Search results for: stress study

Authors: Harun Rashid, Keerthi S. S. Atapaththu, Takashi Asaeda

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Cesium (Cs) induced growth and stress response of Nitella were studied after exposure to four concentration of the metal; i.e. 0 (control), 0.001, 0.01, and 0.1 ppm Cs in growth media. Each treatment with three replicates were randomly allocated to 12 glass beakers in a complete randomize design and the experiment was continued for 30 days. At the end of the experiment, shoot length, cesium content, total chlorophyll, and plant stress response were compared. Anti-oxidant enzyme activities (peroxidase, catalase, and ascorbic peroxidase) and the concentration of H2O2 were measured to check plant stress. The longest shoot was found in control treatment (0 ppm Cs) and the shoot length of plants exposed to 0.001 ppm was statistically similar to that of control. Concentration of cesium in plants grown at 0.001, 0.01, and 0.1 ppm were significantly higher than those in control treatments. The antioxidant enzymes activities of plants exposed to cesium were significantly higher than those grown without any Cs (control). An elevated level of H2O2 concentration was also observed in former groups of plants. Further, the reduction in chlorophyll concentration and chlorophyll fluorescence in response to cesium exposure indicated the chronically damaged photosynthetic efficiency in cesium stressed Nitella.

Keywords: antioxidant enzymes, cesium, growth, Nitella, oxidative stress

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Authors: R. Ziaie Moayed, E. Khavaninzadeh, M. Ghorbani Tochaee

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Direct shear test is widely used in soil mechanics experiment to determine the shear strength parameters of granular soils. For analysis of soil stability problems such as bearing capacity, slope stability and lateral pressure on soil retaining structures, the shear strength parameters must be known well. In the present study, shear strength parameters are determined in silty-sand mixtures. Direct shear tests are performed on 161 Firoozkooh sand with different silt content at a relative density of 70% in three vertical stress of 100, 150, and 200 kPa. Wet tamping method is used for soil sample preparation, and the results include diagrams of shear stress versus shear deformation and sample height changes against shear deformation. Accordingly, in different silt percent, the shear strength parameters of the soil such as internal friction angle and dilation angle are calculated and compared. According to the results, when the sample contains up to 10% silt, peak shear strength and internal friction angle have an upward trend. However, if the sample contains 10% to 50% of silt a downward trend is seen in peak shear strength and internal friction angle.

Keywords: shear strength parameters, direct shear test, silty sand, shear stress, shear deformation

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Authors: M. Zareh, H. Mohammadi, B. Naser

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Atherosclerotic plaque rupture is the main trigger of heart attack and brain stroke which are the leading cause of death in developed countries. Better understanding of rupture-prone plaque can help clinicians detect vulnerable plaques- rupture prone or instable plaques- and apply immediate medical treatment to prevent these life-threatening cardiovascular events. Therefore, there are plenty of studies addressing disclosure of vulnerable plaques properties. Necrotic core and fibrous tissue are two major tissues constituting atherosclerotic plaque; using histopathological and numerical approaches, many studies have demonstrated that plaque rupture is strongly associated with a large necrotic core and a thin fibrous cap, two morphological characteristic which can be acquired by two-dimensional imaging of atherosclerotic plaque present in coronary and carotid arteries. Plaque rupture is widely considered as a mechanical failure inside plaque tissue; this failure occurs when the stress within plaque excesses the strength of tissue material; hence, finite element method, a strong numerical approach, has been extensively applied to estimate stress distribution within plaques with different compositions which is then used for assessment of various vulnerability characteristics including plaque morphology, material properties and blood pressure. This study aims to evaluate significance of three-dimensional morphology on vulnerability degree of atherosclerotic plaque. To reach this end, different two-dimensional geometrical models of atherosclerotic plaques are considered based on available data and named Main 2D Models (M2M). Then, for each of these M2Ms, two three-dimensional idealistic models are created. These two 3D models represent two possible three-dimensional morphologies which might exist for a plaque with similar 2D morphology to one of M2Ms. Finite element method is employed to estimate stress, von-Mises stress, within each 3D models. Results indicate that for each M2Ms stress can significantly varies due to possible 3D morphological changes in that plaque. Also, our results show that an atherosclerotic plaque with thick cap may experience rupture if it has a critical 3D morphology. This study highlights the effect of 3D geometry of plaque on its instability degree and suggests that 3D morphology of plaque might be necessary to more effectively and accurately assess atherosclerotic plaque vulnerability.

Keywords: atherosclerotic plaque, plaque rupture, finite element method, 3D model

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Authors: Gyongyver Csapo, Andrea Czibor

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Machiavellianism is a personality trait based on the exploitation and deception of others. Machiavellian individuals are motivated to gain and to maintain power with the help of their strategic thinking, manipulation tactics, and interpersonal skills. Consequently, Machiavellianism is treated as a personality trait that can affect an individual’s career and work-related behavior. The aim of our research is to provide a narrative psychological approach to Machiavellianism in order to get a more comprehensive picture about the attitudes, values, and work-related behaviors of Machiavellian individuals. In this study, semi-structured interviews were made with employees (N=275) about their work-related experiences. Additionally, participants completed questionnaires about their turnover intention and perceived stress. The interviews were examined with narrative psychological content analysis and thematic analyzes. Based on the thematic analysis, mentioning of two topics (recognition at work and control) were associated with Machiavellianism. Scientific narrative psychological content analysis showed a negative association between Machiavellianism and positive emotions. Turnover intention and the magnitude of perceived work-related stress showed a significant positive correlation with Machiavellianism. In this study, qualitative and quantitative methodologies were combined in order to get a deeper insight of Machiavellianism from an organizational psychological perspective. Our research can contribute to a better understanding of this personality trait and provides an excellent basis for further investigations.

Keywords: machiavellianism, narrative psychology, turnover intention, work-related stress

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Authors: Adia Fatima, Naila Chand, Rifat Ullah Khan

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The goal of this study was to determine how fennel seed supplementation affected broiler growth, carcass quality, antioxidant status, and antibody titer in heat-stressed broilers. A total of 720 one-day-old broiler chickens were weighed and assigned to 28-floor pens (25 broiler chickens per pen). The broiler chickens were housed in a thermoneutral (TN) environment and were exposed to heat stress (HS). For 23 hours, the broiler chickens were kept under fluorescent lighting. For 35d, HS broiler chickens were fed a control diet and three levels of fennel seeds powder at rates of 15g/kg (Fen-15), 20 g/kg (Fen-20), and 25 g/kg (Fen-25). Overall feed intake, weight gain, and dressing % were considerably greater (P < 0.05) in Fen-25 and TN, but FCR was significantly reduced (P<0.01) in the same groups. When TN, Fen-20, and Fen-25 were compared to the control, malondialdehyde (MDA), paraoxonase (PON1), and antibody titer against New Castle disease (ND) were considerably (P < 0.05) greater. Further, the linear and quadratic response was for feed intake, weight gain, FCR, MDA, PON1, and ND titer. It was concluded that Fen-20 and Fen-25 increased broiler growth, carcass quality, antioxidant status, and immunological response under HS conditions.

Keywords: heat stress, growth, antioxidant, immunity

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Authors: Ana C. Ramos Valdivia, Ileana Vera-Reyes, Ariana A. Huerta-Heredia

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The conditions of biotic and abiotic stress in plants can lead to the generation of high amounts of reactive oxygen species (ROS), which leads through a signaling cascade and second messengers to different antioxidant defense responses including the production of secondary metabolites. A limited number of species of plants like Uncaria tomentosa (cat claw) typical of the Amazon region produce monoterpenoid oxindole alkaloids (MOA) such as isopteropodine, mitraphylline, rhynchophylline and its isomers. Moreover, in cultivated roots, the glucoindole alkaloid 3α-dihydrocadambine (DHC) is also accumulated. Several studies have demonstrated that MAO has antioxidant properties and possess important pharmacological activities such as antitumor and immunostimulant while DHC, has hypotensive and hypolipidemic effects. In order the study the regulatory concerns operating in MAO production, the links between oxidative stress and antioxidant alkaloid production in U. tomentosa root cultures were examined. Different amount of hydrogen peroxide between 0.2 -1.0 mM was added to 12 days old roots cultures showing that, this substance had a differential effect on the production of DHC and MOA whereas the viability remained in 80% after six days. Addition of 0.2 mM hydrogen peroxide increased approximately 65% MAO and DHC production (0,540 ± 0.018 and 0.618 ± 0.029 mg per g dry weight, respectively) relative to the control. On contrast, after the addition of 0.6 mM and 1 mM hydrogen peroxide, DHC accumulation into the roots gradually decreased to 53% and 93% respectively, without changes in MAO concentration, which was in relation to a twice increase of the intracellular hydrogen peroxide content. On the other hand, concentrations of DHC (0.1, 0.5 and 1.0 mM in methanol) demonstrated free-radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The calculated IC50 for all tested concentrations was 0.180 mg per ml (0.33 mM) while the calculated TE50 was 276 minutes. Our results suggest that U. tomentosa root cultures both MAO and DHC have antioxidant capacities and respond to oxidative stress with a stimulation of their production; however, in presence of a higher concentration of ROS into the roots, DHC could be oxidized.

Keywords: monoterpenoid indole alkaloid, oxidative stress, root cultures, uncaria tomentosa

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Authors: Sanat K. Dash, Rama S. Verma, Sarit K. Das

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A logarithmic microfluidic shear device was designed and fabricated for cellular mechanotransduction studies. The device contains four cell culture chambers in which flow was modulated to achieve a logarithmic increment. Resistance values were optimized to make the device compact. The network of resistances was developed according to a unique combination of series and parallel resistances as found via optimization. Simulation results done in Ansys 16.1 matched the analytical calculations and showed the shear stress distribution at different inlet flow rates. Fabrication of the device was carried out using conventional photolithography and PDMS soft lithography. Flow profile was validated taking DI water as working fluid and measuring the volume collected at all four outlets. Volumes collected at the outlets were in accordance with the simulation results at inlet flow rates ranging from 1 ml/min to 0.1 ml/min. The device can exert fluid shear stresses ranging four orders of magnitude on the culture chamber walls which will cover shear stress values from interstitial flow to blood flow. This will allow studying cell behavior in the long physiological range of shear stress in a single run reducing number of experiments.

Keywords: microfluidics, mechanotransduction, fluid shear stress, physiological shear

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Authors: Jessica Gladden

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Anxiety remains one of the most common mental health disorders in the United States. Many university students report having a high level of anxiety, with additional life stressors that might include being away from home for the first time, being around unfamiliar people, having new expectations placed on them, and often have financial struggles. Universities have the ability and opportunity to form programs that can involve students with activities that reduce stress and teach coping skills. This research includes one example of using a somatic based group format of yoga to teach these skills and assist students in applying these strategies to their daily lives. This study compared a group of 17 students participating in weekly yoga classes to 34 students who did not attend the program. The students who attended the program reported a larger reduction of anxiety on both the BAI and GAD-7 than the control group, and verbally reported additional benefits in relaxation and coping skills. This presentation will review the results of the program as well as detailing the steps taken in creating a yoga program for university students with stress and anxiety. This will include a discussion on the components of trauma-sensitive yoga and the concerns and strategies to consider when developing a program for students.

Keywords: yoga, trauma-sensitive yoga, anxiety, students

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Authors: Dongjoo Chin

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The purpose of this study was to investigate the effectiveness of an Early Intensive Behavioral Intervention (EIBI) program on infants with autism spectrum disorder (ASD) and to explore the factors predicting the effectiveness of the program, focusing on the infant's age, language ability, problem behaviors, and parental stress. 19 pairs of infants aged between 2 and 5 years who have had been diagnosed with ASD, and their parents participated in an EIBI program at a clinic providing evidence-based treatment based on applied behavior analysis. The measurement tools which were administered before and after the EIBI program and compared, included PEP-R, a curriculum evaluation, K-SIB-R, K-Vineland-II, K-CBCL, and PedsQL for the infants, and included PSI-SF and BDI-II for the parents. Statistical analysis was performed using a sample t-test and multiple regression analysis and the results were as follows. The EIBI program showed significant improvements in overall developmental age, curriculum assessment, and quality of life for infants. There was no difference in parenting stress or depression. Furthermore, measures for both children and parents at the start of the program predicted neither PEP-R nor the degree of improvement in curriculum evaluation measured six months later at the end of the program. Based on these results, the authors suggest future directions for developing an effective intensive early intervention (EIBI) program for infants with ASD in Korea, and discuss the implications and limitations of this study.

Keywords: applied behavior analysis, autism spectrum disorder, early intensive behavioral intervention, parental stress

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Authors: Anca Dinischiotu, Sorina Nicoleta Voicu

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Silica nanoparticles (SiO2-NPs) are widely used in consumer products such as paints, plastics, insulation materials, tires, concrete production, as well as in gene delivery systems and imaging procedures. Environmental human exposure to them occurs during utilization of these products, in a time-dependent manner, the uptake being by topic and inhalation route especially. SiO2-NPs enter cells and induce membrane damage, oxidative stress and inflammatory reactions in a concentration-dependent manner. In this study, MRC-5 cells (human fetal lung fibroblasts) were exposed to amorphous SiO2-NPs at a dose of 62.5 μg/ml for 24, 48 and 72 hours. The size distribution of NPs was a lognormal function, in the range 3-14 nm. A time-dependent decrease of total reduced glutathione concentration by 36%, 50%, and 78% and an increase of NO level by 62%, 32%, respectively 24% compared to control were noticed. An up-regulation of NF-kB expression by 20%, 50% respectively 10% and of Nrf-2 by 139%, 58%, and 16% compared to control after 24, 48 and 72 hours was noticed also. The expression of IL-1β, IL-6, IL-8, and COX-2 was up-regulated in a time-dependent manner. Also, the expression of MMP-2 and MMP-9 were down-regulated after 48 and 72 hours, whereas their activities raised in a time-dependent manner. Exposure of cells to NPs up-regulated the expression of inducible NO synthase, as previously was shown, and probably this is the reason for the increased level of NO, that can react with the thiol groups of reduced glutathione molecules, diminishing its concentration Nrf2 is a transcription factor translocated in nucleus, under oxidative stress, where downstream gene expression activates in order to modulate the adaptive intracellular response against oxidative stress. The cross-talk between Nrf2 and NF-kB activities regulates the inflammatory processes. The activation of NF-kB could activate up-regulation of IL-1β, IL-6, and IL-8. The increase of COX-2 expression could be correlated with IL-1β one. Also, probably in response to the pro-inflammatory cytokines, MMP-2 and MMP-9 were induced and activated. In conclusion, the exposure of MRC-5 cells to SiO2-NPs generated inflammation in a time-dependent manner.

Keywords: inflammation, MRC-5 cells, oxidative stress, silica nanoparticles

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Authors: Emmanuel Uba, Oluwasegun Omidiora, Eugenia Abiodun-Eniayekan

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The role of phonology on reading comprehension is long established in the literature. However, the vast majority of studies on the relationship between phonology and reading or comprehension among adults involve investigating the role of intonation, stress, and segmental knowledge on understanding texts. Not much attention is paid to junctural observation and its effect on the interpretation of texts. This study, therefore, presents a preliminary case-study investigation of the effect of juncture on comprehension of texts among adult Nigerian learners of English. Eighty adult learners of English in Nigeria were presented with fifteen seemingly ambiguous sentences to interpret. The sentences were structured in a way that pausing at different points would produce different interpretations. The results reveal that wrong application of pause is capable of affecting comprehension even when other phonological factors such as stress and intonation are observed properly.

Keywords: comprehension, juncture, phonology, reading

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Authors: Moon Byung Woo, Seok Chang-Sung, Koo Jae-Mean, Kim Sang-Young, Choi Jae Gu, Huh Nam-Su

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Recently, the occurrence of the earthquake has increased sharply and many of the casualties have occurred worldwide, due to the influence of earthquakes. Especially, the Fukushima nuclear power plant accident which was caused by the earthquake in 2011 has significantly increased the fear of people and the demand for the safety of the nuclear power plant. Thus, in order to prevent the earthquake accident at nuclear power plant, it is important to evaluate the fracture toughness considering the seismic loading rate. To obtain fracture toughness for the safety evaluation of nuclear power plant, it is desirable to perform experiments with a real scale pipe which is expensive and hard to perform. Therefore, many researchers have proposed various test specimens to replicate the fracture toughness of a real scale pipe. Since such specimens have several problems, the equivalent stress gradient (ESG) specimen has been recently suggested. In this study, in order to consider the effects of the dynamic loading speed on fracture toughness, the experiment was conducted by applying five different kinds of test speeds using an ESG specimen. In addition, after we performed the fracture toughness test under dynamic loading with different speeds using an ESG specimen and a standard specimen, we compared them with the test results under static loading.

Keywords: dynamic loading speed, fracture toughness, load-ratio-method, equivalent stress gradient (ESG) specimen

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Authors: Duane Booysen, Ashraf Kagee

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There is a high prevalence of violent crime and trauma exposure in South African society. Considering the prevalence of continuous violent crimes and traumatization in South Africa, the public mental health sector is required to combat the burgeoning effect of traumatic stress in South Africa. Trauma counselors, especially, provide important mental health services at primary health care to persons affected by traumatic events. Therefore, the evaluation and implementation of evidence-based trauma therapies is essential at a primary health care level in treating traumatic stress. A single-case design was used to evaluate the treatment effect of a Brief Trauma Treatment Programme treating persons who present with symptoms of posttraumatic stress disorder at a primary care trauma centre in Cape Town, South Africa. The sample consisted of six adult participants who presented with symptoms of posttraumatic stress and were assessed at baseline, during treatment, post-intervention and at 3-month follow. All participants received six sessions of trauma therapy. Assessment measures included the posttraumatic stress disorder symptom scale interviews for Diagnostic and Statistical Manual fifth edition (DSM5), the posttraumatic disorder checklist for DSM5, Beck Depression Inventory and Beck Anxiety Inventory. Results demonstrate that participants had noticeable reduced symptoms for traumatic stress, anxiety and depression despite living in contexts of violent crime and trauma. In conclusion, the article critically reflects on the need to evaluate and implement evidence-based treatments for the South African context, and how evidence-based treatments are used in developing socio-economic and cultural diverse contexts with continuous levels of violence and traumatization.

Keywords: psychological interventions, public mental health, traumatic stress, single-case design

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Authors: Areej A. Alzarqaa, Shahira S. Roushdy, Ali A. Alderfasi, Fahad A. AL-Yahya, Ahmed A. Dawaba

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The resistance of mungbean (Vigna radiata L. Wilczeck) and its physiological responses to drought stress was studied in a greenhouse pot experiment. A randomized complete block Design (RCBD) with factorial arrangement having three replications of each treatment was used. Treatments included three water deficit samples (80%, 40% and 20% of field capacity), two mungbean genotypes (Kawmay-1 and VC2010) and two root-knot nematode (Meloidogyne javanica) infection levels (infected and non-infected). Results showed that water deficit stress significantly hampered most of the studied parameters, except for the shoot water content, whereas genotypes showed highly significant differences for stomatal conductance, shoot dry weight and leaf area. Shoot water content was found to be non-significant in relation to chlorophyll b, shoot dry weight and leaf area, whereas highly significant but negatively correlated with chlorophyll a and stomatal conductance. However, all other possible correlations among studied parameters were found to be highly and positively significant. Results also showed that VC 2010 surpassed Kawmay-1 in most of studied characteristics. In the present study, genotypic variation was observed for these parameters and can be used as a basis for selection of the most promising variety under drought conditions.

Keywords: drought stress, Meloidogyne javanica, mungbean, stomatal conductivity, leaf area, root-knot nematode, shoot water content

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Authors: Roman Kalvin, Anam Nadeem, Saba Arif

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Turbocharger is a device that is driven by the turbine and increases efficiency and power output of the engine by forcing external air into the combustion chamber. This study focused on the distribution of stress on the turbine blades and total deformation that may occur during its working along with turbocharger to carry out its static structural analysis of turbine blades. Structural steel was selected as the material for turbocharger. Assembly of turbocharger and turbine blades was designed on PRO ENGINEER. Furthermore, the structural analysis is performed by using ANSYS. This research concluded that by using structural steel, the efficiency of engine is improved and by increasing number of turbine blades, more waste heat from combustion chamber is emitted.

Keywords: turbocharger, turbine blades, structural steel, ANSYS

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Authors: J. B. Sharma, Vivek Kakkar, Sunesh Kumar, K. K. Roy, Rajesh Kumari, Kavita Pandey, Smriti Hari

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Background: Stress urinary incontinence (SUI) is a common problem affecting the quality of life of women. Methods: It is a prospective study conducted over 40 women of SUI by endovaginal ultrasound on rest and Valsalva preoperatively and six months postoperatively for levator hiatus, pubovisceral thickness, urethral length, and bladder neck position. A 24-hour pad test was also performed on all women at the same time for grading of SUI. Treatment given was medical in 4 (10%), Burch colposuspension in 18 (45%), and tension-free obturator tape in 18 (45%). Results: Mean age, parity, and body mass index in the study were 41.60 years, 2.73, and 24.2 kg/m², respectively. All 40 (100%) patients had SUI, with the mean duration of symptoms being 4.04 years. On the 24-hour pad test, mild SUI was in 4 (10%), moderate SUI in 33 (82.5%), and severe SUI in 3 (7.5%), with mean preoperative 24-hour pad test being 36.69 gm which significantly reduced to 9.79 gm postoperatively (p 0.001). There was a significant change in levator hiatus and pubovisceral thickness with the treatment of SUI. Overall urethral length increased, but there was a significant decrease in urethral length on Valsalva after the treatment (0.40 versus 0.28 cm, p 0.04) and a significant reduction in bladder neck descent after Valsalva after treatment (0.41 cm versus 0.27 cm, p 0.001). Conclusion: Endovaginal ultrasound and 24-hour pad test are useful diagnostic modalities for SUI diagnosis and to see the impact of treatment.

Keywords: stress urinary incontinence, endovaginal ultrasound, 24-hours pad test, pubovisceral muscle thickness

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Authors: Kuan-Han Lin, Kuan-Yin Lin, Ka-Chun Siu

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The purpose of this systematic review was to determine the impact of post-traumatic stress disorders (PTSD) symptom or depressive symptoms on return to work (RTW) after occupational injury. The original articles of clinical trials and observational studies from PubMed, MEDLINE, and PsycINFO between January 1980 and November 2016 were retrieved. Two reviewers evaluated the abstracts identified by the search criteria for full-text review. To be included in the final analysis, studies were required to use either intervention or observational study design to examine the association between psychiatric symptoms and RTW. A modified checklist designed by Downs & Black and Crombie was used to assess the methodological quality of included study. A total of 58 articles were identified from the electronic databases after duplicate removed. Seven studies fulfilled the inclusion criteria and were critically reviewed. The rates of RTW in the included studies were reported to be 6% to 63.6% among workers after occupational injuries. This review found that post-traumatic stress symptom and depressive symptoms were negatively associated with RTW. Although the impact of psychiatric symptoms on RTW after occupational injury remains poorly understood, this review brought up the important information that injured workers with psychiatric symptoms had poor RTW outcome. Future work should address the effective management of psychiatric factors affecting RTW among workers.

Keywords: depressive symptom, occupational injury, post-traumatic stress disorder, return to work

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Authors: Ja’afar U., A. M. Gumi, Salisu N., Obadiah C. D.

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Rice is susceptible to flooding due to its semi-aquatic characteristics, which enable it to thrive in wet or submerged environments. The development of aerenchyma allows for oxygen transfer, enabling faster lengthening of submerged shoot organs. Rice's germination and early seedling growth phases are highly intolerant of submersion, resulting in survival in low-oxygen environments. The research involved a study on rice plants treated with salicylic acid at different concentrations. Hypo was used for washing, while a reagent was used for submergence treatment. The plants were waterlogged for 11 days and submerged for 7 days, with control plants receiving distilled water. The study found a significant difference between Jirani Zawara's control and treated plants, with plants treated with 2 g/L of S.A. showing a 6.00 node increase per plant and Faro cultivars having more nodes. The study found significant differences between the control and treated plants, with the Jirani Zawara plant showing longer internode lengths and the Faro cultivar having longer internode lengths, while the B.G. cultivar had the longest. The research found that the Jirani Zawara cultivar treated with 3 g/L of S.A. produced tallest plants, with heights increasing from 14.43 cm to 15.50 cm in Faro cultivar S.A., and the highest height was 16.30 cm. The study reveals that salicylic acid significantly enhances the number of nodes, internode length, plant height, and root length in rice cultivars, thereby improving submerged stress recovery and promoting plant development.

Keywords: rice, submergence, stress, salicylic acid

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Authors: Filali Kamel, Sbartai Badreddine

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The cyclic resistance curves developed by Andrus and Stokoe related to shear wave velocity case history databases are frequently used in accordance with the assumption of the Seed and Idriss simplified procedure. These cyclic resistance curves were deduced using a database according to the cyclic stress ratio (CSR) proposed by Seed and Idriss. Their approach is founded on the hypothesis that the dynamic cyclic shear stress (τd) is always less than that given by the simplified procedure (τr), as deduced by Seed and Idriss through their simplifying assumptions (rd= τd / τr <1). In 2017, Filali and Sbartai demonstrated that rd can often exceed 1, and they proposed a correction for the CSR in cases where rd > 1. Therefore, the correction of CSR implies that the cyclic resistance ratio (CRR) must also be corrected because it is defined by the boundary curve, which separates the liquefied and nonliqueified cases plotted using the original CSR of Seed and Idriss on which values of CRR are equal to CSR. For this purpose, in the context of this study, we have proposed in the range when the peak ground acceleration is ≤0.30g, which corresponds to rd>1, a modified boundary curve in accordance with the corrected version of the simplified method, which provides the safest case, generalize its use for any used earthquakes and allows the simplified method to be the more conservative.

Keywords: liquefaction, soil, earthquake, simplified method, cyclic stress ratio, cyclique resistance ratio

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Authors: Naoyuki Sugihashi, Toshiharu Kishi

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The probability of occurrence of thermal cracks in mass concrete in Japan is evaluated by the cracking probability diagram that represents the relationship between the thermal cracking index and the probability of occurrence of cracks in the actual structure. In this paper, we propose a method to directly calculate the cracking probability, following a probabilistic theory by modeling the variance of tensile stress and tensile strength. In this method, the relationship between the variance of tensile stress and tensile strength, the thermal cracking index, and the cracking probability are formulated and presented. In addition, standard deviation of tensile stress and tensile strength was identified, and the method of calculating cracking probability in a general construction controlled environment was also demonstrated.

Keywords: thermal crack control, mass concrete, thermal cracking probability, durability of concrete, calculating method of cracking probability

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Authors: Hyun Kyu Cho, Jun Soo Kim, Young Hoon Lee, Sang Hoon Kang, Young Chul Park

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In the study, structure for one of offshore drilling system APV(Air Pressure Vessle) modules was designed by using topology optimum design and performed structural safety evaluation according to DNV rules. 3D model created base on design area and non-design area separated by using topology optimization for the environmental loads. This model separated 17 types for wind loads and dynamic loads and performed structural analysis evaluation for each model. As a result, the maximum stress occurred 181.25MPa.

Keywords: APV, topology optimum design, DNV, structural analysis, stress

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Authors: Ali Haghiri

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This research has been to investigate the cause of the stress corrosion cracking on dryer equipment (2DR-1745 and DR-1402) in Shahid Tondguyan Petrochemical Company (STPC). These dryers are as a drying powder Terphetalic acid in CTA2 and CTA1 unit. After passing through RVF equipment, wet cake moisture content of about 14% and temperature of 90C changed into a dry cake with a moisture content of less than 0.1% and the final temperature of about 140C and sent out Final Silo (FS-1820). After the declaration of the operation department concerning the observation of acid leakage under the primary insulation was decided that at the first opportunity, this issue must be investigated. So, after the shutdown of a unit at the date 2012/10/20 (2DR-1745) and 2021/11/24 (DR-1402) and after washing the dryer wall, insulation around the wall opened and it was found to crack and leakage from some points.

Keywords: stress corrosion cracking, residual stress, austenitic stainless steel, Br- ion

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Authors: Nishant Shrivastava, D. K. Sehgal

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In Finite Element Technique nodal stresses are calculated through displacement as nodes. In this process, the displacement calculated at nodes is sufficiently good enough but stresses calculated at nodes are not sufficiently accurate. Therefore, the accuracy in the stress computation in FEM models based on the displacement technique is obviously matter of concern for computational time in shape optimization of engineering problems. In the present work same is focused to find out unique points within the element as well as the boundary of the element so, that good accuracy in stress computation can be achieved. Generally, major optimal stress points are located in domain of the element some points have been also located at boundary of the element where stresses are fairly accurate as compared to nodal values. Then, it is subsequently concluded that there is an existence of unique points within the element, where stresses have higher accuracy than other points in the elements. Therefore, it is main aim is to evolve a generalized procedure for the determination of the optimal stress location inside the element as well as at the boundaries of the element and verify the same with results from numerical experimentation. The results of quadratic 9 noded serendipity elements are presented and the location of distinct optimal stress points is determined inside the element, as well as at the boundaries. The theoretical results indicate various optimal stress locations are in local coordinates at origin and at a distance of 0.577 in both directions from origin. Also, at the boundaries optimal stress locations are at the midpoints of the element boundary and the locations are at a distance of 0.577 from the origin in both directions. The above findings were verified through experimentation and findings were authenticated. For numerical experimentation five engineering problems were identified and the numerical results of 9-noded element were compared to those obtained by using the same order of 25-noded quadratic Lagrangian elements, which are considered as standard. Then root mean square errors are plotted with respect to various locations within the elements as well as the boundaries and conclusions were drawn. After numerical verification it is noted that in a 9-noded element, origin and locations at a distance of 0.577 from origin in both directions are the best sampling points for the stresses. It was also noted that stresses calculated within line at boundary enclosed by 0.577 midpoints are also very good and the error found is very less. When sampling points move away from these points, then it causes line zone error to increase rapidly. Thus, it is established that there are unique points at boundary of element where stresses are accurate, which can be utilized in solving various engineering problems and are also useful in shape optimizations.

Keywords: finite elements, Lagrangian, optimal stress location, serendipity

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Authors: Petra Hurbišová, Monika Davidová

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The article deals with the readiness of military professionals for challenging situations. It discusses higher requirements on the psychical endurance of military professionals arising from the specific nature of the military occupation, which is typical for being very difficult to maintain regularity, which is in accordance with the hygiene of work alternated by relaxation. The soldier must be able to serve in the long term and constantly intense performance that goes beyond human tolerance to stress situations. A challenging situation is always associated with overcoming difficulties, obstacles and complicated circumstances or using unusual methods, ways and means to achieve the desired (expected) objectives, performing a given task or satisfying an important need. This paper describes the categories of challenging situations, their classification and characteristics. Attention is also paid to the formation of personality in challenging situations, coping with stress in challenging situations, Phases of solutions of stressful situations, resistance to challenging life situations and its factors. Finally, the article is focused on increasing the readiness of military professionals for challenging situations.

Keywords: coping, challenging situations, stress, stressful situations, military professionals, resilience

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Authors: Marianna De Almeida

Abstract:

Greek secondary education is a highly selective system with regard to the access of students to Greek universities. Since access from elementary to lower secondary education and afterward to upper secondary education is rather liberal and almost free of selective mechanisms, the basic selection process comes after graduating from upper secondary school into play when students go through a highly selective process for university entry. This structure is responsible for the experience of extreme stress on the part of the candidates during a period of at least two years before the entrance examination leading to a radical change in students' everyday life routines. Instead of the school being an important agent for academic and psychological support, it seems that other agents, such as the informal private preparatory school and the student's families, take on the supportive role.

Keywords: stress, entrance examinations, family support, secondary education

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Authors: M. Abdollahi, S. N. Moghaddas Tafreshi

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Expanded polystyrene (EPS) geofoam is often used in below ground applications in geotechnical engineering. A most recent configuration system implemented in roadways to protect lifelines such as buried pipes, electrical cables and culvert systems could be consisted of two EPS geofoam blocks, “posts” placed on each side of the structure, an EPS block capping, “beam” put atop two posts, and soil cover on the beam. In this configuration, a rectangular void space will be built atop the lifeline. EPS blocks will stand all the imposed vertical forces due to their strength and deformability, thus the lifeline will experience no vertical stress. The present paper describes the results of a numerical study on the post and beam configuration subjected to the static loading. Three-dimensional finite element analysis using ABAQUS software is carried out to investigate the effect of different parameters such as beam thickness, soil thickness over the beam, post height to width ratio, EPS density, and free span between two posts, on the stress distribution and the deflection of the beam. The results show favorable performance of EPS geofoam for protecting sensitive infrastructures.

Keywords: beam, EPS block, numerical analysis, post, stress distribution

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Authors: Mojtaba Esmaeilzad Limoudehi, Ebrahim Amiri

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Water scarcity is now one of the leading challenges for human societies. In this regard, recognizing the relationship between soil, water, plant growth, and plant response to stress is very significant. In this paper, considering the importance of drought stress and the role of choosing suitable cultivars in resistance against drought, a split-plot experiment using early, intermediate, and late-maturing cultivars was carried out in Katul filed, Golestan province during two cultivation years of 2015 and 2016. The main factor was irrigation intervals at four levels, including 7 days, 14 days, 21 days, and 28 days. The subfactor was the subplot of six maize cultivars (two early maturing cultivars, two medium maturing cultivars, and two late-maturing cultivars). The results of variance analysis have revealed that irrigation interval and cultivars treatment have significant effects on the number of grain in each corn, number of rows in each corn, number of grain per row, the weight of 1000 grains, grain yield, and biomass yield. Although, the interaction of these two factors on the mentioned attributes was meaningful. The best grain yield was achieved at 7 days irrigation interval and late maturing maize cultivars treatment, which was equal to 12301 kg/ha.

Keywords: corn, growth period, optimization, stress

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Authors: K. Chalernpon, P. Aroonjarattham, K. Aroonjarattham

Abstract:

Total hip replacement had been one of the most successful operations in hip arthritis surgery. The purpose of this research had been to develop a dynamic hip contact of Thai femoral bone to analyze the stress distribution on the implant and the strain distribution on the bone model under daily activities and compared with the static load simulation. The results showed the different of maximum von Mises stress 0.14 percent under walking and 0.03 percent under climbing stair condition and the different of equivalent total strain 0.52 percent under walking and 0.05 percent under climbing stair condition. The muscular forces should be evaluated with dynamic condition to reduce the maximum von Mises stress and equivalent total strain.

Keywords: dynamic loading, static load, hip prosthesis, Thai femur, femoral bone, finite element analysis

Procedia PDF Downloads 347

Authors: Vijaya Nirmala Pangi, K. V. Subhramanyam, C. Vijay Lakshmi

Abstract:

Background: The prevalence of Type 2 Diabetes Mellitus is increasing drastically at a vigorous rate all over the world population. Aim: The present study aims to determine the prevalence of type-2 diabetes mellitus in Paderu tribal area population of Visakhapatnam district, located in northeastern region of Andhra Pradesh. Methods: A random sampling method was followed in 1025 subjects including controls (n=25) and determined 75-g oral glucose tolerance test to assess the presence of type 2 diabetes mellitus. The effect of anthropometric factors like age, gender, literacy, socio economic status, and environmental risk factors such as body fat response, hypertension and psychophysical stress response were determined in the studied subjects. Results: 78 (7.8%) were diabetic. Type 2 Diabetes Mellitus was found to be comparable between the two genders. Prevalence of diabetes was observed to be high in illiterate, low economic status subjects. Body fat response was comparable between control and diabetic subjects. However hypertension, stress associated enzymes showed significant (p < 0.05) decrease in diabetic subjects compared to controls in both the genders. Conclusion: It appears that there is a rising pattern in the prevalence of diabetes mellitus in tribal area, Paderu, Andhra Pradesh, India compared to previous rural studies.

Keywords: anthropometric studies, hypertension, oral glucose tolerance test, stress enzymes, type-2 diabetes mellitus

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Authors: Ravi Raghav Sonani, Niraj Kumar Singh, Jitendra Kumar, Datta Madamwar

Abstract:

Phycobiliproteins (PBPs) are light harvesting proteins showing very strong absorbance and fluorescence in the visible range of the solar spectrum. Phycoerythrin (PE) and phycocyanin (PC) are majorly found PBPs in the cyanobacteria and red algae. In the present study, we have investigated the reactive oxygen species (ROS)-averting capacity of purified PE and PC of cyanobacterial origin. Furthermore, the possibility - whether the ROS-averting potential of PBPs can be explored in the therapeutics of oxidative stress associated physiological anomalies including aging and neurodegenerative diseases. The nematode Caenorhabditis elegans has been used as model organism in this study. PE and PC treatment moderated normal aging and associated physiological functionalities like pharyngeal pumping and locomotion of C. elegans. Moreover, PE-treatment enhanced the stress (oxidative and heat) tolerance upon PE and PC treatment. Specifically, PE treatment was also noted to moderate the progression of Alzheimer’s disease in transgenic C. elegans CL4176. However, PC-treatment curtailed the polyQ aggregation mediated proteotoxicity in C. elegans AM141 (Huntington disease model) under stressed (paraquat stress) as well as normal conditions. The effectiveness of PE and PC in expanding the lifespan of mutant C. elegans knockout for some up- (daf 16) and down- (daf-2 and age-1) stream regulators of insulin/IGF-1 signalling (IIS) shows the independency of their effects from DAF-2–AGE-1–DAF-16 signalling pathway. In conclusion, the present report demonstrates the anti-aging and neuro-protective potential of cyanobacterial PE and PC.

Keywords: phycobiliproteins, aging, alzheimer, huntington, C. elegans

Procedia PDF Downloads 389