Search results for: organozational role stress

Authors: Khairul Zahreen Mohd Arof, Rahimah Muhamad

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Oil palm fiber (OPF) is a fibrous material produced from the waste of palm oil industry which is suitable to be used in construction industry. The applications of OPF in concrete can reduce the material costs and enhance concrete behavior. Dog-bone test provides significant results for investigating the behavior of fiber reinforced concrete under tensile loading. It is able to provide stress-strain profile, modulus of elasticity, stress at cracking point and total crack width. In this research, dog-bone tests have been conducted to analyze total crack width, stress-strain profile, and modulus of elasticity of OPFC. Specimens are in a dog-bone shape with a long notch in the middle as compared to the end, to ensure cracks occur only within the notch. Tests were instrumented using a universal testing machine Shimadzu 300kN, a linear variable differential transformer and two strain gauges. A total of nine specimens with different fibers at fiber volume fractions of 0.75%, 1.00%, and 1.25% have been tested to analyze the behavior under tensile loading. Also, three specimens of plain concrete fiber have been tested as control specimens. The tensile test of all specimens have been carried out for concrete age exceed 28 days. It shows that OPFC able to reduce total crack width. In addition, OPFC has higher cracking stress than plain concrete. The study shows plain concrete can be improved with the addition of OPF.

Keywords: cracks, crack width, dog-bone test, oil palm fiber concrete

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Authors: Aminul Islam

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The issue of aging is now an emerging aspect of all over the world. Both the rural and urban societies of our country are not immune from this problem. This study mainly explored the influence of wealth on the enjoyment of role and status of the elderly in rural Bangladesh. It is based on empirical findings from the four villages of Gopalnagar union of Dhunat upazila of Bogra district. The study depicted that wealth has much influence regarding the enjoyment of role and status. Mixed approach has been given priority in this study. Survey, observation, case study and life history methods and focus group discussion technique have also been used in this study. Data have been collected from both primary and secondary sources. Simple random sampling procedure has also been followed in this study.

Keywords: wealth, role status, elderly

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Authors: Amari Khaoula, Berrahou Mohamed

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The topic of our article revolves around a numerical and comparative analysis between two notched Boron/epoxy plates that are U-shaped and the other V-shaped, cracked, and repaired by a rectangular patch of the same composite material; the finite element method was used for the analytical study and comparison of the results obtained for determining the optimal shape of notch which will give a longer life to the repair. In this context, we studied the variation of the stress intensity factor, the evolution of the damaged area, and the calculation of the ratio of the damaged area according to the crack length and the concentration of the Von Mises stresses as a function of the lengths of the paths. According to the results obtained, we conclude that the notch plate U is the optimal one than notch plate V because it has lower values either for the stress intensity factor (SIF), damaged area ratio (Dᵣ), or the Von Mises stresses.

Keywords: the notch U, the notch V, the finite element method FEM, comparison, rectangular patch, composite, stress intensity factor, damaged area ratio, Von Mises stresses

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Authors: Nicolas Meylan, Eric Tardif

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Many studies have highlighted the links between substance use and school difficulties. However, most of these studies address only the consumption in terms of frequency without considering the different types of behavior (use, abuse, dependence). Moreover, little is known about the associations between substance use and variables such as school engagement and school burnout recently described as a positive state of mind and an exhaustion syndrome related to school, respectively. Through this study, we wish to describe and compare school-related variables in adolescents with different type of substance use. Our study focuses on 402 Swiss adolescents, aged between 14 and 19 years old. They responded collectively and anonymously to a set of scales assessing substance use and several school variables (social support, stress, burnout, engagement and school climate). First, results on frequency and severity of substance use are relatively close to those observed in other studies. Second, it also appears that certain dimensions of stress, burnout, engagement and school climate are associated with the frequency of alcohol and cannabis consumption. Finally, adolescents’ substance abusers show particularly high scores of burnout, cynicism and stress related to workload, which can be understand as self-medication behavior. Additional analyzes are underway to clarify these associations. Results are discussed in terms of implications for research and clinical practice in academic burnout.

Keywords: school burnout, school engagement, adolescence, substance use, self-medication

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Authors: Sarada Nivedita Bhuyan

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Earthquake is the sudden, rapid movement of the earth’s crust and is the natural means of releasing stress. Tectonic plates play a major role for earthquakes as tectonic plates are the crust of the planet. The boundary lines of tectonic plates are usually known as fault lines. To understand an earthquake before its occurrence, different types of earthquake precursors are studied by different researchers. Surface temperature, strange cloud cover, earth’s electric field, geomagnetic phenomena, ground water level, active faults, ionospheric anomalies, tectonic movements are taken as parameters for earthquake study by different researchers. In this paper we tried to gather complete and helpful information of earthquake precursors which have been studied until now.

Keywords: earthquake precursors, earthquake, tectonic plates, fault

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Authors: Tri Sulistyaningtyas, Yani Suryani, Dana Waskita, Linda Handayani Sukaemi, Ferry Fauzi Hermawan

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The enthusiasm of foreigners studying the Indonesian language by Foreign Speakers (BIPA) was documented in a sitcom "International Class". Tone and stress when they speak the Indonesian language is unique and different from Indonesian pronunciation. By using the Praat program, this research aims to describe prosodic Indonesian language which is spoken by ‘International Class” actors consisting of Abbas from Nigeria, Lee from Korea, and Kotaro from Japan. Data for the research are taken from the video sitcom "International Class" that aired on Indonesian television. The results of this study revealed that pitch movement that arises when pronouncing Indonesian sentences was up and down gradually, there is also a rise and fall sharply. In terms of stress, respondents tend to contain a lot of stress when pronouncing Indonesian sentences. Meanwhile, in terms of temporal structure, the duration pronouncing Indonesian sentences tends to be longer than that of Indonesian speakers.

Keywords: melodic structure, temporal structure, prosody, experimental phonetics, international class

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Authors: Olusola Olalekan Elekofehinti, Isaac Gbadura Adanlawo, Joao Batista Teixeira Rocha

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We evaluated the potential neuroprotective effect of Phyllantus nuriri against Fe2+ and SNP induced oxidative stress in mitochondria of rats brain. Cellular viability was assessed by MTT reduction, reactive oxygen species (ROS) generation was measured using the probe 2,7-dichlorofluorescein diacetate (DCFH-DA). Glutathione content was measured using dithionitrobenzoic acid (DTNB). Fe2+ (10µM) and SNP (5µM) significantly decreased mitochondrial activity, assessed by MTT reduction assay, in a dose-dependent manner, this occurred in parallel with increased glutathione oxidation, ROS production and lipid peroxidation end-products (thiobarbituric acid reactive substances, TBARS). The co-incubation with methanolic extract of Phyllantus nuriri (10-100 µg/ml) reduced the disruption of mitochondrial activity, gluthathione oxidation, ROS production as well as the increase in TBARS levels caused by both Fe2+ and SNP in a dose dependent manner. HPLC analysis of the extract revealed the presence of gallic acid (20.54±0.01), caffeic acid (7.93±0.02), rutin (25.31±0.05), quercetin (31.28±0.03) and kaemferol (14.36±0.01). This result suggests that these phytochemicals account for the protective actions of Phyllantus nuriri against Fe2+ and SNP -induced oxidative stress. Our results show that Phyllantus nuriri consist important bioactive molecules in the search for an improved therapy against the deleterious effects of Fe2+, an intrinsic producer of reactive oxygen species (ROS), that leads to neuronal oxidative stress and neurodegeneration.

Keywords: Phyllantus niruri, neuroprotection, oxidative stress, mitochondria, synaptosome

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Authors: Shakeela Ahmed, Nabanita Hazarika

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The study aims to understand the effects of dementia on family members. The primary objectives of this research are to identify the main reasons for dementia among the elderly, understand the struggles and stigmas faced by the family members, and understand the effects of dementia on family members. The research employs a qualitative method and utilizes unstructured interviews with family members, counselors and caregivers. A descriptive research design is employed, and thematic analysis is used to analyze the data. A total of 17 family members in the age group of 54-69 years were interviewed, along with 2 counselors and 2 caretakers. In understanding dementia, the researcher has reviewed articles, and the studies revealed diverse meanings, symptoms, stages attached to dementia, and the complex interplay of protective and risk factors for dementia. However, in understanding dementia and its effects on families, there is a lack of studies in relation to the significant effects of dementia on family members and their role as primary caregivers. Therefore, an attempt has been made to understand the effects of dementia on family members, along with ways to improve dementia care for family members. The purpose of the study was to understand the effects and challenges of dementia on family members, the psychosocial reasons for dementia among the elderly, and the various struggles and stigmas faced by the family members of dementia patients. The major findings of the study indicate that people with dementia are cared for by family members at home. Dementia has a significant impact on family members. Family member's quality of life is affected; they experience feelings of anxiety, stress, irritation, frustration, and fear as they watch their loved ones struggle with dementia. They also experience financial strain, as dementia care, medication, and therapy are expensive. Another common impact is the role reversal of family members for their loved ones with dementia. There is a lack of awareness and social understanding about dementia, which leads to family members experiencing stigma and struggles. Caregivers are unable to take care of themselves, and many times, the primary caregiver, a spouse who is elderly, experiences acute stress and a physical inability to meet the demands of being a caregiver. Strategies to improve dementia care are understanding dementia, being patient with the person, showing love and care for the person, avoiding provoking the person, distracting them, offering reassurance, playing their favorite music, talking about things they love, going through old memories, following a structured routine, and remaining calm. The study has made an attempt to provide strategies to manage dementia care, understanding the struggles family members go through, and raising awareness about dementia that will enable further research and investigations.

Keywords: elderly, dementia, stigma, family members

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Authors: Artur Cichowicz

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The last active mine in the Central Rand Goldfields area (50 km x 15 km) ceased operations in 2008. This resulted in the closure of the pumping stations, which previously maintained the underground water level in the mining voids. As a direct consequence of the water being allowed to flood the mine voids, seismic activity has increased directly beneath the populated area of Johannesburg. Monitoring of seismicity in the area has been on-going for over five years using the network of 17 strong ground motion sensors. The objective of the project is to improve strategies for mine closure. The evolution of the seismicity pattern was investigated in detail. Special attention was given to seismic source parameters such as magnitude, scalar seismic moment and static stress drop. Most events are located within historical mine boundaries. The seismicity pattern shows a strong relationship between the presence of the mining void and high levels of seismicity; no seismicity migration patterns were observed outside the areas of old mining. Seven years after the pumping stopped, the evolution of the seismicity has indicated that the area is not yet in equilibrium. The level of seismicity in the area appears to not be decreasing over time since the number of strong events, with Mw magnitudes above 2, is still as high as it was when monitoring began over five years ago. The average rate of seismic deformation is 1.6x1013 Nm/year. Constant seismic deformation was not observed over the last 5 years. The deviation from the average is in the order of 6x10^13 Nm/year, which is a significant deviation. The variation of cumulative seismic moment indicates that a constant deformation rate model is not suitable. Over the most recent five year period, the total cumulative seismic moment released in the Central Rand Basin was 9.0x10^14 Nm. This is equivalent to one earthquake of magnitude 3.9. This is significantly less than what was experienced during the mining operation. Characterization of seismicity triggered by a rising water level in the area can be achieved through the estimation of source parameters. Static stress drop heavily influences ground motion amplitude, which plays an important role in risk assessments of potential seismic hazards in inhabited areas. The observed static stress drop in this study varied from 0.05 MPa to 10 MPa. It was found that large static stress drops could be associated with both small and large events. The temporal evolution of the inter-event time provides an understanding of the physical mechanisms of earthquake interaction. Changes in the characteristics of the inter-event time are produced when a stress change is applied to a group of faults in the region. Results from this study indicate that the fluid-induced source has a shorter inter-event time in comparison to a random distribution. This behaviour corresponds to a clustering of events, in which short recurrence times tend to be close to each other, forming clusters of events.

Keywords: inter-event time, fluid induced seismicity, mine closure, spectral parameters of seismic source

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Authors: Meitham Amereh, Mohsen Akbari, Ben Nadler

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Cancer has been recognized as one of the most challenging problems in biology and medicine. Aggressive tumors are a lethal type of cancers characterized by high genomic instability, rapid progression, invasiveness, and therapeutic resistance. Their behavior involves complicated molecular biology and consequential dynamics. Although tremendous effort has been devoted to developing therapeutic approaches, there is still a huge need for new insights into the dark aspects of tumors. As one of the key requirements in better understanding the complex behavior of tumors, mathematical modeling and continuum physics, in particular, play a pivotal role. Mathematical modeling can provide a quantitative prediction on biological processes and help interpret complicated physiological interactions in tumors microenvironment. The pathophysiology of aggressive tumors is strongly affected by the extracellular cues such as stresses produced by mechanical forces between the tumor and the host tissue. During the tumor progression, the growing mass displaces the surrounding extracellular matrix (ECM), and due to the level of tissue stiffness, stress accumulates inside the tumor. The produced stress can influence the tumor by breaking adherent junctions. During this process, the tumor stops the rapid proliferation and begins to remodel its shape to preserve the homeostatic equilibrium state. To reach this, the tumor, in turn, upregulates epithelial to mesenchymal transit-inducing transcription factors (EMT-TFs). These EMT-TFs are involved in various signaling cascades, which are often associated with tumor invasiveness and malignancy. In this work, we modeled the tumor as a growing hyperplastic mass and investigated the effects of mechanical stress from surrounding ECM on tumor invasion. The invasion is modeled as volume-preserving inelastic evolution. In this framework, principal balance laws are considered for tumor mass, linear momentum, and diffusion of nutrients. Also, mechanical interactions between the tumor and ECM is modeled using Ciarlet constitutive strain energy function, and dissipation inequality is utilized to model the volumetric growth rate. System parameters, such as rate of nutrient uptake and cell proliferation, are obtained experimentally. To validate the model, human Glioblastoma multiforme (hGBM) tumor spheroids were incorporated inside Matrigel/Alginate composite hydrogel and was injected into a microfluidic chip to mimic the tumor’s natural microenvironment. The invasion structure was analyzed by imaging the spheroid over time. Also, the expression of transcriptional factors involved in invasion was measured by immune-staining the tumor. The volumetric growth, stress distribution, and inelastic evolution of tumors were predicted by the model. Results showed that the level of invasion is in direct correlation with the level of predicted stress within the tumor. Moreover, the invasion length measured by fluorescent imaging was shown to be related to the inelastic evolution of tumors obtained by the model.

Keywords: cancer, invasion, mathematical modeling, microfluidic chip, tumor spheroids

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Authors: Emmanuel Carlo Belara, Albert John Dela Merced, Mark Anthony Dominguez, Diomari Erasga, Jerome Ferrer, Bernard Ombrog

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Social distancing errors are a common prevalence between vaccinated and unvaccinated in the Filipino community. This study aims to identify and relate the factors on how they affect our daily lives. Observed factors include memory, attention, anxiety, decision-making, and stress. Upon applying the ergonomic tools and statistical treatment such as t-test and multiple linear regression, stress and attention turned out to have the most impact to the errors of social distancing.

Keywords: vaccinated, unvaccinated, socoal distancing, filipinos

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Authors: Kyung-Tae Lee, Li Li Wang, Kwang-Woo Jung, Yong-Sun Bahn

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Microtubules are involved in mechanical support, cytoplasmic organization as well as in a number of cellular processes by interacting with diverse microtubule-associated proteins (MAPs), such as plus-end tracking proteins, motor proteins, and tubulin-folding cofactors. A common feature of these proteins is the presence of a cytoskeleton-associated protein-glycine-rich (CAP-Gly) domain, which is evolutionarily conserved and generally considered to bind to α-tubulin to regulate functions of microtubules. However, there has been a dearth of research on CAP-Gly proteins in fungal pathogens, including Cryptococcus neoformans, which causes fatal meningoencephalitis globally. In this study, we identified five CAP-Gly proteins encoding genes in C. neoformans. Among these, Cgp1, encoded by CNAG_06352, has a unique domain structure that has not been reported before in other eukaryotes. Supporting the role of Cpg1 in microtubule-related functions, we demonstrate that deletion or overexpression of CGP1 alters cellular susceptibility to thiabendazole, a microtubule destabilizer, and Cgp1 is co-localized with cytoplasmic microtubules. Related to the cellular functions of microtubules, Cgp1 also governs maintenance of membrane stability and genotoxic stress responses. Furthermore, we demonstrate that Cgp1 uniquely regulates sexual differentiation of C. neoformans with distinct roles in the early and late stage of mating. Our domain analysis reveals that the CAP-Gly domain plays major roles in all the functions of Cgp1. Finally, the cgp1Δ mutant is attenuated in virulence. In conclusion, this novel CAP-Gly protein, Cgp1, has pleotropic roles in regulating growth, stress responses, differentiation and pathogenicity of C. neoformans.

Keywords: human fungal pathogen, CAP-Glycine protein, microtubule, meningoencephalitis

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Authors: Fadwa Alhalaiqa, Othman Alfuqaha, Anas H. Khalifeh, Mahmoud Alsaraireh, Rami Masa’Deh, Natija S Manaa

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Background: Post-traumatic stress disorders (PTSD) usually occur after traumatic occurrences that exceed the range of common human experience. This study aimed to test the psychometric properties of PCL-5 checklist for the 20 PTSD symptoms from DSM-5 among Lebanese population and to identify the prevalence of PTSD. Methods: A cross sectional survey of PCL5 among 950 Lebanese using the online survey platform by Google form was conducted. Snowball recruitment was used to identify participants for the survey. STROBE guideline was used in reporting the current study. Results: Face content, construct, discriminant, and convergent validity had been accomplished of PCL-5. The reliability by Cronbach alpha, composite, and average variance extracted were set superior. We found also that more than half of the participants (55.6%) scored 33 or above, which is the cutoff score for a likely diagnosis of PTSD. Conclusion: The current study provides further support for the Arabic version PCL-5 validity and reliability among non-Western populations. This support using this tool in the screening of PTSD.

Keywords: post traumatic stress disorder, psychometric properties, stress, adult population

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Authors: Y. S. Mohamed, L. A. Ahmed, H. A. Salem, A. M. Agha

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Liver Fibrosis is one of the most serious conditions that affect the Egyptian society. In the present study, the effect of nicorandil was investigated in experimentally-induced liver fibrosis by bile duct ligation in rats. Nicorandil (3mg/kg/day) was given orally 24 h after bile duct ligation for 14 days till the end of the experiment. Nicorandil group showed a significant improvement in liver function tests (ALT and ALP) as well as a significant decrease in oxidative stress biomarkers (TBARS and GSH), area of fibrosis and activity of hepatic stellate cells as indicated by decreased expression of alpha smooth muscle actin.Moreover, nicorandil treatment decreased HSCs proliferation due to its inhibitory effects on protein kinase C(PKC) and Platelet derived growth factor (PDGF) . Oral administration of either glibenclamide (10 mg/kg/day)(a KATP channel blocker) or L-NAME (30 mg/kg/day) (an inhibitor of nitric oxide synthase) blocked the protective effects of nicorandil. However, nicorandil and L-NAME treated group showed more or less results similar to that of untreated bile duct ligated group. In conclusion, nicorandil was effective against the development of bile duct ligated-induced liver fibrosis in rats where activation of the NO pathway plays an important role in the protective effect nicorandil.

Keywords: hepatic stellate cells, nicorandil, nitric oxide donor, liver fibrosis

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Authors: Sharon Millen, Sarah Miller, Laura Dunne, Clare McGeady, Laura Neeson

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This paper presents the findings from a randomised controlled trial (RCT) and process evaluation of the Lifestart parenting programme. Lifestart is a structured child-centred programme of information and practical activity for parents of children aged from birth to five years of age. It is delivered to parents in their own homes by trained, paid family visitors and it is offered to parents regardless of their social, economic or other circumstances. The RCT evaluated the effectiveness of the programme and the process evaluation documented programme delivery and included a qualitative exploration of parent and child outcomes. 424 parents and children participated in the RCT: 216 in the intervention group and 208 in the control group across the island of Ireland. Parent outcomes included: parental knowledge of child development, parental efficacy, stress, social support, parenting skills and embeddedness in the community. Child outcomes included cognitive, language and motor development and social-emotional and behavioural development. Both groups were tested at baseline (when children were less than 1 year old), mid-point (aged 3) and at post-test (aged 5). Data were collected during a home visit, which took two hours. The process evaluation consisted of interviews with parents (n=16 at baseline and end-point), and focus groups with Lifestart Coordinators (n=9) and Family Visitors (n=24). Quantitative findings from the RCT indicated that, compared to the control group, parents who received the Lifestart programme reported reduced parenting-related stress, increased knowledge of their child’s development, and improved confidence in their parenting role. These changes were statistically significant and consistent with the hypothesised pathway of change depicted in the logic model. There was no evidence of any change in parents’ embeddedness in the community. Although four of the five child outcomes showed small positive change for children who took part in the programme, these were not statistically significant and there is no evidence that the programme improves child cognitive and non-cognitive skills by immediate post-test. The qualitative process evaluation highlighted important challenges related to conducting trials of this magnitude and design in the general population. Parents reported that a key incentive to take part in study was receiving feedback from the developmental assessment, which formed part of the data collection. This highlights the potential importance of appropriate incentives in relation to recruitment and retention of participants. The interviews with intervention parents indicated that one of the first changes they experienced as a result of the Lifestart programme was increased knowledge and confidence in their parenting ability. The outcomes and pathways perceived by parents and described in the interviews are also consistent with the findings of the RCT and the theory of change underpinning the programme. This hypothesises that improvement in parental outcomes, arising as a consequence of the programme, mediate the change in child outcomes. Parents receiving the Lifestart programme reported great satisfaction with and commitment to the programme, with the role of the Family Visitor being identified as one of the key components of the programme.

Keywords: parent-child relationship, parental self-efficacy, parental stress, school readiness

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Authors: Thumesha Jayatilake

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As platform work continues to proliferate, algorithmic management, which takes care of its operational role, poses complex challenges, including job satisfaction, worker involvement, ethical decision-making, and worker well-being. This conceptual paper scrutinizes how algorithmic management influences virtue development among platform workers, with an emphasis on the effects of role conflict and role ambiguity. Using an interdisciplinary approach, the research elucidates the complex relationship between algorithmic management systems and the ethical dimensions of work. The study also incorporates the interplay of human interaction and short-term task orientation, thus broadening the understanding of the impacts of algorithmic management on virtue development. The findings have significant implications for policymakers, academics, and industry practitioners, illuminating the ethical complexities presented by the use of algorithms in modern employment settings.

Keywords: algorithmic management, ethics, platform work, virtue

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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: Jamil Ahmed

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Access control models aim to decide whether a user should be denied or granted access to the user‟s requested activity. Various access control models have been established and proposed. The most prominent of these models include role-based, attribute-based, policy based access control models as well as role-centric attribute based access control model. In this paper, a novel access control model is presented called “Role centric Attribute based Policy Driven Access Control (RAPDAC) model”. RAPDAC incorporates the concept of “policy” in the “role centric attribute based access control model”. It leverages the concept of "policy‟ by precisely combining the evaluation of conditions, attributes, permissions and roles in order to allow authorization access. This approach allows capturing the "access control policy‟ of a real time application in a well defined manner. RAPDAC model allows making access decision at much finer granularity as illustrated by the case study of a real time library information system.

Keywords: authorization, access control model, role based access control, attribute based access control

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Authors: P. Selva, B. Lorraina, J. Alexis, A. Seror, A. Longuet, C. Mary, F. Denard

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Over the past four decades, the fatigue behavior of nickel-based alloys has been widely studied. However, in recent years, significant advances in the fabrication process leading to grain size reduction have been made in order to improve fatigue properties of aircraft turbine discs. Indeed, a change in particle size affects the initiation mode of fatigue cracks as well as the fatigue life of the material. The present study aims to investigate the fatigue behavior of a newly developed nickel-based superalloy under biaxial-planar loading. Low Cycle Fatigue (LCF) tests are performed at different stress ratios so as to study the influence of the multiaxial stress state on the fatigue life of the material. Full-field displacement and strain measurements as well as crack initiation detection are obtained using Digital Image Correlation (DIC) techniques. The aim of this presentation is first to provide an in-depth description of both the experimental set-up and protocol: the multiaxial testing machine, the specific design of the cruciform specimen and performances of the DIC code are introduced. Second, results for sixteen specimens related to different load ratios are presented. Crack detection, strain amplitude and number of cycles to crack initiation vs. triaxial stress ratio for each loading case are given. Third, from fractographic investigations by scanning electron microscopy it is found that the mechanism of fatigue crack initiation does not depend on the triaxial stress ratio and that most fatigue cracks initiate from subsurface carbides.

Keywords: cruciform specimen, multiaxial fatigue, nickel-based superalloy

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Authors: Hashem M. Alargha, Mohammad O. Hamdan, Waseem H. Aziz

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Aerobatic and military pilots are subjected to high gravitational forces that could cause blackout, physical injuries or death. A CFD simulation using fluid-solid interactions scheme has been conducted to investigate the gravitational effects and hazards inside cerebral aneurysms. Medical data have been used to derive the size and geometry of a simple aneurysm on a T-shaped bifurcation. The results show that gravitational force has no effect on maximum Wall Shear Stress (WSS); hence, it will not cause aneurysm initiation/formation. However, gravitational force cause causes hypertension which could contribute to aneurysm rupture.

Keywords: aneurysm, cfd, wall shear stress, gravity, fluid dynamics, bifurcation artery

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Authors: Gourav Jain, Sameer Dixit, Surjeet Kumar Arya, Praveen C. Verma

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Plant cell wall plays a major role in defence mechanism against biotic and abiotic stress as it constitutes the physical barrier between the microenvironment and internal component of the cell. It is a complex structure composed of mostly carbohydrates among which cellulose and hemicelluloses are most abundant that is embedded in a matrix of pectins and proteins. Multiple enzymes have been reported which plays a vital role in cell wall modification, Pectin Methylesterase (PME) is one of them which catalyses the demethylesterification of homogalacturonans component of pectin which releases acidic pectin and methanol. As emitted methanol is toxic to the insect pest, we use PME gene for the better methanol production. In the current study we showed overexpression of PME gene isolated from Withania somnifera under the insect inducible promoter causes enhancement of methanol production at the time of insect feeds to plants, and that provides better insect resistance property. We found that the 85-90% mortality causes by transgenic tobacco in both chewing (Spodoptera litura larvae and Helicoverpa armigera) and sap-sucking (Aphid, mealybug, and whitefly) pest. The methanol content and emission level were also enhanced by 10-15 folds at different inducible time point interval (15min, 30min, 45min, 60min) which would be analysed by Purpald/Alcohol Oxidase method.

Keywords: methanol, Pectin methylesterase, inducible promoters, Purpald/Alcohol oxidase

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Authors: Julianne Macmullen

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Due to advances in technology and early detection and treatment of cancer, many cancer patients are surviving longer than five years post-diagnosis. Most cancer patients suffer from depression, anxiety, and post-traumatic stress disorder (PTSD) at some point during diagnosis, treatment, and survivorship. A subgroup of patients will continue to suffer from depression and PTSD and require early intervention. Support groups provide patients with the emotional and informational support they require while also giving survivors a sense of community, friendship, and purpose. This type of support is recognized by researchers to improve the quality of life while also decreasing depression and PTSD symptoms. The gaps in the literature include cultural diversity, minorities, and support groups involving cancer types other than breast cancer. Another gap in the literature includes the perceptions of cancer patients as well as longitudinal studies to determine the relationships between support groups and decreased depression and PTSD rates over time. Future research is required to fill the gaps in the literature mentioned previously. Future research is also needed to analyze the difference in age groups and different types of support groups such as professionally-led, peer-led, and online. Implications for practice involve providers assessing for the symptoms of depression and PTSD in order to offer prompt treatment and support services to those patients. In conclusion, social support by way of support groups improves the quality of life, gives survivors a sense of purpose to help others while also gaining the support they need, and reduces the rate of depressive episodes related to PTSD.

Keywords: cancer survivor, survivorship, post-traumatic stress disorder (PTSD), depression, support groups

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Authors: Regina A. Tayong, Reza Barati

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A stable, fast and robust three-phase, 2D IMPES simulator has been developed for assessing the influence of; breaker concentration on yield stress of filter cake and broken gel viscosity, varying polymer concentration/yield stress along the fracture face, fracture conductivity, fracture length, capillary pressure changes and formation damage on fracturing fluid cleanup in tight gas reservoirs. This model has been validated as against field data reported in the literature for the same reservoir. A 2-D, two-phase (gas/water) fracture propagation model is used to model our invasion zone and create the initial conditions for our clean-up model by distributing 200 bbls of water around the fracture. A 2-D, three-phase IMPES simulator, incorporating a yield-power-law-rheology has been developed in MATLAB to characterize fluid flow through a hydraulically fractured grid. The variation in polymer concentration along the fracture is computed from a material balance equation relating the initial polymer concentration to total volume of injected fluid and fracture volume. All governing equations and the methods employed have been adequately reported to permit easy replication of results. The effect of increasing capillary pressure in the formation simulated in this study resulted in a 10.4% decrease in cumulative production after 100 days of fluid recovery. Increasing the breaker concentration from 5-15 gal/Mgal on the yield stress and fluid viscosity of a 200 lb/Mgal guar fluid resulted in a 10.83% increase in cumulative gas production. For tight gas formations (k=0.05 md), fluid recovery increases with increasing shut-in time, increasing fracture conductivity and fracture length, irrespective of the yield stress of the fracturing fluid. Mechanical induced formation damage combined with hydraulic damage tends to be the most significant. Several correlations have been developed relating pressure distribution and polymer concentration to distance along the fracture face and average polymer concentration variation with injection time. The gradient in yield stress distribution along the fracture face becomes steeper with increasing polymer concentration. The rate at which the yield stress (τ_o) is increasing is found to be proportional to the square of the volume of fluid lost to the formation. Finally, an improvement on previous results was achieved through simulating yield stress variation along the fracture face rather than assuming constant values because fluid loss to the formation and the polymer concentration distribution along the fracture face decreases as we move away from the injection well. The novelty of this three-phase flow model lies in its ability to (i) Simulate yield stress variation with fluid loss volume along the fracture face for different initial guar concentrations. (ii) Simulate increasing breaker activity on yield stress and broken gel viscosity and the effect of (i) and (ii) on cumulative gas production within reasonable computational time.

Keywords: formation damage, hydraulic fracturing, polymer cleanup, multiphase flow numerical simulation

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Authors: M. Szechynska-Hebda, M. Sobczak, E. Rozanska, J. Troczynska, Z. Banaszak, N. Hordyńska, M. Dyda, M. Wedzony

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Chloroplasts, as essential organelles for photosynthesis, play a critical role in plant development. However, disturbances in the proper functioning of chloroplasts, in the extreme case manifesting as albinism of tissues and whole plants, are a phenomenon often occurring in conditions deviating from natural (e.g., in vitro cultures applied in breeding programs). Using whole-transcriptome analysis (RNA-Seq) together with light, fluorescent and electron microscopy, it was shown, that development of chloroplasts and formation of green or albino plants in the androgenesis process are genotype-dependent; however, they could be modulated by sub-optimal temperature treatment. The reprogramming of the microspore development from gametophytic to sporophytic, and then regeneration of green plant can be positively regulated by cold stress (4 ⁰C). A high temperature stress (32 ⁰C) can induce androgenesis, but it is a factor negatively influencing green plant regeneration (promoting albinism). A similar effect on microspores, androgenesis, and subsequent chloroplast formation, is elicited as a result of postponing the date of spike collection from spring to summer in field conditions (natural temperature rise). It is determined in both environmental or genotypic manner. The delay of the sowing date (environmental effect) or growing of late genotypes (genotypic effect) result in spike maturation at higher temperatures and significantly enhance albino plant formation in androgenesis process. Such a temperature system (4 ⁰C vs. 32 ⁰C) was used to study the chloroplast biogenesis process in wheat and triticale. It was shown, that efficiency of physiological processes differentiates microspore development during cold reprograming in genotypes susceptible and resistant to androgenesis. Moreover, a great variation in developmental stages of the microspores in one anther is observed for susceptible genotypes. Microspores that are more physiologically active under cold conditions can activate signaling pathways and processes, which provide an appropriate supply of metabolites to cell compartments. This, in turn, fully correlates with the genotype-dependent efficiency of chloroplast formation (or different types of plastid) at particular steps of androgenesis. The effect obtained after applying a high temperature stress is different. High temperature causes a significant acceleration of microspore development and less variation in developmental stages at the end of the treatment. Therefore, the developmental diversity of the microspores in one anther seems to be a critical factor for subsequent cell and chloroplast differentiation. The work was financed by Ministry of Agriculture and Rural Development within Program: 'Biological Progress in Plant Production', project no HOR.hn.802.15.2018

Keywords: androgenesis, chloroplast biogenesis, temperature stress, wheat

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Authors: Ibrahim Ellithy, Mauricio Esguerra, , Rewanth Radhakrishnan

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In this study, the effects of hydrostatic stress on the magnetic properties of MnZn ferrite rings of different power grades, were measured and analyzed in terms of the magneto-mechanical effect on core losses was modeled via the Hodgdon-Esguerra hysteresis model. The results show excellent agreement with the model and a correlation between the permeability drop and the core loss increase in dependence of the material grade properties. These results emphasize the vulnerabilities of MnZn ferrites when subjected to mechanical perturbations, especially in real-world scenarios like under-road embedding for WPT.

Keywords: hydrostatic stress, power ferrites, core losses, wireless power transfer

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Authors: Hassan Shahmiri Barzoki

Abstract:

Background: Posttraumatic stress disorder (PTSD) is an abnormal physiologic and psychological reaction in person with severe traumatic history. In recent studies, the relationship between PTSD and some other disease apparently unrelated to psychological situations, such as cardiovascular diseases, diabetes, and metabolic syndrome, has been revealed. Thus, the aim of this study was to survey the prevalence of metabolic syndrome and mental health in PTSD patients. Methods: The research design was retrospective cohort study. Subjects were consisted of 142 Iran-Iraq war veterans with PTSD (age: 40-60 years), and the control group was consisted of 153 veterans without PTSD. Data was collected using questionnaires, physical exams and laboratory tests. Results: Prevalence of metabolic syndrome was 45.1%in PTSD group and 17% in control group. In addition, blood pressure, triglyceride and fasting blood sugar in PTSD group were significantly higher than control group (p<0.05). Also, PTSD patients had significant high rates of psychiatric disorders. Conclusion: PTSD patients are more prone to metabolic syndrome and psychiatric disorders than control group.

Keywords: mental health, metabolic syndrome, post traumatic stress disorder, patient

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Authors: Fariba Azizi, Firoozeh Haghighi, Viliam Makis

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In this paper, we propose a method to model the relationship between failure time and degradation for a simple step stress test where underlying degradation path is linear and different causes of failure are possible. It is assumed that the intensity function depends only on the degradation value. No assumptions are made about the distribution of the failure times. A simple step-stress test is used to shorten failure time of products and a tampered failure rate (TFR) model is proposed to describe the effect of the changing stress on the intensities. We assume that some of the products that fail during the test have a cause of failure that is only known to belong to a certain subset of all possible failures. This case is known as masking. In the presence of masking, the maximum likelihood estimates (MLEs) of the model parameters are obtained through an expectation-maximization (EM) algorithm by treating the causes of failure as missing values. The effect of incomplete information on the estimation of parameters is studied through a Monte-Carlo simulation. Finally, a real example is analyzed to illustrate the application of the proposed methods.

Keywords: cause of failure, linear degradation path, reliability function, expectation-maximization algorithm, intensity, masked data

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

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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: Vaibhav Baliyan, S. S. Parihar

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With the rise in temperature during reproductive phase and moisture stress, winter wheat yields are likely to decrease because of limited plant growth, higher rate of night respiration, higher spikelet sterility or number of grains per spike and restricted embryo development thereby reducing grain number. Crop management practices play a pivotal role in minimizing adverse effects of terminal heat stress on wheat production. Amongst various agronomic management practices, adjusting sowing date, crop cultivars and irrigation scheduling have been realized to be simple yet powerful, implementable and eco-friendly mitigation strategies to sustain yields under elevated temperature conditions. Taking into account, large variability in wheat production in space and time, a study was conducted to identify the suitable wheat varieties under both early and late planting with suitable irrigation schedule for minimizing terminal heat stress effect and thereby improving wheat production. Experiments were conducted at research farms of Indian Agricultural Research Institute, New Delhi, India, separately for timely and late sown conditions with suitable varieties with staggering dates of sowing from 1st November to 30th November in case of timely sown and from 1st December to 31st December for late sown condition. The irrigation schedule followed for both the experiments were 100% of ETc (evapotranspiration of crop), 80% of ETc and 60% of ETc. Results of the timely sown experiment indicated that 1st November sowing resulted in higher grain yield followed by 10th November. However, delay in sowing thereafter resulted in gradual decrease in yield and the maximum reduction was noticed under 30th November sowing. Amongst the varieties, HD3086 produced higher grain yield compared to other varieties. Irrigation applied based on 100% of ETc gave higher yield comparable to 80% of ETc but both were significantly higher than 60% of ETc. It was further observed that even liberal irrigation under 100% of ETc could not compensate the yield under delayed sowing suggesting that rise in temperature beyond January adversely affected the growth and development of crop as well as forced maturity resulting in significant reduction of yield attributing characters due to terminal heat stress. Similar observations were recorded under late sown experiment too. Planting on 1st December along with 100% ETc of irrigation schedule resulted in significantly higher grain yield as compared to other dates and irrigation regimes. Further, it was observed that reduction in yield under late sown conditions was significantly large than the timely sown conditions irrespective of the variety grown and irrigation schedule followed. Delayed sowing resulted in reducing crop growth period and forced maturity in turn led to significant deterioration in all the yield attributing characters and there by reduction in yield suggesting that terminal heat stress had greater impact on yield under late sown crop than timely sown due to temperature rise coinciding with reproductive phase of the crop.

Keywords: climate, irrigation, mitigation, wheat

Procedia PDF Downloads 116