic smoothing splines using genetic algorithm. To verify the proposed method, the optimal sensor measurement technique is applied to simulation tests on 2-D steel frame structure. The simulation tests are performed under various loading scenarios. Through those tests, the optimal sensing plan for the structure is suggested and verified.

Keywords: genetic algorithm, optimal sensing, optimizing sensor placements, steel frame structure

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Authors: Teresa Smith, Farrah Jacquez

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Health-risk behaviors (e.g., smoking, poor diet) directly increase the risk for chronic disease and morbidity. There is substantial evidence of a negative association between socioeconomic status (SES) and engagement in health-risk behaviors. However, due to the complexity of SES, researchers have suggested looking beyond this factor to fully understand the mechanisms that underlie engagement in health-risk behaviors. Stress is one plausible mechanism through which SES impacts health-risk behaviors. Currently, it remains unclear how stress occurring across the life course might impact health behaviors and explain the association between SES and these behaviors. To address the gaps in the literature, 172 adults between the ages of 18-49 were surveyed about their lifetime stress exposure, sociodemographic variables, and health-risk behaviors via an online recruitment portal, Prolific. Five major findings emerged from the current study. First, SES was negatively associated with engagement in health-risk behaviors and lifetime stress above and beyond current stress and other relevant demographics. Second, lifetime stress was significantly associated with health-risk behaviors above and beyond current stress and relevant demographic variables. Third, lifetime stress fully mediated the association between SES and health-risk behaviors above and beyond current stress and other demographics. Fourth, the severity of stress experienced emerged as the most significant lifetime stress variable that explains the relation between SES and health-risk behaviors. Fifth and finally, lower SES and experiencing financial and legal/crime stressors increased the likelihood of engaging in health-risk behaviors. The current study results align with previous research and suggest that stress occurring over the lifespan impacts the relation between SES and health-risk behaviors, which are in turn known to impact health outcomes. However, our findings move the current literature forward by providing a more nuanced understanding of the specific aspects of stress that influence this association. Specifically, the severity of stress experienced across the entire lifespan was the most important aspect of stress when examining the association between SES and health-risk behaviors. Further, individuals most at risk for engaging in health-risk behaviors are those of the lowest SES and experience financial and legal/crime stressors. These findings have the potential to inform interventions and policies aimed at addressing health-risk behaviors by providing a more sophisticated understanding of the impact of stress.

Keywords: stress, health behaviors, socioeconomic status, health

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Authors: Mamman Jimoh Ahmadu, Sanusi Abubakar Sadiq, Eldah Ephraim Buba

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In modern societies, stress has become a widespread phenomenon and therefore an issue of major concern to employees, organizations, and the state. As senior management of an organization, executives are not immune to this problem because they carry out lots of activities while on duty. This paper is centered on the benefits of Tourism, Leisure and Recreation to the management of executive stress. Executives work has always been considered to be stressful. The key objective of the research is to gain a better understanding of the causes of stress among executives and to find out how tourism, leisure, and recreational activities could be used as a means to managing stress. Interview and observation data were analyzed using SPSS. The major finding revealed that that human system has specific limitations and nature cannot be cheated. It is recommended that executives should take regular and mandatory vacation of least forty days in a year. The only answer then is rest. The research recommends that a break tends to improves and relaxes, refreshes the mind and enhances performance.

Keywords: executive, recreation, stress, tourism

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Authors: Eryati Darwin, Arina Widya Murni, Adnil Edwin Nurdin

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Background: Functional dyspepsia (FD) is a highly prevalent and heterogeneous disorder. Most patients with FD complain of symptoms related to the intake of meals. Psychological stress may promote peptic ulcer and had an effect on ulcers associated Hp, and may also trigger worsen symptoms in inflammatory disorders of the gastrointestinal. Cells in mucosal gastric stimulate the production of several cytokines, which might associated with Helicobacter pylori infection. The cascade of biological events leading to stress-induced FD remains poorly understood. Aim of Study: To determine the prion-flammatory cytokine IL-6, and Helicobacter pylori activity on mucosal gastric of FD and their association with psychological stress. Methods: The subjects of this study were dyspeptic patients who visited M. Djamil General Hospital and in two Community Health Centers in Padang. On the basis of the stress index scale to identify psychological stress by using Depression Anxiety and Stress Scale (DASS 42), subjects were divided into two groups of 20 each, stress groups and non-stress groups. All diagnoses were confirmed by review of cortisol and esophagogastroduodenoscopy reports. Gastric biopsy samples and peripheral blood were taken during diagnostic procedures. Immunohistochemistry methods were used to determine the expression of IL-6 and Hp in gastric mucosal. The data were statistically analyzed by univariate and bivariate analysis. All procedures of this study were approved by Research Ethics Committee of Medical Faculty Andalas University. Results: In this study, we enrolled 40 FD patients (26 woman and 14 men) in range between 35-56 years old. Cortisol level of blood FD patients as parameter of stress hormone which taken in the morning was significantly higher in stress group than non-stress group. The expression of IL-6 in gastric mucosa was significantly higher in stress group in compared to non-stress group (p<0,05). Helicobacter pylori activity in gastric mucosal in stress group were significantly higher than non-stress group. Conclusion: The present study showed that psychological stress can induce gastric mucosal inflammation and increase of Helicobacter pylori activity.

Keywords: functional dyspepsia, Helicobacter pylori, interleukin-6, psychological stress

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Authors: S. Silva

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Some professions had an increased risk for occupational stress and less quality of working life. Among several professions this risk is particularly preoccupant in teachers, namely high school teachers. This study aims to characterize the work stress in teachers and understand how the work stress influences their quality of working life. One hundred teachers, 60 women and 40 men with mean age of 43,2 years (SD=7,8), from North Portugal teaching in several high schools filled in the following questionnaires: Social-Demographic Questionnaire, Teacher Stress Questionnaire and the Survey of Professional Life, during January to March 2015. The results of our study show that high school teachers have several occupational stressors (M=5) and poor perceived quality of working life. They are unsatisfied with their current job and they refer to a considerable job frustration. 33% referred to no expectations about a better future in these profession and 40% have no career development. There is a strong negative correlation between stress and teacher quality of working life (r=-.775). Moderate levels of stress are related to more favorable quality of working life (r=.632). Stress, frequent in teachers, is a significant predictor of poor quality of working life. There are several stressors affecting the teachers’ performance. Career development is not considered among this professional class and it seems related to current job frustration. Considering the role of high school teacher in the development and learning of students, these results should be taken in consideration when planning the graduation and interventions with teachers.

Keywords: career, quality of working life, stress, teachers

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Authors: Parisa Alizadeh Oskuie, Shahram Baghban Ciruse

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The influence of arbuscular mycorrhizal (AM) fungus(Glomus mossea) on plant growth and leaf-water potential of tomato (lycopersicum esculentum L.cv.super star) were studied in potted culture water stress stress period of 3 months in greenhouse conditions with the soil matric potential maintained at Fc1, Fc2, Fc3, and Fc4 respectively (0.8,0.7,0.6,0.5 Fc). Seven-day-old seedlings of tomato were transferred to pots containing Glomus mossea or non-AMF. AM colonization significantly stimulated shoot dry matter and leaf-water potential but water stress significantly decreased leaf area, shoot dry matter colonization and leaf-water potential.

Keywords: leaf-water potential, plant growth, tomato, VA mycorrhiza, water-stress

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Authors: Salam K. Al-Dawery

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Despite of few research works on municipal sludge, still there is a lack of actual data. Thus, this work was focused on the conditioning and rheology of fresh activated sludge. The effect of cationic polyelectrolyte has been investigated at different concentrations and pH values in a comparative fashion. Yield stress is presented in all results indicating the minimum stress that necessary to reach flow conditions. Connections between particle-particle is the reason for this yield stress, also, the addition of polyelectrolyte causes strong bonds between particles and water resulting in the aggregation of particles which required higher shear stress in order to flow. The results from the experiments indicate that the cationic polyelectrolytes have significant effluence on the sludge characteristic and water quality such as turbidity, SVI, zone settling rate and shear stress.

Keywords: rheology, polyelectrolyte, settling volume index, turbidity

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Authors: Jayanta Kumar Mahato, Partha Sarathi De, Amrita Kundu, P. C. Chakraborti

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Ratcheting is one of the most important phenomena to be considered for design and safety assessment of structural components subjected to stress controlled asymmetric cyclic loading in the elasto-plastic domain. In the present study uniaxial ratcheting behavior of commercially pure annealed OFHC copper and aluminium with two different grain sizes has been investigated. Stress-controlled tests have been conducted at various combinations of stress amplitude and mean stress. These stresses were selected in such a way that the ratio of equivalent stress amplitude (σₐeq) to ultimate tensile strength (σUTS) of the selected materials remains constant. It is found that irrespective of grain size the ratcheting fatigue lives decrease with the increase of both stress amplitude and mean stress following power relationships. However, the effect of stress amplitude on ratcheting lives is observed higher as compared to mean stress for both the FCC metals. It is also found that for both FCC metals ratcheting fatigue lives at a constant ratio of equivalent stress amplitude (σ ₐeq) to ultimate tensile strength (σUTS) are more in case fine grain size. So far ratcheting strain rate is concerned, it decreases rapidly within first few cycles and then a steady state is reached. Finally, the ratcheting strain rate increases up to the complete failure of the specimens due to a very large increase of true stress for a substantial reduction in cross-sectional area. The steady state ratcheting strain rate increases with the increase in both stress amplitude and mean stress. Interestingly, a unique perfectly power relationship between steady state ratcheting strain rate and cycles to failure has been found irrespective of stress combination for both FCC metals. Similar to ratcheting strain rate, the strain energy density decreases rapidly within first few cycles followed by steady state and then increases up to a failure of the specimens irrespective of stress combinations for both FCC metals; but strain energy density at steady state decreases with increase in mean stress and increases with the increase of stress amplitude. From the fractography study, it is found that the void density increases with the increase of maximum stress, but the void size and void density are almost same for any combination of stress parameters considering constant maximum stress.

Keywords: ratcheting phenomena, grain size, stress parameter, ratcheting lives, ratcheting strain rate

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Authors: Erhan Çetin, Ali Kurşun, Şafak Aksoy, Merve Tunay Çetin

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The closed form study deal with elastic stress analysis of annular bi-material discs with variable thickness subjected to the mechanical and termomechanical loads. Those discs have many applications in the aerospace industry, such as gas turbines and gears. Those discs normally work under thermal and mechanical loads. Their life cycle can increase when stress components are minimized. Each material property is assumed to be isotropic. The results show that material combinations and thickness profiles play an important role in determining the responses of bi-material discs and an optimal design of those structures. Stress distribution is investigated and results are shown as graphs.

Keywords: bi-material discs, elastic stress analysis, mechanical loads, rotating discs

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Authors: Narumon Phaonakrop, Janthima Jaresitthikunchai, Sittiruk Roytrakul, Wasinee Pongprayoon

Abstract:

Chitosan has been proposed as a natural polymer, and it is derived from chitin. The objective of this research was to determine the growth promoting responses induced by chitosan at the molecular physiology level in Khao Dawk Mali 105 (KDML 105) rice (Oryza sativa L.) seedlings under drought stress by adding of 2% polyethylene glycol 4000 (PEG4000) to the nutrient solution and after removal of the drought stress (re-water). Oligomeric chitosan at 40 ppm could enhance shoot fresh weight and shoot dry weight during drought stress and re-water. After 7 days of drought stress and re-water, significant increases in chlorophyll a and chlorophyll b contents in KDML 105 cultivar were observed. The 749 phosphoproteins in rice leaf treated with chitosan could be resolved by phosphoprotein enrichment, tryptic digestion and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. They can be classified into 10 groups. Proteins involved in the metabolic process and biological regulation were upregulated in response to chitosan during drought stress. This work will help us to understand protein phosphorylation relating to chitosan response during drought stress in aromatic rice seedlings.

Keywords: Chitosan, drought, phosphoproteome, rice

Procedia PDF Downloads 122

Authors: Mohamed Barbary, Mohamed H. Abd El-azeem

Abstract:

Maneuvering non-ellipsoidal extended object tracking (M-NEOT) using high-resolution inverse synthetic aperture radar (ISAR) observations is gaining momentum recently. This work presents a new robust implementation of the Jump Markov (JM) multi-Bernoulli (MB) filter for M-NEOT, where the M-NEOT’s ISAR observations are characterized using a skewed (SK) non-symmetrically normal distribution. To cope with the possible abrupt change of kinematic state, extension, and observation distribution over an extended object when a target maneuvers, a multiple model technique is represented based on an MB-track-before-detect (TBD) filter supported by SK-sub-random matrix model (RMM) or sub-ellipses framework. Simulation results demonstrate this remarkable impact.

Keywords: maneuvering extended objects, ISAR, skewed normal distribution, sub-RMM, JM-MB-TBD filter

Procedia PDF Downloads 31

Authors: Hossein Nikandam Kermanshah, Babak Samavatian, Akbar Hemmati Sabet, Mohammad Ahmadpanah

Abstract:

This is a quasi-experimental study that has been conducted in order to compare the effectiveness of social skills training and stress management training on self-esteem and aggression in first grade high school students. Forty-five people were selected from research community and were put randomly in there groups of social skills training, stress management training and control ones. Collecting data tools in this study was devise, self-esteem and AGQ aggression questionnaire. Self-esteem and aggression questionnaires has been conducted as the pre-test and post-test. Social skills training and stress management groups participated in eight 1.5 hour session in a week. But control group did not receive any therapy. For descriptive analysis of data, statistical indicators like mean, standard deviation were used, and in inferential statistics level multi variable covariance analysis have been used. The finding result show that group training social skills and stress management is significantly effective on the self-esteem and aggression, there is a meaningful difference between training social skills and stress management on self-esteem that the preference is with group social skills training, in the difference between group social skills training and stress management on aggression, the preference is with group stress management.

Keywords: social skill training, stress management training, self-esteem aggression, psychological sciences

Procedia PDF Downloads 442