WorldWideScience

Sample records for acute thermal stress

  1. Biogenic amines and acute thermal stress in the rat

    Science.gov (United States)

    Williams, B. A.; Moberg, G. P.

    1975-01-01

    A study is summarized which demonstrates that depletion of the biogenic amines 5-hydroxytryptamine (5-HT) or norepinephrine (NE) alters the normal thermoregulatory responses to acute temperature stress. Specifically, NE depletion caused a significant depression in equilibrium rectal temperature at 22 C and a greater depression in rectal temperature than controls in response to cold (6 C) stress; NE depletion also resulted in a significantly higher rectal temperature response to acute heat (38 C) stress. Depletion of 5-HT had less severe effects. It remains unclear whether the primary site of action of these agents is central or peripheral.

  2. Early Age Thermal Conditioning Improves Broiler Chick's Response to Acute Heat Stress at Marketing Age

    Directory of Open Access Journals (Sweden)

    Ahmed M. Hassan

    2012-01-01

    Full Text Available Problem statement: Acute heat stress at marketing age especially in broiler chickens raised in open houses with reduced means of heat exchange leads to economic losses. The objective of this study was to determine beneficial effects of early age thermal conditioning in reducing adverse effects of acute heat stress and decrease losses. Approach: Ninety one day-old broiler chicks were randomly assigned to one of three treatments (n = 30: (1 control (normally raised, (2 early age thermal conditioning (exposed to temperature of 40±1°C for 24 h at 5th day of age, then raised as control chicks and (3 chronic stress (exposed to 33±2°C from day one till 6 weeks of age. At 42nd day of age, all chicks were subjected to acute heat stress of 39±2°C for 2 h. Blood samples were collected from all groups before and after exposure to acute heat stress. Results: Blood pH increased in both controls and thermally-conditioned chicks after exposure to acute heat stress coinciding with significant decrease in blood carbon dioxide pressure (pCo2 in controls only. Blood potassium level decreased in controls, while in thermally-conditioned or chronically-stressed no significant changes were observed. Blood sodium level showed a trend toward decreased levels in controls while a trend toward increased levels was observed in both thermally-conditioned and chronically-stressed birds. Importantly, significant reductions were observed in total erythrocyte count and hemoglobin level in chronically-stressed birds as compared to other groups before and after acute stress exposure. Hetrophil/lymphocyte ratio increased in both controls and thermally-conditioned chicks after acute heat exposure, but not in chronically-stressed birds. Conclusion: When exposed to acute heat stress at marketing age, chicks subjected to early age thermal conditioning responded very similar to birds adapted to chronic heat stress indicating a protective role of early age thermal conditioning.

  3. Sensitivity of gypsy moth neurosecretory neurons to acute thermal stress

    Directory of Open Access Journals (Sweden)

    Ilijin Larisa

    2013-01-01

    Full Text Available In gypsy moth caterpillars exposed to a temperature of 35°C (for 1, 12 and 24 h and caterpillars that were exposed to elevated temperature for 12 h and were allowed to recover for 12 h at 23°C, changes in the brain protein profiles and morphometric characteristics of A1’ medial and L2 lateral protocerebral neurosecretory neurons were analyzed. In all groups, protein bands with a molecular mass corresponding to that of members of heat-shock protein families were detected, indicating that acute exposure to this temperature likely induced the synthesis of HSP. Increased morphometric parameters of A1’ neurons and the large amount of neurosecretory material in the neuron body implicate that the temperature of 35°C is not in the temperature range that exerts stimulatory effects on growth and survival. Changes in the morphometric characteristics of L2 neurosecretory neurons from the lateral part of the protocerebrum, and retention of neurosecretory material in their cytoplasm indicate a low level of secretion.

  4. Consequences of acclimation on the resistance to acute thermal stress: Proteomic focus on mussels from pristine site.

    Science.gov (United States)

    Péden, Romain; Rocher, Béatrice; Chan, Philippe; Vaudry, David; Poret, Agnès; Olivier, Stéphanie; Le Foll, Frank; Bultelle, Florence

    2016-10-01

    Climate change constitutes an additional threat for intertidal species that already have to cope with a challenging environment. The present study focuses on the blue mussel Mytilus edulis and aims at investigating the importance of thermal acclimation in heat stress response. Microcosm exposures were performed with mussels submitted to an identical acute thermal stress following two thermal summer acclimations standing for present or future temperature conditions. Gill proteomes were analyzed by 2DE and 96 differentially expressed proteoforms were identified. Our results show that cell integrity appears to be maintained by the rise in molecular protective systems (i.e. Heat Shock Proteins), and by the reallocation of energy production via a switch to anaerobic metabolism and the setting up of alternative energy pathways. Finally, our results indicate that the response of mussels to acute thermal stress is conditioned by the acclimation temperature with an improved response in organisms acclimated to higher temperatures.

  5. Consequences of acclimation on the resistance to acute thermal stress: Proteomic focus on mussels from pristine site.

    Science.gov (United States)

    Péden, Romain; Rocher, Béatrice; Chan, Philippe; Vaudry, David; Poret, Agnès; Olivier, Stéphanie; Le Foll, Frank; Bultelle, Florence

    2016-10-01

    Climate change constitutes an additional threat for intertidal species that already have to cope with a challenging environment. The present study focuses on the blue mussel Mytilus edulis and aims at investigating the importance of thermal acclimation in heat stress response. Microcosm exposures were performed with mussels submitted to an identical acute thermal stress following two thermal summer acclimations standing for present or future temperature conditions. Gill proteomes were analyzed by 2DE and 96 differentially expressed proteoforms were identified. Our results show that cell integrity appears to be maintained by the rise in molecular protective systems (i.e. Heat Shock Proteins), and by the reallocation of energy production via a switch to anaerobic metabolism and the setting up of alternative energy pathways. Finally, our results indicate that the response of mussels to acute thermal stress is conditioned by the acclimation temperature with an improved response in organisms acclimated to higher temperatures. PMID:26972988

  6. Self-supplementation and effects of dietary antioxidants during acute thermal stress.

    Science.gov (United States)

    Beaulieu, Michaël; Haas, Anabel; Schaefer, H Martin

    2014-02-01

    Thermal stress leads to increased production of reactive oxygen species. If an organism is not able to simultaneously mount an efficient antioxidant defense system, this may lead to increased oxidative damage, which is potentially deleterious in terms of health and fitness. Exposure to cold or heat is therefore expected to be associated with a high demand for antioxidants. In agreement, several studies have shown that supplementing the diet of thermally stressed organisms with antioxidants leads to a reduction of oxidative damage. However, whether organisms can actively supplement their diet with antioxidants to alleviate temperature-induced oxidative damage is unknown. Here, we show that captive Gouldian finches (Erythrura gouldiae) supplement their diet more with seeds rich in antioxidants below than within their thermoneutral zone. Moreover, having access to seeds rich in antioxidants at temperatures below thermoneutrality decreases their oxidative damage. These results indicate that, when facing a thermal challenge, animals are able to take advantage of the antioxidant properties of their food to improve their oxidative balance. Having access to food resources rich in antioxidants may therefore be of primary importance for organisms in their natural habitat, as it may help them to cope with oxidative constraints due to challenging temperature regimes.

  7. Acute heat stress and thermal acclimation induce CCAAT/enhancer-binding protein delta in the goby Gillichthys mirabilis.

    Science.gov (United States)

    Buckley, Bradley A

    2011-08-01

    Members of the CCAAT/enhancer-binding protein (C/EBP) family of transcription factors have regulatory control over numerous processes related to cell fate determination, including differentiation, proliferation, cell cycle arrest and apoptosis. In mammals, abnormalities in the expression of some isoforms of C/EBPs are pathogenic and are implicated as being involved in myeloid leukemia and breast cancers. Next to nothing is known about their regulation, function or stress-responsiveness in poikilotherms. Here, both acute heat stress and thermal acclimation were demonstrated to induce the expression of one isoform, C/EBP-δ, in the liver, white muscle and gill of the eurythermal estuarine goby, Gillichthys mirabilis. The established role of C/EBP-δ in causing cell cycle arrest and/or promoting apoptosis in other vertebrates suggests that the heat-inducibility of this protein in poikilotherms may be part of the conserved cellular stress response with the hypothesized role of causing temporary cessation of cell growth and/or programmed cell death during bouts of environmental stress. The observed regulation of c/ebp-δ during hyperthermia represents a novel, heat-inducible signaling pathway in fishes. PMID:21442321

  8. Thermal stresses in pipes

    OpenAIRE

    Al-Zaharnah, Iyad

    2002-01-01

    This study presents results about thermal stresses in externally heated pipes that are subjected to different flow types: laminar flow, turbulent flow, and pulsating flow. The effect o f flow Reynolds number on thermal stresses in the pipe is studied. To investigate the influence o f fluid and solid properties on the resulting thermal stresses in pipes, two solids namely; steel and cooper and three fluids namely; water, coolanol-25, and mercury are used in the study. Pipes with different diam...

  9. Risk Preferences under Acute Stress

    OpenAIRE

    Cingl, Lubomír; Cahlíková, Jana

    2013-01-01

    Many important decisions are made under stress and they often involve risky alternatives. There has been ample evidence that stress influences decision making in cognitive as well as in affective domains, but still very little is known about whether individual attitudes to risk change with exposure to acute stress. To directly evaluate the causal effect of stress on risk attitudes, we adopt an experimental approach in which we randomly expose participants to a psychosocial stressor in the for...

  10. Encyclopedia of thermal stresses

    CERN Document Server

    2014-01-01

    The Encyclopedia of Thermal Stresses is an important interdisciplinary reference work.  In addition to topics on thermal stresses, it contains entries on related topics, such as the theory of elasticity, heat conduction, thermodynamics, appropriate topics on applied mathematics, and topics on numerical methods. The Encyclopedia is aimed at undergraduate and graduate students, researchers and engineers. It brings together well established knowledge and recently received results. All entries were prepared  by leading experts from all over the world, and are presented in an easily accessible format. The work is lavishly illustrated, examples and applications are given where appropriate, ideas for further development abound, and the work will challenge many students and researchers to pursue new results of their own. This work can also serve as a one-stop resource for all who need succinct, concise, reliable and up to date information in short encyclopedic entries, while the extensive references will be of inte...

  11. Thermal Stresses in Welding

    DEFF Research Database (Denmark)

    Hansen, Jan Langkjær

    1998-01-01

    Studies of the transient temperature fields and the hereby induced deformations and stressses in a butt-welded mild steel plate modelledrespectively in 2D plane stress state (as well as plane strain state) and in full 3D have been done. The model has been implemented in the generalpurpose FE...

  12. Oxidative Stress Adaptation with Acute, Chronic and Repeated Stress

    OpenAIRE

    Pickering, Andrew. M.; Vojtovich, Lesya; Tower, John; Davies, Kelvin J. A.

    2012-01-01

    Oxidative stress adaptation or hormesis is an important mechanism by which cells and organisms respond to, and cope with, environmental and physiological shifts in the level of oxidative stress. Most studies of oxidative stress adaption have been limited to adaptation induced by acute stress. In contrast, many if not most environmental and physiological stresses are either repeated or chronic. In this study we find that both cultured mammalian cells, and the fruit fly Drosophila melanogaster,...

  13. Acute Cold / Restraint Stress in Castrated Rats

    Directory of Open Access Journals (Sweden)

    Farideh Zafari Zangeneh

    2008-09-01

    Full Text Available Objective: The present study aimed to determine whether castration altered osmotically stimulated vasopressin (VP release and urinary volume and what is the role of endocrine-stress axis in this process.Materials and methods: Totally 108 mice were studied in two main groups of castrated (n=78 and control (n=30. Each group was extracted by acute cold stress (4◦C for 2h/day, restraint stress (by syringes 60cc 2h/day and cold/restraint stress. The castrated group was treated in sub groups of testosterone, control (sesame oil as vehicle of testosterone. Propranolol as blocker of sympathetic nervous system was given to both groups of castrated mice and main control.Results: Our results showed that, there is interactions between testosterone and sympathetic nervous system on vasopressin, because urine volume was decreased only in testoctomized mice with cold/restraint and cold stress (P<0.001; propranolol as the antagonist of sympathetic nervous system could block and increase urine volume in castrated mice. This increased volume of urine was due to acute cold stress, not restraint stress (p<0.001. The role of testosterone, noradrenalin (NA and Vasopressin (VP in the acute cold stress is confirmed, because testosterone could return the effect of decreased urine volume in control group (P<0.001. Conclusion: Considering the effect of cold/restraint stress on urinary volume in castrated mice shows that there is interaction between sex hormone (testosterone, vasopressin and adrenergic systems.

  14. Thermal stress studies using optical holographic interferometry

    Science.gov (United States)

    Harris, W. J.; Woods, D. C.

    1974-01-01

    The application of holography to thermal stress studies is discussed. Interference fringes as produced by holograms and their interpretation are reviewed in relation to workpiece displacement. Three potential mechanisms are given to explain thermal displacement as detected by holographic methods. Results of some thermal stressing studies are reported, including tests on a live rocket motor.

  15. Contribution to encyclopedia of thermal stresses

    Science.gov (United States)

    Taler, Jan; Ocłoń, Pawel

    2015-06-01

    This paper lists the contribution in the international interdisciplinary reference - Encyclopedia of Thermal Stresses (ETS). The ETS, edited by the world famous expert in field of Thermal Stresses - Professor Richard Hetnarski from Rochester Institute of Technology, was published by Springer in 2014. This unique Encyclopedia, subdivided into 11 volumes is the most extensive and comprehensive work related to the Thermal Stresses topic. The entries were carefully prepared by specialists in the field of thermal stresses, elasticity, heat conduction, optimization among others. The Polish authors' contribution within this work is significant; over 70 entries were prepared by them.

  16. Acute Stress Response in Critically Ill Children

    NARCIS (Netherlands)

    M. den Brinker (Marieke)

    2006-01-01

    textabstractThe understanding of the endocrine changes in critically ill children is important, as it provides insights in the pathophysiology of the acute stress in children and its differences compared with adults. Furthermore, it delineates prognostic factors for survival and supports the rati

  17. Acute stress may induce ovulation in women

    Directory of Open Access Journals (Sweden)

    Cano Antonio

    2010-05-01

    Full Text Available Abstract Background This study aims to gather information either supporting or rejecting the hypothesis that acute stress may induce ovulation in women. The formulation of this hypothesis is based on 2 facts: 1 estrogen-primed postmenopausal or ovariectomized women display an adrenal-progesterone-induced ovulatory-like luteinizing hormone (LH surge in response to exogenous adrenocorticotropic hormone (ACTH administration; and 2 women display multiple follicular waves during an interovulatory interval, and likely during pregnancy and lactation. Thus, acute stress may induce ovulation in women displaying appropriate serum levels of estradiol and one or more follicles large enough to respond to a non-midcycle LH surge. Methods A literature search using the PubMed database was performed to identify articles up to January 2010 focusing mainly on women as well as on rats and rhesus monkeys as animal models of interaction between the hypothalamic-pituitary-adrenal (HPA and hypothalamic-pituitary-gonadal (HPG axes. Results Whereas the HPA axis exhibits positive responses in practically all phases of the ovarian cycle, acute-stress-induced release of LH is found under relatively high plasma levels of estradiol. However, there are studies suggesting that several types of acute stress may exert different effects on pituitary LH release and the steroid environment may modulate in a different way (inhibiting or stimulating the pattern of response of the HPG axis elicited by acute stressors. Conclusion Women may be induced to ovulate at any point of the menstrual cycle or even during periods of amenorrhea associated with pregnancy and lactation if exposed to an appropriate acute stressor under a right estradiol environment.

  18. Cancer, acute stress disorder, and repressive coping

    DEFF Research Database (Denmark)

    Pedersen, Anette Fischer; Zachariae, Robert

    2010-01-01

    The purpose of this study was to investigate the association between repressive coping style and Acute Stress Disorder (ASD) in a sample of cancer patients. A total of 112 cancer patients recently diagnosed with cancer participated in the study. ASD was assessed by the Stanford Acute Stress...... Reaction Questionnaire, and repressive coping was assessed by a combination of scores from the Marlowe-Crowne Social Desirability Scale, and the Bendig version of the Taylor Manifest Anxiety Scale. Significantly fewer patients classified as "repressors" were diagnosed with ASD compared to patients...... classified as "non-repressors". However, further investigations revealed that the lower incidence of ASD in repressors apparently was caused by a low score on anxiety and not by an interaction effect between anxiety and defensiveness. Future studies have to investigate whether different psychological...

  19. Dynamic residual stress in thermal sprayed coatings

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiping; Yang Yuanyuan

    2005-01-01

    With the modified Almen method, the forming and development process of residual stress in a thermal sprayed coating has been obtained. The test results identify that the residual stress in a coating is depend on coating material properties, technique and coating thickness. The paper pays much attention to the hysteresis between the coating temperature and residual stress in the coating or between the applied stress and the strain of the coating, and confirms that the fact is resulted from the"Gas Fix" character of a thermal sprayed coating.

  20. Thermal Stress Analysis of Security Injection Tank

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The purpose of the thermal stress analysis of the security injection tank is to make sure whether the tank can withstand the concerned thermal load or not on all the conditions conforming to the concerned code prescripts and the design requirements.

  1. THERMAL STRESS IN METEOROIDS BY AERODYNAMIC HEATING

    Institute of Scientific and Technical Information of China (English)

    Chi-Yu King

    2003-01-01

    Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heattransfer coefficient. Given enough time, the tensile stress in the interior of the meteoroid can be as high as 10 kb. This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter. Significant thermal stress(1 kb) can develop quickly within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large radius<l m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid's interior. Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes, the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters. In large meteoroids that require longer heating for thermal stress to fully develop,its effect is probably insignificant. The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.

  2. THERMAL STRESS IN METEOROIDS BY AERODYNAMIC HEATING

    Institute of Scientific and Technical Information of China (English)

    Chi-YuKing

    2003-01-01

    Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heattransfer coefficient. Given enough time,the tensile stress in the interior of the meteoroid can be as high as 10 kb. This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter. Significant thermal stress(1 kb) can develop quickly (within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large(radius<l m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid's interior. Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes, the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters. In large meteoroids that require longer heating for thermal stress to fully develop, its effect is probably insignificant. The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.

  3. Thermal Residual Stresses in Multilayered Coatings

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Binshi XU; Haidou WANG; Yixiong WU

    2005-01-01

    The mechanical integrity and reliability of coated devices are strongly affected by the residual stresses in thin films and coatings. However, due to the metallurgical complexity of materials, it is rather difficult to obtain a closed-form solution of residual stresses within multilayered coatings (e.g. functionally graded coatings, FGCs). In this paper,an analytical model is developed to predict the distribution of residual stresses within multilayered coatings. The advantage of this model is that the solution of residual stresses is independent of the number of layers. Specific results are obtained by calculating elastic thermal stresses in ZrO2/NiCoCrAIY FGCs, which consist of different material layers. Furthermore, the residual stress distribution near the edges and the stress-induced failure modes of coating are also analyzed. The topics discussed provide some insights into the development of a methodology for designing fail-safe coating systems.

  4. Thermal and stress analysis of control rod

    International Nuclear Information System (INIS)

    In order to survey the mechanical integrity of a control rod in the high temperature core of the VHTR, thermal analysis and thermal stress analysis were carried out by means of calculus of finite differentials and finite element methods for the plant under the normal operating condition as well as under several abnormal conditions. The results of the analyses have been applied to refine the mechanical design of the control rod

  5. Thermal Stress Relaxation of Nonhomogeneous Coatings

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Nonhomogeneous coatings (NCs) are new type of engineering structures that is not yet fully understood. One important aspect in the mechanical analysis of NCs is to determine the gradient distribution that creates the maximum thermal stress relaxation. This paper employs numerical analysis using the finite element metho d and experimental analysis using moire interference to study the stress distrib ution in NCs. Attention focused on the edge effect stresses in the coating/subst rate structures and their dependence on the different gradient distributions of this new kind of composite structure.

  6. Stress kinase inhibition modulates acute experimental pancreatitis

    Institute of Scientific and Technical Information of China (English)

    F. Fleischer; R. Dabew; B. Goke; ACC Wagner

    2001-01-01

    AIM To examine the role of p38 during acute experimental cerulein pancreatitis.METHODS Rats were treated with cerulein with or without a specific JNK inhibitor (CEP1347)andy or a specific p38 inhbitor (SB203380) and pancreatic stress kinase activity wasdetermined. Parameters to assess pancreatitis included trypsin, amylase, lipase, pancreatic weight and histology.RESULTS JNK inhibition with CEP1347ameliorated pancreatitis, reducing pancreatic edema. In contrast, p38 inhibition with SB203580aggravated pancreatitis with higher trypsinlevels and, with induction of acinar necrosis not normally found after cerulein hyperstimulation.Simultaneous treatment with both CEP1347 and SB203580 mutually abolished the effects of either compound on cerulein pancreatitis.CONCLUSION Stress kinases modulatepancreatitis differentially. JNK seems to promote pancreatitis development, possibly by supporting inflammatory reactions such as edema formation while its inhibition ameliorates pancreatitis. In contrast, p38 may help reduce organ destruction while inhibition of p38 during induction of cerulein pancreatitis leads to the occurrence of acinar necrosis.

  7. Thermal analysis of thermoelectric power generator; Including thermal stresses

    Science.gov (United States)

    Al-Merbati, Abdulrahman Salman

    In recent years, the energy demand is increasing leads to use and utilization of clean energy becomes target of countries all over the world. Thermoelectric generator is one type of clean energy generators which is a solid-state device that converts heat energy into electrical energy through the Seebeck effect. With availability of, heat from different sources such as solar energy and waste energy from systems, thermoelectric research becomes important research topic and researchers investigates efficient means of generating electricity from thermoelectric generators. One of the important problems with a thermoelectric is development of high thermal stresses due to formation of temperature gradient across the thermoelectric generator. High thermal stress causes device failure through cracks or fractures and these short comings may reduce the efficiency or totally fail the device. In this thesis work, thermodynamic efficiency and thermal stresses developed in thermoelectric generator are analyzed numerically. The bismuth telluride (Bi2Te3) properties are used in simulation. Stress levels in thermoelectric device pins are computed for various pin geometric configurations. MASTER.

  8. Thermal stress depletes energy reserves in Drosophila.

    Science.gov (United States)

    Klepsatel, Peter; Gáliková, Martina; Xu, Yanjun; Kühnlein, Ronald P

    2016-01-01

    Understanding how environmental temperature affects metabolic and physiological functions is of crucial importance to assess the impacts of climate change on organisms. Here, we used different laboratory strains and a wild-caught population of the fruit fly Drosophila melanogaster to examine the effect of temperature on the body energy reserves of an ectothermic organism. We found that permanent ambient temperature elevation or transient thermal stress causes significant depletion of body fat stores. Surprisingly, transient thermal stress induces a lasting "memory effect" on body fat storage, which also reduces survivorship of the flies upon food deprivation later after stress exposure. Functional analyses revealed that an intact heat-shock response is essential to protect flies from temperature-dependent body fat decline. Moreover, we found that the temperature-dependent body fat reduction is caused at least in part by apoptosis of fat body cells, which might irreversibly compromise the fat storage capacity of the flies. Altogether, our results provide evidence that thermal stress has a significant negative impact on organismal energy reserves, which in turn might affect individual fitness. PMID:27641694

  9. Thermal stress depletes energy reserves in Drosophila

    Science.gov (United States)

    Klepsatel, Peter; Gáliková, Martina; Xu, Yanjun; Kühnlein, Ronald P.

    2016-01-01

    Understanding how environmental temperature affects metabolic and physiological functions is of crucial importance to assess the impacts of climate change on organisms. Here, we used different laboratory strains and a wild-caught population of the fruit fly Drosophila melanogaster to examine the effect of temperature on the body energy reserves of an ectothermic organism. We found that permanent ambient temperature elevation or transient thermal stress causes significant depletion of body fat stores. Surprisingly, transient thermal stress induces a lasting “memory effect” on body fat storage, which also reduces survivorship of the flies upon food deprivation later after stress exposure. Functional analyses revealed that an intact heat-shock response is essential to protect flies from temperature-dependent body fat decline. Moreover, we found that the temperature-dependent body fat reduction is caused at least in part by apoptosis of fat body cells, which might irreversibly compromise the fat storage capacity of the flies. Altogether, our results provide evidence that thermal stress has a significant negative impact on organismal energy reserves, which in turn might affect individual fitness. PMID:27641694

  10. The role of inflammatory stress in acute coronary syndrome

    Institute of Scientific and Technical Information of China (English)

    沈成兴; 陈灏珠; 葛均波

    2004-01-01

    Objective To summarize current understanding of the roles of anti-inflammatory and proinflammatory mechanisms in the development of atherosclerosis and acute coronary syndrome and to postulate the novel concept of inflammation stress as the most important factor triggering acute coronary syndrome. Moreover, markers of inflammation stress and ways to block involved pathways are elucidated.Data sources A literature search (MEDLINE 1997 to 2002) was performed using the key words "inflammation and cardiovascular disease". Relevant book chapters were also reviewed.Study selection Well-controlled, prospective landmark studies and review articles on inflammation and acute coronary syndrome were selected.Data extraction Data and conclusions from the selected articles providing solid evidence to elucidate the mechanisms of inflammation and acute coronary syndrome were extracted and interpreted in the light of our own clinical and basic research.Data synthesis Inflammation is closely linked to atherosclerosis and acute coronary syndrome. Chronic and long-lasting inflammation stress, present both systemically or in the vascular walls, can trigger acute coronary syndrome.Conclusions Inflammation stress plays an important role in the process of acute coronary syndrome. Drugs which can modulate the balance of pro- and anti-inflammatory processes and attenuate inflammation stress, such as angiotensin-converting enzyme (ACE) inhibitors/angiotensin Ⅱ receptor blockers, statins, and cytokine antagonists may play active roles in the prevention and treatment of acute coronary syndrome when used in addition to conventional therapies (glycoprotein Ⅱb/Ⅲa receptor antagonists, mechanical intervention strategies, etc).

  11. 40 CFR 90.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 90.329... Equipment Provisions § 90.329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for thermally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000...

  12. 40 CFR 91.427 - Catalyst thermal stress resistance evaluation.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress resistance... Procedures § 91.427 Catalyst thermal stress resistance evaluation. (a)(1) The purpose of the evaluation procedure specified in this section is to determine the effect of thermal stress on catalyst...

  13. 40 CFR 90.427 - Catalyst thermal stress resistance evaluation.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress resistance... Gaseous Exhaust Test Procedures § 90.427 Catalyst thermal stress resistance evaluation. (a) The purpose of... catalyst conversion efficiency for Phase 1 engines. The thermal stress is imposed on the test catalyst...

  14. Coral thermal tolerance: tuning gene expression to resist thermal stress.

    Directory of Open Access Journals (Sweden)

    Anthony J Bellantuono

    Full Text Available The acclimatization capacity of corals is a critical consideration in the persistence of coral reefs under stresses imposed by global climate change. The stress history of corals plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub-lethal temperature of 3°C below bleaching threshold temperature were compared to both non-preconditioned corals and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned corals from non-preconditioned corals, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned corals and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned corals. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with coral thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs

  15. The Effects of Acute Stress on Rainbow Trout (Oncorhynchus mykiss)

    OpenAIRE

    KUBİLAY, Ayşegül

    2002-01-01

    The physiological effects of acute stressors (transport, handling, netting and confinement) on rainbow trout in an aquaculture system were investigated. Serum cortisol level, serum glucose and lysozyme activity were determined in rainbow trout stressed by acute stressors, and compared with those of unstressed (control) fish. Serum cortisol, glucose levels and lysozyme activity were significantly higher(P

  16. Estimation of Subjective Stress in Acute Myocardial Infarction

    Directory of Open Access Journals (Sweden)

    Chockalingam A

    2003-01-01

    Full Text Available BACKGROUND and AIMS: Mental stress is considered to be a precipitating factor in acute coronary events. We aimed to assess the association of subjective or 'perceived' mental stress with the occurrence of acute coronary events. SETTINGS AND DESIGN: Prospective case-control survey was carried out in a referral teaching hospital. subjects & METHODS: Consecutive patients with acute myocardial infarction and ST elevation on electrocardiogram who were admitted to the Coronary Care Unit of a referral teaching hospital were enrolled in the study as cases. Controls were unmatched and were enrolled from amongst patients with coronary artery disease who did not have recent acute coronary events. Subjective Stress Functional Classification (SS-FC for the preceding 2-4 weeks was assessed and assigned four grades from I to IV as follows: I - baseline, II - more than usual but not affecting daily routine, III - significantly high stress affecting daily routine and IV - worst stress in life. STATISTICAL ANALYSIS: Proportions of different characteristics were compared using chi-square test with Yates continuity correction. Student's unpaired t test was applied for mean age. 'p' value of < 0.05 was considered statistically significant. RESULTS: SS-FC could be reliably (99% and easily assessed. Eighty (53% of the total 150 patients with acute MI reported 'high' levels of stress (stress class III and IV. This is in contrast to only 30 (20% of 150 healthy controls reporting high stress for the same period (p value < 0.001. CONCLUSION: Patients with acute myocardial infarction report a higher subjective mental stress during 2 to 4 weeks preceding the acute coronary event.

  17. Heat transfer and thermal stress analysis in grooved tubes

    Indian Academy of Sciences (India)

    Veysel Özceyhan; Necdet Altuntop

    2005-08-01

    Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was applied from the external surface of the tube. Energy and governing flow equations were solved using finite difference scheme. Finite element method (FEM) was used to compute the thermal stress fields. Grooving effects on the thermal stress ratio have been discussed. As a result, maximum thermal stress occurs in the case of $p = d$ for all water inlet velocities. The maximum thermal stress ratio positions inside the tube have been indicated as MX for all investigated cases. In the light of the thermal stress values, various designs can be applied to reduce thermal stress in grooved tubes.

  18. Thermal Stress Analysis of Welded Joint in 1420 Al-Li Alloy Induced by Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    Hongbin GENG; Song HE; Dezhuang YANG

    2003-01-01

    A model of double grains under plane stress state has been established. According to the double grain model, thermal stress induced by thermal cycling in welding fusion zone is numerically simulated by finite element method, and the microstructures before

  19. Finite Element Analysis of Thermal Stresses in Ceramic/Metal Gradient Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    MING Pingshun; XIAO Jinsheng; LIU Jie; ZHOU Xiaoqin

    2005-01-01

    This paper studied the thermal stresses of ceramic/metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating (TBC) and functionally gradient material (FGM). Thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.

  20. Acute psychosocial stress and children's memory

    NARCIS (Netherlands)

    Veld, D.M.J. de; Riksen-Walraven, J.M.A.; Weerth, C. de

    2014-01-01

    We investigated whether children's performance on working memory (WM) and delayed retrieval (DR) tasks decreased after stress exposure, and how physiological stress responses related to performance under stress. About 158 children (83 girls; M-age = 10.61 years, SD = 0.52) performed two WM tasks (WM

  1. Physiological Responses to Thermal Stress and Exercise

    Science.gov (United States)

    Iyota, Hiroyuki; Ohya, Akira; Yamagata, Junko; Suzuki, Takashi; Miyagawa, Toshiaki; Kawabata, Takashi

    The simple and noninvasive measuring methods of bioinstrumentation in humans is required for optimization of air conditioning and management of thermal environments, taking into consideration the individual specificity of the human body as well as the stress conditions affecting each. Changes in human blood circulation were induced with environmental factors such as heat, cold, exercise, mental stress, and so on. In this study, the physiological responses of human body to heat stress and exercise were investigated in the initial phase of the developmental research. We measured the body core and skin temperatures, skin blood flow, and pulse wave as the indices of the adaptation of the cardiovascular system. A laser Doppler skin blood flowmetry using an optical-sensor with a small portable data logger was employed for the measurement. These results reveal the heat-stress and exercise-induced circulatory responses, which are under the control of the sympathetic nerve system. Furthermore, it was suggested that the activity of the sympathetic nervous system could be evaluated from the signals of the pulse wave included in the signals derived from skin blood flow by means of heart rate variability assessments and detecting peak heights of velocity-plethysmogram.

  2. Sympathetic neural responses to mental stress during acute simulated microgravity

    OpenAIRE

    Durocher, John J.; Schwartz, Christopher E.; Carter, Jason R.

    2009-01-01

    Neural and cardiovascular responses to mental stress and acute 6° head-down tilt (HDT) were examined separately and combined. We hypothesized sympathoexcitation during mental stress, sympathoinhibition during HDT, and an additive neural interaction during combined mental stress and HDT. Muscle sympathetic nerve activity (MSNA), mean arterial pressure (MAP), and heart rate (HR) were recorded in 16 healthy subjects (8 men, 8 women) in the supine position during three randomized trials: 1) menta...

  3. Acute Stress Reduces Reward Responsiveness: Implications for Depression

    OpenAIRE

    Bogdan, Ryan; Pizzagalli, Diego

    2006-01-01

    Background: Stress, one of the strongest risk factors for depression, has been linked to "anbedonic" behavior and dysfunctional reward-related neural circuitry in preclinical models. Methods: To test if acute stress reduces reward responsiveness (i.e., the ability to modulate behavior as a function of past reward), a signal-detection task coupled with a differential reinforcement schedule was utilized. Eighty female participants completed the task under both a stress condition, either threat-...

  4. 40 CFR 91.329 - Catalyst thermal stress test.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Catalyst thermal stress test. 91.329....329 Catalyst thermal stress test. (a) Oven characteristics. The oven used for termally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C. (b)...

  5. Acute stress selectively impairs learning to act.

    Science.gov (United States)

    de Berker, Archy O; Tirole, Margot; Rutledge, Robb B; Cross, Gemma F; Dolan, Raymond J; Bestmann, Sven

    2016-01-01

    Stress interferes with instrumental learning. However, choice is also influenced by non-instrumental factors, most strikingly by biases arising from Pavlovian associations that facilitate action in pursuit of rewards and inaction in the face of punishment. Whether stress impacts on instrumental learning via these Pavlovian associations is unknown. Here, in a task where valence (reward or punishment) and action (go or no-go) were orthogonalised, we asked whether the impact of stress on learning was action or valence specific. We exposed 60 human participants either to stress (socially-evaluated cold pressor test) or a control condition (room temperature water). We contrasted two hypotheses: that stress would lead to a non-selective increase in the expression of Pavlovian biases; or that stress, as an aversive state, might specifically impact action production due to the Pavlovian linkage between inaction and aversive states. We found support for the second of these hypotheses. Stress specifically impaired learning to produce an action, irrespective of the valence of the outcome, an effect consistent with a Pavlovian linkage between punishment and inaction. This deficit in action-learning was also reflected in pupillary responses; stressed individuals showed attenuated pupillary responses to action, hinting at a noradrenergic contribution to impaired action-learning under stress. PMID:27436299

  6. Individual differences in delay discounting under acute stress: the role of trait perceived stress

    Directory of Open Access Journals (Sweden)

    Karolina M. Lempert

    2012-07-01

    Full Text Available Delay discounting refers to the reduction of the value of a future reward as the delay to that reward increases. The rate at which individuals discount future rewards varies as a function of both individual and contextual differences, and high delay discounting rates have been linked with problematic behaviors, including drug abuse and gambling. The current study investigated the effects of acute anticipatory stress on delay discounting, while considering two important factors: individual perceptions of stress and whether the stressful situation is future-focused or present-focused. Half of the participants experienced acute stress by anticipating giving a videotaped speech. This stress was either future-oriented (speech about future job or present-oriented (speech about physical appearance. They then performed a delay discounting task, in which they chose between smaller, immediate rewards and larger, delayed rewards. Their scores on the Perceived Stress Scale were also collected. The way in which one appraises a stressful situation interacts with acute stress to influence choices; under stressful conditions, delay discounting rate was highest in individuals with low perceived stress and lowest for individuals with high perceived stress. This result might be related to individual variation in reward responsiveness under stress. Furthermore, the time orientation of the task interacted with its stressfulness to affect the individual’s propensity to choose immediate rewards. These findings add to our understanding of the intermediary factors between stress and decision making.

  7. Cannabinoids & Stress: impact of HU-210 on behavioral tests of anxiety in acutely stressed mice.

    Science.gov (United States)

    Kinden, Renee; Zhang, Xia

    2015-05-01

    Anxiety disorders are one of the most prevalent classes of mental disorders affecting the general population, but current treatment strategies are restricted by their limited efficacy and side effect profiles. Although the cannabinoid system is speculated to be a key player in the modulation of stress responses and emotionality, the vast majority of current research initiatives had not incorporated stress exposure into their experimental designs. This study was the first to investigate the impact of exogenous cannabinoid administration in an acutely stressed mouse model, where CD1 mice were pre-treated with HU-210, a potent CB1R agonist, prior to acute stress exposure and subsequent behavioral testing. Exogenous cannabinoid administration induced distinct behavioral phenotypes in stressed and unstressed mice. While low doses of HU-210 were anxiolytic in unstressed subjects, this effect was abolished when mice were exposed to an acute stressor. The administration of higher HU-210 doses in combination with acute stress exposure led to severe locomotor deficits that were not previously observed at the same dose in unstressed subjects. These findings suggest that exogenous cannabinoids and acute stress act synergistically in an anxiogenic manner. This study underlies the importance of including stress exposure into future anxiety-cannabinoid research due to the differential impact of cannabinoid administration on stressed and unstressed subjects.

  8. Acute stress modulates genotype effects on amygdala processing in humans

    OpenAIRE

    Cousijn, Helena; Rijpkema, Mark; Qin, Shaozheng; van Marle, Hein J. F.; Franke, Barbara; Hermans, Erno J.; van Wingen, Guido; Fernández, Guillén

    2010-01-01

    Probing gene–environment interactions that affect neural processing is crucial for understanding individual differences in behavior and disease vulnerability. Here, we tested whether the current environmental context, which affects the acute brain state, modulates genotype effects on brain function in humans. We manipulated the context by inducing acute psychological stress, which increases noradrenergic activity, and probed its effect on tonic activity and phasic responses in the amygdala us...

  9. Acute stress impairs cognitive flexibility in men, not women.

    Science.gov (United States)

    Shields, Grant S; Trainor, Brian C; Lam, Jovian C W; Yonelinas, Andrew P

    2016-09-01

    Psychosocial stress influences cognitive abilities, such as long-term memory retrieval. However, less is known about the effects of stress on cognitive flexibility, which is mediated by different neurobiological circuits and could thus be regulated by different neuroendocrine pathways. In this study, we randomly assigned healthy adults to an acute stress induction or control condition and subsequently assessed participants' cognitive flexibility using an open-source version of the Wisconsin Card Sort task. Drawing on work in rodents, we hypothesized that stress would have stronger impairing effects on cognitive flexibility in men than women. As predicted, we found that stress impaired cognitive flexibility in men but did not significantly affect women. Our results thus indicate that stress exerts sex-specific effects on cognitive flexibility in humans and add to the growing body of research highlighting the need to consider sex differences in effects of stress.

  10. Thermal fatigue of pipes induced by fluid temperature change. Influence of thermal stratification oscillation characteristics on thermal stress response

    International Nuclear Information System (INIS)

    The oscillation of thermal stratification layer has possibilities to induce thermal fatigue damages on structures of nuclear components. To evaluate thermal stress induced by thermal stratification oscillation, the moving layer frequency response function of thermal stress was developed. However, the model assumed in developing this function does not take into account the thickness of the thermal stratification layer. Thus, it is impossible to evaluate the stress generated by thermal stratified layer having finite thickness with sufficient accuracy. To clarify the effects of thickness of stratified layer, finite element simulations were conducted under some fluid conditions. Based on mechanisms of above effects, the frequency response function was improved. (author)

  11. Acute psychosocial stress and children's memory.

    Science.gov (United States)

    de Veld, Danielle M J; Riksen-Walraven, J Marianne; de Weerth, Carolina

    2014-07-01

    We investigated whether children's performance on working memory (WM) and delayed retrieval (DR) tasks decreased after stress exposure, and how physiological stress responses related to performance under stress. About 158 children (83 girls; Mage = 10.61 years, SD = 0.52) performed two WM tasks (WM forward and WM backward) and a DR memory task first during a control condition, and 1 week later during a stress challenge. Salivary alpha-amylase (sAA) and cortisol were assessed during the challenge. Only WM backward performance declined over conditions. Correlations between physiological stress responses and performance within the stress challenge were present only for WM forward and DR. For WM forward, higher cortisol responses were related to better performance. For DR, there was an inverted U-shape relation between cortisol responses and performance, as well as a cortisol × sAA interaction, with concurrent high or low responses related to optimal performance. This emphasizes the importance of including curvilinear and interaction effects when relating physiology to memory.

  12. Acute Anteroseptal Myocardial Infarction after a Negative Exercise Stress Test

    OpenAIRE

    Abdullah M. Al-Alawi; Jyotsna Janardan; Peck, Kah Y.; Alan Soward

    2016-01-01

    A myocardial infarction is a rare complication which can occur after an exercise stress test. We report a 48-year-old male who was referred to the Mildura Cardiology Practice, Victoria, Australia, in August 2014 with left-sided chest pain. He underwent an exercise stress test which was negative for myocardial ischaemia. However, the patient presented to the Emergency Department of the Mildura Base Hospital 30 minutes after the test with severe retrosternal chest pain. An acute anteroseptal ST...

  13. Acute Stress Disorder: Conceptual Issues and Treatment Outcomes

    Science.gov (United States)

    Koucky, Ellen M.; Galovski, Tara E.; Nixon, Reginald D. V.

    2012-01-01

    Acute stress disorder (ASD) was included as a diagnosis to the 4th edition of the "Diagnostic and Statistical Manual" (American Psychiatric Association, 1994) as a way of describing pathological reactions in the first month following a trauma. Since that time, ASD has been the focus of some controversy, particularly regarding the theoretical basis…

  14. Predicting Performance Under Acute Stress : The Role of Individual Characteristics

    NARCIS (Netherlands)

    Delahaij, R.; Dam, K. van; Gaillard, A.W.K.; Soeters, J.

    2011-01-01

    This prospective study examined how differences in coping style, coping self-efficacy, and metacognitive awareness influence coping behavior and performance during a realistic acute stressful exercise in 2 military samples (n = 122 and n = 132). Results showed that coping self-efficacy and coping st

  15. Deficiency of antinociception and excessive grooming induced by acute immobilization stress in Per1 mutant mice.

    Science.gov (United States)

    Zhang, Jing; Wu, Zhouqiao; Zhou, Linglin; Li, Huili; Teng, Huajing; Dai, Wei; Wang, Yongqing; Sun, Zhong Sheng

    2011-01-14

    Acute stressors induce changes in numerous behavioral parameters through activation of the hypothalamic-pituitary-adrenal (HPA) axis. Several important hormones in paraventricular nucleus of the hypothalamus (PVN) play the roles in these stress-induced reactions. Corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) and corticosterone are considered as molecular markers for stress-induced grooming behavior. Oxytocin in PVN is an essential modulator for stress-induced antinociception. The clock gene, Per1, has been identified as an effecter response to the acute stresses, but its function in neuroendocrine stress systems remains unclear. In the present study we observed the alterations in grooming and nociceptive behaviors induced by acute immobilization stress in Per1 mutant mice and other genotypes (wild types and Per2 mutant). The results displayed that stress elicited a more robust effect on grooming behavior in Per1 mutant mice than in other genotypes. Subsequently, the obvious stress-induced antinociception was observed in the wild-type and Per2 mutant mice, however, in Per1 mutant, this antinociceptive effects were partially-reversed (mechanical sensitivity), or over-reversed to hyperalgesia (thermal sensitivity). The real-time qPCR results showed that in PVN, there were stress-induced up-regulations of Crh, Avp and c-fos in all of genotypes; moreover, the expression change of Crh in Per1 mutant mice was much larger than in others. Another hormonal gene, Oxt, was up-regulated induced by stress in wild-type and Per2 mutant but not in Per1 mutant. In addition, the stress significantly elevated the serum corticosterone levels without genotype-dependent differences, and accordingly the glucocorticoid receptor gene, Nr3c1, expressed with a similar pattern in PVN of all strains. Taken together, the present study indicated that in acute stress treated Per1 mutant mice, there are abnormal hormonal responses in PVN, correlating with the aberrant

  16. The Relationship between Acute Stress Disorder and Posttraumatic Stress Disorder Following Cancer

    Science.gov (United States)

    Kangas, Maria; Henry, Jane L.; Bryant, Richard A.

    2005-01-01

    In this study, the authors investigated the relationship between acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) following cancer diagnosis. Patients who were recently diagnosed with 1st onset head and neck or lung malignancy (N = 82) were assessed for ASD within the initial month following their diagnosis and reassessed (n =…

  17. Does acute stress disorder predict posttraumatic stress disorder following bank robbery?

    DEFF Research Database (Denmark)

    Hansen, M.; Elklit, A.

    2013-01-01

    Unfortunately, the number of bank robberies is increasing and little is known about the subsequent risk of posttraumatic stress disorder (PTSD). Several studies have investigated the prediction of PTSD through the presence of acute stress disorder (ASD). However, there have only been a few studie...

  18. Does Acute Stress Disorder Predict Posttraumatic Stress Disorder Following Bank Robbery?

    Science.gov (United States)

    Hansen, Maj; Elklit, Ask

    2013-01-01

    Unfortunately, the number of bank robberies is increasing and little is known about the subsequent risk of posttraumatic stress disorder (PTSD). Several studies have investigated the prediction of PTSD through the presence of acute stress disorder (ASD). However, there have only been a few studies following nonsexual assault. The present study…

  19. REPEATED ACUTE STRESS INDUCED ALTERATIONS IN CARBOHYDRATE METABOLISM IN RAT

    Directory of Open Access Journals (Sweden)

    Nirupama R.

    2010-09-01

    Full Text Available Acute stress induced alterations in the activity levels of rate limiting enzymes and concentration of intermediates of different pathways of carbohydrate metabolism have been studied. Adult male Wistar rats were restrained (RS for 1 h and after an interval of 4 h they were subjected to forced swimming (FS exercise and appropriate controls were maintained. Five rats were killed before the commencement of the experiment (initial controls, 5 control and equal number of stressed rats were killed 2 h after RS and remaining 5 rats in each group were killed 4 h after FS. There was a significant increase in the adrenal 3β- hydroxy steroid dehydrogenase activity following RS, which showed further increase after FS compared to controls and thereby indicated stress response of rats. There was a significant increase in the blood glucose levels following RS which showed further increase and reached hyperglycemic condition after FS. The hyperglycemic condition due to stress was accompanied by significant increases in the activities of glutamate- pyruvate transaminase, glutamate- oxaloacetate transaminase, glucose -6- phosphatase and lactate dehydrogenase and significant decrease in the glucose -6- phosphate dehydrogenase and pyruvate dehydrogenase activities, whereas pyruvate kinase activity did not show any alteration compared to controls. Further, the glycogen and total protein contents of the liver were decreased whereas those of pyruvate and lactate showed significant increase compared to controls after RS as well as FS.The results put together indicate that acute stress induced hyperglycemia results due to increased gluconeogenesis and glycogenolysis without alteration in glycolysis. The study first time reveals that after first acute stress exposure, the subsequent stressful experience augments metabolic stress response leading to hyperglycemia. The results have relevance to human health as human beings are exposed to several stressors in a day and

  20. Acute stress responses: A review and synthesis of ASD, ASR, and CSR.

    Science.gov (United States)

    Isserlin, Leanna; Zerach, Gadi; Solomon, Zahava

    2008-10-01

    Toward the development of a unifying diagnosis for acute stress responses this article attempts to find a place for combat stress reaction (CSR) within the spectrum of other defined acute stress responses. This article critically compares the diagnostic criteria of acute stress disorder (ASD), acute stress reaction (ASR), and CSR. Prospective studies concerning the predictive value of ASD, ASR, and CSR are reviewed. Questions, recommendations, and implications for clinical practice are raised concerning the completeness of the current acute stress response diagnoses, the heterogeneity of different stressors, the scope of expected outcomes, and the importance of decline in function as an indicator of future psychological, psychiatric, and somatic distress. PMID:19123763

  1. Effect of severe environmental thermal stress on redox state in salmon.

    Science.gov (United States)

    Nakano, Toshiki; Kameda, Masumi; Shoji, Yui; Hayashi, Satoshi; Yamaguchi, Toshiyasu; Sato, Minoru

    2014-01-01

    Fish are exposed to many kinds of environmental stressors and the chances of succumbing to infectious diseases may be increased a result. For example, an acute increase in temperature can induce numerous physiological changes in the body. In the present study, we examined the redox state in response to a severe acute stress resulting from heat shock in teleost coho salmon (Oncorhynchus kisutch). The plasma lipid peroxides levels in fish gradually increased after heat shock treatment. By 2.5 h post-heat stress, plasma glutathione (GSH) levels had decreased, but they had returned to basal levels by 17.5 h post-stress. Plasma superoxide dismutase activities in stressed fish were significantly increased compared with those in control fish at 17.5 h post-stress, but had returned to basal levels by 48 h post-stress. Expression levels of hepatic GSH and heat shock protein 70 gradually increased after heat shock treatment. These results concerning the changing patterns of multiple important redox-related biomarkers suggest that severe thermal stressors can affect the redox state and induce oxidative stress in ectothermal animals, such as fish, in vivo. Hence, manipulation of appropriate thermal treatment may possibly be useful to control fish fitness.

  2. Effect of severe environmental thermal stress on redox state in salmon

    Directory of Open Access Journals (Sweden)

    Toshiki Nakano

    2014-01-01

    Full Text Available Fish are exposed to many kinds of environmental stressors and the chances of succumbing to infectious diseases may be increased a result. For example, an acute increase in temperature can induce numerous physiological changes in the body. In the present study, we examined the redox state in response to a severe acute stress resulting from heat shock in teleost coho salmon (Oncorhynchus kisutch. The plasma lipid peroxides levels in fish gradually increased after heat shock treatment. By 2.5 h post-heat stress, plasma glutathione (GSH levels had decreased, but they had returned to basal levels by 17.5 h post-stress. Plasma superoxide dismutase activities in stressed fish were significantly increased compared with those in control fish at 17.5 h post-stress, but had returned to basal levels by 48 h post-stress. Expression levels of hepatic GSH and heat shock protein 70 gradually increased after heat shock treatment. These results concerning the changing patterns of multiple important redox-related biomarkers suggest that severe thermal stressors can affect the redox state and induce oxidative stress in ectothermal animals, such as fish, in vivo. Hence, manipulation of appropriate thermal treatment may possibly be useful to control fish fitness.

  3. Effect of thermal shield and gas flow on thermal elastic stresses in 300 mm silicon crystal

    Institute of Scientific and Technical Information of China (English)

    GAO Yu; XIAO Qinghua; ZHOU Qigang; DAI Xiaolin; TU Hailing

    2006-01-01

    The thermal elastic stresses induced in 300 mm Si crystal may be great troubles because it can incur the generation of dislocations and undesirable excessive residual stresses.A special thermal modeling tool, CrysVUn, was used for numerical analysis of thermal elastic stresses and stress distribution of 300 mm Si crystal under the consideration of different thermal shields and gas flow conditions.The adopted governing partial equations for stress calculation are Cauchy's first and second laws of motion.It is demonstrated that the presence and shape of thermal shield, the gas pressure and velocity can strongly affect von Mises stress distribution in Si crystal.With steep-wall shield, however, the maximal stress and ratio of high stress area are relatively low.With slope-wall shield or without shield, both maximal stress and ratio of high stress area are increased in evidence.Whether thermal shields are used or not, the increase of gas flow velocity could raise the stress level.In contrast, the increase of gas pressure cannot result in so significant effect.The influence of thermal shield and gas flow should be attributed to the modification of heat conduction and heat radiation by them.

  4. Thermal Super-Pixels for Bimodal Stress Recognition

    DEFF Research Database (Denmark)

    Irani, Ramin; Nasrollahi, Kamal; Dhall, Abhinav;

    2016-01-01

    to be in touch with the body which is not always practical. Contact-free monitoring of the stress by a camera [1, 2] can be an alternative. These systems usually utilize only an RGB or a thermal camera to recognize stress. To the best of our knowledge, the only work on fusion of these two modalities for stress...

  5. Evaluation of properties and thermal stress field for thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    王良; 齐红宇; 杨晓光; 李旭

    2008-01-01

    In order to get thermal stress field of the hot section with thermal barrier coating (TBCs), the thermal conductivity and elastic modulus of top-coat are the physical key properties. The porosity of top-coat was tested and evaluated under different high temperatures. The relationship between the microstructure (porosity of top-coat) and properties of TBCs were analyzed to predict the thermal properties of ceramic top-coat, such as thermal conductivity and elastic modulus. The temperature and stress field of the vane with TBCs were simulated using two sets of thermal conductivity data and elastic modulus, which are from literatures and this work, respectively. The results show that the temperature and stress distributions change with thermal conductivity and elastic modulus. The differences of maximum temperatures and stress are 6.5% and 8.0%, respectively.

  6. Fluoxetine and diazepam acutely modulate stress induced-behavior.

    Science.gov (United States)

    Giacomini, Ana Cristina V V; Abreu, Murilo S; Giacomini, Luidia V; Siebel, Anna M; Zimerman, Fernanda F; Rambo, Cassiano L; Mocelin, Ricieri; Bonan, Carla D; Piato, Angelo L; Barcellos, Leonardo J G

    2016-01-01

    Drug residue contamination in aquatic ecosystems has been studied extensively, but the behavioral effects exerted by the presence of these drugs are not well known. Here, we investigated the effects of acute stress on anxiety, memory, social interaction, and aggressiveness in zebrafish exposed to fluoxetine and diazepam at concentrations that disrupt the hypothalamic-pituitary-interrenal (HPI) axis. Stress increased the locomotor activity and time spent in the bottom area of the tank (novel tank). Fluoxetine and diazepam prevented these behaviors. We also observed that stress and fluoxetine and diazepam exposures decreased social interaction. Stress also increased aggressive behavior, which was not reversed by fluoxetine or diazepam. These data suggest that the presence of these drugs in aquatic ecosystems causes significant behavioral alterations in fish. PMID:26403161

  7. Photo-elastic effect, thermal lensing and depolarization in a-cut tetragonal laser crystals

    Science.gov (United States)

    Yumashev, K. V.; Zakharova, A. N.; Loiko, P. A.

    2016-06-01

    We report on analytical description of thermal lensing effect in tetragonal crystals cut along the [1 0 0] crystallographic axis, for the two principal light polarizations, E ┴ c and E || c, under diode-pumping (plane stress approximation). Within this approach, we take into account anisotropy of elastic, photo-elastic, thermal and optical properties of the material. Expressions for the ‘generalized’ thermo-optic coefficient χ are presented. It is shown that astigmatism of thermal lens is determined both by the photo-elastic and end-bulging effects. The sign of the photo-elastic term χ″ can be either positive or negative affecting significantly the sign of the thermal lens. Depolarization loss in a-cut tetragonal crystals is few orders of magnitude lower than that in cubic crystals. Calculations are performed for a-cut tetragonal molybdates, Nd:CaMoO4, Nd:PbMoO4 and Nd:NaBi(MoO4)2.

  8. Insect population differentiation in response to enviromental thermal stress

    Institute of Scientific and Technical Information of China (English)

    CHEN Bing; KANG Le

    2005-01-01

    Numerous studies reported the adaptation strategies adopted by ecthotherms to survive under environmental thermal stress. Geographic and seasonal variations in the thermal stress tolerance, which is closely associated with species' climatic adaptation and allopatric speciation, have been extensively investigated in insects. The variation patterns suggest directional selection for species' adaptive straits, and are used to predict the origin, distribution and dynamics of insect populations. These studies are becoming more and more important in the context of global warming. This paper discusses the process of adaptation to environmental thermal stress and the mechanisms underlying the differentiation in related adaptive straits of insect populations.

  9. Anxiety symptom severity differentiates HPA acute stress reactivity in children

    OpenAIRE

    Slattery, Marcia J.; Grieve, Adam J.; Paletz, Elliott M.; Kalin, Ned H.

    2012-01-01

    Rationale/statement of the problem : Considerable research has focused on the relationship of anxiety with alterations in the hypothalamic-pituitary-adrenal (HPA) acute stress response. Findings, however, differ among studies on adults and children, and among different types of anxiety. This study investigates the relationship of anxiety symptom severity with HPA reactivity to the cold pressor task (CPT) in preadolescent children. We hypothesize that children with increased symptoms of anxiet...

  10. Thermal stresses in composite tubes using complementary virtual work

    Science.gov (United States)

    Hyer, M. W.; Cooper, D. E.

    1988-01-01

    This paper addresses the computation of thermally induced stresses in layered, fiber-reinforced composite tubes subjected to a circumferential gradient. The paper focuses on using the principle of complementary virtual work, in conjunction with a Ritz approximation to the stress field, to study the influence on the predicted stresses of including temperature-dependent material properties. Results indicate that the computed values of stress are sensitive to the temperature dependence of the matrix-direction compliance and matrix-direction thermal expansion in the plane of the lamina. There is less sensitivity to the temperature dependence of the other material properties.

  11. Modelling of thermal stress in vapor generator supports

    International Nuclear Information System (INIS)

    To assure safety and availability of a nuclear power plant components or equipment stress analysis are done. When thermal loads are involved it's necessary to know the temperature field of the component or equipment. This paper describes the structural analysis of a steam generator lug with thermal load including the model used for computer simulation and presents the evolution of the temperature profile, the stress intensity and principal stress during start up and shut down of a nuclear power reactor. Temperature field obtained from code calculation show good agreement with the experimental data while stress analysis results are in agreement with a preview estimation. (author)

  12. Residual stress evolution regularity in thermal barrier coatings under thermal shock loading

    Directory of Open Access Journals (Sweden)

    Ximin Chen

    2014-01-01

    Full Text Available Residual stress evolution regularity in thermal barrier ceramic coatings (TBCs under different cycles of thermal shock loading of 1100°C was investigated by the microscopic digital image correlation (DIC and micro-Raman spectroscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress undergoes three distinct stages: a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1100°C, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide (TGO layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.

  13. Stress dependent thermal pressurization of a fluid-saturated rock

    CERN Document Server

    Ghabezloo, Siavash

    2008-01-01

    Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experimentally for a saturated granular rock in an undrained heating test under constant isotropic stress. Careful analysis of the effect of mechanical and thermal deformation of the drainage and pressure measurement system is performed and a correction of the measured pore pressure is introduced. The test results are modelled using a non-linear thermo-poro-elastic constitutive model of the granular rock with emphasis on the stress-dependent character of the rock compressibility. The effects of stress and temperature on therma...

  14. Response of Serum Prolactin to Thermal Stress During Water Immersion

    OpenAIRE

    Matsumoto, Takaaki; Kosaka, Mitsuo; Yamauchi, Masaki; Nakamura, Koichi; Yamashita, Shunichi; Izumi, Motomori; Nagataki, Shigenobu

    1988-01-01

    Physiological action of prolactin is not well-known in human except those concerning pregnancy and lactation. Elevated serum prolactin level due to various stresses such as heat load, physical exercise, surgery, gastroscopy has been reported. In order to elucidate the response of serum prolactin to thermal stress, preliminary experiments were done in a male subject. Three different thermal stimuli were applied by head-out water immersion (water temperature: 28.5, 34 and 40℃, respectively) for...

  15. Comparison of the effects of acute and chronic psychological stress on metabolic features in rats

    Institute of Scientific and Technical Information of China (English)

    Fatemeh ROSTAMKHANI; Homeira ZARDOOZ; Saleh ZAHEDIASL; Babak FARROKHI

    2012-01-01

    This study was aimed to compare the effects of acute and chronic psychological stress on metabolic factors.Forty-two male Wistar rats were divided into control and stressed groups.Stress was applied by a communication box acutely (1 d) and chronically (15 and 30 d).Blood sampling was carried out by retro-orbital-puncture method.The plasma levels of glucose,cholesterol,triglyceride,insulin,and corticosterone were measured.In addition,feed and water intake,latency to eat and drink,adrenal and body weights were determined.Acute and chronic psychological stress did not significantly change basal plasma corticosterone levels.However,immediately (1 min) after acute exposure to stress,plasma corticosterone level increased compared to that before stress exposure.Acute stress increased plasma insulin levels significantly.Fifteen days of stress exposure resulted in plasma glucose increase.Chronic stress significantly increased feed intake,latency to eat,and adrenal weight compared to acute stress.The body weights of both control and stressed groups increased markedly during the experiment.Homeostasis model assessment of insulin resistance (HOMA-IR) index did not change significantly in the stressed group.In conclusion,application of acute and chronic psychological stress leads to different metabolic and/or behavioral changes but the metabolic changes resulting from acute exposure to stress seem to be more pronounced.

  16. Low thermal stress ceramic turbine nozzle

    Science.gov (United States)

    Glezer, Boris; Bagheri, Hamid; Fierstein, Aaron R.

    1996-01-01

    A turbine nozzle vane assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The metallic components having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine nozzle vane assembly. The turbine nozzle vane assembly includes an outer shroud and an inner shroud having a plurality of vanes therebetween. Each of the plurality of vanes have a device for heating and cooling a portion of each of the plurality of vanes. Furthermore, the inner shroud has a plurality of bosses attached thereto. A cylindrical member has a plurality of grooves formed therein and each of the plurality of bosses are positioned in corresponding ones of the plurality of grooves. The turbine nozzle vane assembly provides an economical, reliable and effective ceramic component having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the other component.

  17. Human thermal bioclimatic conditions associated with acute cardiovascular syndromes in Crete Island, Greece

    Science.gov (United States)

    Bleta, Anastasia G.; Nastos, Panagiotis T.

    2013-04-01

    The aim of this study is to quantify the association between bioclimatic conditions and daily counts of admissions for non-fatal acute cardiovascular (acute coronary syndrome, arrhythmia, decompensation of heart failure) syndromes (ACS) registered by the two main hospitals in Heraklion, Crete Island, during a five-year period 2008-2012. The bioclimatic conditions analyzed are based on human thermal bioclimatic indices such as the Physiological Equivalent Temperature (PET) and the Universal Thermal Climate Index (UTCI). Mean daily meteorological parameters, such as air temperature, relative humidity, wind speed and cloudiness, were acquired from the meteorological station of Heraklion (Hellenic National Meteorological Service). These parameters were used as input variables in modeling the aforementioned thermal indices, in order to interpret the grade of the thermo-physiological stress. The PET and UTCI analysis was performed by the use of the radiation and bioclimate model, "RayMan", which is well-suited to calculate radiation fluxes and human biometeorological indices. Generalized linear models (GLM) were applied to time series of daily numbers of outpatients with ACS against bioclimatic variations, after controlling for possible confounders and adjustment for season and trends. The interpretation of the results of this analysis suggests a significant association between cold weather and increased coronary heart disease incidence, especially in the elderly and males. Additionally, heat stress plays an important role in the configuration of daily ACS outpatients, even in temperate climate, as that in Crete Island. In this point it is worth mentioning that Crete Island is frequently affected by Saharan outbreaks, which are associated in many cases with miscellaneous phenomena, such as Föhn winds - hot and dry winds - causing extreme bioclimatic conditions (strong heat stress). Taking into consideration the projected increased ambient temperature in the future, ACS

  18. Acute Stress Reactions in Couples after a Burn Event to Their Young Child

    NARCIS (Netherlands)

    Bakker, A.; Van Loey, N.E.; Van der Heijden, P.G.M.; Van Son, M.J.M.

    2012-01-01

    Objective This multicenter study examines acute stress reactions in couples following a burn event to their preschool child. Methods Participants were 182 mothers and 154 fathers, including 143 couples, of 193 children (0–4 years) with acute burns. Parents’ self-reported acute stress reactions and e

  19. Think aloud: acute stress and coping strategies during golf performances.

    Science.gov (United States)

    Nicholls, Adam R; Polman, Remco C J

    2008-07-01

    A limitation of the sport psychology coping literature is the amount of time between a stressful episode and the recall of the coping strategies used in the stressful event (Nicholls & Polman, 2007). The purpose of this study was to develop and implement a technique to measure acute stress and coping during performance. Five high-performance adolescent golfers took part in Level 2 verbalization think aloud trials (Ericsson & Simon, 1993), which involved participants verbalizing their thoughts, over six holes of golf. Verbal reports were audio-recorded during each performance, transcribed verbatim, and analyzed using protocol analysis (Ericsson & Simon, 1993). Stressors and coping strategies varied throughout the six holes, which support the proposition that stress and coping is a dynamic process that changes across phases of the same performance (Lazarus, 1999). The results also revealed information regarding the sequential patterning of stress and coping, suggesting that the golfers experienced up to five stressors before reporting a coping strategy. Think aloud appears a suitable method to collect concurrent stress and coping data. PMID:18612855

  20. Prenatal Acute Stress Attenuated Epileptiform Activities in Neonate Mice

    Directory of Open Access Journals (Sweden)

    Behnam Heshmatian

    2010-01-01

    Full Text Available Objective: Development of the central nervous system (CNS is dependent on interactionsbetween genetic and epigenetic factors, some of which could affect the susceptibilityof the developing brain to damaging insults. Gestational stress has been shown as a potentialfactor associated with higher risk of developing certain neurological and psychiatricdisorders. This study tested the hypothesis that maternal stress influences the risk ofepilepsy in offsprings.Materials and Methods: Pregnant mice were exposed to restraint stress twice a day forthree days at the start of the last week of gestation. Ten days after birth, the intact hippocampiof the newborn mice were excised and prepared for investigation. The hippocampiwere bathed in low magnesium artificial cerebrospinal fluid to induce field potential,and the subsequent spontaneous seizure-like events of the CA1 neurons were recorded.Plasma corticosterone was measured using a commercial radioimmunoassay (RIA kitand the values were expressed as μg/100 ml.Results: Both the number of recurrent seizures and the duration of seizure activity werereduced in the stressed group compared to the controls (p<0.001. Stress induced a significantrise in serum corticosterone levels in both pregnant mice and in their newbornpups (p<0.001.Conclusion: These findings suggest that acute prenatal stress, which may mimic acutestress in human pregnancy, is a likely factor affecting seizure control in childhood temporallobe epilepsy. The underlying inhibitory mechanism may be an increase in the level ofneurosteroids both in the blood and the brain.

  1. A new model for analysing thermal stress in granular composite

    Institute of Scientific and Technical Information of China (English)

    郑茂盛; 金志浩; 浩宏奇

    1995-01-01

    A double embedding model of inletting reinforcement grain and hollow matrix ball into the effective media of the particulate-reinforced composite is advanced. And with this model the distributions of thermal stress in different phases of the composite during cooling are studied. Various expressions for predicting elastic and elastoplastic thermal stresses are derived. It is found that the reinforcement suffers compressive hydrostatic stress and the hydrostatic stress in matrix zone is a tensile one when temperature decreases; when temperature further decreases, yield area in matrix forms; when the volume fraction of reinforcement is enlarged, compressive stress on grain and tensile hydrostatic stress in matrix zone decrease; the initial temperature difference of the interface of reinforcement and matrix yielding rises, while that for the matrix yielding overall decreases.

  2. Thermal residual stresses and stress distributions under tensile and compressive loadings of short fiber reinforced metal matrix composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The thermal residual stresses and the stress distributions of short fiber reinforced metal matrix composite under tensile and compressive loadings were studied using large strain axisymmetric elasto-plastic finite element method. It is demonstrated that the thermal residual stresses can result in asymmetrical stress distributions and matrix plasticity. The thermal residual stresses decrease the stress transfer in tension and enhance the stress transfer in compression. The fiber volume fraction has more important effects on the thermal residual stresses and the stress distributions under tensile and compressive loadings than the fiber aspect ratio and the fiber end distance.

  3. Thermally developing forced convection and the corresponding thermal stresses in a porous plate channel

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao; LIU Xuemei

    2007-01-01

    Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection of the local thermal equili- brium and the corresponding thermal stresses in a semi- infmite saturated porous plate channel are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the Péclet number (Pe) and Brinkman number (Br) on temperature, Nusselt number (Nu) and thermal stress are revealed numerically.

  4. Effect of the Mechanical and Thermal Stresses of Rotating Blades

    Directory of Open Access Journals (Sweden)

    Malik M. Ali

    2007-01-01

    Full Text Available Rotating blades are the important parts in gas turbines. Hence, an accurate mathematical estimation (F.E.M of the stresses and deformations characteristics was required in the design applications to avoid failure. In recent year’s there are researchers interest in the effect of temperature on solid bodies has greatly increased, The main of this study investigated the thermal and rotational effects. So, the thermal stresses due to high pressure and temperature are studies, also determine the steady state stresses and deformations of rotating blades due to mechanical effect. Many parameters such as thickness and centre of rotating are investigated in this paper. The study results can ensure good recommendation for the effect of the mechanical and thermal stresses of rotary blades.

  5. Effect of Thermal Stress on Cardiac Function

    OpenAIRE

    Wilson, Thad E.; Crandall, Craig G.

    2011-01-01

    Whole-body heating decreases pulmonary capillary wedge pressure and cerebral vascular conductance, and causes an inotropic shift in the Frank-Starling curve. Whole-body cooling increases pulmonary capillary wedge pressure and cerebral vascular conductance without changing systolic function. These and other data indicate factors affecting cardiac function may mechanistically contribute to syncope during heat stress and improvements in orthostatic tolerance during cold stress.

  6. EFFECTS OF ACUTE THERMAL STRESS ON HSP70 MRNA, PHYSIOLOGY AND NONSPECIFIC IMMUNITY IN SIBERIAN STURGEON (ACIPENSER BAERII)%急性热应激对西伯利亚鲟HSP70mRNA表达、血清皮质醇和非特异性免疫的影响

    Institute of Scientific and Technical Information of China (English)

    田照辉; 徐绍刚; 王巍; 胡红霞; 马国庆

    2013-01-01

    The effect of acute thermal stress on HSP1Q mRNA expression, physiology and nonspecific immunity were investigated in Siberian sturgeon. In the experiment, ten fish were transferred froml7.5℃ to 27.5℃ water, then data were measured at lh and 3h. Fish in 17.5℃ water were taken as Oh group. Respiratory rate increased from 80-90 breaths/min to 210 breaths/min, then decreased to 180 breaths/min after 0.5h. Among the three tissues including gill, spleen and brain, the HSP70 mRNA expression in gill rose most quickly after lh stress, and was about 1.63 fold compared with the Oh group (P<0.05), then remained this level to 3h; The HSP10 mRNA expression in spleen and brain had nearly no change in lh thermal stress, then rose quickly from lh to 3h in the two tissues, especially in brain at 3h rose most quickly to about 1.77 fold compared with the lh group (P<0.05). Compared with the Oh group, serum cortisol increased quickly and was 5.14 fold (PO.05) at lh, then decreased quickly to 2.1 fold at 3h. Spleen macrophage respiratory burst achieved the maximum (P<0.05) at lh, then reduced to the Oh group level. Serum complement C3 increased at lh and decreased significantly at 3h (P<0.05). Serum lysozyme activity firstly elevated then decreased but had no significant differences. Serum SOD activity decreased when thermal stress time prolonged, and achieved the minimum at 3h (P<0.05). Serum MDA content decreased when thermal stress time prolonged and had no significant difference. The results showed that lh acute thermal stress promoted the nonspecific immunity and tolerance, but 3h acute thermal stress decreased it.%为研究西伯利亚鲟(Acipenser baerii)对急性热应激的抗逆机理,将体质量为(155.47±19.50) g的鱼从17.5 ℃迅速转至27.5 ℃水中,在1h和3h取样测定HSP70 mRNA表达变化、血清皮质醇和非特异性免疫指标.结果显示:急性热应激时鳃、脾和脑的HSP70 mRNA表达量升高,具有组织特异性,热应激1h时

  7. Effects of hemin and thermal stress exposure on JWA expression

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming; CHEN Rui; LI Aiping; ZHOU Jianwei

    2007-01-01

    To investigate the expression of JWA after hemin and (or) thermal stress exposure,we treated K562 (chronic myelogenous leukemia cells) cells with different doses of hemin and thermal stress using different exposure times.The expression of JWA protein was determined by Western blot analysis.Reverse transcription-polymerase chain reaction was carried out to determine JWA mRNA expression.JWA promoter transcription activity analysis was performed by chloramphenicol acetyl transferase-enzyme linked immunosorbent assay (CAT-ELISA).The expression of JWA protein was significantly increased by up to (3.23 +0.57) folds compared to the control in K562 cells after hemin treatment (50 μM for one week),and a similar pattern was observed in the cells after treatment with thermal stress (42℃) for 2 hours [increased by (8.00+ 1.73) folds].The expression of JWA mRNA was also significantly elevated by up to (1.37 + 0.06)folds in K562 cells treated with hemin (30 μM for 48 hours),and a similar regulatory pattern [increased by (1.87±0.13)folds] was observed with thermal stress exposure (42℃) for 30 minutes.However,a combined antagonistic effect was observed in the treatment of K562 cells with hemin (30 μM,48 h) followed by thermal stress (42℃,30 min).CAT-ELISA further confirmed that either hemin or thermal stress treatment could up-regulate JWA transcription activity,however,the effects could be counteracted partly by treatment with a combination of both.Hemin and thermal stress might regulate JWA expression via distinct intracellular signal transduction pathways.

  8. Acute psychological stress reduces working memory-related activity in the dorsolateral prefrontal cortex.

    NARCIS (Netherlands)

    Qin, S.; Hermans, E.J.; Marle, H.J.F. van; Luo, J.; Fernandez, G.S.E.

    2009-01-01

    BACKGROUND: Acute psychological stress impairs higher-order cognitive function such as working memory (WM). Similar impairments are seen in various psychiatric disorders that are associated with higher susceptibility to stress and with prefrontal cortical dysfunctions, suggesting that acute stress m

  9. Acute Short-Term Mental Stress Does Not Influence Salivary Flow Rate Dynamics

    OpenAIRE

    Naumova, Ella A; Sandulescu, Tudor; Al Khatib, Philipp; Thie, Michael; Lee, Wing-Kee; Zimmer, Stefan; Arnold, Wolfgang H.

    2012-01-01

    Background: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. Methods: S...

  10. Acute Anteroseptal Myocardial Infarction after a Negative Exercise Stress Test

    Directory of Open Access Journals (Sweden)

    Abdullah M. Al-Alawi

    2016-05-01

    Full Text Available A myocardial infarction is a rare complication which can occur after an exercise stress test. We report a 48-year-old male who was referred to the Mildura Cardiology Practice, Victoria, Australia, in August 2014 with left-sided chest pain. He underwent an exercise stress test which was negative for myocardial ischaemia. However, the patient presented to the Emergency Department of the Mildura Base Hospital 30 minutes after the test with severe retrosternal chest pain. An acute anteroseptal ST segment elevation myocardial infarction was observed on electrocardiography. After thrombolysis, he was transferred to a tertiary hospital where coronary angiography subsequently revealed significant left anterior descending coronary artery stenosis. Thrombus aspiration and a balloon angioplasty were performed. The patient was discharged three days after the surgical procedure in good health.

  11. Increased oxidative stress following acute and chronic high altitude exposure.

    Science.gov (United States)

    Jefferson, J Ashley; Simoni, Jan; Escudero, Elizabeth; Hurtado, Maria-Elena; Swenson, Erik R; Wesson, Donald E; Schreiner, George F; Schoene, Robert B; Johnson, Richard J; Hurtado, Abdias

    2004-01-01

    The generation of reactive oxygen species is typically associated with hyperoxia and ischemia reperfusion. Recent evidence has suggested that increased oxidative stress may occur with hypoxia. We hypothesized that oxidative stress would be increased in subjects exposed to high altitude hypoxia. We studied 28 control subjects living in Lima, Peru (sea level), at baseline and following 48 h exposure to high altitude (4300 m). To assess the effects of chronic altitude exposure, we studied 25 adult males resident in Cerro de Pasco, Peru (altitude 4300 m). We also studied 27 subjects living in Cerro de Pasco who develop excessive erythrocytosis (hematocrit > 65%) and chronic mountain sickness. Acute high altitude exposure led to increased urinary F(2)-isoprostane, 8-iso PGF(2 alpha) (1.31 +/- 0.8 microg/g creatinine versus 2.15 +/- 1.1, p = 0.001) and plasma total glutathione (1.29 +/- 0.10 micromol versus 1.37 +/- 0.09, p = 0.002), with a trend to increased plasma thiobarbituric acid reactive substance (TBARS) (59.7 +/- 36 pmol/mg protein versus 63.8 +/- 27, p = NS). High altitude residents had significantly elevated levels of urinary 8-iso PGF(2 alpha) (1.3 +/- 0.8 microg/g creatinine versus 4.1 +/- 3.4, p = 0.007), plasma TBARS (59.7 +/- 36 pmol/mg protein versus 85 +/- 28, p = 0.008), and plasma total glutathione (1.29 +/- 0.10 micromol versus 1.55 +/- 0.19, p < 0.0001) compared to sea level. High altitude residents with excessive erythrocytosis had higher levels of oxidative stress compared to high altitude residents with normal hematological adaptation. In conclusion, oxidative stress is increased following both acute exposure to high altitude without exercise and with chronic residence at high altitude.

  12. Non-thermal Plasma and Oxidative Stress

    Science.gov (United States)

    Toyokuni, Shinya

    2015-09-01

    Thermal plasmas and lasers have been used in medicine to cut and ablate tissues and for coagulation. Non-equilibrium atmospheric pressure plasma (NEAPP; non-thermal plasma) is a recently developed, non-thermal technique with possible biomedical applications. Although NEAPP reportedly generates reactive oxygen/nitrogen species, electrons, positive ions, and ultraviolet radiation, few research projects have been conducted to merge this technique with conventional free radical biology. Recently, Prof. Masaru Hori's group (Plasma Nanotechnology Research Center, Nagoya University) developed a NEAPP device with high electron density. Here electron spin resonance revealed hydroxyl radicals as a major product. To merge non-thermal plasma biology with the preexisting free radical biology, we evaluated lipid peroxidation and DNA modifications in various in vitro and ex vivo experiments. Conjugated dienes increased after exposure to linoleic and alfa-linolenic acids. An increase in 2-thiobarbituric acid-reactive substances was also increased after exposure to phosphatidylcholine, liposomes or liver homogenate. Direct exposure to rat liver in medium produced immunohistochemical evidence of 4-hydroxy-2-nonenal- and acrolein-modified proteins. Exposure to plasmid DNA induced dose-dependent single/double strand breaks and increased the amounts of 8-hydroxy-2'-deoxyguanosine and cyclobutane pyrimidine dimers. These results indicate that oxidative biomolecular damage by NEAPP is dose-dependent and thus can be controlled in a site-specific manner. Simultaneous oxidative and UV-specific DNA damage may be useful in cancer treatment. Other recent advancements in the related studies of non-thermal plasma in Nagoya University Graduate School of Medicine will also be discussed.

  13. Lipid biomarkers in Symbiodinium dinoflagellates: new indicators of thermal stress

    KAUST Repository

    Kneeland, J.

    2013-08-30

    Lipid content and fatty acid profiles of corals and their dinoflagellate endosymbionts are known to vary in response to high-temperature stress. To better understand the heat-stress response in these symbionts, we investigated cultures of Symbiodinium goreauii type C1 and Symbiodinium sp. clade subtype D1 grown under a range of temperatures and durations. The predominant lipids produced by Symbiodinium are palmitic (C16) and stearic (C18) saturated fatty acids and their unsaturated analogs, the polyunsaturated fatty acid docosahexaenoic acid (C22:6, n-3; DHA), and a variety of sterols. Prolonged exposure to high temperature causes the relative amount of unsaturated acids within the C18 fatty acids in Symbiodinium tissue to decrease. Thermal stress also causes a decrease in abundance of fatty acids relative to sterols, as well as the more specific ratio of DHA to an algal 4-methyl sterol. These shifts in fatty acid unsaturation and fatty acid-to-sterol ratios are common to both types C1 and D1, but the apparent thermal threshold of lipid changes is lower for type C1. This work indicates that ratios among free fatty acids and sterols in Symbiodinium can be used as sensitive indicators of thermal stress. If the Symbiodinium lipid stress response is unchanged in hospite, the algal heat-stress biomarkers we have identified could be measured to detect thermal stress within the coral holobiont. These results provide new insights into the potential role of lipids in the overall Symbiodinium thermal stress response. © 2013 Springer-Verlag Berlin Heidelberg.

  14. Financial stress and outcomes after acute myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Sachin J Shah

    Full Text Available BACKGROUND: Little is known about the association between financial stress and health care outcomes. Our objective was to examine the association between self-reported financial stress during initial hospitalization and long-term outcomes after acute myocardial infarction (AMI. MATERIALS AND METHODS: We used prospective registry evaluating myocardial infarction: Event and Recovery (PREMIER data, an observational, multicenter US study of AMI patients discharged between January 2003 and June 2004. Primary outcomes were disease-specific and generic health status outcomes at 1 year (symptoms, function, and quality of life (QoL, assessed by the Seattle Angina Questionnaire [SAQ] and Short Form [SF]-12. Secondary outcomes included 1-year rehospitalization and 4-year mortality. Hierarchical regression models accounted for patient socio-demographic, clinical, and quality of care characteristics, and access and barriers to care. RESULTS: Among 2344 AMI patients, 1241 (52.9% reported no financial stress, 735 (31.4% reported low financial stress, and 368 (15.7% reported high financial stress. When comparing individuals reporting low financial stress to no financial stress, there were no significant differences in post-AMI outcomes. In contrast, individuals reporting high financial stress were more likely to have worse physical health (SF-12 PCS mean difference -3.24, 95% Confidence Interval [CI]: -4.82, -1.66, mental health (SF-12 MCS mean difference: -2.44, 95% CI: -3.83, -1.05, disease-specific QoL (SAQ QoL mean difference: -6.99, 95% CI: -9.59, -4.40, and be experiencing angina (SAQ Angina Relative Risk = 1.66, 95%CI: 1.19, 2.32 at 1 year post-AMI. While 1-year readmission rates were increased (Hazard Ratio = 1.50; 95%CI: 1.20, 1.86, 4-year mortality was no different. CONCLUSIONS: High financial stress is common and an important risk factor for worse long-term outcomes post-AMI, independent of access and barriers to care.

  15. Thermal mechanical stress modeling of GCtM seals

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Chambers, Robert [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Finite-element thermal stress modeling at the glass-ceramic to metal (GCtM) interface was conducted assuming heterogeneous glass-ceramic microstructure. The glass-ceramics were treated as composites consisting of high expansion silica crystalline phases dispersed in a uniform residual glass. Interfacial stresses were examined for two types of glass-ceramics. One was designated as SL16 glass -ceramic, owing to its step-like thermal strain curve with an overall coefficient of thermal expansion (CTE) at 16 ppm/ºC. Clustered Cristobalite is the dominant silica phase in SL16 glass-ceramic. The other, designated as NL16 glass-ceramic, exhibited clusters of mixed Cristobalite and Quartz and showed a near-linear thermal strain curve with a same CTE value.

  16. Transient thermal stress problem for a circumferentially cracked hollow cylinder

    Science.gov (United States)

    Nied, H. F.; Erdogan, F.

    1982-01-01

    The transient thermal stress problem for a hollow elasticity cylinder containing an internal circumferential edge crack is considered. It is assumed that the problem is axisymmetric with regard to the crack geometry and the loading, and that the inertia effects are negligible. The problem is solved for a cylinder which is suddenly cooled from inside. First the transient temperature and stress distributions in an uncracked cylinder are calculated. By using the equal and opposite of this thermal stress as the crack surface traction in the isothermal cylinder the crack problem is then solved and the stress intensity factor is calculated. The numerical results are obtained as a function of the Fourier number tD/b(2) representing the time for various inner-to-outer radius ratios and relative crack depths, where D and b are respectively the coefficient of diffusivity and the outer radius of the cylinder.

  17. Analisa Thermal Stress Pada Dinding Silinder Linier Engine Bersilinder Tunggal

    Directory of Open Access Journals (Sweden)

    Syaiful Wijayantara

    2014-03-01

    Full Text Available Pada penelitian ini akan dilakukan analisa thermal stress pada body cylinder liner dan cylinder head dari linier engine dua tak otto 30,55 CC dengan variasi jumlah kecepatan rata-rata piston engine 1.02 m/s , 4.07 m/s  , 4.58 m/s  beban penuh. Hal ini dilakukan karena proses scavenging tidak terjadi secara baik sehingga performa engine tidak pada kondisi optimalnya. Pada penelitian ini menggunakan software yang berbasis finite element untuk menganalisa distribusi panas dan thermal stress. Tahapan penelitian meliputi pemasukan gambar geometry sylinder liner dan cylinder head ke dalam software dan proses analisa distribusi panas dan thermal stress analisis .Luaran dari penelitian ini berupa gambar persebaran thermal expansion, gambar dari persebaran thermal stress analysis, dan grafik perbandingan antar distribusi panas yang terjadi ketika engine berada pada kecepatan rata-rata piston engine 1.02 m/s  , 4.07 m/s  , 4.58 m/s. Selain grafik perbandingan antar distribusi panas pada tiap percepatan, luaran dari penelitian ini juga menyangkut grafik temperature terendah pada masing-masing percepatan

  18. Viral and Bacterial Epibionts in Thermally-Stressed Corals

    OpenAIRE

    Hanh Nguyen-Kim; Thierry Bouvier; Corinne Bouvier; Van Ngoc Bui; Huong Le-Lan; Yvan Bettarel

    2015-01-01

    The periodic rise in seawater temperature is one of the main environmental determinants of coral bleaching. However, the direct incidence of these episodic thermal anomalies on coral-associated microbiota and their subsequent effects on coral health are still not completely understood. In this study, we investigated the dynamics of three main microbial communities of the coral holobiont (e.g., Symbiodinium, bacteria and viruses), during an experimental thermal stress (+4 °C) conducted on the ...

  19. Combined thermal and herbicide stress in functionally diverse coral symbionts

    International Nuclear Information System (INIS)

    Most reef building corals rely on symbiotic microalgae (genus Symbiodinium) to supply a substantial proportion of their energy requirements. Functional diversity of different Symbiodinium genotypes, endorsing the host with physiological advantages, has been widely reported. Yet, the influence of genotypic specificity on the symbiont's susceptibility to contaminants or cumulative stressors is unknown. Cultured Symbiodinium of presumed thermal-tolerant clade D tested especially vulnerable to the widespread herbicide diuron, suggesting important free-living populations may be at risk in areas subjected to terrestrial runoff. Co-exposure experiments where cultured Symbiodinium were exposed to diuron over a thermal stress gradient demonstrated how fast-growing clade C1 better maintained photosynthetic capability than clade D. The mixture toxicity model of Independent Action, considering combined thermal stress and herbicide contamination, revealed response additivity for inhibition of photosynthetic yield in both tested cultures, emphasizing the need to account for cumulative stressor impacts in ecological risk assessment and resource management. - Highlights: • Water quality influences thermal stress thresholds in different Symbiodinium types. • Photosystem of clade D tested more sensitive than C1 to a common herbicide. • Increased thermal tolerance quickly countered in presence of herbicide. • Mixture toxicity approach demonstrated response additivity for combined stressors. • Symbiotic partnership may be compromised in areas subjected to terrestrial runoff. - Thermal-tolerant Symbiodinium type D tested especially vulnerable to a common herbicide, emphasizing the significance of cumulative stressors in ecological risk management

  20. Food availability promotes rapid recovery from thermal stress in a scleractinian coral

    Science.gov (United States)

    Connolly, S. R.; Lopez-Yglesias, M. A.; Anthony, K. R. N.

    2012-12-01

    Bleaching in corals due to environmental stress represents a loss of energy intake often leading to an increase in mortality risk. Successful coral recovery from severe bleaching events may depend on the rate of replenishment of algal symbiont populations following the period of thermal stress, the supply of an alternative food source, or both. Here, we explore the role of food availability in promoting the survival and recovery of a common coral ( Acropora intermedia) following acute experimentally induced thermal stress. Fed corals were provided with live rotifers daily, to maintain densities of zooplankton in tanks that are typical of coral reefs. After a 6-week acclimation phase, heated corals were subjected to a +4 °C thermal anomaly for a 7-day period (bleaching phase) then temperatures were returned to normal for a further 2 weeks (recovery phase). Results demonstrated that heated corals had higher survival when they were provided with heterotrophic food. Fed corals experienced reduced loss of chlorophyll a, relative to unfed corals. During the recovery phase, both fed and unfed corals recovered within a few days; however, fed corals recovered to pre-bleaching phase levels of chlorophyll a, whereas unfed corals stabilized approximately one-third below this level. Protein levels of fed corals declined markedly during the bleaching phase, but recovered all of their losses by the end of the recovery phase. In contrast, unfed corals had low protein levels that were maintained throughout the experiment. To the extent that these results are representative of corals' responses to thermal anomalies in nature, the findings imply that availability of particulate food matter has the potential to increase corals' capacity to survive thermally induced bleaching and to ameliorate its sub-lethal effects. They also support the hypothesis that different rates of heterotrophy are an important determinant of variation in resilience to thermal stress among reef environments.

  1. Acute Restraint Stress Enhances Hippocampal Endocannabinoid Function via Glucocorticoid Receptor Activation

    OpenAIRE

    Wang, Meina; Hill, Matthew N.; Zhang, Longhua; Gorzalka, Boris B.; Hillard, Cecilia J.; Alger, Bradley E.

    2011-01-01

    Exposure to behavioral stress normally triggers a complex, multi-level response of the hypothalamic-pituitary-adrenal (HPA) axis that helps maintain homeostatic balance. Although the endocannabinoid (eCB) system (ECS) is sensitive to chronic stress, few studies have directly addressed its response to acute stress. Here we show that acute restraint stress enhances eCB-dependent modulation of GABA release measured by whole-cell voltage clamp of inhibitory post-synaptic currents (IPSCs) in rat h...

  2. On the effect of soil wetness on thermal stress

    Science.gov (United States)

    Ookouchi, Y.; Segal, M.; Pielke, R. A.; Mahrer, Y.

    1987-03-01

    A coupled atmosphere-soil model was applied in order to evaluate the impact of soil wetness on human stress in the absence of horizontal gradients in moisture. The results are illustrated and discussed with consideration to various combinations of wind speed and lower level atmospheric moisture during daylight hours with summer weather conditions. A thermal index composed of the air temperature and wet-bulb temperature does not show major changes as a function of variation of soil mosture. When wind speed and solar radiation are also considered, in a more detailed thermal index, relatively wet soil is associated with the optimal thermal comfort.

  3. Impairments of spatial working memory and attention following acute psychosocial stress.

    Science.gov (United States)

    Olver, James S; Pinney, Myra; Maruff, Paul; Norman, Trevor R

    2015-04-01

    Few studies have investigated the effect of an acute psychosocial stress paradigm on impaired attention and working memory in humans. Further, the duration of any stress-related cognitive impairment remains unclear. The aim of this study was to examine the effect of an acute psychosocial stress paradigm, the Trier Social Stress, on cognitive function in healthy volunteers. Twenty-three healthy male and female subjects were exposed to an acute psychosocial stress task. Physiological measures (salivary cortisol, heart rate and blood pressure) and subjective stress ratings were measured at baseline, in anticipation of stress, immediately post-stress and after a period of rest. A neuropsychological test battery including spatial working memory and verbal memory was administered at each time point. Acute psychosocial stress produced significant increases in cardiovascular and subjective measures in the anticipatory and post-stress period, which recovered to baseline after rest. Salivary cortisol steadily declined over the testing period. Acute psychosocial stress impaired delayed verbal recall, attention and spatial working memory. Attention remained impaired, and delayed verbal recall continued to decline after rest. Acute psychosocial stress is associated with an impairment of a broad range of cognitive functions in humans and with prolonged abnormalities in attention and memory.

  4. Thermal lensing and stress in Cr,Er:YSGG

    Science.gov (United States)

    Gollihar, William A.; Margo, Satrijo T.; DeShazer, Larry G.; Kennedy, Chandler J.

    1995-04-01

    Thermal and stress lensing effects have been measured in a Cr,Er:YSGG rod by observing a transmitted 1064 nm Nd:YAG beam diverging from an operating Cr,Er:YSGG laser. The results compare favorably with theory and estimated thermal-optic properties of YSGG, which is intermediate between YAG and GSGG. Numerical simulations of the laser agree substantially with the threshold and power observed and show a heat generation rate which is consistent with our observations of lensing. Thermal fracture of the rod has been observed on several occasions, leading to an estimate of the thermal fracture figure of merit which is also intermediate between YAG and GSGG. Back focal distances of less than 20 cm occur in the vicinity of half the thermal rupture limit.

  5. The measurement of thermal stress distributions along the flow path in injection-molded flat plates

    NARCIS (Netherlands)

    Hastenberg, C.H.V.; Wildervanck, P.C.; Leenen, A.J.H.; Schennink, G.G.J.

    1992-01-01

    Internal stresses in injection-molded parts are the result of thermal, flow, and pressure histories. Internal stresses can be roughly divided into thermal and flow-induced stresses. In this paper, a modified layer-removal method is presented to determine thermal stress distributions in injection-mol

  6. Detection and classification of stress using thermal imaging technique

    Science.gov (United States)

    Hong, Kan; Yuen, Peter; Chen, Tong; Tsitiridis, Aristeidis; Kam, Firmin; Jackman, James; James, David; Richardson, Mark; Oxford, William; Piper, Jonathan; Thomas, Francis; Lightman, Stafford

    2009-09-01

    This paper reports how Electro-Optics (EO) technologies such as thermal and hyperspectral [1-3] imaging methods can be used for the detection of stress remotely. Emotional or physical stresses induce a surge of adrenaline in the blood stream under the command of the sympathetic nerve system, which, cannot be suppressed by training. The onset of this alleviated level of adrenaline triggers a number of physiological chain reactions in the body, such as dilation of pupil and an increased feed of blood to muscles etc. The capture of physiological responses, specifically the increase of blood volume to pupil, have been reported by Pavlidis's pioneer thermal imaging work [4-7] who has shown a remarkable increase of skin temperature in the periorbital region at the onset of stress. Our data has shown that other areas such as the forehead, neck and cheek also exhibit alleviated skin temperatures dependent on the types of stressors. Our result has also observed very similar thermal patterns due to physical exercising, to the one that induced by other physical stressors, apparently in contradiction to Pavlidis's work [8]. Furthermore, we have found patches of alleviated temperature regions in the forehead forming patterns characteristic to the types of stressors, dependent on whether they are physical or emotional in origin. These stress induced thermal patterns have been seen to be quite distinct to the one resulting from having high fever.

  7. Temperature and thermal stresses in accelerator target plates

    International Nuclear Information System (INIS)

    Simple calculations of temperatures and elastic thermal stresses are given for a particular design of spallation neutron target plate in normal operation and in a quench process used in its manufacture. The main conclusion is that considerable plastic deformation will occur in both circumstances. (author)

  8. Acute Stress Symptoms in Children: Results From an International Data Archive

    Science.gov (United States)

    Kassam-Adams, Nancy; Palmieri, Patrick A.; Rork, Kristine; Delahanty, Douglas L.; Kenardy, Justin; Kohser, Kristen L.; Landolt, Markus A.; Le Brocque, Robyne; Marsac, Meghan L.; Meiser-Stedman, Richard; Nixon, Reginald D.V.; Bui, Eric; McGrath, Caitlin

    2012-01-01

    Objective: To describe the prevalence of acute stress disorder (ASD) symptoms and to examine proposed "DSM-5" symptom criteria in relation to concurrent functional impairment in children and adolescents. Method: From an international archive, datasets were identified that included assessment of acute traumatic stress reactions and concurrent…

  9. Predictors of acute stress disorder in response to bank robbery

    Directory of Open Access Journals (Sweden)

    Maj Hansen

    2011-05-01

    Full Text Available Background : Research has shown that robberies in the workplace, in particular those in the bank sector are traumatising events for many employees. However, research in the acute sequelae of bank robberies is limited. Objective and design : The present study explores the prevalence and predictors of acute stress disorder (ASD in a questionnaire survey of bank employees following a bank robbery. Results : Results show that 14.5% (n=22 of participants (N=152 suffered from probable ASD, which is similar to the ASD prevalence found in other interpersonal assault studies. In addition, a number of associations were found between ASD severity, gender, age, social support, previous trauma, and trauma severity. In the final hierarchical multiple regression model, which included 12 variables, 66% of the variance in ASD symptom level was accounted for by two peri-trauma variables (perceived helplessness and perceived life threat and one post-trauma variable (perceived safety after the robbery. Conclusions : The present study yielded some promising results with regards to the influential role of peri-traumatic and post-traumatic variables in predicting ASD after a bank robbery—in particular perceived safety. Although there may be different paths to developing ASD and PTSD, a common core feature may be perceived safety. Furthermore, the results also supported the inclusion of perceived helplessness in the A2 criterion of the DSM-IV ASD diagnosis.For the abstract or full text in other languages, please see Supplementary files under Reading Tools online

  10. Acute short-term mental stress does not influence salivary flow rate dynamics.

    Directory of Open Access Journals (Sweden)

    Ella A Naumova

    Full Text Available BACKGROUND: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. METHODS: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI data were obtained. The subjects were divided into stress subgroup (S1 (psychological reactivity, stress subgroup (S2 (psychological and physiological reactivity and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. RESULTS: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. CONCLUSIONS: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine

  11. Thermal Stress Behavior of Aluminum Nanofilms under Heat Cycling

    International Nuclear Information System (INIS)

    In-situ thermal stress in aluminum nanofilms with silicon oxide glass (SOG) passivation was investigated by using synchrotron radiation at the SPring-8. Aluminum films of varying thickness (10, 20, 50 nm) were deposited on thermally oxidized silicon wafers by RF magnetron sputtering. Each specimen was heated in air over two cycles between room temperature and 300 deg. C. The following results were obtained: (1) {111} planes of aluminum nanofilm crystals were oriented parallel to the substrate normal; (2) the intensity of 111 diffraction was almost independent of temperature except in the case of the 50-nm-thick film; (3) the FWHM of 111 diffraction was almost independent of temperature at any given film thickness; and (4) for all films, the thermal stress varied linearly with heating temperature, and the hysteresis between the heating and cooling steps disappeared

  12. The relationship between bioclimatic thermal stress and subjective thermal sensation in pedestrian spaces

    Science.gov (United States)

    Pearlmutter, David; Jiao, Dixin; Garb, Yaakov

    2014-12-01

    Outdoor thermal comfort has important implications for urban planning and energy consumption in the built environment. To better understand the relation of subjective thermal experience to bioclimatic thermal stress in such contexts, this study compares micrometeorological and perceptual data from urban spaces in the hot-arid Negev region of Israel. Pedestrians reported on their thermal sensation in these spaces, whereas radiation and convection-related data were used to compute the Index of Thermal Stress (ITS) and physiologically equivalent temperature (PET). The former is a straightforward characterization of energy exchanges between the human body and its surroundings, without any conversion to an "equivalent temperature." Although the relation of ITS to subjective thermal sensation has been analyzed in the past under controlled indoor conditions, this paper offers the first analysis of this relation in an outdoor setting. ITS alone can account for nearly 60 % of the variance in pedestrians' thermal sensation under outdoor conditions, somewhat more than PET. A series of regressions with individual contextual variables and ITS identified those factors which accounted for additional variance in thermal sensation, whereas multivariate analyses indicated the considerable predictive power ( R-square = 0.74) of models including multiple contextual variables in addition to ITS. Our findings indicate that pedestrians experiencing variable outdoor conditions have a greater tolerance for incremental changes in thermal stress than has been shown previously under controlled indoor conditions, with a tapering of responses at high values of ITS. However, the thresholds of ITS corresponding to thermal "neutrality" and thermal "acceptability" are quite consistent regardless of context.

  13. Acute stress disorder in hospitalised victims of 26/11-terror attack on Mumbai, India.

    Science.gov (United States)

    Balasinorwala, Vanshree Patil; Shah, Nilesh

    2010-11-01

    The 26/11 terror attacks on Mumbai have been internationally denounced. Acute stress disorder is common in victims of terror. To find out the prevalence and to correlate acute stress disorder, 70 hospitalised victims of terror were assessed for presence of the same using DSM-IV TR criteria. Demographic data and clinical variables were also collected. Acute stress disorder was found in 30% patients. On demographic profile and severity of injury, there were some interesting observations and differences between the victims who developed acute stress disorder and those who did not; though none of the differences reached the level of statistical significance. This study documents the occurrence of acute stress disorder in the victims of 26/11 terror attack.

  14. Attenuation of Acute and Chronic Restraint Stress-induced Perturbations in Experimental Animals by Nelumbo nucifera Gaertn

    OpenAIRE

    Kulkarni, M. P.; Juvekar, A. R.

    2008-01-01

    Aqueous extract of leaves of Nelumbo nucifera was investigated on acute stress (immobilization stress)-induced biochemical alterations in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) and acute chemical stress (writhing test) to gauge the antistress potential of the extract. Further to evaluate the antistress activity of Nelumbo nucifera in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4° for 1 h) for 7 da...

  15. Attenuation of acute and chronic restraint stress-induced perturbations in experimental animals by Nelumbo nucifera Gaertn

    OpenAIRE

    Kulkarni M; Juvekar A

    2008-01-01

    Aqueous extract of leaves of Nelumbo nucifera was investigated on acute stress (immobilization stress)-induced biochemical alterations in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) and acute chemical stress (writhing test) to gauge the antistress potential of the extract. Further to evaluate the antistress activity of Nelumbo nucifera in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4° for 1 h) f...

  16. TNF-α from hippocampal microglia induces working memory deficits by acute stress in mice.

    Science.gov (United States)

    Ohgidani, Masahiro; Kato, Takahiro A; Sagata, Noriaki; Hayakawa, Kohei; Shimokawa, Norihiro; Sato-Kasai, Mina; Kanba, Shigenobu

    2016-07-01

    The role of microglia in stress responses has recently been highlighted, yet the underlying mechanisms of action remain unresolved. The present study examined disruption in working memory due to acute stress using the water-immersion resistant stress (WIRS) test in mice. Mice were subjected to acute WIRS, and biochemical, immunohistochemical, and behavioral assessments were conducted. Spontaneous alternations (working memory) significantly decreased after exposure to acute WIRS for 2h. We employed a 3D morphological analysis and site- and microglia-specific gene analysis techniques to detect microglial activity. Morphological changes in hippocampal microglia were not observed after acute stress, even when assessing ramification ratios and cell somata volumes. Interestingly, hippocampal tumor necrosis factor (TNF)-α levels were significantly elevated after acute stress, and acute stress-induced TNF-α was produced by hippocampal-ramified microglia. Conversely, plasma concentrations of TNF-α were not elevated after acute stress. Etanercept (TNF-α inhibitor) recovered working memory deficits in accordance with hippocampal TNF-α reductions. Overall, results suggest that TNF-α from hippocampal microglia is a key contributor to early-stage stress-to-mental responses. PMID:26551431

  17. Acute Psychosocial Stress and Emotion Regulation Skills Modulate Empathic Reactions to Pain in Others

    OpenAIRE

    Gabriele eBuruck; Johannes eWendsche; Marlen eMelzer; Alexander eStrobel; Denise eDörfel

    2014-01-01

    Psychosocial stress affects resources for adequate coping with environmental demands. A crucial question in this context is the extent to which acute psychosocial stressors impact empathy and emotion regulation. In the present study, 120 participants were randomly assigned to a control group vs. a group confronted with the Trier Social Stress Test, an established paradigm for the induction of acute psychosocial stress. Empathy for pain as a specific subgroup of empathy was assessed via pain i...

  18. Acute psychosocial stress and emotion regulation skills modulate empathic reactions to pain in others

    OpenAIRE

    Buruck, Gabriele; Wendsche, Johannes; Melzer, Marlen; Strobel, Alexander; Dörfel, Denise

    2014-01-01

    Psychosocial stress affects resources for adequate coping with environmental demands. A crucial question in this context is the extent to which acute psychosocial stressors impact empathy and emotion regulation. In the present study, 120 participants were randomly assigned to a control group vs. a group confronted with the Trier Social Stress Test (TSST), an established paradigm for the induction of acute psychosocial stress. Empathy for pain as a specific subgroup of empathy was assessed via...

  19. Development of structural response diagram approach to evaluation of thermal stress caused by thermal striping

    Energy Technology Data Exchange (ETDEWEB)

    Kasahara, Naoto; Yacumpai, Apisara [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Takasho, Hideki

    1999-02-01

    At incomplete mixing area of high temperature and low temperature fluids near the surface of structures, temperature fluctuation of fluid gives thermal fatigue damage to wall structures. This thermohydraulic and thermomechanical coupled phenomenon is called thermal striping, which has so complex mechanism and sometimes causes crack initiation on the structural surfaces that rational evaluation methods are required for screening rules in design codes. In this study, frequency response characteristics of structures and its mechanism were investigated by both numerical and theoretical methods. Based on above investigation, a structural response diagram was derived, which can predict stress amplitude of structures from temperature amplitude and frequency of fluids. Furthermore, this diagram was generalized to be the Non-dimensional structural response diagram by introducing non-dimensional parameters such as Biot number, non-dimensional frequency, and non-dimensional stress. The use of the Non-dimensional structural response diagram appears to evaluate thermal stress caused by thermal striping, rapidly without structural analysis, and rationally with considering attenuation by non-stationary heat transfer and thermal unloading. This diagram can also give such useful information as sensitive frequency range to adjust coupled thermohydraulic and thermomechanical analysis models taking account of four kinds of attenuation factors: turbulent mixing, molecular diffusion, non-stationary heat transfer, and thermal unloading. (author)

  20. Effect of interfacial thermal barrier on the thermal stresses near spherical inclusion in matrix subjected to linear heat flow

    Energy Technology Data Exchange (ETDEWEB)

    Osiroff, R.; Hasselman, D.P.H. (Virginia Polytechnic Institute and State University, Blacksburg (United States))

    1991-12-01

    The thermal stresses in the vicinity of a spherical inclusion within a matrix with different thermal and mechanical properties are analyzed for the condition of linear heat flow and the presence of an interfacial thermal barrier. A numerical example indicates that the existence of such a thermal barrier can have a significant effect on both the magnitude as well as sign of the thermal stresses as the result of disturbance of the temperature distribution due to the inclusion. For the case of perfect thermal contact, the results correspond to those obtained by Tauchert. It is also shown that the presence of an interfacial thermal barrier introduces an inclusion size effect on the magnitude of the thermal stresses, in addition to the direct linear dependence of the stresses on inclusion size, regardless of the existence of a thermal barrier. 6 refs.

  1. Thermal stress, human performance, and physical employment standards.

    Science.gov (United States)

    Cheung, Stephen S; Lee, Jason K W; Oksa, Juha

    2016-06-01

    Many physically demanding occupations in both developed and developing economies involve exposure to extreme thermal environments that can affect work capacity and ultimately health. Thermal extremes may be present in either an outdoor or an indoor work environment, and can be due to a combination of the natural or artificial ambient environment, the rate of metabolic heat generation from physical work, processes specific to the workplace (e.g., steel manufacturing), or through the requirement for protective clothing impairing heat dissipation. Together, thermal exposure can elicit acute impairment of work capacity and also chronic effects on health, greatly contributing to worker health risk and reduced productivity. Surprisingly, in most occupations even in developed economies, there are rarely any standards regarding enforced heat or cold safety for workers. Furthermore, specific physical employment standards or accommodations for thermal stressors are rare, with workers commonly tested under near-perfect conditions. This review surveys the major occupational impact of thermal extremes and existing employment standards, proposing guidelines for improvement and areas for future research. PMID:27277564

  2. Review of VA/DOD Clinical Practice Guideline on management of acute stress and interventions to prevent posttraumatic stress disorder

    Directory of Open Access Journals (Sweden)

    William P. Nash, MD

    2012-06-01

    Full Text Available This article summarizes the recommendations of the Department of Veterans Affairs (VA/Department of Defense (DOD VA/DOD Clinical Practice Guideline for Management of Post-Traumatic Stress that pertain to acute stress and the prevention of posttraumatic stress disorder, including screening and early interventions for acute stress states in various settings. Recommended interventions during the first 4 days after a potentially traumatic event include attending to safety and basic needs and providing access to physical, emotional, and social resources. Psychological first aid is recommended for management of acute stress, while psychological debriefing is discouraged. Further medical and psychiatric assessment and provision of brief, trauma-focused cognitive-behavioral therapy are warranted if clinically significant distress or functional impairment persists or worsens after 2 days or if the criteria for a diagnosis of acute stress disorder are met. Follow-up monitoring and rescreening are endorsed for at least 6 months for everyone who experiences significant acute posttraumatic stress. Four interventions that illustrate early intervention principles contained in the VA/DOD Clinical Practice Guideline are described.

  3. ANALYSIS OF TRANSIENT THERMAL STRESS IN CYLINDRICALLY ORTHOTROPIC TUBES

    Institute of Scientific and Technical Information of China (English)

    凌道盛

    2003-01-01

    The incorrect deduction of equations in the research works devoted to the studies of transient stress in cylindrically orthotropic tubes and done by Kardomateas ( Journal of Applied Mechanics, 1989, 1990) leads to the wrong results. The errata (1991) correct the deduction error, but do not give the right numerical results. All errors are corrected, and the Mathematica is adopted to solve the large argument problem for Bessel function. A theoretical solution of the transient thermal stresses in tubes with uniform form is presented,and a numerical example is studied.

  4. Coefficient of thermal expansion of stressed thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-dao; JIANG Shao-qing

    2006-01-01

    A new technique was proposed to determine the coefficient of thermal expansion (CTE) of thin films at low temperature. Different pre-stress could be applied and the elastic modulus of materials at different temperatures was measured with CTE simultaneously to eliminate the influence of mechanical deformation caused by the pre-stress. By using this technique,the CTEs of polyimide/silica nanocomposite films with different silica doping levels were experimentally studied at temperature from 77 K to 287 K,and some characteristics related to this new technique were discussed.

  5. Bond strength, bond stress and spallation mechanisms of thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Krishnakumar, V.; McCarron, K.; Barber, B.; Sohn, Y.-H. [Connecticut Univ., Storrs, CT (United States). Dept. of Metall. and Mater. Eng.; Eric, J. [Connecticut Univ., Storrs, CT (United States). Dept. of Mechanical Engineering; Tolpygo, V.K.

    1999-11-01

    Five production thermal barrier coatings were thermally cycled between room temperature and 1121 C (2050 F) to determine relative spallation life. Bond strength measurements were made using a modified ASTM direct pull-test. Bond stress measurements were made in the thermally grown oxide using a laser photoluminescence technique. Bond strength and bond stress measurements were conducted on two electron beam physical vapor deposition coatings as a function of thermal cycling. Each coating showed characteristic values of as-coated strength and stress and changes in strength and stress with thermal cycling. These variations in strength and stress with thermal cycling are related to oxidation and micro-debonding effects. (orig.)

  6. Bond strength, bond stress and spallation mechanisms of thermal barrier coatings

    International Nuclear Information System (INIS)

    Five production thermal barrier coatings were thermally cycled between room temperature and 1121 C (2050 F) to determine relative spallation life. Bond strength measurements were made using a modified ASTM direct pull-test. Bond stress measurements were made in the thermally grown oxide using a laser photoluminescence technique. Bond strength and bond stress measurements were conducted on two electron beam physical vapor deposition coatings as a function of thermal cycling. Each coating showed characteristic values of as-coated strength and stress and changes in strength and stress with thermal cycling. These variations in strength and stress with thermal cycling are related to oxidation and micro-debonding effects. (orig.)

  7. Entrainment of the mouse circadian clock by sub-acute physical and psychological stress.

    Science.gov (United States)

    Tahara, Yu; Shiraishi, Takuya; Kikuchi, Yosuke; Haraguchi, Atsushi; Kuriki, Daisuke; Sasaki, Hiroyuki; Motohashi, Hiroaki; Sakai, Tomoko; Shibata, Shigenobu

    2015-01-01

    The effects of acute stress on the peripheral circadian system are not well understood in vivo. Here, we show that sub-acute stress caused by restraint or social defeat potently altered clock gene expression in the peripheral tissues of mice. In these peripheral tissues, as well as the hippocampus and cortex, stressful stimuli induced time-of-day-dependent phase-advances or -delays in rhythmic clock gene expression patterns; however, such changes were not observed in the suprachiasmatic nucleus, i.e. the central circadian clock. Moreover, several days of stress exposure at the beginning of the light period abolished circadian oscillations and caused internal desynchronisation of peripheral clocks. Stress-induced changes in circadian rhythmicity showed habituation and disappeared with long-term exposure to repeated stress. These findings suggest that sub-acute physical/psychological stress potently entrains peripheral clocks and causes transient dysregulation of circadian clocks in vivo.

  8. Reduction of thermal stresses in continuous fiber reinforced metal matrix composites with interface layers

    Science.gov (United States)

    Jansson, S.; Leckie, F. A.

    1992-01-01

    The potential of using interface layer to reduce thermal stresses in the matrix of composites with a mismatch in coefficients of thermal expansion of fiber and matrix has been investigated. It was found that compliant layers, with properties of readily available materials, do not have the potential to reduce thermal stresses significantly. However, interface layers with high coefficient of thermal expansion can compensate for the mismatch and reduce thermal stresses in the matrix significantly.

  9. Prolonged Effects of Acute Stress on Decision-Making under Risk: A Human Psychophysiological Study

    Science.gov (United States)

    Yamakawa, Kaori; Ohira, Hideki; Matsunaga, Masahiro; Isowa, Tokiko

    2016-01-01

    This study investigates the prolonged effects of physiological responses induced by acute stress on risk-taking in decision-making. Participants were divided into a Stress group (N = 14) and a Control group (N = 12). The Trier Social Stress Test was administered as an acute stressor, and reading was administered as a control task; thereafter, participants performed a decision-making task in which they needed to choose a sure option or a gamble option in Gain and Loss frame trials 2 h after (non-) exposure to the stressor. Increased cortisol, adrenaline, heart rate (HR), and subjective stress levels validated acute stress manipulation. Stressed participants made fewer risky choices only in the Gain domain, whereas no effect of stress was shown in the Loss domain. Deceleration of HR reflecting attention was greater for Gains compared with Losses only in the Stress group. Risk avoidance was determined by increased levels of cortisol caused by acute stress. These results suggest that processes regarding glucocorticoid might be involved in the prolonged effects of acute stress on the evaluation of risks and the monitoring of outcomes in decision-making.

  10. Simulasi Thermal Stress Pada Tube Superheater Package Boiler

    OpenAIRE

    Hamdani

    2013-01-01

    This project investigates the thermal stress behavior and the mechanisms of superheater tube failure with experimental method and numerical analysis. First of all the procedures for failure analysis were applied to determine the root cause of them. A visual assessment of boiler critical pressure parts was carried out, and then the failed tube is examined by nondestructive evaluation. For the numerical domain, initially the elastic solution for a superheater tube subjected to an internal press...

  11. Calculation of thermal stresses in glass-ceramic composites

    OpenAIRE

    Ganghoffer, Jean-François

    2015-01-01

    Opto-electronics make intensive use of composite materials based on amorphous materials, which can be considered as smart materials since they are capable of high performances in their final state. Particularly, glass-ceramic composites involved in welding operations for microelectronics applications are subjected to important thermal stresses during their production, which can deteriorate their properties at room temperature, until the failure stage is reached. It is then essential to be abl...

  12. Influence of thermal stress on marginal integrity of restorative materials

    Directory of Open Access Journals (Sweden)

    Maximiliano Sérgio Cenci

    2008-04-01

    Full Text Available The aim of this study was to evaluate the influence of thermal stress on the marginal integrity of restorative materials with different adhesive and thermal properties. Three hundred and sixty Class V cavities were prepared in buccal and lingual surfaces of 180 bovine incisors. Cervical and incisal walls were located in dentin and enamel, respectively. Specimens were restored with resin composite (RC; glass ionomer (GI or amalgam (AM, and randomly assigned to 18 groups (n=20 according to the material, number of cycles (500 or 1,000 cycles and dwell time (30 s or 60 s. Dry and wet specimens served as controls Specimens were immersed in 1% basic fuchsine solution (24 h, sectioned, and microleakage was evaluated under x40 magnification. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests: Thermal cycling regimens increased leakage in all AM restorations (p<0.05 and its effect on RC and GI restorations was only significant when a 60-s dwell time was used (p<0.05. Marginal integrity was more affected in AM restorations under thermal cycling stress, whereas RC and GI ionomer restoration margins were only significantly affected only under longer dwell times.

  13. Cognitive Load Undermines Thought Suppression in Acute Stress Disorder.

    Science.gov (United States)

    Nixon, Reginald D V; Rackebrandt, Julie

    2016-05-01

    Thought suppression studies demonstrate that attempts to suppress can be undermined by cognitive load. We report the first instance in which this has been tested experimentally in a sample of recently traumatized individuals. Individuals with and without acute stress disorder (ASD) were recruited following recent trauma and randomized to load or no load conditions (N=56). They monitored intrusive memories during baseline, suppression, and think anything phases. The impact of suppression and load on self-reported intrusions, attention bias (dot-probe), and memory priming (word-stem task) was assessed. The ASD load group were less able to suppress memories (d=0.32, CI95 [-0.15, 0.83], p=.088) than the ASD no load group (d=0.63, CI95 [0.08, 1.24], panything phase, the ASD load group reported more intrusions than the ASD no load or non-ASD groups (with and without load). No consistent findings were observed in relation to attentional bias. ASD load individuals exhibited stronger priming responses for motor vehicle accident and assault words than all other groups (ds between 0.35-0.73). Working memory did not moderate any outcomes of interest. The findings indicate that cognitive load interferes with suppression and may enhance access to trauma memories and associated material. The study extends previous research by demonstrating these effects for the first time in a clinical sample of recent survivors of trauma. PMID:27157032

  14. Differential expression of heat shock transcription factors and heat shock proteins after acute and chronic heat stress in laying chickens (Gallus gallus.

    Directory of Open Access Journals (Sweden)

    Jingjing Xie

    Full Text Available Heat stress due to high environmental temperature negatively influences animal performances. To better understand the biological impact of heat stress, laying broiler breeder chickens were subjected either to acute (step-wisely increasing temperature from 21 to 35°C within 24 hours or chronic (32°C for 8 weeks high temperature exposure. High temperature challenges significantly elevated body temperature of experimental birds (P<0.05. However, oxidation status of lipid and protein and expression of heat shock transcription factors (HSFs and heat shock proteins (HSPs 70 and 90 were differently affected by acute and chronic treatment. Tissue-specific responses to thermal challenge were also found among heart, liver and muscle. In the heart, acute heat challenge affected lipid oxidation (P = 0.05 and gene expression of all 4 HSF gene expression was upregulated (P<0.05. During chronic heat treatment, the HSP 70 mRNA level was increased (P<0.05 and HSP 90 mRNA (P<0.05 was decreased. In the liver, oxidation of protein was alleviated during acute heat challenge (P<0.05, however, gene expression HSF2, 3 and 4 and HSP 70 were highly induced (P<0.05. HSP90 expression was increased by chronic thermal treatment (P<0.05. In the muscle, both types of heat stress increased protein oxidation, but HSFs and HSPs gene expression remained unaltered. Only tendencies to increase were observed in HSP 70 (P = 0.052 and 90 (P = 0.054 gene expression after acute heat stress. The differential expressions of HSF and HSP genes in different tissues of laying broiler breeder chickens suggested that anti-heat stress mechanisms might be provoked more profoundly in the heart, by which the muscle was least protected during heat stress. In addition to HSP, HSFs gene expression could be used as a marker during acute heat stress.

  15. Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze.

    Science.gov (United States)

    van Gerven, Dustin J H; Ferguson, Thomas; Skelton, Ronald W

    2016-07-01

    Stress and stress hormones are known to influence the function of the hippocampus, a brain structure critical for cognitive-map-based, allocentric spatial navigation. The caudate nucleus, a brain structure critical for stimulus-response-based, egocentric navigation, is not as sensitive to stress. Evidence for this comes from rodent studies, which show that acute stress or stress hormones impair allocentric, but not egocentric navigation. However, there have been few studies investigating the effect of acute stress on human spatial navigation, and the results of these have been equivocal. To date, no study has investigated whether acute stress can shift human navigational strategy selection between allocentric and egocentric navigation. The present study investigated this question by exposing participants to an acute psychological stressor (the Paced Auditory Serial Addition Task, PASAT), before testing navigational strategy selection in the Dual-Strategy Maze, a modified virtual Morris water maze. In the Dual-Strategy maze, participants can chose to navigate using a constellation of extra-maze cues (allocentrically) or using a single cue proximal to the goal platform (egocentrically). Surprisingly, PASAT stress biased participants to solve the maze allocentrically significantly more, rather than less, often. These findings have implications for understanding the effects of acute stress on cognitive function in general, and the function of the hippocampus in particular. PMID:27174311

  16. Effect of estrogen on plasma ceruloplasmin level in rats exposed to acute stress

    Directory of Open Access Journals (Sweden)

    Ganaraja B

    2004-04-01

    Full Text Available BACKGROUND: Plasma ceruloplasmin, a copper containing protein, belongs to a class called acute phase proteins. Reduced level of ceruloplasmin was associated with Wilson′s disease and Menke′s kinky hair disease in man, primarily affecting copper metabolism. Stress was known to increase Ceruloplasmin. Several stress associated changes were commonly observed in women at menopause and also those who underwent overiectomy. Present experiment investigated the effect of estrogen on ceruloplasmin level in acute stress. AIMS: To assess the estradiol induced changes in plasma ceruloplasmin concentration on exposure of the rats to acute stress. SETTINGS AND DESIGN: Acute stress was induced by forcing the rats to swim till exhaustion. The rats were overiectomised bilaterally to remove the primary source of sex hormones. And hormone replacement was done later. MATERIAL AND METHODS: Wistar albino female rats were used. Acute stress was induced before overiectomy, following recovery from surgery, and again after Estradiol Valerate injection (for 10 days in same group of rats. The plasma ceruloplasmin was estimated immediately after stress during each stage - that is preoperative control, stressed control, after overiectomy and then following treatment with Estradiol Valerate. STATISTICAL ANALYSIS USED: Paired sample T test was applied to analyze the findings. Results: We found lowest ceruloplasmin level after stress in overiectomised animals, while on substitution of estradiol the trend appeared to be reversed. CONCLUSION: The result suggested a direct effect of estrogen on hepatic ceruloplasmin production/release and this could account for some of the beneficial effects of hormone replacement therapy.

  17. Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze.

    Science.gov (United States)

    van Gerven, Dustin J H; Ferguson, Thomas; Skelton, Ronald W

    2016-07-01

    Stress and stress hormones are known to influence the function of the hippocampus, a brain structure critical for cognitive-map-based, allocentric spatial navigation. The caudate nucleus, a brain structure critical for stimulus-response-based, egocentric navigation, is not as sensitive to stress. Evidence for this comes from rodent studies, which show that acute stress or stress hormones impair allocentric, but not egocentric navigation. However, there have been few studies investigating the effect of acute stress on human spatial navigation, and the results of these have been equivocal. To date, no study has investigated whether acute stress can shift human navigational strategy selection between allocentric and egocentric navigation. The present study investigated this question by exposing participants to an acute psychological stressor (the Paced Auditory Serial Addition Task, PASAT), before testing navigational strategy selection in the Dual-Strategy Maze, a modified virtual Morris water maze. In the Dual-Strategy maze, participants can chose to navigate using a constellation of extra-maze cues (allocentrically) or using a single cue proximal to the goal platform (egocentrically). Surprisingly, PASAT stress biased participants to solve the maze allocentrically significantly more, rather than less, often. These findings have implications for understanding the effects of acute stress on cognitive function in general, and the function of the hippocampus in particular.

  18. Transition from stress-driven to thermally activated stress relaxation in metallic glasses

    Science.gov (United States)

    Qiao, J. C.; Wang, Yun-Jiang; Zhao, L. Z.; Dai, L. H.; Crespo, D.; Pelletier, J. M.; Keer, L. M.; Yao, Y.

    2016-09-01

    The short-range ordered but long-range disordered structure of metallic glasses yields strong structural and dynamic heterogeneities. Stress relaxation is a technique to trace the evolution of stress in response to a fixed strain, which reflects the dynamic features phenomenologically described by the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation describes a broad distribution of relaxation times with a small number of empirical parameters, but it does not arise from a particular physically motivated mechanistic picture. Here we report an anomalous two-stage stress relaxation behavior in a Cu46Zr46Al8 metallic glass over a wide temperature range and generalize the findings in other compositions. Thermodynamic analysis identifies two categories of processes: a fast stress-driven event with large activation volume and a slow thermally activated event with small activation volume, which synthetically dominates the stress relaxation dynamics. Discrete analyses rationalize the transition mechanism induced by stress and explain the anomalous variation of the KWW characteristic time with temperature. Atomistic simulations reveal that the stress-driven event involves virtually instantaneous short-range atomic rearrangement, while the thermally activated event is the percolation of the fast event accommodated by the long-range atomic diffusion. The insights may clarify the underlying physical mechanisms behind the phenomenological description and shed light on correlating the hierarchical dynamics and structural heterogeneity of amorphous solids.

  19. Histamine is not released in acute thermal injury in human skin in vivo: a microdialysis study

    DEFF Research Database (Denmark)

    Petersen, Lars Jelstrup; Pedersen, Juri Lindy; Skov, Per Stahl;

    2009-01-01

    BACKGROUND: Animal models have shown histamine to be released from the skin during the acute phase of a burn injury. The role of histamine during the early phase of thermal injuries in humans remains unclear. PURPOSE: The objectives of this trial were to study histamine release in human skin during.......6 +/- 1.8 nM vs. post-burn values of 14.8 +/- 1.8 nM, n = 8). CONCLUSIONS: Histamine is not released in human skin during the acute phase of a thermal injury....... the acute phase of a standardized thermal injury in healthy volunteers. METHODS: Histamine concentrations in human skin were measured by skin microdialysis technique. Microdialysis fibers were inserted into the dermis in the lower leg in male healthy volunteers. A standardized superficial thermal injury...

  20. Acute Immobilization Stress Modulate GABA Release from Rat Olfactory Bulb: Involvement of Endocannabinoids—Cannabinoids and Acute Stress Modulate GABA Release

    OpenAIRE

    Alejandra Delgado; Erica H. Jaffé

    2011-01-01

    We studied the effects of cannabinoids and acute immobilization stress on the regulation of GABA release in the olfactory bulb. Glutamate-stimulated 3H-GABA release was measured in superfused slices. We report that cannabinoids as WIN55, 212-2, methanandamide, and 2-arachidonoylglycerol were able to inhibit glutamate- and KCl-stimulated 3H-GABA release. This effect was blocked by the CB1 antagonist AM281. On the other hand, acute stress was able per se to increase endocannabinoid activity. Th...

  1. Effects of displacement boundary conditions on thermal deformation in thermal stress problems

    Directory of Open Access Journals (Sweden)

    S. Y. Kwak

    2013-05-01

    Full Text Available Most computational structural engineers are paying more attention to applying loads rather than to DBCs (Displacement Boundary Conditions because most static stable mechanical structures are working under already prescribed displacement boundary conditions. In all of the computational analysis of solving a system of algebraic equations, such as FEM (Finite Element Method, three translational and three rotational degrees of freedom (DOF should be constrained (by applying DBCs before solving the system of algebraic equation in order to prevent rigid body motions of the analysis results (singular problem. However, it is very difficult for an inexperienced engineer or designer to apply proper DBCs in the case of thermal stress analysis where no prescribed DBCs or constraints exist, for example in water quenching for heat treatment. Moreover, improper DBCs cause incorrect solutions in thermal stress analysis, such as stress concentration or unreasonable deformation phases. To avoid these problems, we studied a technique which performs the thermal stress analysis without any DBCs; and then removes rigid body motions from the deformation results in a post process step as the need arises. The proposed technique makes it easy to apply DBCs and prevent the error caused by improper DBCs. We proved it was mathematically possible to solve a system of algebraic equations without a step of applying DBCs. We also compared the analysis results with those of a traditional procedure for real castings.

  2. Thermal imaging to detect physiological indicators of stress in humans

    Science.gov (United States)

    Cross, Carl B.; Skipper, Julie A.; Petkie, Douglas T.

    2013-05-01

    Real-time, stand-off sensing of human subjects to detect emotional state would be valuable in many defense, security and medical scenarios. We are developing a multimodal sensor platform that incorporates high-resolution electro-optical and mid-wave infrared (MWIR) cameras and a millimeter-wave radar system to identify individuals who are psychologically stressed. Recent experiments have aimed to: 1) assess responses to physical versus psychological stressors; 2) examine the impact of topical skin products on thermal signatures; and 3) evaluate the fidelity of vital signs extracted from thermal imagery and radar signatures. Registered image and sensor data were collected as subjects (n=32) performed mental and physical tasks. In each image, the face was segmented into 29 non-overlapping segments based on fiducial points automatically output by our facial feature tracker. Image features were defined that facilitated discrimination between psychological and physical stress states. To test the ability to intentionally mask thermal responses indicative of anxiety or fear, subjects applied one of four topical skin products to one half of their face before performing tasks. Finally, we evaluated the performance of two non-contact techniques to detect respiration and heart rate: chest displacement extracted from the radar signal and temperature fluctuations at the nose tip and regions near superficial arteries to detect respiration and heart rates, respectively, extracted from the MWIR imagery. Our results are very satisfactory: classification of physical versus psychological stressors is repeatedly greater than 90%, thermal masking was almost always ineffective, and accurate heart and respiration rates are detectable in both thermal and radar signatures.

  3. The influence of acute stress on the regulation of conditioned fear

    OpenAIRE

    Raio, Candace M.; Phelps, Elizabeth A.

    2014-01-01

    Fear learning and regulation is a prominent model for describing the pathogenesis of anxiety disorders and stress-related psychopathology. Fear expression can be modulated using a number of regulatory strategies, including extinction, cognitive emotion regulation, avoidance strategies and reconsolidation. In this review, we examine research investigating the effects of acute stress and stress hormones on these regulatory techniques. We focus on what is known about the impact of stress on the ...

  4. Effects of acute stress on learning and memory processes of malnourished rats

    OpenAIRE

    Lucas Duarte Ferreira Manhas dos Vales; Marisa Tomoe Hebihara Fukuda; Sebastião de Sousa Almeida

    2014-01-01

    The aim of the study was to investigate the effects of acute stress on the processes of learning and memory in malnourished rats tested in the Morris water maze. The animals were divided into eight groups according to nutritional status (malnourished or well nourished) and stress (stressed or unstressed). In Experiment I the animals were subjected to immobilization stress procedure before the learning session and in Experiment II after the learning sessions. The test consisted of two daily se...

  5. Chronic and acute effects of stress on energy balance: are there appropriate animal models?

    OpenAIRE

    Harris, Ruth B. S.

    2014-01-01

    Stress activates multiple neural and endocrine systems to allow an animal to respond to and survive in a threatening environment. The corticotropin-releasing factor system is a primary initiator of this integrated response, which includes activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. The energetic response to acute stress is determined by the nature and severity of the stressor, but a typical response to an acute stressor is inhibition of food...

  6. Virtual Mold Technique in Thermal Stress Analysis during Casting Process

    Institute of Scientific and Technical Information of China (English)

    Si-Young Kwak; Jae-Wook Baek; Jeong-Ho Nam; Jeong-Kil Choi

    2008-01-01

    It is important to analyse the casting product and the mold at the same time considering thermal contraction of the casting and thermal expansion of the mold. The analysis considering contact of the casting and the mold induces the precise prediction of stress distribution and the defect such as hot tearing. But it is difficult to generate FEM mesh for the interface of the casting and the mold. Moreover the mesh for the mold domain spends lots of computational time and memory for the analysis due to a number of meshes. Consequently we proposed the virtual mold technique which only uses mesh of the casting part for thermal stress analysis in casting process. The spring bar element in virtual mold technique is used to consider the contact of the casting and the mold. In general, a volume of the mold is much bigger than that of casting part, so the proposed technique decreases the number of mesh and saves the computational memory and time greatly. In this study, the proposed technique was verified by the comparison with the traditional contact technique on a specimen. And the proposed technique gave satisfactory results.

  7. Alterations in neuronal morphology in infralimbic cortex predict resistance to fear extinction following acute stress.

    Science.gov (United States)

    Moench, Kelly M; Maroun, Mouna; Kavushansky, Alexandra; Wellman, Cara

    2016-06-01

    Dysfunction in corticolimbic circuits that mediate the extinction of learned fear responses is thought to underlie the perseveration of fear in stress-related psychopathologies, including post-traumatic stress disorder. Chronic stress produces dendritic hypertrophy in basolateral amygdala (BLA) and dendritic hypotrophy in medial prefrontal cortex, whereas acute stress leads to hypotrophy in both BLA and prelimbic cortex. Additionally, both chronic and acute stress impair extinction retrieval. Here, we examined the effects of a single elevated platform stress on extinction learning and dendritic morphology in infralimbic cortex, a region considered to be critical for extinction. Acute stress produced resistance to extinction, as well as dendritic retraction in infralimbic cortex. Spine density on apical and basilar terminal branches was unaffected by stress. However, animals that underwent conditioning and extinction had decreased spine density on apical terminal branches. Thus, whereas dendritic morphology in infralimbic cortex appears to be particularly sensitive to stress, changes in spines may more sensitively reflect learning. Further, in stressed rats that underwent conditioning and extinction, the level of extinction learning was correlated with spine densities, in that rats with poorer extinction retrieval had more immature spines and fewer thin spines than rats with better extinction retrieval, suggesting that stress may have impaired learning-related spine plasticity. These results may have implications for understanding the role of medial prefrontal cortex in learning deficits associated with stress-related pathologies. PMID:26844245

  8. Individual differences in early adolescents' latent trait cortisol (LTC): Relation to recent acute and chronic stress.

    Science.gov (United States)

    Stroud, Catherine B; Chen, Frances R; Doane, Leah D; Granger, Douglas A

    2016-08-01

    Research suggests that environmental stress contributes to health by altering the regulation of the hypothalamic pituitary adrenal (HPA) axis. Recent evidence indicates that early life stress alters trait indicators of HPA axis activity, but whether recent stress alters such indicators is unknown. Using objective contextual stress interviews with adolescent girls and their mothers, we examined the impact of recent acute and chronic stress occurring during the past year on early adolescent girls' latent trait cortisol (LTC) level. We also examined whether associations between recent stress and LTC level: a) varied according to the interpersonal nature and controllability of the stress; and b) remained after accounting for the effect of early life stress. Adolescents (n=117;M age=12.39years) provided salivary cortisol samples three times a day (waking, 30min post-waking and bedtime) over 3days. Results indicated that greater recent interpersonal acute stress and greater recent independent (i.e., uncontrollable) acute stress were each associated with a higher LTC level, over and above the effect of early adversity. In contrast, greater recent chronic stress was associated with a lower LTC level. Findings were similar in the overall sample and a subsample of participants who strictly adhered to the timed schedule of saliva sample collection. Implications for understanding the impact of recent stress on trait-like individual differences in HPA axis activity are discussed. PMID:27155256

  9. Surface Residual Stresses in Ti-6Al-4V Friction Stir Welds: Pre- and Post-Thermal Stress Relief

    Science.gov (United States)

    Edwards, P.; Ramulu, M.

    2015-09-01

    The purpose of this study was to determine the residual stresses present in titanium friction stir welds and if a post-weld thermal stress relief cycle would be effective in minimizing those weld-induced residual stresses. Surface residual stresses in titanium 6Al-4V alloy friction stir welds were measured in butt joint thicknesses ranging from 3 to 12 mm. The residual stress states were also evaluated after the welds were subjected to a post-weld thermal stress relief cycle of 760 °C for 45 min. High (300-400 MPa) tensile residual stresses were observed in the longitudinal direction prior to stress relief and compressive residual stresses were measured in the transverse direction. After stress relief, the residual stresses were decreased by an order of magnitude to negligible levels.

  10. Thermal/residual stress in an electron beam physical vapor deposited thermal barrier coating system

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, J.; Jordan, E.H.; Barber, B.; Gell, M. [Univ. of Connecticut, Storrs, CT (United States)

    1998-10-09

    Elastic-plastic finite element models are used to define the thermal/residual stress state responsible for the observed failure behavior of an electron beam physical vapor deposited yttria stabilized zirconia thermal barrier coating on a Pt-Al bond coat. The failures were observed to start at grain boundary ridges, some of which evolved into oxide filled cavities. Finite element models are made of the actual interface geometries through the use of metallographic sectioning and imaging processing. There is a one to one correspondence of calculated tension in the oxide layer and the observed localized damage. Purely elastic analysis failed to show some important tensile regions associated with the observed failure.

  11. Child Anxiety Symptoms Related to Longitudinal Cortisol Trajectories and Acute Stress Responses: Evidence of Developmental Stress Sensitization

    Science.gov (United States)

    Laurent, Heidemarie K.; Gilliam, Kathryn S.; Wright, Dorianne B.; Fisher, Philip A.

    2015-01-01

    Cross-sectional research suggests that individuals at risk for internalizing disorders show differential activation levels and/or dynamics of stress-sensitive physiological systems, possibly reflecting a process of stress sensitization. However, there is little longitudinal research to clarify how the development of these systems over time relates to activation during acute stress, and how aspects of such activation map onto internalizing symptoms. We investigated children’s (n=107) diurnal hypothalamic-pituitary-adrenal activity via salivary cortisol (morning and evening levels) across 29 assessments spanning 6+ years, and related longitudinal patterns to acute stress responses at the end of this period (age 9–10). Associations with child psychiatric symptoms at age 10 were also examined to determine internalizing risk profiles. Increasing morning cortisol levels across assessments predicted less of a cortisol decline following interpersonal stress at age 9, and higher cortisol levels during performance stress at age 10. These same profiles of high and/or sustained cortisol elevation during psychosocial stress were associated with child anxiety symptoms. Results suggest developmental sensitization to stress—reflected in rising morning cortisol and eventual hyperactivation during acute stress exposure—may distinguish children at risk for internalizing disorders. PMID:25688433

  12. Burrowing, byssus, and biomarkers: behavioral and physiological indicators of sublethal thermal stress in freshwater mussels (Unionidae)

    Science.gov (United States)

    Archambault, Jennifer M.; Cope, W. Gregory; Kwak, Thomas J.

    2013-01-01

    Recent research has elucidated the acute lethal effects of elevated water temperatures to glochidia (larvae), juvenile, and adult life stages of freshwater mussels (Order Unionida), but few studies have focused on sublethal effects of thermal stress. We evaluated the sublethal effects of elevated temperature on burrowing behavior and byssus production in juveniles, and on enzymatic biomarkers of stress in adults in acute (96 h) laboratory experiments in sediment, with two acclimation temperatures (22 and 27 °C) and two experimental water levels (watered and dewatered) as proxies for flow regime. Increasing temperature significantly reduced burrowing in all five species tested, and the dewatered treatment (a proxy for drought conditions) reduced burrowing in all but Amblema plicata. Production of byssal threads was affected most drastically by flow regime, with the probability of byssus presence reduced by 93–99% in the dewatered treatment, compared to the watered treatment (a proxy for low flow conditions); increasing temperature alone reduced byssus by 18–35%. Alanine aminotransferase and aspartate aminotransferase were significantly affected by treatment temperature in the 27 °C acclimation, watered test (p = 0.04 and 0.02, respectively). Our results are important in the context of climate change, because stream temperature and flow are expected to change with increasing air temperature and altered precipitation patterns.

  13. Amygdala-Hippocampal Connectivity Changes During Acute Psychosocial Stress: Joint Effect of Early Life Stress and Oxytocin.

    Science.gov (United States)

    Fan, Yan; Pestke, Karin; Feeser, Melanie; Aust, Sabine; Pruessner, Jens C; Böker, Heinz; Bajbouj, Malek; Grimm, Simone

    2015-11-01

    Previous evidence shows that acute stress changes both amygdala activity and its connectivity with a distributed brain network. Early life stress (ELS), especially emotional abuse (EA), is associated with altered reactivity to psychosocial stress in adulthood and moderates or even reverses the stress-attenuating effect of oxytocin (OXT). The neural underpinnings of the interaction between ELS and OXT remain unclear, though. Therefore, we here investigate the joint effect of ELS and OXT on transient changes in amygdala-centered functional connectivity induced by acute psychosocial stress, using a double-blind, randomized, placebo-controlled, within-subject crossover design. Psychophysiological interaction analysis in the placebo session revealed stress-induced increases in functional connectivity between amygdala and medial prefrontal cortex, posterior cingulate cortex, putamen, caudate and thalamus. Regression analysis showed that EA was positively associated with stress-induced changes in connectivity between amygdala and hippocampus. Moreover, hierarchical linear regression showed that this positive association between EA and stress-induced amygdala-hippocampal connectivity was moderated after the administration of intranasal OXT. Amygdala-hippocampal connectivity in the OXT session correlated negatively with cortisol stress responses. Our findings suggest that altered amygdala-hippocampal functional connectivity during psychosocial stress may have a crucial role in the altered sensitivity to OXT effects in individuals who have experienced EA in their childhood.

  14. Study of thermal stress in heat affected zones during welding

    International Nuclear Information System (INIS)

    The importance of applications of welding in the nuclear industry leads to the study of the main problem concerning metal welding: sensibility to cracking. The development of computation methods allows the numerical simulation of welding effects. Due to the complexity of this problem, it is divided in three steps: thermal, metallurgical and mechanical calculus. Interactions between the 3 steps are examined. Mathematical models necessary to get residual stress (i.e. stress remaining when welding is completed and structure at ambient temperature) are described. Then parameters for metallurgical structure determination are given and compared to experiments. A508 and A533 type steels of primary coolant circuit of PWR reactors are taken as examples and the numerical simulation of a test is presented

  15. Bond strength and stress measurements in thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Jordan, E. [Univ. of Connecticut, Storrs, CT (United States)

    1995-10-01

    Thermal barrier coatings have been used extensively in aircraft gas turbines for more than 15 years to insulate combustors and turbine vanes from the hot gas stream. Plasma sprayed thermal barrier coatings (TBCs) provide metal temperature reductions as much as 300{degrees}F, with improvements in durability of two times or more being achieved. The introduction of TBCs deposited by electron beam physical vapor deposition (EB-PVD) processes in the last five years has provided a major improvement in durability and also enabled TBCs to be applied to turbine blades for improved engine performance. To meet the aggressive Advanced Turbine Systems goals for efficiency, durability and the environment, it will be necessary to employ thermal barrier coatings on turbine airfoils and other hot section components. For The successful application of TBCs to ATS engines with 2600{degrees}F turbine inlet temperatures and required component lives 10 times greater than those for aircraft gas turbine engines, it is necessary to develop quantitative assessment techniques for TBC coating integrity with time and cycles in ATS engines. Thermal barrier coatings in production today consist of a metallic bond coat, such as an MCrAlY overlay coating or a platinum aluminide (Pt-Al) diffusion coating. During heat treatment, both these coatings form a thin, tightly adherent alumina (Al{sub 2}O{sub 3}) film. Failure of TBC coatings in engine service occurs by spallation of the ceramic coating at or near the bond coat to alumina or the alumina to zirconia bonds. Thus, it is the initial strength of these bonds and the stresses at the bond plane, and their changes with engine exposure, that determines coating durability. The purpose of this program is to provide, for the first time, a quantitative assessment of TBC bond strength and bond plane stresses as a function of engine time and cycles.

  16. Investigation of Thermal Stress Distribution in Laser Spot Welding Process

    Directory of Open Access Journals (Sweden)

    Osamah F. Abdulateef

    2009-01-01

    Full Text Available The objective of this paper was to study the laser spot welding process of low carbon steel sheet. The investigations were based on analytical and finite element analyses. The analytical analysis was focused on a consistent set of equations representing interaction of the laser beam with materials. The numerical analysis based on 3-D finite element analysis of heat flow during laser spot welding taken into account the temperature dependence of the physical properties and latent heat of transformations using ANSYS code V.10.0 to simulate the laser welding process. The effect of laser operating parameters on the results of the temperature profile were studied in addition to the effect on thermal stresses and dimensions of the laser welded workpiece which showed good correlations between analytical and numerical results. It was found that the temperature gradients during laser welding are usually very large and it was viewed that very high temperature at the center of the workpiece, and is decreased very significantly as propagating along the radial direction. Also it found that the thermal residual stresses around the laser spot due to plastic strains were very small and localized within 1.0 mm range. It is concluded that the laser welding process is effective to reduce the welding residual stress. The stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding to tension at the spot under the laser beam and compression away from the spot when it cooled, which are in a good agreement with the published results.

  17. Thermal and thermal stress analysis of a pool type LMFBR deck structure

    International Nuclear Information System (INIS)

    The thermal capabilities of the ANSYS code were used to construct a thermal model of a pool type LMFBR system. This model included the primary tank of hot sodium covered by the concrete deck. Included in the geometry were the pump, heat exchanger, and control rod penetrations, and the metallic insulation underneath the concrete. The model included radiation and conduction of heat from the hot sodium to the concrete deck, and the cooling of the concrete via water pipes embedded in it. Thermal stresses are calculated within the code for the various plate and shell steel elements used in the code to represent different parts of the structure. This study provides a basis for studying the effect of insulation and coolant in the design of the deck structure

  18. Cognitive Processing Therapy for Acute Stress Disorder Resulting from an Anti-Gay Assault

    Science.gov (United States)

    Kaysen, Debra; Lostutter, Ty W.; Goines, Marie A.

    2005-01-01

    This case study describes Cognitive Processing Therapy (CPT) with a 30-year-old gay man with symptoms of acute stress disorder (ASD) following a recent homophobic assault. Treatment addressed assault-related posttraumatic stress disorder symptoms and depressive symptoms. Also addressed were low self-esteem, helplessness, and high degrees of…

  19. Previous stress and acute psychological defence as predictors of perinatal grief - An exploratory study

    NARCIS (Netherlands)

    J.A.M. Hunfeld (Joke); J.W. Wladimiroff (Juriy); F. Verhage; J. Passchier (Jan)

    1995-01-01

    textabstractWe evaluated whether the emotional reactions of women at 2–6 weeks after the prenatal diagnosis of a lethal anomaly and at 3 months after perinatal loss might be predicted by previous stress and acute psychological defence reactions to the diagnosis. Previous stress was defined objective

  20. Acute restraint stress enhances hippocampal endocannabinoid function via glucocorticoid receptor activation.

    Science.gov (United States)

    Wang, Meina; Hill, Matthew N; Zhang, Longhua; Gorzalka, Boris B; Hillard, Cecilia J; Alger, Bradley E

    2012-01-01

    Exposure to behavioural stress normally triggers a complex, multilevel response of the hypothalamic-pituitary-adrenal (HPA) axis that helps maintain homeostatic balance. Although the endocannabinoid (eCB) system (ECS) is sensitive to chronic stress, few studies have directly addressed its response to acute stress. Here we show that acute restraint stress enhances eCB-dependent modulation of GABA release measured by whole-cell voltage clamp of inhibitory postsynaptic currents (IPSCs) in rat hippocampal CA1 pyramidal cells in vitro. Both Ca(2+)-dependent, eCB-mediated depolarization-induced suppression of inhibition (DSI), and muscarinic cholinergic receptor (mAChR)-mediated eCB mobilization are enhanced following acute stress exposure. DSI enhancement is dependent on the activation of glucocorticoid receptors (GRs) and is mimicked by both in vivo and in vitro corticosterone treatment. This effect does not appear to involve cyclooxygenase-2 (COX-2), an enzyme that can degrade eCBs; however, treatment of hippocampal slices with the L-type calcium (Ca(2+)) channel inhibitor, nifedipine, reverses while an agonist of these channels mimics the effect of in vivo stress. Finally, we find that acute stress produces a delayed (by 30 min) increase in the hippocampal content of 2-arachidonoylglycerol, the eCB responsible for DSI. These results support the hypothesis that the ECS is a biochemical effector of glucocorticoids in the brain, linking stress with changes in synaptic strength. PMID:21890595

  1. Infusion of glucose and lipids at physiological rates causes acute endoplasmic reticulum stress in rat liver.

    Science.gov (United States)

    Boden, Guenther; Song, Weiwei; Duan, Xunbao; Cheung, Peter; Kresge, Karen; Barrero, Carlos; Merali, Salim

    2011-07-01

    Endoplasmic reticulum (ER) stress has recently been implicated as a cause for obesity-related insulin resistance; however, what causes ER stress in obesity has remained uncertain. Here, we have tested the hypothesis that macronutrients can cause acute (ER) stress in rat liver. Examined were the effects of intravenously infused glucose and/or lipids on proximal ER stress sensor activation (PERK, eIF2-α, ATF4, Xbox protein 1 (XBP1s)), unfolded protein response (UPR) proteins (GRP78, calnexin, calreticulin, protein disulphide isomerase (PDI), stress kinases (JNK, p38 MAPK) and insulin signaling (insulin/receptor substrate (IRS) 1/2 associated phosphoinositol-3-kinase (PI3K)) in rat liver. Glucose and/or lipid infusions, ranging from 23.8 to 69.5 kJ/4 h (equivalent to between ~17% and ~50% of normal daily energy intake), activated the proximal ER stress sensor PERK and ATF6 increased the protein abundance of calnexin, calreticulin and PDI and increased two GRP78 isoforms. Glucose and glucose plus lipid infusions induced comparable degrees of ER stress, but only infusions containing lipid activated stress kinases (JNK and p38 MAPK) and inhibited insulin signaling (PI3K). In summary, physiologic amounts of both glucose and lipids acutely increased ER stress in livers 12-h fasted rats and dependent on the presence of fat, caused insulin resistance. We conclude that this type of acute ER stress is likely to occur during normal daily nutrient intake.

  2. The magnitude of heat treatment induced residual stresses and the thermal stress relief of aluminium alloys

    OpenAIRE

    Robinson, J S; Tanner, D.A

    2002-01-01

    To produce useful strengthening, precipitation hardenable aluminium alloys rely on rapid quenching from the solution heat treatment temperature to suppress the formation of coarse equilibrium second phases. An unavoidable consequence of the rapid quenching of thick sections is the severe thermal gradients that quickly develop in the material. The attendant inhomogeneous plastic flow can then result in the establishment of residual stresses. Established procedures exist to minim...

  3. The effect of obesity on inflammatory cytokine and leptin production following acute mental stress.

    Science.gov (United States)

    Caslin, H L; Franco, R L; Crabb, E B; Huang, C J; Bowen, M K; Acevedo, E O

    2016-02-01

    Obesity may contribute to cardiovascular disease (CVD) risk by eliciting chronic systemic inflammation and impairing the immune response to additional stressors. There has been little assessment of the effect of obesity on psychological stress, an independent risk factor for CVD. Therefore, it was of interest to examine interleukin-6, tumor necrosis factor-α, interleukin-1β (IL-1β), interleukin-1 receptor antagonist (IL-1Ra), and leptin following an acute mental stress task in nonobese and obese males. Twenty college-aged males (21.3 ± 0.56 years) volunteered to participate in a 20-min Stroop color-word and mirror-tracing task. Subjects were recruited for obese (body mass index: BMI > 30) and nonobese (BMI < 25) groups, and blood samples were collected for enzyme-linked immunosorbent assay analysis. The acute mental stress task elicited an increase in heart rate, catecholamines, and IL-1β in all subjects. Additionally, acute mental stress increased cortisol concentrations in the nonobese group. There was a significant reduction in leptin in obese subjects 30 min posttask compared with a decrease in nonobese subjects 120 min posttask. Interestingly, the relationship between the percent change in leptin and IL-1Ra at 120 min posttask in response to an acute mental stress task was only observed in nonobese individuals. This is the first study to suggest that adiposity in males may impact leptin and inflammatory signaling mechanisms following acute mental stress. PMID:26511907

  4. Viral and Bacterial Epibionts in Thermally-Stressed Corals

    Directory of Open Access Journals (Sweden)

    Hanh Nguyen-Kim

    2015-10-01

    Full Text Available The periodic rise in seawater temperature is one of the main environmental determinants of coral bleaching. However, the direct incidence of these episodic thermal anomalies on coral-associated microbiota and their subsequent effects on coral health are still not completely understood. In this study, we investigated the dynamics of three main microbial communities of the coral holobiont (e.g., Symbiodinium, bacteria and viruses, during an experimental thermal stress (+4 °C conducted on the scleractinian Fungia repanda. The heat-treatment induced coral bleaching after 11 days and resulted in a final elevation of ca. 9, 130 and 250-fold in the abundance of mucosal viruses, bacteria, and Symbiodinium, respectively. On the contrary, the proportion of actively respiring bacterial cells declined by 95% in heat-stressed corals. The community composition of epibiotic bacteria in healthy corals also greatly differed from bleached ones, which also exhibited much higher production rates of viral epibionts. Overall, our results suggest that the shift in temperature induced a series of microbial changes, including the expulsion and transfer of Symbiodinium cells from the coral polyps to the mucus, the collapse of the physiological state of the native bacterial associates, a substantial alteration in their community structure, and accompanied by the development of a cortege of highly active virulent phages. Finally, this study provides new insights into the environmentally-driven microbial and viral processes responsible for the dislocation of the coral holobiont.

  5. RAAS and stress markers in acute ischemic stroke

    DEFF Research Database (Denmark)

    Back, C.; Thiesen, K L; Olsen, Karsten Skovgaard;

    2015-01-01

    . RESULTS: The acute systolic blood pressure was significantly increased, 148 (141-168) vs 140 (130-147) mmHg post-stroke. Angiotensin I, renin and aldosterone levels were significantly lower, angiotensin II was unchanged, and ACE activity was higher in the acute phase compared to post-stroke. No...... differences in RAAS were detected between jugular and cubital plasma levels. Jugular venous plasma levels of epinephrine and cortisol were elevated in the acute phase compared to cubital levels (P < 0.05). CONCLUSION: Increased epinephrine and cortisol levels in the jugular vein blood may reflect a higher...

  6. Frequency of adverse outcomes of acute myocardial infarction in patients with stress hyperglycem)a

    International Nuclear Information System (INIS)

    Objective: To determine the frequency of in-hospital adverse outcomes of acute myocardial infarction in patients with stress hyperglycemia. Methodology: This was a descriptive cross sectional study conducted from August 2010 to January 2011 in Cardiology department, Lady Reading Hospital, Peshawar. Patients of age 25-70 years, of either gender, non-diabetic with acute myocardial infarction with stress hyperglycemia were included. Random blood sugar >144 mg/dl was taken as stress hyperglycemia for patients at presentation of acute myocardial infarction. Patients were monitored for electrical complications such as atrial fibrillation, ventricular tachycardia, ventricular fibrillation and complete heart block and mechanical complications such as cardiac pulmonary edema and cardiogenic shock during hospital stay. The statistical analysis was performed using the statistical package for social sciences (SPSS Ver. 15.0). Results: A total of 341 patients having acute myocardial infarction with stress hyperglycemia were studied. The mean age was 56.35 +- 9.748 (95% CI 57.39 - 55.31). Male were 58.1% (n=198). The frequency of various major in-hospital electrical adverse outcomes of acute myocardial infarction with stress hyperglycemia were atrial fibrillation (AF) 15.8%, ventricular tachycardia (VT) 11.7%, ventricular fibrillation (VF) 10.9% and complete heart block (CHB) 6.7%, while mechanical adverse outcomes were cardiac pulmonary edema (CPE) 7.9% and cardiogenic shock (CS) 11.7%. Conclusion: Stress hyperglycemia has adverse impact on outcomes of patients presenting with acute myocardial infarction. Among electrical and mechanical complications of acute myocardial infarction in patients with stress hyperglycemia, the two most frequent in-hospital adverse outcomes were atrial fibrillation and cardiogenic shock, respectively. (author)

  7. Acute social stress and cardiac electrical activity in rats

    NARCIS (Netherlands)

    Sgoifo, A; Stilli, D; de Boer, SF; Koolhaas, JM; Musso, E; Koolhaas, Jaap M.

    1998-01-01

    This paper summarizes the results of experiments aimed at describing electrocardiographic responses to different acute social stressors in healthy male rats. Electrocardiograms were telemetrically recorded during maternal aggression, social defeat, and psychosocial stimulation, as obtained using the

  8. Prognostics Approach for Power MOSFET Under Thermal-Stress

    Science.gov (United States)

    Galvan, Jose Ramon Celaya; Saxena, Abhinav; Kulkarni, Chetan S.; Saha, Sankalita; Goebel, Kai

    2012-01-01

    The prognostic technique for a power MOSFET presented in this paper is based on accelerated aging of MOSFET IRF520Npbf in a TO-220 package. The methodology utilizes thermal and power cycling to accelerate the life of the devices. The major failure mechanism for the stress conditions is dieattachment degradation, typical for discrete devices with leadfree solder die attachment. It has been determined that dieattach degradation results in an increase in ON-state resistance due to its dependence on junction temperature. Increasing resistance, thus, can be used as a precursor of failure for the die-attach failure mechanism under thermal stress. A feature based on normalized ON-resistance is computed from in-situ measurements of the electro-thermal response. An Extended Kalman filter is used as a model-based prognostics techniques based on the Bayesian tracking framework. The proposed prognostics technique reports on preliminary work that serves as a case study on the prediction of remaining life of power MOSFETs and builds upon the work presented in [1]. The algorithm considered in this study had been used as prognostics algorithm in different applications and is regarded as suitable candidate for component level prognostics. This work attempts to further the validation of such algorithm by presenting it with real degradation data including measurements from real sensors, which include all the complications (noise, bias, etc.) that are regularly not captured on simulated degradation data. The algorithm is developed and tested on the accelerated aging test timescale. In real world operation, the timescale of the degradation process and therefore the RUL predictions will be considerable larger. It is hypothesized that even though the timescale will be larger, it remains constant through the degradation process and the algorithm and model would still apply under the slower degradation process. By using accelerated aging data with actual device measurements and real

  9. Social Support, Social Intimacy, and Cardiovascular Reactions to Acute Psychological Stress

    OpenAIRE

    Anna C Phillips; Gallagher, Stephen; Carroll, Douglas

    2009-01-01

    peer-reviewed Background: Exaggerated cardiovascular reactions to psychological stress are considered a risk factor for cardiovascular morbidity. Social support may reduce such risk by attenuating cardiovascular reactivity to stress. Purpose: To examine the effects of three independent social support variables and their interaction on cardiovascular reactivity to acute stress. The variables were stranger or friend presence; active supportive or passive presence, and male or ...

  10. High-fat diet did not change metabolic response to acute stress in rats

    OpenAIRE

    Farrokhi, Babak; Ghalami, Jamileh; Hedayati, Mehdi; Rostamkhani, Fatemeh; Zardooz, Homeira

    2011-01-01

    This study investigated the effects of high-fat diet on metabolic factors in the presence of acute foot-shock and psychological stresses in male Wistar rats. The animals were divided into high-fat (45 % cow intra-abdominal fat) and normal (standard pellets) diet groups; then, each group was allocated into stressed and control groups. Stress was induced by a communication box. Blood samples were collected by retro-orbital-puncture method under isoflurane anesthesia. Plasma levels of gluc...

  11. Working memory performance after acute exposure to the cold pressor stress in healthy volunteers

    OpenAIRE

    Duncko, Roman; Johnson, Linda; Merikangas, Kathleen; Grillon, Christian

    2009-01-01

    Effects of acute stress exposure on learning and memory have been frequently studied in both animals and humans. However, only a few studies have focused specifically on working memory performance and the available data are equivocal. The present study examined working memory performance during the Sternberg item recognition task after exposure to a predominantly adrenergic stressor. Twenty four healthy subjects were randomly assigned to a stress group or a control group. The stress group was...

  12. Deficiency of Antinociception and Excessive Grooming Induced by Acute Immobilization Stress in Per1 Mutant Mice

    OpenAIRE

    Jing Zhang; Zhouqiao Wu; Linglin Zhou; Huili Li; Huajing Teng; Wei Dai; Yongqing Wang; Zhong Sheng Sun

    2011-01-01

    Acute stressors induce changes in numerous behavioral parameters through activation of the hypothalamic-pituitary-adrenal (HPA) axis. Several important hormones in paraventricular nucleus of the hypothalamus (PVN) play the roles in these stress-induced reactions. Corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) and corticosterone are considered as molecular markers for stress-induced grooming behavior. Oxytocin in PVN is an essential modulator for stress-induced antinocicepti...

  13. Comparative Research of Oil-paper Aging Characteristics Under Thermal Stress and Combined Thermo-electrical Stresses

    Institute of Scientific and Technical Information of China (English)

    WANG Shi-qiang; WU Feng-jiao; XU Hao; ZHANG Guan-jun

    2011-01-01

    During the operation of power transformer, its oil-paper insulation is continuously subjected to various stresses, e. g. , the thermal, electrical, mechanical, and chemical stresses, which cause insulation aging gradually. It has been considered that the combined thermal and electrical stresses are the most important and unavoidable factors that induce insulation materials aging. In this work, accelerated aging experiments of oil-impregnated pressboards un der combined thermal (130℃) and electrical stresses (4 kV/mm) are performed, while the aging experiments under single thermal stress are also carried out at the corresponding temperature (130 ℃). The electrical and physic-chemical properties of oil, including dielectric losses factor tanδ resistivity, acid value and pH value etc. , are measured during the aging process. Dissolved gasses in oil and polymerization degree of cellulose are also measured. The relationship between these properties of oil-paper insulation and aging time is investigated. The results show that dissolved gases in oil, resistivity, tanδ of oil under combined thermal and electrical stresses are obviously different from that under thermal stress during aging process while some other properties show similar changing :trend. For cellulose, compared with the single thermal aging results, it even shows a slower degradation rate in the presence of elec trical stress.

  14. Media's role in broadcasting acute stress following the Boston Marathon bombings.

    Science.gov (United States)

    Holman, E Alison; Garfin, Dana Rose; Silver, Roxane Cohen

    2014-01-01

    We compared the impact of media vs. direct exposure on acute stress response to collective trauma. We conducted an Internet-based survey following the Boston Marathon bombings between April 29 and May 13, 2013, with representative samples of residents from Boston (n = 846), New York City (n = 941), and the remainder of the United States (n = 2,888). Acute stress symptom scores were comparable in Boston and New York [regression coefficient (b) = 0.43; SE = 1.42; 95% confidence interval (CI), -2.36, 3.23], but lower nationwide when compared with Boston (b = -2.21; SE = 1.07; 95% CI, -4.31, -0.12). Adjusting for prebombing mental health (collected prospectively), demographics, and prior collective stress exposure, six or more daily hours of bombing-related media exposure in the week after the bombings was associated with higher acute stress than direct exposure to the bombings (continuous acute stress symptom total: media exposure b = 15.61 vs. direct exposure b = 5.69). Controlling for prospectively collected prebombing television-watching habits did not change the findings. In adjusted models, direct exposure to the 9/11 terrorist attacks and the Sandy Hook School shootings were both significantly associated with bombing-related acute stress; Superstorm Sandy exposure wasn't. Prior exposure to similar and/or violent events may render some individuals vulnerable to the negative effects of collective traumas. Repeatedly engaging with trauma-related media content for several hours daily shortly after collective trauma may prolong acute stress experiences and promote substantial stress-related symptomatology. Mass media may become a conduit that spreads negative consequences of community trauma beyond directly affected communities. PMID:24324161

  15. Acute Modulation of Sugar Transport in Brain Capillary Endothelial Cell Cultures during Activation of the Metabolic Stress Pathway*

    OpenAIRE

    Cura, Anthony J.; Carruthers, Anthony

    2010-01-01

    GLUT1-catalyzed equilibrative sugar transport across the mammalian blood-brain barrier is stimulated during acute and chronic metabolic stress; however, the mechanism of acute transport regulation is unknown. We have examined acute sugar transport regulation in the murine brain microvasculature endothelial cell line bEnd.3. Acute cellular metabolic stress was induced by glucose depletion, by potassium cyanide, or by carbonyl cyanide p-trifluoromethoxyphenylhydrazone, which reduce or deplete i...

  16. Assessment of oxidative stress parameters of brain-derived neurotrophic factor heterozygous mice in acute stress model

    Directory of Open Access Journals (Sweden)

    Gulay Hacioglu

    2016-04-01

    Full Text Available Objective(s: Exposing to stress may be associated with increased production of reactive oxygen species (ROS. Therefore, high level of oxidative stress may eventually give rise to accumulation of oxidative damage and development of numerous neurodegenerative diseases. It has been presented that brain-derived neurotrophic factor (BDNF supports neurons against various neurodegenerative conditions. Lately, there has been growing evidence that changes in the cerebral neurotrophic support and especially in the BDNF expression and its engagement with ROS might be important in various disorders and neurodegenerative diseases. Hence, we aimed to investigate protective effects of BDNF against stress-induced oxidative damage. Materials and Methods: Five- to six-month-old male wild-type and BDNF knock-down mice were used in this study. Activities of catalase (CAT and superoxide dismutase (SOD enzymes, and the amount of malondialdehyde (MDA were assessed in the cerebral homogenates of studied groups in response to acute restraint stress. Results: Exposing to acute physiological stress led to significant elevation in the markers of oxidative stress in the cerebral cortexes of experimental groups. Conclusion: As BDNF-deficient mice were observed to be more susceptible to stress-induced oxidative damage, it can be suggested that there is a direct interplay between oxidative stress indicators and BDNF levels in the brain.

  17. Plasma omega 3 polyunsaturated fatty acid status and monounsaturated fatty acids are altered by chronic social stress and predict endocrine responses to acute stress in titi monkeys

    Science.gov (United States)

    Disturbances in fatty acid (FA) metabolism may link chronic psychological stress, endocrine responsiveness, and psychopathology. Therefore, lipid metabolome-wide responses and their relationships with endocrine (cortisol; insulin; adiponectin) responsiveness to acute stress (AS) were assessed in a ...

  18. Maintenance of a positive outlook during acute stress protects against pro-inflammatory reactivity and future depressive symptoms

    OpenAIRE

    Aschbacher, K; Epel, E; Wolkowitz, O M; Prather, A A; Puterman, E; Dhabhar, F.S.

    2011-01-01

    Cognitive and affective responses to acute stress influence pro-inflammatory cytokine reactivity, and peripheral cytokines (particularly lnterleukin-1 beta (IL-1β)), can act on the brain to promote depressive symptoms. It is unknown whether acute stress-induced changes in positive affect and cognitions (POS) and pro-inflammatory reactivity predict future depressive symptoms. We examined acute stress responses among women, to determine prospective predictors of depressive symptoms. Hypotheses:...

  19. Thermal stresses in an orthotropic rectangular plate with a rigid ribbonlike inclusion

    International Nuclear Information System (INIS)

    On the basis of the complex variable method for determining the stationary two-dimensional thermal stresses, the thermal stresses in an orthotropic rectangular plate with a rigid ribbonlike inclusion under a steady state temperature field is considered. The solution is found by the analytic continuation argument and the modified mapping-collocation technique. Numerical results indicate a dependence of the orthotropic stress intensity factors on the thermal, elastic and geometrical constants over a certain parameter range. (orig.)

  20. Corals escape bleaching in regions that recently and historically experienced frequent thermal stress

    OpenAIRE

    Thompson, D M; R. van Woesik

    2009-01-01

    The response of coral-reef ecosystems to contemporary thermal stress may be in part a consequence of recent or historical sea-surface temperature (SST) variability. To test this hypothesis, we examined whether: (i) there was a relationship between the historical frequency of SST variability and stress experienced during the most recent thermal-stress events (in 1998 and 2005–2006) and (ii) coral reefs that historically experienced frequent thermal anomalies were less likely to experience cora...

  1. Acute restraint stress induces rapid and prolonged changes in erythrocyte and hippocampal redox status.

    Science.gov (United States)

    Spiers, Jereme G; Chen, Hsiao-Jou; Bradley, Adrian J; Anderson, Stephen T; Sernia, Conrad; Lavidis, Nickolas A

    2013-11-01

    The onset and consequential changes in reduction-oxidation (redox) status that take place in response to short-term stress have not been well defined. This study utilized erythrocytes and neural tissue from male Wistar rats to demonstrate the rapid redox alterations that occur following an acute restraining stress. Serial blood samples collected from catheterized animals were used to measure prolactin, corticosterone, glucose, general oxidative status, and glutathione/glutathione disulfide ratios. Restraint increased prolactin concentration by approximately 300% at 30 min and rapidly returned to baseline values by 120 min of stress. Baseline blood glucose and corticosterone increased during stress exposure by approximately 25% and 150% respectively. Over the experimental period, the erythrocytic oxidative status of restrained animals increased by approximately 10% per hour which persisted after stress exposure, while changes in the glutathione redox couple were not observed until 120 min following the onset of stress. Application of restraint stress increased hippocampal oxidative status by approximately 17% while no change was observed in the amygdala. It was concluded that while endocrine and metabolic markers of stress rapidly increase and habituate to stress exposure, redox status continues to change following stress in both peripheral and neural tissue. Studies with longer post-restraint times and the inclusion of several brain regions should further elucidate the consequential redox changes induced by acute restraint stress.

  2. Mitochondrial reactive oxygen species production by fish muscle mitochondria: Potential role in acute heat-induced oxidative stress.

    Science.gov (United States)

    Banh, Sheena; Wiens, Lilian; Sotiri, Emianka; Treberg, Jason R

    2016-01-01

    Acute heat challenge is known to induce cell-level oxidative stress in fishes. Mitochondria are well known for the capacity to make reactive oxygen species (ROS) and as such are often implicated as a source of the oxidants associated with this thermally-induced oxidative stress. This implication is often asserted, despite little direct data for mitochondrial ROS metabolism in fishes. Here we characterize mitochondrial ROS metabolism in three Actinopterygian fish species at two levels, the capacity for superoxide/H2O2 production and the antioxidant thiol-reductase enzyme activities. We find that red muscle mitochondria from all three species have measurable ROS production and respond to different assay conditions consistent with what might be anticipated; assuming similar relative contributions from difference ROS producing sites as found in rat skeletal muscle mitochondria. Although there are species and assay specific exceptions, fish mitochondria may have a greater capacity to produce ROS than that found in the rat when either normalized to respiratory capacity or determined at a common assay temperature. The interspecific differences in ROS production are not correlated with thiol-based antioxidant reductase activities. Moreover, mimicking an acute in vivo heat stress by comparing the impact of increasing assay temperature on these processes in vitro, we find evidence supporting a preferential activation of mitochondrial H2O2 production relative to the increase in the capacity of reductase enzymes to supply electrons to the mitochondrial matrix peroxidases. This supports the contention that mitochondria may be, at least in part, responsible for the ROS that lead to oxidative stress in fish tissues exposed to acute heat challenge.

  3. Acute stress response and recovery after whiplash injuries. A one-year prospective study

    DEFF Research Database (Denmark)

    Kongsted, Alice; Bendix, Tom; Qerama, Erisela;

    2007-01-01

    Chronic whiplash-associated disorder (WAD) represents a major medical and psycho-social problem. The typical symptomatology presented in WAD is to some extent similar to symptoms of post traumatic stress disorder. In this study we examined if the acute stress reaction following a whiplash injury...... outcome-measures were neck pain and headache, neck disability, general health, and working ability one year after the accident. A total of 737 participants were included and completed the IES, and 668 (91%) participated in the 1-year follow-up. A baseline IES-score denoting a moderate to severe stress...... were modified by baseline neck pain intensity. It was not possible to distinguish between participants who recovered and those who did not by means of the IES (AUC=0.6). In conclusion, the association between the acute stress reaction and persistent WAD suggests that post traumatic stress reaction may...

  4. Acute stress response and recovery after whiplash injuries. A one-year prospective study

    DEFF Research Database (Denmark)

    Kongsted, Alice; Bendix, Tom; Montvilas, Erisela Qerama;

    2008-01-01

    Chronic whiplash-associated disorder (WAD) represents a major medical and psycho-social problem. The typical symptomatology presented in WAD is to some extent similar to symptoms of post traumatic stress disorder. In this study we examined if the acute stress reaction following a whiplash injury...... outcome-measures were neck pain and headache, neck disability, general health, and working ability one year after the accident. A total of 737 participants were included and completed the IES, and 668 (91%) participated in the 1-year follow-up. A baseline IES-score denoting a moderate to severe stress...... were modified by baseline neck pain intensity. It was not possible to distinguish between participants who recovered and those who did not by means of the IES (AUC=0.6). In conclusion, the association between the acute stress reaction and persistent WAD suggests that post traumatic stress reaction may...

  5. OSO paradigm--A rapid behavioral screening method for acute psychosocial stress reactivity in mice.

    Science.gov (United States)

    Brzózka, M M; Unterbarnscheidt, T; Schwab, M H; Rossner, M J

    2016-02-01

    Chronic psychosocial stress is an important environmental risk factor for the development of psychiatric diseases. However, studying the impact of chronic psychosocial stress in mice is time consuming and thus not optimally suited to 'screen' increasing numbers of genetically manipulated mouse models for psychiatric endophenotypes. Moreover, many studies focus on restraint stress, a strong physical stressor with limited relevance for psychiatric disorders. Here, we describe a simple and a rapid method based on the resident-intruder paradigm to examine acute effects of mild psychosocial stress in mice. The OSO paradigm (open field--social defeat--open field) compares behavioral consequences on locomotor activity, anxiety and curiosity before and after exposure to acute social defeat stress. We first evaluated OSO in male C57Bl/6 wildtype mice where a single episode of social defeat reduced locomotor activity, increased anxiety and diminished exploratory behavior. Subsequently, we applied the OSO paradigm to mouse models of two schizophrenia (SZ) risk genes. Transgenic mice with neuronal overexpression of Neuregulin-1 (Nrg1) type III showed increased risk-taking behavior after acute stress exposure suggesting that NRG1 dysfunction is associated with altered affective behavior. In contrast, Tcf4 transgenic mice displayed a normal stress response which is in line with the postulated predominant contribution of TCF4 to cognitive deficits of SZ. In conclusion, the OSO paradigm allows for rapid screening of selected psychosocial stress-induced behavioral endophenotypes in mouse models of psychiatric diseases.

  6. Being a Grump Only Makes Things Worse: A Transactional Account of Acute Stress on Mind Wandering

    Directory of Open Access Journals (Sweden)

    Melaina T Vinski

    2013-11-01

    Full Text Available The current work investigates the influence of acute stress on mind wandering. Participants completed the Positive and Negative Affect Scale as a measure of baseline negative mood, and were randomly assigned to either the high stress or low stress version of the Trier Social Stress Test. Participants then completed the Sustained Attention to Response Task (SART as a measure of mind wandering behaviour. In Experiment 1, participants reporting a high degree of negative mood that were exposed to the high stress condition were more likely to engage in a variable response time, make more errors, and were more likely to report thinking about the stressor relative to participants that report a low level of negative mood. These effects diminished throughout task performance, suggesting that acute stress induces a temporary mind wandering state in participants with a negative mood. The temporary affect-dependent deficits observed in Experiment 1 were replicated in Experiment 2, with the high negative mood participants demonstrating limited resource availability (indicated by pupil diameter immediately following stress induction. These experiments provide novel evidence to suggest that acute psychosocial stress briefly suppresses the availability of cognitive resources and promotes an internally-oriented focus of attention in participants with a negative mood.

  7. Effect of ultrasonic treatment on stress condition of gas-thermal coatings of nickel alloys

    International Nuclear Information System (INIS)

    The ultrasonic treatment (UST) effect on residual stresses in gas-thermal coatings is studied. It is shown that the UST changes the structure of gas-thermal coatings and so affects their stressed state. Variations in UST intensity allow controlling the level and the sigh of residual stresses in coatings. The generation of compressive stresses in the coatings during the UST results in an increase of their operational characteristics

  8. Preliminary Thermal Stress Analysis of a High-Pressure Cryogenic Storage Tank

    Science.gov (United States)

    Baker, J. Mark

    2003-01-01

    The thermal stresses on a cryogenic storage tank strongly affect the condition of the tank and its ability to withstand operational stresses. These thermal stresses also affect the growth of any surface damage that might occur in the tank walls. These stresses are particularly of concern during the initial cooldown period for a new tank placed into service, and during any subsequent thermal cycles. A preliminary thermal stress analysis of a high-pressure cryogenic storage tank was performed. Stresses during normal operation were determined, as well as the transient temperature distribution. An elastic analysis was used to determine the thermal stresses in the inner wall based on the temperature data. The results of this elastic analysis indicate that the inner wall of the storage tank will experience thermal stresses of approximately 145,000 psi (1000 MPa). This stress level is well above the room-temperature yield strength of 304L stainless steel, which is about 25,000 psi (170 MPa). For this preliminary analysis, several important factors have not yet been considered. These factors include increased strength of 304L stainless steel at cryogenic temperatures, plastic material behavior, and increased strength due to strain hardening. In order to more accurately determine the thermal stresses and their affect on the tank material, further investigation is required, particularly in the area of material properties and their relationship to stress.

  9. Exposure to acute stress enhances decision-making competence: Evidence for the role of DHEA.

    Science.gov (United States)

    Shields, Grant S; Lam, Jovian C W; Trainor, Brian C; Yonelinas, Andrew P

    2016-05-01

    Exposure to acute stress can impact performance on numerous cognitive abilities, but little is known about how acute stress affects real-world decision-making ability. In the present study, we induced acute stress with a standard laboratory task involving uncontrollable socio-evaluative stress and subsequently assessed decision-making ability using the Adult Decision Making Competence index. In addition, we took baseline and post-test saliva samples from participants to examine associations between decision-making competence and adrenal hormones. Participants in the stress induction group showed enhanced decision-making competence, relative to controls. Further, although both cortisol and dehydroepiandrosterone (DHEA) reactivity predicted decision-making competence when considered in isolation, DHEA was a significantly better predictor than cortisol when both hormones were considered simultaneously. Thus, our results show that exposure to acute stress can have beneficial effects on the cognitive ability underpinning real-world decision-making and that this effect relates to DHEA reactivity more than cortisol.

  10. Non-stationary thermal stress of feed water studs

    International Nuclear Information System (INIS)

    Recent observations in BWR's exhibit fractures on the inner surface of feed water studs. The depth of these fractures is found to be very low. Experimental investigations suggest, that this is due to temperature oscillations between two liquid layers existing during operation times with less than 10% feed water flow. This work gives an analytical calculation for the radial time-dependant temperature distribution in the pipe walls. An expression is derived, to evaluate the temperature oscillation on the inner surface, which causes the fractures, if the behaviour on the outer suface is known by measurements. In addition the thermal stress is evaluated for the calculated temperature distribution. Results explain the observed facts such as position, orientation and the low depth of the fractures. (orig.)

  11. Divergent responses of inflammatory mediators within the amygdala and medial prefrontal cortex to acute psychological stress.

    Science.gov (United States)

    Vecchiarelli, Haley A; Gandhi, Chaitanya P; Gray, J Megan; Morena, Maria; Hassan, Kowther I; Hill, Matthew N

    2016-01-01

    There is now a growing body of literature that indicates that stress can initiate inflammatory processes, both in the periphery and brain; however, the spatiotemporal nature of this response is not well characterized. The aim of this study was to examine the effects of an acute psychological stress on changes in mRNA and protein levels of a wide range of inflammatory mediators across a broad temporal range, in key corticolimbic brain regions involved in the regulation of the stress response (amygdala, hippocampus, hypothalamus, medial prefrontal cortex). mRNA levels of inflammatory mediators were analyzed immediately following 30min or 120min of acute restraint stress and protein levels were examined 0h through 24h post-termination of 120min of acute restraint stress using both multiplex and ELISA methods. Our data demonstrate, for the first time, that exposure to acute psychological stress results in an increase in the protein level of several inflammatory mediators in the amygdala while concomitantly producing a decrease in the protein level of multiple inflammatory mediators within the medial prefrontal cortex. This pattern of changes seemed largely restricted to the amygdala and medial prefrontal cortex, with stress producing few changes in the mRNA or protein levels of inflammatory mediators within the hippocampus or hypothalamus. Consistent with previous research, stress resulted in a general elevation in multiple inflammatory mediators within the circulation. These data indicate that neuroinflammatory responses to stress do not appear to be generalized across brain structures and exhibit a high degree of spatiotemporal specificity. Given the impact of inflammatory signaling on neural excitability and emotional behavior, these data may provide a platform with which to explore the importance of inflammatory signaling within the prefrontocortical-amygdala circuit in the regulation of the neurobehavioral responses to stress.

  12. Depressive Symptoms Are Associated with Mental Stress-Induced Myocardial Ischemia after Acute Myocardial Infarction

    OpenAIRE

    Jingkai Wei; Pratik Pimple; Shah, Amit J.; Cherie Rooks; Douglas Bremner, J.; Nye, Jonathon A.; Ijeoma Ibeanu; Nancy Murrah; Lucy Shallenberger; Paolo Raggi; Viola Vaccarino

    2014-01-01

    Objectives Depression is an adverse prognostic factor after an acute myocardial infarction (MI), and an increased propensity toward emotionally-driven myocardial ischemia may play a role. We aimed to examine the association between depressive symptoms and mental stress-induced myocardial ischemia in young survivors of an MI. Methods We studied 98 patients (49 women and 49 men) age 38–60 years who were hospitalized for acute MI in the previous 6 months. Patients underwent myocardial perfusion ...

  13. Heat-shock protein 70 expression in shrimp Fenneropenaeus chinensis during thermal and immune-challenged stress

    Institute of Scientific and Technical Information of China (English)

    GUO Zhenyu; JIAO Chuanzhen; XIANG Jianhai

    2004-01-01

    Using western immunoblotting, we obtained heat-shock protein 70 (HSP70) induction data and distribution in different tissues from shrimp Fenneropenaeus chinensis during thermal and immune-challenged stresses. This is probably the first report of the effects of various stressors on the expression of HSP70 in shrimp. HSP70 was prominently induced in hepatopancreas and gills, but not in muscle, eyestalk and hemolymph, when the shrimp were exposed to heat shock and Vibrio anguillavium-challenged stresses. Cold shock and WSSV treatment had no significant effects on the levels of HSP70 expression in all tissues examined. HSP70 induction was greatest after 2 h exposure to heat shock stress, which was elevated after acute heat shock exposure of 10℃ above ambient temperature.

  14. A diagnostic interview for acute stress disorder for children and adolescents.

    Science.gov (United States)

    Miller, Alisa; Enlow, Michelle Bosquet; Reich, Wendy; Saxe, Glenn

    2009-12-01

    The goal of this study was to develop a semistructured clinical interview for assessing acute stress disorder (ASD) in youth and test its psychometric properties. Youth (N = 168) with an acute burn or injury were administered the acute stress disorder module of the Diagnostic Interview for Children and Adolescents (DICA-ASD). The DICA-ASD demonstrated strong psychometric properties, including high internal consistency (alpha = .97) and perfect diagnostic interrater agreement (kappa = 1.00). Participants diagnosed with ASD scored significantly higher than those not diagnosed on validated traumatic stress symptomatology measures but not on other symptomatology measures, providing evidence of convergent and discriminant validity. Preliminary evidence supports the reliability and validity of the first semistructured clinical interview for diagnosing ASD in youth.

  15. Thermal stresses in hexagonal materials - heat treatment influence on their mechanical behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Gloaguen, D.; Freour, S.; Guillen, R.; Royer, J. [Nantes Univ., GeM, Institut de Recherche en Genie Civil et Mecanique, Ecole Centrale de Nantes, UMR CNRS 6183, 44 (France); Francois, M. [Universite de Technologie de Troyes, Lab. des Systemes Mecaniques et d' Ingenierie Simultanee (LASMIS), 10 - Troyes (France)

    2004-12-01

    Internal stresses due to anisotropic thermal and plastic properties were investigated in rolled zirconium and titanium. The thermal stresses induced by a cooling process were predicted using a self-consistent model and compared with experimental results obtained by X-ray diffraction. The study of the elastoplastic response during uniaxial loading was performed along the rolling and the transverse direction of the sheet, considering the influence of the texture and the thermal stresses on the mechanical behaviour. An approach in order to determine the thermal behaviour of phases embedded in two-phase materials is also presented. For zirconium, the residual stresses due to thermal anisotropy are rather important (equivalent to 35% of the yield stress) and consequently they play an important role on the elastoplastic transition contrary to titanium. The study of two-phase material shows the influence and the interaction of the second phase on the thermal behaviour in the studied phase.

  16. Thermal stress in SiC element used in heat exchanger

    Institute of Scientific and Technical Information of China (English)

    LI He-song; MEI Chi

    2005-01-01

    An especial snake SiC pipe was designed for collecting losing heat from furnaces. The three-dimensions thermal, fluid and thermal stress coupled field of heat exchanger was analyzed by using the commercial engineering computer package ANSYS. The structural and operational parameters of heat exchanger, the junction between standpipe and snake pipe, the diameter of snake pipe, ratio of thickness to diameter of pipe, velocity of inlet air were optimized for thermal stress. The computed results show that the large thermal stress exits in the SiC, and the stand pipe should be ellipse for the least thermal stress; the optimal ratio of thickness to diameter of pipe is 6, the velocity of inlet air is 25 m/s. The most thermal stress is in inverse proportion to diameter of pipe and velocity of inlet air.

  17. Acute phase proteins in cattle after exposure to complex stress

    DEFF Research Database (Denmark)

    Lomborg, S. R.; Nielsen, L. R.; Heegaard, Peter M. H.;

    2008-01-01

    Abstract Stressors such as weaning, mixing and transportation have been shown to lead to increased blood concentrations of acute phase proteins (APP), including serum amyloid A (SAA) and haptoglobin, in calves. This study was therefore undertaken to assess whether SAA and haptoglobin levels...

  18. Myocardial stress in patients with acute cerebrovascular events

    DEFF Research Database (Denmark)

    Jespersen, Christian M; Fischer Hansen, Jørgen

    2008-01-01

    Signs of myocardial involvement are common in patients with acute cerebrovascular events. ST segment deviations, abnormal left ventricular function, increased N-terminal pro-brain natriuretic peptide (NT-proBNP), prolonged QT interval, and/or raised troponins are observed in up to one third of the...

  19. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M.; Struis, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  20. Simulation of thermal and sodium expansion stress in aluminum reduction cells

    Institute of Scientific and Technical Information of China (English)

    LI Jie; WU Yu-yun; LAI Yan-qing; LIU Wei; WANG Zhi-gang; LIU Jie; LIU Ye-xiang

    2008-01-01

    Two finite element(FE) models were built up for analysis of stress field in the lining of aluminum electrolysis cells. Distribution of sodium concentration in cathode carbon blocks was calculated by one FE model of a cathode block. Thermal stress field was calculated by the other slice model of the cell at the end of the heating-up. Then stresses coupling thermal and sodium expansion were considered after 30 d start-up. The results indicate that sodium penetrates to the bottom of the cathode block after 30 d start-up. The semi-graphitic carbon block has the largest stress at the thermal stage. After 30 d start-up the anthracitic carbon has the greatest sodium expansion stress and the graphitized carbon has the lowest sodium expansion stress. Sodium penetration can cause larger deformation and stress in the cathode carbon block than thermal expansion.

  1. Acute Exercise and Oxidative Stress: CrossFit™ vs. Treadmill Bout

    OpenAIRE

    Kliszczewicz Brian; John Quindry C.; Daniel Blessing L.; Gretchen Oliver D.; Michael Esco R.; Kyle Taylor J.

    2015-01-01

    CrossFit™, a popular high-intensity training modality, has been the subject of scrutiny, with concerns of elevated risk of injury and health. Despite these concerns empirical evidence regarding physiologic stresses including acute oxidative stress is lacking. Therefore, the purpose of this investigation was to examine the acute redox response to a CrossFit™ bout. Furthermore, these findings were compared to a high-intensity treadmill bout as a point of reference. Ten males 26.4 ± 2.7 yrs havi...

  2. Acute stress increases sex differences in risk seeking in the balloon analogue risk task.

    Directory of Open Access Journals (Sweden)

    Nichole R Lighthall

    Full Text Available BACKGROUND: Decisions involving risk often must be made under stressful circumstances. Research on behavioral and brain differences in stress responses suggest that stress might have different effects on risk taking in males and females. METHODOLOGY/PRINCIPAL FINDINGS: In this study, participants played a computer game designed to measure risk taking (the Balloon Analogue Risk Task fifteen minutes after completing a stress challenge or control task. Stress increased risk taking among men but decreased it among women. CONCLUSIONS/SIGNIFICANCE: Acute stress amplifies sex differences in risk seeking; making women more risk avoidant and men more risk seeking. Evolutionary principles may explain these stress-induced sex differences in risk taking behavior.

  3. Dual-task performance under acute stress in female adolescents with borderline personality disorder.

    Science.gov (United States)

    Kaess, Michael; Parzer, Peter; Koenig, Julian; Resch, Franz; Brunner, Romuald

    2016-09-01

    Research to elucidate early alterations of higher cognitive processes in adolescents with BPD is rare. This study investigated differences in dual-task performance in adolescents with BPD during stress and non-stress conditions. The study sample comprised 30 female adolescents with BPD and 34 healthy controls. The impact of stress on dual-task performance was measured using a standardized stressor. Self-reports of distress and measures of heart rate (HR) were obtained to measure stress reactivity. There were no group differences in task performance. Under stress conditions, the performance on the auditory task decreased in both groups but without significant group differences. Healthy controls showed an increase of mean HR after stress induction compared to no change in the BPD group. The finding of attenuated HR response to acute stress in adolescent patients with BPD may contradict current theories that the affective hyperresponsivity in BPD is based on a biologically determined mechanism. PMID:26852226

  4. Acute psychosocial stress and emotion regulation skills modulate empathic reactions to pain in others.

    Science.gov (United States)

    Buruck, Gabriele; Wendsche, Johannes; Melzer, Marlen; Strobel, Alexander; Dörfel, Denise

    2014-01-01

    Psychosocial stress affects resources for adequate coping with environmental demands. A crucial question in this context is the extent to which acute psychosocial stressors impact empathy and emotion regulation. In the present study, 120 participants were randomly assigned to a control group vs. a group confronted with the Trier Social Stress Test (TSST), an established paradigm for the induction of acute psychosocial stress. Empathy for pain as a specific subgroup of empathy was assessed via pain intensity ratings during a pain-picture task. Self-reported emotion regulation skills were measured as predictors using an established questionnaire. Stressed individuals scored significantly lower on the appraisal of pain pictures. A regression model was chosen to find variables that further predict the pain ratings. These findings implicate that acute psychosocial stress might impair empathic processes to observed pain in another person and the ability to accept one's emotion additionally predicts the empathic reaction. Furthermore, the ability to tolerate negative emotions modulated the relation between stress and pain judgments, and thus influenced core cognitive-affective functions relevant for coping with environmental challenges. In conclusion, our study emphasizes the necessity of reducing negative emotions in terms of empathic distress when confronted with pain of another person under psychosocial stress, in order to be able to retain pro-social behavior. PMID:24910626

  5. Some physiological and biochemical methods for acute and chronic stress evaluation in dairy cows

    Directory of Open Access Journals (Sweden)

    Giuseppe Bertoni

    2010-01-01

    Full Text Available Stress factors are so numerous and so diverse in their strength and duration that the consequences on animal welfare can be quite varied. The first important distinction concerns the characterization of acute and chronic stress conditions. Acute stress is a short-lived negative situation that allows a quick and quite complete recovery of the physiological balance (adaptation, while chronic stress is a long lasting condition from which the subject cannot fully recover (maladaptation. In the latter case, the direct effects of the stress factors (heat, low energy, anxiety, suffering etc., as well as the indirect ones (changes occurring at endocrinological, immune system or function level can be responsible for pre-pathological or pathological consequences which reduce animal welfare. To evaluate the possible chronic stress conditions in single animals or on a farm (in particular a farm of dairy cows, some parameters of the direct or indirect effects can be utilised. They are physiological (mainly hormone changes: cortisol, β-endorphin, behavioural (depression, biochemical (metabolites, acute phase proteins, glycated proteins etc., as well as performance parameters (growing rate, milk yield, fertility, etc.. Special attention has been paid to the interpretation of cortisol levels and to its changes after an ACTH challenge. Despite fervent efforts, well established and accepted indices of chronic stress (distress are currently lacking; but without this objective evaluation, the assessment of animal welfare and, therefore, the optimization of the livestock production, could prove more difficult.

  6. Acute psychosocial stress and emotion regulation skills modulate empathic reactions to pain in others.

    Science.gov (United States)

    Buruck, Gabriele; Wendsche, Johannes; Melzer, Marlen; Strobel, Alexander; Dörfel, Denise

    2014-01-01

    Psychosocial stress affects resources for adequate coping with environmental demands. A crucial question in this context is the extent to which acute psychosocial stressors impact empathy and emotion regulation. In the present study, 120 participants were randomly assigned to a control group vs. a group confronted with the Trier Social Stress Test (TSST), an established paradigm for the induction of acute psychosocial stress. Empathy for pain as a specific subgroup of empathy was assessed via pain intensity ratings during a pain-picture task. Self-reported emotion regulation skills were measured as predictors using an established questionnaire. Stressed individuals scored significantly lower on the appraisal of pain pictures. A regression model was chosen to find variables that further predict the pain ratings. These findings implicate that acute psychosocial stress might impair empathic processes to observed pain in another person and the ability to accept one's emotion additionally predicts the empathic reaction. Furthermore, the ability to tolerate negative emotions modulated the relation between stress and pain judgments, and thus influenced core cognitive-affective functions relevant for coping with environmental challenges. In conclusion, our study emphasizes the necessity of reducing negative emotions in terms of empathic distress when confronted with pain of another person under psychosocial stress, in order to be able to retain pro-social behavior.

  7. Acute Psychosocial Stress and Emotion Regulation Skills Modulate Empathic Reactions to Pain in Others

    Directory of Open Access Journals (Sweden)

    Gabriele eBuruck

    2014-05-01

    Full Text Available Psychosocial stress affects resources for adequate coping with environmental demands. A crucial question in this context is the extent to which acute psychosocial stressors impact empathy and emotion regulation. In the present study, 120 participants were randomly assigned to a control group vs. a group confronted with the Trier Social Stress Test, an established paradigm for the induction of acute psychosocial stress. Empathy for pain as a specific subgroup of empathy was assessed via pain intensity ratings during a pain-picture task. Self-reported emotion regulation skills were measured as predictors using an established questionnaire. Stressed individuals scored significantly lower on the appraisal of pain pictures. A regression model was chosen to find variables that further predict the pain ratings. These findings implicate that acute psychosocial stress might impair empathic processes to observed pain in another person and the ability to accept one’s emotion additionally predicts the empathic reaction. Furthermore, the ability to tolerate negative emotions modulated the relation between stress and pain judgments, and thus influenced core cognitive-affective functions relevant for coping with environmental challenges. In conclusion, our study emphasizes the necessity of reducing negative emotions in terms of empathic distress when confronted with pain of another person under psychosocial stress, in order to be able to retain pro-social behavior.

  8. [Biological function prediction of mir-210 in the liver of acute cold stress rat].

    Science.gov (United States)

    Guo, Wen-Jin; Lian, Shuai; Guo, Jing-Ru; Zhai, Jun-Fei; Zhang, Yu-Chen; Li, Yue; Zhen, Li; Ji, Hong; Yang, Huan-Min

    2016-04-25

    The study was aimed to observe mir-210 expression in liver tissue of acute cold stress rat and predict the function of mir-210 in cold stress. Thirty SPF Wistar male rats which were 12-week-old and weighed (340 ± 20) g were used. The rats were pre-fed in normal room temperature for one week, and then were randomly divided into acute cold stress group at (4 ± 0.1) °C and normal control group at (24 ± 0.1) °C. After the rats were treated with cold stress for 12 h, the liver tissue was extracted and the gene expression of mir-210 was assayed using qRT-PCR. The results demonstrated that the gene expression of mir-210 was significantly enhanced in acute cold stress group compared with that in normal control group (n = 3, P kinds of target genes such as E2F3, RAD52, ISCU and Ephrin-A3 are more relative with liver cold stress. ISCU regulates the cell respiratory metabolism and Ephrin-A3 is related with cell proliferation and apoptosis. On the other hand, up-regulated mir-210 affects the DNA repairing mechanism which usually leads to genetic instabilities. Our results suggest that cold stress-induced up-regulation of mir-210 in liver harmfully influences cell growth, energy metabolism and hereditary.

  9. Stress among nurses working in an acute hospital in Ireland.

    LENUS (Irish Health Repository)

    Donnelly, Teresa

    2014-01-01

    Stress among nurses leads to absenteeism, reduced efficiency, long-term health problems and a decrease in the quality of patient care delivered. A quantitative cross-sectional study was conducted. The study\\'s aim was to identify perceived stressors and influencing factors among nurses working in the critical and non-critical care practice areas. A convenience sample of 200 nurses were invited to complete the Bianchi Stress Questionnaire. Information was collected on demographics and daily nursing practice. Findings indicated that perceived stressors were similar in both groups. The most severe stressors included redeployment to work in other areas and staffing levels. Results from this study suggest that age, job title, professional experience and formal post-registration qualifications had no influence on stress perception. These results will increase awareness of nurses\\' occupational stress in Ireland.

  10. Stress analysis in curved composites due to thermal loading

    Science.gov (United States)

    Polk, Jared Cornelius

    Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, longer fatigue life, lower density, possibilities in reduction of life cycle and/or acquisition cost, and greater adaptability to intended function of structure via material composition and geometry. To be able to design and manufacture a safe composite laminate or structure, it is imperative that the stress distributions, their causes, and effects are thoroughly understood in order to successfully accomplish mission objectives and manufacture a safe and reliable composite. The objective of the thesis work is to expand upon the knowledge of simply curved composite structures by exploring and ascertaining all pertinent parameters, phenomenon, and trends in stress variations in curved laminates due to thermal loading. The simply curved composites consist of composites with one radius of curvature throughout the span of the specimen about only one axis. Analytical beam theory, classical lamination theory, and finite element analysis were used to ascertain stress variations in a flat, isotropic beam. An analytical method was developed to ascertain the stress variations in an isotropic, simply curved beam under thermal loading that is under both free-free and fixed-fixed constraint conditions. This is the first such solution to Author's best knowledge

  11. Effect of Thermal Stresses on the Failure Criteria of Fiber Composites

    DEFF Research Database (Denmark)

    Leong, Martin Klitgaard; Sankar, Bhavani V.

    2010-01-01

    , the latter, called micro-thermal stresses, has not been given much attention. In this paper the Direct Micromechanics Method is used to investigate the effects of micro-thermal stresses on the failure envelope of composites. Using FEA the unit-cell of the composite is analyzed. Assuming the failure criteria...

  12. Corticosterone and dehydroepiandrosterone in songbird plasma and brain: effects of season and acute stress

    OpenAIRE

    Newman, Amy E.M.; Soma, Kiran K.

    2009-01-01

    Prolonged increases in plasma glucocorticoids can exacerbate neurodegeneration. In rats, these neurodegenerative effects can be reduced by dehydroepiandrosterone (DHEA), an androgen precursor with anti-glucocorticoid actions. In song sparrows, season and acute restraint stress affect circulating levels of corticosterone and DHEA, and the effects of stress differ in plasma collected from the brachial and jugular veins. Jugular plasma is an indirect index of the neural steroidal milieu. Here, w...

  13. Acute stress increases interstitial fluid amyloid-β via corticotropin-releasing factor and neuronal activity

    OpenAIRE

    Kang, Jae-Eun; Cirrito, John R.; Dong, Hongxin; John G. Csernansky; Holtzman, David M.

    2007-01-01

    Aggregation of the amyloid-β (Aβ) peptide in the extracellular space of the brain is critical in the pathogenesis of Alzheimer's disease. Aβ is produced by neurons and released into the brain interstitial fluid (ISF), a process regulated by synaptic activity. To determine whether behavioral stressors can regulate ISF Aβ levels, we assessed the effects of chronic and acute stress paradigms in amyloid precursor protein transgenic mice. Isolation stress over 3 months increased Aβ levels by 84%. ...

  14. Prognostic significance of sinus deceleration during dobutamine stress echocardiography test following acute myocardial infarction

    OpenAIRE

    Šalinger Sonja; Tomašević Miloje; Glasnović Jozef; Apostolović Svetlana; Pavlović Milan; Pešić Zoran; Ranđelović Miomir; Stojković Aleksandar; Krstić Nebojša; Milić Dragan

    2006-01-01

    Background/Aim. Chronotropic incompetence during exercise stress testing after acute myocardial infarction is an indicator of ischemia or impaired left ventricular function. On the other side, infusion of dobutamine leads to a typical dose-dependent increase in heart rate. The aim of this study was to evaluate of paradoxical sinus deceleration during dobutamine stress echocardiography (DSE), as the sign of ischemia and impaired left ventricular function, or the consequence of infarction local...

  15. Effect of estrogen on plasma ceruloplasmin level in rats exposed to acute stress

    OpenAIRE

    Ganaraja B; Pavithran P; Ghosh S

    2004-01-01

    BACKGROUND: Plasma ceruloplasmin, a copper containing protein, belongs to a class called acute phase proteins. Reduced level of ceruloplasmin was associated with Wilson′s disease and Menke′s kinky hair disease in man, primarily affecting copper metabolism. Stress was known to increase Ceruloplasmin. Several stress associated changes were commonly observed in women at menopause and also those who underwent overiectomy. Present experiment investigated the effect of estrogen on cer...

  16. Graded stress radiography in acute injury to the lateral ligaments of the ankle

    International Nuclear Information System (INIS)

    The diagnostic accuracy of graded stress radiography in 26 patients with acute injury to the lateral ankle ligaments has been compared with findings at arthrography and surgery. Measuring talar tilt angles and anterior talar displacement over a range of pressures applied to the distal tibia using a commercially available stress device allows diagnostic distinction between isolated anterior talofibular ligament injury and a combined lesion that involves the calcaneofibular ligament. The results compare well with arthrographic and surgical findings. (orig.)

  17. Sex differences in physiological reactivity to acute psychosocial stress in adolescence

    OpenAIRE

    Ordaz, Sarah; Luna, Beatriz

    2012-01-01

    Females begin to demonstrate greater negative affective responses to stress than males in adolescence. This may reflect the concurrent emergence of underlying differences in physiological response systems, including corticolimbic circuitries, the hypothalamic—pituitary— adrenal axis (HPAA), and the autonomic nervous system (ANS). This review examines when sex differences in physiological reactivity to acute psychosocial stress emerge and the directionality of these differences over developmen...

  18. Acute stress induces increases in salivary IL-10 levels.

    Science.gov (United States)

    Szabo, Yvette Z; Newton, Tamara L; Miller, James J; Lyle, Keith B; Fernandez-Botran, Rafael

    2016-09-01

    The purpose of this study was to investigate the stress-reactivity of the anti-inflammatory cytokine, IL-10, in saliva and to determine how salivary IL-10 levels change in relation to those of IL-1β, a pro-inflammatory cytokine, following stress. Healthy young adults were randomly assigned to retrieve a negative emotional memory (n = 46) or complete a modified version of the Trier Social Stress Test (n = 45). Saliva samples were taken 10 min before (baseline) and 50 min after (post-stressor) onset of a 10-min stressor, and were assayed using a high sensitivity multiplex assay for cytokines. Measurable IL-10 levels (above the minimum detectable concentration) were found in 96% of the baseline samples, and 98% of the post-stressor samples. Flow rate-adjusted salivary IL-10 levels as well as IL-1β/IL-10 ratios showed moderate but statistically significant increases in response to stress. Measurement of salivary IL-10 and pro-/anti-inflammatory cytokine ratios may be useful, noninvasive tools, in stress research.

  19. Aged rats are hypo-responsive to acute restraint: implications for psychosocial stress in aging

    Directory of Open Access Journals (Sweden)

    Heather M Buechel

    2014-02-01

    Full Text Available Cognitive processes associated with prefrontal cortex and hippocampus decline with age and are vulnerable to disruption by stress. The stress/ stress hormone/ allostatic load hypotheses of brain aging posit that brain aging, at least in part, is the manifestation of life-long stress exposure. In addition, as humans age, there is a profound increase in the incidence of new onset stressors, many of which are psychosocial (e.g., loss of job, death of spouse, social isolation, and aged humans are well-understood to be more vulnerable to the negative consequences of such new-onset chronic psychosocial stress events. However, the mechanistic underpinnings of this age-related shift in chronic psychosocial stress response, or the initial acute phase of that chronic response, have been less well-studied. Here, we separated young (3 mo. and aged (21 mo. male F344 rats into control and acute restraint (an animal model of psychosocial stress groups (n = 9-12/ group. We then assessed hippocampus-associated behavioral, electrophysiological, and transcriptional outcomes, as well as blood glucocorticoid and sleep architecture changes. Aged rats showed characteristic water maze, deep sleep, transcriptome, and synaptic sensitivity changes compared to young. Young and aged rats showed similar levels of distress during the three hour restraint, as well as highly significant increases in blood glucocorticoid levels 21 hours after restraint. However, young, but not aged, animals responded to stress exposure with water maze deficits, loss of deep sleep and hyperthermia. These results demonstrate that aged subjects are hypo-responsive to new-onset acute psychosocial stress, which may have negative consequences for long-term stress adaptation and suggest that age itself may act as a stressor occluding the influence of new onset stressors.

  20. Aged rats are hypo-responsive to acute restraint: implications for psychosocial stress in aging.

    Science.gov (United States)

    Buechel, Heather M; Popovic, Jelena; Staggs, Kendra; Anderson, Katie L; Thibault, Olivier; Blalock, Eric M

    2014-01-01

    Cognitive processes associated with prefrontal cortex and hippocampus decline with age and are vulnerable to disruption by stress. The stress/stress hormone/allostatic load hypotheses of brain aging posit that brain aging, at least in part, is the manifestation of life-long stress exposure. In addition, as humans age, there is a profound increase in the incidence of new onset stressors, many of which are psychosocial (e.g., loss of job, death of spouse, social isolation), and aged humans are well-understood to be more vulnerable to the negative consequences of such new-onset chronic psychosocial stress events. However, the mechanistic underpinnings of this age-related shift in chronic psychosocial stress response, or the initial acute phase of that chronic response, have been less well-studied. Here, we separated young (3 month) and aged (21 month) male F344 rats into control and acute restraint (an animal model of psychosocial stress) groups (n = 9-12/group). We then assessed hippocampus-associated behavioral, electrophysiological, and transcriptional outcomes, as well as blood glucocorticoid and sleep architecture changes. Aged rats showed characteristic water maze, deep sleep, transcriptome, and synaptic sensitivity changes compared to young. Young and aged rats showed similar levels of distress during the 3 h restraint, as well as highly significant increases in blood glucocorticoid levels 21 h after restraint. However, young, but not aged, animals responded to stress exposure with water maze deficits, loss of deep sleep and hyperthermia. These results demonstrate that aged subjects are hypo-responsive to new-onset acute psychosocial stress, which may have negative consequences for long-term stress adaptation and suggest that age itself may act as a stressor occluding the influence of new onset stressors.

  1. ANALYTICAL SOLUTIONS OF THERMAL STRESS DISTRIBUTION IN PLASTIC ENCAPSULATED INTEGRATED CIRCUIT PACKAGES

    Institute of Scientific and Technical Information of China (English)

    刘玉岚; 王彪; 王殿富

    2003-01-01

    Due to the mismatch in the coefficients of thermal expansion of slicon chip and the surrounding plastic encapsulation materials, the induced thermal stress is the main cause for die and encapsulant rupture. The corner geometry is simplified as the semi-infinite wedge. Then the two-dimensional thermal stress distribution around the corner was obtained explicitly. Based on the stress calculation, the strain energy density factor criterion is used to evaluate the strength of the structure, which can not only give the critical condition for the stresses, but also determine the direction of fracture initiation around the corner.

  2. Social stress modulates the cortisol response to an acute stressor in rainbow trout (Oncorhynchus mykiss).

    Science.gov (United States)

    Jeffrey, J D; Gollock, M J; Gilmour, K M

    2014-01-15

    In rainbow trout (Oncorhynchus mykiss) of subordinate social status, circulating cortisol concentrations were elevated under resting conditions but the plasma cortisol and glucose responses to an acute stressor (confinement in a net) were attenuated relative to those of dominant trout. An in vitro head kidney preparation, and analysis of the expression of key genes in the stress axis prior to and following confinement in a net were then used to examine the mechanisms underlying suppression of the acute cortisol stress response in trout experiencing chronic social stress. With porcine adrenocorticotropic hormone (ACTH) as the secretagogue, ACTH-stimulated cortisol production was significantly lower for head kidney preparations from subordinate trout than for those from dominant trout. Dominant and subordinate fish did not, however, differ in the relative mRNA abundance of melanocortin-2 receptor (MC2R), steroidogenic acute regulatory protein (StAR) or cytochrome P450 side chain cleavage enzyme (P450scc) within the head kidney, although the relative mRNA abundance of these genes was significantly higher in both dominant and subordinate fish than in sham trout (trout that did not experience social interactions but were otherwise treated identically to the dominant and subordinate fish). The relative mRNA abundance of all three genes was significantly higher in trout exposed to an acute net stressor than under control conditions. Upstream of cortisol production in the stress axis, plasma ACTH concentrations were not affected by social stress, nor was the relative mRNA abundance of the binding protein for corticotropin releasing factor (CRF-BP). The relative mRNA abundance of CRF in the pre-optic area of subordinate fish was significantly higher than that of dominant or sham fish 1h after exposure to the stressor. Collectively, the results indicate that chronic social stress modulates cortisol production at the level of the interrenal cells, resulting in an attenuated

  3. Acute stress-induced antinociception is cGMP-dependent but heme oxygenase-independent

    Directory of Open Access Journals (Sweden)

    P.G. Carvalho-Costa

    2014-12-01

    Full Text Available Endogenous carbon monoxide (CO, which is produced by the enzyme heme oxygenase (HO, participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3′,5′-cyclic guanosine monophosphate (cGMP. In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group using the analgesia index (AI in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ blocked the increase in the AI induced by acute stress.

  4. Acute stress-induced antinociception is cGMP-dependent but heme oxygenase-independent

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho-Costa, P.G. [Programa de Graduação em Psicobiologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Branco, L.G.S. [Departamento de Morfologia, Fisiologia e Patologia Básica, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Leite-Panissi, C.R.A. [Programa de Graduação em Psicobiologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Departamento de Morfologia, Fisiologia e Patologia Básica, Faculdade de Odontologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

    2014-09-19

    Endogenous carbon monoxide (CO), which is produced by the enzyme heme oxygenase (HO), participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3′,5′-cyclic guanosine monophosphate (cGMP). In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group) using the analgesia index (AI) in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) blocked the increase in the AI induced by acute stress.

  5. Acute stress-induced antinociception is cGMP-dependent but heme oxygenase-independent

    International Nuclear Information System (INIS)

    Endogenous carbon monoxide (CO), which is produced by the enzyme heme oxygenase (HO), participates as a neuromodulator in physiological processes such as thermoregulation and nociception by stimulating the formation of 3′,5′-cyclic guanosine monophosphate (cGMP). In particular, the acute physical restraint-induced fever of rats can be blocked by inhibiting the enzyme HO. A previous study reported that the HO-CO-cGMP pathway plays a key phasic antinociceptive role in modulating noninflammatory acute pain. Thus, this study evaluated the involvement of the HO-CO-cGMP pathway in antinociception induced by acute stress in male Wistar rats (250-300 g; n=8/group) using the analgesia index (AI) in the tail flick test. The results showed that antinociception induced by acute stress was not dependent on the HO-CO-cGMP pathway, as neither treatment with the HO inhibitor ZnDBPG nor heme-lysinate altered the AI. However, antinociception was dependent on cGMP activity because pretreatment with the guanylate cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) blocked the increase in the AI induced by acute stress

  6. Residual stress field and thermal relaxation behavior of shot-peened TC4-DT titanium alloy

    International Nuclear Information System (INIS)

    Shot peening is an effective surface treatment method, which can improve the fatigue properties of metallic materials. In the present paper, the residual compressive stress field induced in TC4-DT titanium alloy under different shot peening conditions and the thermal relaxation behaviors of shot-peened TC4-DT were discussed. The shot peening can cause residual compressive stress on the material surface compared to un-peened materials. The subsurface residual stress distributions of original and shot-peened specimens were measured by an X-ray diffraction method. The residual compressive stress profiles accord with the characteristic curve of residual stress field. The maximum residual compressive stress is located at subsurface layer. Surface roughness also increases with increasing shot peening intensity. There is relaxation of residual compressive stress during temperature. Thermal relaxation behavior of residual stress was studied at 150 and 300 deg. C with different ageing time. The residual stress relaxation is influenced by temperature and time during ageing. Thermal relaxation of residual stress is a thermal recovery process. The relaxation process of thermal residual stress is analyzed by applying the Zener-Wert-Avrami function.

  7. The Additive Benefit of Hypnosis and Cognitive-Behavioral Therapy in Treating Acute Stress Disorder

    Science.gov (United States)

    Bryant, Richard A.; Moulds, Michelle L.; Guthrie, Rachel M.; Nixon, Reginald D. V.

    2005-01-01

    This research represents the first controlled treatment study of hypnosis and cognitive- behavioral therapy (CBT) of acute stress disorder (ASD). Civilian trauma survivors (N = 87) who met criteria for ASD were randomly allocated to 6 sessions of CBT, CBT combined with hypnosis (CBT-hypnosis), or supportive counseling (SC). CBT comprised exposure,…

  8. Acute and reversible cardiomyopathy provoked by stress in a Chinese woman

    Institute of Scientific and Technical Information of China (English)

    KANG Lian-ming; ZHANG Jian; DOU Ke-fei; XU Zhi-min; GAO Xiao-jin; YANG Yue-jin

    2008-01-01

    @@ Areversible cardiomyopathy triggered by psychologically stressful events occurs in older women and may mimic evolving acute myocardial infarction or coronary syndrome.This condition is characterized by a distinctive form of systolic dysfunction that predominantly affects the distal left ventricle chamber and a favourable outcome with appropriate medical therapy.

  9. Family Stress Management Following Acute Myocardial Infarction: An Educational and Skills Training Intervention Program.

    Science.gov (United States)

    Nelson, David V.; Cleveland, Sidney E.; Baer, Paul E.

    1998-01-01

    Provides a conceptual background for specific behavioral-therapy approach to family stress management in dealing with the sequelae of acute myocardial infarction for all family members with the goal of reducing morbidity for all family members as they cope with ongoing survivorship issues. Describes the program and discusses its pilot…

  10. Glucose intolerance induced by blockade of central FGF receptors is linked to an acute stress response

    Directory of Open Access Journals (Sweden)

    Jennifer M. Rojas

    2015-08-01

    Conclusions: The effect of acute inhibition of central FGFR signaling to impair glucose tolerance likely involves a stress response associated with pronounced, but transient, sympathoadrenal activation and an associated reduction of insulin secretion. Whether this effect is a true consequence of FGFR blockade or involves an off-target effect of the FGFR inhibitor requires additional study.

  11. Salivary MUC5B-mediated adherence (ex vivo) of Heliocobacter pylori during acute stress.

    NARCIS (Netherlands)

    J.A. Bosch; E.J.C. de Geus; T.J.M. Ligtenberg; K. Nazmi; E.C.I. Veerman; J. Hoogstraten; A.V. Amerongen Nieuwland

    2000-01-01

    Biochemical host defenses at mucosal sites, such as the oral cavity, play a key role in the regulation of microbial ecology and the prevention of infectious disease. This study investigated the effects of acute stress on the salivary levels of the carbohydrate structure sulfo-Lewis-super(a ) (SL), w

  12. Acute exercise improves endothelial function despite increasing vascular resistance during stress in smokers and nonsmokers.

    Science.gov (United States)

    Rooks, Cherie R; McCully, Kevin K; Dishman, Rod K

    2011-09-01

    The present study examined the effect of acute exercise on flow mediated dilation (FMD) and reactivity to neurovascular challenges among female smokers and nonsmokers. FMD was determined by arterial diameter, velocity, and blood flow measured by Doppler ultrasonography after forearm occlusion. Those measures and blood pressure and heart rate were also assessed in response to forehead cold and the Stroop Color-Word Conflict Test (CWT) before and after 30 min of rest or an acute bout of cycling exercise (∼50% VO₂ peak). Baseline FMD and stress responses were not different between smokers and nonsmokers. Compared to passive rest, exercise increased FMD and decreased arterial velocity and blood flow responses during the Stroop CWT and forehead cold in both groups. Overall, acute exercise improved endothelial function among smokers and nonsmokers despite increasing vascular resistance and reducing limb blood flow during neurovascular stress. PMID:21457274

  13. Factors Influencing Residual Stresses in Yttria Stabilized Zirconia Thermal Barrier Coatings

    Science.gov (United States)

    McGrann, Roy T. R.; Rybicki, Edmund F.; Shadley, John R.; Brindley, William J.

    1997-01-01

    To improve gas turbine and diesel engine performance using thermal barrier coatings (TBC's) requires an understanding of the factors that influence the in-service behavior of thermal barrier coatings. One of the many factors related to coating performance is the state of stress in the coating. The total stress state is composed of the stresses due to the in-service loading history and the residual stresses. Residual stresses have been shown to affect TBC life, the bond strength of thermal spray coatings, and the fatigue life of tungsten carbide coatings. Residual stresses are first introduced in TBC's by the spraying process due to elevated temperatures during processing and the difference in coefficients of thermal expansion of the top coat, bond coat, and substrate. Later, the residual stresses can be changed by the in-service temperature history due to a number of time and temperature dependent mechanisms, such as oxidation, creep, and sintering. Silica content has also been shown to affect sintering and the cyclic life of thermal barrier coatings. Thus, it is important to understand how the spraying process, the in-service thermal cycles, and the silica content can create and alter residual stresses in thermal barrier coatings.

  14. ANALYSIS OF THERMAL-ELASTIC STRESS OF WHEEL-RAIL IN ROLLING-SLIDING CONTACT

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; JIN Xuesong; ZHAI Wanming

    2007-01-01

    A coupling thermo-mechanical model of wheel/rail in rolling-sliding contact is put forward using finite element method. The normal contact pressure is idealized as the Hertzian distribution, and the tangential force presented by Carter is used. In order to obtain thermal-elastic stress, the thermal-elastic plane stress problem is transformed to an elastic plane stress problem with equivalent fictitious thermal body force and fictitious boundary distributed force. The temperature rise and thermal-elastic stress of wheel and rail in rolling-sliding are analyzed. The non-steady state heat transfer between the contact surfaces of wheel and rail, heat-convection and radiation between the wheel/rail and the ambient are taken into consideration. The influences of the wheel rolling speed and wear rate For rolling-sliding case, the thermal stress in the thin layer near the contact patch due to the friction temperature rise is severe. The higher rolling speed leads to the lower friction temperature rise and wheel rise quickly in the initial sliding stage, and then get into a steady state gradually. The expansion of the contact patch, due to material wear, can affect the friction temperature rise and the thermal stress during wear process. The higher wear rate generates lower stress. The results can help understand the influence of friction temperature and thermal-elastic stress on wheel and rail damage.

  15. Coupling Mechanism of Electromagnetic Field and Thermal Stress on Drosophila melanogaster.

    Science.gov (United States)

    Zhang, Zi-Yan; Zhang, Jing; Yang, Chuan-Jun; Lian, Hui-Yong; Yu, Hui; Huang, Xiao-Mei; Cai, Peng

    2016-01-01

    Temperature is an important factor in research on the biological effects of extremely low-frequency electromagnetic field (ELF-EMF), but interactions between ELF-EMF and temperature remain unknown. The effects of ELF-EMF (50 Hz, 3 mT) on the lifespan, locomotion, heat shock response (HSR), and oxidative stress (OS) of Canton-Special (CS) and mutant w1118 flies were investigated at 25°C and 35°C (thermal stress). Results showed that thermal stress accelerated the death rates of CS and w1118 flies, shortened their lifespan, and influenced their locomotion rhythm and activity. The upregulated expression levels of heat shock protein (HSP) 22, HSP26, and HSP70 indicated that HSR was enhanced. Thermal stress-induced OS response increased malondialdehyde content, enhanced superoxide dismutase activity, and decreased reactive oxygen species level. The effects of thermal stress on the death rates, lifespan, locomotion, and HSP gene expression of flies, especially w1118 line, were also enhanced by ELF-EMF. In conclusion, thermal stress weakened the physiological function and promoted the HSR and OS of flies. ELF-EMF aggravated damages and enhanced thermal stress-induced HSP and OS response. Therefore, thermal stress and ELF-EMF elicited a synergistic effect. PMID:27611438

  16. Coupling Mechanism of Electromagnetic Field and Thermal Stress on Drosophila melanogaster

    Science.gov (United States)

    Yang, Chuan-Jun; Lian, Hui-Yong; Yu, Hui; Huang, Xiao-Mei; Cai, Peng

    2016-01-01

    Temperature is an important factor in research on the biological effects of extremely low-frequency electromagnetic field (ELF-EMF), but interactions between ELF-EMF and temperature remain unknown. The effects of ELF-EMF (50 Hz, 3 mT) on the lifespan, locomotion, heat shock response (HSR), and oxidative stress (OS) of Canton-Special (CS) and mutant w1118 flies were investigated at 25°C and 35°C (thermal stress). Results showed that thermal stress accelerated the death rates of CS and w1118 flies, shortened their lifespan, and influenced their locomotion rhythm and activity. The upregulated expression levels of heat shock protein (HSP) 22, HSP26, and HSP70 indicated that HSR was enhanced. Thermal stress-induced OS response increased malondialdehyde content, enhanced superoxide dismutase activity, and decreased reactive oxygen species level. The effects of thermal stress on the death rates, lifespan, locomotion, and HSP gene expression of flies, especially w1118 line, were also enhanced by ELF-EMF. In conclusion, thermal stress weakened the physiological function and promoted the HSR and OS of flies. ELF-EMF aggravated damages and enhanced thermal stress-induced HSP and OS response. Therefore, thermal stress and ELF-EMF elicited a synergistic effect. PMID:27611438

  17. Elastic-Plastic Thermal Stress Analysis of a High-Pressure Cryogenic Storage Tank

    Science.gov (United States)

    Barker, J. Mark; Field, Robert E. (Technical Monitor)

    2003-01-01

    The thermal stresses on a cryogenic storage tank contribute strongly to the state of stress of the tank material and its ability to withstand operational stresses. These thermal stresses also affect the growth of any surface damage that might occur in the tank walls. These stresses are particularly of concern during the initial cooldown period for a new tank placed into service, and during any subsequent thermal cycles. A previous preliminary elastic analysis showed that the thermal stress on the inner wall would reach approximately 1,000MPa (145,000 psi). This stress far exceeds the ASTM specified room temperature values for both yield (170MPa) and ultimate (485 MPa) strength for 304L stainless steel. The present analysis determines the thermal stresses using an elastic-plastic model. The commercial software application ANSYS was used to determine the transient spatial temperature profile and the associated spatial thermal stress profiles in a segment of a thick-walled vessel during a typical cooldown process. A strictly elastic analysis using standard material properties for 304L stainless steel showed that the maximum thermal stress on the inner and outer walls was approximately 960 MPa (tensile) and - 270 MPa (compressive) respectively. These values occurred early in the cooldown process, but at different times, An elastic-plastic analysis showed significantly reducing stress, as expected due to the plastic deformation of the material. The maximum stress for the inner wall was approximately 225 MPa (tensile), while the maximum stress for the outer wall was approximately - 130 MPa (compressive).

  18. Stress and parental care: Prolactin responses to acute stress throughout the breeding cycle in a long-lived bird.

    Science.gov (United States)

    Riou, Samuel; Chastel, Olivier; Lacroix, André; Hamer, Keith C

    2010-08-01

    While the role of corticosterone in mediating the response of birds to acute stress is well established, it has recently been proposed that a decrease in prolactin levels following stress may complement corticosterone in redirecting resources away from breeding activities and towards behaviors promoting immediate survival. Here, for the first time, we detail changes in the prolactin stress response of birds throughout the breeding cycle. We then discuss the modulation of the corticosterone and prolactin stress responses over successive stages of breeding, differing in reproductive value and parental effort. In a long-lived Procellariiform seabird, the Manx shearwater Puffinus puffinus, we found that prolactin levels decreased in response to acute stress during incubation and mid chick-rearing but increased in response to stress during late chick-rearing and in non parenting birds, a pattern similar to that previously described for mammals. The high corticosterone stress response in pre-breeders was consistent with predictions based on reproductive value, but a similar response during late chick-rearing was not. This probably reflected foraging effort and a heightened importance of the parents' own nutritional status at this stage of the season, in advance of post-breeding migration. We also found that baseline prolactin levels were maintained at high levels during chick-rearing and were only slightly lower during late chick-rearing and in failed breeders and non-breeders. These data suggest that prolactin may play a role in nestling care long beyond the brooding phase, that this is not due to birds spending long periods away from the colony and that prolactin secretion may be necessary for nest-guarding behavior.

  19. The implicit affiliation motive moderates cortisol responses to acute psychosocial stress in high school students.

    Science.gov (United States)

    Wegner, Mirko; Schüler, Julia; Budde, Henning

    2014-10-01

    It has been previously shown that the implicit affiliation motive - the need to establish and maintain friendly relationships with others - leads to chronic health benefits. The underlying assumption for the present research was that the implicit affiliation motive also moderates the salivary cortisol response to acute psychological stress when some aspects of social evaluation and uncontrollability are involved. By contrast we did not expect similar effects in response to exercise as a physical stressor. Fifty-nine high school students aged M=14.8 years were randomly assigned to a psychosocial stress (publishing the results of an intelligence test performed), a physical stress (exercise intensity of 65-75% of HRmax), and a control condition (normal school lesson) each lasting 15min. Participants' affiliation motives were assessed using the Operant Motive Test and salivary cortisol samples were taken pre and post stressor. We found that the strength of the affiliation motive negatively predicted cortisol reactions to acute psychosocial but not to physical stress when compared to a control group. The results suggest that the affiliation motive buffers the effect of acute psychosocial stress on the HPA axis. PMID:25016451

  20. The implicit affiliation motive moderates cortisol responses to acute psychosocial stress in high school students.

    Science.gov (United States)

    Wegner, Mirko; Schüler, Julia; Budde, Henning

    2014-10-01

    It has been previously shown that the implicit affiliation motive - the need to establish and maintain friendly relationships with others - leads to chronic health benefits. The underlying assumption for the present research was that the implicit affiliation motive also moderates the salivary cortisol response to acute psychological stress when some aspects of social evaluation and uncontrollability are involved. By contrast we did not expect similar effects in response to exercise as a physical stressor. Fifty-nine high school students aged M=14.8 years were randomly assigned to a psychosocial stress (publishing the results of an intelligence test performed), a physical stress (exercise intensity of 65-75% of HRmax), and a control condition (normal school lesson) each lasting 15min. Participants' affiliation motives were assessed using the Operant Motive Test and salivary cortisol samples were taken pre and post stressor. We found that the strength of the affiliation motive negatively predicted cortisol reactions to acute psychosocial but not to physical stress when compared to a control group. The results suggest that the affiliation motive buffers the effect of acute psychosocial stress on the HPA axis.

  1. Habitat pollution and thermal regime modify molecular stress responses to elevated temperature in freshwater mussels (Anodonta anatina: Unionidae)

    Energy Technology Data Exchange (ETDEWEB)

    Falfushynska, H.; Gnatyshyna, L.; Yurchak, I. [Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, Kryvonosa Str 2, 46027 Ternopil (Ukraine); Ivanina, A. [Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223 (United States); Stoliar, O. [Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, Kryvonosa Str 2, 46027 Ternopil (Ukraine); Sokolova, I., E-mail: isokolov@uncc.edu [Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223 (United States)

    2014-12-01

    Elevated temperature and pollution are common stressors in freshwater ecosystems. We study cellular stress response to acute warming in Anodonta anatina (Unionidae) from sites with different thermal regimes and pollution levels: a pristine area and an agriculturally polluted site with normal temperature regimes (F and A, respectively) and a polluted site with elevated temperature (N) from the cooling pond of an electrical power plant. Animals were exposed to different temperatures for 14 days and stress response markers were measured in gills, digestive gland and hemocytes. Mussels from site N and A had elevated background levels of lactate dehydrogenase activity indicating higher reliance on anaerobic metabolism for ATP production and/or redox maintenance. Exposure to 25 °C and 30 °C induced oxidative stress (indicated by elevated levels of lipid peroxidation products) in digestive gland and gills of mussels from A and F sites, while in mussels from N sites elevated oxidative stress was only apparent at 30 °C. Temperature-induced changes in levels of antioxidants (superoxide dismutase, metallothioneins and glutathione) were tissue- and population-specific. Acute warming led to destabilization of lysosomal membranes and increased frequencies of nuclear lesions in mussels from F and A sites but not in their counterparts from N site. Elevated temperature led to an increase in the frequency of micronuclei in hemocytes in mussels from F and A sites at 25 °C and 30 °C and in mussels from N site at 30 °C. The mussels from N site also demonstrated better survival at elevated temperature (30 °C) than their counterparts from the F and A sites. Taken together, these data indicate that long-term acclimation and/or adaptation of A. anatina to elevated temperatures result in increased thermotolerance and alleviate stress response to moderate temperature rise. In contrast, extreme warming (30 °C) is harmful to mussels from all populations indicating limit to this induced

  2. Habitat pollution and thermal regime modify molecular stress responses to elevated temperature in freshwater mussels (Anodonta anatina: Unionidae)

    International Nuclear Information System (INIS)

    Elevated temperature and pollution are common stressors in freshwater ecosystems. We study cellular stress response to acute warming in Anodonta anatina (Unionidae) from sites with different thermal regimes and pollution levels: a pristine area and an agriculturally polluted site with normal temperature regimes (F and A, respectively) and a polluted site with elevated temperature (N) from the cooling pond of an electrical power plant. Animals were exposed to different temperatures for 14 days and stress response markers were measured in gills, digestive gland and hemocytes. Mussels from site N and A had elevated background levels of lactate dehydrogenase activity indicating higher reliance on anaerobic metabolism for ATP production and/or redox maintenance. Exposure to 25 °C and 30 °C induced oxidative stress (indicated by elevated levels of lipid peroxidation products) in digestive gland and gills of mussels from A and F sites, while in mussels from N sites elevated oxidative stress was only apparent at 30 °C. Temperature-induced changes in levels of antioxidants (superoxide dismutase, metallothioneins and glutathione) were tissue- and population-specific. Acute warming led to destabilization of lysosomal membranes and increased frequencies of nuclear lesions in mussels from F and A sites but not in their counterparts from N site. Elevated temperature led to an increase in the frequency of micronuclei in hemocytes in mussels from F and A sites at 25 °C and 30 °C and in mussels from N site at 30 °C. The mussels from N site also demonstrated better survival at elevated temperature (30 °C) than their counterparts from the F and A sites. Taken together, these data indicate that long-term acclimation and/or adaptation of A. anatina to elevated temperatures result in increased thermotolerance and alleviate stress response to moderate temperature rise. In contrast, extreme warming (30 °C) is harmful to mussels from all populations indicating limit to this induced

  3. Having your cake and eating it too: A habit of comfort food may link chronic social stress exposure and acute stress-induced cortisol hyporesponsiveness.

    Science.gov (United States)

    Stress has been tied to changes in eating behavior and food choice. Previous studies in rodents have shown that chronic stress increases palatable food intake which, in turn, increases mesenteric fat and inhibits acute stress-induced hypothalamic-pituitary-adrenal (HPA) axis activity. The effect of...

  4. The Latent Factor Structure of Acute Stress Disorder following Bank Robbery

    DEFF Research Database (Denmark)

    Hansen, M.; Lasgaard, M.; Elklit, A.

    2013-01-01

    OBJECTIVE: Acute stress disorder (ASD) was introduced into the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) to identify posttraumatic stress reactions occurring within the first month after a trauma and thus help...... for the ASD diagnosis in the pending DSM-5, there is a profound need for empirical studies that investigate the latent structure of ASD prior to the DSM-5 being finalized. DESIGN: Based on previous factor analytic research, the DSM-IV, and the proposed DSM-5 formulation of ASD, four different models...... of the latent structure of ASD were specified and estimated. METHOD: The analyses were based on a national study of bank robbery victims (N = 450) using the acute stress disorder scale. RESULTS: The results of the confirmatory factor analyses showed that the DSM-IV model provided the best fit to the data. Thus...

  5. Acute stress increases neuropsin mRNA expression in the mouse hippocampus through the glucocorticoid pathway.

    Science.gov (United States)

    Harada, Akiko; Shiosaka, Sadao; Ishikawa, Yasuyuki; Komai, Shoji

    2008-05-01

    Stress affects synaptic plasticity and may alter various types of behaviour, including anxiety or memory formation. In the present study, we examined the effects of acute stress (1 h restraint with or without tail-shock) on mRNA levels of a plasticity-related serine protease neuropsin (NP) in the hippocampus using semiquantitative RT-PCR and in situ hybridization. We found that NP mRNA expression was dramatically increased shortly after exposure to the acute restraint tail-shock stress and remained at high level for at least 24 h. The level of NP mRNA would be correlated to the elevated plasma concentration of the glucocorticoid corticosterone (CORT) and to the stress intensity. Application of CORT either onto primary cultured hippocampal neurons (5 nM) or in vivo to adrenalectomized (ADX) mice (10 mg/kg B.W., s.c.) mimicked the effect of stress and significantly elevated NP mRNA. These results suggest that the upregulation of NP mRNA after stress is CORT-dependent and point to a role for neuropsin in stress-induced neuronal plasticity.

  6. Repeated exposure to conditioned fear stress increases anxiety and delays sleep recovery following exposure to an acute traumatic stressor

    Directory of Open Access Journals (Sweden)

    Benjamin N Greenwood

    2014-10-01

    Full Text Available Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by humans, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to either no, mild (10, or severe (100 acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced REM and NREM sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep / wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep / wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.

  7. Understanding recovery in children following traffic-related injuries: Exploring acute traumatic stress reactions, child coping, and coping assistance

    OpenAIRE

    Marsac, Meghan L; Donlon, Katharine A.; Hildenbrand, Aimee K.; Winston, Flaura K.; Kassam-Adams, Nancy

    2013-01-01

    Millions of children incur potentially traumatic physical injuries every year. Most children recover well from their injury but many go on to develop persistent traumatic stress reactions. This study aimed to describe children’s coping and coping assistance (i.e., the ways in which parents and peers help children cope) strategies and to explore the association between coping and acute stress reactions following an injury. Children (N = 243) rated their acute traumatic stress reactions within ...

  8. Thermal stress dependence of magnetic hysteretic processes in core–shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dumitru, Ioan, E-mail: ioan.dumitru@uaic.ro; Astefanoaei, Iordana; Stancu, Alexandru

    2013-11-20

    The control of thermal stresses in the core–shell structures is an important task in order to understand their temperature dependent magnetization processes. This paper is dedicated to a theoretical and micromagnetic study of the thermal stresses on the hysteretic processes in core–shell nanoparticles. The analytical model can predict the thermal and elastic behavior of the core–shell nanoparticle supposed to a forced cooling process. The temperature and thermal stresses values obtained by direct computation from the analytical model were used to evaluate the magneto-elastic energy of the core–shell system. A micromagnetic model was used to compute the equilibrium positions of the particle magnetization as function of the applied field. The model allows an evaluation of the increase of the particle coercive field and of the blocking temperature as an effect of the thermal stress.

  9. Heat storage rate and acute fatigue in rats

    OpenAIRE

    L.O.C. Rodrigues; Oliveira, A.; Lima, N.R.V.; C.A. Machado-Moreira

    2003-01-01

    Thermal environmental stress can anticipate acute fatigue during exercise at a fixed intensity (%VO2max). Controversy exists about whether this anticipation is caused by the absolute internal temperature (Tint, ºC), by the heat storage rate (HSR, cal/min) or by both mechanisms. The aim of the present study was to study acute fatigue (total exercise time, TET) during thermal stress by determining Tint and HSR from abdominal temperature. Thermal environmental stress was controlled in an environ...

  10. Investigation of Coating Layer to Reduce Thermal Stresses in Steel Fiber Reinforced Aluminum Metal Matrix Composite

    OpenAIRE

    OKUMUŞ, Fuat

    2011-01-01

    In this study, by using coating layers to reduce thermal stresses in the metal matrix composites with a mismatch in coefficients of thermal expansions of fiber and matrix is investigated. The thermoelastic solutions based on a three cylinder model are deformed. It is shown that the effectiveness of the layer can be defined by the product of its cofficients of thermal expansions and thickness and that a compensating layer with a sufficiently high coefficient of thermal expansions can reduce th...

  11. Changes of central haemodynamic parameters during mental stress and acute bouts of static and dynamic exercise.

    Science.gov (United States)

    Lydakis, C; Momen, A; Blaha, C; Gugoff, S; Gray, K; Herr, M; Leuenberger, U A; Sinoway, L I

    2008-05-01

    Chronic dynamic (aerobic) exercise decreases central arterial stiffness, whereas chronic resistance exercise evokes the opposite effect. Nevertheless, there is little information available on the effects of acute bouts of exercise. Also, there is limited data showing an increase of central arterial stiffness during acute mental stress. This study aimed to determine the effect of acute mental and physical (static and dynamic exercise) stress on indices of central arterial stiffness. Fifteen young healthy volunteers were studied. The following paradigms were performed: (1) 2 min of mental arithmetic, (2) short bouts (20 s) of static handgrip at 20 and 70% of maximal voluntary contraction (MVC), (3) fatiguing handgrip at 40% MVC and (4) incremental dynamic knee extensor exercise. Central aortic waveforms were assessed using SphygmoCor software. As compared to baseline, pulse wave transit time decreased significantly for all four interventions indicating that central arterial stiffness increased. During fatiguing handgrip there was a fall in the ratio of peripheral to central pulse pressure from 1.69+/-0.02 at baseline to 1.56+/-0.05 (Pfatiguing handgrip protocols, whereas there was no change in the knee extensor protocol. We conclude that (1) during all types of acute stress tested in this study (including dynamic exercise) estimated central stiffness increased, (2) during static exercise the workload posed on the left ventricle (expressed as change in central pulse pressure) is relatively higher than that posed during dynamic exercise (given the same pulse pressure change in the periphery). PMID:18273040

  12. Effect of thermal stress on the performance of HgCdTe/Si diodes and FPAs

    International Nuclear Information System (INIS)

    As a typical hetero-epitaxial material, the HgCdTe film which directly grows on the Si substrate possesses great residual stress for the large lattice and thermal expansion mismatch. Thermal stress caused by the thermal expansion mismatch dominates the stress mechanism after growth and seriously affects the device performance. In this paper, the performance of the HgCdTe/Si material, diodes and focal plane arrays under different thermal stress condition was studied. The experimental results indicate that the performance regularly changes with the thermal stress and all the results can be duplicated and recoverable. By analyzing the changes of the energy band under different stress conditions, it was found that the stress in the HgCdTe film impacts the film's characteristics. The HgCdTe film with tensile stress exhibits higher electron mobility, while with the compressive stress, the film exhibits higher hole mobility than that of the bulk HgCdTe crystal. Finally, the theoretical analysis can explain the experimental results well. (paper)

  13. Post-stress rumination predicts HPA axis responses to repeated acute stress.

    Science.gov (United States)

    Gianferante, Danielle; Thoma, Myriam V; Hanlin, Luke; Chen, Xuejie; Breines, Juliana G; Zoccola, Peggy M; Rohleder, Nicolas

    2014-11-01

    Failure of the hypothalamus-pituitary-adrenal (HPA) axis to habituate to repeated stress exposure is related with adverse health outcomes, but our knowledge of predictors of non-habituation is limited. Rumination, defined as repetitive and unwanted past-centered negative thinking, is related with exaggerated HPA axis stress responses and poor health outcomes. The aim of this study was to test whether post-stress rumination was related with non-habituation of cortisol to repeated stress exposure. Twenty-seven participants (n=13 females) were exposed to the Trier Social Stress Test (TSST) twice on consecutive afternoons. Post-stress rumination was measured after the first TSST, and HPA axis responses were assessed by measuring salivary cortisol 1 min before, and 1, 10, 20, 60, and 120 min after both TSSTs. Stress exposure induced HPA axis activation on both days, and this activation showed habituation indicated by lower responses to the second TSST (F=3.7, p=0.015). Post-stress rumination after the first TSST was associated with greater cortisol reactivity after the initial stress test (r=0.45, pHPA axis responses. This finding implicates rumination as one possible mechanism mediating maladaptive stress response patterns, and it might also offer a pathway through which rumination might lead to negative health outcomes.

  14. The evolution of the painful sensitivity in acute and chronic stress.

    Science.gov (United States)

    Cristea, A; Ciobanu, A; Stoenescu, M; Rusei, I

    1994-01-01

    The clinical research was made on two groups of young volunteer students. We considered stress consisting in chronic informational overexposure during the examination session and the acute stress from their emotions before a hard examination. The painful sensitivity was analysed by measuring the retraction time of the finger from water at 55 degrees C. The experimental research was made on a group of 100 male mice. The acute stress was performed by subjecting each mouse to swim (behavioral despair test). Painful sensitivity was determined by the test of the hot plate heated at 50 degrees C. Individuals with hyper (H) and hypo (h) painful sensitivity were selected for the tests. In chronic stress, the results proved increased painful sensitivity (hyperalgia) more important at "h" compared to "H" (p behaviors with opposite mechanisms involved in stress analgesia. This hypothesis is related with studies which demonstrate the involvement in stress analgesia of non-opioid monoaminergic mechanisms together with the opioid mechanisms (Lewis, 1980). PMID:8640371

  15. Acute stress in adulthood impoverishes social choices and triggers aggressiveness in preclinical models

    Directory of Open Access Journals (Sweden)

    Anne eNosjean

    2015-01-01

    Full Text Available Adult C57BL/6J mice are known to exhibit high level of social flexibility while mice lacking the β2 subunit of nicotinic receptors (β2-/- mice present social rigidity. We asked ourselves what would be the consequences of a restraint acute stress (45 min on social interactions in adult mice of both genotypes, hence the contribution of neuronal nicotinic receptors in this process. We therefore dissected social interaction complexity of stressed and not stressed dyads of mice in a social interaction task. We also measured plasma corticosterone levels in our experimental conditions. We showed that a single stress exposure occurring in adulthood reduced and disorganized social interaction complexity in both C57BL/6J and β2-/- mice. These stress-induced maladaptive social interactions involved alteration of distinct social categories and strategies in both genotypes, suggesting a dissociable impact of stress depending on the functioning of the cholinergic nicotinic system. In both genotypes, social behaviors under stress were coupled to aggressive reactions with no plasma corticosterone changes. Thus, aggressiveness appeared a general response independent of nicotinic function. We demonstrate here that a single stress exposure occurring in adulthood is sufficient to impoverish social interactions: stress impaired social flexibility in C57BL/6J mice whereas it reinforced β2-/- mice behavioral rigidity.

  16. On plane stress state and stress free deformation of thick plate with FGM interface under thermal loading

    Science.gov (United States)

    Szubartowski, Damian; Ganczarski, Artur

    2016-10-01

    This paper demonstrates the plane stress state and the stress free thermo-elastic deformation of FGM thick plate under thermal loading. First, the Sneddon-Lockett theorem on the plane stress state in an isotropic infinite thick plate is generalized for a case of FGM problem in which all thermo-mechanical properties are optional functions of depth co-ordinate. The proof is based on application of the Iljushin thermo-elastic potential to displacement type system of equations that reduces it to the plane stress state problem. Then an existence of the purely thermal deformation is proved in two ways: first, it is shown that the unique solution fulfils conditions of simultaneous constant temperature and linear gradation of thermal expansion coefficient, second, proof is based directly on stress type system of equations which straightforwardly reduces to compatibility equations for purely thermal deformation if only stress field is homogeneous in domain and at boundary. Finally, couple examples of application to an engineering problem are presented.

  17. Acclimation-dependent expression of heat shock protein 70 in Pacific abalone (Haliotis discus hannai Ino) and its acute response to thermal exposure

    Institute of Scientific and Technical Information of China (English)

    LI Jiaqi; HE Qingguo; SUN Hui; LIU Xiao

    2012-01-01

    Heat shock protein 70 (Hsp70) is one important member of heat shock protein (Hsp) family that is responsible for various stresses,especially thermal stress.Here we examined the response of Hsp70gene to both chronic and acute thermal exposure in Pacific abalone (Haliotis discus hannai Ino).For the chronic exposure,abalones were maintained at 8,12,20,and 30℃ for four months and their mRNA levels were measured.The highest mRNA level of Hsp70 gene relative to actin gene was detected in the 30℃-acclimated group,followed by the 8℃-acclimated group and then the 12℃- and 20℃-acclimated groups.After the long-term acclimation,gills from each of the above acclimation groups were dissected and exposed to different temperatures between 8℃ and 38℃ for 30 min.Hsp70 expression in gills acclimated to different temperatures responded differentially to the same temperature exposure.The incubation temperature that induced maximum Hsp70 mRNA expression was higher in the higher temperature acclimation groups than lower temperature groups.Pacific abalones could alter the expression pattern of Hsp70 gene according to environmental thermal conditions,through which they deal with the stress of thermal variations.

  18. Symptoms of Acute Posttraumatic Stress Disorder in Patients With Acute Hand Injuries

    NARCIS (Netherlands)

    Opsteegh, Lonneke; Reinders-Messelink, Heleen A.; Groothoff, Johan W.; Postema, Klass; Dijkstra, Pieter U.; van der Sluis, Corry K.

    2010-01-01

    Purpose Symptoms of posttraumatic stress disorder (PTSD) in patients with hand injuries may delay return to work, even when criteria of the Diagnostic and Statistical Manual of Mental Disorders-IV are not met. This study investigated which biomedical and psychosocial factors relate to symptoms of ac

  19. INFLUENCE OF ACUTE EXERCISE ON OXIDATIVE STRESS IN CHRONIC SMOKERS

    Directory of Open Access Journals (Sweden)

    Zehra Serdar

    2003-09-01

    Full Text Available The relative oxidative insult caused by exercise and smoking on biological systems are well documented, however, their cumulative influence needs to be clarified. In order to examine the collective effects of exercise and smoking on oxidant and antioxidant parameters, young male smokers (n=10 and non-smokers (n=10 made to perform a negative slope (10% cycling exercise for 30 minutes at individual load equivalent to 60% maximal oxygen consumption (VO2max. Pre- and post-exercise (post-ex haematocrit, haemoglobin, white blood cells, plasma malondialdehyde (MDA levels, protein carbonyl formation and non-HDL oxidation, erythrocyte superoxide dismutase (SOD and glutathione peroxidase (GPX activities, serum ceruloplasmin (CER and urinary cotinine concentrations were evaluated. Pre-ex CER and urinary cotinine concentrations of smokers were significantly higher (p<0.05 and p<0.01, respectively compared to that of non-smokers and pre-ex CER concentrations were significantly correlated with cotinine levels in all subjects (p<0.05. Significant (p<0.01 increases were observed in non-HDL oxidation following the exercise in both groups and the elevations were more pronounced in smokers. Pre-ex SOD and GPX activities were not different between the two groups, however post-ex enzyme activities were significantly reduced in smokers (p<0.05. MDA and protein carbonyl concentrations were not different between the two groups and there were not any significant changes due to exercise.In conclusion, according to the results of the present study, we suggest that erythrocyte antioxidants SOD and GPX and plasma non-HDL are more prone to the possible oxidant damage of acute physical exercise in chronic smokers.

  20. Depressive symptoms are associated with mental stress-induced myocardial ischemia after acute myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Jingkai Wei

    Full Text Available Depression is an adverse prognostic factor after an acute myocardial infarction (MI, and an increased propensity toward emotionally-driven myocardial ischemia may play a role. We aimed to examine the association between depressive symptoms and mental stress-induced myocardial ischemia in young survivors of an MI.We studied 98 patients (49 women and 49 men age 38-60 years who were hospitalized for acute MI in the previous 6 months. Patients underwent myocardial perfusion imaging at rest, after mental stress (speech task, and after exercise or pharmacological stress. A summed difference score (SDS, obtained with observer-independent software, was used to quantify myocardial ischemia under both stress conditions. The Beck Depression Inventory-II (BDI-II was used to measure depressive symptoms, which were analyzed as overall score, and as separate somatic and cognitive depressive symptom scores.There was a significant positive association between depressive symptoms and SDS with mental stress, denoting more ischemia. After adjustment for demographic and lifestyle factors, disease severity and medications, each incremental depressive symptom was associated with 0.14 points higher SDS. When somatic and cognitive depressive symptoms were examined separately, both somatic [β = 0.17, 95% CI: (0.04, 0.30, p = 0.01] and cognitive symptoms [β = 0.31, 95% CI: (0.07, 0.56, p = 0.01] were significantly associated with mental stress-induced ischemia. Depressive symptoms were not associated with ischemia induced by exercise or pharmacological stress.Among young post-MI patients, higher levels of both cognitive and somatic depressive symptoms are associated with a higher propensity to develop myocardial ischemia with mental stress, but not with physical (exercise or pharmacological stress.

  1. Acute iron overload and oxidative stress in brain

    International Nuclear Information System (INIS)

    An in vivo model in rat was developed by intraperitoneally administration of Fe-dextran to study oxidative stress triggered by Fe-overload in rat brain. Total Fe levels, as well as the labile iron pool (LIP) concentration, in brain from rats subjected to Fe-overload were markedly increased over control values, 6 h after Fe administration. In this in vivo Fe overload model, the ascorbyl (A·)/ascorbate (AH−) ratio, taken as oxidative stress index, was assessed. The A·/AH− ratio in brain was significantly higher in Fe-dextran group, in relation to values in control rats. Brain lipid peroxidation indexes, thiobarbituric acid reactive substances (TBARS) generation rate and lipid radical (LR·) content detected by Electron Paramagnetic Resonance (EPR), in Fe-dextran supplemented rats were similar to control values. However, values of nuclear factor-kappaB deoxyribonucleic acid (NFκB DNA) binding activity were significantly increased (30%) after 8 h of Fe administration, and catalase (CAT) activity was significantly enhanced (62%) 21 h after Fe administration. Significant enhancements in Fe content in cortex (2.4 fold), hippocampus (1.6 fold) and striatum (2.9 fold), were found at 6 h after Fe administration. CAT activity was significantly increased after 8 h of Fe administration in cortex, hippocampus and striatum (1.4 fold, 86, and 47%, respectively). Fe response in the whole brain seems to lead to enhanced NF-κB DNA binding activity, which may contribute to limit oxygen reactive species-dependent damage by effects on the antioxidant enzyme CAT activity. Moreover, data shown here clearly indicate that even though Fe increased in several isolated brain areas, this parameter was more drastically enhanced in striatum than in cortex and hippocampus. However, comparison among the net increase in LR· generation rate, in different brain areas, showed enhancements in cortex lipid peroxidation, without changes in striatum and hippocampus LR· generation rate after 6 h

  2. Acute iron overload and oxidative stress in brain.

    Science.gov (United States)

    Piloni, Natacha E; Fermandez, Virginia; Videla, Luis A; Puntarulo, Susana

    2013-12-01

    An in vivo model in rat was developed by intraperitoneally administration of Fe-dextran to study oxidative stress triggered by Fe-overload in rat brain. Total Fe levels, as well as the labile iron pool (LIP) concentration, in brain from rats subjected to Fe-overload were markedly increased over control values, 6h after Fe administration. In this in vivo Fe overload model, the ascorbyl (A)/ascorbate (AH(-)) ratio, taken as oxidative stress index, was assessed. The A/AH(-) ratio in brain was significantly higher in Fe-dextran group, in relation to values in control rats. Brain lipid peroxidation indexes, thiobarbituric acid reactive substances (TBARS) generation rate and lipid radical (LR) content detected by Electron Paramagnetic Resonance (EPR), in Fe-dextran supplemented rats were similar to control values. However, values of nuclear factor-kappaB deoxyribonucleic acid (NFκB DNA) binding activity were significantly increased (30%) after 8h of Fe administration, and catalase (CAT) activity was significantly enhanced (62%) 21h after Fe administration. Significant enhancements in Fe content in cortex (2.4 fold), hippocampus (1.6 fold) and striatum (2.9 fold), were found at 6h after Fe administration. CAT activity was significantly increased after 8h of Fe administration in cortex, hippocampus and striatum (1.4 fold, 86, and 47%, respectively). Fe response in the whole brain seems to lead to enhanced NF-κB DNA binding activity, which may contribute to limit oxygen reactive species-dependent damage by effects on the antioxidant enzyme CAT activity. Moreover, data shown here clearly indicate that even though Fe increased in several isolated brain areas, this parameter was more drastically enhanced in striatum than in cortex and hippocampus. However, comparison among the net increase in LR generation rate, in different brain areas, showed enhancements in cortex lipid peroxidation, without changes in striatum and hippocampus LR generation rate after 6h of Fe overload

  3. Assessment of oxidative stress in acute myeloid leukemia

    Directory of Open Access Journals (Sweden)

    Esfahani A

    2011-02-01

    Full Text Available "nBackground: Many chemotherapeutic regimens used in the treatment of cancer generate free radicals that may be a part of their beneficial effects. The aim of this study was to assess the oxidative status in patients undergoing chemotherapy for acute myeloid leukemia (AML."n "nMethods: Thirty-eight patients with AML (17 female and 21 male patients with a mean age 34.05±12.49 years were included in the study. All the patients received cytarabine and daunorubicin as their standard induction therapy. Serum levels of malondialdehyde (MDA, total antioxidant capacity (TAC, and also the erythrocyte superoxide dismutase and glutathione peroxidase activities were measured before and 14 days after chemotherapy."n "nResults: Plasma malondialdehyde concentrations increased significantly (from a former 2.68±0.89 nmol/ml to 3.14±1.29 nmol/ml 14 days post chemotherapy (p=0.04. Moreover, the total plasma antioxidant capacity changed from 1.09±0.15 mmol/L to 1.02±0.14 mmol/L (p=0.005. Erythrocyte superoxide dismutase and glutathione peroxidase activity decreased over time from 1157.24±543.61 U/gHb to 984.01±419.09 U/gHb (p=0.04 and 46.96±13.70 U/gHb to 41.40±6.44 U/gHb (p=0.02, respectively."n "nConclusion: In this study, an increase in malondialdehyde levels and a decrease in the levels of antioxidant enzymes and total antioxidant capacity were observed. It seems that chemotherapy by cytarabine and daunorubicin generates enormous amounts of free radicals in patients undergoing the treatment for AML. Use of antioxidant supplementation during chemotherapy i is discouraged as it may interfere with the generation of free radicals that may be a part of the therapeutic efficacy of these drugs.

  4. Optical stimulation of the hearing and deaf cochlea under thermal and stress confinement condition

    Science.gov (United States)

    Schultz, M.; Baumhoff, P.; Kallweit, N.; Sato, M.; Krüger, A.; Ripken, T.; Lenarz, T.; Kral, A.

    2014-03-01

    There is a controversy, to which extend cochlear stimulation with near infrared laser pulses at a wavelength of 1860 nm is based on optoacoustic stimulation of intact hair cells or -in contrast- is based on direct stimulation of the nerve cells in absence of functional hair cells. Thermal and stress confinement conditions apply, because of the pulse duration range (5 ns, 10 μs-20 ms) of the two lasers used. The dependency of the signal characteristics on pulse peak power and pulse duration was investigated in this study. The compound action potential (CAP) was measured during stimulation of the cochlea of four anaesthetized guinea pigs, which were hearing at first and afterwards acutely deafened using intracochlear neomycin-rinsing. For comparison hydrophone measurements in a water tank were performed to investigate the optoacoustic signals at different laser interaction regimes. With rising pulse peak power CAPs of the hearing animals showed first a threshold, then a positively correlated and finally a saturating dependency. CAPs also showed distinct responses at laser onset and offset separated with the pulse duration. At pulse durations shorter than physiological response times the signals merged. Basically the same signal characteristics were observed in the optoacoustic hydrophone measurements, scaled with the sensitivity and response time of the hydrophone. Taking together the qualitative correspondence in the signal response and the absence of any CAPs in deafened animals our results speak in favor of an optoacoustic stimulation of intact hair cells rather than a direct stimulation of nerve cells.

  5. Thermal stress analysis of the NASA Dryden hypersonic wing test structure

    Science.gov (United States)

    Morris, Glenn

    1990-01-01

    Present interest in hypersonic vehicles has resulted in a renewed interest in thermal stress analysis of airframe structures. While there are numerous texts and papers on thermal stress analysis, practical examples and experience on light gage aircraft structures are fairly limited. A research program has been undertaken at General Dynamics to demonstrate the present state of the art, verify methods of analysis, gain experience in their use, and develop engineering judgement in thermal stress analysis. The approach for this project has been to conduct a series of analyses of this sample problem and compare analysis results with test data. This comparison will give an idea of how to use our present methods of thermal stress analysis, and how accurate we can expect them to be.

  6. Micromechanics analysis of space simulated thermal deformations and stresses in continuous fiber reinforced composites

    Science.gov (United States)

    Bowles, David E.

    1990-01-01

    Space simulated thermally induced deformations and stresses in continuous fiber reinforced composites were investigated with a micromechanics analysis. The investigation focused on two primary areas. First, available explicit expressions for predicting the effective coefficients of thermal expansion (CTEs) for a composite were compared with each other, and with a finite element (FE) analysis, developed specifically for this study. Analytical comparisons were made for a wide range of fiber/matrix systems, and predicted values were compared with experimental data. The second area of investigation focused on the determination of thermally induced stress fields in the individual constituents. Stresses predicted from the FE analysis were compared to those predicted from a closed-form solution to the composite cylinder (CC) model, for two carbon fiber/epoxy composites. A global-local formulation, combining laminated plate theory and FE analysis, was used to determine the stresses in multidirectional laminates. Thermally induced damage initiation predictions were also made.

  7. Numerical Simulation of Transient Thermal Stress Field for Laser Metal Deposition Shaping

    Institute of Scientific and Technical Information of China (English)

    LONG Risheng; LIU Weijun

    2006-01-01

    To decrease thermal stress during laser metal deposition shaping (LMDS) process, it is of great importance to learn the transient thermal stress distribution regularities. Based on the "element life and death" technique of finite element analysis (FEA), a three-dimensional multi-track and multi-layer numerical simulation model for LMDS is developed with ANSYS parametric design language (APDL) for the first time, in which long-edge parallel reciprocating scanning paths is introduced. Through the model, detailed simulations of thermal stress during whole metal cladding process are conducted, the generation and distribution regularities of thermal stress are also discussed in detail. Using the same process parameters, the simulation results show good agreement with the features of samples which fabricated by LMDS.

  8. Thermal-stress effects on enhanced low-dose-rate sensitivity of linear bipolar circuits

    Energy Technology Data Exchange (ETDEWEB)

    SHANEYFELT,MARTY R.; SCHWANK,JAMES R.; WITCZAK,STEVEN C.; RIEWE,LEONARD CHARLES; WINOKUR,PETER S.; HASH,GERALD L.; PEASE,R.L.; FLEETWOOD,D.M.

    2000-02-17

    Thermal-stress effects are shown to have a significant impact on the enhanced low-dose-rate sensitivity of linear bipolar circuits. Implications of these results on hardness assurance testing and mechanisms are discussed.

  9. Effects of Prepubertal Acute Immobilization Stress on Serum Kisspeptin Level and Testis Histology in Rats.

    Science.gov (United States)

    Maalhagh, Mehrnoosh; Jahromi, Abdolreza Sotoodeh; Yusefi, Alireza; Razeghi, Ali; Zabetiyan, Hassan; Karami, Mohammad Yasin; Madani, Abdol Hossein

    2016-01-01

    Stress has inhibitory effect on HPG axis through increasing cortisol serum level. In this study, the effect of acute prepubertal stress on kisspeptin, which plays essential role in puberty achievement is assessed. To do this experimental study thirty immature healthy male wistar rats of 4 weeks old and without any symptoms of puberty were selected randomly. These rats were divided into three groups, randomly. Two groups were chosen as control and pretest and one as stress (test) group. Immobilization stress was applied for 10 days and serum level of cortisol, testosterone and kisspeptin were measured. Primary and secondary spermatocyte and sertoli cell evaluated and compared among groups. Mean serum level of kisspeptin in pretest group, control group and stress (test) group were 0.0381 ± 0.0079, 91.0500 ± 4.87430 and 15.2156 ± 3.88135 pg mL(-1) respectively. Serum level of kisspeptin had significant differences between three groups (p stress led to decrease in serum level of kisspeptin and testosterone in stress (test) group compared to control groups. Also stress caused a significant decrease in the numbers of secondary spermatocytes of the test group. PMID:26930799

  10. Numerical Simulation of Temperature Field and Thermal Stress Field of Work Roll During Hot Strip Rolling

    Institute of Scientific and Technical Information of China (English)

    LI Chang-sheng; YU Hai-liang; DENG Guan-yu; LIU Xiang-hua; WANG Guo-dong

    2007-01-01

    Based on the thermal conduction equations, the three-dimensional (3D) temperature field of a work roll was investigated using finite element method (FEM). The variations in the surface temperature of the work roll during hot strip rolling were described, and the thermal stress field of the work roll was also analyzed. The results showed that the highest roll surface temperature is 593 ℃, and the difference between the minimum and maximum values of thermal stress of the work roll surface is 145.7 MPa. Furthermore, the results of this analysis indicate that temperature and thermal stress are useful parameters for the investigation of roll thermal fatigue and also for improving the quality of strip during rolling.

  11. Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review.

    Science.gov (United States)

    Molnár, Gergő A; Kun, Szilárd; Sélley, Eszter; Kertész, Melinda; Szélig, Lívia; Csontos, Csaba; Böddi, Katalin; Bogár, Lajos; Miseta, Attila; Wittmann, István

    2016-01-01

    Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (pglucose product in non-diabetic septic cases (pRats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases. PMID:26785996

  12. Mucus Sugar Content Shapes the Bacterial Community Structure in Thermally Stressed Acropora muricata

    OpenAIRE

    Lee, Sonny T. M.; Davy, Simon K.; Tang, Sen-Lin; Kench, Paul S.

    2016-01-01

    It has been proposed that the chemical composition of a coral’s mucus can influence the associated bacterial community. However, information on this topic is rare, and non-existent for corals that are under thermal stress. This study therefore compared the carbohydrate composition of mucus in the coral Acropora muricata when subjected to increasing thermal stress from 26 to 31°C, and determined whether this composition correlated with any changes in the bacterial community. Results showed tha...

  13. Sleep quality but not sleep quantity effects on cortisol responses to acute psychosocial stress.

    Science.gov (United States)

    Bassett, Sarah M; Lupis, Sarah B; Gianferante, Danielle; Rohleder, Nicolas; Wolf, Jutta M

    2015-01-01

    Given the well-documented deleterious health effects, poor sleep has become a serious public health concern and increasing efforts are directed toward understanding underlying pathways. One potential mechanism may be stress and its biological correlates; however, studies investigating the effects of poor sleep on a body's capacity to deal with challenges are lacking. The current study thus aimed at testing the effects of sleep quality and quantity on cortisol responses to acute psychosocial stress. A total of 73 college-aged adults (44 females) were investigated. Self-reported sleep behavior was assessed via the Pittsburgh Sleep Quality Index and salivary cortisol responses to the Trier Social Stress Test were measured. In terms of sleep quality, we found a significant three-way interaction, such that relative to bad sleep quality, men who reported fairly good or very good sleep quality showed blunted or exaggerated cortisol responses, respectively, while women's stress responses were less dependent on their self-reported sleep quality. Contrarily, average sleep duration did not appear to impact cortisol stress responses. Lastly, participants who reported daytime dysfunctions (i.e. having trouble staying awake or keeping up enthusiasm) also showed a trend to blunted cortisol stress responses compared to participants who did not experience these types of daytime dysfunctions. Overall, the current study suggests gender-specific stress reactivity dysfunctions as one mechanism linking poor sleep with detrimental physical health outcomes. Furthermore, the observed differential sleep effects may indicate that while the body may be unable to maintain normal hypothalamic-pituitary-adrenal functioning in an acute psychosocial stress situation after falling prey to low sleep quality, it may retain capacities to deal with challenges during extended times of sleep deprivation.

  14. Acute physiological stress promotes clustering of synaptic markers and alters spine morphology in the hippocampus.

    Directory of Open Access Journals (Sweden)

    Veronica Sebastian

    Full Text Available GluA2-containing AMPA receptors and their association with protein kinase M zeta (PKMζ and post-synaptic density-95 (PSD-95 are important for learning, memory and synaptic plasticity processes. Here we investigated these synaptic markers in the context of an acute 1h platform stress, which can disrupt spatial memory retrieval for a short-term memory on the object placement task and long-term memory retrieval on a well-learned radial arm maze task. Acute stress increased serum corticosterone and elevated the expression of synaptic PKMζ while decreasing synaptic GluA2. Using co-immunoprecipitation, we found that this stressor promotes the clustering of GluA2, PKMζ and PSD-95, which is consistent with effects reported from overexpression of PKMζ in cell culture. Because PKMζ overexpression has also been shown to induce spine maturation in culture, we examined how stress impacts synaptic markers within changing spines across various hippocampal subfields. To achieve this, we employed a new technique combining Golgi staining and immmunohistochemistry to perform 3D reconstruction of tertiary dendrites, which can be analyzed for differences in spine types and the colocalization of synaptic markers within these spines. In CA1, stress increased the densities of long-thin and mushroom spines and the colocalization of GluA2/PSD-95 within these spines. Conversely, in CA3, stress decreased the densities of filopodia and stubby spines, with a concomitant reduction in the colocalization of GluA2/PSD-95 within these spines. In the outer molecular layer (OML of the dentate gyrus (DG, stress increased both stubby and long-thin spines, together with greater GluA2/PSD-95 colocalization. These data reflect the rapid effects of stress on inducing morphological changes within specific hippocampal subfields, highlighting a potential mechanism by which stress can modulate memory consolidation and retrieval.

  15. Assessing Cumulative Thermal Stress in Fish During Chronic Exposure to High Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bevelhimer, M.S.; Bennett, W.R.

    1999-11-14

    As environmental laws become increasingly protective, and with possible future changes in global climate, thermal effects on aquatic resources are likely to receive increasing attention. Lethal temperatures for a variety of species have been determined for situations where temperatures rise rapidly resulting in lethal effects. However, less is known about the effects of chronic exposure to high (but not immediately lethal) temperatures and even less about stress accumulation during periods of fluctuating temperatures. In this paper we present a modeling framework for assessing cumulative thermal stress in fish. The model assumes that stress accumulation occurs above a threshold temperature at a rate depending on the degree to which the threshold is exceeded. The model also includes stress recovery (or alleviation) when temperatures drop below the threshold temperature as in systems with large daily variation. In addition to non-specific physiological stress, the model also simulates thermal effects on growth.

  16. Tasco(®), a product of Ascophyllum nodosum, imparts thermal stress tolerance in Caenorhabditis elegans.

    Science.gov (United States)

    Kandasamy, Saveetha; Fan, Di; Sangha, Jatinder Singh; Khan, Wajahatullah; Evans, Franklin; Critchley, Alan T; Prithiviraj, Balakrishnan

    2011-01-01

    Tasco(®), a commercial product manufactured from the brown alga Ascophyllum nodosum, has been shown to impart thermal stress tolerance in animals. We investigated the physiological, biochemical and molecular bases of this induced thermal stress tolerance using the invertebrate animal model, Caenorhabiditis elegans. Tasco(®) water extract (TWE) at 300 μg/mL significantly enhanced thermal stress tolerance as well as extended the life span of C. elegans. The mean survival rate of the model animals under thermal stress (35 °C) treated with 300 μg/mL and 600 μg/mL TWE, respectively, was 68% and 71% higher than the control animals. However, the TWE treatments did not affect the nematode body length, fertility or the cellular localization of daf-16. On the contrary, TWE under thermal stress significantly increased the pharyngeal pumping rate in treated animals compared to the control. Treatment with TWE also showed differential protein expression profiles over control following 2D gel-electrophoresis analysis. Furthermore, TWE significantly altered the expression of at least 40 proteins under thermal stress; among these proteins 34 were up-regulated while six were down-regulated. Mass spectroscopy analysis of the proteins altered by TWE treatment revealed that these proteins were related to heat stress tolerance, energy metabolism and a muscle structure related protein. Among them heat shock proteins, superoxide dismutase, glutathione peroxidase, aldehyde dehydrogenase, saposin-like proteins 20, myosin regulatory light chain 1, cytochrome c oxidase RAS-like, GTP-binding protein RHO A, OS were significantly up-regulated, while eukaryotic translation initiation factor 5A-1 OS, 60S ribosomal protein L18 OS, peroxiredoxin protein 2 were down regulated by TWE treatment. These results were further validated by gene expression and reporter gene expression analyses. Overall results indicate that the water soluble components of Tasco(®) imparted thermal stress tolerance in

  17. Tasco®, a Product of Ascophyllum nodosum, Imparts Thermal Stress Tolerance in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Franklin Evans

    2011-11-01

    Full Text Available Tasco®, a commercial product manufactured from the brown alga Ascophyllum nodosum, has been shown to impart thermal stress tolerance in animals. We investigated the physiological, biochemical and molecular bases of this induced thermal stress tolerance using the invertebrate animal model, Caenorhabiditis elegans. Tasco® water extract (TWE at 300 µg/mL significantly enhanced thermal stress tolerance as well as extended the life span of C. elegans. The mean survival rate of the model animals under thermal stress (35 °C treated with 300 µg/mL and 600 µg/mL TWE, respectively, was 68% and 71% higher than the control animals. However, the TWE treatments did not affect the nematode body length, fertility or the cellular localization of daf-16. On the contrary, TWE under thermal stress significantly increased the pharyngeal pumping rate in treated animals compared to the control. Treatment with TWE also showed differential protein expression profiles over control following 2D gel-electrophoresis analysis. Furthermore, TWE significantly altered the expression of at least 40 proteins under thermal stress; among these proteins 34 were up-regulated while six were down-regulated. Mass spectroscopy analysis of the proteins altered by TWE treatment revealed that these proteins were related to heat stress tolerance, energy metabolism and a muscle structure related protein. Among them heat shock proteins, superoxide dismutase, glutathione peroxidase, aldehyde dehydrogenase, saposin-like proteins 20, myosin regulatory light chain 1, cytochrome c oxidase RAS-like, GTP-binding protein RHO A, OS were significantly up-regulated, while eukaryotic translation initiation factor 5A-1 OS, 60S ribosomal protein L18 OS, peroxiredoxin protein 2 were down regulated by TWE treatment. These results were further validated by gene expression and reporter gene expression analyses. Overall results indicate that the water soluble components of Tasco® imparted thermal stress

  18. Moderate Thermal Stress Causes Active and Immediate Expulsion of Photosynthetically Damaged Zooxanthellae (Symbiodinium from Corals.

    Directory of Open Access Journals (Sweden)

    Lisa Fujise

    Full Text Available The foundation of coral reef biology is the symbiosis between corals and zooxanthellae (dinoflagellate genus Symbiodinium. Recently, coral bleaching, which often results in mass mortality of corals and the collapse of coral reef ecosystems, has become an important issue around the world as coral reefs decrease in number year after year. To understand the mechanisms underlying coral bleaching, we maintained two species of scleractinian corals (Acroporidae in aquaria under non-thermal stress (27°C and moderate thermal stress conditions (30°C, and we compared the numbers and conditions of the expelled Symbiodinium from these corals. Under non-thermal stress conditions corals actively expel a degraded form of Symbiodinium, which are thought to be digested by their host coral. This response was also observed at 30°C. However, while the expulsion rates of Symbiodinium cells remained constant, the proportion of degraded cells significantly increased at 30°C. This result indicates that corals more actively digest and expel damaged Symbiodinium under thermal stress conditions, likely as a mechanism for coping with environmental change. However, the increase in digested Symbiodinium expulsion under thermal stress may not fully keep up with accumulation of the damaged cells. There are more photosynthetically damaged Symbiodinium upon prolonged exposure to thermal stress, and corals release them without digestion to prevent their accumulation. This response may be an adaptive strategy to moderate stress to ensure survival, but the accumulation of damaged Symbiodinium, which causes subsequent coral deterioration, may occur when the response cannot cope with the magnitude or duration of environmental stress, and this might be a possible mechanism underlying coral bleaching during prolonged moderate thermal stress.

  19. Relationship between antioxidant capacity and oxidative stress in children with acute hepatitis A

    Institute of Scientific and Technical Information of China (English)

    Mustafa Cemek; Semiha Dede; Fahri Bayiro(g)lu; Hüseyin (C)aksen; Fatma Cemek; Nihat Mert

    2006-01-01

    AIM: To investigate in children with acute hepatitis A.According to our knowledge, there are no data about the blood levels of malondialdehyde (MDA, an indicator of oxidative stress) and nonenzymic antioxidants in children with acute hepatitis A.METHODS: Whole blood MDA and reduced glutathione (GSH), serum β-carotene, retinol, vitamin E and vitamin C levels were studied in 19 (10 females, 9 males)children with acute hepatitis A and in 29 (13 females, 16males) healthy control subjects.RESULTS: There was a statistically significant difference between patients and controls for all parameters (P <0.05). Lipid peroxidation marker MDA was significantly elevated (P < 0.001), while antioxidants β-carotene,retinol and GSH were significantly decreased (all P <0.001) in patients compared to healthy subjects. In addition, α-tocopherol and ascorbic acid levels were significantly lower in patients when compared to age and sex matched controls (P < 0.05, P < 0.01, respectively).CONCLUSION: Our study shows that hepatitis A virus induces oxidative stress in childern with hepatitis A. This finding could be taken into consideration to improve the therapeutic approach in acute hepatitis A.

  20. Thermal residual stress analysis of coated diamond grits

    Institute of Scientific and Technical Information of China (English)

    Zi-qian Huang; Bo Xiang; Yue-hui He; Bai-yun Huang

    2009-01-01

    Residual stresses of coated diamond grits were analyzed by a finite element unit cell model.Diamond grits coated with four types of metals, W, Mo, Ti, and Cr, were considered.The numerical results show that compressive stress occurs in the diamond particles and tensile stress occurs in the metal matrix; compressive stress is concentrated in the diamond sharp comer; interface stresses decrease by more than 1000 MPa with a metal interlayer; plastic deformation of the matrix begins near the sharp comer of diamond grits and extends toward the peripheral zone.Stress concentration dramatically decreases due to plastic deformation of the matrix.The deposition of transition metals on a diamond surface can dramatically promote the adhesion between diamond grits and the metal bond.

  1. The effects of acute anticipatory stress on frontal executive functions in healthy females

    OpenAIRE

    Brookmann, Frieda

    2010-01-01

    Objective Results from previous studies show effects of stress hormones (cortisol) on cognitive functions, particularly those mediated by the hippocampus, but little research has examined the effects of cortisol on frontal executive functions, despite a preponderance of cortisol receptors in the frontal lobes. Existing research has focused on traditional measures of executive functions and the findings are inconsistent. The aim of the present study was to examine the effects of acute stres...

  2. Time profile of oxidative stress and neutrophil activation in ovine acute lung injury and sepsis

    OpenAIRE

    Lange, Matthias; Szabo, Csaba; Traber, Daniel L.; Horvath, Eszter; Hamahata, Atsumori; Nakano, Yoshimitsu; Traber, Lillian D.; Cox, Robert A.; Schmalstieg, Frank C.; Herndon, David N.; Enkhbaatar, Perenlei

    2012-01-01

    The formation of oxidative stress in the lung and activation of neutrophils are major determinants in the development of respiratory failure following acute lung injury (ALI) and sepsis. However, the time changes of these pathogenic factors have not been sufficiently described. Twenty-four chronically instrumented sheep were subjected to cotton smoke inhalation injury and instillation of live Pseudomonas aeruginosa into both lungs. The sheep and were euthanized at 4, 8, 12, 18, and 24 hours p...

  3. Acute stress and working memory: The role of sex and cognitive stress appraisal.

    Science.gov (United States)

    Zandara, M; Garcia-Lluch, M; Pulopulos, M M; Hidalgo, V; Villada, C; Salvador, A

    2016-10-01

    Sex is considered a moderating factor in the relationship between stress and cognitive performance. However, sex differences and the impact of cognitive stress appraisal on working memory performance have not received much attention. The aim of this study was to investigate the role of physiological responses (heart rate and salivary cortisol) and cognitive stress appraisal in Working Memory (WM) performance in males and females. For this purpose, we subjected a comparable number of healthy young adult males (N=37) and females (N=45) to a modified version of the Trier Social Stress Test (TSST), and we evaluated WM performance before and after the stress task. Females performed better on attention and maintenance after the TSST, but males did not. Moreover, we found that attention and maintenance performance presented a negative relationship with cortisol reactivity in females, but not in males. Nevertheless, we observed that only the females who showed a cortisol decrease after the TSST performed better after the stress task, whereas females and males who showed an increase or no change in cortisol levels, and males who showed a cortisol decrease, did not change their performance over time. In females, we also found that the global indexes of cognitive stress appraisal and cognitive threat appraisal were negatively related to attention and maintenance performance, whereas the Self-concept of Own Competence was positively related to it. However, these relationships were not found in males. PMID:27321755

  4. Determination of Creep Behavior of Thermal Barrier Coatings Under Laser Imposed High Thermal and Stress Gradient Conditions

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    A laser sintering/creep technique has been established to determine the creep behavior of thermal barrier coatings under steady-state high heat flux conditions. For a plasma sprayed zirconia-8 wt. % yttria coating, a significant primary creep strain and a low apparent creep activation energy were observed. Possible creep mechanisms involved include stress induced mechanical sliding and temperature and stress enhanced cation diffusion through the splat and grain boundaries. The elastic modulus evolution, stress response, and total accumulated creep strain variation across the ceramic coating are simulated using a finite difference approach. The modeled creep response is consistent with experimental observations.

  5. The acute effects of 3,4-methylenedioxymethamphetamine on oxidative stress in rat brain

    Directory of Open Access Journals (Sweden)

    Simić Ivan

    2008-01-01

    Full Text Available Introduction Oxidative stress and oxygen free radicals are thought to play an important role in acute effects of a number of neurotoxic processes. 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy, a ring substituted amphetamine derivate, has attracted a great deal of media attention in recent years due to its widespread abuse as recreational drug by the young generation. The aim of the present study was to evaluate the acute effects of 3,4-methylenedioxymethamphetamine on oxidative stress parameters (index of lipid peroxidation - ILP, superoxide radicals O2-, superoxide dismutase - SOD and glutathione - GSH in frontal cortex, striatum and hippocampus in Wistar rats. Materials and methods The study included 40 male Wistar rats (200-250 g, housed 4 per cage having free access to food and water. MDMA was dissolved in distillated water and administered peroraly at 5, 10, 20 or 40 mg/kg. 8 hours following MDMA, the rats were killed by decapitation, their brains were rapidly removed and the brain structures were dissected out on ice and analyzed biochemically. Results Acute peroral administration of a single dose (5, 10, 20 and 40 mg/kg resulted in increase of ILP, O2-, SOD and decrease of GSH. Conclusion The results obtained in the present study suggest that oxidative stress plays a crucial role in MDMA-induced neurotoxicity and that the mechanism of MDMA neurotoxycity may vary between brain regions.

  6. Association between Peripheral Oxidative Stress and White Matter Damage in Acute Traumatic Brain Injury

    Directory of Open Access Journals (Sweden)

    Wei-Ming Lin

    2014-01-01

    Full Text Available The oxidative stress is believed to be one of the mechanisms involved in the neuronal damage after acute traumatic brain injury (TBI. However, the disease severity correlation between oxidative stress biomarker level and deep brain microstructural changes in acute TBI remains unknown. In present study, twenty-four patients with acute TBI and 24 healthy volunteers underwent DTI. The peripheral blood oxidative biomarkers, like serum thiol and thiobarbituric acid-reactive substances (TBARS concentrations, were also obtained. The DTI metrics of the deep brain regions, as well as the fractional anisotropy (FA and apparent diffusion coefficient, were measured and correlated with disease severity, serum thiol, and TBARS levels. We found that patients with TBI displayed lower FAs in deep brain regions with abundant WMs and further correlated with increased serum TBARS level. Our study has shown a level of anatomic detail to the relationship between white matter (WM damage and increased systemic oxidative stress in TBI which suggests common inflammatory processes that covary in both the peripheral and central reactions after TBI.

  7. Stress and Strain During the Process of Thermal Stabilization of Modified Pan Precursors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wang-xi; WANG Yan-zhi; PAN Wei

    2007-01-01

    Thermal mechanical analysis, FT- IR, WAXD and some conventional measurements, such as densities and mechanical properties, were used to characterize the effect of the modification using KMnO4 and SnCl4 on the thermal mechanical behaviors and structural changes dining the process of thermal stabilization of modified PAN precursors. to the unmodified original PAN precursors, some conclusions were drawn that the thermal stabilization starts at a lower temperature for modified PAN fibers, for example, the peak of thermal stress changes for modified PAN precursors using KMnO4 displays a decrease of 20℃ and a increase of 30% in the ultimate thermal stress, that chemical modification makes structural transformation perfect and increases by 25% of the thermal stress at the temperature range of 230℃- 300℃, that the modified PAN fibers display an increase of 100% in the thermal strain, once after pre-oxidized, show an increase of 7.8% in orientation index, and a decrease of 9.9% in crystal size for identical preload in the region of 13.1 - 14.5 MPa. It was also concluded that the modification using SnCl4 would alleviate the changes in physical and chemical stress regimes and result in improvement in structure and decrease in defects.

  8. EFFECT OF HELICOBACTER PYLORI INFECTION ON ACUTE STRESS-RELATED GASTRIC MUCOSAL DAMAGE OF SERIOUSLY ILL PATIENTS

    Institute of Scientific and Technical Information of China (English)

    赵超; 肖文; 叶光福; 周建平; 周其璋

    2002-01-01

    Emergency endoscopy studies have shown that the most of seriously ill patients develop acute stress-related mucosal damage and ulceration within 24 hours of admission, which manifest the upper gastrointestinal tract

  9. Investigating the molecular basis of local adaptation to thermal stress: population differences in gene expression across the transcriptome of the copepod Tigriopus californicus

    Directory of Open Access Journals (Sweden)

    Schoville Sean D

    2012-09-01

    Full Text Available Abstract Background Geographic variation in the thermal environment impacts a broad range of biochemical and physiological processes and can be a major selective force leading to local population adaptation. In the intertidal copepod Tigriopus californicus, populations along the coast of California show differences in thermal tolerance that are consistent with adaptation, i.e., southern populations withstand thermal stresses that are lethal to northern populations. To understand the genetic basis of these physiological differences, we use an RNA-seq approach to compare genome-wide patterns of gene expression in two populations known to differ in thermal tolerance. Results Observed differences in gene expression between the southern (San Diego and the northern (Santa Cruz populations included both the number of affected loci as well as the identity of these loci. However, the most pronounced differences concerned the amplitude of up-regulation of genes producing heat shock proteins (Hsps and genes involved in ubiquitination and proteolysis. Among the hsp genes, orthologous pairs show markedly different thermal responses as the amplitude of hsp response was greatly elevated in the San Diego population, most notably in members of the hsp70 gene family. There was no evidence of accelerated evolution at the sequence level for hsp genes. Among other sets of genes, cuticle genes were up-regulated in SD but down-regulated in SC, and mitochondrial genes were down-regulated in both populations. Conclusions Marked changes in gene expression were observed in response to acute sub-lethal thermal stress in the copepod T. californicus. Although some qualitative differences were observed between populations, the most pronounced differences involved the magnitude of induction of numerous hsp and ubiquitin genes. These differences in gene expression suggest that evolutionary divergence in the regulatory pathway(s involved in acute temperature stress may offer at

  10. Analytical model of transient temperature and thermal stress in continuous wave double-end-pumped laser rod: Thermal stress minimization study

    Indian Academy of Sciences (India)

    Khalid S Shibib; Mayada M Tahir; Haqi I Qatta

    2012-08-01

    A time-dependent analytical thermal model of the temperature and the corresponding induced thermal stresses in continuous wave double-end-pumped laser rod are derived from the first principle using the integral transform method. The aim of the paper is to study the effect of increasing the pumping powers while the laser crystals are still in the safe zone (i.e. far away from failure stress) and to suitably choose a crystal that achieves this task. The result of this work is compared with a well-verified finite element solution and a good agreement has been found. Some conclusions are obtained: Tm:YAP crystal, which has high thermal conductivity, low expansion coefficient, low absorption coefficient, low thermal factor and low product of /(1−), is the best choice to reduce induced stress although it is responded and brought to thermal equilibrium faster than the other types of crystal usually used in the end-pumped solid-state laser.

  11. The double-end-pumped cubic Nd:YVO4 laser: Temperature distribution and thermal stress

    Indian Academy of Sciences (India)

    P Elahi; S Morshedi

    2010-01-01

    Thermal effects of a double-end-pumped cubic Nd:YVO4 laser crystal are investigated in this paper. A detailed analysis of temperature distribution and thermal stress in cubic crystal with circular shape pumping is discussed. It has been shown that by considering the total input powers as constant, the double-end-pumped configurations with equal pump power can be considered as having a minimum thermal effect with respect to the other end-pumped configuration.

  12. Measurements of thermal residual stresses in SiC/Ti-15-3 composites

    Energy Technology Data Exchange (ETDEWEB)

    Bobet, J.-L.; Masuda, C. [National Research Inst. for Metals, Tsukuba, Ibaraki (Japan)

    1997-06-01

    Residual stresses present in an as received and thermally cycled SCS-6/Ti-15-3 metal matrix composite (MMC) have been approached via X-ray diffraction (sin{sup 2}{psi}) experiments. Determination of stress profiles have been achieved by successive removal of the matrix from the composite surface by electropolishing. Axial and hoop stresses in the matrix were tensile (higher on the surface) and those measured in the fiber were compressive (about -500 to -600 MPa). A stress gradient normal to the surface of the composite was found. Measurement of residual stress levels in the composite subjected to thermal cycling from 400degC to 800degC in an inert atmosphere or in vacuum revealed a huge stress relaxation after only 200 cycles. (author)

  13. BEHAVIORAL CHARACTERISTICS OF RATS ON VARIOUS HIERARCHICAL LEVEL CAUSED BY ACUTE INFORMATIONAL STRESS.

    Science.gov (United States)

    Matitaishvili, T; Domianidze, T; Emukhvari, N; Khananashvili, M

    2016-03-01

    The aim of our research was to study behavioral indices of rats standing on various hierarchical level in the conditions of acute informational stress as well as their resistance to stress taking into account their social status. The Animal's behavior has been studied in conflict and agonist conditions against the background of high food and thirst motivation. After determination of hierarchical relations the stressing procedure of two active avoidance reactions was performed simultaneously during one trial (14 days). During the experiment, behavioral indices of rats induced by stressing procedure were registered. We used "open field" test in order to assess animals' emotional state. The studies performed by us demonstrated behavioral characteristics of animals standing on various hierarchical level. The obtained results showed that after stressing all the animals of the group under stressogenic influence of equal strength, behavior of rats did nor reliably differ in conflict situations. Dominants standing on high hierarchical level remained active in both conflict situations. The impact of stress on their behavior was less detected. Dominant animal maintained its hierarchical status. Submissive rats were more greatly influenced by stress. The obtained results confirmed that dominant animals were characterized with more comprehensively developed self-regulating mechanisms of brain. PMID:27119838

  14. Biomarkers for oxidative stress in acute lung injury induced in rabbits submitted to different strategies of mechanical ventilation

    Science.gov (United States)

    Oxidative damage has been said to play an important role in pulmonary injury, which is associated with the development and progression of acute respiratory distress syndrome (ARDS). We aimed to identify biomarkers to determine the oxidative stress in an animal model of acute lung injury (ALI) using ...

  15. Mice lacking sulfonylurea receptor 2 (SUR2) ATP sensitive potassium channels are resistant to acute cardiovascular stress

    OpenAIRE

    Stoller, Douglas; Kakkar, Rahul; Smelley, Matthew; Chalupsky, Karel; Earley, Judy U.; Shi, Nian-Qing; Makielski, Jonathan C.; McNally, Elizabeth M.

    2007-01-01

    Adenosine triphosphate sensitive potassium (KATP) channels are thought to mediate stress response by sensing intracellular ATP concentration. Cardiomyocyte KATP channels are composed of the pore-forming Kir6.2 subunit and the regulatory sulfonylurea receptor 2 (SUR2). We studied the response to acute isoproterenol in SUR2 null mice as a model of acute adrenergic stress and found that the episodic coronary vasospasm observed at baseline in SUR2 null mice was alleviated. Similar results were ob...

  16. The effect of thermal properties and weld efficiency on residual stresses in welding

    OpenAIRE

    E. Armentani; Esposito, R.; R. Sepe

    2007-01-01

    Purpose: A parametric model is adopted and the technique of element “birth and death” is used to estimate theeffect of thermal properties and weld efficiency on residual stresses in butt weld joints.Design/methodology/approach: Residual stresses and distortions on butt welded joints are numericallyevaluated by means of finite element method. The FE analysis allows to highlight and evaluate the stress fieldand its gradient around the fusion zone of welded joints, higher than any other located ...

  17. Investigations in thermal fields and stress fields induced by electron beam welding

    International Nuclear Information System (INIS)

    This document presents the thermal study of electron beam welding and identifies stresses and strains from welding: description of the operating principles of the electron gun and characterization of various welding parameters, examination of the temperature fields during electron beam welding development of various mathematic models and comparison with experimental results, measurement and calculation of stresses and strains in the medium plane of the welding assembly, residual stresses analysis

  18. Plasticity of upper thermal limits to acute and chronic temperature variation in Manduca sexta larvae.

    Science.gov (United States)

    Kingsolver, Joel G; MacLean, Heidi J; Goddin, Silvan B; Augustine, Kate E

    2016-05-01

    In many ectotherms, exposure to high temperatures can improve subsequent tolerance to higher temperatures. However, the differential effects of single, repeated or continuous exposure to high temperatures are less clear. We measured the effects of single heat shocks and of diurnally fluctuating or constant rearing temperatures on the critical thermal maximum (CTmax) for final instar larvae of Manduca sexta Brief (2 h) heat shocks at temperatures of 35°C and above significantly increased CTmax relative to control temperatures (25°C). Increasing mean temperatures (from 25 to 30°C) or greater diurnal fluctuations (from constant to ±10°C) during larval development also significantly increased CTmax Combining these data showed that repeated or continuous temperature exposure during development improved heat tolerance beyond the effects of a single exposure to the same maximum temperature. These results suggest that both acute and chronic temperature exposure can result in adaptive plasticity of upper thermal limits. PMID:26944498

  19. Rock properties and their effect on thermally-induced displacements and stresses

    International Nuclear Information System (INIS)

    A discussion is given of the importance of material properties in the finite-element calculations for thermally induced displacements and stresses resulting from a heating experiment in an in-situ granitic rock, at Stripa, Sweden. Comparisons are made between field measurements and finite element method calculations using (1) temperature independent, (2) temperature dependent thermal and thermomechanical properties and (3) in-situ and laboratory measurements for Young's modulus. The calculations of rock displacements are influenced predominantly by the temperature dependence of the thermal expansion coefficient, whereas the dominant factor affecting predictions for rock stresses is the in-situ modulus

  20. Rock properties and their effect on thermally-induced displacements and stresses

    Energy Technology Data Exchange (ETDEWEB)

    Chan, T.; Hood, M.; Board, M.

    1980-02-01

    A discussion is given of the importance of material properties in the finite-element calculations for thermally induced displacements and stresses resulting from a heating experiment in an in-situ granitic rock, at Stripa, Sweden. Comparisons are made between field measurements and finite element method calculations using (1) temperature independent, (2) temperature dependent thermal and thermomechanical properties and (3) in-situ and laboratory measurements for Young's modulus. The calculations of rock displacements are influenced predominantly by the temperature dependence of the thermal expansion coefficient, whereas the dominant factor affecting predictions for rock stresses is the in-situ modulus.

  1. Temperature and Thermal Stress Distribution for Metal Mold in Squeeze Casting Process

    Institute of Scientific and Technical Information of China (English)

    K.H.Chang; G.C.Jang; C.H.Lee; S.H.Lee

    2008-01-01

    In the squeeze casting process, loaded high pressure (over approximately 100 MPa) and high temperature influence the thermo-mechanical behavior and performance of the used metal mold. Therefore, to safely maintain the metal molds, the thermo-mechanical characteristics (temperature and thermal stress) of metal mold in the squeeze casting must be investigated. In this paper, temperature and thermal stress distribution of steel mold in squeeze casting process were investigated by using a three-dimensional non-steady heat conduction analysis and a three-dimensional thermal elastic-plastic analysis considering temperature-dependent thermo- physical and mechanical properties of the steel mold.

  2. Acute effect of aspartame-induced oxidative stress in Wistar albino rat brain.

    Science.gov (United States)

    Ashok, Iyaswamy; Sheeladevi, Rathinasamy; Wankhar, Dapkupar

    2015-09-01

    The present study was carried out to investigate the acute effect of aspartame on oxidative stress in the Wistar albino rat brain. We sought to investigate whether acute administration of aspartame (75 mg/kg) could release methanol and induce oxidative stress in the rat brain 24 hours after administration. To mimic human methanol metabolism, methotrexate treated rats were used to study aspartame effects. Wistar strain male albino rats were administered with aspartame orally as a single dose and studied along with controls and methotrexate treated controls. Blood methanol and formate level were estimated after 24 hours and rats were sacrificed and free radical changes were observed in discrete regions by assessing the scavenging enzymes, reduce dglutathione (GSH), lipid peroxidation and protein thiol levels. There was a significant increase in lipid peroxidation levels, superoxide dismutase activity (SOD), glutathione peroxidase levels (GPx), and catalase activity (CAT) with a significant decrease in GSH and protein thiol. Aspartame exposure resulted in detectable methanol even after 24 hours. Methanol and its metabolites may be responsible for the generation of oxidative stress in brain regions. The observed alteration in aspartame fed animals may be due to its metabolite methanol and elevated formate. The elevated free radicals due to methanol induced oxidative stress.

  3. Effect of acute stresses on zebra fish (Danio rerio) metabolome measured by NMR-based metabolomics.

    Science.gov (United States)

    Mushtaq, Mian Yahya; Marçal, Rosilene Moretti; Champagne, Danielle L; van der Kooy, Frank; Verpoorte, Robert; Choi, Young Hae

    2014-09-01

    We applied an acute stress model to zebra fish in order to measure the changes in the metabolome due to biological stress. This was done by submitting the fish to fifteen minutes of acute confinement (netting) stress, and then five minutes for the open field and light/dark field tests. A polar extract of the zebra fish was then subjected to (1)H nuclear magnetic spectroscopy. Multivariate data analysis of the spectra showed a clear separation associated to a wide range of metabolites between zebra fish that were submitted to open field and light/dark field tests. Alanine, taurine, adenosine, creatine, lactate, and histidine were high in zebra fish to which the light/dark field test was applied, regardless of stress, while acetate and isoleucine/lipids appeared to be higher in zebra fish exposed to the open field test. These results show that any change in the environment, even for a small period of time, has a noticeable physiological impact. This research provides an insight of how different mechanisms are activated under different environments to maintain the homeostasis of the body. It should also contribute to establish zebra fish as a model for metabolomics studies. PMID:25098933

  4. Behavioral and autonomic responses to acute restraint stress are segregated within the lateral septal area of rats.

    Directory of Open Access Journals (Sweden)

    Daniel G Reis

    Full Text Available BACKGROUND: The Lateral Septal Area (LSA is involved with autonomic and behavior responses associated to stress. In rats, acute restraint (RS is an unavoidable stress situation that causes autonomic (body temperature, mean arterial pressure (MAP and heart rate (HR increases and behavioral (increased anxiety-like behavior changes in rats. The LSA is one of several brain regions that have been involved in stress responses. The aim of the present study was to investigate if the neurotransmission blockade in the LSA would interfere in the autonomic and behavioral changes induced by RS. METHODOLOGY/PRINCIPAL FINDINGS: Male Wistar rats with bilateral cannulae aimed at the LSA, an intra-abdominal datalogger (for recording internal body temperature, and an implanted catheter into the femoral artery (for recording and cardiovascular parameters were used. They received bilateral microinjections of the non-selective synapse blocker cobalt chloride (CoCl(2, 1 mM/ 100 nL or vehicle 10 min before RS session. The tail temperature was measured by an infrared thermal imager during the session. Twenty-four h after the RS session the rats were tested in the elevated plus maze (EPM. CONCLUSIONS/SIGNIFICANCE: Inhibition of LSA neurotransmission reduced the MAP and HR increases observed during RS. However, no changes were observed in the decrease in skin temperature and increase in internal body temperature observed during this period. Also, LSA inhibition did not change the anxiogenic effect induced by RS observed 24 h later in the EPM. The present results suggest that LSA neurotransmission is involved in the cardiovascular but not the temperature and behavioral changes induced by restraint stress.

  5. Thermal residual stress analysis of diamond coating on graded cemented carbides

    Institute of Scientific and Technical Information of China (English)

    HUANG Zi-qian; HE Yue-hui; CAI Hai-tao; WU Cong-hai; XIAO Yi-feng; HUANG Bai-yun

    2008-01-01

    Finite element model was developed to analyze thermal residual stress distribution of diamond coating on graded and homogeneous substrates. Graded cemented carbides were formed by carburizing pretreatment to reduce the cobalt content in the surface layer and improve adhesion of diamond coating. The numerical calculation results show that the surface compressive stress of diamond coating is 950 MPa for graded substrate and 1 250 MPa for homogenous substrate, the thermal residual stress decreases by around 24% due to diamond coating. Carburizing pretreatment is good for diamond nucleation rate, and can increase the interface strength between diamond coating and substrate.

  6. Measurement and computation of thermal stresses in injection molding of amorphous and crystalline polymers

    Science.gov (United States)

    Farhoudi, Yalda

    1998-12-01

    An integrated experimental and theoretical study of the residual thermal stresses has been carried out. The final stress profiles along the thickness were measured in an amorphous and a semi-crystalline injection molded polymer using the layer removal technique. The two materials exhibited drastically distinct residual profiles. Furthermore, processing parameters such as melt and coolant temperatures, pressure history, and mold thickness were found to modify the profiles. In order to elucidate the findings, two models were derived. The two-dimensional free mold shrinkage model was developed to provide a rapid estimation of thermal stresses and the main features of their profile. A more complex model was developed by integrating the stress analysis with the simulation of the complete injection molding cycle by McKam. This model accounts for the fountain flow effect, the crystallization, and the PVT behavior of the material. With the help of the model predictions, explanations were provided for the occurrence of various regions in the residual stress profiles. Transitions or reversal of the regions under variable conditions or material properties were observed to be mainly determined by the ratio of the thermal to the pressure effects. Using these concepts, practical conclusions were drawn for controlling the residual stresses. As an alternative for optimization of injection molding with respect to residual stresses, inverse methods were developed to calculate the pressure history or the initial temperature distribution required to produce a prescribed residual stress distribution. These methods were tested using direct solutions with added errors and experimental stress data.

  7. Acute Ethanol Gavage Attenuates Hemorrhage/Resuscitation-Induced Hepatic Oxidative Stress in Rats

    Directory of Open Access Journals (Sweden)

    B. Relja

    2012-01-01

    Full Text Available Acute ethanol intoxication increases the production of reactive oxygen species (ROS. Hemorrhagic shock with subsequent resuscitation (H/R also induces ROS resulting in cellular and hepatic damage in vivo. We examined the role of acute ethanol intoxication upon oxidative stress and subsequent hepatic cell death after H/R. 14 h before H/R, rats were gavaged with single dose of ethanol or saline (5 g/kg, EtOH and ctrl; H/R_EtOH or H/R_ctrl, resp.. Then, rats were hemorrhaged to a mean arterial blood pressure of 30±2 mmHg for 60 min and resuscitated. Two control groups underwent surgical procedures without H/R (sham_ctrl and sham_EtOH, resp.. Liver tissues were harvested at 2, 24, and 72 h after resuscitation. EtOH-gavage induced histological picture of acute fatty liver. Hepatic oxidative (4-hydroxynonenal, 4-HNE and nitrosative (3-nitrotyrosine, 3-NT stress were significantly reduced in EtOH-gavaged rats compared to controls after H/R. Proapoptotic caspase-8 and Bax expressions were markedly diminished in EtOH-gavaged animals compared with controls 2 h after resuscitation. EtOH-gavage increased antiapoptotic Bcl-2 gene expression compared with controls 2 h after resuscitation. iNOS protein expression increased following H/R but was attenuated in EtOH-gavaged animals after H/R. Taken together, the data suggest that acute EtOH-gavage may attenuate H/R-induced oxidative stress thereby reducing cellular injury in rat liver.

  8. Analytical Predictions of Thermal Stress in the Stardust PICA Heatshield Under Reentry Flight Conditions

    Science.gov (United States)

    Squire, Thomas; Milos, Frank; Agrawal, Parul

    2009-01-01

    We performed finite element analyses on a model of the Phenolic Impregnated Carbon Ablator (PICA) heatshield from the Stardust sample return capsule (SRC) to predict the thermal stresses in the PICA material during reentry. The heatshield on the Stardust SRC was a 0.83 m sphere cone, fabricated from a single piece of 5.82 cm-thick PICA. The heatshield performed successfully during Earth reentry of the SRC in January 2006. Material response analyses of the full, axisymmetric PICA heatshield were run using the Two-Dimensional Implicit Ablation, Pyrolysis, and Thermal Response Program (TITAN). Peak surface temperatures were predicted to be 3385K, while the temperature at the PICA backface remained at the estimated initial cold-soak temperature of 278K. Surface recession and temperature distribution results from TITAN, at several points in the reentry trajectory, were mapped onto an axisymmetric finite element model of the heatshield. We used the finite element model to predict the thermal stresses in the PICA from differential thermal expansion. The predicted peak compressive stress in the PICA heatshield was 1.38 MPa. Although this level of stress exceeded the chosen design limit for compressive stresses in PICA tiles for the design of the Orion crew exploration vehicle heatshield, the Stardust heatshield exhibited no obvious mechanical failures from thermal stress. The analyses of the Stardust heatshield were used to assess and adjust the level of conservatism in the finite element analyses in support of the Orion heatshield design.

  9. Temperature propagation in prismatic lithium-ion-cells after short term thermal stress

    Science.gov (United States)

    Bohn, Pamina; Liebig, Gerd; Komsiyska, Lidiya; Wittstock, Gunther

    2016-05-01

    In this paper a 3D model based on the thermal material characteristics of an automotive prismatic Li-NiMnCoO2 (NMC) cell was created in COMSOL Multiphysics® in order to simulate the temperature propagation in the cell during short term thermal stress. The thermal characteristics of the battery components were experimentally determined via laser flash analysis (LFA) and differential scanning calorimetry (DSC) and used as an input parameter for the models. In order to validate the modelling approach, an experimental setup was built to measure the temperature propagation during thermal stresses within a dummy cell, equipped with temperature sensors. After validating, the model is used to describe the temperature propagation after a short-term temperature stress on automotive prismatic lithium-ion cells, simulating welding of the contact leads.

  10. Texture formation in FePt thin films via thermal stress management

    International Nuclear Information System (INIS)

    The transformation variant of the fcc to fct transformation in FePt thin films was tailored by controlling the stresses in the thin films, thereby allowing selection of in- or out-of-plane c-axis orientation. FePt thin films were deposited at ambient temperature on several substrates with differing coefficients of thermal expansion relative to the FePt, which generated thermal stresses during the ordering heat treatment. X-ray diffraction analysis revealed preferential out-of-plane c-axis orientation for FePt films deposited on substrates with a similar coefficients of thermal expansion, and random orientation for FePt films deposited on substrates with a very low coefficient of thermal expansion, which is consistent with theoretical analysis when considering residual stresses

  11. The Effects of Hemodynamic Shear Stress on Stemness of Acute Myelogenous Leukemia (AML)

    Science.gov (United States)

    Raddatz, Andrew; Triantafillu, Ursula; Kim, Yonghyun (John)

    2015-11-01

    Cancer stem cells (CSCs) have recently been identified as the root cause of tumors generated from cancer cell populations. This is because these CSCs are drug-resistant and have the ability to self-renew and differentiate. Current methods of culturing CSCs require much time and money, so cancer cell culture protocols, which maximize yield of CSCs are needed. It was hypothesized that the quantity of Acute myelogenous leukemia stem cells (LSCs) would increase after applying shear stress to the leukemia cells based on previous studies with breast cancer in bioreactors. The shear stress was applied by pumping the cells through narrow tubing to mimic the in vivo bloodstream environment. In support of the hypothesis, shear stress was found to increase the amount of LSCs in a given leukemia population. This work was supported by NSF REU Site Award 1358991.

  12. Telomere dynamics in human mesenchymal stem cells after exposure to acute oxidative stress

    DEFF Research Database (Denmark)

    Harbo, M.; Koelvraa, S.; Serakinci, N.;

    2012-01-01

    A gradual shortening of telomeres due to replication can be measured using the standard telomere restriction fragments (TRF) assay and other methods by measuring the mean length of all the telomeres in a cell. In contrast, stress-induced telomere shortening, which is believed to be just...... due to the advantages of the newly developed Universal single telomere length assay (STELA), and we therefore believe that this method should be considered the method of choice when measuring the length of telomeres after exposure to oxidative stress. In order to test our hypothesis, cultured human...... estimated by senescence-associated beta-galactosidase staining. The exposure to acute oxidative stress resulted in an increased number of ultra-short telomeres, which correlated strongly with the percentage of senescent cells, whereas a correlation between mean telomere length and the percentage...

  13. Effect of weld thermal cycle, stress and helium content on helium bubble formation in stainless steels

    International Nuclear Information System (INIS)

    Helium bubble structure was examined on a helium-implanted stainless steel after applying thermal and stress cycle using a weld thermal and stress cycle simulator. Helium ions were implanted on Type 304 stainless steels up to 200 appm uniformly to a depth of 3.5 μm. The specimens were heated at various temperatures between 1073 and 1473 K for 2 s in Ar gas atmosphere. Tensile stresses from 0.5 to 8 MPa were applied during the thermal cycle. TEM observations revealed that size of the bubbles at grain boundaries was larger for the specimens with a higher tensile stress and with a higher annealing temperature. Densities of bubbles increased with increasing helium content. A theoretical model calculation showed a good agreement with the experimental results

  14. Average thermal stress in the Al+SiC composite due to its manufacturing process

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Carlos A.J.; Libardi, Rosani M.P.; Marcelino, Sergio; Boari, Zoroastro M., E-mail: cmiranda@ipen.br, E-mail: rmpenha@ipen.br, E-mail: sergio.marcelino@gmail.com, E-mail: zoroastr@uol.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear

    2013-07-01

    The numerical analyses framework to obtain the average thermal stress in the Al+SiC Composite due to its manufacturing process is presented along with the obtained results. The mixing of Aluminum and SiC powders is done at elevated temperature and the usage is at room temperature. A thermal stress state arises in the composite due to the different thermal expansion coefficients of the materials. Due to the particles size and randomness in the SiC distribution, some sets of models were analyzed and a statistical procedure used to evaluate the average stress state in the composite. In each model the particles position, form and size are randomly generated considering a volumetric ratio (VR) between 20% and 25%, close to an actual composite. The obtained stress field is represented by a certain number of iso stress curves, each one weighted by the area it represents. Systematically it was investigated the influence of: (a) the material behavior: linear x non-linear; (b) the carbide particles form: circular x quadrilateral; (c) the number of iso stress curves considered in each analysis; and (e) the model size (the number of particles). Each of above analyzed condition produced conclusions to guide the next step. Considering a confidence level of 95%, the average thermal stress value in the studied composite (20% ≤ VR ≤ 25%) is 175 MPa with a standard deviation of 10 MPa. Depending on its usage, this value should be taken into account when evaluating the material strength. (author)

  15. Validation of Reef-Scale Thermal Stress Satellite Products for Coral Bleaching Monitoring

    Directory of Open Access Journals (Sweden)

    Scott F. Heron

    2016-01-01

    Full Text Available Satellite monitoring of thermal stress on coral reefs has become an essential component of reef management practice around the world. A recent development by the U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch (NOAA CRW program provides daily global monitoring at 5 km resolution—at or near the scale of most coral reefs. In this paper, we introduce two new monitoring products in the CRW Decision Support System for coral reef management: Regional Virtual Stations, a regional synthesis of thermal stress conditions, and Seven-day Sea Surface Temperature (SST Trend, describing recent changes in temperature at each location. We describe how these products provided information in support of management activities prior to, during and after the 2014 thermal stress event in the Commonwealth of the Northern Mariana Islands (CNMI. Using in situ survey data from this event, we undertake the first quantitative comparison between 5 km satellite monitoring products and coral bleaching observations. Analysis of coral community characteristics, historical temperature conditions and thermal stress revealed a strong influence of coral biodiversity in the patterns of observed bleaching. This resulted in a model based on thermal stress and generic richness that explained 97% of the variance in observed bleaching. These findings illustrate the importance of using local benthic characteristics to interpret the level of impact from thermal stress exposure. In an era of continuing climate change, accurate monitoring of thermal stress and prediction of coral bleaching are essential for stakeholders to direct resources to the most effective management actions to conserve coral reefs.

  16. The Influence of Non-Uniform High Heat Flux on Thermal Stress of Thermoelectric Power Generator

    Directory of Open Access Journals (Sweden)

    Tingzhen Ming

    2015-11-01

    Full Text Available A thermoelectric generator (TEG device which uses solar energy as heat source would achieve higher efficiency if there is a higher temperature difference between the hot-cold ends. However, higher temperature or higher heat flux being imposed upon the hot end will cause strong thermal stress, which will have a negative influence on the life cycle of the thermoelectric module. Meanwhile, in order to get high heat flux, a Fresnel lens is required to concentrate solar energy, which will cause non-uniformity of heat flux on the hot end of the TEG and further influence the thermal stress of the device. This phenomenon is very common in solar TEG devices but seldom research work has been reported. In this paper, numerical analysis on the heat transfer and thermal stress performance of a TEG module has been performed considering the variation on the power of the heat flux being imposed upon the hot-end; the influence of non-uniform high heat flux on thermal stress has also been analyzed. It is found that non-uniformity of high heat flux being imposed upon the hot end has a significant effect on the thermal stress of TEG and life expectation of the device. Taking the uniformity of 100% as standard, when the heating uniformity is 70%, 50%, 30%, and 10%, respectively, the maximum thermal stress of TEG module increased by 3%, 6%, 12%, and 22% respectively. If we increase the heat flux on the hot end, the influence of non-uniformity on the thermal stress will be more remarkable.

  17. Effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices

    Directory of Open Access Journals (Sweden)

    Torres I.L.S.

    2001-01-01

    Full Text Available It has been suggested that glucocorticoids released during stress might impair neuronal function by decreasing glucose uptake by hippocampal neurons. Previous work has demonstrated that glucose uptake is reduced in hippocampal and cerebral cortex slices 24 h after exposure to acute stress, while no effect was observed after repeated stress. Here, we report the effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices and on plasma glucose and corticosterone levels. Male adult Wistar rats were exposed to restraint 1 h/day for 50 days in the chronic model. In the acute model there was a single exposure. Immediately or 24 h after stress, the animals were sacrificed and the hippocampus and cerebral cortex were dissected, sliced, and incubated with Krebs buffer, pH 7.4, containing 5 mM glucose and 0.2 µCi D-[U-14C] glucose. CO2 production from glucose was estimated. Trunk blood was also collected, and both corticosterone and glucose were measured. The results showed that corticosterone levels after exposure to acute restraint were increased, but the increase was smaller when the animals were submitted to repeated stress. Blood glucose levels increased after both acute and repeated stress. However, glucose utilization, measured as CO2 production in hippocampal and cerebral cortex slices, was the same in stressed and control groups under conditions of both acute and chronic stress. We conclude that, although stress may induce a decrease in glucose uptake, this effect is not sufficient to affect the energy metabolism of these cells.

  18. Behavioral economic analysis of stress effects on acute motivation for alcohol.

    Science.gov (United States)

    Owens, Max M; Ray, Lara A; MacKillop, James

    2015-01-01

    Due to issues of definition and measurement, the heavy emphasis on subjective craving in the measurement of acute motivation for alcohol and other drugs remains controversial. Behavioral economic approaches have increasingly been applied to better understand acute drug motivation, particularly using demand curve modeling via purchase tasks to characterize the perceived reinforcing value of the drug. This approach has focused on using putatively more objective indices of motivation, such as units of consumption, monetary expenditure, and price sensitivity. To extend this line of research, the current study used an alcohol purchase task to determine if, compared to a neutral induction, a personalized stress induction would increase alcohol demand in a sample of heavy drinkers. The stress induction significantly increased multiple measures of the reinforcing value of alcohol to the individual, including consumption at zero price (intensity), the maximum total amount of money spent on alcohol (Omax), the first price where consumption was reduced to zero (breakpoint), and the general responsiveness of consumption to increases in price (elasticity). These measures correlated only modestly with craving and mood. Self-reported income was largely unrelated to demand but moderated the influence of stress on Omax. Moderation based on CRH-BP genotype (rs10055255) was present for Omax, with T allele homozygotes exhibiting more pronounced increases in response to stress. These results provide further support for a behavioral economic approach to measuring acute drug motivation. The findings also highlight the potential relevance of income and genetic factors in understanding state effects on the perceived reinforcing value of alcohol. PMID:25413719

  19. The Effects of Social Context and Acute Stress on Decision Making Under Uncertainty.

    Science.gov (United States)

    FeldmanHall, Oriel; Raio, Candace M; Kubota, Jennifer T; Seiler, Morgan G; Phelps, Elizabeth A

    2015-12-01

    Uncertainty preferences are typically studied in neutral, nonsocial contexts. This approach, however, fails to capture the dynamic factors that influence choices under uncertainty in the real world. Our goal was twofold: to test whether uncertainty valuation is similar across social and nonsocial contexts, and to investigate the effects of acute stress on uncertainty preferences. Subjects completed matched gambling and trust games following either a control or a stress manipulation. Those who were not under stress exhibited no differences between the amount of money gambled and the amount of money entrusted to partners. In comparison, stressed subjects gambled more money but entrusted less money to partners. We further found that irrespective of stress, subjects were highly attuned to irrelevant feedback in the nonsocial, gambling context, believing that every loss led to a greater chance of winning (the gamblers' fallacy). However, when deciding to trust a stranger, control subjects behaved rationally, treating each new interaction as independent. Stress compromised this adaptive behavior, increasing sensitivity to irrelevant social feedback. PMID:26546080

  20. Neonatal stress tempers vulnerability of acute stress response in adult socially isolated rats

    Directory of Open Access Journals (Sweden)

    Mariangela Serra

    2014-06-01

    Full Text Available Adverse experiences occurred in early life and especially during childhood and adolescence can have negative impact on behavior later in life and the quality of maternal care is considered a critical moment that can considerably influence the development and the stress responsiveness in offspring. This review will assess how the association between neonatal and adolescence stressful experiences such as maternal separation and social isolation, at weaning, may influence the stress responsiveness and brain plasticity in adult rats. Three hours of separation from the pups (3-14 postnatal days significantly increased frequencies of maternal arched-back nursing and licking-grooming by dams across the first 14 days postpartum and induced a long-lasting increase in their blood levels of corticosterone. Maternal separation, which per sedid not modified brain and plasma allopregnanolone and corticosterone levels in adult rats, significantly reduced social isolation-induced decrease of the levels of these hormones. Moreover, the enhancement of corticosterone and allopregnanolone levels induced by foot shock stress in socially isolated animals that were exposed to maternal separation was markedly reduced respect to that observed in socially isolated animals. Our results suggest that in rats a daily brief separation from the mother during the first weeks of life, which per se did not substantially alter adult function and reactivity of hypothalamic-pituitary-adrenal (HPA axis, elicited a significant protection versus the subsequent long-term stressful experience such that induced by social isolation from weaning. Proceedings of the 10th International Workshop on Neonatology · Cagliari (Italy · October 22nd-25th, 2014 · The last ten years, the next ten years in NeonatologyGuest Editors: Vassilios Fanos, Michele Mussap, Gavino Faa, Apostolos Papageorgiou

  1. Investigation of effective factors of transient thermal stress of the MONJU-System components

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Masaaki; Hirayama, Hiroshi; Kimura, Kimitaka; Jinbo, M. [Toshiba Corp., Kawasaki, Kanagawa (Japan)

    1999-03-01

    Transient thermal stress of each system Component in the fast breeder reactor is an uncertain factor on it's structural design. The temperature distribution in a system component changes over a wide range in time and in space. An unified evaluation technique of thermal, hydraulic, and structural analysis, in which includes thermal striping, temperature stratification, transient thermal stress and the integrity of the system components, is required for the optimum design of tho fast reactor plant. Thermal boundary conditions should be set up by both the transient thermal stress analysis and the structural integrity evaluation of each system component. The reasonable thermal boundary conditions for the design of the MONJU and a demonstration fast reactor, are investigated. The temperature distribution analysis models and the thermal boundary conditions on the Y-piece structural parts of each system component, such as reactor vessel, intermediate heat exchanger, primary main circulation pump, steam generator, superheater and upper structure of reactor core, are illustrated in the report. (M. Suetake)

  2. Dioscin alleviates dimethylnitrosamine-induced acute liver injury through regulating apoptosis, oxidative stress and inflammation.

    Science.gov (United States)

    Zhang, Weixin; Yin, Lianhong; Tao, Xufeng; Xu, Lina; Zheng, Lingli; Han, Xu; Xu, Youwei; Wang, Changyuan; Peng, Jinyong

    2016-07-01

    In our previous study, the effects of dioscin against alcohol-, carbon tetrachloride- and acetaminophen-induced liver damage have been found. However, the activity of it against dimethylnitrosamine (DMN)-induced acute liver injury remained unknown. In the present study, dioscin markedly decreased serum ALT and AST levels, significantly increased the levels of SOD, GSH-Px, GSH, and decreased the levels of MDA, iNOS and NO. Mechanism study showed that dioscin significantly decreased the expression levels of IL-1β, IL-6, TNF-α, IκBα, p50 and p65 through regulating TLR4/MyD88 pathway to rehabilitate inflammation. In addition, dioscin markedly up-regulated the expression levels of SIRT1, HO-1, NQO1, GST and GCLM through increasing nuclear translocation of Nrf2 against oxidative stress. Furthermore, dioscin significantly decreased the expression levels of FasL, Fas, p53, Bak, Caspase-3/9, and upregulated Bcl-2 level through decreasing IRF9 level against apoptosis. In conclusion, dioscin showed protective effect against DMN-induced acute liver injury via ameliorating apoptosis, oxidative stress and inflammation, which should be developed as a new candidate for the treatment of acute liver injury in the future. PMID:27317992

  3. Association between Oxidative Stress and Outcome in Different Subtypes of Acute Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    Nai-Wen Tsai

    2014-01-01

    Full Text Available Objectives. This study investigated serum thiobarbituric acid-reactive substances (TBARS and free thiol levels in different subtypes of acute ischemic stroke (AIS and evaluated their association with clinical outcomes. Methods. This prospective study evaluated 100 AIS patients, including 75 with small-vessel and 25 with large-vessel diseases. Serum oxidative stress (TBARS and antioxidant (thiol were determined within 48 hours and days 7 and 30 after stroke. For comparison, 80 age- and sex-matched participants were evaluated as controls. Results. Serum TBARS was significantly higher and free thiol was lower in stroke patients than in the controls on days 1 and 7 after AIS. The level of free thiol was significantly lower in the large-vessel disease than in the small-vessel disease on day 7 after stroke. Using the stepwise logistic regression model for potential variables, only stroke subtype, NIHSS score, and serum TBARS level were independently associated with three-month outcome. Higher TBARS and lower thiol levels in the acute phase of stroke were associated with poor outcome. Conclusions. Patients with large-vessel disease have higher oxidative stress but lower antioxidant defense compared to those with small-vessel disease after AIS. Serum TBARS level at the acute phase of stroke is a potential predictor for three-month outcome.

  4. Crack prediction in EB-PVD thermal barrier coatings based on the simulation of residual stresses

    Science.gov (United States)

    Chen, J. W.; Zhao, Y.; Liu, S.; Zhang, Z. Z.; Ma, J.

    2016-07-01

    Thermal barrier coatings systems (TBCs) are widely used in the field of aerospace. The durability and insulating ability of TBCs are highly dependent on the residual stresses of top coatings, thus the investigation of the residual stresses is helpful to understand the failure mechanisms of TBCs. The simulation of residual stresses evolution in electron beam physical vapor deposition (EB-PVD) TBCs is described in this work. The interface morphology of TBCs subjected to cyclic heating and cooling is observed using scanning electron microscope (SEM). An interface model of TBCs is established based on thermal elastic-plastic finite method. Residual stress distributions in TBCs are obtained to reflect the influence of interfacial roughness. Both experimental and simulation results show that it is feasible to predict the crack location by stress analysis, which is crucial to failure prediction.

  5. Cooling-dominated cracking in thermally stressed volcanic rocks

    Science.gov (United States)

    Browning, John; Meredith, Philip; Gudmundsson, Agust

    2016-08-01

    Most studies of thermally induced cracking in rocks have focused on the generation of cracks formed during heating and thermal expansion. Both the nature and the mechanism of crack formation during cooling are hypothesized to be different from those formed during heating. We present in situ acoustic emission data recorded as a proxy for crack damage evolution in a series of heating and cooling experiments on samples of basalt and dacite. Results show that both the rate and the energy of acoustic emission are consistently much higher during cooling than during heating. Seismic velocity comparisons and crack morphology analysis of our heated and cooled samples support the contemporaneous acoustic emission data and also indicate that thermal cracking is largely isotropic. These new data are important for assessing the contribution of cooling-induced damage within volcanic structures and layers such as dikes, sills, and lava flows.

  6. The Mitochondrial Calcium Uniporter Selectively Matches Metabolic Output to Acute Contractile Stress in the Heart.

    Science.gov (United States)

    Kwong, Jennifer Q; Lu, Xiyuan; Correll, Robert N; Schwanekamp, Jennifer A; Vagnozzi, Ronald J; Sargent, Michelle A; York, Allen J; Zhang, Jianyi; Bers, Donald M; Molkentin, Jeffery D

    2015-07-01

    In the heart, augmented Ca(2+) fluxing drives contractility and ATP generation through mitochondrial Ca(2+) loading. Pathologic mitochondrial Ca(2+) overload with ischemic injury triggers mitochondrial permeability transition pore (MPTP) opening and cardiomyocyte death. Mitochondrial Ca(2+) uptake is primarily mediated by the mitochondrial Ca(2+) uniporter (MCU). Here, we generated mice with adult and cardiomyocyte-specific deletion of Mcu, which produced mitochondria refractory to acute Ca(2+) uptake, with impaired ATP production, and inhibited MPTP opening upon acute Ca(2+) challenge. Mice lacking Mcu in the adult heart were also protected from acute ischemia-reperfusion injury. However, resting/basal mitochondrial Ca(2+) levels were normal in hearts of Mcu-deleted mice, and mitochondria lacking MCU eventually loaded with Ca(2+) after stress stimulation. Indeed, Mcu-deleted mice were unable to immediately sprint on a treadmill unless warmed up for 30 min. Hence, MCU is a dedicated regulator of short-term mitochondrial Ca(2+) loading underlying a "fight-or-flight" response that acutely matches cardiac workload with ATP production.

  7. The Mitochondrial Calcium Uniporter Selectively Matches Metabolic Output to Acute Contractile Stress in the Heart

    Directory of Open Access Journals (Sweden)

    Jennifer Q. Kwong

    2015-07-01

    Full Text Available In the heart, augmented Ca2+ fluxing drives contractility and ATP generation through mitochondrial Ca2+ loading. Pathologic mitochondrial Ca2+ overload with ischemic injury triggers mitochondrial permeability transition pore (MPTP opening and cardiomyocyte death. Mitochondrial Ca2+ uptake is primarily mediated by the mitochondrial Ca2+ uniporter (MCU. Here, we generated mice with adult and cardiomyocyte-specific deletion of Mcu, which produced mitochondria refractory to acute Ca2+ uptake, with impaired ATP production, and inhibited MPTP opening upon acute Ca2+ challenge. Mice lacking Mcu in the adult heart were also protected from acute ischemia-reperfusion injury. However, resting/basal mitochondrial Ca2+ levels were normal in hearts of Mcu-deleted mice, and mitochondria lacking MCU eventually loaded with Ca2+ after stress stimulation. Indeed, Mcu-deleted mice were unable to immediately sprint on a treadmill unless warmed up for 30 min. Hence, MCU is a dedicated regulator of short-term mitochondrial Ca2+ loading underlying a “fight-or-flight” response that acutely matches cardiac workload with ATP production.

  8. Thermal Stability of Residual Stresses in Ti-6Al-4V components

    Science.gov (United States)

    Stanojevic, A.; Angerer, P.; Oberwinkler, B.

    2016-03-01

    The need for light weight design while maintaining a high safety is essential for many components, especially in the aircraft industry. Therefore, it's important to consider every aspect to reduce weight, improve fatigue life and maintain safety of crucial components. Residual stresses are a major factor which can positively influence components and fulfil all three requirements. However, due to the inconstancy of the behaviour of residual stresses during the life time of a component, residual stresses are often neglected. If the behaviour of residual stresses could be described reliably over the entire life time of a component, residual stresses could be taken into account and components could be optimized even further. Mechanical and thermal loads are the main reason for relaxation of residual stresses. This work covers the thermal stability of residual stresses in Ti-6Al-4V components. Therefore, exposure tests at raised temperatures were performed on specimens with different surface conditions. Residual stresses were measured by x-ray diffraction before and after testing. Creep tests were also carried out to describe the creep behaviour and thereby the ability for residual stress relaxation. A correlation between the creep rate and amount of relaxed stress was found. The creep behaviour of the material was described by using a combination of the Norton Power law and the Arrhenius equation. The Zener-Wert-Avrami model was used to describe the residual stress relaxation. With these models a satisfying correlation between measured and calculated data was found. Hence, the relaxation of residual stresses due to thermal load was described reliably.

  9. Chronic stress differentially affects antioxidant enzymes and modifies the acute stress response in liver of Wistar rats.

    Science.gov (United States)

    Djordjevic, J; Djordjevic, A; Adzic, M; Niciforovic, A; Radojcic, M B

    2010-01-01

    Clinical reports suggest close interactions between stressors, particularly those of long duration, and liver diseases, such as hepatic inflammation, that is proposed to occur via reactive oxygen species. In the present study we have used 21-day social isolation of male Wistar rats as a model of chronic stress to investigate protein expression/activity of liver antioxidant enzymes: superoxide dismutases (SODs), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GLR), and protein expression of their upstream regulators: glucocorticoid receptor (GR) and nuclear factor kappa B (NFkB). We have also characterized these parameters in either naive or chronically stressed animals that were challenged by 30-min acute immobilization. We found that chronic isolation caused decrease in serum corticosterone (CORT) and blood glucose (GLU), increase in NFkB signaling, and disproportion between CuZnSOD, peroxidases (CAT, GPx) and GLR, thus promoting H2O2 accumulation and prooxidative state in liver. The overall results suggested that chronic stress exaggerated responsiveness to subsequent stressor at the level of CORT and GLU, and potentiated GLR response, but compromised the restoration of oxido-reductive balance due to irreversible alterations in MnSOD and GPx. PMID:20406049

  10. Chronic and Acute Stress, Gender, and Serotonin Transporter Gene-Environment Interactions Predicting Depression Symptoms in Youth

    Science.gov (United States)

    Hammen, Constance; Brennan, Patricia A.; Keenan-Miller, Danielle; Hazel, Nicholas A.; Najman, Jake M.

    2010-01-01

    Background: Many recent studies of serotonin transporter gene by environment effects predicting depression have used stress assessments with undefined or poor psychometric methods, possibly contributing to wide variation in findings. The present study attempted to distinguish between effects of acute and chronic stress to predict depressive…

  11. Temporal Dynamics of Acute Stress-Induced Dendritic Remodeling in Medial Prefrontal Cortex and the Protective Effect of Desipramine

    DEFF Research Database (Denmark)

    Nava, Nicoletta; Treccani, Giulia; Alabsi, Abdelrahman;

    2015-01-01

    dendrites was observed at 1 day, which was prevented by chronic DMI, and at 14 days after stress exposure. Chronic DMI resulted in dendritic elaboration at 7 days but did not prevent the effects of FS-stress. Collectively, these data demonstrate that 1) acute stressors may induce rapid and sustained changes...

  12. Effects of methionine supplementation on the expression of oxidative stress-related genes in acute heat stress-exposed broilers.

    Science.gov (United States)

    Del Vesco, Ana Paula; Gasparino, Eliane; Grieser, Daiane de Oliveira; Zancanela, Vittor; Soares, Maria Amélia Menck; Neto, Adhemar Rodrigues de Oliveira

    2015-02-28

    The aim of the present study was to evaluate the effects of heat stress (HS) and methionine supplementation on the markers of stress and on the gene expression levels of uncoupling proteins (UCP), betaine-homocysteine methyltransferase (BHMT), cystathionine β-synthase (CBS), glutathione synthetase (GSS) and glutathione peroxidase 7 (GPx7). Broilers from 1 to 21 d and from 22 to 42 d of age were divided into three treatment groups related to methionine supplementation: without methionine supplementation (MD); recommended level of methionine supplementation (DL1); excess methionine supplementation (DL2). The broilers were either kept at a comfortable thermal temperature or exposed to HS (38°C for 24 h). During the starter period, we observed the effects of the interaction between diet and environment on the gene expression levels of UCP, BHMT and GSS. Higher gene expression levels of UCP and BHMT were observed in broilers that were maintained at thermal comfort conditions and received the MD diet. HS broilers fed the DL1 and DL2 diets had the highest expression level of GSS. The expression levels of the CBS and GPx7 genes were influenced by both the environment and methionine supplementation. During the grower period, the gene expression levels of BHMT, CBS, GSS and GPx7 were affected by the diet × environment interaction. A higher expression level of BHMT was observed in broilers maintained at thermal comfort conditions and on the MD diet. HS induced higher expression levels of CBS, GSS and GPx7 in broilers that received the DL1 and DL2 diets. The present results suggest that under HS conditions, methionine supplementation could mitigate the effects of stress, since methionine contributed to the increased expression levels of genes related to antioxidant activity.

  13. Human Thermal Comfort and Heat Stress in an Outdoor Urban Arid Environment: A Case Study

    Directory of Open Access Journals (Sweden)

    A. M. Abdel-Ghany

    2013-01-01

    Full Text Available To protect humans from heat stress risks, thermal comfort and heat stress potential were evaluated under arid environment, which had never been made for such climate. The thermal indices THI, WBGT, PET, and UTCI were used to evaluate thermal comfort and heat stress. RayMan software model was used to estimate the PET, and the UTCI calculator was used for UTCI. Dry and wet bulb temperatures (Td, Tw, natural wet bulb temperature (Tnw, and globe temperature (Tg were measured in a summer day to be used in the calculation. The results showed the following. (i The thermal sensation and heat stress levels can be evaluated by either the PET or UTCI scales, and both are valid for extremely high temperature in the arid environment. (ii In the comfort zone, around 75% of individuals would be satisfied with the surrounding environment and feel comfortable during the whole day. (iii Persons are exposed to strong heat stress and would feel uncomfortable most of the daytime in summer. (iv Heat fatigue is expected with prolonged exposure to sun light and activity. (v During the daytime, humans should schedule their activities according to the highest permissible values of the WBGT to avoid thermal shock.

  14. Attenuation of acute and chronic restraint stress-induced perturbations in experimental animals by Zingiber officinale Roscoe.

    Science.gov (United States)

    Lakshmi, B V S; Sudhakar, M

    2010-02-01

    Ethanolic extract of rhizomes of Zingiber officinale was investigated on anoxia stress tolerance test in Swiss mice. The animals were also subjected to acute physical stress (swimming endurance test) to gauge the anti-stress potential of the extract. Further to evaluate the anti-stress activity of Z. officinale in chronic stress condition, fresh Wistar rats were subjected to cold restraint stress (4 degrees for 2 h) for 10 days. Stimulation of hypothalamus pituitary adrenal axis in stressful condition alters plasma glucose, triglyceride, cholesterol, BUN and corticosterone levels. There is also alteration in the blood cell counts. Pretreatment with the extract significantly ameliorated the stress-induced variations in these biochemical levels and blood cell counts in both acute and chronic stress models. The extract treated animals showed increase in swimming endurance time and increase in anoxia tolerance time in physical and anoxia stress models, respectively. Treatment groups also reverted back increase in liver, adrenal gland weights and atrophy of spleen caused by cold chronic stress and swimming endurance stress models. The results indicate that ethanolic extract of Z. officinale has significant adaptogenic activity against a variety of biochemical and physiological perturbations in different stress models. PMID:19909780

  15. Research of thermal stress between long linear MCT arrays and lead board using FEM

    Science.gov (United States)

    Wu, Wen; Wu, Yonghong; Liu, Dafu

    2010-10-01

    For the long wavelength infrared detection, HgCdTe (MCT) photoconductive devices are selected as the core of next-generation meteorological because of its mature fabrication technique and stable performance. During the assembly process, an innovative multilayer ceramic board providing mechanical support is designed as the electrical interconnection between MCT chips and external circuits for cryogenic application. Furthermore, due to its brittleness, long linear MCT device is normally glued to sapphire substrates on the multilayer ceramic board with cryogenic glue. Thus, it can be seen clearly that the assembly structure is a multilayer configuration which comprises various kinds of materials, including ceramic broad, sapphire, MCT and glues. As a result, the difference in Thermal Expansion Coefficient (TEC) between the layers could create the potential to introduce thermal stress at working environmental temperature (approximately 70K), which could result in device performance degradation, even die crack. This article analyzes the thermal stress between long linear MCT devices and a multilayer ceramic board by using Finite Element Method (FEM). According to analysis results, two factors are revealed as the most significant causes for introducing thermal stress: one is the sapphire substrate thickness; the other is the parameters of various materials, for instance Yong's modulus and TEC. Since the structure of MCT detector is determined by system requirements and is under the limitation of manufacture technology, this article reveals two effective approaches to reduce the unavoidable thermal stress: first, choosing the appropriate thickness of ceramic board which is made by Al2O3; second, adding another metal cushion Invar. With the above considerations, the distribution of thermal stress is simulated using FEM under different parameter conditions. Based on the results of simulations, an optimal design of package structure which could improve the reliability of

  16. Acute effects of nandrolone decanoate on oxidative stress in isolated rat heart

    Directory of Open Access Journals (Sweden)

    Jevđević Maja

    2015-01-01

    Full Text Available Abuse of anabolic-androgenic steroids (AAS produces side effects in different tissues, with oxidative stress linked to their pathophysiology, being involved in fibrosis, cellular proliferation, and tumorigenesis. The aim of this study was to examine the acute effects of nandrolone decanoate (ND on oxidative stress in isolated rat heart. The hearts of male Wistar albino were excised and perfused according to the Langendorff technique at gradually increasing coronary perfusion pressures (40-120 cmH2O. The hearts were perfused with ND at doses of 1, 10 and 100 μM. Oxidative stress markers, including the index of lipid peroxidation (thiobarbituric acid reactive substances (TBARS, nitric oxide (nitrites; NO2-, the superoxide anion radical (O2- and hydrogen peroxide (H2O2 were measured in the coronary venous effluent. Our results showed that acute effects of ND do not promote the production of reactive oxygen species (ROS. Our finding pointed out that the highest concentration of ND may even possess some anti-oxidative potential, which should be examined further.

  17. Study on the frequency response mechanisms of thermal stress induced by thermal stratification oscillation phenomenon

    International Nuclear Information System (INIS)

    The temperature oscillation produced by thermal stratification phenomenon induces thermal fatigue damages on structures of nuclear components, which should be prevented. To evaluate thermal fatigue, the frequency response function was developed. However, this theoretical method does not take particular effects of thermal stratification oscillation into account. To clarify these effects, finite element simulations were conducted with two fluid temperature models. Based on mechanisms of the effects, the frequency response function was improved. Agreement with the results of the finite element simulations confirmed the proposed function. (author)

  18. Regulation of apoptotic pathways by Stylophora pistillata (Anthozoa, Pocilloporidae to survive thermal stress and bleaching.

    Directory of Open Access Journals (Sweden)

    Hagit Kvitt

    Full Text Available Elevated seawater temperatures are associated with coral bleaching events and related mortality. Nevertheless, some coral species are able to survive bleaching and recover. The apoptotic responses associated to this ability were studied over 3 years in the coral Stylophora pistillata from the Gulf of Eilat subjected to long term thermal stress. These include caspase activity and the expression profiles of the S. pistillata caspase and Bcl-2 genes (StyCasp and StyBcl-2-like cloned in this study. In corals exposed to thermal stress (32 or 34°C, caspase activity and the expression levels of the StyBcl-2-like gene increased over time (6-48 h and declined to basal levels within 72 h of thermal stress. Distinct transcript levels were obtained for the StyCasp gene, with stimulated expression from 6 to 48 h of 34°C thermal stress, coinciding with the onset of bleaching. Increased cell death was detected in situ only between 6 to 48 h of stress and was limited to the gastroderm. The bleached corals survived up to one month at 32°C, and recovered back symbionts when placed at 24°C. These results point to a two-stage response in corals that withstand thermal stress: (i the onset of apoptosis, accompanied by rapid activation of anti-oxidant/anti-apoptotic mediators that block the progression of apoptosis to other cells and (ii acclimatization of the coral to the chronic thermal stress alongside the completion of symbiosis breakdown. Accordingly, the coral's ability to rapidly curb apoptosis appears to be the most important trait affecting the coral's thermotolerance and survival.

  19. Investigation of risk factors for acute stress reaction following induced abortion

    Directory of Open Access Journals (Sweden)

    Vukelić Jelka

    2010-01-01

    Full Text Available Introduction. Termination of pregnancy - induced abortion is inevitable in family planning as the final solution in resolving unwanted pregnancies. It can be the cause of major physical and phychological concequences on women’s health. Diverse opinions on psychological consequences of induced abortion can be found in literature. Material and methods. A prospective study was performed in order to predict acute stress disorder (ASD after the induced abortion and the possibility of post-traumatic stress disorder (PTSD. Seven days after the induced abortion, 40 women had to fill in: 1. a special questionnaire made for this investigation, with questions linked to some risk factors inducing stress, 2. Likert’s emotional scale and 3. Bryant’s acute stress reaction scale. Results. After an induced abortion 52.5% women had ASD and 32.5% women had PTSD. Women with ASD after the abortion developed more sense of guilt, irritability, shame, self-judgement, fear from God and self-hatred. They were less educated, had lower income, they were more religious, did not approve of abortion and had worse relationship with their partners after the abortion in comparison to women without ASD. Age, number of previous abortions and decision to abort did not differ between the two groups. Discussion and conclusion. Induced abortion represents a predisposing factor for ASD and PTSD in women. Some psychosocial factors contribute to the development of stress after abortion. Serbia has a task to reduce the number of abortions which is very high, in order, to preserve reproductive and phychological health of women.

  20. Early detection of oil-induced stress in crops using spectral and thermal responses

    Science.gov (United States)

    Emengini, Ebele Josephine; Blackburn, George Alan; Theobald, Julian Charles

    2013-01-01

    Oil pollution is a major source of environmental degradation, and requires accurate monitoring and timely detection for an effective control of its occurrence. This paper examines the potential of a remote sensing approach using the spectral and thermal responses of crops for the early detection of stress caused by oil pollution. In a glasshouse, pot-grown maize was treated with oil at sublethal and lethal applications. Thereafter, leaf thermal, spectral and physiological measurements were taken every two to three days to monitor the development of stress responses. Our results indicate that absolute leaf temperature was a poor indicator of developing stress. However, a derived thermal index (IG) responded consistently in the early stages of physiological damage. Various spectral reflectance features were highly sensitive to oil-induced stress. A narrow-band index using wavelengths in the near-infrared and red-edge region, (R755-R716)/(R755+R716), was optimal for previsual detection of oil-induced stress. This index had a strong linear relationship with photosynthetic rate. This indicates that by detecting vegetation stress, thermal and hyperspectral remote sensing has considerable potential for the timely detection of oil pollution in the environment.

  1. Discrimination of plant stress caused by oil pollution and waterlogging using hyperspectral and thermal remote sensing

    Science.gov (United States)

    Emengini, Ebele Josephine; Blackburn, George Alan; Theobald, Julian Charles

    2013-01-01

    Remote sensing of plant stress holds promise for detecting environmental pollution by oil. However, in oil-rich delta regions, waterlogging is a frequent source of plant stress that has similar physiological effects to oil pollution. This study investigated the capabilities of remote sensing for discriminating between these two sources of plant stress. Bean plants were subjected to oil pollution, waterlogging, and combined oil and waterlogging treatments. Canopy physiological, hyperspectral, and thermal measurements were taken every two to three days after treatment to follow the stress responses. For plants treated with oil, spectral and thermal responses were evident six days before symptoms could be observed visually. In waterlogged plants, only spectral responses were observed, but these were present up to eight days before visual symptoms. A narrowband reflectance ratio was efficient in detecting stress caused by oil and waterlogging. Canopy temperature and a thermal index were good indicators of oil and combined oil and waterlogging stress, but insensitive to waterlogging alone. Hence, this study provides evidence that combined hyperspectral and thermal remote sensing of vegetation has potential for monitoring oil pollution in environments that are also subjected to waterlogging.

  2. Is gill cortisol concentration a good acute stress indicator in fish? A study in rainbow trout and zebrafish

    DEFF Research Database (Denmark)

    Gesto, Manuel; Hernandez, Juan; Lopez-Patino, Marcos A.;

    2015-01-01

    -invasive techniques have been developed to measure cortisol directly in the water from fish-holding tanks, in skin mucus or in scales. In this study, we explored the possibility to analyze fish cortisol from gill filaments as a reliable acute stress marker. Our results show that gill cortisol levels correlate well...... with plasma cortisol levels in both rainbow trout and zebrafish exposed or not to an acute stress protocol. Measuring cortisol in gill filaments increases the available possibilities for stress assessment in fish. Although this approach should yet be tested for its use with other stressors, it has several...

  3. When depth is no refuge: cumulative thermal stress increases with depth in Bocas del Toro, Panama

    Science.gov (United States)

    Neal, B. P.; Condit, C.; Liu, G.; dos Santos, S.; Kahru, M.; Mitchell, B. G.; Kline, D. I.

    2014-03-01

    Coral reefs are increasingly affected by high-temperature stress events and associated bleaching. Monitoring and predicting these events have largely utilized sea surface temperature data, due to the convenience of using large-scale remotely sensed satellite measurements. However, coral bleaching has been observed to vary in severity throughout the water column, and variations in coral thermal stress across depths have not yet been well investigated. In this study, in situ water temperature data from 1999 to 2011 from three depths were used to calculate thermal stress on a coral reef in Bahia Almirante, Bocas del Toro, Panama, which was compared to satellite surface temperature data and thermal stress calculations for the same area and time period from the National Oceanic and Atmospheric Administration Coral Reef Watch Satellite Bleaching Alert system. The results show similar total cumulative annual thermal stress for both the surface and depth-stratified data, but with a striking difference in the distribution of that stress among the depth strata during different high-temperature events, with the greatest thermal stress unusually recorded at the deepest measured depth during the most severe bleaching event in 2005. Temperature records indicate that a strong density-driven temperature inversion may have formed in this location in that year, contributing to the persistence and intensity of bleaching disturbance at depth. These results indicate that depth may not provide a stress refuge from high water temperature events in some situations, and in this case, the water properties at depth appear to have contributed to greater coral bleaching at depth compared to near-surface locations. This case study demonstrates the importance of incorporating depth-stratified temperature monitoring and small-scale oceanographic and hydrologic data for understanding and predicting local reef responses to elevated water temperature events.

  4. Thermal stress measurement in continuous welded rails using the hole-drilling method

    Science.gov (United States)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2016-04-01

    The absence of expansion joints in Continuous Welded Rail (CWR) has created the need for the railroad industry to determine the in-situ level of thermal stresses so as to prevent train accidents caused by rail buckling in hot weather and by rail breakage in cold weather. The development of non-destructive or semi-destructive methods for determining the level of thermal stresses in rails is today a high research priority. This study explores the known hole-drilling method as a possible solution to this problem. A new set of calibration coefficients to compute the relieved stress field with the finer hole depth increments was determined by a 3D Finite Element Analysis that modeled the entire hole geometry, including the mechanics of the hole bottom and walls. To compensate the residual stress components, a linear relationship was experimentally established between the longitudinal and the vertical residual stresses of two common sizes of rails, the 136RE and the 141RE, with statistical significance. This result was then utilized to isolate the longitudinal thermal stress component in hole-drilling tests conducted on the 136RE and 141RE thermally-loaded rails at the Large-scale CWR Test-bed of UCSD's Powell Research Laboratories. The results from the Test-bed showed that the hole-drilling procedure, with the appropriate residual stress compensation, can indeed estimate the in-situ thermal stresses to achieve a +/-5°F accuracy of Neutral Temperature determination with a 90% statistical confidence, which is the desired industry gold standard.

  5. Acute stress alters autonomic modulation during sleep in women approaching menopause.

    Science.gov (United States)

    de Zambotti, Massimiliano; Sugarbaker, David; Trinder, John; Colrain, Ian M; Baker, Fiona C

    2016-04-01

    Hot flashes, hormones, and psychosocial factors contribute to insomnia risk in the context of the menopausal transition. Stress is a well-recognized factor implicated in the pathophysiology of insomnia; however the impact of stress on sleep and sleep-related processes in perimenopausal women remains largely unknown. We investigated the effect of an acute experimental stress (impending Trier Social Stress Task in the morning) on pre-sleep measures of cortisol and autonomic arousal in perimenopausal women with and without insomnia that developed in the context of the menopausal transition. In addition, we assessed the macro- and micro-structure of sleep and autonomic functioning during sleep. Following adaptation to the laboratory, twenty two women with (age: 50.4 ± 3.2 years) and eighteen women without (age: 48.5 ± 2.3 years) insomnia had two randomized in-lab overnight recordings: baseline and stress nights. Anticipation of the task resulted in higher pre-sleep salivary cortisol levels and perceived tension, faster heart rate and lower vagal activity, based on heart rate variability measures, in both groups of women. The effect of the stress manipulation on the autonomic nervous system extended into the first 4 h of the night in both groups. However, vagal tone recovered 4-6 h into the stress night in controls but not in the insomnia group. Sleep macrostructure was largely unaltered by the stress, apart from a delayed latency to REM sleep in both groups. Quantitative analysis of non-rapid eye movement sleep microstructure revealed greater electroencephalographic (EEG) power in the beta1 range (15-≤23 Hz), reflecting greater EEG arousal during sleep, on the stress night compared to baseline, in the insomnia group. Hot flash frequency remained similar on both nights for both groups. These results show that pre-sleep stress impacts autonomic nervous system functioning before and during sleep in perimenopausal women with and without insomnia. Findings also indicate

  6. Chronic desipramine prevents acute stress-induced reorganization of medial prefrontal cortex architecture by blocking glutamate vesicle accumulation and excitatory synapse increase

    DEFF Research Database (Denmark)

    Nava, Nicoletta; Treccani, Giulia; Liebenberg, Nico;

    2014-01-01

    While a clear negative influence of chronic exposure to stressful experiences has been repeatedly demonstrated, the outcome of acute stress on key brain regions has only just started to be elucidated. Although it has been proposed that acute stress may produce enhancement of brain plasticity...

  7. Trait Hostility and Acute Inflammatory Responses to Stress in the Laboratory.

    Science.gov (United States)

    Girard, Dominique; Tardif, Jean-Claude; Boisclair Demarble, Julie; D'Antono, Bianca

    2016-01-01

    Hostility has been associated with higher basal levels of inflammation. The present study evaluated the association of hostility with acute stress-induced changes in inflammatory activity. One hundred and ninety-nine healthy men and women, aged 19-64 years, were exposed to a stress protocol involving four interpersonal stressors. Participants completed the Cook-Medley Hostility questionnaire and provided two blood samples for the measurement of inflammatory biomarkers (CRP, Il-6, MPO, TNF-α, MCP-1, Il-8, Il-10, and Il-18), prior to and following exposure to a standardized stress protocol. In univariate analyses, hostility was associated with significantly higher TNF-α, but lower Il-8 and Il-18 values post-stress, though only Il-8 remained significant after controlling for baseline differences. In multivariate analyses, a significant Age by Hostility interaction emerged for Il-6, while sex moderated the relation between hostility and Il-10 reactivity. Following stress, hostility was associated with greater pro-inflammatory Il-6 activity among younger individuals and to decreased anti-inflammatory Il-10 activity in women. Future research is needed to replicate these findings and to evaluate their implication for disease. PMID:27270459

  8. Effects of different kinds of acute stress on nerve growth factor content in rat brain.

    Science.gov (United States)

    von Richthofen, Sita; Lang, Undine E; Hellweg, Rainer

    2003-10-17

    Nerve growth factor (NGF) has several effects on the central nervous system; on the one hand NGF fosters survival and function of cholinergic neurons of the basal forebrain, on the other hand this protein is implicated in the stress response of the hypothalamic-pituitary-adrenocortical axis (HPAA). In this study we tested the influence of threatening and painful stress treatments in three different intensities as well as forced motoric activity on NGF content in different brain areas in adult rats. We found that threatening treatment with or without painful stimuli was followed by a significant decrease of NGF concentration in the amygdala (44.5%; P=0.03) and the frontal cortex (-45.5%; P=0.02). We also observed that after stress of forced motoric activity NGF content in the frontal cortex (-32%; P=0.01) and the hippocampus (-32%; P=0.006) was significantly reduced. Thus, NGF content in distinct brain regions is decreased, following different forms of acute stress. This might be relevant for the pathophysiological understanding of psychiatric diseases, such as depression, which are associated with stress.

  9. Cold stress aggravates inflammatory responses in an LPS-induced mouse model of acute lung injury

    Science.gov (United States)

    Joo, Su-Yeon; Park, Mi-Ju; Kim, Kyun-Ha; Choi, Hee-Jung; Chung, Tae-Wook; Kim, Yong Jin; Kim, Joung Hee; Kim, Keuk-Jun; Joo, Myungsoo; Ha, Ki-Tae

    2016-08-01

    Although the relationship between environmental cold temperature and susceptibility to respiratory infection is generally accepted, the effect of ambient cold temperature on host reactivity in lung inflammation has not been fully studied. To examine the function of ambient cold temperature on lung inflammation, mice were exposed to 4 °C for 8 h each day for 14 days. In the lungs of mice exposed to cold stress, inflammatory cells in bronchoalveolar lavage (BAL) fluid and lung tissues were slightly increased by about twofold. However, the structures of pulmonary epithelial cells were kept within normal limits. Next, we examined the effect of cold stress on the inflammatory responses in a lipopolysaccharide (LPS)-induced acute lung injury (ALI) mouse model. The infiltration of neutrophils and inflammation of lung tissue determined by histology were significantly increased by exposure to ambient cold temperature. In addition, the production of pro-inflammatory cytokines including interleukin (IL)-12, IL-17, and monokine induced by gamma interferon (MIG) was elevated by exposure to cold stress. Therefore, we suggest that cold stress is a factor that exacerbates lung inflammation including ALI. To our knowledge, this is the first report on the relationship between cold stress and severity of lung inflammation.

  10. A Numerical Investigation of the Thermal Stresses of a Planar Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Paulina Pianko-Oprych

    2016-09-01

    Full Text Available A typical operating temperature of a solid oxide fuel cell (SOFC is quite high above 750 °C and affects the thermomechanical behavior of the cell. Thermal stresses may cause microstructural instability and sub-critical cracking. Therefore, a joint analysis by the computational fluid dynamics (CFD and computational structural mechanics based on the finite element method (FEM was carried out to analyze thermal stresses in a planar SOFC and to predict potential failure locations in the cell. A full numerical model was based on the coupling of thermo-fluid model with the thermo-mechanical model. Based on a temperature distribution from the thermo-fluid model, stress distribution including the von Mises stress, shear stress as well as the operating principal stress were derived in the thermo-mechanical model. The FEM calculations were performed under different working conditions of the planar SOFC. The highest total stress was noticed at the lower operating voltage of 0.3 V, while the lowest total stress was determined at the voltage of 0.7 V. The obtained stress distributions allowed a better understanding of details of internal processes occurring within the SOFC and provided helpful guidance in the optimization of a new SOFC design.

  11. Perceived Thermal Discomfort and Stress Behaviours Affecting Students’ Learning in Lecture Theatres in the Humid Tropics

    Directory of Open Access Journals (Sweden)

    Tamaraukuro Tammy Amasuomo

    2016-04-01

    Full Text Available The study investigated the relationship between students’ perceived thermal discomfort and stress behaviours affecting their learning in lecture theatres in the humid tropics. Two lecture theatres, LTH-2 and 3, at the Niger Delta University, Nigeria, were used for the study. Two groups of students from the Faculties of Agriculture and Engineering and the Department of Technology Education constituted the population. The sample size selected through random sampling for Groups A and B was 210 and 370 students, respectively. Objective and self-report instruments were used for data collection. The objective instrument involved physical measurement of the two lecture theatres and of the indoor temperature, relative humidity and air movement. The self-report instrument was a questionnaire that asked for the students perceived indoor thermal discomfort levels and the effect of indoor thermal comfort level on perceived stress behaviours affecting their learning. The objective indoor environmental data indicated thermal discomfort with an average temperature of 29–32 °C and relative humidity of 78% exceeding the ASHARE [1] and Olgyay [2].The students’ experienced a considerable level of thermal discomfort and also perceived that stress behaviours due to thermal discomfort affected their learning. Further, there were no significant differences in the perceived thermal discomfort levels of the two groups of students in LTH-2 and 3. Furthermore, stress behaviours affecting learning as perceived by the two groups of students did not differ significantly. In addition, no correlation existed between the perceived indoor thermal discomfort levels and stress behaviour levels affecting learning for students in LTH-2, because the arousal level of the students in the thermal environment was likely higher than the arousal level for optimal performance [3,4]. However, a correlation existed in the case of students in LTH-3, which was expected because it only

  12. Thermal stress induced voids in nanoscale copper interconnects by in-situ TEM heating

    Science.gov (United States)

    An, Jin Ho

    Stress induced void formation in Cu interconnects, due to thermal stresses generated during the processing of semiconductors, is an increasing reliability issue in the semiconductor industry as Cu interconnects are being downscaled to follow the demand for faster chip speed. In this work, 1.8 micron and 180 nm wide Cu interconnects, fabricated by Freescale Semiconductors, were subjected to thermal cycles, in-situ in the TEM, to investigate the stress relaxation mechanisms as a function of interconnect linewidth. The experiments show that the 1.8 micron Cu interconnect lines relax the thermal stresses through dislocation nucleation and motion while the Cu interconnect 180 nm lines exhibit void formation. Void formation in 180 nm lines occurs predominantly at triple junctions where the Ta diffusion barrier meets a Cu grain boundary. In order to understand void formation in 180 nm lines, the grain orientation and local stresses are determined. In particular, Nanobeam Diffraction (NBD) in the TEM is used to obtain the diffraction pattern of each grain, from which the crystal orientation is evaluated by the ACT (Automated Crystallography for TEM) software. In addition, 2D Finite Element Method (FEM) simulations are performed using the Object Oriented Finite Modeling (OOF2) software to correlate grain orientation with local stresses, and consequently void formation. According to the experimental and simulation results obtained, void formation in 180nm Cu interconnects does not seem to be solely dependent on local stresses, but a combination of diffusion paths available, stress gradients and possibly the presence of defects. In addition, based on the in-situ TEM observations, void growth seems to occur through grain boundary and/or interfacial diffusion. However, in-situ STEM observations of fully opened voids post-failure show pileup of material at the Cu grain surfaces. This means that surface or interface diffusion is also very active during void growth in the presence

  13. Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants.

    Directory of Open Access Journals (Sweden)

    Laura Musazzi

    Full Text Available BACKGROUND: Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release. METHODOLOGY/FINDINGS: Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated, and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486. On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats. Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability. CONCLUSIONS/SIGNIFICANCE: Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes

  14. The Prefrontal Cortex Communicates with the Amygdala to Impair Learning after Acute Stress in Females but Not in Males

    OpenAIRE

    Lisa Y. Maeng; Waddell, Jaylyn; Shors, Tracey J.

    2010-01-01

    Acute stress exposure enhances classical eyeblink conditioning in male rats, whereas exposure to the same event dramatically impairs performance in females (Wood & Shors, 1998; Wood et al., 2001). We hypothesized that stress affects learning differently in males and females because different brain regions and circuits are being activated. In the first experiment, we determined that neuronal activity within the medial prefrontal cortex (mPFC) during the stressful event is necessary to disrupt ...

  15. Bond strength and stress measurements in thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Jordan, E.

    1995-12-31

    Thermal barrier coatings have been used extensively in aircraft gas turbines for more than 15 years to insulate combustors and turbine vanes from the hot gas stream. Plasma sprayed thermal barrier coatings (TBCs) provide metal temperature reductions as much as 300{degrees}F, with improvements in durability of two times or more being achieved. The introduction of TBCs deposited by electron beam physical vapor deposition (EB-PVD) processes in the last five years has provided a major improvement in durability and also enabled TBCs to be applied to turbine blades for improved engine performance. This program evaluates the bond strength of yttria stabilized zirconia coatings with MCrAlY and Pt-Al bond coats utilizing diffraction and fluorescence methods.

  16. Analysis on Interface Shear Stress of Thermally Insulated Ocean Pipelines Under Installation

    Institute of Scientific and Technical Information of China (English)

    YAN Shu-wang; TIAN Ying-hui; LIU Run; WANG Zhang-ling; WANG Jin-ying

    2006-01-01

    It has been proved that the thermally insulated ocean pipeline has advantages over the conventional pipe-in-pipe pipeline. The risk of using the thermally insulated pipeline is that the exterior layers covering the steel pipe may be pulled off if the shear stress on the interface induced by the pullout force from the tensioner is greater than the binding force between two neighboring layers during installation. This paper develops a procedure to calculate the shear stress on the interface. The binding force between two neighboring layers can be determined with full scale model tests. The safety of the thermally insulated pipe under installation can then be checked by comparison of the interface shear stress with the binding force.

  17. Lipocalin 2 regulation by thermal stresses: Protective role of Lcn2/NGAL against cold and heat stresses

    Energy Technology Data Exchange (ETDEWEB)

    Roudkenar, Mehryar Habibi, E-mail: roudkenar@ibto.ir [Research Center, Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Halabian, Raheleh [Research Center, Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Roushandeh, Amaneh Mohammadi [Department of Anatomy, Faculty of Medicine, Medical University of Tabriz, Tabriz (Iran, Islamic Republic of); Nourani, Mohammad Reza [Chemical Injury Research Center, Baqiyatallah Medical Science University, Tehran (Iran, Islamic Republic of); Masroori, Nasser [Research Center, Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Ebrahimi, Majid [Research Center, Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Chemical Injury Research Center, Baqiyatallah Medical Science University, Tehran (Iran, Islamic Republic of); Nikogoftar, Mahin; Rouhbakhsh, Mehdi; Bahmani, Parisa [Research Center, Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Najafabadi, Ali Jahanian [Department of Molecular Biology, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali [National Cell Bank of Iran, Pasteur institute of Iran, Tehran (Iran, Islamic Republic of)

    2009-11-01

    Environmental temperature variations are the most common stresses experienced by a wide range of organisms. Lipocalin 2 (Lcn2/NGAL) is expressed in various normal and pathologic conditions. However, its precise functions have not been fully determined. Here we report the induction of Lcn2 by thermal stresses in vivo, and its role following exposure to cold and heat stresses in vitro. Induction of Lcn2 in liver, heart and kidney was detected by RT-PCR, Western blot and immunohistochemistry following exposure of mice to heat and cold stresses. When CHO and HEK293T cells overexpressing NGAL were exposed to cold stress, cell proliferation was higher compared to controls. Down-regulatrion of NGAL by siRNA in A549 cells resulted in less proliferation when exposed to cold stress compared to control cells. The number of apoptotic cells and expression of pro-apoptotic proteins were lower in the NGAL overexpressing CHO and HEK293T cells, but were higher in the siRNA-transfected A549 cells compared to controls, indicating that NGAL protects cells against cold stress. Following exposure of the cells to heat stress, ectopic expression of NGAL protected cells while addition of exogenous recombinant NGAL to the cell culture medium exacerbated the toxicity of heat stress specially when there was low or no endogenous expression of NGAL. It had a dual effect on apoptosis following heat stress. NGAL also increased the expression of HO-1. Lcn2/NGAL may have the potential to improve cell proliferation and preservation particularly to prevent cold ischemia injury of transplanted organs or for treatment of some cancers by hyperthermia.

  18. The effects of acute stress exposure on neural correlates of Pavlovian conditioning with monetary gains and losses

    Directory of Open Access Journals (Sweden)

    Andrea H Lewis

    2014-05-01

    Full Text Available Pavlovian conditioning involves the association of an inherently neutral stimulus with an appetitive or aversive outcome, such that the neutral stimulus itself acquires reinforcing properties. Across species, this type of learning has been shown to involve subcortical brain regions such as the striatum and the amygdala. It is less clear, however, how the neural circuitry involved in the acquisition of Pavlovian contingencies in humans is affected by acute stress. In the current study, we investigate the effect of acute stress exposure on Pavlovian conditioning using monetary reinforcers. Participants underwent a partial reinforcement conditioning procedure in which neutral stimuli were paired with high and low magnitude monetary gains and losses. A between-subjects design was used, such that half of the participants were exposed to cold stress while the remaining participants were exposed to a no stress control procedure. Cortisol measurements and subjective ratings were used as measures of stress. We observed an interaction between stress, valence and magnitude in the ventral striatum, with the peak in the putamen. More specifically, the stress group exhibited an increased sensitivity to magnitude in the gain domain. This effect was driven by those participants who experienced a larger increase in circulating cortisol levels in response to the stress manipulation. Taken together, these results suggest that acute stress can lead to individual differences in circulating cortisol levels which influence brain regions involved in associative learning such as the ventral striatum.

  19. The effects of acute stress exposure on striatal activity during Pavlovian conditioning with monetary gains and losses.

    Science.gov (United States)

    Lewis, Andrea H; Porcelli, Anthony J; Delgado, Mauricio R

    2014-01-01

    Pavlovian conditioning involves the association of an inherently neutral stimulus with an appetitive or aversive outcome, such that the neutral stimulus itself acquires reinforcing properties. Across species, this type of learning has been shown to involve subcortical brain regions such as the striatum and the amygdala. It is less clear, however, how the neural circuitry involved in the acquisition of Pavlovian contingencies in humans, particularly in the striatum, is affected by acute stress. In the current study, we investigate the effect of acute stress exposure on Pavlovian conditioning using monetary reinforcers. Participants underwent a partial reinforcement conditioning procedure in which neutral stimuli were paired with high and low magnitude monetary gains and losses. A between-subjects design was used, such that half of the participants were exposed to cold stress while the remaining participants were exposed to a no stress control procedure. Cortisol measurements and subjective ratings were used as measures of stress. We observed an interaction between stress, valence, and magnitude in the ventral striatum, with the peak in the putamen. More specifically, the stress group exhibited an increased sensitivity to magnitude in the gain domain. This effect was driven by those participants who experienced a larger increase in circulating cortisol levels in response to the stress manipulation. Taken together, these results suggest that acute stress can lead to individual differences in circulating cortisol levels which influence the striatum during Pavlovian conditioning with monetary reinforcers.

  20. Thermal Stresses in an Anisotropic Thin Plate Subjected to Moving Plane Heat Sources

    Directory of Open Access Journals (Sweden)

    Malak Naji

    2014-04-01

    Full Text Available The aim of this study is to numerically simulate the plane moving heat source through anisotropic mild steal thin plate. Heat conduction problems in anisotropic material, where the thermal conductivity varies with direction and involving a moving heat source have several industrial applications, such like metal cutting, flame or laser hardening of metals, welding and others. The parabolic heat conduction model is used for the prediction of the temperature history. The temperature distribution inside the plate is determined from the solution of heat equation. Thus, the heat equation is solved numerically using finite deference method and the temperature distributions are determined. The thermal stresses in this case are, also, investigated and computed numerically. It is found that the thermal conductivity ratio affect in both temperature and thermal stresses distributions, in additional to the speed and heat source intensity.

  1. miRNA-dysregulation associated with tenderness variation induced by acute stress in Angus cattle

    Directory of Open Access Journals (Sweden)

    Zhao Chunping

    2012-06-01

    Full Text Available Abstract miRNAs are a class of small, single-stranded, non-coding RNAs that perform post-transcriptional repression of target genes by binding to 3’ untranslated regions. Research has found that miRNAs involved in the regulation of many metabolic processes. Here we uncovered that the beef quality of Angus cattle sharply diversified after acute stress. By performing miRNA microarray analysis, 13 miRNAs were significantly differentially expressed in stressed group compared to control group. Using a bioinformatics method, 135 protein-coding genes were predicted as the targets of significant differentially expressed miRNAs. Gene Ontology (GO term and Ingenuity Pathway Analysis (IPA mined that these target genes involved in some important pathways, which may have impact on meat quality and beef tenderness.

  2. Posterior midline activation during symptom provocation in acute stress disorder: An fMRI study

    Directory of Open Access Journals (Sweden)

    Jan Christopher Cwik

    2014-05-01

    Full Text Available Functional imaging studies of patients with Posttraumatic Stress Disorder showed wide-spread activation of mid-line cortical areas during symptom provocation i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with Acute Stress Disorder (ASD shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in mid-line cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients.

  3. Mucus sugar content shapes the bacterial community structure in thermally stressed Acropora muricata

    OpenAIRE

    Lee, Sonny T. M.; Davy, Simon K.; Sen-Lin eTang; Kench, Paul S.

    2016-01-01

    It has been proposed that the chemical composition of a coral’s mucus can influence the associated bacterial community. However, information on this topic is rare, and non-existent for corals that are under thermal stress. This study therefore compared the carbohydrate composition of mucus in the coral Acropora muricata when subjected to increasing thermal stress from 26°C to 31°C, and determined whether this composition correlated with any changes in the bacterial community. Results showed t...

  4. Laser cutting of Kevlar laminates and thermal stress formed at cutting sections

    Science.gov (United States)

    Yilbas, B. S.; Akhtar, S. S.

    2012-02-01

    Laser cutting of Kevlar laminates is carried out and thermal stress field developed in the cutting region is predicted using the finite element code. Temperature predictions are validated through the thermocouple data. The morphological changes in the cutting section are examined by incorporating optical and scanning electron microscopes. It is found that temperature predictions agree well with the thermocouple data. High values of von Mises stress are observed at the cutting edges and at the mid-thickness of the Kevlar laminate due to thermal compression formed in this region. The laser cut edges are free from whiskers; however, striation formation and some small sideways burning is observed at the kerf edges.

  5. Changes in laser-induced fluorescence responses of 3T3 fibroblasts to repetitive thermal stress

    Science.gov (United States)

    Beuthan, J.; Dressler, C.; Zabarylo, U.; Minet, O.

    2009-04-01

    The combined experimental use of laser-induced autofluorescence of cellular metabolites and methodological fundamentals of systems biology will provide access to biological thermal stress analysis on a sub cellular level. A test setup incorporating a pulsed nitrogen laser was realized with which autofluorescence of the coenzyme NADH could be measured in living 3T3 cells. The cells were subjected to different temperature stress at repetitive time intervals. When subjected to a simple mathematical analysis, the NADH concentration change measured through autofluorescence in biological cells exhibited approximate concentration-equivalent balance curves. These results add up to the fundamental know-how about the dosimetry of thermally therapeutic methods.

  6. Development of thermal stress concentration factors for life assessment of turbine casings

    International Nuclear Information System (INIS)

    The major components of thermal power plants are made of low-alloy steel and operated under high temperature and pressure conditions. Even though such facilities have design lives of 100,000 h, unexpected failure can occur due to thermal fatigue or creep damages during operation. In particular, high-pressure and intermediate-pressure casing components are susceptible to frequent cracking due to thermo-mechanical low-cycle fatigue at the nozzle fit corner radius and other stress concentration shapes. Thus, for effective maintenance, it is necessary to have accurate knowledge of transient thermal stresses at critical positions that are susceptible to failure. In this paper, thermal stress concentration factors for the inner surface of the casing and valve are defined to account for variations in the geometry using three-dimensional finite element analysis. In addition, the total strain range is obtained to assess the low-cycle fatigue life according to the life assessment procedures in Korea. Highlights: ► Analytical model of thermal stress concentration factors of casing was developed. ► TSCFs take into account variations in geometry through three-dimensional FEA. ► TSCFs from approximated equation correspondence with TSCFs from FEA. ► TSCFs from approximated equation is independent of disk length L.

  7. Transcriptional response of two core photosystem genes in Symbiodinium spp. exposed to thermal stress.

    Directory of Open Access Journals (Sweden)

    Michael P McGinley

    Full Text Available Mutualistic symbioses between scleractinian corals and endosymbiotic dinoflagellates (Symbiodinium spp. are the foundation of coral reef ecosystems. For many coral-algal symbioses, prolonged episodes of thermal stress damage the symbiont's photosynthetic capability, resulting in its expulsion from the host. Despite the link between photosynthetic competency and symbiont expulsion, little is known about the effect of thermal stress on the expression of photosystem genes in Symbiodinium. This study used real-time PCR to monitor the transcript abundance of two important photosynthetic reaction center genes, psbA (encoding the D1 protein of photosystem II and psaA (encoding the P(700 protein of photosystem I, in four cultured isolates (representing ITS2-types A13, A20, B1, and F2 and two in hospite Symbiodinium spp. within the coral Pocillopora spp. (ITS2-types C1b-c and D1. Both cultured and in hospite Symbiodinium samples were exposed to elevated temperatures (32°C over a 7-day period and examined for changes in photochemistry and transcript abundance. Symbiodinium A13 and C1b-c (both thermally sensitive demonstrated significant declines in both psbA and psaA during the thermal stress treatment, whereas the transcript levels of the other Symbiodinium types remained stable. The downregulation of both core photosystem genes could be the result of several different physiological mechanisms, but may ultimately limit repair rates of photosynthetic proteins, rendering some Symbiodinium spp. especially susceptible to thermal stress.

  8. An investigation on thermal residual stresses in a cylindrical functionally graded WC–Co component

    International Nuclear Information System (INIS)

    The thermal residual stress distribution in a functionally graded cemented tungsten carbide (FG WC–Co) hollow cylinder was examined with an emphasis on the effects of key variables, such as gradient profile and gradient thickness on the magnitude and distribution of the stress field. An analytical direct solution based on solving the governing equations of a cylinder composed of a uniform inner core and a functionally graded outer shell was developed, considering the cylindrical compound as two separate elements: a homogeneous cylinder and a functionally graded shell. Through the graded shell, material properties such as the modulus of elasticity and the coefficient of thermal expansion (CTE), except Poisson's ratio, were considered to vary as a power function of the radius, and proper mechanical boundary conditions were imposed at the interface of the two cylinders. Practical values for the two variables, gradient profile and gradient thickness, were evaluated in the mathematical solution for the FG WC–Co compound, and their effects on the stress distribution were studied. An examination of different gradient profiles showed that with excess Co content in the graded region, compressive radial stresses were created, while with decreasing Co content through the graded region tensile stresses were generated at the interface. The effect of gradient thickness was shown to have a greater effect on radial stress, compared to hoop stress, and increasing the gradient thickness significantly increased the radial stress magnitude.

  9. An investigation on thermal residual stresses in a cylindrical functionally graded WC-Co component

    Energy Technology Data Exchange (ETDEWEB)

    Tahvilian, L. [Metallurgical Engineering, University of Utah, 135 South 1460 East, Salt Lake City, UT 84112 (United States); Fang, Z. Zak, E-mail: zak.fang@utah.edu [Metallurgical Engineering, University of Utah, 135 South 1460 East, Salt Lake City, UT 84112 (United States)

    2012-11-15

    The thermal residual stress distribution in a functionally graded cemented tungsten carbide (FG WC-Co) hollow cylinder was examined with an emphasis on the effects of key variables, such as gradient profile and gradient thickness on the magnitude and distribution of the stress field. An analytical direct solution based on solving the governing equations of a cylinder composed of a uniform inner core and a functionally graded outer shell was developed, considering the cylindrical compound as two separate elements: a homogeneous cylinder and a functionally graded shell. Through the graded shell, material properties such as the modulus of elasticity and the coefficient of thermal expansion (CTE), except Poisson's ratio, were considered to vary as a power function of the radius, and proper mechanical boundary conditions were imposed at the interface of the two cylinders. Practical values for the two variables, gradient profile and gradient thickness, were evaluated in the mathematical solution for the FG WC-Co compound, and their effects on the stress distribution were studied. An examination of different gradient profiles showed that with excess Co content in the graded region, compressive radial stresses were created, while with decreasing Co content through the graded region tensile stresses were generated at the interface. The effect of gradient thickness was shown to have a greater effect on radial stress, compared to hoop stress, and increasing the gradient thickness significantly increased the radial stress magnitude.

  10. In Situ Measurement of Stress and Whisker/Hillock Density During Thermal Cycling of Sn Layers

    Science.gov (United States)

    Pei, Fei; Chason, Eric

    2014-01-01

    Compressive stress is believed to be the primary driving force that makes Sn whiskers/hillocks grow, but the mechanisms that create the stress (e.g., intermetallic compound growth) are difficult to control. As an alternative, the thermal expansion mismatch between the Sn layer and the substrate can be used to induce stress in a controlled way via heating and cooling. In this work, we describe real-time experiments which quantify the whiskering behavior and stress evolution during cyclic heating. The density of whiskers/hillocks is measured with an optical microscope, while the stress is measured simultaneously with a wafer-curvature-based multi-beam optical stress sensor. Results from three thermal cycles are described in which the samples are heated from room temperature to 65 °C at rates of 10, 30, and 240 °C/h. In each case, we find that the whisker/hillock formation is the primary source of stress relaxation. At fast heating rates, the relaxation is proportional to the number of hillocks, indicating that the stress is relaxed by the nucleation of many small surface features. At slower heating rates, the whisker/hillock density is lower, and continual growth of the features is suggested after nucleation. Long whiskers are found to be more likely to form in the slow heating cycle.

  11. Influence of temperature in thermal and oxidative stress responses in estuarine fish.

    Science.gov (United States)

    Madeira, D; Narciso, L; Cabral, H N; Vinagre, C; Diniz, M S

    2013-10-01

    The influence of increasing temperatures in thermal and oxidative stress responses were studied in the muscle of several estuarine fish species (Diplodus vulgaris, Diplodus sargus, Dicentrarchus labrax, Gobius niger and Liza ramada). Selected fish were collected in July at the Tagus estuary (24±0.9°C; salinity of 30±4‰; pH=8). Fish were subjected to a temperature increase of 1°C.h(-1) until they reached their Critical Thermal Maximum (CTMax), starting at 24°C (control temperature). Muscle samples were collected during the trial and results showed that oxidative stress biomarkers are highly sensitive to temperature. Results from stress oxidative enzymes show alterations with increasing temperature in all tested species. Catalase (CAT; EC 1.11.1.6) activity significantly increased in L. ramada, D. labrax and decreased in D. vulgaris. Glutathione S-transferase (GST; EC 2.5.1.18) activity increased in L. ramada, D. sargus, D. vulgaris, and D. labrax. In G. niger it showed a cycle of increase-decrease. Lipid peroxidation (LPO) increased in L. ramada, D. sargus and D. labrax. With respect to correlation analysis (Pearson; Spearman r), the results showed that oxidation products and antioxidant defenses were correlated in L. ramada (LPO-CAT and LPO-GST, D. sargus (LPO-CAT), and D. labrax (LPO-CAT). Oxidative biomarkers were correlated with thermal stress biomarker (Hsp70) in L. ramada (CAT-Hsp70), D. vulgaris (LPO-Hsp70), D. labrax (GST-Hsp70) and G. niger (LPO-Hsp70). In conclusion, oxidative stress does occur with increasing temperatures and there seems to be a relation between thermal stress response and oxidative stress response. The results suggest that oxidative stress biomarkers should be applied with caution, particularly in field multi-species/multi-environment studies. PMID:23774589

  12. Coping with Commitment: Projected Thermal Stress on Coral Reefs under Different Future Scenarios

    OpenAIRE

    Donner, Simon D.

    2009-01-01

    BACKGROUND: Periods of anomalously warm ocean temperatures can lead to mass coral bleaching. Past studies have concluded that anthropogenic climate change may rapidly increase the frequency of these thermal stress events, leading to declines in coral cover, shifts in the composition of corals and other reef-dwelling organisms, and stress on the human populations who depend on coral reef ecosystems for food, income and shoreline protection. The ability of greenhouse gas mitigation to alter the...

  13. Thermal Stress Analysis of Laminated Composite Plates using Shear Flexible Element

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1996-01-01

    Full Text Available Using degree Centigrade shear flexible QUAD-9 plate element, stresses and deflections in composite laminated plates due to thermal loads analysed. A formulation based on first order shear deformation theory has been employed for the analysis. The effects of various parameters, such as ply-angle, number of layers, thickness and aspect ratios on stresses and deflections are brought out. The present formulation is being extended for studying composite shell structures.

  14. Thermal Stress Analysis of Laminated Composite Plates using Shear Flexible Element

    OpenAIRE

    Ganapathi, M; Patel, B.P.; V. Balamurugan; D.R.S.V. Varma

    1996-01-01

    Using degree Centigrade shear flexible QUAD-9 plate element, stresses and deflections in composite laminated plates due to thermal loads analysed. A formulation based on first order shear deformation theory has been employed for the analysis. The effects of various parameters, such as ply-angle, number of layers, thickness and aspect ratios on stresses and deflections are brought out. The present formulation is being extended for studying composite shell structures.

  15. Rockfall triggering by cyclic thermal stressing of exfoliation fractures

    Science.gov (United States)

    Collins, Brian; Stock, Greg M.

    2016-01-01

    Exfoliation of rock deteriorates cliffs through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cliff in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are sufficient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the efficacy of other, more typical rockfall triggers.

  16. Rockfall triggering by cyclic thermal stressing of exfoliation fractures

    Science.gov (United States)

    Collins, Brian D.; Stock, Greg M.

    2016-05-01

    Exfoliation of rock deteriorates cliffs through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cliff in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are sufficient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the efficacy of other, more typical rockfall triggers.

  17. Coping with commitment: projected thermal stress on coral reefs under different future scenarios.

    Directory of Open Access Journals (Sweden)

    Simon D Donner

    Full Text Available BACKGROUND: Periods of anomalously warm ocean temperatures can lead to mass coral bleaching. Past studies have concluded that anthropogenic climate change may rapidly increase the frequency of these thermal stress events, leading to declines in coral cover, shifts in the composition of corals and other reef-dwelling organisms, and stress on the human populations who depend on coral reef ecosystems for food, income and shoreline protection. The ability of greenhouse gas mitigation to alter the near-term forecast for coral reefs is limited by the time lag between greenhouse gas emissions and the physical climate response. METHODOLOGY/PRINCIPAL FINDINGS: This study uses observed sea surface temperatures and the results of global climate model forced with five different future emissions scenarios to evaluate the "committed warming" for coral reefs worldwide. The results show that the physical warming commitment from current accumulation of greenhouse gases in the atmosphere could cause over half of the world's coral reefs to experience harmfully frequent (p> or =0.2 year(-1 thermal stress by 2080. An additional "societal" warming commitment, caused by the time required to shift from a business-as-usual emissions trajectory to a 550 ppm CO(2 stabilization trajectory, may cause over 80% of the world's coral reefs to experience harmfully frequent events by 2030. Thermal adaptation of 1.5 degrees C would delay the thermal stress forecast by 50-80 years. CONCLUSIONS/SIGNIFICANCE: The results suggest that adaptation -- via biological mechanisms, coral community shifts and/or management interventions -- could provide time to change the trajectory of greenhouse gas emissions and possibly avoid the recurrence of harmfully frequent events at the majority (97% of the world's coral reefs this century. Without any thermal adaptation, atmospheric CO(2 concentrations may need to be stabilized below current levels to avoid the degradation of coral reef ecosystems

  18. Redrawing Papez' circuit: a theory about how acute stress becomes chronic and causes disease.

    Science.gov (United States)

    Eggers, Arnold E

    2007-01-01

    The diseases of chronic stress include migraine, essential hypertension, depression, and the metabolic syndrome. A theory is presented to explain how acute stress becomes chronic and causes these inter-related conditions. The theory is based on a new "circuit of emotion", which is derived from Papez' famous theory of emotion. The hypothesis is as follows: There is a basic circuit of emotion which runs from the hippocampus (defined as the dentate gyrus plus the CA regions), where emotion arises, to the amygdala and from there to serotonergic pacemaker cells in the dorsal raphe nucleus (DRN). The DRN projects back to the dentate gyrus in two ways: a direct route without a stop and an indirect route via pacemaker cells in the entorhinal cortex. The purpose of the direct route is to promote neurogenesis in the subgranular zone of the dentate; the indirect route has two purposes: to imprint ongoing moments of consciousness onto new dentate cells for retention as memory and to provide a negative feedback loop for regulation of the whole process. The hippocampus, the amygdala, and the DRN all project to the hypothalamus, which are branches off the basic loop that subserve the autonomic expression of emotion. Pathologic overdrive of the DRN causes overdrive of the entorhinal cortex, which leads to excitotoxic cell death of neurons in the hippocampus involved in the negative feedback loop. The disinhibited amygdala and DRN are then free to orchestrate the syndromes of chronic stress. Recovery from chronic stress requires repopulation of the dentate gyrus and restoration of the feedback loop. Excitotoxic cell death in the hippocampus results from either extraordinary acute stress or increased susceptibility to DRN overdrive, as might be caused, for example, by genetic factors, age, high cortisol levels, or incomplete recovery from previous damage. Three goals for therapeutic intervention are identified: inhibition of pacemaker cells in the DRN (which can be targeted by

  19. Acute Exercise and Oxidative Stress: CrossFit™ vs. Treadmill Bout

    Directory of Open Access Journals (Sweden)

    Kliszczewicz Brian

    2015-09-01

    Full Text Available CrossFit™, a popular high-intensity training modality, has been the subject of scrutiny, with concerns of elevated risk of injury and health. Despite these concerns empirical evidence regarding physiologic stresses including acute oxidative stress is lacking. Therefore, the purpose of this investigation was to examine the acute redox response to a CrossFit™ bout. Furthermore, these findings were compared to a high-intensity treadmill bout as a point of reference. Ten males 26.4 ± 2.7 yrs having three or more months of CrossFit™ experience participated in the present study. Blood plasma was collected at four time points: Pre-exercise (PRE, immediately-post-exercise (IPE, 1 hr-post (1-HP and 2 hr-post (2-HP, to examine oxidative damage and antioxidant capacity. Regarding plasma oxidative damage, CrossFit™ and Treadmill elicited a time-dependent increase of lipid peroxides 1-HP (CrossFit™=+143%,Treadmill=+115% and 2-HP (CrossFit™=+256%,Treadmill+167%. Protein Carbonyls were increased IPE in CF only (+5%, while a time-dependent decrease occurred 1-HP (CrossFit™=−16%,Treadmill=−8% and 2-HP (CF=−16%,TM=−1% compared to IPE. Regarding antioxidant capacity, Ferric Reducing Antioxidant Power also demonstrated a time-dependent increase within CrossFit™ and Treadmill: IPE (CrossFit™=+25%,Treadmill=+17%, 1-HP (CrossFit™=+26%,Treadmill=+4.8%, 2-HP (CrossFit™=+20%,Treadmill=+12%. Total Enzymatic Antioxidant Capacity showed a time-dependent decrease in IPE (CrossFit™= −10%,Treadmill=−12%, 1-HP (CrossFit™= −12%,Treadmill=−6%, 2-HP (CrossFit™= −7%,Treadmill=−11%. No trial-dependent differences were observed in any biomarker of oxidative stress. The CrossFit™ bout elicited an acute blood oxidative stress response comparable to a traditional bout of high-intensity treadmill running. Results also confirm that exercise intensity and the time course of exercise recovery influence oxidative responses.

  20. Acute Exercise and Oxidative Stress: CrossFit(™) vs. Treadmill Bout.

    Science.gov (United States)

    Kliszczewicz, Brian; Quindry, C John; Blessing, L Daniel; Oliver, D Gretchen; Esco, R Michael; Taylor, J Kyle

    2015-09-29

    CrossFit(™), a popular high-intensity training modality, has been the subject of scrutiny, with concerns of elevated risk of injury and health. Despite these concerns empirical evidence regarding physiologic stresses including acute oxidative stress is lacking. Therefore, the purpose of this investigation was to examine the acute redox response to a CrossFit(™) bout. Furthermore, these findings were compared to a high-intensity treadmill bout as a point of reference. Ten males 26.4 ± 2.7 yrs having three or more months of CrossFit(™) experience participated in the present study. Blood plasma was collected at four time points: Pre-exercise (PRE), immediately-post-exercise (IPE), 1 hr-post (1-HP) and 2 hr-post (2-HP), to examine oxidative damage and antioxidant capacity. Regarding plasma oxidative damage, CrossFit(™) and Treadmill elicited a time-dependent increase of lipid peroxides 1-HP (CrossFit(™)=+143%, Treadmill=+115%) and 2-HP (CrossFit(™)=+256%, Treadmill+167%). Protein Carbonyls were increased IPE in CF only (+5%), while a time-dependent decrease occurred 1-HP (CrossFit(™)=-16%, Treadmill=-8%) and 2-HP (CF=-16%, TM=-1%) compared to IPE. Regarding antioxidant capacity, Ferric Reducing Antioxidant Power also demonstrated a time-dependent increase within CrossFit(™) and Treadmill: IPE (CrossFit(™)=+25%, Treadmill=+17%), 1-HP (CrossFit(™)=+26%, Treadmill=+4.8%), 2-HP (CrossFit(™)=+20%, Treadmill=+12%). Total Enzymatic Antioxidant Capacity showed a time-dependent decrease in IPE (CrossFit(™)=-10%, Treadmill=-12%), 1-HP (CrossFit(™)=-12%, Treadmill=-6%), 2-HP (CrossFit(™)=-7%, Treadmill=-11%). No trial-dependent differences were observed in any biomarker of oxidative stress. The CrossFit(™) bout elicited an acute blood oxidative stress response comparable to a traditional bout of high-intensity treadmill running. Results also confirm that exercise intensity and the time course of exercise recovery influence oxidative responses. PMID

  1. Acute Exercise and Oxidative Stress: CrossFit™ vs. Treadmill Bout

    Science.gov (United States)

    Kliszczewicz, Brian; Quindry, C. John; Blessing, L. Daniel; Oliver, D. Gretchen; Esco, R. Michael; Taylor, J. Kyle

    2015-01-01

    CrossFit™, a popular high-intensity training modality, has been the subject of scrutiny, with concerns of elevated risk of injury and health. Despite these concerns empirical evidence regarding physiologic stresses including acute oxidative stress is lacking. Therefore, the purpose of this investigation was to examine the acute redox response to a CrossFit™ bout. Furthermore, these findings were compared to a high-intensity treadmill bout as a point of reference. Ten males 26.4 ± 2.7 yrs having three or more months of CrossFit™ experience participated in the present study. Blood plasma was collected at four time points: Pre-exercise (PRE), immediately-post-exercise (IPE), 1 hr-post (1-HP) and 2 hr-post (2-HP), to examine oxidative damage and antioxidant capacity. Regarding plasma oxidative damage, CrossFit™ and Treadmill elicited a time-dependent increase of lipid peroxides 1-HP (CrossFit™=+143%, Treadmill=+115%) and 2-HP (CrossFit™=+256%, Treadmill+167%). Protein Carbonyls were increased IPE in CF only (+5%), while a time-dependent decrease occurred 1-HP (CrossFit™=−16%, Treadmill=−8%) and 2-HP (CF=−16%, TM=−1%) compared to IPE. Regarding antioxidant capacity, Ferric Reducing Antioxidant Power also demonstrated a time-dependent increase within CrossFit™ and Treadmill: IPE (CrossFit™=+25%, Treadmill=+17%), 1-HP (CrossFit™=+26%, Treadmill=+4.8%), 2-HP (CrossFit™=+20%, Treadmill=+12%). Total Enzymatic Antioxidant Capacity showed a time-dependent decrease in IPE (CrossFit™=−10%, Treadmill=−12%), 1-HP (CrossFit™=−12%, Treadmill=−6%), 2-HP (CrossFit™=−7%, Treadmill=−11%). No trial-dependent differences were observed in any biomarker of oxidative stress. The CrossFit™ bout elicited an acute blood oxidative stress response comparable to a traditional bout of high-intensity treadmill running. Results also confirm that exercise intensity and the time course of exercise recovery influence oxidative responses. PMID:26557192

  2. The thermal and magnetic stress analyses of the ATLAS Barrel Toroid- B0 coil

    CERN Document Server

    Sun, Z; Daël, A; Mayri, C; Pes, C; Reytier, M

    2002-01-01

    The B0 coil is a test-model of the ATLAS Barrel Toroid (BT) coils. It has been installed in the test station at CERN. One important item of the B0 test is the strain/stress measurements. In order to determine the expected stress values at the strain gage locations on the coil casing and the tie rods, detailed thermal and magnetic stress analyses of the B0 coil have been carried out. The analysis results are prepared for a later one-to-one comparison with the measurement results. (6 refs).

  3. Thermal Stress-Induced Birefringence in Borate Glass Irradiated by Femtosecond Laser Pulses

    Institute of Scientific and Technical Information of China (English)

    DAI Ye; YU Bing-Kun; LU Bo; QIU Jian-Rong; YAN Xiao-Na; JIANG Xiong-Wei; ZHU Cong-Shan

    2005-01-01

    @@ Thermal stress-induced birefringence in borate glass which has been irradiated by 800-nm femtosecond laser pulses is observed under cross-polarized light. Due to the high temperature and pressure formed in the focal volume, the material at the edge of the micro-modified region is compressed between the expanding region and the unheated one, then stress emerges. Raman spectroscopy is used to investigate the stress distribution in the micro-modified region and indicates the redistributions of density and refractive index by Raman peak shift. We suggest that this technique can develop waveguide polarizers and Fresnel zone plates in integrated optics.

  4. Analyses of thermal stress and fracture during cryopreservation of blood vessel

    Institute of Scientific and Technical Information of China (English)

    华泽钊; 徐红艳; 周国燕; 刘锦纷; 黄惠民; 丁文祥

    2001-01-01

    The occurrence of fractures in the vessel wall has been a major problem for human blood vessel cryopreservation. The large volumetric expansion of water during crystallization produces great inner stresses. To solve these complicated heat transfer and thermal stress problems, a model and an analytic method are presented in this paper, with which transient temperature field, the transient stress field inside the blood vessels during freezing can be calculated and analyzed, and the probable cracks or fractures can be predicted. The analytic results of sheep thoracic artery are consistent with the experimental observations of fractures.

  5. Hepatoprotective effect of carob against acute ethanol-induced oxidative stress in rat.

    Science.gov (United States)

    Souli, Abdelaziz; Sebai, Hichem; Chehimi, Latifa; Rtibi, Kaïs; Tounsi, Haifa; Boubaker, Samir; Sakly, Mohsen; El-Benna, Jamel; Amri, Mohamed

    2015-09-01

    The present study was undertaken to determine whether subacute treatment with aqueous extract of carob (Ceratonia siliqua L.) pods (AECPs) protects against ethanol (EtOH)-induced oxidative stress in rat liver. Animals were divided into four groups: control, carob, EtOH and EtOH + carob. Wistar rats were intraperitoneally pretreated with AECP (600 mg/kg body weight (bw)) during 7 days and intoxicated for 6 h by acute oral administration of EtOH (6 g/kg bw) 24 h after the last injection. We found that acute administration of EtOH leads to hepatotoxicity as monitored by the increase in the levels of hepatic marker aspartate aminotransferase and alanine aminotransferase as well as hepatic tissue injury. EtOH also increased the formation of malondialdehyde in the liver, indicating an increase in lipid peroxidation and depletion of antioxidant enzyme activities as superoxide dismutase, catalase and glutathione peroxidase. Subacute carob pretreatment prevented all the alterations induced by EtOH and returned their levels to near normal. Importantly, we showed that acute alcohol increased hepatic and plasmatic hydrogen peroxide and free iron levels. The carob pretreatment reversed EtOH effects to near control levels. These data suggest that carob could have a beneficial effect in inhibiting the oxidative damage induced by acute EtOH administration and that its mode of action may involve an opposite effect on plasma and tissue-free iron accumulation. Indeed, carob can be offered as a food additive to protect against EtOH-induced oxidative damage.

  6. Stress determination in thermally grown alumina scales using ruby luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Renusch, D.; Veal, B.W.; Koshelev, I.; Natesan, K.; Grimsditch [Argonne National Lab., IL (United States); Hou, P.Y. [Lawrence Berkeley Lab., CA (United States)

    1996-06-01

    By exploiting the strain dependence of the ruby luminescence line, we have measured the strain in alumina scales thermally grown on Fe-Cr- Al alloys. Results are compared and found to be reasonably consistent with strains determined using x rays. Oxidation studies were carried out on alloys Fe - 5Cr - 28Al and Fe - 18Cr - 10Al (at.%). Significantly different levels of strain buildup were observed in scales on these alloys. Results on similar alloys containing a ``reactive element`` (Zr or Hf) in dilute quantity are also presented. Scales on alloys containing a reactive element (RE) can support significantly higher strains than scales on RE-free alloys. With the luminescence technique, strain relief associated with spallation thresholds is readily observed.

  7. Effect of Residual Stress on the Wear Resistance of Thermal Spray Coatings

    Science.gov (United States)

    Luo, W.; Selvadurai, U.; Tillmann, W.

    2016-01-01

    The wear resistance of thermal spray coatings mainly depends on coating properties such as the microstructure, hardness, and porosity, as well as on the residual stress in the coating. The residual stress is induced by a variety of influences e.g., temperature gradients, difference of the thermal expansion coefficient of the coating/substrate materials, and the geometry of the components. To investigate the residual stress, the impulse excitation technique was employed to measure the Young's and shear moduli. The residual stress was determined by the hole-drilling method and x-ray diffraction. Pin-on-Disk and Pin-on-Tube tests were used to investigate the wear behavior. After the wear tests, the wear volume was measured by means of a 3D-profilometer. The results show that the value of the residual stress can be modified by varying the coating thickness and the substrate geometry. The compressive stress in the HVOF-sprayed WC-Co coatings has a significant positive influence on the wear resistance whereas the tensile stress has a negative effect.

  8. Contrasting patterns of coral bleaching susceptibility in 2010 suggest an adaptive response to thermal stress.

    Directory of Open Access Journals (Sweden)

    James R Guest

    Full Text Available BACKGROUND: Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. METHODOLOGY/PRINCIPAL FINDINGS: Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; p<0.001. Bleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. CONCLUSIONS/SIGNIFICANCE: The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments.

  9. Modeling and simulation of 3D thermal stresses of large-sized castings in solidification processes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large- sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings.Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.

  10. Thermal stress analysis method considering geometric effect of risers in sand mold casting process

    Institute of Scientific and Technical Information of China (English)

    S Y Kwak; HY Hwang; C Cho

    2014-01-01

    Solidification and fluid flow analysis using computer simulation is a current common practice. There is also a high demand for thermal stress analysis in the casting process because casting engineers want to control the defects related to thermal stresses, such as large deformation and crack generation during casting. The riser system is an essential part of preventing the shrinkage defects in the casting process, and it has a great influence on thermal phenomena. The analysis domain is dramatical y expanded by attaching the riser system to a casting product due to its large volume, and it makes FEM mesh generation difficult. However, it is difficult to study and solve the above proposed problem caused by riser system using traditional analysis methods which use single numerical method such as FEM or FDM. In this paper, some research information is presented on the effects of the riser system on thermal stress analysis using a FDM/FEM hybrid method in the casting process simulation. The results show the optimal conditions for stress analysis of the riser model in order to save computation time and memory resources.

  11. Examining rapid onset drought development using the thermal infrared based evaporative stress index

    Science.gov (United States)

    Reliable indicators of rapid drought onset are necessary to improve the utility of drought early warning systems. In this study, the Evaporative Stress Index (ESI), which uses remotely-sensed thermal infrared imagery to estimate evapotranspiration (ET), is compared to meteorological data and United...

  12. Influence of thermal residual stresses on the elastic phase-strain

    Energy Technology Data Exchange (ETDEWEB)

    Shi, N.; Bourke, M.A.M.; Goldstone, J.A. [and others

    1996-04-01

    The development of elastic lattice phase strains in a 15 vol. pct TiC particulate reinforced 2219-T6 Al composite was modeled as a function of tensile uniaxial loading by finite element method (FEM). In the relationship of applied stress vs. elastic lattice phase strain, the slopes vary with the applied load even before the macroscopic yielding. The slopes for the phase-strain perpendicular to loading follow nonmonotonic changes with loading, while, in the direction parallel to loading, the slopes change monotonically with the applied load. In this investigation, we have demonstrated via FEM that thermal residual stresses from thermal expansion mismatch between phases affect initiation of matrix plasticity. And the differences in the matrix plasticity initiation influence the internal stress distribution. The changes in the slope are dictated by the internal stress transfer between phases. FEM models with and without thermal history show significant differences in the response of elastic strain component, a mechanics equivalent of the lattice elastic strain. Agreement with experiment can only be obtained by including the thermal history. From a simple elasto-plastic spring model we are able to demonstrate that, with matrix plasticity propagating as predicted by FEM, the elastic strain component responds similarly to the more rigorous numerical predictions, suggesting that the morphology of elastic strain evolution is dictated by the development of matrix plasticity.

  13. Estimating maize water stress by standard deviation of canopy temperature in thermal imagery

    Science.gov (United States)

    A new crop water stress index using standard deviation of canopy temperature as an input was developed to monitor crop water status. In this study, thermal imagery was taken from maize under various levels of deficit irrigation treatments in different crop growing stages. The Expectation-Maximizatio...

  14. Gene expression under thermal stress varies across a geographical range expansion front.

    Science.gov (United States)

    Lancaster, Lesley T; Dudaniec, Rachael Y; Chauhan, Pallavi; Wellenreuther, Maren; Svensson, Erik I; Hansson, Bengt

    2016-03-01

    Many ectothermic species are currently expanding their distributions polewards due to anthropogenic global warming. Molecular genetic mechanisms facilitating range expansion under these conditions are largely unknown, but understanding these could help mitigate expanding pests and disease vectors, or help explain why some species fail to track changing climates. Here, using RNA-seq data, we examine genomewide changes in gene expression under heat and cold stress in the range-expanding damselfly Ischnura elegans in northern Europe. We find that both the number of genes involved and levels of gene expression under heat stress have become attenuated during the expansion, consistent with a previously reported release from selection on heat tolerances as species move polewards. Genes upregulated under cold stress differed between core and edge populations, corroborating previously reported rapid adaptation to cooler climates at the expansion front. Expression of sixty-nine genes exhibited a region x treatment effect; these were primarily upregulated in response to heat stress in core populations but in response to cold stress at the range edge, suggesting that some cellular responses originally adapted to heat stress may switch to cold-stress functionality upon encountering novel thermal selection regimes during range expansion. Transcriptional responses to thermal stress involving heat-shock and neural function genes were largely geographically conserved, while retrotransposon, regulatory, muscle function and defence gene expression patterns were more variable. Flexible mechanisms of cold-stress response and the ability of some genes to shift their function between heat and cold stress might be key mechanisms facilitating rapid poleward expansion in insects. PMID:26821170

  15. Microstructural studies and residual stress evolution in zirconia-based thermal barrier coatings

    International Nuclear Information System (INIS)

    Thick thermal barrier coatings consisting of NiCrAlY bond coating and a 1.4 mm thick Zirconia-based top coating were air plasma sprayed onto grit blasted nickel-base substrates, Hastelloy X. Different amounts of external cooling were utilized during the spraying of the top coatings, which resulted in different specimen temperature histories. A finite element model was developed to simulate the heat flux from the spraying process and the resulting thermal stresses in the specimen. The modelled stresses after the spraying of the bond coating and the top coating were compared to measured residual stresses. The measurements were performed with a layer removal technique, allowing the residual stresses to be determined as a function of depth in the specimen. Further, the microstructure of the top coatings was studied by electron microscopy techniques. In the bond coating, high tensile stresses were predicted. These stresses remained after the spraying of the top coating, where low compressive stresses were predicted as a result from stress relaxation by microcracking. Good agreement between modelled and measured residual stress was found, except from a measured compressive zone in the substrate. The compressive stresses were found to have originated during the grit blasting process, which was not incorporated in the model. The top coating microstructure contained high densities of vertical microcracks and horizontal delaminations. Both defect densities decreased when the substrate temperature during spraying was high. A correlation between modelled inelastic strain in the top coating and point counted densities of vertical microcracks was obtained. 33 refs, 8 figs,

  16. Clinical evaluation of oxidative stress in patients with diabetes mellitus type II: Impact of acute exercise

    Directory of Open Access Journals (Sweden)

    Kostić Nada

    2009-01-01

    Full Text Available Background/Aim. Exercise is a well recognized model of oxidative stress and, also, an important tool in diabetes management. The aim of our study was to evaluate oxidative stress in patients with diabetes mellitus type 2 and to determine influence of acute exercise training on the investigated parameters. Methods. To evaluate oxidative stress in the patients, we determinated following parameters: triglycerides (TG, total cholesterol, low density lipoprotein cholesterol (LDL, oxidized LDL cholesterol (Ox LDL, superoxide dismutase (SOD, glutathione peroxidase (GSHPx, plasminogen activator inhibitor (PAI which were measured at rest and immediately after the acute bout of cardiopulmonary exercise cycle-ergometer test. Results. In basal condition, diabetic patients compared to controls have significant higher values of TG (3.12 ± 1.09 vs 1.74 ± 0.9 mmol/L, p < 0.01, Ox LDL (84.73 ± 16.90 vs 79.00 ± 29.26 mmol/L, p < 0.05 and SOD enzyme activity (913.38 ± 120.36 vs 877.14 ± 153.18 U/g Hb, p < 0.05. During the acute exercise test, there was significant increase of Ox LDL in both the study patients (from 84.73 ± 16.90 to 92.33 ± 23.29 mmol/L, p < 0.05 and in the control group (from 79.00 ± 29.26 to 89.30 ± 29.07 mmol/L, p < 0.05. SOD activity was significantly increased in both groups during exercise, in diabetic patients from 913.38 ± 120.36 to 921.50 ± 130.03 U/gHb, p < 0.05, and in the controls from 877.14 ± 153.18 to 895.00 ± 193.49, U/gHb, p < 0.05. GSH-Px activity was significantly increased only in the diabetic patients after the acute exercise (from 45.04 ± 11.19 to 51.81 ± 15.07 U/gHb, p < 0.01, but not in the controls (from 44.63 ± 13.73 to 43.97 ± 25.97 U/gHb, p = ns. PAI significantly decreased during the exercise test, only in the healthy subjects (from 2.60 ± 0.35 to 2.22 ± 0.65, p < 0.05. Type 2 diabetic patients with complications had only significant increase in GSH-Px activity (from 47.10 ± 7.37 to 54.52 ± 11.97 U

  17. Acute effects of traditional Thai massage on cortisol levels, arterial blood pressure and stress perception in academic stress condition: A single blind randomised controlled trial.

    Science.gov (United States)

    Bennett, Surussawadi; Bennett, Michael John; Chatchawan, Uraiwon; Jenjaiwit, Patcharaporn; Pantumethakul, Rungthip; Kunhasura, Soontorn; Eungpinichpong, Wichai

    2016-04-01

    Traditional Thai massage (TTM) has been applied widely to promote relaxation. However, there is little evidence to support its efficacy on academic stress. A randomised controlled trial was performed to examine the acute effects of TTM on cortisol level, blood pressure, heart rate and stress perception in academic stress. This prospective trial included 36 physiotherapy students with a self perceived stress score of between 3 and 5. They were randomly allocated into the TTM (18 people) group or the control group (18 people). Saliva cortisol level, blood pressure, heart rate and stress perception rating were measured before and after the intervention. Both groups showed a significant reduction in cortisol level and heart rate when compared with baseline (p stress of TTM.

  18. Effects study on the thermal stresses in a LEU metal foil annular target

    International Nuclear Information System (INIS)

    The effects of fission gas pressure, uranium swelling and thermal contact conductance on the thermal–mechanical behavior of an annular target containing a low-enriched uranium foil (LEU) encapsulated in a nickel foil have been presented in this paper. The draw-plug assembly method is simulated to obtain the residual stresses, which are applied to the irradiation model as initial inputs, and the integrated assembly-irradiation process is simulated as an axisymmetric problem using the commercial finite element code Abaqus FEA. Parametric studies were performed on the LEU heat generation rate and the results indicate satisfactory irradiation performance of the annular target. The temperature and stress margins have been provided along with a discussion of the results. - Highlights: • Analyzed the thermal stresses in a low-enriched uranium foil based annular target. • Included fission gas, uranium swelling, and thermal contact conductance effects. • Worst case scenarios for temperature and stresses were found to be different. • Sensitivity studies on the foil heat generation rates were performed. • Temperature and stress were found to be within acceptable limits

  19. Evaluation of Transverse Thermal Stresses in Composite Plates Based on First-Order Shear Deformation Theory

    Science.gov (United States)

    Rolfes, R.; Noor, A. K.; Sparr, H.

    1998-01-01

    A postprocessing procedure is presented for the evaluation of the transverse thermal stresses in laminated plates. The analytical formulation is based on the first-order shear deformation theory and the plate is discretized by using a single-field displacement finite element model. The procedure is based on neglecting the derivatives of the in-plane forces and the twisting moments, as well as the mixed derivatives of the bending moments, with respect to the in-plane coordinates. The calculated transverse shear stiffnesses reflect the actual stacking sequence of the composite plate. The distributions of the transverse stresses through-the-thickness are evaluated by using only the transverse shear forces and the thermal effects resulting from the finite element analysis. The procedure is implemented into a postprocessing routine which can be easily incorporated into existing commercial finite element codes. Numerical results are presented for four- and ten-layer cross-ply laminates subjected to mechanical and thermal loads.

  20. Radiation-induced rf loss measurements and thermal-stress calculations for ceramic windows

    International Nuclear Information System (INIS)

    Irradiation with high energy neutrons can cause increases in loss tangent and thermal resistivity for some ceramics. Loss tangents over the range 0.02 to several MHz have been measured for single and polycrystalline aluminum oxide and polycrystalline beryllium oxide, after irradiation with a spallation neutron source. Some samples of single crystal aluminum oxide were also irradiated with 14-MeV neutrons at RTNS-II to compare spectral effects. Significant increases in loss tangent were observed at the higher frequencies for the RTNS-II irradiated material. Numerical calculations of thermal stresses in rf windows, based on heating from dielectric losses and thermal conductivities, show that stresses can exceed measured fracture strengths in these materials

  1. On the Use of Constitutive Internal Variable Equations for Thermal Stress Predictions in Aluminium Casting

    Directory of Open Access Journals (Sweden)

    Asbjørn Mo

    1993-01-01

    Full Text Available The report discusses the use of constitutive equations with internal variables in mathematical calculations of the thermally induced strains and stresses that arise during casting of aluminium. Application of the so-called MATMOD (MATerials MODel constitutive relations for the viscoplastic deformation of the material is first discussed in relation to the specific characteristics of the casting process. Some numerical time integrations of the one-dimensional version of the MATMOD equations that are relevant for aluminium casting are then presented. The evolution of temperature and total strain are here chosen to be close to values experienced in the direct chill (D.C. casting process, and values for thermally induced strains and stresses are calculated. The results are compared with predictions based on the traditional approach, in which a set of representative stress-strain curves at different constant temperatures and strain rates constitute the complete description of the viscoplastic deformation.

  2. Mucus sugar content shapes the bacterial community structure in thermally stressed Acropora muricata

    Directory of Open Access Journals (Sweden)

    Sonny T.M. Lee

    2016-03-01

    Full Text Available It has been proposed that the chemical composition of a coral’s mucus can influence the associated bacterial community. However, information on this topic is rare, and non-existent for corals that are under thermal stress. This study therefore compared the carbohydrate composition of mucus in the coral Acropora muricata when subjected to increasing thermal stress from 26°C to 31°C, and determined whether this composition correlated with any changes in the bacterial community. Results showed that, at lower temperatures, the main components of mucus were N-acetyl glucosamine and C6 sugars, but these constituted a significantly lower proportion of the mucus in thermally-stressed corals. The change in the mucus composition coincided with a shift from a γ-Proteobacteria- to a Verrucomicrobiae- and α-Proteobacteria-dominated community in the coral mucus. Bacteria in the class Cyanobacteria also started to become prominent in the mucus when the coral was thermally stressed. The increase in the relative abundance of the Verrucomicrobiae at higher temperature was strongly associated with a change in the proportion of fucose, glucose and mannose in the mucus. Increase in the relative abundance of α-Proteobacteria were associated with GalNAc and glucose, while the drop in relative abundance of γ-Proteobacteria at high temperature coincided with changes in fucose and mannose. Cyanobacteria were highly associated with arabinose and xylose. Changes in mucus composition and the bacterial community in the mucus layer occurred at 29°C, which were prior to visual signs of coral bleaching at 31°C. A compositional change in the coral mucus, induced by thermal stress could therefore be a key factor leading to a shift in the associated bacterial community. This, in turn, has the potential to impact the physiological function of the coral holobiont.

  3. Mucus Sugar Content Shapes the Bacterial Community Structure in Thermally Stressed Acropora muricata.

    Science.gov (United States)

    Lee, Sonny T M; Davy, Simon K; Tang, Sen-Lin; Kench, Paul S

    2016-01-01

    It has been proposed that the chemical composition of a coral's mucus can influence the associated bacterial community. However, information on this topic is rare, and non-existent for corals that are under thermal stress. This study therefore compared the carbohydrate composition of mucus in the coral Acropora muricata when subjected to increasing thermal stress from 26 to 31°C, and determined whether this composition correlated with any changes in the bacterial community. Results showed that, at lower temperatures, the main components of mucus were N-acetyl glucosamine and C6 sugars, but these constituted a significantly lower proportion of the mucus in thermally stressed corals. The change in the mucus composition coincided with a shift from a γ-Proteobacteria- to a Verrucomicrobiae- and α-Proteobacteria-dominated community in the coral mucus. Bacteria in the class Cyanobacteria also started to become prominent in the mucus when the coral was thermally stressed. The increase in the relative abundance of the Verrucomicrobiae at higher temperature was strongly associated with a change in the proportion of fucose, glucose, and mannose in the mucus. Increase in the relative abundance of α-Proteobacteria were associated with GalNAc and glucose, while the drop in relative abundance of γ-Proteobacteria at high temperature coincided with changes in fucose and mannose. Cyanobacteria were highly associated with arabinose and xylose. Changes in mucus composition and the bacterial community in the mucus layer occurred at 29°C, which were prior to visual signs of coral bleaching at 31°C. A compositional change in the coral mucus, induced by thermal stress could therefore be a key factor leading to a shift in the associated bacterial community. This, in turn, has the potential to impact the physiological function of the coral holobiont. PMID:27047481

  4. "Stress" hyperglycaemia during acute myocardial infarction: an indicator of pre-existing diabetes?

    Science.gov (United States)

    Husband, D J; Alberti, K G; Julian, D G

    1983-07-23

    Hyperglycaemia occurring at admission in patients with suspected acute myocardial infarction is generally held to represent stress hyperglycaemia. 26 patients, not previously known to be diabetic, had blood glucose values greater than or equal to 10 mmol/l on admission to a coronary care unit. 16 survived for 2 months at which time a 75 g oral glucose tolerance test (OGTT) showed diabetes in 10 (63%) and impaired glucose tolerance in 1 (WHO criteria). All those with abnormal glucose tolerance at 2 months had had raised glycosylated haemoglobin (HbA1) (greater than 7.5%) on admission, indicating pre-existing diabetes. All those with a HbA1 level over 8% had abnormal glucose tolerance. 7 of the 10 who died or did not have an OGTT also had raised HbA1 at admission. An admission blood glucose greater than or equal to 10 mmol/l in patients with severe chest pain is more likely to indicate previously undiagnosed diabetes than "stress" hyperglycaemia. There is no evidence that myocardial infarction precipitates diabetes. The glycosylated haemoglobin concentration can be used to distinguish between stress hyperglycaemia and hyperglycaemia caused by diabetes.

  5. Acute and chronic stress-induced disturbances of microglial plasticity, phenotype and function.

    Science.gov (United States)

    Walker, Frederick Rohan; Nilsson, Michael; Jones, Kimberley

    2013-10-01

    Traditionally, microglia have been considered to act as macrophages of the central nervous system. While this concept still remains true it is also becoming increasingly apparent that microglia are involved in a host of nonimmunological activities, such as monitoring synaptic function and maintaining synaptic integrity. It has also become apparent that microglia are exquisitely sensitive to perturbation by environmental challenges. The aim of the current review is to critically examine the now substantial literature that has developed around the ability of acute, sub-chronic and chronic stressors to alter microglial structure and function. The vast majority of studies have demonstrated that stress promotes significant structural remodelling of microglia, and can enhance the release of pro-inflammatory cytokines from microglia. Mechanistically, many of these effects appear to be driven by traditional stress-linked signalling molecules, namely corticosterone and norepinephrine. The specific effects of these signalling molecules are, however, complex as they can exert both inhibitory and suppressive effects on microglia depending upon the duration and intensity of exposure. Importantly, research has now shown that these stress-induced microglial alterations, rather than being epiphenomena, have broader behavioural implications, with the available evidence implicating microglia in directly regulating certain aspects of cognitive function and emotional regulation. PMID:24020974

  6. Pressor recovery after acute stress is impaired in high fructose-fed Lean Zucker rats.

    Science.gov (United States)

    Thompson, Jennifer A; D'Angelo, Gerard; Mintz, James D; Fulton, David J; Stepp, David W

    2016-06-01

    Insulin resistance is a powerful predictor of cardiovascular disease; however, the mechanistic link remains unclear. This study aims to determine if early cardiovascular changes associated with short-term fructose feeding in the absence of obesity manifest as abnormal blood pressure control. Metabolic dysfunction was induced in Lean Zucker rats by short-term high-fructose feeding. Rats were implanted with telemetry devices for the measurement of mean arterial blood pressure (MAP) and subjected to air jet stress at 5 and 8 weeks after feeding. Additional animals were catheterized under anesthesia for the determination of MAP and blood flow responses in the hind limb and mesenteric vascular beds to intravenous injection of isoproterenol (0.001-0.5 μm), a β-adrenergic agonist. Metabolic dysfunction in high-fructose rats was not accompanied by changes in 24-h MAP Yet, animals fed a high-fructose diet for 8 weeks exhibited a marked impairment in blood pressure recovery after air-jet stress. Dose-dependent decreases in MAP and peripheral blood flow in response to isoproterenol treatment were significantly attenuated in high-fructose rats. These data suggest that impaired blood pressure recovery to acute mental stress precedes the onset of hypertension in the early stages of insulin resistance. Further, blunted responses to isoproterenol implicate β2-adrenergic sensitivity as a possible mechanism responsible for altered blood pressure control after short-term high-fructose feeding. PMID:27335430

  7. Thermal vibration of a single-layered graphene with initial stress predicted by semiquantum molecular dynamics

    Science.gov (United States)

    Liu, Rumeng; Wang, Lifeng; Jiang, Jingnong

    2016-09-01

    Thermal vibration of a rectangular single-layered graphene sheet (RSLGS) with initial stress is investigated by a semiquantum molecular dynamics (SQMD) method on the basis of modified Langevin dynamics. The quantum effect in the thermal vibration of RSLGS is accounted by introducing a quantum thermal bath. The spectrum of the thermal vibration of RSLGSs is obtained both by SQMD and classical molecular dynamics (CMD). The RSLGS vibrates with the same frequencies via both the SQMD simulation and the CMD simulation. The root of mean squared (rms) amplitude obtained via the CMD is greater than that obtained via the SQMD. The energy in high order mode is frozen at very low temperature if quantum effect is taken into consideration. An elastic plate model with initial stress considering quantum effects is established to describe the thermal vibration of the RSLGS. The rms amplitude of RSLGS calculated by plate model with the law of energy equipartition and that obtained from the CMD coincide very well. The plate model considering the quantum effects provides accurate prediction of the rms amplitude of the RSLGS obtained from the SQMD. These results indicate that quantum effects cannot be neglected in the thermal vibration of the RSLGS at low temperature case.

  8. Effect of Shouldering Angle on Distribution of Thermal Stress in Sapphire Single Crystal Growth Using Improved Kyropoulos

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A two-dimensional model was established in the rectangular co-ordinate to study the thermal stress in the sapphire single crystal grown by the improved Kyropoulos. In the simulation, the distribution, the maximum and minimum values of the thermal stress were calculated. In addition, the relationship between the thermal stress and the shouldering angles was obtained that for lower shouldering angles, the maximum of the thermal stress value is lower and the minimum value is higher. It indicates that the distribution of the thermal stress can be improved by decreasing the shouldering angles of the crystal during the growth process. To evaluate the model, the experiment was carried out and the results are in good agreement with the calculation.

  9. Thermal-hydraulic performance and structural thermal stress analysis for ITER shield blanket module nearby NB rejoin

    International Nuclear Information System (INIS)

    Hydraulic and thermal analysis of the International Thermonuclear Experimental Reactor (ITER) standard neutral beam (NB) blanket module was carried out in order to check whether the latest design meets ITER requirements. Minor-loss coefficients were estimated with a CFD code, and friction factors of straight channels were obtained using existing formulas. The effects of different radial hole's diameter, length of the back of the radial hole, size of clearance, type of flow driver, branch velocity and flow direction on minor-loss coefficients for radial holes were investigated. Since total mass flow rate and dimensions of the cooling channels were given, when pressure drop due to intersection of the radial hole with back drilled collector was ignored, we can obtain pressure drop, flow rate, velocity and heat transfer coefficient in each radial hole. An improved calculation without neglecting the pressure drop caused by the intersection was also done to compare with the simplified one. Finally, maximum temperature, thermal stress and deformation were evaluated according to FEM thermal analysis. The results of the latest hydraulic and thermal analysis indicate that the current design meets ITER requirements well, except that flow distribution is not so uniform when different types of flow drivers are used, and temperature in the front head surface is a little high. Improved design is necessary in the further. (authors)

  10. Artificial light at night alters delayed-type hypersensitivity reaction in response to acute stress in Siberian hamsters.

    Science.gov (United States)

    Bedrosian, Tracy A; Aubrecht, Taryn G; Kaugars, Katherine E; Weil, Zachary M; Nelson, Randy J

    2013-11-01

    Several physiological and behavioral processes rely on precisely timed light information derived from the natural solar cycle. Using this information, traits have adapted to allow individuals within specific niches to optimize survival and reproduction, but urbanization by humans has significantly altered natural habitats. Nighttime light exposure alters immune function in several species, which could lead to decreased fitness or survival, particularly in the face of an environmental challenge. We exposed male Siberian hamsters (Phodopus sungorus) to five lux of light at night for four weeks, and then administered six hours of acute restraint stress. Delayed-type hypersensitivity (DTH) response was assessed immediately following stress. Acute restraint increased the DTH reaction in dark nights, but exposure to nighttime light prevented this response. Exposure to light at night prolonged the DTH response in non-stressed control hamsters. These results suggest that light pollution may significantly alter physiological responses in Siberian hamsters, particularly in response to a salient environmental challenge such as stress.

  11. Optimization design and residual thermal stress analysis of PDC functionally graded materials

    Institute of Scientific and Technical Information of China (English)

    CAO Pin-lu; LIU Bao-chang; YIN Kun; ZHANG Zu-pei

    2006-01-01

    The distribution of thermal stresses in functionally graded polycrystalline diamond compact (PDC) and in single coating of PDC are analyzed respectively by thermo-mechanical finite element analysis (FEA). It is shown that they each have a remarkable stress concentration at the edge of the interfaces. The diamond coatings usually suffer premature failure because of spallation, distortion or defects such as cracks near the interface due to these excessive residual stresses. Results showed that the axial tensile stress in FGM coating is reduced from 840 MPa to 229 MPa compared with single coating, and that the shear stress is reduced from 671 MPa to 471 MPa. Therefore, the single coating is more prone to spallation and cracking than the FGM coating.The effects of the volume compositional distribution factor (n) and the number of the graded layers (L) on the thermal stresses in FGM coating are also discussed respectively. Modelling results showed that the optimum value of the compositional distribution factor is 1.2, and that the best number of the graded layers is 6.

  12. Finite element analysis of the residual thermal stresses on functionally gradated dental restorations.

    Science.gov (United States)

    Henriques, B; Miranda, G; Gasik, M; Souza, J C M; Nascimento, R M; Silva, F S

    2015-10-01

    The aim of this work was to study, using the finite element method (FEM), the distribution of thermal residual stresses arising in metal-ceramic dental restorations after cooling from the processing temperature. Three different interface configurations were studied: with conventional sharp transition; one with a 50% metal-50% ceramic interlayer; and one with a compositionally functionally gradated material (FGM) interlayer. The FE analysis was performed based on experimental data obtained from Dynamic Mechanical Analysis (DMA) and Dilatometry (DIL) studies of the monolithic materials and metal/ceramic composites. Results have shown significant benefits of using the 50% metal-50% ceramic interlayer and the FGM interlayer over the conventional sharp transition interface configuration in reduction of the thermal residual stress and improvement of stress profiles. Maximum stresses magnitudes were reduced by 10% for the crowns with 50% metal-50% ceramic interlayer and by 20% with FGM interlayer. The reduction in stress magnitude and smoothness of the stress distribution profile due to the gradated architectures might explain the improved behavior of these novel dental restorative systems relative to the conventional one, demonstrated by in-vitro studies already reported in literature. PMID:26122789

  13. Thermal imaging of soybean response to drought stress: the effect of Ascophyllum nodosum seaweed extract.

    Science.gov (United States)

    Martynenko, Alex; Shotton, Katy; Astatkie, Tessema; Petrash, Gerry; Fowler, Christopher; Neily, Will; Critchley, Alan T

    2016-01-01

    Previous experiments have demonstrated positive effect of Acadian(®) extract of Ascophyllum nodosum on plant stress-resistance, however the mode of action is not fully understood. The aim of this study was to understand the physiological effect of Acadian(®) seaweed extract on the plant response to drought stress. Leaf temperature and leaf angle were measured as early-stage indicators of plant stress with thermal imaging "in situ" over a 5-day stress-recovery trial. The early stress-response of control became visible on the third day as a rapid wilting of leaves, accompanied with the asymptotic increase of leaf temperature on 4-5 °C to the thermal equilibrium with ambient air temperature. At the same time Acadian(®) treated plants still maintained turgor, accompanied with the linear increase in leaf temperature, which indicated better control of stomatal closure. Re-watering on the fifth day showed better survival of treated plants compared to control. This study demonstrated the ability of Acadian(®) seaweed extract to improve resistance of soybean plants to water stress. PMID:27610312

  14. Chronic Psychosocial Factors and Acute Physiological Responses to Laboratory-Induced Stress in Healthy Populations: A Quantitative Review of 30 Years of Investigations

    Science.gov (United States)

    Chida, Yoichi; Hamer, Mark

    2008-01-01

    This meta-analysis included 729 studies from 161 articles investigating how acute stress responsivity (including stress reactivity and recovery of hypothalamic-pituitary-adrenal [HPA] axis, autonomic, and cardiovascular systems) changes with various chronic psychosocial exposures (job stress; general life stress; depression or hopelessness;…

  15. Dehydroepiandrosterone and Corticosterone Are Regulated by Season and Acute Stress in a Wild Songbird: Jugular Versus Brachial Plasma

    OpenAIRE

    Newman, Amy E.M.; Pradhan, Devaleena S.; Soma, Kiran K.

    2008-01-01

    Stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of glucocorticoids can have detrimental effects on the brain. Dehydroepiandrosterone (DHEA), an androgen precursor synthesized in the adrenal glands or the brain itself, has anti-glucocorticoid properties, but little is known about the role of DHEA in the stress response, particularly in the brain. Here, we measured the effects of acute restraint on circulating corticosterone (CORT) and DHEA levels in wil...

  16. Brain aromatase and circulating corticosterone are rapidly regulated by combined acute stress and sexual interaction in a sex specific manner

    OpenAIRE

    Dickens, M.J.; Balthazart, J.; Cornil, C. A.

    2012-01-01

    Neural production of 17β-oestradiol via aromatisation of testosterone may play a critical role in rapid, non-genomic regulation of physiological and behavioural processes. In brain nuclei implicated in the control of sexual behaviour, sexual or stressfull stimuli induce respectively a rapid inhibition or increase in preoptic aromatase activity (AA). Here, we tested quail that were either non-stressed or acutely stressed (15 min restraint) immediately prior to sexual interaction (5 min) with s...

  17. Vacuum-Cleaner Noise and Acute Stress Responses in Female C57BL/6 Mice (Mus musculus)

    OpenAIRE

    Jensen, Kelly; Hahn, Nina E; Palme, Rupert; Saxton, Katherine; Francis, Darlene D.

    2010-01-01

    Audiogenic stress is a well-documented phenomenon in laboratory rodents. Despite the recommendation in the Guide for the Care and Use of Laboratory Animals to consider noise a concern in the animal facility, only a small body of literature empirically addresses the effects of facility noise on laboratory rodents, particularly mice. The objective of this study was to determine whether facility noise generated by a vacuum cleaner induces an acute stress response in a commonly used strain of lab...

  18. Beyond Thermal Performance Curves: Modeling Time-Dependent Effects of Thermal Stress on Ectotherm Growth Rates.

    Science.gov (United States)

    Kingsolver, Joel G; Woods, H Arthur

    2016-03-01

    Thermal performance curves have been widely used to model the ecological responses of ectotherms to variable thermal environments and climate change. Such models ignore the effects of time dependence-the temporal pattern and duration of temperature exposure-on performance. We developed and solved a simple mathematical model for growth rate of ectotherms, combining thermal performance curves for ingestion rate with the temporal dynamics of gene expression and protein production in response to high temperatures to predict temporal patterns of growth rate in constant and diurnally fluctuating temperatures. We used the model to explore the effects of heat shock proteins on larval growth rates of Manduca sexta. The model correctly captures two empirical patterns for larval growth rate: first, maximal growth rate and optimal temperature decline with increasing duration of temperature exposure; second, mean growth rates decline with time in diurnally fluctuating temperatures at higher mean temperatures. These qualitative results apply broadly to cases where proteins or other molecules produced in response to high temperatures reduce growth rates. We discuss some of the critical assumptions and predictions of the model and suggest potential extensions and alternatives. Incorporating time-dependent effects will be essential for making more realistic predictions about the physiological and ecological consequences of temperature fluctuations and climate change. PMID:26913942

  19. Differential coral bleaching—Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress

    OpenAIRE

    Krüger, Thomas; Hawkins, Thomas; Becker, Susanne; Pontasch, Stefanie; Dove, Sophie; Hoegh-Guldberg, Ove; Leggat, William; Davy, Simon

    2015-01-01

    Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Co...

  20. The Stressed Female Brain: Neuronal activity in the prelimbic but not infralimbic region of the medial prefrontal cortex suppresses learning after acute stress

    Directory of Open Access Journals (Sweden)

    Lisa Y. Maeng

    2013-12-01

    Full Text Available Women are nearly twice as likely as men to suffer from anxiety and post-traumatic stress disorder (PTSD, indicating that many females are especially vulnerable to stressful life experience. A profound sex difference in the response to stress is also observed in laboratory animals. Acute exposure to an uncontrollable stressful event disrupts associative learning during classical eyeblink conditioning in female rats but enhances this same type of learning process in males. These sex differences in response to stress are dependent on neuronal activity in similar but also different brain regions. Neuronal activity in the basolateral nucleus of the amygdala (BLA is necessary in both males and females. However, neuronal activity in the medial prefrontal cortex (mPFC during the stressor is necessary to modify learning in females but not in males. The mPFC is often divided into its prelimbic (PL and infralimbic (IL subregions, which differ both in structure and function. Through its connections to the BLA, we hypothesized that neuronal activity within the PL, but not IL, during the stressor is necessary to suppress learning in females. To test this hypothesis, either the PL or IL of adult female rats was bilaterally inactivated with GABAA agonist muscimol during acute inescapable swim stress. 24h later, all subjects were trained with classical eyeblink conditioning. Though stressed, females without neuronal activity in the PL learned well. In contrast, females with IL inactivation during the stressor did not learn well, behaving similar to stressed vehicle-treated females. These data suggest that exposure to a stressful event critically engages the PL, but not IL, to disrupt associative learning in females. Together with previous studies, these data indicate that the PL communicates with the BLA to suppress learning after a stressful experience in females. This circuit may be similarly engaged in women who become cognitively impaired after stressful

  1. Functional Genomic Analysis of Variation on Beef Tenderness Induced by Acute Stress in Angus Cattle

    Directory of Open Access Journals (Sweden)

    Chunping Zhao

    2012-01-01

    Full Text Available Beef is one of the leading sources of protein, B vitamins, iron, and zinc in human food. Beef palatability is based on three general criteria: tenderness, juiciness, and flavor, of which tenderness is thought to be the most important factor. In this study, we found that beef tenderness, measured by the Warner-Bratzler shear force (WBSF, was dramatically increased by acute stress. Microarray analysis and qPCR identified a variety of genes that were differentially expressed. Pathway analysis showed that these genes were involved in immune response and regulation of metabolism process as activators or repressors. Further analysis identified that these changes may be related with CpG methylation of several genes. Therefore, the results from this study provide an enhanced understanding of the mechanisms that genetic and epigenetic regulations control meat quality and beef tenderness.

  2. Femoral diaphyseal stress fracture as the initial presentation of acute leukaemia in an adolescent.

    Science.gov (United States)

    Chase, Helen Emily; Pang, Joe Hwong; Sanghrajka, Anish Pradip

    2016-01-01

    A 14-year-old boy was referred to the orthopaedic clinic by his general practitioner, reporting of a 6-week history of left thigh pain. Clinical examination was unremarkable. Radiographs demonstrated a periosteal reaction at the proximal femur. MRI scans demonstrated a stress fracture of the femur, with no associated sinister features and no evidence of a pathological lesion. As the fracture healed and symptoms improved, the patient became unwell with weight loss, lethargy, chest and jaw pain and fevers. After multiple blood tests over a 25-day period, including five full blood counts and two normal blood films, a third blood film finally demonstrated blasts in keeping with acute leukaemia. We discuss a literature review of musculoskeletal manifestations of leukaemia and the often atypical presentations found. PMID:27353177

  3. Characterisation of acute toxicity, genotoxicity and oxidative stress posed by textile effluent on zebrafish

    Institute of Scientific and Technical Information of China (English)

    Wenjuan Zhang; Wei Liu; Jing Zhang; Huimin Zhao; Yaobin Zhang; Xie Quan; Yihe Jin

    2012-01-01

    Textile industries are important sources of toxic discharges and contribute enormously to water deterioration,while little attention has been paid to the toxicity of textile effluents in discharge regulation.Bioassays with zebrafish were employed to evaluate the toxicity of wastewater samples collected from different stages at a textile factory and sewage treatment plants (STPs).Physico-chemical parameters,acute toxicity,genotoxicity and oxidative stress biomarkers were analyzed.The wastewater samples from bleaching,rinsing and soaping of the textile factory exhibited high acute toxicity and genotoxicity.The coexisting components of dye compounds,as assistants and oxidants,seemed to cause some effect on the toxic response.After treatment employing the anoxic-oxic (A/O) process in STPs,the color and the chemical oxygen demand (COD) were reduced by 40% and 84%,respectively,falling within the criteria of the Chinese Sewage Discharge Standard.In contrast,increases in acute toxicity and genotoxicity were observed in the anaerobic tank,indicating the formation of toxic intermediates.The genotoxicity of the effluent of the STP was not significantly different from that of the influent,suggesting the wastewater treatment processes were not effective in removing the genotoxicity of the dye wastewater.Results indicated that the effluent contains pro-oxidants since the activities of glutathione (GSH),malondialdehyde (MDA),and total anti-oxidation capacity (T-AOC) were all elevated.In addition,decreases in superoxide dismutase (SOD) and glutathione-S transferase (GST) activities observed can be interpreted as a cytotoxicity sign due to an over-production of reactive oxygen species (ROS).The results of the present study suggest that the STPs were not capable of reducing the toxicity of wastewater sufficiently.Further treatment is needed to remove the potential risks posed by textile effluent to ecosystems and human health,and employing a toxicity index is necessary for

  4. S-nitroso-proteome in poplar leaves in response to acute ozone stress.

    Directory of Open Access Journals (Sweden)

    Elisa Vanzo

    Full Text Available Protein S-nitrosylation, the covalent binding of nitric oxide (NO to protein cysteine residues, is one of the main mechanisms of NO signaling in plant and animal cells. Using a combination of the biotin switch assay and label-free LC-MS/MS analysis, we revealed the S-nitroso-proteome of the woody model plant Populus x canescens. Under normal conditions, constitutively S-nitrosylated proteins in poplar leaves and calli comprise all aspects of primary and secondary metabolism. Acute ozone fumigation was applied to elicit ROS-mediated changes of the S-nitroso-proteome. This treatment changed the total nitrite and nitrosothiol contents of poplar leaves and affected the homeostasis of 32 S-nitrosylated proteins. Multivariate data analysis revealed that ozone exposure negatively affected the S-nitrosylation status of leaf proteins: 23 proteins were de-nitrosylated and 9 proteins had increased S-nitrosylation content compared to the control. Phenylalanine ammonia-lyase 2 (log2[ozone/control] = -3.6 and caffeic acid O-methyltransferase (-3.4, key enzymes catalyzing important steps in the phenylpropanoid and subsequent lignin biosynthetic pathways, respectively, were de-nitrosylated upon ozone stress. Measuring the in vivo and in vitro phenylalanine ammonia-lyase activity indicated that the increase of the phenylalanine ammonia-lyase activity in response to acute ozone is partly regulated by de-nitrosylation, which might favor a higher metabolic flux through the phenylpropanoid pathway within minutes after ozone exposure.

  5. OPTICAL IMAGING OF LIPOPOLYSACCHARIDE-INDUCED OXIDATIVE STRESS IN ACUTE LUNG INJURY FROM HYPEROXIA AND SEPSIS.

    Science.gov (United States)

    Sepehr, Reyhaneh; Audi, Said H; Maleki, Sepideh; Staniszewski, Kevin; Eis, Annie L; Konduri, Girija G; Ranji, Mahsa

    2013-07-01

    Reactive oxygen species (ROS) have been implicated in the pathogenesis of many acute and chronic pulmonary disorders such as acute lung injury (ALI) in adults and bronchopulmonary dysplasia (BPD) in premature infants. Bacterial infection and oxygen toxicity, which result in pulmonary vascular endothelial injury, contribute to impaired vascular growth and alveolar simplification seen in the lungs of premature infants with BPD. Hyperoxia induces ALI, reduces cell proliferation, causes DNA damage and promotes cell death by causing mitochondrial dysfunction. The objective of this study was to use an optical imaging technique to evaluate the variations in fluorescence intensities of the auto-fluorescent mitochondrial metabolic coenzymes, NADH and FAD in four different groups of rats. The ratio of these fluorescence signals (NADH/FAD), referred to as NADH redox ratio (NADH RR) has been used as an indicator of tissue metabolism in injuries. Here, we investigated whether the changes in metabolic state can be used as a marker of oxidative stress caused by hyperoxia and bacterial lipopolysaccharide (LPS) exposure in neonatal rat lungs. We examined the tissue redox states of lungs from four groups of rat pups: normoxic (21% O2) pups, hyperoxic (90% O2) pups, pups treated with LPS (normoxic + LPS), and pups treated with LPS and hyperoxia (hyperoxic + LPS). Our results show that hyperoxia oxidized the respiratory chain as reflected by a ~31% decrease in lung tissue NADH RR as compared to that for normoxic lungs. LPS treatment alone or with hyperoxia had no significant effect on lung tissue NADH RR as compared to that for normoxic or hyperoxic lungs, respectively. Thus, NADH RR serves as a quantitative marker of oxidative stress level in lung injury caused by two clinically important conditions: hyperoxia and LPS exposure.

  6. Calculation of Local Stress and Fatigue Resistance due to Thermal Stratification on Pressurized Surge Line Pipe

    International Nuclear Information System (INIS)

    Thermal stratification introduces thermal shock effect which results in local stress and fatigue problems that must be considered in the design of nuclear power plant components. Local stress and fatigue calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343 deg. C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.

  7. Thermal conductivity of silicon nitride membranes is not sensitive to stress

    Science.gov (United States)

    Ftouni, Hossein; Blanc, Christophe; Tainoff, Dimitri; Fefferman, Andrew D.; Defoort, Martial; Lulla, Kunal J.; Richard, Jacques; Collin, Eddy; Bourgeois, Olivier

    2015-09-01

    We have measured the thermal properties of suspended membranes from 10 to 300 K for two amplitudes of internal stress (about 0.1 and 1 GPa) and for two different thicknesses (50 and 100 nm). The use of the original 3 ω -Volklein method has allowed the extraction of both the specific heat and the thermal conductivity of each SiN membrane over a wide temperature range. The mechanical properties of the same substrates have been measured at helium temperatures using nanomechanical techniques. Our measurements show that the thermal transport in freestanding SiN membranes is not affected by the presence of internal stress. Consistently, mechanical dissipation is also unaffected even though Q 's increase with increasing tensile stress. We thus demonstrate that the theory developed by Wu and Yu [J. Wu and C. C. Yu, Phys. Rev. B 84, 174109 (2011), 10.1103/PhysRevB.84.174109] does not apply to this amorphous material in this stress range. On the other hand, our results can be viewed as a natural consequence of the "dissipation dilution" argument [Y. L. Huang and P. R. Saulson, Rev. Sci. Instrum. 69, 544 (1998), 10.1063/1.1148692], which has been introduced in the context of mechanical damping.

  8. Temperature-time distribution and thermal stresses on the RTG fins and shell during water cooling

    Science.gov (United States)

    Turner, R. H.

    1983-01-01

    Radioisotope thermoelectric generator (RTG) packages designed for space missions generally do not require active cooling. However, the heat they generate cannot remain inside of the launch vehicle bay and requires active removal. Therefore, before the Shuttle bay door is closed, the RTG coolant tubes attached to the heat rejection fins must be filled with water, which will circulate and remove most of the heat from the cargo bay. There is concern that charging a system at initial temperature around 200 C with water at 24 C can cause unacceptable thermal stresses in the RTG shell and fins. A computer model is developed to estimate the transient temperature distribution resulting from such charging. The thermal stresses resulting from the temperature gradients do not exceed the elastic deformation limit for the material. Since the simplified mathematical model for thermal stresses tends to overestimate stresses, it is concluded that the RTG can be cooled by introducing water at 24 C to the initially hot fin coolant tubes while the RTG is in the Shuttle cargo bay.

  9. Steady thermal stress and strain rates in a rotating circular cylinder under steady state temperature

    Directory of Open Access Journals (Sweden)

    Pankaj Thakur

    2014-01-01

    Full Text Available Thermal stress and strain rates in a thick walled rotating cylinder under steady state temperature has been derived by using Seth’s transition theory. For elastic-plastic stage, it is seen that with the increase of temperature, the cylinder having smaller radii ratios requires lesser angular velocity to become fully plastic as compared to cylinder having higher radii ratios The circumferential stress becomes larger and larger with the increase in temperature. With increase in thickness ratio stresses must be decrease. For the creep stage, it is seen that circumferential stresses for incompressible materials maximum at the internal surface as compared to compressible material, which increase with the increase in temperature and measure n.

  10. Impact of physical activity on energy balance, food intake and choice in normal weight and obese children in the setting of acute social stress: a randomized controlled trial

    OpenAIRE

    Horsch A.; Wobmann M.; Kriemler S.; Munsch S.; Borloz S.; Balz A.; Marques-Vidal P.; Borghini A.; Puder J. J.

    2015-01-01

    BACKGROUND: Psychological stress negatively influences food intake and food choices, thereby contributing to the development of childhood obesity. Physical activity can also moderate eating behavior and influence calorie intake. However, it is unknown if acute physical activity influences food intake and overall energy balance after acute stress exposure in children. We therefore investigated the impact of acute physical activity on overall energy balance (food intake minus energy expenditure...

  11. Psychobiology of the acute stress response and its relationship to the psychobiology of post-traumatic stress disorder.

    Science.gov (United States)

    Marshall, Randall D; Garakani, Amir

    2002-06-01

    The literature to date that examines the biology of the acute stress reactions suggests that relatively lower baseline cortisol is associated with the development of PTSD. This is particularly informative because of the ongoing controversy surrounding baseline cortisol in PTSD. Studies have found low baseline cortisol, normal range, and elevated baseline cortisol in chronic PTSD, and it has been unclear whether this reflects methodologic differences across studies or true heterogeneity within the disorder. Thus, the few studies to date support the finding of low-normal baseline cortisol in chronic PTSD and suggest that it is a pre-existing functional trait. Whether it plays an etiologic role or is an epiphenomenon of some other process is unclear. What does seem clear, however, is that this characteristic is relatively nonspecific to PTSD, given the fact that low cortisol has been observed in multiple subject populations, including normal individuals under chronic stress as well as chronic medical conditions (for review see [23]). For example, it is possible that reduced baseline cortisol reflects the net result of input to the hypothalamus from cortical and subcortical regions of the brain linked to increased vigilance, sensitization to trauma because of prior traumatic experiences, or genetic factors. For example, primate studies have demonstrated persistent alterations in HPA axis functioning in animals reared by mothers living in moderately stressful conditions [24]. The development of PTSD is associated with sensitization of the startle response. Because the neurobiology of startle is well characterized, this finding implicates a role for specific neurocircuitry in PTSD [25]. Non-habituation of the startle response in PTSD appears related to sensitization specifically to contextual cues (i.e., the environment) that signal the presence of potential threat of danger-related fears [26]. This may be the neurobiological correlate to the over-generalization seen in

  12. Classification of acute stress using linear and non-linear heart rate variability analysis derived from sternal ECG

    DEFF Research Database (Denmark)

    Tanev, George; Saadi, Dorthe Bodholt; Hoppe, Karsten;

    2014-01-01

    features from electrocardiograms (ECG) acquired by the wireless wearable ePatch® recorder. The highest recognition rates were acquired for the neutral stage (90%), the acute stress stage (80%) and the baseline stage (80%) by sample entropy, detrended fluctuation analysis and normalized high frequency...

  13. Acute Exposure to Stress Improves Performance in Trace Eyeblink Conditioning and Spatial Learning Tasks in Healthy Men

    Science.gov (United States)

    Duncko, Roman; Cornwell, Brian; Cui, Lihong; Merikangas, Kathleen R.; Grillon, Christian

    2007-01-01

    The present study investigated the effects of acute stress exposure on learning performance in humans using analogs of two paradigms frequently used in animals. Healthy male participants were exposed to the cold pressor test (CPT) procedure, i.e., insertion of the dominant hand into ice water for 60 sec. Following the CPT or the control procedure,…

  14. Locus of Control Predicts Cortisol Reactivity and Speech Performance in Response to Acute Stress in Undergraduate Students

    Science.gov (United States)

    Szabo, Yvette Z.; Chang, Andrew; Chancellor-Freeland, Cheryl

    2015-01-01

    Previous studies have found that an individual's perception of control in a situation (Locus of Control; LOC) can serve as a protective factor that has physiological and psychological benefits. The present study examines LOC in an acute stress paradigm to examine the relationship between LOC and hypothalamic-pituitary-adrenal axis functioning as…

  15. Rest/stress myocardial perfusion imaging: A means to prevent missed acute ischemic coronary syndrome diagnoses

    International Nuclear Information System (INIS)

    Aim: The sensitivity and specificity of rest/stress (R/S) myocardial perfusion imaging (MPI) in detecting an acute ischemic coronary syndrome (AICS) was determined in 100 consecutive patients (pts) admitted to the Chest Pain Clinic-Observation Unit (CPC-OU) with chest pain (CP) of suspected cardiac etiology and a negative (neg) or non diagnostic (dx) EKG. There were 57 females and 43 males, 30-83 years of age. 50 studies were performed from 1/15/98 to 4/2/98; 50 from 11/19/99 to 1/10/00. Material and Methods: An AICS was deemed present if a reversible perfusion defect was demonstrated scintigraphically; a ?50% luminal narrow angiographically. No AICS if the pt had a normal R/S MPI, a fixed defect with normal wall motion and thickening, a neg cardiac catheterization, or was free of cardiac symptoms and had no history of a vascular event for 2-3 years post CPC-OU admission. 13 pts with a positive MPI had a cardiac catheterization, none with a neg MPI. SPECT rest MPI's were performed 30-90 minutes (mins) post 10.0 mCi of technetium 99m Sestamibi. SPECT stress MPI's were performed following a 6-8 hour acute myocardial infarction enzyme (CP-MB/Troponin 1) rule out and 30-90 mins post 30.0 mCi of technetium 99m Sestamibi. Results: 29 pts were lost to follow-up. There were 12 true positive, 5 false positive, 54 true negative and 0 false negative studies. The sensitivity, specificity, positive and negative predictive value of a R/S MPI in detecting an AICS is 100%, 91%, 70% and 100%, respectively. An AICS was detected in 12% of pts admitted to the CPC-OU; a finding that correlates with its reported incidence of 2-12%. 6 were managed medically, 3 required emergent bypass surgery, 3 were stented. Conclusion: R/S MPI should be included in the CPC-OU dx work-up of pts with CP of suspected cardiac etiology to prevent missed AICS diagnoses. Patient care will be optimized and health care and medical malpractice awards for failure to diagnosis an acute myocardial infarction

  16. Time-Course Changes of Steroidogenic Gene Expression and Steroidogenesis of Rat Leydig Cells after Acute Immobilization Stress

    Directory of Open Access Journals (Sweden)

    Han Lin

    2014-11-01

    Full Text Available Leydig cells secrete testosterone, which is essential for male fertility and reproductive health. Stress increases the secretion of glucocorticoid (corticosterone, CORT; in rats, which decreases circulating testosterone levels in part through a direct action by binding to the glucocorticoid receptors (NR3C1 in Leydig cells. The intratesticular CORT level is dependent on oxidative inactivation of glucocorticoid by 11β-hydroxysteroid dehydrogenase 1 (HSD11B1 in Leydig cells. In the present study, we investigated the time-course changes of steroidogenic gene expression levels after acute immobilization stress in rats. The plasma CORT levels were significantly increased 0.5, 1, 3 and 6 h after immobilization stress, while plasma testosterone levels were significantly reduced 3 and 6 h, after stress and luteinizing hormone (LH did not change. Immobilization stress caused the down-regulation of Scarb1, Star and Cyp17a1 expression levels in the rat testis starting at the first hour of stress, ahead of the significant decreases of plasma testosterone levels. Other mRNA levels, including Cyp11a1, Hsd3b1 and Hsd17b3, began to decline after 3 h. Hsd11b1 and Nos2 mRNA levels did not change during the course of stress. Administration of glucocorticoid antagonist RU486 significantly restored plasma testosterone levels. In conclusion, Scarb1, Star and Cyp17a1 expression levels are more sensitive to acute stress, and acute immobilization stress causes the decline of the steroidogenic pathway via elevating the levels of glucocorticoid, which binds to NR3C1 in Leydig cells to inhibit steroidogenic gene expression.

  17. Acute social stress before the planning phase improves memory performance in a complex real life-related prospective memory task.

    Science.gov (United States)

    Glienke, Katharina; Piefke, Martina

    2016-09-01

    Successful execution of intentions, but also the failure to recall are common phenomena in everyday life. The planning, retention, and realization of intentions are often framed as the scientific concept of prospective memory. The current study aimed to examine the influence of acute stress on key dimensions of complex "real life" prospective memory. To this end, we applied a prospective memory task that involved the planning, retention, and performance of intentions during a fictional holiday week. Forty healthy males participated in the study. Half of the subjects were stressed with the Socially Evaluated Cold Pressor Test (SECPT) before the planning of intentions, and the other half of the participants underwent a control procedure at the same time. Salivary cortisol was used to measure the effectiveness of the SECPT stress induction. Stressed participants did not differ from controls in planning accuracy. However, when we compared stressed participants with controls during prospective memory retrieval, we found statistically significant differences in PM across the performance phase. Participants treated with the SECPT procedure before the planning phase showed improved prospective memory retrieval over time, while performance of controls declined. Particularly, there was a significant difference between the stress and control group for the last two days of the holiday week. Interestingly, control participants showed significantly better performance for early than later learned items, which could be an indicator of a primacy effect. This differential effect of stress on performance was also found in time- and event-dependent prospective memory. Our results demonstrate for the first time, that acute stress induced before the planning phase may improve prospective memory over the time course of the performance phase in time- and event-dependent prospective memory. Our data thus indicate that prospective memory can be enhanced by acute stress.

  18. Acute social stress before the planning phase improves memory performance in a complex real life-related prospective memory task.

    Science.gov (United States)

    Glienke, Katharina; Piefke, Martina

    2016-09-01

    Successful execution of intentions, but also the failure to recall are common phenomena in everyday life. The planning, retention, and realization of intentions are often framed as the scientific concept of prospective memory. The current study aimed to examine the influence of acute stress on key dimensions of complex "real life" prospective memory. To this end, we applied a prospective memory task that involved the planning, retention, and performance of intentions during a fictional holiday week. Forty healthy males participated in the study. Half of the subjects were stressed with the Socially Evaluated Cold Pressor Test (SECPT) before the planning of intentions, and the other half of the participants underwent a control procedure at the same time. Salivary cortisol was used to measure the effectiveness of the SECPT stress induction. Stressed participants did not differ from controls in planning accuracy. However, when we compared stressed participants with controls during prospective memory retrieval, we found statistically significant differences in PM across the performance phase. Participants treated with the SECPT procedure before the planning phase showed improved prospective memory retrieval over time, while performance of controls declined. Particularly, there was a significant difference between the stress and control group for the last two days of the holiday week. Interestingly, control participants showed significantly better performance for early than later learned items, which could be an indicator of a primacy effect. This differential effect of stress on performance was also found in time- and event-dependent prospective memory. Our results demonstrate for the first time, that acute stress induced before the planning phase may improve prospective memory over the time course of the performance phase in time- and event-dependent prospective memory. Our data thus indicate that prospective memory can be enhanced by acute stress. PMID:27370532

  19. THE EFFECTS OF ACUTE AND CHRONIC STRESS ON ERYTHROCYTE DYNAMIC IN COMBINATION WITH ß–ADRENERGIC RECEPTORS BLOCKADE IN RATS

    Directory of Open Access Journals (Sweden)

    Lucian Hritcu

    2005-08-01

    Full Text Available : 3 consecutive days propranolol hydrochloride administration (5 mg/kg b.w., subcutaneous injections under acute and chronic stress conditions causes changes of peripheral erythrocyte distribution in rats. The effects of acute stress and its combination with ȕ-adrenergic receptor blockade on erythrocyte dynamic were more pregnant beside the effects of chronic stress and its combination with ȕ-adrenergic receptor blockade, respectively. ȕ-adrenergic mechanisms were shown to be involved in regulation of erythrocyte dynamic in acute and chronic stress response.

  20. Piezotronic Effect Enhanced Photocatalysis in Strained Anisotropic ZnO/TiO₂ Nanoplatelets via Thermal Stress.

    Science.gov (United States)

    Wang, Longfei; Liu, Shuhai; Wang, Zheng; Zhou, Yongli; Qin, Yong; Wang, Zhong Lin

    2016-02-23

    Effective piezoelectric semiconductor based hybrid photocatalysts are successfully developed by assembling TiO2 nanoparticles on ZnO monocrystalline nanoplatelets. The piezopotential can be introduced and tuned by thermal stress on the piezoelectric material of ZnO monocrystalline nanoplatelets through cooling hybrid photocatalysts from high temperature to room temperature with different rates based on the mismatched thermal expansion coefficient of the two materials, which can be used to engineer the heterojunction band structure and significantly enhance the photocatalytic performance in a wide range by improving charge separation. It is proposed that the piezotronic effect enhanced photocatalyst will provide a strategy for high-performance photocatalysis applications.

  1. The effect of thermal properties and weld efficiency on residual stresses in welding

    Directory of Open Access Journals (Sweden)

    E. Armentani

    2007-01-01

    Full Text Available Purpose: A parametric model is adopted and the technique of element “birth and death” is used to estimate theeffect of thermal properties and weld efficiency on residual stresses in butt weld joints.Design/methodology/approach: Residual stresses and distortions on butt welded joints are numericallyevaluated by means of finite element method. The FE analysis allows to highlight and evaluate the stress fieldand its gradient around the fusion zone of welded joints, higher than any other located in the surrounding area.Findings: The main conclusion is the significant effect of varying the value of the conductivity on residualstresses.Practical implications: Several experimental destructive and non destructive techniques for directly measuringresidual stress have been developed. However, the application of these methods in practice is usually limitedby either cost or accuracy. Numerical simulation based on finite element techniques, therefore, offers acomprehensive solution for the prediction of residual stress and strain as well as welding distortion in complexwelded structures.Originality/value: In this study it is shown that the technique of element “birth and death” can be usefullyapplied to welding process in order to take in account the effect of the thermal properties of materials.

  2. Changes in fatty acid composition in the giant clam Tridacna maxima in response to thermal stress

    Science.gov (United States)

    Dubousquet, Vaimiti; Gros, Emmanuelle; Berteaux-Lecellier, Véronique; Viguier, Bruno; Raharivelomanana, Phila; Bertrand, Cédric; Lecellier, Gaël J.

    2016-01-01

    ABSTRACT Temperature can modify membrane fluidity and thus affects cellular functions and physiological activities. This study examines lipid remodelling in the marine symbiotic organism, Tridacna maxima, during a time series of induced thermal stress, with an emphasis on the morphology of their symbiont Symbiodinium. First, we show that the French Polynesian giant clams harbour an important proportion of saturated fatty acids (SFA), which reflects their tropical location. Second, in contrast to most marine organisms, the total lipid content in giant clams remained constant under stress, though some changes in their composition were shown. Third, the stress-induced changes in fatty acid (FA) diversity were accompanied by an upregulation of genes involved in lipids and ROS pathways. Finally, our microscopic analysis revealed that for the giant clam's symbiont, Symbiodinium, thermal stress led to two sequential cell death processes. Our data suggests that the degradation of Symbiodinium cells could provide an additional source of energy to T. maxima in response to heat stress. PMID:27543058

  3. Thermal stress in the edge cladding of Nova glass laser disks

    International Nuclear Information System (INIS)

    We calculated thermal stresses in Nova glass laser disks having light-absorbing edge cladding glass attached to the periphery with an epoxy adhesive. Our closed-form solutions indicated that, because the epoxy adhesive is only 25 μm across, it does not significantly affect the thermal stress in the disk or cladding glass. Our numerical results showed a peak tensile stress in the cladding glass of 24 MPa when the cladding glass had a uniform absorption coefficient of 7.5 cm-1. This peak value is reduced to 19 MPa if surface parasitic oscillation heating is eliminated by tilting the disk edges. The peak tensile stresses exceed the typical 7 to 14-MPa working stress for glass; however, we have not observed any disk or cladding glass failures at peak Nova fluences of 20 J/cm2. We have observed delamination of the epoxy adhesive bond at fluences several times that which would occur on Nova. Replacement laser disks will incorporate cladding with a reduced absorption coefficient of 4.5 cm-1. Recent experiments show that this reduced absorption coefficient is satisfactory

  4. Facilitation of the HPA Axis to a Novel Acute Stress Following Chronic Stress Exposure Modulates Histone Acetylation and the ERK/MAPK Pathway in the Dentate Gyrus of Male Rats

    OpenAIRE

    Ferland, Chantelle L.; Harris, Erin P.; Lam, Mai; Schrader, Laura A.

    2014-01-01

    Evidence suggests that when presented with novel acute stress, animals previously exposed to chronic homotypic or heterotypic stressors exhibit normal or enhanced hypothalamic-pituitary-adrenal (HPA) response compared with animals exposed solely to that acute stressor. The molecular mechanisms involved in this effect remain unknown. The extracellular signal-regulated kinase (ERK) is one of the key pathways regulated in the hippocampus in both acute and chronic stress. The aim of this study wa...

  5. Caustic stress corrosion cracking of austenitic stainless steels with thermal treatment(TT)

    International Nuclear Information System (INIS)

    This paper dealt with the effects of TT(Thermal Treatment) and nitrogen content on caustic stress corrosion cracking of austenitic stainless steels. Nitrogen content and grain size had affected on the caustic SCC resistance. Increasing nitrogen content, SCC resistance was increased due to the enhanced repassivation rate, but at high nitrogen content, the resistance was decreased because of the dual effects between mechanical and repassivation behavior. Regardless of nitrogen content, TT improved the caustic SCC resistance and this behavior was reviewed on the points of residual stress, grain size, and dislocation array

  6. Reactive oxygen species in pregnant rats: effects of exercise and thermal stress.

    Science.gov (United States)

    Osorio, R A L; Christofani, J S; D'Almeida, V; Russo, A K; Piçarro, I C

    2003-05-01

    With the aim of evaluating the effect of interaction between physical training or exercise only during pregnancy and thermal stress on oxidative stress, and antioxidant mechanism sedentary pregnant rats (PS), exercised pregnant rats only during pregnancy (PE) and trained rats submitted to also exercise during pregnancy (PT) were compared (N=63). Exercise sessions consisted of swimming at 80% of maximal work load supported into water at 28 degrees C (hypothermia, PS 28, PE28, PT28) or 35 degrees C (thermal neutrality, PS35, PE35, PT35) or 39 degrees C (hyperthermia, PS39, PE39, PT39), for 30 min. The initial body weight in all groups of rats was from 177 to 207 g. On the 20th day of pregnancy, 24 h after the last immersion or swimming session venous blood was collected to determine oxidative stress. Plasma concentrations of means malondialdehyde (MDA) values measured as thiobarbituric acid reactive substances (TBARS); total glutathione (GSH) and vitamin E were determined. The oxidative stress index was calculated from the ratio TBARS/GSH and TBARS/Vitamin E. TBARS did not change on the group PE at different temperatures of water; TBARS were higher for PS28 than PS35 and PS39; PT35 had higher values than PT28 and PT39. For GSH, PS39 was lower than PS35; PE28 was higher than PE35 and PE39 and PT35 were lower than PT28 and PT39. Plasma concentration of vitamin E did not present any difference for sedentary rats at different water temperatures, but for PE28, the values were lower than for PE35 and PE39, whereas PT39 was lower than PT35 and PT28. In relation to TBARS/GSH, it was verified an increase in oxidative stress for PS28 (in relation to PS35 and PS39), PE35, and PT35 (in relation to PE28 and PE39 or PT28 and PT39); regarding the ratio TBARS/vitamin E, the highest values were obtained at 35 degrees C for PS and PT groups and at 39 for PE group. These results have shown the great complexity of the interaction between physical training, thermal stress and pregnancy

  7. Quasi-static transient thermal stresses in a thick annular disc

    Indian Academy of Sciences (India)

    V S Kulkarni; K C Deshmukh

    2007-10-01

    The present paper deals with the determination of transient thermal stresses in a thick annular disc. A thick annular disc is considered having zero initial temperature and subjected to arbitrary heat flux on the upper and lower surfaces where as the fixed circular edges are at zero temperature.The governing heat conduction equation have been solved by using integral transform technique. The results are obtained in series form in terms of Bessel’s functions. The results for displacement and stresses have been computed numerically and are illustrated graphically

  8. Prediction of Short-Circuit-Related Thermal Stress in Aged IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Uhrenfeldt, Christian;

    2016-01-01

    In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purpose...... surface temperature distribution which confirms the hypothesis that short-circuit events produce significantly uneven stresses on bond wires....... fabricated. The temperature distribution produced by such abnormal conditions has been modelled first by means of FEM simulations and then experimentally validated by means of a non-destructive testing technique including an ultra-fast infrared camera. Results demonstrate a significant imbalance in the...

  9. A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales duringhigh temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed onthe surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novelmethod does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be usedunaer tne condition of longer time and higher temperature.

  10. The impact of acute stress on hormones and cytokines, and how their recovery is affected by music-evoked positive mood.

    Science.gov (United States)

    Koelsch, Stefan; Boehlig, Albrecht; Hohenadel, Maximilian; Nitsche, Ines; Bauer, Katrin; Sack, Ulrich

    2016-01-01

    Stress and recovery from stress significantly affect interactions between the central nervous system, endocrine pathways, and the immune system. However, the influence of acute stress on circulating immune-endocrine mediators in humans is not well known. Using a double-blind, randomized study design, we administered a CO2 stress test to n = 143 participants to identify the effects of acute stress, and recovery from stress, on serum levels of several mediators with immune function (IL-6, TNF-α, leptin, and somatostatin), as well as on noradrenaline, and two hypothalamic-pituitary-adrenal axis hormones (ACTH and cortisol). Moreover, during a 1 h-recovery period, we repeatedly measured these serum parameters, and administered an auditory mood-induction protocol with positive music and a neutral control stimulus. The acute stress elicited increases in noradrenaline, ACTH, cortisol, IL-6, and leptin levels. Noradrenaline and ACTH exhibited the fastest and strongest stress responses, followed by cortisol, IL-6 and leptin. The music intervention was associated with more positive mood, and stronger cortisol responses to the acute stressor in the music group. Our data show that acute (CO2) stress affects endocrine, immune and metabolic functions in humans, and they show that mood plays a causal role in the modulation of responses to acute stress. PMID:27020850

  11. The impact of acute stress on hormones and cytokines, and how their recovery is affected by music-evoked positive mood

    Science.gov (United States)

    Koelsch, Stefan; Boehlig, Albrecht; Hohenadel, Maximilian; Nitsche, Ines; Bauer, Katrin; Sack, Ulrich

    2016-01-01

    Stress and recovery from stress significantly affect interactions between the central nervous system, endocrine pathways, and the immune system. However, the influence of acute stress on circulating immune-endocrine mediators in humans is not well known. Using a double-blind, randomized study design, we administered a CO2 stress test to n = 143 participants to identify the effects of acute stress, and recovery from stress, on serum levels of several mediators with immune function (IL-6, TNF-α, leptin, and somatostatin), as well as on noradrenaline, and two hypothalamic–pituitary–adrenal axis hormones (ACTH and cortisol). Moreover, during a 1 h-recovery period, we repeatedly measured these serum parameters, and administered an auditory mood-induction protocol with positive music and a neutral control stimulus. The acute stress elicited increases in noradrenaline, ACTH, cortisol, IL-6, and leptin levels. Noradrenaline and ACTH exhibited the fastest and strongest stress responses, followed by cortisol, IL-6 and leptin. The music intervention was associated with more positive mood, and stronger cortisol responses to the acute stressor in the music group. Our data show that acute (CO2) stress affects endocrine, immune and metabolic functions in humans, and they show that mood plays a causal role in the modulation of responses to acute stress. PMID:27020850

  12. Acute predator stress impairs the consolidation and retrieval of hippocampus-dependent memory in male and female rats

    OpenAIRE

    Collin R Park; Zoladz, Phillip R.; Conrad, Cheryl D.; Fleshner, Monika; Diamond, David M

    2008-01-01

    We have studied the effects of an acute predator stress experience on spatial learning and memory in adult male and female Sprague-Dawley rats. All rats were trained to learn the location of a hidden escape platform in the radial-arm water maze (RAWM), a hippocampus-dependent spatial memory task. In the control (non-stress) condition, female rats were superior to the males in the accuracy and consistency of their spatial memory performance tested over multiple days of training. In the stress ...

  13. Behavioral response of tilapia (Oreochromis niloticus) to acute ammonia stress monitored by computer vision

    Institute of Scientific and Technical Information of China (English)

    XU Jian-yu; MIAO Xiang-wen; LIU Ying; CUI Shao-rong

    2005-01-01

    The behavioral responses of a tilapia (Oreochromis niloticus) school to low (0.13 mg/L), moderate (0.79 mg/L) and high (2.65 mg/L) levels of unionized ammonia (UIA) concentration were monitored using a computer vision system. The swimming activity and geometrical parameters such as location of the gravity center and distribution of the fish school were calculated continuously. These behavioral parameters of tilapia school responded sensitively to moderate and high UIA concentration. Under high UIA concentration the fish activity showed a significant increase (P<0.05), exhibiting an avoidance reaction to high ammonia condition, and then decreased gradually. Under moderate and high UIA concentration the school's vertical location had significantly large fluctuation (P<0.05) with the school moving up to the water surface then down to the bottom of the aquarium alternately and tending to crowd together. After several hours' exposure to high UIA level, the school finally stayed at the aquarium bottom. These observations indicate that alterations in fish behavior under acute stress can provide important information useful in predicting the stress.

  14. von Willebrand Factor and Oxidative Stress Parameters in Acute Coronary Syndromes

    Directory of Open Access Journals (Sweden)

    Zoran Koprivica

    2011-01-01

    Full Text Available Considering the role of von Willebrand factor (vWf in hemostasis, and the role of oxidative stress in the development of endothelial dysfunction and atherosclerotic disease, the aim of our study was to investigate the relationship between vWf, parameters of oxidative stress and different types of acute coronary syndromes (ACS. Levels of vWf activity (vWfAct, vWf antigen (vWfAg, nitric oxide (estimated through nitrites–NO2 −, superoxide anion radical (O2 −, hydrogen peroxide (H2O2, index of lipid peroxidation (estimated through thiobarbituric acid reactive substances–TBARS, superoxide dismutase (SOD and catalase (CAT activity of 115 patients were compared with those of 40 healthy controls. ACS patients had significantly higher vWfAct and vWfAg levels, as well as TBARS levels, while their levels of NO2 −, H2O2, SOD and CAT activities were lower than controls'. vWfAg showed high specificity and sensitivity as a test to reveal healthy or diseased subjects. Multivariant logistic regression marked only vWfAg and TBARS as parameters that were under independent effect of ACS type. The results of our study support the implementation of vWf in clinical rutine and into therapeutic targets, and suggest that ACS patients are in need of antioxidant supplementation to improve their impaired antioxidant defence.

  15. Von Willebrand factor and oxidative stress parameters in acute coronary syndromes.

    Science.gov (United States)

    Koprivica, Zoran; Djordjevic, Dusica; Vuletic, Milena; Zivkovic, Vladimir; Barudzic, Nevena; Andjelkovic, Nebojsa; Djuric, Dragan; Iric-Cupic, Violeta; Krkeljic, Jelena; Jakovljevic, Vladimir

    2011-01-01

    Considering the role of von Willebrand factor (vWf) in hemostasis, and the role of oxidative stress in the development of endothelial dysfunction and atherosclerotic disease, the aim of our study was to investigate the relationship between vWf, parameters of oxidative stress and different types of acute coronary syndromes (ACS). Levels of vWf activity (vWfAct), vWf antigen (vWfAg), nitric oxide (estimated through nitrites-NO(2)-), superoxide anion radical (O(2)-), hydrogen peroxide (H2O2), index of lipid peroxidation (estimated through thiobarbituric acid reactive substances-TBARS), superoxide dismutase (SOD) and catalase (CAT) activity of 115 patients were compared with those of 40 healthy controls. ACS patients had significantly higher vWfAct and vWfAg levels, as well as TBARS levels, while their levels of NO(2)-, H2O2, SOD and CAT activities were lower than controls'. vWfAg showed high specificity and sensitivity as a test to reveal healthy or diseased subjects. Multivariant logistic regression marked only vWfAg and TBARS as parameters that were under independent effect of ACS type. The results of our study support the implementation of vWf in clinical rutine and into therapeutic targets, and suggest that ACS patients are in need of antioxidant supplementation to improve their impaired antioxidant defence.

  16. Cortisol response to acute stress in asthma: Moderation by depressive mood.

    Science.gov (United States)

    Trueba, Ana F; Simon, Erica; Auchus, Richard J; Ritz, Thomas

    2016-05-15

    Both individuals with asthma and depression show signs of a dysregulated hypothalamus-pituitary-adrenal axis. However, little is known about the cortisol response to stress in the context of co-occurring asthma and depressive mood. Thirty-nine individuals with asthma and 41 healthy controls underwent a combined speech and mental arithmetic stressor. During the course of the laboratory session, salivary cortisol was collected 5 times, with 1 sample at 0min before the stressor and 4 samples at 0, 15, 30 and 45min after the stressor. Depressive mood in the past week was assessed with the Hospital Anxiety and Depression Scale at the beginning of the session. Depressive symptoms moderated cortisol response to the acute stressor, but only among asthmatic patients. Higher depressive mood was associated with a significant increase in cortisol, whereas low depressive mood was associated with no cortisol response. In healthy participants, depressive mood had no substantial effect on cortisol response to the stressor. These findings suggest that depressive mood and chronic inflammatory diseases such as asthma can interact to augment cortisol response to stress.

  17. Effect of iron supplementation on oxidative stress and intestinal inflammation in rats with acute colitis.

    Science.gov (United States)

    Aghdassi, E; Carrier, J; Cullen, J; Tischler, M; Allard, J P

    2001-05-01

    In this study, we investigated the effect of intraperitoneal iron dextran (100 mg/100 g body weight) on oxidative stress and intestinal inflammation in rats with acute colitis induced by 5% dextran sulfate sodium. In both colitis and healthy animals, disease activity index, crypt and inflammatory scores, colon length, plasma and colonic lipid peroxides, and plasma vitamins E, C, and retinol were assessed. The results showed that iron-supplemented groups had moderate iron deposition in the colonic submucosa and lamina propria. In the colitis group supplemented with iron, colon length was significantly shorter; disease activity index, crypt, and inflammatory scores and colonic lipid peroxides were significantly higher; and plasma alpha-tocopherol was significantly lower compared to the colitis group without iron supplementation. There was no intestinal inflammation and no significant increase in colonic lipid peroxides in healthy rats supplemented with iron. In conclusion, iron injection resulted in an increased oxidative stress and intestinal inflammation in rats with colitis but not in healthy rats. PMID:11341654

  18. Effects of Breaking Sitting by Standing and Acute Exercise on Postprandial Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Takahashi

    2015-09-01

    Full Text Available Background Sedentary behavior, which includes sitting and TV viewing, has been identified as an independent risk factor for type 2 diabetes and cardiovascular disease. Breaking sedentary behavior improves metabolic health such as postprandial glycaemia and insulinemia. However, the mechanisms underlying this effect are unclear. Objectives Here, we examined whether breaking sitting by standing and acute exercise reduces postprandial oxidative stress. Patient and Methods Fifteen participants performed 3 trials (sitting, standing, and exercise, each lasting 2 days, in a randomised order. On day one of sitting trial, participants sat in a chair. For the standing trial, the participants stood 6 times, for a 45-minute period each time. For the exercise trial, the participants walked or ran at approximately 60% of age-predicted maximum heart rate for 30 minutes. On day two of each trial, participants rested and consumed the standardised breakfast and lunch. Blood samples were collected in the morning and afternoon on day one, and fasting and at 2, 4, and 6 hours postprandially on day two. Results The concentrations of serum derivatives of reactive oxygen metabolites (d-ROMs measured at 4 hours (P = 0.064 and 6 hours (P = 0.071 tended to be higher than that in the fasting state in the sitting trial, but not standing and exercise trial (two-factor analysis of variance (ANOVA, trial × time interaction, P = 0.006. Conclusions Our results indicate the importance of reducing sitting time for improving postprandial oxidative stress status.

  19. Ulinastatin suppresses endoplasmic reticulum stress and apoptosis in the hippocampus of rats with acute paraquat poisoning

    Directory of Open Access Journals (Sweden)

    Hai-feng Li

    2015-01-01

    Full Text Available Lung injury is the main manifestation of paraquat poisoning. Few studies have addressed brain damage after paraquat poisoning. Ulinastatin is a protease inhibitor that can effectively stabilize lysosomal membranes, prevent cell damage, and reduce the production of free radicals. This study assumed that ulinastatin would exert these effects on brain tissues that had been poisoned with paraquat. Rat models of paraquat poisoning were intraperitoneally injected with ulinastatin. Simultaneously, rats in the control group were administered normal saline. Hematoxylin-eosin staining showed that most hippocampal cells were contracted and nucleoli had disappeared in the paraquat group. Fewer cells in the hippocampus were concentrated and nucleoli had disappeared in the ulinastatin group. Western blot assay showed that expressions of GRP78 and cleaved-caspase-3 were significantly lower in the ulinastatin group than in the paraquat group. Immunohistochemical findings showed that CHOP immunoreactivity was significantly lower in the ulinastatin group than in the paraquat group. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining showed that the number of apoptotic cells was reduced in the paraquat and ulinastatin groups. These data confirmed that endoplasmic reticular stress can be induced by acute paraquat poisoning. Ulinastatin can effectively inhibit this stress as well as cell apoptosis, thereby exerting a neuroprotective effect.

  20. Acute stress alters amygdala microRNA miR-135a and miR-124 expression: inferences for corticosteroid dependent stress response.

    Directory of Open Access Journals (Sweden)

    Cecilia Mannironi

    Full Text Available The amygdala is a brain structure considered a key node for the regulation of neuroendocrine stress response. Stress-induced response in amygdala is accomplished through neurotransmitter activation and an alteration of gene expression. MicroRNAs (miRNAs are important regulators of gene expression in the nervous system and are very well suited effectors of stress response for their ability to reversibly silence specific mRNAs. In order to study how acute stress affects miRNAs expression in amygdala we analyzed the miRNA profile after two hours of mouse restraint, by microarray analysis and reverse transcription real time PCR. We found that miR-135a and miR-124 were negatively regulated. Among in silico predicted targets we identified the mineralocorticoid receptor (MR as a target of both miR-135a and miR-124. Luciferase experiments and endogenous protein expression analysis upon miRNA upregulation and inhibition allowed us to demonstrate that mir-135a and mir-124 are able to negatively affect the expression of the MR. The increased levels of the amygdala MR protein after two hours of restraint, that we analyzed by western blot, negatively correlate with miR-135a and miR-124 expression. These findings point to a role of miR-135a and miR-124 in acute stress as regulators of the MR, an important effector of early stress response.

  1. Grafting as a tool to improve tolerance of vegetables to abiotic stresses : Thermal stress, water stress and organic pollutants

    NARCIS (Netherlands)

    Schwarz, Dietmar; Rouphael, Youssef; Colla, Giuseppe; Venema, Jan Henk

    2010-01-01

    Due to limited availability of arable land and the high market demand for vegetables around the world, cucurbit (cucumber, melon, and watermelon) and solanaceous (eggplant, pepper and tomato) crops are frequently cultivated under unfavourable soil and environmental conditions. These include thermal

  2. Study of Thermal Stress Influence on Dimensional Stability of Silicone Molds

    Directory of Open Access Journals (Sweden)

    Bajčičák Martin

    2014-06-01

    Full Text Available The paper is focused on the study of temperature influence on dimensional stability of silicone molds used for spin casting of the low melting points alloys. The silicone material denoted as TEKSIL Silicone-GP-S was used to produce samples during experiments. The samples were heated to temperatures in the range from 100 up to 250oC for 30 up to 120 min. Dimensional changes of the samples in the radial and axial directions aa well as their change of weight were evaluated. The results of experiments proved that thermal stress of silicone molds can influence the size and shape of mold cavities. These results can also explain the possible mechanism of degradation process of silicone molds under thermal stress.

  3. Metallurgical characterization and determination of residual stresses of coatings formed by thermal spraying

    Science.gov (United States)

    Laribi, M.; Mesrati, N.; Vannes, A. B.; Treheux, D.

    2003-06-01

    This work presents an experimental determination of residual stresses in 35CrMo4 (Euronorm) low alloyed steel substrates with thermally sprayed coatings. Two different materials were separately deposited. The first one consisted of a blend of two superalloys: Cr-Ni steel and Cr-Mn steel, designated 55E and 65E, respectively. The second material was molybdenum. In a first part, basic characteristics of the deposited layers (metallographic analysis, hardness, and adhesion) are presented. In a second part, the determination of the residual stresses, in both substrate and thermal sprayed layers is performed using an extensometric method in combination with a simultaneous progressive electrolytic polishing. The influence of a nickel-aluminum (80:20%) bond-coat and/or a post-annealing at 850 °C in air for 1 h is studied.

  4. Expression analysis of NOS family and HSP genes during thermal stress in goat ( Capra hircus)

    Science.gov (United States)

    Yadav, Vijay Pratap; Dangi, Satyaveer Singh; Chouhan, Vikrant Singh; Gupta, Mahesh; Dangi, Saroj K.; Singh, Gyanendra; Maurya, Vijay Prakash; Kumar, Puneet; Sarkar, Mihir

    2016-03-01

    Approximately 50 genes other than heat shock protein (HSP) expression changes during thermal stress. These genes like nitric oxide synthase (NOS) need proper attention and investigation to find out their possible role in the adaptation to thermal stress in animals. So, the present study was undertaken to demonstrate the expressions of inducible form type II NOS (iNOS), endothelial type III NOS (eNOS), constitutively expressed enzyme NOS (cNOS), HSP70, and HSP90 in peripheral blood mononuclear cells (PBMCs) during different seasons in Barbari goats. Real-time polymerase chain reaction, western blot, and immunocytochemistry were applied to investigate messenger RNA (mRNA) expression, protein expression, and immunolocalization of examined factors. The mRNA and protein expressions of iNOS, eNOS, cNOS, HSP70, and HSP90 were significantly higher ( P cellular integrity and homeostasis in goats.

  5. Packaging strategies for printed circuit board components. Volume I, materials & thermal stresses.

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Michael K. (Kansas City Plant, Kansas City, MO); Austin, Kevin N.; Adolf, Douglas Brian; Spangler, Scott W.; Neidigk, Matthew Aaron; Chambers, Robert S.

    2011-09-01

    Decisions on material selections for electronics packaging can be quite complicated by the need to balance the criteria to withstand severe impacts yet survive deep thermal cycles intact. Many times, material choices are based on historical precedence perhaps ignorant of whether those initial choices were carefully investigated or whether the requirements on the new component match those of previous units. The goal of this program focuses on developing both increased intuition for generic packaging guidelines and computational methodologies for optimizing packaging in specific components. Initial efforts centered on characterization of classes of materials common to packaging strategies and computational analyses of stresses generated during thermal cycling to identify strengths and weaknesses of various material choices. Future studies will analyze the same example problems incorporating the effects of curing stresses as needed and analyzing dynamic loadings to compare trends with the quasi-static conclusions.

  6. Neuronal and inducible nitric oxide synthase upregulation in the rat medial prefrontal cortex following acute restraint stress: A dataset

    Directory of Open Access Journals (Sweden)

    Jereme G. Spiers

    2016-03-01

    Full Text Available This data article provides additional evidence on gene expression changes in the neuronal and inducible isoforms of nitric oxide synthase in the medial prefrontal cortex following acute stress. Male Wistar rats aged 6–8 weeks were exposed to control or restraint stress conditions for up to four hours in the dark cycle after which the brain was removed and the medial prefrontal cortex isolated by cryodissection. Following RNA extraction and cDNA synthesis, gene expression data were measured using quantitative real-time PCR. The mRNA levels of the neuronal and inducible nitric oxide synthase isoforms, and the inhibitory subunit of NF-κB, I kappa B alpha were determined using the ΔΔCT method relative to control animals. This data article presents complementary results related to the research article entitled ‘Acute restraint stress induces specific changes in nitric oxide production and inflammatory markers in the rat hippocampus and striatum’ [1].

  7. Inflammation and Oxidative Stress in Young and Aged Rats after Acute Homocysteine Administration

    Directory of Open Access Journals (Sweden)

    Cristina-Sorina CĂTANĂ

    2011-06-01

    Full Text Available Introduction: Hyperhomocysteinemia plays an etiologic role in homocystinuria, neurodegenerative and cardiovascular diseases. Potential mechanisms involved in the degenerative diseases of aging include: oxidative stress, endothelial dysfunction and inflammation. Aim: In the present study we evaluated the effect of acute administration of homocysteine (Hcy, at a level similar to that found in homocystinuria, on biochemical markers of inflammation (such as IL-6 and of oxidative stress (such as gluthathione peroxidase - GPx. Material and Method: The study was performed on 40 young and older Wistar rats. IL-6 serum level was quantified by a high-sensitivity enzyme-linked immunoabsorbent assay (ELISA method and the activity of whole blood GPx was measured using a commercially available Randox kit. Results: Our results showed that Hcy administration increased the pro-inflammatory cytokine IL-6 in young rats (p<0.3 and decreased IL-6 level in older rats (p<0.008, when compared to the control group. GPx activity was found to increase with age (587.07 U/gHb versus 847.5 U/gHb, p<0.001. Two hours after Hcy administration, GPx activity was found to decrease, but not in a statistically significant manner. The difference between GPx activities in Hcy treated groups remains statistically significant (p<0.01 in the younger group, compared to older group (556.62 U/gHb versus 748.38 U/gHb. Conclusion: Our results indicate the existence of a correlation between hyperhomocysteinemia, proinflammatory state and oxidative stress, illustrated by the direct dependence of whole blood GPx activities on the increasing age.

  8. Acute maternal stress in pregnancy and schizophrenia in offspring: A cohort prospective study

    Directory of Open Access Journals (Sweden)

    Fennig S

    2008-08-01

    Full Text Available Abstract Schizophrenia has been linked with intrauterine exposure to maternal stress due to bereavement, famine and major disasters. Recent evidence suggests that human vulnerability may be greatest in the first trimester of gestation and rodent experiments suggest sex specificity. We aimed to describe the consequence of an acute maternal stress, through a follow-up of offspring whose mothers were pregnant during the Arab-Israeli war of 1967. A priori, we focused on gestational month and offspring's sex. Method In a pilot study linking birth records to Israel's Psychiatric Registry, we analyzed data from a cohort of 88,829 born in Jerusalem in 1964–76. Proportional hazards models were used to estimate the relative risk (RR of schizophrenia, according to month of birth, gender and other variables, while controlling for father's age and other potential confounders. Other causes of hospitalized psychiatric morbidity (grouped together were analyzed for comparison. Results There was a raised incidence of schizophrenia for those who were in the second month of fetal life in June 1967 (RR = 2.3, 1.1–4.7, seen more in females (4.3, 1.7–10.7 than in males (1.2, 0.4–3.8. Results were not explained by secular or seasonal variations, altered birth weight or gestational age. For other conditions, RRs were increased in offspring who had been in the third month of fetal life in June 1967 (2.5, 1.2–5.2, also seen more in females (3.6, 1.3–9.7 than males (1.8, 0.6–5.2. Conclusion These findings add to a growing literature, in experimental animals and humans, attributing long term consequences for offspring of maternal gestational stress. They suggest both a sex-specificity and a relatively short gestational time-window for gestational effects on vulnerability to schizophrenia.

  9. Intrathecal Clonidine Pump Failure Causing Acute Withdrawal Syndrome With 'Stress-Induced' Cardiomyopathy.

    Science.gov (United States)

    Lee, Hwee Min D; Ruggoo, Varuna; Graudins, Andis

    2016-03-01

    Clonidine is a central alpha(2)-agonist antihypertensive used widely for opioid/alcohol withdrawal, attention deficit hyperactivity disorder and chronic pain management. We describe a case of clonidine withdrawal causing life-threatening hypertensive crisis and stress-induced cardiomyopathy. A 47-year-old man with chronic back pain, treated with clonidine for many years via intrathecal pump (550 mcg/24 h), presented following a collapse and complaining of sudden worsening of back pain, severe headache, diaphoresis, nausea and vomiting. A few hours prior to presentation, his subcutaneous pump malfunctioned. On presentation, vital signs included pulse 100 bpm, BP 176/103 mmHg, temperature 37.8 °C and O2 saturation 100 % (room air). Acute clonidine withdrawal with hypertensive crisis was suspected. Intravenous clonidine loading dose and a 50 mcg/h infusion were commenced. Five hours later, severe chest pain, dyspnoea, tachycardia, hypoxia, with BP 180/120 mmHg and pulmonary edema ensued. ECG showed sinus tachycardia with no ST elevation. Repeated intravenous clonidine doses were given (25 mcg every 5-10 min), with ongoing clonidine infusion to control blood pressure. Glyceryl trinitrate infusion, positive pressure ventilation and intravenous benzodiazepines were added. Bedside echocardiogram showed stress-induced cardiomyopathy pattern. Serum troponin-I was markedly elevated. His coronary angiography showed minor irregularities in the major vessels. Over the next 3 days in the ICU, drug infusions were weaned. Discharge was 12 days later on oral clonidine, metoprolol, perindopril, aspirin and oxycodone-SR. Two months later, his echocardiogram was normal. The intrathecal pump was removed. We report a case of stress-induced cardiomyopathy resulting from the sudden cessation of long-term intrathecal clonidine. This was managed by re-institution of clonidine and targeted organ-specific therapies. PMID:26370679

  10. Cinnamon (Cinnamomum sp.) inclusion in diets for Nile tilapia submitted to acute hypoxic stress.

    Science.gov (United States)

    M Dos Santos, Welliene; S de Brito, Túlio; de A Prado, Samuel; G de Oliveira, Camila; C De Paula, Andréia; C de Melo, Daniela; A P Ribeiro, Paula

    2016-07-01

    The aim of this study was to evaluate the possible effects of diets supplemented with probiotics and different cinnamon levels (powder and essential oil) on immunological parameters of Nile tilapia after being subjected to acute stress by hypoxia. Three hundred and thirty juvenile male tilapia fish (66.08 ± 2.79 g) were distributed in 30 tanks of 100 L capacity (11/cage) with a water recirculation system. The animals were fed for 71 days with diets containing extruded cinnamon powder at different levels (0.5, 1, 1.5, 2%), cinnamon essential oil (0.05, 0.1, 0.15; 0.2%) and probiotics (0.4%), all in triplicate. At the end of the experiment, the fish (200.36 ± 19.88 g) of the different groups were subjected to stress by hypoxia. Hypoxia was achieved by capturing the animals with a net, keeping them out of the water for three minutes, and then sampling the blood 30 min after the procedure to determine the levels of cortisol, glucose, haematocrit, lysozyme, bactericidal index, total protein, and its fractions. The animals kept blood homeostasis after hypoxic stress. Diet supplementation with 0.5% cinnamon powder improved the fish immune response, since it resulted in an increase of 0.5% in γ-globulin level. Administration of 0.15% cinnamon essential oil resulted in an increase of α1 and α2-globulins, which may be reflected in increased lipid content of the carcass and the hepatosomatic index. More studies are necessary to better understand the effects of these additives for fish immunity. PMID:27142937

  11. Degradation Of H.V. Generator Insulation Under Mechanical, Electrical And Thermal Stresses

    OpenAIRE

    Ramu, TS

    1990-01-01

    The paper presents the results of ageing experiments under combined electrical, mechanical (vibration) and thermal stresses on epoxy bonded mica insulation. Actual 11 KV machine coils designed for use in 1 MW rotating machines are used as the specimens. Both diagnostic and destructive tests were carried out to assess the amount of ageing. It was observed that the incremental loss tangent and partial discharge energy per cycle increase monotonically with time of ageing and that the dielectric...

  12. Response of coral assemblages to thermal stress: are bleaching intensity and spatial patterns consistent between events ?

    OpenAIRE

    Penin, L.; Vidal-Dupiol, J.; Adjeroud, Mehdi

    2013-01-01

    Mass bleaching events resulting in coral mortality are among the greatest threats to coral reefs, and are projected to increase in frequency and intensity with global warming. Achieving a better understanding of the consistency of the response of coral assemblages to thermal stress, both spatially and temporally, is essential to determine which reefs are more able to tolerate climate change. We compared variations in spatial and taxonomic patterns between two bleaching events at the scale of ...

  13. Validation of Reef-Scale Thermal Stress Satellite Products for Coral Bleaching Monitoring

    OpenAIRE

    Heron, Scott F.; Lyza Johnston; Gang Liu; Erick F. Geiger; Maynard, Jeffrey A; Jacqueline L. De La Cour; Steven Johnson; Ryan Okano; David Benavente; Timothy F. R. Burgess; John Iguel; Denise I. Perez; Skirving, William J.; Alan E. Strong; Kyle Tirak

    2016-01-01

    Satellite monitoring of thermal stress on coral reefs has become an essential component of reef management practice around the world. A recent development by the U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch (NOAA CRW) program provides daily global monitoring at 5 km resolution—at or near the scale of most coral reefs. In this paper, we introduce two new monitoring products in the CRW Decision Support System for coral reef management: Regional Virtual Stations, a reg...

  14. Numerical Parametric Analysis of Bond Coat Thickness Effect on Residual Stresses in Zirconia-Based Thermal Barrier Coatings

    Science.gov (United States)

    Abbas, Musharaf; Hasham, Hasan Junaid; Baig, Yasir

    2016-02-01

    Numerical-based finite element investigation has been conducted to explain the effect of bond coat thickness on stress distribution in traditional and nanostructured yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBC). Stress components have been determined to quantitatively analyze the mechanical response of both kinds of coatings under the thermal shock effect. It has been found that maximum radial tensile and compressive stresses that exist at thermally grown oxide (TGO)/bond coat interface and within TGO respectively decrease with an increase in bond coat thickness. Effect of bond coat thickness on axial tensile stresses is not significant. However, axial compressive stresses that exist at the edge of the specimen near bond coat/substrate interface decrease appreciably with the increase in bond coat thickness. Residual stress profile as a function of bond coat thickness is further explained for comparative analysis of both coatings to draw some useful conclusions helpful in failure studies of TBCs.

  15. A protocol for analysing thermal stress in insects using infrared thermography.

    Science.gov (United States)

    Gallego, Belén; Verdú, José R; Carrascal, Luis M; Lobo, Jorge M

    2016-02-01

    The study of insect responses to thermal stress has involved a variety of protocols and methodologies that hamper the ability to compare results between studies. For that reason, the development of a protocol to standardize thermal assays is necessary. In this sense, infrared thermography solves some of the problems allowing us to take continuous temperature measurements without handling the individuals, an important fact in cold-blooded organisms like insects. Here, we present a working protocol based on infrared thermography to estimate both cold and heat thermal stress in insects. We analyse both the change in the body temperature of individuals and their behavioural response. In addition, we used partial least squares regression for the statistical analysis of our data, a technique that solves the problem of having a large number of variables and few individuals, allowing us to work with rare or endemic species. To test our protocol, we chose two species of congeneric, narrowly distributed dung beetles that are endemic to the southeastern part of the Iberian Peninsula. With our protocol we have obtained five variables in the response to cold and twelve in the response to heat. With this methodology we discriminate between the two flightless species of Jekelius through their thermal response. In response to cold, Jekelius hernandezi showed a higher rate of cooling and reached higher temperatures of stupor and haemolymph freezing than Jekelius punctatolineatus. Both species displayed similar thermoregulation ranges before reaching lethal body temperature with heat stress. Overall, we have demonstrated that infrared thermography is a suitable method to assess insect thermal responses with a high degree of sensitivity, allowing for the discrimination between closely related species. PMID:26857985

  16. Deterioration of the ornamental stones from Apulia (SE Italy) caused by thermal stresses

    Science.gov (United States)

    Andriani, G. F.; Germinario, L.

    2012-04-01

    Mesozoic carbonate rocks cropping out in Apulia, SE Italy, represent today, as in the past, a fundamental artistic and communicative mean for the local culture. For their physico-mechanical and aesthetic properties, these sedimentary rocks have always found a large application both as ornamental stones and as simple construction materials, particurarly in military architecture and worship buildings during the Middle Ages. The Apulian "marbles" are characterised by high strength and durability, nevertheless outdoors exposure often involves significant changes in their technical properties and state of conservation caused by weathering. The effects of thermal stresses on the material performances, due to diurnal and seasonal temperature fluctuations, constitute a topic of particular interest in the assessment of durability problems associated to long-term exposure. In this work, a study about changes in technical properties of the Apulian ornamental limestones and dolostones induced by thermal stresses is presented. Direct and indirect evaluations concerning index properties, mechanical strength, deformability, textural characteristics and chromatic features, on samples subjected to thermal cycles, were used for providing a comprehensive perspective about deterioration, from the mesoscopic scale to the microscopic one. In a muffle fornace, the samples were subjected to thermal cycles ranging from 100 to 700°C. At the end of each cycle, mass and volume determinations, mercury porosimetry measurements, sclerometric tests, ultrasonic tests, thin section observations and chromatic evaluations through image analysis and Munsell charts were performed. The proposed methodology took into account only non-destructive or semi-destructive tests, in order to highlight the qualitative and quantitative characteristics of decay related to thermal stresses exclusively. In this way a constant comparison among the results of different experimental tests was carried out.

  17. Serum leptin and cortisol, related to acutely perceived academic examination stress and performance in female university students.

    Science.gov (United States)

    Haleem, Darakhshan J; Inam, Qurrat-Ul-Aen; Haider, Saida; Perveen, Tahira; Haleem, Muhammad Abdul

    2015-12-01

    Leptin, identified as an antiobesity hormone, also has important role in responses to stress and processing of memory. This study was designed to determine effects of academic examination stress-induced changes in serum leptin and its impact on academic performance. Eighty five healthy female students (age 19-21 years; BMI 21.9 ± 1.6) were recruited for the study. Serum leptin and cortisol were monitored at base line (beginning of academic session) and on the day of examination; using a standardized ELISA kit. Acute perception of academic examination stress was determined with the help of a questionnaire derived from Hamilton Anxiety Scale and self report of stress perception. Academic performance was evaluated by the percentage of marks obtained in the examination. Serum cortisol levels were positively correlated (p < 0.01) with the subjective perception of examination stress but not with academic performance. There was an inverted U-shape relationship between level of stress and academic performance. Leptin increased in all stress groups and correlated (p < 0.01) positively with academic performance. There was an inverted U-shape relationship between level of stress and circulating leptin. The findings suggest the peptide hormone, leptin, is a biomarker of stress perception and a mediator of facilitating effects of stress on cognition. PMID:26187200

  18. Serum leptin and cortisol, related to acutely perceived academic examination stress and performance in female university students.

    Science.gov (United States)

    Haleem, Darakhshan J; Inam, Qurrat-Ul-Aen; Haider, Saida; Perveen, Tahira; Haleem, Muhammad Abdul

    2015-12-01

    Leptin, identified as an antiobesity hormone, also has important role in responses to stress and processing of memory. This study was designed to determine effects of academic examination stress-induced changes in serum leptin and its impact on academic performance. Eighty five healthy female students (age 19-21 years; BMI 21.9 ± 1.6) were recruited for the study. Serum leptin and cortisol were monitored at base line (beginning of academic session) and on the day of examination; using a standardized ELISA kit. Acute perception of academic examination stress was determined with the help of a questionnaire derived from Hamilton Anxiety Scale and self report of stress perception. Academic performance was evaluated by the percentage of marks obtained in the examination. Serum cortisol levels were positively correlated (p stress but not with academic performance. There was an inverted U-shape relationship between level of stress and academic performance. Leptin increased in all stress groups and correlated (p stress and circulating leptin. The findings suggest the peptide hormone, leptin, is a biomarker of stress perception and a mediator of facilitating effects of stress on cognition.

  19. Thermal Stress-Induced Depolarization Loss in Conventional and Panda-Shaped Photonic Crystal Fiber Lasers

    Science.gov (United States)

    Mousavi, Seyedeh Laleh; Sabaeian, Mohammad

    2016-10-01

    We report on the modeling of the depolarization loss in the conventional and panda-shaped photonic crystal fiber lasers (PCFLs) due to the self-heating of the fiber, which we call it thermal stress-induced depolarization loss (TSIDL). We first calculated the temperature distribution over the fiber cross sections and then calculated the thermal stresses/strains as a function of heat load per meter. Thermal stress-induced birefringence (TSIB), which is defined as | n x - n y |, in the core and cladding regions was calculated. Finally, TSIDL was calculated for the conventional and panda-shaped PCFLs as a function of fiber length and, respectively, saturated values of 22 and 25 % were obtained which were independent of heat load per meter. For panda-shaped PCFLs, prior to being saturated, an oscillating and damping behavior against the fiber length was seen where in some lengths reached 35 %. The results are close to an experimental value of 30 % reported for a pulsed PCFL (Limpert et al., Opt Express 12:1313-1319, 2004) where the authors reported a degree of polarization of 70 % (i.e., a depolarization of 30 %). The most important result of this work is a saturation behavior of TSIDL at long-enough lengths of the fiber laser which is independent of heat load per meter. To our knowledge, this the first report of TSIBL for PCFLs.

  20. Expression analysis of NOS family and HSP genes during thermal stress in goat (Capra hircus).

    Science.gov (United States)

    Yadav, Vijay Pratap; Dangi, Satyaveer Singh; Chouhan, Vikrant Singh; Gupta, Mahesh; Dangi, Saroj K; Singh, Gyanendra; Maurya, Vijay Prakash; Kumar, Puneet; Sarkar, Mihir

    2016-03-01

    Approximately 50 genes other than heat shock protein (HSP) expression changes during thermal stress. These genes like nitric oxide synthase (NOS) need proper attention and investigation to find out their possible role in the adaptation to thermal stress in animals. So, the present study was undertaken to demonstrate the expressions of inducible form type II NOS (iNOS), endothelial type III NOS (eNOS), constitutively expressed enzyme NOS (cNOS), HSP70, and HSP90 in peripheral blood mononuclear cells (PBMCs) during different seasons in Barbari goats. Real-time polymerase chain reaction, western blot, and immunocytochemistry were applied to investigate messenger RNA (mRNA) expression, protein expression, and immunolocalization of examined factors. The mRNA and protein expressions of iNOS, eNOS, cNOS, HSP70, and HSP90 were significantly higher (P P < 0.05) during peak winter season as compared with moderate season. The iNOS, eNOS, cNOS, HSP70, and HSP90 were mainly localized in plasma membrane and cytoplasm of PBMCs. To conclude, data generated in the present study indicate the possible involvement of the NOS family genes in amelioration of thermal stress so as to maintain cellular integrity and homeostasis in goats. PMID:26205811

  1. Thermal Stress-Induced Depolarization Loss in Conventional and Panda-Shaped Photonic Crystal Fiber Lasers

    Science.gov (United States)

    Mousavi, Seyedeh Laleh; Sabaeian, Mohammad

    2016-07-01

    We report on the modeling of the depolarization loss in the conventional and panda-shaped photonic crystal fiber lasers (PCFLs) due to the self-heating of the fiber, which we call it thermal stress-induced depolarization loss (TSIDL). We first calculated the temperature distribution over the fiber cross sections and then calculated the thermal stresses/strains as a function of heat load per meter. Thermal stress-induced birefringence (TSIB), which is defined as |n x - n y |, in the core and cladding regions was calculated. Finally, TSIDL was calculated for the conventional and panda-shaped PCFLs as a function of fiber length and, respectively, saturated values of 22 and 25 % were obtained which were independent of heat load per meter. For panda-shaped PCFLs, prior to being saturated, an oscillating and damping behavior against the fiber length was seen where in some lengths reached 35 %. The results are close to an experimental value of 30 % reported for a pulsed PCFL (Limpert et al., Opt Express 12:1313-1319, 2004) where the authors reported a degree of polarization of 70 % (i.e., a depolarization of 30 %). The most important result of this work is a saturation behavior of TSIDL at long-enough lengths of the fiber laser which is independent of heat load per meter. To our knowledge, this the first report of TSIBL for PCFLs.

  2. Expression analysis of NOS family and HSP genes during thermal stress in goat ( Capra hircus)

    Science.gov (United States)

    Yadav, Vijay Pratap; Dangi, Satyaveer Singh; Chouhan, Vikrant Singh; Gupta, Mahesh; Dangi, Saroj K.; Singh, Gyanendra; Maurya, Vijay Prakash; Kumar, Puneet; Sarkar, Mihir

    2016-03-01

    Approximately 50 genes other than heat shock protein (HSP) expression changes during thermal stress. These genes like nitric oxide synthase (NOS) need proper attention and investigation to find out their possible role in the adaptation to thermal stress in animals. So, the present study was undertaken to demonstrate the expressions of inducible form type II NOS (iNOS), endothelial type III NOS (eNOS), constitutively expressed enzyme NOS (cNOS), HSP70, and HSP90 in peripheral blood mononuclear cells (PBMCs) during different seasons in Barbari goats. Real-time polymerase chain reaction, western blot, and immunocytochemistry were applied to investigate messenger RNA (mRNA) expression, protein expression, and immunolocalization of examined factors. The mRNA and protein expressions of iNOS, eNOS, cNOS, HSP70, and HSP90 were significantly higher ( P < 0.05) during peak summer, and iNOS and eNOS expressions were also observed to be significantly higher ( P < 0.05) during peak winter season as compared with moderate season. The iNOS, eNOS, cNOS, HSP70, and HSP90 were mainly localized in plasma membrane and cytoplasm of PBMCs. To conclude, data generated in the present study indicate the possible involvement of the NOS family genes in amelioration of thermal stress so as to maintain cellular integrity and homeostasis in goats.

  3. Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

    Institute of Scientific and Technical Information of China (English)

    Baoguo CHEN; Rui DING; Junjie ZHENG; Shibiao ZHANG

    2009-01-01

    A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and stow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.

  4. Reciprocal relationship between acute stress and acute fatigue in everyday life in a sample of university students.

    Science.gov (United States)

    Doerr, Johanna M; Ditzen, Beate; Strahler, Jana; Linnemann, Alexandra; Ziemek, Jannis; Skoluda, Nadine; Hoppmann, Christiane A; Nater, Urs M

    2015-09-01

    We investigated whether stress may influence fatigue, or vice versa, as well as factors mediating this relationship. Fifty healthy participants (31 females, 23.6±3.2 years) completed up to 5 momentary assessments of stress and fatigue during 5 days of preparation for their final examinations (exam condition) and 5 days of a regular semester week (control condition). Sleep quality was measured by self-report at awakening. A sub-group of participants (n=25) also collected saliva samples. Fatigue was associated with concurrent stress, stress reported at the previous measurement point, and previous-day stress. However, momentary stress was also predicted by concurrent fatigue, fatigue at the previous time point, and previous-day fatigue. Sleep quality mediated the association between stress and next-day fatigue. Cortisol and alpha-amylase did not mediate the stress-fatigue relationship. In conclusion, there is a reciprocal stress-fatigue relationship. Both prevention and intervention programs should comprehensively cover how stress and fatigue might influence one another. PMID:26143479

  5. Modeling and experimental verification of thermally induced residual stress in RF-MEMS

    International Nuclear Information System (INIS)

    Electrostatically actuated radio frequency microelectromechanical systems (RF-MEMS) generally consist of microcantilevers and clamped–clamped microbeams. The presence of residual stress in these microstructures affects the static and dynamic behavior of the device. In this study, nonlinear finite element method (FEM) modeling and the experimental validation of residual stress induced in the clamped–clamped microbeams and the symmetric toggle RF-MEMS switch (STS) is presented. The formation of residual stress due to plastic deformation during the thermal loading-unloading cycle in the plasma etching step of the microfabrication process is explained and modeled using the Bauschinger effect. The difference between the designed and the measured natural frequency and pull-in voltage values for the clamped–clamped microbeams is explained by the presence of the nonhomogenous tensile residual stress. For the STS switch specimens, three-dimensional (3D) FEM models are developed and the initial deflection at zero bias voltage, observed during the optical profile measurements, is explained by the residual stress developed during the plasma etching step. The simulated residual stress due to the plastic deformation is included in the STS models to obtain the switch pull-in voltage. At the end of the simulation process, a good correspondence is obtained between the FEM model results and the experimental measurements for both the clamped–clamped microbeams and the STS switch specimens. (paper)

  6. Direct and correlated effects of selection on flight after exposure to thermal stress in Drosophila melanogaster.

    Science.gov (United States)

    Krebs, Robert A; Thompson, Kimberly A

    2006-01-01

    To demonstrate how insects may adapt to ecologically relevant levels of heat stress, we performed artificial selection on the ability of Drosophila melanogaster to fly after an exposure to a high but non-lethal thermal stress. Both tolerance and intolerance to heat stress arose very quickly, as only a few generations of selection were necessary to cause significant separation between high and low lines for heat tolerance. Estimates of heritability based on the lines artificially selected for increased flight ability ranged from 0.024 to 0.052, while estimates of heritability based on the lines selected for the inability to fly after heat stress varied between 0.035 and 0.091. Reciprocal F1 crosses among these lines revealed strong additive effects of one or more autosomes and a weaker X-chromosome effect. This variation apparently affected flight specifically; neither survival to a more extreme stress nor knockdown by high temperature changed between lines selected for high and low heat tolerance as measured by flight ability. As the well-studied heat-shock response is associated with heat tolerance as measured by survival and knockdown, the aspects of the stress physiology that actually affect flight ability remains unknown.

  7. Acute physiological stress down-regulates mRNA expressions of growth-related genes in coho salmon.

    Directory of Open Access Journals (Sweden)

    Toshiki Nakano

    Full Text Available Growth and development in fish are regulated to a major extent by growth-related factors, such as liver-derived insulin-like growth factor (IGF -1 in response to pituitary-secreted growth hormone (GH binding to the GH receptor (GHR. Here, we report on the changes in the expressions of gh, ghr, and igf1 genes and the circulating levels of GH and IGF-1 proteins in juvenile coho salmon (Oncorhynchus kisutch in response to handling as an acute physiological stressor. Plasma GH levels were not significantly different between stressed fish and prestressed control. Plasma IGF-1 concentrations in stressed fish 1.5 h post-stress were the same as in control fish, but levels in stressed fish decreased significantly 16 h post-stress. Real-time quantitative PCR (qPCR analysis showed that ghr mRNA levels in pituitary, liver, and muscle decreased gradually in response to the stressor. After exposure to stress, hepatic igf1 expression transiently increased, whereas levels decreased 16 h post-stress. On the other hand, the pituitary gh mRNA level did not change in response to the stressor. These observations indicate that expression of gh, ghr, and igf1 responded differently to stress. Our results show that acute physiological stress can mainly down-regulate the expressions of growth-related genes in coho salmon in vivo. This study also suggests that a relationship between the neuroendocrine stress response and growth-related factors exists in fish.

  8. THERMAL STRESS FIELD WHEN CRACK ARREST IN AN AXIAL SYMMETRY METAL DIE USING ELECTROMAGNETIC HEATING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to solve the thermal stress field around crack tip in metal die when crack prevention using electromagnetic heating, a metal die with a half-embedded round crack was selected as the study object. The complex function method was used as a basis for the theoretical model of the space crack prevention in metal dies using electromagnetic heating. The crack arrest was accomplished by a pulse current discharge through the inner and outer. The theoretical analysis results show that the temperature around the crack tip rises instantly above the melting point of the metal. Small welded joints are formed at a small sphere near the crack tip inside the metal die by metal melting as a result of the heat concentration effect when the current pulse discharged. The thermal compressive stress field appears around the crack tip at the moment. The research results show that the crack prevention using electromagnetic heating can decrease the stress concentration and forms a compressive stress area around the crack tip, and also prevents the main crack from propagating further, and the goal of crack preventing can be reached.

  9. Impact of Thermal Stresses on Wellbore Integrity during CO2 Injection

    Science.gov (United States)

    Roy, P.; Walsh, S.; Morris, J.; Carroll, S.; Hao, Y.; Iyer, J.; Torsater, M.; Gawel, K.; Todorovic, J.

    2015-12-01

    Thermal stresses caused by injection of cold CO2 into warmer storage reservoirs could create leakage pathways out of the storage reservoir. Although few studies have been conducted to investigate the well bore integrity subjected to thermal cycling during CO2injection, a systematic investigation on thermally induced expansion and contraction affecting the debonding and cracking of the well barrier materials has not yet been performed. In this work, we have analyzed the thermo-mechanical characteristics of the well barrier materials undergoing repeated thermal cycling using a multiscale, multiphysics platform named GEOS. More specifically, we model the modes of failure during thermal cycling to assess the temperature range for minimal impact on well integrity. A finite element solver was used for the geomechanics and a finite volume solver was used for the thermal diffusion. Results of the initiation and propagation of fractures due to temperature variations in the cement sheath are presented. Preliminary results suggest that radial fracture develops as the cement is heated while debonding occurs in the casing-cement and cement-rock interfaces during the cooling period. The effects of different confinement conditions based on in-situ stresses were also analyzed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under the Contract DE-AC52-07NA27344. This work has been produced with support from the BIGCCS Centre, performed under the Norwegian research program Centres for Environment-friendly Energy Research (FME) and the KPN project "Ensuring well integrity during CO2 injection". The authors acknowledge the following partners for their contributions: Gassco, Shell, Statoil, TOTAL, GDF SUEZ and the Research Council of Norway (193816/S60 and 23389).

  10. Thermal infrared as a tool to detect tree water stress in a coniferous forest

    Science.gov (United States)

    Nourtier, M.; Chanzy, A.; Bes, B.; Davi, H.; Hanocq, J. F.; Mariotte, N.; Sappe, G.

    2009-04-01

    In the context of climatic change, species area may move and so, a study of forest species vulnerability is on interest. In Mediterranean regions, trees can suffer of water stress due to drought during summer. Responses to environmental constraints are delayed in forest so it is necessary to anticipate risks in order to adapt management. It would be therefore interesting to localize areas where trees might be vulnerable to water stress. To detect such areas, the idea developed in this study is to map the severity of water stress, which may be linked to soil. Because vegetation surface temperature is linked to transpiration and so to water stress, the relevance of thermal infrared as a tool to detect water stress was explored. Past studies about surface temperature of forests at the planting scale did not lead to conclusive results. At this scale, important spatial and temporal variations of surface temperature, with a magnitude of about 10°C, can be registered but there is possibly a sizeable contribution of the undergrowth (Duchemin, 1998a, 1998b). In the other hand, important stress are not detectable, probably due to meteorological conditions (Pierce et al., 1990). During spring and summer 2008, an experimentation was carried out on the silver fir (Abies alba) forest of Mont Ventoux (south of France) to evaluate temporal variations at tree scale of the surface temperature in relation to water stress and climatic conditions. Two sites and three trees were chosen for measurements of surface temperature with a view to have different levels of water stress. Transpiration deficit is characterised by the ratio of actual transpiration to potential transpiration which is computed by the ISBA model (Noilhan et al., 1989) implemented by climatic observations made at the top of tree canopy. Sap flow measurements needed to calculate this ratio were completed on different trees of the sites. Climatic datas also allows building reference temperature and then surface

  11. Thermal stress characterization using the impedance-based structural health monitoring system

    Science.gov (United States)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2016-04-01

    Structural health monitoring (SHM) has attracted researchers' interests for the past two decades to reinforce the maintenance of the aging infrastructure systems all over the world. As one of the potential solutions, the electro-mechanical impedance (EMI) method was introduced in the early 1990s and has a great number of potential applications in the SHM of civil, mechanical and aerospace industries. This paper studied the impedance-based technique with the presence of environmental/operational variability, especially the influences of temperature and uniaxial stress on the admittance signature-based features. A comprehensive analytical model is established and provides satisfactory agreements with the experimental results. The stress and temperature sensitivities of all the proposed features are quantified using the experimental measurements, with discussions on their advantages and disadvantages. The final results illustrate that the EMI method can potentially provide effective measure for thermal stress.

  12. Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

    OpenAIRE

    Lin, Qiao; Jiang, Fukang; Wang, Xuan-Qi; Xu, Yong; Han, Zhigang; Tai, Yu-Chong; Lew, James; Ho, Chih-Ming

    2004-01-01

    MEMS thermal shear-stress sensors exploit heat-transfer effects to measure the shear stress exerted by an air flow on its solid boundary, and have promising applications in aerodynamic control. Classical theory for conventional, macroscale thermal shear-stress sensors states that the rate of heat removed by the flow from the sensor is proportional to the 1/3-power of the shear stress. However, we have observed that this theory is inconsistent with experimental data from MEMS sensors. This pap...

  13. Acute hematopoietic stress in mice is followed by enhanced osteoclast maturation in the bone marrow microenvironment.

    Science.gov (United States)

    Kuzmac, Sania; Grcevic, Danka; Sucur, Alan; Ivcevic, Sanja; Katavic, Vedran

    2014-11-01

    Osteoclasts are components of hematopoietic stem cell (HSC) niches, but their role as contributors to the HSC homeostasis and release are still controversial. We aimed to investigate whether an acute blood loss of 10% of total blood content, along with the consequent intense hematopoiesis, would affect osteoclast differentiation and activity. Isolated peripheral blood, spleen, and bone marrow (BM) cells from bones of hind limbs were investigated for the presence of specific subpopulations of osteoclast precursors: B220(-)CD3(-)NK1.1(-)CD11b(-/low)CD115(+)CD117(+) cells in BM, and B220(-)CD3(-)NK1.1(-)Gr-1(-)CD11b(+)CD115(+) cells in peripheral blood and spleen as well as the receptor activator of nuclear factor κ-B(+) cycle-arrested quiescent osteoclast precursors. Expression of osteoclastogenesis-related genes CD115, receptor activator of nuclear factor κ-B, and cathepsin K, the potential of BM cells to form osteoclast-like cells in vitro, and osteoclast activity in vivo were also evaluated. We observed an increase in spleen cellularity and myelopoiesis during week 1 following blood loss, without any significant effects on BM cellularity or BM myeloid precursors, including cells with high osteoclastogenic potential. However, at 1 week postbleeding, hematopoiesis significantly promoted the expression of cathepsin K, interleukin-34, and bone morphogenetic protein-6. Quiescent osteoclast precursors increased significantly in spleen 2 days following bleeding, whereas osteoclast activity remained unchanged up to 2 weeks postbleeding. Osteoclast-dependent B-cell differentiation was affected at the pre-B stage of maturation in BM, whereas the Lin(-)Sca-1(+)c-kit(+) population expanded in BM and spleen after 2 days postbleeding. Our data demonstrate that an acute blood loss promotes differentiation and maturation of osteoclasts at 1 week but does not enhance osteoresorption at 2 weeks postbleeding. Our data also identify osteoclast differentiation as a consequent and

  14. The acute glucocorticoid stress response does not differentiate between rewarding and aversive social stimuli in rats.

    Science.gov (United States)

    Buwalda, Bauke; Scholte, Jan; de Boer, Sietse F; Coppens, Caroline M; Koolhaas, Jaap M

    2012-02-01

    The mere presence of elevated plasma levels of corticosterone is generally regarded as evidence of compromised well-being. However, environmental stimuli do not necessarily need to be of a noxious or adverse nature to elicit activation of the stress response systems. In the present study, the physiological and neuroendocrine responses to repeated social stimuli that can be regarded as emotional opposites, i.e. social defeat and sexual behavior, were compared. Similar corticosterone responses were observed in animals confronted for the first time with either a highly aggressive male intruder or a receptive female, but a decrease was noticed in defeated rats tested during a third interaction. Only if animals are being physically attacked does the corticosterone response remain similar to the one observed during sexual behavior. In addition, the number of activated cells in the parvocellular hypothalamic paraventricular nucleus, as visualized by c-Fos immunocytochemistry, shows no difference between rats 1h after the third exposure to defeat or sex. Finally, biotelemetric recordings of heart rate, body temperature and locomotor activity show a robust response to both social stimuli that is generally, however, higher in animals being confronted with a receptive female. The data clearly indicate that acute plasma corticosterone levels are not reflecting the emotional valence of a salient stimulus. The magnitude of the response seems to be a direct reflection of the behavioral activity and hence of the metabolic requirements of activated tissues. Next to its direct metabolic role, acute increases in plasma corticosterone will have neurobiological and behavioral effects that largely depend on the neural circuitry that is activated by the stimulus that triggered its release. PMID:22210197

  15. Role for leptin in promoting glucose mobilization during acute hyperosmotic stress in teleost fishes.

    Science.gov (United States)

    Baltzegar, David A; Reading, Benjamin J; Douros, Jonathon D; Borski, Russell J

    2014-01-01

    Osmoregulation is critical for survival in all vertebrates, yet the endocrine regulation of this metabolically expensive process is not fully understood. Specifically, the function of leptin in the regulation of energy expenditure in fishes, and among ectotherms, in general, remains unresolved. In this study, we examined the effects of acute salinity transfer (72  h) and the effects of leptin and cortisol on plasma metabolites and hepatic energy reserves in the euryhaline fish, the tilapia (Oreochromis mossambicus). Transfer to 2/3 seawater (23  ppt) significantly increased plasma glucose, amino acid, and lactate levels relative to those in the control fish. Plasma glucose levels were positively correlated with amino acid levels (R2=0.614), but not with lactate levels. The mRNA expression of liver leptin A (lepa), leptin receptor (lepr), and hormone-sensitive and lipoprotein lipases (hsl and lpl) as well as triglyceride content increased during salinity transfer, but plasma free fatty acid and triglyceride levels remained unchanged. Both leptin and cortisol significantly increased plasma glucose levels in vivo, but only leptin decreased liver glycogen levels. Leptin decreased the expression of liver hsl and lpl mRNAs, whereas cortisol significantly increased the expression of these lipases. These findings suggest that hepatic glucose mobilization into the blood following an acute salinity challenge involves both glycogenolysis, induced by leptin, and subsequent gluconeogenesis of free amino acids. This is the first study to report that teleost leptin A has actions that are functionally distinct from those described in mammals acting as a potent hyperglycemic factor during osmotic stress, possibly in synergism with cortisol. These results suggest that the function of leptin may have diverged during the evolution of vertebrates, possibly reflecting differences in metabolic regulation between poikilotherms and homeotherms. PMID:24194509

  16. Upper temperature tolerance of loach minnow under acute, chronic, and fluctuating thermal regimes

    Science.gov (United States)

    Widmer, A.M.; Carveth, C.J.; Bonar, Scott A.; Simms, J.R.

    2006-01-01

    We used four methods to estimate the upper lethal temperature of loach minnow Rhinichthys cobitis: the lethal thermal method (LTM), chronic lethal method (CLM), acclimated chronic exposure (ACE) method with static temperatures, and ACE method with diel temperature fluctuations. The upper lethal temperature of this species ranged between 32??C and 38??C, depending on the method and exposure time; however, temperatures as low as 28??C resulted in slowed growth compared with the control groups. In LTM trials, we increased temperatures 0.3??C/min and death occurred at 36.8 ?? 0.2??C (mean ?? SE) for fish (37-19 mm total length) acclimated to 30??C and at 36.4 ?? 0.07??C for fish acclimated to 25??C. In CLM trials, temperatures were increased more slowly (1??C/d), allowing fish to acclimate. Mean temperature at death was 33.4 ?? 0.1??C for fish 25-35 mm and 32.9 ?? 0.4??C for fish 45-50 mm. In the ACE experiment with static temperatures, we exposed fish for 30 d to four constant temperatures. No fish (20-40 mm) survived beyond 30 d at 32??C and the 30-d temperature lethal to 50% of the test animals was 30.6??C. Growth at static 28??C and 30??C was slower than growth at 25??C, suggesting that fish were stressed at sublethal temperatures. In ACE trials with diel temperature fluctuations of 4,6, and 10??C and a 32??C peak temperature, over 80% of fish (20-40 mm) survived 30 d. Although brief exposures to 32??C were not lethal, the growth of fish in the three fluctuating-temperature treatments was significantly less than the growth at the ambient temperature (25-29??C). To minimize thermal stress and buffer against temperature spikes, we recommend that loach minnow habitat be managed to avoid water temperatures above 28??C. ?? Copyright by the American Fisheries Society 2006.

  17. The implicit Power Motive and Adolescents' Salivary Cortisol Responses to Acute Psychosocial Stress and Exercise in School.

    Science.gov (United States)

    Wegner, Mirko; Schüler, Julia; Scheuermann, Katharina S; Machado, Sergio; Budde, Henning

    2015-01-01

    In the present study we examined the moderating effect of the power motive on salivary cortisol responses to acute psychosocial stress and exercise in adolescents. Fifty-seven high school students aged M = 14.8 years participated in the study. The Operant Motive Test was applied to measure the implicit power motive and the Personality Research Form was used to measure the explicit power motive. Salivary cortisol levels were assessed before and after the stress stimuli. Participants were randomly assigned to three experimental groups. An exercise group ran 15 minutes at a defined heart rate of 65-75% HRmax. A psychosocial stress group worked on a standard intelligence test for the same amount of time under the assumption, that their test scores will be made public in class after the test. The control group participated in a regular class session. The implicit power motive was significantly associated with increased cortisol levels in the psychosocial stress group. The explicit power motive was not associated with cortisol responses. Findings suggest that the implicit power motive moderates the cortisol responses to acute stress in an adolescent age group with higher responses to psychosocial stress in comparison to exercise or control conditions.

  18. Association between exposure to environmental tobacco smoke and biomarkers of oxidative stress among patients hospitalised with acute myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Ian L Megson

    Full Text Available OBJECTIVE: To determine whether exposure to environmental tobacco smoke was associated with oxidative stress among patients hospitalised for acute myocardial infarction. DESIGN: An existing cohort study of 1,261 patients hospitalised for acute myocardial infarction. SETTING: Nine acute hospitals in Scotland. PARTICIPANTS: Sixty never smokers who had been exposed to environmental tobacco smoke (admission serum cotinine ≥3.0 ng/mL were compared with 60 never smokers who had not (admission serum cotinine ≤0.1 ng/mL. INTERVENTION: None. MAIN OUTCOME MEASURES: Three biomarkers of oxidative stress (protein carbonyl, malondialdehyde (MDA and oxidised low-density lipoprotein (ox-LDL were measured on admission blood samples and adjusted for potential confounders. RESULTS: After adjusting for baseline differences in age, sex and socioeconomic status, exposure to environmental tobacco smoke was associated with serum concentrations of both protein carbonyl (beta coefficient 7.96, 95% CI 0.76, 15.17, p = 0.031 and MDA (beta coefficient 10.57, 95% CI 4.32, 16.81, p = 0.001 but not ox-LDL (beta coefficient 2.14, 95% CI -8.94, 13.21, p = 0.703. CONCLUSIONS: Exposure to environmental tobacco smoke was associated with increased oxidative stress. Further studies are requires to explore the role of oxidative stress in the association between environmental tobacco smoke and myocardial infarction.

  19. Greater Heart Rate Responses to Acute Stress Are Associated with Better Post-Error Adjustment in Special Police Cadets.

    Science.gov (United States)

    Yao, Zhuxi; Yuan, Yi; Buchanan, Tony W; Zhang, Kan; Zhang, Liang; Wu, Jianhui

    2016-01-01

    High-stress jobs require both appropriate physiological regulation and behavioral adjustment to meet the demands of emergencies. Here, we investigated the relationship between the autonomic stress response and behavioral adjustment after errors in special police cadets. Sixty-eight healthy male special police cadets were randomly assigned to perform a first-time walk on an aerial rope bridge to induce stress responses or a walk on a cushion on the ground serving as a control condition. Subsequently, the participants completed a Go/No-go task to assess behavioral adjustment after false alarm responses. Heart rate measurements and subjective reports confirmed that stress responses were successfully elicited by the aerial rope bridge task in the stress group. In addition, greater heart rate increases during the rope bridge task were positively correlated with post-error slowing and had a trend of negative correlation with post-error miss rate increase in the subsequent Go/No-go task. These results suggested that stronger autonomic stress responses are related to better post-error adjustment under acute stress in this highly selected population and demonstrate that, under certain conditions, individuals with high-stress jobs might show cognitive benefits from a stronger physiological stress response. PMID:27428280

  20. Changes in thermal infrared spectra of plants caused by temperature and water stress

    Science.gov (United States)

    Buitrago, Maria F.; Groen, Thomas A.; Hecker, Christoph A.; Skidmore, Andrew K.

    2016-01-01

    Environmental stress causes changes in leaves and the structure of plants. Although physiological adaptations to stress by plants have been explored, the effect of stress on the spectral properties in the thermal part of the electromagnetic spectrum (3-16 μm) has not yet been investigated. In this research two plant species (European beech, Fagus sylvatica and rhododendron, Rhododendron cf. catawbiense) that both grow naturally under temperature limited conditions were selected, representing deciduous and evergreen plants respectively. Besides TIR spectra, Leaf Water Content (LWC) and cuticle thickness were measured as possible variables that can explain the changes in TIR spectra. The results demonstrated that both species, when exposed to either water or temperature stress, showed significant changes in their TIR spectra. The changes in TIR in response to stress were similar within a species, regardless of the stress imposed on them. However, changes in TIR spectra differed between species. For rhododendron emissivity in TIR increased under stress while for beech it decreased. Both species showed depletion of Leaf Water Content (LWC) under stress, ruling LWC out as a main cause for the change in the TIR spectra. Cuticle thickness remained constant for beech, but increased for rhododendron. This suggests that changes in emissivity may be linked to changes in the cuticle thickness and possibly the structure of cuticle. It is known that spectral changes in this region have a close connection with microstructure and biochemistry of leaves. We propose detailed measurements of these changes in the cuticle to analyze the effect of microstructure on TIR spectra.