Статті в журналах: "High-Intensity stress"

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Mat Ludin, Arimi Fitri. "The Effects of High Intensity Progressive Resistance Training on Psychological Stress and Biochemicals Parameters." Jurnal Sains Kesihatan Malaysia 13, no. 2 (2015): 53–60. http://dx.doi.org/10.17576/jskm-2015-13(2)6.

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Bhosle, Sanika Gajanan, Vishnu Vardhan, and Aashirwad Mahajan. "EFFECT OF HIGH INTENSITY INTERVAL TRAINING WITH THE USE OF TRAMPOLINE IN INDIVIDUALS WITH STRESS." International Journal of Physiotherapy and Research 6, no. 6 (November 1, 2018): 2899–904. http://dx.doi.org/10.16965/ijpr.2018.168.

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Belaya, L. A., and I. M. Lavit. "Calculating stress intensity factor for high-velocity crack." Journal of Physics: Conference Series 1479 (March 2020): 012128. http://dx.doi.org/10.1088/1742-6596/1479/1/012128.

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Meerlo, Peter, Bertrand J. Pragt, and Serge Daan. "Social stress induces high intensity sleep in rats." Neuroscience Letters 225, no. 1 (March 1997): 41–44. http://dx.doi.org/10.1016/s0304-3940(97)00180-8.

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Xu, Qingzhong, Meihua Su, and Degang Hu. "CARDIOVASCULAR CONTROL RESPONSES IN HIGH INTENSITY EXERCISE STRESS TESTS." Revista Brasileira de Medicina do Esporte 27, no. 7 (July 2021): 678–81. http://dx.doi.org/10.1590/1517-8692202127072021_0355.

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ABSTRACT Introduction: High intensity exercise is an important factor to achieve the best exercise effect, and is closely related to the patient's safety and rehabilitation. Objective: To investigate the effects of high intensity exercise on cardiovascular response and substance and energy metabolism. Methods: 50 male students at a university were selected. The average age of the subjects was 23 years old. Process of the experiment: Before the experiment, each subject took routine warm-up activities first, then put on the experimental equipment and began to run 100 meters. At the same time, the subjects’ heart rate, blood oxygen parameters and exercise time were recorded. After passing the finish line, a period of heart rate recording and blood oxygen parameters were continued. Results: Anaerobic metabolism was the main activity in the 100m race. The first 7s after the start of the race, there is a non-lactic acid process without oxygen metabolism, and the muscle oxygen saturation curve presents little change. Conclusions: High intensity exercise in sports training and physical exercise can lead to reduced heart rate variability. The increased incidence of various arrhythmias should be based on the actual situation of the movement of the object, and a reasonable arrangement of exercise load intensity. Level of evidence II; Therapeutic studies - investigation of treatment results.

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Yan, Ming, Hao Chuan Li, and Lin Li. "Stress Intensity Factor of Thermal Fatigue Crack in High Temperature." Advanced Materials Research 581-582 (October 2012): 677–80. http://dx.doi.org/10.4028/www.scientific.net/amr.581-582.677.

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Stress intensity factor of thermal fatigue crack was calculated within one cycle by using finite element method in consideration of the multi-linear kinematic hardening characteristic of a material. The affection of loading sequence to stress intensity factor was studied under circularly variational temperature by comparing to that in one cycle. The low temperature cycle can not affect the stress intensity factor of latter cycles with high temperature; but high temperature cycle can affect the stress intensity factor of latter cycles with low temperature, and make it be equal to that of the high temperature cycle.

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Araujo, Nayara Costa, Anibal Monteiro Magalhães Neto, Mahmi Fujimori, Miguel Sordi Bortolini, Allisson Benatti Justino, Adenilda Cristina Honorio-França, and Eduardo Luzía França. "Immune and Hormonal Response to High-intensity Exercise During Orienteering." International Journal of Sports Medicine 40, no. 12 (August 14, 2019): 768–73. http://dx.doi.org/10.1055/a-0970-9064.

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AbstractOrienteering is an endurance sport that combines physical and cognitive activity, during which the athlete must complete a course with several points distributed over unknown terrain in the shortest possible time. A number of studies have investigated the body’s physiological adaptations to the stress caused during competition, but not the immunological changes. To that end, the present study evaluated the immunological, physiological and pathological responses in athletes performing high-intensity physical exercise during an orienteering race. The 30 athletes tested belonged to the elite orienteering category and participated in the regional championship. Cortisol levels were determined before and after the competition to assess stress response, as were the cytokines IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17 to evaluate the immune response. Cortisol levels increased after the competition, indicating a stress condition. IFN-γ, IL-6 and IL-10 levels also rose post competition. The results indicate that orienteers are exposed to high stress levels, and that this condition affects their immune and endocrine systems, triggering a predominantly anti-inflammatory response, likely an athlete’s mechanism of adaptation to the stress imposed by high-intensity physical exercise.

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Baker, Julien S., and Bruce Davies. "Evidence for Oxidative Stress Damage Following High Intensity Anaerobic Performance." Open Sports Medicine Journal 2, no. 1 (March 17, 2008): 9–13. http://dx.doi.org/10.2174/1874387000802010009.

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Dallas, J., T. Demchak, and J. Buckworth. "STRESS RESPONSE DURING HIGH INTENSITY TRAINING OF WOMEN'S COLLEGIATE CREW." Medicine & Science in Sports & Exercise 31, Supplement (May 1999): S217. http://dx.doi.org/10.1097/00005768-199905001-01011.

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Dernbach, A. R., W. M. Sherman, J. C. Simonsen, K. M. Flowers, and D. R. Lamb. "No evidence of oxidant stress during high-intensity rowing training." Journal of Applied Physiology 74, no. 5 (May 1, 1993): 2140–45. http://dx.doi.org/10.1152/jappl.1993.74.5.2140.

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In untrained subjects, strenuous exercise provokes the appearance of oxidant stress markers in blood and muscle. On the other hand, trained muscle is resistant to oxidant stress unless exercise challenges the muscle glycogen supply. It is not known whether chronic high-intensity exercise alters the susceptibility of skeletal muscle to oxidant stress, whether there are gender-related differences in markers of oxidant stress, or whether elevating muscle glycogen stores by increasing dietary carbohydrate can minimize any exercise-related oxidant stress. To address these issues, collegiate rowers (12 men, 11 women) were randomly assigned to a moderate-(MOD, 5 g/kg body wt) or high-carbohydrate (HI, 10 g/kg) diet in a double-blind design and underwent strenuous training for 4 wk. Training in the A.M. was 40 min at 70% maximal O2 consumption (VO2); in the P.M. it was either three 2,500-m time trials (to assess power output) or aerobic and lactate tolerance training. Total daily training time was 65 min at 70% maximal VO2 and 38 min at > or = 90% maximal VO2. Thrice-weekly morning blood samples were assayed for serum creatine kinase (CK), plasma thiobarbituric acid-reactive substances (TBARS), and serum beta-glucuronidase (beta-Gluc). Weekly muscle biopsies were obtained for analysis of glycogen and, when tissue sample quantity allowed, TBARS. HI rowers produced more power and improved power more (10.7 +/- 1.0 vs. 1.6 +/- 1.6%) over the 4 wk than did the MOD rowers. Preexercise muscle glycogen concentration was maintained at 119 mmol/kg in MOD but increased 65% in HI rowers (P < 0.05).

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Mackay, T. L., and B. J. Alperin. "Stress intensity factors for fatigue cracking in high-strength bolts." Engineering Fracture Mechanics 21, no. 2 (January 1985): 391–97. http://dx.doi.org/10.1016/0013-7944(85)90027-x.

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Gabriel, Brendan, Aivaras Ratkevicius, Patrick Gray, Michael P. Frenneaux, and Stuart R. Gray. "High-intensity exercise attenuates postprandial lipaemia and markers of oxidative stress." Clinical Science 123, no. 5 (May 16, 2012): 313–21. http://dx.doi.org/10.1042/cs20110600.

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Regular exercise can reduce the risk of CVD (cardiovascular disease). Although moderate-intensity exercise can attenuate postprandial TAG (triacylglycerol), high-intensity intermittent exercise might be a more effective method to improve health. We compared the effects of high-intensity intermittent exercise and 30 min of brisk walking on postprandial TAG, soluble adhesion molecules and markers of oxidative stress. Nine men each completed three 2-day trials. On day 1, subjects rested (control), walked briskly for 30 min (walking) or performed 5×30 s maximal sprints (high-intensity). On day 2, subjects consumed a high-fat meal for breakfast and 3 h later for lunch. Blood samples were taken at various times and analysed for TAG, glucose, insulin, ICAM-1 (intracellular adhesion molecule-1), VCAM-1 (vascular adhesion molecule-1), TBARS (thiobarbituric acid- reactive substances), protein carbonyls and β-hydroxybutyrate. On day 2 of the high-intensity trial, there was a lower (P<0.05) incremental TAG AUC (area under the curve; 6.42±2.24 mmol/l per 7 h) compared with the control trial (9.68±4.77 mmol/l per 7 h) with no differences during day 2 of the walking trial (8.98±2.84 mmol/l per 7 h). A trend (P=0.056) for a reduced total TAG AUC was also seen during the high-intensity trial (14.13±2.83 mmol/l per 7 h) compared with control (17.18±3.92 mmol/l per 7 h), walking showed no difference (16.33±3.51 mmol/l per 7 h). On day 2 of the high-intensity trial plasma TBARS and protein carbonyls were also reduced (P<0.05) when compared with the control and walking trials. In conclusion, high-intensity intermittent exercise attenuates postprandial TAG and markers of oxidative stress after the consumption of a high-fat meal.

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Morales, Serena, Joseph Stewart, Shelly Weise, and H. H. Huang. "High-intensity Interval Training Versus Moderate-intensity Interval Training: Anthropometrics, Inflammation, Stress Markers And Exercise Enjoyment." Medicine & Science in Sports & Exercise 55, no. 9S (September 2023): 684. http://dx.doi.org/10.1249/01.mss.0000986260.49124.7f.

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YAU, Chen Yi, Shu Chen SHEN, and Sandy HSIEH. "Effects of High-intensity Exercise and Fish Oil-induced Oxidative Stress." Asian Journal of Physical Education & Recreation 9, no. 2 (December 1, 2003): 89–96. http://dx.doi.org/10.24112/ajper.91134.

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LANGUAGE NOTE | Document text in Chinese; abstract also in English.High-intensity exercise may induce active oxygen free radicals higher. Fish oil, which is one of the CO-3 PUFA series that can decrease TG and influence plasma lipids, appears to prevent arteriosclerosis and CHD, but some evidence describe it increases the lipid peroxidation in the cell. Fish oil would then seem to influence the antioxidant defense system that causes damage or disease. This study investigates the effects on the antioxidant defence system of combining high-intensity exercise with fish oil supplementation. Methods: Thirty-three healthy males were randomly assigned into four groups (20.3±1.4 yrs; 64.3±7.9 kg), which were given set combinations of dietary fish oil (9 g per day), exercise (intensity 85-90 % HRmax reserve), and placebos. The experiment lasted 4 weeks in total. Venous samples were obtained prior to exercise and within 5 min after. 4 venous samples were also taken from fish oil groups during the four-week period. Blood from all groups was analyzed for sesuperoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total glutathione (T-GSH), total antioxidant ability (TAA), malodialdehyde (MDA). A Generalized Estimating Equations (G.E.E.) method was used for data analysis. Results: In the fish oil groups SOD activity significantly increased 11.27 kU/g-HB(P

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Ormsbee, Michael J., Amber W. Kinsey, Minwook Chong, Heather S. Friedman, Tonya Dodge, and Patricia C. Fehling. "Short-term High-intensity Interval Training and The Physiological Stress Response." Medicine & Science in Sports & Exercise 43, Suppl 1 (May 2011): 905–6. http://dx.doi.org/10.1249/01.mss.0000402530.52638.9b.

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Yu, Zhi Wei, Sheng Guo Cheng, and Zhao Rong Jiang. "Calculate the Stress Intensity Factor by ANSYS." Advanced Materials Research 838-841 (November 2013): 2250–53. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2250.

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Mode I crack for an example, this paper conducts the introduction and analysis of the use of finite element software ANSYS to calculate the stress intensity factor approaches. Compared the stress intensity factor values with the analytic solution, it shows that the finite element method to calculate the stress intensity factor has a very high precision, and easy to operate.

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Hardy, Charles J., and Robert G. McMerray. "A/B Types and Psychophysiological Responses to Exercise Stress." Journal of Sport and Exercise Psychology 11, no. 2 (June 1989): 141–51. http://dx.doi.org/10.1123/jsep.11.2.141.

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Ten Type A's and 10 Type B's, as measured by the student version of the JAS and the TASRI, exercised on a cycle ergometer for 20 minutes at light (40% V02max), moderate (60% V02max), and high (80% V02max) intensity exercise to determine A/B differences in psychophysiological responses. The norepinephrine and epinephrine responses of A/B types were similar at the light and moderate intensities. However, at the high intensity, norepmephrine response of Type A's was significantly greater than that of Type B's. Epinephrine responses (p=.ll) evidenced the same, albeit nonsignificant, trend. Oxygen uptake and heart rate data indicated that this amine difference was not a function of differential workloads, suggesting that Type A's had a greater psychophysiological reactivity to high intensity exercise than Type B's. Ratings of perceived exertion were similar for Type A's and B's at all intensities. However, a significant interaction between behavioral pattern and intensity emerged for affect. Interpretation of this interaction indicated that Type A's were more positive than B's at light and moderate intensities, yet at the high intensity exercise A's were more negative than B's. The results of this study suggest that A and B types do differ in their psychophysiological responses during exercise, with A's evidencing more positive affect during light and moderate intensities, yet more negative affect and greater neuroendocrine responses during high intensity exercise than B's.

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Rodrigues, Alesson, and Leonardo De Lucca. "Acute leptin response after high intensity interval and moderate intensity continuous runs." European Journal of Human Movement 45 (2020): 26–35. http://dx.doi.org/10.21134/eurjhm.2020.45.3.

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The possible direct role of exercise intensity and duration on leptin concentrations is conflicting. The aim of this study was to evaluate the acute effects of high intensity interval (HIIE) and moderate intensity continuous (MICE) exercise on plasma leptin response. Seven young volunteers underwent three tests: 1) a treadmill graded exercise test to identify running peak velocity (PV); 2) HIIE: 5 × 2 min work bouts at 90% of PV, interspersed by 2 min of passive recovery and; 3) MICE: 30 min at 70 % of PV. Blood samples were drawn for the assays of leptin before and 30 minutes after HIIE and MICE. A 2-way repeated measures ANOVA showed a significant main effect of time [F(1,6) =17,52; p=0,006], no significant effect of condition (type of exercise) (F(1,6) = 0,16; p = 0,68) and no significant interaction (condition × time) (F(1,6)= 0,48, p=0,51). Leptin decreased 30 min after HIIE (t= 2,95, p=0,025) and MICE (t=4,18; p=0,005). There was no difference between the HIIE and MICE conditions immediately after exercise (t=0,90; p=0,40). After HIIE and MICE, leptin decreased in the same magnitude. It appears that both exercise modalities result in physical stress which is sufficient to improve short-term leptin sensibility.

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Donato, Silvia, Miriam Parise, Ariela F. Pagani, Simona Sciara, Raffaella Iafrate, and Giuseppe Pantaleo. "The paradoxical influence of stress on the intensity of romantic feelings towards the partner." Interpersona: An International Journal on Personal Relationships 12, no. 2 (December 21, 2018): 215–31. http://dx.doi.org/10.5964/ijpr.v12i2.310.

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According to Brehm’s emotional intensity theory (EIT), the strength of feelings of romantic affect towards a romantic partner should vary as a cubic function of increasing levels of relationship stress (i.e., deterrence to feelings of romantic affect). The study tested this hypothesis in a true experiment with 80 young adults actually engaged in a romantic relationship, by systematically manipulating stress, through a recall procedure, across four distinct levels of intensity (control vs. low vs. moderate vs. high levels of manipulated stress). As predicted by emotional intensity theory, feelings of romantic affect were strong in the control condition, reduced in the low stress condition (low deterrence), maintained intense in the moderate stress condition (moderate deterrence), and reduced, again, in the high stress condition (high deterrence). Findings and both theoretical and practical implications for professionals and future research are discussed, with special emphasis on how to promote partners’ everyday adjustments to stress and emotional intensity regulation.

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Kharlamenkova, Nataliya E., and Dariya A. Nikitina. "PSYCHOLOGICAL CONSEQUENCES OF THE INFLUENCE OF HIGH-INTENSITY STRESSORS OF DIFFERENT TYPES." Yaroslavl Pedagogical Bulletin 116, no. 5 (2020): 110–20. http://dx.doi.org/10.20323/1813-145x-2020-5-116-110-120.

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The article is devoted to the study of delayed (post-traumatic) stress caused by different types of stressful situations (death of a loved one, life-threatening diseases, traffic accidents, situations of physical and emotional violence) during early adulthood, the analysis of specific psychological markers of its intensity. The study involved 509 people (232 men and 277 women) aged 17 to 35 years (Me = 21; SD = 4,3). Methods: Posttraumatic Stress Disorder Checklist (PCL-5) in the Russian-language adaptation by N. V. Tarabrina and co-authors for the diagnosis of stressful events and their psychological consequences; the list of stress situations contained in the Life Events Checklist (LEC-5) for DSM-5; the Symptom Check List-90-r-Revised (SCL-90-R) technique in the Russian-language adaptation by N. V. Tarabrina and co-authors was used to evaluate psychopathological symptoms. It has been shown that the most severe in intensity posttraumatic stress causes situations that pose a threat to the physical and psychological well-being of a person at the same time (violence and life-threatening disease). Taking into account the level of mental trauma and the type of stressor, an analysis of a number of features of psychopathological symptoms was carried out. The results of the study made it possible to identify markers of severe post-traumatic stress, which were indicators of violation of contact with reality, expressed in distancing a person from the surrounding reality, distrust of the world, suspicion, phobic anxiety.

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Bagheri, Rasool, Mohammad Reza Pourahmadi, Rozita Hedayati, Ziaeddin Safavi-Farokhi, Atefeh Aminian-far, Sadegh Tavakoli, and Jafar Bagheri. "Relationships Between Hoffman Reflex Parameters, Trait Stress, and Athletic Performance." Perceptual and Motor Skills 125, no. 4 (June 18, 2018): 749–68. http://dx.doi.org/10.1177/0031512518782562.

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This study evaluated the relationships between trait stress, Hoffman reflex, and performance among 36 healthy amateur male athletes. We first obtained a trait stress questionnaire from participants and then assigned them to high- and low-stress groups. We next recorded Hoffman reflex data from the soleus and lateral gastrocnemius muscles and then examined their athletic performance on testing protocols separated by a 72-hour washout period. Performance testing utilized vertical jump height, 20 -m sprint time, and standing stork tests. There were significant correlations between (a) the standing stork test, vertical jump height, and trait stress and (b) Hmax/ Mmax ratios, threshold intensity ( Hth), the intensity of the Hmax, and the intensity of the Hlast. Hth, the intensity of Hmax, and the intensity of Hlast were significantly higher among the low-stress compared with the high-stress participant groups ( p < .05), despite participants’ similar training history. We suggest that self-perceived psychological stress affects performance through neural adaptation.

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Du, HongYing, and Young-Je Sim. "Effect of changes in blood fatigue indicators, inflammatory markers, and stress hormone levels on 100-m records of sprinters following an 8-week intense interval training." Journal of Exercise Rehabilitation 17, no. 5 (October 26, 2021): 348–53. http://dx.doi.org/10.12965/jer.2142536.268.

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This study aimed to examine the changes in the blood fatigue indicators, inflammatory markers, and stress hormones following an 8-week intensity interval training in sprinters, and to investigate the effects on changes in the 100-m sprint records. Twenty sprinters from a boys’ high school were equally assigned to high-intensity and medium-intensity interval training groups, and three 60-min interval training sessions were performed per week for 8 weeks, for a total of 24 sessions. Exercise intensity was defined as 85%–95% and 75%–85% of heart rate reserve for high- and medium-intensity training, respectively. At rest, both groups had an exercise intensity of 60% of the heart rate reserve. Our results showed decreased fatigue indicators, inflammatory markers, and stress hormone levels after high-intensity and medium-intensity interval training, with no difference between the training levels. In addition, the 100-m sprint records were different in high- and medium-intensity interval training groups, based on the lactate dehydrogenase and adrenocorticotropic hormone levels. In conclusion, medium-intensity interval training with a reserve heart rate of ≥ 75% can have a positive effect on blood fatigue indicators, inflammatory markers, and stress hormones in sprinters. Specifically, the changes in adrenocorticotropic hormone level seen in the high-intensity interval training group were found to have a significant effect on the 100-m sprinting records.

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Par, Matej, Phoebe Burrer, Katica Prskalo, Saskia Schmid, Anna-Lena Schubiger, Danijela Marovic, Zrinka Tarle, Thomas Attin, and Tobias T. Tauböck. "Polymerization Kinetics and Development of Polymerization Shrinkage Stress in Rapid High-Intensity Light-Curing." Polymers 14, no. 16 (August 12, 2022): 3296. http://dx.doi.org/10.3390/polym14163296.

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This study investigated polymerization kinetics, linear shrinkage, and shrinkage stress development for six contemporary composite materials of different viscosities cured using radiant exitances of 1100–2850 mW/cm2. Real-time measurements of degree of conversion, linear shrinkage, and shrinkage stress were performed over 5 min using Fourier-transform infrared spectrometry, a custom-made linometer, and a custom-made stress analyzer, respectively. For most tested variables, the factor “material” had a higher effect size than the factor “curing protocol”. Maximum polymerization rate and maximum shrinkage stress rate were the most affected by changes in curing conditions. In contrast, no significant effects of curing conditions were identified within each material for shrinkage stress values measured at the end of the 5 min observation period. Linear shrinkage and shrinkage stress values measured after 5 min were closely correlated (R = 0.905–0.982). The analysis of polymerization kinetics suggested that the two composites specifically designed for rapid light-curing responded to higher radiant exitances differently than other composites. Polymerization kinetics and shrinkage stress behavior of contemporary restorative composite materials of different viscosities were overall more affected by material type than differences in curing conditions. Subtle differences in polymerization kinetics behavior shown by the two composites specifically designed for rapid high-intensity light-curing did not translate into significant differences in the development of polymerization shrinkage stress.

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Chalyi, O., M. Diaconescu, I. Gurova, Y. Lisovyi, P. Pigylevsky, S. Shcherbina, A. Shevtsov, and L. Shumlianska. "THE CAUSE OF HIGH INTENSITY OF SEISMICITY IN UKRAINE." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 4 (83) (2018): 38–45. http://dx.doi.org/10.17721/1728-2713.83.05.

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In the article, the earthquake near Sumy is considered in detail. According to the authors, this earthquake occurred under the influence of several stress regimes. At the regional level: it is related to the transfer of stresses from the Vrancea zone along the mantle lineament of Sollogub; a change in the local stress field, which is created by blocks with different thicknesses of the earth's crust, with the presence of subcrustal thermal anomalies. The area of the location of the earthquake focus near the town of Sumy in tectonic terms is on the southwestern slope of the Voronezh crystalline massif near the northeastern side of the Dnieper-Donets Basin (DDB). The epicenter is confined to the northern extension of the Krivyy-Rig-Kremenchug suture zone. The earthquake focus is confined to the tectonic node formed by the eastern edge fault of the Krivyy-Rig-Kremenchug suture zone and the northern side fracture of the DDB. The main deep faults near the source of the earthquake are the northern side fault of the DDB rift and the northern extension of the Krivyy Rig-Kremenchug fault. The hypocenter of the event is in the area with sharp change in the structural plan of the Moho surface accompanied by a negative mantle gravitational anomaly. In the relief of the Moho surface, a superimposition of the structural plan of the northwestern direction, connected with the Devonian rift of the DDV, on the ancient structural plan of the Ukrainian shield and Voronezh crystalline massive is clearly visible. Within the DDV, the isohypses of the Moho surface clearly delineate the ascent to ~ 35 km in the central part of the rift. The Krivyy-Rig-Kremenchug suture zone is expressed in the Moho surface by a narrow elongated depression with depths of more than 50 km in the central part. Here, in the lower part of the cortex, the development of the crust-mantle mixture is observed. The Krivyy-Rig-Kremenchug suture zone is also distinguished by the development of high-intensity deep magnetic inhomogeneities along it. In addition, here in the lower part of the crust and in the upper mantle a linear object of high electrical conductivity is isolated. Thus, the earth's crust of the region has a pronounced physic-geological heterogeneity, which creates instability of lithostatic stress, and this, in turn, is a prerequisite for the appearance of additional stresses.

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Hennion, V., J. M. Sprauel, and H. Michaud. "Contribution to residual-stress evaluation in high-stress-gradient zones by X-ray diffraction." Journal of Applied Crystallography 33, no. 1 (February 1, 2000): 26–34. http://dx.doi.org/10.1107/s0021889899010973.

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The non-destructive X-ray diffraction method is usually employed to evaluate stress states at the near surface of materials. In specific zones with high-stress gradients parallel to the surface, like welding joins, areas affected by lasers, or ball-bearing raceways, the classical measurement method is not particularly well suited, as the irradiation spot covers regions of varying stress according to its size. This leads to inaccurate stress evaluations. A new X-ray diffraction measurement and data treatment method is therefore proposed. It is based on longitudinal step-by-step scanning in a fixed direction of the surface. As the acquired data results from the convolution of local diffraction peaks with the incident-beam intensity, an accurate model of the true two-dimensional intensity distribution inside the spot has been developed. Firstly, the true shape and size of the irradiation area is defined. The distribution of the intensity received by the sample surface is then computed. The true local strains and stresses along the scanning direction are finally determined from the acquired peaks using an optimization through a least-squares fitting by a nonlinear function.

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Javed, Raja Ahsan, Shi Fan Zhu, and Feng Chun Jiang. "Importance of Material’s Dynamic Stress Intensity Factor Calculation in the Design of High Strenght Structures." International Journal of Engineering Research in Africa 15 (April 2015): 97–106. http://dx.doi.org/10.4028/www.scientific.net/jera.15.97.

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The researchers and scientists have concluded that material dynamic fracture properties must be considered during the design stage of the modern structure. The dynamic stress intensity factor is very important in understanding of material dynamic behavior. Keeping in view the importance of the materials dynamic stress intensity factor: an efficient and reliable numerical-analytical procedure is developed for calculation of dynamic stress intensity factor. For this, three-dimensional model of a Modified Hopkinson Pressure Bar (MHPB) and a specimen is modeled and analyzed with the ANSYS software. Transient dynamic analysis technique is used for simulation of load-variations as a function of time. As an output of analysis, values of load point displacement and Crack Mouth Opening Displacement (CMOD) are obtained. These values are substituted into two different analytical formulas for calculation of a dynamic stress intensity factor. The results obtained are compared with previous published results, and a good agreement is found.

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Wu, Di. "Numerical Study on the Bombardment Effects of Tungsten by High-Intensity Pulsed Ion Beam." Applied Mechanics and Materials 444-445 (October 2013): 1122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1122.

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In order to study the response of tungsten under high heat load, the nonlinear thermodynamic equations considering the phase transition were established to the tungsten target irradiated by intense pulsed ion beam. Also the equations which describe the thermal stress and the total strain produced by the changed temperature in the material element were built. Numerical method was used to solve the evolutions of the thermal stress field formed in the target, and spatial temporal evolutions of stress field in the tungsten target are obtained. While the ion current density reached 100A/cm2, the surface materials of tungsten target at the beam incident center was melted and then re-solidified due to the heat conduction after the end of a pulse. There exists the gradient of temperature in tungsten, therefore the thermal stress formed. Radial tensile stress is produced within the melting region, meanwhile outside the region compressive stress is formed; the boundary appears on the edge of the melting region. The stresses on the incidental surface of target are larger compared with the internal.

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Ostrom, Ethan L., Ana P. Valencia, David J. Marcinek, and Tinna Traustadóttir. "High intensity muscle stimulation activates a systemic Nrf2-mediated redox stress response." Free Radical Biology and Medicine 172 (August 2021): 82–89. http://dx.doi.org/10.1016/j.freeradbiomed.2021.05.039.

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29

Martikainen, Teemu, Fjola Sigurdardottir, Christian Benedict, Torbjørn Omland, and Jonathan Cedernaes. "Effects of curtailed sleep on cardiac stress biomarkers following high-intensity exercise." Molecular Metabolism 58 (April 2022): 101445. http://dx.doi.org/10.1016/j.molmet.2022.101445.

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Meade, Robert D., Naoto Fujii, Martin P. Poirier, Pierre Boulay, Ronald J. Sigal, and Glen P. Kenny. "Oxidative stress does not influence local sweat rate during high-intensity exercise." Experimental Physiology 103, no. 2 (December 20, 2017): 172–78. http://dx.doi.org/10.1113/ep086746.

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31

Rogers, Melissa M., Kimberly A. Hubing, Laura R. Quigg, John T. Bassett, Luke P. Quebedeaux, Robert M. Patrizi, Kristin L. Byrd, David E. Upton, Melody D. Phillips, and Joel B. Mitchell. "Fatigue During High Intensity Exercise: The Interaction Between pH and Thermal Stress." Medicine & Science in Sports & Exercise 40, Supplement (May 2008): S368. http://dx.doi.org/10.1249/01.mss.0000323473.88057.2c.

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32

Fisher, G., D. D. Schwartz, J. Quindry, M. D. Barberio, E. B. Foster, K. W. Jones, and D. D. Pascoe. "Lymphocyte enzymatic antioxidant responses to oxidative stress following high-intensity interval exercise." Journal of Applied Physiology 110, no. 3 (March 2011): 730–37. http://dx.doi.org/10.1152/japplphysiol.00575.2010.

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The purposes of this study were to 1) examine the immune and oxidative stress responses following high-intensity interval training (HIIT); 2) determine changes in antioxidant enzyme gene expression and enzyme activity in lymphocytes following HIIT; and 3) assess pre-HIIT, 3-h post-HIIT, and 24-h post-HIIT lymphocyte cell viability following hydrogen peroxide exposure in vitro. Eight recreationally active males completed three identical HIIT protocols. Blood samples were obtained at preexercise, immediately postexercise, 3 h postexercise, and 24 h postexercise. Total number of circulating leukocytes, lymphocytes, and neutrophils, as well as lymphocyte antioxidant enzyme activities, gene expression, cell viability (CV), and plasma thiobarbituric acid-reactive substance (TBARS) levels, were measured. Analytes were compared using a three (day) × four (time) ANOVA with repeated measures on both day and time. The a priori significance level for all analyses was P < 0.05. Significant increases in superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities were observed in lymphocytes following HIIT. No significant increases in lymphocyte SOD, CAT, or GPX gene expression were found. A significant increase in TBARS was found immediately post-HIIT on days 1 and 2. Lymphocyte CV in vitro significantly increased on days 2 and 3 compared with day 1. Additionally, there was a significant decrease in CV at 3 h compared with pre- and 24 h postexercise. These findings indicate lymphocytes respond to oxidative stress by increasing antioxidant enzyme activity. Additionally, HIIT causes oxidative stress but did not induce a significant postexercise lymphocytopenia. Analyses in vitro suggest that lymphocytes may become more resistant to subsequent episodes of oxidative stress. Furthermore, the analysis in vitro confirms that lymphocytes are more vulnerable to cytotoxic molecules during recovery from exercise.

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NOGUCHI, Toshio, and Tsutomu EZUMI. "Examination of Dynamic Stress Intensity Factor of Polycarbonate under High Temperature Environment." Proceedings of Yamanashi District Conference 2002 (2002): 25–26. http://dx.doi.org/10.1299/jsmeyamanashi.2002.25.

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Gao, Zhiwen, and Youhe Zhou. "Dynamic stress intensity factors of mode-I crack in high temperature superconductor." Physica C: Superconductivity 495 (December 2013): 169–73. http://dx.doi.org/10.1016/j.physc.2013.09.013.

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35

Kellmann, M. "Preventing overtraining in athletes in high-intensity sports and stress/recovery monitoring." Scandinavian Journal of Medicine & Science in Sports 20 (September 14, 2010): 95–102. http://dx.doi.org/10.1111/j.1600-0838.2010.01192.x.

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36

Khandelwal, Nita, Peter May, and J. Randall Curtis. "Financial stress after critical illness: an unintended consequence of high-intensity care." Intensive Care Medicine 46, no. 1 (September 23, 2019): 107–9. http://dx.doi.org/10.1007/s00134-019-05781-0.

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Hsieh, S. T., J. R. Lymangrover, W. P. Dunlap, D. Majeau-Chargois, C. F. Walker, and Y. J. Seto. "High-intensity electric field induced mild stress response in animal organ weights." Bioelectrochemistry and Bioenergetics 14, no. 1-3 (November 1985): 45–56. http://dx.doi.org/10.1016/0302-4598(85)85006-6.

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38

Kudra, T., I. Niewczas, B. Szot, and G. S. V. Raghavan. "Stress Cracking During High-Intensity Drying and its Effect on Grain Quality." Drying Technology 14, no. 2 (January 1996): 367–80. http://dx.doi.org/10.1080/07373939608917102.

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Batacan, Romeo B., Mitch J. Duncan, Vincent J. Dalbo, Kylie J. Connolly, and Andrew S. Fenning. "Light-intensity and high-intensity interval training improve cardiometabolic health in rats." Applied Physiology, Nutrition, and Metabolism 41, no. 9 (September 2016): 945–52. http://dx.doi.org/10.1139/apnm-2016-0037.

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Physical activity has the potential to reduce cardiometabolic risk factors but evaluation of different intensities of physical activity and the mechanisms behind their health effects still need to be fully established. This study examined the effects of sedentary behaviour, light-intensity training, and high-intensity interval training on biometric indices, glucose and lipid metabolism, inflammatory and oxidative stress markers, and vascular and cardiac function in adult rats. Rats (12 weeks old) were randomly assigned to 1 of 4 groups: control (CTL; no exercise), sedentary (SED; no exercise and housed in small cages to reduce activity), light-intensity trained (LIT; four 30-min exercise bouts/day at 8 m/min separated by 2-h rest period, 5 days/week), and high-intensity interval trained (HIIT, four 2.5-min work bouts/day at 50 m/min separated by 3-min rest periods, 5 days/week). After 12 weeks of intervention, SED had greater visceral fat accumulation (p < 0.01) and slower cardiac conduction (p = 0.04) compared with the CTL group. LIT and HIIT demonstrated beneficial changes in body weight, visceral and epididymal fat weight, glucose regulation, low-density lipoprotein cholesterol, total cholesterol, and mesenteric vessel contractile response compared with the CTL group (p < 0.05). LIT had significant improvements in insulin sensitivity and cardiac conduction compared with the CTL and SED groups whilst HIIT had significant improvements in systolic blood pressure and endothelium-independent vasodilation to aorta and mesenteric artery compared with the CTL group (p < 0.05). LIT and HIIT induce health benefits by improving traditional cardiometabolic risk factors. LIT improves cardiac health while HIIT promotes improvements in vascular health.

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Anna, Barczak-Brzyżek, Brzyżek Grzegorz, Koter Marek, Gawroński Piotr, and Filipecki Marcin. "Exposure to High-Intensity Light Systemically Induces Micro-Transcriptomic Changes in Arabidopsis thaliana Roots." International Journal of Molecular Sciences 20, no. 20 (October 16, 2019): 5131. http://dx.doi.org/10.3390/ijms20205131.

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In full sunlight, plants often experience a light intensity exceeding their photosynthetic capacity and causing the activation of a set of photoprotective mechanisms. Numerous reports have explained, on the molecular level, how plants cope with light stress locally in photosynthesizing leaves; however, the response of below-ground organs to above-ground perceived light stress is still largely unknown. Since small RNAs are potent integrators of multiple processes including stress responses, here, we focus on changes in the expression of root miRNAs upon high-intensity-light (HL) stress. To achieve this, we used Arabidopsis thaliana plants growing in hydroponic conditions. The expression of several genes that are known as markers of redox changes was examined over time, with the results showing that typical HL stress signals spread to the below-ground organs. Additionally, micro-transcriptomic analysis of systemically stressed roots revealed a relatively limited reaction, with only 17 up-regulated and five down-regulated miRNAs. The differential expression of candidates was confirmed by RT-qPCR. Interestingly, the detected differences in miRNA abundance disappeared when the roots were separated from the shoots before HL treatment. Thus, our results show that the light stress signal is induced in rosettes and travels through the plant to affect root miRNA levels. Although the mechanism of this regulation is unknown, the engagement of miRNA may create a regulatory platform orchestrating adaptive responses to various simultaneous stresses. Consequently, further research on systemically HL-regulated miRNAs and their respective targets has the potential to identify attractive sequences for engineering stress tolerance in plants.

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Simanjuntak, Armanto P., and Jae-Young Lee. "Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel." Energies 13, no. 18 (September 10, 2020): 4711. http://dx.doi.org/10.3390/en13184711.

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Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

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Jiang, Zhuanzhuan, Li Zhu, Qiuyu Wang, and Xin Hou. "Autophagy-Related 2 Regulates Chlorophyll Degradation under Abiotic Stress Conditions in Arabidopsis." International Journal of Molecular Sciences 21, no. 12 (June 25, 2020): 4515. http://dx.doi.org/10.3390/ijms21124515.

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Chloroplasts are extraordinary organelles for photosynthesis and nutrient storage in plants. During leaf senescence or under stress conditions, damaged chloroplasts are degraded and provide nutrients for developing organs. Autophagy is a high-throughput degradation pathway for intracellular material turnover in eukaryotes. Along with chloroplast degradation, chlorophyll, an important component of the photosynthetic machine, is also degraded. However, the chlorophyll degradation pathways under high light intensity and high temperature stress are not well known. Here, we identified and characterized a novel Arabidopsis mutant, sl2 (seedling lethal 2), showing defective chloroplast development and accelerated chlorophyll degradation. Map-based cloning combined with high-throughput sequencing analysis revealed that a 118.6 kb deletion region was associated with the phenotype of the mutant. Complementary experiments confirmed that the loss of function of ATG2 was responsible for accelerating chlorophyll degradation in sl2 mutants. Furthermore, we analyzed chlorophyll degradation under abiotic stress conditions and found that both chloroplast vesiculation and autophagy take part in chlorophyll degradation under high light intensity and high temperature stress. These results enhanced our understanding of chlorophyll degradation under high light intensity and high temperature stress.

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Kim, K. S. "A Stress Intensity Factor Tracer." Journal of Applied Mechanics 52, no. 2 (June 1, 1985): 291–97. http://dx.doi.org/10.1115/1.3169043.

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A new optical method, Stress Intensity Factor Tracer (SIFT), has been developed. The device measures continuously the real-time stress intensity factor variation, K1(t), of a moving crack tip using a single, stationary photodetector. The method uses the fact that any variation in K1(t) leads to a change in the intensity of light, I(t), impinging on a fixed finite area, Γ, on the focal plane. The focal plane is defined as the plane on which initially parallel light rays transmitted through a transparent fracture specimen (or reflected from the surface of an opaque specimen) are focused by a converging lens. Provided that the light detecting area, Γ, excludes the focal point, a simple relation, I(t) =B[K1(t)]4/3, has been obtained for a K1-dominant field. The constant, B, is a product of several experimental parameters including a “shape factor” of the sampling area, Γ, where I(t) is measured. A significant feature of this method is that I(t) is independent of the location of the crack tip in the illuminated zone on the specimen plane. The technique may therefore be applied to dynamic fracture studies without using high-speed photography. Only the constant, B, becomes a function of crack velocity for the dynamic K1-field. This paper presents the theoretical development of the SIFT method, including the wave optics of the system. Experimental results supporting the theory are included.

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Kurimay, Dora, Alison Pope-Rhodius, and Miran Kondric. "The Relationship Between Stress and Coping in Table Tennis." Journal of Human Kinetics 55, no. 1 (January 1, 2017): 75–81. http://dx.doi.org/10.1515/hukin-2017-0007.

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Abstract The aim of this study was to examine the relationship between cognitive competitive anxiety intensity and coping strategies in table tennis players. One hundred and two (102) US competitive table tennis players of age range from 10 to 60 filled out a Revised Competitive State Anxiety Inventory-2 (CSAI-2R, Cox et al., 2003) at least 30 minutes before the start of their tournament match and a Modified Cope questionnaire (MCOPE; Crocker and Graham, 1995) 15 minutes after they finished their match. Our study found significant differences between low and high cognitive competitive anxiety groups with regard to the use of coping strategies. The high cognitive competitive anxiety intensity group used significantly more behavioral disengagement (avoidance coping, p ≤ 0.05), denial coping strategies (emotion focused coping, p ≤ 0.01) compared to the low cognitive anxiety intensity group. Our results suggest that there is some connection between anxiety intensity and coping strategies. If the cognitive anxiety intensity (for example, intensity from worrying) is very high, an athlete might be more likely to use avoidance coping (such as behavioral disengagement) and emotion-focused coping (such as denial and venting of emotions) compared to athletes who have low cognitive competitive anxiety. Furthermore, gender differences in cognitive anxiety and direction were found. Confidence management techniques such as positive self-talk, breathing techniques and visualization should be taught to athletes to assist them in coping with their competitive anxiety better and to enhance their performance.

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Qi, Hong Yu, and Peng Chao Guo. "Stress Intensity Factors for High Aspect Ratio Semi-Elliptical External Surface Cracks in Cylindrical Vessels." Advanced Materials Research 986-987 (July 2014): 882–86. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.882.

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External surface cracks can occur in cylindrical vessels due to damage and propagate in the manufacturing process and during service life. Most of research focuses on stress intensity factors for surface cracks with low aspect ratios, i.e., a/c ≤1.0. Situation may well arise where the aspect ratio of cracks is larger than one. An external longitudinal surface crack is assumed to be subjected to different types of hoop stress distributions acting perpendicular to the crack faces. The stress intensity factors (SIFs) along the crack front were determined through the three-dimensional finite element method. Then these results are used to compute approximate values of SIFs in the case of complex loadings by employing both the superposition principle and the power series expansions of the actual hoop stresses. It is found that the maximum stress intensity factor for external surface cracks with high aspect ratio occurs at different point to that with low aspect ratio.

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Weller, A. S., C. E. Millard, M. A. Stroud, P. L. Greenhaff, and I. A. Macdonald. "Physiological responses to cold stress during prolonged intermittent low- and high-intensity walking." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 272, no. 6 (June 1, 1997): R2025—R2033. http://dx.doi.org/10.1152/ajpregu.1997.272.6.r2025.

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In a previous study [Am. J. Physiol. 272 (Regulatory Integrative Comp. Physiol. 41): R226-R233, 1997], the physiological responses to 240 min of intermittent low-intensity walking exercise in a cold (+5 degrees C), wet, and windy environment (Cold) may have been influenced by a 120-min preceding phase of intermittent higher-intensity exercise. Furthermore, the physiological responses observed during this latter phase may have been different if it had been more prolonged. To address these questions, active men attempted a 360-min intermittent (15 min of rest, 45 min of exercise) exercise protocol in Cold and a thermoneutral environment (+15 degrees C, Neutral) at a low (0% grade, 5 km/h; Low; n = 14) and a higher (10% grade, 6 km/h; High; n = 10) intensity. During Low, rectal temperature was lower in Cold than in Neutral, whereas O2 consumption, carbohydrate oxidation, plasma norepinephrine and epinephrine, and blood lactate were higher. During High, Cold had a similar but less marked influence on the thermoregulatory responses to exercise than during Low. In conclusion, the physiological responses to Low are similarly influenced by Cold whether or not they are preceded by High. Furthermore, during intermittent exercise up to an intensity of approximately 60% of peak O2 consumption, a cold, wet, and windy environment will influence the physiological responses to exercise and potentially impair performance.

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Zhou, Zhanyi, Chaoyi Chen, Ee-Chon Teo, Yan Zhang, Jialu Huang, Yining Xu, and Yaodong Gu. "Intracellular Oxidative Stress Induced by Physical Exercise in Adults: Systematic Review and Meta-Analysis." Antioxidants 11, no. 9 (September 4, 2022): 1751. http://dx.doi.org/10.3390/antiox11091751.

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A physical exercise program is one of the commonly used methods for improving an individual’s antioxidative capacity. However, an inappropriate physical exercise program would induce extra oxidative stress (OS), and the relationship between the details of a physical exercise protocol and the severity of intracellular OS is still unclear. A systematic review and meta-analysis of randomized controlled trials were conducted by searching PubMed, Medline, and Web of Science with the eligibility criteria: (1) participants over 18 years old; (2) physical exercise interventions; (3) 8-hydroxydeoxyguanosine, F2-isoprostanes, and protein carbonyls (PCs) as outcome measures; (4) published in English and peer-reviewed. 12 studies were included, and the data of 8 in them were pooled together. The agreement between authors reached a kappa value of 0.73. The results of the meta-analysis showed that: (1) the level of OS did not depend on the absolute intensity of physical exercise but on both the intensity and the volume of exercise; (2) high-intensity aerobic exercise (HIAE) and a combined protocol of HIAE and resistance training had the highest potential to induce large OS in unhealthy people; (3) the OS induced by moderate-to-high intensity aerobic exercise was significantly larger than that induced by ordinary life activities in healthy adults; (4) high-intensity interval training and moderate-intensity aerobic exercise had the lowest and sub-lowest probabilities to induce high intracellular OS for unhealthy adults. activities induce OS in various tissues in the human body, and the severity of OS depends on many factors of physical exercises as well as the health condition of an individual. A high-intensity and high-volume physical exercise program has the largest possibility of inducing severe OS, while a moderate-intensity aerobic exercise program and a high-intensity interval training program with a relatively low volume might be beneficial to the redox balance for unhealthy individuals. In conclusion, continuous aerobic exercise under moderate-intensity or high-intensity interval training could be recommended to enhance the body’s capacity for maintaining redox balance, especially for unhealthy individuals. The PROSPERO Registration Number is CRD42022349687.

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Bourdier, Guillaume, Patrice Flore, Hervé Sanchez, Jean-Louis Pepin, Elise Belaidi, and Claire Arnaud. "High-intensity training reduces intermittent hypoxia-induced ER stress and myocardial infarct size." American Journal of Physiology-Heart and Circulatory Physiology 310, no. 2 (January 15, 2016): H279—H289. http://dx.doi.org/10.1152/ajpheart.00448.2015.

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Chronic intermittent hypoxia (IH) is described as the major detrimental factor leading to cardiovascular morbimortality in obstructive sleep apnea (OSA) patients. OSA patients exhibit increased infarct size after a myocardial event, and previous animal studies have shown that chronic IH could be the main mechanism. Endoplasmic reticulum (ER) stress plays a major role in the pathophysiology of cardiovascular disease. High-intensity training (HIT) exerts beneficial effects on the cardiovascular system. Thus, we hypothesized that HIT could prevent IH-induced ER stress and the increase in infarct size. Male Wistar rats were exposed to 21 days of IH (21-5% fraction of inspired O2, 60-s cycle, 8 h/day) or normoxia. After 1 wk of IH alone, rats were submitted daily to both IH and HIT (2 × 24 min, 15-30m/min). Rat hearts were either rapidly frozen to evaluate ER stress by Western blot analysis or submitted to an ischemia-reperfusion protocol ex vivo (30 min of global ischemia/120 min of reperfusion). IH induced cardiac proapoptotic ER stress, characterized by increased expression of glucose-regulated protein kinase 78, phosphorylated protein kinase-like ER kinase, activating transcription factor 4, and C/EBP homologous protein. IH-induced myocardial apoptosis was confirmed by increased expression of cleaved caspase-3. These IH-associated proapoptotic alterations were associated with a significant increase in infarct size (35.4 ± 3.2% vs. 22.7 ± 1.7% of ventricles in IH + sedenary and normoxia + sedentary groups, respectively, P < 0.05). HIT prevented both the IH-induced proapoptotic ER stress and increased myocardial infarct size (28.8 ± 3.9% and 21.0 ± 5.1% in IH + HIT and normoxia + HIT groups, respectively, P = 0.28). In conclusion, these findings suggest that HIT could represent a preventive strategy to limit IH-induced myocardial ischemia-reperfusion damages in OSA patients.

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Xiao, Linfa, Heng Lin, Yongxiang Wang, Yiming Yang, and Huapeng Chen. "Numerical Investigation of Fatigue Crack Propagation Behaviour of 550E High-Performance Steel." Metals 13, no. 8 (August 21, 2023): 1496. http://dx.doi.org/10.3390/met13081496.

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The fatigue crack propagation behaviour of Q550E high-performance steel (HPS) is studied in this paper. Static tensile testing and fatigue crack propagation testing were carried out, and the results were compared with those of Q235. Finite element models were developed and verified against the experimental results. The impacts of the initial crack angle, crack depth ratio, stress ratio, thickness, and corrosion pitting on the fatigue crack propagation behaviour of the HPS were analysed. The results show that the fatigue life of Q550 was reduced by 18% due to the corrosion pitting, but it did not change the crack propagation path. When the stress intensity factor is higher than a certain value, the fatigue performance of Q235 is better than that of Q550E. The initial crack angle of 52.5° is the critical angle of the crack stress intensity factor. The steel tends to fracture as the crack depth ratio increases, and more attention should be paid to the effective crack length in engineering practice. An increasing stress ratio leads to a smaller stress intensity factor, and the thickness affects the stress intensity factor in the later stage. The crack stress intensity factor around the corrosion pits gradually decreases along the thickness direction, and the crack tips around the corrosion pits tend to reach the yield state initially, accelerating the fatigue fracture of the specimen and ultimately leading to a decrease in fatigue life.

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Porpiglia, Ermelinda, Daniel Hidalgo, and Merav Socolovsky. "Digital and Analog Modes of Stat5 Signaling Regulate Basal and Stress Erythropoiesis." Blood 116, no. 21 (November 19, 2010): 4766. http://dx.doi.org/10.1182/blood.v116.21.4766.4766.

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Abstract Abstract 4766 Erythropoietin concentration in serum spans three orders of magnitude as it regulates erythropoietic rates in basal and stress erythropoiesis. It is not clear how Epo concentration is encoded intracellularly to generate the required erythropoietic rate. Stat5 activation by the Epo receptor (EpoR) is required for both basal and stress erythropoiesis. We asked whether dynamic properties of Stat5 signaling, namely the manner in which the Stat5 signal intensity varies with time or with Epo concentration, might somehow encode downstream responses. To this end, we studied the Stat5 signaling response quantitatively in freshly-isolated single cells in mouse erythropoietic tissue, by flow cytometry. Using wild type mice, as well as mutant EpoR-HM mice expressing a truncated EpoR that lacks cytoplasmic domain tyrosines, we identified two modes of Stat5 signaling, digital and analog, which are specifically required for basal and stress erythropoiesis, respectively. We found that expression levels of the Stat5 protein are key in shaping the Stat5 signal. Early erythroblasts, ‘S1’ (Subset 1) cells, express high levels of of Stat5, and are able to respond to high Epo with a high intensity graded, or analog, signal. By contrast, mature erythroblasts, labeled ‘S3’ (Subset 3), express lower Stat5 levels, and their response to Epo is limited to a low intensity signal. We found that this low –intensity response is nevertheless decisive, responding to an Epo stimulus with a binary (or digital) ‘on’ or ‘off’ signal. The digital character of this low-intensity signal can be measured quantitatively: we found that its reposnse to increasing levels of Epo may be fitted by a Hill curve with a high Hill coefficient, similar in magnitude to that found for the cooperative binding of oxygen to hemoglobin. Mechanistically, the digital, low-intensity Stat5 signal is due to bistable Stat5 activation, in turn a result of a positive feedback interaction whereby phosphorylated Stat5 promotes further Stat5 phosphorylation. Following bistable activation, however, and in the presence of high Stat5 expression, Stat5 activation can increase further in a graded fashion, in response to increasing Epo levels. In mature S3 erythroblasts, however, in the absence of high Stat5 levels, no further increase in the signal occurs, giving rise to a digital behavior. Stat5 activation is therefore analogous to that of a dimmer light switch: a toggle-mechanism controls an initial bistable activation, giving rise to a low-level light signal; further graded rotation of a dial lower the circuit's resistance and gives rise to a graded increase in light intensity (Figure 1). We found that the EpoR-HM erythroblasts lost the ability to signal via the analog Stat5 signaling mode, but retained digital signaling. By comparing genetic models that either completely lack Stat5 function (the Stat5-/- mouse), or that specifically lack the graded, high intensity signal (the EpoR-HM mouse), we found that the digital, low-intensity signal was both necessary and sufficient for erythroblast survival and for maintenance of basal erythropoiesis. By contrast, the high intensity analog p-Stat5 signal was required for the response to erythropoietic stress, as seen from the inability of EpoR-HM mice to respond to stress. Further, we identified a specific gene target of analog Stat5 signaling during stress. We found that the stress-dependent upregulation of CD71 in early erythroblasts was absent in EpoR-HM. By exogenously expressing high levels of Stat5 in EpoR-HM erythroblasts in vitro, we were able to rescue both the analog high-intensity Stat5 signal in these cells, as well as their ability to express high CD71 in response to stress levels of Epo. We propose that the combined bistable and graded Stat5 signaling responses in early erythroblasts has evolved in order to generate a high fidelity response to Epo over its broad concentration range in basal and stress erythropoiesis. Digital low-intensity signaling transduces a clear signal in response to low-levels of Epo; whereas the ability to respond to higher levels of Epo with a graded, high intensity signal, is retained. This work was funded by NIH/NHLBI RO1 HL084168 and by American Cancer SocietyFigure 1:Stat5 activation in response to low, basal Epo is through a bistable switch that generates a low intensity signal. A further increase in Epo results in a graded increase in signal, but only in cells that express high Stat5.Figure 1:. Stat5 activation in response to low, basal Epo is through a bistable switch that generates a low intensity signal. A further increase in Epo results in a graded increase in signal, but only in cells that express high Stat5. Disclosures: No relevant conflicts of interest to declare.

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