Search results for " STRESS"
showing 10 items of 3936 documents
Factor analysis of the Spanish Burnout Inventory among public administration employees
2014
Burnout has been recognized as an important stress-related problem. Researchers have been troubled by some of the psychometric limitations of the questionnaires developed to evaluate burnout. This study was designed to assess the factor structure of the Spanish Burnout Inventory in a sample of 548 Brazilian public administration employees. This instrument comprises 20 items distributed in four dimensions: enthusiasm toward the job (5 items), psychological exhaustion (4 items), indolence (6 items), and guilt (5 items). The factor structure was examined through confirmatory factor analysis. To assess the factorial validity of the Spanish Burnout Inventory, four alternative models were tested.…
Adolescent coping with everyday stressors: A seven-nation study of youth from central, eastern, southern, and northern Europe
2007
The present study compares problem-specific coping strategies and coping styles of European adolescents from seven nations. The sample consisted of 3031 adolescent participants, aged 11 to 20, from Croatia, the Czech Republic, Germany, Italy, Norway, Portugal, and Switzerland. The adolescents completed the Coping Across Situations Questionnaire (CASQ) by indicating which coping strategies (from 20 alternatives) they usually employed in dealing with age-specific problems (covering 8 different domains). The strategies can be collapsed to three coping styles: active coping, internal coping, and withdrawal. Results show that adolescents from all seven nations predominantly employed functional f…
Peroxynitrite generated from constitutive nitric oxide synthase mediates the early biochemical injury in short-term cultured hepatocytes
2000
AbstractEarly loss of P450 in rat hepatocyte cultures appears directly related to nitric oxide (NO) overproduction. This study provides experimental evidence for the induction – shortly after isolation through the classical procedure – of strong oxidative stress that involves both oxygen-derived and NO-derived species. NO formation at this stage is due to the early activation of liver constitutive NO synthase (cNOS). Immunodetection of nitrated proteins provides direct evidence of endogenous peroxynitrite (PN) formation upon hepatocyte isolation. On the basis of the combined use of dihydrorhodamine 123 and NOS inhibitors, the analysis of the amount, time course and nature of the species inv…
Three-dimensional numerical simulations on wind- and tide-induced currents: The case of Augusta Harbour (Italy)
2014
The hydrodynamic circulation in the coastal area of the Augusta Bay (Italy), located in the eastern part of Sicily, is analysed. Due to the heavy contamination generated by the several chemical and petrochemical industries active in the zone, the harbour was declared a Contaminated Site of National Interest. To mitigate the risks connected with the industrial activities located near the harbour, it is important to analyse the hydrodynamic circulation in the coastal area. To perform such analysis, a parallel 3D numerical model is used to solve the Reynolds-averaged momentum and mass balance, employing the k-e turbulence model for the Reynolds stresses. The numerical model is parallelized usi…
Analisi numerico-sperimentale per la determinazione delle tensioni residue in un giunto saldato
2013
La durata di un componente dipende dall’interazione tra le caratteristiche meccaniche del materiale con cui è costruito e gli sforzi a cui esso è sottoposto. Per la determinazione dello stato tensionale agente, oltre agli sforzi dovuti ai carichi imposti durante l’esercizio, è necessario conoscere accuratamente gli stati tensionali residui derivanti dal processo di produzione. Generalmente, le tensioni residue sono indesiderate poiché possono essere di entità elevata e tale da ridurre la resistenza complessiva del componente meccanico. Un aspetto particolarmente insidioso delle tensioni residue è che la loro presenza viene generalmente riconosciuta solo dopo il verificarsi di un malfunziona…
Residual Stresses Induced by Cold Expansion of Adjacent and Cut-Out Holes
2012
Fatigue life of fastener holes can be enhanced via a cold-expansion process to introduce a compressive residual stress field around the hole edge and to reduce crack growth propagation. Considering that aerospace components contain multiple rows of holes, the present investigation focuses on the evaluation of the three-dimensional residual stress distribution in adjacent cold-expanded (CE) holes. The redistribution of residual stresses caused by a cut introduced between two adjacent holes was also investigated. Finite element (FE) analysis and experimental technique were used to assess the residual stress distribution in a 6082-T6 aluminum plate with two adjacent holes expanded sequentially…
The Proteome and Lipidome of Synechocystis sp. PCC 6803 Cells Grown under Light-Activated Heterotrophic Conditions*
2015
Cyanobacteria are photoautotrophic prokaryotes with a plant-like photosynthetic machinery. Because of their short generation times, the ease of their genetic manipulation, and the limited size of their genome and proteome, cyanobacteria are popular model organisms for photosynthetic research. Although the principal mechanisms of photosynthesis are well-known, much less is known about the biogenesis of the thylakoid membrane, hosting the components of the photosynthetic, and respiratory electron transport chain in cyanobacteria. Here we present a detailed proteome analysis of the important model and host organism Synechocystis sp. PCC 6803 under light-activated heterotrophic growth condition…
Biological Strategies of Lichen Symbionts to the Toxicity of Lead (Pb)
2019
Lichens are symbiotic organisms, originated by mutualistic associations of heterotrophic fungi (mycobiont), photosynthetic partners (photobionts) which can be either cyanobacteria (cyanobionts) or green microalgae (phycobionts), and bacterial consortia. They are poikilohydric organisms without cuticles or nutrient absorption organs adapted to anhydrobiosis. They present a large range of tolerance to abiotic stress (UV radiation, extreme temperatures, high salinity, mineral excess, etc.) and prosper all around the Earth, especially in harsh habitats, including Antarctica and warm deserts. Their biodiversity is widely used as a bioindicator of environmental quality due to this diversity of to…
Variational methods for the steady state response of elastic–plastic solids subjected to cyclic loads
2003
Abstract Solids (or structures) of elastic–plastic internal variable material models and subjected to cyclic loads are considered. A minimum net resistant power theorem, direct consequence of the classical maximum intrinsic dissipation theorem of plasticity theory, is envisioned which describes the material behavior by determining the plastic flow mechanism (if any) corresponding to a given stress/hardening state. A maximum principle is provided which characterizes the optimal initial stress/hardening state of a cyclically loaded structure as the one such that the plastic strain and kinematic internal variable increments produced over a cycle are kinematically admissible. A steady cycle min…
Statistical Properties of Generalized Strain Criterion for Multiaxial Random Fatigue
1989
ABSTRACT Statistical properties of generalized criterion of the maximum shear and normal strains on the fracture plane have been presented, Functions of probability distribution and spectral density of the equivalent strain have been analysed on the assumption that a random tensor of strain state is a six-dimensional stationary and ergodic Gaussian process. The expected value and variance of the equivalent strain have been determined as well. From spectral analysis a new limitation has been derived for extension of some multiaxial cyclic fatigue criteria to random loadings. It is connected with the fact that in some cases the frequency band of the equivalent strain is greater than that for …